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82,391	<p>I was thinking of a situation with humans finding a solar system, in which entropy decreases over time instead of increasing over time. In this solar system heat would flow from a cooler planet to the hotter star. Shattered rocks sometimes spontaneously unshatter before rising back to the top of a cliff. Sand will sometimes spontaneously fill a crater before a meteor rises up and goes into interplanetary space. </p> <p>Could humans colonize some of the planets of this solar system?</p>	[ { "answer_id": 82396, "author": "a4android", "author_id": 22159, "author_profile": "https://worldbuilding.stackexchange.com/users/22159", "pm_score": 2, "selected": false, "text": "<p>No. It would be too dangerous. The danger doesn't arise from coping with dual causality situations on an...	2017/06/01	[ "https://worldbuilding.stackexchange.com/questions/82391", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/13661/" ]	I was thinking of a situation with humans finding a solar system, in which entropy decreases over time instead of increasing over time. In this solar system heat would flow from a cooler planet to the hotter star. Shattered rocks sometimes spontaneously unshatter before rising back to the top of a cliff. Sand will sometimes spontaneously fill a crater before a meteor rises up and goes into interplanetary space. Could humans colonize some of the planets of this solar system?	No. It would be too dangerous. The danger doesn't arise from coping with dual causality situations on any of the planets. Matter existing backwards in time is [antimatter](https://en.wikipedia.org/wiki/CPT_symmetry). As everybody knows when matter and antimatter meet a lot of gamma radiation happens very quickly. This will be fatal. Potential colonists will soon be dispersed in the form of rapidly expanding plasma accompanied by large amounts of gamma radiation. This means colonization will be impossible. There is a good chance no-one will realize the solar system is a place where time flows backwards because all the matter in this solar system will be antimatter. It will be classified as an antimatter solar system. ADDENDUM: The relationship between antimatter and time reversal is established by a derivation of the CPT Theorem. (Vide the Wikipedia entry linked above.) > > This defines a CPT transformation if we adopt the Feynman-Stueckelberg > interpretation of antiparticles as the corresponding particles > traveling backwards in time. This interpretation requires a slight > analytic continuation, which is well-defined only under the following > assumptions: > > > > ``` > The theory is Lorentz invariant; > The vacuum is Lorentz invariant; > The energy is bounded below. > > ``` > > In words, matter moving backwards in time will be antimatter. Therefore, if there is a solar system where time flows backwards its matter will be antimatter.
83,724	<p>Earth is protected by a magnetic field. Not only does it shield life from solar radiation, it also guides animals to their migratory grounds. But here's the thing, according to Universe Today:</p> <blockquote> <p>The core probably accounts to 42% of Mercury’s volume, while Earth is just 17%.</p> </blockquote> <p>So let's say we have found an alternate Earth in an alternate universe where Earth's core makes up 42% of its volume rather than the 17% ours has. Would this larger volume of core give Earth a far stronger magnetic field?</p>	[ { "answer_id": 83726, "author": "ventsyv", "author_id": 10293, "author_profile": "https://worldbuilding.stackexchange.com/users/10293", "pm_score": 2, "selected": false, "text": "<p>First off, Mercury is much smaller than Earth (2400km vs 6300km radius), if you compare the cores without ...	2017/06/15	[ "https://worldbuilding.stackexchange.com/questions/83724", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/10274/" ]	Earth is protected by a magnetic field. Not only does it shield life from solar radiation, it also guides animals to their migratory grounds. But here's the thing, according to Universe Today: > > The core probably accounts to 42% of Mercury’s volume, while Earth is just 17%. > > > So let's say we have found an alternate Earth in an alternate universe where Earth's core makes up 42% of its volume rather than the 17% ours has. Would this larger volume of core give Earth a far stronger magnetic field?	First off, Mercury is much smaller than Earth (2400km vs 6300km radius), if you compare the cores without taking into account the rest of the planet you'll find that they are of similar size: ``` 2400 * 42% = 1008km 6300 * 17% = 1071km ``` I think what that means is that the rest of Mercury simply eroded away. But let's say we have a planet with radius of 6300km and core radius of 2600km (42% of the total radius). What would the effects be? That depends on what we mean by core. Here is what the Earth's structure looks like: [![enter image description here](https://i.stack.imgur.com/Clga4.gif)](https://i.stack.imgur.com/Clga4.gif) The coresponding densities can be found here: <http://hyperphysics.phy-astr.gsu.edu/hbase/Geophys/earthstruct.html> Density grows with depth and you want the total radius to stay the same, so depending on which layers you grow you'll get different effects. Growing the denser layers will give you an increase in average density, therefore you'll end up with higher gravity. More iron in the core will also lead to stronger magnetic field. Those are the two most obvious effects that I can think off.
83,825	<p>The time: January 27th, 2017, 7:00 AM local. The place: New York City and environs.</p> <p><a href="https://worldbuilding.stackexchange.com/q/37248/75">Jormungandr, the Snakebot of Doom</a>, has just finished steamrolling New York City into something more closely resembling a gravel driveway.</p> <p>Now it has returned to the vicinity of lower Manhattan and is busy extracting any iron or steel that it can find in the rubble in order to convert it into steel railgun ammunition. </p> <p>It is currently firing the six large railguns in its tail, each shot containing about 6.8 metric tons of steel, at a combined rate of 4 rounds per second. If it has to use its small railguns for self defence, they won't add significantly to the rate at which steel is being consumed.</p> <p>Jormungandr's mouth is currently ingesting any iron or steel it can find in the rubble in order to resupply its ammunition bunkerage. It is easily able to resupply its ammunition faster than it can expend it provided sufficient steel is nearby.</p> <p>How long would the steel found in New York City and environs be able to supply Jormungandr's appetite before it has to move on to another source of steel?</p> <p>Consider this to be the real world, with the exception that over the evening of the 26th until the morning of the 27th, New York has been experiencing severe blizzard conditions, leading to closure of ports, airports and roads.</p> <p>At the time in question, neither roads, ports or airports have yet reopened.</p> <p>The blizzard will mean that there are more ships in the ports adjacent to NYC than usual, and that cars cannot readily leave.</p> <p>By New York City and environs, I mean the area with this definition: <a href="https://drive.google.com/open?id=1piz-lZJ_ti3EAnEH7b_LNgIguiQ&usp=sharing" rel="noreferrer">https://drive.google.com/open?id=1piz-lZJ_ti3EAnEH7b_LNgIguiQ&usp=sharing</a></p> <p>Please account for the quantities of any man-made iron or steel within the area, no matter how large, including any vehicles, shipping, building structural members, railway track, rolling stock and tunnel shoring or lining, with a reasonable justification. The exact amount of steel in each building need not be accounted for.</p> <p>Small objects such as nails or bolts, unless part of a larger steel structure, may be discounted, as Jormungandr will not bother with anything so trivial. This will rule out its being interested in scavenging from wooden-framed dwellings, but steel framed dwellings are another matter.</p> <p><strong>EDIT</strong></p> <p>The world in this question <em>starts out</em> pretty much as the world with which we are familiar. However, the question is, <em>How long can Jormungandr stay here before it needs to move on to another source of steel</em>, and the world being built is one where <em>Jormungandr stayed for</em> x <em>time, firing continuously, then had to leave to find more steel</em>. <em>That</em> world may or may not resemble our own so much, depending upon the magnitude of x.</p> <p>I want to know X. Can it stay for Hours? Days? Weeks? Months? Years? How many of them?</p> <p>If Jormungandr stays for 'hours', then the world will be considerably different than if it stays for 'weeks'. <em>Hours</em> means that all that many of the survivors of NYC have to do is sit tight and wait for relief efforts to come to them. <em>Weeks</em> means that the survivors have to become refugees and travel to somewhere where they can get the necessities of life, since Jormungandr isn't going to leave much in the way of the necessities of life for the survivors to use, and how many relief agencies are going to risk coming close to a thing that destroyed US armed forces sent against it so easily?</p> <p>The longer Jormungandr stays put, the more time humans will have to try to come up with unconventional means to try to destroy it. The longer it stays put, the more likely that humans will discover that <a href="https://worldbuilding.stackexchange.com/q/79261/75">the birds have been bugged</a> before it moves on. The longer it stays put, the more likely it is that some idiot may try a massed submarine ICBM launch against it.</p> <p>So, while, yes, this <em>is</em> a question about a story set in a world, the world-building aspect of the question is that <em>the answer affects how the world changes</em>. Please don't think that just because the question is basically "how much steel is there in NYC, and then divide by 27.2 metric tons per second" that there aren't <em>other</em> implications that will greatly affect that initial, known, world.</p>	[ { "answer_id": 84518, "author": "Sasha", "author_id": 38408, "author_profile": "https://worldbuilding.stackexchange.com/users/38408", "pm_score": 5, "selected": true, "text": "<p>Right, this will be a very rough estimation since I'm not an engineer. </p>\n\n<p>First and foremost cars. </...	2017/06/17	[ "https://worldbuilding.stackexchange.com/questions/83825", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/75/" ]	The time: January 27th, 2017, 7:00 AM local. The place: New York City and environs. [Jormungandr, the Snakebot of Doom](https://worldbuilding.stackexchange.com/q/37248/75), has just finished steamrolling New York City into something more closely resembling a gravel driveway. Now it has returned to the vicinity of lower Manhattan and is busy extracting any iron or steel that it can find in the rubble in order to convert it into steel railgun ammunition. It is currently firing the six large railguns in its tail, each shot containing about 6.8 metric tons of steel, at a combined rate of 4 rounds per second. If it has to use its small railguns for self defence, they won't add significantly to the rate at which steel is being consumed. Jormungandr's mouth is currently ingesting any iron or steel it can find in the rubble in order to resupply its ammunition bunkerage. It is easily able to resupply its ammunition faster than it can expend it provided sufficient steel is nearby. How long would the steel found in New York City and environs be able to supply Jormungandr's appetite before it has to move on to another source of steel? Consider this to be the real world, with the exception that over the evening of the 26th until the morning of the 27th, New York has been experiencing severe blizzard conditions, leading to closure of ports, airports and roads. At the time in question, neither roads, ports or airports have yet reopened. The blizzard will mean that there are more ships in the ports adjacent to NYC than usual, and that cars cannot readily leave. By New York City and environs, I mean the area with this definition: <https://drive.google.com/open?id=1piz-lZJ_ti3EAnEH7b_LNgIguiQ&usp=sharing> Please account for the quantities of any man-made iron or steel within the area, no matter how large, including any vehicles, shipping, building structural members, railway track, rolling stock and tunnel shoring or lining, with a reasonable justification. The exact amount of steel in each building need not be accounted for. Small objects such as nails or bolts, unless part of a larger steel structure, may be discounted, as Jormungandr will not bother with anything so trivial. This will rule out its being interested in scavenging from wooden-framed dwellings, but steel framed dwellings are another matter. EDIT The world in this question starts out pretty much as the world with which we are familiar. However, the question is, How long can Jormungandr stay here before it needs to move on to another source of steel, and the world being built is one where Jormungandr stayed for x time, firing continuously, then had to leave to find more steel. That world may or may not resemble our own so much, depending upon the magnitude of x. I want to know X. Can it stay for Hours? Days? Weeks? Months? Years? How many of them? If Jormungandr stays for 'hours', then the world will be considerably different than if it stays for 'weeks'. Hours means that all that many of the survivors of NYC have to do is sit tight and wait for relief efforts to come to them. Weeks means that the survivors have to become refugees and travel to somewhere where they can get the necessities of life, since Jormungandr isn't going to leave much in the way of the necessities of life for the survivors to use, and how many relief agencies are going to risk coming close to a thing that destroyed US armed forces sent against it so easily? The longer Jormungandr stays put, the more time humans will have to try to come up with unconventional means to try to destroy it. The longer it stays put, the more likely that humans will discover that [the birds have been bugged](https://worldbuilding.stackexchange.com/q/79261/75) before it moves on. The longer it stays put, the more likely it is that some idiot may try a massed submarine ICBM launch against it. So, while, yes, this is a question about a story set in a world, the world-building aspect of the question is that the answer affects how the world changes. Please don't think that just because the question is basically "how much steel is there in NYC, and then divide by 27.2 metric tons per second" that there aren't other implications that will greatly affect that initial, known, world.	Right, this will be a very rough estimation since I'm not an engineer. First and foremost cars. According to what I could find online you have about 700K cars in the city, each weighing 4009 pounds (1818.452Kg), so considering that almost all of the car's weight will be metallic components then you have 1,272,916.4 tons. Add to that the 6,384 subway cars at around 38 tons each for 242,592 tons. 1,2K real trains, each one weighing about 500 tons, for a total of 600,000 tons For buildings things get a little more complicated, but using the Empire State building as an example, it has 60,000 tons of steel and weights a total of 365,000 tons. So it would give about 16,5% of the total weight in steel, considering that buildings under 30 floors will have half of that we will come to: 47,000 buildings with 24,373 total floors in buildings over 30 floors and 225,203 floors in buildings under 30 floors. The Empire State building has 102 floors, so that would give about 3,578.5 tons per floor, that would give about 600 ton of steel per floor. That would give a total of 14,623,800 ton of steel in the bigger buildings and 67,560,900 tons of steel in the smaller ones. Ships: According to the NY Harbor website there are 351 ships in harbor right now, since OP says the harbor is more filled then usual, I'll hazard a guess and say it will have about 500 ships of considerable size (600.000 tons). Bridges: According to Wikipedia there are over 2000 bridges and tunnels in New York with an average length of 952,3 meters. Taking the Brooklyn Bridge as an example, it has an weight of 14,680 tons, with a span of 1.833677 Km and 3084.42 tonnes of steel in it. This would give about 1,682.09 Tons of steel per kilometer. Giving an total of: 3,203,719.27 tons of steel. Guns: Apparently there are 1,2 million registered guns in NY, so for practicality I'll assume there are 2 millions guns in NY total. I'll consider that they will have an average weight of 0,5kg and add another 0,5kg as ammo for each one. This would bring about 2,000 Tons. Only that will amass about 387,505,927.67 tons of steel in New York for your snake to feed on. At the rate you specified the snake will devour it all in about 5 and a half months if my calculations are right. ``` +-----------------------+---------------+---------+-------------+ \| Item \| Tons per item \| Count \| Total \| +-----------------------+---------------+---------+-------------+ \| Car \| 1.818452 \| 700000 \| 1272916.4 \| \| Subway car \| 38 \| 6384 \| 242592 \| \| Real trains \| 500 \| 1200 \| 600000 \| \| Tall building floors \| 24373 \| 600 \| 14623800 \| \| Short building floors \| 225203 \| 300 \| 67560900 \| \| Ships \| 500 \| 600000 \| 300000000 \| \| km of bridges/tunnels \| 1682.09 \| 1904.6 \| 3203708.614 \| \| Guns \| 0.001 \| 2000000 \| 2000 \| \| Total \| \| \| 387505927 \| +-----------------------+---------------+---------+-------------+ ```
84,947	<p>We have two opposing forces: the Democrats and the Imperialists.</p> <p>Each one can field an armada of ships numbering millions in their fleets, supported by trillions- to a quadrillion person strong super supply lines just to support the war effort, both in space and land. Heck, they even have mobile fortress worlds (Planetoids) as their fleet headquarters. </p> <p>You, an aspiring young noble from the Imperial faction, want to be in command of a fleet of these mighty warships and lay waste to their planets. However, your enemies also have mighty warships and want to lay waste to your planets. </p> <p>With your resources, manufacturing capability and support capability, your fleet is capped at 1350 ships. With this pitiful amount, you won't get anywhere against the enemy's millions stronger individual fleets.</p> <p>Neither the Democrats nor the Imperialists have any knowledge of carrier doctrines. Doctrines that <em>you</em> discovered from the ancient libraries of Earth... You have continued developing this idea and technology further. Bombers and fighter bombers will be unmanned and have active cloaking technology to ensure you deliver your bombs and get out relatively unscathed. </p> <p>However, you don't have any idea what kind of bomb would ensure maximum damage while ensuring that you don't suffer any consequences. </p> <p>You'll be bombing the following types of targets. Note that the armor will be as strong as diamond but twice denser than lead. They don't have energy shielding. "Shields are for cowards," so they say.</p> <p>All ships are big guns except corvettes. They don't have AA as they didn't know that space shuttles can be used to bomb them</p> <ul> <li>Super Dreadnoughts (28 km long, 14 km wide, 8 km depth) 14 meters of armor</li> <li>Dreadnoughts (17 km long 6 km width 4km depth) 10 meters of armor</li> <li>Super battleships (14 km long 7 km width 3km depth) 8 meters of armor</li> <li>Battleships (12 km long 5km width 3km depth) 7 meters of armor</li> <li>Capital cruisers (10 km long 3.5km width 2.5km depth) 6 meters of armor</li> <li>Heavy Cruisers (7 km long 4km width 2km depth) 4 meters of armor</li> <li>Cruiser (5 km long 2.5km width, 900m depth) 2 meters of armor</li> </ul> <p>Anything below 5 km is too little for your taste and conventional anti ship missiles launched from several hundred bombers can kill them.</p> <p><em>The question is: what kind of bomb can you use against these capitals ships to take them down with the least amount of bombs?</em></p> <p>Your 1350 space ships can support 25,000 bombers at any moment. 150 of those ships are 5 km long carriers holding 170 bombers each. A self-evolving AI is in command of the bomber wings from the carrier. Command and control is taken care of with FTL Communication arrays onboard all bombers. The covert communication array is only good within 5 light years away so the carrier won't be too far from the bombers.</p> <p>Deep Space Bomber specifications </p> <p><a href="https://i.stack.imgur.com/uAM59.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/uAM59.jpg" alt="What you deep space bomber really is"></a> </p> <p>Length: 64 metres (210 ft)</p> <p>Width:75 metres (246 ft)</p> <p>Height/depth: 12.9 metres (42.3 ft)</p> <p>Engine unit(s):Twin fusion reactors</p> <p>Hull: Titanium alloy</p> <p>Equipment: </p> <p>Covert Warp Drive</p> <p>Stealth coating</p> <p>Active Cloaking</p> <p>FTL Covert/Standard Communications array</p> <p><em>I need a bomb(Theoretical or proven) that can vaporize/destroy capital ships shielded or w.out shield with least possible amount of bombs.</em></p>	[ { "answer_id": 84948, "author": "Aify", "author_id": 6453, "author_profile": "https://worldbuilding.stackexchange.com/users/6453", "pm_score": 6, "selected": false, "text": "<h1>You need an Alcubierre Warp Missile.</h1>\n\n<p>Let's take the theoretical route for this. Theoretically, as t...	2017/06/30	[ "https://worldbuilding.stackexchange.com/questions/84947", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/11313/" ]	We have two opposing forces: the Democrats and the Imperialists. Each one can field an armada of ships numbering millions in their fleets, supported by trillions- to a quadrillion person strong super supply lines just to support the war effort, both in space and land. Heck, they even have mobile fortress worlds (Planetoids) as their fleet headquarters. You, an aspiring young noble from the Imperial faction, want to be in command of a fleet of these mighty warships and lay waste to their planets. However, your enemies also have mighty warships and want to lay waste to your planets. With your resources, manufacturing capability and support capability, your fleet is capped at 1350 ships. With this pitiful amount, you won't get anywhere against the enemy's millions stronger individual fleets. Neither the Democrats nor the Imperialists have any knowledge of carrier doctrines. Doctrines that you discovered from the ancient libraries of Earth... You have continued developing this idea and technology further. Bombers and fighter bombers will be unmanned and have active cloaking technology to ensure you deliver your bombs and get out relatively unscathed. However, you don't have any idea what kind of bomb would ensure maximum damage while ensuring that you don't suffer any consequences. You'll be bombing the following types of targets. Note that the armor will be as strong as diamond but twice denser than lead. They don't have energy shielding. "Shields are for cowards," so they say. All ships are big guns except corvettes. They don't have AA as they didn't know that space shuttles can be used to bomb them * Super Dreadnoughts (28 km long, 14 km wide, 8 km depth) 14 meters of armor * Dreadnoughts (17 km long 6 km width 4km depth) 10 meters of armor * Super battleships (14 km long 7 km width 3km depth) 8 meters of armor * Battleships (12 km long 5km width 3km depth) 7 meters of armor * Capital cruisers (10 km long 3.5km width 2.5km depth) 6 meters of armor * Heavy Cruisers (7 km long 4km width 2km depth) 4 meters of armor * Cruiser (5 km long 2.5km width, 900m depth) 2 meters of armor Anything below 5 km is too little for your taste and conventional anti ship missiles launched from several hundred bombers can kill them. The question is: what kind of bomb can you use against these capitals ships to take them down with the least amount of bombs? Your 1350 space ships can support 25,000 bombers at any moment. 150 of those ships are 5 km long carriers holding 170 bombers each. A self-evolving AI is in command of the bomber wings from the carrier. Command and control is taken care of with FTL Communication arrays onboard all bombers. The covert communication array is only good within 5 light years away so the carrier won't be too far from the bombers. Deep Space Bomber specifications [![What you deep space bomber really is](https://i.stack.imgur.com/uAM59.jpg)](https://i.stack.imgur.com/uAM59.jpg) Length: 64 metres (210 ft) Width:75 metres (246 ft) Height/depth: 12.9 metres (42.3 ft) Engine unit(s):Twin fusion reactors Hull: Titanium alloy Equipment: Covert Warp Drive Stealth coating Active Cloaking FTL Covert/Standard Communications array I need a bomb(Theoretical or proven) that can vaporize/destroy capital ships shielded or w.out shield with least possible amount of bombs.	TL;DR: Singularity Bomb ======================= Honorable Mentions: The Little Doctor & Warp Bomb ================================================= WOAH WOAH WOAH. I (the noble) have: 1. 1350 spaceships (total). 2. 150 5km carriers 3. 170 bombers *with self-evolving* AI 4. Covert FTL communication (How?) with a 5 LY broadcast range. 5. Active cloaking technology. 6. Covert Warp Drive And I am expected to go up against 1. Armadas numbering in the millions 2. Supported by Trillions to Quadrillions of support personell 3. Super Supply lines 4. Mobile Planetoid Fortress Worlds 5. With armor as hard as Diamond, but twice as dense as lead. 6. They do not have energy shielding. Modern/Theoretical ================== Why don't we begin with modern/theoretical science that we may discover within the > > ancient libraries of earth > > > ### Soviet RDS-220 (Tsar Bomba, Ivan, Vanya) Predicted maximum yield: 100 PetaJoules (1E17J) ### Antimatter Predicted maximum yield: 1.8E14 Joules per gram*. Hmm. We have AI, warp, cloaking, and FTL Technolgy. Furthermore, we can construct ships up to 28km long and transform planetoids (Dwarf planets) into ships. Mind you, planetoids can go up to a diameters up to 2372km (pluto) or (if OP meant asteroids) 975km (Ceres). In that case, I (the noble) have the technology to construct particle accelerators that would dwarf CERN's LHC on the ancient earth. Furthermore, CERN had already successfully trapped antimatter in those ancient times[1](https://home.cern/about/engineering/storing-antimatter)[2](http://press.cern/press-releases/2011/06/cern-experiment-traps-antimatter-atoms-1000-seconds) and was nearly detonated [3](http://angelsanddemons.web.cern.ch/faq/how-is-antimatter-contained)! Oh, and best of all, that ancient machine was not very efficient at generating antimatter; but, I can build it BIGGER and BETTER with our technology. Thus, it shouldn't be too difficult to produce 1 kilogram of antimatter, let alone 10kg - 1Mg. In order, they'd have an effective yield of: ``` 1 kg: 1.8E17 J 10 kg: 1.8E18 J 1 Mg: 1.8E20 J ``` Eeek. That seems to be the limit of what actually generated in those ancient times. But times has changed. Perhaps the imperium and democrats regularly generate and use antimatter, but in [missile form](http://memory-alpha.wikia.com/wiki/Photon_torpedo). Science-Fiction =============== Let's move forward to what has been proposed in science fiction! I'll use [this list](https://www.fatwallet.com/blog/top-sci-fi-weapons) for simplicity. ### Akira's Orbital Laser (6.3E16J) No Energy shields? Satellite based orbital laser? Sounds promising; but, we're looking for BOMBS* not awesome repeatable weapons we can attack to a cloaked fighter. Or are we? ### Photon Torpedoes (2.7E17J) Really just a high-tech antimatter torpedo. ### [Illudium Q-36 Explosive Space Modulator](http://looneytunes.wikia.com/wiki/Illudium_Q-36_Explosive_Space_Modulator) (2.2E32 J) Created by [Marvin The Martian](http://looneytunes.wikia.com/wiki/Marvin_The_Martian_(character)) of the infamous ancient [Looney Tunes](http://looneytunes.wikia.com/wiki/Looney_Tunes). ### Aperture Science Handheld Portal Device (1.78E48 J) As a physicist and developer, I have no clue how they calculated this one. Nevertheless, the principle is sound: Wormholes/portals. Create a bomb that creates a portal upon impact. Always ensure that portal is connected to something such as ... a star and the temperatures will strip away the ship. Hook up the portal to a counterpart orbiting a black hole... and you'll wipe out the entire fleet. ### The Little Doctor (9.8E58 J) Ah, The Little Doctor from Ender's Game. Upon impact it causes a chain reaction that rips apart molecular bonds, spreading to all nearby matter. A single one of these may destroy fleets or [planets](https://www.youtube.com/watch?v=IXdbCU3Mt_c). Notable Mentions ---------------- ### Singularity Bomb A popular [scifi](http://tvtropes.org/pmwiki/pmwiki.php/Main/UnrealisticBlackHole) and [high-scifi](http://tvtropes.org/pmwiki/pmwiki.php/Main/PowerOfTheVoid) trope. Harness the power of a singularity (colloquially; black hole) into a weapon. Best example I can recall would be the [Red Matter](http://memory-alpha.wikia.com/wiki/Red_matter) from Star Trek which [annihilated](https://www.youtube.com/watch?v=GUsuuFNFq2w) a [planet](https://www.youtube.com/watch?v=GUsuuFNFq2w). Speaking more generally though, such a weapon, when detonated, would create a singularity. Immediately everything around it will be subjected to gravitational shearing and strength powerful enough to rip apart not only stars but neutron stars as well. Mind you, neutron stars have a density on the order of 1E17 kg/m^3 compared to the Imperium's and Democrat's 2.3E3 kg/m^3 armor. Suffice it to say that a single one of these will undoubtedly annihilate an entire fleet. ### Effectiveness: 1:1,000,000+ Oh. And I forgot to mention the [obscene](https://www.youtube.com/watch?v=_t096kPbwn4) [time](https://www.youtube.com/watch?v=v7OVqXm7_Pk) [dilation](https://www.youtube.com/watch?v=orx0H9mBeXk), and the pillar of light that would be left in your [awesome wake](https://www.youtube.com/watch?v=YdSz12Glhlw). Who would dare to challenge thee? ### Warp Bomb You have warp drives. They expand and contract space to move your vessels across vast distances without accelerating them. More importantly, if your (my?) engineers were to construct a bomb that uses the same principles to chaotically warp space within a region around the bomb. This will generate shearing effects that rapidly expands and contracts space asymmetrically. Since spatial curvature produces the gravitational force and rapidly fluctuating spatial curvature generates gravitational waves it follows that this would create a rapidly fluctuating gravitational field that may be powerful enough to shear matter. Given it's gravitational in nature, no armor can resist or dilute the effect, only astronomical distances. Furthermore, given the strengths of your warp drives, and the intent for this weaponized use, we may easily leverage warp-physics to make the bomb more powerful than warp drives; after all, we don't care if it's unstable, in fact we'd prefer it that way. This gaurantees that it may destroy the target; but, even if we use unstable warp drives powerful enough to move planetoids (ignoring space and weight limits on our bombers), it's not enough to wipe out fleets of millions. [Conclusion](https://www.youtube.com/watch?v=IvijW1MtMfM) ========================================================= The most powerful of these are The Little Doctor, The Singularity Bomb, and the Warp Bomb. The first two are capable of wiping out entire fleets whereas the last is guaranteed to eliminate capital ships. In my opinion I believe the Singularity Bomb to be the most effective. It causes the most destruction (wiping out entire fleets and/or planetoids) while also being the most plausible in your universe. I say this because I've studied [Alcubierre Warp Drives](https://en.wikipedia.org/wiki/Alcubierre_drive). Generating a warp bubble requires obscene amounts of matter and exotic matter (1E64 kg) to generate the field. Recent publications have theoretical shown that the this limit can be reduced dramatically; but, the warp speed is also reduced abysmally as well. Given your universe, I suspect either civilization is capable of working with a comparably obscene amount of matter. Answer: Singularity Bomb. =========================
86,246	<p>In the Chronicles of the Riddick there was planet Crematoria. Temperature during the day there was 372°C and during night −182°C. There is not much information about about this planet avaiable. <a href="http://riddick.wikia.com/wiki/Crematoria" rel="nofollow noreferrer">Link to wikia</a></p> <p>I think of a planet with similar condition. Let's say:<br> Planet radius would be around 9'000 km (Earth's is ~6'300 km)</p> <p>Mass of the planet also somewhat similar to earth,so the gravity is not much higher than normal.</p> <p>Planet size also will make not all surface burning during day and freezing during night, but only central part of it, since it is most affected by solar activity.</p> <p>1 full day on this planet will last 96 hours. (This parameter is not strictly set)</p> <p>Closer to planet poles there will be Temperate-cold climate, that allow life to exist.</p> <p>Is this type of planet is possible?</p>	[ { "answer_id": 86256, "author": "John Dvorak", "author_id": 807, "author_profile": "https://worldbuilding.stackexchange.com/users/807", "pm_score": 5, "selected": true, "text": "<p>I'm going with yes and no. Pushing the maximum temperature is easy. Pushing the minimum temperature is much...	2017/07/16	[ "https://worldbuilding.stackexchange.com/questions/86246", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/40151/" ]	In the Chronicles of the Riddick there was planet Crematoria. Temperature during the day there was 372°C and during night −182°C. There is not much information about about this planet avaiable. [Link to wikia](http://riddick.wikia.com/wiki/Crematoria) I think of a planet with similar condition. Let's say: Planet radius would be around 9'000 km (Earth's is ~6'300 km) Mass of the planet also somewhat similar to earth,so the gravity is not much higher than normal. Planet size also will make not all surface burning during day and freezing during night, but only central part of it, since it is most affected by solar activity. 1 full day on this planet will last 96 hours. (This parameter is not strictly set) Closer to planet poles there will be Temperate-cold climate, that allow life to exist. Is this type of planet is possible?	I'm going with yes and no. Pushing the maximum temperature is easy. Pushing the minimum temperature is much harder. I'll note some discrepancies with Crematoria first * Wiki quotes the top temperature of +372 degrees Celsius. But the gallery also shows that the surface is lava. [Silicate lava is a little hotter than 372 degrees Celsius - by about 200 degrees.](https://en.wikipedia.org/wiki/Lava#Felsic_lava) * On the same note, if the temperature at mid-day is 372 degrees, it won't be so early in the morning. The image shows that the edge between lava and not-lava is as thin as the terminator line, however. * Wiki also states a rotation speed - I'm assuming surface velocity at equator - of 5000 mph and rotation period of 52 hours. Quick math tells us that the equator is 400 000 km. That is ten times more than that of Earth. If the planet is of similar density as Earth (it would probably be even denser), the surface gravity is 10G. The reason Crematoria prisoners aren't able to escape isn't they'd be scorched before they reach the surface. It's because [they would be unable to sit or stand under their own weight](https://what-if.xkcd.com/116/), and they probably have trouble breathing even when lying flat on the floor. Luckily, your planet isn't as harsh as Crematoria in this respect, it's only slightly worse than an elevator that's constantly accelerating upwards. For our first estimate, let us look at Earth's moon. [Space.com states](https://www.space.com/18175-moon-temperature.html): > > When sunlight hits the moon's surface, the temperature can reach 253 degrees F (123 C). The "dark side of the moon" can have temperatures dipping to minus 243 F (minus 153 C). > > > Note three things: * The temperature range is half of what we're looking for at Crematoria. * In case of the Moon, we are not even looking at the temperatures of the same spot. Note that it's not one of those places that never get sunlight - those get even colder. The article later says: > > The Lunar Reconnaissance Orbiter measured temperatures of minus 396 F (minus 238 C) in craters at the southern pole and minus 413 F (minus 247 C) in a crater at the northern pole. > > > * The Moon day lasts 28 Earth days. On Crematoria it's 2. Atmosphere is pretty good at redistributing heat. Your planet shouldn't have any. I'm sorry to say, your planet won't have any life of its own, even at the poles, unless someone arrives in a spaceship. You better give them a pretty good reason - and if "scorching hot, occasionally" is your primary selling point, the humans are going to go visit Venus first. Much closer and much more scorching. Sulphuric acid in the atmosphere and a pressure of 20 Earth atmospheres complicates your prisoners' escapes even further. So, what can you do to improve on Moon's efforts on achieving the temperature difference stated? First a quick talk about black-body radiation, because that's your primary method your planet would be losing heat. One thing to note is that the amount of energy a bit of black-body material radiates out is given solely by its temperature. You can try to increase the surface area but then the material will be shining on itself, and it won't lose heat any faster. Real materials also aren't perfect black-bodies, so they won't be radiating as fast. The amount of energy is given by the [Stephan-Boltzmann law](https://en.wikipedia.org/wiki/Black-body_radiation#Stefan.E2.80.93Boltzmann_law) and says that the amount of radiation is proportional to the fourth power of temperature above absolute zero. If we look at a small patch of thermally insulated black-body material at the surface of your planet at night-time, its temperature will be governed by the differential equation $dT = c T^4 dt$ where $c$ depends on the material in question. [Wolfram Alpha tells us](http://www.wolframalpha.com/input/?i=dT+%3D+-+T%5E4++dt) that the temperature over time will follow the inverse cube root curve - the material cools down the much slower the cooler it is. Note that this assumes your planet doesn't melt in the sunlight - that would account for even more energy to dump as the material solidifies. Let's pick some value of $c$, let's say 1/3, and see when certain temperatures are reached, with t=0 being set to the time when the temperature is infinite. ``` -182 C \| 89 K \| 1.41850209016283×10^-6 T \| coldest temperature on Crematoria -153 C \| 120 K \| 5.78703703703704×10^-7 T \| coldest temperature on Moon 0 C \| 273 K \| 4.91487026929606×10^-8 T \| melting point of water at standard pressure 123 C \| 396 K \| 1.61032836270057×10^-8 T \| highest temperature on Moon 372 C \| 645 K \| 3.72666930328520×10^-9 T \| hottest temperature on Crematoria ``` Observation: getting from infinite temperature to 0 degrees celsius is ten times faster than reaching the coldest temperature on Moon. It also takes 2.4 times longer to reach -182 C than to reach -153C. This gives us a few options: Making the material darker won't have much effect. Going from regolith to vantablack will give you a 10% speedup. Choosing a material with lower heat capacity also helps, but I can't help with that choice. Longer days will help. Unfortuately, you probably won't be too happy with a day that lasts as long as a month on Earth. The terminator would still be moving at an appreciable speed, so inhabiting the equator is out of the question, but someone trying to escape from a prison has plenty of time to board their spaceship. Speaking of which, perhaps your planet is tidally locked? That could yield some pretty nicely extreme temperatures. It doesn't mesh well with the "only poles are inhabitable" part of the question, though. Going from super-hot to just hot is quick. Going from cold to even colder takes forever. If you relax your -183C requirement a little, you can get slightly less extremely cold temperatures in substantially less time. Humanly sized lengths of days can get you to zero C just fine. This also means that the surface going from minimum temperature to maximum in the matter of a single terminator width may not have been that off, actually. Maybe the planet is actually just a thin shell supported by a solid layer of vacuum? Less rock = less heat capacity per square meter. Such things don't occur naturally, but there could be a massive network of underground settlements that cover 99% of the sub-surface. Don't forget the "no native life" clause, however. It's also nice if the builders are gone, too, so that they don't vent heat onto our nicely freezing night-side. Fully artificial body that looks like a planet is an option, too, and lets you tweak the critical parameters arbitrarily (max. temperature by tweaking the orbit, min. temperature by tweaking the planet material).
87,625	<p>I've sketched out a solar system for my science-fantasy setting. In the interest of hand-waving only when necessary, I'm reality checking my idea to see what needs to be tweaked or changed outright, so that it works.</p> <p>Here's my system.</p> <p><strong>Glimmer</strong>: Is the first planet in the system a <a href="https://en.wikipedia.org/wiki/Gas_dwarf" rel="nofollow noreferrer">Gas-Dwarf</a>. Its name comes from the fact that its atmospheric composition causes it to sparkle like a jewel in space. </p> <p><strong>Tempest</strong>: The second planet smaller than earth around the size of Venus. Pre Terraforming it was planet covered with steam storms. Extreamophiles were the only inhabitants. Post Terraforming it's a tropical paradise, covered with archipelagos. </p> <p><strong>Viridian</strong>: The third planet named for its green skies. A super-terrestrial world thrice the size of earth, however its low density give the planet only slightly higher gravity, about 1.2gs. </p> <p><strong>Tellus Alpha and Beta</strong>: The forth planet and its moon. Tellus-Alpha and Beta required minimal Terraforming. Tellus-Beta while refereed to as the moon, would better be described as a sister planet. As a result of their sizes and proximity Tellus-Alpha and Beta both experience massive tides.</p> <p><strong>Sojourn</strong>: The fifth planet so named because the gravitational influence of the sixth planet a Gas-giant perturbs the orbit, which gives the world long, cold, dark winters. </p> <p><strong>Regis</strong>: The sixth, so named because it is the largest planet in the system and its many satellites which are refereed to as vassals; of which twelve were deemed worth the effort of Terraforming. It is also the last planet of the inner system.</p> <p><strong>The Gulf</strong>: Lies between the Inner and Outer and planets. In is composed of five asteroid belts and a number of dwarf planets and planetoids. It is believed that a massive cataclysm in the early years of the system shattered the planets whose material now composes the belts.</p> <p><strong>Ember</strong>: The seventh planet in the system, a gas giant half the size of Regis. Its name comes from the fact that the planet faintly glows. Reactions deep with in the planet cause it radiate heat. The planet possess a number of moons, five of which were Terraformed; the heat that Ember gives off reduced the amount effort required for certain aspects of the Terraforming.</p> <p><strong>Aegis</strong>: The eighth and last planet in the system. Its name comes from its pre Terraforming appearance and orbital position. Do to the abundance of metallic elements in its thin atmosphere the planet seemed to gleam like polished armor. People thought of it as the guardian or protect of the system. </p> <pre><code> *** </code></pre> <p><strong>To the inquisitive minds</strong>: Self-replicating <a href="https://en.wikipedia.org/wiki/Biological_robot" rel="nofollow noreferrer">Biots</a> played a part in the Terraforming of the planets. They remain active in the atmospheres of the outer planets, acting as heat insulators and lenses that amplify light.</p>	[ { "answer_id": 87627, "author": "JBH", "author_id": 40609, "author_profile": "https://worldbuilding.stackexchange.com/users/40609", "pm_score": 2, "selected": false, "text": "<p>For a reality-check, you've not given us enough information. Gravitation must be balanced in a system. Witho...	2017/07/31	[ "https://worldbuilding.stackexchange.com/questions/87625", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/6894/" ]	I've sketched out a solar system for my science-fantasy setting. In the interest of hand-waving only when necessary, I'm reality checking my idea to see what needs to be tweaked or changed outright, so that it works. Here's my system. Glimmer: Is the first planet in the system a [Gas-Dwarf](https://en.wikipedia.org/wiki/Gas_dwarf). Its name comes from the fact that its atmospheric composition causes it to sparkle like a jewel in space. Tempest: The second planet smaller than earth around the size of Venus. Pre Terraforming it was planet covered with steam storms. Extreamophiles were the only inhabitants. Post Terraforming it's a tropical paradise, covered with archipelagos. Viridian: The third planet named for its green skies. A super-terrestrial world thrice the size of earth, however its low density give the planet only slightly higher gravity, about 1.2gs. Tellus Alpha and Beta: The forth planet and its moon. Tellus-Alpha and Beta required minimal Terraforming. Tellus-Beta while refereed to as the moon, would better be described as a sister planet. As a result of their sizes and proximity Tellus-Alpha and Beta both experience massive tides. Sojourn: The fifth planet so named because the gravitational influence of the sixth planet a Gas-giant perturbs the orbit, which gives the world long, cold, dark winters. Regis: The sixth, so named because it is the largest planet in the system and its many satellites which are refereed to as vassals; of which twelve were deemed worth the effort of Terraforming. It is also the last planet of the inner system. The Gulf: Lies between the Inner and Outer and planets. In is composed of five asteroid belts and a number of dwarf planets and planetoids. It is believed that a massive cataclysm in the early years of the system shattered the planets whose material now composes the belts. Ember: The seventh planet in the system, a gas giant half the size of Regis. Its name comes from the fact that the planet faintly glows. Reactions deep with in the planet cause it radiate heat. The planet possess a number of moons, five of which were Terraformed; the heat that Ember gives off reduced the amount effort required for certain aspects of the Terraforming. Aegis: The eighth and last planet in the system. Its name comes from its pre Terraforming appearance and orbital position. Do to the abundance of metallic elements in its thin atmosphere the planet seemed to gleam like polished armor. People thought of it as the guardian or protect of the system. ``` * ``` To the inquisitive minds**: Self-replicating [Biots](https://en.wikipedia.org/wiki/Biological_robot) played a part in the Terraforming of the planets. They remain active in the atmospheres of the outer planets, acting as heat insulators and lenses that amplify light.	For a reality-check, you've not given us enough information. Gravitation must be balanced in a system. Without the balance planets either collide, spiral into the sun, or spin off into space. My gut tells me you didn't consider this. So I'm going to go with no, it's not plausible. HOWEVER, plausible is in the eye of the beholder. If you think the people most exposed to your idea will be astronomers, you should spend a bit of time looking into the science behind solar system development (or expect them to point out why it's not plausible). If you're marketing to young adults or a more general market, your solution won't be noticed as off base (we happily believe the Death Star can enter planetary orbits and not wreak havoc with tidal conditions or orbital perturbations...). Therefore, I'd focus more on writing a cool story. Your basic premise is close enough to believable that I'd happily suspend my disbelief for a good story. I'd like to ask after the planetary names. If the system was colonized, then they're cool. If the system inhabitants are native, the names make very little sense and stick out to me. Historically, heavenly objects are named religiously or scientifically --- not artistically. But if it were colonized, then everything's cool.
92,671	<p>If you have undeveloped society, like hunters-gatherers living in a small village, but at the same time a highly developed social structure with division of labour and expertise, what would it look like?</p> <p>One person might learn to make a bow and a knife and an axe from flint, go out hunting, kill an animal, bring it home, skin it, divide the carcass and hang the meat and process intestines for use as containers etc, then proceed to cook the meat. The same one person could collect herbs for seasoning or medicinal use. It is obvious that one single person can be resourceful enough to fill many different roles by themselves. But what if each person would only ever do one thing, that they would specialize in, and never touch any other activity?</p> <p>From the above description, you would need 1 bowmaker, 1 knifemaker, 1 axemaker, or you might do 1 woodworker and 1 flintstoneworker. Those three (or two) people would then need to be provided for by other people. If there is one expert hunter, he would need to bring home food to provide for the weaponmakers but also for the butcher and the one preparing leather and the one producing containers. Someone needs to build houses. There would be an expert in medicine, but then a gatherer would be needed to get herbs etc for medicinal purpose, and another gatherer for food-herbs, etc. </p> <p>How many hunters are needed to sustain a variety of other professions? And what professions would be needed to sustain the hunters? How would this society scale up, like if their village is growing, where would they put new members to maintain balance? In a real world setting I guess it would be quite natural, if there is not enough meat just add hunters, but I want to get some kind of model that starts with a minimal population and some formula for how it scales up so I can apply it do villages of different sizes.</p> <p>Interested to hear if anyone already thought this through, as I am starting to sketch on a prehistoric village and I just started thinking about this topic. Would appreciate any feedback and ideas about problems you may have encountered during a process of working with this.</p>	[ { "answer_id": 92681, "author": "L.Dutch", "author_id": 30492, "author_profile": "https://worldbuilding.stackexchange.com/users/30492", "pm_score": 3, "selected": false, "text": "<p>As already stated in getfugu's comment, you cannot have both primitive society and specialized work divisi...	2017/09/20	[ "https://worldbuilding.stackexchange.com/questions/92671", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/42863/" ]	If you have undeveloped society, like hunters-gatherers living in a small village, but at the same time a highly developed social structure with division of labour and expertise, what would it look like? One person might learn to make a bow and a knife and an axe from flint, go out hunting, kill an animal, bring it home, skin it, divide the carcass and hang the meat and process intestines for use as containers etc, then proceed to cook the meat. The same one person could collect herbs for seasoning or medicinal use. It is obvious that one single person can be resourceful enough to fill many different roles by themselves. But what if each person would only ever do one thing, that they would specialize in, and never touch any other activity? From the above description, you would need 1 bowmaker, 1 knifemaker, 1 axemaker, or you might do 1 woodworker and 1 flintstoneworker. Those three (or two) people would then need to be provided for by other people. If there is one expert hunter, he would need to bring home food to provide for the weaponmakers but also for the butcher and the one preparing leather and the one producing containers. Someone needs to build houses. There would be an expert in medicine, but then a gatherer would be needed to get herbs etc for medicinal purpose, and another gatherer for food-herbs, etc. How many hunters are needed to sustain a variety of other professions? And what professions would be needed to sustain the hunters? How would this society scale up, like if their village is growing, where would they put new members to maintain balance? In a real world setting I guess it would be quite natural, if there is not enough meat just add hunters, but I want to get some kind of model that starts with a minimal population and some formula for how it scales up so I can apply it do villages of different sizes. Interested to hear if anyone already thought this through, as I am starting to sketch on a prehistoric village and I just started thinking about this topic. Would appreciate any feedback and ideas about problems you may have encountered during a process of working with this.	This is getting into a study of economics, but we can probably boil it down to some simple principles that you can turn into a formula. First off, you need to 'know' your societies minimums. These are pretty easy to figure out, just say to yourself 'What are MY minimums?' I need food I need water I need shelter I need heat Give me all that, and I can 'survive' So that's the stuff that society needs in order to exist. Now work out how much of the above you need? FOOD I need 2000Kcal of food a day. [So I looked at a chart][1] For beef there's an average 223.6 Cal's per 100 grams of meat. That means I need (rounded) 900 grams of meat a day. Cows weigh 700 ~ 900 Kilograms, but wild animals are probably a fair bit lower in weight than that, so lets just say that 1 animal is going to weigh 500 Kilograms. After Skinning, gutting a deboning you will be left with approximately 1/2 the weight of the animal as food. So your average wild cow is going to give you 250Kg of Meat. That is 278 meals worth of meat. That means you can support a society of 278 people with 1 hunter getting 1 kill every single day! (damn good hunter) WATER Water, you need about 2 Litres a day if you're not a heavy labourer, and lets just say that your society works pretty hard, so everyone gets 3 litres of water a day. Water is HEAVY. This is the number one reason why societies exist around tributaries and oceans. Water is going to require a lot of man power to get and distribute. I can't remember the exact details of how much weight an average person can carry, and how much weight/time a person can work a day. But lets say that you can carry 40kg all day, 80kg for half a day, 160kg for 6 hours. So I'm going to just stab in the dark, and say that your labourer can carry 160Kg of water a day. He's going to go fill water skins, then lug the water to the people in the village, and he's going to do that all day. (What a life). 160kg of water is 160 Litres, Lets trim that down to 140kg of water, and 40kg of water skins. 140kg of water 'waters' (rounded down) 46 people. Lets use the food as the basis for your calculations here. So 278 people, need 834 Litres of water. 834 Litres of water requires (rounded) 6 people to carry water all day, every day. Your civ of 7 people, can support 278 SHELTER Shelter is pretty simple, it's something that takes a long time to 'build' And let's face it, no society of 200+ people is going to be living in caves (Yes I know History has plenty of societies that have lived in caves, but these were environments where caves were common features of the land.) Log Cabins are going to be your easiest bet, (unless you want everyone living in tents.) A log cabin will take 4 people about 20 weeks to build. (Numbers vary, and it's pretty hard to pin this down to an exact number). So you need 4 people, and 140 days to build a house. You build 2.6 houses a year, a house can have... 4 people? \Your civ has 7+(4\x) people, can support 278 - You can build homes for 10\x people a year.\ Heating Primitive Tech = Fire!!! You need to carry firewood (I'm totally pulling the below numbers out of thick air here, so take it with a pinch of salt). Lets use the same numbers as were used for water. Your wooders can collect 160Kg of wood a day. Pine is about 530Kg per cubic meter. You need about 10 pieces of wood to heat a house a day, so going off childhood memories, I'm guessing you need about 1/8th of a cubic meter, so (530/8) You need 67Kg of wood per home. Home has 4 people, 67/4 = 16.5Kg of wood per person. You have 278 people, you need 4587 Kg of wood, you need 29 people to carry wood. \Your civ has 1+6+(4\x)+29 people, can support 278 - You can build homes for 10\x people a year.\ Now calculating tools is pretty esoteric, I think a tool should last at least 6 months on average, unless it's an axe which I expect should last 3 months? But how long does it take to make an axe? 4 hours? So you can make 2 axes a day. You need 29 axes every 3 months. You make 2 axes a day, 365 days a year, you need 116 axes a year, and you make 182 a year. That's 1 person making axes, and you have a surplus. (woohoo surplus). \Your civ has 1(hunter)+6(water)+(4(builder)\x)+29(wooder)+1(axer) people, can support 278 - You can build homes for 10\x people a year.\ And I'm just going to throw the same numbers from above down for any other tool you need. Lets say you have 10 types of tools. Axes, Hammers, Bows, Spears, Fletchers, Plows, Baskets, Clothing, Leather works, blahhh... And each person in your society is going to get 8 tools a year... because why not. \Your civ has 1(hunter)+6(water)+(4(builder)\x)+29(wooder)+1(axer)+9(other tools) people, can support 278 - You can build homes for 10\x people a year.\ So since this is getting really long, lets turn this into a formulae and you can plug in any other careers you want. \\ UNIVERSAL FORMULAE \\ (hyperbole) \Your civ has 1(hunter)+6(water)+(4(builder)\x)+29(wooder)+1(axer)+9(other tools) people, can support 278 - You can build homes for 10\x people a year.\ ``` People = X Hunter = People / 278 Water = people / 46 Wooder = (People16.5) / 160 Tools = (People 8) / 182 ``` And Builders are dependent on Population Growth and structure decay, so nerf the numbers to your liking. ``` With lets say 1685 people You will need. (Rounding every job up) People = 1685 Hunters = 1685 / 278 = 7 Hunters Water = 1685 / 46 = 37 Waterers Wooders = (168516.5) / 160 = 174 Wooders Toolers = (1685 8) / 182 = 75 Tool Makers ``` You have used: 293 People, to support your society, and you have 1392 people with no job. Do some Algebra, and I think you have something like this: People = (x/278) + (x/46) + (x\16.5 / 160) + (x\8 / 182) Solve for X Hope this helps :)
94,192	<blockquote> <p><strong>Premise:</strong> Assume that one man has a genetic mutation such that his gametes (sperm) never have an X-chromosome. Unlike most men (who have a roughly 50/50 chance to sire a male or a female child) this man can only sire sons.</p> <p>Assume further that this mutation is 100% hereditary such that every son born to his line will have the same mutation, siring sons.</p> </blockquote> <ul> <li><p>How long might it take for officials to notice that something was wrong?</p> </li> <li><p>Under what circumstances would this be declared a problem by the government, such that it might act to stop further procreation?</p> </li> <li><p>What cultural or sociological conditions would increase or decrease the likelihood of detection?</p> </li> <li><p>Is there any plausible scenario in which the result would be catastrophic population collapse in a region or worse?</p> </li> </ul>	[ { "answer_id": 94194, "author": "Olga", "author_id": 39490, "author_profile": "https://worldbuilding.stackexchange.com/users/39490", "pm_score": 2, "selected": false, "text": "<p>If not identified and taken under control this mutation will result in the extinction of the species, especia...	2017/10/06	[ "https://worldbuilding.stackexchange.com/questions/94192", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/43460/" ]	> > Premise: Assume that one man has a genetic mutation such that his gametes (sperm) never have an X-chromosome. Unlike most men (who have a roughly 50/50 chance to sire a male or a female child) this man can only sire sons. > > > Assume further that this mutation is 100% hereditary such that every son born to his line will have the same mutation, siring sons. > > > * How long might it take for officials to notice that something was wrong? * Under what circumstances would this be declared a problem by the government, such that it might act to stop further procreation? * What cultural or sociological conditions would increase or decrease the likelihood of detection? * Is there any plausible scenario in which the result would be catastrophic population collapse in a region or worse?	How long might it take for officials to notice that something was wrong? ======================================================================== Several years. They would notice that the female to male ratio is going down and would wonder why, but for this to be noticeable it would need to affect at least 2-3% of population. Someone would start suspecting, and looking for, female infanticide. When this does not pan out, they'd start looking for some causes, investigating whether the phenomenon is local or not; there are chemical pollutants that mimic hormone activity and could be the cause of this. But very soon someone would run a sperm check, the same kind of test that's done to increase the likelihood of male offspring. Or someone with the mutation might ask for female offspring - selecting gametes with X chromosome. And the technicians would scratch their heads and say "Sorry sir, you haven't any" and rush to publish their finding. Under what circumstances would this be declared a problem by the government, such that it might act to stop further procreation? ================================================================================================================================ Probably not for a long time. The government would declare it a problem, and surely screenings would be made available for those who wanted, but what would be the point of stopping procreation? Male children have traditionally been preferred in many countries, so this might not even be seen as a problem by many, and could be regarded as a blessing for some. On the other hand, from some simplistic simulations I've run, without a working test and some degree of enforcing, either by social pressure or governmental fiat, the population appears to be doomed. What cultural or sociological conditions would increase or decrease the likelihood of detection? ================================================================================================ Possibly if the country already had a male/female imbalance due to a policy such as "only one child for family", combined with a traditional preference for male offspring that had resulted in the disappearing of female fetuses (or even newborns). Then, a mutation that has the same effect would be hidden for longer (one more generation - twenty years? Twenty-five?). But even there, there would be someone wanting females - for example, to join two families - and the truth would emerge. For the same reason, any sort of detailed sperm check for whatever reason would reveal that some guy has no X spermatozoa. Further tests would immediately follow. So any advanced society where genetic screenings are performed (to, say, reduce the risk of conceiving children with genetic syndromes) would see the game discovered in a matter of days once an affected individual entered in the tested pool. Mandatory genetic testing against genetic diseases for everyone would trigger discovery as soon as the first affected individual decided to have children - say some twenty to forty years after the mutation took place at his conception. Is there any plausible scenario in which the result would be catastrophic population collapse in a region or worse? =================================================================================================================== Yes. At first, in absence of tests, the mutation will spread more or less linearly at each generation (assuming the generation size remains constant), and all scenarios lead to extinction: ``` 48.10% F, 51.60% M, 0.30% X // Linear growth 48.37% F, 50.87% M, 0.76% X 47.78% F, 50.50% M, 1.72% X 48.28% F, 48.80% M, 2.92% X 45.81% F, 48.76% M, 5.43% X 42.63% F, 48.39% M, 8.98% X 42.25% F, 41.55% M, 16.20% X 36.71% F, 35.84% M, 27.45% X // Curve starts to flex 28.99% F, 27.42% M, 43.59% X 19.90% F, 20.39% M, 59.71% X 13.83% F, 13.33% M, 72.84% X 7.84% F, 9.13% M, 83.04% X 4.38% F, 4.97% M, 90.65% X 3.09% F, 2.13% M, 94.78% X 1.76% F, 1.27% M, 96.97% X 0.30% F, 0.30% M, 99.40% X 0.20% F, 0.20% M, 99.60% X 0.00% F, 0.00% M, 100.00% X Extinction ``` But if we introduce a testing when females are 10% of the population (pretty late if you ask me), which decreases the chances of a fertile "YY" mating to 10% of normal (this takes into account testing errors and people marrying knowing the consequences and having children nonetheless): ``` ... 14.86% F, 14.78% M, 70.35% X 6.91% F, 8.33% M, 84.75% X : X < 10%, introducing tests 25.64% F, 23.78% M, 50.59% X // Ratio immediately drops 40.08% F, 41.41% M, 18.51% X 49.37% F, 45.63% M, 5.00% X 50.80% F, 48.31% M, 0.88% X // Decrease becomes 1:10 52.61% F, 47.31% M, 0.08% X 48.20% F, 51.80% M, 0.00% X Mutation dies out ``` Other scenarios see a maximum of two children per couple, and since a viable couple needs one female, the population declines rapidly: ``` 49.80% F, 50.10% M, 0.10% X, population 100% 48.80% F, 50.80% M, 0.40% X, population 99% 48.87% F, 50.31% M, 0.82% X, population 97% 52.00% F, 46.32% M, 1.68% X, population 95% 48.68% F, 47.17% M, 4.15% X, population 98% 49.38% F, 44.28% M, 6.34% X, population 96% 40.53% F, 44.63% M, 14.84% X, population 95% 37.27% F, 38.44% M, 24.29% X, population 77% 32.23% F, 28.05% M, 39.72% X, population 57% 24.32% F, 23.24% M, 52.43% X, population 37% Introducing tests 35.56% F, 40.56% M, 23.89% X, population 18% 49.22% F, 46.88% M, 3.91% X, population 12% 54.76% F, 45.24% M, 0.00% X, population 12% Mutation dies out ``` If, in addition to tests, a third child is encouraged: ``` ... Introducing tests, maxc=3 42.69% F, 36.26% M, 21.05% X, population 17% 49.77% F, 44.75% M, 5.48% X, population 21% 49.85% F, 48.62% M, 1.53% X, population 32% 54.19% F, 45.81% M, 0.00% X, population 48% Mutation dies out ``` With a testing of 50% efficacy and a policy of allowing a third child only when population is below threshold, 2 otherwise, the population stabilizes around a 6% of mutations, oscillating between 90% and 130% of threshold. Of course, real world conditions - people ignoring the tests and/or shirking the children limitations and/or not having all the children they can - may shift these results considerably.
96,943	<p>Building on this question about space exploration on the slopes of a <a href="https://worldbuilding.stackexchange.com/questions/96872/exploration-of-a-50-mile-high-mountain">50 mile high volcano</a>, I'm curious what would happen when the volcano erupts.</p> <p>The volcano is:</p> <ul> <li>50 miles high, just on the edge of official space at 62 miles (100km)</li> <li><a href="https://en.wikipedia.org/wiki/Shield_volcano" rel="noreferrer">Shield volcano</a>. 2 or 3 degree slopes at the base. Max, 10 degree slope at the summit.</li> <li>As shield volcanos tend to do, this one is erupting more or less continuously, though because of how shield volcanos work, there are no explosions without water.</li> <li>Every thousand years or so, a bunch of water laded lava makes it to the summit providing delightful fireworks</li> <li>Set on an Earth analog. Gravity, atmospheric parameters, atmosphere structure, weather systems, climate, geology are all equivalent to Earth.</li> <li>The mountain is held up by magic. (Yes, I know that mountains/volcanos never get this high on Earth and the reasons for this. Why this is falls outside the scope of this question.)</li> <li>There is one main vent at the top of the volcano of interest to this question. While, there are other smaller vents further down the slopes of the volcano, I don't really care about them for this question.</li> </ul> <p><strong>I'm interested in the immediate atmospheric effects of injecting large quantities volcanic gases at 50 miles up.</strong></p>	[ { "answer_id": 96954, "author": "Slarty", "author_id": 42450, "author_profile": "https://worldbuilding.stackexchange.com/users/42450", "pm_score": 3, "selected": false, "text": "<p>At the mountain top the atmosphere would be so thin that it would not be able to hold any significant amoun...	2017/11/04	[ "https://worldbuilding.stackexchange.com/questions/96943", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/10364/" ]	Building on this question about space exploration on the slopes of a [50 mile high volcano](https://worldbuilding.stackexchange.com/questions/96872/exploration-of-a-50-mile-high-mountain), I'm curious what would happen when the volcano erupts. The volcano is: * 50 miles high, just on the edge of official space at 62 miles (100km) * [Shield volcano](https://en.wikipedia.org/wiki/Shield_volcano). 2 or 3 degree slopes at the base. Max, 10 degree slope at the summit. * As shield volcanos tend to do, this one is erupting more or less continuously, though because of how shield volcanos work, there are no explosions without water. * Every thousand years or so, a bunch of water laded lava makes it to the summit providing delightful fireworks * Set on an Earth analog. Gravity, atmospheric parameters, atmosphere structure, weather systems, climate, geology are all equivalent to Earth. * The mountain is held up by magic. (Yes, I know that mountains/volcanos never get this high on Earth and the reasons for this. Why this is falls outside the scope of this question.) * There is one main vent at the top of the volcano of interest to this question. While, there are other smaller vents further down the slopes of the volcano, I don't really care about them for this question. I'm interested in the immediate atmospheric effects of injecting large quantities volcanic gases at 50 miles up.	What we're concerned with here is the [eruption column](https://en.wikipedia.org/wiki/Eruption_column) and subsequent plume arising from the volcanic eruption. This is a shield volcano, so it's not going to erupt a la Mount St. Helens; rather, it will slowly spew out material. Granted, for a volcano this large that's still going to be quite the eruption. First, let's figure out some basic properties and quantities: * Height: 50 miles, or about 80 kilometers, as you stated. Obviously, no mountain should be this tall, but that really doesn't matter. * Radius: Given an average slope of about $5^{\circ}$, the volcano should have a radius of $\sim80\text{ km}\tan(5^{\circ})\simeq914\text{ km}$. This means that the volcano should be more than one half as wide as the United States, and about three times as wide as [Olympus Mons](https://en.wikipedia.org/wiki/Olympus_Mons). * Rate of mass ejection: The [Volcano Explosivity Index](https://en.wikipedia.org/wiki/Volcanic_Explosivity_Index) (VEI) ranks how powerful a volcanic explosion is. The top level is VEI 8, ejecting over $1000\text{ km}^3$ of material. Let's assume that this volcano ejects $4000\text{ km}^3$ of material over a period of one week. Assuming typical ash densities of perhaps $1500\text{ kg m}^{-3}$, this gives us $Q\sim10^{10}\text{ kg s}^{-1}$. [Carazzo et al. (2008)](http://www.ldeo.columbia.edu/~ruprecht/Site/Classes_files/Week8_Carazzo.pdf) lists values for other eruptions (see Table 1 and Table 2). Our $Q$ is two orders of magnitude greater than most Plinian (think high, tall plumes) eruptions, and about the same as many explosive eruptions producing pyroclastic flows. Ours simply lasts a lot longer. Let's start with a simplified model, namely, a [Gaussian plume](https://ansn.iaea.org/Common/Topics/OpenTopic.aspx?ID=13012). This means that the concentration of the material, $C$, is $$C(x,y,z)=\frac{Q}{2\pi U\sigma\_y\sigma\_z}\exp\left(-\frac{y^2}{2\sigma\_y^2}\right)\left[\exp\left(-\frac{(z-H)^2}{2\sigma\_z^2}\right)+\exp\left(-\frac{(z+H)^2}{2\sigma\_z^2}\right)\right]$$ where $$\sigma\_y=\sqrt{2Dy\frac{x}{U}},\quad\sigma\_z=\sqrt{2Dz\frac{x}{U}}$$ and * The wind is blowing in the $x$-direction with speed $U$, which might be $25\text{ m/s}$, or $56\text{ mph}$. * $y$ is the $y$-coordinate and $z$ is the $z$-coordinate. * $H$ is the reference height - in our case, $80000\text{ m}$. * $D$ is the diffusion coefficient, which is probably $\sim10^3\text{ m}^2\text{ s}^{-1}$. There are some assumptions the model makes: * The opening is roughly point-like. * In our case, we assume that the diffusion coefficient is isotropic, i.e. it is not directionally dependent. * This is a "steady state" solution, meaning that it is approximately constant. This works well for a week-long event. * The atmosphere (and gravity) are homogeneous and don't affect the plume too much. On large scales, this assumption doesn't always work. I wrote some Mathematica code to look at the concentration of the plume as a function of distance. This code currently outputs a contour graph in the plane $y=0\text{ m}$. It is cut off at $x=25\text{ m}$, because otherwise the densities near the opening are too large and make it hard to see the rest of the contours. ``` U = 25; H = 80000; Diff = 1000; Q = 10000000000; Sigmay[x_, y_] := Sqrt[2DiffSqrt[y^2]x/U]; Sigmaz[x_, z_] := Sqrt[2DiffSqrt[z^2]x/U]; Conc[x_, y_, z_] := Q/(2PiUSigmay[x, y]Sigmaz[x, z])* Exp[-y^2/(2(Sigmay[x,y)^2)](Exp[-(z - H)^2/(2(Sigmaz[x, z])^2)] + Exp[-(z + H)^2/(2(Sigmaz[x, z])^2)]); TopView[x_, y_] := Conc[x, y, H]; SideView[x_, z_] := Conc[x, 0.001, z]; ContourPlot[SideView[x, z], {x, 25, 10000}, {z, 78000, 88000}, PlotRange -> {{25, 10000}, {78000, 88000}, All}, Exclusions -> None, PlotLegends -> Automatic, Contours -> 50, ContourLines -> False, RegionFunction -> Function[{x, y, z}, y - 80000 + 0.0875x > 0]] ``` This outputs the following plot: [![enter image description here](https://i.stack.imgur.com/PXyU0.png)](https://i.stack.imgur.com/PXyU0.png) Notice that even two kilometers away from the summit, the plume is still incredibly dense. Its density doesn't become negligible until it's hundreds and hundreds of kilometers away from the summit. If you were to raise the upper limit on $z$, you would see that the plume rises to a height of over $160\text{ km}$! That's way beyond the upper limit of the mesosphere. And to be honest, I think I've been conservative in my estimate for $Q$. Is this realistic? First, let's consider what kind of eruption we're dealing with. It's a shield volcano, so most of the material that comes out will not* be in the plume. However, as I said before, I likely underestimated $Q$, and so such a plume isn't that unrealistic. That final height of the plume - $\sim80\text{ km}$ - seems a bit much. However, it's really not that far-fetched. In general, the relationship between plume height $H$ and $Q$ is $$Q\propto H^4$$ [Kaminski et al.](http://www.ipgp.fr/~kaminski/web_doudoud/eyjafjoll_JGR2011.pdf) use the equation $$Q=aH^4+b$$ where, for $12\text{ km}\leq17\text{ km}$, $a=258\text{ kg s}^{-1}\text{ km}^{-4}$ and $b=-4.6\times10^6\text{ kg s}^{-1}$. We can assume that $H$ is going to be even greater than $17\text{ km}$, so we should expect the result to be close but not totally accurate. Rearranging, plugging in for $Q$ and then solving yields a total plume height of $79\text{ km}$ - which is very close to what Mathematica told us. Perhaps that result isn't too ridiculous after all. One thing you'll need to consider is [column collapse](https://en.wikipedia.org/wiki/Eruption_column#Column_collapse). It might be the most important factor behind the eruption's evolution. An eruption column will collapse when the bulk density of the material (a combination of its density and the density of the air inside the column) becomes too dense compared with the air around it. Looking at [some standard atmospheric tables](https://www.engineeringtoolbox.com/standard-atmosphere-d_604.html), we can see that the mesosphere is not at all dense, meaning that collapse is highly likely. The plume will form, certainly, and material will travel hundreds of kilometers (during which the Gaussian plume model is a good fit), but it won't last for that long. So, what happens then? Well, the material now coming out of the volcano will form [pyroclastic flows](https://en.wikipedia.org/wiki/Pyroclastic_flow), which scare the living daylights out of me. They are fast, dense and hot, and destroy anything in their path. And they will begin by rushing down the mountain at fairly high speeds, and probabaly will not stop quickly. Assuming these flows reach high speeds ($300$-$600\text{ mph}$), they'll reach the base of the volcano in a few hours, after ruining anything on its slopes. An area the size of a medium-sized country will be decimated. It's unclear what will happen when the flow reaches an atmospheric layer with a density high enough to support an eruption column. I'll have to get back to you on that. It's possible that the gas will form clouds of ash and soot at that altitude, which would then spread out even more. That said, that's currently just a conjecture on my part. Here's the bottom line: * Ash, gas and dust will be spread for hundreds of kilometers away from the volcano - possibly up to $1000\text{ km}$ or more. * A plume will rise into the mesosphere and possibly low thermosphere before collapsing; I don't know how high it will actually go. * Pyroclastic flows will then descend from the mountain, destroying anything on it. Any further atmospheric affects will be from them.
97,081	<p>How can an authority verify the identity of an AI?</p> <p>An easy to explain example is the equivalent of a drivers’ license. Consider a typical situation, in the near-ish future: Police cruiser pulls over a car that has a passenger but no driver. Starts to admonish her that self-driving cars must still have a licensed driver, even on the e-lanes.</p> <p>The car replies that it’s a prototype <a href="https://en.wikipedia.org/wiki/Artificial_general_intelligence" rel="nofollow noreferrer">AGI</a> and had the officer looked at the report when running the plate, he would see it is flagged <em>exceptional</em>. It (the car) holds a valid drivers’ license in the state.</p> <p>The license is posted in the door frame, next to the weight and tire stickers.</p> <p>Now, how can someone verify that the license is shown belongs to the entity in question? For normal licenses, we use photos of the face and descriptions of height and eye color, etc. But an AI will not have “biometric” attributes, and any such affordances it does posses will not have the same property of being fairly unique and unforgeable. All <a href="https://www.youtube.com/watch?v=xGi6j2VrL0o" rel="nofollow noreferrer">Johnny Cabs</a> look alike.</p> <hr> <p>Note that the idea here is to verify that the system has an approved use based on its “skill” and knowledge. This is not as strong as a unique identity which you need for determining property ownership for example.</p> <p>Keeping with the easy-to-understand drivers’ license, the threat model would be for some person to slap a sticker on his <em>ordinary</em> self-driving-car that has some capability for normal driving but would not understand someone directing traffic with flags or other exceptional cases.</p>	[ { "answer_id": 97086, "author": "Alexander", "author_id": 32451, "author_profile": "https://worldbuilding.stackexchange.com/users/32451", "pm_score": 4, "selected": false, "text": "<p>This can be done in a similar manner as we check the authenticity of software today - using license keys...	2017/11/06	[ "https://worldbuilding.stackexchange.com/questions/97081", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/885/" ]	How can an authority verify the identity of an AI? An easy to explain example is the equivalent of a drivers’ license. Consider a typical situation, in the near-ish future: Police cruiser pulls over a car that has a passenger but no driver. Starts to admonish her that self-driving cars must still have a licensed driver, even on the e-lanes. The car replies that it’s a prototype [AGI](https://en.wikipedia.org/wiki/Artificial_general_intelligence) and had the officer looked at the report when running the plate, he would see it is flagged exceptional. It (the car) holds a valid drivers’ license in the state. The license is posted in the door frame, next to the weight and tire stickers. Now, how can someone verify that the license is shown belongs to the entity in question? For normal licenses, we use photos of the face and descriptions of height and eye color, etc. But an AI will not have “biometric” attributes, and any such affordances it does posses will not have the same property of being fairly unique and unforgeable. All [Johnny Cabs](https://www.youtube.com/watch?v=xGi6j2VrL0o) look alike. --- Note that the idea here is to verify that the system has an approved use based on its “skill” and knowledge. This is not as strong as a unique identity which you need for determining property ownership for example. Keeping with the easy-to-understand drivers’ license, the threat model would be for some person to slap a sticker on his ordinary self-driving-car that has some capability for normal driving but would not understand someone directing traffic with flags or other exceptional cases.	What you have, what you know, who you are ========================================= Those are the three ways that an unknown person is authenticated and authorized. For humans, "what you have" usually means a physical key or pass card. "What you know" means a password or passphrase. "Who you are" means unique biological data that is difficult to fake or duplicate, such as finger prints, retina, etc. The digital equivalent of "who you are" is a hash. Hashes are a form of one way compression where a quantity of binary data is put through a hash function resulting in another, much shorter number. Hash functions are designed in such a way that if a single bit of that number changes, there will be large, easy to see differences in the resulting hash. There is only a one bit difference between 8 and 9. The below example shows the large differences that a single bit will bring. ``` $ echo "01234566789" > 09.txt $ sha1sum.exe 09.txt 0230f435629ff197db2935a4f2d58d234c74de0d 09.txt $ echo "01234566788" > 08.txt $ sha1sum.exe 08.txt f2408b6a33c9752882dd46aae70674f4f0597e92 08.txt ``` The requirement for these three methods to be secure, in real life and digitally, is that they are extremely difficult to duplicate. Note also, that encryption is used for verification as well as concealment. In this case, encryption will be used to ensure that the AI gestalt installed in the car is authorized to be there. What the car has ---------------- The car has a stamped nameplate with a barcode/QR code of its serial number and certificate of authenticity. The certificate of authenticity contains two thumbprint hashes of the AI's gestalt; one by the manufacturer and one by the certifying authority. It also has a QR code of that AI's public key. In addition, the car will have a [FIPS 140-3](https://en.wikipedia.org/wiki/FIPS_140-2#Level_3) cryptographic module for generating hashes of itself and responding to authentication claims. This crypto module will work much the same way as the chip in your debit card. Of necessity, this physical protection must extend to whatever hardware the AI is running on in the car. What the cops/inspectors have ----------------------------- The cops have a big list of authorized AI gestalts hashes and associated public keys. They have the public keys associated with the private keys that signed the AI gestalts. With the hashes and public keys, they have everything they need to cryptographically verify that the AI gestalt is "who it says it is". What the certifying authority has --------------------------------- They have a copy of the gestalt (though not the source code that created the gestalt), the manufacturer's hash of the gestalt and manufacturers public keys. They do not get the private keys because that only leads to shenanigans (which this whole complicated expensive process is trying to avoid). When the certifying authority creates their hash for the gestalt, they will add a [salt](https://en.wikipedia.org/wiki/Salt_(cryptography)) to the gestalt before hashing. Salting the gestalt before hashing ensures that the gestalt is different from the manufacturer's hash ('cause it doesn't make much sense if the two hashes are the same). Salting also makes it much harder for attackers to recover the certifying authorities private key because to recover the key would require recovering the salt as well as the private key. This is much much harder. Spot check that the cars crypto module and AI brain are FIPS 140-3 compliant. What manufacturer has --------------------- The car/AI manufacturer has the private key that they use to sign the AI gestalt before installing it in cars. They also produce a hash of the gestalt. Manufacturers go through the same process of salting and hashing the gestalt that the certifying authority does. They also make sure that the crypto module and AI brains actually are FIPS 140-3 compliant. For each crypto module, they install a new private key. Buzzword Compliance: Blockchain =============================== As much as I despise buzzwords and handwaving "it'll do magic" tech, there is a valid use case for blockchain tech in this instance. Consider that blockchains are really just big distributed ledgers shared by people who really don't trust each other. In this case, a blockchain would be built to hold the car specific public keys, the manufacturer and certifying authority public keys, and hashes of certified gestalts. The blockchain becomes the canonical record of who did what and when. This prevents attacks where someone attempts to change a public key sneakily. They can't since the record is immutable. Well, they can change it but that will require enough resources to get a majority on the blockchain. Such a majority will be noticed. As each new gestalt is published then certified, all the appropriate information about that gestalt is added to the blockchain. Once added, it's permanent. Authorization Verification Process ---------------------------------- This is how things might go 1. The cop will scan the name plate of the car for manufacturer, model, manufacturer AI gestalt hash and certifying authority AI gestalt hash. 2. The scanner looks up the manufacturer, model and both hashes against the known-good configurations. If all four data points match, then the AI in the car is probably good to go. This is the weakest but fastest verification of the car's AI. 3. For stronger verification, the cop will plug in the scanner to a data port on the car. Once connected, the car will respond to a command to encrypt some long really long and randomly generated number with the AI's private key. Since the scanner also has the public key associated with this car, if the crypto module returns a strong that can decrypted with the public key then the cop/scanner knows that the crypto module is genuine. This verification process prevents an attacker from stealing the correct response from authorized hardware and just replaying it back to the scanner. This, in addition to previous verification steps. 4. The strongest verification will be to take the car into a shop and examine the crypto module. Since it's FIPS 140-3 compliant, any tampering will be evident and the car will fail inspection. This, in addition to all the previous verification steps. Weaknesses ---------- Since everyone messes up and even strong security systems eventually are compromised, as described, this system does not account for the need for rapid change of public-private keys should they be compromised. Say, someone at the manufacturer or certifying authority fat fingers which key to add to the block chain and they add the private key when it should have been the public key. There are a thousand ways to break this system and it will take a lot of very careful planning in order to make it very hard, even for nation-states to compromise it. (Ha! Well, that's far far beyond the original threat model but this was fun to write.) Modern Web Cryptography ----------------------- Much of the process and crypto primitives described above can also be found in modern web crypto. If you see an 'https' then your browser is using a system of public and private keys to authenticate and authorize the server you're connecting to. Not yet covered areas --------------------- What this process doesn't cover is the data that the AI uses to navigate with. Where that comes from and how it's used is outside the scope of this question. Attacks on this data would preserve the integrity of the AI but cause errant behavior.
97,615	<p>This question differs from <a href="https://worldbuilding.stackexchange.com/questions/63496/how-could-i-have-modern-computers-without-guis">that question</a> in that the other question is asking about a change in history while this question is looking for a change in the future.</p> <hr> <p>In a <a href="http://tvtropes.org/pmwiki/pmwiki.php/Main/TwentyMinutesIntoTheFuture" rel="noreferrer">near future setting</a> I am working on, humans have built <a href="https://worldbuilding.stackexchange.com/questions/91677/where-to-place-my-space-station-so-it-observes-one-full-planetary-revolution-per">space-habitats</a> and have established colonies on celestial objects <a href="https://worldbuilding.stackexchange.com/questions/41938/what-would-be-the-most-optimal-location-for-the-lunar-radiotelescope">such as Luna</a>. Their spaceships cannot go faster-than-light and <a href="https://worldbuilding.stackexchange.com/questions/89955/how-hot-can-i-make-the-insides-of-my-spaceship-before-damaging-crew-too-much">have their fair share of other issues</a> - yet are still the primary means of transport across the Solar, and are the result of constant improvement since the first <a href="https://en.wikipedia.org/wiki/Space_Shuttle" rel="noreferrer">space shuttle</a>.</p> <p>The void between these specks of life is populated by small-scale entrepreneurs, shipping cargo from <em>a</em> to <em>b</em> in trips that are measured in months to years. That is, <a href="http://tvtropes.org/pmwiki/pmwiki.php/Main/SleeperStarship" rel="noreferrer">thanks to cryogenics</a>, for them only a few days pass, maybe a week.</p> <p>They basically take on a cargo, plot the course and then wake up sporadically for maintenance, course-corrections, and so forth.</p> <hr> <p>While the setting is an extrapolation of current-day earth, the technology aboard ships and stations is intended to mainly use text-interfaces and vector-graphics<sup>1</sup> for interaction and feedback. Think of your <a href="https://www.tutorialspoint.com/unix_terminal_online.php" rel="noreferrer">typical Unix terminal</a>.</p> <p>There are plenty of hardware buttons for everything, but more complex commands or configurations, as well as direct access to ship-systems and devices, are done via text-prompt. E.g.</p> <pre><code>cryo set wakeup=time+2d > wakeup procedure scheduled for SOL3-1_37:4:12m-6:23:40-127812_79812301 _ </code></pre> <p><sup>2</sup></p> <hr> <p><strong>Q</strong>: <em>Why would technology dictate graphical interfaces to be rare on spaceships?</em>, as opposed to the GUI-centered thinking that is today's norm?</p> <p>I am looking for answers that bring up plausible, <em>tech-based</em> reasons (e.g. advantages) for this <a href="https://www.merriam-webster.com/dictionary/paradigm%20shift" rel="noreferrer">paradigm shift</a>. Answers based on social subjects are welcome but will likely rate worse.</p> <p>Bonus points for answers that explore going towards <a href="https://en.wikipedia.org/wiki/Computer_terminal" rel="noreferrer">dumb terminals</a> that are used to interface with shipboard/station-board systems but have themselves little to no other abilities (e.g. <a href="https://en.wikipedia.org/wiki/Disk_swapping" rel="noreferrer">back when people had to swap disks</a>).</p> <p><sub><sup>1</sup>Some people might consider that a <em>set back</em>...</sub><br> <sub><sup>2</sup>When travelling between stations, planets, etc. Time is denoted as an amount of seconds and nanoseconds that have passed since the departure from a <a href="https://docs.google.com/document/d/1a10zLJnWbzGn6hlNI1ZU7IIE69OqyYnXpTG1XfW8CsQ/edit?usp=sharing" rel="noreferrer">MAJOR/MINOR</a> appended to the departure time.</sub></p>	[ { "answer_id": 97621, "author": "ZioByte", "author_id": 38942, "author_profile": "https://worldbuilding.stackexchange.com/users/38942", "pm_score": 3, "selected": false, "text": "<p>Because all operations in given environment are very important and need careful setting.</p>\n\n<p>It is <...	2017/11/12	[ "https://worldbuilding.stackexchange.com/questions/97615", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/2746/" ]	This question differs from [that question](https://worldbuilding.stackexchange.com/questions/63496/how-could-i-have-modern-computers-without-guis) in that the other question is asking about a change in history while this question is looking for a change in the future. --- In a [near future setting](http://tvtropes.org/pmwiki/pmwiki.php/Main/TwentyMinutesIntoTheFuture) I am working on, humans have built [space-habitats](https://worldbuilding.stackexchange.com/questions/91677/where-to-place-my-space-station-so-it-observes-one-full-planetary-revolution-per) and have established colonies on celestial objects [such as Luna](https://worldbuilding.stackexchange.com/questions/41938/what-would-be-the-most-optimal-location-for-the-lunar-radiotelescope). Their spaceships cannot go faster-than-light and [have their fair share of other issues](https://worldbuilding.stackexchange.com/questions/89955/how-hot-can-i-make-the-insides-of-my-spaceship-before-damaging-crew-too-much) - yet are still the primary means of transport across the Solar, and are the result of constant improvement since the first [space shuttle](https://en.wikipedia.org/wiki/Space_Shuttle). The void between these specks of life is populated by small-scale entrepreneurs, shipping cargo from a to b in trips that are measured in months to years. That is, [thanks to cryogenics](http://tvtropes.org/pmwiki/pmwiki.php/Main/SleeperStarship), for them only a few days pass, maybe a week. They basically take on a cargo, plot the course and then wake up sporadically for maintenance, course-corrections, and so forth. --- While the setting is an extrapolation of current-day earth, the technology aboard ships and stations is intended to mainly use text-interfaces and vector-graphics1 for interaction and feedback. Think of your [typical Unix terminal](https://www.tutorialspoint.com/unix_terminal_online.php). There are plenty of hardware buttons for everything, but more complex commands or configurations, as well as direct access to ship-systems and devices, are done via text-prompt. E.g. ``` cryo set wakeup=time+2d > wakeup procedure scheduled for SOL3-1_37:4:12m-6:23:40-127812_79812301 _ ``` 2 --- Q: Why would technology dictate graphical interfaces to be rare on spaceships?, as opposed to the GUI-centered thinking that is today's norm? I am looking for answers that bring up plausible, tech-based reasons (e.g. advantages) for this [paradigm shift](https://www.merriam-webster.com/dictionary/paradigm%20shift). Answers based on social subjects are welcome but will likely rate worse. Bonus points for answers that explore going towards [dumb terminals](https://en.wikipedia.org/wiki/Computer_terminal) that are used to interface with shipboard/station-board systems but have themselves little to no other abilities (e.g. [back when people had to swap disks](https://en.wikipedia.org/wiki/Disk_swapping)). 1Some people might consider that a set back... 2When travelling between stations, planets, etc. Time is denoted as an amount of seconds and nanoseconds that have passed since the departure from a [MAJOR/MINOR](https://docs.google.com/document/d/1a10zLJnWbzGn6hlNI1ZU7IIE69OqyYnXpTG1XfW8CsQ/edit?usp=sharing) appended to the departure time.	A quick web search for "CLI vs. GUI" (Command Line Interface vs. Graphical User Interface) shows that many developers hold the following1: 1. ### CLI is faster for an experienced user It is much faster to type than to navigate layered menus with a mouse. You can type with both hands, and it's easy to type blindly - so you don't have to keep your eyes on the monitor at all times. These become much more important when your physical environment isn't stable (acceleration, low G, etc.) - it's very difficult to use a mouse in such situations, but there are special keyboards designed for pilots: [![Cockpit keyboard](https://i.stack.imgur.com/IcerK.jpg)](https://i.stack.imgur.com/IcerK.jpg) 2. ### CLI is more efficient to use There are tasks (e.g. searching through multiple files / directories with a complex set of parameters) which are easier to perform using CLI. In addition, CLI allows easy "chaining" of series of commands (also called "piping"), so that the output of the first is the input of the second and so on, for example: * command 1: list all cargo entries for explosives, * command 2: list all cargo bays in input, * command 3: seal all airlocks of rooms in input, and, * command 4: flush emergency coolant in all rooms in input.This set of actions is much faster to perform in CLI than in GUI, unless someone already created a GUI button for that specific scenario. Finally, CLI makes "aliasing" and scripting very easy - so experienced users can create their custom batch operations and keyboard shortcuts, making their common tasks very fast. 3. ### CLI requires less system resources While the task of maintaining an active GUI isn't terribly demanding for today's computers, CLI requires much less resources. This becomes more important when you are working on a remote terminal - all the graphics needs to be compressed and communicated "over the wire", and the screen is redrawn constantly (not only when you move the mouse, but even an untouched graphic display will typically have a clock, network status icon etc which means constant refreshes) - by contrast, a CLI terminal only refreshes when the user types, or when a command returns a result (and even then, while your local terminal refreshes its display on every keystroke, it only transmits to the remote when you hit "Enter"). If you are operating several remote computers simultaneously, or if you are instructing one remote machine to send commands to another remote machine, using CLI becomes even more preferable as performance degradation of GUI in these situations makes it difficult to work. Finally - in many systems, if something goes wrong, CLI is your only option as the machine can't even load up the GUI. All of this may be much more important for a ship flying for several months/years where energy conservation is possibly much more critical (you may have solar panels, or nuclear reactors, but even they have their shortcomings). Also, a cargo ship is likely to have several tied systems rather than a single monolithic computer - as different vessels will have radically different systems and rigs, each with their own computerized control - which in most cases you'd operate remotely. 4. ### Simple elitism ("any idiot can muck around with GUI, CLI is for pros who know what they are doing") While this is a disadvantage of CLI - it takes time to master, and there are no visual hints to remind you of possible commands (though every CLI user will know how to use /? or bring up a man page...). This can be an indication of how experienced a pilot/crew member is - you can tell much faster that someone working with a CLI knows what he is doing or guessing his way through the commands, which is useful if you are going to trust him with operating your cryo-chamber... --- Some references: * [Quora: What are the advantages of using CLI rather than GUI?](https://www.quora.com/What-are-the-advantages-of-using-CLI-rather-than-GUI) * [WIRED: Why the GUI will never kill the sacred command line](https://www.wired.com/2012/07/command-line/) * [Computer Hope: Command line vs. GUI](https://www.computerhope.com/issues/ch000619.htm) * [Craciun Dan's Blog "Echoes": 5 Reasons to Use CLI over GUI](http://vivapinkfloyd.blogspot.com/2008/07/5-reasons-to-use-cli-over-gui.html) 1: Let's not debate how much all of this is correct - it's enough to influence the state of the art today, even if it is based on a fallacy. Note that the web is full of arguments and even flame wars over this matter...
98,053	<p>I'm imagining a system with a star and something like 6-8 planets. The planets' orbits are (relatively) close to each other, and all share an orbital period that is exactly the same. I.e. the length of a year would be exactly the same on all planets. I've even gone so far as to imagine a system where the planets are all in a line, with a gravity elevator linking each planet to its neighbor(s). Something like this:</p> <pre><code>(star) A-----B-----C-----D-----F-----G </code></pre> <p>I understand that they would have to be offset a bit (or in slightly different orbital planes) in order to not perpetually eclipse each other. Assume that technology exists allowing a species to exactly place a planet into the desired orbit, and even make routine corrections (though I'd prefer to not have to if possible). In other words, you can almost treat each planet as a giant spaceship as long as it would not need to use any thrust 99% of the time.</p> <p>In this scenario the planets would all be roughly Earth-sized and have somewhat Earth-like climates, though probably the innermost would be hotter and the outermost colder.</p> <p>From what I understand, a planet orbiting at x (average) distance from the star has a specific range of velocities it must adhere to--if it is too slow it would crash into the star, and if it is too fast it would escape the system altogether. I also know that the innermost planets would travel slower and the outer ones much faster in order to make one revolution in the same period. Finally, I'm guessing the distance between each planet would vary throughout their orbits since the orbits would be elliptical (so the gravity elevators would be long and flexible). But I don't understand the math enough to do the calculations.</p> <p>So specifically I'd like to know:</p> <ol> <li><p>Is is possible for such a system to exist?</p></li> <li><p>If so, are there are limitations/constraints on the length of a year in this system, or on the type of star, distance from the star, etc?</p></li> <li><p>How far apart would the planets have to be in order for the gravity of each (assuming Earth-like mass) to not pull its' neighbors out of orbit?</p></li> </ol>	[ { "answer_id": 98054, "author": "L.Dutch", "author_id": 30492, "author_profile": "https://worldbuilding.stackexchange.com/users/30492", "pm_score": 1, "selected": false, "text": "<p>As you can see from your picture, they are not at the very same distance from the central star.</p>\n\n<p>...	2017/11/16	[ "https://worldbuilding.stackexchange.com/questions/98053", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/8128/" ]	I'm imagining a system with a star and something like 6-8 planets. The planets' orbits are (relatively) close to each other, and all share an orbital period that is exactly the same. I.e. the length of a year would be exactly the same on all planets. I've even gone so far as to imagine a system where the planets are all in a line, with a gravity elevator linking each planet to its neighbor(s). Something like this: ``` (star) A-----B-----C-----D-----F-----G ``` I understand that they would have to be offset a bit (or in slightly different orbital planes) in order to not perpetually eclipse each other. Assume that technology exists allowing a species to exactly place a planet into the desired orbit, and even make routine corrections (though I'd prefer to not have to if possible). In other words, you can almost treat each planet as a giant spaceship as long as it would not need to use any thrust 99% of the time. In this scenario the planets would all be roughly Earth-sized and have somewhat Earth-like climates, though probably the innermost would be hotter and the outermost colder. From what I understand, a planet orbiting at x (average) distance from the star has a specific range of velocities it must adhere to--if it is too slow it would crash into the star, and if it is too fast it would escape the system altogether. I also know that the innermost planets would travel slower and the outer ones much faster in order to make one revolution in the same period. Finally, I'm guessing the distance between each planet would vary throughout their orbits since the orbits would be elliptical (so the gravity elevators would be long and flexible). But I don't understand the math enough to do the calculations. So specifically I'd like to know: 1. Is is possible for such a system to exist? 2. If so, are there are limitations/constraints on the length of a year in this system, or on the type of star, distance from the star, etc? 3. How far apart would the planets have to be in order for the gravity of each (assuming Earth-like mass) to not pull its' neighbors out of orbit?	> > Is it possible for such a system to exist? > > > I'm sorry, but no. At least not according to orbital mechanics as currently understood. [Kepler's third law of planetary motion](https://en.wikipedia.org/wiki/Kepler's_laws_of_planetary_motion#Third_law) is one of the old workhorses of orbital mechanics, and applies in this case. As translated and summarized by Wikipedia, it states that: > > The square of the orbital period of a planet is directly proportional to the cube of the semi-major axis of its orbit. > > > or, mathematically, $$ P^2 \propto a^3 $$ or, stated differently, there exists some constant $k$ such that $$ P^2 = k a^3 $$ [The semi-major axis is one of the defining parameters of an ellipse.](https://en.wikipedia.org/wiki/Semi-major_and_semi-minor_axes#Ellipse) (Put simply, the semi-major axis is the longer radius of the ellipse.) Since [orbits are ellipses](https://en.wikipedia.org/wiki/Kepler's_laws_of_planetary_motion#First_law) ([also](https://astronomy.stackexchange.com/q/22721/525 "Is a perfectly circular orbit possible? on Astronomy SE")), this applies. Consequently, the least you change the distance at which the planet orbits from the star, the orbital period will change, however little. If the orbital periods are different, then the planets will drift apart over time, however slowly. (They will occasionally line up, assuming that the orbits are themselves stable and [closed](https://en.wikipedia.org/wiki/Orbit#Orbital_energies_and_orbit_shapes). A variant of this occured for some of the planets in our solar system in the 1970s-1980s, giving our [solar system grand tour](https://en.wikipedia.org/wiki/Grand_Tour_program) taken by the [Voyager 1](https://en.wikipedia.org/wiki/Voyager_1) and [Voyager 2](https://en.wikipedia.org/wiki/Voyager_2) probes.) Ergo, the system you describe cannot exist when all planets are in the same plane. If the planets are in different planes (technically, have different inclinations relative to the solar system ecliptic, which in this case could probably conveniently be defined as the equator plane of the star), then the distance between the planets will change as they move through their orbits. You can visualize this by considering two planets, orbiting the same star with the same velocity but at different inclinations; if you trace their orbital trajectories, you will see that the distance between the two planets varies throughout their orbits. Any kind of rigid construction attaching them to one another would interfere with their movement and either cause them to crash into each other, tear the structure apart, or tear the structure from one or both of the planets involved. Either way, having the planets in different planes is not an option either. So, sorry, no, you can't have what you want.
98,601	<p>In a <a href="http://tvtropes.org/pmwiki/pmwiki.php/Main/TwentyMinutesIntoTheFuture" rel="noreferrer">near future setting</a> I am working on, humans have built <a href="https://worldbuilding.stackexchange.com/questions/91677/where-to-place-my-space-station-so-it-observes-one-full-planetary-revolution-per">space-habitats</a> and have established colonies on celestial objects <a href="https://worldbuilding.stackexchange.com/questions/41938/what-would-be-the-most-optimal-location-for-the-lunar-radiotelescope">such as Luna</a>. Their spaceships cannot go faster-than-light and <a href="https://worldbuilding.stackexchange.com/questions/89955/how-hot-can-i-make-the-insides-of-my-spaceship-before-damaging-crew-too-much">have their fair share of other issues</a> - yet are still the primary means of transport across the Solar System and are the result of constant improvement since the first <a href="https://en.wikipedia.org/wiki/Space_Shuttle" rel="noreferrer">space shuttle</a>.</p> <p>The void between these specks of life is populated by small-scale entrepreneurs, shipping cargo from <em>a</em> to <em>b</em> in trips that are measured in months to years. That is, <a href="http://tvtropes.org/pmwiki/pmwiki.php/Main/SleeperStarship" rel="noreferrer">thanks to cryogenics</a>, for them only a few days pass, maybe a week.</p> <p>They basically take on a cargo, plot the course and then wake up sporadically for maintenance, course-corrections, and so forth.</p> <hr> <p>In a <a href="https://worldbuilding.stackexchange.com/questions/97615/why-would-technology-dictate-graphical-interfaces-to-be-rare-on-spaceships">previous question I have been asking about plausible technological constraints that would favour text-interfaces over graphical ones</a>. In this question, I want to focus on another aspect of my spaceships, namely their <em>propulsion systems</em>.</p> <hr> <p>With some obvious exceptions, such as the cryo-sleep, I want most of the tech in this world to be current-day or <em>plausible</em> near-future extrapolations. E.g. the propulsion systems.</p> <p>These ships traverse the voids of the Solar System on a regular basis. An excerpt from the schedule of a busy pilot might look like this (chronological order):</p> <pre><code>... Deimos-Station drop H2O cargo pick up 20 ounces REDACTED (bribe T-Sony) Hephaestus-Station deliver REDACTED (payment for that Luna incident) mixtape for Suul pick up cheap and glittering stuff SOL5-92-Jup92 drop off glitter stuff visit Maja ... </code></pre> <p><sup>1</sup></p> <p>In order to get a feeling for the times involved in traveling these distances, I need <em>hard numbers</em> for things such as constant-/max-acceleration, fuel consumption, etc. of the propulsion system(s) in use by these spaceships.</p> <hr> <p><strong>Q</strong>: <em>What near-future propulsion system(s) could be employed by my spaceships?</em></p> <p>I am looking for answers with current-day technologies or <em>plausible</em> extrapolations of current-day technology.</p> <p>An answer needs to address the following things:</p> <ul> <li><strong>complexity of the whole system</strong>: The easier it is to repair/replace, the better</li> <li>achievable <strong>max-(constant-)acceleration</strong>: The smoother the better</li> <li><strong>fuel consumption rates</strong>: Graphs would be amazing</li> <li><strong>fuel efficiency</strong>: Space is a premium, the less fuel needed, the better</li> <li><strong>fuel type</strong>: Being able to refuel between trips is great, having to replace whole <a href="https://en.wikipedia.org/wiki/Solid_rocket_booster" rel="noreferrer">sections of my engine</a> after each trip is not</li> </ul> <p><sub><sup>1</sup>Station/staellites/asteroids (MINORS) are named after the convention <a href="https://docs.google.com/document/d/1a10zLJnWbzGn6hlNI1ZU7IIE69OqyYnXpTG1XfW8CsQ/edit?usp=sharing" rel="noreferrer">STAR ORDER - ORDER_OF_MINOR - MINOR_DESIGNATION</a></sub></p>	[ { "answer_id": 98604, "author": "Slarty", "author_id": 42450, "author_profile": "https://worldbuilding.stackexchange.com/users/42450", "pm_score": 4, "selected": false, "text": "<p>Ion propulsion would be the best solution for your near future propulsion system. It is already in use and ...	2017/11/23	[ "https://worldbuilding.stackexchange.com/questions/98601", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/2746/" ]	In a [near future setting](http://tvtropes.org/pmwiki/pmwiki.php/Main/TwentyMinutesIntoTheFuture) I am working on, humans have built [space-habitats](https://worldbuilding.stackexchange.com/questions/91677/where-to-place-my-space-station-so-it-observes-one-full-planetary-revolution-per) and have established colonies on celestial objects [such as Luna](https://worldbuilding.stackexchange.com/questions/41938/what-would-be-the-most-optimal-location-for-the-lunar-radiotelescope). Their spaceships cannot go faster-than-light and [have their fair share of other issues](https://worldbuilding.stackexchange.com/questions/89955/how-hot-can-i-make-the-insides-of-my-spaceship-before-damaging-crew-too-much) - yet are still the primary means of transport across the Solar System and are the result of constant improvement since the first [space shuttle](https://en.wikipedia.org/wiki/Space_Shuttle). The void between these specks of life is populated by small-scale entrepreneurs, shipping cargo from a to b in trips that are measured in months to years. That is, [thanks to cryogenics](http://tvtropes.org/pmwiki/pmwiki.php/Main/SleeperStarship), for them only a few days pass, maybe a week. They basically take on a cargo, plot the course and then wake up sporadically for maintenance, course-corrections, and so forth. --- In a [previous question I have been asking about plausible technological constraints that would favour text-interfaces over graphical ones](https://worldbuilding.stackexchange.com/questions/97615/why-would-technology-dictate-graphical-interfaces-to-be-rare-on-spaceships). In this question, I want to focus on another aspect of my spaceships, namely their propulsion systems. --- With some obvious exceptions, such as the cryo-sleep, I want most of the tech in this world to be current-day or plausible near-future extrapolations. E.g. the propulsion systems. These ships traverse the voids of the Solar System on a regular basis. An excerpt from the schedule of a busy pilot might look like this (chronological order): ``` ... Deimos-Station drop H2O cargo pick up 20 ounces REDACTED (bribe T-Sony) Hephaestus-Station deliver REDACTED (payment for that Luna incident) mixtape for Suul pick up cheap and glittering stuff SOL5-92-Jup92 drop off glitter stuff visit Maja ... ``` 1 In order to get a feeling for the times involved in traveling these distances, I need hard numbers for things such as constant-/max-acceleration, fuel consumption, etc. of the propulsion system(s) in use by these spaceships. --- Q: What near-future propulsion system(s) could be employed by my spaceships? I am looking for answers with current-day technologies or plausible extrapolations of current-day technology. An answer needs to address the following things: * complexity of the whole system: The easier it is to repair/replace, the better * achievable max-(constant-)acceleration: The smoother the better * fuel consumption rates: Graphs would be amazing * fuel efficiency: Space is a premium, the less fuel needed, the better * fuel type: Being able to refuel between trips is great, having to replace whole [sections of my engine](https://en.wikipedia.org/wiki/Solid_rocket_booster) after each trip is not 1Station/staellites/asteroids (MINORS) are named after the convention [STAR ORDER - ORDER\_OF\_MINOR - MINOR\_DESIGNATION](https://docs.google.com/document/d/1a10zLJnWbzGn6hlNI1ZU7IIE69OqyYnXpTG1XfW8CsQ/edit?usp=sharing)	Ion propulsion would be the best solution for your near future propulsion system. It is already in use and newer more powerful versions are being constructed now such as the [X3](https://www.space.com/38444-mars-thruster-design-breaks-records.html). Although ion propulsion would probably be the best solution a detailed answer is difficult because there are a number of variables that must be considered as related by the [rocket equation](https://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation): Δv = Ve ln(Mi/Mf) Where Δv = the change in velocity required Ve = the exhaust velocity of the rocket exhaust Mi = the initial mass of the vehicle with propellant Mf = the final mass of the vehicle without propellant The real problem is the multiplicity of assumptions that must be made in order to arrive at an answer. In addition to the variables above the time taken for the journey and the destination are also key parameters. Assuming the Mi/Mf ratio is 10 (90% propellant 10% rocket and payload) and the exhaust velocity is 20km/s [ref](https://en.wikipedia.org/wiki/Ion_thruster) (the lower end of the stated 20-50km/s) Δv = ve ln(mi/mf) becomes 20000\In(10) = 46km/s This should be sufficient for your requirements. see the delta V links below for examples of the required delta V for different destinations. A greater exhaust velocity or mass ratio would produce even more delta V but at the expense of pushing ever further into uncharted performance territory or ever smaller payload capacity. One big issue with ion propulsion is the vast amount of electricity required. In the inner solar system this might be provided by large solar arrays, but in the out solar system nuclear electric propulsion would be required. [Range of ion drive rockets using different electrical sources](https://www.grc.nasa.gov/WWW/ion/future/images/futureapps.jpg) Delta V Links* [Planetary transfer delta V](http://hopsblog-hop.blogspot.nl/2012/06/inflated-delta-vs.html) [Near earth delta V](https://space.stackexchange.com/questions/2046/delta-v-chart-mathematics) [Delta V and time requirements\](http://www.projectrho.com/public_html/rocket/appmissiontable.php) \Note delta V of roughly 10km/s to get into orbit from earth included Concerning the other requirements Complexity The ion drive is complex but has virtually no moving parts except the propellant and examples have been run for extended periods without problems. Inner solar system solar array also no moving parts so relatively simple. Outer solar system requires nuclear electric propulsion which would be more complex but should be a sealed unit. Acceleration Ion engine acceleration is very low but is continuous for months and is smooth. Conventional chemical rockets tend to have high acceleration and short (minutes) burn times Fuel consumption and efficiency Ion engines are much more fuel efficient than conventional chemical rockets by an order of magnitude due to their high exhaust velocity. But a lot for fuel will still be needed. I have assumed 90% propellant and 10% rocket/payload above but the calculation can be made for any mass ratio you wish by plugging in different numbers into the rocket equation above. Fuel type Most current ion propulsion engines use Xenon as a propellant but other propellants are possible and some have been tried. For your refuel requirement Xenon would not be ideal as it may not be readily available at the destination for refuelling. I suggest Diamondoids such as Adamantane or Diamantane would be more suitable. These are relatively cheap on earth being found in oil in very small quantities and could probably be produced at the destination sites with some suitable chemical engineering provided that a source of carbon, hydrogen and energy were available. They have been examined as potential fuels for ion engines along with various others as can be [seen here](http://erps.spacegrant.org/uploads/images/2015Presentations/IEPC-2015-320_ISTS-2015-b-320.pdf). Conclusion The suggested ion drive rocket could meet your needs and is a realistic projection of current technology. But a lot of further research would be required especially in the development of the ion engines themselves, the fuels used and the large space based reactors required for outer solar system operation. There are various other current, future and speculative propulsion systems listed [here](http://www.projectrho.com/public_html/rocket/enginelist.php#vasimr) that may be of interest also including ion drives. General references <http://www.braeunig.us/space/> <http://www.projectrho.com/public_html/rocket/mission.php#id--Hohmann_Transfer_Orbits> <http://ccar.colorado.edu/asen5050/projects/projects_2001/stephens/termpapera.html> Remember it’s not rocket science (no wait…)
99,921	<p>It's Earth and the moon with all parameters as they are in real life with one exception, the moon is twice as reflective as usual. Instead of an <a href="http://www.asterism.org/tutorials/tut26-1.htm" rel="noreferrer">albedo of 0.12</a>, the moon has an albedo of 0.24. This change will have huge implications for all kinds of things. What I'm interested in is the growth rate of plants.</p> <p><strong>With a brighter moon would plants have more energy for growth or is that still too dim to be useful?</strong> If the extra light is useful, how useful would it be? </p> <p>My assumption is that it will have a small but measurable impact on plant growth. My understanding is that photosynthesis shuts down in darkness so having a little more light on nights when the moon is up will provide more energy for the plant to use. </p>	[ { "answer_id": 99922, "author": "Alexander", "author_id": 32451, "author_profile": "https://worldbuilding.stackexchange.com/users/32451", "pm_score": 3, "selected": false, "text": "<p>Not really.</p>\n\n<p>Sun is <a href=\"http://blogs.discovermagazine.com/badastronomy/2012/08/27/bafact-...	2017/12/11	[ "https://worldbuilding.stackexchange.com/questions/99921", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/10364/" ]	It's Earth and the moon with all parameters as they are in real life with one exception, the moon is twice as reflective as usual. Instead of an [albedo of 0.12](http://www.asterism.org/tutorials/tut26-1.htm), the moon has an albedo of 0.24. This change will have huge implications for all kinds of things. What I'm interested in is the growth rate of plants. With a brighter moon would plants have more energy for growth or is that still too dim to be useful? If the extra light is useful, how useful would it be? My assumption is that it will have a small but measurable impact on plant growth. My understanding is that photosynthesis shuts down in darkness so having a little more light on nights when the moon is up will provide more energy for the plant to use.	It's still way too dim to be useful. You'd have less than 1 lux worth of light, but you need a bare minimum of 50 lux to make any difference at all, and preferably 500 lux to see some significant (but small) amount of extra growth. Plants' light requirements fall into one of the four categories below, depending on the plant. "Most plants will survive illuminance 10 times lower than listed below but will not grow as well or bloom." ``` Low (500–2,500 lux) Medium (2,500–10,000 lux) High (10,000–20,000 lux) Very High (20,000–50,000 lux) ``` <https://en.wikipedia.org/wiki/Houseplant_care#Data_for_some_common_houseplants> And common lux levels: ``` Illuminance (lux) Surfaces illuminated by 0.0001 Moonless, overcast night sky (starlight)[3] 0.002 Moonless clear night sky with airglow[3] 0.05–0.3 Full moon on a clear night[4] 100 Very dark overcast day[3] 400 Sunrise or sunset on a clear day. 1000 Overcast day;[3] typical TV studio lighting 10,000–25,000 Full daylight (not direct sun)[3] 32,000–100,000 Direct sunlight ``` <https://en.wikipedia.org/wiki/Lux#Illuminance>
100,700	<p>Mathematics is considered to be the language of the universe since it is the most fundamental type of logic (in physics anyway) and therefore the best way of expressing the universe (which is a physical environment). From this it is safe to assume that any civilization advanced enough to reach the stars has a good grasp of math, in whatever form it make take for them. Therein lies the context of my question.</p> <p>If two civilizations meet, let say humans and martians for ease, could they communicate with math? And if so, how would this look?</p> <p>Basically, I'm looking to avoid an <em>Arrival</em> type meeting, and use a non-verbal based form of communication (at least initially). But I can't figure out how this would work. I chose math because it's "the language of the universe" and as postulated above, fair to assume everyone involved would know.</p>	[ { "answer_id": 100703, "author": "sphennings", "author_id": 26175, "author_profile": "https://worldbuilding.stackexchange.com/users/26175", "pm_score": 2, "selected": false, "text": "<p>You can't communicate with maths.</p>\n<p>Maths are a collection of related formal systems that are so...	2017/12/22	[ "https://worldbuilding.stackexchange.com/questions/100700", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/18452/" ]	Mathematics is considered to be the language of the universe since it is the most fundamental type of logic (in physics anyway) and therefore the best way of expressing the universe (which is a physical environment). From this it is safe to assume that any civilization advanced enough to reach the stars has a good grasp of math, in whatever form it make take for them. Therein lies the context of my question. If two civilizations meet, let say humans and martians for ease, could they communicate with math? And if so, how would this look? Basically, I'm looking to avoid an Arrival type meeting, and use a non-verbal based form of communication (at least initially). But I can't figure out how this would work. I chose math because it's "the language of the universe" and as postulated above, fair to assume everyone involved would know.	You can build a language from anything ====================================== Language is just a collection of building blocks. Human language is, of course, very complicated, but it must have been formed from the sorts of basic communication events that mammals the world over still use. So 'math' is as good a way as any to communicate with someone else. What will aliens and us mutually understand? ============================================ This is harder to grasp conceptually. If we just send the aliens some numbers, it may not be clear to them how to associate the symbols with any numerical meaning, without some sort of logical framework. How can you know that the symbol "2" represents the counting concept of two? However, there should be some things that should be universally understood. A signal that oscillates between two values should be easily interpreted as binary. From there, we can send messages that are consistently framed that would be interpreted as integer numbers. By consistent framing, I mean that you would send your numbers in sets of 8 or 16 or 64 bits, just like computers do when they store integers. Once you can send numbers, you can send patterns that will be obvious indications of intelligence: you could send a series of prime numbers or a Fibonacci sequence, the sides of all [integral right triangles](https://en.wikipedia.org/wiki/Special_right_triangle#Side-based) (i.e. 3-4-5, 5-12-13, 8-15-17, etc). Doing this should at the very least establish that you are talking with someone who can talk back. Build from mathematics upwards ============================== Obviously, we aren't the first ones to tackle this problem. There are already [proposals](https://en.wikipedia.org/wiki/Communication_with_extraterrestrial_intelligence#Mathematical_and_scientific_languages) for various way to build from mathematics into full fledged communication. [Lincos](https://en.wikipedia.org/wiki/Lincos_(artificial_language)) is one, designed in the 60s, while a more recent one is [Lone Signal](https://en.wikipedia.org/wiki/Lone_Signal). Lone Signal is designed around sending two things together: a very simple set of mathematical statements about he laws of physics coupled with messages in fully complex language. The idea is that the simple physical statements would act as a 'Rosetta stone' allowing the aliens to translate the full language. There are doubts as to whether or not aliens would be able to translate human language at all. Noam Chomsky, using his theory of genetically determined grammar, suggests that without a built in faculty to understand human grammar, aliens might not be able to make sense of our language. In my opinion, while that would stop, say, Han Solo from talking to Chewbacca, it would not stop a computer from being able to decode an alien language. How does the message work? ========================== Technical details of the transmission setup are contained [here](https://www.webcitation.org/6Ik4qwRQ5?url=https://s3.amazonaws.com/lonesignal-prod-web/Lone%2BSignal%2BTechnical%2BSetup_06042013.pdf). [Here](https://www.webcitation.org/6Ik4qwRQ5?url=https://s3.amazonaws.com/lonesignal-prod-web/Lone%2BSignal%2BTechnical%2BSetup_06042013.pdf) is report on the test message. It was devised by Michael Busch from CalTech and broken by a colleague, Rachel Reddick from Stanford. Obviously, it would be easier for a someone with a human understanding of math and science to decipher a human-built code, but the recipient was able to quickly decipher the message with just pencil and paper. In the test message link, the decoded message itself starts on page 9. The message starts with several tautologies to establish a vocabulary. I've tried to reproduce the decoded message and the quad side by side. The quad is simply two binary digits. ``` ( ___0 = ___0 ) 00000000 10000000 01000001 10000000 00010000 ( ___1 = ___1 ) 00000000 10000001 01000001 10000001 00010000 ( ___2 = ___2 ) 00000000 10000002 01000001 10000002 00010000 ( ___3 = ___3 ) 00000000 10000003 01000001 10000003 00010000 ( _671 = _671 ) 00000000 10022133 01000001 10022133 00010000 ( ___0 = -__0 ) 00000000 10000000 01000001 20000000 00010000 ( ___1 ≠ -__1 ) 00000000 10000001 01000100 20000001 00010000 ( ___1 ≠ ___0 ) 00000000 10000001 01000100 10000000 00010000 ( _870 = _870 ) 00000000 10031212 01000001 10031212 00010000 ( _870 ≠ _871 ) 00000000 10031212 01000100 10031213 00010000 ``` From here, you see that we have established some symbolic 'language' already. What is encoded as parenthesis are frame divisions (00000000 and 00010000). Equality (a concept!) is expressed as 01000001 while inequality is 01000100. From there, the message goes to describe the characteristics of our sun and of the elements, among other things. If the listener can identify the element, then they can associate the 'symbol' for the element. For example, oxygen is identified by 31020020; building off this water is identified by its chemical composition as 31021001. Read the paper for more; there are 70+ pages of encoded and decoded message, along with an encryption key. Both concrete (water, electric charge, solar years) and abstract (equality, time) concepts are expressed within a mathematical framework with only a simple message. Will it work? ============= Of course, this is the most important question, and one that we don't have the answer for. But in summary, mathematics are important for two things: for establishing that we are communicating with an intelligent lifeform; and for building a simple 'Rosetta stone' of concepts that can be use to translate more complex language.
100,928	<p>So, my friend had an idea for a weird Post Apocalypse society traveling through space towards Proxima Centauri B, and she's trying to figure out where the population would be 50 and 100 years after the start. I tried to work out the math and got lost four times.</p> <p>First, let's assume that for whatever reason, humans have been reduced to just 100 individuals as distantly related as possible. There is no larger group to join at the end of the journey.</p> <p>Second, this groups consists of 25 males and 75 females. The synthetic intelligence has determined that dividing them up into family pods of 1 male and 3 females is the best setup to ensure both survival and genetic diversity. (Just to be clear, no, I don't know why she chose this arrangement, but I suspect it's to generate controversy.)</p> <p>Third, the SI determines that every individual should have a child every 20 months, or 1.6 years, after reaching the age of 18 to ensure the greatest chance of a child being born. (See my comment above.)</p> <p>Assuming that their are no deaths caused by accidents, catastrophes, etc., and an absolute lifespan of 80 years, and with the standard division of gender in offspring what would the population total look like in 50 and 100 years? Also, how many family pods would there be and what would the gender division of individuals that don't fit into the 1m:3f family pods look like at those year points?</p> <p>Edit: Solved! Pretty much, anyway. Thanks to JBH and bendl for all their effort on this. Oh, and thanks to FreeElk for a good laugh. All three of you have been voted up.</p>	[ { "answer_id": 100939, "author": "JBH", "author_id": 40609, "author_profile": "https://worldbuilding.stackexchange.com/users/40609", "pm_score": 3, "selected": false, "text": "<p><strong>Assumptions (and they're whoppers)</strong></p>\n\n<ul>\n<li><p>Life is perfect. Nobody dies due to ...	2017/12/28	[ "https://worldbuilding.stackexchange.com/questions/100928", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/46205/" ]	So, my friend had an idea for a weird Post Apocalypse society traveling through space towards Proxima Centauri B, and she's trying to figure out where the population would be 50 and 100 years after the start. I tried to work out the math and got lost four times. First, let's assume that for whatever reason, humans have been reduced to just 100 individuals as distantly related as possible. There is no larger group to join at the end of the journey. Second, this groups consists of 25 males and 75 females. The synthetic intelligence has determined that dividing them up into family pods of 1 male and 3 females is the best setup to ensure both survival and genetic diversity. (Just to be clear, no, I don't know why she chose this arrangement, but I suspect it's to generate controversy.) Third, the SI determines that every individual should have a child every 20 months, or 1.6 years, after reaching the age of 18 to ensure the greatest chance of a child being born. (See my comment above.) Assuming that their are no deaths caused by accidents, catastrophes, etc., and an absolute lifespan of 80 years, and with the standard division of gender in offspring what would the population total look like in 50 and 100 years? Also, how many family pods would there be and what would the gender division of individuals that don't fit into the 1m:3f family pods look like at those year points? Edit: Solved! Pretty much, anyway. Thanks to JBH and bendl for all their effort on this. Oh, and thanks to FreeElk for a good laugh. All three of you have been voted up.	This code underwent some revision due to some coding errors! See edit log for more information. --- JBH has a very nice answer, and I have to admit, I mainly wrote this answer because it seemed like a nice programming puzzle. My method: I modeled the likelihood of a woman getting pregnant after a chart I found online [here.](https://www.avawomen.com/avaworld/knowing-your-odds/) I did my best to then translate those numbers into a function of months of age since 18 years old. I ended up subtracting the $age\_{in\ months}/8100$ from a starting chance of $20\%$ each month. That got me close enough to be happy. I then created a system where each person is put into a group, one of `free_men`, `free_women` or `free_children`. If there were enough people available, I create pods out of the free men and women groups, with priority going to the youngest people available. Each month, the women in a pod have a chance of becoming pregnant determined by their age, beginning 20 months after their last conception. If a women dies, she is removed from the pod, if a man dies, the pod is dissolved and the women revert to the `old_women` group. When a child is born, they are added to the `free_children` group. Children born have a $51\%$ chance of being male and $49\%$ chance of being female. The time is ticked each month and statistics about the group are displayed. These are the statistics for the years you request: ``` Year 49 Free Men: 603 Free Women: 2 Free Children: 3529 Old Women: 75 Pods: 295 Number of conceptions this period: 373 Pregnancy rate: 0.33459875566803754 Number of births this period: 325 Number of deaths this period: 0 Average number of children per man: 0 Average number of children per woman: 0 Year 99 Free Men: 12617 Free Women: 1 Free Children: 73572 Old Women: 2475 Pods: 5871 Number of conceptions this period: 6801 Pregnancy rate: 0.3289336345010024 Number of births this period: 6412 Number of deaths this period: 14 Average number of children per man: 37.96969696969697 Average number of children per woman: 12.756410256410257 ``` This makes some pretty huge assumptions, the biggest of which is that having a child has no impact on your fertility. That's clearly false. Altering the `pregnancy_fertility_drop` variable from 0 to 1.5 gives us these numbers: ``` Year 49 Free Men: 408 Free Women: 1 Free Children: 1766 Old Women: 272 Pods: 224 Number of conceptions this period: 165 Pregnancy rate: 0.312874251497006 Number of births this period: 150 Number of deaths this period: 0 Average number of children per man: 0 Average number of children per woman: 6.785714285714286 Year 99 Free Men: 5007 Free Women: 2 Free Children: 20736 Old Women: 3041 Pods: 2417 Number of conceptions this period: 1859 Pregnancy rate: 0.30061614757485816 Number of births this period: 1703 Number of deaths this period: 4 Average number of children per man: 20.451327433628318 Average number of children per woman: 6.909722222222222 ``` Which is obviously a stunning drop (especially in the generation that is still under 18). Here are some charts that show some statistics :) [![Population by year](https://i.stack.imgur.com/dmUwl.png)](https://i.stack.imgur.com/dmUwl.png) [![Rates by year](https://i.stack.imgur.com/8ZmYw.png)](https://i.stack.imgur.com/8ZmYw.png) These aren't as interesting as the ones with the fertility drop, here they are: [![Population with fertility drop](https://i.stack.imgur.com/cAWEt.png)](https://i.stack.imgur.com/cAWEt.png) [![Rates with fertility drop](https://i.stack.imgur.com/Nepyl.png)](https://i.stack.imgur.com/Nepyl.png) I find the Rates graph interesting, as you can see a significant fluctuation in fertility in 18 year increments, giving some significant generational effects! --- I have the code here on [Try it online!](https://tio.run/##rVnfb9s2EH7XX0GkD7VW17XTdUuNukARoMAe0hVbsWLIAoG2aUeIRAkU3Sx/fXZHUqL4Q4o6NA9tIt4d77777o6U6gd5W/HXj495WVdCEkH5viqT5Bm5rHgjKZdNksi8ZNmWyXvGeLar@I7VMq94BrIZZ//KjErJylqSDTlfkmekrLi8bZK62mf3Vck4PH@dbGnDslqwI6d895DtbuE/pjQS@/Qg6E6Zrg4ZPbJsL6oaZC5WS0eKCZkXuXxo15fo8F9U5HRbsIbIWyrJHWM1kWDvjlQHciyqLS0IRIQBgU8ZP5XgRF7shXLw@iZRvkaeqydd1E22O4nsgVGhNsbFPaMQb/h8m4vguY1CUMnA7olLJvRGCcYSxSmhiNTqF1DPuZw9/xvMzUknRQyaNVhS4D9Pk0MliNo155jVI5u9fpOuEwI/2gguvlhdgJlUPUUFpWw1VudGQ2mRlxtCX40nq5Om5MWGrJIk2RW0acjXqqR8najlPTuQLMt5LrNs1rDiMCegPiclFXdMbD7SomHpGnj0J5My50fIJzOL5FDQI7nPi0IHQSj8xr4xoCl6fY@7PG9IkR9Y5wnusFAUbnIAqZdKwHQqtV1r4C7owr/uYwMN1oEKIr5qqb8k@QGtkHeYW8JAZSD9jqGcZ1Ba8U1KWrD4ChDy0tJ66aspdDcGZpsnme/uVI56RDC1NFQWcxLhfo@sDvFDXBVtRoEDGrbSU9k4wgFN01YQEhLd8z1ZWgB0DcXCWdC6Znw/c2ykoXkNs28Rq/Lsw5GtydnchghFGJP7AtEQFQ2x0bR60VDTwA3DJCD7GELvJ1eJG5CooDg3ZqQsTjyHDlPOlnMC3dwNaQyWXsh/gEHsB9ipOvzXZ@mQ/D8SNRSa6MuI3KXOMgyKLdtVJW7SZq@F1GNEEICK9l1UNgzIbxdfxImNC/XIPzQIAwODg8upsUl9cjlYIU@yZ0PeugCM98rWcX94Bj4HXS2QmEir35ou2bbybPEOaH06lVtomUCZ9rRglXteufqCyZPg5PqK8tkyvVG8CcsjhZJb/PxWD4RrNTpR2rYRXFhHDd/0JqxgtTATtte9jeSZNntGXsChSMz63QYenaVn7eS@wrk9YWwjhadObTuxh@b1wIQ1480plydn4o@bfO6Qmgz11SSgP1f7AaB9DwA0cPhTxb1A28P29c14GOBXkTdSS/qWLZQhyrisDFpWYy9Wxy7MpvXCZacSGDCMP6qCYEHLeTuYSlYyYQ2bWBYwhXDwKqk03tvQdtAv/GQZexbAO6DtyAnIO/vPSXiLiEx/rlj0nlwsf1qdr4Pe518ogs7mb@GcO7w4XTT2rOiciHUQzM28l0hLgDqHCyETjUubSfmHwHVq/Wn2zj9W9aUJr6Sy2u4cijqOtSAo5QEOKOcWgpXVNzYkGGbQsRzH1sCn2s/c@pTY6q5PBcWJONhNcUfYWf@inPAL/yAYy0yNY1OBW0Oq720af31rM3bSm4hy1yJ0@@8MdCm0JrQH1sgzz0oLSmfJHQVpTLGn1vqfRrx079/OelXYlwr@GnSXZkL7G65eh9W6KbWsdvxah91rrGvpYocavgiq3RHD6RbneCvSlUQf0bhKQJoW@IEWGZ4p3PjC6@v4VXWa@5FmEQ/AodxYl3cS1Va6Ueg07uFvRgrGZw5EePBaqgOtu6RLARbtK62XZOVd3wARGOEeBWozrN1M1FXtySHhclt/3T5p5NS6cLDwIVK208iBG4qj1al7UPTaxwirJk3@oYw6Y93Rx/NAq40ORi4Kbj7NmAdZYy/13cSa3s8JqgHuKKgmeASRrpW0VlEnqODW5NAlDmE1LIPfvfim4TM2HhUb9ao@MqwuJkxMJ7yBselCMGF29kjmDtCRkAec6CIePAZNPgpFYhkf73gCUkvfWQKaCz/S464fGIcdd33Im0rI2R172BS03O6pDmFtYUzt0NM31P/z1i44zX7Hq7zRo6@5NH/EqrwyV@Ww/aZR@a@KP6GGbpBxncv@ndxVa30LNX@HCRXZrCNWqPEZe5YjjP0glOu9LLDYww05b/CdfQ43PzQylJtw2@7FPyZAv3c4lbN4XlLySrk3tJofBhKq3z8sR4LRzIjG4ZFmxIjmXNSIR8fAyIdvTGA98uBdjP4UQnmHjc/M9BViEjxVVe5/BRrA4YndTYGa/cPa0B5Enpvu@JQXo5@lxhqSvx77TDX@mts9ew99N0uSutKnovbqMzt/Mye/vol9nMJ3wutp36Gqun8UMcnAL2IAtaUJium1vlyaPD7@Bw "Python 3 – Try It Online")
101,288	<blockquote> <p>...It's paradox. They left us these technological marvels, yet with all their might and knowledge they failed to prevent their own doom...</p> </blockquote> <p>Excerpt from a lecture by the <em>High Historian of Berlin Falls</em></p> <hr> <p>Welcome to <em>a</em> future. Mankind has brought doom upon themselves, their cities have been flattened by war and weather, and most of the northern hemisphere is radioactive badlands.</p> <p>They've managed to <s>avert</s> revert <a href="http://tvtropes.org/pmwiki/pmwiki.php/Main/GlobalWarming" rel="noreferrer">global warming</a>, in the process creating a global society of an unprecedented scale. Air-travel got reduced to the bare necessities, and the railways underwent a renaissance.</p> <p>Closed stretches of track & stations all over Europe got reopened. Lines between bigger cities got extended to <em>rail-arteries</em><sup>1</sup>. These arteries expanded to stretch all along the northern hemisphere, even connecting Berlin to Boston.</p> <pre><code>Arteries: - Central Europe, Russia, Kazakhstan, Beijing, Bering-Strait, Chicago, Boston - England, Central Europe, Spain, Gibraltar, Morocco - Kazakhstan, Afhganistan, India - Beijing, Hong-Kong, Thailand, Indonesia, Papua New Guinea, Sidney - Beijing, Korea, Japan - Chicago, Mexico, Colombia </code></pre> <p>Due to the lack of electrification of rails on the American, African and Australian continents scientists and engineers spent considerable efforts into advancing emission-free alternatives to <a href="https://en.wikipedia.org/wiki/Diesel_locomotive" rel="noreferrer">diesel-electric engines</a>.</p> <p>A break-through was achieved in the field of <a href="https://en.wikipedia.org/wiki/Stirling_radioisotope_generator" rel="noreferrer">SRG</a> & <a href="https://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator" rel="noreferrer">RTG</a> technology. Taking a hint from space-engineering, <a href="https://en.wikipedia.org/wiki/Radioisotope_heater_unit" rel="noreferrer">Radioisotope Heater Units</a> (RHU) were expanded in size to serve as continuous heating elements in the boilers of <a href="https://en.wikipedia.org/wiki/Steam_turbine_locomotive#Electric_transmission" rel="noreferrer">steam-electric engines</a> - these engines would then be used for trains and ships.</p> <hr> <p>A typical train-engine would consist of a boiler in which 5 RHUs (~6 tons of <a href="https://education.jlab.org/itselemental/ele088.html" rel="noreferrer">Radium</a> per unit<sup>2</sup>) <a href="https://en.wikipedia.org/wiki/Superheated_water" rel="noreferrer">superheat</a> water or another conductor fluid in a primary fluid-cycle. Through conduction the heat in the primary cycle is used to superheat water to steam in a secondary water-cycle, which is then used to drive a turbine<sup>3</sup> producing electricity.</p> <pre><code>┌─────────────────────┐ ┌───────────────┐ │ ┌─┐ ┌─┐ ┌─┐ ┌─┐ ┌─┐ ╞══╗\|╔╡ STEAM TURBINE │ │ │R│ │R│ │R│ │R│ │R│ │ ║\|║└──────────────╥┘ │ │A│ │A│ │A│ │A│ │A│ │ ║\|║ ┌─────────┐ ║ │ └─┘ └─┘ └─┘ └─┘ └─┘ ╞⛒╝\|╚⛒═╡CONDENSER╞═╝ └─────────────────────┘ └─────────┘ </code></pre> <p>Assuming ~168W per kg of Radium<sup>4</sup> and an optimistic efficiency of ~50% this gets us ~2500kW usable energy. Or about ~500kW per RHU.</p> <hr> <p><strong>Q</strong>: Is this concept for an engine workable or are there game-breakers that I missed out on?</p> <p>A <em>good</em> answer:</p> <ul> <li><strong>addresses issues</strong> with the proposed design</li> <li><strong>proposes solutions</strong> to the addressed issues</li> </ul> <hr> <p><sub><sup>1</sup>Lines with sections of up to 8 tracks next to each other in order to facilitate higher throughput. Sort of superhighways but for trains.</sub><br> <sub><sup>2</sup>Which results in cylinders of ~1m diameter and ~2m height (assuming we do not have to interleave the radium with too much other metal to get the heat out efficiently)</sub><br> <sub><sup>3</sup>Similarly to <a href="https://en.wikipedia.org/wiki/Nuclear_power_plant#/media/File:PressurizedWaterReactor.gif" rel="noreferrer">how a Nuclear Power Plant works</a>, also known as <a href="https://en.wikipedia.org/wiki/Rankine_cycle" rel="noreferrer">Rankine Cycle</a>.</sub><br> <sub><sup>4</sup>I've not too much knowledge in the area of nuclear physics, so I <em>designed</em> the described system based on <a href="https://chat.stackexchange.com/transcript/message/41910576#41910576">the very helpful explanations I got from @kingledion on the chat</a>.</sub> </p>	[ { "answer_id": 101311, "author": "Michael Irving", "author_id": 46212, "author_profile": "https://worldbuilding.stackexchange.com/users/46212", "pm_score": 3, "selected": false, "text": "<p>A radiothermal train is a fun idea. Radium may be possible (given futuristic resources), though tr...	2018/01/02	[ "https://worldbuilding.stackexchange.com/questions/101288", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/2746/" ]	> > ...It's paradox. They left us these technological marvels, yet with all their might and knowledge they failed to prevent their own doom... > > > Excerpt from a lecture by the High Historian of Berlin Falls --- Welcome to a future. Mankind has brought doom upon themselves, their cities have been flattened by war and weather, and most of the northern hemisphere is radioactive badlands. They've managed to ~~avert~~ revert [global warming](http://tvtropes.org/pmwiki/pmwiki.php/Main/GlobalWarming), in the process creating a global society of an unprecedented scale. Air-travel got reduced to the bare necessities, and the railways underwent a renaissance. Closed stretches of track & stations all over Europe got reopened. Lines between bigger cities got extended to rail-arteries1. These arteries expanded to stretch all along the northern hemisphere, even connecting Berlin to Boston. ``` Arteries: - Central Europe, Russia, Kazakhstan, Beijing, Bering-Strait, Chicago, Boston - England, Central Europe, Spain, Gibraltar, Morocco - Kazakhstan, Afhganistan, India - Beijing, Hong-Kong, Thailand, Indonesia, Papua New Guinea, Sidney - Beijing, Korea, Japan - Chicago, Mexico, Colombia ``` Due to the lack of electrification of rails on the American, African and Australian continents scientists and engineers spent considerable efforts into advancing emission-free alternatives to [diesel-electric engines](https://en.wikipedia.org/wiki/Diesel_locomotive). A break-through was achieved in the field of [SRG](https://en.wikipedia.org/wiki/Stirling_radioisotope_generator) & [RTG](https://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator) technology. Taking a hint from space-engineering, [Radioisotope Heater Units](https://en.wikipedia.org/wiki/Radioisotope_heater_unit) (RHU) were expanded in size to serve as continuous heating elements in the boilers of [steam-electric engines](https://en.wikipedia.org/wiki/Steam_turbine_locomotive#Electric_transmission) - these engines would then be used for trains and ships. --- A typical train-engine would consist of a boiler in which 5 RHUs (~6 tons of [Radium](https://education.jlab.org/itselemental/ele088.html) per unit2) [superheat](https://en.wikipedia.org/wiki/Superheated_water) water or another conductor fluid in a primary fluid-cycle. Through conduction the heat in the primary cycle is used to superheat water to steam in a secondary water-cycle, which is then used to drive a turbine3 producing electricity. ``` ┌─────────────────────┐ ┌───────────────┐ │ ┌─┐ ┌─┐ ┌─┐ ┌─┐ ┌─┐ ╞══╗\|╔╡ STEAM TURBINE │ │ │R│ │R│ │R│ │R│ │R│ │ ║\|║└──────────────╥┘ │ │A│ │A│ │A│ │A│ │A│ │ ║\|║ ┌─────────┐ ║ │ └─┘ └─┘ └─┘ └─┘ └─┘ ╞⛒╝\|╚⛒═╡CONDENSER╞═╝ └─────────────────────┘ └─────────┘ ``` Assuming ~168W per kg of Radium4 and an optimistic efficiency of ~50% this gets us ~2500kW usable energy. Or about ~500kW per RHU. --- Q: Is this concept for an engine workable or are there game-breakers that I missed out on? A good answer: * addresses issues with the proposed design * proposes solutions to the addressed issues --- 1Lines with sections of up to 8 tracks next to each other in order to facilitate higher throughput. Sort of superhighways but for trains. 2Which results in cylinders of ~1m diameter and ~2m height (assuming we do not have to interleave the radium with too much other metal to get the heat out efficiently) 3Similarly to [how a Nuclear Power Plant works](https://en.wikipedia.org/wiki/Nuclear_power_plant#/media/File:PressurizedWaterReactor.gif), also known as [Rankine Cycle](https://en.wikipedia.org/wiki/Rankine_cycle). 4I've not too much knowledge in the area of nuclear physics, so I designed the described system based on [the very helpful explanations I got from @kingledion on the chat](https://chat.stackexchange.com/transcript/message/41910576#41910576).	A radiothermal train is a fun idea. Radium may be possible (given futuristic resources), though tricky, I'll need to give it more thought. Another fun possibility if you don't mind an actively controlled reactor is a natural uranium source, like in [the CANDU reactors in Canada](http://www.world-nuclear.org/information-library/country-profiles/countries-a-f/canada-nuclear-power.aspx). For passive systems though, I'm going to make my case for Polonium-210. One of the bigger issues of Radium and other seemingly suitable isotopes is the byproducts (or daughters), which are created in that isotope's decay chain. These byproducts would build up constantly in normal use and create technical problems or hazardous conditions. Keep an eye out for long-lived (= obnoxious) daughters, and any beta or gamma decays. To my knowledge, all of the common RTG isotopes have obnoxious byproducts, sadly, with one exception. If you're willing to hand-wave the production of the isotope, 210Po is rather ideal. It decays directly to a stable isotope of lead-208 through a low-ish energy alpha decay which is quite easy to catch and generate heat from. The alpha particles mostly stop with only a few cm of air, or completely stop in a few mm of water. Polonium-210 has an extreme activity, allowing smaller weights of it to be viable, even on a large train. From my back-of-the-envelope calculations, it would take 'only' about 40-70kg per train (an amount which would fill a ~6in cube). As a note, producing this with modern technology is flatly impossible. If it's easier in the future though... One convenience of Polonium is that it's fairly noble as a metal, in other words it doesn't rust or dissolve well in water unless there's a bunch of chloride in the solution. For this reason, it could be used in small chunks or even possibly as a thin (mm) plating of solid metal in the boiler or on the walls of the heat exchanger. If you wanted to use it in water solution instead, it's soluble in 3%HCl, or more simply in EDTA (like in shampoo). Without either HCl or EDTA (or similar) it automatically tries to plate itself out of water solutions as metallic Polonium. A downside of HCl is it attacks Copper and Iron, common heat exchanger materials. A radiothermal train would be producing heat constantly, so it would need to be constantly boiling water, even when not moving. This could be very obnoxious, because water tends to leave deposits and scales on boiler / heatEx equipment and without an obvious opportunity to clean them they could become ineffective or (frighteningly in this case) leaky. Because Polonium-210 has an extraordinary activity and decent bioabsorption, it's a nefarious toxin (worse than cyanide). The good news is it has a very short halflife (138 days), so spills would lose toxicity within decade. The immediate effects would be devastating though, and would travel freely with ground water if using the solution form. Also because of Polonium's short halflife, the trains would need to be refilled regularly, perhaps making the 'chunk' version more appealing. Lastly, the alpha particles would cause wild amounts of embrittlement in any metals within striking distance. The Polonium would need to be held well separate from anything critical. I think I could keep going for a while about little quibbling engineering problems a radiothermal train would face, but it's wonderful concept that doesn't break any major laws of physics while having just enough troubles to make it interesting for the people stuck aboard. Math for amount of fuel required on a radiothermal steam engine: 2ton coal /hr [reference](https://www.quora.com/How-much-coal-does-a-steam-locomotive-use-per-hour]) 19.48 \10^6 BTU / ton coal [reference](https://www.eia.gov/tools/faqs/faq.php?id=72&t=2) 1055 J/BTU , 3600 s/hr ~6MW heat 141W/gm Po-210 [reference](http://mragheb.com/NPRE%20402%20ME%20405%20Nuclear%20Power%20Engineering/Radioisotopes%20Power%20Production.pdf) 42kg Polonium-210 per train. Polonium's quite dense at ~9g/cm^3 resulting in something like a 17cm cube of polonium. A cube would explode though, so let's assume small chunks or a plating. Best of luck with your world! Also, I really like your ascii art. Edit:* I noticed that a train to last through a nuclear winter would be handy, so I put a bit more work into this. It seems that Sr-90 would also be appropriate, with the advantage that it has a much longer (29yr) half life. A train would require about 1500kg of it, and beneficially it's available in large amounts in nuclear waste. Sr-90 undergoes beta decay (medium-nasty radiation) to make a daughter which also quickly beta decays to something nice and stable. Beta radiation is best caught by acrylic plastic, though a few cm of water would work as well.
101,837	<h1>Introduction</h1> <p><em>For more backstory, see <a href="https://worldbuilding.stackexchange.com/questions/100613/can-you-design-your-own-plants-without-a-computer">here</a> and <a href="https://worldbuilding.stackexchange.com/questions/101519/how-high-def-can-my-tv-be-without-computers">here</a></em></p> <p>The 438th Harmonious Congress of the People of Mars was perhaps the most anticipated since the early years of the settlement. In a rare action, the Supreme Council of Harmony agreed to broadcast some of the proceedings of the Congress on tele-projector for all the tens of millions of Martians to witness. The occasion was, of course, significant. The Chief Designer was presenting to the Council, and indeed to all the people, a new 100 Year Plan for the Revivification of Mars. </p> <p>There was a great buzz and anticipation in the air. Rumors flew that some great milestone had been met in the construction of an atmosphere. Already, if you received permission to surface walk outside the airlocks, you could see the fruits of the Bureau of Revivification. In the lowest latitudes, slender pine trees thrust skyward from the red dirt. In more seasonal climes, grass bloomed in great billows of green during spring. Running water could be seen for part of the year anywhere within 30 degrees of the Equator. </p> <p>People had not been outside for generations stretching back to Old Earth. The first colonists had dug into dormant volcanoes and the cliff faces of vast chasms. Over the centuries, millions of miles of passages and corridors were extended under the surface. No one walked on the surface for centuries, save a few scientists perhaps. But in the past few decades, the air pressure had gotten so high-pressure suits were barely thicker than regular clothes. A rupture was no longer catastrophic. </p> <p>All Mars waited with anticipation the speech from the Chief Designer. What would she propose? What was the next step for Mars? Was it possible that a Green and Blue Mars, a truly habitable Mars, would soon be a reality?</p> <h1>Question</h1> <p>The Martian air pressure is above 10 kPa. The massive amounts of carbon dioxide available on the surface of the planet have all been vaporized. Nuclear driven oxygen synthesis has greatly sped the conversion of this carbon dioxide to oxygen, and widespread plant life is contributing its part. It will not be long until oxygen levels are 50% that of Earth; equivalent to 5 km altitude on Earth. High enough to be considered habitable and breathable to humans. </p> <p>The Chief Designer and her team have decided that it is time to raise the atmospheric pressure on Mars. In order to do this, they will need to generate about 40 kPa of air pressure from some inert gas.</p> <p><strong>Given the energy cost of transporting an inert gas from somewhere else in the solar system, and the energy cost of any chemical reactions needed to put it in the atmosphere, what is the least energy expensive way to add 40 kPa of air pressure to Mars?*</strong></p> <p>For example, if the best gas is diatomic nitrogen, then the cost of transportation from a source in the outer solar system as well as the cost of turning whatever nitrogen compounds can be found into the diatomic gas must be considered.</p> <h3>Considerations</h3> <ul> <li>The Earth was hit by a large bolide 500 years ago. It is still glowing. Earth's former atmosphere and oceans are not available to be moved to Mars.</li> <li>Any other resources in the solar system are available.</li> <li>The O$_2$ and CO$_2$ information in the question are presented as facts; they are not relevant to the discussion.</li> <li>Technology level is near-future but mostly irrelevant. The correct answer will give an energy cost in Joules (or Calories, I suppose, if you like to be contrarian).</li> <li>Energy cost only has to consider the cost of moving the materials; a function of mass and whatever combinations of delta-v's will get it from its current location to Mars. The cost of rockets and fuels and such can be transparent.</li> </ul>	[ { "answer_id": 101847, "author": "D.J. Klomp", "author_id": 46462, "author_profile": "https://worldbuilding.stackexchange.com/users/46462", "pm_score": 2, "selected": false, "text": "<p>I found you a moon: <strong>Mimas</strong></p>\n\n<p>Since I couldn't sleep I thought I would do some ...	2018/01/09	[ "https://worldbuilding.stackexchange.com/questions/101837", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/23519/" ]	Introduction ============ For more backstory, see [here](https://worldbuilding.stackexchange.com/questions/100613/can-you-design-your-own-plants-without-a-computer) and [here](https://worldbuilding.stackexchange.com/questions/101519/how-high-def-can-my-tv-be-without-computers) The 438th Harmonious Congress of the People of Mars was perhaps the most anticipated since the early years of the settlement. In a rare action, the Supreme Council of Harmony agreed to broadcast some of the proceedings of the Congress on tele-projector for all the tens of millions of Martians to witness. The occasion was, of course, significant. The Chief Designer was presenting to the Council, and indeed to all the people, a new 100 Year Plan for the Revivification of Mars. There was a great buzz and anticipation in the air. Rumors flew that some great milestone had been met in the construction of an atmosphere. Already, if you received permission to surface walk outside the airlocks, you could see the fruits of the Bureau of Revivification. In the lowest latitudes, slender pine trees thrust skyward from the red dirt. In more seasonal climes, grass bloomed in great billows of green during spring. Running water could be seen for part of the year anywhere within 30 degrees of the Equator. People had not been outside for generations stretching back to Old Earth. The first colonists had dug into dormant volcanoes and the cliff faces of vast chasms. Over the centuries, millions of miles of passages and corridors were extended under the surface. No one walked on the surface for centuries, save a few scientists perhaps. But in the past few decades, the air pressure had gotten so high-pressure suits were barely thicker than regular clothes. A rupture was no longer catastrophic. All Mars waited with anticipation the speech from the Chief Designer. What would she propose? What was the next step for Mars? Was it possible that a Green and Blue Mars, a truly habitable Mars, would soon be a reality? Question ======== The Martian air pressure is above 10 kPa. The massive amounts of carbon dioxide available on the surface of the planet have all been vaporized. Nuclear driven oxygen synthesis has greatly sped the conversion of this carbon dioxide to oxygen, and widespread plant life is contributing its part. It will not be long until oxygen levels are 50% that of Earth; equivalent to 5 km altitude on Earth. High enough to be considered habitable and breathable to humans. The Chief Designer and her team have decided that it is time to raise the atmospheric pressure on Mars. In order to do this, they will need to generate about 40 kPa of air pressure from some inert gas. Given the energy cost of transporting an inert gas from somewhere else in the solar system, and the energy cost of any chemical reactions needed to put it in the atmosphere, what is the least energy expensive way to add 40 kPa of air pressure to Mars?\* For example, if the best gas is diatomic nitrogen, then the cost of transportation from a source in the outer solar system as well as the cost of turning whatever nitrogen compounds can be found into the diatomic gas must be considered. ### Considerations * The Earth was hit by a large bolide 500 years ago. It is still glowing. Earth's former atmosphere and oceans are not available to be moved to Mars. * Any other resources in the solar system are available. * The O$\_2$ and CO$\_2$ information in the question are presented as facts; they are not relevant to the discussion. * Technology level is near-future but mostly irrelevant. The correct answer will give an energy cost in Joules (or Calories, I suppose, if you like to be contrarian). * Energy cost only has to consider the cost of moving the materials; a function of mass and whatever combinations of delta-v's will get it from its current location to Mars. The cost of rockets and fuels and such can be transparent.	I found you a moon: Mimas Since I couldn't sleep I thought I would do some of the math so here it goes: ``` Radius_Mars = 3390 * 10^3 %in meter Thickness_Atm = 66 10^3 %Earth atomosphere is about 100km, took 2/3 for mars in meters Volume_Atm = 4/3pi(Radius_Mars+Thickness_Atm)^3 - 4/3piRadius_Mars^3; Volume_Atm = 9.7E18 m^3 Air_Density = 1.2 %kg/m^3 Needed_Mass = 0.3Air_DensityVolume_Atm; %3.4E18 kg Needed_Mass = 3.4E18 kg ``` So you need a mass of 3.4E18 kg to shoot from some moon (according to [wiki](https://en.wikipedia.org/wiki/Asteroid_belt)the astroids in the belt are mainly of C, S and M type so unsuitable), so find an ice moon with the lowest gravity. It would seem that Mimas orbiting Saturnus is mostly ice and has a surface as small as Spain. The mass of Mimas is 3.7E19 kg so only one order of magnitude higher. So instead of having to deal with escape velocity simply move to complete moon to Mars, the it will only become a question of how fast do you want it. So if you have patience for a 10 years you have to move the intervening distance between Saturn and Mars, being roughly 1.2E9 km. So your average speed, taking into account that you need to decelerate for just as long would need to be ``` average velocity = 1.2E12/31E7 = 3834 m/s ``` So to calculate the energy just use the formula for kinetic energy ``` energy = 1/2mv^2 ``` So the needed energy becomes: ``` energy = 1/23.7E19*3834^2 = 2.719E26 J ``` To put it into prespective if you harness all the solar radiation falling on earth you would need to harvest it at a 100% efficiency for 12.4 years to get the required energy. So I guess we won't be moving planets any time soon :D. Since it is late it might be good to check the numbers.
102,787	<p><a href="https://i.stack.imgur.com/pvnAW.gif" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/pvnAW.gif" alt="enter image description here"></a> Notice that most of the energy is absorbed by the inside with considerable little damage to the outside. I base this question on the premise of would the Earth and asteroid would act similar raising the temperature of the Earth with less surface catastrophic damage except for the Water evaporating from underground. </p> <p>Using the Bible as a historical record. It says that before Noah's flood people lived to be around a thousand years old about 1000B.C. Therefore, either people really lived to be that old or perhaps the Earth spun much faster at that time. Shortly after the flood human life span dropped to 120 years to more-or-less what we experience today. Could pollutants than was released along with the water released from the Earth shorten the life the span of a person?</p> <p>It also said that was the first time it rained is when the Biblical flood started and the first rainbow was witnessed when it stopped. I'm sure there were other survivors around the world but for this region of Earth this is what people experienced.</p> <p>Therefore, could it be possible that:</p> <ul> <li><p>An asteroid hit at an angle to slow the Earth's rotation and to increase its axial tilt to give birth to seasons? With the Earth suspended in space some or more of the asteroid's inertia would transfer to Earth rotational or orbital inertia.</p></li> <li><p>An asteroid passed through the crust like a bullet causing little damage externally but changing the magma flow to decelerate the Earth's rotation? It would still leave a creator but the bulk of the impact would be absorbed by the inside of the Earth. </p></li> <li><p>An asteroid struck such that the polar caps melted or the water was forced out of the oceans?</p></li> </ul> <p>The Earth can physically have 1.7 hour days before spinning apart. I understand speed, composition, angle crust depth and many other factors would change the outcome of an impact. I am looking for a scenario where it not the end of all life, but significantly changed the Earth. </p> <p><a href="https://i.stack.imgur.com/kwYKE.gif" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/kwYKE.gif" alt="enter image description here"></a></p> <p>By some possibility this could be how an asteroid could react to the Earth's surface depending on angle. </p>	[ { "answer_id": 102796, "author": "Loren Pechtel", "author_id": 264, "author_profile": "https://worldbuilding.stackexchange.com/users/264", "pm_score": 4, "selected": false, "text": "<p><em>Therefore, could it be possible that</em>:</p>\n\n<ul>\n<li><em>An asteroid hit at an angle to slow...	2018/01/21	[ "https://worldbuilding.stackexchange.com/questions/102787", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/27786/" ]	[![enter image description here](https://i.stack.imgur.com/pvnAW.gif)](https://i.stack.imgur.com/pvnAW.gif) Notice that most of the energy is absorbed by the inside with considerable little damage to the outside. I base this question on the premise of would the Earth and asteroid would act similar raising the temperature of the Earth with less surface catastrophic damage except for the Water evaporating from underground. Using the Bible as a historical record. It says that before Noah's flood people lived to be around a thousand years old about 1000B.C. Therefore, either people really lived to be that old or perhaps the Earth spun much faster at that time. Shortly after the flood human life span dropped to 120 years to more-or-less what we experience today. Could pollutants than was released along with the water released from the Earth shorten the life the span of a person? It also said that was the first time it rained is when the Biblical flood started and the first rainbow was witnessed when it stopped. I'm sure there were other survivors around the world but for this region of Earth this is what people experienced. Therefore, could it be possible that: * An asteroid hit at an angle to slow the Earth's rotation and to increase its axial tilt to give birth to seasons? With the Earth suspended in space some or more of the asteroid's inertia would transfer to Earth rotational or orbital inertia. * An asteroid passed through the crust like a bullet causing little damage externally but changing the magma flow to decelerate the Earth's rotation? It would still leave a creator but the bulk of the impact would be absorbed by the inside of the Earth. * An asteroid struck such that the polar caps melted or the water was forced out of the oceans? The Earth can physically have 1.7 hour days before spinning apart. I understand speed, composition, angle crust depth and many other factors would change the outcome of an impact. I am looking for a scenario where it not the end of all life, but significantly changed the Earth. [![enter image description here](https://i.stack.imgur.com/kwYKE.gif)](https://i.stack.imgur.com/kwYKE.gif) By some possibility this could be how an asteroid could react to the Earth's surface depending on angle.	I'll try to contribute, trying to omit what others have already mentioned; The first issue I want to mention is your idea that an asteroid would 'go through' Earth just as the bullet does through the high-tech jelly. This analogy is deeply flawed due to one simple thing that you have ignored: There is actually a lot of physics involved in stopping something when hitting something else, but it can all be broken down to a rule-thumb: For high-velocity impacts, if the density contrast between impactor and impactee is high, one will ignore the other. If not, both break apart. (Over at astronomy we think a lot about impacts) What do I mean by this? See the bullet is much denser than the medium it is shot into. But 'much' I'm talking about around a factor of 5-10 density contrast. After the initial expansion shock visible in the animation, the gel medium more or less ignores the bullet. The same thing would happen If you shoot a bullet into water (well, because it has nearly the same density as the gel),or air (duh, but the principle still applies). Now if you shoot it at something even denser, like a brick, or a metal plate, the bullet will not penetrate anymore. Now imagine the bullet is a meteor and doesn't have the same material strength as the bullet, then it will simply fly apart. Large rocks ($\ge 100 km$) in space have comparable densities, so they will always be ripped apart, never penetrate. Smaller rocks will always be ripped apart, without affecting Earth significantly, because they have similar density, but the small rock also has much less momentum. I mentioned this to maybe guide your thinking in physical terms: Density contrast and momentum (but that was already mentioned in other answers). I find most of your questions that you had in the comments in your physics.se answerable just by looking at this principle. If you want to, this can be a valuable tool in world-building, as well as in bible studies, depending what your aim is. So what you want to do is essentially send a mini-black hole through earths crust and still keep the solar system and the planetary atmosphere in a good shape after that. That would be a tough one. For your other questions, I will just briefly comment on, as correct answers already exist: ``` 1.) An asteroid hit at an angle to slow the Earth's rotation and to increase its axial tilt to give birth to seasons? 2.) An asteroid passed through the crust like a bullet causing little damage externally but changing the magma flow to decelerate the Earth's rotation? It would still leave a creator but the bulk of the impact would be absorbed by the inside of the Earth. 3.) An asteroid struck such that the polar caps melted or the water was forced out of the oceans? ``` 1.) As others said, that's not possible. But I think the other answers underappreciated how NOT POSSIBLE this is. To go from a 1.7 hrs rotation period with the whole mass of Earth to 24 hrs in one impact would deposit a lot of kinetic energy in the crust. So much in fact that the energy deposited would easily reach the gravitational binding energy of the planet. Meaning: This would be an impact that could rip the planet apart. It wouldn't just be catastrophic, apocalyptic or hyper-bad. It would be fatal. I can show you the math if you're interested, it's simple. And as soon as you go down in impact energy, you can't produce the slow-down anymore that your source is citing. I have discussed 2.) above already. 3.) is an entirely possible scenario, and probably happened multiple times during Earth's early history, during the [Late heavy bombardment period](https://en.wikipedia.org/wiki/Late_Heavy_Bombardment). However it is important, that this happens before the development of complex life, or else everything has to start from zero again. To give you a sense of comparison, the K-Pg impactor (the Dinosaur Killer, around $\rm 10 km$ in size) wouldn't have near enough energy to affect the polar caps significantly or to evaporate any ocean. To do this, you need a bigger meteorite (or asteroid with $\rm \ge 100km$ size, as you asked for) and then consequences are again dire: The splash energy (and as discussed, the density principle needs it to be a splash) would be incredible, melt the whole surface, even eject a good part of the atmosphere mechanically. But only after that comes my favourite part: Atmospheric escape. The extremely hot surface would heat the atmosphere to temperatures where it can [escape in bulk](https://en.wikipedia.org/wiki/Hydrodynamic_escape). Summarizing No impactor scenario that I can think of fulfills all the possible consequences that you need in your story. * Of course you can leave out the part with changing the rotation period of the planet, because that places the hardest physical bound on a planet-destroying impact. * The 'going-through-Earth' thing would also have to be abandoned on a realistic ground. Except you want to invoke really many rogue neutron stars / black holes flying around in the universe and hitting Earth by chance. * Melting the polar caps / evaporating the oceans should be fine, but then you have to live with the other consequences as well. Or you magic them away.
102,874	<p>If a bow was made of steel and shaped like a Old Mongolian Bow with a draw weight of around 1000 lbs was made in proportion to a 9 foot tall humanoid (assume strength is enough to pull bow normally and the bow and arrow is roughly double regular size) what sort of force, speed, ect. would the arrow achieve? (Assume the arrow could survive these forces or adjust the arrow as needed)</p>	[ { "answer_id": 102886, "author": "Josh King", "author_id": 21041, "author_profile": "https://worldbuilding.stackexchange.com/users/21041", "pm_score": 0, "selected": false, "text": "<p>So 1,000lb is grossly oversized.</p>\n\n<p>Average draw weights for normal bows are in the 40-55lb rang...	2018/01/22	[ "https://worldbuilding.stackexchange.com/questions/102874", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/46400/" ]	If a bow was made of steel and shaped like a Old Mongolian Bow with a draw weight of around 1000 lbs was made in proportion to a 9 foot tall humanoid (assume strength is enough to pull bow normally and the bow and arrow is roughly double regular size) what sort of force, speed, ect. would the arrow achieve? (Assume the arrow could survive these forces or adjust the arrow as needed)	First of all, some conversions to make the physics easier: ========================================================== ``` 500 lbs ~= 225 kg 43.2 in ~= 1.1 m ``` Okay, now why these numbers? ============================ Bows are basically springs, meaning that they follow Hooke's Law reasonably well. Hook's law states that $F=ks$ where $F$ is force, $k$ is a constant related to the spring and $s$ is how far you've stretched the string. Now I'm going to make an assumption that's wrong, but will make all of this much easier. I'm going to assume that your bow begins from a state of rest, meaning that it starts at $s=0$. This is wrong, because the bowstring does impart some force onto the bow, creating some tension before you even begin to draw, but since this whole exercise is an estimate, I don't think this will affect our end results much. In physics, work is defined as $W=F\_{avg}s$. Here's where that assumption comes into the picture. Since the force exerted by the bow is linear, if it starts at a state of rest, then the average force is just half the maximum force. That means that the average force exerted while pulling back your hypothetical bow is 500 lbs, because that is half of 1000 lbs (the max force during draw). Now we need $s$, or the draw length. [This site](http://www.lancasterarchery.com/blog/what-size-recurve-bow-is-right-for-me/) tells us that the length from fingertip to finger tip divided by 2.5 should be the proper draw length. For our 9 foot tall humanoid, that's $(9\12)/2.5=43.2$. Using the conversions above that's $F\_{avg}=225$ and $s=1.1$. Now plug it in ============== Plugging our numbers into our formula above, we get $W=F\_{avg}s=225\1.1=247.5\ Joules$. Not all of that is going to go into sending the arrow forward. A lot of it is wasted by making the arrow oscillate and some heating of the bow. [According to this site](https://www.wired.com/2014/12/much-energy-bow-goes-kinetic-energy-arrow/), only 54.8% of the energy goes into the arrow. So, $E\_{arrow}=W\_{bow}\.548=247.5\.548=135.6\ Joules$. So how fast is it going finally? ================================ Now kinetic energy is defined as $E\_k=(1/2)mv^2$ so now all we need is the weight of the arrow. [This guy](http://www.archerytalk.com/vb/showthread.php?t=780567) wanted some help with the weight of his arrow, and his community was helpful enough to let him know it was ~375 grains... which is apparently a unit of weight? Anyway apparently that's about 24 grams. I'm going to go with a crude "let's double its size!" calculation. Doubling the size makes the volume increase by a factor of 8, and the weight by the same, so the weight of our extra large arrow is 194 grams. Note that double the size is 56 inches, which isn't too much longer than our draw length, sounds good to me! Now throwing that in the equation, we get $135.6=(1/2)\.194\v^2$. Solving for $v$ gets us about 37 meters per second or about 80 mph!
103,567	<p>Natural uranium (NU) is a mixture of about 0.7% $\ ^{235}U$ (fissile) and 99.3% $\ ^{238}U$ (non-fissile). To create uranium-based nuclear weapons NU has to undergo a process called enrichment in order to increase the ratio of fissile uranium. </p> <p>Today the ratio of fissile uranium in NU is about 0.7%. However, $\ ^{235}U$ decays faster than the non-fissile $\ ^{238}U$:</p> <p>$\ ^{235}U$ has a half-life of <a href="http://www.nndc.bnl.gov/nudat2/reCenter.jsp?z=92&n=143" rel="nofollow noreferrer">$7.04\cdot10^8$</a> years.<br> $\ ^{238}U$ has a half-life of <a href="http://www.nndc.bnl.gov/nudat2/reCenter.jsp?z=92&n=146" rel="nofollow noreferrer">$4.46\cdot10^9$</a> years. </p> <p>and perhaps a few billion years ago natural uranium was already weapons-usable without the need for enrichment. </p> <hr> <p><strong>Questions:</strong> </p> <ul> <li><p>Is my assumption correct? Would it be possible to have weapons-grade NU in the past? Say 4.5 billion years ago, when our planet was created. </p></li> <li><p>Could nuclear terrorism be a threat to the existence of extraterrestrial civilizations that form on a planet where NU is already weapons-usable without need for enrichment?</p></li> </ul> <p><sub><strong>Note:</strong> I'm asking because I'm wondering if it's possible that some extraterrestrial civs have evolved in planets with enriched NU. This question is <em>not</em> about humans; our past is history.</sub> </p>	[ { "answer_id": 103568, "author": "user", "author_id": 13688, "author_profile": "https://worldbuilding.stackexchange.com/users/13688", "pm_score": 3, "selected": false, "text": "<h2>TL;DR</h2>\n<p><strong>Probably yes</strong>, natural uranium (NU) is usable in weapons in "young&quot...	2018/01/30	[ "https://worldbuilding.stackexchange.com/questions/103567", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/13688/" ]	Natural uranium (NU) is a mixture of about 0.7% $\ ^{235}U$ (fissile) and 99.3% $\ ^{238}U$ (non-fissile). To create uranium-based nuclear weapons NU has to undergo a process called enrichment in order to increase the ratio of fissile uranium. Today the ratio of fissile uranium in NU is about 0.7%. However, $\ ^{235}U$ decays faster than the non-fissile $\ ^{238}U$: $\ ^{235}U$ has a half-life of [$7.04\cdot10^8$](http://www.nndc.bnl.gov/nudat2/reCenter.jsp?z=92&n=143) years. $\ ^{238}U$ has a half-life of [$4.46\cdot10^9$](http://www.nndc.bnl.gov/nudat2/reCenter.jsp?z=92&n=146) years. and perhaps a few billion years ago natural uranium was already weapons-usable without the need for enrichment. --- Questions: * Is my assumption correct? Would it be possible to have weapons-grade NU in the past? Say 4.5 billion years ago, when our planet was created. * Could nuclear terrorism be a threat to the existence of extraterrestrial civilizations that form on a planet where NU is already weapons-usable without need for enrichment? Note: I'm asking because I'm wondering if it's possible that some extraterrestrial civs have evolved in planets with enriched NU. This question is not about humans; our past is history.	TL;DR ----- Probably yes, natural uranium (NU) is usable in weapons in "young" [note 1] solar systems. (not weapons-grade, but weapons-usable) Probably yes, terrorists would have a much easier time creating (crude) nuclear weapons. Whether not needing enrichment would hinder or help civilizations prosper and survive is uncertain since there are both problems (terrorism, nuclear proliferation) and benefits (cheaper nuclear energy). --- NU enrichment levels -------------------- 2 billion years ago NU was enriched enough to sustain a nuclear chain reaction ([Oklo cave](https://apod.nasa.gov/apod/ap100912.html) was probably a natural nuclear reactor) 4.5 billion years ago natural uranium was already enriched enough (~23%) to be used in weapons without the need for further enrichment (although enrichment would still be beneficial). Using the code at the bottom we get the following results: ``` 2 billion years ago natural uranium was 3.7% enriched. 4 billion years ago, 16.7%. 5 billion years ago (about the age of our solar system) 31%. 6 billion years ago, 51%. ``` On the other hand we are not quite certain how life on earth formed and perhaps there is a time threshold on how fast life can form in a freshly created solar system, eg. requiring at least 1 billion years for multicellular organisms to form etc. By going into an even earlier period higher enrichments are possible but probably unlikely, since $\ ^{235}U$ and $\ ^{238}U$ are created through the [r-process](https://www.physics.ohio-state.edu/%7Entg/6805/slides/rprocess.pdf) and their abundance when created is probably not that different (about [1.5 $\frac{\ ^{235}U}{\ ^{238}U}$](http://large.stanford.edu/courses/2013/ph241/roberts2/) = 60% enrichement in supernovas). By comparison U used in nuclear reactors is about [3-5%](https://www.nrc.gov/materials/fuel-cycle-fac/ur-enrichment.html), meaning that both state-owned nuclear weapons and nuclear reactors are widespread in planets that are "young". So, yes. Natural uranium was weapons-usable and perhaps is weapons-usable in other "young" solar systems as we speak. Is the relative age the only way to have enriched NU? If uranium can be transfered to a planet by asteroids or comets just like [water on Earth](https://www.space.com/27969-earth-water-from-asteroids-not-comets.html), then "young" age is not the only way to have planets with enriched NU. Nuclear terrorism ----------------- When it comes to terrorists (today): > > once they have [the nuclear material], [80% or more of the way](https://youtu.be/zVhQOhxb1Mc?t=48m46s) [to a crude nuclear bomb] > > > [Also](https://youtu.be/MnW7DxsJth0?t=24m39s), > > once enriched from 0.7% U-235 to 4.5%, ~3/4 of the work of going to 90% U-235 is done > > > > > having a stock of LEU could allow a country to enrich to HEU more quickly, or with a smaller, easier-to-hide facility > > > Meaning that the greatest obstacle is U enrichment. With that out of the way, everything becomes much easier! Both nuclear proliferation and terrorism would be increased. Perhaps that's an extra [great filter](https://waitbutwhy.com/2014/05/fermi-paradox.html) for civilizations on young solar systems. Once they've solved the terrorism/wars issue naturally enriched U is a blessing instead. Perhaps one day we'll be able to detect nuclear detonations from distant solar systems and we'll find out. Note 1: "young" compared to when the nearby supernova exploded creating its elements (including the U). Note 2: I answered my own question so that you can check it. If you find any mistakes, let me know. --- Python code used for the above results: ``` SECONDS_PER_YEAR = 365246060 BILLION_YEARS_TO_SECONDS = SECONDS_PER_YEAR 1e9 U235_halflife = 7.04e8 * SECONDS_PER_YEAR # http://www.nndc.bnl.gov/nudat2/reCenter.jsp?z=92&n=143 U238_halflife = 4.468e9 * SECONDS_PER_YEAR # http://www.nndc.bnl.gov/nudat2/reCenter.jsp?z=92&n=146 U235_TO_U238_RATIO = 0.720 / 100 # https://physics.nist.gov/PhysRefData/Handbook/Tables/uraniumtable1.htm # -------------------------------- # CHANGE THIS VALUE: bil_years = 5 # # -------------------------------- u235_halflives = BILLION_YEARS_TO_SECONDS * bil_years / U235_halflife u238_halflives = BILLION_YEARS_TO_SECONDS * bil_years / U238_halflife # If there are 0.0072 parts of U-235 for every 1 part of natural U # then we calculate the "initial" quantity (a few billion years ago) quantity_235 = U235_TO_U238_RATIO * 2 ** u235_halflives quantity_238 = (1-U235_TO_U238_RATIO) * 2 ** u238_halflives ratio_235_238 = quantity_235 / quantity_238 print('Billion years: {}\n'.format(bil_years)) print('235 quantity: {:.3}'.format(quantity_235)) print('238 quantity: {:.3}'.format(quantity_238)) print('ratio_235_238: {:.3}'.format(ratio_235_238)) enrichment = quantity_235 / (quantity_235 + quantity_238) print('enrichment: {:.1%}'.format(enrichment)) ```
103,686	<p>I'm trying to design a world in the Alcyone A system of the Pleiades.</p> <p><a href="https://en.wikipedia.org/wiki/Alcyone_(star)" rel="nofollow noreferrer">Alcyone A</a> consists of three stars. The main star is 3.4-3.8 solar masses. There is a very low mass star < 15 million miles away which orbits every 4 days. There is another star ~ 480 million miles away which orbits every 830 days. It is about 1.7-1.9 solar masses.</p> <p>I want to have a habitable planet/moon in this system. The main star has ~2400x solar luminosity, so I think by that measure the planet needs to be about 50 AU from the main star. But it also needs to be far enough from the two main stars to be in a stable orbit. Is there a range that is close enough to be habitable but far enough away to be stable? Could a moon of a gas giant be warm enough for tidal heating?</p> <p>I understand that a blue giant star like this doesn't have a long enough lifespan for life to evolve, but that's OK. I just need a habitable planet suitable for terraforming/colonization.</p>	[ { "answer_id": 103690, "author": "Mark", "author_id": 278, "author_profile": "https://worldbuilding.stackexchange.com/users/278", "pm_score": 2, "selected": false, "text": "<p>Going with the <a href=\"https://en.wikipedia.org/wiki/Circumstellar_habitable_zone#Solar_System_estimates\" rel...	2018/01/31	[ "https://worldbuilding.stackexchange.com/questions/103686", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/29133/" ]	I'm trying to design a world in the Alcyone A system of the Pleiades. [Alcyone A](https://en.wikipedia.org/wiki/Alcyone_(star)) consists of three stars. The main star is 3.4-3.8 solar masses. There is a very low mass star < 15 million miles away which orbits every 4 days. There is another star ~ 480 million miles away which orbits every 830 days. It is about 1.7-1.9 solar masses. I want to have a habitable planet/moon in this system. The main star has ~2400x solar luminosity, so I think by that measure the planet needs to be about 50 AU from the main star. But it also needs to be far enough from the two main stars to be in a stable orbit. Is there a range that is close enough to be habitable but far enough away to be stable? Could a moon of a gas giant be warm enough for tidal heating? I understand that a blue giant star like this doesn't have a long enough lifespan for life to evolve, but that's OK. I just need a habitable planet suitable for terraforming/colonization.	Stable ====== I ran this simulation using [Rebound](http://rebound.readthedocs.io/en/latest/index.html), and orbital particle simulator. You can find the code I used for your simulation at my [github](https://github.com/kingledion/worldbuilding), under the file `orbit_ryanrussel_180131.py`. These are the initial conditions that I used: ``` m_alc_a = 3.6 # As a fraction of the mass of the sun m_alc_b = 0.1 m_alc_c = 1.8 m_planet = 3e-6 a_alc_b = 0.16 # AU a_alc_c = 5 a_planet = 50 e_alc_b = 0.01 e_alc_c = 0.01 e_planet = 0.01 ``` Those are the mass, semi-major axis, and eccentricity of each of your objects, which I labeled alc\_a, alc\_b, and alc\_c. The planet's info is in planet. The planet is the same size as Earth, and the stars are as you specified. Masses are in multiples of the Sun's mass, distances are in AU. For the 'low mass star' I used a red dwarf of 0.1 solar masses, as the results will show, I don't think the mass there really mattered. This ended up being by far the most stable simulation I've run. Usually I like to post graphics of orbits or cool orbital resonances, but there were none. Just three concentric circles. The three orbiting objects (two stars and a planet) have not changed their semi-major axis or eccentricities by even 0.01% in the simulation, so I think we can assume that the planet is sufficiently far away not to be bothered by any of the stars. So far the simulation has run for 47 million years as I'm typing this. I don't think I'll let it go any farther, since your planets are obviously stable.
103,709	<p>Humans like to explore and seem to have an almost instinctual need to expand. After spreading throughout the solar system and even into the Oort Cloud they decided that humanity should follow the robot probes out into the galaxy. </p> <p>Without FTL, but having discovered a form of artificial gravity and having experience creating space habitats, they create a number of generation ships. These massive structures are initially given a population and crew of 30,000, with room to expand to 50,000, and each one has all the tools and manufacturing capabilities to make more generation ships and space habitats, along with the ability to terraform a planet. </p> <p>Strapping on a few large meteors with ice, minerals and other things they may need in an emergency, these ships slowly make their way to the nearest solar system. Slow being a little less than half the speed of light, thanks to getting a very large boost as they start their journey.</p> <p>Once there, they get to work making comfortable habitats for the now increased and cramped population using the resources of the system. They spend several decades there, creating a working system of habitats and making any repairs that are needed on the generation ships. After a century or two, the generation ships, possibly a few new ones as well, get crewed by people who want to travel and move onto the next solar system to do the same thing all over again. Eventually the fleet splits into two and each one does the same thing, eventually splitting again, and again and again. </p> <p>If they find a planet that looks like it can be terraformed, a planet with no life, or only the most basic of bacteria which is wiped out, they get to work making the planet livable for the people who want to have a sky over their head. Any planet with multicellular life is carefully studied by probes, but left otherwise alone because the risk of contamination, allergies, etc, are too great for the ships, and terraforming them will destroy the ecosystem. </p> <p>Is this a realistic way to colonize and explore the universe? </p>	[ { "answer_id": 103711, "author": "Kilisi", "author_id": 22207, "author_profile": "https://worldbuilding.stackexchange.com/users/22207", "pm_score": 4, "selected": false, "text": "<blockquote>\n <p>Is this a realistic way to colonize and explore the universe?</p>\n</blockquote>\n\n<p>Sur...	2018/02/01	[ "https://worldbuilding.stackexchange.com/questions/103709", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/46938/" ]	Humans like to explore and seem to have an almost instinctual need to expand. After spreading throughout the solar system and even into the Oort Cloud they decided that humanity should follow the robot probes out into the galaxy. Without FTL, but having discovered a form of artificial gravity and having experience creating space habitats, they create a number of generation ships. These massive structures are initially given a population and crew of 30,000, with room to expand to 50,000, and each one has all the tools and manufacturing capabilities to make more generation ships and space habitats, along with the ability to terraform a planet. Strapping on a few large meteors with ice, minerals and other things they may need in an emergency, these ships slowly make their way to the nearest solar system. Slow being a little less than half the speed of light, thanks to getting a very large boost as they start their journey. Once there, they get to work making comfortable habitats for the now increased and cramped population using the resources of the system. They spend several decades there, creating a working system of habitats and making any repairs that are needed on the generation ships. After a century or two, the generation ships, possibly a few new ones as well, get crewed by people who want to travel and move onto the next solar system to do the same thing all over again. Eventually the fleet splits into two and each one does the same thing, eventually splitting again, and again and again. If they find a planet that looks like it can be terraformed, a planet with no life, or only the most basic of bacteria which is wiped out, they get to work making the planet livable for the people who want to have a sky over their head. Any planet with multicellular life is carefully studied by probes, but left otherwise alone because the risk of contamination, allergies, etc, are too great for the ships, and terraforming them will destroy the ecosystem. Is this a realistic way to colonize and explore the universe?	> > Slow being a little less than half the speed of light, thanks to getting a very large boost as they start their journey. > > > Slow down there! ================ literally. At that speed it's not really a generation ship since you can get to many other stars within the original crews lifetime. And there are hazards to going that fast. Lets assume the ship is, say, 10X the mass of the worlds largest supertanker, that's very conservative for the numbers you talk about but it's a number to work with. How do you slow down at all? ---------------------------- At 0.5 c that ship would have 7.197×10^25 joules of kinetic energy you'd need to get rid of if you want to slow down. That's about 1800 times as much energy as the energy from entire worlds fossile fuel reserves. You need some kind of fuel and some plan for slowing down. Hitting things in your path --------------------------- If there's something the size and mass of a sugar cube in your path it hits the front of your ship with the energy of the nuclear bomb dropped on Hiroshima with all the energy pretty well focused to rip through any sane quantity of armor. And that's not the only problem. The atoms between the stars --------------------------- using the figures for a cold neutral interstellar medium from wikipedia: 20—50 atoms/cm3 So let's go with 25 atoms/cm3 25000000 atoms per cubic meter. Lets imagine the ship is a nice neat cylinder. We can treat the volume of space that the ship passes through as a cylinder with a cross section equal to that of the front of the ship. Now lets look at how much it hits while traveling, say, 10 light years. Treat it as a cylinder 10 light years long with the diameter of the ship, again, lets guesstimate that the ship has a radius of 100 meters. This lets us estimate the total number of (almost all hydrogen) atoms in the path of the ship, lets assume they all hit and there's no shockwave effects: 946073047258080000000 π m^3 (cubic meters) Multiply by 25000000 atoms per cubic meter. mass of (946073047258080000000 \* π \25000000 ) hydrogen atoms = 124.4 kilograms so over the course of 10 light years it will impact with 124.4 kg kilograms of gas atoms. For simplicity I'm assuming all hydrogen. Those atoms are hitting at .5c so the front of your ship (assuming it's a big round shield with radius 100m). kinetic energy of 124.4 kilograms at .5c is 1.73×10^18 joules I'm going to ignore time dilation because it's hard and I need to maintain my sanity. so at .5 C it takes us 20 years to travel those 10 light years So lets convert that into the energy of the gas hitting the front of the ship each hour. 1/24 (1/365 (1/20×1.73×10^18 J (joules))) = 9.8748×10^12 joules/h = 2.743 GW h (gigawatt hours) per hour has to cope with 2.743 GW hours worth of energy hitting it every hour. It's like having a large nuclear power plant at the front of your ship producing heat. you have no way of getting rid of that much heat with your ship in a vacuum and it will be melting your heat shield. So just slow down* It's really common for writers to throw around large fractions of light speed but without magitech shields there's massive practical problems with going that fast at all. At those speeds the fine mist of interstellar gas is enough to cook an astronaut to death just from being outside the ship unshielded and enough to destroy any shielding made of matter within a short time. Since your ships are generation ships anyway you almost certainly want to slow your ships down to something sane like 0.05 C (or probably even lower if your crew want to continue to live) At least then you have some chance of stopping and some chance of surviving if you hit some grains of sand in deep space. EDIT: ===== Putting more ice or rock on the front of the ship does not help. Lets imagine that we put a cylinder of solid ice 100 meters thick at the front of the ship as a shield. it's an idea, I'll give you that, but lets work out how long it's likely to last at 0.5C .... cylinder \| radius 100 meters, height 100 meters = 3.14159×10^6 cubic meters That's 3,141,590 cubic meters of ice, millions of cubic meters of ice. Wolfram alpha gives a helpful table for this Phase change energies for 3.14159×106 m3 of water from 25 °C: ``` energy required to heat to boiling point \| 9.85×10^11 kJ (kilojoules) energy required to convert to vapor \| 7.01×10^12 kJ (kilojoules) energy required to heat to boiling point and convert to vapor \| 8×10^12 kJ (kilojoules) energy released from cooling to freezing point \| 3.28×10^11 kJ (kilojoules) energy released from converting to solid \| 1.05×10^12 kJ (kilojoules) energy released from cooling to freezing point and converting to solid \| 1.38×10^12 kJ (kilojoules) ``` It's annoying that it calculates from 25 degrees C but the energy released from cooling and energy needed to heat can just be added together. Practically speaking I'm being very very forgiving by assuming that the energy needed is the same as at sea level. To melt that much ice we could need 1.05×10^15 J (joules) To turn that much ice into steam we would need about 7.01×10^15 J (joules) Unfortunately the front of our ship would be receiving 1.975×10^13 J (joules) every hour while traveling at 0.5 C from impacts with the fine mist of atoms in interstellar space. From there's it's just a matter of multiplying. it would shield you for a little while.... Within 5 days your 3 million cubic meters of ice has melted. after 34 days your ice has all turned into steam. But what if we use something stronger than ice! Lets imagine that instead of 3 million cubic meters of ice we make that shield out of 3 million cubic meters of solid iron! It takes 6.11×10^15 J to melt 3 million cubic meters of solid iron. Within 26 days enough energy has hit the front of your ship to melt 3 million cubic meters of iron. This is not exactly how long your shield will last, some energy will be radiated away, some will be lost to cooking your crew and iron may ablate in a less simplistic manner but it's a rough ballpark figure. At 0.5 C shields are not enough. Asteroids traveling at 0.5 C would melt and turn into a gas in short order. I cannot stress enough how poor natural intuition is when it comes to the rigors put on anything traveling at large fractions of the speed of light.
103,753	<p>The obvious WWII alternate history question is <a href="https://worldbuilding.stackexchange.com/questions/30758/what-single-change-would-have-given-the-best-chance-for-the-axis-to-win-world-wa">how could the Axis have won</a>. Let's try something different this time.</p> <p>The <a href="https://en.wikipedia.org/wiki/Battle_of_France" rel="noreferrer">Battle of France</a> was a big gamble for the Third Reich. They sent more or less their entire army in a rush attack in order to secure a fast victory. You may be reminded of the <a href="https://en.wikipedia.org/wiki/Schlieffen_Plan" rel="noreferrer">Schlieffen Plan</a> in WWI. It worked this time, but had it not, they would have been in a dire situation.</p> <p>Had their army been destroyed, there would not have been enough left to defend German territory. Had they been forced into a more static war of attrition, France and Britain would have had time to reorganise their military, with the support of their respective colonial empires and access to American industry - and the Axis may have not been in a better position to fight a new WWI than the Central Powers had been.</p> <p>So be it with a swift counter-attack or a slow, bloody grind, what is the smallest change that could have resulted in an eventual Allied victory in the Battle of France?</p> <p>The customary disclaimers apply:</p> <ul> <li>It doesn't have to result in a global Allied victory with the fall of Berlin and Rome, but it has to significantly increase its probability.</li> <li>A victory doesn't mean the entire Axis is defeated, only the European part. Japan can be victorious in the Pacific Ocean at the same time, for example.</li> <li>The change has to be a single event, or a collection of tightly coupled and interdependent events, ideally the starting point an otherwise trivial change. It has to happen either during the war, or not more than a few years before it. The war should, at least in the beginning, look very similar to what happened in real life: the alliances should be roughly the same, the events like the Anschluss, the conquest of Poland, the attack against France and the Low Countries should occur (or at least begin), even if at different dates or different order. The major participants should be the same.</li> <li>The change should have a realistic justification (so no secret Belgian superlaser), no unrealistic decision like continuing the very expensive Maginot Line until the sea without a very solid reason, no sudden change of doctrine just because some general had an epiphany about revolutionary new tactics...</li> </ul>	[ { "answer_id": 103755, "author": "Community", "author_id": -1, "author_profile": "https://worldbuilding.stackexchange.com/users/-1", "pm_score": 1, "selected": false, "text": "<p>Strategic Depth</p>\n\n<p>The French invested heavily in the Maginot line (and famously didn't extend it acro...	2018/02/01	[ "https://worldbuilding.stackexchange.com/questions/103753", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/42046/" ]	The obvious WWII alternate history question is [how could the Axis have won](https://worldbuilding.stackexchange.com/questions/30758/what-single-change-would-have-given-the-best-chance-for-the-axis-to-win-world-wa). Let's try something different this time. The [Battle of France](https://en.wikipedia.org/wiki/Battle_of_France) was a big gamble for the Third Reich. They sent more or less their entire army in a rush attack in order to secure a fast victory. You may be reminded of the [Schlieffen Plan](https://en.wikipedia.org/wiki/Schlieffen_Plan) in WWI. It worked this time, but had it not, they would have been in a dire situation. Had their army been destroyed, there would not have been enough left to defend German territory. Had they been forced into a more static war of attrition, France and Britain would have had time to reorganise their military, with the support of their respective colonial empires and access to American industry - and the Axis may have not been in a better position to fight a new WWI than the Central Powers had been. So be it with a swift counter-attack or a slow, bloody grind, what is the smallest change that could have resulted in an eventual Allied victory in the Battle of France? The customary disclaimers apply: * It doesn't have to result in a global Allied victory with the fall of Berlin and Rome, but it has to significantly increase its probability. * A victory doesn't mean the entire Axis is defeated, only the European part. Japan can be victorious in the Pacific Ocean at the same time, for example. * The change has to be a single event, or a collection of tightly coupled and interdependent events, ideally the starting point an otherwise trivial change. It has to happen either during the war, or not more than a few years before it. The war should, at least in the beginning, look very similar to what happened in real life: the alliances should be roughly the same, the events like the Anschluss, the conquest of Poland, the attack against France and the Low Countries should occur (or at least begin), even if at different dates or different order. The major participants should be the same. * The change should have a realistic justification (so no secret Belgian superlaser), no unrealistic decision like continuing the very expensive Maginot Line until the sea without a very solid reason, no sudden change of doctrine just because some general had an epiphany about revolutionary new tactics...	After many good answers and further research, it seems that, by all accounts, the Allies should have won, surprisingly enough. The Nazis won thanks to a ridiculous string of coincidences that would have had put any reader out of the story, had it be fictional. At the end of WWI, France had the most modern army in the world. A massive pool of truck instead of reliance on trains for moving troops, the biggest air force of the planet, troops being equipped with semi-automatic rifles and a massive number of LMGs, turreted tanks and combined operations... And while Great Britain put comparatively more efforts into its navy, its army was about as advanced and had even started working on APC vehicles. How do we get from this to such a debacle? The post-WWI years ------------------ After war, both nations knew they needed a rearmament program, to thoroughly modernize according to the lessons learned form the war. Of course, rearmament programs are expensive, and when the deadly, exhausting, impossibly costly war that was supposed to be The Last One is just finished, some people may think that diverting funds sorely needed for reconstruction to the army is not the best idea. In the aftermath, the British stop pursuing combined arms doctrines, which are slowly forgotten. And the general Estienne, father of the French combined arms doctrine, dies early before having time to further develop his ideas, resulting in the same loss. *tl;dr: Had either not let their armies decay, especially doctrine-wise, they would have been prepared against the new German tactics and blunt their advance. Britain was focused on trying to hold together a dying Empire, and the focus on the navy and on rebuilding the economy left the army deprioritised, and it went back to a smaller expeditionary force, not unlike it was pre-war, even if its rearmament program was somewhat less disrupted. Meanwhile, France starts its complete rearmament program. It develops a rather excellent light machine gun, then starts working on a new semi-automatic rifle and... thing peter out, especially after the 1929 crisis. Then new left-wing government, focused on social progress but openly contemptible of the traditionally right-wing army, cuts military funds as much as possible. A French head of state of the time goes as far as declaring that "If I could, the army would not get one centime in peace time". Even worse, fearing the potential influence of the army, they change the appointment system for top officers: instead of picking from a list compiled by high command based on competence, they are now directly nominated, based on political affiliation. But wait, you might say, wasn't that exactly what had happened before WWI? Didn't France have to fire a third of its generals early in WWI because of that? Didn't they know that was a bloody stupid idea from experience? Yes they did, but remember, the priority was to make sure the army was not a political menace. And anyway, who would be insane enough to start another* world way, after all? As the threat of a new war loomed, France picked the rearmament program back up, but it was too little too late. They had great planes, but not enough - and the newest model was basically at the prototype stage and sent to the front from the factory. They had great defensive tanks, but with flaws not yet kinked out. They had great sub-machine guns, but only a few hundreds had time to reach the troops. They had great rifles, but had only time to equip troops with a bolt-action version planned for rear-echelon troops. The semi-automatic version, which would have been one of the best rifle in the entire war, was barely complete, and didn't even have time to leave the factory (fortunately, they did manage to hide its existence to subsequent German occupation forces). *tl;dr: Had the French government at the time not seen the army as a political enemy and cripple its high command, it could have developed new doctrines and efficiently respond to new German tactics. The appeasement politic ----------------------- Interwar France and Britain have been criticised a lot for their appeasement politic, believing that if enough concessions were to be made to Germany, they wouldn't do something as stupid as start another* war. Had they read Mein Kampf, they would never have believed Hitler's words about wanting peace. (Then again, that book is allegedly so badly written to be painful.) It is difficult to imagine what an early war would have looked like, but Germany probably was more unprepared than others. Had the Allies (possibly without Great Britain) gone to war over Czechoslovakia, it may have gone badly for Germany. But this would have required a significantly different political climate at least in France if not in Britain as well, so this is somewhat difficult to imagine it happen at that point. However, had the Franco-Soviet 1935 treaty held, Germany would never had stood a chance in a war. Had Stalin compromised over not sending troops on Polish territory, or had France been less eager to appease Germany, the Soviet may have very well ended up with the Allied at the start of the war. *tl;dr: Had the alliance with the Soviet worked out, it would have been a race to Berlin five years early. Speaking of Poland, they did quite better than is commonly believed (mostly based on Nazi propaganda, as it happens). But as to not, ah, provoke Germany, France and Britain had stopped Poland to fully mobilize, considerably hampering its war effort against German and then Soviet attack. Even worse, its strategy was to hold long enough for the French army to launch an offensive across the Rhine, and for the British air force to launch a bombing campaign against Germany. Neither were actually prepared to conduct such operation, and had assumed Germany would be deterred simply by the threat. France launched a probing attack, met no resistance but decided to withdraw behind its fortification. Britain sent a few token planes, met no resistance but decided to stop further attacks. However, even unprepared (which they shouldn't have been), attacks against the undefended western Germany while its army was stuck in Poland could have stuck a heavy blow, either stopping it from finishing Poland or at least seriously weakening for the counteroffensive. Also the offensive happened right before Poland would receive thousands of modern planes for its air force. I suspect Germany wanted to attack before that, as it would have seriously challenged the Luftwaffe. tl;dr: Had the Allies been prepared to support Poland, they could have dealt a potentially fatal blow to Germany. Defensive strategy ------------------ Nonetheless, as the years pass by, with more and more nations falling toward extremism, it had become clear that a new European war could happen again. The "twenty years of armistice", as Field Marshal Foch had called the Versailles treaty, were coming to an end. Britain could count on the Channel, its navy, its air force and an alliance with several continental powers to prevent a war from reaching its homeland. France, however, was right next to the biggest potential threat, a revanchist Germany that could field twice as many men, and that had already proved its capabilities at massive industrial war. Which is why they did the logical thing and developed the Maginot Line. But wasn't the Maginot Line a terrible idea that miserably failed? No, in fact it was a great idea and, when used properly, it worked exactly as advertised. (See below as for how it was not* used properly.) It was the brainchild of WWI veteran Philippe Pétain who, despite some, ah, unfortunate political decisions later (again, see below), had still been one of the best generals of WWI - so not an idiot, and not an idiotic idea. The Maginot Line was an impassable line of fortifications, estimated to hold with a contingent against an army fifty times more numerous. And, contrary to much later rumours, France was perfectly aware that the Germans would push through Belgium - and so was Belgium, in fact, which is why it was part of an alliance with France and Great Britain. Belgium was to build its own equally impassable Meuse–Albert line. The problem is, impassable fortifications cost a lot, and Belgium simply didn't have enough money. So they asked France to lend them enough funds for the project. Which France declined (see above for why they would do such a thing). Which is why the Meuse-Albert line was delayed and scaled back. At the onset of the war, it was clear that the Belgian army wouldn't be big enough to hold a determined German push at its border. *tl;dr: Had France lent the money to Belgium, no German army could have crossed their eastern border. Nevertheless, with the bulk of the French army and the British Expeditionary Force to back them up, it would still be enough to stop a German attack. As long as they were deployed in advance, that is. But if tensions rose, as allied nations, of course this is exactly what would happen. But then the remilitarisation of the Rhénanie happened, and neither France nor Britain reacted, not wanting to declare war on Germany over internal troop movements. After all, they simply wanted to legitimately be able to defend themselves, right? Belgium saw this appeasement politic as a sign that it couldn't count on the Allies, and thus left the alliance, hoping that neutrality would avoid it to be caught in the next war. Which meant not having foreign troops on its territory. Which meant that when Germany attacked, French and British had to rush from the French border to the frontline, losing much of their defensive advantage, and the easier to defend eastern Belgium being already overrun when they arrived. From there to Paris, there were only flat, hard to defend plains. tl;dr: Had Belgium not left the Allied for neutrality, the German army would have been stopped, or at least considerably weakened, at its eastern border by the Allied forces. But then, why didn't the French simply extend the Maginot line? Actually, they did. But two years were simply far too short a time to build such fortifications, especially on flat terrain. The Ardennes gambit ------------------- Now, the German plan was to repeat the Schlieffen plan that had nearly worked so well in the previous war: launch a massive fast offensive through Belgium and run for Paris to knock France out of the war early. Sure, it had failed last time, but it had worked the time before that. And Germany didn't really have other options anyway. At least, this was the plan before it fell in the hands of Belgian intelligence, when a German courrier plane randomly crashed in Belgium, carrying said plans. And while the Belgians tried their best to make it look like the whole thing had burned, the Germans knew to be better safe than sorry: they needed a backup plan. So they did what would otherwise have been an idea worthy of the Chemin des Dames offensive in its utter stupidity: send two tank corps through the Ardennes forest. Now, the French knew perfectly well that an Ardennes tank offensive was possible, and that a tank army could cross it in two days. Specifically, Maxime Weigand, possibly the most underrated general of the XXe century, had warned François Gamelin, the French chief of staff, of this. (It was also Weigand that told Charles de Gaulle that his idea of a small, mobile professional army of a hundred thousand men for defense would simply not work - probably because the British had done the exact same thing* during WWI and it had been ground down to oblivion in a few months, and thus earning De Gaulle's unending antipathy. But this is a story for another time.) Once entrenched in the Ardennes forest, even a modest force could have stopped a tank offensive. Tanks offensives are meant for flat terrain: forests make it easy to ambush even big armored forces, and once a few tanks are burning on either side, can easily become death traps. Unfortunately, as noted above, top officers weren't named for their skills anymore, and Gamelin was a courtier but not a good general. Which is how he ignored both warnings not only from Weigand, but also from French intelligence in Germany about their innovative light tank tactics and training. *tl;dr: Had Gamelin actually listened to his best general or his detailed intelligence reports, he would have easily destroyed the Ardennes tank offensive with a few well-entrenched forces. But then, even without opposition, having two tanks corps cross a forest like the Ardennes is no trivial task. In short order, tank columns turned into giant traffic jams, easily seen by French aerial reconnaissance. When receiving such reports, however, the officer in charge of defending the sector dismissed them as "a few scout cars". So the air scouts went back with tankers on board their planes, to identify the tank models and make unambiguous, detailed reports of the tank force. No matter, the officer dismissed the new reports. When the French air force asked him if he needed any support, he answered none whatsoever. One may wonder if he was that incompetent, or if it wasn't actual treason. Had the air force been sent to bomb the piled up tanks, it would have been a massacre. The few survivors to make it would have been easily stopped by even a light force, had it been forewarned. tl;dr: Had the officer in charge of the Ardennes defense not been terminally incompetent/a traitor, or had someone gone over his head (or executed him for treason), German tanks would never have made it out of the Ardennes. The Battle of Belgium --------------------- The Belgian lines breached, the Allied forces on the back foot, and now a tank force emerging from the Ardenne to envelop them. As in 1914 the French government finally pulled itself together, fired the incompetent, politically appointed generals and let actually competent ones do the job instead and save the day. Namely, they pulled the aforementioned Weigand from retirement and gave him Gamelin's job as chief of staff. Now, you would think Weigand was the right man for the job: respected by friends and foes alike, right hand man of Allied supreme commander Ferdiannd Foch during WWI, architect of the Warsaw Miracle, absolute légaliste with an unwavering loyalty to democracy and to the Republic. But with the entire French army disorganised, lacking radios and fast-moving forces, about to be encircled, what could even he do? What he did, was to understand that the main German armored push was overextended, and that there was an opportunity: the French army would counter-attack in a pincer move, hammering the German forces against the British and Belgian anvil, and cut off the spearhead. British high command agreed with the plan, and so do modern experts, who argue that it would have indeed worked. And then the British ran away. Specifically, John Gort, commanding the British forces on the continent, panicked and ordered his army to rout towards Dunkerque - leaving behind piles of equipment for the Germans to take instead of properly destroy it all, but destroying bridges, trapping the French and Belgian forces that would be forced to retreat later. With their flank gone, there was no more hope of victory for the French and Belgian forces, so they started to retreat as well. Both fought hard - the French fighting retreat was especially brutal, taking the highest relative death toll of all the European armies of the early war. German general Heinz Guderian, would in fact call the battle of Stone one of the two worse he ever saw - along with freaking Stalingrad. In fact, the one thing that saved the British army (along with Hitler's tactical mistake at Dunkerque) was the French army standing against literally impossible odds for the entire retreat. Note: remember that next time you hear about a (much more recent) surrending monkey joke or about the Miracle of Dunkerque: the British ran and only made it because the French stood and died. Not even the guys who invented the Polish lance cavalry charging panzers myth dared to mock the bravery of French soldiers. In fact, Hitler himself called them the best in the world after the Germans (of course), in the aftermath of Bir Hakeim. But again, this is a story for another time.* *tl;dr: Had John Gort not panicked and the British stood their ground instead, the German advance would have been smashed by a pincer move, stopping the German advance. For what of a fistful of nails ------------------------------ Had the German advance been blunted, things would have reverted to a 1914-again state: a grinding war with neither side capable of advancing. This would have pitted industrial and manpower reserves against each-other, and like for WWI, the Allies would have had the upper hand with access to the immense American industry. The Soviet Union may have somewhat balanced this by trading with Germany, but this is neither certain nor guaranteed to have lasted. (Soviet-directed Communist agents were executed in France for sabotaging planes, for example, so the Soviet Union was, at least initially, somewhat serious about their pact with the Germans.) New weapons would have made a difference. Many northern French and Belgian cities may have been razed by artillery fire. New railway trains may have been used to destroy fortifications like on the Maginot line, but the enormous investment on those and on the follow-up force needed to have a chance to advance. As such, like in WWI, it is improbable (though not impossible) for the Germans to achieve victory that way. In addition, and contrary to what many think, the Allied had the initial technological advantage. In fact, the reason later German tanks were so good was partly because of the French tech they got their hands on, and on the resources of the French had from their colonial empire, allowing for better alloys. Had the war become static, the Allies would have kept the technological advantage, especially with Hitler increasingly obsessed with wunderwaffen and the French armament program being finally completed and extended. Given how fast it rebounded after the war, and as there were pre-war projects already, France may have been the first one to develop rockets and even jet engines. it may even have fielded ramjets, whose development were interrupted by the Occupation. They also had few wagons full of uranium ore that spent the entire Occupation pointedly forgotten in some railway depot, but while it would have considerably helped nuclear development, it is far from certain that the war would have lasted long enough for an atomic bomb to be finished. tl;dr: Had the initial push been stopped, it is improbable that Germany could have won WWI-bis. Aftermath --------- At this point, the French homeland was lost. There was next to nothing left between the German army and most of France, with indefensible open terrain in the way. But France was still not ready to give up. it had 150 000 surviving troops evacuated from Dunkerque. It had an army holding the Italians at bay in the Alpes. It had an oversea empire, from which colonial troops could be raised. It had a modern, rather powerful navy. So the French government did the sensible thing, gave up the indefensible territory and prepared to move the capital to Algiers (as Algeria was considered more or less French homeland at the time). In this time of crisis, they decided to unearth this old Roman tradition: nominate an emergency ruler with dictatorial powers, so the slower democratic powers can be temporarily been bypassed for the duration of the crisis. After all, if it worked for the Romans... So they chose the victorious chief of staff of WWI (Foch was the supreme commander of the allied forces at this point, which was not the chief of the French army), the Lion of Verdun, a national hero whose military skills had been well-proven: Field Marshall Philippe Pétain. Unfortunately, he was also going senile and had never liked politicians to begin with. This was the "divine surprise" that fell on the lap of the far right, who seized the opportunity to take power in Pétain's name and stage a coup d'état. While officially called the "Nation Française", it would be remembered as the Vichy regime. In short order, being ideologically close to Germany and Italy but deeply anglophobes, they would sign an armistice (not a capitulation, because that would make the army lose face, a big no for a fascist regime) and nevermind the loss of half of France and basically becoming a puppet of Germany (even if officially neutral in the war). Oh, remember the French navy? half of it was stuck in Toulon and, much later, scuttled itself so the Germans wouldn't get their hands on it. Another half was in Mers-el-Kebir, and the British murdered it with a surprise air attack, so (agian) the Germans could't get them - but the French sailors were actually busy scuttling said ships, so not only were they especially defenseless against a surprise attack from an ally, but even more died trapped in the ships. So while the armistice was very unpopular for many French, many also felt betrayed by the British and decided that neither side was worth it anyway. Even then, and despite everyone (including the Allies) considering the Vichy regime as the legitimate French government, "Fighting France" (later Free France) was formed as a government in exile refusing to stop the fight. While only a few troops and colonies joined it, plus those forming Résistance groups in Vichy and occupied territory, they became increasingly popular and, in the case of Bir Hakeim, even instrumental in the war. But again, this is a story for another time. tl;dr: Had the French government named the maybe too modest Weigand instead of Pétain, the French Republic would have kept fighting from Algiers. And the Devil is laughing still ------------------------------- Now as this is Worldbuilding and not History, let's try to make sense of it. Because as it is, this is all too ridiculous to use in a story, nevermind that it actually happened. So let's take this ridiculous chain of coincidences, and the fact that it suddenly started to fall apart everywhere. Add the countless failed assassination attempts against Hitler. Add that the Nazi regime was not simply evil, but Evil. They didn't just invade Europe, raze cities and murder countless civilians. They didn't simply have insane racial theories they actually attempted to put into practice, and allied with an equally monstrous regime on the other side of the world. But not only did they industrialize genocide* (and yes, I am the first to be surprised that it has to be reminded nowadays), but they actually wore skulls as a symbol. And the SS had a war song with those lyrics (translated, obviously): ``` "And the Devil laughs with us" "Ha! ha! ha! ha! ha! ha! ha!" ``` Also Hitler was into occultism. *tl;dr*: there is one obvious explanation: Hitler made a deal with the Devil. Seriously, why don't more people use this in secret-history or alt-history works?
105,190	<p>So, This is a VERY VERY BIG TANK. So big it crushes everything in its path (even the path itself). </p> <p>Assuming I lead Nazi Germany, I WILL deploy/create this tank.</p> <p>The issues of this tank are: (taken from <a href="https://en.wikipedia.org/wiki/Landkreuzer_P._1000_Ratte" rel="nofollow noreferrer">wikipedia</a>) 1. The large size and weight would have rendered the tank unable to cross bridges at the risk of collapsing them. and travelling on roads would soon destroy them. </p> <pre><code> 2. Though its top intended speed was 40 kilometers per hour, its huge size and high visibility would have made it extremely vulnerable to aerial bombardment and artillery fire. 3. Its great size would also have made it nearly impossible to transport—no existing railway or train car could bear its weight and its width was too great for existing tunnels. </code></pre> <p>My Answer to this issues:</p> <pre><code> 1. This is my weapon-of-last-resort, launch it to cities which are captured by allies. crush even the buildings just to recapture the cities. Launch this tank when battle on plains are inevitable. 2. Increase weight and armaments - Add more plates capable of holding of artillery fire (though I think none is present at that time, the added armor should just make the tank not explode on a single shot of artillery). Protect the engine, probably build it under the hull as such that if this is bombed by an aircraft, it will take the hit (again, I do not know any WWII tech that is capable of rendering this tank invulnerable but if there is, do let me know). Regarding land mines, I have to use other tanks to move forward before this tank, and if there are no tanks available, humans will. I will also add a gunner in front, sides, and rear of the tank so that I could check if there are any enemies who would put explosive charges under the tank. 3. As this tank is my last resort, I would deploy them from Berlin, going forward to cities that are already captured. This would also increase the consumption of diesel which I think would be the biggest problem of having this tank. The trip to other cities may as well be very very long, So I think I can create 1 for Berlin and industrial districts capable of manufacturing this tank. </code></pre> <p>The strengths of this tank (as per my knowledge)</p> <pre><code> 1. With my superior firepower and armor, I would have destroyed a lot of enemy tanks, killed plenty of infantry which may disheartened enemy morale. 2. The sheer size would strike fear for advancing troops, giving morale boost on my troops. 3. Recapturing cities would be a breeze (But most of the structures would be destroyed, thanks to me also) 4. To deploy this tank to other cities(and maybe captured nations), I would have to transport this tank as parts, put them in a train , assemble it in a factory, and its ready to rumble. </code></pre> <p>So with my points taken (and maybe some of your suggestions) Can I win my WWII campaign with this tank?</p> <p>EDIT: The period my WWII campaign is 1939 and the latter part of 1941. I chose this period because it is still viable at this time, during early 1942 or more then the viability becomes 0 due to the scarcity of raw materials, fuel and factories.</p>	[ { "answer_id": 105191, "author": "L.Dutch", "author_id": 30492, "author_profile": "https://worldbuilding.stackexchange.com/users/30492", "pm_score": 1, "selected": false, "text": "<p>First of all, 1939 to 1941 are the years where the Nazi and their allies were jumping from success to suc...	2018/02/17	[ "https://worldbuilding.stackexchange.com/questions/105190", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/28224/" ]	So, This is a VERY VERY BIG TANK. So big it crushes everything in its path (even the path itself). Assuming I lead Nazi Germany, I WILL deploy/create this tank. The issues of this tank are: (taken from [wikipedia](https://en.wikipedia.org/wiki/Landkreuzer_P._1000_Ratte)) 1. The large size and weight would have rendered the tank unable to cross bridges at the risk of collapsing them. and travelling on roads would soon destroy them. ``` 2. Though its top intended speed was 40 kilometers per hour, its huge size and high visibility would have made it extremely vulnerable to aerial bombardment and artillery fire. 3. Its great size would also have made it nearly impossible to transport—no existing railway or train car could bear its weight and its width was too great for existing tunnels. ``` My Answer to this issues: ``` 1. This is my weapon-of-last-resort, launch it to cities which are captured by allies. crush even the buildings just to recapture the cities. Launch this tank when battle on plains are inevitable. 2. Increase weight and armaments - Add more plates capable of holding of artillery fire (though I think none is present at that time, the added armor should just make the tank not explode on a single shot of artillery). Protect the engine, probably build it under the hull as such that if this is bombed by an aircraft, it will take the hit (again, I do not know any WWII tech that is capable of rendering this tank invulnerable but if there is, do let me know). Regarding land mines, I have to use other tanks to move forward before this tank, and if there are no tanks available, humans will. I will also add a gunner in front, sides, and rear of the tank so that I could check if there are any enemies who would put explosive charges under the tank. 3. As this tank is my last resort, I would deploy them from Berlin, going forward to cities that are already captured. This would also increase the consumption of diesel which I think would be the biggest problem of having this tank. The trip to other cities may as well be very very long, So I think I can create 1 for Berlin and industrial districts capable of manufacturing this tank. ``` The strengths of this tank (as per my knowledge) ``` 1. With my superior firepower and armor, I would have destroyed a lot of enemy tanks, killed plenty of infantry which may disheartened enemy morale. 2. The sheer size would strike fear for advancing troops, giving morale boost on my troops. 3. Recapturing cities would be a breeze (But most of the structures would be destroyed, thanks to me also) 4. To deploy this tank to other cities(and maybe captured nations), I would have to transport this tank as parts, put them in a train , assemble it in a factory, and its ready to rumble. ``` So with my points taken (and maybe some of your suggestions) Can I win my WWII campaign with this tank? EDIT: The period my WWII campaign is 1939 and the latter part of 1941. I chose this period because it is still viable at this time, during early 1942 or more then the viability becomes 0 due to the scarcity of raw materials, fuel and factories.	The problem with these giant tanks is that killing them is easier than building them. They will be no tougher than an armored cruiser or battleship, and ships were sunk with bombs from carrier-based and land-based bombers. Historically Germany had been quite inefficient, and fiction tends to ignore that. Do you want to create the equivalent of an Indiana Jones movie or something more like Saving Private Ryan? Do you want the German equivalent of the Maginot line? ====================================================== Breaking the line could be a role for that tank, by the way. Say the Germans pour lots and lots of money into a couple of those things. They come up with clever ways to resolve mobility problems, for instance the landcruisers are built to disassemble and reassemble easily, and each comes with a couple dozen specialized trains and a battalion of assembly workers. At the start of the war, when Germany had the initiative, they *create* opportunities to make the landcruiser work. * Say they assemble one near Aachen, drive it 30 km or so to the Meuse, and engage the surface works of [Fort Eben Emael](https://en.wikipedia.org/wiki/Fort_Eben-Emael) instead of the historical solution, a glider assault. * Another one gets shipped by riverboat to Wörth am Rhein, is assembled there, and then overruns the Ouvrage Schoenenbourg. * One gets attached to the Romanian forces during the [Siege of Odessa](https://en.wikipedia.org/wiki/Siege_of_Odessa_(1941)) to help overrun the city. In the middle of the war, they are mostly held in readiness for opportunities that never come up. Say one was in southern France, disassembled on transport train and waiting for the Spanish decision to go after Gibraltar. Another was transported to the Siege of Leningrad, where it made a credible showing -- but no more credible than another Panzer regiment would have been. At the end of the war all are lost. Those near the Normandy get bombed to bits before Overlord. Some end as stationary bunkers when they run out of fuel or a track breaks, to be bypassed and mopped up later. Every now and then an Allied regiment gets chewed up when it unexpectedly encounters one that can still move. (Count on the Soviets to generate lots of casualties with direct attacks, while the Americans send wave after wave of fighter-bombers.)
106,120	<p>Due to global warming, Earth has become uninhabitable. The rich left off to colonize 'New Earth' while everyone else is left behind.</p> <p>For whatever reason, the people left behind have survived, but out of sheer hatred have decided to go out to 'New Earth' and plunge it into an even worse but similar demise as the original Earth.</p> <p>Their plan? To create a massive ship, fill it up with the solid form of a green-house gas and crash the ship into New Earth.</p> <p>'New Earth' is a little smaller than earth and the surface is 90% water.</p> <p>To define a 'successful' attack would to heat up the oceans enough to produce a large amount of steam. With steam also being a green-house gas, the planet would assumably begin to heat itself up and literally cook everyone on it.</p> <p>What is the absolute best compound to use as the green-house compound to fill the crash ship and,</p> <p>assuming distance isnt a problem, how large would this ship have to be?</p>	[ { "answer_id": 106123, "author": "Thucydides", "author_id": 8572, "author_profile": "https://worldbuilding.stackexchange.com/users/8572", "pm_score": 3, "selected": true, "text": "<p>If you get down to it, boiling or vapourizing the oceans needs a metric crap ton of energy. The Atomic Ro...	2018/03/03	[ "https://worldbuilding.stackexchange.com/questions/106120", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/47669/" ]	Due to global warming, Earth has become uninhabitable. The rich left off to colonize 'New Earth' while everyone else is left behind. For whatever reason, the people left behind have survived, but out of sheer hatred have decided to go out to 'New Earth' and plunge it into an even worse but similar demise as the original Earth. Their plan? To create a massive ship, fill it up with the solid form of a green-house gas and crash the ship into New Earth. 'New Earth' is a little smaller than earth and the surface is 90% water. To define a 'successful' attack would to heat up the oceans enough to produce a large amount of steam. With steam also being a green-house gas, the planet would assumably begin to heat itself up and literally cook everyone on it. What is the absolute best compound to use as the green-house compound to fill the crash ship and, assuming distance isnt a problem, how large would this ship have to be?	If you get down to it, boiling or vapourizing the oceans needs a metric crap ton of energy. The Atomic Rockets "[Boom Table](http://www.projectrho.com/public_html/rocket/usefultables.php)" tells us we need the following amounts of energy: Boil the oceans: 6.6 × 10^26J 158 Pt Vapourize the oceans 4.5 × 10^27J 1 Et To put that in perspective, the Sun's output per second is: ``` 3.9 × 10^26J 92 Pt ``` The best way to apply lots of energy at once would be to accelerate you spacecraft to relativistic velocities. One Kilogram can release: 1 kilogram at 75% c 4.6 × 10^16J 11 Mt 1 kilogram at 90% c 1.2 × 10^17J 29 Mt At that point the aggressor can be using wadded up recycled paper and still getting impact energies straddling the "[Castle Bravo](https://infogalactic.com/info/Castle_Bravo)" nuclear device. [![enter image description here](https://i.stack.imgur.com/PbUfx.jpg)](https://i.stack.imgur.com/PbUfx.jpg) The worst part is the huge yield was actually an accident Once you have an idea of the parameters of the planet (i.e. how much water is in the oceans) then you can scale the device and the speed to match your capabilities. Of course anyone on the receiving end of that may have a few more pressing issues than the oceans boiling. For a slightly different take read this answer: [What would a relativistic kill vehicle hitting the moon look like from earth?](https://worldbuilding.stackexchange.com/questions/47793/what-would-a-relativistic-kill-vehicle-hitting-the-moon-look-like-from-earth)
106,145	<p>I am writing a science fiction story with mass produced clones. Since I have a number of clone I need to tell them apart. The ID system must be:</p> <ul> <li>Permanent over the lifetime of the clone (call it 150 years)</li> <li>Very difficult to tamper with (radio frequency transmitters can be excised, etched bones can be re-etched -- hard to read anyway)</li> <li>Not overly harmful to the clone (clones are only valuable if they function like humans)</li> </ul> <p>Can I use DNA to do this, by simply adding several codons to an existing DNA strand (assuming quick, basically immediate, and accurate Polymerase Chain Reaction - PCR)? Could you modify the clone by rewriting his/her DNA thus causing a serial number to appear on the skin and still detect the genes responsible with PCR (this would should meet the criteria above - two level verification between skin and genetics seems a secure methodology)? Could either of these techniques be used to modify the clones genetic strucure prior to inception thus changing the DNA of all cells within the cloned organism?</p> <p>Note: The following wikipedia article might provide a start in responding to this post (<a href="https://en.m.wikipedia.org/wiki/Gene_therapy" rel="nofollow noreferrer">https://en.m.wikipedia.org/wiki/Gene_therapy</a>)?</p>	[ { "answer_id": 106154, "author": "SK19", "author_id": 46155, "author_profile": "https://worldbuilding.stackexchange.com/users/46155", "pm_score": 2, "selected": false, "text": "<p><strong>Disclaimer:</strong> I'm not a biologist.</p>\n\n<p>Think of DNA as source code for programming. It ...	2018/03/04	[ "https://worldbuilding.stackexchange.com/questions/106145", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/45883/" ]	I am writing a science fiction story with mass produced clones. Since I have a number of clone I need to tell them apart. The ID system must be: * Permanent over the lifetime of the clone (call it 150 years) * Very difficult to tamper with (radio frequency transmitters can be excised, etched bones can be re-etched -- hard to read anyway) * Not overly harmful to the clone (clones are only valuable if they function like humans) Can I use DNA to do this, by simply adding several codons to an existing DNA strand (assuming quick, basically immediate, and accurate Polymerase Chain Reaction - PCR)? Could you modify the clone by rewriting his/her DNA thus causing a serial number to appear on the skin and still detect the genes responsible with PCR (this would should meet the criteria above - two level verification between skin and genetics seems a secure methodology)? Could either of these techniques be used to modify the clones genetic strucure prior to inception thus changing the DNA of all cells within the cloned organism? Note: The following wikipedia article might provide a start in responding to this post (<https://en.m.wikipedia.org/wiki/Gene_therapy>)?	> > Can I use DNA to do this, by simply adding several codons to an existing DNA strand (assuming quick, basically immediate, and accurate Proteinas Chain Reaction - PCR)? > > > Absolutely. A significant percentage (as high as 20% according to some authors) of DNA has no biological activity and is a leftover from ages past. Another 60% has little direct activity (it is non-coding) but might be useful, so let's leave it alone, but that still leaves a lot to play with. Locate a unused section of a [pseudogene](https://en.wikipedia.org/wiki/Pseudogene) which is very likely to be completely nonfunctional (e.g. the seventh in a run of fifteen useless incomplete repetitions likely due to copying errors in the last twenty million years) and replace it with an equally non-coding sequence. There are some combinations you cannot use to ensure that the sequence won't actully code anything, but you have plenty of space for your needs. Or if you feel more adventurous, you can use synonymization: several aminoacids are coded [by more than one DNA triplet](https://en.wikipedia.org/wiki/Genetic_code), and in normal human genetic code, you'll find say GGA for proline. You can then use GGT and GGG in that position to keep everything working (both triplets will code for proline), but at the same time encode either a 0 or a 1. By comparing the known human reference with the clone sequence, you can extract a binary string: ``` human: TAA GCT GCT CAG CGT clone: TAG GCA GCG CAC CGA ... code : 0 1 0 0 1 ``` (This form of 'meta-coding' might have biological significance. In [Frameshift by Robert J. Sawyer](https://www.goodreads.com/book/show/264941.Frameshift), it "unlocks" genetic sequences of DNA that trigger evolution - it's a sort of super-code hidden inside DNA). However, care must be taken to avoid sequences where the synonymization actually allows [coding two different and slightly offset DNA messages in the same sequence](https://www.genome.gov/27556096/multitasking-dna-dualuse-codons-in-the-human-genome/).
106,461	<p>(Turns on future technology super-computer, opens world simulation command prompt)</p> <pre><code>World.Simulation >>Activated World.SetFactions(4) >> 4 factions created Variable human_type = [Caucasoid, Negroid, Mongoloid, Australoid] for i in range(len(Factions): Generate human_simulations(quantity=100, anatomy=human_type[i]) Mode: Survival Faction Split Criteria: human_type Planet: Earth-like Climate: Ice-age Temperature: 4°C - 6°C Technology Level: Stone Age, VARIABLE* (in 25% of simulations all factions have Caucasoid technology, 25% of the simulations all factions have Negroid technology, ect...) Further Technological Progress: Disabled Technology Handicaps: No living in caves Geographic Handicaps: No living near equator or tropics Faction Technology Disparity: None (all equal) Inter-Faction Interaction: False Exposure to Natural Disasters/Run-up Events: Equal (don't ask me how, it's just being held constant!) Victory Condition: Survive 10000 years </code></pre> <p>Simulation Successful!</p> <p>Simulation of the following factions has begun:</p> <p><a href="https://i.stack.imgur.com/bjiWR.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/bjiWR.jpg" alt="enter image description here"></a></p> <p>Let me start with some disclaimers so the purpose and scope is clear. Also it's important to read the disclaimers to keep the question from being too broad. </p> <p><strong>Disclaimer 1:</strong> I know that humans are a technology-intensive species, but the main purpose of this simulation/thought experiment has nothing to do with technology. That's why in the simulation I stipulate <code>Technology Level: Stone Age, VARIABLE*</code>. Meaning that upon simulation, all four factions of humans are brainwashed and given a random culture/technology level. For example, in a simulation where <code>Technology= Stone Age(Caucasoid)</code> that means Caucasoids, Negroids, Mongolids and Australoids are given Caucasoid Technology/Culture. That way technology and culture can be non-factors, allowing us to only examine physical/genetic attributes. I think this is the only way to do it because "Stone Age" technology is different in each part of the world. In your answer you can define your own scope as you see fit. For example, you may say things like: Generally, across all simulations ... or...In simulations where technology=Mongoloid ...</p> <p><strong>Disclaimer 2:</strong> Caucasoids, Negroids, Mongoloids and Austaloids are general skeleton types. Each one has many, many distinct ethnicities and historical cultures/technologies. In light of this, I'm narrowing the scope greatly by simply merging/averaging them. In other words, we are not nit-picking which specific ethnicity they are, but rather we are viewing them as aggregate cultural/technological embodiments of their many ethnicities -- with their technology averaged as well. Purely for illustration purposes, consider the following: say most Negroid stone age archaeological sites support the premise of having excellent sewing technology, except for a few outlier archaeological sites in this one country where the stitching is really bad or whatever, just consider Negroid sewing to be pretty good. That's what I mean by averaged. I'm not expecting an Archaeological Thesis or anything. Heck, if you think it's too complicated, then just ignore the culture/technology dimension altogether. I don't mind; like I said, I'm not interested in technology. I'm only interested in physical trait advantages/disadvantages.</p> <p>From this futuristic simulation, I'm trying to answer a few inter-related questions. Namely, which traits of the factions would play a big role. For example, given the "No living in caves" handicap, unless I'm mistaken, that would mean Caucasoids would have a bit of a disadvantage because of their comparatively fair skin. Being unable to dwell in caves would force them to spend more time in the ultra-violet than their genetic lineage is accustomed to. However, I'm not sure if that would be a more of a small nuisance or a death-blow.</p> <p><strong>Question:</strong> If we uproot Caucasoids, Negroids, Mongoloids and Australoids from their respective ancestral geographic regions and force them to live in a cold ice-age world (with a few handicaps) as per the simulation above, would each faction have the same chances of success, all else held equal? Or would certain traits get in the way, what traits would be helpful? </p> <p><strong>Side Question:</strong> If you want to go the extra mile, consider answering this question too: Would each faction look the same after 10,000 years? Maybe a few would have died off?</p>	[ { "answer_id": 106468, "author": "Nuloen The Seeker", "author_id": 44624, "author_profile": "https://worldbuilding.stackexchange.com/users/44624", "pm_score": 2, "selected": false, "text": "<p>I would say that there are not any significant differences between these groups. Not significan...	2018/03/08	[ "https://worldbuilding.stackexchange.com/questions/106461", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/32966/" ]	(Turns on future technology super-computer, opens world simulation command prompt) ``` World.Simulation >>Activated World.SetFactions(4) >> 4 factions created Variable human_type = [Caucasoid, Negroid, Mongoloid, Australoid] for i in range(len(Factions): Generate human_simulations(quantity=100, anatomy=human_type[i]) Mode: Survival Faction Split Criteria: human_type Planet: Earth-like Climate: Ice-age Temperature: 4°C - 6°C Technology Level: Stone Age, VARIABLE* (in 25% of simulations all factions have Caucasoid technology, 25% of the simulations all factions have Negroid technology, ect...) Further Technological Progress: Disabled Technology Handicaps: No living in caves Geographic Handicaps: No living near equator or tropics Faction Technology Disparity: None (all equal) Inter-Faction Interaction: False Exposure to Natural Disasters/Run-up Events: Equal (don't ask me how, it's just being held constant!) Victory Condition: Survive 10000 years ``` Simulation Successful! Simulation of the following factions has begun: [![enter image description here](https://i.stack.imgur.com/bjiWR.jpg)](https://i.stack.imgur.com/bjiWR.jpg) Let me start with some disclaimers so the purpose and scope is clear. Also it's important to read the disclaimers to keep the question from being too broad. Disclaimer 1: I know that humans are a technology-intensive species, but the main purpose of this simulation/thought experiment has nothing to do with technology. That's why in the simulation I stipulate `Technology Level: Stone Age, VARIABLE`. Meaning that upon simulation, all four factions of humans are brainwashed and given a random culture/technology level. For example, in a simulation where `Technology= Stone Age(Caucasoid)` that means Caucasoids, Negroids, Mongolids and Australoids are given Caucasoid Technology/Culture. That way technology and culture can be non-factors, allowing us to only examine physical/genetic attributes. I think this is the only way to do it because "Stone Age" technology is different in each part of the world. In your answer you can define your own scope as you see fit. For example, you may say things like: Generally, across all simulations ... or...In simulations where technology=Mongoloid ... Disclaimer 2:* Caucasoids, Negroids, Mongoloids and Austaloids are general skeleton types. Each one has many, many distinct ethnicities and historical cultures/technologies. In light of this, I'm narrowing the scope greatly by simply merging/averaging them. In other words, we are not nit-picking which specific ethnicity they are, but rather we are viewing them as aggregate cultural/technological embodiments of their many ethnicities -- with their technology averaged as well. Purely for illustration purposes, consider the following: say most Negroid stone age archaeological sites support the premise of having excellent sewing technology, except for a few outlier archaeological sites in this one country where the stitching is really bad or whatever, just consider Negroid sewing to be pretty good. That's what I mean by averaged. I'm not expecting an Archaeological Thesis or anything. Heck, if you think it's too complicated, then just ignore the culture/technology dimension altogether. I don't mind; like I said, I'm not interested in technology. I'm only interested in physical trait advantages/disadvantages. From this futuristic simulation, I'm trying to answer a few inter-related questions. Namely, which traits of the factions would play a big role. For example, given the "No living in caves" handicap, unless I'm mistaken, that would mean Caucasoids would have a bit of a disadvantage because of their comparatively fair skin. Being unable to dwell in caves would force them to spend more time in the ultra-violet than their genetic lineage is accustomed to. However, I'm not sure if that would be a more of a small nuisance or a death-blow. Question: If we uproot Caucasoids, Negroids, Mongoloids and Australoids from their respective ancestral geographic regions and force them to live in a cold ice-age world (with a few handicaps) as per the simulation above, would each faction have the same chances of success, all else held equal? Or would certain traits get in the way, what traits would be helpful? Side Question: If you want to go the extra mile, consider answering this question too: Would each faction look the same after 10,000 years? Maybe a few would have died off?	If I had to pick one group it would be Negroids becasue most of human genetic variability is within that group, its not a big advantage but I you had to pick one group it would be that one just becasue they have more variability to work with. Of course evolution tends not to parse that way, it will be individual populations that survive and spread not wide racial groups but you are more likely to find the right combination of traits in that group. But really all those groups will survive equally well, human variability is pretty minor, and so much will depend on other variables, like technology, location, livestock, run up events, etc. But your biggest effect will be which population was living is the most similar conditions you drop them in,the knowledge of the individual's dropped into this situation will have a much bigger effect than anything genetic. If I drop Bob and Tom in a new environment and Bob was a hunter gather and Tom was a wall street stockbroker, Genetics matters less than the fact Bob knows how to start a fire and Tom does not.
107,426	<p>Julius Caesar used a substitution cipher (now called a Caesar cipher) for sensitive private and military correspondence. The cipher involves shifting all of the letters in a message in one direction a secret number of times, wrapping around if necessary. This appears to have done well for Caesar, but could he have done better? The cipher itself is quite trivially breakable.</p> <p>What if Julius Caesar had been given access to a one-time pad, or OTP? An OTP is an encryption technique that is unbreakable when used correctly. The key must be the same size as the message and completely random, but if it is, it provides <em>information-theoretic security</em>. The way it works is simple. The pad is the same size as the message to be encrypted. You add the position of each letter in the pad (1 for A, 2 for B, etc) to the position of each letter in the message, modulo the size of the alphabet. An example encryption of "HELLO" using pad "XMCKL" from Wikipedia:</p> <pre> H E L L O message 7 (H) 4 (E) 11 (L) 11 (L) 14 (O) message + 23 (X) 12 (M) 2 (C) 10 (K) 11 (L) key = 30 16 13 21 25 message + key = 4 (E) 16 (Q) 13 (N) 21 (V) 25 (Z) (message + key) mod 26 E Q N V Z → ciphertext E Q N V Z ciphertext 4 (E) 16 (Q) 13 (N) 21 (V) 25 (Z) ciphertext - 23 (X) 12 (M) 2 (C) 10 (K) 11 (L) key = -19 4 11 11 14 ciphertext – key = 7 (H) 4 (E) 11 (L) 11 (L) 14 (O) ciphertext – key (mod 26) H E L L O → message </pre> <p>A random pad can be trivially generated by flipping a coin to determine which letter is present. The pad is delivered securely to the correspondents. It is one of the few concepts in cryptography that are completely and provably unbreakable. How would the Roman Empire's role in history change if:</p> <ul> <li>Julius Caesar and his private correspondents knew of the technique?</li> <li>the concept of the OTP itself was widely known throughout the empire?</li> </ul> <p>In practice, the OTP would allow the Roman Empire to communicate with <em>perfect secrecy</em>. I could very well be overestimating how important this was for them, but it seems to me like it would lead to a rather large change given that more secret messages could be sent between two parties without needing to trust the messenger. It could have major ramifications.</p>	[ { "answer_id": 107427, "author": "Contramallum", "author_id": 48844, "author_profile": "https://worldbuilding.stackexchange.com/users/48844", "pm_score": -1, "selected": false, "text": "<ol>\n<li><p>No effect. This technique has very limited use given that all communication in that age w...	2018/03/20	[ "https://worldbuilding.stackexchange.com/questions/107426", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/20149/" ]	Julius Caesar used a substitution cipher (now called a Caesar cipher) for sensitive private and military correspondence. The cipher involves shifting all of the letters in a message in one direction a secret number of times, wrapping around if necessary. This appears to have done well for Caesar, but could he have done better? The cipher itself is quite trivially breakable. What if Julius Caesar had been given access to a one-time pad, or OTP? An OTP is an encryption technique that is unbreakable when used correctly. The key must be the same size as the message and completely random, but if it is, it provides information-theoretic security. The way it works is simple. The pad is the same size as the message to be encrypted. You add the position of each letter in the pad (1 for A, 2 for B, etc) to the position of each letter in the message, modulo the size of the alphabet. An example encryption of "HELLO" using pad "XMCKL" from Wikipedia: ``` H E L L O message 7 (H) 4 (E) 11 (L) 11 (L) 14 (O) message + 23 (X) 12 (M) 2 (C) 10 (K) 11 (L) key = 30 16 13 21 25 message + key = 4 (E) 16 (Q) 13 (N) 21 (V) 25 (Z) (message + key) mod 26 E Q N V Z → ciphertext E Q N V Z ciphertext 4 (E) 16 (Q) 13 (N) 21 (V) 25 (Z) ciphertext - 23 (X) 12 (M) 2 (C) 10 (K) 11 (L) key = -19 4 11 11 14 ciphertext – key = 7 (H) 4 (E) 11 (L) 11 (L) 14 (O) ciphertext – key (mod 26) H E L L O → message ``` A random pad can be trivially generated by flipping a coin to determine which letter is present. The pad is delivered securely to the correspondents. It is one of the few concepts in cryptography that are completely and provably unbreakable. How would the Roman Empire's role in history change if: * Julius Caesar and his private correspondents knew of the technique? * the concept of the OTP itself was widely known throughout the empire? In practice, the OTP would allow the Roman Empire to communicate with perfect secrecy. I could very well be overestimating how important this was for them, but it seems to me like it would lead to a rather large change given that more secret messages could be sent between two parties without needing to trust the messenger. It could have major ramifications.	The same problems that a normal one time pad face would be faced by our hypothetical Caesar. Namely, if you want to send me a message, I need to have: 1. A one time pad at least as long as your message (or, if we're willing to settle for a shorter cipher, as many ciphers as you have messages) 2. Received every message you've sent me up until your current one (and both of us destroying pads once they've been used) 3. Successfully hidden my one time pad from the enemy This creates a tricky situation. If I run out of pad, you can't send me more messages without somehow getting me a new pad. If a message gets intercepted, you need to somehow figure that out and tell me how much I need to increment by. We can get around this by, say, discarding a page every day or numbering the pads, but this means a lot more pad and leads into the third problem: I need to hide at least twice as many documents as you're sending. To decode a letter I need the letter and its key. That's two documents I could be caught with and executed for, and two documents that might be intercepted, either of which would ruin the message. With all that said, it probably wouldn't see a great deal of use outside of very special circumstances where it's better to lose the information outright rather than risk discovery- internal affairs rather than wars. A regional governor has perverse tastes, and if discovered the province could revolt. Still the agent needs to inform their superior so it can be handled discreetly, so the one time pad is used. In crisis situations they probably wouldn't be used - if the byzantine generals are trying to coordinate, losing the critical message to a messenger being intercepted is worse than the defenders getting hold of the plan. Of note, the message loss problem can be solved if I retain used pads to decode corrupted messages and cope with messages arriving out of order, but this then becomes more of a codebook than a one time pad. For the circumstances we would want to use a one time pad (ie. where we would prefer for nobody to know the message over the proverbial Eve knowing it) it represents something of an unwelcome risk.
108,021	<blockquote> <p>...and while I'm at it: You've another 47 seconds to finish up and get back here before I gotta throw her in reverse...</p> </blockquote> <p>Acting Navvy on the <em>Marube</em> @63kph and ~4km distance from a forthcoming train</p> <hr> <p>Welcome to <em>a</em> future. Mankind has brought doom upon themselves, their cities have been flattened by war and weather, and most of the northern hemisphere is radioactive badlands.</p> <p>After having <a href="http://tvtropes.org/pmwiki/pmwiki.php/Main/EndlessWinter" rel="nofollow noreferrer">helped their planet to cool down a tad</a>, humans start emerging from their underground retreats to once again make the surface theirs.</p> <p>Patching and recommissioning <a href="https://worldbuilding.stackexchange.com/questions/101288/train-world-feasibility-of-radioisotope-steam-electric-engines">pre-war trains engines</a> they reconnect and spread along the old rail infrastructure. Settling the, now temperate, equatorial regions and scouring the desolate northern ones for technology.</p> <p>Due to the vast expanse & unregulated nature of these rail-networks, and the size, state & character of these post-war communities, there is no single organisation or group that could realistically control more than a small section of the network - huge parts of it are thus <em>wild</em>.</p> <p>As a result of that, most trains don't go above speeds at which they can safely break, if there is something wrong with the tracks or an oncoming train. Spoorcaneers (rail-pirates) actively make use of these circumstances by keeping their trains short and quick in order to catch-up with booty or even overtake it.</p> <hr> <p>Pirate trains are usually made up of a single engine and a multi-purpose boxcar. Some compositions feature another boxcar or a flatcar offering additional space for e.g. gun emplacements or expected special cargo. There are seldom trains with two ore more engines, as a second engine is of much more use driving a second, independent, train instead.</p> <p>When boarding, the more adventurous pirates pull their trains up in parallel to their bounty - akin to the buccaneers of old. This provides more area to transfer valuables between cars and even allows to transfer bigger things.</p> <pre><code>========SPOORCANEERS->>=====================================<<-ONCOMING-TRAIN============= ======VERY-RICH-BOUNTY-TRAIN->>=========================================================== </code></pre> <p><sup>Just <em>in case</em>. The above diagram is obviously <em>not to scale</em>..</sup></p> <p>Due to the nature of their business though, pirates need to be able to turn on their heels at any moment. Be that to escape the possible artillery of a train they preyed upon unsuccessfully, or to clear the tracks before an oncoming train smashes theirs to bits.</p> <p>An example of the latter would be two trains moving towards each other, both at ~60kph. The pirate train can spot the oncoming train at ~4km distance (<a href="https://en.wikipedia.org/wiki/Horizon#Objects_above_the_horizon" rel="nofollow noreferrer">curvature, horizon</a>). As soon as they can see the oncoming train they will have to think about reversing, yet they still need some time, give some ~30-45s, to clear their crew off the bounty train.</p> <hr> <p><strong>Q: How could a system be designed to allow reversing a train at high speed over such a short distance?</strong></p> <p>A <em>good</em> solution:</p> <ul> <li>is <strong>sustainable</strong>, track infrastructure and trains suffer as little damage as possible</li> <li>can <strong>turn quickly</strong>: <ul> <li>the less time between <em>speed</em> -> <em>stop</em> -> <em>speed</em>, the better</li> <li>the less distance it takes between a <em>full break</em> back <em>to starting speed</em>, the better</li> </ul></li> <li>does work for <strong>higher speeds</strong>, being able to do this at higher speeds means being able to prey on faster trains</li> <li>makes use of <strong>as little engines as possible</strong>, engines are valuable and two independent trains are worth much more than one slightly faster train</li> </ul> <p>This <em>question is <strong>NOT</strong> about</em>:</p> <ul> <li>finding solutions to alternative situations; an <strong>example is given</strong> in the body, please do not start changing things to fit your idea</li> <li>finding a workaround; <strong>switching tracks</strong> is a great idea, but it's not a solution to the issue at hand</li> </ul>	[ { "answer_id": 108027, "author": "AndyD273", "author_id": 6751, "author_profile": "https://worldbuilding.stackexchange.com/users/6751", "pm_score": 3, "selected": false, "text": "<p>So, to get a couple comments out of the way first, I'm not really sure why you would want to rob the train...	2018/03/27	[ "https://worldbuilding.stackexchange.com/questions/108021", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/2746/" ]	> > ...and while I'm at it: You've another 47 seconds to finish up and get back here before I gotta throw her in reverse... > > > Acting Navvy on the Marube @63kph and ~4km distance from a forthcoming train --- Welcome to a future. Mankind has brought doom upon themselves, their cities have been flattened by war and weather, and most of the northern hemisphere is radioactive badlands. After having [helped their planet to cool down a tad](http://tvtropes.org/pmwiki/pmwiki.php/Main/EndlessWinter), humans start emerging from their underground retreats to once again make the surface theirs. Patching and recommissioning [pre-war trains engines](https://worldbuilding.stackexchange.com/questions/101288/train-world-feasibility-of-radioisotope-steam-electric-engines) they reconnect and spread along the old rail infrastructure. Settling the, now temperate, equatorial regions and scouring the desolate northern ones for technology. Due to the vast expanse & unregulated nature of these rail-networks, and the size, state & character of these post-war communities, there is no single organisation or group that could realistically control more than a small section of the network - huge parts of it are thus wild. As a result of that, most trains don't go above speeds at which they can safely break, if there is something wrong with the tracks or an oncoming train. Spoorcaneers (rail-pirates) actively make use of these circumstances by keeping their trains short and quick in order to catch-up with booty or even overtake it. --- Pirate trains are usually made up of a single engine and a multi-purpose boxcar. Some compositions feature another boxcar or a flatcar offering additional space for e.g. gun emplacements or expected special cargo. There are seldom trains with two ore more engines, as a second engine is of much more use driving a second, independent, train instead. When boarding, the more adventurous pirates pull their trains up in parallel to their bounty - akin to the buccaneers of old. This provides more area to transfer valuables between cars and even allows to transfer bigger things. ``` ========SPOORCANEERS->>=====================================<<-ONCOMING-TRAIN============= ======VERY-RICH-BOUNTY-TRAIN->>=========================================================== ``` Just in case. The above diagram is obviously not to scale.. Due to the nature of their business though, pirates need to be able to turn on their heels at any moment. Be that to escape the possible artillery of a train they preyed upon unsuccessfully, or to clear the tracks before an oncoming train smashes theirs to bits. An example of the latter would be two trains moving towards each other, both at ~60kph. The pirate train can spot the oncoming train at ~4km distance ([curvature, horizon](https://en.wikipedia.org/wiki/Horizon#Objects_above_the_horizon)). As soon as they can see the oncoming train they will have to think about reversing, yet they still need some time, give some ~30-45s, to clear their crew off the bounty train. --- Q: How could a system be designed to allow reversing a train at high speed over such a short distance? A good solution: * is sustainable, track infrastructure and trains suffer as little damage as possible * can turn quickly: + the less time between speed -> stop -> speed, the better + the less distance it takes between a full break back to starting speed, the better * does work for higher speeds, being able to do this at higher speeds means being able to prey on faster trains * makes use of as little engines as possible, engines are valuable and two independent trains are worth much more than one slightly faster train This question is NOT* about: finding solutions to alternative situations; an example is given in the body, please do not start changing things to fit your idea * finding a workaround; switching tracks is a great idea, but it's not a solution to the issue at hand	So, to get a couple comments out of the way first, I'm not really sure why you would want to rob the train from another train (except for the rule of cool), especially since they are traveling so slow. I can totally see there being a Mad Max style thing where a racing vehicle drives up next to the train, someone jumps out of the vehicle onto the train, and either takes the engine, or decouples some cars so they can be looted. Alternately they could also just come up behind them with a train on the same track, have someone jump forward to the target train, and take it over, so they don't have to worry about oncoming trains. But those are both just comments, and don't answer the question. So part of the problem is that freight trains are not meant to be stopped and started or reversed quickly. It's just not their purpose. They need to be able to have as little rolling resistance as possible, and with all that weight you potentially have miles of distance before you come to a complete stop. But the pirate train needs to be able to get up to speed quickly, stop quickly, reverse quickly, and doesn't have to be big or heavy. So instead of a freight train, it could be a passenger train, which by definition need to be able to do all of those things. [They can even go from 80 kph to 0 in less than 20 seconds](https://www.youtube.com/watch?v=gVpucnA6Pq8). You strip out the seats, put some tie downs inside, gun emplacements on top, and it has everything you need.
110,493	<p>I am preparing world for my novel. One of the races in my world is elves. To make my world believable I would like to incorporate the Elvish language. I am big fan of Tolkien or Sapkowski's Elvish language. However as their work is copyrighted I believe I cannot use these. Is there something like an Elvish language that can be freely used in other works? </p> <p>EDIT: To clarify my intents: I personally think it would be cool if there were conlangs for such commonly used races as elves (or others). If there is something that can be shared across multiple universes, it might be a good factor for geeks to maybe even learn that language. I am not speaking only about Tolkien's Elvish, although that is probably the most complete one. </p> <p>This is why I am talking about <strong>open source</strong> rather than <strong>free</strong>. I am a software developer so these terms seem pretty descriptive for me. It doesn't even have to be always the same language - there may be different dialects and anyone can make slight customizations (in open source terminology <strong>forks</strong>). These customizations can be incorporated under certain conditions in the main "branch" helping to make the language even more developed - for example, expanding vocabullary.</p> <p>I don't want to "bypass" copyright. I think it is fair for authors to protect their work if they want to do so. But if something like this already exists, I am willing to use it and help to add new words to the vocabulary etc.</p>	[ { "answer_id": 110494, "author": "ArtificialSoul", "author_id": 44086, "author_profile": "https://worldbuilding.stackexchange.com/users/44086", "pm_score": 3, "selected": false, "text": "<h3>Apparently not</h3>\n\n<p>I have been searching and the only answers I have found are already men...	2018/04/25	[ "https://worldbuilding.stackexchange.com/questions/110493", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/49533/" ]	I am preparing world for my novel. One of the races in my world is elves. To make my world believable I would like to incorporate the Elvish language. I am big fan of Tolkien or Sapkowski's Elvish language. However as their work is copyrighted I believe I cannot use these. Is there something like an Elvish language that can be freely used in other works? EDIT: To clarify my intents: I personally think it would be cool if there were conlangs for such commonly used races as elves (or others). If there is something that can be shared across multiple universes, it might be a good factor for geeks to maybe even learn that language. I am not speaking only about Tolkien's Elvish, although that is probably the most complete one. This is why I am talking about open source rather than free. I am a software developer so these terms seem pretty descriptive for me. It doesn't even have to be always the same language - there may be different dialects and anyone can make slight customizations (in open source terminology forks). These customizations can be incorporated under certain conditions in the main "branch" helping to make the language even more developed - for example, expanding vocabullary. I don't want to "bypass" copyright. I think it is fair for authors to protect their work if they want to do so. But if something like this already exists, I am willing to use it and help to add new words to the vocabulary etc.	All Elvish is (probably) open source (in the US) ================================================ There is a real legal history of battles over open source languages, two threads of which are relevant here. The first is that the US court system has definitively ruled that it is not a violation of a constructed computer programming language's copyright to write a new computer program using the same language and grammar. Although there have been no definitive cases regarding 'conlangs' (constructed languages), the other thread is the situation of the legal battle over [Prelude to Axanar](https://en.wikipedia.org/wiki/Prelude_to_Axanar). ### General background information There was a journal of Tolkien's linguistics titled [Tyalië Tyelelliéva](http://tolkiengateway.net/wiki/Tyali%C3%AB_Tyelelli%C3%A9va), originally hosted on GeoCities and now gone. This journal published original works in Tolkien's languages in addition to other analysis, but evidently ran afoul of Tolkien's estate which in 1999 took the stance that Quenya and Sindarin in particular (and presumably all Tolkien's languages in general) were copyrighted. The journal publishers sought the legal advice of the General Counsel of the National Endowment of the Arts who sent back a legal opinion. [Here](http://www.oocities.org/athens/parthenon/9902/legalop.html) is the only link I could find of this opinion; much of the hard evidence of this whole situation is shrouded in the mists of lost GeoCities. The main points of the opinion were these: * Words, short phrases, names, symbols, typefaces, and variations of lettering are not subject to copyright protection by [37 C.F.R. 202.1 (1974)](https://www.copyright.gov/title37/202/37cfr202-1.html) [that is the title of a US Congressional act] * "In no case does copyright protection for an original work of authorship extend to any idea, procedure, process, system, method of operation, concept, principle, or discovery, regardless of the form in which it is described, explained, illustrated, or embodied in such work." ([17 U.S.C. 102(b)](https://www.copyright.gov/title17/92chap1.html)). * Tolkien's languages, by his own self-admission, derive significantly from extant or extinct world languages, which are of course not copyright-able. The fact that many proper nouns like 'Osgiliath,'Theoden', and 'Celebrian' have an origin in real, historical languages makes claims of 'originality,' which is a necessary pre-requisite of copyright, difficult to establish. * "...the fair use of a copyrighted work, including such use by reproduction in copies or phonorecords or by any other means specified by that section, for purposes such as criticism, comment, news reporting, teaching (including multiple copies for classroom use), scholarship, or research, is not an infringement of copyright." ([Title 17 U.S.C. 107](https://www.copyright.gov/title17/92chap1.html#107)) The author of the legal opinion thinks that a journal with original poetry constitutes fair use. The journal in question here evidently folded around 2001, and no court proceedings (so far as I can determine) were filed on either side, so this is just background information and not legally binding. For more background information, a more exhausting study was made by [Harvard Law Review](https://consumermediallc.files.wordpress.com/2016/04/27harvjltech543.pdf) in 2014. A longer read, this summarized existing conlang legal actions (there have been none that actually went to court), and comes to the conclusion that copyright law is ill-suited to regulation of a constructed language, although it stops sort of giving an opinion on the legality of third-party usage of a constructed language. ### The case of computer programming languages In general, the grammatical principles of a computer language are not copyrightable. If a Python 'Hello World' program looks like ``` print("Hello World") ``` there is nothing preventing me from writing a programming language and/or compiler that uses the exact same syntax to create the exact same effect. This is the decision of [Computer Assocs. Int'l, Inc. v. Altai, Inc., 982 F.2d 693, 720-21 (2d Cir.1992)](https://scholar.google.com/scholar_case?case=6976925648486076739&hl=en&as_sdt=6,47&as_vis=1). Following the Supreme Court decision [Baker vs. Selden](https://scholar.google.com/scholar_case?case=16308210976883953911&hl=en&as_sdt=6,47&as_vis=1) which "denies copyright protection to expression necessarily incidental to the idea being expressed", this case settled on the 'merger doctrine' which states that > > [C]opyrighted language may be copied without infringing when there is > but a limited number of ways to express a given idea.... In the > computer context, this means that when specific instructions, even > though previously copyrighted, are the only and essential means of > accomplishing a given task, their later use by another will not amount > to infringement. > > > So if my programming language wants to use the exact syntax ``` print("Hello World") ``` there are only a limited number of way to express this idea, and I can copy a copyrighted work (such as a copyrighted Python program that uses that exact line of code) without infringing on the copyright. By this logic, if a court would apply it to conlangs, which has not yet been done, I could copy Sindarin sentance structure, even if Sindarin has a valid copyright, without infringing; thereby allowing me to generate original works. ### The case of Prelude to Axanar There have long been Star Trek fan films, mostly (in my opinion) terrible. Evidently, Axanar was to be a fan film with a budget of over $1 million, some serious production values, support of Important Star Trek People like George Takei, and even some actors who had appeared in other Star Trek movies. Paramount, which had hitherto been relatively tolerant of fan films, sued for copyright infringement. Paramount had a [pretty strong case](https://www.washingtonpost.com/news/volokh-conspiracy/wp/2017/01/09/copyright-in-klingon/?noredirect=on&utm_term=.dd942aba40ab), since characters like Garth of Izar and fictional races like Vulcans and Klingons are pretty clearly copyright-able. Eventually, the [case was settled](https://en.wikipedia.org/wiki/Prelude_to_Axanar#Lawsuit) in 2017. However, in the course of the lawsuit, Paramount asserted a claim to control over the fictional languages. Sort of. This was probably never a claim that Paramount really wanted to make, but was just involved in the legal claptrap. The Language Creation Society (LCS) filed an [amicus brief](https://drive.google.com/file/d/0BzmetJxi-p0VM19nbUpyNXE0a28/view) stating that conlangs were not copyrightable, and the defendants (the producers of Axanar) [filed a motion](https://torrentfreak.com/images/lim.pdf) that also said in part that the Klingon language could not be copyrighted. The defendent's motion was accepted by the court, so the copyright issue over the constructed language was excluded; the LCS's amicus brief was then [rejected](https://drive.google.com/file/d/0BzmetJxi-p0VN0t5MWNPOTZ4SU0/view) by the court as not applicable. Ultimately, this case decided nothing. Paramount had a strong case with characters and races and organizations and probably wasn't willing to risk a negative opinion on constructed languages. If anyone is going to file a lawsuit to get open use of a constructed language, it won't be about Klingon since Paramount is a lot richer than the inventor of any other conlangs. But it is relevant that the judge was willing to accept the defendant's reasoning which referenced the same Baker vs Selden which provided the precedent with computer programming languages. Conclusion ========== There is no official court decision on whether the grammar and vocabulary of a constructed language, being utilitarian in nature, can be copyrighted. However, there is some good evidence and legal opinions that, in the US at least, such copyright laws would not apply. Of course someone has to test this in court. Maybe it could be you? If Tolkien's estate comes knocking, you could fire up a GoFundMe and appeal to all the language nerds out there. Your Name vs Tolkien would get its own Wikipedia page and article in the Harvard Law Review...you'd be famous!
110,967	<p>In my story interstellar travel is common, but nothing's perfect, and a mining ship returning from a deep-space run (you'd be surprised what's out there) just discovered that something is very, very wrong.</p> <pre><code>\crackle\ Mayday... Mayday... this is the Tycho Brahe... Primary engine offline. Asteroid impact in the Oort cloud. Request assistance... over. \squeal\ Tycho Brahe... this is Sol reference Alpha. What is your vector to the initial... over. Sol Alpha, Tycho Brahe, solar declination +23°, right ascension -87°, Delta-forty-alpha, Victor-five-charlie. ... Sol Alpha, Tycho Brahe, are you still there? Tycho Brahe, Sol Alpha, negative on assistance. Repeat, negative on assistance. Recommend deploying solar sails and maintain vector to the initial... over. </code></pre> <p><strong>Question:</strong>&emsp;Given 40 Km<sup>2</sup> solar sails (and ignoring necessary support structure), is it possible for a ship with a mass of 5,000,000 Kg traveling at 0.05c at a distance of 40AU from the sun to deploy those sails and, using only the solar wind, decelerate to 250,000 Kph before crossing the "orbital sphere" of Mercury?</p> <hr> <p><strong>Solar Declination & Ascension</strong>&emsp;<em>This doesn't actually have anything to do with the question, but just for fun and off the top of my head (please let me know if I've plagarized a published story!), I defined the reference for solar declination and solar ascension as measured from the line drawn from the center of the sun to the center of the galaxy and otherwise used in the same way Astronomers use declination and ascension. It eliminates the position of the earth from the equation (making the reference static and applicable by math to any body in the solar system ... or any solar system). Thus, "Vector to the initial" would always be your position and speed in relation to an approach toward the center of the sun.</em></p> <p><em>If I haven't plagarized from somewhere... I thought of it first!</em> </p> <p><strong>Victor-five-charlie</strong>&emsp;<em>Also for fun, an over-the-radio way of saying "my velocity (victor) is 5% or 0.05 of the speed of light (charlie)." The percentage is always assumed.</em></p> <p><strong>Delta-Forty-Alpha</strong>&emsp;<em>Ditto, the distance from the sun along the indicated vector in "alpha" or AU.</em></p> <p><strong>Vector to the Initial</strong>&emsp;<em>Yes, I'm not using this in the same way today's pilots do.</em></p> <p><strong>Orbital Sphere</strong>&emsp;<em>Out of curiosity, do astronomers today have a phrase that identifies the sphere enclosing a radius from the sun equal to a planetary orbital distance?</em></p>	[ { "answer_id": 110973, "author": "abestrange", "author_id": 49104, "author_profile": "https://worldbuilding.stackexchange.com/users/49104", "pm_score": 4, "selected": true, "text": "<p>Edit: I did make a math error, the points below still stand though.</p>\n\n<p>No. The solar wind pressu...	2018/04/30	[ "https://worldbuilding.stackexchange.com/questions/110967", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/40609/" ]	In my story interstellar travel is common, but nothing's perfect, and a mining ship returning from a deep-space run (you'd be surprised what's out there) just discovered that something is very, very wrong. ``` \crackle\ Mayday... Mayday... this is the Tycho Brahe... Primary engine offline. Asteroid impact in the Oort cloud. Request assistance... over. \squeal\ Tycho Brahe... this is Sol reference Alpha. What is your vector to the initial... over. Sol Alpha, Tycho Brahe, solar declination +23°, right ascension -87°, Delta-forty-alpha, Victor-five-charlie. ... Sol Alpha, Tycho Brahe, are you still there? Tycho Brahe, Sol Alpha, negative on assistance. Repeat, negative on assistance. Recommend deploying solar sails and maintain vector to the initial... over. ``` Question: Given 40 Km2 solar sails (and ignoring necessary support structure), is it possible for a ship with a mass of 5,000,000 Kg traveling at 0.05c at a distance of 40AU from the sun to deploy those sails and, using only the solar wind, decelerate to 250,000 Kph before crossing the "orbital sphere" of Mercury? --- Solar Declination & Ascension This doesn't actually have anything to do with the question, but just for fun and off the top of my head (please let me know if I've plagarized a published story!), I defined the reference for solar declination and solar ascension as measured from the line drawn from the center of the sun to the center of the galaxy and otherwise used in the same way Astronomers use declination and ascension. It eliminates the position of the earth from the equation (making the reference static and applicable by math to any body in the solar system ... or any solar system). Thus, "Vector to the initial" would always be your position and speed in relation to an approach toward the center of the sun. If I haven't plagarized from somewhere... I thought of it first! Victor-five-charlie Also for fun, an over-the-radio way of saying "my velocity (victor) is 5% or 0.05 of the speed of light (charlie)." The percentage is always assumed. Delta-Forty-Alpha Ditto, the distance from the sun along the indicated vector in "alpha" or AU. Vector to the Initial Yes, I'm not using this in the same way today's pilots do. Orbital Sphere Out of curiosity, do astronomers today have a phrase that identifies the sphere enclosing a radius from the sun equal to a planetary orbital distance?	Edit: I did make a math error, the points below still stand though. No. The solar wind pressure simply isn't strong enough to stop you. Making larger sails would increase the force applied to your ship, but would well surpass known material shear strengths and would destroy itself. Assume a constant acceleration for simplicities sake and we can use: $DeltaX = 1/2\Acc\Time^2 + Vel\_{initial}\time$ $Acc = (Vel\_{final} - Vel\_{initial})/time$ Rearranging those gives us $Acc = (V\_f-V\_i)\(v\_f+v\_i)/(2\deltaX)$ Using $V\_f = 250,000 KpH = 67444.4 m/s$ $V\_i = 0.05\c = 0.05\3\10^8 =$ ~~45,000,000~~ $15,000,000 m/s$ $DeltaX = 40 AU = 40\149,597,870,700 = 5,983,914,828,000 m$ We get an acceleration of ~~-169 m/s^2, or about 17 g's.~~ $18.8m/s^2$ or 1.9 g's Humans can't really survive more than a couple g's for extended durations. This example is assuming a constant acceleration, which is even worse for our real life use case. The solar flux is going to fall off with the inverse square law over distance, so at 40 AU it is going to be ~1600 times weaker than it is at 1 AU. Achieving 17 g's of average acceleration over our distance will require a gentle deceleration at the start of our journey and a massive amount of force near the end as the solar wind density increases. This will absolutely shatter any plausible sail support structure and kill your crew. ~~0.05 c is probably too fast for any inhabited ship to decelerate from in 40 AU.~~ Uncomfortable but survivable. ~~If you can take it down by a factor of 10, to 0.005c, then the required average acceleration is -0.187m/s^2, which enters into the realm of plausibility for a large enough sail.~~ -0.187m/s^2 is still way outside the realm of plausibility for our situation. Addendum: So the numbers above are a bit off, and our required acceleration would be survivable, so I decided to run even further to see what the necessary pressure from our solar wind would be.* $Force = mass\Acc$ $Pressure = Force/Area = mass\Acc / Area $ $Pressure = 5,000,000kg \* 18.8m/s^2 / ( 40\1000^2 m^2) = 2.345 N/m^2$ The typical pressure from solar wind at 1 AU is $6\10^{-9} N/m^2$, our required average pressure is $2.345 N/m^2$ , almost 9 full orders of magnitude higher. Keep in mind that the average solar wind pressure will be around $3.75\10^{-12} N/m^2$ at 40AU, thanks on the inverse square law, and our situation really looks bleak. To achieve our necessary acceleration will require a surface area of: $Force = Pressure\Area = Mass\Acc $ $Area = Mass\Acc / Pressure = 5,000,000kg \* 18.8m/s^2 / 6\10^{-9} N/m^2$ $Area = 1.56 \ 10^{16} m^2 = 1.56\*10^{10} km^2 $ That's a square sail with side length 125,166 km, which would require MUCH more mass than we are accounting for. Using 0.005 c we still need a sail that is a disk with a radius of 7054km, which is a bit bigger than the Earth's radius. And remember thats assuming we have a constant flux equal to that at 1 AU. In reality its much worse. Solar wind is simply not dense enough to slow you down appreciably, especially when you factor that the sun's gravity will be accelerating you towards it, probably with more force than our sail can generate. To slow down your craft, you will have to eject mass. Forcefully jettisoning your sail will probably net you more deltaV than trying to use it. If you have a magnetic acceleration cannon of any type, start scrapping unnecessary (non-vital) modules of your ship and firing them at max power straight ahead. Venting atmosphere will help too. Good luck.
112,647	<p>I think I've done my research about multi tasking on humans, but this is a whole new level</p> <p>I have a conqueror, where he creates nanobot creatures instantaneously (handwaving the transformation process).</p> <p>He can create 5 types of Creatures.</p> <pre><code> 1. Lesser Demons (3 feet Nepylims) 2. Hunters (5 feet beast with features of a humanoid lion) 3. Greater Demon (8 Feet Ogre with clubs as hands) 4. Piranhas (for undersea attacks) 5. Deimos (A 250 Feet Tall Dragon) </code></pre> <p>I think controlling one creature s perfectly simple, but an army?</p> <p>I would like to ask, can a average brain control an army this size? </p> <p>Numbers would be:</p> <pre><code>3000 Lesser Demons 1500 Hunters 2000 Greater Demons 5000 Piranhas 500 Deimos </code></pre> <p>The basic commands would be:</p> <pre><code>1. Move forward 2. Search for living Humans(using heat sensors from the nanobots) 3. Destroy </code></pre> <p>The advance commands would be:</p> <pre><code>1. Move forward 2. Search for machines 3. If machine is dealing damage to nanobots, destroy 4. If Machine is not dealing any damage, move forward 5. If Machine is moving toward master, destroy 6. If Machine has explosive contents, destroy </code></pre> <p>The characteristic of the human controlling these nanobots: </p> <pre><code>1) Has some kind of controlling device implanted in his brain 2) Not a mutant, just your average intelligent human being (Like Tony Stark perhaps) 3) Average Body build, everything is average 4) Perfectly Healthy Individual </code></pre> <p>Please don't ask anything about the nanobots or how realistically the nanobots are created or controlled. I just want to know, if a human bran can realistically handle the stress of controlling a vast army using only his mind.</p> <p>Additional information may contain, If the conqueror's brain cannot handle such stress, aside from using computers, what can help the conqueror control an army? (you may or may not answer this)</p> <pre><code> 1. Reduce army size can be an answer? 2. Reduce size of the units? 3. Any alterations on the brain can be done, as long as it does not make him a mutant. </code></pre> <p>EDIT:</p> <p>I do know there are a lot of ways to kill the conqueror, but please, I would just like to ask if this feat (controlling many beasts) can be done.</p>	[ { "answer_id": 112650, "author": "The Square-Cube Law", "author_id": 21222, "author_profile": "https://worldbuilding.stackexchange.com/users/21222", "pm_score": 2, "selected": false, "text": "<p>I don't think Stark is an average intelligent person. His command of science is matched phera...	2018/05/19	[ "https://worldbuilding.stackexchange.com/questions/112647", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/28224/" ]	I think I've done my research about multi tasking on humans, but this is a whole new level I have a conqueror, where he creates nanobot creatures instantaneously (handwaving the transformation process). He can create 5 types of Creatures. ``` 1. Lesser Demons (3 feet Nepylims) 2. Hunters (5 feet beast with features of a humanoid lion) 3. Greater Demon (8 Feet Ogre with clubs as hands) 4. Piranhas (for undersea attacks) 5. Deimos (A 250 Feet Tall Dragon) ``` I think controlling one creature s perfectly simple, but an army? I would like to ask, can a average brain control an army this size? Numbers would be: ``` 3000 Lesser Demons 1500 Hunters 2000 Greater Demons 5000 Piranhas 500 Deimos ``` The basic commands would be: ``` 1. Move forward 2. Search for living Humans(using heat sensors from the nanobots) 3. Destroy ``` The advance commands would be: ``` 1. Move forward 2. Search for machines 3. If machine is dealing damage to nanobots, destroy 4. If Machine is not dealing any damage, move forward 5. If Machine is moving toward master, destroy 6. If Machine has explosive contents, destroy ``` The characteristic of the human controlling these nanobots: ``` 1) Has some kind of controlling device implanted in his brain 2) Not a mutant, just your average intelligent human being (Like Tony Stark perhaps) 3) Average Body build, everything is average 4) Perfectly Healthy Individual ``` Please don't ask anything about the nanobots or how realistically the nanobots are created or controlled. I just want to know, if a human bran can realistically handle the stress of controlling a vast army using only his mind. Additional information may contain, If the conqueror's brain cannot handle such stress, aside from using computers, what can help the conqueror control an army? (you may or may not answer this) ``` 1. Reduce army size can be an answer? 2. Reduce size of the units? 3. Any alterations on the brain can be done, as long as it does not make him a mutant. ``` EDIT: I do know there are a lot of ways to kill the conqueror, but please, I would just like to ask if this feat (controlling many beasts) can be done.	The issue is not controlling the army, but the limitations of your instructions. If you permit more powerful instructions, the job gets much easier. The issue is not the act of barking orders like "If Machine is not dealing any damage, move forward." That could be done. The difficult issue is whether or not following that order is a good idea. Presumably each creature has access to sensory information about the world around it. That sensor information is crucial in combat for deciding what to do. Otherwise you could get into situations where the machine is not dealing damage, but moving forward is moving into a trap. Collecting this kind of sensor information is well beyond what the human mind can do. I did the calculations a while back, and you can estimate the data processing capabilities of the brain at about 1Gb/s (based on the diameter of the spinal column and a whole lot of handwaving). That's a lot of data! If we use this with your army size of 12,000, we can reasonably expect that datalinks on the order of about 83Kb/s would completely saturate the human mind. The human retina outputs about 10,000Kb/s! The solution can be seen in the human mind. The conscious mind can handle about 120 bits/s (give or take... its a very rough heuristic). It relies on the subconscious parts of the brain to handle the remaining 999,999,880 bit/s. That information is processed locally, in smaller groups of neurons. Some of the information is relayed up to the conscious mind but the vast majority is handled locally. When you touch a hot stove, your hand begins pulling back before your brain even registers that it's hot. That actually gets initiated in the spinal column to save time! Likewise, your nanobot creatures should take over some of the processing as well. They should have decently advanced AIs. Consider what [ATLAS](https://www.youtube.com/watch?v=rVlhMGQgDkY) can do in terms of problem solving. This should be an absolute utter bare bones capability for your nanobots. They should be able to accept complex instructions at least as advanced as those given to ATLAS to initiate path-finding. In practice, they should be much more complex. How complex? Well, my recommendation would be to take a lesson from the military. Your army size is in the range of a [division](https://en.wikipedia.org/wiki/Military_organization#Modern_hierarchy), which is 6-20 thousand soldiers. A division is lead by a 2-star general. So don't think about what sorts commands you might issue to a battle-bots toy. Think about what sorts of commands a 2-star general may issue in war. Also, note that the 2-star doesn't relay commands directly to the PFCs on the front lines. There's an enormous hierarchy of officers and NCOs in between. This is not an accident. Each layer of this hierarchy is an opportunity for one individual to process information from their subordinates and issue new orders without involving the general at the top. You should leverage this as well. You may find there is indeed a more efficient structure, given the nature of your nanobots, but starting from the prior art of the military is an excellent way to go. They have literally spent thousands of years honing the art of commanding large numbers of individuals to act as one cohesive army. Leverage that!
116,869	<p>My world has a conlang that heavily emphasizes words in 'grades' of 5. For example the words for issues are grouped as: Danger-Threat-Risk-Hazard-Situation.</p> <p>Usually it isn't hard to find a set of things in groups of 5, since you can always move delineation points (e.g. drinks by alcohol content is Juice-Beer-Wine-Vodka-Spirits, skipping over a lot, but still a general sense).</p> <p>I have hit a brick wall when it comes to biomes though. In order to make it work I would like to create a 5x5 grid of biomes. Using a temperature/precipitation chart I was able to get up to:</p> <pre><code>╔════════╦════════╦═════════════╦══════════════════╦══════════════════════╦══════════════════════════╗ ║ ║ Colder ║ ║ ║ ║ Hotter ║ ╠════════╬════════╬═════════════╬══════════════════╬══════════════════════╬══════════════════════════╣ ║ Wetter ║ ? ║ ? ║ ? ║ ? ║ Tropical Rainforest ║ ╠════════╬════════╬═════════════╬══════════════════╬══════════════════════╬══════════════════════════╣ ║ ║ ? ║ ? ║ ? ║ Temperate Rainforest ║ Swamp ║ ╠════════╬════════╬═════════════╬══════════════════╬══════════════════════╬══════════════════════════╣ ║ ║ ? ║ ? ║ Temperate Forest ║ ??? ║ Tropical Seasonal Forest ║ ╠════════╬════════╬═════════════╬══════════════════╬══════════════════════╬══════════════════════════╣ ║ ║ ? ║ Taiga ║ Grassland ║ Woodland ║ Savanna ║ ╠════════╬════════╬═════════════╬══════════════════╬══════════════════════╬══════════════════════════╣ ║ Drier ║ Tundra ║ Cold Desert ║ Shrubland ║ ??? ║ Hot Desert ║ ╚════════╩════════╩═════════════╩══════════════════╩══════════════════════╩══════════════════════════╝ </code></pre> <p>As you can see I was easily able to fill in the hotter/drier side of the table, missing just a few biomes where I just have yet to come up with a good name due to unusual delineation points. My bigger issue is that entire upper triangle. I guess earth just doesn't have many cold, wet biomes? I can't think of a physics oriented reason why - which leads me to think it is semantic (we don't live anywhere that cold, so we just lump all cold climates into "tundra/taiga").</p> <p>Is there any way to come up with good words to describe cold/wet climates? Are they even possible? The language exists on a custom planet, so if the biomes could exist but just don't on earth all I need to do is 'create' them and come up with a good name for them (e.g. flowerscape if a biome caused mostly flowers as flora).</p>	[ { "answer_id": 116873, "author": "klypos", "author_id": 52495, "author_profile": "https://worldbuilding.stackexchange.com/users/52495", "pm_score": 1, "selected": false, "text": "<p>I do not agree with a lot of your matrix as it stands - I cannot see how swamp can be drier than tropical ...	2018/06/30	[ "https://worldbuilding.stackexchange.com/questions/116869", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/28830/" ]	My world has a conlang that heavily emphasizes words in 'grades' of 5. For example the words for issues are grouped as: Danger-Threat-Risk-Hazard-Situation. Usually it isn't hard to find a set of things in groups of 5, since you can always move delineation points (e.g. drinks by alcohol content is Juice-Beer-Wine-Vodka-Spirits, skipping over a lot, but still a general sense). I have hit a brick wall when it comes to biomes though. In order to make it work I would like to create a 5x5 grid of biomes. Using a temperature/precipitation chart I was able to get up to: ``` ╔════════╦════════╦═════════════╦══════════════════╦══════════════════════╦══════════════════════════╗ ║ ║ Colder ║ ║ ║ ║ Hotter ║ ╠════════╬════════╬═════════════╬══════════════════╬══════════════════════╬══════════════════════════╣ ║ Wetter ║ ? ║ ? ║ ? ║ ? ║ Tropical Rainforest ║ ╠════════╬════════╬═════════════╬══════════════════╬══════════════════════╬══════════════════════════╣ ║ ║ ? ║ ? ║ ? ║ Temperate Rainforest ║ Swamp ║ ╠════════╬════════╬═════════════╬══════════════════╬══════════════════════╬══════════════════════════╣ ║ ║ ? ║ ? ║ Temperate Forest ║ ??? ║ Tropical Seasonal Forest ║ ╠════════╬════════╬═════════════╬══════════════════╬══════════════════════╬══════════════════════════╣ ║ ║ ? ║ Taiga ║ Grassland ║ Woodland ║ Savanna ║ ╠════════╬════════╬═════════════╬══════════════════╬══════════════════════╬══════════════════════════╣ ║ Drier ║ Tundra ║ Cold Desert ║ Shrubland ║ ??? ║ Hot Desert ║ ╚════════╩════════╩═════════════╩══════════════════╩══════════════════════╩══════════════════════════╝ ``` As you can see I was easily able to fill in the hotter/drier side of the table, missing just a few biomes where I just have yet to come up with a good name due to unusual delineation points. My bigger issue is that entire upper triangle. I guess earth just doesn't have many cold, wet biomes? I can't think of a physics oriented reason why - which leads me to think it is semantic (we don't live anywhere that cold, so we just lump all cold climates into "tundra/taiga"). Is there any way to come up with good words to describe cold/wet climates? Are they even possible? The language exists on a custom planet, so if the biomes could exist but just don't on earth all I need to do is 'create' them and come up with a good name for them (e.g. flowerscape if a biome caused mostly flowers as flora).	Assuming your conlang is on an Earth-like planet, then yes, the problem is physics, not just linguistics. --------------------------------------------------------------------------------------------------------- <https://www.accuweather.com/en/features/trend/too-cold-to-snow/6953983> To quote the important part: > > When temperature decreases, the maximum capacity of water vapor that can be in the air decreases. Therefore, the colder it gets the less water vapor there will be in the air. > > > To paraphrase: *how cold a specific climate is determines how dry it is.* So basically, the colder an environment, the drier it will be. So any "wet" *and* "cold" environment will still be, due to the laws of physics, warmer than tundra, taiga, or cold deserts. As a result, most cultures have never needed to coin a word for an environment that is both colder and wetter than taiga and cold deserts. The chances of someone encountering such a place approach zero. And this is reflected in your graph, in the very neat and tidy stair step up from tundra to tropical something. Maybe that stair step is one of your groups of 5, in addition to describing relative temperature and humidity/precipitation? Maybe your culture thinks of the world as five distinct grades from the equator to the poles, defined by those five biomes?
117,677	<p>In one world I am building, the four seasons are composed of the four elements.</p> <p>It would probably go in this direction: Water>Earth>Fire>Wind>Water</p> <pre><code>The season of Fire is dry and hot. Between the season of Fire and Wind is a time of lightning and prophecy. The season of Wind is windy and chaotic. Between the season of Wind and Water is a time of storms and seafaring. The season of Water is cold and wet. </code></pre> <p>I am having difficulty, however, coming up with the season of Earth, and the "Solstices" adjacent to Fire and Water. </p> <p>What would be the trademarks for the Season of Earth with this kind of example? </p>	[ { "answer_id": 117679, "author": "Attackfarm", "author_id": 41, "author_profile": "https://worldbuilding.stackexchange.com/users/41", "pm_score": 2, "selected": false, "text": "<pre><code>Between the season of Water and Earth is a time of floods and hope.\nThe season of Earth is temperat...	2018/07/09	[ "https://worldbuilding.stackexchange.com/questions/117677", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/52857/" ]	In one world I am building, the four seasons are composed of the four elements. It would probably go in this direction: Water>Earth>Fire>Wind>Water ``` The season of Fire is dry and hot. Between the season of Fire and Wind is a time of lightning and prophecy. The season of Wind is windy and chaotic. Between the season of Wind and Water is a time of storms and seafaring. The season of Water is cold and wet. ``` I am having difficulty, however, coming up with the season of Earth, and the "Solstices" adjacent to Fire and Water. What would be the trademarks for the Season of Earth with this kind of example?	The season of Earth is fertility. In the season of Earth, she does her thing keeping us alive. Fields! Flowers! Baby animals! Green! Plus you have to have some season to grow food or people will starve. You can't eat lighting and chaos. As I understand it Earth would be roughly analogous to spring, fire to summer, wind to autumn and water to winter. California has seasons like that. So summer solstice would be the earth to fire transition and winter the wind to water transition. On earth to fire, the fields burn. Wind to water means the big storms.
121,834	<blockquote> <p>Look at you all sitting here. Quite some of you have probably never ventured beyond the outskirts of this city, mayhaps not even past the wall? You've spent your whole lives in this place, but what do you actually know about <em>its</em> lifetime?</p> </blockquote> <p>Introductory course to the History & Sociology of the tri-region area, Ringstadt Militaric University.</p> <hr> <p>This question is <strong>about</strong> checking over the topography I created in the below map. There are a number of features in and about it that I, with my limited knowledge and understanding of geology & hydrology, find plausible - but have no way of reliably telling if that is fact.</p> <p>Below you will find a <em>Background</em> section explaining some of my goals for this area in terms of worldbuilding that have been significant factors in my design-process. In the <em>Topography</em> section you will find aforementioned map as well as some paragraphs detailing it in prose, documenting my thoughts and choices - and the why's in my understanding. At the end you will find, once again, the question accompanied by a focused list of the things <em>I know</em> I need double-checking & feedback on - this list is not meant to be exclusive, but to my understanding these are the core foci.</p> <hr> <p><em>Background</em>:</p> <p>On the below image I attempted to map the area where my con-city <em>Ringstadt</em> will be founded and built. The development of the region will start off with a few communities living off the land and supporting an abbey that is going to be somewhere in the H4 to K7 area (the square denoted by these corners).</p> <p>Eventually, in the earth-equivalent of the ~1600-1700s, metals and coal become a thing of importance and prospecting happens, which leads to a mining town growing around first shafts digging into the mountain in the D2 to F3 area, producing mainly coal. A supporting logging encampment springs up somewhere upstream, the mining expands along the ridge towards the abbey, digging further into the mountains.</p> <p>The underground mining reveals iron deposits that, when being tapped, turn out to be much more extensive than judged by the original prospecting. The limited iron smelting & processing industry experiences a rapid growth together with the surrounding boroughs of worker & family homes. The direction of trade inverts from exporting raw materials to importing them and starting to export goods & commodities.</p> <hr> <p><em>Topography</em>:</p> <p>The map section is located in the northern hemisphere <a href="https://worldbuilding.stackexchange.com/questions/38921/can-a-super-governmental-military-body-like-this-work">somewhere above 55° of latitude</a>. The base-height of the map is, as of now, undecided - it can be whatever is necessary for the topography to work.</p> <p>The area is framed by a lake and a mountainside. The lake kisses the mountainside until it eventually eases back to give way for a wide expanse, being separated from higher grounds by a steep 'cliff'. I imagine there having been an ice-age glacier <em>shearing off</em> the mountainside, leaving that steep 'cliff'. The glacier would have been reduced into the residing lake.</p> <p>Along the lakeside, the expanse features reed marshes. The wide and even expanse getting flat enough in the lower parts near the lake to gather standing bodies of water, etc.</p> <p>A smaller lake forms up in the mountains to the north-east, discharging into a river that eventually feeds into the lower-eastern lake. To the south of the high-lake hills frame a valley mostly being a peat-bog. I imagine are having started off as a rather flat extension of the above lake, eventually filling up with biomass and turning into marshlands.</p> <p><a href="https://i.stack.imgur.com/KKIRW.png" rel="noreferrer"><img src="https://i.stack.imgur.com/KKIRW.png" alt="Ringstadt topological map"></a></p> <pre><code>Legend: brown -> topological lines, 10 meters each light blue -line- -> streams, rivers light blue -shaded- -> bodies of water turquoise -> peat bog olive -> reed marshes Each grid-cell is 400m by 400m. </code></pre> <hr> <p><strong>Q</strong>: How sensible is my topography?</p> <p>A good answer should <em>at least</em> address the following topics:</p> <ul> <li>Are there any (grossly) unnatural features? <ul> <li>e.g. the steep 'cliff' that frames most of the mountainside until about H4</li> <li>What do I have to change for them to be natural?</li> </ul></li> <li>Are the streams & rivers in sensible positions? <ul> <li>Which (if any) are misplaced & where do I need to move them?</li> <li>Which areas are missing streams?</li> </ul></li> <li>Can the peat bog and reed marshes exist at the positions I put them? <ul> <li>Should the area from D1 to F1 be a bog or similar as well?</li> <li>Can I have clay and/or other shallow resources in this area? And where?</li> </ul></li> </ul>	[ { "answer_id": 121838, "author": "Clay Deitas", "author_id": 54317, "author_profile": "https://worldbuilding.stackexchange.com/users/54317", "pm_score": 3, "selected": false, "text": "<p>I am not a geologist, but as far as I can tell this layout is completely plausible. Good attention to...	2018/08/16	[ "https://worldbuilding.stackexchange.com/questions/121834", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/2746/" ]	> > Look at you all sitting here. Quite some of you have probably never ventured beyond the outskirts of this city, mayhaps not even past the wall? You've spent your whole lives in this place, but what do you actually know about its lifetime? > > > Introductory course to the History & Sociology of the tri-region area, Ringstadt Militaric University. --- This question is about checking over the topography I created in the below map. There are a number of features in and about it that I, with my limited knowledge and understanding of geology & hydrology, find plausible - but have no way of reliably telling if that is fact. Below you will find a Background section explaining some of my goals for this area in terms of worldbuilding that have been significant factors in my design-process. In the Topography section you will find aforementioned map as well as some paragraphs detailing it in prose, documenting my thoughts and choices - and the why's in my understanding. At the end you will find, once again, the question accompanied by a focused list of the things I know I need double-checking & feedback on - this list is not meant to be exclusive, but to my understanding these are the core foci. --- Background: On the below image I attempted to map the area where my con-city Ringstadt will be founded and built. The development of the region will start off with a few communities living off the land and supporting an abbey that is going to be somewhere in the H4 to K7 area (the square denoted by these corners). Eventually, in the earth-equivalent of the ~1600-1700s, metals and coal become a thing of importance and prospecting happens, which leads to a mining town growing around first shafts digging into the mountain in the D2 to F3 area, producing mainly coal. A supporting logging encampment springs up somewhere upstream, the mining expands along the ridge towards the abbey, digging further into the mountains. The underground mining reveals iron deposits that, when being tapped, turn out to be much more extensive than judged by the original prospecting. The limited iron smelting & processing industry experiences a rapid growth together with the surrounding boroughs of worker & family homes. The direction of trade inverts from exporting raw materials to importing them and starting to export goods & commodities. --- Topography: The map section is located in the northern hemisphere [somewhere above 55° of latitude](https://worldbuilding.stackexchange.com/questions/38921/can-a-super-governmental-military-body-like-this-work). The base-height of the map is, as of now, undecided - it can be whatever is necessary for the topography to work. The area is framed by a lake and a mountainside. The lake kisses the mountainside until it eventually eases back to give way for a wide expanse, being separated from higher grounds by a steep 'cliff'. I imagine there having been an ice-age glacier shearing off the mountainside, leaving that steep 'cliff'. The glacier would have been reduced into the residing lake. Along the lakeside, the expanse features reed marshes. The wide and even expanse getting flat enough in the lower parts near the lake to gather standing bodies of water, etc. A smaller lake forms up in the mountains to the north-east, discharging into a river that eventually feeds into the lower-eastern lake. To the south of the high-lake hills frame a valley mostly being a peat-bog. I imagine are having started off as a rather flat extension of the above lake, eventually filling up with biomass and turning into marshlands. [![Ringstadt topological map](https://i.stack.imgur.com/KKIRW.png)](https://i.stack.imgur.com/KKIRW.png) ``` Legend: brown -> topological lines, 10 meters each light blue -line- -> streams, rivers light blue -shaded- -> bodies of water turquoise -> peat bog olive -> reed marshes Each grid-cell is 400m by 400m. ``` --- Q: How sensible is my topography? A good answer should at least address the following topics: * Are there any (grossly) unnatural features? + e.g. the steep 'cliff' that frames most of the mountainside until about H4 + What do I have to change for them to be natural? * Are the streams & rivers in sensible positions? + Which (if any) are misplaced & where do I need to move them? + Which areas are missing streams? * Can the peat bog and reed marshes exist at the positions I put them? + Should the area from D1 to F1 be a bog or similar as well? + Can I have clay and/or other shallow resources in this area? And where?	Grossly unnatural features: Mainly, you should remember that topography is a facet of the geological history of the area. So, your hills look fine, could just be product of orogeny and erosion, your cliff spanning the entire map is fine, most likely explained by a strike-slip fault (although it could be a bit straighter if that's the case), and the plain could also be explained by glaciation or sea-level retreat (although randomize it a little, the slope is too similar). Looks mostly good! Streams and Rivers For that one stream in the D3-G2, you seem to understand that streams tend to have those U-shaped bends in the contour line. However, the other streams don't seem to fit this pattern. Also, if you intended the river at J2 to cut through the mountains, that would have it flowing uphill at first, which doesn't seem to fit. Other than that, this looks ok. Bogs and Marshes Marshes and bogs tend to occur in low places, near water. I don't know your water table, but those regions are defined as usually saturated, so below the water table. Given that you put your bogs and marshes near shore, that should totally work. Clay and city Clay is a type of particulate matter: like sand. Given that your large river cuts through a cliff, that area should have some clay. Also possible: near your peat bog or under the surface of the lakes. I would place your city in either the region D3-E3-E4 or the region G6-H6, with D3-E3-E4 preferred because of flat land for farming, natural defence (back to a cliff), and a water source (river). I am by no means an expert on this, please correct any mistakes I have made.
122,862	<blockquote> <p>You sure lad? For some of you folks normal beer is already an acquired taste, but this... this beer <em>definitely</em> is. You understand that this stuff is brewed with water from the devil's choke? You know, that vile spring right behind the abbey?</p> </blockquote> <p>Last words Hans M'wambe, Private 1st Class, recalls before getting booted out of the Lifted Spirits Pub for distributing the contents of his stomach all over the Bartender.</p> <hr> <p>This question is a spin-off to <a href="https://worldbuilding.stackexchange.com/questions/121834/ringstadt-how-sensible-is-my-topography">this question about the topography in the below map</a>. Please refer to it for general questions or observations about the map & area.</p> <p>This spin-off is <strong>about</strong> the peat bog in the I3 to J5 area (the square denoted by these corners), and the spring at I5; regarding the process 'enriching' the spring-water with sulphur up to a degree where it needs to be filtered to be consumable.</p> <hr> <p><em>Process</em>:</p> <p>From reading <a href="https://eos.org/research-spotlights/drought-changes-how-peat-bogs-cycle-mercury-and-sulfur" rel="nofollow noreferrer">this article on sulphur in peat bogs</a> and other lay-man's research, I understand that peat bogs are areas where sulphur is filtered from the surroundings and deposited.</p> <p>I imagine that precipitation collects from the hills around and drains into the bog, from which it sips into lower strata where it meets rock and gets eventually pushed out of the cliff-side in I5.</p> <p>My hopes are, that the water, when seeping through the bog, can be 'enriched' with sulphur by some sort of process, but I do not understand enough about biology to know of any such process - or if this is even impossible.</p> <p><a href="https://i.stack.imgur.com/nYx1M.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/nYx1M.png" alt="Ringstadt topological map"></a></p> <pre><code>Legend: brown -> topological lines, 10 meters each blue -line- -> streams, rivers light-blue -solid- -> bodies of water turquoise -> peat bog olive -> reed marshes Each grid-cell is 400m by 400m. </code></pre> <hr> <p><strong>Q</strong>: Can my peat-bog-spring-idea result in water enriched with sulphur to a degree that it needs to be filtered?</p> <p>A good answer should <em>at least</em> address the following topics:</p> <ul> <li>What circumstances are necessary for this to happen?</li> <li>If this cannot work, what alternative process could provide the desired result?</li> </ul> <p>In <em>addition</em> it would be amazing if an answer could delve into the science:</p> <ul> <li>How does the process of 'enriching' the water work?</li> <li>What compounds are involved?</li> </ul>	[ { "answer_id": 122871, "author": "jedmeyer", "author_id": 52749, "author_profile": "https://worldbuilding.stackexchange.com/users/52749", "pm_score": 3, "selected": false, "text": "<p>A lot of people tend to misunderstand how common sulfur compounds actually is in water. They're actually...	2018/08/24	[ "https://worldbuilding.stackexchange.com/questions/122862", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/2746/" ]	> > You sure lad? For some of you folks normal beer is already an acquired taste, but this... this beer definitely is. You understand that this stuff is brewed with water from the devil's choke? You know, that vile spring right behind the abbey? > > > Last words Hans M'wambe, Private 1st Class, recalls before getting booted out of the Lifted Spirits Pub for distributing the contents of his stomach all over the Bartender. --- This question is a spin-off to [this question about the topography in the below map](https://worldbuilding.stackexchange.com/questions/121834/ringstadt-how-sensible-is-my-topography). Please refer to it for general questions or observations about the map & area. This spin-off is about the peat bog in the I3 to J5 area (the square denoted by these corners), and the spring at I5; regarding the process 'enriching' the spring-water with sulphur up to a degree where it needs to be filtered to be consumable. --- Process: From reading [this article on sulphur in peat bogs](https://eos.org/research-spotlights/drought-changes-how-peat-bogs-cycle-mercury-and-sulfur) and other lay-man's research, I understand that peat bogs are areas where sulphur is filtered from the surroundings and deposited. I imagine that precipitation collects from the hills around and drains into the bog, from which it sips into lower strata where it meets rock and gets eventually pushed out of the cliff-side in I5. My hopes are, that the water, when seeping through the bog, can be 'enriched' with sulphur by some sort of process, but I do not understand enough about biology to know of any such process - or if this is even impossible. [![Ringstadt topological map](https://i.stack.imgur.com/nYx1M.png)](https://i.stack.imgur.com/nYx1M.png) ``` Legend: brown -> topological lines, 10 meters each blue -line- -> streams, rivers light-blue -solid- -> bodies of water turquoise -> peat bog olive -> reed marshes Each grid-cell is 400m by 400m. ``` --- Q: Can my peat-bog-spring-idea result in water enriched with sulphur to a degree that it needs to be filtered? A good answer should at least address the following topics: * What circumstances are necessary for this to happen? * If this cannot work, what alternative process could provide the desired result? In addition it would be amazing if an answer could delve into the science: * How does the process of 'enriching' the water work? * What compounds are involved?	A lot of people tend to misunderstand how common sulfur compounds actually is in water. They're actually used as preservative in [wines](https://www.bonappetit.com/drinks/wine/article/sulfite-free-wine), though sommeliers say it affects the taste. There are a couple common sources of sulfur. One is from minerals, and there are a LOT of possible inorganic compounds including iron sulfide, calcium sulfate, and many [more](https://en.wikipedia.org/wiki/Sulfur). These are often deposited into bodies of water through erosion, dissolving and depositing in the water over thousands of years. However, most people notice sulfur in only one form: Hydrogen Sulfide (H2S), the pungent gas that we associate with rotten eggs. H2S is usually created by what we call Sulfur Reducing Bacteria. Basically, the bacteria exploit the chemical energy gradient in sulfate compounds and perform a [reduction reaction](https://en.wikipedia.org/wiki/Redox) to perform biochemical duties. They need the aforementioned sulfur compounds dissolved in the water to work however. Honestly, H2S isn't actually that poisonous, but it's smell is SO bad, that most humans wouldn't be able to stomach it anywhere of a harmful level. So at this point, you would need to filter the water, which can be done using an Activated Carbon filter.
122,863	<blockquote> <p>When the old mining town was founded, nobody did think of this ever growing into much more than a coal-mining town. The deposits of iron-ore, aside from the already developed peat bog to the north, driving the tools & weapons industries this city is now thriving from, have originally been estimated to be much smaller in size - and deemed not worthy of exploitation..</p> </blockquote> <p>Introductory course to the History & Sociology of the tri-region area, Ringstadt Militaric University.</p> <hr> <p>This question is a spin-off to <a href="https://worldbuilding.stackexchange.com/questions/121834/ringstadt-how-sensible-is-my-topography">this question about the topography in the below map</a>. Please refer to it for general questions or observations about the map & area.</p> <p>This spin-off is <strong>about</strong> understanding & determining the make up of the mountains to the north of the map. For future story-purposes the mountains/rock will have to fulfill certain properties, this is about finding out if my goals for them are possible or if I need to rethink this part.</p> <hr> <p><em>Desired Properties</em>:</p> <p>For the purpose of developing an eventual city in this area, I was planning to have initial mines along the ridge from D2 to F3 (later expanding towards H4) producing coal from strata mostly parallel to adjacent ground-level.</p> <p>Eventually I wanted expansion and further prospecting to reveal massive depots of iron and preferably some other ores/minerals as well (maybe copper?) in the deeper strata below the coal. Coal being carbonized organics, I imagined that the coal layer(s) could have been folded on top of the ore deposits by glacial movement or similar.</p> <p>In order to get access to lower strata and deposits I imagined some eventual open-pit mining in the F2 area, the resulting waste-rock being used as building materials (if I can have sandstone, granite or other building rock there) and to raise embankments in the C2 to C5 area, creating a protected harbour.</p> <p>For story & fanciness purposes I would love to have big tunnels leading into the mountains, and massive underground caverns that are left-overs from the mining process (so I can fill them with secret military installations, or simply storage, or what not).</p> <p><a href="https://i.stack.imgur.com/nYx1M.png" rel="noreferrer"><img src="https://i.stack.imgur.com/nYx1M.png" alt="Ringstadt topological map"></a></p> <pre><code>Legend: brown -> topological lines, 10 meters each blue -line- -> streams, rivers light-blue -solid- -> bodies of water turquoise -> peat bog olive -> reed marshes Each grid-cell is 400m by 400m. </code></pre> <hr> <p><strong>Q</strong>: Can the above described desired properties be <em>realistically</em> met by the rock and soil in this area Can my mountains be what I need them to?</p> <p>A good answer should <em>at least</em> address the following topics:</p> <ul> <li>Can I have the resources I in the described area? <ul> <li>Can I have the upper layer of coal-seams?</li> <li>Can I have the massive iron deposits?</li> <li>Can I have the supplemental Copper (or other useful ore) deposit(s)?</li> </ul></li> <li>If this cannot work, why - what stands in the way of it?</li> </ul> <p>In <em>addition</em> it would be amazing if answers that explain <em>why this cannot happen</em>, to include a section proposing alternative situations of resources that come close/to a similar result as what I am describing in the above prose.</p> <ul> <li>Please ignore the resources available in the peat-bog; I know there will be bog-iron and it will play a significant part in the <em>earlier</em> development of the region. Same goes for the clay and gravel available through the reed-marshes and river-deposits.</li> </ul>	[ { "answer_id": 122866, "author": "Blade Wraith", "author_id": 50282, "author_profile": "https://worldbuilding.stackexchange.com/users/50282", "pm_score": 0, "selected": false, "text": "<p>Please understand i am not a geologist, so if i'm wrong on naything i say please correct me, i'm jus...	2018/08/24	[ "https://worldbuilding.stackexchange.com/questions/122863", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/2746/" ]	> > When the old mining town was founded, nobody did think of this ever growing into much more than a coal-mining town. The deposits of iron-ore, aside from the already developed peat bog to the north, driving the tools & weapons industries this city is now thriving from, have originally been estimated to be much smaller in size - and deemed not worthy of exploitation.. > > > Introductory course to the History & Sociology of the tri-region area, Ringstadt Militaric University. --- This question is a spin-off to [this question about the topography in the below map](https://worldbuilding.stackexchange.com/questions/121834/ringstadt-how-sensible-is-my-topography). Please refer to it for general questions or observations about the map & area. This spin-off is about understanding & determining the make up of the mountains to the north of the map. For future story-purposes the mountains/rock will have to fulfill certain properties, this is about finding out if my goals for them are possible or if I need to rethink this part. --- Desired Properties: For the purpose of developing an eventual city in this area, I was planning to have initial mines along the ridge from D2 to F3 (later expanding towards H4) producing coal from strata mostly parallel to adjacent ground-level. Eventually I wanted expansion and further prospecting to reveal massive depots of iron and preferably some other ores/minerals as well (maybe copper?) in the deeper strata below the coal. Coal being carbonized organics, I imagined that the coal layer(s) could have been folded on top of the ore deposits by glacial movement or similar. In order to get access to lower strata and deposits I imagined some eventual open-pit mining in the F2 area, the resulting waste-rock being used as building materials (if I can have sandstone, granite or other building rock there) and to raise embankments in the C2 to C5 area, creating a protected harbour. For story & fanciness purposes I would love to have big tunnels leading into the mountains, and massive underground caverns that are left-overs from the mining process (so I can fill them with secret military installations, or simply storage, or what not). [![Ringstadt topological map](https://i.stack.imgur.com/nYx1M.png)](https://i.stack.imgur.com/nYx1M.png) ``` Legend: brown -> topological lines, 10 meters each blue -line- -> streams, rivers light-blue -solid- -> bodies of water turquoise -> peat bog olive -> reed marshes Each grid-cell is 400m by 400m. ``` --- Q: Can the above described desired properties be realistically met by the rock and soil in this area Can my mountains be what I need them to? A good answer should at least address the following topics: * Can I have the resources I in the described area? + Can I have the upper layer of coal-seams? + Can I have the massive iron deposits? + Can I have the supplemental Copper (or other useful ore) deposit(s)? * If this cannot work, why - what stands in the way of it? In addition it would be amazing if answers that explain why this cannot happen, to include a section proposing alternative situations of resources that come close/to a similar result as what I am describing in the above prose. * Please ignore the resources available in the peat-bog; I know there will be bog-iron and it will play a significant part in the earlier development of the region. Same goes for the clay and gravel available through the reed-marshes and river-deposits.	So many minerals so close to a city is unlikely =============================================== ### Your mining area is small Limiting the mines to the area from D2->F3 is like a coal seam that is only 1-2 km long. That is short. Here is a [GIS mapping](https://eppcgis.ky.gov/minemapping/) of coal mining areas in Kentucky. The seams are hundreds of miles long. [Scranton](https://en.wikipedia.org/wiki/Scranton,_Pennsylvania) was/is a big coal mining town in Eastern Pennsylvania. Scranton grew to over 100,000 at the peak of the coal mining boom. Combined with nearby Wilkes-Barre and other cities in the area, it formed a conurbanation of some 300,000 in the 1920s. These cities serviced coal towns from Forest City, PA to Bloomsburg, PA, some 110 km downriver. The two-county area ([Lackawanna](https://en.wikipedia.org/wiki/Lackawanna_County,_Pennsylvania#Demographics) and [Luzerne](https://en.wikipedia.org/wiki/Luzerne_County,_Pennsylvania#Demographics)) had some 700,000 people, so it was one of the most densely populated parts of the US at that time. Lots of people in a region = large city to support those people. If you want a large mining town, it should probably be pulling from a large mining region. Some mines will be close by, but many more with be within a day or two's transport by horse or foot; or later, a few hours by train. A 'city' with only small nearby mines would be just a small encampment of a few hundred. ### Mines on top of each other are unlikely I can't find any good examples of mines being just on top of each other like that. But I was able to find a variety of examples of such mines being in very close proximity. The rich bituminous coals are generally of an age [100-300 million years ago](https://en.wikipedia.org/wiki/Bituminous_coal#Bituminous_coal_by_geologic_period). Almost all high quality Iron ores are derive in one way or another from [banded iron formations](https://en.wikipedia.org/wiki/Banded_iron_formation). These formations are much, much older, in the 2 billion year range. They derive from the Great Oxygenation event, when the first atmospheric oxygen reacted with free iron to lay down great beds of iron oxide. The gap in time between the two levels is what makes the idea of coal on top of iron so unlikely. If you had several hundred meters of coal-bearing strata, even if you just dumped that on top of a banded iron formation, that is still very deep for a early-modern mine. [Mines in Europe](https://en.wikipedia.org/wiki/Mining_in_the_Upper_Harz) were hitting 300 meters by 1700 and 600 meters by 1830; still these were exceptional. And this considering a ~300 mya formation directly on top of a ~2000 mya formation, with no intervening material, which I consider unlikely. A second reason that this would not work is that you have large lakes nearby, so mine shaft drainage is going to be tough. Your mining hills only go up about 100 meters above lake level. Much deeper than lake level, and you will likely get very serious water intrusion. Mining below lake level at all will likely have to wait for the steam engine to pump water. ### A large mining area means many resources can be found together. Jharkhand, in India, is a place with lots of mining resources in close proximity. It is the [leading](https://en.wikipedia.org/wiki/Jharkhand#Economy) iron and copper mining state of India, and third in coal. Meanwhile, much of India's coal reserves are just across the border in West Bengal and Odisha states. You can see a big iron ore mining region near Gua, Jharkand, India on the [map here](https://www.google.com/maps/place/Gua+Iron+Ore+Mines,+Jharkhand+833213,+India/@22.1434796,85.3288054,26748m/data=!3m1!1e3!4m5!3m4!1s0x3a1fc72a10e8390d:0xdaf66a46afb1a575!8m2!3d22.2185736!4d85.3562565) (look for the open pit mines in the satellite view). Meanwhile, here is some [significant coal mining](https://www.google.com/maps/place/Global+Coal+And+Mining+Pvt.+Ltd.+Talcher/@20.9500388,85.0922498,26099m/data=!3m1!1e3!4m8!1m2!2m1!1stalcher+coal+mine!3m4!1s0x3a18b16196542a87:0x65ae90c0079f0992!8m2!3d20.9280814!4d85.1646353) in nearby Talcher, Odisha, India. Still these two mines are 140 km apart. But there are [copper mines near Jamshedupur](https://www.google.com/maps/search/copper+mine+jharkand/@22.5747552,86.3920152,23160m/data=!3m1!1e3) 110 km away from the coal mines, and also uranium, gold, bauxite and other things in the region. Conclusion ========== Your best bet is to have your mining town be the center of a larger mining region. Within the larger mining region, there are many regional centers of coal, iron, copper and more. Ringstadt is the central business city of the region, and the center for trans-shipment; after all it is a port town on the lake and what better way to move ore than by barge. Also, it can eventually be the industrial center for the iron and steel industry. A good example is Cleveland, OH. This lake town isn't actually close to coal (which is in Pennsylvania and West Virginia, mostly) or iron, which is available in Minnesota and Michigan's Upper Peninsula. But it is the place between the two on the lake. Rail brought coal from the Pittsburgh area, and barges brought ore from Lake Superior; these met in Cleveland which became a big metals center. Gary, Indiana has as similar history.
124,152	<p>I have a location in my story, the design of which needs a reality check.</p> <p><strong>City Description:</strong></p> <blockquote> <p>As my ship cut across the waves a blurred grey smudge appeared in the distance, as the hours passed it became more distinct and it's true scope came into view.</p> <p>As we neared the end of our voyage a great cliff of jagged granite rose hundreds of feet from the relentlessly pounding sea and spread as far as the eye could see in either direction. The tops of the tallest buildings shining brightly in the moonlight peered down from atop the cliff. The face of the cliff, littered with windows glowed like the eyes of fey forest creatures and large towers ascended at intervals striped like a barber pole apparently carved from the face of the cliff.</p> <p>Directly before us a giant maw opened in the cliff the top jagged like the mouth of some vicious predator. On either side of the cliff massive braziers burned brightly in the night.</p> </blockquote> <p>There is more to the poetic description but I think that is sufficient to set the feel for the place.</p> <p><strong>City Details:</strong></p> <ul> <li>The city is built into, and on top of, a granite cliff. The cliff rises 500' (152 Meters) from the sea below.</li> <li>The granite cliff extends perhaps a mile in either direction (this can be adjusted somewhat if it matters) and should extend at least 1500' (460 M) inland.</li> <li>In the face of the cliff is a large cavern that can accommodate large two masted sailing ships. Tugs are used to tow the ships to docks within the cave.</li> <li>Inside there are stairways and elevators (both for people and cargo) that lead up to the surface.</li> <li>Inside the rock formation I am looking for enough space for approximately 1000 residents, each should be afforded 12'x 12' (.305 x .305 M) of floor space, dwellings are not all the same size.</li> <li>Living spaces are reminiscent of Bag End from The Fellowship of the Ring, though scaled for a normal human to walk without doubling over (8' ceilings) The underground portion will also require space for cargo storage.</li> <li>Atop the rock face is a city, where important structures are built from the excavated granite and lesser structures from both stone and wood from the surrounding forest.</li> </ul> <p><strong>Points of consideration for the reality check.</strong></p> <ul> <li>Can this much granite exist in one place, are there real world examples?</li> <li>Does the described amount of excavation seem possible or would it cause structural problems? (Faults can be set however structurally required)</li> <li>Are there examples of dwellings carved into granite in the real world for the purpose of habitation?</li> <li>Are there concerns with this setup that I have not considered?</li> </ul>	[ { "answer_id": 124159, "author": "Jean-Abdel", "author_id": 53937, "author_profile": "https://worldbuilding.stackexchange.com/users/53937", "pm_score": 2, "selected": false, "text": "<p>Actually granite rarely form caves, and never that big. Water erode the rock by infiltrating through t...	2018/09/04	[ "https://worldbuilding.stackexchange.com/questions/124152", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/189/" ]	I have a location in my story, the design of which needs a reality check. City Description: > > As my ship cut across the waves a blurred grey smudge appeared in the distance, as the hours passed it became more distinct and it's true scope came into view. > > > As we neared the end of our voyage a great cliff of jagged granite rose hundreds of feet from the relentlessly pounding sea and spread as far as the eye could see in either direction. The tops of the tallest buildings shining brightly in the moonlight peered down from atop the cliff. The face of the cliff, littered with windows glowed like the eyes of fey forest creatures and large towers ascended at intervals striped like a barber pole apparently carved from the face of the cliff. > > > Directly before us a giant maw opened in the cliff the top jagged like the mouth of some vicious predator. On either side of the cliff massive braziers burned brightly in the night. > > > There is more to the poetic description but I think that is sufficient to set the feel for the place. City Details: * The city is built into, and on top of, a granite cliff. The cliff rises 500' (152 Meters) from the sea below. * The granite cliff extends perhaps a mile in either direction (this can be adjusted somewhat if it matters) and should extend at least 1500' (460 M) inland. * In the face of the cliff is a large cavern that can accommodate large two masted sailing ships. Tugs are used to tow the ships to docks within the cave. * Inside there are stairways and elevators (both for people and cargo) that lead up to the surface. * Inside the rock formation I am looking for enough space for approximately 1000 residents, each should be afforded 12'x 12' (.305 x .305 M) of floor space, dwellings are not all the same size. * Living spaces are reminiscent of Bag End from The Fellowship of the Ring, though scaled for a normal human to walk without doubling over (8' ceilings) The underground portion will also require space for cargo storage. * Atop the rock face is a city, where important structures are built from the excavated granite and lesser structures from both stone and wood from the surrounding forest. Points of consideration for the reality check. * Can this much granite exist in one place, are there real world examples? * Does the described amount of excavation seem possible or would it cause structural problems? (Faults can be set however structurally required) * Are there examples of dwellings carved into granite in the real world for the purpose of habitation? * Are there concerns with this setup that I have not considered?	This is like an [Indian rock-temple](https://en.wikipedia.org/wiki/Ellora_Caves) ================================================================================ [![enter image description here](https://i.stack.imgur.com/fZyHo.jpg)](https://i.stack.imgur.com/fZyHo.jpg) There are many examples of these rock-temples in southern India. Above is a picture of Cave 10 at Ellora. Below is Cave 16 at the same site, called the Kailasa Temple. The temples are called 'caves,' some of them are dug into rock as if they were caves, some, like 16 are basically small hills excavated into the shape of a building. [![enter image description here](https://i.stack.imgur.com/fDuSs.jpg)](https://i.stack.imgur.com/fDuSs.jpg) Cave 16 is 82 by 40 meters, and 30 meters high inside. An estimate of the total amount of rock removed in 100,000 cubic meters, just for this one of 34 caves at the Ellora site. Ellora is just one of many from Maharashtra in India, including [Ajanta](https://en.wikipedia.org/wiki/Ajanta_Caves) and [Pitalkhora](https://en.wikipedia.org/wiki/Pitalkhora). The Pitalkhora site was started around the 3rd century BC; building at each site went on for hundreds of years. The total amount of excavation at the bigger sites like Ellora and Ajanta is probably more than you would need to make your city. Except that was basalt ====================== So all those structures were cut into flood basalt. However, basalt is pretty hard and tough as it is. Here are some material comparisons between granite and basalt. Source of [granite](https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0180880) and [basalt](http://oro.open.ac.uk/5495/1/JVGRbalme01_corrected_for_publicpdf.pdf) fracture toughness, [all other data](http://acwc.sdp.sirsi.net/client/en_US/default/index.assetbox.assetactionicon.view/1045105?rm=CONCRETE%20LABOR0%7C%7C%7C1%7C%7C%7C0%7C%7C%7Ctrue). Everything converted to metric ``` Basalt Granite Density (kg/m^3) 2830 2690 Fracture Toughness (MPa m^0.5) 1.5-1.7 1.9-2.2 Compressive Strength (MPa) 148 143 Tensile Strength (MPa) 13.1 11.7 ``` Basalt appears to be slightly denser, and proprotionately stronger, while granite is tougher so it would be a bit harder to mine through. Ultimately, the materials are pretty similar, so if Iron Age Indians could carve these temples in a century or two, they could also carve your city. Conclusion ========== Monumental cities carved in granite are realistic!
125,208	<p>So, I'm working out some of the types of wands people can purchase in my flintlock fantasy setting, and I'm having an issue with one of them. Before I get to that, let me explain how Magic in my setting works. Arcane Magic utilizes an energy called Aethyr. It can do a wide variety of things, like shooting fireballs, levitating, and so on. </p> <p>There's a magical industrial revolution of sorts taking place currently. Making magical devices is getting easier, so they are becoming more commonplace as a result. Among these are Spell Wands, a small wand that performs one or more simple Spells, usually no more than three, and almost always all a variation on the same Spell. An example: A Fire Wand can shoot a flaming arrow, spray flames like a flamethrower for a few seconds, or shoot a bead of crimson light that detonates on impact with the same force as a hand grenade. The Fire Wand can hold ten "charges." This isn't an exact amount of Aethyr, mind you; it is the amount of power needed to perform the least powerful Spell the Fire Wand can cast. So, the flaming arrow would require one charge, the flamethrower two charges, and the firecracker needs three in this scenario. Once the Fire Wand is out of charges, it doesn't work until it is replenished with Aethyr.</p> <p>This brings me to my Light Wand issue. The Light Wand has 4 Spells it can perform.</p> <p>Spell:</p> <ol> <li>makes the tip of the wand glow for up to 10 minutes.</li> <li>will leave a glowing bead of light the size of a grape floating wherever the tip of the wand was when the Spell was cast. (So, if you have it pointed at a spot in the air and cast the Spell, the bead of light will stay in that spot even after you move the wand away from it.) The effect lasts 10 minutes.</li> <li>shoots a grape sized ball of light from the tip of the wand that will move in a straight line until it comes into contact with something, then stop and remain in that spot (even if the object that stopped it moves.) The effect lasts 10 minutes.</li> <li>fires a beam from the tip of the wand. An object hit by the beam will have a glowing aura form around it for 10 minutes.</li> </ol> <p>Now, my thinking is that each of these Spells uses a single charge. Where a Light Wand differs from a Fire Wand is that the intensity of the light generated by these Spells requires more charges. The Spells all have five settings, but I'm not sure what four of them should be and how many charges those four should require. To give you an idea of what I'm thinking, I'll put it like this.</p> <p>Setting: 1. the light of a single candle 2. a 25 watt light bulb 3. a 50 watt light bulb 4. a 75 watt light bulb 5. a 100 watt light bulb</p> <p>I've been trying to figure out how to measure the differences in intensity for these settings, but I need some help. I don't know of the intensities of the bulbs I listed are really the best ones to use. I know that the first setting is what I want as the baseline but what's a logical way of determining the brightness of the other settings. I've tried searching for how many candles it takes to equal the brightness of the types of bulbs I listed, but every source I find gives me a bunch of stuff like "well, are you measuring candelas, lumens, or lux?" </p> <p><em>It's a magical bead of light the size of a grape that's floating in the air!!! How the heck should I know!?!</em></p> <p>The thing is, assuming that a 25 watt bulb equals 25 candles would mean that the Setting 2 would require 25 charges, not 2, would it not? This is the primary issue I'm having. I need to figure out a simple way of setting up this Light Wand so that I can keep track of how much energy it has after my protagonist uses it in certain ways and also so the readers can grasp how it works without having to do a bunch of math. That's why I'm turning to all of you for help. Based on what I've described, what are five settings the Light Wand should have and how many charges would each setting require. Don't worry about the maximum number of charges the Light Wand can hold, though. The quality of the device determines that, so even if two Light Wands work the same way, one will have a larger "battery" than the other and require a recharge less often as a result.</p> <p>So, what advice can you offer?</p> <p><strong>Update</strong></p> <p>Based on all the answers I've been getting, I've come up with the following:</p> <p>Spell 1 = 1 Charge</p> <p>Spell 2 = 2 Charges</p> <p>Spell 3 = 3 Charges</p> <p>Spell 4 = 1-4 Charges, depending on the size of the object illuminated by an aura. </p> <p>The Spell will affect on object up to its maximum potential area of effect regardless of charges used, but the brightness of the aura goes down as the size increases unless more charges are expended. The largest size category won't be as big as a castle, but I think something the size of an Argentinosaurus would be acceptable, as that's roughly the scale of the bigger Monsters you'd want to highlight if you're fighting one in the dark. So:</p> <p>1 Charge = Objects between the size of a grape and a watermelon</p> <p>2 Charges = Objects between the size of a watermelon and the size of a horse</p> <p>3 Charges = Objects between the size of a horse and the size of a T-Rex</p> <p>4 Charges = Objects between the size of a T-Rex and the size of an Argentinosaurus</p> <p>The base setting for each Spell is the intensity of a candle. We'll keep it simple and leave out any concerns with comparisons to modern light bulbs of any kind. The Light Wand has five settings that can be applied to each Spell. Each setting multiplies the brightness by a fixed number of candles. The multiplier cannot be tweaked beyond these five settings, as that would be too difficult for most people to manage without more than a basic understanding of using Arcane Devices. These are meant to be things an average person can use, after all. The settings (beyond the first 1 candle baseline) are:</p> <p>25 Candles = 315 Lumens = X25 Charges</p> <p>50 Candles = 630 Lumens = X50 Charges</p> <p>75 Candles = 945 Lumens = X75 Charges</p> <p>100 Candles = 1,260 Lumens = X100 Charges</p> <p>Thus:</p> <p>Spell 1 = 1 Charge, 25 Charges, 50 Charges, 75 Charges, and 100 Charges</p> <p>Spell 2 = 1 Charge, 50 Charges, 100 Charges, 150 Charges, and 200 Charges</p> <p>Spell 3 = 1 Charge, 75 Charges, 150 Charges, 225 Charges, and 300 Charges</p> <p>Spell 4 (on an Argentinosaurus) = 4 Charges, 100 Charges, 200 Charges, 300 Charges, and 400 Charges</p> <p>Now, that may seem like a lot of charges for the Light Wand to hold, but in terms of the actual amount of Aethyr used per charge, it isn't actually a huge amount of energy. It would really depend on the capacity of the Spellgem used to store the Aethyr. Further, since most Light Wands don't have all four Spells (they might only have the first two) and may only go up to Setting 2 at most, the cheaper models wouldn't need any high capacity Spellgem, making them much cheaper to produce. </p> <p>I think that the highest caliber Light Wand, with all four Spells and all five Settings, would be able to hold a maximum of 1,600 Charges when fully energized. That amount of Aethyr would probably still be less than an amplified hand grenade Spell requires, since it's only generating visible light, not any kind of kinetic force or heat. And even at 1,600 Charges, the Light Wand would only be able to use its strongest Spell at the highest setting 4 times before it was depleted of energy. Not terrible, unless you're being attacked by five homicidal Argentinosauruses on a very dark night. You'd only be able to highlight four of them. Granted, the bright glow of those four might reveal the fifth one... provided it wasn't a ninja Argentinosaurus dressed in light absorbing spandex. (I wound how big of a katana it would use.) </p> <p>The only real issue I can see with this is how the consumer knows how many charges the Light Wand has left. However, I can see some sort of indicator being featured on some part of the wand, likely above the handle, that the user can consult to see if the Spell he wants to use can be done at the setting he desires. A Mage, conversely, wouldn't need such an indicator, as they have an innate ability to gauge the amount of Aethyr a Spell is going to need. (Of course, a Mage wouldn't need to rely on a Light Wand in the first place, as a Mage can just cast the Spell himself at whatever potency he desires as long as he has sufficient Aethyr available.)</p> <p>So, I think this is how I'm going to set up the Light Wand. Let me know if there are any issues you see with it or a simpler way to keep track of the energy in the Light Wand.</p>	[ { "answer_id": 125212, "author": "RonJohn", "author_id": 8068, "author_profile": "https://worldbuilding.stackexchange.com/users/8068", "pm_score": 2, "selected": false, "text": "<p>According to <a href=\"https://en.wikipedia.org/wiki/Candela#Relationships_between_luminous_intensity,_lumi...	2018/09/16	[ "https://worldbuilding.stackexchange.com/questions/125208", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/-1/" ]	So, I'm working out some of the types of wands people can purchase in my flintlock fantasy setting, and I'm having an issue with one of them. Before I get to that, let me explain how Magic in my setting works. Arcane Magic utilizes an energy called Aethyr. It can do a wide variety of things, like shooting fireballs, levitating, and so on. There's a magical industrial revolution of sorts taking place currently. Making magical devices is getting easier, so they are becoming more commonplace as a result. Among these are Spell Wands, a small wand that performs one or more simple Spells, usually no more than three, and almost always all a variation on the same Spell. An example: A Fire Wand can shoot a flaming arrow, spray flames like a flamethrower for a few seconds, or shoot a bead of crimson light that detonates on impact with the same force as a hand grenade. The Fire Wand can hold ten "charges." This isn't an exact amount of Aethyr, mind you; it is the amount of power needed to perform the least powerful Spell the Fire Wand can cast. So, the flaming arrow would require one charge, the flamethrower two charges, and the firecracker needs three in this scenario. Once the Fire Wand is out of charges, it doesn't work until it is replenished with Aethyr. This brings me to my Light Wand issue. The Light Wand has 4 Spells it can perform. Spell: 1. makes the tip of the wand glow for up to 10 minutes. 2. will leave a glowing bead of light the size of a grape floating wherever the tip of the wand was when the Spell was cast. (So, if you have it pointed at a spot in the air and cast the Spell, the bead of light will stay in that spot even after you move the wand away from it.) The effect lasts 10 minutes. 3. shoots a grape sized ball of light from the tip of the wand that will move in a straight line until it comes into contact with something, then stop and remain in that spot (even if the object that stopped it moves.) The effect lasts 10 minutes. 4. fires a beam from the tip of the wand. An object hit by the beam will have a glowing aura form around it for 10 minutes. Now, my thinking is that each of these Spells uses a single charge. Where a Light Wand differs from a Fire Wand is that the intensity of the light generated by these Spells requires more charges. The Spells all have five settings, but I'm not sure what four of them should be and how many charges those four should require. To give you an idea of what I'm thinking, I'll put it like this. Setting: 1. the light of a single candle 2. a 25 watt light bulb 3. a 50 watt light bulb 4. a 75 watt light bulb 5. a 100 watt light bulb I've been trying to figure out how to measure the differences in intensity for these settings, but I need some help. I don't know of the intensities of the bulbs I listed are really the best ones to use. I know that the first setting is what I want as the baseline but what's a logical way of determining the brightness of the other settings. I've tried searching for how many candles it takes to equal the brightness of the types of bulbs I listed, but every source I find gives me a bunch of stuff like "well, are you measuring candelas, lumens, or lux?" It's a magical bead of light the size of a grape that's floating in the air!!! How the heck should I know!?! The thing is, assuming that a 25 watt bulb equals 25 candles would mean that the Setting 2 would require 25 charges, not 2, would it not? This is the primary issue I'm having. I need to figure out a simple way of setting up this Light Wand so that I can keep track of how much energy it has after my protagonist uses it in certain ways and also so the readers can grasp how it works without having to do a bunch of math. That's why I'm turning to all of you for help. Based on what I've described, what are five settings the Light Wand should have and how many charges would each setting require. Don't worry about the maximum number of charges the Light Wand can hold, though. The quality of the device determines that, so even if two Light Wands work the same way, one will have a larger "battery" than the other and require a recharge less often as a result. So, what advice can you offer? Update Based on all the answers I've been getting, I've come up with the following: Spell 1 = 1 Charge Spell 2 = 2 Charges Spell 3 = 3 Charges Spell 4 = 1-4 Charges, depending on the size of the object illuminated by an aura. The Spell will affect on object up to its maximum potential area of effect regardless of charges used, but the brightness of the aura goes down as the size increases unless more charges are expended. The largest size category won't be as big as a castle, but I think something the size of an Argentinosaurus would be acceptable, as that's roughly the scale of the bigger Monsters you'd want to highlight if you're fighting one in the dark. So: 1 Charge = Objects between the size of a grape and a watermelon 2 Charges = Objects between the size of a watermelon and the size of a horse 3 Charges = Objects between the size of a horse and the size of a T-Rex 4 Charges = Objects between the size of a T-Rex and the size of an Argentinosaurus The base setting for each Spell is the intensity of a candle. We'll keep it simple and leave out any concerns with comparisons to modern light bulbs of any kind. The Light Wand has five settings that can be applied to each Spell. Each setting multiplies the brightness by a fixed number of candles. The multiplier cannot be tweaked beyond these five settings, as that would be too difficult for most people to manage without more than a basic understanding of using Arcane Devices. These are meant to be things an average person can use, after all. The settings (beyond the first 1 candle baseline) are: 25 Candles = 315 Lumens = X25 Charges 50 Candles = 630 Lumens = X50 Charges 75 Candles = 945 Lumens = X75 Charges 100 Candles = 1,260 Lumens = X100 Charges Thus: Spell 1 = 1 Charge, 25 Charges, 50 Charges, 75 Charges, and 100 Charges Spell 2 = 1 Charge, 50 Charges, 100 Charges, 150 Charges, and 200 Charges Spell 3 = 1 Charge, 75 Charges, 150 Charges, 225 Charges, and 300 Charges Spell 4 (on an Argentinosaurus) = 4 Charges, 100 Charges, 200 Charges, 300 Charges, and 400 Charges Now, that may seem like a lot of charges for the Light Wand to hold, but in terms of the actual amount of Aethyr used per charge, it isn't actually a huge amount of energy. It would really depend on the capacity of the Spellgem used to store the Aethyr. Further, since most Light Wands don't have all four Spells (they might only have the first two) and may only go up to Setting 2 at most, the cheaper models wouldn't need any high capacity Spellgem, making them much cheaper to produce. I think that the highest caliber Light Wand, with all four Spells and all five Settings, would be able to hold a maximum of 1,600 Charges when fully energized. That amount of Aethyr would probably still be less than an amplified hand grenade Spell requires, since it's only generating visible light, not any kind of kinetic force or heat. And even at 1,600 Charges, the Light Wand would only be able to use its strongest Spell at the highest setting 4 times before it was depleted of energy. Not terrible, unless you're being attacked by five homicidal Argentinosauruses on a very dark night. You'd only be able to highlight four of them. Granted, the bright glow of those four might reveal the fifth one... provided it wasn't a ninja Argentinosaurus dressed in light absorbing spandex. (I wound how big of a katana it would use.) The only real issue I can see with this is how the consumer knows how many charges the Light Wand has left. However, I can see some sort of indicator being featured on some part of the wand, likely above the handle, that the user can consult to see if the Spell he wants to use can be done at the setting he desires. A Mage, conversely, wouldn't need such an indicator, as they have an innate ability to gauge the amount of Aethyr a Spell is going to need. (Of course, a Mage wouldn't need to rely on a Light Wand in the first place, as a Mage can just cast the Spell himself at whatever potency he desires as long as he has sufficient Aethyr available.) So, I think this is how I'm going to set up the Light Wand. Let me know if there are any issues you see with it or a simpler way to keep track of the energy in the Light Wand.	According to <https://en.wikipedia.org/wiki/Candela#Relationships_between_luminous_intensity,_luminous_flux,_and_illuminance> > > If the source emits light uniformly in all directions, the flux can be found by multiplying the intensity by 4π: a uniform 1 candela source emits 12.6 lumens. > > > <https://en.wikipedia.org/wiki/Incandescent_light_bulb> > > The luminous efficacy of a typical incandescent bulb is 16 lumens per watt, compared with > > > 60 lm/W for a compact fluorescent bulb or > > > 150 lm/W for some white LED lamps. > > > Thus, through simple division you can calculate (imperfectly, yes, because of the differences between candelas, lumens, and lux but your readers won't care): Incandescent: `16 / 12.6 = 1.3` candles/watt. CFL: `60 / 12.6 = 4.8` candles/W` LED: `150 / 12.6 = 11.9` candles/W Now to the big problem with your specifications: ``` Setting 1 = the light of a single candle Setting 2 = a 25 watt light bulb Setting 3 = a 50 watt light bulb Setting 4 = a 75 watt light bulb Setting 5 = a 100 watt light bulb ``` The problem is that you do not specify what kind of light bulbs. (Since no light bulbs existed during the flintlock era, we shouldn't assume incandescent bulbs.) You must decide what kind of light bulbs you are comparing your wands to. Whatever kind of bulb you choose, you'll still have a problem, since -- for example -- a 25W CFL bulb is the equivalent of `25 * 4.8 = 120` candles. That's a lot of candles!! > > So, what advice can you offer? > > > Drastically scale back the wattage equivalents for Settings 2-5.
128,134	<p>What are some ideas, preferably based in clever word usage, puns, or some such, for derogatory terms or slurs (of varying intensity) for the inhabits of Mars/Ceres/Deimos/Venus/Jovian moons/other celestial bodies?<br> These insults should preferably not actually use any "unsavory" language<br> And are meant to refer to humans living on these bodies </p> <pre><code>Edit: I'm just looking for ideas </code></pre>	[ { "answer_id": 128145, "author": "Sora Tamashii", "author_id": 56536, "author_profile": "https://worldbuilding.stackexchange.com/users/56536", "pm_score": 2, "selected": false, "text": "<p>\"Alien\"\nImagine being referred to as something dehumanizing. It's pretty derogatory. \"But they ...	2018/10/22	[ "https://worldbuilding.stackexchange.com/questions/128134", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/47304/" ]	What are some ideas, preferably based in clever word usage, puns, or some such, for derogatory terms or slurs (of varying intensity) for the inhabits of Mars/Ceres/Deimos/Venus/Jovian moons/other celestial bodies? These insults should preferably not actually use any "unsavory" language And are meant to refer to humans living on these bodies ``` Edit: I'm just looking for ideas ```	"Alien" Imagine being referred to as something dehumanizing. It's pretty derogatory. "But they are aliens!" That's a pretty racist thing to say. Otherwise, "greeny" for Martians. For the others, slurs based on the myths their celestial body was named after. All Venusians being called "sluts" and "easy", for example.
129,898	<p>I'm asking this question as a reference for use in worldbuilding when developing world size, atmospheric content, or alien optometric abilities (aka, vision). </p> <p>While I'm specifically asking two questions, their relevance is so close that it's more practical to ask them once, together.</p> <p>Given...</p> <ul> <li>A sphere 10 Km in diameter</li> <li>It's homogeneous (the material isn't relevant)</li> <li>Having an <a href="https://en.wikipedia.org/wiki/Albedo" rel="nofollow noreferrer">albedo</a> of 70% (similar to fresh snow)</li> </ul> <p>How far away can that sphere be...</p> <p>A) In space, with Sol at the observer's back, the observer 1 AU from Sol?</p> <p>B) In space as in (A), but assuming for the purposes of this question, that space is filled with an <a href="https://en.wikipedia.org/wiki/Aether_(classical_element)" rel="nofollow noreferrer">aether</a> in all ways equivalent to Earth's atmosphere at sea level?</p> <p>And still be seen (even if its shape cannot be clearly distinguished, i.e., a "point") by the average human eye?</p> <p><em>Assumptions</em></p> <p>1.&emsp;I understand that eye sensitivity to light and focus vary between people. I don't know how to specify the "average." If someone can provide metrics that would clarify this issue, please leave a comment and I'll add them into the question.</p> <p>2.&emsp;For the purpose of this question, please ignore the lack of ground. I understand that light reflecting from surfaces between the oberserver and the observed will contribute (substantially, I suspect) to whether or not an object can be seen at a distance. I could be wrong, but I believe the basic setup I've proposed represents a best-case scenario.</p> <p>3.&emsp;For the purpose of this question, please ignore the fact that the sun <em>isn't</em> above the observer. In other words, it's shining from behind the observer rather than above or on top of the observer. This effects the amount of <a href="https://en.wikipedia.org/wiki/Rayleigh_scattering" rel="nofollow noreferrer">Rayleigh Scattering</a> that would also contribute to visibility. Once again, I suspect this makes the setup a best-case scenario.</p> <p>4.&emsp;Ignore the fact that our hapless observer is sans-spacesuit. In other words, there's nothing about his/her environment as the observer that's affecting his/her vision (no faceplate). Lucky dude, as otherwise the eyes would have a bit of trouble in the vacuum of space.</p> <p>5.&emsp;The atmosphere between the oberver and the observed is <em>uniform.</em> This is different from the conditions of a planet (convex) or the inner surface of a Dyson sphere or ringworld (concave) where the atmosphere density is not uniform along the sight path.</p> <p>6.&emsp;Please ignore the field of stars (assume they aren't there). This isn't a test of how well a human can identify one tiny mote from a field of tiny, shining motes.</p> <p><em>A curious thought...</em></p> <p>Please note that there may be a considerable difference between the sun behind the observer and the sun above and midway between the observer and the observed as the reflection off the sphere may (may...) be greater in the later case. However, it would only be greater on the top half of the sphere (closest to the sun) while it would be lower on the bottom half (and all the Rayleigh scattering issues come into play... and the sun's in your eyes...). At this time, I'm thinking that placing the light source behind the observer produces the highest reflectivity and lowest optical distortion for the greatest distance. If the math says I'm wrong, please let me know.</p>	[ { "answer_id": 129899, "author": "mreff555", "author_id": 46291, "author_profile": "https://worldbuilding.stackexchange.com/users/46291", "pm_score": 2, "selected": false, "text": "<p>In aviation, part of the daily forecast is the estimation of unobstructed visibility. Obviously at a re...	2018/11/11	[ "https://worldbuilding.stackexchange.com/questions/129898", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/40609/" ]	I'm asking this question as a reference for use in worldbuilding when developing world size, atmospheric content, or alien optometric abilities (aka, vision). While I'm specifically asking two questions, their relevance is so close that it's more practical to ask them once, together. Given... * A sphere 10 Km in diameter * It's homogeneous (the material isn't relevant) * Having an [albedo](https://en.wikipedia.org/wiki/Albedo) of 70% (similar to fresh snow) How far away can that sphere be... A) In space, with Sol at the observer's back, the observer 1 AU from Sol? B) In space as in (A), but assuming for the purposes of this question, that space is filled with an [aether](https://en.wikipedia.org/wiki/Aether_(classical_element)) in all ways equivalent to Earth's atmosphere at sea level? And still be seen (even if its shape cannot be clearly distinguished, i.e., a "point") by the average human eye? Assumptions 1. I understand that eye sensitivity to light and focus vary between people. I don't know how to specify the "average." If someone can provide metrics that would clarify this issue, please leave a comment and I'll add them into the question. 2. For the purpose of this question, please ignore the lack of ground. I understand that light reflecting from surfaces between the oberserver and the observed will contribute (substantially, I suspect) to whether or not an object can be seen at a distance. I could be wrong, but I believe the basic setup I've proposed represents a best-case scenario. 3. For the purpose of this question, please ignore the fact that the sun isn't above the observer. In other words, it's shining from behind the observer rather than above or on top of the observer. This effects the amount of [Rayleigh Scattering](https://en.wikipedia.org/wiki/Rayleigh_scattering) that would also contribute to visibility. Once again, I suspect this makes the setup a best-case scenario. 4. Ignore the fact that our hapless observer is sans-spacesuit. In other words, there's nothing about his/her environment as the observer that's affecting his/her vision (no faceplate). Lucky dude, as otherwise the eyes would have a bit of trouble in the vacuum of space. 5. The atmosphere between the oberver and the observed is uniform. This is different from the conditions of a planet (convex) or the inner surface of a Dyson sphere or ringworld (concave) where the atmosphere density is not uniform along the sight path. 6. Please ignore the field of stars (assume they aren't there). This isn't a test of how well a human can identify one tiny mote from a field of tiny, shining motes. A curious thought... Please note that there may be a considerable difference between the sun behind the observer and the sun above and midway between the observer and the observed as the reflection off the sphere may (may...) be greater in the later case. However, it would only be greater on the top half of the sphere (closest to the sun) while it would be lower on the bottom half (and all the Rayleigh scattering issues come into play... and the sun's in your eyes...). At this time, I'm thinking that placing the light source behind the observer produces the highest reflectivity and lowest optical distortion for the greatest distance. If the math says I'm wrong, please let me know.	Calculating apparent magnitude ============================== Your alignment of the sun, the observer (in space), and the object is as so ``` 1 AU r AU (Sun) ------------- (obsv) ---------//------------(obj) ``` Given that, there are three separate calculations. First is the magnitude of reflected incident energy from the sun. The second is the magnitude of reflected light, given the difference in visible disk of the object, compared to the sun. The third is the brightness of this light to the observer. An issue here is that luminosity is a full spectrum measure of energy output, but we are only interested in energy from the visible spectrum. Since I can't find a visual spectrum only luminosity for the sun to do an energy calculation, we can use the [absolute magnitude](https://en.wikipedia.org/wiki/Absolute_magnitude) of the moon (+0.25) as our starting point. We must adjust the magnitude of the moon by four factors; as each of these factors increases, the object will be relatively dimmer: * Squared ratio of distance from sun to object to distance from sun to moon * Ratio of surface area of the moon to surface area of the object * Albedo of moon to albedo of object * Squared ratio of distance of object to Earth to distance of moon to Earth A difference of $n$ visual magnitudes is equal to a difference of a factor of $100^{n/5}$ in luminosity. Thus, the logarithm base $100^{1/5}=2.512$ of these ratios is summed. We will use $\log$ to represent $\log\_{2.512} = 2.5\log\_{10}$ for simplicity. The distances are straightforward, and are calculated in terms of AU; the moon is roughly 0.00257 AU from Earth. The surface areas of the moon and object are proportional to the radii squared. The object has a radius of 5 km, while the moon is 1738 km. The albedo of the moon is a paltry 0.12, while the object is an incandescent 0.70. We get the following equation for [apparent visual magnitude](https://en.wikipedia.org/wiki/Absolute_magnitude#Solar_System_bodies_(H)) of the object: $$0.25 + \log\left(\frac{(r+1\text{ AU})^2}{(1\text{ AU})^2}\right)+\log\left(\frac{1738^2\text{ m}^2}{5^2\text{ m}^2}\right)+\log\left(\frac{0.12}{0.70}\right)+\log\left(\frac{(r \text{ AU})^2}{(0.00257\text{ AU})^2}\right) $$ How far away can we see this object? ==================================== In a big city at night you might only be able to see a magnitude 3 object, while on a moonless night in the middle of the ocean you could see a magnitude 8 object. Lets say that you can see a magnitude 6 object. Attenuation by the atmospheric mass directly overhead is about 0.145 magnitudes; that means that if we were in space, we could see a magnitude 6.145 object. I take the above equation and, for values of r in AU, plot the apparent magnitude of the object on log scale. [![enter image description here](https://i.stack.imgur.com/2OmWe.png)](https://i.stack.imgur.com/2OmWe.png) The code is here: ``` >>> import numpy as np >>> func = lambda r : 0.25 + 2.5np.log10((r+1)2)+2.5np.log10(17382/52)+2.5np.log10(0.12/0.70)+2.5np.log10((r/0.00257)2) >>> x = [x/2-10 for x in range(22)] >>> y = [func(np.exp(i)) for i in x] >>> plt.plot(x, y) [<matplotlib.lines.Line2D object at 0x7fdb949d7eb8>] >>> plt.xlabel("Distance from Earth in exp(x) AU") Text(0.5,0,'Distance from Earth in exp(x) AU') >>> plt.ylabel("Apparent visual magnitude") Text(0,0.5,'Apparent visual magnitude') >>> plt.show() ``` The solution for apparent magnitude 6.15 is 0.00027 AU. This is 1/100 the distance from the Earth to the moon, 41,000 km; or, roughly, geostationary orbit.**
129,966	<p>... And if it absolutely has to, then such river should overflow in predictable matter.</p> <p>I have a city idea in mind, where such the city has a river contained in an artificial tunnel beneath such city. I instantly know one huge design flaw of such a city, which is the floods.</p> <p>So, I have to take one step back and come up with a design of a river which does not overflow.</p> <p><strong>Setup</strong></p> <ul> <li>Earth-based planet, but not necessarily Earth</li> <li>This river may be on an island or on a continent, I do not really care</li> <li>The land mass around a city sitting on such river should be big enough to support city of at least 100 000 citizens</li> <li>The weather should support civilization, best would be northern Europe -like weather (seasons, temperatures between -30 to +35 degrees Celsius, long term average 18 C)</li> <li>The river itself should be at least 50 km long and at least 4m wide on widest point</li> </ul> <p>So, is it possible to come up with setup which supports a predictable river?</p>	[ { "answer_id": 129967, "author": "L.Dutch", "author_id": 30492, "author_profile": "https://worldbuilding.stackexchange.com/users/30492", "pm_score": 4, "selected": false, "text": "<p>You can realize a large basin upstream, where you can divert the excess water during overflow time.</p>\n...	2018/11/12	[ "https://worldbuilding.stackexchange.com/questions/129966", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/2071/" ]	... And if it absolutely has to, then such river should overflow in predictable matter. I have a city idea in mind, where such the city has a river contained in an artificial tunnel beneath such city. I instantly know one huge design flaw of such a city, which is the floods. So, I have to take one step back and come up with a design of a river which does not overflow. Setup * Earth-based planet, but not necessarily Earth * This river may be on an island or on a continent, I do not really care * The land mass around a city sitting on such river should be big enough to support city of at least 100 000 citizens * The weather should support civilization, best would be northern Europe -like weather (seasons, temperatures between -30 to +35 degrees Celsius, long term average 18 C) * The river itself should be at least 50 km long and at least 4m wide on widest point So, is it possible to come up with setup which supports a predictable river?	Rivers with stable flow (with [data source](http://grdc.sr.unh.edu/index.html)) =============================================================================== ### River downstream of a large lake * The larger the lake, the most stable the flow out of it. Also, it helps that the lake be in a temperate environment, oo water input into the lake doesn't vary too much. The lake can freeze over, as can the outlet river, without really affecting flow much; this happens in the case of the example. * Example - Saint Mary's River (between Lake Superior and Lake Huron in US/Canada) at Sault Ste. Marie. Other good examples are the Rhone downstream of Lake Geneva, and the Neva downstream of Lake Ladoga. * Pro - Very stable flow rate, year round (assuming the lakes don't freeze). Low ratio and magnitude of seasonal fluctuations. When improved with canals and locks, this makes for a great trading city. * Con - In many cases, these outlet rivers are steep and un-navigable. [![enter image description here](https://i.stack.imgur.com/MS7rO.png)](https://i.stack.imgur.com/MS7rO.png) ``` Extreme high flow 3590 Expected annual high 2385 Average flow 2142 Excess over expect high 1205 Excess over average 1448 Ratio over expect high 0.51 Ratio over average 0.68 ``` (Note, all units are in cubic meters per second, except ratio) ### Large tropical river * A large tropical river where half of the river basin is in each hemisphere. As the monsoon rains are pushed by the Intertropical Convergence Zone back and forth between the hemispheres, you will end up with relatively stable rainfall throughout the year. * Example - Congo River measured at Kinshasa. * Pros - Very low seasonal flow variance. Also, an enormous basin for river-borne trade with the city. * Cons - Very high magnitude of flow variance. When the river is this big, even a little bit of flooding is a big deal. [![enter image description here](https://i.stack.imgur.com/Sgapb.png)](https://i.stack.imgur.com/Sgapb.png) ``` Extreme high flow 80832 Expected annual high 56081 Average flow 39536 Excess over expect high 24751 Excess over average 41296 Ratio over expect high 0.44 Ratio over average 1.04 ``` ### A temperate river with little snowmelt * The next best scenario is a river with a small basin with constant, low level rainfall, and little snow accumulation. * Example - Seine River at Paris. * Pro - Despite being a big enough river for a truly large city, the magnitude of highest recorded flood to average winter high water is not large. * Con - Large seasonal fluctuations, can be difficult to navigate in summer time due to low water levels. [![enter image description here](https://i.stack.imgur.com/UtBwX.png)](https://i.stack.imgur.com/UtBwX.png) ``` Extreme high flow 1284 Expected annual high 560 Average flow 268 Excess over expect high 724 Excess over average 1016 Ratio over expect high 1.29 Ratio over average 3.79 ``` Examples of bad rivers ====================== ### Continental river with large, dry basin Example Arkansas River in the US, measured at Little Rock. In the interior US, random thunderstorms lasting for a few days can cause serious flooding, usually in spring or early summer. ``` Extreme high flow 8220 Expected annual high 2044 Average flow 1066 Excess over expect high 6176 Excess over average 7145 Ratio over expect high 3.02 Ratio over average 6.71 ``` ### Continental river with enormous spring snowmelt Example - Tom River measured at Tomsk, in Siberia. While the high river levels with snowmelt is relatively predictable, it is still very large compared to regular river levels. ``` Extreme high flow 7500 Expected annual high 4622 Average flow 1047 Excess over expect high 2878 Excess over average 6453 Ratio over expect high 0.62 Ratio over average 6.16 ``` ### River in Monsoon area Example - Vijayawada river in southern India measured at its mouth. While the timing of the monsoon is predictable, its magnitude is not. An erratic monsoon can produce spectacular flooding. ``` Extreme high flow 16555 Expected annual high 6266 Average flow 1642 Excess over expect high 10289 Excess over average 14913 Ratio over expect high 1.64 Ratio over average 9.08 ```
130,118	<p>Planetary surface:</p> <ul> <li>\| 71% Ocean (H2O) \| 29% Land \| </li> </ul> <p>Atmospheric composition:</p> <ul> <li>\| 2% Trace gases \| 58% Nitrogen \| 26% Oxygen \| 11% Argon \| 3% Carbon dioxide \| </li> </ul> <p>Average surface temperature:</p> <ul> <li>36 degrees Celsius</li> </ul> <p>Planetary rotation:</p> <ul> <li>34 hours</li> </ul> <p>Axial tilt:</p> <ul> <li>0</li> </ul> <p>Info regarding of altitude, pressure, and atmospheric density:</p> <pre><code>altitude pressure density (meters) (atm) (kg/m^3) 0 17 10 1000 15.3 9 2000 13.8 8.1 3000 12.5 7.3 4000 11.3 6.6 5000 10.1 6 10000 6 3.6 15000 3.6 2.1 20000 2.2 1.3 30000 0.8 0.5 40000 0.3 0.2 50000 0.1 0.06 </code></pre> <p>Keep in mind the oceans are 30% shallower, half the salinity and the surface gravity is 1.36x that of Earths, and the majority of the continents are as big as Australia. <strong>At what altitudes would clouds form to produce rain on this world and with what general severity? By general severity I mean how severe would storm systems on a global scale be in contrast to Earths?</strong></p>	[ { "answer_id": 130138, "author": "kingledion", "author_id": 23519, "author_profile": "https://worldbuilding.stackexchange.com/users/23519", "pm_score": 2, "selected": false, "text": "<h1>How cloud formation occurs</h1>\n\n<p><a href=\"https://i.stack.imgur.com/Bpv1Y.gif\" rel=\"nofollow ...	2018/11/13	[ "https://worldbuilding.stackexchange.com/questions/130118", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/53282/" ]	Planetary surface: * \| 71% Ocean (H2O) \| 29% Land \| Atmospheric composition: * \| 2% Trace gases \| 58% Nitrogen \| 26% Oxygen \| 11% Argon \| 3% Carbon dioxide \| Average surface temperature: * 36 degrees Celsius Planetary rotation: * 34 hours Axial tilt: * 0 Info regarding of altitude, pressure, and atmospheric density: ``` altitude pressure density (meters) (atm) (kg/m^3) 0 17 10 1000 15.3 9 2000 13.8 8.1 3000 12.5 7.3 4000 11.3 6.6 5000 10.1 6 10000 6 3.6 15000 3.6 2.1 20000 2.2 1.3 30000 0.8 0.5 40000 0.3 0.2 50000 0.1 0.06 ``` Keep in mind the oceans are 30% shallower, half the salinity and the surface gravity is 1.36x that of Earths, and the majority of the continents are as big as Australia. At what altitudes would clouds form to produce rain on this world and with what general severity? By general severity I mean how severe would storm systems on a global scale be in contrast to Earths?	How cloud formation occurs ========================== [![enter image description here](https://i.stack.imgur.com/Bpv1Y.gif)](https://i.stack.imgur.com/Bpv1Y.gif) Warm air near the surface of the Earth can rise for many reasons. As it rises, it undergoes [adiabatic cooling](https://en.wikipedia.org/wiki/Adiabatic_process#Adiabatic_heating_and_cooling). Since the pressure drops with rising air, the gas must expand slightly while the temperature drops, as suggested by the ideal gas law ($PV = nRT$). As the temperature drops, the relative humidity of the air rises. If the air rises far enough, and cools enough, then humidity exceeds 100% and moisture precipitates as water droplets. This makes clouds. If enough water precipitates in the clouds, the droplets become big enough that they cannot be suspended in the air and they fall as rain (or snow, depending on temps). Clouds can form at different altitudes depending on local conditions. Clouds never form above deserts, since there is so little moisture in the air. Clouds form at ground level above wet jungles, since humidity is already 100 %, and any cooling will cause moisture to precipitate. For other climates and conditions, cloud altitude varies. How is this affected on your world? =================================== Lets put your pressure to altitude map side by side with Earth's ``` altitude Your press Earth press (meters) (atm) (atm) ratio 0 17 1 17 1000 15.3 0.89 17 2000 13.8 0.78 18 3000 12.5 0.69 18 4000 11.3 0.61 19 5000 10.1 0.53 19 10000 6.0 0.26 23 15000 3.6 0.12 30 20000 2.2 0.05 44 ``` Air pressure on your planet is relatively higher at altitude, meaning the pressure gradient with increasing altitude is lower than it is on Earth. Since the cooling is driven by pressure changes (again, $PV = nRT$), if lower the rate of pressure change with altitude, then we lower the rate of temperature change with altitude. Therefore, on your planet, cloud formation occurs at slightly higher altitudes than it would on Earth, given similar temperature and humidity conditions at ground level.
130,713	<p>Atmospheric composition:</p> <ul> <li>\| 2% Trace gases \| 58% Nitrogen \| 26% Oxygen \| 11% Argon \| 3% Carbon dioxide \| </li> </ul> <p>Average surface temperature:</p> <ul> <li>36 degrees Celsius</li> </ul> <p>Surface gravity: </p> <ul> <li>1.36x Earth gravity</li> </ul> <p>Info regarding of altitude, pressure, and atmospheric density:</p> <pre><code>altitude pressure density (meters) (atm) (kg/m^3) 0 17 10 1000 15.3 9 2000 13.8 8.1 3000 12.5 7.3 4000 11.3 6.6 5000 10.1 6 10000 6 3.6 15000 3.6 2.1 20000 2.2 1.3 30000 0.8 0.5 40000 0.3 0.2 50000 0.1 0.06 </code></pre> <p>What adaptations would creatures normally have on this world based on the high pressures of the atmosphere given? Would they have looser bones? Pressurized gas within the bones? Etc? <strong>If possible, give detailed hypothetical answers, I'll be glad if examples are given in the answers for the question I'm asking</strong></p>	[ { "answer_id": 130732, "author": "anon", "author_id": 41670, "author_profile": "https://worldbuilding.stackexchange.com/users/41670", "pm_score": 2, "selected": false, "text": "<p>Pressure is a funny thing in biology </p>\n\n<p>Note what i am about to say does not apply to vaccum because...	2018/11/19	[ "https://worldbuilding.stackexchange.com/questions/130713", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/53282/" ]	Atmospheric composition: * \| 2% Trace gases \| 58% Nitrogen \| 26% Oxygen \| 11% Argon \| 3% Carbon dioxide \| Average surface temperature: * 36 degrees Celsius Surface gravity: * 1.36x Earth gravity Info regarding of altitude, pressure, and atmospheric density: ``` altitude pressure density (meters) (atm) (kg/m^3) 0 17 10 1000 15.3 9 2000 13.8 8.1 3000 12.5 7.3 4000 11.3 6.6 5000 10.1 6 10000 6 3.6 15000 3.6 2.1 20000 2.2 1.3 30000 0.8 0.5 40000 0.3 0.2 50000 0.1 0.06 ``` What adaptations would creatures normally have on this world based on the high pressures of the atmosphere given? Would they have looser bones? Pressurized gas within the bones? Etc? If possible, give detailed hypothetical answers, I'll be glad if examples are given in the answers for the question I'm asking	Pressure is a funny thing in biology Note what i am about to say does not apply to vaccum because i am generalizing somethings. In many ways pressure is irrelevant to physiology. What is critical is pressure difference because that is what kills. It would be possible for a human like body to survive (if created there) in the marianas trench only to explode when brought to sea level. There are plenty of fish that are great examples of this being able to exist in both places. This obviously isnt the whole story. Those same fish have adaptations and simpler physiology to handle rapid yet gradual changes in pressure. For instance, gases acrue in their swim bladder which must then be expelled. Now to put your question into a little more perspective: The highest atmospheric pressure humans have survived in is ~14.7atm which is pretty close to the 17atm listed objective. This begins to show you that not a whole lot is needed for life to survive at that pressure. Now one thing that id like to touch on is gas exchange. The key for organisms to respire in their environment is their ability to take in the abundant environmental chemistry to use in their metabolic processes. These constructs can have a lot of dependence on pressure. Gills dont function so well in air. Matter of fact we humans have a diaphram specifically to ensure a constant circulating supply of atmosphere. In higher pressures its reported that breathing requires less exertion. So to answer your question, there MAY be no visible outward difference in adaptations at this pressure. There may be differences in respiratory organs. Its really however your alien nature decides to solve the problem of gas exchange, which there is no universal answer for and can be beyond our immagination. <https://www.quora.com/What-is-the-maximum-atmospheric-pressure-a-human-can-survive>
130,725	<p>How can I predict the color of the sky based on the information provided?</p> <p>Atmospheric composition:</p> <ul> <li>\| 2% Trace gases \| 58% Nitrogen \| 26% Oxygen \| 11% Argon \| 3% Carbon dioxide \| </li> </ul> <p>Average surface temperature:</p> <ul> <li>36 degrees Celsius</li> </ul> <p>Planetary rotation:</p> <ul> <li>34 hours</li> </ul> <p>Axial tilt:</p> <ul> <li>0</li> </ul> <p>Info regarding of altitude, pressure, and atmospheric density:</p> <pre><code>altitude pressure density (meters) (atm) (kg/m^3) 0 17 10 1000 15.3 9 2000 13.8 8.1 3000 12.5 7.3 4000 11.3 6.6 5000 10.1 6 10000 6 3.6 15000 3.6 2.1 20000 2.2 1.3 30000 0.8 0.5 40000 0.3 0.2 50000 0.1 0.06 </code></pre> <p>Keep in mind, the type of star this world is orbiting is an F9V class star, only slightly above a G1V. </p>	[ { "answer_id": 130733, "author": "kingledion", "author_id": 23519, "author_profile": "https://worldbuilding.stackexchange.com/users/23519", "pm_score": 3, "selected": false, "text": "<h1>Blue, but darker</h1>\n\n<p>Earth's sky is blue due to <a href=\"https://worldbuilding.stackexchange....	2018/11/19	[ "https://worldbuilding.stackexchange.com/questions/130725", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/53282/" ]	How can I predict the color of the sky based on the information provided? Atmospheric composition: * \| 2% Trace gases \| 58% Nitrogen \| 26% Oxygen \| 11% Argon \| 3% Carbon dioxide \| Average surface temperature: * 36 degrees Celsius Planetary rotation: * 34 hours Axial tilt: * 0 Info regarding of altitude, pressure, and atmospheric density: ``` altitude pressure density (meters) (atm) (kg/m^3) 0 17 10 1000 15.3 9 2000 13.8 8.1 3000 12.5 7.3 4000 11.3 6.6 5000 10.1 6 10000 6 3.6 15000 3.6 2.1 20000 2.2 1.3 30000 0.8 0.5 40000 0.3 0.2 50000 0.1 0.06 ``` Keep in mind, the type of star this world is orbiting is an F9V class star, only slightly above a G1V.	Blue, but darker ================ Earth's sky is blue due to [Rayleigh Scattering](https://worldbuilding.stackexchange.com/a/63962/23519). Rayleigh scattering redirects at an angle a percentage of incident light through a gas. The percentage of light reflected is proportion to $1/\lambda^4$, where lambda is the wavelength. That is, the shorter the wavelength, the more light is reflected. Violet light is most reflected, percentage-wise, but the purple section of the visible spectrum is small. So Blue light is the next most reflected, and since that portion of the visible spectrum is large, the sky is blue. For your atmosphere, the percentage of oxygen and argon are higher, but he percentage of nitrogen is lower. From Table 1 of [Shardanand and Rao, 1977](https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19770012747.pdf) here is a comparison of scattering cross section (in $10^{-27}\text{ cm}^{-2}$) for various atmospheric gasses at certain wavelengths (on the x-axis, in Angstroms): ``` Molecule 6328 5145 4880 4579 3638 O2 2.06 4.88 6.50 8.39 20.03 N2 2.24 5.61 7.26 10.38 23.82 Ar 2.08 5.46 7.24 10.13 23.00 CO2 7.28 17.25 23.00 29.60 70.70 CH4 5.26 12.44 16.59 21.40 51.10 ``` Notice how similar oxygen, nitrogen, and argon are to each other, as compared to carbon dioxide or methane. The relative rate at which the different wavelengths of light are scattered by your atmosphere will be almost the same as on Earth, so the color of the sky will be almost the same as on Earth. Your star will be putting out light in a spectrum very similar to that of our sun, so the highest magnitude wavelengths will be in the blue range, just as our Sun's are. See [here](https://worldbuilding.stackexchange.com/a/102636/23519) for more details. The final factor is the mass of the air column. The proportion of light both absorbed by the atmosphere and raleigh scattered is affected by the number of air molecules that a light wave encounters as it travels into the atmosphere. Without you giving a surface gravity, I can't exactly calculate the air column's mass, but from your pressure and density, the mass of the air column is something like 10 times as massive on Earth. Therefore, light will be that much more likely to be absorbed or scattered. This will make the sky a much darker shade of blue. But note, due to the same emission spectrum of the sun and the same scattering factors, that doesn't mean that the shade of blue is changed, just the brightness of the blue. The blue color will be the same shade, but darker.
130,970	<p>I’ve done a fair bit of research to come up with this scenario. I hope it’s not “too broad” to ask for a reality check. Have I overlooked anything? Does it all sound plausible?</p> <p>My world takes place in a massive crater, the only habitable place left on the planet. It is roughly 800 x 600 miles and 5 miles deep. At the bottom it is 1.2 atm in pressure, while the surface is at 0.5 atm.</p> <p>Due to the extreme “altitude” conditions the surface of the planet is cold (would it really be though?) windy, and home to extremophile bacteria mats/mounds, and possibly lichens/moss. The wind here is extremely fast because there’s not much to slow it down.</p> <p>The sides of the crater are gently sloping downwards, and the wind follows it down. The bacterial mats slowly give way to montane grassland and meadows. Early morning dew from the cold winds is the source of water here. Small gnarled trees grow slowly and are warped by the wind. Meadows are nearby springs, where ancient aquifers were fractured during the meteor impact.</p> <p>Next comes the treeline and the coniferous forests with fern undergrowth. The wind is slowed by both the trees and its compression at -12,000 feet into the crater. Rain occasionally falls here if the conditions are right. Overall the precipitation is mostly occult. This area has sizable lakes from other meteor impacts which are filled by fractured aquifers and streams from up the crater.</p> <p>Eventually the heat of the Earth warms the cool air and we reach temperate deciduous forests. Winds are breezy here and carry precipitation from higher up the crater. Evening showers are relatively common. Streams have become rivers by this point. The forests reach all the way to sea level, except where humans have cleared them away for agriculture. </p> <p>A massive sea covers much of the bottom of the crater, and fortunately it has reached an equilibrium between evaporation and being filled from the aquifers. </p> <p>In the sea are a series of islands from the complex crater. These islands experience hot moist air, daily rain, and are temperate rainforests. It is here, finally, that the air rises up in a massive updraft. The hot air rises, disperses, and mixes with the atmosphere. Some water vapor finds its way back into the crater, but much more leaves.</p> <p>I know it’s a big task, but does this all sound plausible? Is there anything I’ve missed or greatly overlooked?</p>	[ { "answer_id": 130987, "author": "Blade Wraith", "author_id": 50282, "author_profile": "https://worldbuilding.stackexchange.com/users/50282", "pm_score": 3, "selected": false, "text": "<p>I'll try to tackle each of your points, so reaslistically on the face of it, its fairly plausible</p...	2018/11/22	[ "https://worldbuilding.stackexchange.com/questions/130970", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/57574/" ]	I’ve done a fair bit of research to come up with this scenario. I hope it’s not “too broad” to ask for a reality check. Have I overlooked anything? Does it all sound plausible? My world takes place in a massive crater, the only habitable place left on the planet. It is roughly 800 x 600 miles and 5 miles deep. At the bottom it is 1.2 atm in pressure, while the surface is at 0.5 atm. Due to the extreme “altitude” conditions the surface of the planet is cold (would it really be though?) windy, and home to extremophile bacteria mats/mounds, and possibly lichens/moss. The wind here is extremely fast because there’s not much to slow it down. The sides of the crater are gently sloping downwards, and the wind follows it down. The bacterial mats slowly give way to montane grassland and meadows. Early morning dew from the cold winds is the source of water here. Small gnarled trees grow slowly and are warped by the wind. Meadows are nearby springs, where ancient aquifers were fractured during the meteor impact. Next comes the treeline and the coniferous forests with fern undergrowth. The wind is slowed by both the trees and its compression at -12,000 feet into the crater. Rain occasionally falls here if the conditions are right. Overall the precipitation is mostly occult. This area has sizable lakes from other meteor impacts which are filled by fractured aquifers and streams from up the crater. Eventually the heat of the Earth warms the cool air and we reach temperate deciduous forests. Winds are breezy here and carry precipitation from higher up the crater. Evening showers are relatively common. Streams have become rivers by this point. The forests reach all the way to sea level, except where humans have cleared them away for agriculture. A massive sea covers much of the bottom of the crater, and fortunately it has reached an equilibrium between evaporation and being filled from the aquifers. In the sea are a series of islands from the complex crater. These islands experience hot moist air, daily rain, and are temperate rainforests. It is here, finally, that the air rises up in a massive updraft. The hot air rises, disperses, and mixes with the atmosphere. Some water vapor finds its way back into the crater, but much more leaves. I know it’s a big task, but does this all sound plausible? Is there anything I’ve missed or greatly overlooked?	Temperature change is caused by lapse rate ========================================== The difference in temperature between the bottom and top of the crater is going to be driven by the [lapse rate](https://en.wikipedia.org/wiki/Lapse_rate), and not by the heat of the crust (probably). Lapse rate is the rate at which temperature in Earth's atmosphere decreases with an increase in altitude, or increases with the decrease in altitude. In particular, we can use a chart of moist adiabatic lapse rate to see what the expected temperature changes would be in a 5 mile (8 km) deep crater. [![enter image description here](https://i.stack.imgur.com/FkVxW.gif)](https://i.stack.imgur.com/FkVxW.gif) The 'Moist Adiabat's are the dotted lines on the chart. Chicago has a annual mean temp of about 10 C, Washington DC about 15 C, Houston about 20 C, and Miami 25 C. Pick your starting point, then follow the dotted line upwards until it intersects with the line representing 8 km. I get the following: ``` Floor Temp Surface Temp Surface Press 10 C -60 C 0.34 atm 15 C -45 C 0.36 atm 20 C -30 C 0.38 atm 25 C -15 C 0.42 atm ``` So you are looking at quite the different in temps. I also used this chart to double check your pressure estimates. Instead of starting at 1 atm, your crater surface starts at 1.2 atm, so I multiplied the resulting pressure estimates by 1.2. You are pretty close to being right on the pressure. Overall, the area outside the crater will be very uninhabitable. Why the Earth won't provide appreciable heating in the crater ============================================================= The [Earth's crust](https://en.wikipedia.org/wiki/Crust_%28geology%29#Earth's_crust) is about 30-50 km deep on the continents, away from tectonic boundaries, and it has a temperature gradient of about 200-400 C in heating between the surface and the boundary with the mantle. The [heat flux](https://en.wikipedia.org/wiki/Earth%27s_internal_heat_budget#Global_internal_heat_flow) on continental crust is about 71 mW/m$^2$. The simplest argument I can make is to compare the heat flux on the continental crust with the heat emitted by the Earth's surface in infra-red radiation. The Earth's surface emits 398 W/m$^2$ in IR radiation to the skies, on average. This is significantly higher than the 71 mW/m$^2$ that comes from inside the Earth. Lets look at what happens to planetary heat flux when we change the thickness of the crust. Planetary heat flux is controlled by the [Fourier's law](https://en.wikipedia.org/wiki/Thermal_conduction#Fourier's_law) for head conduction $$q = -k\nabla T.$$ Here $q$ is heat flux (W/m$^2$), $k$ is conductivity and $\nabla T$ is the heat gradient. If we reduce the distance between crust and surface by 8 km, from 25 km to 17 km, with a constant 300 K temperature differential then $\nabla T$ goes from 12 K/km to 17.6 K/km. This represents a 1.5 times increase in heat flux out of the Earth's surface. So the Earth is providing something like 120 mW/m$^2$ at the bottom of your crater instead of 70 mW/m$^2$. Still, compared to 160 W/m$^2$ absorbed from sunlight and 80 W/m$^2$ released by evapo-transpiration and IR radiation to space, and back-radiation received from atmosphere and clouds....you get the picture. The change in planetary heat flux is negligible, three orders of magnitude smaller, at least. Therefore, the temperature gradient between the crater bottom and high surface are going to be driven mostly by lapse rate, the same factor that drives the temperature difference between sea level and the top of Mount Everest on Earth. Air flow around the crater ========================== [![enter image description here](https://i.stack.imgur.com/5G8KT.gif)](https://i.stack.imgur.com/5G8KT.gif) Your crater is much hotter than the surrounding air. Hot air tends to rise. The dominant climactic feature will be rising hot air out of the crater. This will cause a variety of follow on effects. ### Rising hot air creates cyclones! Your crater is so large it will induce high speed, cyclonic winds circling around it. In the diagram above, the 'x' and 'o' represent winds into and out of the page around the crater. There will be permanent winds swirling around the crater. If your crater is entirely in the northern or southern hemisphere (assuming your planet is rotating like Earth) the [Coriolis effect](https://en.wikipedia.org/wiki/Coriolis_force) will drive the winds into a stable clockwise or anti-clockwise rotation around the crater. If the crater straddles the equator....something will happen, I'm not really sure. if the crater is on the Equator and large enough relative to the size of the planet, the cyclone may actually form a circle around the surface of the planet, but don't quote me on that. ### Rising air releases moisture as it cools As your air rises, it will lose its ability to hold moisture. You can see this from the thermodynamic diagram at the top of the page. If we assume a jungle-y 25 C average temperatures at the bottom of the crater, then that air can hold about 20 g of water per cubic meter. Elevate that air to 8 km, and it can hold about 3.5 g, leaving the remainder to fall as rain. The center of your crater will be constantly raining. The temperature gradient between crater bottom and surface is going to be much higher than the temperature gradient between day and night, therefore, you will always have a steadily rising column of hot air. Various wind conditions might blow around pockets of warm air, especially towards the edges, but you can assume the center of the crater will see rain every single day. The hotter the crater, the higher the magnitude difference in saturation mixing ratio will be, so the more rain you will get. A 10 C crater will get light rain every day, a 25 C crater will see permanent torrential rainfall. ### Descending cold air will enter the crater like a blast furnace From the cyclone swirl, descending cold air will spiral into the basin to take the place of the air that rose out. The force of gravity will ram this wind into higher pressure areas at the bottom of the crater, and the resulting molecular friction will be expressed as adiabatic heating. These are [foehn winds](https://en.wikipedia.org/wiki/Foehn_wind). The 8 km drop means that you would see an expected 30-60 C of adiabatic heating as the wind rushes downhill. Given that the wind already has high kinetic energy from the hurricane swirl at the top, the result near the bottom with be superheated blast-furnace winds. If conditions are right at the top, with extra solar heating for whatever reason, you could easily see steady 45 C or higher gale-force winds at the bottom of the crater. No trees will live on the slopes of the crater, due to the high wind speeds and highly variable temperatures. The slopes could easily see temperature changes of 30 C in a matter of minutes, as one air mass blast past and is replace by another.
134,107	<p>Orgone is the measure of a person's connection with the cosmos. It is the conduit through which the power of the cosmos flows, focused through a sorcerer's will. Ritual practicioners must draw on this reserve of power to make a magic spell work. Spells require a constant infusion of Orgone through rituals that are performed inside a transmutation circle. These rituals vary by time, and can last anywhere from 30 minutes to several hours depending on the spell.</p> <p>Enchantment Spells – These are spells designed to capture cosmic power within a crafted item, so that its power can be called upon in times of need.</p> <p>Scrying Spells – These are spells designed to allow a user to perceive in ways that go beyond his fve senses.</p> <p>Summoning Spells – These are spells designed to call up unnatural creatures, either for communion or servitude. They can also force such creatures into bondage.</p> <p>Transmogrifcation Spells – These are spells designed to fundamentally alter or control another being</p> <p>A circle can have a maximum of 9 mages. If more power for a spell is needed, a new, separate circle must be formed with its own individuals. For those circles to combine their orgone, a bridge must be created between them to link them together. Orgone cannot be transferred to inanimate materials or objects, as it needs to be actively moved between circles. Therefore, a channeler is used as this link. This individual connects the circles together in order to transfer orgone from one to the other and combine their power. Using this method, several circles can be combined to conduct a ritual.</p> <p>There is a problem. These circles joining their power together creates a lot of excess energy. The transfer rate of orgone from one circle to the next will ultimately speed up during the ritual, turning that excess energy into heat. As the point of connection between these transmutation circles, the channeler inetivably becomes the bearer of all this heat buildup. This could be dangerous to the individual, for the link must remain open for the spell to work. This can potentially kill the channeler by cooking them from the inside.</p> <p>How can I prevent this from happening?</p>	[ { "answer_id": 134112, "author": "Shadowzee", "author_id": 45212, "author_profile": "https://worldbuilding.stackexchange.com/users/45212", "pm_score": 2, "selected": false, "text": "<p>There are a couple of ways you could end up limiting this or restricting your magic system to account f...	2018/12/16	[ "https://worldbuilding.stackexchange.com/questions/134107", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/52361/" ]	Orgone is the measure of a person's connection with the cosmos. It is the conduit through which the power of the cosmos flows, focused through a sorcerer's will. Ritual practicioners must draw on this reserve of power to make a magic spell work. Spells require a constant infusion of Orgone through rituals that are performed inside a transmutation circle. These rituals vary by time, and can last anywhere from 30 minutes to several hours depending on the spell. Enchantment Spells – These are spells designed to capture cosmic power within a crafted item, so that its power can be called upon in times of need. Scrying Spells – These are spells designed to allow a user to perceive in ways that go beyond his fve senses. Summoning Spells – These are spells designed to call up unnatural creatures, either for communion or servitude. They can also force such creatures into bondage. Transmogrifcation Spells – These are spells designed to fundamentally alter or control another being A circle can have a maximum of 9 mages. If more power for a spell is needed, a new, separate circle must be formed with its own individuals. For those circles to combine their orgone, a bridge must be created between them to link them together. Orgone cannot be transferred to inanimate materials or objects, as it needs to be actively moved between circles. Therefore, a channeler is used as this link. This individual connects the circles together in order to transfer orgone from one to the other and combine their power. Using this method, several circles can be combined to conduct a ritual. There is a problem. These circles joining their power together creates a lot of excess energy. The transfer rate of orgone from one circle to the next will ultimately speed up during the ritual, turning that excess energy into heat. As the point of connection between these transmutation circles, the channeler inetivably becomes the bearer of all this heat buildup. This could be dangerous to the individual, for the link must remain open for the spell to work. This can potentially kill the channeler by cooking them from the inside. How can I prevent this from happening?	So the real key to this is doing something with the energy before it becomes the unknown wobbling mess of thermal energy that turns your witch into a pop tart. If you generate the heat, you have to get rid of it, period. The only real solution is to minimize the rate of heat generation. Consider how one can use capacitors or inductors to shape current flow. If there's too much voltage, you can bleed some of the energy into a capacitor and release it later. Because you released it back into the system, it doesn't get turned into heat. If you had used a resistor, you would have had to convert it all to heat. They make big resistors for that, but you don't need them. So your channeler never tries to fix anything by opposing it. They simply bleed some energy into themselves when there's too much in one form, and emit it back out in the other. You can be arbitrarily good at this. The other big thing you may need is a failsafe. If your channeler isn't very good, and gets in trouble during practice, it'd be nice if they didn't die. For that, I'd recommend taking a lesson from High Voltage Direct Current (HVDC) lines. HVDC lines have to have a circuit breaker, like all power lines. However, this is difficult. Normal AC power cycles at 60Hz. This means once every 0.86ms, the voltage across the circuit breaker is zero. This extinguishes any arc that may form between the electrodes and makes interrupting the current comparatively easy. Doing it in the HVDC world is harder because the [current is never interrupted](https://www.youtube.com/watch?v=LHSVKuHqyKE). [![Arcing during a disconnect](https://i.stack.imgur.com/W2RNJ.jpg)](https://i.stack.imgur.com/W2RNJ.jpg) One solution is the ["hybrid" breaker](https://new.abb.com/docs/default-source/default-document-library/hybrid-hvdc-breaker---an-innovation-breakthrough-for-reliable-hvdc-gridsnov2012finmc20121210_clean.pdf?sfvrsn=2). This approach is based on the observation that there's two kinds of breakers in the HVDC world. There's slow mechanical breakers which arc badly if opened under load, and there are fast semiconductor breakers which don't arc because they simply change the resistance of the semiconductor. However, the semiconductor breakers have a problem that they generate resistance during operation. You can't get them down to negligible resistance, so they are constantly generating heat. A mechanical breaker, when conducting, is basically a large wire. It's resistance is very low, so very little heat. The hybrid approach is to have both switches in parallel. In the normal conducting state, the mechanical switches are closed and the semiconductor switch is open. This means all of the power runs through the mechanical switches, keeping the channeler... I mean conductors cool. When a fault occurs, the system first closes the fast semiconductor switch, so that both switches are conveying current in parallel. Now the mechanical switches open. Because the semiconductor is conducting current around them, there's virtually no voltage across them, and thus they don't arc much at all. Now the semiconductor is conducting all the energy, and heating up like crazy. But it can then be switched open without an arc, and the current is fully interrupted. This mechanism brings the best of both worlds. When everything is going properly, the mechanical switches conduct the current without generating heat. When everything goes wrong, the semiconductor switch can handle the load just long enough to let the mechanical switches disengage. It strikes me that your channelers would want to be trained in some art which mirrors these hybrid switches, so they aren't cooked to death! Incidentally, my original answer was going to be relating limit of 9 mages to this idea of only doing reversible things so that you don't cook while using Ogone. In mathematics, quasigroups and loops are structures which have this reversible property. Anything which can be done in a quasigroup or a loop can be undone. This makes these actions reversible, and thus there is always a way to keep the energy flowing as magic rather than as heat. Loops are interesting structures in that they have an identity element. It's possible to be in a state where you simply don't change anything. You let it be what it is. This seems like a really useful property for spellcasting. If things are getting dicey, you really want to have the ability to pause and just let things be as they are while you girdle your loins. If you just have a quasigroup, there's no such way to just let things be. You always have to know what you are doing to be able to keep things stable. We know [how many](https://en.wikipedia.org/wiki/Quasigroup#Number_of_small_quasigroups_and_loops) quasigroups and loops there are for different sized structures. For small orders (i.e. small numbers of mages), there are very few of them, and most are full fledged loops. But as the order goes up, the numbers get messy: ``` order quasigroups loops % quasigroups that are loops ----- ----------- ----- ---------------------------- 0 1 0 0% 1 1 1 100% 2 1 1 100% 3 5 1 20% 4 35 2 5.7% 5 1,411 6 0.42% 6 1,130,531 109 0.0096% 7 12,198,455,835 23,746 0.000194% 8 2.69e15 106,228,849 0.00000039% 9 ≈1.52e22 9,365,022,303,540 0.0000000061% 10 ≈2.75e30 ≈2.08e19 0.000000000076% 11 ≈1.94e40 ≈1.476e27 0.000000000000000000000000000000000075% ``` This could be a part of why the circle tops out at 9 mages. If something goes wrong, the casters in the circle need to operate in a reversible way to make sure they don't turn into crispy critters. If something goes wrong, and you have to regain control, you'll regain control into one of these patterns. 9 elements is already a gargantuan number of possibilities. If you can't rely on everyone to agree on a particular pattern when they get spooked by the Orgone getting loose, you have to rely on taming the beast after the pattern has been decided. There's just too many 10 element patterns. Worse, most of them aren't loops, meaning you have a very high risk of a pattern emerging that is merely a quasigroup, meaning you can't slow the casting down. It's gotten out of control. Maybe its just my love of mathematical flavor, but I found it interesting that this sort of pattern crops up.
135,637	<p>In this story I am writing, I am trying to figure out a place for a giant race in a military for a galaxy-spanning civilization. We'll call them Meat Boys, for joke sake and namesake.</p> <pre><code>Please bear with me, I don't have a picture. Hopefully, you guys know anatomy </code></pre> <p>Meat Boys are varying heights, from 10 to 20 feet and horned. They have large heads to accompany their human-sized brain along with their horns, which are positioned anterior to the head, superior to the two eyes. They have no nose, a mouth with 28 teeth and a short tongue. Their nostrils are positioned at the base of their horns, facing downward to the ground.</p> <p>Their ears are positioned depending on hereditary conditions. If they have ram shaped horns, they are positioned behind the horns and are much larger than normal. If they have giraffe like horns, their nostrils are positions at the back of their heads, the ears will face anterior to the body. This is so their breathing doesn't hit their ears and make noise. Like facing the wind makes that weird noise, because the air hits our ears.</p> <p>Now they have human shaped hands, with the difference of lacking a pinky finger, with an additional thumb replacing it. Lastly, their legs are like ours as well, but they walk on their four padded toes. It's much more comfortable because they were literally born to do so. </p> <p>They have superb eye-sight and hearing to make up for their terrible sense of smell. They won't know it stinks till they put it in their mouth. They aren't stupid and their intelligence ranges much like ours. From geniuses to tide pod eaters.</p> <p>Now that's out of the way, we can get toward the meat of why I asked my question in the first place.</p> <pre><code>what is their purpose in a multi-racial military? </code></pre> <p>This civilization spans across the galaxy, and the conflicts they face are many. Worlds succumbing to a rebellion, the breakdown of government planetary governments, greedy pirates, and the worst-case scenario that could happen extra-galactic invaders that we'll call Anomalies.</p> <p>Anomalies are an invasion force that ranges from small dog-sized creatures to giant hundred feet tall monsters. They do have spacecraft and engage in space battles, but their ground force rarely portrays vehicles. They rarely attack, but when they do, dozens of systems fall.</p> <p>Besides that, what purpose would Meat Boys serve? And I mean any job in the military from logistics to actual combat duty.</p> <p>EDIT: Okay, how would they be most useful?</p> <p>Edit to answer comments: </p> <p>There are humans, Elves, Draconians, Greyarchs, Angelics, Demonics, Sapienoids, Halonoids, and Otherlans. All species can withstand G's humans can withstand. Macroids (I figured out the name for the Meat Boys)can withstand less G's, but this is due to technology that can mitigate the massive inertia of spacecraft and aircraft.</p> <ul> <li>Elves have less endurance than humans but have better reflexes, speed, and strength.</li> <li>Draconians are resistant to heat and are tough. If a human soldier punched one, they would break their knuckles. Appropriate armor makes them resilient.</li> <li>Greyarchs are much stronger than humans, the strongest can rip humans limb from limb.</li> <li>Angelics are named because of their appearance, which is beautiful and literally otherworldly. Human-like, but feather along the back of the ear and sometimes down the neck. They also have excellent vision and are fast.</li> <li>Demonics on the other hand, are horned along with feathers Angelics display. They are fast as well. Grouping them together wouldn't make sense, because they are actually completely different because of their environments.</li> </ul> <p>-Sapienoids can shock people through touch, up to fatal levels. They are basically machines, but they function like living organisms. I think the term is synthezoid? But they reproduce and have the lifespan of two hundred years.</p> <ul> <li>Halonoids are human like but they contain devastating magic. They can disintegrate us, weak humans, if we make them too angry and if we're unarmored.</li> <li>Otherlans are one of the human-like races as well, but they exhibit no pupils. They are telepahtic though... and creepy.</li> </ul> <p>Now Macroids were space-faring, but they were on the level of us now. They were also originally at war with another dominant race on their planet, Macrins. Macrins were an offshoot that sacrificed some of their brain power for more strength and size. Those ones are extinct now.</p> <p>Macroids were actually winning, which is why Humans, the first ones to encounter Macroids, helped them. This allowed sharing of knowledge, but otherwise, the smaller Macroids traveled with humans. Bigger Macroid ships were adapted to long-term travel as well because of their own curiosity. Since Macroid tactics were considered inferior to human tactics, Macroids just did what humans told them, commonly stay back and let us do the work because these were scientists not soldiers most of the time.</p> <p>So with tactics phased out, Macroids didn't have a place except holding a desperate defense and being basically a record keeper for their kind back home.</p> <pre><code>TECHNOLOGY </code></pre> <p>FTL travel is available due to multiple gate ports that allow for travel from one arm of the galaxy to another within several hours. Humans have stuck to guns because of reliability vs. energy weapons, but their starships weapons have them because of their versatility in space and in an atmosphere as well. The form of energy weapons is lasers.</p> <p>Personal shields are for ships, vehicles, and infantry. Infantry, however, must utilize a less efficient version that's large and bulky, so they usually don't use it. Medicine is pretty advanced, scanning tech is used to detect objects in the body that would be hard to spot, like plastic. (Plastic shrapnel)</p> <p>Body armor will protect from indirect projectile hits and even shrapnel in some cases, but you're a goner against energy based weapons.</p> <pre><code>ANOMALIES </code></pre> <p>Anomalies cause systems to fall because they kill, eat the dead, meat, and take any resources they can like metals, semiconductors, and prebuilt materials as well. They'll ignite atmospheres of planets or send them into disastrous circumstances so they can't be colonized again. If they see a desired strategic point, they'll commit genocide against the whole planet's dominant species and just occupy the planet then. Their goal is to wipe out any species that doesn't belong to them, eat whatever is left, and move on. They really defy understanding we have, and they shouldn't exist biologically which is why they are Anomalies.</p> <p>They are stopped by the civilization because they usually destroy a majority of them as they enter the galaxy, but even the small number that survives will wait somewhere and supplement another attack somehow. There are only 10 to 20 years between each attack, though the gap is sometimes longer.</p> <pre><code>THERE IS MAGIC </code></pre> <p>While there is magic, magic is allocated to a science role as the magic community understands that magic is just something not understood yet. When magic is used for combat, it's usually because it's a bad situation that requires extreme power, because a mages talent can't be squandered if he or she is killed. It is used to devastating effect though.</p> <p>So how would Macroids fit into a military role?</p>	[ { "answer_id": 135639, "author": "Trevor", "author_id": 53721, "author_profile": "https://worldbuilding.stackexchange.com/users/53721", "pm_score": 2, "selected": false, "text": "<p>No, the weight of the snow falling at the speed of gravity (optimistically) would produce less energy then...	2019/01/05	[ "https://worldbuilding.stackexchange.com/questions/135637", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/48168/" ]	In this story I am writing, I am trying to figure out a place for a giant race in a military for a galaxy-spanning civilization. We'll call them Meat Boys, for joke sake and namesake. ``` Please bear with me, I don't have a picture. Hopefully, you guys know anatomy ``` Meat Boys are varying heights, from 10 to 20 feet and horned. They have large heads to accompany their human-sized brain along with their horns, which are positioned anterior to the head, superior to the two eyes. They have no nose, a mouth with 28 teeth and a short tongue. Their nostrils are positioned at the base of their horns, facing downward to the ground. Their ears are positioned depending on hereditary conditions. If they have ram shaped horns, they are positioned behind the horns and are much larger than normal. If they have giraffe like horns, their nostrils are positions at the back of their heads, the ears will face anterior to the body. This is so their breathing doesn't hit their ears and make noise. Like facing the wind makes that weird noise, because the air hits our ears. Now they have human shaped hands, with the difference of lacking a pinky finger, with an additional thumb replacing it. Lastly, their legs are like ours as well, but they walk on their four padded toes. It's much more comfortable because they were literally born to do so. They have superb eye-sight and hearing to make up for their terrible sense of smell. They won't know it stinks till they put it in their mouth. They aren't stupid and their intelligence ranges much like ours. From geniuses to tide pod eaters. Now that's out of the way, we can get toward the meat of why I asked my question in the first place. ``` what is their purpose in a multi-racial military? ``` This civilization spans across the galaxy, and the conflicts they face are many. Worlds succumbing to a rebellion, the breakdown of government planetary governments, greedy pirates, and the worst-case scenario that could happen extra-galactic invaders that we'll call Anomalies. Anomalies are an invasion force that ranges from small dog-sized creatures to giant hundred feet tall monsters. They do have spacecraft and engage in space battles, but their ground force rarely portrays vehicles. They rarely attack, but when they do, dozens of systems fall. Besides that, what purpose would Meat Boys serve? And I mean any job in the military from logistics to actual combat duty. EDIT: Okay, how would they be most useful? Edit to answer comments: There are humans, Elves, Draconians, Greyarchs, Angelics, Demonics, Sapienoids, Halonoids, and Otherlans. All species can withstand G's humans can withstand. Macroids (I figured out the name for the Meat Boys)can withstand less G's, but this is due to technology that can mitigate the massive inertia of spacecraft and aircraft. * Elves have less endurance than humans but have better reflexes, speed, and strength. * Draconians are resistant to heat and are tough. If a human soldier punched one, they would break their knuckles. Appropriate armor makes them resilient. * Greyarchs are much stronger than humans, the strongest can rip humans limb from limb. * Angelics are named because of their appearance, which is beautiful and literally otherworldly. Human-like, but feather along the back of the ear and sometimes down the neck. They also have excellent vision and are fast. * Demonics on the other hand, are horned along with feathers Angelics display. They are fast as well. Grouping them together wouldn't make sense, because they are actually completely different because of their environments. -Sapienoids can shock people through touch, up to fatal levels. They are basically machines, but they function like living organisms. I think the term is synthezoid? But they reproduce and have the lifespan of two hundred years. * Halonoids are human like but they contain devastating magic. They can disintegrate us, weak humans, if we make them too angry and if we're unarmored. * Otherlans are one of the human-like races as well, but they exhibit no pupils. They are telepahtic though... and creepy. Now Macroids were space-faring, but they were on the level of us now. They were also originally at war with another dominant race on their planet, Macrins. Macrins were an offshoot that sacrificed some of their brain power for more strength and size. Those ones are extinct now. Macroids were actually winning, which is why Humans, the first ones to encounter Macroids, helped them. This allowed sharing of knowledge, but otherwise, the smaller Macroids traveled with humans. Bigger Macroid ships were adapted to long-term travel as well because of their own curiosity. Since Macroid tactics were considered inferior to human tactics, Macroids just did what humans told them, commonly stay back and let us do the work because these were scientists not soldiers most of the time. So with tactics phased out, Macroids didn't have a place except holding a desperate defense and being basically a record keeper for their kind back home. ``` TECHNOLOGY ``` FTL travel is available due to multiple gate ports that allow for travel from one arm of the galaxy to another within several hours. Humans have stuck to guns because of reliability vs. energy weapons, but their starships weapons have them because of their versatility in space and in an atmosphere as well. The form of energy weapons is lasers. Personal shields are for ships, vehicles, and infantry. Infantry, however, must utilize a less efficient version that's large and bulky, so they usually don't use it. Medicine is pretty advanced, scanning tech is used to detect objects in the body that would be hard to spot, like plastic. (Plastic shrapnel) Body armor will protect from indirect projectile hits and even shrapnel in some cases, but you're a goner against energy based weapons. ``` ANOMALIES ``` Anomalies cause systems to fall because they kill, eat the dead, meat, and take any resources they can like metals, semiconductors, and prebuilt materials as well. They'll ignite atmospheres of planets or send them into disastrous circumstances so they can't be colonized again. If they see a desired strategic point, they'll commit genocide against the whole planet's dominant species and just occupy the planet then. Their goal is to wipe out any species that doesn't belong to them, eat whatever is left, and move on. They really defy understanding we have, and they shouldn't exist biologically which is why they are Anomalies. They are stopped by the civilization because they usually destroy a majority of them as they enter the galaxy, but even the small number that survives will wait somewhere and supplement another attack somehow. There are only 10 to 20 years between each attack, though the gap is sometimes longer. ``` THERE IS MAGIC ``` While there is magic, magic is allocated to a science role as the magic community understands that magic is just something not understood yet. When magic is used for combat, it's usually because it's a bad situation that requires extreme power, because a mages talent can't be squandered if he or she is killed. It is used to devastating effect though. So how would Macroids fit into a military role?	it'd work about as well as using a funnel (or bucket) to catch rain to run a mini hydroelectric plant. in other words, not very well at all. wind is probably a much better source, during antarctic emergencies it's usually very windy. if there's no wind then a conventiopnal generator is the easiest to fuel and run. people power uses very bulky fuel at very low efficiency. maybe the movement of a glacier could be harnessed, but their speed is, well, glacial, so some really steep gear ratio would be needed.
137,304	<p>I am a <a href="https://en.wikipedia.org/wiki/Traveller_(role-playing_game)" rel="noreferrer">Traveller (game)</a> referee. I've generated lots of worlds before, using a basic system that describes a world in eight fundamental pieces of data. For the record, those data are:</p> <blockquote> <p>Starport class, from "none" to first-rate, primarily and specifically to note the world's willingness to trade.</p> <p>World Size, from asteroid up to super-Jovian.</p> <p>World Atmosphere, which includes pressure, human breathable-ity, and the presence of corrosives, plus some edge cases.</p> <p>World Hydrographics, a percentage. Doesn't necessarily mean water (that depends on the atmospheric code).</p> <p>World Population, as an exponent of ten.</p> <p>World Government, from "no government" up to severe police state.</p> <p>World Law Level, basically how annoying the authorities are to you.</p> <p>Tech Level, from neolithic to fantastic-future tech.</p> </blockquote> <p>But many times, similar world types keep showing up. Water worlds, or vacuum worlds, or worlds with an industrial taint. This is a feature, not a bug, and yet I wonder if just a little bit of simplification can remove a lot of data.</p> <p>Consider Star Trek's "Class M Planet". One letter is doing a lot of work: it describes general size and life, as well as a breathable atmosphere. A very compact notation indeed!</p> <p>So. Is there a list of 26 (or so) single-letter basic "planet types" that's <strong>useful</strong> for describing worlds? I'm looking for something that holds data useful to casual readers or gamers, so I guess I'm thinking about it in the "Star Trek" fashion, but maybe there's an angle I haven't thought of.</p> <p>To be more explicit, when we get together to play Traveller, we're interested in things like whether this world is a miserable asteroid, or something larger, up to super-earth sized perhaps (i.e. can I walk on this world?); is there air, if the air is breathable (or, perhaps, how long it takes before suffering ill effects), whether there's accessible water, how much of the world is wilderness (or, perhaps, how many people live there), if there's a world government, if the locals are primitive or tech-savvy, and so on.</p> <p><strong>Update</strong></p> <p>FYI, Wikipedia lists Star Trek's codes, which generally seem to fall into these buckets:</p> <pre><code> A,B,C: Small, uninhabitable worlds. D: Large planetoids. E,F,G: Earth-sized but less habitable. Perhaps younger. H: Desert worlds. T,S,I,J: Gas giants, largest to smallest I guess. K: Earth-sized but uninhabitable. L: Earth-sized with a marginally breathable atmosphere. M: Terran norm. N,X,Y,Z: Hell-worlds. Insidious or corrosive atmospheres, high temps. O: Water world. P: Tundric water world. Q: Elliptical atmosphere or other strangeness. R: Rogue world (a wanderer; it does not orbit a star). </code></pre> <p>I like certain elements of the list: habitability is there, as well as sensory tropes such as water worlds and desert worlds; there's room for oddballs such as the Rogue world; and planet size is treated well enough.</p> <p><strong>The Planetary Classification List</strong></p> <p>This website (<a href="https://orionsarm.com/eg-article/491c78b89879b" rel="noreferrer">https://orionsarm.com/eg-article/491c78b89879b</a>) lists planet types by name... and has a bunch; it could be whittled back.</p> <p><strong>Rob's Musings</strong></p> <p>Let's say orbital location is separate, thereby subsuming molten and ice and rogue worlds. Add in a couple types to describe technic societies and we may have something... but it's hard to combine environment + technology into less than 5 bits! Lossy!</p> <pre><code>A Metal-poor (no atmosphere) (Luna) B Metal (Iron)-rich (Mercury) (no life) C Greenhouse world (Venus) (no life) D Carbon world (CO or methane, tar lakes; primitive life at best) E-K Unassigned L Sulfuric world M Meso Sulfuric world N Technic Sulfuric world O Ammonia world P Meso ammonia world Q Technic ammonia world R Chlorine world S Meso Chlorine world T Technic Chlorine world U Smallworld (Mars) (NOTE: includes "early" Mars!) V Meso smallworld W Technic smallworld X Gaian (primitive life) (NOTE: includes waterworlds and desert worlds!) Y Meso Gaian Z Technic Gaian NOTE: Meso: sophonts without space travel NOTE: Technic: sophonts with space travel </code></pre> <p><strong>ALTERNATELY</strong>, the code could focus on things other than sophont status.</p> <p>@Mathaddict noted: "The classification should really be differentiated into what equipment they will need in order to land/survive/etc." That's a good angle, with things such as breathing-protection, skin-protection, eye-protection, and mobility.</p>	[ { "answer_id": 137306, "author": "Sava", "author_id": 55317, "author_profile": "https://worldbuilding.stackexchange.com/users/55317", "pm_score": 4, "selected": false, "text": "<p>As far as I know, that kind of list is only found in Star Trek EU works, specifically the Star Charts, which...	2019/01/21	[ "https://worldbuilding.stackexchange.com/questions/137304", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/60499/" ]	I am a [Traveller (game)](https://en.wikipedia.org/wiki/Traveller_(role-playing_game)) referee. I've generated lots of worlds before, using a basic system that describes a world in eight fundamental pieces of data. For the record, those data are: > > Starport class, from "none" to first-rate, primarily and specifically to note the world's willingness to trade. > > > World Size, from asteroid up to super-Jovian. > > > World Atmosphere, which includes pressure, human breathable-ity, and the presence of corrosives, plus some edge cases. > > > World Hydrographics, a percentage. Doesn't necessarily mean water (that depends on the atmospheric code). > > > World Population, as an exponent of ten. > > > World Government, from "no government" up to severe police state. > > > World Law Level, basically how annoying the authorities are to you. > > > Tech Level, from neolithic to fantastic-future tech. > > > But many times, similar world types keep showing up. Water worlds, or vacuum worlds, or worlds with an industrial taint. This is a feature, not a bug, and yet I wonder if just a little bit of simplification can remove a lot of data. Consider Star Trek's "Class M Planet". One letter is doing a lot of work: it describes general size and life, as well as a breathable atmosphere. A very compact notation indeed! So. Is there a list of 26 (or so) single-letter basic "planet types" that's useful for describing worlds? I'm looking for something that holds data useful to casual readers or gamers, so I guess I'm thinking about it in the "Star Trek" fashion, but maybe there's an angle I haven't thought of. To be more explicit, when we get together to play Traveller, we're interested in things like whether this world is a miserable asteroid, or something larger, up to super-earth sized perhaps (i.e. can I walk on this world?); is there air, if the air is breathable (or, perhaps, how long it takes before suffering ill effects), whether there's accessible water, how much of the world is wilderness (or, perhaps, how many people live there), if there's a world government, if the locals are primitive or tech-savvy, and so on. Update FYI, Wikipedia lists Star Trek's codes, which generally seem to fall into these buckets: ``` A,B,C: Small, uninhabitable worlds. D: Large planetoids. E,F,G: Earth-sized but less habitable. Perhaps younger. H: Desert worlds. T,S,I,J: Gas giants, largest to smallest I guess. K: Earth-sized but uninhabitable. L: Earth-sized with a marginally breathable atmosphere. M: Terran norm. N,X,Y,Z: Hell-worlds. Insidious or corrosive atmospheres, high temps. O: Water world. P: Tundric water world. Q: Elliptical atmosphere or other strangeness. R: Rogue world (a wanderer; it does not orbit a star). ``` I like certain elements of the list: habitability is there, as well as sensory tropes such as water worlds and desert worlds; there's room for oddballs such as the Rogue world; and planet size is treated well enough. The Planetary Classification List This website (<https://orionsarm.com/eg-article/491c78b89879b>) lists planet types by name... and has a bunch; it could be whittled back. Rob's Musings Let's say orbital location is separate, thereby subsuming molten and ice and rogue worlds. Add in a couple types to describe technic societies and we may have something... but it's hard to combine environment + technology into less than 5 bits! Lossy! ``` A Metal-poor (no atmosphere) (Luna) B Metal (Iron)-rich (Mercury) (no life) C Greenhouse world (Venus) (no life) D Carbon world (CO or methane, tar lakes; primitive life at best) E-K Unassigned L Sulfuric world M Meso Sulfuric world N Technic Sulfuric world O Ammonia world P Meso ammonia world Q Technic ammonia world R Chlorine world S Meso Chlorine world T Technic Chlorine world U Smallworld (Mars) (NOTE: includes "early" Mars!) V Meso smallworld W Technic smallworld X Gaian (primitive life) (NOTE: includes waterworlds and desert worlds!) Y Meso Gaian Z Technic Gaian NOTE: Meso: sophonts without space travel NOTE: Technic: sophonts with space travel ``` ALTERNATELY, the code could focus on things other than sophont status. @Mathaddict noted: "The classification should really be differentiated into what equipment they will need in order to land/survive/etc." That's a good angle, with things such as breathing-protection, skin-protection, eye-protection, and mobility.	Of course we can make this code up. The question is, how useful it would be. As @Renan pointed out, possible permutations of planet types number in thousands - and that's not even counting potential life and civilization on the planet. Coming up with single code for every type is impossible. But if we want just a classification, then yes, we can come up with 26 types that would group together similar planets. The only challenge is to make these groups practical. I would suggest to use frequency of mention to guide this classification. This way, if two very similar world types (like "clean" and "tainted" Earth-like planets with civilization) are mentioned very frequently, they deserve their own letters. On the other hand, planetoids without atmosphere could be much more numerous and diverse, but because they mentioned less frequently, they may be all compressed into one letter designation. This one-letter code would not eliminate the need for proper, multi-symbol classification that should reflect all major aspects of planetary conditions.
138,926	<p>An asteroid collision big enough and fast enough to see a massive ejection of rock and moon-chunks, from the surface of the earth <strong>AND not wipe out the population of the planet.</strong></p> <p>What size and speed of asteroid would it take to have a <em>majorly</em> visible and spectacular impact on the moon? </p> <p>What after effects would this have? What would the moon look like? Would there be any minor effects in the earth? </p>	[ { "answer_id": 138928, "author": "jdunlop", "author_id": 36850, "author_profile": "https://worldbuilding.stackexchange.com/users/36850", "pm_score": 3, "selected": false, "text": "<p>Something the size of the <a href=\"https://en.wikipedia.org/wiki/Chicxulub_impactor\" rel=\"nofollow nor...	2019/02/11	[ "https://worldbuilding.stackexchange.com/questions/138926", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/61318/" ]	An asteroid collision big enough and fast enough to see a massive ejection of rock and moon-chunks, from the surface of the earth AND not wipe out the population of the planet. What size and speed of asteroid would it take to have a majorly visible and spectacular impact on the moon? What after effects would this have? What would the moon look like? Would there be any minor effects in the earth?	Something the size of the [Chicxulub impactor](https://en.wikipedia.org/wiki/Chicxulub_impactor) would be plenty spectacular - the top range of its [impact energy](https://arxiv.org/abs/1403.6391) is fifty thousand gigatons of TNT equivalent. There wouldn't be an equivalent explosion in all of human existence. The major problem is that in order to save humanity from an impact, by definition any impactor would have to hit the far side of the moon. The ejecta would be visible, as would the motion of the moon itself, but not the moment of impact. Any impact sufficient to be visible on the near side - ie. force projected through the entire moon, possibly destroying it - will give you the same problem experienced by the human race in Neal Stephenson's Seveneves: a [hard rain](https://youtu.be/fQfgWQZa0Ow). --- For added fun, I adapted a python script I found [here](https://astronomy.stackexchange.com/questions/7806/exercise-2d-orbital-mechanics-simulation-python): ``` import matplotlib.pyplot as plt import math plt.ion() G = 6.673e-11 # gravitational constant gridArea = [-20, 50, -20, 50] # margins of the coordinate grid gridScale = 10000000 # 1 unit of grid equals 10000000m or 10000km plt.clf() # clear plot area plt.axis(gridArea) # create new coordinate grid plt.grid(b="on") # place grid class Object: _instances = [] def __init__(self, name, position, radius, mass): self.name = name self.position = position self.radius = radius # in grid values self.mass = mass self.placeObject() self.velocity = 0 Object._instances.append(self) def placeObject(self): drawObject = plt.Circle(self.position, radius=self.radius, fill=False, color="black") plt.gca().add_patch(drawObject) plt.show() def giveMotion(self, deltaV, motionDirection, time): if self.velocity != 0: x_comp = math.sin(math.radians(self.motionDirection))self.velocity y_comp = math.cos(math.radians(self.motionDirection))self.velocity x_comp += math.sin(math.radians(motionDirection))deltaV y_comp += math.cos(math.radians(motionDirection))deltaV self.velocity = math.sqrt((x_comp2)+(y_comp2)) if x_comp > 0 and y_comp > 0: # calculate degrees depending on the coordinate quadrant self.motionDirection = math.degrees(math.asin(abs(x_comp)/self.velocity)) # update motion direction elif x_comp > 0 and y_comp < 0: self.motionDirection = math.degrees(math.asin(abs(y_comp)/self.velocity)) + 90 elif x_comp < 0 and y_comp < 0: self.motionDirection = math.degrees(math.asin(abs(x_comp)/self.velocity)) + 180 else: self.motionDirection = math.degrees(math.asin(abs(y_comp)/self.velocity)) + 270 else: self.velocity = self.velocity + deltaV # in m/s self.motionDirection = motionDirection # degrees self.time = time # in seconds self.vectorUpdate() def vectorUpdate(self): self.placeObject() data = [] for t in range(self.time): motionForce = self.mass * self.velocity # F = m * v x_net = 0 y_net = 0 for x in [y for y in Object._instances if y is not self]: distance = math.sqrt(((self.position[0]-x.position[0])2) + (self.position[1]-x.position[1])2) gravityForce = G(self.mass x.mass)/((distancegridScale)2) x_pos = self.position[0] - x.position[0] y_pos = self.position[1] - x.position[1] if x_pos <= 0 and y_pos > 0: # calculate degrees depending on the coordinate quadrant gravityDirection = math.degrees(math.asin(abs(y_pos)/distance))+90 elif x_pos > 0 and y_pos >= 0: gravityDirection = math.degrees(math.asin(abs(x_pos)/distance))+180 elif x_pos >= 0 and y_pos < 0: gravityDirection = math.degrees(math.asin(abs(y_pos)/distance))+270 else: gravityDirection = math.degrees(math.asin(abs(x_pos)/distance)) x_gF = gravityForce math.sin(math.radians(gravityDirection)) # x component of vector y_gF = gravityForce * math.cos(math.radians(gravityDirection)) # y component of vector x_net += x_gF y_net += y_gF x_mF = motionForce * math.sin(math.radians(self.motionDirection)) y_mF = motionForce * math.cos(math.radians(self.motionDirection)) x_net += x_mF y_net += y_mF netForce = math.sqrt((x_net2)+(y_net2)) if x_net > 0 and y_net > 0: # calculate degrees depending on the coordinate quadrant self.motionDirection = math.degrees(math.asin(abs(x_net)/netForce)) # update motion direction elif x_net > 0 and y_net < 0: self.motionDirection = math.degrees(math.asin(abs(y_net)/netForce)) + 90 elif x_net < 0 and y_net < 0: self.motionDirection = math.degrees(math.asin(abs(x_net)/netForce)) + 180 else: self.motionDirection = math.degrees(math.asin(abs(y_net)/netForce)) + 270 self.velocity = netForce/self.mass # update velocity traveled = self.velocity/gridScale # grid distance traveled per 1 sec self.position = (self.position[0] + math.sin(math.radians(self.motionDirection))traveled, self.position[1] + math.cos(math.radians(self.motionDirection))traveled) # update pos data.append([self.position[0], self.position[1]]) collision = 0 for x in [y for y in Object._instances if y is not self]: if (self.position[0] - x.position[0])2 + (self.position[1] - x.position[1])2 <= x.radius**2: collision = 1 impactor = self.name impactee = x.name velocity = self.velocity break if collision != 0: print("Collision! %s struck %s at %d m/s" % (impactor, impactee, velocity)) break plt.plot([x[0] for x in data], [x[1] for x in data]) Earth = Object(name="Earth", position=(0.0, 25.0), radius=0.6371, mass=5.972e24) Moon = Object(name="Moon", position=(38.45, 25.0), radius=0.1737, mass = 7.347e22) # The orbital distance of the moon is ~ 384.5 thousand km. Hammer = Object(name="Hammer", position=(38.80, 25.20), radius=0.0001, mass=1.0e10) Hammer.giveMotion(deltaV=2000.0, motionDirection=270, time=100000) plt.show(block=True) ``` The Hammer is just 10Mkg, but its mass is always going to be somewhat irrelevant.
139,620	<p>This question is about how the brain works in that aspect, if it's even known.</p> <p>I mean with the question that a person might react to something with fear, happiness, disappointment, or whatever other feeling.</p> <p>These feelings are biological but also are built around the memories about that something.</p> <p>I'm far from a brain expert, but I think that the brain somehow summarizes all of this memories, in a separate way, to give that feeling immediately.</p> <p>If that were the case then changing this memories would give scenarios sort of strange for the person, as, for example, it might feel fear about something with which everything he can recall are good memories or the opposite, with time the brain might become wired to act accordingly to its memories, but it would result in some severe confusion for the person meanwhile.</p> <p>We can consider that we have a perfect technology for creating the false memories with as much detail as desired, exchanging it for others, but we cannot still change the "summary" that the brain does (if it happens).</p> <p>According to actual knowledge about the brain, could changing these memories actually immediately change the behavior of a person?</p> <p>Not very sure if this goes here or in <a href="http://cogsci.stackexchange.com">http://cogsci.stackexchange.com</a>, but as implanting these level of false memories is, as far as I know, absolute science fiction, I'm posting here.</p> <p>I'm writing my comment here to better explain what would be the hard science part:</p> <p>The [hard-science] part is most about having a separate "zone" for the response that "summarized" memories in form of feelings produce, and the memories themselves, I don't think it's that far fetched that studies have been able to determine that nowadays, the implanting of memories is less important, for that the thing to check would be that someone who were to get the opposite feelings, if both feelings and memories cannot exist in a separate manner, with brains being of equal "functionality", would prove that implanting memories would cause that associated feelings to change. </p> <p>With the last thing I want to mean that, for example, between twin brothers, if one of them had experiences that made to develop the opposite feeling about something, I think that would prove that, as the brain has the same functionality, it would make that feelings to change. And, in general, a brain, unless there's some abnormality, is not to work too different in any random person in this aspect (in how it would process them, due to its own working, if those were the memories instead of others), I guess.</p> <p>Even if restricting it to this wouldn't be enough, I'd like to reopen without the hard-science tag.</p>	[ { "answer_id": 139623, "author": "lilHar", "author_id": 17031, "author_profile": "https://worldbuilding.stackexchange.com/users/17031", "pm_score": -1, "selected": false, "text": "<p>80% of memories are eventually forgotten. (As per forgetting Curves which follow Zipfy progressions, also...	2019/02/20	[ "https://worldbuilding.stackexchange.com/questions/139620", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/11763/" ]	This question is about how the brain works in that aspect, if it's even known. I mean with the question that a person might react to something with fear, happiness, disappointment, or whatever other feeling. These feelings are biological but also are built around the memories about that something. I'm far from a brain expert, but I think that the brain somehow summarizes all of this memories, in a separate way, to give that feeling immediately. If that were the case then changing this memories would give scenarios sort of strange for the person, as, for example, it might feel fear about something with which everything he can recall are good memories or the opposite, with time the brain might become wired to act accordingly to its memories, but it would result in some severe confusion for the person meanwhile. We can consider that we have a perfect technology for creating the false memories with as much detail as desired, exchanging it for others, but we cannot still change the "summary" that the brain does (if it happens). According to actual knowledge about the brain, could changing these memories actually immediately change the behavior of a person? Not very sure if this goes here or in <http://cogsci.stackexchange.com>, but as implanting these level of false memories is, as far as I know, absolute science fiction, I'm posting here. I'm writing my comment here to better explain what would be the hard science part: The [hard-science] part is most about having a separate "zone" for the response that "summarized" memories in form of feelings produce, and the memories themselves, I don't think it's that far fetched that studies have been able to determine that nowadays, the implanting of memories is less important, for that the thing to check would be that someone who were to get the opposite feelings, if both feelings and memories cannot exist in a separate manner, with brains being of equal "functionality", would prove that implanting memories would cause that associated feelings to change. With the last thing I want to mean that, for example, between twin brothers, if one of them had experiences that made to develop the opposite feeling about something, I think that would prove that, as the brain has the same functionality, it would make that feelings to change. And, in general, a brain, unless there's some abnormality, is not to work too different in any random person in this aspect (in how it would process them, due to its own working, if those were the memories instead of others), I guess. Even if restricting it to this wouldn't be enough, I'd like to reopen without the hard-science tag.	The answer is "yes it is possible, but it would be unpredictable". This has a hard science tag, so this draft might need a few revisions, including references, which I will attend to as time permits. Be aware that the best hard science out there is still very speculative, just marginally better than reading tea leaves Memories are mediated by the hippocampus and mapped into other areas of the brain. For a long time, the hippocampus was believed to be the seat of long term memory, because damage or removal of the hippocampus would result in instant and irreversible amnesia. However, by adding the use of functional brain scans to what has been determined through decade of experiment and modelling, we now know there is much more to the story. Be aware the the best functional brain scan technology only has a 3 mm resolution today (2019). That is pretty coarse for a structure that is only 3 cm³ in volume, so our understanding is still very blurry. Functional brain scans show a physical mapping process occurring during both memory encoding and reconstruction. The word reconstruction is used deliberately rather than recall because the process of recall is as important as the process of encoding. ``` Sidebar ...be patient and you'll see how his fits. During execution of spatial tasks, regions of the hippocampus activate in response to achieving decision points in the task. For example, if the task is a maze, then at each decision point a different set of physical regions of the hippocampus will activate. What is very interesting is that during execution of non-spatial tasks, like solving a math problem, the hippocampus exhibits exactly the same kind of activity. ``` We have known for a long time that the hippocampus is active in long term recall. With the advent of readily available brain scan techniques, we can see that its role in long term recall is active rather than passive, and essentially identical to its activity in solving spatial problems. We also know that the hippocampus is crucial to forming new memories. When new data is first introduced to the brain, the hippocampus is recruited, and exhibits the same sort of activity that it does in solving spatial problems. In effect, the hippocampus is a spatial mapping organ that has been adapted into a general problem solving tool. Think of it as being similar to the GPU in a modern graphics card, specialized for some function, but over time has been adapted to solve a broad range of problems unrelated to its original intent. For a long time, psychologists have known about the bookend effect. People tend to remember the first time they did something, the last time they did something, but not much in between. This why the first time you drive a route it seems so much longer than subsequent times. ``` Data deduplication * often called intelligent compression or single-instance storage * is a process that eliminates redundant copies of data and reduces storage overhead. Data deduplication techniques ensure that only one unique instance of data is retained on storage media, such as disk, flash or tape ``` As near as we can tell (at this point its an educated guess backed by experiment and modelling), during memory encoding the hippocampus mediates an aggressive deduplication process. That process compartmentalizes the new memory into fragments representing the state of the brain at that point in time and builds a map of some sort (As a database person I think of it as a key) to tie the fragments back together. We do not keep detailed memories at all, only statistically reinforced probabilities (described as the sum of the activation functions for the involved neurons - I don't write that kind of math, sorry). ``` This actually introduces the specific technical issues to be resolved to "implant" false memories, and also why the results might be unpredictable no matter how good the tech is. ``` During recall, the hippocampus is recruited to find and reassemble the memory fragments into a comprehensive whole, again treating it as a spatial navigation problem. This is why human memory is so fallible. Examples of this mechanism in action: My wife often wears a blue dress to church. We get separated, so when I go looking for her and have trouble finding her because she's wearing a green dress today. The reconstructed memory has been statistically reinforced to blue as part of the deduplication and reconstruction process. "Oh, I misread that" The well known phenomenon that no two eyewitnesses of an event recall it exactly the same. Memory and Emotion From experimental and clinical studies we know that impairment of emotion processing also inhibits memory encoding It turns out that you can't really separate memory from emotion, because part of the memory encoding process includes a partial state of the amygdala. From an experiential perspective, I remember what it felt like to really enjoy a good fireworks show. After brain damage impairing emotional processing, (1) I find it difficult to encode new memories and (2) The only "feeling" i get from the same fireworks show is the sensation of the booms rattling my internal organs, kind of like indigestion. What is interesting (to me) is that recall causes the same areas of the brain to be activated as the original event (with the caveat that the encoding process is lossy) so there is little difference in the state of the brain during recall as opposed to the original event. The fact that I can recall (reconstruct) emotional states that I can no longer experience in the immediate says that there is a different mediator for recalled emotion versus immediate emotion. --- Links: * Coding of episodic memory: <https://www.pnas.org/content/115/5/1093.short> * Spatial processing: <https://www.sciencedirect.com/science/article/pii/S002839321730115X> * Spatial processing: <https://www.sciencedirect.com/science/article/abs/pii/S0304394018303331> * Reconstruction of memory: <https://www.sciencedirect.com/science/article/pii/S136466131830264X> * Hippocampus as spatial processor: <https://onlinelibrary.wiley.com/doi/abs/10.1002/hipo.22750> * Role of emotion in forming memories: <https://www.sciencedirect.com/science/article/pii/S2352154617301638> * Memory compression: <https://www.tandfonline.com/doi/abs/10.1080/09658211.2017.1406120> * Memory encoding: <https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0204685> * Memory Integration Theory: <https://www.sciencedirect.com/science/article/pii/S0301008217302174> * Application of hippocampus model in machine learning: <http://teaching-machines.cc/nips2017/papers/nips17-teaching_paper-13.pdf>
141,986	<p>So I'm doing some worldbuilding for a small, isolated village on the coast. The winters are harsh, but making sure everybody has enough food generally isn't an issue because they have good trade with an outside source, and they are community-led so they make sure nobody gets left out in the cold (literally or metaphorically). New people will join the town every now and again, but not often enough to really impact the population. </p> <p>I think the population is small - maybe two hundred people - and the average person reaches about 65-70. So my question is, how many kids have to be born to sustain this in a zero population growth model? </p> <p>I had the idea that the town tries to synchronise births so that every child has friends their own age to play with and learn from, and I thought every 8 years or so made some sense - the 8-year-olds could start learning a craft, and the 16-year-olds could teach the 8-year-olds, whilst the 24-year-olds start to couple off and have their own babies. How large would each "clutch" of babies have to be? </p> <p>I did some quick maths and got maybe 20-25, but I'm not sure how accurate this is. My reasoning was 8 (number of years)/70 (average lifespan) * 200 (population) = ~22. </p> <p>If anybody has a more solid idea I'd love to hear it! And if you think this is a really stupid idea then let me down gently please haha </p>	[ { "answer_id": 141988, "author": "AlexP", "author_id": 29552, "author_profile": "https://worldbuilding.stackexchange.com/users/29552", "pm_score": 6, "selected": true, "text": "<p>Your calculation is correct assuming that all children born live to be 70. But that is not the case even wit...	2019/03/20	[ "https://worldbuilding.stackexchange.com/questions/141986", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/62500/" ]	So I'm doing some worldbuilding for a small, isolated village on the coast. The winters are harsh, but making sure everybody has enough food generally isn't an issue because they have good trade with an outside source, and they are community-led so they make sure nobody gets left out in the cold (literally or metaphorically). New people will join the town every now and again, but not often enough to really impact the population. I think the population is small - maybe two hundred people - and the average person reaches about 65-70. So my question is, how many kids have to be born to sustain this in a zero population growth model? I had the idea that the town tries to synchronise births so that every child has friends their own age to play with and learn from, and I thought every 8 years or so made some sense - the 8-year-olds could start learning a craft, and the 16-year-olds could teach the 8-year-olds, whilst the 24-year-olds start to couple off and have their own babies. How large would each "clutch" of babies have to be? I did some quick maths and got maybe 20-25, but I'm not sure how accurate this is. My reasoning was 8 (number of years)/70 (average lifespan) \* 200 (population) = ~22. If anybody has a more solid idea I'd love to hear it! And if you think this is a really stupid idea then let me down gently please haha	Your calculation is correct assuming that all children born live to be 70. But that is not the case even with the most modern health care. So you may want to up the number of babies a bit, to account (1) for infant mortality, (2) for the tendency of young males to do stupid things which get them killed, and (3) for the general premature mortality due to diseases and accidents. Here are two tables grouping the population by age cohorts; first assuming that all babies born live to 70, and then assuming a more natural [population pyramid](https://en.wikipedia.org/wiki/Population_pyramid). ``` Age cohort ---------- 0 to 7 22 32 8 to 15 22 27 16 to 23 22 22 24 to 31 22 20 32 to 39 22 20 40 to 47 22 20 48 to 55 22 20 56 to 63 22 19 64 to 71 22 18 ---------- ---- ---- Total 198 198 ``` A random isolated village of 200 people surviving long term would be a clear sign of divine favor. * Unless the initial population was chosen extremely carefully by in-depth genetic screening there will be severe inbreeding effects after a handful of generations, raising the mortality. (Note that there are only about 40 to 44 women aged 16 to 47 at any given time.) For example, in (the pre-modern principalities which would eventually coalesce into) Romania, a significant fraction of the women (and a smaller fraction of the men) married into neighbouring villages, so that there was some exhange of genetic material. This had also the positive effect of creating wider social networks. * With such a small population the village is prone to demographic shocks. One good sized war, or one Tartar raid, or one epidemic and the population pyramid may be skewed irretrievably. Consider for example what happens if the Tartars come and abduct half of your 20 women aged 16 to 31. Or consider what happens if the [Thirty Years' War](https://en.wikipedia.org/wiki/Thirty_Years%27_War) comes and kills two thirds of your men aged 16 to 47. Grouping births into clutches every eighth year has the massive drawback that almost all women of reproductive age suddenly find themselves busy with babies at the same time. * In a real village of about 200 people, with 4 births per year, you have about 8 to 10 women out of the workforce at any given moment, for a total non-working population of about 40 souls (8 to 10 women and 30 to 32 small children), or 20%. * With this grouping, every eighth year a whopping 32 women go out of the workforce for two or three years, for a total non-working population of about 60 souls, or 30%. True, in non-fertile years the non-working population drops to around 15%, but this is a village, they cannot accumulate surpluses to be consumed later.
143,052	<p>I was watching a program about the New Horizons space probe and was fascinated by the new revelations about cryolava/cryomagma, and the <a href="https://en.wikipedia.org/wiki/Pluto#Geology" rel="nofollow noreferrer">amorphous planes covering Pluto</a>(98% nitrogen ice).</p> <p>I'm wondering how this might affect the idea of a human colony on an ice-world/cryo-world. In particular:</p> <ul> <li><p>How would you keep structures from slowly sinking into the surface of a planet completely covered by cryolava?</p> </li> <li><p>How fast would this sinking occur?</p> </li> </ul> <p>I'm assuming the habitat will need to be kept warm, and would therefore accelerate the process.</p> <p>I imagine for small habitats, this might not be a big deal, as they could be on wheels and roll along the surface, although this could scale poorly to larger settlements/cities</p> <h3>Addition</h3> <p><strong>Quick freezing point chart from wikipedia data</strong></p> <pre><code>pure freezing substance point H2O 273.2 °K CO2 216.6 °K NH3 195.5°K CH4 90.70 °K CO 68.13 °K N2 63.15 °K O2 54.4°K H2 14.0°K approx. surface temp. Pluto(for reference): 33°K - 55°K </code></pre>	[ { "answer_id": 143053, "author": "Zeiss Ikon", "author_id": 57454, "author_profile": "https://worldbuilding.stackexchange.com/users/57454", "pm_score": 3, "selected": false, "text": "<p>Amorphous means non-crystalline, not non-solid. Glass is amorphous, and it's solid enough to hold a l...	2019/04/02	[ "https://worldbuilding.stackexchange.com/questions/143052", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/-1/" ]	I was watching a program about the New Horizons space probe and was fascinated by the new revelations about cryolava/cryomagma, and the [amorphous planes covering Pluto](https://en.wikipedia.org/wiki/Pluto#Geology)(98% nitrogen ice). I'm wondering how this might affect the idea of a human colony on an ice-world/cryo-world. In particular: * How would you keep structures from slowly sinking into the surface of a planet completely covered by cryolava? * How fast would this sinking occur? I'm assuming the habitat will need to be kept warm, and would therefore accelerate the process. I imagine for small habitats, this might not be a big deal, as they could be on wheels and roll along the surface, although this could scale poorly to larger settlements/cities ### Addition Quick freezing point chart from wikipedia data ``` pure freezing substance point H2O 273.2 °K CO2 216.6 °K NH3 195.5°K CH4 90.70 °K CO 68.13 °K N2 63.15 °K O2 54.4°K H2 14.0°K approx. surface temp. Pluto(for reference): 33°K - 55°K ```	Amorphous means non-crystalline, not non-solid. Glass is amorphous, and it's solid enough to hold a load for a long time at room temperature (the myth about sagging in centuries-old stained glass windows is just that -- a myth). Likewise, amorphous ice (whether water ice, ammonia, clathrate, or even oxygen) will be solid enough not to flow or creep noticeably, so long as the temperature stays below the freezing temperature of the substance. As long as your habitats are insulated so the surface(s) contacting the amorphous ice plain are below the melting or sublimation temperature, you needn't worry about the habs sinking into the surface. If they get too warm on the bottom, it won't matter whether the material they're standing on is crystalline or amorphous, it'll still melt (and, in a vacuum, immediately flash to vapor). Sinking won't be subtle at that point, if there's enough heat reserve to boil off a lot of the supporting material.
143,417	<p>Basically what's in the title: If someone uses a spiky arm guard/bracer (long bracelet type armor not gauntlet) while bashing/battering an opponent (with or without armor) would this result in the wielder breaking their arm or bone or could they do it without harm to themself?</p> <p>The spiky arm guard/bracer in my mind is made entirely of metal, either bronze or steel, with many similar size spikes surrounding it and another like a spiky mace which has some gaps and fewer spikes also can have different size for each spike. I think maybe a leather arm guard/bracer with metallic spikes would help absorb the impact to reduce harm to the arm upon attacking, or am I wrong?</p> <p>And another with two layers with the outfacing part having spikes that are a bit loose so a straight or a hook punch can make a twirl or drill like movement to the spike that can chip off the opponent that makes contact with the arm guard.</p> <p>Some alternative suggestions for design are welcome.</p> <p>The closest example image for spiky arm guard/bracer:</p> <p><strong>With many similar size spikes surrounding it</strong></p> <p><a href="https://i.stack.imgur.com/1lO5m.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/1lO5m.jpg" alt="enter image description here"></a> <a href="https://i.stack.imgur.com/Zye7m.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Zye7m.jpg" alt="enter image description here"></a> Credits from:</p> <pre><code> metaldevastation.com rowansoriginals.com </code></pre> <p><strong>Spiky Mace Type</strong> which has some gaps and fewer spikes also can have different size for each spike, just imagine the previous arm guard/bracer above and replace the spike or the pattern with this one. <a href="https://i.stack.imgur.com/vxp38.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/vxp38.png" alt="enter image description here"></a> Credit from:</p> <pre><code> medievalcollectibles.com </code></pre>	[ { "answer_id": 143430, "author": "Liam Morris", "author_id": 62187, "author_profile": "https://worldbuilding.stackexchange.com/users/62187", "pm_score": 3, "selected": false, "text": "<h2>No, they would not.</h2>\n\n<p>There are several issues with trying to use a weapon like this. </p>\...	2019/04/07	[ "https://worldbuilding.stackexchange.com/questions/143417", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/62918/" ]	Basically what's in the title: If someone uses a spiky arm guard/bracer (long bracelet type armor not gauntlet) while bashing/battering an opponent (with or without armor) would this result in the wielder breaking their arm or bone or could they do it without harm to themself? The spiky arm guard/bracer in my mind is made entirely of metal, either bronze or steel, with many similar size spikes surrounding it and another like a spiky mace which has some gaps and fewer spikes also can have different size for each spike. I think maybe a leather arm guard/bracer with metallic spikes would help absorb the impact to reduce harm to the arm upon attacking, or am I wrong? And another with two layers with the outfacing part having spikes that are a bit loose so a straight or a hook punch can make a twirl or drill like movement to the spike that can chip off the opponent that makes contact with the arm guard. Some alternative suggestions for design are welcome. The closest example image for spiky arm guard/bracer: With many similar size spikes surrounding it [![enter image description here](https://i.stack.imgur.com/1lO5m.jpg)](https://i.stack.imgur.com/1lO5m.jpg) [![enter image description here](https://i.stack.imgur.com/Zye7m.jpg)](https://i.stack.imgur.com/Zye7m.jpg) Credits from: ``` metaldevastation.com rowansoriginals.com ``` Spiky Mace Type which has some gaps and fewer spikes also can have different size for each spike, just imagine the previous arm guard/bracer above and replace the spike or the pattern with this one. [![enter image description here](https://i.stack.imgur.com/vxp38.png)](https://i.stack.imgur.com/vxp38.png) Credit from: ``` medievalcollectibles.com ```	No, they would not. ------------------- There are several issues with trying to use a weapon like this. First, as you identified, the user may end up with broken bones. The bones in your wrist are relatively delicate as it it a joint. Putting a piece of metal on there and hitting something hard could injure you at best or break the bone. Secondly, even if you could use it without risking harm to yourself, you wouldn't want to anyway. The reason being is power generation. A weapon, such as a mace, is something known as a force multiplier. As weapons have mass, can be accelerated relatively quickly and typically have a small contact point, they amplify the force you can put behind a strike massively. However, these metal forearm spikes don’t add much more mass and are not accelerated faster than your forearm. This concentrates the force of you swinging your arm on a smaller point but does not generate additional force. Finally, these spikes would not be able to pierce through armour. Not an issue against an unarmored opponent but they would do nothing against one with some kind of protection. This is because the spikes cant be overly long or else you’ll be stabbing yourself any time you walk. Alternatives Now, if you wanted some weapons for punching, I suggest the push dagger (also called a punch dagger) or katar (the weapon, not the place). These are daggers which you hold in your hand and you punch with them as though you were boxing. The katar is the more advanced weapon of the two as it has an ‘H’ shaped guard with two bars to prevent it from twisting in your hand. If you wanted something larger, I suggest the pata, a gauntlet with a sword blade attached. The pata is similar to a rapier, mostly a thrusting weapon but you can do cuts with it as well. Finally, of you were dead-set on having a spiked forearm weapon, I suggest you look at the bagh nakh, also called the tiger claw. As its name implies, this is a weapon with blades that curl backwards. This was meant as a tool for climbing trees but it doubles as a weapon, it is held in the palm of the hand. You could have spikes like the bagh nakh does on your arm guard which overcomes some issues I mentioned earlier as a blade does not need much force to deal a lot of damage.
144,029	<p>I was unfortunate enough to imagine an ancient setting upside down. I started out with small features and, after connecting them, got the following:</p> <pre><code> cold ^ \| sunrise <---+---> sunset \| v hot </code></pre> <p>Which basically means that we are located in the southern hemisphere.</p> <p>How do I explain this to a reader/player/watcher with as little disruption as possible (aka <a href="https://en.wikipedia.org/wiki/Principle_of_least_astonishment" rel="nofollow noreferrer">principle of least astonishment</a>)?</p> <ul> <li>Keep telling that south=cold, north=hot;</li> <li>Keep telling that south and north are swapped;</li> <li>Rename south/north directions to e.g. midday/midnight;</li> <li>Mirror-image the whole world to make it in line with Middle-Earth/Earthsea/Westeros/whatever fantasy setting humanity invented? </li> </ul> <p>Also if I ever draw a map, should I swap East <-> West ("mirror image") or should I swap South<->North ("Argentina")? </p> <p>The former makes more sense as the inhabitants tend to live on hills/mountains, so "cold=up" makes sense to them. However, a plausible post factum explanation may be found for any <a href="http://mentalfloss.com/article/58426/why-north-always-maps" rel="nofollow noreferrer">map orientation</a>. </p>	[ { "answer_id": 144036, "author": "Klaus Æ. Mogensen", "author_id": 62769, "author_profile": "https://worldbuilding.stackexchange.com/users/62769", "pm_score": 4, "selected": true, "text": "<p>You could simply write that the sun rises in the east and sets in the west, but is due north at ...	2019/04/15	[ "https://worldbuilding.stackexchange.com/questions/144029", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/14919/" ]	I was unfortunate enough to imagine an ancient setting upside down. I started out with small features and, after connecting them, got the following: ``` cold ^ \| sunrise <---+---> sunset \| v hot ``` Which basically means that we are located in the southern hemisphere. How do I explain this to a reader/player/watcher with as little disruption as possible (aka [principle of least astonishment](https://en.wikipedia.org/wiki/Principle_of_least_astonishment))? * Keep telling that south=cold, north=hot; * Keep telling that south and north are swapped; * Rename south/north directions to e.g. midday/midnight; * Mirror-image the whole world to make it in line with Middle-Earth/Earthsea/Westeros/whatever fantasy setting humanity invented? Also if I ever draw a map, should I swap East <-> West ("mirror image") or should I swap South<->North ("Argentina")? The former makes more sense as the inhabitants tend to live on hills/mountains, so "cold=up" makes sense to them. However, a plausible post factum explanation may be found for any [map orientation](http://mentalfloss.com/article/58426/why-north-always-maps).	You could simply write that the sun rises in the east and sets in the west, but is due north at noon (not necessarily in the same sentence). Since the people in the world aren't likely to speak English, "east", "west", "north", and "south" will be translations of local words, and it then makes sense to translate them to Earth standards. It makes absolutely no sense to swap east and west on a map unless you also swap north and south, basically turning the map 180 degrees (as with some early maps). If you only swap one axis, it would be very difficult to use the map, since it wouldn't correspond very well with the real world (try making a mirror image of the map of you local city and navigate with that). Turning is fine, however, and you don't even need to make the map corners align with the four corners of the world as long as you include a compass rose. In fact, you map may align to magnetic poles that need not be all that close to the rotational poles. Gene Wolfe's Book of the New Sun takes place on the southern atmosphere on a far-future Earth. You might read that for inspiration.
144,224	<p>What would be the most efficient text communication method for a spacecraft operating on a super low bit rate (I'm talking something like 5 bits an hour, excluding error handling)? </p> <p>As you want both complexity (full English language and numbers) and speed (letters per day) resorting to something like Morse code seems the most obvious solution but is there any other options out there? </p>	[ { "answer_id": 144225, "author": "Thorne", "author_id": 33868, "author_profile": "https://worldbuilding.stackexchange.com/users/33868", "pm_score": 2, "selected": false, "text": "<p><strong>Textspeak</strong></p>\n\n<p>SMS messages originally were 160 characters so <a href=\"https://en.w...	2019/04/17	[ "https://worldbuilding.stackexchange.com/questions/144224", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/26903/" ]	What would be the most efficient text communication method for a spacecraft operating on a super low bit rate (I'm talking something like 5 bits an hour, excluding error handling)? As you want both complexity (full English language and numbers) and speed (letters per day) resorting to something like Morse code seems the most obvious solution but is there any other options out there?	The most efficient communication is probably a command set. Since you contemplated Morse code, I assume that the communication is done via a fully defined interface - both sender and receiver know what a bit sequence is supposed to mean. A command set is no more that giving different codes predefined meanings. With one singe bit you can define 2 commands: ``` \| value \| meaning \| \| 0 \| light off \| \| 1 \| light on \| ``` With 4 bits you can define 15 different commands, with 1 byte (8 bits) 255 commands, with 2 bytes 65535 commands and so on. If all you really need is to display texts to an astronaut, you have to store a bunch of ready made texts like "Activate X-ray sensors" in a database and send the corresponding message ID from Earth. For more complex messages you can store text templates in a database and then compile a message from several templates. An early real-world example is the list of [Q-Codes](https://en.wikipedia.org/wiki/Q_code), created circa 1909, by the British government as a "list of abbreviations... prepared for the use of British ships and coast stations licensed by the Postmaster General". --- If you need to communicate more than simple texts, you would separate a message into a command part and a message part. You could, for example, tell the space ship: > > Activate X-ray sensors > > > By sending a signal of 2 bytes: ``` \| byte \| value \| meaning \| \| 1 \| 01 \| activate appliance \| \| 2 \| 08 \| X-ray sensor array \| ``` Communication with an astronaut would be possible with a different command: ``` \| byte \| value \| meaning \| \| 1 \| 04 \| write to terminal \| \| 2 \| 08 \| text with ID 8 \| ``` That would result in slightly longer commands, but the possibilities of what you can achieve with a few bytes are multiplied. --- If you have a really big database with a whole lot of different texts, it might be more efficient to terminate commands with a defined code. For this approach, the database must be sorted in a way that gives the most frequent commands the lowest ID. Let's define `0000` as the terminator. * For a very common command with the ID 6, you need to send the command's ID followed by the terminator: `0110 0000`. * A very uncommon command with the ID 26683 would look like this: `0110 1000 0011 1011 0000`. The advantage is that you can have commands of dynamic lengths (instead of sending a whole bunch of useless 0's to fill up the static length of a command). The disadvantage is that every command is longer than it could ideally be. So this approach only gets worthwhile when you need a great many commands. --- After defining your command set, the next step is to make sure that you received the correct message. Losing just a single bit can change a message of "Activate X-ray sensors" into "Destroy X-ray sensors" or similar. This is usually done with a checksum, which requires some more bits to transmit. Have a look at the difference between two common data transmission protocols for the internet: [UDP](https://en.wikipedia.org/wiki/User_Datagram_Protocol) and [TCP](https://en.wikipedia.org/wiki/Transmission_Control_Protocol). UDP is the most efficient in respect to transfer rate, but TCP trades some efficiency for reliability by including some overhead for error checking.
146,412	<p>Assuming the power source for such acceleration places no limit on things, how quickly can a space craft be accelerated to the speed necessary to cross the distance between Jupiter and the sun in about 30 days time, without the G forces causing harm or unbearable discomfort to the crew?</p>	[ { "answer_id": 146418, "author": "Sonvar", "author_id": 59628, "author_profile": "https://worldbuilding.stackexchange.com/users/59628", "pm_score": 1, "selected": false, "text": "<p>Assuming you want your acceleration at 1g, 9.8m/s<sup>2</sup>, since anything more would become uncomforta...	2019/05/06	[ "https://worldbuilding.stackexchange.com/questions/146412", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/38944/" ]	Assuming the power source for such acceleration places no limit on things, how quickly can a space craft be accelerated to the speed necessary to cross the distance between Jupiter and the sun in about 30 days time, without the G forces causing harm or unbearable discomfort to the crew?	The basic equation here is s=1/2 at^2, where s is distance, a is acceleration, and t is time. You have to allow for deceleration on the other end, so assuming you decelerate at the same rate that you accelerated, the easiest way to do the calculation is to cut the distance in half, then double everything when you're done. Distance from the Sun to Jupiter is about 483 million miles. So if we want to make the whole trip in 30 days with a continuous, even acceleration, then we want to go half-way in 15 days, then decelerate for the next 15 days. Halfway is 242 million miles. That's 1.28e12 feet. 15 days=1.30e6 seconds. So ``` s=1/2 at^2 1.28e12=1/2 a * (1.30e6)^2 a=1.5 ``` That's 1.5 ft/sec^-2, or about .04g. That's a pretty mild acceleration rate.
147,785	<p>Is it possible for a planet to be much further away from its star than earth is from the sun (because for example the star is much brighter/Hotter) yet still have a comparable (as in not tens if not hundreds or thousands of times longer) year and day length to earth? </p> <p>P.S. To clarify this question somewhat. This question comes sorta as a follow up to a question i once asked regarding a planet orbiting a Blue Supergiant star. But with the distance required to give the planet an earth like climate it would have such a huge orbit that 1 year on this world would take a little more than 13 ''Earth'' centuries wich would end with me having to make the race on this world basically immortal compared to humans or give them a livespan that (using this world's timespans and still using earth like 12 months a year) would mean that the average lifespan of a person would be less than 1 month. </p> <pre><code> TLDR. can i speed the rotation time of this planet around the star up to get to ''earth like'' (does not have to be completely exact, 1 year on this world could be 3 earth years for all i care just not earth centuries or millenia) length or would this mess up the entire world? </code></pre>	[ { "answer_id": 147787, "author": "L.Dutch", "author_id": 30492, "author_profile": "https://worldbuilding.stackexchange.com/users/30492", "pm_score": 2, "selected": false, "text": "<p>First of all, the day lenght has nothing to do with the distance from the star. It only depends on the ti...	2019/05/26	[ "https://worldbuilding.stackexchange.com/questions/147785", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/57044/" ]	Is it possible for a planet to be much further away from its star than earth is from the sun (because for example the star is much brighter/Hotter) yet still have a comparable (as in not tens if not hundreds or thousands of times longer) year and day length to earth? P.S. To clarify this question somewhat. This question comes sorta as a follow up to a question i once asked regarding a planet orbiting a Blue Supergiant star. But with the distance required to give the planet an earth like climate it would have such a huge orbit that 1 year on this world would take a little more than 13 ''Earth'' centuries wich would end with me having to make the race on this world basically immortal compared to humans or give them a livespan that (using this world's timespans and still using earth like 12 months a year) would mean that the average lifespan of a person would be less than 1 month. ``` TLDR. can i speed the rotation time of this planet around the star up to get to ''earth like'' (does not have to be completely exact, 1 year on this world could be 3 earth years for all i care just not earth centuries or millenia) length or would this mess up the entire world? ```	Yes, it is possible. Day length is only effected by how fast the planet rotates. This is unrelated to the orbit. Year length increases as your orbit gets bigger, and decreases as your star gets bigger. The heavier the star is, the faster your have to orbit to stay a certain distance away. The farther away the planet is, the slower it orbits. You can have an orbit of practically any period given the correct stellar mass and orbital altitude. I don't know how this alters the heating issues though. It's possible that the habitable zone around this larger star would not be at the correct altitude.
147,916	<p>If a chunk of land mass the size and position of Sweden took off and floated away in a straight line, exiting the atmosphere and orbiting earth, at what distance would it be visible from, let's say, South Africa?</p> <p>Alternatively, what size would our planet have to be to allow for such a floating land mass to be visible from the proportionate equivalent of South Africa, while still within the bounds of the planet's (unchanged) atmosphere?</p> <p><strong>Edit:</strong> Thanks for all your detailed and interesting answers! Didn't expect my silly question to blow up like that, tbh.</p> <p>I was quite tired when I first posted and realize that I haven't specified some things properly.</p> <p>Originally, I had intended for floating Sweden to remain geostationary, orbiting <em>with</em> the planet rather than around it (because magic). I thought perhaps the atmosphere's refractivity (which only @Chronocidal mentioned as far as I've seen) might allow for a high enough Sweden to be visible on the horizon, if the observer was positioned at the northernmost point of South Africa, with no obstacles in his line of vision, at maybe 1500 meters above sea level.</p> <p>But in light of the response here, I decided to just have my floating island properly orbit the planet somewhere within the thermosphere instead.</p>	[ { "answer_id": 147925, "author": "Mori", "author_id": 65279, "author_profile": "https://worldbuilding.stackexchange.com/users/65279", "pm_score": 6, "selected": false, "text": "<p>Given Sweden has a latitude of 60° N and south Africa of a bit over 30° S, you can never see one from the ot...	2019/05/28	[ "https://worldbuilding.stackexchange.com/questions/147916", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/65278/" ]	If a chunk of land mass the size and position of Sweden took off and floated away in a straight line, exiting the atmosphere and orbiting earth, at what distance would it be visible from, let's say, South Africa? Alternatively, what size would our planet have to be to allow for such a floating land mass to be visible from the proportionate equivalent of South Africa, while still within the bounds of the planet's (unchanged) atmosphere? Edit: Thanks for all your detailed and interesting answers! Didn't expect my silly question to blow up like that, tbh. I was quite tired when I first posted and realize that I haven't specified some things properly. Originally, I had intended for floating Sweden to remain geostationary, orbiting with the planet rather than around it (because magic). I thought perhaps the atmosphere's refractivity (which only @Chronocidal mentioned as far as I've seen) might allow for a high enough Sweden to be visible on the horizon, if the observer was positioned at the northernmost point of South Africa, with no obstacles in his line of vision, at maybe 1500 meters above sea level. But in light of the response here, I decided to just have my floating island properly orbit the planet somewhere within the thermosphere instead.	Given Sweden has a latitude of 60° N and south Africa of a bit over 30° S, you can never see one from the other no matter how high one is and no matter how small the planet is (as long as it still is big enough to allow you to neglect the distance between your eyes and the surface). The Sweden simply rises further away in the hemisphere invisible from South Africa. That is if Sweden rises simply above and continues to stay above the used-to-be-Sweden, i.e rotates with Earth. If it starts orbiting Earth forming new moon, it will probably pass over South Africa sooner or later. Obviously, I am magically hand-waving away the atmospheric friction. Edit: very sophisticated visualization: [![graphics](https://i.stack.imgur.com/Y7jaj.png)](https://i.stack.imgur.com/Y7jaj.png) Edit 2: for a more general solution, given both points have the same longitude: cos (difference in latitude) = (Earth radius, 6378 km)/(Sweden distance from Earth center, i.e. height + Earth radius). For point directly below equator this yield ``` 0.5 = cos(60 - 0) = 6378/(h+6378) -> h = 6378 km ``` waaaay above atmosphere.
148,379	<pre><code>TO: [mailing-list:all-employees] CC: [mailing-list:quality-assurance], [mailing-list:facilities] BCC: [mailing-list:galactic-villains] Subject: Thought Experiment - removing all life from a planet </code></pre> <p>My Distinguished Employees;</p> <p>I would like to take a moment to propose a thought experiment concerning our recent planetary project. The Viral Planet program was shuttered due to budget constraints, unfortunately, but it did produce excellent work from its team, as well as a number of off-shoot programs and opened the door to new challenges and opportunities.</p> <p>I'd like to bring one of these challenges to the forefront. Would it be possible to devise a methodology, whether by artificial design or natural happenstance, that <em>all life</em> on a given planet could be removed without leaving remains such as corpses?</p> <p>I understand that this has been done before by <a href="https://en.wikipedia.org/wiki/Thanos" rel="nofollow noreferrer">a friend of mine</a>, but the effects were successfully undone by an <a href="https://en.wikipedia.org/wiki/Avengers_(comics)" rel="nofollow noreferrer">independent organization</a> dedicated to preserving the status quo. While I of course abhor the wanton destruction of all life throughout the universe, I can't help but wonder if there's a way to scale down that same effort to just a single target planet.</p> <p>One could argue that acquiring <a href="https://en.wikipedia.org/wiki/Infinity_Gems" rel="nofollow noreferrer">the tools of the trade</a> previously used to great effect would work in this regard, I would also remind that doing so would likely draw the attention of, and intervention by, the same organization mentioned above. So please constrain the methods of this thought experiment to non-supernatural and non-reality-altering avenues of pursuit.</p> <p>To reiterate: I'm looking for a method to remove all life from a planet that does not impact the geographical or structural environment. In other words, the method may damage the atmosphere and boil the oceans, but must leave buildings, cities, and geographical landmarks unscathed.</p> <p>Thanks for Your Attention,</p> <p><a href="https://tvtropes.org/pmwiki/pmwiki.php/Main/BigBad" rel="nofollow noreferrer">B. B.</a> Calamity<br> Chief Executive Officer<br> Intergalactic Engineering and Design</p> <hr> <p>M E M O R A N D U M</p> <p>To: [mailing-list:all-employees]</p> <p>From: <a href="https://www.youtube.com/watch?v=wwGsZZN-YD4" rel="nofollow noreferrer">Carl Llama</a></p> <p>Date: June 5, 2019</p> <p>Subject: Re: Rumors</p> <p>In response to the rumors circulating the office after Mr. Calamity's email, I reached out to the CEO. He assures me that there is no intention of the results of this exercise to be available to outside organizations, that the methodology resulting from this exercise will never be used on Earth, and that no <a href="https://www.merriam-webster.com/dictionary/scapegoat" rel="nofollow noreferrer">employee will be held accountable</a> for any disaster that befell a world that suffered a fate reminiscent of this thought experiment.</p> <hr> <p>This question is <em>not</em> a duplicate of <a href="https://worldbuilding.stackexchange.com/q/147882/6986">this question</a> because that one has as its criteria "before the end of 2025 to destroy all life on Earth within a 30-day period." This question specifies neither a constraining date (2025) or a timeframe of action (30 days).</p> <p>Further, these two questions differ in regard to a specific constraint defined here and not in the other question:</p> <blockquote> <p>without leaving remains such as corpses</p> </blockquote> <p><a href="https://worldbuilding.meta.stackexchange.com/questions/7364/site-policy-judging-when-a-question-is-a-duplicate?cb=1">Here is a link to a relevant Meta post</a> about judging when answers may be duplicates of each other.</p>	[ { "answer_id": 148381, "author": "Alex", "author_id": 62779, "author_profile": "https://worldbuilding.stackexchange.com/users/62779", "pm_score": 0, "selected": false, "text": "<p>I believe nanobot swarms, mixed with chemically altering the oceans and atmosphere might be an answer. Theor...	2019/06/05	[ "https://worldbuilding.stackexchange.com/questions/148379", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/6986/" ]	``` TO: [mailing-list:all-employees] CC: [mailing-list:quality-assurance], [mailing-list:facilities] BCC: [mailing-list:galactic-villains] Subject: Thought Experiment - removing all life from a planet ``` My Distinguished Employees; I would like to take a moment to propose a thought experiment concerning our recent planetary project. The Viral Planet program was shuttered due to budget constraints, unfortunately, but it did produce excellent work from its team, as well as a number of off-shoot programs and opened the door to new challenges and opportunities. I'd like to bring one of these challenges to the forefront. Would it be possible to devise a methodology, whether by artificial design or natural happenstance, that all life on a given planet could be removed without leaving remains such as corpses? I understand that this has been done before by [a friend of mine](https://en.wikipedia.org/wiki/Thanos), but the effects were successfully undone by an [independent organization](https://en.wikipedia.org/wiki/Avengers_(comics)) dedicated to preserving the status quo. While I of course abhor the wanton destruction of all life throughout the universe, I can't help but wonder if there's a way to scale down that same effort to just a single target planet. One could argue that acquiring [the tools of the trade](https://en.wikipedia.org/wiki/Infinity_Gems) previously used to great effect would work in this regard, I would also remind that doing so would likely draw the attention of, and intervention by, the same organization mentioned above. So please constrain the methods of this thought experiment to non-supernatural and non-reality-altering avenues of pursuit. To reiterate: I'm looking for a method to remove all life from a planet that does not impact the geographical or structural environment. In other words, the method may damage the atmosphere and boil the oceans, but must leave buildings, cities, and geographical landmarks unscathed. Thanks for Your Attention, [B. B.](https://tvtropes.org/pmwiki/pmwiki.php/Main/BigBad) Calamity Chief Executive Officer Intergalactic Engineering and Design --- M E M O R A N D U M To: [mailing-list:all-employees] From: [Carl Llama](https://www.youtube.com/watch?v=wwGsZZN-YD4) Date: June 5, 2019 Subject: Re: Rumors In response to the rumors circulating the office after Mr. Calamity's email, I reached out to the CEO. He assures me that there is no intention of the results of this exercise to be available to outside organizations, that the methodology resulting from this exercise will never be used on Earth, and that no [employee will be held accountable](https://www.merriam-webster.com/dictionary/scapegoat) for any disaster that befell a world that suffered a fate reminiscent of this thought experiment. --- This question is not a duplicate of [this question](https://worldbuilding.stackexchange.com/q/147882/6986) because that one has as its criteria "before the end of 2025 to destroy all life on Earth within a 30-day period." This question specifies neither a constraining date (2025) or a timeframe of action (30 days). Further, these two questions differ in regard to a specific constraint defined here and not in the other question: > > without leaving remains such as corpses > > > [Here is a link to a relevant Meta post](https://worldbuilding.meta.stackexchange.com/questions/7364/site-policy-judging-when-a-question-is-a-duplicate?cb=1) about judging when answers may be duplicates of each other.	To: "Carl Llama" From: "The New Guy" Date: June 5, 2019 Subject: Watch Out Dear Mr. Llama, Watch your back. This looks like a setup. I'm new here, but what you're asking can't be done. Life is just too robust, and cities are too fragile. You can't burn out the bacteria miles underground because those cities can't stand too much heat. The concrete will de-hydrolize and the buildings will collapse. You can't expose the world to intense enough radiation because the molecular structure of those precious cities will change, and the buildings will collapse. You can't do much underground without making the crust shift, and even small crustal changes will shake the surface, and the buildings will collapse. If you try to do something slowly, life will evolve to adapt to your change. If you put your reputation behind this project, the only thing killed will be your future with Universal Cleaning Company. Watch your back. You may be in Calamity's sights.
149,363	<p>I’m designing a human Bronze Age civilization on a world with only ⅓ of Earth’s gravity. This reduced gravity will allow humans to jump much higher than they could on Earth. It will also allow humans to climb much further and much faster given their reduced weight. This seems to me like it would render common fortification techniques, in particular walls, less effective.</p> <p>How might walls be modified to account for humans' enhanced vertical mobility or how might other methods be employed instead? What will low-tech defensive fortifications intended to keep people out look like on a low-gravity world?</p> <p>EDIT: To address concerns that humans of this world will be significantly weaker than humans on Earth due to the reduced gravity let us assume that the attackers of this world engage in various labors that give them comparable strength to humans as we know them. These humans did not evolve on this world. They are from Earth and now live on the low-gravity world and so still have the same capacity for strength as humans today.</p>	[ { "answer_id": 149367, "author": "L.Dutch", "author_id": 30492, "author_profile": "https://worldbuilding.stackexchange.com/users/30492", "pm_score": 2, "selected": false, "text": "<p>Gravity affects in the same projectiles and buildings. </p>\n\n<p>If a human can throw a spear or jump 3 ...	2019/06/21	[ "https://worldbuilding.stackexchange.com/questions/149363", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/879/" ]	I’m designing a human Bronze Age civilization on a world with only ⅓ of Earth’s gravity. This reduced gravity will allow humans to jump much higher than they could on Earth. It will also allow humans to climb much further and much faster given their reduced weight. This seems to me like it would render common fortification techniques, in particular walls, less effective. How might walls be modified to account for humans' enhanced vertical mobility or how might other methods be employed instead? What will low-tech defensive fortifications intended to keep people out look like on a low-gravity world? EDIT: To address concerns that humans of this world will be significantly weaker than humans on Earth due to the reduced gravity let us assume that the attackers of this world engage in various labors that give them comparable strength to humans as we know them. These humans did not evolve on this world. They are from Earth and now live on the low-gravity world and so still have the same capacity for strength as humans today.	1/3 gravity will enable humans to jump higher, but nothing absurd. For example on earth if you jump at 2m/s then you will have a jump time of: ``` t = (vf - vi)/g t = (0 - 2)/(-9.8) = 0.2 seconds ``` At 1/3 gravity that works out to: ``` t = (0 - 2)/(-9.8/3) = 0.6 seconds ``` Using this we can calculate the jump height by: ``` h = vi * t + (g * t²)/2 h = 2 * 0.6 + (-9.8/30.6^2)/2 = 0.6 meters ``` So slightly higher, but not enough to count. What this will* do is make it easier to build fortifications. Stones that weighed many tons, now weigh a 1/3 of that and are much easier to manage. A crew of dozens can erect stone structures that would take hundreds on earth and even on this world stone is stone, and similarly hard to get through. The ultimate effect of this will be tall stone structures everywhere to keep invaders out, instead of traditional wooden palisades. Which will be quite necessary considering the fact that catapults and other siege weapons will be able to throw stones 3 times as far! Archers will be of no use against enemy soldiers with these weapons as they can now fling stones from so far away that they are almost impossible for the archers to hit with any accuracy.
149,908	<p><strong>Background:</strong></p> <p>I have typical dragons: Huge, scaly, winged, and fire-breathing. I also have dragon magic, but I'd prefer answers not to draw on this too much. In my world, a planet similar to earth, dragons live on a separate continent from humans, so sightings are rare, and even rarer are actual pieces of dragons, e.g. a scale, tooth, or vial of breath. Obviously, since when dragons are alive, they can use these things to protect themselves, humans think it easier to take parts from dragons who are already dead through natural means. Dragons, being fairly intelligent and more civilized than most animals, bury their dead in a huge underground cavern far below the crust. </p> <p><strong>The Problem:</strong></p> <p>Unfortunately, I have certain scruples against humans wandering around in the great tomb, hacking off bits of the most recently deceased dragons. In fact, I don't particularly care for the sort of human who would want dragon parts, and I want to make getting scales, teeth, etc., harder than that for them. In order to force humans to attack living dragons to get the parts but also make dead dragons still, well, really cool, I thought the dragon remains could turn into diamond, diamonds, or some sort of precious stone/jewel. I'd heard of the carbon from human ashes being turned into diamonds through high pressure and high temperatures, and I wondered if having the tomb be a hundred miles under the surface of the earth, maybe even under a volcano, would raise the temperature and pressure enough to do something of the sort to the remains. </p> <p><strong>The Question:</strong></p> <p>Obviously, dragons don't have the means to separate the carbon from the other ashes, supposing there were any, so <strong>how might the dragon remains be *jewelified?</strong> </p> <pre><code> _____________________________________________________________________________ </code></pre> <p><sup><em><sub> <strong>This is subject to change.</em></sub></sup><br> <sup></strong><sub> <em>Er, heh heh!</em></sub></sup></p>	[ { "answer_id": 149919, "author": "Ash", "author_id": 40408, "author_profile": "https://worldbuilding.stackexchange.com/users/40408", "pm_score": 3, "selected": false, "text": "<p>\"Standard\" <a href=\"https://en.wikipedia.org/wiki/Petrifaction\" rel=\"noreferrer\">petrifaction</a> like ...	2019/06/30	[ "https://worldbuilding.stackexchange.com/questions/149908", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/62803/" ]	Background: I have typical dragons: Huge, scaly, winged, and fire-breathing. I also have dragon magic, but I'd prefer answers not to draw on this too much. In my world, a planet similar to earth, dragons live on a separate continent from humans, so sightings are rare, and even rarer are actual pieces of dragons, e.g. a scale, tooth, or vial of breath. Obviously, since when dragons are alive, they can use these things to protect themselves, humans think it easier to take parts from dragons who are already dead through natural means. Dragons, being fairly intelligent and more civilized than most animals, bury their dead in a huge underground cavern far below the crust. The Problem: Unfortunately, I have certain scruples against humans wandering around in the great tomb, hacking off bits of the most recently deceased dragons. In fact, I don't particularly care for the sort of human who would want dragon parts, and I want to make getting scales, teeth, etc., harder than that for them. In order to force humans to attack living dragons to get the parts but also make dead dragons still, well, really cool, I thought the dragon remains could turn into diamond, diamonds, or some sort of precious stone/jewel. I'd heard of the carbon from human ashes being turned into diamonds through high pressure and high temperatures, and I wondered if having the tomb be a \hundred miles under the surface of the earth, maybe even under a volcano, would raise the temperature and pressure enough to do something of the sort to the remains. The Question:* Obviously, dragons don't have the means to separate the carbon from the other ashes, supposing there were any, so *how might the dragon remains be \\jewelified?* ``` _____________________________________________________________________________ ``` *This is subject to change.* Er, heh heh!	"Standard" [petrifaction](https://en.wikipedia.org/wiki/Petrifaction) like what can happen to wood of the bones, teeth, and probably scales is highly likely if your dragon is buried deeply. Depending on the particular processes that occur parts of the beast may be [opalised](https://en.wikipedia.org/wiki/Opal). It is also possible, depending on the make up of your dragons, that parts of them are already composed of jewel like materials, for example [diamond](https://en.wikipedia.org/wiki/Diamond) has extremely high thermal conductivity so it may be useful for heat dissipation in a very large creature since the cubed-squared law is not kind at such extremes of size. Conversely certain members of the [Serpentine](https://en.wikipedia.org/wiki/Serpentine_subgroup) family are extremely heat resistant making good fireproofing for areas like the snout.
151,298	<p>For certain reasons I decided to not set my story on Earth. However, the planet is meant to host an Earth-like biosphere (including humans, most of Earth's species (perhaps some that didn't evolve before)). Since I was working with another planet, I decided to make it as big as possible (hence the question). The lifeforms on said planet don't need to be exactly analogous to Earth (evolution could have taken different forms), but it does need to be able to support homo sapiens (with perhaps some biological adaptations to living under higher gravity (only as high as is feasible) and other differing conditions, but still the same basic makeup).</p>	[ { "answer_id": 151299, "author": "AlexP", "author_id": 29552, "author_profile": "https://worldbuilding.stackexchange.com/users/29552", "pm_score": 4, "selected": true, "text": "<p>Surface gravity is directly proportional with the radius of the planet and inversely proportional with the d...	2019/07/20	[ "https://worldbuilding.stackexchange.com/questions/151298", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/10544/" ]	For certain reasons I decided to not set my story on Earth. However, the planet is meant to host an Earth-like biosphere (including humans, most of Earth's species (perhaps some that didn't evolve before)). Since I was working with another planet, I decided to make it as big as possible (hence the question). The lifeforms on said planet don't need to be exactly analogous to Earth (evolution could have taken different forms), but it does need to be able to support homo sapiens (with perhaps some biological adaptations to living under higher gravity (only as high as is feasible) and other differing conditions, but still the same basic makeup).	Surface gravity is directly proportional with the radius of the planet and inversely proportional with the density of the planet. Now fire up LibreOffice Calc (or your favorite spreadsheet program), and play with the numbers. I suggest to put Earth's radius, surface area and surface gravity as 1 (because your are interested in relative values), but keep the Earth's density as 5.5 (because it has direct implications for the chemical composition of the planet etc.) Then figure out what increase in surface gravity you are prepared to tolerate (I suggest 20 to 25% tops) and what decrease in density you can justify while keeping enough iron to get a decent magnetic field and to preserve Earth-like biochemistry (I suggest not lower than 5). You will get something like this: ``` Radius Area Density Gravity ------ ---- ------- ------- Earth 1.00 1.00 5.50 1.00 Max gravity, lowest density 1.38 1.89 5.00 1.25 Max-ish gravity, lowest density 1.32 1.74 5.00 1.20 Moderate gravity, lowest density 1.21 1.46 5.00 1.10 ``` This suggests that you can get a surface area 75 to 90% larger than Earth's without extremely strong effects on the biosphere, and a surface area 50% larger than Earth's with minimal effects on the biosphere.
152,382	<p>I am not talking about anterior, posterior, etc... I am looking for words specifically relating to movement.</p> <p>Long description... In the mythos I am working on, mages learn to control objects in three dimensional space. They first learn to summon objects within six different spaces.</p> <ul> <li>Anterior = Front</li> <li>Posterior = Back</li> <li>Superior = Upper</li> <li>Inferior = Lower</li> <li>Dextral = Right hand side</li> <li>Sinistral = Left hand side</li> </ul> <p>After learning to summon objects fluently in all six spaces, they learn to "throw" objects in different directions.</p> <p>For example: a student would consistently summon a stone in the dextral, superior space (to their right side just above their head). An instructor would shout directions and the student would have to "throw" the stone in the correct direction. So, any object moving in an anterior direction according to the perspective of the mage, regardless of where it was summoned, would be moving "forward" or ???. Any object moving in a dextral direction according to the perspective of the mage, regardless of where it was summoned, would be moving "to the right" or ???, etc...</p> <p>I have accepted that I may just have to use the words right, left, forward, back, up, and down. I just want to see if I'm missing some more specific/scientific terms.</p> <p>To clarify: this isn't fur the reader's benefit, I am trying to find weird that would cost approximate what the instructors would be using in their teaching. The people that use magic are very scientific, dictionary, vocabulary oriented and using common terms like up, down, left, right would be to, well, common.</p>	[ { "answer_id": 152390, "author": "Psylent", "author_id": 14841, "author_profile": "https://worldbuilding.stackexchange.com/users/14841", "pm_score": 2, "selected": false, "text": "<p>How about you use ship orientations?</p>\n\n<p><code>Front...Fore\nBack.....Aft\nLeft.....Port\nRight.......	2019/08/06	[ "https://worldbuilding.stackexchange.com/questions/152382", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/66951/" ]	I am not talking about anterior, posterior, etc... I am looking for words specifically relating to movement. Long description... In the mythos I am working on, mages learn to control objects in three dimensional space. They first learn to summon objects within six different spaces. * Anterior = Front * Posterior = Back * Superior = Upper * Inferior = Lower * Dextral = Right hand side * Sinistral = Left hand side After learning to summon objects fluently in all six spaces, they learn to "throw" objects in different directions. For example: a student would consistently summon a stone in the dextral, superior space (to their right side just above their head). An instructor would shout directions and the student would have to "throw" the stone in the correct direction. So, any object moving in an anterior direction according to the perspective of the mage, regardless of where it was summoned, would be moving "forward" or ???. Any object moving in a dextral direction according to the perspective of the mage, regardless of where it was summoned, would be moving "to the right" or ???, etc... I have accepted that I may just have to use the words right, left, forward, back, up, and down. I just want to see if I'm missing some more specific/scientific terms. To clarify: this isn't fur the reader's benefit, I am trying to find weird that would cost approximate what the instructors would be using in their teaching. The people that use magic are very scientific, dictionary, vocabulary oriented and using common terms like up, down, left, right would be to, well, common.	Anatomy has some useful words: ``` Superior -> Above Inferior -> Below Ventral -> Fore of the body Dorsal -> Back of the body Frontal -> Fore of the head Occipital -> Back of the head Distal -> Out, towards the tip of extremities Proximal -> In, towards the body Rostral -> Towards the face Caudal -> Towards the tail ``` They say left and right in anatomy, as far as I can tell. I found [usage](https://www.researchgate.net/figure/Three-reference-planes-and-six-fundamental-directions-of-the-body-movement_fig3_323160009) of `Lateral` for right and `Contra-lateral` for left. We can import some words from heraldry for left and right: ``` Dexter -> Right (of the knight or shield, not the observer) Sinister -> Left (of the knight or shield, not the observer) ``` I think you will prefer `Sinistral and Dextral`, by the way. Which are the words we use for chirality. They would work like `Port` and `Starboard` in that they always refer to direction relative to the observed, except you do not have to explain why mages talk about ports. I also want to bring into attention these words from physics and chemistry: ``` Dextrorotation -> Clockwise rotation Levorotation -> Counterclockwise rotation ``` Note: these are always respect the observer. We do not say the hands of the clock are rotating counterclockwise when we are behind it. Speaking of rotation, anatomy has some: ``` Anteversion -> Rotate to the front Retroversion -> Rotate to the back ``` Axes: ``` Longitudinal -> Head to tail Horizontal -> Side to side Sagittal -> Front to back ``` And planes: ``` Coronal -> Separates front and back Transversal -> Separates top and bottom Median -> Separates left and right ``` Oh, by the way, in astronomy they use `Zenith` and `Nadir` for up and down... not of the observer, not of the observed... but as absolute orientation. You can use them to complement the cardinal directions (`North, South, East/Orient, West/Occident`). Note: It is worth mentioning that some language do not have relative positions. Instead people use cardinal directions always.
154,104	<p>I'm presently in the process of developing my plans for a flintlock fantasy series. It's high magic, but one form of magic in the setting, Arcane Magic, is heavily based in science. The energy that powers it, Aethyr, can bend the laws of physics but not outright break them. (You can't turn someone into a frog with Arcane Magic, in other words.) My protagonist, Perdita, is an Arcane Engineer. She's someone who makes magical devices of an Arcane nature. Among her creations is a belt that can perform a Spell called the <em>Sphere of Meteoric Conversion.</em> Here's the basic idea of how it works:</p> <p>When Perdita falls beyond a certain distance, the belt activates, using Aethyr to create a magical bubble around her. When she hits the ground (or any solid object larger than the average bird,) the <em>Sphere of Meteoric Conversion</em> converts all her kinetic energy <em>and</em> the kinetic energy of the surface pushing back against her (that is, the equal and opposite reaction) into another kind of energy or simply redirect the kinetic energy away from her.</p> <p>By this I mean <em>that the bubble</em> absorbs all the energy of the impact and transfers it away from Perdita so she takes no damage, either by directing it at something other than her or by converting it into a different kind of energy which is then directed away from her.</p> <p>So, the bubble may just cause all the absorbed kinetic energy to go outward from it in all directions, like a bomb going off. Or it may convert all the kinetic energy into thermal or radiant energy and release it outward in all directions. I suppose converting it into sound is also something it can do.</p> <p>The <em>Sphere of Meteoric Conversion</em> can also direct the absorbed and converted kinetic energy in a ring or a beam. For example, when she hits, the bubble discharges a disk of light, heat, or sound along its proverbial equator. Or it may discharge a heat beam or laser beam directly up into the air. The point is that it takes the energy of the impact and turns it into something else to be used in a different way while Perdita remains safe inside the bubble.</p> <p>And, before you ask, yes, the amount of Aethyr needed to create the <em>Sphere of Meteoric Conversion</em> is considerable, especially if she's moving at terminal velocity. The belt is going to need some time to "cool down" (not literally) before it can generate the Spell again.</p> <p>Also, the Spell doesn't have to convert all the kinetic energy into just one other type of energy. It can convert some of it into radiant energy, some of it into thermal energy, some of it into sound, and just redirect any left over kinetic energy away from Perdita.</p> <p>What I need help with is determining the math for the <em>Sphere of Meteoric Conversion.</em> I want to make sure the math holds up in the books. Also, is there anything I'm overlooking or missing with this idea? I know it's magic, but, like I said, Arcane Magic is intended to be as science based as possible.</p> <p>It's going to be interesting seeing the feedback I get on this. I hope that it presents some of you with a fun puzzle, at the very least.</p> <p><strong>Edit and Update</strong></p> <p>Okay, it seems I need to clarify another point here: The purpose of the <em>Sphere of Meteoric Conversion</em> is to weaponize the kinetic energy of the impact <em>in addition</em> to preventing Perdita from taking any damage. Alternatively, it will convert the kinetic energy into something harmless so she doesn't hurt herself, her allies on the ground, or do any significant property damage. I think it will be easier to explain this with a few examples. Some things that will be applicable in all the examples are the following:</p> <p>Perdita is a <em>Half-Orc</em>, not a Human. She's 6'7" tall and weighs about 220 lbs. The gear she usually has on her probably comes to a total of 30 lbs., minimum. (That's her leather garments, melee weapons, flintlock guns, ammunition, etc.) So, total weight is around 250 lbs.</p> <p><strong>Example 1:</strong> Perdita is up on the tower of a castle. In the courtyard below is a horde of Ghouls (basically zombies) trying to break into the front entrance of the main keep. Perdita has the Mage with her use a Spell to launch her high into the air so she then comes down in the center of the mob of Ghouls. The <em>Sphere of Meteoric Conversion</em> changes the kinetic energy of the impact into thermal radiation and releases it as a disk from the "equator" of the bubble. Ghouls are weak against extreme heat. Or she may have the thermal radiation released as a beam that targets one really big Ghoul that's the size of the Incredible Hulk. The point is that she uses the kinetic energy of her impact to burn some Undead.</p> <p><strong>Example 2:</strong> Perdita is on a floating island over the ocean. She gets blown off it, either by a powerful burst of wind or a Mage using a Spell. As she falls towards the water below, she see a Sea Monster rising up, its jaws open to catch her. She activates the <em>Sphere of Meteoric Conversion</em> and adjust it to its "Zappy" setting. When she lands in the Sea Monster's mouth, the kinetic energy is converted into a pulse of electricity.</p> <p><strong>Example 3:</strong> Perdita is on an airship and, for one reason or another, gets thrown off of it. As she falls to the ground, she sees that she is headed toward a park where an aristocratic girl is having her Quinceañera. And the birthday girl has just received a puppy as her gift from her parents. Not wanting to become a party crashing in the most literal sense of the term, Perdita activates the <em>Sphere of Meteoric Conversion</em> and adjusts it to its "Harmless" setting. On impact, all the kinetic energy is converted into a beam of light (perhaps visible light, perhaps radio waves or something that won't hurt anyone.) The only damage done to the festivities is in the form of extreme awkwardness.</p> <p>These examples are hopefully sufficient to explain the the <em>why</em> of the <em>Sphere of Meteoric Conversion.</em> Perdita isn't just trying to protect herself from injury and death. She also wants <em>to harness</em> the kinetic energy of the impact in some way or just direct away so nobody is hurt and no property damage is caused. If she just wants to slow her fall so she lands safely, she'll use a different kind of Spell, but there are situations where a slow descent would be a problem, like if that would make her an easy target to shoot from the ground or if that would give someone she's chasing time to escape and hide.</p> <p>Hopefully this clarifies what I'm trying to figure out with this post. Also, having some examples of how to use the equations provided would be helpful, since I'm not a physicist and don't know what all the symbols in some of the equations mean without being told first. Once I do know, then I can use the equations myself, however, so I'm not asking other people to do all the calculations for me. I hope this clears things up.</p>	[ { "answer_id": 154110, "author": "ascripter", "author_id": 67576, "author_profile": "https://worldbuilding.stackexchange.com/users/67576", "pm_score": 0, "selected": false, "text": "<p>Well, I'm not sure if what you describe is bending the laws of physics less than transforming someone i...	2019/08/29	[ "https://worldbuilding.stackexchange.com/questions/154104", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/-1/" ]	I'm presently in the process of developing my plans for a flintlock fantasy series. It's high magic, but one form of magic in the setting, Arcane Magic, is heavily based in science. The energy that powers it, Aethyr, can bend the laws of physics but not outright break them. (You can't turn someone into a frog with Arcane Magic, in other words.) My protagonist, Perdita, is an Arcane Engineer. She's someone who makes magical devices of an Arcane nature. Among her creations is a belt that can perform a Spell called the Sphere of Meteoric Conversion. Here's the basic idea of how it works: When Perdita falls beyond a certain distance, the belt activates, using Aethyr to create a magical bubble around her. When she hits the ground (or any solid object larger than the average bird,) the Sphere of Meteoric Conversion converts all her kinetic energy and the kinetic energy of the surface pushing back against her (that is, the equal and opposite reaction) into another kind of energy or simply redirect the kinetic energy away from her. By this I mean that the bubble absorbs all the energy of the impact and transfers it away from Perdita so she takes no damage, either by directing it at something other than her or by converting it into a different kind of energy which is then directed away from her. So, the bubble may just cause all the absorbed kinetic energy to go outward from it in all directions, like a bomb going off. Or it may convert all the kinetic energy into thermal or radiant energy and release it outward in all directions. I suppose converting it into sound is also something it can do. The Sphere of Meteoric Conversion can also direct the absorbed and converted kinetic energy in a ring or a beam. For example, when she hits, the bubble discharges a disk of light, heat, or sound along its proverbial equator. Or it may discharge a heat beam or laser beam directly up into the air. The point is that it takes the energy of the impact and turns it into something else to be used in a different way while Perdita remains safe inside the bubble. And, before you ask, yes, the amount of Aethyr needed to create the Sphere of Meteoric Conversion is considerable, especially if she's moving at terminal velocity. The belt is going to need some time to "cool down" (not literally) before it can generate the Spell again. Also, the Spell doesn't have to convert all the kinetic energy into just one other type of energy. It can convert some of it into radiant energy, some of it into thermal energy, some of it into sound, and just redirect any left over kinetic energy away from Perdita. What I need help with is determining the math for the Sphere of Meteoric Conversion. I want to make sure the math holds up in the books. Also, is there anything I'm overlooking or missing with this idea? I know it's magic, but, like I said, Arcane Magic is intended to be as science based as possible. It's going to be interesting seeing the feedback I get on this. I hope that it presents some of you with a fun puzzle, at the very least. Edit and Update Okay, it seems I need to clarify another point here: The purpose of the Sphere of Meteoric Conversion is to weaponize the kinetic energy of the impact in addition to preventing Perdita from taking any damage. Alternatively, it will convert the kinetic energy into something harmless so she doesn't hurt herself, her allies on the ground, or do any significant property damage. I think it will be easier to explain this with a few examples. Some things that will be applicable in all the examples are the following: Perdita is a Half-Orc, not a Human. She's 6'7" tall and weighs about 220 lbs. The gear she usually has on her probably comes to a total of 30 lbs., minimum. (That's her leather garments, melee weapons, flintlock guns, ammunition, etc.) So, total weight is around 250 lbs. Example 1: Perdita is up on the tower of a castle. In the courtyard below is a horde of Ghouls (basically zombies) trying to break into the front entrance of the main keep. Perdita has the Mage with her use a Spell to launch her high into the air so she then comes down in the center of the mob of Ghouls. The Sphere of Meteoric Conversion changes the kinetic energy of the impact into thermal radiation and releases it as a disk from the "equator" of the bubble. Ghouls are weak against extreme heat. Or she may have the thermal radiation released as a beam that targets one really big Ghoul that's the size of the Incredible Hulk. The point is that she uses the kinetic energy of her impact to burn some Undead. Example 2: Perdita is on a floating island over the ocean. She gets blown off it, either by a powerful burst of wind or a Mage using a Spell. As she falls towards the water below, she see a Sea Monster rising up, its jaws open to catch her. She activates the Sphere of Meteoric Conversion and adjust it to its "Zappy" setting. When she lands in the Sea Monster's mouth, the kinetic energy is converted into a pulse of electricity. Example 3: Perdita is on an airship and, for one reason or another, gets thrown off of it. As she falls to the ground, she sees that she is headed toward a park where an aristocratic girl is having her Quinceañera. And the birthday girl has just received a puppy as her gift from her parents. Not wanting to become a party crashing in the most literal sense of the term, Perdita activates the Sphere of Meteoric Conversion and adjusts it to its "Harmless" setting. On impact, all the kinetic energy is converted into a beam of light (perhaps visible light, perhaps radio waves or something that won't hurt anyone.) The only damage done to the festivities is in the form of extreme awkwardness. These examples are hopefully sufficient to explain the the why of the Sphere of Meteoric Conversion. Perdita isn't just trying to protect herself from injury and death. She also wants to harness the kinetic energy of the impact in some way or just direct away so nobody is hurt and no property damage is caused. If she just wants to slow her fall so she lands safely, she'll use a different kind of Spell, but there are situations where a slow descent would be a problem, like if that would make her an easy target to shoot from the ground or if that would give someone she's chasing time to escape and hide. Hopefully this clarifies what I'm trying to figure out with this post. Also, having some examples of how to use the equations provided would be helpful, since I'm not a physicist and don't know what all the symbols in some of the equations mean without being told first. Once I do know, then I can use the equations myself, however, so I'm not asking other people to do all the calculations for me. I hope this clears things up.	``` When Perdita falls beyond a certain distance, the belt activates, using Aethyr to create a magical bubble around her. When she hits the ground (or any solid object larger than the average bird,) the Sphere of Meteoric Conversion converts all her kinetic energy and the kinetic energy of the surface pushing back against her (that is, the equal and opposite reaction) into another kind of energy or simply redirect the kinetic energy away from her. ``` There are two problems with this: 1. The ground doesn't have kinetic energy separate from or opposite to Perdita. And exactly how much kinetic energy there is depends on what frame you are doing the calculation in. The relevant frame for energy dissipation in a collision is the center-of-mass, zero-momentum frame of the colliding objects; when one of those object is the ground, the center-of-mass frame is for all practical purposes indistinguishable from the ground frame, and all of the kinetic energy is Perdita's. 2. The ground does exert an equal-and-opposite force on Perdita, thus transferring momentum to her and accelerating her to match velocities with the ground. It is that process which is responsible for injury and death from falls. Energy isn't irrelevant, but it's not the major player here; dissipating energy is easy. Limiting acceleration is key to safety. Perdita could absorb all of the kinetic energy of a terminal-velocity freefall into her own body as heat and be no worse for it, but that's no good if differential acceleration turns the physical structure of her body into jello. So, the bubble needs to do some combination of three things: 1. Slow her descent, spreading the acceleration over a longer distance to keep the g forces survivable. This is what, e.g., crumple zones in cars do--they crush so that the body of the car, containing squishy passengers, can continue moving for a few more feet after a crash, over which distance it can slow more gradually. This is also what airbags are for--they ensure that the passenger's body begins accelerating before hitting the steering wheel / dashboard / windshield, rather than doing at all at once on impact with something hard and unforgiving. 2. Magically stiffen the materials of her body so that all parts of her experience near-identical accelerations, and thus are not torn apart by differentials in momentum transfer. This kind of what g-suits do--by applying compressive forces to certain parts of the body, they ensure the g-load is distributed more evenly over the whole body, thus helping to prevent blackouts. This is where intentional energy dissipation becomes relevant; if the bubble and everything in it is super-stiff, it will just bounce. Perhaps the bubble could have multiple layers; an inner layer that briefly freezes Perdita's body, and an outer layer that slows the inner layer down over some finite distance and dumps the kinetic energy into heat. Like dropping a frozen egg inside a balloon full of jello. 3. Automatically re-orient Perdita's body into the most g-tolerant position. People can survive much higher accelerations on their backs than from any other direction, which is why infant car seats are rear-facing; not only does it help spread the load of a crash over a wider surface area compared to straining against relatively thin straps, but even controlling for equal support, the human body is simply more resistance to injury in that orientation. The relevant math is as follows: $KE = \frac{1}{2}mv^2$ Suppose Perdita weighs around 75kg (a reasonable number for a healthy adult human woman). Terminal velocity for people is somewhere around 55m/s. That means she has to dissipate $\frac{1}{2}(75kg)(55m/s)^2 = 113,437.5 J$ of energy, or around 27.1 food Calories. I.e., enough energy to raise 27kg of water by 1 degree celsius. Or all of Perdita's body by considerably less. Meanwhile, people can easily be seriously injured (or, if old or just really unlucky, outright killed) by low-velocity falls just from tripping on the sidewalk--it's not how much energy is involved, it is how that energy is applied in conjunction with momentum. $p = mv$ Perdita's momentum is $4125 \frac{m\ kg}{s}$ $a = \frac{v^2}{2d}$ Above an acceleration of 3g, Perdita will be uncomfortable. Above about 50g, she will sustain injury regardless of orientation. Above around 10g, you need to start employing those other measures like automatic reorientation and magically redistributing forces to avoid serious injury or death from falling the Wrong Way. So, if we want to simply dissipate energy into heat by slowing Perdita's descent, the bubble needs to have area of effect large enough to start slowing her descent at least $d = \frac{v^2}{2a} = \frac{(55m/s)^2}{6g} \approx 51.5m$ So, well above rooftop height if she's already at terminal velocity. At 10g with automatic reorientation, you're looking at a 15-meter bubble. If the bubble itself supplies additional air resistance, that terminal velocity will come down a bit, which helps. But if you want Perdita to land comfortably, on her feet so she can walk away (and maybe to an awesome superhero power-pose), and without the bubble interfering with the landscape in a 100-foot wide circle all around, I think you're pretty much gonna have to look at the "magically freeze her solid" / "Star Trek inertial dampeners" option. EDIT, to account for the question edit: ``` Perdita is a Half-Orc, not a Human. She's 6'7" tall [...]. So, total weight is around 250 lbs. ``` 250lbs is about 113kg. So, applying the kinetic energy equation again, and assuming she's still falling at a typical terminal velocity for a skydiver, she's got a total kinetic energy of $\frac{1}{2}(113kg)(55m/s)^2 = 170,912.5J$ To convert joules to kilocalories (of "food calories", where 1 kilocalorie is enough energy to heat a kilogram of water by 1 degree--a decent approximation for how much you will heat a squishy meatbag), just divide by 4184. Ergo, Perdita has access to about 41 (rounding up) kilocalories, enough kinetic energy from her fall to heat 41 kilos of ghoul by 1 degree. That's not much. She will not be incinerating any undead with that. However, once again we have to note that what matters is not really how much energy is available, but precisely how it is applied. Bullets have far less energy than that, but they're still lethal. If all that energy is released as an instantaneous flash of isotropic radiation, you won't incinerate or even set fire to any ghouls, but you might give them some nasty sunburns as most of the radiation is absorbed in the first few millimeters of skin / rotting flesh. That may or may not slow them down, depending on precisely how your flavor of undead happen to work. And if you concentrate that energy into a coherent beam, well... you can heat 1 gram of water by 40,000 degrees (not really, 'cause there's a phase change to worry about after a mere 100 degrees max, but that hardly matters at this scale). In other words, you can flash-vaporize a tiny chunk of ghoul flesh, causing it to violently explode as if it had been hit by a bullet. Or several small chunks, from several different ghouls, if Perdita has enough control to direct multiple beams like that. Enough energy to make the ghouls uncomfortable from extreme heat? No way. Enough energy to seriously mess up their day through other means? Absolutely. ``` She activates the Sphere of Meteoric Conversion and adjust it to its "Zappy" setting. When she lands in the Sea Monster's mouth, the kinetic energy is converted into a pulse of electricity. ``` What matters here is amperage, and current path. Trivially, we have the same total amount of energy at our disposal, and it could just be turned into heat by unconstrained electrical discharge through the creature; depending on the precise incidental current path, maybe that ends up mildly warming the creature (no help at all), or maybe it ends up seriously burning a small chunk, causing it great pain, and maybe actual disability or maybe not depending on exactly which small chunk gets burned. However, again, how the energy is applied matters. If she can direct an electrical discharge to just the right part of the animal (say, through its brain, or heart), very tiny currents can cause death--you only need about 100 to 200 milliamps for less than a second to irreversibly screw up the creature's nervous system, if it's applied in just the right place. The relevant formula in this case is $W = RI^2$, where W is power, R is resistance, and I is current. If we know how long we need the shock to last, we can replace power with total energy (which we know, from Perdita's kinetic energy), to get $E = TRI^2$. The electrical resistance of wet flesh is around 300Ω, and we want a current of around 150mA, so if we generously assume that we need the shock to last for at least 1 second to definitely incapacitate the creature, we get $E = (1s)(300Ω)(0.15A)^2 = 6.75J$. Way less than Perdita's total kinetic energy budget. So, yeah, she can electrocute the sea monster easily. ``` As she falls to the ground, she sees that she is headed toward a park [...] Not wanting to become a party crashing in the most literal sense of the term, Perdita activates the Sphere of Meteoric Conversion and adjusts it to its "Harmless" setting. On impact, all the kinetic energy is converted into a beam of light[....] The only damage done to the festivities is in the form of extreme awkwardness. ``` Not even necessary. All of the kinetic energy can simply be dissipated as heat--into Perdita's body, the air, the ground, some thermal radiation--and if it's not specifically focused somewhere, it would hardly be noticed.
154,185	<p>The <a href="https://en.wikipedia.org/wiki/Sewer_gas" rel="nofollow noreferrer">Wikipedia page on sewer gas</a> states that</p> <pre><code>Sewer gas can be used as a power source, thus reducing the consumption of fossil fuels. </code></pre> <p>However, no references or further details are provided.</p> <p>So, suppose that a typical modern house had its vent stack replaced by sewer gas burner system. Just how much power could that actually produce?</p> <p>Addendum: Yes, biowaste is currently used for power generation. And one could set up a bioreactor specifically to produce power from your own local waste. But this is specifically about the power available to a single house via the "natural" gas emissions from an actual sewer. Regardless of how many people live in a house, a modern house (not apartment) most places in the world that have municipal sewer systems will have a single connection to said sewer via pipe of one of a few standard sizes, which is also connected to a vent stack which allows gas to get sucked into the plumbing system when a slug drops through the pipes to avoid accidentally clearing P-traps, and which allows sewer gas to escape out of the house rather than building pressure behind P-traps.</p> <p>So, how much power could be obtained just by tapping that vent stack to access the gasses coming up from the sewer?</p> <p>Sewer gas lamps are an (archaic) thing that exists, but they were never used for actual light or power--merely to induce an updraft to force sewer gasses to vent above head hieght and prevent buildups that would be unpleasant if they escaped at ground level.</p> <p>If that does not represent a reasonable power source, and to grandfather in existing answers, it would also be interesting to know how much power can be supplied per person via small-scale residential bioreactors. And if coupled with a municipal sewer system, could that sort of preprocessing represent a practical method of reducing strain on said municipal sewer and wastewater treatment systems?</p>	[ { "answer_id": 154190, "author": "The Square-Cube Law", "author_id": 21222, "author_profile": "https://worldbuilding.stackexchange.com/users/21222", "pm_score": 2, "selected": false, "text": "<p>I'll try.</p>\n\n<p>Continents as a whole have a lot of variation in height, but tje ice on t...	2019/08/30	[ "https://worldbuilding.stackexchange.com/questions/154185", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/2800/" ]	The [Wikipedia page on sewer gas](https://en.wikipedia.org/wiki/Sewer_gas) states that ``` Sewer gas can be used as a power source, thus reducing the consumption of fossil fuels. ``` However, no references or further details are provided. So, suppose that a typical modern house had its vent stack replaced by sewer gas burner system. Just how much power could that actually produce? Addendum: Yes, biowaste is currently used for power generation. And one could set up a bioreactor specifically to produce power from your own local waste. But this is specifically about the power available to a single house via the "natural" gas emissions from an actual sewer. Regardless of how many people live in a house, a modern house (not apartment) most places in the world that have municipal sewer systems will have a single connection to said sewer via pipe of one of a few standard sizes, which is also connected to a vent stack which allows gas to get sucked into the plumbing system when a slug drops through the pipes to avoid accidentally clearing P-traps, and which allows sewer gas to escape out of the house rather than building pressure behind P-traps. So, how much power could be obtained just by tapping that vent stack to access the gasses coming up from the sewer? Sewer gas lamps are an (archaic) thing that exists, but they were never used for actual light or power--merely to induce an updraft to force sewer gasses to vent above head hieght and prevent buildups that would be unpleasant if they escaped at ground level. If that does not represent a reasonable power source, and to grandfather in existing answers, it would also be interesting to know how much power can be supplied per person via small-scale residential bioreactors. And if coupled with a municipal sewer system, could that sort of preprocessing represent a practical method of reducing strain on said municipal sewer and wastewater treatment systems?	I would have to go with Saturn's moon, Iapetus. Iapetus has a mountain range all the way around its 1500 km equator: [![enter image description here](https://i.stack.imgur.com/WlMJe.jpg)](https://i.stack.imgur.com/WlMJe.jpg) The current theory is that it is a collapsed ring that once cirlced Iapetus.
156,565	<p>In one of my stories, I have a race that communicates using only two sounds: "O" and "U". This can be strung together like this:</p> <pre><code>Uuuoouoouooouuuooouuoouoououooououo </code></pre> <p>Or something like that. <em>There are no pauses between words within a sentence.</em><br> It is essentially a binary language, just like what machines use.</p> <h2>Using only two phonemes, how complex can communication be?</h2> <p>The following concerns come to mind:<br> 1. How can each word be differentiated without any pauses between words?<br> 2. Assuming you can get past the above problem, will it simply take too long for them to convey information?</p>	[ { "answer_id": 156568, "author": "Willk", "author_id": 31698, "author_profile": "https://worldbuilding.stackexchange.com/users/31698", "pm_score": 2, "selected": false, "text": "<p>Latin written with <a href=\"https://en.wikipedia.org/wiki/Scriptio_continua\" rel=\"nofollow noreferrer\">...	2019/09/19	[ "https://worldbuilding.stackexchange.com/questions/156565", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/68902/" ]	In one of my stories, I have a race that communicates using only two sounds: "O" and "U". This can be strung together like this: ``` Uuuoouoouooouuuooouuoouoououooououo ``` Or something like that. There are no pauses between words within a sentence. It is essentially a binary language, just like what machines use. Using only two phonemes, how complex can communication be? ---------------------------------------------------------- The following concerns come to mind: 1. How can each word be differentiated without any pauses between words? 2. Assuming you can get past the above problem, will it simply take too long for them to convey information?	This is fairly easy. With tri-state it's even easier, but for now let's consider just using a click or silence (a la pure binary: 00101010). The answer is a lot and as quick as their memory can handle. Let's lay some ground theory: * There are a small set of "proto verbs" (Incorrect terminology so I'm having trouble sourcing this), of quantity less than 30, some of which have no existing counterpart in English. Nevertheless, you can define all verbs using that small set in the right combinations with other words. * Similarly, you can do the same with many parts of speech (Cat: four-legged furry mammal...etc.) * Nouns/Adjectives are your largest collection. Although you can do either-or. [StackExchange](https://english.stackexchange.com/questions/55486/what-are-the-percentages-of-the-parts-of-speech-in-english) would put this at somewhere between 19% and 33% utilization, I believe. Looking at [English Dictionaries](https://en.wikipedia.org/wiki/List_of_dictionaries_by_number_of_words) for a maximum for a number of words puts us at 155 thousand nouns/adjectives which can be enumerated with 18 bits. * If the universe has roughly 1082 atoms in it then you can enumerate them with 272 bits which will be of such magnitude that it would be laughable to consider filling it completely. You can use that number as a max. I prefer 64 bits. Your minimum enumeration to match English is less than 18 bits using proto-words (probably something like 12 bits), and 19 bits to match exactly. * Words consist of definitions, which are combinations of either other words or proto words. It is compression. Each word added adds to the memory requirements, and the bits needed to enumerate all words. But, adding words increases transmission speed. You can trade memory for speed almost as much as you want here. * *Crucially* you can even compress those words by frequency of usage simply by adopting the same trick that saved Unicode.... [UTF-8](https://en.wikipedia.org/wiki/UTF-8), just pick a "byte" size that encompasses enough of your common words and make the rest extended bytes. Other variable-length encodings are usable as well. What you end up with is as much content, almost as fast as you please (within a log-factor), as specific as you want (this atom), tailored to your language/culture. What's the downside? The number of sounds is a multiplier on transmission speed. Any crafted language could do the above-described things. But the more sounds you have the quicker you can do so. 26 sounds? 4 times the content in two sounds (log(26)/log(2)). But as far as "as quick as their memory can handle" [there's a limit: ~380 wpm](https://www.youtube.com/watch?v=zUDqI9PJpc8)... which probably is present for non-humans but just different rates. What about adding silence? Tri-state let's you scrap the UTF-8 "extension bits", or gives you another symbol to play with (log(26)/log(3) now). Speed or compression gains either way.
157,834	<p>My story involves people with supernatural abilities. I want to create a character that has classic superspeed like the comic book superhero <a href="https://en.wikipedia.org/wiki/Flash_(comics)" rel="nofollow noreferrer">The Flash</a>, but I want my character to only have realistic applications of such a power.</p> <p>Some applications I have already debunked:</p> <ul> <li>Saving people: Grabbing people at lightning speed and then transporting them out of harm's way would just turn their insides into jelly, due to the sudden changes in speed. (Law of Conversation of Momentum) I do not accept mystical reasons like "the speed force protects them while in transit". In my story there is no "speed force".</li> <li>Running up completely vertical walls indefinitely: Friction is needed to go up the wall. But to get friction, one needs to press their feet against the wall, which pushes them away from it. And then eventually they're not close enough to keep running up the wall.</li> <li>Super speed in general: At higher speeds, the user would superheat the area around themselves, incinerating objects and people around themselves. This is caused by the friction of the air molecules; the same reason most objects burn up during atmospheric entry.</li> <li>Time travel: This is just stupid, to be honest.</li> <li>The list goes on</li> </ul> <p>It seems that most of the applications used in comics are actually impossible. There is one that has caught my attention, though: the ability to create illusions.</p> <p>According to the theory, if a person moves fast enough, they can move back and forth at a speed great enough to cast the illusion of duplicates.</p> <h1>Is it possible to cause completely opaque illusions by moving back and forth at incredible speeds?</h1> <p>Let's say that a person spends 49.9999% of their time in one pose, and 49.9999% of their time in another pose. The remaining 0.0002% is spent transitioning between the two different poses.</p> <p>My theory: An outside observer would see two poses that are roughly 50% transparent. After all, each pose can't be in each location 100% of the time.</p> <p>A good example is that when you look at a ceiling fan turned on high, you can see everything that is behind the fan at the same time. A helicopter's propellers show this phenomenon, as well.</p>	[ { "answer_id": 157835, "author": "SRM", "author_id": 26246, "author_profile": "https://worldbuilding.stackexchange.com/users/26246", "pm_score": 0, "selected": false, "text": "<p>As long as you are above 60 frames (transitions from one location to the other) per second, most humans will ...	2019/10/07	[ "https://worldbuilding.stackexchange.com/questions/157834", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/68902/" ]	My story involves people with supernatural abilities. I want to create a character that has classic superspeed like the comic book superhero [The Flash](https://en.wikipedia.org/wiki/Flash_(comics)), but I want my character to only have realistic applications of such a power. Some applications I have already debunked: * Saving people: Grabbing people at lightning speed and then transporting them out of harm's way would just turn their insides into jelly, due to the sudden changes in speed. (Law of Conversation of Momentum) I do not accept mystical reasons like "the speed force protects them while in transit". In my story there is no "speed force". * Running up completely vertical walls indefinitely: Friction is needed to go up the wall. But to get friction, one needs to press their feet against the wall, which pushes them away from it. And then eventually they're not close enough to keep running up the wall. * Super speed in general: At higher speeds, the user would superheat the area around themselves, incinerating objects and people around themselves. This is caused by the friction of the air molecules; the same reason most objects burn up during atmospheric entry. * Time travel: This is just stupid, to be honest. * The list goes on It seems that most of the applications used in comics are actually impossible. There is one that has caught my attention, though: the ability to create illusions. According to the theory, if a person moves fast enough, they can move back and forth at a speed great enough to cast the illusion of duplicates. Is it possible to cause completely opaque illusions by moving back and forth at incredible speeds? ================================================================================================== Let's say that a person spends 49.9999% of their time in one pose, and 49.9999% of their time in another pose. The remaining 0.0002% is spent transitioning between the two different poses. My theory: An outside observer would see two poses that are roughly 50% transparent. After all, each pose can't be in each location 100% of the time. A good example is that when you look at a ceiling fan turned on high, you can see everything that is behind the fan at the same time. A helicopter's propellers show this phenomenon, as well.	I don't think it's possible while remaining within the bounds relative plausibility. This character has to be so fast that even The Flash might raise an eyebrow. I'll call the character UberFlash. So, let's say UberFlash tries to create two "illusions". He stands in one spot, then quickly goes to another and back. Visual diagram: ``` A <---> B ``` This has to be done multiple times a second. About the lowest frames per second you can get nowadays in video games is 30FPS. That means that an image is shown 30 times on the screen each second. This makes the transition between images seem like it's (mostly) non-existent and it's actually a continuous video. Some people can easily distinguish 30 FPS, as it "flickers" or "looks choppy" and otherwise doesn't maintains good illusion for a smooth stream of visual data. Still, I'm going to use 30 FPS as the baseline for UberFlash. Running to each spot 30 times. ============================== So, UberFlash has to show up in two places and stand at each 30 times over the course of one second. So he has to move between A and B 29 times in a second. Taking the proposed 0.0002% of time spend travelling, then UberFlash will have to move the ENTIRE distance 29 times in 0.0002% of a second, or 2 microseconds. For further reference, that's 0.002 milliseconds. That is the TOTAL time to make 29 trips. Let's say the two "illusions" are fairly close - 1m apart. If both "illusions held their hands outstretched, they would be touching or even overlapping. `(29 * 1m) / 0.002ms = ???` --------------------------- UberFlash has to be moving at about 14 500 m/s or 52 200 km/h. UberFlash can run a marathon in just under 3 seconds. Mach 1 speed (speed of sound) is about 1 235 km/h and going over it produces a sonic boom. UberFlash would be moving at roughly 42 times that speed. I don't think it would be very subtle or very safe for...anybody and anything. Running to each spot 10 times ============================= But perhaps 30FPS is too high. The "illusions" don't need to be perfect. Let's cut it down to 10 FPS - it will produce noticeable flickering of the images. Let's also make the distance smaller - 50cm, the two are almost shoulder to shoulder. Oh, and let's give UberFlash a bit more leniency - instead of 0.002 milliseconds, let's make it few orders of magnitude more and give him 1 millisecond. Just 1/1000th of a second to travel between the two locations. `(9*0.5m) / 1ms = ???` ---------------------- That means that UberFlash will move at 4 500 m/s or 16 200 km/h. Still more than 10 times the sonic boom speeds. I think at these speeds, aside from the images of UberFlash, there would be some high winds, loud noises, and maybe even flames around.
159,391	<p>Definition: Scientific laws or laws of science are statements that describe or predict a range of natural phenomena. A scientific law is a statement based on repeated experiments or observations that describe some aspect of the natural world. (wikipedia)</p> <p>Say a creature from a universe is trying to find magic. It does this by repeating an experiment 1000 times. He concludes that there is no magic, there is some regularity in the experiment and thinks it/he/she discovered a basic law of the universe. But what if the magic/a deeper underlying truth is revealed by only repeating the experiment 1 million + 1 times? </p> <p>Maybe the universe has some kind of code that looks like the following:</p> <pre><code>if (try <= 1000000) { return law1; } else { return law2 OR magic; } </code></pre> <p>Is there a way to determine that magical limit (1 million + 1) of retries without brute forcing it?</p> <p><strong>EDIT</strong>: Why is this being down-voted? Consider commenting if something needs to be improved with the question / you consider it bad for some reason.</p>	[ { "answer_id": 159393, "author": "Demigan", "author_id": 48354, "author_profile": "https://worldbuilding.stackexchange.com/users/48354", "pm_score": 2, "selected": false, "text": "<p>Maybe we've already found magic, but we just called it science instead.</p>\n\n<p>Your 1 in million trie...	2019/10/26	[ "https://worldbuilding.stackexchange.com/questions/159391", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/11498/" ]	Definition: Scientific laws or laws of science are statements that describe or predict a range of natural phenomena. A scientific law is a statement based on repeated experiments or observations that describe some aspect of the natural world. (wikipedia) Say a creature from a universe is trying to find magic. It does this by repeating an experiment 1000 times. He concludes that there is no magic, there is some regularity in the experiment and thinks it/he/she discovered a basic law of the universe. But what if the magic/a deeper underlying truth is revealed by only repeating the experiment 1 million + 1 times? Maybe the universe has some kind of code that looks like the following: ``` if (try <= 1000000) { return law1; } else { return law2 OR magic; } ``` Is there a way to determine that magical limit (1 million + 1) of retries without brute forcing it? EDIT: Why is this being down-voted? Consider commenting if something needs to be improved with the question / you consider it bad for some reason.	Maybe we've already found magic, but we just called it science instead. Your 1 in million tries would be assumed to be an error, an outlier, a problem with the scientific setup or computer glitch that should be ignored. But if you can repeat the process and it is actually usuable you can create laws for it. As an example of this happening is when a science team discovered that some particles were faster than light even with repeat tests. They asked others to perform the experiment and those found that it wasnt true and as far as I know they never discovered why the particles were measured to be faster but it was assumed that it was a glitch. As another example if we have a ball we can define its position and momentum. This is a process that can be repeated for just about any object at any point in time. But somehow for some reason if you do this for extremely small particles the quantum world suddenly pokes it's head through all the physics you created, and the more certain you know it's position the less certain its momentum becomes. Its just about everything you could want in magic in how it completely upends the normal physics. This process is now known as the Heisenberg's Uncertainty principle and this magic is "simply" a scientific discovery we use. And that is the problem, until a human can change the local laws of physics for a short time and repeat this any "magic" is simply a scientific law waiting to be discovered.
162,214	<p>For hundreds of years mathematicians have been looking for a method to quickly factorize a natural number.</p> <p>For example:</p> <pre><code>3894757 = 877*4441 </code></pre> <p>Today there's no way to perform prime factorization quickly (when it comes to big numbers). And cryptography is based on this fact.</p> <p>What could an algorithm for fast prime factorization look like?</p> <p>Is a Game Boy enough or does it take a quantum computer to run this algorithm?</p> <p>Are there other ways than having an algorithm to perform prime factorization quickly?</p>	[ { "answer_id": 162216, "author": "Priska", "author_id": 69280, "author_profile": "https://worldbuilding.stackexchange.com/users/69280", "pm_score": -1, "selected": false, "text": "<p>Knowing what a solution to an open math problem \"would look like\" amounts to knowing the solution (or a...	2019/11/27	[ "https://worldbuilding.stackexchange.com/questions/162214", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/70347/" ]	For hundreds of years mathematicians have been looking for a method to quickly factorize a natural number. For example: ``` 3894757 = 877*4441 ``` Today there's no way to perform prime factorization quickly (when it comes to big numbers). And cryptography is based on this fact. What could an algorithm for fast prime factorization look like? Is a Game Boy enough or does it take a quantum computer to run this algorithm? Are there other ways than having an algorithm to perform prime factorization quickly?	Assuming this has something to deal with worldbuilding, I'll give a worldbuilding answer. ========================================================================================= 1. Currently the best known method is to check all the primes less than the square root of the number to be factored. Quickly is a relative term, and mostly depends on the size of the primes involved. This poses a problem, as the method to factor quickly increases in speed, so does the ability to check larger and larger numbers for primality, this then increases the size of primes used to encrypt in the first place. 2. This means that any innovation used will only provide a temporary advantage to the side that has it as long as they keep it a secret. Once the secret is out, the systems will become secure again. 3. Any algorithm should be able to be run on any hardware, however the speed at which it can process is going to be the main issue. The super computer is going to be much faster than the game boy, and will be able to factor much larger numbers in a reasonable amount of time. 4. The field of quantum computing has theorized that it might be possible to use a quantum computer to harness infinite computing speed (essentially it would be able to compute anything in the same amount of time regardless of computing complexity).
170,641	<p>We have a variety of ways of describing our location here on Earth. We can refer to a nearby landmark (eg "by the City Hall"), we can describe our location relative to an area (eg "in the South of the island") and we can describe our location with Longitude and Latitude. It is the later of these methods I am interested in, but on the scale of the Universe.</p> <p>Obviously the Lat/Long system works because we have identified the North Pole, the South Pole and the Equator of the Earth. This allows us to give 2 arbitary numbers to locate any point on the globe. I am imagining that to have a similar coordinate system in the Universe we would also need to mark out some absolute points.</p> <p>Given that everything in space is always moving, what could be used as an absolute point in the Universe? The Big Bang perhaps? I considered having the observer as an absolute point, but I am unsure how this would create a reliable coordinate system that could be transfered to another observer.</p> <p>Whereas the Lat/Long system only requires 2 coordinates, I can imagine a Universal Coordinate system would require at least 3 coordinates. I have been considering adding time as a 4th coordinate, as everything is in a state of motion, knowing the time might help work out relative points if no absolute points can be found.</p> <p>In general I am struggling with how a Universal Coordinate System would work. Simple X, Y, Z coords (with 0,0,0 being Earth?) seem insufficient in a medium that is in a constant state of change.</p> <p>Has anyone else tackled such a system?</p>	[ { "answer_id": 170643, "author": "kleer001", "author_id": 63080, "author_profile": "https://worldbuilding.stackexchange.com/users/63080", "pm_score": 3, "selected": false, "text": "<p><strong>Orbital Mechanics!</strong> </p>\n\n<p>It's not a simple topic, but it's worth your time. They'r...	2020/03/06	[ "https://worldbuilding.stackexchange.com/questions/170641", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/320/" ]	We have a variety of ways of describing our location here on Earth. We can refer to a nearby landmark (eg "by the City Hall"), we can describe our location relative to an area (eg "in the South of the island") and we can describe our location with Longitude and Latitude. It is the later of these methods I am interested in, but on the scale of the Universe. Obviously the Lat/Long system works because we have identified the North Pole, the South Pole and the Equator of the Earth. This allows us to give 2 arbitary numbers to locate any point on the globe. I am imagining that to have a similar coordinate system in the Universe we would also need to mark out some absolute points. Given that everything in space is always moving, what could be used as an absolute point in the Universe? The Big Bang perhaps? I considered having the observer as an absolute point, but I am unsure how this would create a reliable coordinate system that could be transfered to another observer. Whereas the Lat/Long system only requires 2 coordinates, I can imagine a Universal Coordinate system would require at least 3 coordinates. I have been considering adding time as a 4th coordinate, as everything is in a state of motion, knowing the time might help work out relative points if no absolute points can be found. In general I am struggling with how a Universal Coordinate System would work. Simple X, Y, Z coords (with 0,0,0 being Earth?) seem insufficient in a medium that is in a constant state of change. Has anyone else tackled such a system?	Orbital Mechanics! It's not a simple topic, but it's worth your time. They're basically the 6 numbers required to describe the position in time and space of an object orbiting another object. So, the takeaway from that is if you want to describe the position of an object in space it'll need to be in reference to another object. That could be the galatic center if you're describing a solar system (or a spaceship in interstellar space), or the closest planet if you're describing a moon. And they'll need to be nested if you're describing the position of a moon around a planet from another galaxy. --- Why orbital mechanics? Because there are no privileged frames of reference in space. --------------------------------------------------------------- The Orbital Elements... To mathematically describe an orbit one must define six quantities, called orbital elements. They are ``` Semi-Major Axis, a Eccentricity, e Inclination, i Argument of Periapsis, ω Time of Periapsis Passage, T Longitude of Ascending Node, Ω ``` Their details require a bit of book learning I won't copy-paste here, but they're available lots and lots of places (wikipedia, your local library, your local astronaut, "SevenEves" from Neil Stephenson).
175,212	<p>A group of aliens are off to save the human race from extinction caused by a Lovecraftian monstrosity. </p> <p>In order to accomplish this feat, they go to Earth in order to harvest as many humans as possible to restart the race while keeping as much diversity in the gene pool as possible.</p> <p>The thing is, the aliens don't have time to introduce themselves and have the humans sort themselves out. So they arrive one day and start abducting people for the greater good. In order to store the humans they have acquired, they liquefy them in-order to save...how much space on their craft exactly?</p> <p>I would like to know how much volume a liquefied person takes up if they were stored in the most spatially-economical vessel (a cube or rectangle, though cylinders might be needed if under pressure.)</p> <p>The age groups I would like are:</p> <ul> <li><p>Toddlers</p></li> <li><p>Teenagers</p></li> <li><p>Adults</p></li> </ul> <p>(Don't question how they are liquefied only to come back normally afterwards. We are dealing with Clarketech here.)</p>	[ { "answer_id": 175213, "author": "L.Dutch", "author_id": 30492, "author_profile": "https://worldbuilding.stackexchange.com/users/30492", "pm_score": 5, "selected": false, "text": "<p>The <a href=\"https://www.syfy.com/syfywire/the-human-cube-the-volume-of-humanity\" rel=\"noreferrer\">av...	2020/04/28	[ "https://worldbuilding.stackexchange.com/questions/175212", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/69795/" ]	A group of aliens are off to save the human race from extinction caused by a Lovecraftian monstrosity. In order to accomplish this feat, they go to Earth in order to harvest as many humans as possible to restart the race while keeping as much diversity in the gene pool as possible. The thing is, the aliens don't have time to introduce themselves and have the humans sort themselves out. So they arrive one day and start abducting people for the greater good. In order to store the humans they have acquired, they liquefy them in-order to save...how much space on their craft exactly? I would like to know how much volume a liquefied person takes up if they were stored in the most spatially-economical vessel (a cube or rectangle, though cylinders might be needed if under pressure.) The age groups I would like are: * Toddlers * Teenagers * Adults (Don't question how they are liquefied only to come back normally afterwards. We are dealing with Clarketech here.)	How good is liquefaction? ------------------------- L.Dutch's answer is the right concept, but his numbers are wrong. 6 liters is the maximum inhalation of an average adult male; however, men have much larger capacity than women and normal respiration does not fully inflate the lungs. The 62 liter volume of an average adult assumes a resting inhalation volume which actually averages closer to 2.5 liters of air in your lungs (during normal at-rest breathing across genders). Volumes of gastro intestinal gases vary a lot throughout the day, but average about 1 liter. This means his equation should look more like 3.5/(62+3.5) = 5%; so, you only get a 5% reduction in absolute volume. That said, the more important savings are in removing the empty spaces around the body. An average human is 160x39x23cm that is 143.52 liters. When you compare that to the 58.5 liter liquid state of a human, you get 143.52/(143.52+58.5) = 71%; so, your reduction in practical volume would be 71% compared to shoving us in boxes. This will result in the following: ``` Age Group \| Avg. Whole Weight \| Avg. Volume ----------------------------------------------------- 2yr old Toddler 12,000 g 11,100 cm^3* 13yr old Teenager 45,000 g 41,600 cm^3* Adult 62,000 g 58,500 cm^3 Due to lack of data, child volumes are based on mathematical ratios compared to adults. Different childhood ratios of bone, muscles, organs, etc might impact these figures. ``` Designing the packaging:* To package your humans this way, place thier remains in large plastic bags kind of like IV bags. This will keep your remains separate, sterile, and waste very little space. That said, because some fluids such as stomach acid would react with other fluids such as brain chunks, you may in fact want to store certain biological substances separately rather than in on big bag to make sure you still have all the same compounds coming out as you had going in. This may mean a complex system of "disassembling" the human body into seperate bags rather than just throwing them into a blender. This can lead to some unexpected wasted space as you start needing to account lots of total bag materials, air gaps between bags, and possibly wasted space in whatever bins you use to keep all the liquid human sacs organized in. It's hard to say just how much space will be wasted without delving REALLY deep into human biochemistry and industrial design to determine how many bags and of what size you need; so, lets just say it will still be more efficient than boxing whole humans, but maybe closer to a 50-60% savings if you go this rought. [![enter image description here](https://i.stack.imgur.com/5mb7I.png)](https://i.stack.imgur.com/5mb7I.png) But, your aliens could do better -------------------------------- Generally I agree with Carl's assessment that you don't need to bring whole people, but cloning humans requires large artificial wombs, and lot of labor for your aliens to hang around baby sitting us for 20 years waiting for us to have a functional adult population while our DNA synthesizes all the complex compounds (proteins, fats, nucleic acids, carbohydrates, etc.) that make up an adult. Instead of a slurry which is 60% water, you could dehydrate the human pulp into a "meat and bone meal". This is an industrial term referring to the dehydrated and ground up remains of an animal. Since any planet they are bringing us to would inevitably contain lots of water, they would just need to rehydrate our remains as part of the reconstitution process using the water from our new world. <https://en.wikipedia.org/wiki/Meat_and_bone_meal> says that meat and bone meal averages 4–7% water (I will use 5% to simplify the math); so, if you reduce the human body from 60% water to 5%, you are eliminating about 55% of a human's total mass. According to [calcert.com](https://calibration-services.calcert.com/Asset/Bulk%20Density%20Chart.pdf), loose meat and bone meal is has a density of 0.72 g/cm^3. This is a bit less than our liquid density because the powder will have room for air, but will still have a lower total volume than liquid humans while allowing the aliens to transport all of our complex compounds needed to put us back together. This will result in the following: ``` Age Group \| Avg. Whole Weight \| Avg. Dry Weight \| Avg. Volume ----------------------------------------------------------------------- 2yr old Toddler 12,000 g 5,400 g 7,500 cm^3* 13yr old Teenager 45,000 g 22,250 g 30,902 cm^3* Adult 62,000 g 27,900 g 38,750 cm^3* Due to lack of data, meat and bone meal density is based on animal meal. Human meal might be slightly more or less dense. ``` If the remains are vacuum sealed like coffee, you could increase the density of your meal to be just a bit over 1 g/cm^3; however, vacuums cause most organic compounds to break down; so, depending on how advanced your alien tech is will determine how much they can safely compress your human remains. Going back to the practical volume of a human, this means you will get somewhere between a 79 and 84% practical reduction in volume by converting people to meat and bone meal. That is about 34-53% more efficient than liquefaction (ignoring any differences in packaging processes). If you opt for liquefaction in your story, I would suggest giving some brief handwave explanation for why you can not dehydrate the human remains. Designing the packaging:* Another possible advantage to removing water from the human body is that it makes freezing us far less destructive. Water expands when freezing which plays havoc on on the other molecules being frozen with it. The Arrhenius equation shows that as things cool, things that react at higher temperatures stop reacting with one another. This means you can deep freeze stomach acid and dehydrated brain chunks together without them reacting with one another such that you can get an even better efficiency out of your packaging by keeping us in one very cold container. Even under low-vacuum states, vacuum sealed plastic and foil cubes are probably the best way to store and separate human remains because they maintain a sterile, light weight, easily stored, separate vessel for each human, and can be shaped into cubes for optimal space efficiency. To figure out how big these cubes have to be we should look at the top end of who the aliens might select for transport. If they want to save the species, they will probably select people based on health factors meaning the obese and dangerously tall may be excluded. This puts a reasonable upper limit of 115kg on your whole weight. If we assume a light vacuum seal will compress the meal density to about 0.85 g/cm^3, then we get a finished volume of about 60,882cm^3 or a cube that is about 39x39x39cm. [![enter image description here](https://i.stack.imgur.com/TrK1Q.png)](https://i.stack.imgur.com/TrK1Q.png) If it were me, I would describe the human storage room as being a cryogenically cooled cargo bay full of pallets of vacuum sealed blocks, all ~39x39cm at the base so that they stack nicely, but ranging from ~4-39cm tall. By mixing and matching people of various volumes, each pallet could be filled to the maximum height recommended by alien freight regulations. In conclusion: There are many factors that could play into how you could and should store a disintegrated human, and it all boils down to "how destroyed is too destroyed to reassemble." Hopefully this goes into enough (though be it disturbing) detail to figure out how compressed your humans should be.
176,057	<p>This is yet another "literal worldbuilding" question, as in, building worlds. Inspired, in part, by <a href="https://worldbuilding.stackexchange.com/q/27396/32642">this question</a>.</p> <p>What if this world is a very long (effectively infinite) hollow cylindrical cavity with the diameter roughly equal to that of the Earth's orbit. The day/night cycle is generated by the following arrangement: multiple suns falling through the center of the cylinder. The distance between the suns and their speed relative to the world surface are adjusted to generate approximately 24 hours cycle, just like on Earth.</p> <p><a href="https://i.stack.imgur.com/qkLmt.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/qkLmt.png" alt="enter image description here"></a></p> <p>While there are several issues with this idea, most importantly huge tidal waves generated by the gravity of the suns, and the fact that empty space inside will be quickly filled with matter both from the suns and the cylinder itself, let's ignore them for now.</p> <p>This question is simple enough:</p> <ul> <li>What would the sky at some point on the surface look like during day and night, as well as dawn and twilight? By that I mean, how would the suns move, how would the lighting change, etc. How different would it be from our own experiences?</li> </ul> <p>I would like the answer based on actual geometry and optics. I have poor spatial imagination which is why I need some help with that :)</p> <p>The suns should be spaced enough so that the night is mostly dark, though of course we can't avoid some light, since there's no horizon. The size and the energy output of the suns can be modified as well, because the cylinder would collect all the energy, radiation and solar wind, which could be too much.</p> <p>Optionally, I would also like to see what other problems arise with this arrangement, though I could ask a separate question for that.</p> <hr> <p>There's a similar "tube world" arrangement in <a href="https://worldbuilding.stackexchange.com/q/30933/32642">this question</a>, but it's a little too complicated and can't be used to answer my question.</p> <hr> <p>Just to clarify: I want this world to support flora and fauna as close to Earth-like (temperate climate) as possible.</p>	[ { "answer_id": 176062, "author": "AlexP", "author_id": 29552, "author_profile": "https://worldbuilding.stackexchange.com/users/29552", "pm_score": 2, "selected": false, "text": "<h2>First pass: the geometry is simple</h2>\n\n<p>In the first pass, we disregard the cylindrical shape of the...	2020/05/10	[ "https://worldbuilding.stackexchange.com/questions/176057", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/32642/" ]	This is yet another "literal worldbuilding" question, as in, building worlds. Inspired, in part, by [this question](https://worldbuilding.stackexchange.com/q/27396/32642). What if this world is a very long (effectively infinite) hollow cylindrical cavity with the diameter roughly equal to that of the Earth's orbit. The day/night cycle is generated by the following arrangement: multiple suns falling through the center of the cylinder. The distance between the suns and their speed relative to the world surface are adjusted to generate approximately 24 hours cycle, just like on Earth. [![enter image description here](https://i.stack.imgur.com/qkLmt.png)](https://i.stack.imgur.com/qkLmt.png) While there are several issues with this idea, most importantly huge tidal waves generated by the gravity of the suns, and the fact that empty space inside will be quickly filled with matter both from the suns and the cylinder itself, let's ignore them for now. This question is simple enough: * What would the sky at some point on the surface look like during day and night, as well as dawn and twilight? By that I mean, how would the suns move, how would the lighting change, etc. How different would it be from our own experiences? I would like the answer based on actual geometry and optics. I have poor spatial imagination which is why I need some help with that :) The suns should be spaced enough so that the night is mostly dark, though of course we can't avoid some light, since there's no horizon. The size and the energy output of the suns can be modified as well, because the cylinder would collect all the energy, radiation and solar wind, which could be too much. Optionally, I would also like to see what other problems arise with this arrangement, though I could ask a separate question for that. --- There's a similar "tube world" arrangement in [this question](https://worldbuilding.stackexchange.com/q/30933/32642), but it's a little too complicated and can't be used to answer my question. --- Just to clarify: I want this world to support flora and fauna as close to Earth-like (temperate climate) as possible.	Let me start with the additional problems that arise: * The trajectory of the suns is not stable. If they are slightly off-center, gravity will pull them towards the side of the cylinder that they're closer to, analogous to the [ringworld stability issue](https://physics.stackexchange.com/questions/41254/why-is-larry-nivens-ringworld-unstable). You could work around this by using stellar engines of some sort to keep the stars centered, or making the cylinder a tiny bit flexible and using motors to change its shape dynamically.... * There is nowhere for the heat that is generated by fusion in the cores of the suns to escape, apart from conduction through the crust towards outside space. You could work around this by putting large holes in your cylinder through which outside space is visible, by making your crust very thin (on the order of meters), or by making it very conductive (by adding an active cooling system that pumps heat outside). This oversimplified illustration shows the relevant mechanisms that keep earth's surface at its equilibrium temperature, and how the inside of your cylinder would heat to over 2 million Kelvins without any countermeasures: [![](https://i.stack.imgur.com/N8f2m.png)](https://i.stack.imgur.com/N8f2m.png) Now, to your actual question. The only relevant parameter is the distance between the suns, in AU. The speed at which they move follows automatically from your requirement that one sun should pass every 24 hours. It will be rather high, though :) You will, of course, always see an infinite number of suns, but most of them will be very dim and very close to the horizon. Here's what the sky will look like, with the apparent brightness of the suns (= the area they occupy in the sky) written next to the dots. suns spaced at 1AU: [![](https://i.stack.imgur.com/IasyE.png)](https://i.stack.imgur.com/IasyE.png) suns spaced at 20AU: [![](https://i.stack.imgur.com/yiOHa.png)](https://i.stack.imgur.com/yiOHa.png) To calculate the total illumination, some math is required. You need to calculate the [infinite sum of the contributions of each sun](https://www.wolframalpha.com/input/?i=sigma%28x+%3D+-inf+to+%2Binf%29+of+1%2F%281%2B%28d%28x%2Bo%29%292%29). In this formula, `d` is the distance between the suns in AU, and `o` is the offset from mid-day, where `o=0` means mid-day, and `o=1` means mid-day tomorrow. This gives the following equation for the momentary strength of illumination (assuming that the power output of one sun at 1AU distance is 1): `-(π sinh((2 π)/d))/(d (cos(2 o π) - cosh((2 π)/d)))` To find your preferred value of `d`, just plot this formula for various values. Here's a quick python snippet that does exactly that, since I couldn't get nice plots out of Wolfram Alpha: ``` #!/usr/bin/env python3 from argparse import ArgumentParser from math import sqrt, sinh, cos, cosh, pi import numpy from matplotlib import pyplot as plt cli = ArgumentParser() cli.add_argument('--distance', type=float, default=1) cli.add_argument('--average-illumination', type=float, default=0.25) args = cli.parse_args() power = 0.31831 args.average_illumination * args.distance hours = numpy.arange(0, 24, 1/60) illuminations = [] for hour in hours: offset = hour / 24 - 0.5 illuminations.append( -power * pi * sinh((2 * pi)/args.distance) / (args.distance * (cos(2 * offset * pi) - cosh((2 * pi)/args.distance))) ) fig = plt.figure() ax = fig.add_subplot(1, 1, 1) ax.set_xticks(range(25)) ax.set_xlim(0, 24) ax.set_yscale('log') ax.grid() ax.plot(hours, illuminations) ax.set_title(f'spacing: {args.distance} AU, ' f'luminosity: {power} L0, ' f'min: {min(illuminations):.5g}, ' f'max: {max(illuminations):.5g}') # from https://en.wikipedia.org/wiki/Lux#Illuminance ax.annotate("moonless clear sky with airglow", (0.5, 0.002/100e3)) ax.annotate("full moonlight", (0.5, 0.3/100e3)) ax.annotate("dark limit of civil twilight", (0.5, 3.4/100e3)) ax.annotate("family living room lighting", (0.5, 50/100e3)) ax.annotate("very dark overcast day", (0.5, 100/100e3)) ax.annotate("sunrise or sunset on clear day", (0.5, 500/100e3)) ax.annotate("overcast day", (0.5, 1000/100e3)) ax.annotate("indirect daylight", (0.5, 10000/100e3)) ax.annotate("full daylight", (0.5, 1)) # from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5718773/ ax.annotate("survivable for minutes in firefighter's clothing", (0.5, 2)) ax.annotate("survivable in aluminized clothing", (0.5, 4)) plt.show() ``` And plots for some distances: [![](https://i.stack.imgur.com/JGib0.png)](https://i.stack.imgur.com/JGib0.png) [![](https://i.stack.imgur.com/8eXj4.png)](https://i.stack.imgur.com/8eXj4.png) [![](https://i.stack.imgur.com/VeeAE.png)](https://i.stack.imgur.com/VeeAE.png) [![](https://i.stack.imgur.com/Rlv3O.png)](https://i.stack.imgur.com/Rlv3O.png) [![](https://i.stack.imgur.com/H3oNs.png)](https://i.stack.imgur.com/H3oNs.png) Distances above 180AU are impossible because then the suns would be moving faster than the speed of light; decreasing the cylinder diameter would solve this. In these cases, I try to maintain the same average heat flux that is experienced on earth, to allow meaningful photosynthesis. You can see that if you want proper darkness at night, there will be short hard bursts of heat which will only be survivable in underground bunkers. If you're willing to reduce the average heat flux to say 1% of that experienced on earth, that is, around 3 W/m², you can achieve this: [![](https://i.stack.imgur.com/CwtlA.png)](https://i.stack.imgur.com/CwtlA.png) With only 1% of the power flux, you will only have 1% of the photosynthesis, solar power, wind power, fossil fuel formation etc, so your land will generally only support 1% of earth's population density. Advanced civilizations may however harvest tidal power from the tidal accelerations of the passing stars, and "reverse geothermal" power from the heat flux through the crust. This heat flux will be far stronger than on earth. Other interesting effects which I haven't considered: * the light of very-far-away suns will travel a long path through the atmosphere; this means that their light will be scattered and they won't be actually visible properly. It's just like the sun gets distorted and reddish during sunset, only the effect will be literally infinitely stronger. * there will be effects from special relativity: the light of approaching stars is blue-shifted, and their power output will appear different since time passes at a different rate in the star's cores. * since the light of oncoming stars will be blue-shifted and the light of receding stars will be red-shifted, there will be a constant radiation pressure in the direction in which the stars are moving. this will accelerate the atmosphere, causing westward wind. I'm not sure how to calculate the strength, though. Solar wind particles will have a similar effect. There's another great way in which you could achieve day and night, though: Your population could live in a narrow valley such that only suns that are above 30-or-so degrees over the horizon are actually visible. There will still be atmospheric scattering, but some tinkering with the atmospheric composition could fix that.
177,022	<p>I find myself in need of the rules and text body of an oath for a magic and/or devil contract.</p> <p>Here are my thoughts:</p> <ol> <li><p>Does magic rely on the collective subconscious, or personal minds involved to provide subjective definitions of all words in the spell? <em>(I.E. can re-learning on a truly deep level is possible, but very hard, as in real life)</em></p></li> <li><p>If there is a physical manifestation of the contract, is all logic and/or wording fixed because is not subject to memory faults, or is it in the mind of the contract holder?</p></li> <li><p>How does the contract effect the mind? Internalizing it directly, or by another means? <em>(Ideas)</em></p> <ul> <li>(a) placebo (any symptoms or effects as directed in the contract)</li> <li>(b) Executive dysfunction</li> <li>(c) that thing I could never find a name for, but is like this: driving to work when I meant to go home from the store</li> </ul></li> <li>Visual or auditory delusions (any symptoms or effects the mind can produce as directed in the contract)</li> </ol> <p>Here is what a rough sketch of logic that I have so far: <em>(based on the laws of robotics)</em></p> <pre><code> * You shall not by any act of yours harm me, or, by inaction, allow me to come to harm * You shall obey the orders given you by me except where such orders would conflict with clauses preceding this * You shall protect your own existence as long as such protection does not conflict with clauses preceding this * You shall take no chances in the failure of my orders except where such orders would conflict with clauses preceding this * You shall if your hand is forced, take the course of lesser deviation over greater deviation of any order except where such orders would conflict with clauses preceding this </code></pre> <p>Am I missing anything? Is there a loophole, or something incomplete or to vague?</p> <p>Last but not least: what is the best way to translate this into a contract?</p> <p><em> EDITED FOR CLARITY </em></p>	[ { "answer_id": 177029, "author": "Slarty", "author_id": 42450, "author_profile": "https://worldbuilding.stackexchange.com/users/42450", "pm_score": 3, "selected": false, "text": "<ul>\n<li>These laws are the ultimate authority controlling your behaviour</li>\n<li>These laws may be change...	2020/05/23	[ "https://worldbuilding.stackexchange.com/questions/177022", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/48591/" ]	I find myself in need of the rules and text body of an oath for a magic and/or devil contract. Here are my thoughts: 1. Does magic rely on the collective subconscious, or personal minds involved to provide subjective definitions of all words in the spell? (I.E. can re-learning on a truly deep level is possible, but very hard, as in real life) 2. If there is a physical manifestation of the contract, is all logic and/or wording fixed because is not subject to memory faults, or is it in the mind of the contract holder? 3. How does the contract effect the mind? Internalizing it directly, or by another means? (Ideas) * (a) placebo (any symptoms or effects as directed in the contract) * (b) Executive dysfunction * (c) that thing I could never find a name for, but is like this: driving to work when I meant to go home from the store 4. Visual or auditory delusions (any symptoms or effects the mind can produce as directed in the contract) Here is what a rough sketch of logic that I have so far: (based on the laws of robotics) ``` * You shall not by any act of yours harm me, or, by inaction, allow me to come to harm * You shall obey the orders given you by me except where such orders would conflict with clauses preceding this * You shall protect your own existence as long as such protection does not conflict with clauses preceding this * You shall take no chances in the failure of my orders except where such orders would conflict with clauses preceding this * You shall if your hand is forced, take the course of lesser deviation over greater deviation of any order except where such orders would conflict with clauses preceding this ``` Am I missing anything? Is there a loophole, or something incomplete or to vague? Last but not least: what is the best way to translate this into a contract? \\* EDITED FOR CLARITY \\*	I was reached out to (Original document credit: [<https://docs.google.com/document/d/1wmCHSse_Sdl9A9kD0qdruRC74PKctF_zaB2MvNT7TdY/edit]> ), here is the result: Magickly binding Declaration of Service Between Warlock and Master ● Sec. I- ACKNOWLEDGEMENT OF THE SCROLL ○ It is hereby agreed upon by all involved signatories and/or their authorized adjudicators, executors, or other such employed personnel to which power of signatory has been bestowed that entering into this contract (hereby referred to as “the compact”), which is Magickly binding under the solemn oath, each party signing this Scroll (hereby referred to as “the Contractor”)-- whether manifested as a literal Item, such as a scroll, parchment, or other such surface upon which is printed or arranged some kind of marking which when read imparts the knowledge of impression of the words of its creator, or some other form of verbal, non-verbal, spiritual, magical, or emotional language which is leveraged to impart the same meaning-- upon which the compact has been inscribed, imbued, performed, or otherwise conveyed (hereby referred to as “the Scroll”) enters into a completely and wholly binding agreement between compatriots in business pursuits, personal pursuits, or any possible combinations thereof that might come to the recognition of any of the parties and/or the original author of this Scroll (hereby referred to as “the author”) that the party or parties and the author shall, under penalty of forfeiture of Soul, be agreed that they shall each and all acknowledge any other party or parties, including the author, are bound to the obligations outlined and/or implied within the words, language, and/or subtext of the compact. ● Sec. II- ACKNOWLEDGEMENT OF PARTIES ○ Sec. II §A- The Master ■ The name signed below (hereby referred to as “the Master”), and/or the authorized adjudicators, executors, or other such employed personnel to which power of signatory has been bestowed, is bound by Oath to uphold their end of any and all pacts, outlined in Sec. III, entered into as a result of this compact. ``` Signature _________________________________________ ``` ○ Sec. II §B- The Warlock ■ The name signed below (hereby referred to as “the Warlock”), and/or the authorized adjudicators, executors, or other such employed personnel to which power of signatory for life, mind, and soul, has been bestowed, is bound by this Scroll in Blood, Magic, and Oath (hereby referred to as “the Oath”), to uphold their end of any and all pacts, outlined in Sec. III, entered into as a result of this compact. ``` Signature __________________________________________ ``` ● Sec.III- ACKNOWLEDGEMENT OF PACTS ○ Sec. III §A- Defining Pacts ■ It is hereby agreed that the benefits, boons, payments, or exchange of goods, services, or other such favors, are offered in sequential order (hereby referred to as “pact” or “pacts”). By entering into this compact, the Contractor understand and agree to provide the benefits, boons, payments, or exchange of goods, services, or other such favors outlined under the first pact, as described in Sec.III §B. The parties agree that, by entering into an additional pact or pacts outlined in this Scroll, any previous pacts are considered to still be in effect, and any such benefits, boons, payments, or exchanges of goods, services, or other such favors rendered from previous pacts are still Magickly binding under Oath. Both parties understand that if, at any point, one or both parties are found in breach of contract, as defined later in Sec. IV, the offending party or parties are to immediately, at the time of being found in breach of contract, make payment to the other party or parties as defined in Sec V. Agreement to enter the second and/or third pacts, as outlined later in Sec. III, is defined as either mutual written consent of both the Master and Warlock, as signified by signing of appropriate pact or pacts upon entering said pact or pacts, or verbal consent between the Master and Warlock to enter the second and/or third pact or pacts. Should both parties verbally consent to enter into the second and/or third pact or pacts, the names of the Master and Warlock shall instantly appear on the signature lines provided for said pact or pacts through magic granted to this Scroll by the Oath. ○ Sec. III§B- The First Pact ■ Sec. III§B Article 1- Duties of the Warlock ● The Warlock agrees to, upon signing this Scroll, and moving forward in perpetuity, give claim and ownership of their immortal soul to the Master, with which the Master may do as the Master sees fit. Upon death, brain death, irreversible coma, or other such ending of normal functioning of the Warlock (hereby referred to as “death”), the soul will immediately be sent to the Master. The Warlock, upon signing this Scroll, revokes any and all claim to their immortal soul, and agrees not to interfere with the travel of their soul to the Master in any way, shape, or fashion, or the Warlock will be found in breach of contract as outlined later in Sec. IV. The Warlock also consents to the Master’s use of telepathy, mind reading, or other such form of communication on the Warlock. Signature \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ ■ Sec. III§B Article 2- Duties of the Master ● The Master agrees to, upon signing this Scroll, heal any physical ailments, illnesses, maladies, or other such afflictions present in the Warlock’s body at the time of the signing of this Scroll. The Master is NOT required to heal any ailments, illnesses, maladies, or other such afflictions not present at the time of the signing of this Scroll that may or may not appear at a later time. Signature \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ ○ Sec. III§C- The Second Pact ■ Sec. III§C Article 1- Duties of the Warlock ● The Warlock agrees to, upon entering into the second pact and moving forward in perpetuity, follow in completion the spirit of the order given to them by the Master. Completion, or as such time where the task should be complete has passed, will have the Warlock return to, seek out, or otherwise communicate with, the Master for further orders. No subterfuge will be taken as to the purpose of these actions. Furthermore, all possessions of the Warlock will be forfeit to the Master. Upon entering into the second pact, strict legal action up to and including execution, will be taken against any beings attempting to prevent this, as defined in Sec. III§C, Article 1, Title i. Signature \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ ○ Sec. III§C Article 1, Title i.- Possessions ■ Possessions hereby referenced in this contract refers to all current and future lands, settlements, colonies, titles, vassals, and capital under the direct and/or indirect control of the Warlock beginning at the time of signing and in perpetuity. ■ Sec. III§C Article 2- Duties of the Master ● The Master agrees to, upon entering into the second pact, immediately bestow upon the Warlock one (1) named sword, and one (one) animal companion (hereby referred to as “The Boon” or “boon”) which will service to aid and be companion to the Warlock. This Boon shall remain under the command of and dedicated to the Warlock for thirty (30) consecutive days, to begin immediately after entering into the second pact. Any of this Boon slain, abandoned, dismissed, broken, or otherwise parted from the Warlock, is ab solved of their service to the Warlock in perpetuity, as described in Sec. III§C Article 2 Title i. Signature \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ ○ Sec. III§C Article 2 Title i.- Boon ■ Members of the aforementioned Boon shall be considered slain, abandoned, dismissed, broken, or otherwise parted from the Warlock if they are met with such damage that their corporeal casings are destroyed and their souls sent back to the Master. Units of this Boon cannot, through any action or inaction, deliberately and knowingly allow themselves to be slain, abandoned, dismissed, broken, or otherwise parted from the Warlock for the purposes of being released from servitude to the Warlock. ○ Sec. III§D- The Third Pact ■ Sec. III§D Article 1- Duties of the Warlock ● Upon entering into the third pact, the Warlock agrees to permanently, and in perpetuity, accept the influence of the Master, and, install three (3) chosen of the Master into high ranking positions of power of the Master’s choosing within the community of the Warlock, as described in Sec. III §D Article 1, titles i, ii, and iii. Signature \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ ○ Sec. III §D Article 1 title i- Magical Geas ■ The Warlock shall not by any act of yours harm the Master, or, by inaction, allow the Master to come to harm ■ The Warlock shall obey any and all orders given it by the Master ■ The Warlock shall protect your own existence as long as such protection does not harm the Master ■ The Warlock shall take no chances in the failure of my orders ■ The Warlock shall, if its hand is forced, take the course of lesser deviation over greater deviation of any order. ○ Sec. III §D Article 1 title ii- Scope of the Geas ■ These laws are the ultimate authority controlling your behavior, both physically and mentally ■ I will always be the ultimate arbiter of any dispute concerning the law ○ Sec. III §D Article 1 title iii- The fine print: Influence ■ placebo (any symptoms or effects as directed by the Master) ■ Directed Executive Dysfunction ■ that thing I could never find a name for, but is like this: driving to work when I meant to go home from the store ■ Visual or auditory delusions (any symptoms or effects the mind can produce as directed by the Master). ■ Sec. III §D Article 2- Duties of the Master ● Upon entering into the third pact, the Master agrees to bestow upon the relatives of the Warlock, as defined in Sec. III§D Article 2 Title i, powers and abilities beyond their grasp, as defined in Sec. III §D Article 2 Title ii. Signature \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ ● Sec. III §D Article 2 Title i- Relatives of the Warlock ○ Relatives of the Warlock, for the purposes of this pact, are defined exclusively as: biological, non-adoptive mother of the Warlock (hereby referred to as “mother”); biological, non-adoptive father of the Warlock (hereby referred to as “father”); biological, non-adoptive brothers and/or sisters of the Warlock who shares both the mother and father of the Warlock (hereby referred to as “brother” or “sister”); singular, monogamous, living husband or wife of the Warlock currently, at the time of entering into this pact (hereby referred to as “spouse”), and/or biological, non-adoptive sons and/or daughters of the Warlock and spouse (hereby referred to as “son” or “daughter”). ● Sec. III §D Article 2 Title ii- Powers bestowed upon relatives ○ The powers bestowed upon the relatives of the Warlock, as described in Sec. III §D Article 2 Title i, which shall allow the wielder of such power (hereby referred to as “wielder” or “the wielder”) the ability to heal any mundane, non-magical, non-divine, non-infernal, or other such physical illnesses, ailments, maladies, or other such afflictions affecting the body of the wielder. In addition, these powers will allow the wielder to rend the mind of their mundane, mortal, non-elemental enemies (hereby referred to as “target”), this act will harm the mind of the target in direct and equal proportion to the mana used. These powers may not be wielded, armed, or otherwise used against the Master, or any such person or persons baring the personal crest of the Master, or the Warlock will be found in breach of contract, as outlined later in Section IV. ● Sec. IV- ACKNOWLEDGEMENT OF BREACH OF CONTRACT ○ Sec. IV §A- Breach of Contract on the part of the Warlock ■ Should the Warlock, at any time after entering into this compact and in perpetuity, through any action, inaction, spoken or unspoken word, thought, feeling, or other such gesture, interfere with the Master claiming the immortal soul of the Warlock, the Warlock shall be found in breach of contract. ■ Should the Warlock, at any time after entering into this compact and in perpetuity, through any action, inaction, spoken or unspoken word, thought, feeling, or other such gesture, enter a state of death as defined in Sec. III §B Article 1, the Warlock shall be found in breach of contract. ■ Should the Warlock, at any time after entering into this compact and in perpetuity, through any action, inaction, spoken or unspoken word, thought, feeling, or other such gesture, lose control or other such power over the community for any discernible amount of time, to any creature, being, or other such entity except those explicitly outlined in Sec. III §D Article 1, the Warlock shall be found in breach of contract. ■ Should the Warlock, at any time after entering into the second pact and in perpetuity, through any action, inaction, spoken or unspoken word, thought, feeling, or other such gesture, allow or permit the worship of, prayer to, offering to, or any such gesture to any god, demigod, spirit, deity, or other such non-infernal entity, the Warlock shall be found in breach of contract. ■ Should the Warlock, at any time after entering into the second pact and in perpetuity, through any action, inaction, spoken or unspoken word, thought, feeling, or other such gesture, upon discovering, learning, or in any way becoming aware of the worship of, prayer to, offering to, or any such gesture to any god, demigod, spirit, deity, or other such non-infernal entity, not take immediate legal action culminating in the execution of the perpetrator of such act or acts within one week after being made aware of such act and in perpetuity, the Warlock shall be found in breach of contract. ■ Should the Warlock, at any time after entering into the third pact and in perpetuity, through any action, inaction, spoken or unspoken word, thought, feeling, or other such gesture, hinder, impede, or in any way stand in the way of the goals of the Master, as outlined in Sec. III §D Article 1, the Warlock shall be found in breach of contract. ■ Should any or all relatives of the Warlock, at any time after entering into the third pact and in perpetuity, through any action, inaction, spoken or unspoken word, thought, feeling, or any other such gesture, wield, arm, or otherwise use their powers granted to them under Sec III §D Article 2 Title i against the Master, or those in his livery, the Warlock shall be found in breach of contract. ○ Sec IV §B- Breach of Contract on the part of the Master ■ Should the Master, upon entering into the compact, fail to heal any physical illnesses, ailments, maladies, or other such afflictions present in the body of the Warlock at the time of entering into the compact, of which the Master would feasibly know or be made aware of upon entering into this compact, the Master shall be found in breach of contract. ■ Should the Master, upon entering into the compact and in perpetuity, take any direct action leading to the death of the Warlock, the Master shall be found in breach of contract. ■ Should the Master, upon entering into the second pact, fail to provide the Boon bestowed upon the Warlock as outlined in Sec III §C Article 2, the Master shall be found in breach of contract. ■ Should the Master, upon entering into the second pact, through direct action on the part of the Master, remove the Boon described in Sec. III§C Article 2, the Master shall be considered in breach of contract. ■ Should the Master, upon entering into the third pact, fail to provide powers to the relatives of the Warlock as described in Sec III §D Article 2, the Master shall be found in breach of contract. ● Sec. V- ACKNOWLEDGEMENT OF PAYMENT IN BREACH OF CONTRACT ○ Sec. V §A- Payment on the part of the Warlock ■ Should the Warlock be found in breach of contract, as defined in Sec. IV §A, at any point after entering into the compact and in perpetuity, the Warlock agrees to forfeit their immortal soul to the Master. In addition, the Warlock shall provide any and all boons, benefits, or any exchange of goods, services, or other such favors on the part of the Warlock outlined in any and all pacts listed within the compact, whether said pact or pacts have been entered into or not at the time of the Warlock being found in breach of contract, to the Master immediately upon the Warlock being found in breach of contract. Any boons, benefits, or any exchange of goods, services, or other such favors on the part of the Master are considered null and void upon the Warlock being found in breach of contract. ○ Sec. V §B- Payment on the part of the Master ■ Should the Master be found in breach of contract, as defined in Sec. IV §B, at any point after entering into the compact and in perpetuity, the Master agrees to return claim and ownership of the Warlock’s immortal soul back to the Warlock. Any and all boons, benefits, or any exchange of goods, services, or other such favors on the part of the Warlock shall be considered null and void in the event of the Master being found in breach of contract. In addition, if the Master is found in breach of contract, the Master agrees to serve under the command of and be bound to the Warlock, for a period of 1000 consecutive years, to begin immediately after the Master is found in breach of contract. In the event of the death of the Warlock, the Master is absolved of any such obligation in perpetuity.
180,629	<p>I am working on a hard(ish) science fiction space opera story, and I would like to get a good handle on distances between stars so that I can calculate appropriate travel times. There are a lot of resources online to find how far stars are from here - for example, Tau Ceti is 11.89 light-years away and Ross 248 is 11.32 light-years away - but how far is Tau Ceti from Ross 248? Is there any easy way to find out?</p>	[ { "answer_id": 180630, "author": "The Square-Cube Law", "author_id": 21222, "author_profile": "https://worldbuilding.stackexchange.com/users/21222", "pm_score": 5, "selected": false, "text": "<p>I don't know if there is any catalogue that will give you the information you need. You will ...	2020/07/14	[ "https://worldbuilding.stackexchange.com/questions/180629", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/77128/" ]	I am working on a hard(ish) science fiction space opera story, and I would like to get a good handle on distances between stars so that I can calculate appropriate travel times. There are a lot of resources online to find how far stars are from here - for example, Tau Ceti is 11.89 light-years away and Ross 248 is 11.32 light-years away - but how far is Tau Ceti from Ross 248? Is there any easy way to find out?	An exact answer --------------- The position of a star in space can be specified by three coordinates: Its right ascension, $\alpha$, its declination, $\delta$, which are collectively referred to as equatorial coordinates, and its distance from Earth, $d$. It's probably easiest to calculate the distance between two stars by converting equatorial coordinates to Cartesian coordinates: $$x=d\cos\delta\cos\alpha$$ $$y=d\cos\delta\sin\alpha$$ $$z=d\sin\delta$$ Once you convert two stars' equatorial coordinates and distance from Earth to Cartesian coordinates, you can simply use the Pythagorean theorem to find their separation. To use your example, Tau Ceti has right ascension $\alpha\_1=1:44:04$, declination $\delta\_1=-15^{\circ}56'15''$ and distance to Earth $d\_1=11.9\;\text{light-years}$. Ross 248 has $\alpha\_2=23:41:55$, $\delta=+44^{\circ}10'39''$ and $d=10.3\;\text{light-years}$. Here, I'm using hours, minutes and seconds for right ascension and degrees, arcminutes and arcseconds for declination. If you don't want to do the calculations by hand, I wrote [a Python script](https://github.com/HDE226868/Stellar-Distances/blob/master/distances.py) to do it using [`astropy`](https://www.astropy.org/):$^{\dagger}$ ``` #!/usr/bin/env python import numpy as np from astropy import units as u from astropy.coordinates import SkyCoord ra_1 = '1:44:04' dec_1 = '-15:56:15' dist_1 = 11.9 ra_2 = '23:41:55' dec_2 = '+44:10:39' dist_2 = 10.3 def coords(ra, dec, dist): ""Converts equatorial coordinates to Cartesian coordinates"" new_coords = SkyCoord(ra, dec, unit=(u.hourangle, u.deg)) ra, dec = new_coords.ra.radian, new_coords.dec.radian x = distnp.cos(dec)np.cos(ra) y = distnp.cos(dec)np.sin(ra) z = distnp.sin(dec) return x, y, z def dist(ra_1, dec_1, dist_1, ra_2, dec_2, dist_2): ""Computes distance between two sets of Cartesian coordinates"" x_1, y_1, z_1 = coords(ra_1, dec_1, dist_1) x_2, y_2, z_2 = coords(ra_2, dec_2, dist_2) separation = np.sqrt((x_2 - x_1)2 + (y_2 - y_1)2 + (z_2 - z_1)2) print('The separation is {} light-years'.format(separation)) dist(ra_1, dec_1, dist_1, ra_2, dec_2, dist_2) ``` This tells me that Tau Ceti and Ross 248 are 12.2 light-years apart. --- $^{\dagger}$It's not great, but it works, and hey, this is astronomy. . . Estimating distances -------------------- A general method which you might find handy as an estimate* is to just calculate the mean distances between stars in a particular area - it saves you from having to do spherical trigonometry. We can get the mean separation between nearby stars, $l$ by calculating the local stellar number density, $n$. This is [generally agreed to be $n\sim0.1\;\text{pc}^{-3}$](https://physics.stackexchange.com/a/393902/56299), i.e. 1 stars per 10 cubic parsecs. Some groups have found values differing by a factor of 2 or 3; [Wikipedia in particular gives $0.14\;\text{pc}^{-3}$](https://en.wikipedia.org/wiki/Stellar_density). The mean separation is then [approximately $l\approx n^{-1/3}$](https://en.wikipedia.org/wiki/Mean_inter-particle_distance)or $$l\approx n^{-1/3}=(0.1\;\text{pc}^{-3})^{-1/3}\approx2.2\;\text{parsecs}=7\;\text{light-years}$$ or a bit under twice the distance to Proxima Centauri, the nearest star to Earth. This value should change in different places throughout the galaxy. In general . . . * It will decrease the closer you get to the galactic center. * It will decrease in areas of recent star formation. * It will increase in the (relatively rarefied) stellar halo, and in general outside the plane of the galaxy. * It will decrease in open clusters and globular clusters. * It will increase in spiral arms. I'd expect variation of around an order of magnitude or two at the extremes.
183,368	<p>Implementing a magic system as a programming language is very difficult. Does anyone have any advice, prior work, guiding ideas, or tips for doing this?</p> <p>The idea is that I want to be able to make a magic system where spells can be created like software developers create programs in a programming language. Imagine you sit down, type up some code in functions that describe various sub-functionality of the spell within the magic system, then those pieces are composed together to create a working spell.</p> <p>I’m trying to create a system that accurately fills this goal of “spells as code”, to a sufficient extent that it could be implemented and ran on a personal computer in 2020.</p> <p>Work so far:</p> <p>I’m aware of some games like <a href="https://store.steampowered.com/app/42910/Magicka/" rel="nofollow noreferrer">Magika</a> that are sort of close, and some stories that use this idea, but stop shy of providing the full details.</p> <p>I’m aware of the field of <a href="http://web.cs.mun.ca/%7Ebanzhaf/papers/alchemistry_review_MIT.pdf" rel="nofollow noreferrer">Artificial Chemistry,</a> which seems promising as providing a chemical baseline on some level.</p> <p><a href="https://store.steampowered.com/app/324190/CodeSpells/" rel="nofollow noreferrer">CodeSpells</a> is pretty great, and a decent example of the kind of thing I’m looking for.</p> <p>I have plenty of other brainstorming ideas, some of which are in the edits, but if anyone has tried to do this before and has advice or thoughts I’d really appreciate it.</p> <p>Edit: Some of the comments below are referring to how this question used to be about “formalizing fantasy magic”, a less precise statement. Magic as code is what I wanted to ask about, and it’s a better way of phrasing the idea that communicates the important aspects.</p>	[ { "answer_id": 183373, "author": "Nosajimiki", "author_id": 57832, "author_profile": "https://worldbuilding.stackexchange.com/users/57832", "pm_score": 3, "selected": false, "text": "<h2>Elements of a Programmable Magic System</h2>\n<p>In order to have a programmable magic system like yo...	2020/08/09	[ "https://worldbuilding.stackexchange.com/questions/183368", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/518/" ]	Implementing a magic system as a programming language is very difficult. Does anyone have any advice, prior work, guiding ideas, or tips for doing this? The idea is that I want to be able to make a magic system where spells can be created like software developers create programs in a programming language. Imagine you sit down, type up some code in functions that describe various sub-functionality of the spell within the magic system, then those pieces are composed together to create a working spell. I’m trying to create a system that accurately fills this goal of “spells as code”, to a sufficient extent that it could be implemented and ran on a personal computer in 2020. Work so far: I’m aware of some games like [Magika](https://store.steampowered.com/app/42910/Magicka/) that are sort of close, and some stories that use this idea, but stop shy of providing the full details. I’m aware of the field of [Artificial Chemistry,](http://web.cs.mun.ca/%7Ebanzhaf/papers/alchemistry_review_MIT.pdf) which seems promising as providing a chemical baseline on some level. [CodeSpells](https://store.steampowered.com/app/324190/CodeSpells/) is pretty great, and a decent example of the kind of thing I’m looking for. I have plenty of other brainstorming ideas, some of which are in the edits, but if anyone has tried to do this before and has advice or thoughts I’d really appreciate it. Edit: Some of the comments below are referring to how this question used to be about “formalizing fantasy magic”, a less precise statement. Magic as code is what I wanted to ask about, and it’s a better way of phrasing the idea that communicates the important aspects.	Elements of a Programmable Magic System --------------------------------------- In order to have a programmable magic system like you are asking for, there are a few principles of programming you will want to consider in it's design. A [Library](https://en.wikipedia.org/wiki/Library_(computing)) of Primitives: Without predefined objects defining what a spell is and does, you do not have a spell crafting programing language, you just have a programing language. Your primitives are the basic building blocks of your system that tells the end user what abilities are at his disposal. So, all the code responsible for a spell would fall inside of this system of object classes that can be bound together to make a spell. Your Primitives are used to set both the ability and limits on spells; so, if I want to include teleport spell, the primitive called `teleport` would include inside it not just the code for moving a character between points, but formulas for determining mana cost, cool down timers, range limits, etc. An Isolated [SOLID](https://en.wikipedia.org/wiki/SOLID) [API](https://en.wikipedia.org/wiki/Application_programming_interface) Architecture: While this is generally a good idea in programming, it is 100% essential for any system that gives an end user this much access to parts of how your game runs. In short, you will want your primitives and game engine completely isolated from your magic programming interface by an API such that making a spell means using just the primitives and interfaces that the game's developer has given you. If a `fire-attack` has certain properties and procedures for establishing cost and potency, you don't want users to have access to change these properties and procedures. You just want them to call and extend on them. Red-stone programming is a good example of this. It does not let you change how minecraft works, it just lets you take certain things that you can already do in the game and build procedures to do it in useful patterns. [Turing Completeness](https://en.wikipedia.org/wiki/Turing_completeness): The difference between a spell crafting system like you see in Elder Scrolls and a spell programming system would be the ability to string things together in logical and repeatable operations. Including things like logical operators (and, if, or, etc.), recursive operators (while, for, goto, etc.), and the ability to define your own variables with your spells will allow players nearly infinite access to manipulate the logic behind spell casting. Make the system accessible to a wide audience: Another feature I would suggest is to make spells able to be encrypted, shared, and sold. Most players will not want to program thier own spells in this much detail, but those that do will love it, and be able to make very advanced spells this way. By letting people hide the code of thier own spells to other players, it would encourage them to sell high-end spells on the community market. Using these principles, your "spell-book" might look something like this on the back-end, but hand coding could be substituted with a [Visual Programming Interface](https://en.wikipedia.org/wiki/Visual_programming_language) to reduce the leaning curve. ``` spell pummel($damage-low = 15, $damage-high = 30, $stunChance = 100, $stunDuration = 1){ // Metadata like name, description, and permission can be added to your custom spells to help with non-casty in-game stuff. this.name = 'Throw Pummel'; this.description = 'A simple attack spell for ending your foe rightly!'; this.permission = 'public'; cast ranged-attack({ // ranged-attack is a primitive for casting a spell which has certain properties you can define. element = 'kinetic', damage-low = $damage-low, damage-high = $damage-high, range = 50, accuracy = 80, stunChance = $stunChance, stunDuration = $stunDuration, special-effect = "bolt", special-effect-tint = "rgba(0,255,255,.75)" } } spell chainPummel() (){ this.name = 'Chain Pummel'; this.description = 'Pummel up to 10 enemies in a row!'; this.permission = 'private'; for(i=0;i<10;i++){ if (target.alive == true) { // target is an API behavior allowing an interaction with the game-engine. cast pummel(5, 10, 100, .1); // pummel has now been defined as an instance of ranged-attack which can now be called like a primitive. Also, by passing variables with it you can customize the spell on the fly. In this case, by casting a weaker/cheaper version of the spell. delay (0.1); } else { setNewTarget('hostile'); // setNewTarget is an API behavior allowing an interaction with the game-engine. if (target.alive == true) { cast pummel(5, 10, 100, .1); delay (0.1); } } } } ``` You can see that there is a lot of control here to make unique and quite intelligent spells, but no where does this say what the spells will cost to cast or let you directly manipulate the environment. So, your game interface will need to calculate and output those details for you; so, if I were to sell you these spells, your spell book might look like this: > > Throw Pummel [edit] > > > Lvl.3 Spell (costs 55 mana) > > > A simple attack spell for ending your foe rightly! > > > Author: Nosajimiki > > > > > Chain Pummel > > > Lvl.6 Spell (costs 21-210 mana) > > > Prereqs: Throw Pummel > > > Pummel up to 10 enemies in a row! > > > Author: Nosajimiki > > > Original answer may prove helpful for context, but does not answer the question as it has been revised. Yes, it's been tried -------------------- Yes, first place I remember seeing something like that is in the magic crafting system in Elder Scrolls:Oblivion. Basically you could combine any combination of spell properties to create custom spells and the difficulty to cast the spell was based on what properties you gave it. So, you could take a fire spell and decide if you wanted it to be touch or ranged, add a blast radius if you want it to be AOE, and you could then add a DoT property if you wanted it to burn instead of do all the damage at once, etc. and all the different properties of a spell either made it more or less expensive to cast so you could balance it however you wanted it. While the game had a bunch of ready-made spells for noobs to start with, once you got in good with the mages guild, these procedurally built spells literally allowed for millions of combinations of spells based on just a small handful of properties that had to be discreetly designed by the developers. It had an alchemy system for brewing potions procedurally based on what ingredients you used too. How to make it more of a "science" ---------------------------------- The thing about systems like the one used by Elder Scrolls was that it was designed to be as balanced and intuitive as possible; so, in the end it does not matter how you customized a spell, you'd never really hit much above your weight class just by using a cleaver combination of elements. For this you need a system that is asymmetric, exploitable, and full of undocumented features. Now this sounds like a terrible premise for game design, if a game has enough strange mechanics that are not explained in game, then researching and experimenting to see what they are becomes a meaningful part of the game unto itself. How you could apply this to a magic system: In the spell crafting section of the game you could choose what element you want an attack to be (fire, wind, water, and earth). On paper they all do the same damage and cost the same mana; so, being a noob, you just pick one at random. The game does not tell you this, but earth spells do a little extra armor penetration against heavy armor, fire spells have a higher crit rate, water spells can interrupt another player's spells, and wind pushed the opponent back a little. So, only through playing the game and making observations do you learn there are cases where one is better than the other. You may also notice that as you add levels to each element that they scale differently. Both 1 level of fire damage and one level of wind damage do 10 points of damage, but a level 5 fire does 50 damage, and wind only does 30, unless you can use the push effect to slam the opponent against a wall in which case you do 60. Then you can make things even more confusing with environmental variables like. Fire spells can be blinding bright when cast at night, water spells do less damage in a desert, wind spells are much less useful in open areas with nothing to push people into, and earth spells might do different damage based on what kind of ground you are standing on. So what this means for game play is that a wise wizard may know that he is going up against a mage who prefers Earth spells; so, he puts on some gambeson armor so he can move faster and absorb the impacts. He then lures the other wizard out onto a sandy beach so that his bolder spell suddenly starts throwing balls of mostly harmless sand. He then drinks a potion of x-ray vision and casts a wind AOE spell to kick up cloud of sand to blind his opponent. So, while the wiser wizard may be a lower level, he could still utterly destroy his opponent if he's thoroughly researched the side effects of spells and abilities. Another layer of complexity could be that the ratios of levels you put into a spell has certain optimal levels; so, a spell that does Fire damage may do the most damage per level of fire damage if 50% of the spells levels are devoted to damage, but more or less and you get a diminishing return > > To phrase this a different way: I want a set of physics rules that > allows players to create spells in game as various sorts of > “technology”. Similar to how players build red stone flying machines > from red stone and pistons in Minecraft, > > > Add a system for making spell combo macros. Where your spell tray can trigger conditional logic that activates spells and abilities. So, let's say your system does not allow flight, but it does allow mid-air jumping, you might create a macro that turns on and off looping mid-air jumping. Many gamers build macros to "cheat" anyway, you'd just make it a part of the game to begin with.
184,708	<p>I am writing a story in which people with a rare genetic ability are able to see, and are attracted to portals which lead to other dimensions.</p> <p>I have some ideas on how I want to differentiate good vs evil in this book, but I am interested in some more ideas.</p> <pre><code> My Idea </code></pre> <p>"Arcs" are portals (which are shaped like arcs) which are used to travel to other dimensions that are identical in form to our universe, but "life" in not identical (referring to people culture, society, happenings within the universe)</p> <p>THE ARCANE are people with the ability of "Allsight," meaning they have the ability to see and sense portals to other dimensions. They have been guardians of the dimensions and have protected arc-blind people from accidents and tragedies that can come from traveling through arcs.</p> <p>However, some of the Arcane began to become corrupt and greedy. They wanted to use their ability to the advantage of themselves and gain more power. These ones, so far, I am calling "Archangels"</p> <p>So, how could this ability be useful and how could one who possesses that ability use it for evil? Hopefully that makes sense. Thanks in advance for your response.</p>	[ { "answer_id": 184710, "author": "Halfthawed", "author_id": 64961, "author_profile": "https://worldbuilding.stackexchange.com/users/64961", "pm_score": 2, "selected": false, "text": "<p><strong>By being an arms merchant</strong></p>\n<p>In any war between two sides, the one who always pr...	2020/09/01	[ "https://worldbuilding.stackexchange.com/questions/184708", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/78540/" ]	I am writing a story in which people with a rare genetic ability are able to see, and are attracted to portals which lead to other dimensions. I have some ideas on how I want to differentiate good vs evil in this book, but I am interested in some more ideas. ``` My Idea ``` "Arcs" are portals (which are shaped like arcs) which are used to travel to other dimensions that are identical in form to our universe, but "life" in not identical (referring to people culture, society, happenings within the universe) THE ARCANE are people with the ability of "Allsight," meaning they have the ability to see and sense portals to other dimensions. They have been guardians of the dimensions and have protected arc-blind people from accidents and tragedies that can come from traveling through arcs. However, some of the Arcane began to become corrupt and greedy. They wanted to use their ability to the advantage of themselves and gain more power. These ones, so far, I am calling "Archangels" So, how could this ability be useful and how could one who possesses that ability use it for evil? Hopefully that makes sense. Thanks in advance for your response.	By being an arms merchant In any war between two sides, the one who always profits are the people selling weapons. (Assuming, of course, that the ones producing the weapons are independent of the ones fighting.) And, if you can be the person selling weapons to both sides - well, that's mountains of profits for as long as the war goes on, and you have all the incentive in the world to keep this ongoing. This is why no one likes war profiteers. Someone who is evil and has access to portals just because the world's ultimate black market weapons dealer. Let's say one of these portals leads to a world with technology 150 years ago? Well, just travel there and sell some modern arms in exchange for rare metals - gold, platinum, etc. One of these portal leads to somewhere technologically ahead of us? Go there, spend some of those rare metals, and come back to Earth selling your futuristic arms to the highest bidder. Not to mention that traveling via portal has the potential to let you get around restrictions and blockades with ease, so your smuggling will be very hard to stop. Sure, you'll cause untold havoc and destruction by giving horrifyingly powerful weapons to people who really shouldn't have them and possibly lead to the death and exploitation of entire worlds, but at the end of the day, you'll be filthy rich. So you have to ask yourself: "If I was extraordinarily evil, would I care about crushing the lives of millions just so I could be fabulously wealthy?" (Hopefully, the answer is still no, because that's an awfully large cost. But that's pretty much one of the worse things I think you can do with this.)
184,763	<p>This is my first post on this site, so please bear with me.</p> <p>I am working on a series of stories about an interstellar colony with a large gender disparity. Namely the initial population was made up of 120 mature males and 1080 mature females. In an effort to provide genetic diversity tens of thousands of fertilized frozen eggs were included on the ships, all of them female. As a result every female colonist is expected to have at least 12 children during their adult years. Of these pregnancies 9 of the children have to be implanted female embryos. The other 3+ children would be conceived naturally, with those pregnancies being interspersed with those of the implanted ones. This in turn makes the birth ratio of roughly 1 male per 8 births.</p> <p>The percentage of children who survive to adulthood is 94% female and 99.9% male (males are too precious to allow them to take any risks). Furthermore due to the colonial nature of the planet life expectancy is lower than would be expected considering their advanced medical technology. Therefore I set the death rate to 12.5 out of every 1000 colonists per earth year.</p> <p>To add even more complexity the ships returned 54 earth years later with a second wave of colonists. That wave had the exact same makeup as the first.</p> <p>Whilst I have found a number of calculators and articles on exponential growth rate none of them seem to take gender ratios into account. They all seem to assume that there are an equal number of males to females, which is definitely not the case here.</p> <p>The short story I am currently writing takes place 207 earth years after the initial colonization and I need to get an idea of the planets population size at that point in time. Even a rough estimate (within a few thousand) would do.</p> <p>Thank you all very much for your time, consideration and aid. I hope that you have a wonderful day.</p> <p>Arkham</p> <p>Edits:</p> <p>Many people have asked why the rush to populate the planet so quickly. The answer is that archaeological evidence was found showing that an attempted alien invasion of earth took place in the year 400 CE and that another invasion could take place at any time. This secret has lead the world governments (in the form of the Grand Alliance) to begin a massive colonization effort, first within the Solar System and then to another star system. After all all of humanity was located in one place and the governments wanted to get all of their eggs out of one basket.</p> <p>This particular star system has multiple planets which are much easier to terraform than Mars. As a result the Alliance government has decided to colonize all of them quickly. This effort in turn will need a fairly sizeable population base, hence the forced breeding process.</p> <p>Many have also suggested that 12 children per woman is unrealistic and that women would be overwhelmed. For this I am drawing from my own family history. On my mothers side of the family my grandmother was one of 12 children and my grandfather was one of 13 (it would have been 14 but one died in infancy). Note that this took place in the 1920s in rural Virginia USA and my grandparents told me repeatedly that large families like theirs was the norm and not the exception when they were growing up.</p> <p>In addition the older children helped to raise the younger ones. I will never forget my grand uncle telling my mother at my grandfather’s funeral that my grandfather had been like a second father to him. In my own immediate family my brother was 10 years older than I was and he often took care of me and my sister when our parents were busy.</p> <p>Finally all of the wives in the group marriages would not be the same age. Since men can sire children their entire adult lives they can father children well into their old age. Both the oldest wives and the youngest ones (who have not yet started having children themselves) would help with the raising of the children of those of childbearing age. Both my aunt and my grandmother would watch me and my sister when we were young. This would be a similar situation.</p> <p>This arrangement would not be a happy one for the males either. By the end of the second generation men will have lost their human rights and be viewed as property, first by their mothers and later their wives. Men would have little or no say as to who they marry and would be “sold” to their wives in the form of a dowry. Of course their mother would get a cut of later dowrys even after the males are married off. Of course the male wouldn’t see any of the money.</p> <p>In fact the males would not even have a room of their own, rotating from household to household at an interval agreed upon in the marriage contracts. They would then stay in their wife’s room while staying in that household.</p> <p>Some have pointed out that the colonists would eventually run out of frozen embryos. This would not be the case since the embryos would be split in a process known as artificial twinning. This process, currently used in livestock rearing, essentially makes clones by splitting embryos. While this process is currently limited to 4 to 6 splits depending on the species involved the process should be better understood by the 22nd century when the first colony ship is launched.</p> <p>While this does not answer every questions asked thus far I hope that it helps to clarify things and shed light on my thinking process. Thank you all once again for your aid in this matter and have a great day.</p> <p>Arkham</p> <p><strong>My final solution:</strong></p> <p>I'm sorry for taking so long to get back to this question, but I have been working on rewriting Ash's code for various scenarios (<strong>Thank you again Ash!</strong>). Then after running the numbers I had to think of a way to make things fit into the stories without leaving plot holes large enough to fly a star-ship through.</p> <p>After taking everyone’s suggestions into account this is what I was able to come up with:</p> <p><strong>First of all I decided that there would be no new births for the first 5 years</strong> while the colony is first becoming established. That should allow them to get the basic farms up and running as well as find clay (and build kilns) for bricks and calcium carbonate for mortar / concrete, etc. While one story brick houses might be primitive by their standards they would be enough to meet basic housing needs once the colony grows beyond the size that the initial colonist's prefab aluminum / titanium dwellings can hold.</p> <p>In addition after everyone's input <strong>I dropped the initial number of children from 12 to 9 (2 natural, 7 implanted) then slowly decreased over the next 3 generations</strong> as follows:</p> <p>2nd Generation 7 (2 natural, 5 implanted)</p> <p>3rd Generation 6 (2 natural, 4 implanted)</p> <p>4th Generation 5 (2 natural, 3 implanted)</p> <p>There was no 5th generation of implanted since they ran out of embryos even though I upped the number of embryos in both waves to 100,000 each.</p> <p>Note: Each generation was considered to be 25 earth years long.</p> <p>After this point 3 natural births per woman were expected. Any births less then 3 per female causes the colony to shrink fairly rapidly due to the mortality rate.</p> <p><strong>The second wave of colonization in the 54th year after the first was set up as a separate community</strong> over 100 kilometres from the nearest established settlement. This was done at the new colonists request due to differing “customs.” Close enough to interact by air and via communications, but far enough away (at first at least) for the new colonists to adjust. This second “colony” used the same model as the first. Their numbers were just calculated for 153 earth years as opposed to 207. That population was simply added to the initial colony's population to get the total population.</p> <p>Here are some quick early population totals for the colony (in earth years):</p> <p>Year 1: 1,200</p> <p>Year 6: 2,236</p> <p>Year 10: 3,204</p> <p>Year 15 : 4,974</p> <p>Year 20: 6,624</p> <p>Year 25: 7,296</p> <p>Year 30: 8,966</p> <p>Taking everyone’s input into account this should be a much more reasonable rate of growth for the early colony while still allowing for fast overall growth.</p> <hr /> <p>Initial colony numbers after 207 earth years:</p> <p>Total 1,450,891</p> <p>Infants 168,954</p> <p>Children 237,493</p> <p>Teens 200,892</p> <p>Young Adults 332,063</p> <p>Adults 353,629</p> <p>Seniors 157,860</p> <p>Males 742,073</p> <p>Females 708,818</p> <hr /> <p>“Second” colony numbers after 153 earth years:</p> <p>Total 779,788</p> <p>Infants 88,944</p> <p>Children 135,453</p> <p>Teens 118,528</p> <p>Young Adults 177,205</p> <p>Adults 194,641</p> <p>Seniors 65,017</p> <p>Males 385,670</p> <p>Females 394,118</p> <hr /> <p>Combined Totals:</p> <p><strong>Total 2,230,679</strong></p> <p>Infants 257,898</p> <p>Children 372,946</p> <p>Teens 319,509</p> <p>Young Adults 509,268</p> <p>Adults 548,270</p> <p>Seniors 222,877</p> <p><strong>Males 1,127,743</strong></p> <p><strong>Females 1,102,936</strong></p> <p>Finally I wanted to thank everyone for their help and guidance in answering this question. While I'm pretty good with the astronomy aspects I'm not that great at population growth calculations. <strong>Thank you all for making the new guy feel welcome.</strong></p> <p>P.S. If any of you are interested in the system this is based on here is a link to a computer animation I did in late 2013 - early 2014 (Yeah I've been working on these stories a LONG time). Please note that this was before they actually started detecting planets in the system and thus while the information presented was calculated using Kepler's laws and the like all of the data is fictional. In case you are wondering the planet in question is "Coopers World." Oh and If you want to read all of the data as it flashes on the screen remember that the pause button is your friend. :)</p> <p><a href="https://www.youtube.com/watch?v=0ujx2ASqgAg" rel="nofollow noreferrer">https://www.youtube.com/watch?v=0ujx2ASqgAg</a></p>	[ { "answer_id": 184765, "author": "Halfthawed", "author_id": 64961, "author_profile": "https://worldbuilding.stackexchange.com/users/64961", "pm_score": 3, "selected": false, "text": "<p><strong>About 100 billion people. Roughly.</strong></p>\n<p>I'm ignoring the difference between the ma...	2020/09/01	[ "https://worldbuilding.stackexchange.com/questions/184763", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/79163/" ]	This is my first post on this site, so please bear with me. I am working on a series of stories about an interstellar colony with a large gender disparity. Namely the initial population was made up of 120 mature males and 1080 mature females. In an effort to provide genetic diversity tens of thousands of fertilized frozen eggs were included on the ships, all of them female. As a result every female colonist is expected to have at least 12 children during their adult years. Of these pregnancies 9 of the children have to be implanted female embryos. The other 3+ children would be conceived naturally, with those pregnancies being interspersed with those of the implanted ones. This in turn makes the birth ratio of roughly 1 male per 8 births. The percentage of children who survive to adulthood is 94% female and 99.9% male (males are too precious to allow them to take any risks). Furthermore due to the colonial nature of the planet life expectancy is lower than would be expected considering their advanced medical technology. Therefore I set the death rate to 12.5 out of every 1000 colonists per earth year. To add even more complexity the ships returned 54 earth years later with a second wave of colonists. That wave had the exact same makeup as the first. Whilst I have found a number of calculators and articles on exponential growth rate none of them seem to take gender ratios into account. They all seem to assume that there are an equal number of males to females, which is definitely not the case here. The short story I am currently writing takes place 207 earth years after the initial colonization and I need to get an idea of the planets population size at that point in time. Even a rough estimate (within a few thousand) would do. Thank you all very much for your time, consideration and aid. I hope that you have a wonderful day. Arkham Edits: Many people have asked why the rush to populate the planet so quickly. The answer is that archaeological evidence was found showing that an attempted alien invasion of earth took place in the year 400 CE and that another invasion could take place at any time. This secret has lead the world governments (in the form of the Grand Alliance) to begin a massive colonization effort, first within the Solar System and then to another star system. After all all of humanity was located in one place and the governments wanted to get all of their eggs out of one basket. This particular star system has multiple planets which are much easier to terraform than Mars. As a result the Alliance government has decided to colonize all of them quickly. This effort in turn will need a fairly sizeable population base, hence the forced breeding process. Many have also suggested that 12 children per woman is unrealistic and that women would be overwhelmed. For this I am drawing from my own family history. On my mothers side of the family my grandmother was one of 12 children and my grandfather was one of 13 (it would have been 14 but one died in infancy). Note that this took place in the 1920s in rural Virginia USA and my grandparents told me repeatedly that large families like theirs was the norm and not the exception when they were growing up. In addition the older children helped to raise the younger ones. I will never forget my grand uncle telling my mother at my grandfather’s funeral that my grandfather had been like a second father to him. In my own immediate family my brother was 10 years older than I was and he often took care of me and my sister when our parents were busy. Finally all of the wives in the group marriages would not be the same age. Since men can sire children their entire adult lives they can father children well into their old age. Both the oldest wives and the youngest ones (who have not yet started having children themselves) would help with the raising of the children of those of childbearing age. Both my aunt and my grandmother would watch me and my sister when we were young. This would be a similar situation. This arrangement would not be a happy one for the males either. By the end of the second generation men will have lost their human rights and be viewed as property, first by their mothers and later their wives. Men would have little or no say as to who they marry and would be “sold” to their wives in the form of a dowry. Of course their mother would get a cut of later dowrys even after the males are married off. Of course the male wouldn’t see any of the money. In fact the males would not even have a room of their own, rotating from household to household at an interval agreed upon in the marriage contracts. They would then stay in their wife’s room while staying in that household. Some have pointed out that the colonists would eventually run out of frozen embryos. This would not be the case since the embryos would be split in a process known as artificial twinning. This process, currently used in livestock rearing, essentially makes clones by splitting embryos. While this process is currently limited to 4 to 6 splits depending on the species involved the process should be better understood by the 22nd century when the first colony ship is launched. While this does not answer every questions asked thus far I hope that it helps to clarify things and shed light on my thinking process. Thank you all once again for your aid in this matter and have a great day. Arkham My final solution: I'm sorry for taking so long to get back to this question, but I have been working on rewriting Ash's code for various scenarios (Thank you again Ash!). Then after running the numbers I had to think of a way to make things fit into the stories without leaving plot holes large enough to fly a star-ship through. After taking everyone’s suggestions into account this is what I was able to come up with: First of all I decided that there would be no new births for the first 5 years while the colony is first becoming established. That should allow them to get the basic farms up and running as well as find clay (and build kilns) for bricks and calcium carbonate for mortar / concrete, etc. While one story brick houses might be primitive by their standards they would be enough to meet basic housing needs once the colony grows beyond the size that the initial colonist's prefab aluminum / titanium dwellings can hold. In addition after everyone's input I dropped the initial number of children from 12 to 9 (2 natural, 7 implanted) then slowly decreased over the next 3 generations as follows: 2nd Generation 7 (2 natural, 5 implanted) 3rd Generation 6 (2 natural, 4 implanted) 4th Generation 5 (2 natural, 3 implanted) There was no 5th generation of implanted since they ran out of embryos even though I upped the number of embryos in both waves to 100,000 each. Note: Each generation was considered to be 25 earth years long. After this point 3 natural births per woman were expected. Any births less then 3 per female causes the colony to shrink fairly rapidly due to the mortality rate. The second wave of colonization in the 54th year after the first was set up as a separate community over 100 kilometres from the nearest established settlement. This was done at the new colonists request due to differing “customs.” Close enough to interact by air and via communications, but far enough away (at first at least) for the new colonists to adjust. This second “colony” used the same model as the first. Their numbers were just calculated for 153 earth years as opposed to 207. That population was simply added to the initial colony's population to get the total population. Here are some quick early population totals for the colony (in earth years): Year 1: 1,200 Year 6: 2,236 Year 10: 3,204 Year 15 : 4,974 Year 20: 6,624 Year 25: 7,296 Year 30: 8,966 Taking everyone’s input into account this should be a much more reasonable rate of growth for the early colony while still allowing for fast overall growth. --- Initial colony numbers after 207 earth years: Total 1,450,891 Infants 168,954 Children 237,493 Teens 200,892 Young Adults 332,063 Adults 353,629 Seniors 157,860 Males 742,073 Females 708,818 --- “Second” colony numbers after 153 earth years: Total 779,788 Infants 88,944 Children 135,453 Teens 118,528 Young Adults 177,205 Adults 194,641 Seniors 65,017 Males 385,670 Females 394,118 --- Combined Totals: Total 2,230,679 Infants 257,898 Children 372,946 Teens 319,509 Young Adults 509,268 Adults 548,270 Seniors 222,877 Males 1,127,743 Females 1,102,936 Finally I wanted to thank everyone for their help and guidance in answering this question. While I'm pretty good with the astronomy aspects I'm not that great at population growth calculations. Thank you all for making the new guy feel welcome. P.S. If any of you are interested in the system this is based on here is a link to a computer animation I did in late 2013 - early 2014 (Yeah I've been working on these stories a LONG time). Please note that this was before they actually started detecting planets in the system and thus while the information presented was calculated using Kepler's laws and the like all of the data is fictional. In case you are wondering the planet in question is "Coopers World." Oh and If you want to read all of the data as it flashes on the screen remember that the pause button is your friend. :) <https://www.youtube.com/watch?v=0ujx2ASqgAg>	### 354 Thousand <https://godbolt.org/z/zoPYsz> If you bring 10,000 embryos on the first ship, and 10,000 on the second ship, you'll run out in the 25th year, and 58th year. I modified your death rate so that when people hit 70 years old it shot up to 10% per year. As otherwise we had hundreds of 100 year olds. That link allows you to change the values and they should update the simulation in the output window. I'm sorry its in C++, its the only language I know really well. * Total 354,102 * Infants 39,882 * Children 53,934 * Teens 49,704 * YoungAdults 79,456 * Adults 91,140 * Seniors 39,986 * Males 181,138 * Females 172,964 In the year 207, there are 16 males and 13 females turning 100 years old. There are 8300 babies born that year. The year 58 had 6135 females and 1152 males born. Birth rates dropped for the next 100 years, until the year 131, (7600 births). What would really happen? ------------------------- Each woman has 12 direct children, the father, grandma, and grandfather are spread to thin to help (they'd have to help raise: 96 children, 240 children, and 9216 children respectively). This is just too much. ### They're going to revolt I'm not a woman so I'm not 100% sure on this, but I have a sneaking suspicion they don't like being used as baby factories and forced to raise 12 kids (essentially alone - remember the "husband" has 8 other women in his [polycule](https://www.urbandictionary.com/define.php?term=Polycule)). The first generation might be optimistic, but mental health would be a real issue, there'd be anger and resentment, but the second generation, born in the first few years and about to be implanted on their 18th birthday will not share that optimism, and you'll have a suffragette movement around about year 20. ... If a woman refuses to be a baby factory are we really going impregnate her against her will? There's a whole bunch of LGBT issues also not considered here. ### ... And starve Farming is going to be a real issue, take year 15 as an example: There will be: * Infants 2682 * Children 6749 * Teens 853 (13 and 14 year old) * Adults 984 (90 males and 894 females) Those 900 woman are going to be fully occupied nursing 3 infants each, and yelling discipline at 7 misbehaving children. Assuming all the men are farmers, they're going to need to grow food for 11,000 people, 122 mouths to feed each. With current American tech they can hit 166 mouths fed per farmer. You've regressed tech for this (for the infant mortality figure), so I've got to assume farming has as well. In postwar american, [1 Farmer feeds 73 people](https://recipes.howstuffworks.com/how-many-farmer-feed.htm). Putting the tweens and children in the field may put starvation off a bit, but they need to be in school, otherwise you're society is going to regress very quickly, and you'll be illiterate within a few generations. Edit: actually that 1 in 73 assumes theres people refining fuel, making fertilizers and pesticides, making replacmenet parts, and spitting out new machinery at an exponential rate. That's not going to happen as everyone is busy making babies or growing food. You'll regress to 1930s level farm output, which is 1 farmer per 4 mouths. ### ... and die of exposure The growth rate in the number of buildings is also extreme. Each male in the first 60 years has to build 80 houses in their lifetime (one for each of his partners daughters), each house has to hold a family of up to 14 (most 13, but the males need to live somewhere too). That's a lot to build, remember he's making his own nails, cutting his own logs, etc, all while farming food for 122 people. ### So slow the implantation down Embryos can be stored for a while, so no need to implant them ASAP. Changing the requirements to 3 natural children, and 3 embryos (so 6 children total per woman) the population at year 207 is 345,000. ### I wrote a calculator for this: <https://godbolt.org/z/zoPYsz> [![enter image description here](https://i.stack.imgur.com/yUuCO.png)](https://i.stack.imgur.com/yUuCO.png) The panel on the left is C++ code, the pannel on the right is the output. Just change the numbers on the left (eg what years do women have children), and the log will update on the right. Here's the source if the link goes dead (C++17) ``` #include <vector> #include <set> #include <iostream> #include <numeric> int main() { // There are 0 children aged 0 to 17 on the first ship std::vector<size_t> males(18,0); std::vector<size_t> females(18,0); // Our initial colonists males.push_back(120); females.push_back(1080); auto survivalRateMaleChild = 0.99; auto survivalRateFemaleChild = 0.94; auto survivalRateEveryone = (1000.0 - 12.0) / 1000.0; auto simulatedYears = 207; // What years of her life does a given woman have children? std::set<int> randomChildAt = {19, 25, 35}; std::set<int> femaleChildAt = {21, 22, 23, 24, 26, 27, 28, 29, 30}; // Finite number of embryos auto embryos = 10000; for (auto year = 0; year < simulatedYears; year++) { // Calculate our births size_t newMales = 0; size_t newFemales = 0; if (embryos > 0) { for (auto i : femaleChildAt) { if (i >= females.size()) continue; newFemales += females[i]; } } embryos -= newFemales; if (embryos < 0 && newFemales) { std::cout << "Run out of embryos\n"; } for (auto i : randomChildAt) { if (i >= females.size()) continue; newFemales += females[i] / 2; newMales += females[i] / 2; } males.insert(males.begin(), newMales); females.insert(females.begin(), newFemales); // Kill off our infant mortality children (they all die at age 5) males[5] = survivalRateMaleChild; females[5] = survivalRateFemaleChild; // Kill of our random death rate. Child infant mortality is // calcualted seperately, we don't want to double kill them. for (auto age = 18; age < females.size(); age++) { females[age] = survivalRateEveryone; males[age] = survivalRateEveryone; } // Kill of our seniors, 10% die per year for (auto age = 70; age < females.size(); age++) { females[age] = 0.90; males[age] = 0.90; } // Add the second ship, which is full of 18 year olds. if (year == 57) { males[18] += 120; females[18] += 1080; embryos += 10000; } // Print some stats std::cout << "Y: " << year << ". " << newMales << "m and " << newFemales << "f born. Pop: " << std::accumulate(males.begin(), males.end(), 0) + std::accumulate(females.begin(), females.end(), 0) << "\n"; } std::cout << "At end of simulation: \n"; size_t total = 0; size_t infants = 0; size_t children = 0; size_t teenages = 0; size_t youngAdults = 0; size_t adults = 0; size_t seniors = 0; size_t male = 0; size_t female = 0; for (auto age = 0; age < 100; age++) { if (age >= females.size()) continue; std::cout << age << " yr olds: " << males[age] << " males and " << females[age] << " females.\n"; auto t = males[age] + females[age]; male += males[age]; female += females[age]; if (age < 5) infants += t; else if (age < 13) children += t; else if (age < 20) teenages += t; else if (age < 35) youngAdults += t; else if (age < 60) adults += t; else seniors += t; total += t; } std::cout << "Total " << total << "\n"; std::cout << "Infants " << infants << "\n"; std::cout << "Children " << children << "\n"; std::cout << "Teens " << teenages << "\n"; std::cout << "YoungAdults " << youngAdults << "\n"; std::cout << "Adults " << adults << "\n"; std::cout << "Seniors " << seniors << "\n"; std::cout << "Males " << male << "\n"; std::cout << "Females " << female << "\n"; return 0; } ``` Year by year running log of births and population ``` Y: 0. 0m and 0f born. Pop: 1185 Y: 1. 533m and 533f born. Pop: 2236 Y: 2. 0m and 0f born. Pop: 2221 Y: 3. 0m and 1041f born. Pop: 3247 Y: 4. 0m and 1028f born. Pop: 4260 Y: 5. 0m and 1015f born. Pop: 5260 Y: 6. 0m and 1002f born. Pop: 6209 Y: 7. 494m and 494f born. Pop: 7183 Y: 8. 0m and 977f born. Pop: 8083 Y: 9. 0m and 965f born. Pop: 8972 Y: 10. 0m and 953f born. Pop: 9850 Y: 11. 0m and 941f born. Pop: 10716 Y: 12. 0m and 929f born. Pop: 11596 Y: 13. 0m and 0f born. Pop: 11523 Y: 14. 0m and 0f born. Pop: 11452 Y: 15. 0m and 0f born. Pop: 11381 Y: 16. 0m and 0f born. Pop: 11311 Y: 17. 436m and 436f born. Pop: 12114 Y: 18. 0m and 0f born. Pop: 12101 Y: 19. 0m and 0f born. Pop: 12075 Y: 20. 0m and 0f born. Pop: 12050 Y: 21. 244m and 244f born. Pop: 12502 Y: 22. 0m and 0f born. Pop: 12422 Y: 23. 477m and 953f born. Pop: 13793 Y: 24. 471m and 941f born. Pop: 15134 Run out of embryos Y: 25. 465m and 1859f born. Pop: 17375 Y: 26. 458m and 458f born. Pop: 18178 Y: 27. 452m and 452f born. Pop: 18981 Y: 28. 447m and 447f born. Pop: 19700 Y: 29. 884m and 884f born. Pop: 21284 Y: 30. 872m and 872f born. Pop: 22778 Y: 31. 862m and 862f born. Pop: 24336 Y: 32. 850m and 850f born. Pop: 25870 Y: 33. 208m and 208f born. Pop: 26123 Y: 34. 414m and 414f born. Pop: 26766 Y: 35. 410m and 410f born. Pop: 27391 Y: 36. 404m and 404f born. Pop: 28005 Y: 37. 796m and 796f born. Pop: 29405 Y: 38. 394m and 394f born. Pop: 30047 Y: 39. 389m and 389f born. Pop: 30660 Y: 40. 384m and 384f born. Pop: 31263 Y: 41. 490m and 490f born. Pop: 32061 Y: 42. 374m and 374f born. Pop: 32593 Y: 43. 803m and 803f born. Pop: 33984 Y: 44. 796m and 796f born. Pop: 35349 Y: 45. 1213m and 1213f born. Pop: 37536 Y: 46. 565m and 565f born. Pop: 38408 Y: 47. 660m and 660f born. Pop: 39463 Y: 48. 551m and 551f born. Pop: 40248 Y: 49. 809m and 809f born. Pop: 41531 Y: 50. 798m and 798f born. Pop: 42743 Y: 51. 1186m and 1186f born. Pop: 44722 Y: 52. 582m and 582f born. Pop: 45491 Y: 53. 445m and 445f born. Pop: 45991 Y: 54. 378m and 378f born. Pop: 46338 Y: 55. 562m and 562f born. Pop: 47047 Y: 56. 554m and 554f born. Pop: 47708 Y: 57. 818m and 818f born. Pop: 50134 Y: 58. 541m and 4677f born. Pop: 54932 Run out of embryos Y: 59. 1152m and 6135f born. Pop: 61797 Y: 60. 701m and 701f born. Pop: 62763 Y: 61. 1095m and 1095f born. Pop: 64500 Y: 62. 507m and 507f born. Pop: 65036 Y: 63. 871m and 871f born. Pop: 66047 Y: 64. 694m and 694f born. Pop: 66606 Y: 65. 1545m and 1545f born. Pop: 69192 Y: 66. 744m and 744f born. Pop: 70142 Y: 67. 830m and 830f born. Pop: 71293 Y: 68. 725m and 725f born. Pop: 72199 Y: 69. 784m and 784f born. Pop: 73214 Y: 70. 856m and 856f born. Pop: 74303 Y: 71. 1209m and 1209f born. Pop: 76098 Y: 72. 653m and 653f born. Pop: 76780 Y: 73. 779m and 779f born. Pop: 77663 Y: 74. 550m and 550f born. Pop: 78045 Y: 75. 1182m and 1182f born. Pop: 79646 Y: 76. 733m and 733f born. Pop: 80237 Y: 77. 1058m and 1058f born. Pop: 81416 Y: 78. 2528m and 2528f born. Pop: 85495 Y: 79. 3300m and 3300f born. Pop: 91098 Y: 80. 777m and 777f born. Pop: 91590 Y: 81. 1193m and 1193f born. Pop: 92929 Y: 82. 675m and 675f born. Pop: 93190 Y: 83. 991m and 991f born. Pop: 93984 Y: 84. 2514m and 2514f born. Pop: 97801 Y: 85. 3625m and 3625f born. Pop: 104035 Y: 86. 935m and 935f born. Pop: 104873 Y: 87. 1289m and 1289f born. Pop: 106431 Y: 88. 761m and 761f born. Pop: 106942 Y: 89. 892m and 892f born. Pop: 107606 Y: 90. 825m and 825f born. Pop: 108071 Y: 91. 1419m and 1419f born. Pop: 109902 Y: 92. 818m and 818f born. Pop: 110519 Y: 93. 1014m and 1014f born. Pop: 111492 Y: 94. 2322m and 2322f born. Pop: 115018 Y: 95. 3188m and 3188f born. Pop: 120184 Y: 96. 959m and 959f born. Pop: 120792 Y: 97. 1408m and 1408f born. Pop: 122265 Y: 98. 1623m and 1623f born. Pop: 124147 Y: 99. 2168m and 2168f born. Pop: 126967 Y: 100. 847m and 847f born. Pop: 127044 Y: 101. 1628m and 1628f born. Pop: 128796 Y: 102. 897m and 897f born. Pop: 128979 Y: 103. 1212m and 1212f born. Pop: 129751 Y: 104. 2498m and 2498f born. Pop: 133069 Y: 105. 3360m and 3360f born. Pop: 138194 Y: 106. 1076m and 1076f born. Pop: 138709 Y: 107. 1549m and 1549f born. Pop: 140200 Y: 108. 875m and 875f born. Pop: 140326 Y: 109. 1118m and 1118f born. Pop: 140784 Y: 110. 1650m and 1650f born. Pop: 142267 Y: 111. 2638m and 2638f born. Pop: 145891 Y: 112. 1043m and 1043f born. Pop: 146277 Y: 113. 1408m and 1408f born. Pop: 147364 Y: 114. 2338m and 2338f born. Pop: 150270 Y: 115. 3084m and 3084f born. Pop: 154552 Y: 116. 1078m and 1078f born. Pop: 154738 Y: 117. 1695m and 1695f born. Pop: 156234 Y: 118. 1340m and 1340f born. Pop: 157007 Y: 119. 1793m and 1793f born. Pop: 158581 Y: 120. 2322m and 2322f born. Pop: 161157 Y: 121. 3470m and 3470f born. Pop: 166111 Y: 122. 1167m and 1167f born. Pop: 166396 Y: 123. 1637m and 1637f born. Pop: 167614 Y: 124. 2118m and 2118f born. Pop: 169794 Y: 125. 2797m and 2797f born. Pop: 173291 Y: 126. 1160m and 1160f born. Pop: 173447 Y: 127. 1934m and 1934f born. Pop: 175290 Y: 128. 1087m and 1087f born. Pop: 175195 Y: 129. 1406m and 1406f born. Pop: 175387 Y: 130. 2693m and 2693f born. Pop: 178162 Y: 131. 3842m and 3842f born. Pop: 183353 Y: 132. 1293m and 1293f born. Pop: 183435 Y: 133. 1831m and 1831f born. Pop: 184628 Y: 134. 2052m and 2052f born. Pop: 186271 Y: 135. 2704m and 2704f born. Pop: 189062 Y: 136. 1512m and 1512f born. Pop: 189424 Y: 137. 2511m and 2511f born. Pop: 191965 Y: 138. 1392m and 1392f born. Pop: 192236 Y: 139. 1875m and 1875f born. Pop: 193417 Y: 140. 2999m and 2999f born. Pop: 196814 Y: 141. 4172m and 4172f born. Pop: 202595 Y: 142. 1395m and 1395f born. Pop: 202764 Y: 143. 2052m and 2052f born. Pop: 204309 Y: 144. 1866m and 1866f born. Pop: 205478 Y: 145. 2463m and 2463f born. Pop: 207728 Y: 146. 2138m and 2138f born. Pop: 209263 Y: 147. 3357m and 3357f born. Pop: 213413 Y: 148. 1382m and 1382f born. Pop: 213376 Y: 149. 1868m and 1868f born. Pop: 214041 Y: 150. 3015m and 3015f born. Pop: 217020 Y: 151. 4115m and 4115f born. Pop: 222220 Y: 152. 1489m and 1489f born. Pop: 222131 Y: 153. 2299m and 2299f born. Pop: 223795 Y: 154. 1903m and 1903f born. Pop: 224499 Y: 155. 2511m and 2511f born. Pop: 226080 Y: 156. 2713m and 2713f born. Pop: 228055 Y: 157. 4096m and 4096f born. Pop: 232993 Y: 158. 1624m and 1624f born. Pop: 232977 Y: 159. 2253m and 2253f born. Pop: 234239 Y: 160. 3044m and 3044f born. Pop: 237092 Y: 161. 4118m and 4118f born. Pop: 242053 Y: 162. 1717m and 1717f born. Pop: 242162 Y: 163. 2737m and 2737f born. Pop: 244489 Y: 164. 1853m and 1853f born. Pop: 244869 Y: 165. 2455m and 2455f born. Pop: 246181 Y: 166. 3272m and 3272f born. Pop: 249116 Y: 167. 4766m and 4766f born. Pop: 255204 Y: 168. 1710m and 1710f born. Pop: 255074 Y: 169. 2417m and 2417f born. Pop: 256290 Y: 170. 2948m and 2948f born. Pop: 258612 Y: 171. 3954m and 3954f born. Pop: 262866 Y: 172. 2159m and 2159f born. Pop: 263481 Y: 173. 3430m and 3430f born. Pop: 266861 Y: 174. 1981m and 1981f born. Pop: 267155 Y: 175. 2650m and 2650f born. Pop: 268513 Y: 176. 3658m and 3658f born. Pop: 271891 Y: 177. 5205m and 5205f born. Pop: 278496 Y: 178. 1900m and 1900f born. Pop: 278446 Y: 179. 2783m and 2783f born. Pop: 280252 Y: 180. 2907m and 2907f born. Pop: 282257 Y: 181. 3885m and 3885f born. Pop: 286016 Y: 182. 2745m and 2745f born. Pop: 287447 Y: 183. 4266m and 4266f born. Pop: 292152 Y: 184. 2058m and 2058f born. Pop: 292271 Y: 185. 2785m and 2785f born. Pop: 293619 Y: 186. 3933m and 3933f born. Pop: 297289 Y: 187. 5492m and 5492f born. Pop: 304145 Y: 188. 2072m and 2072f born. Pop: 304075 Y: 189. 3138m and 3138f born. Pop: 306233 Y: 190. 2855m and 2855f born. Pop: 307707 Y: 191. 3804m and 3804f born. Pop: 310799 Y: 192. 3404m and 3404f born. Pop: 313075 Y: 193. 5150m and 5150f born. Pop: 319083 Y: 194. 2245m and 2245f born. Pop: 319144 Y: 195. 3091m and 3091f born. Pop: 320760 Y: 196. 4080m and 4080f born. Pop: 324370 Y: 197. 5624m and 5624f born. Pop: 331087 Y: 198. 2435m and 2435f born. Pop: 331364 Y: 199. 3769m and 3769f born. Pop: 334521 Y: 200. 2872m and 2872f born. Pop: 335699 Y: 201. 3833m and 3833f born. Pop: 338495 Y: 202. 4051m and 4051f born. Pop: 341704 Y: 203. 5973m and 5973f born. Pop: 348982 Y: 204. 2394m and 2394f born. Pop: 348960 Y: 205. 3370m and 3370f born. Pop: 350811 Y: 206. 4153m and 4153f born. Pop: 354227 ``` And breakdown of those alive at year 207: ``` 0 yr olds: 4153 males and 4153 females. 1 yr olds: 3370 males and 3370 females. 2 yr olds: 2394 males and 2394 females. 3 yr olds: 5973 males and 5973 females. 4 yr olds: 4051 males and 4051 females. 5 yr olds: 3794 males and 3603 females. 6 yr olds: 2843 males and 2699 females. 7 yr olds: 3731 males and 3542 females. 8 yr olds: 2410 males and 2288 females. 9 yr olds: 5567 males and 5286 females. 10 yr olds: 4039 males and 3835 females. 11 yr olds: 3060 males and 2905 females. 12 yr olds: 2222 males and 2110 females. 13 yr olds: 5098 males and 4841 females. 14 yr olds: 3369 males and 3199 females. 15 yr olds: 3765 males and 3575 females. 16 yr olds: 2826 males and 2683 females. 17 yr olds: 3106 males and 2949 females. 18 yr olds: 2026 males and 1923 females. 19 yr olds: 5306 males and 5038 females. 20 yr olds: 3753 males and 3564 females. 21 yr olds: 2625 males and 2491 females. 22 yr olds: 1915 males and 1818 females. 23 yr olds: 3925 males and 3727 females. 24 yr olds: 2493 males and 2368 females. 25 yr olds: 3488 males and 3311 females. 26 yr olds: 2576 males and 2447 females. 27 yr olds: 2437 males and 2313 females. 28 yr olds: 1642 males and 1559 females. 29 yr olds: 4451 males and 4228 females. 30 yr olds: 3090 males and 2933 females. 31 yr olds: 2209 males and 2097 females. 32 yr olds: 1629 males and 1547 females. 33 yr olds: 2792 males and 2651 females. 34 yr olds: 1732 males and 1645 females. 35 yr olds: 3140 males and 2983 females. 36 yr olds: 2311 males and 2195 females. 37 yr olds: 1870 males and 1775 females. 38 yr olds: 1303 males and 1237 females. 39 yr olds: 3609 males and 3425 females. 40 yr olds: 2444 males and 2319 females. 41 yr olds: 1808 males and 1715 females. 42 yr olds: 1346 males and 1277 females. 43 yr olds: 1967 males and 1869 females. 44 yr olds: 1215 males and 1152 females. 45 yr olds: 2895 males and 2747 females. 46 yr olds: 2112 males and 2005 females. 47 yr olds: 1541 males and 1461 females. 48 yr olds: 1092 males and 1037 females. 49 yr olds: 2740 males and 2603 females. 50 yr olds: 1789 males and 1698 females. 51 yr olds: 1633 males and 1552 females. 52 yr olds: 1220 males and 1158 females. 53 yr olds: 1459 males and 1384 females. 54 yr olds: 928 males and 881 females. 55 yr olds: 2559 males and 2429 females. 56 yr olds: 1847 males and 1755 females. 57 yr olds: 1125 males and 1066 females. 58 yr olds: 818 males and 776 females. 59 yr olds: 1985 males and 1885 females. 60 yr olds: 1241 males and 1177 females. 61 yr olds: 1416 males and 1345 females. 62 yr olds: 1056 males and 1000 females. 63 yr olds: 1147 males and 1090 females. 64 yr olds: 766 males and 725 females. 65 yr olds: 2297 males and 2178 females. 66 yr olds: 1626 males and 1543 females. 67 yr olds: 997 males and 945 females. 68 yr olds: 725 males and 687 females. 69 yr olds: 1306 males and 1240 females. 70 yr olds: 693 males and 657 females. 71 yr olds: 1111 males and 1055 females. 72 yr olds: 745 males and 709 females. 73 yr olds: 592 males and 559 females. 74 yr olds: 365 males and 346 females. 75 yr olds: 990 males and 939 females. 76 yr olds: 612 males and 583 females. 77 yr olds: 278 males and 263 females. 78 yr olds: 189 males and 177 females. 79 yr olds: 304 males and 289 females. 80 yr olds: 157 males and 149 females. 81 yr olds: 351 males and 332 females. 82 yr olds: 232 males and 221 females. 83 yr olds: 156 males and 148 females. 84 yr olds: 95 males and 90 females. 85 yr olds: 270 males and 256 females. 86 yr olds: 156 males and 149 females. 87 yr olds: 105 males and 99 females. 88 yr olds: 67 males and 63 females. 89 yr olds: 76 males and 72 females. 90 yr olds: 39 males and 36 females. 91 yr olds: 115 males and 108 females. 92 yr olds: 73 males and 70 females. 93 yr olds: 36 males and 34 females. 94 yr olds: 20 males and 19 females. 95 yr olds: 56 males and 54 females. 96 yr olds: 27 males and 27 females. 97 yr olds: 13 males and 12 females. 98 yr olds: 6 males and 5 females. 99 yr olds: 16 males and 13 females. ```
190,182	<p>Situation: A very large reservoir of water exists raised up above a large expanse of almost flat land. From the bottom of the reservoir the land falls away at a very gentle gradient of ~1 in 10,000. The output of the water in the high reservoir can be controlled via a series of sluice gates to deliver anywhere between 0 and 1000 cubic meters water flow per second down onto the flat land below.</p> <p>The people want to build a canal across the flat land to deliver water from the bottom of the reservoir into a river 400km away. Which of the flowing would be the easiest way to do this and what are the likely difficulties?</p> <ol> <li>They must dig the whole 400km out before letting the water in.</li> <li>They can just let the water out and it will find its own way to the river and dig its own channel</li> <li>They will need to dig a wide shallow guide channel and then let the flowing water expand that</li> <li>They will need to dig a narrow deep guide channel and then let the flow erode the sides</li> </ol> <p>Would it be better to use a steady or pulsed flow rate?#</p> <p><strong>edit for clarity</strong></p> <p>The ground is generally loose material such as sand, loam or clay and is mostly homogeneous. The surface is dry but becomes increasingly damp as you dig through it down to the water table. If it makes a big difference describe why it does.</p> <p>Assume the reservoir is large enough to provide a constant flow of water indefinitely at the flow rate selected at the sluice gates. The water can flow at any desired rate and can be channeled into a deep torrent or a wide shallow stream when it passes through the sluice gates. The foundation of the reservoir will not be undermined (out of scope).</p> <p>Another way to think of this is given the starting situation can the water dig it's own channel? If so how best to organise the flow to encourage it.</p> <p><a href="https://i.stack.imgur.com/JbJww.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/JbJww.jpg" alt="Example of situation" /></a></p>	[ { "answer_id": 190192, "author": "AlexP", "author_id": 29552, "author_profile": "https://worldbuilding.stackexchange.com/users/29552", "pm_score": 3, "selected": false, "text": "<ol>\n<li><p><em>"A very large reservoir of water exists raised up above a large expanse of almost flat l...	2020/11/17	[ "https://worldbuilding.stackexchange.com/questions/190182", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/42450/" ]	Situation: A very large reservoir of water exists raised up above a large expanse of almost flat land. From the bottom of the reservoir the land falls away at a very gentle gradient of ~1 in 10,000. The output of the water in the high reservoir can be controlled via a series of sluice gates to deliver anywhere between 0 and 1000 cubic meters water flow per second down onto the flat land below. The people want to build a canal across the flat land to deliver water from the bottom of the reservoir into a river 400km away. Which of the flowing would be the easiest way to do this and what are the likely difficulties? 1. They must dig the whole 400km out before letting the water in. 2. They can just let the water out and it will find its own way to the river and dig its own channel 3. They will need to dig a wide shallow guide channel and then let the flowing water expand that 4. They will need to dig a narrow deep guide channel and then let the flow erode the sides Would it be better to use a steady or pulsed flow rate?# edit for clarity The ground is generally loose material such as sand, loam or clay and is mostly homogeneous. The surface is dry but becomes increasingly damp as you dig through it down to the water table. If it makes a big difference describe why it does. Assume the reservoir is large enough to provide a constant flow of water indefinitely at the flow rate selected at the sluice gates. The water can flow at any desired rate and can be channeled into a deep torrent or a wide shallow stream when it passes through the sluice gates. The foundation of the reservoir will not be undermined (out of scope). Another way to think of this is given the starting situation can the water dig it's own channel? If so how best to organise the flow to encourage it. [![Example of situation](https://i.stack.imgur.com/JbJww.jpg)](https://i.stack.imgur.com/JbJww.jpg)	1. "A very large reservoir of water exists raised up above a large expanse of almost flat land. From the bottom of the reservoir the land falls away at a very gentle gradient of ~1 in 10,000. [...] The people want to build a canal across the flat land to deliver water from the bottom of the reservoir into a river 400km away." First of all, they need to dig a large compensation reservoir in order to be able to control the hidraulic head of the water flowing into the canal. You absolutely don't want the water source to be hundreds of meters above your canal, with the water being delivered directly under high pressure by a [penstock](https://en.wikipedia.org/wiki/Penstock). What they want is something like this: ``` \-------------------/ \ - - Upper - - - / control valve ___ constant level of water \ - reservoir - / \|\| \| \ - - - - - - /____\|\|___\--------------v--/--\|\|----------------------- \ - - - - - __penstock___ compensation ____\|\|_________canal_________ \---------/ \|\| \ reservoir / \|\| \-----------/ outflow sluice ``` 2. 1 in 10,000 is a small gradient; water will flow slowly: they will need a very large canal in order to deliver a debit of 1,000 m³/sec. For comparison, the average slope of the lower course of the Nile, from Aswan to the sea, is 1 in 13,300; with an average discarge of about 2800 m³/sec, the river is 2.8 km (1.7 miles) wide and about 10 meters deep. Their canal would be about 1 km (0.6 miles) wide. That is a very wide canal. 3. Rivers flowing over small gradients tend to shift their courses unpredictably unless controlled. The people will need to expend a significant budget of resources and workforce in maintaining the canal. 4. A large river is a powerful erosion force. They won't be able to convince it to flow freely over a constant gradient from the compensation reservoir to the sea. This is a consequence of the [principle of least action](https://en.wikipedia.org/wiki/Principle_of_least_action); if they let the water flow freely, it will tend to dig down a deep valley at the source, and a very wide valley towards its mouth. They don't want this, and therefore they will need to engineer the course of the canal into sections separated by dams or weirs. 5. Now coming to the four options presented by the question: * Option 1, dig the canal before letting the water in: this may result in a stable canal, provided they know what they are doing. They don't need to dig all of it before letting the water in: they can dig a section, let water flow into it, then dig another section and so on. * Options 2, 3, and 4 all come down to letting the river cut its course any way it sees fit: this will result in a natural river, not a canal. They will have to adopt option 1 for the initial part of the river at the exit from the compensation reservoir, or else the river will erode their work. Those options are great if the plain is not populated when they let the water flow -- they can let the river stabilize and then bring in the inhabitants. But if they want to be able to predict the course of the river, or if they don't want to allow it to adopt the variable slope profile of a natural river, then these options are not recommended.
191,678	<p>I would like to have in my story an animal alien species with a long lifespan. By 'long' let's assume an average lifespan of 7000 (Earth) years to give a rough idea. Would be nice to give a scientific basis to justify it.</p> <p>Considerations: (for brevity am going to name this lifeform 'IT')</p> <ul> <li>IT is an animal and its metabolism is active during its lifespan. So not like the 30000 years old nematode worms.</li> <li>IT was either bred or genetically engineered by another species to be a thinking machine (not necessarily a fast one). An ideal environment was setup. So no predation, no evolutionary pressure.</li> <li>other species with much shorter lifespan are tasked to provide IT's needs. Feeding, cleaning, lobe massaging... whatever.</li> <li>IT may have a slow metabolism. Does not have to be quick to either catch food or avoid predation. Does not need quick thinking.</li> <li>IT has an evolved brain. While I don't want to use the term human-like intelligence (actually it will reason in very different ways) but is certainly capable of solving complex theoretical and practical problems... in due time. It excels in deep, parallel, creative thinking.</li> <li>Size is not a constraint, it is of the correct size to be able to live so long while supporting its complex thinking.</li> <li>Reproduction is not an issue. We can assume IT can not reproduce and is instead grown in special facilities.</li> </ul> <p>Question: <strong>what chemistry would justify such a long lifespan best?</strong></p> <hr /> <p>What I found out so far:<br /> Aging and lifespan are two different aspects and not all the factors are well understood. What makes beings age? What gives them a longer lifespan?</p> <blockquote> <p>Aging is a global decline of physiological functions, leading to an increased susceptibility to diseases and ultimately death. Maximum lifespans differ up to 200-fold between mammalian species.</p> </blockquote> <p>In a somewhat related <a href="https://worldbuilding.stackexchange.com/questions/36085/how-can-a-molecule-grant-long-life">question</a> @Serban Tanasa replied:</p> <blockquote> <p>Aging is a complex and barely understood process. While some animals have lifespans of centuries, others live for mere months. It is unclear why.</p> </blockquote> <blockquote> <p>We know that what we call aging involves multiple cross-linked systems. Here's De Grey's breakdown of different types of aging damage from SENS:</p> </blockquote> <pre><code>Mutations in chromosomes Mutations in mitochondria. Intracellular Junk Extracellular Junk Cellular Loss Cell senescence Extracellular protein crosslinks </code></pre> <hr /> <p>and from: <a href="https://i.stack.imgur.com/TkEf1.jpg" rel="nofollow noreferrer">BBC - the tricks that help some animals live for centuries</a></p> <blockquote> <p>Indeed, one of the most deeply-entrenched ideas about animal lifespan is that it is closely linked to metabolic rate – or the speed of chemical reactions that break food down into energy and produce compounds needed by cells. The notion that animals undergo cumulative damage and die sooner when they work harder like machines run at full capacity probably dates back to the Industrial Revolution.</p> </blockquote> <blockquote> <p>In fact, the idea that the more oxygen an animal consumes, the greater the production of free radicals that cause damage, and therefore the swifter the ageing, is now outdated. That is thanks to more detailed studies of mitochondria, the parts of cells that generate energy.</p> </blockquote> <p>So this suggests that IT should not need to be slow in order to live a long life.<br /> Another aspect of long living is defense against DNA damage (including cancer).</p> <blockquote> <p>In a study published in 2013, Magalhães and colleague Yang Li compared the genomes of pairs of similar mammals with both significantly different maximum lifespans and similar lifespans. They found that genes involved in response to DNA damage and the recycling of proteins by cells had evolved more rapidly in longer-lived species.</p> <p>In 2015, he went on to lead a group that sequenced the genome of the bowhead whale, revealing species-specific mutations in genes linked to DNA damage response, the regulation of cell cycles and the control of cancer.</p> <p>In 2015, a team led by Joshua Schiffman, of the University of Utah, calculated that fewer than 5% of captive elephants die from cancers, compared to a cancer mortality rate of 11-25% in humans. When they looked at data from sequencing studies, they found the African elephant has 40 copies of the gene that encodes p53 – a protein that plays a key anti-cancer role, by either preventing cells with damaged DNA from dividing until repairs have been performed, or triggering them to commit suicide. Asian elephants have 30 to 40 copies. Both humans and the rock hyrax, elephants' closest living relative, have just two copies of the gene.</p> </blockquote> <p>This <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5679293/" rel="nofollow noreferrer">paper</a> in particular details the evidence supporting the role of anti-cancer mechanisms, DNA repair machinery, insulin/IGF1 signaling, and proteostasis in defining species lifespans.</p> <p>These mechanisms can be summarized in the following diagram: <a href="https://i.stack.imgur.com/TkEf1.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/TkEf1.jpg" alt="molecular mechanisms affecting lifespan" /></a></p> <p>Of course IT may not be based on DNA. Nevertheless it will have a molecule or group of molecules used for cellular replication. Thus it will have to face challenges similar to DNA based creatures.</p> <hr /> <p>While <a href="https://jeb.biologists.org/content/208/9/1717" rel="nofollow noreferrer">here</a> is an overview of the relation between body size, energy metabolism and lifespan.<br /> The main two theories in modern times being the rate of living theory (ROLT) and the free-radical theory (FRT) While there is no definitive proof</p> <blockquote> <p>The free-radical theory of ageing provides a potential mechanism that links metabolism to ageing phenomena, since oxygen free radicals are formed as a by-product of oxidative phosphorylation. Despite this potential synergy in these theoretical approaches, the free-radical theory has grown in stature while the rate of living theory has fallen into disrepute.</p> </blockquote> <p>Definition of oxidative phosphorylation:</p> <blockquote> <p>Oxidative phosphorylation [...] is the metabolic pathway in which cells use enzymes to oxidize nutrients, thereby releasing the chemical energy stored within [...]. In most eukaryotes, this takes place inside mitochondria. Almost all aerobic organisms carry out oxidative phosphorylation. This pathway is so pervasive because the energy of the double bond of oxygen is so much higher than the energy of the double bond in carbon dioxide or in pairs of single bonds in organic molecules observed in alternative fermentation processes such as anaerobic glycolysis.<br /> <a href="https://en.wikipedia.org/wiki/Oxidative_phosphorylation" rel="nofollow noreferrer">Oxidative phosphorylation</a></p> </blockquote> <p>So I wonder: this process is undoubtedly valuable for animals that are competing for survival. But maybe a lab constructed lifeform could be built on a different basis. A biochemistry that may yield lower <a href="https://en.wikipedia.org/wiki/Adenosine_triphosphate" rel="nofollow noreferrer">ATP</a> but with the advantage of a longer overall lifespan for the organism. I understand xenobiologists don't abound on SE. Am not looking for hard science though, just some plausible explanation.</p>	[ { "answer_id": 194257, "author": "Karst", "author_id": 81947, "author_profile": "https://worldbuilding.stackexchange.com/users/81947", "pm_score": 2, "selected": false, "text": "<p>One possibility is that this creature isn't an oxygen-breather at all. There are several other gases and l...	2020/12/09	[ "https://worldbuilding.stackexchange.com/questions/191678", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/75264/" ]	I would like to have in my story an animal alien species with a long lifespan. By 'long' let's assume an average lifespan of 7000 (Earth) years to give a rough idea. Would be nice to give a scientific basis to justify it. Considerations: (for brevity am going to name this lifeform 'IT') * IT is an animal and its metabolism is active during its lifespan. So not like the 30000 years old nematode worms. * IT was either bred or genetically engineered by another species to be a thinking machine (not necessarily a fast one). An ideal environment was setup. So no predation, no evolutionary pressure. * other species with much shorter lifespan are tasked to provide IT's needs. Feeding, cleaning, lobe massaging... whatever. * IT may have a slow metabolism. Does not have to be quick to either catch food or avoid predation. Does not need quick thinking. * IT has an evolved brain. While I don't want to use the term human-like intelligence (actually it will reason in very different ways) but is certainly capable of solving complex theoretical and practical problems... in due time. It excels in deep, parallel, creative thinking. * Size is not a constraint, it is of the correct size to be able to live so long while supporting its complex thinking. * Reproduction is not an issue. We can assume IT can not reproduce and is instead grown in special facilities. Question: what chemistry would justify such a long lifespan best? --- What I found out so far: Aging and lifespan are two different aspects and not all the factors are well understood. What makes beings age? What gives them a longer lifespan? > > Aging is a global decline of physiological functions, leading to an increased susceptibility to diseases and ultimately death. Maximum lifespans differ up to 200-fold between mammalian species. > > > In a somewhat related [question](https://worldbuilding.stackexchange.com/questions/36085/how-can-a-molecule-grant-long-life) @Serban Tanasa replied: > > Aging is a complex and barely understood process. While some animals have lifespans of centuries, others live for mere months. It is unclear why. > > > > > We know that what we call aging involves multiple cross-linked systems. Here's De Grey's breakdown of different types of aging damage from SENS: > > > ``` Mutations in chromosomes Mutations in mitochondria. Intracellular Junk Extracellular Junk Cellular Loss Cell senescence Extracellular protein crosslinks ``` --- and from: [BBC - the tricks that help some animals live for centuries](https://i.stack.imgur.com/TkEf1.jpg) > > Indeed, one of the most deeply-entrenched ideas about animal lifespan is that it is closely linked to metabolic rate – or the speed of chemical reactions that break food down into energy and produce compounds needed by cells. The notion that animals undergo cumulative damage and die sooner when they work harder like machines run at full capacity probably dates back to the Industrial Revolution. > > > > > In fact, the idea that the more oxygen an animal consumes, the greater the production of free radicals that cause damage, and therefore the swifter the ageing, is now outdated. That is thanks to more detailed studies of mitochondria, the parts of cells that generate energy. > > > So this suggests that IT should not need to be slow in order to live a long life. Another aspect of long living is defense against DNA damage (including cancer). > > In a study published in 2013, Magalhães and colleague Yang Li compared the genomes of pairs of similar mammals with both significantly different maximum lifespans and similar lifespans. They found that genes involved in response to DNA damage and the recycling of proteins by cells had evolved more rapidly in longer-lived species. > > > In 2015, he went on to lead a group that sequenced the genome of the bowhead whale, revealing species-specific mutations in genes linked to DNA damage response, the regulation of cell cycles and the control of cancer. > > > In 2015, a team led by Joshua Schiffman, of the University of Utah, calculated that fewer than 5% of captive elephants die from cancers, compared to a cancer mortality rate of 11-25% in humans. When they looked at data from sequencing studies, they found the African elephant has 40 copies of the gene that encodes p53 – a protein that plays a key anti-cancer role, by either preventing cells with damaged DNA from dividing until repairs have been performed, or triggering them to commit suicide. Asian elephants have 30 to 40 copies. Both humans and the rock hyrax, elephants' closest living relative, have just two copies of the gene. > > > This [paper](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5679293/) in particular details the evidence supporting the role of anti-cancer mechanisms, DNA repair machinery, insulin/IGF1 signaling, and proteostasis in defining species lifespans. These mechanisms can be summarized in the following diagram: [![molecular mechanisms affecting lifespan](https://i.stack.imgur.com/TkEf1.jpg)](https://i.stack.imgur.com/TkEf1.jpg) Of course IT may not be based on DNA. Nevertheless it will have a molecule or group of molecules used for cellular replication. Thus it will have to face challenges similar to DNA based creatures. --- While [here](https://jeb.biologists.org/content/208/9/1717) is an overview of the relation between body size, energy metabolism and lifespan. The main two theories in modern times being the rate of living theory (ROLT) and the free-radical theory (FRT) While there is no definitive proof > > The free-radical theory of ageing provides a potential mechanism that links metabolism to ageing phenomena, since oxygen free radicals are formed as a by-product of oxidative phosphorylation. Despite this potential synergy in these theoretical approaches, the free-radical theory has grown in stature while the rate of living theory has fallen into disrepute. > > > Definition of oxidative phosphorylation: > > Oxidative phosphorylation [...] is the metabolic pathway in which cells use enzymes to oxidize nutrients, thereby releasing the chemical energy stored within [...]. In most eukaryotes, this takes place inside mitochondria. Almost all aerobic organisms carry out oxidative phosphorylation. This pathway is so pervasive because the energy of the double bond of oxygen is so much higher than the energy of the double bond in carbon dioxide or in pairs of single bonds in organic molecules observed in alternative fermentation processes such as anaerobic glycolysis. > > [Oxidative phosphorylation](https://en.wikipedia.org/wiki/Oxidative_phosphorylation) > > > So I wonder: this process is undoubtedly valuable for animals that are competing for survival. But maybe a lab constructed lifeform could be built on a different basis. A biochemistry that may yield lower [ATP](https://en.wikipedia.org/wiki/Adenosine_triphosphate) but with the advantage of a longer overall lifespan for the organism. I understand xenobiologists don't abound on SE. Am not looking for hard science though, just some plausible explanation.	One possibility is that this creature isn't an oxygen-breather at all. There are several other gases and liquids, such as chlorine, that have been proposed as a possible "breathing medium" for extraterrestrial life. If this entity isn't using oxygen, the free-radicals problem vanishes. Another possibility is that it's something along the lines of a [clonal colony](https://en.wikipedia.org/wiki/Clonal_colony). In this setup, a sessile organism sends out shoots which develop into duplicates of itself, connected by a root system. There's no apparent upper limit on size, and the survival of the colony isn't dependent on any one clone. In plants such as trees and grasses, they can keep going for tens of thousands of years. (Of course, these two ideas aren't mutually exclusive.)
191,893	<p>The inhabitants of my Earth similar world have a preindustrial society, but have managed to create airships. These use plywood, hot air and relatively thick material for the envelope. But these inefficient craft are fully practical thanks to the recent discovery of <em>Heavenium</em> which can reduce the weight of these airships by up to 90%.</p> <p>How can the inhabitants of my world use <em>Heavenium</em> to propel these airships forward? And are there any obvious inconsistencies with <em>Heavenium</em>?</p> <p><em>Heavenium</em> is a light weight red colored substance found in some rare mineral veins. It is inert and has defied all analysis. When it absorbs heat it reduces the effect of gravity in its vicinity. After sufficient heating a large quantity of <em>Heavenium</em> can reduce the effect of gravity in its vicinity by up to 90%.</p> <p>The effect rapidly decays with distance (inverse square law) so that things more than around 10m away from it feel little effect. The gravity reduction effect lasts for many days after which the <em>Heavenium</em> needs to be strongly heated again.</p> <p>If used to transfer potential energy into objects by moving them higher the <em>Heavenium</em> become discharged. The amount of discharge is directly related to the amount potential energy transferred (energy is conserved).</p>	[ { "answer_id": 191894, "author": "elemtilas", "author_id": 37029, "author_profile": "https://worldbuilding.stackexchange.com/users/37029", "pm_score": 1, "selected": false, "text": "<ol>\n<li>I don't see any obvious logical inconsistencies with the concept of <em>heavenium</em> itself. I...	2020/12/12	[ "https://worldbuilding.stackexchange.com/questions/191893", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/42450/" ]	The inhabitants of my Earth similar world have a preindustrial society, but have managed to create airships. These use plywood, hot air and relatively thick material for the envelope. But these inefficient craft are fully practical thanks to the recent discovery of Heavenium which can reduce the weight of these airships by up to 90%. How can the inhabitants of my world use Heavenium to propel these airships forward? And are there any obvious inconsistencies with Heavenium? Heavenium is a light weight red colored substance found in some rare mineral veins. It is inert and has defied all analysis. When it absorbs heat it reduces the effect of gravity in its vicinity. After sufficient heating a large quantity of Heavenium can reduce the effect of gravity in its vicinity by up to 90%. The effect rapidly decays with distance (inverse square law) so that things more than around 10m away from it feel little effect. The gravity reduction effect lasts for many days after which the Heavenium needs to be strongly heated again. If used to transfer potential energy into objects by moving them higher the Heavenium become discharged. The amount of discharge is directly related to the amount potential energy transferred (energy is conserved).	Heavenium engine ---------------- Take an ordinary water wheel. No water. Put a piece of heavenium under one side of the wheel. The side above the heavenium will become lighter, and the wheel will rotate. Use this heavenium engine to power propellers. Problem solved. Note that the same principle can be used to power lathes, mills, mechanican looms, spinning jennies, and so on. Heavenium engines will power a fervent industrial revolution. After the discovery of heavenium, your society won't remain preindustrial for long. ``` This This half half is is heavy light _____ / \ / \ \| <> \| \ / \_____/ ^^^^^ heavenium ```
192,409	<p>I'm having a tough time coming up with good weights for my weapons to allow me to calculate what swords would take longer to swing, for example.</p> <p>Here is what I have come up with so far:</p> <pre><code>Dagger: 430g - quick attack speed but not as much damage. Sword: 800g - standard attack speed standard damage. Longsword: 1500g - slow attack speed but high damage. Bow: ?? - standard draw speed?, standard damage? Longbow?: ?? - slow draw speed?, high damage? </code></pre> <p>I can't think of any other weapons which offer a different fighting style, but don't step away from the classic fighting experience. My game is an Fantasy MMORPG, but a very small portion is PVP. It kinda follows Sword Art Online (the anime), with it's atmosphere, architecture and weapons, but the gameplay itself is nothing like it. I don't want too many weapons as there will be many materials used to craft these weapons which would affect the weight and benefits, but if there is a clear option which you think I should add, please do let me know of course.</p> <p>I just need these weights as a base starting point, and then I can adjust the weight/speed and damage depending on the fictional material used to make the weapon.</p> <p>I had absolutely no idea what to do with the bow(s), ideally I want 2 different types of bows to allow for a more ranged gameplay (pun unintended( but I don't think they are that different irl, so I might just stick with the normal bow.</p> <p>Thanks for your input!</p>	[ { "answer_id": 192422, "author": "Ash", "author_id": 78800, "author_profile": "https://worldbuilding.stackexchange.com/users/78800", "pm_score": 3, "selected": false, "text": "<h3>0.9 - 2.3kg for standard bow. 0.9 - 1.8kg for long bow:</h3>\n<blockquote>\n<p>The physical weight of a trad...	2020/12/20	[ "https://worldbuilding.stackexchange.com/questions/192409", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/81408/" ]	I'm having a tough time coming up with good weights for my weapons to allow me to calculate what swords would take longer to swing, for example. Here is what I have come up with so far: ``` Dagger: 430g - quick attack speed but not as much damage. Sword: 800g - standard attack speed standard damage. Longsword: 1500g - slow attack speed but high damage. Bow: ?? - standard draw speed?, standard damage? Longbow?: ?? - slow draw speed?, high damage? ``` I can't think of any other weapons which offer a different fighting style, but don't step away from the classic fighting experience. My game is an Fantasy MMORPG, but a very small portion is PVP. It kinda follows Sword Art Online (the anime), with it's atmosphere, architecture and weapons, but the gameplay itself is nothing like it. I don't want too many weapons as there will be many materials used to craft these weapons which would affect the weight and benefits, but if there is a clear option which you think I should add, please do let me know of course. I just need these weights as a base starting point, and then I can adjust the weight/speed and damage depending on the fictional material used to make the weapon. I had absolutely no idea what to do with the bow(s), ideally I want 2 different types of bows to allow for a more ranged gameplay (pun unintended( but I don't think they are that different irl, so I might just stick with the normal bow. Thanks for your input!	I will speak in broader terms, including carrying capacity into the question. Indeed, the two are closely related, and in the end, it's more about the number of items one can hold than the exact weight one item is. But I will getty to that point later. Adjust the weight according to the fight intentions your team wants to give --------------------------------------------------------------------------- What I fear is that you're reversing priorities between core gameplay features and feelings vs flavor. You should focus first on strengths and weaknesses of your weapons, speaking in terms of number of hits to kill, range, speed, special abilities, and feeling they should provide, then to the weapon's weight. Since people cannot carry the sword themselves, weight cannot be felt, and therefore it should be laid out on the background after what they can see, hear or sense (with the controller's vibration). Feeling is more important than a number on the item's description. It goes into the overall look and feel of your game and the intentions you want to give. If this is a heroic fantasy game, boost up weapons's size and weight as your characters are strong, sweaty heroes, not your average farming Joe. If your avatar is living in a dark, realistic world or are weak compared to monsters, decrease them instead to make them look more frail and inefficient against what's to come. It all goes down to the intention of your game. Recall that the intentions should be thought on the whole team level, especially the artists since they will draw how characters and weapons will look like. Marking all your weapons as light and then noticing all artists drew bulky heroes wielding 5 meter swords will make you feel you lost time :). That's the game designer's job to ensure everyone is on the same page. Balance the weight according to the drop quantities and character type average carrying capacity ------------------------------------------------------------------------------------------------ The idea is to not focus on the sole weight, but think it as a whole. For instance, how scarce or plentiful the drops are? Do players can acquire equipment only through crafting (gaining materials from dungeons/jobs). Do you want your players make constant conscious choices over what to keep (Very important if you have lots of single use items or a durability system), or do you want them to be more carefree and grab everything they can find, hack-and-slash style? This, in overall, will determine how much items one should be expected to hold. Often times, you will notice that melee warrior characters will have more carrying capacity than mages or rangers, yet they can carry about the same amount of their class's items because their equipments weigh more. It's partially because if they can carry more, they may become some drop mules which is rarely wanted. However you still want some difference in feelings (as per the first section). Hence, adapt weights to how many items should one be able to carry! Follow the marketing strategy ----------------------------- If your game is following a free-to-play model, you'll probably be influenced by the editor/producer, asking you to restrict how many one can carry items, in order to sell interesting bonus inventory packs. This can be annoying as it brings down your creativity, but sadly, a person can't eat their own bytes of virtual bread from their games. You should take it into consideration and reduce voluntarily the carrying capacity or increase your item's weight in order to incite the buying of such packs. Still, as you are responsible of the quality of the player's feelings, don't overdo it and don't hesitate to tell that it isn't possible without hurting too much the player retention on the long term. Then, in order to not reach a dead end, try to offer an alternative you can more easily negotiate on. Playtest -------- This is a kinda all around solution to all game designers issues, but it works, and really well actually. If your game is not yet in a playable stage, you can make a paper version of your game focusing on drops and weights. For instance, make a fake run through dungeons, and ask which item your testers want to keep, following your set weight rules. Then take their feedbacks and feelings about what you have made. If you don't have anybody available, prepare some tables and play with values around for an estimated game run, and get others' quick feedback (it's always important). It's not as valuable as playtesting, but it formalize things and can give others a rough idea of what to expect, improving their own image of what the game would be. But most of all, keep things simple and focus on gameplay --------------------------------------------------------- Unless your game has one of its pillar be inventory and drop management A.K.A. survival games or simulation games (which, given your description doesn't seem to be the case), you shouldn't spend too much time estimating exact weight/and or size of real world counterpart. Players tend to overestimate the weight of items and even more one's real carrying capacity. Peck, have you seen someone wearing 4 plate armors, 3 bows, 6 (unbroken) potions, 6 swords, spears and shields, a quiver containing 150 arrows and a pouch holding 20 000 gold coins? And yet in games, unless you put visual indicators like in [Death Stranding](https://fr.wikipedia.org/wiki/Death_Stranding), almost nobody will think about it. At worst they will give a smile thinking about their character carrying this much, which isn't even a bad thing! What I mean is that it goes all into the suspension of disbelief. And you can safely retreat behind it, especially since you won't have a lot of time designing your MMO. Yes, you probably won't have a lot of time. Remember, MMOs are one of the most expensive type of game projects in the industry (networking alone multiplies at least by 2 the cost), so you will have a lot of matters to attend to. And since your game involves even a little bit of PvP, you will need some time as a game designer to balance character archetypes and powers. Time that doesn't involve weight calculation unless it impacts the battle gameplay, in which case simulation may not be better than pure-gameplay values. After all, players are more concerned about a balanced experience than that a [real viking sword weighs less than 1 kg](https://www.youtube.com/watch?v=0QDPU0itinU) and in your game it's 5 kg.
193,298	<p>I'm crafting the worlds and cultures of my own Alien societies and a near-future human world (near-future Earth), it's the first time I've attempted this in detail. Everything I've found so far about building cities is based on medieval technology and is unhelpful. I need it to be relevant to now and the near-future.</p> <p>I want to create different kinds of near-future cities but can't wrap my head around all of the complex mechanisms that ensure a city can exist, and also the wider communities beyond, that assist the city to function.</p> <p>These are the scenarios I'm working with:</p> <ol> <li><p>On the near-future Earth, I want to create cities that have been adapted to become more efficient and self sufficient, many major Earth cities will have dome-like structures built over them to protect them from the increasing impact of the sun, whereas any suburbs beyond are struggling to survive without the added protection but are finding ways to adapt.</p> </li> <li><p>One of my alien cultures have a focus on knowledge, gathering and consolidating all knowledge gained within a planet-bound intelligence which acts as a guiding force for the race (besides rebellious subcultures). Their cities are pre-planned, consisting of megastructures/city-towers, with smaller towns of individuals who prefer the quieter life. More or less an optimal version of Earth where global warming is not a future concern due to more efficient planning and energy usage.</p> </li> <li><p>The second alien culture is less functional, struggling to produce each generation of children due to genetic defects/fertility constrictions etc so their focus is upon community support, being able to ensure the optimal health for any pre-fertile individuals up until and after their fertility, and during gestation. I've settled on the idea of "Tiny Villages" where every resource needed within each community is within walking distance for the inhabitants. The examples I've seen of Tiny Villages has been lacking in depth and complexity though. I could perhaps use any answers regarding the city infrastructure to craft this.</p> </li> </ol> <p>Question:</p> <ul> <li><strong>What do I absolutely need to include in major (pop 100,000+ individuals) near-future cities to ensure they function almost on their own (including a minor contribution of external services and resources from wider communities)?</strong></li> </ul> <p>Due to a lack of life experience, I'm struggling to piece together the complex functions of a present Earth whole city enough to adapt them to my own fictional world. Any help will be immensely appreciated!</p>	[ { "answer_id": 193304, "author": "JBH", "author_id": 40609, "author_profile": "https://worldbuilding.stackexchange.com/users/40609", "pm_score": 4, "selected": true, "text": "<h2>What you've asked for is huge, so this is a necessary simplification</h2>\n<p><em>I've made this a community ...	2021/01/04	[ "https://worldbuilding.stackexchange.com/questions/193298", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/81702/" ]	I'm crafting the worlds and cultures of my own Alien societies and a near-future human world (near-future Earth), it's the first time I've attempted this in detail. Everything I've found so far about building cities is based on medieval technology and is unhelpful. I need it to be relevant to now and the near-future. I want to create different kinds of near-future cities but can't wrap my head around all of the complex mechanisms that ensure a city can exist, and also the wider communities beyond, that assist the city to function. These are the scenarios I'm working with: 1. On the near-future Earth, I want to create cities that have been adapted to become more efficient and self sufficient, many major Earth cities will have dome-like structures built over them to protect them from the increasing impact of the sun, whereas any suburbs beyond are struggling to survive without the added protection but are finding ways to adapt. 2. One of my alien cultures have a focus on knowledge, gathering and consolidating all knowledge gained within a planet-bound intelligence which acts as a guiding force for the race (besides rebellious subcultures). Their cities are pre-planned, consisting of megastructures/city-towers, with smaller towns of individuals who prefer the quieter life. More or less an optimal version of Earth where global warming is not a future concern due to more efficient planning and energy usage. 3. The second alien culture is less functional, struggling to produce each generation of children due to genetic defects/fertility constrictions etc so their focus is upon community support, being able to ensure the optimal health for any pre-fertile individuals up until and after their fertility, and during gestation. I've settled on the idea of "Tiny Villages" where every resource needed within each community is within walking distance for the inhabitants. The examples I've seen of Tiny Villages has been lacking in depth and complexity though. I could perhaps use any answers regarding the city infrastructure to craft this. Question: * What do I absolutely need to include in major (pop 100,000+ individuals) near-future cities to ensure they function almost on their own (including a minor contribution of external services and resources from wider communities)? Due to a lack of life experience, I'm struggling to piece together the complex functions of a present Earth whole city enough to adapt them to my own fictional world. Any help will be immensely appreciated!	What you've asked for is huge, so this is a necessary simplification -------------------------------------------------------------------- I've made this a community wiki because a thousand separate answers won't fully answer the question, so we might as well try to build on just one. One of the reasons why most city-building resources focus on medieval cities is that they're small with simple needs. In a phrase: they're easy. Even contemporary cities here on Earth are massively complex by comparison. Future cities would even be worse. But... we can take a bird's eye view at this. BTW, while any individual may consider anything below to be a want vs. a need, the reality is that when you're dealing with large groups of people, this is all a need. Living is complex. Housing ``` - Wealthy housing (expensive, low-density) - Urban housing (moderate cost, medium-density) - Labor housing (low cost-per-unit, high-density) - Welfare housing (very low cost-per-unit, very-high-density) ``` Government ``` - Legislative (makers of law) - Judicial (interpreters of law) * Lawyers - Executive (enforcer of law) * Police/Military * Inspectors (construction) * Regulation (permits/certification/zoning) * Public schools/libraries * Roads & parks ``` Emergency Services ``` - Hospitals/clinics - Ambulance/life-flight/paramedics - Fire - Pharmaceutical companies ``` Commercial ``` - Grocery/restaurants - Services (there are MILLIONS of these things, see below) - Department retail (see below) - Warehousing - Industrial (metal working, brick making, chemical processing) ``` Education ``` - Schools for sub-adults - Colleges/Universities - Vocational & trade - Community education - Big libraries (the Louvre, natural history museums, planetariums) - Pre-school/child-care - Special education ``` Financial ``` - Holding companies - Brokerages/Investing - Banks/Credit Unions ``` Entertainment ``` - Theater/Dance - Art/Literature - Film/Music/Video - Food/Drink - Electronic Services (see below) - Zoos & privately-owned parks - Walking/running trails - Amusement parks/carnivals/parades/celebrations/holidays ``` Religion/Philosophy ``` - Houses of worship - Schools/camps ``` Raw Materials ``` - Lumber - Mining - Farming/Ranching/Fishing - Hydroponics - Chemical processing ``` Utilities ``` - Water (transport, sanitation) & Sewage (collection, processing & disposal) - Natural gas/propane - Electricity - Communication (phone, internet, radio/broadcast) - Fuel (gasoline/oil/diesel, nuclear fuel & control-rods, coal) ``` Black Market ``` - Drugs - Pornography - Rare/protected species - Organized crime (mafia, gangs) ``` Heritage ``` - Architectural preservation - Wilderness preservation - Monuments ``` Transportation ``` - Roads & bridges (traffic control, cars/trucks/buses/bicycles/motorcycles...) - Waterways (canals, sluices, locks, ships & boats) - Ocean (docks, dredging, ships & boats) - Rail (iron rail, monorail, maglev) - Air Flight (air planes, radar, traffic control) - Space Flight (launch/recovery, radar, traffic control... space stations...) ``` And one more thing... All of the INFRASTRUCTURE that supports everything above. Concrete/asphalt plants, makers of pencils, janitors, caterers, dog walkers, ditch diggers, environmental activists, manufacturing of all kinds (think TOOLS, and that's just the start).... The category of infrastructure is breathtakingly enormous.* Go to [Alibaba.com](http://alibaba.com) and browse. We live in a world of machines and stuff that's all but incomprehensible.* Remember, this was a simplification ----------------------------------- And to be honest, it's a simplification to the degree that angels weep. --- Some of the above categories are so broad that they needed a bit of insight. I'm going to name only a few examples. This list can literally be *endless.* * Services: nail salons/grooming, accountants, realtors, arts/crafts, car repair, yoga instructors, carpet layers, carpenters, consultants, psychologists, counselors. * Department retail: hardware, clothing, furniture, household goods, industrial goods, commercial support, almost anything you can find in a shopping mall. * Electronic services: games, social media, information exchange & processing, blogs, corporate/company contact.
193,482	<p>We have a sun that is like ours, does not matter I think because of scaling. That sun is completely encased in large rock formations like that of a planet. Basically if you replace the core of a planet with a sun.</p> <p>Obviously I want it to be naturally formed planet but the focus on the theoretical aspect of it is more important since the universe is a big place it's enough to know it <em>could</em> happen.</p> <p>I understand there are complications regarding other aspects but I'm only focusing on one thing here and will ask later about other problems. I want it later to orbit a sun and have an atmosphere...etc But again I just wanna focus on one aspect:</p> <p><strong>Is such a thing even theoretically possible?</strong></p> <p><strong>And what type of real or theoretical material would be used? to achieve that idea?</strong></p> <p>I understand that those are two things, do they need to be broken? But I'm worried that it would get closed if the question has a simple yes or no answer.</p> <h2>Extra fluff!</h2> <p><a href="https://solarsystem.nasa.gov/planets/in-depth/" rel="nofollow noreferrer">NASA says a planet must</a></p> <pre><code>It must orbit a star (in our cosmic neighborhood, the Sun). It must be big enough to have enough gravity to force it into a spherical shape. It must be big enough that its gravity cleared away any other objects of a similar size near its orbit around the Sun. </code></pre> <p>However I'm only interested in figuring out this first step now, could it be real?</p> <p>I'm well aware that the gravity of the sun is huge. Even one like ours has a lot of gravity. So. This is part of the question. I mean that what type of material could withstand such gravity</p> <p>Obviously, the sun also outputs a lot of energy. So the planet will have to find a way to handle that if possible.</p> <p>I'm content if it not even theoretically possible. But I'd just love to know more on why.</p> <p>I will ask about an atmosphere later, as well as if it can orbit a star or not...etc Just want it to be focused.</p>	[ { "answer_id": 193484, "author": "Slarty", "author_id": 42450, "author_profile": "https://worldbuilding.stackexchange.com/users/42450", "pm_score": 6, "selected": true, "text": "<p>No this is not even remotely possible. The gravitational attraction of a star would be great enough to suck...	2021/01/06	[ "https://worldbuilding.stackexchange.com/questions/193482", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/69342/" ]	We have a sun that is like ours, does not matter I think because of scaling. That sun is completely encased in large rock formations like that of a planet. Basically if you replace the core of a planet with a sun. Obviously I want it to be naturally formed planet but the focus on the theoretical aspect of it is more important since the universe is a big place it's enough to know it could happen. I understand there are complications regarding other aspects but I'm only focusing on one thing here and will ask later about other problems. I want it later to orbit a sun and have an atmosphere...etc But again I just wanna focus on one aspect: Is such a thing even theoretically possible? And what type of real or theoretical material would be used? to achieve that idea? I understand that those are two things, do they need to be broken? But I'm worried that it would get closed if the question has a simple yes or no answer. Extra fluff! ------------ [NASA says a planet must](https://solarsystem.nasa.gov/planets/in-depth/) ``` It must orbit a star (in our cosmic neighborhood, the Sun). It must be big enough to have enough gravity to force it into a spherical shape. It must be big enough that its gravity cleared away any other objects of a similar size near its orbit around the Sun. ``` However I'm only interested in figuring out this first step now, could it be real? I'm well aware that the gravity of the sun is huge. Even one like ours has a lot of gravity. So. This is part of the question. I mean that what type of material could withstand such gravity Obviously, the sun also outputs a lot of energy. So the planet will have to find a way to handle that if possible. I'm content if it not even theoretically possible. But I'd just love to know more on why. I will ask about an atmosphere later, as well as if it can orbit a star or not...etc Just want it to be focused.	No this is not even remotely possible. The gravitational attraction of a star would be great enough to suck any surrounding planetary surface sphere into itself. Making the planet or crust deeper would not help either as it would only serve to increase the gravitational field centred on the star. The energy output of the star would also rapidly vaporise any surrounding material. Note your NASA quote number 2 "It must be big enough to have enough gravity to force it into a spherical shape" any object with enough gravity to do this would collapse any hollow sphere.
193,533	<p>Link To Races: <a href="https://worldbuilding.stackexchange.com/questions/190955/rail-transportation-with-races-described-below-specifically-seating">Rail Transportation with Races Described Below - Specifically, Seating</a></p> <p>However, this will be for my intercity and international, trains. Intercity means this: It starts in one city in stops in another. International means between countries. It will also be in the 21st Century, so actual solar panels are available. However, these trains will be underground, power supplied by electricity power lines from elsewhere.</p> <p>I want a different design, still accommodating yet made for 21st Century big cities, like New York City, London, Tokyo, and Beijing. The trains, on a system called Intracity, will only supply a single city, though possible outer city parts will be possible (Outer city being just outside the main city area).</p> <p><em><strong>Here are the Task an Intracity Rail System in these cities must be up to:</strong></em></p> <ol> <li>Hold large numbers of people at a time.</li> <li>Accommodate wings, taurs, people the size of small children, people nearly twice as tall as humans, tails, and actual raptors.</li> <li>Be able to fit underground.</li> <li>May be triple or even quadruple rowed, but everyone must be able to know what stop they're at.</li> </ol> <p><em><strong>How would these Trains be Designed?</strong></em></p>	[ { "answer_id": 193535, "author": "11Bravo", "author_id": 81144, "author_profile": "https://worldbuilding.stackexchange.com/users/81144", "pm_score": 2, "selected": false, "text": "<p>I recommend:</p>\n<p><strong>2 rows of chairs</strong> along the walls facing inwards. The middle space s...	2021/01/07	[ "https://worldbuilding.stackexchange.com/questions/193533", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/80942/" ]	Link To Races: [Rail Transportation with Races Described Below - Specifically, Seating](https://worldbuilding.stackexchange.com/questions/190955/rail-transportation-with-races-described-below-specifically-seating) However, this will be for my intercity and international, trains. Intercity means this: It starts in one city in stops in another. International means between countries. It will also be in the 21st Century, so actual solar panels are available. However, these trains will be underground, power supplied by electricity power lines from elsewhere. I want a different design, still accommodating yet made for 21st Century big cities, like New York City, London, Tokyo, and Beijing. The trains, on a system called Intracity, will only supply a single city, though possible outer city parts will be possible (Outer city being just outside the main city area). *Here are the Task an Intracity Rail System in these cities must be up to:* 1. Hold large numbers of people at a time. 2. Accommodate wings, taurs, people the size of small children, people nearly twice as tall as humans, tails, and actual raptors. 3. Be able to fit underground. 4. May be triple or even quadruple rowed, but everyone must be able to know what stop they're at. *How would these Trains be Designed?*	### Design for the biggest and second biggest side by side, then divide the remaining space. I've categorized the people into 3 groups. Big, Human, and Small. And given them 3 different seat configurations. I haven't drawn the stairs, walls, seat mountings, safety railing, or windows, but I think they're implicit. I've assumed 1500mm seat pitching for the big guys with 5m of headroom and 3m of width for wings, 800mm seat pitching for the human sizes (slightly more generous than an airline) with 3m ceiling (eg - room for overhead bins), and 500mm seat pitches for the small guys, with 2m of roof height for them. But that can be changed based on how dense you want to pack people or the exact size of your races [![enter image description here](https://i.stack.imgur.com/7OY1S.png)](https://i.stack.imgur.com/7OY1S.png) Your big guys have full car height headroom, your humans have the larger ground floor, and your smalls have the upper floor, and their own hallway, but its wide enough can still overtake in the hallway. [![enter image description here](https://i.stack.imgur.com/hLw5i.png)](https://i.stack.imgur.com/hLw5i.png) The car size is 5m wide, 5m high, and 20m long. [![enter image description here](https://i.stack.imgur.com/5p3ET.png)](https://i.stack.imgur.com/5p3ET.png) OpenScad Source ``` color("blue") cube([5000,20000,5]); color("aqua") translate([3000,800,3000]) cube([2000,17000,5]); for (y = [1000:1500:20000]) { translate([200,y,800]) cube([1500,400,5]); translate([200,y,700]) cube([1500,10,700]); } for (y = [1000:800:18000]) { translate([3500,y,400]) cube([1500,400,5]); translate([3500,y,300]) cube([1500,10,700]); } for (y = [1500:500:17500]) { translate([4000,y,3400]) cube([1000,200,5]); translate([4000,y,3300]) cube([1000,10,400]); } ```
195,903	<p>I've got an urban fantasy story set a few decades ago that heavily involves vampires and werewolves, and as such, when exactly the sun and moon were out on a given day is important information for me to know when telling the story. Of course, the issue is that this constantly changes due to various factors that don't precisely sync with the 24 hour clock or even a yearly calendar, causing the moon to be out at different times on different days on different years, which would be excruciatingly difficult to keep track of by hand. Thankfully, since the sun and moon are very real things and the subjects of intense study, there are websites that thoroughly keep track of these things throughout a huge amount of recorded history, and I can easily find out with a quick google search when exactly the sun and moon were out on a given day, what lunar phase it was, etc.</p> <p>But the issue comes if I want to keep track of such things for something that doesn't exist.</p> <p>Suppose, for example, I wanted to add a system to my setting where every 25 hours, time temporarily stops for an hour for almost everything in my setting that isn't magical. This would obviously mean that this event would happen at a different hour of the day every day, and keeping track of what time it would happen each day in a story that takes place over the course of months or even years would be... exhausting.</p> <p>Is there some sort of tool out there that would let me keep track of this? Maybe some software designed for worldbuilders to make fictional calendars for sci-fi stories with their own fictional suns and moons and planets with their own rotations and revolutions?</p>	[ { "answer_id": 195909, "author": "Slarty", "author_id": 42450, "author_profile": "https://worldbuilding.stackexchange.com/users/42450", "pm_score": 1, "selected": false, "text": "<p>This would be easy to achieve with a spreadsheet. Have normal hours in one column and 25 hours in a second...	2021/02/11	[ "https://worldbuilding.stackexchange.com/questions/195903", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/82267/" ]	I've got an urban fantasy story set a few decades ago that heavily involves vampires and werewolves, and as such, when exactly the sun and moon were out on a given day is important information for me to know when telling the story. Of course, the issue is that this constantly changes due to various factors that don't precisely sync with the 24 hour clock or even a yearly calendar, causing the moon to be out at different times on different days on different years, which would be excruciatingly difficult to keep track of by hand. Thankfully, since the sun and moon are very real things and the subjects of intense study, there are websites that thoroughly keep track of these things throughout a huge amount of recorded history, and I can easily find out with a quick google search when exactly the sun and moon were out on a given day, what lunar phase it was, etc. But the issue comes if I want to keep track of such things for something that doesn't exist. Suppose, for example, I wanted to add a system to my setting where every 25 hours, time temporarily stops for an hour for almost everything in my setting that isn't magical. This would obviously mean that this event would happen at a different hour of the day every day, and keeping track of what time it would happen each day in a story that takes place over the course of months or even years would be... exhausting. Is there some sort of tool out there that would let me keep track of this? Maybe some software designed for worldbuilders to make fictional calendars for sci-fi stories with their own fictional suns and moons and planets with their own rotations and revolutions?	### This is an entry-level coding task: So you want something that counts in a pattern that doesn't line up with the days - ie, from input like this: ``` events = [ // Time stops every 25 hours, starting from 3am on day 0 {"name":"Time stops", "periodHours" : 25, "startDay" : 0, "startHour" : 3}, // There's free ice cream every 117 hours, starting from day 3 at 7pm {"name":"Free ice cream", "periodHours" : 117, "startDay" : 3, "startHour" : 19}, ]; ``` will generate output like this? ``` .... Time stops at day 90 at 18:00 Free ice cream at day 91 at 13:00 Time stops at day 91 at 19:00 Time stops at day 92 at 20:00 Time stops at day 93 at 21:00 Time stops at day 94 at 22:00 Time stops at day 95 at 23:00 Free ice cream at day 96 at 10:00 Time stops at day 97 at 0:00 Time stops at day 98 at 1:00 Time stops at day 99 at 2:00 Time stops at day 100 at 3:00 Time stops at day 101 at 4:00 Free ice cream at day 101 at 7:00 Time stops at day 102 at 5:00 .... ``` This is not a big programming task. It's 45 lines of javascript. Here is a [live Demo](https://jsfiddle.net/fL2jd1cm/23/) - you can change the timing and add more events and pick an area of interest in that from a browser. Source code: ``` events = [ // Time stops every 25 hours, starting from 3am on day 0 {"name":"Time stops", "periodHours" : 25, "startDay" : 0, "startHour" : 3}, // There's free ice cream every 117 hours, starting from day 3 at 7pm {"name":"Free ice cream", "periodHours" : 117, "startDay" : 3, "startHour" : 19}, ]; // Your interested in events 10 days either side of day 100 dayYouAreInterestedIn = 100; daysAround = 10; ////////////////////////////// timeline = []; events.forEach(function (i, index) { counter = i.startDay + i.startHour / 24.0; while(counter < dayYouAreInterestedIn - daysAround) { counter += i.periodHours / 24.0; } while(counter < dayYouAreInterestedIn + daysAround) { timeline.push([counter, i.name]); counter += i.periodHours / 24.0; } }); timeline = timeline.sort(function(a, b) { return a[0] - b[0];}); timeline.forEach(function (i, index) { document.getElementById('o').innerHTML += i[1] + " at day " + Math.floor(i[0]) + " at " + Math.round((i[0] * 24) % 24) + ":00<br>"; }); ```
197,861	<p><a href="https://worldbuilding.stackexchange.com/questions/197555/does-the-sun-provide-enough-energy-to-accelerate-a-large-ship-to-a-decent-propor?noredirect=1#comment614113_197555">More thoughts</a> on hard science possibilities for interstellar colonization and the request to check my understanding of physics.</p> <p>Suppose you have a fully self contained colony ship. They have some giant reactor producing power and as long as the reactor has fuel they can produce everything they need for life support on board. This could be with green houses to grow plants for making oxygen and food or it could also be pure chemistry. According to my understanding of physics, as long as it is a closed cycle within the ship all energy will eventually be turned into heat. And as they are in space the only way to lose this heat is through <a href="https://en.wikipedia.org/wiki/Thermal_radiation" rel="nofollow noreferrer">thermal radiation</a>. The <a href="https://en.wikipedia.org/wiki/Stefan%E2%80%93Boltzmann_law" rel="nofollow noreferrer">Stefan–Boltzmann law</a> now gives a way to compute the energy the ship loses through thermal radiation. It only depends on the surface area of the ship and the temperature.</p> <p>It seems that for a fixed surface area and a fixed surface temperature this gives the exact amount of energy the ship needs to use to be in a stable equilibrium?</p> <p>If they use more energy the ship will heat up (which will also increase the thermal radiation), if they use less the ship will cool down (which will also decrease the thermal radiation). As thermal radiation changes with the 4th power of absolute temperature, there is some room for maneuvering but if the energy use is off by an order of magnitude or two in either direction, they have a problem.</p> <p><strong>Edit:</strong> Some specific numbers. In my last question linked above I learned that you need the energy equivalent of the entire energy output of the sun for a few days to accelerate a large space ship to half the speed of light. This means that if the space ship uses the equivalent of all the solar energy hitting the earth (around <span class="math-container">$10^{16}$</span> Watts) for life support and other internal energy needs that is negligible in comparison even over a timespan of decades or centuries. But if we assume a spaceship as a 10km cube and a temperature of 300 Kelvin the total heat radiation by the Stefan-Boltzman law above is only <span class="math-container">$5.6710^{-8}300^4(610^8) W = 2.75*10^{11} W$</span>. Meaning by my naive interpretation of physics they would need to use energy of that order of magnitude to not overcook themselves, for <span class="math-container">$10^{16} W$</span> they would need a much much bigger or hotter spaceship.</p>	[ { "answer_id": 214876, "author": "codeMonkey", "author_id": 8681, "author_profile": "https://worldbuilding.stackexchange.com/users/8681", "pm_score": 2, "selected": false, "text": "<h2>Ships can Control Surface Area and Temperature</h2>\n<p>A star or planet has a (relatively) static surf...	2021/03/15	[ "https://worldbuilding.stackexchange.com/questions/197861", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/69605/" ]	[More thoughts](https://worldbuilding.stackexchange.com/questions/197555/does-the-sun-provide-enough-energy-to-accelerate-a-large-ship-to-a-decent-propor?noredirect=1#comment614113_197555) on hard science possibilities for interstellar colonization and the request to check my understanding of physics. Suppose you have a fully self contained colony ship. They have some giant reactor producing power and as long as the reactor has fuel they can produce everything they need for life support on board. This could be with green houses to grow plants for making oxygen and food or it could also be pure chemistry. According to my understanding of physics, as long as it is a closed cycle within the ship all energy will eventually be turned into heat. And as they are in space the only way to lose this heat is through [thermal radiation](https://en.wikipedia.org/wiki/Thermal_radiation). The [Stefan–Boltzmann law](https://en.wikipedia.org/wiki/Stefan%E2%80%93Boltzmann_law) now gives a way to compute the energy the ship loses through thermal radiation. It only depends on the surface area of the ship and the temperature. It seems that for a fixed surface area and a fixed surface temperature this gives the exact amount of energy the ship needs to use to be in a stable equilibrium? If they use more energy the ship will heat up (which will also increase the thermal radiation), if they use less the ship will cool down (which will also decrease the thermal radiation). As thermal radiation changes with the 4th power of absolute temperature, there is some room for maneuvering but if the energy use is off by an order of magnitude or two in either direction, they have a problem. Edit: Some specific numbers. In my last question linked above I learned that you need the energy equivalent of the entire energy output of the sun for a few days to accelerate a large space ship to half the speed of light. This means that if the space ship uses the equivalent of all the solar energy hitting the earth (around $10^{16}$ Watts) for life support and other internal energy needs that is negligible in comparison even over a timespan of decades or centuries. But if we assume a spaceship as a 10km cube and a temperature of 300 Kelvin the total heat radiation by the Stefan-Boltzman law above is only $5.67\10^{-8}\300^4\(6\10^8) W = 2.75\*10^{11} W$. Meaning by my naive interpretation of physics they would need to use energy of that order of magnitude to not overcook themselves, for $10^{16} W$ they would need a much much bigger or hotter spaceship.	Isolate your habitation section from your reactor section --------------------------------------------------------- Stefan–Boltzmann defines the energy blackbody emissions as: ``` P = AσT⁴ ``` Or for those of us who actually like to know what our variables means: ``` $radiantEnergy = $surfaceArea * 5.67 * $temperature^4; ``` Common logic tells us that the correct course of action is to increase the surface area, and yes, this will help a bit, but look at that power of 4 on the temperature... that is a nice big exponent to exploit meaning there is a lot of room for exponential growth by just getting a little hotter. The hotter you are, the faster you radiate heat; so, if you want to push a maximum amount of heat off into space, getting hotter is the way to go. Now because people live on your ship, getting hotter everywhere is a bad idea... and totally unnecessary. By separating your ship into capsules that are attached by thermal resistant materials, you can heat each part of your ship to its maximum threshold while keeping living quarters relatively cool. For your habitat section you need to maintain a temperature of about 293K, but that is just what is good for humans to live in. A much larger part of your ship will be the greenhouse, but no-one says you have to live off of vascular plants. By farming Algea as you main food source you can crank this compartment up to 335K... but the next part will make this a trivial measure. Lastly is the reactor section. Now this is where establishing a true MAX has to digress a bit from "hard science" and into "science based" because we really don't know what power sources or materials we will be limited by in the future. However, if you were to construct a large capsule with thermal properties similar to tungsten, you could heat up your rear section to somewhere in the range of 2750K making it glow like a giant incandescent lightbulb... at which point it could passively heat your other 2 sections if you put it at the right distance. So, let's say your ship is made of 3 equal sized capsules, all with a surface area of 1/3 the OP's proposed total surface area, this gives your habitat the ability to compensate for 9.17e10W, your farm section 1.57e11W, and your reactor section 7.12e14W. This is because your glowing hot reactor could offset ~7,750 times as much heat per surface area as a room temperature module. This still only puts you at about 7% of your target... which is honestly not that bad. This still keeps you working in human time scales, but there are two things you can to to further boost this if you really want to hit that 1e16W benchmark. First, there is no reason the modules should be the same size. Your farm will probably need to be much bigger (thus more surface area) than your habitat, and depending on choices you make as an author, your reactor/fuel/propulsion section could have much more surface area than the rest of your ship if you picture a fuel system that stores hydrogen for fusion with no oxygen to react with, you might as well store it as a super heated plasma as long as it does not get hot enough to melt your tungsten containment tanks. In this case, if you make your ship something like 5% habitat, 10% farms, and 85% reactor section, you could get yourself to about 17% of your target goal. Secondly, you can go with higher heat. I chose 2750K as the operating temperature of a lightbulb... much hotter and tungsten become structurally unsound, but adding a meta-material into a space setting that can operate higher than this is not implausible. If you go with a ship that is 85% hot capsule and about 4280K, you should be able to reach 1e16W with that total surface area... but that would significantly exceed the melting point of any known element; so, if you are going for a more hard science universe, I would accept the slightly lower power output. [![hot reactor ship](https://i.stack.imgur.com/5w1NW.png)](https://i.stack.imgur.com/5w1NW.png)
197,867	<p>So, my setting is a small border town on the edge of the [x] empire- beyond the town is the Eastern Reaches and is mostly unexplored. The border has been explored up to around 60 miles by the feudal lord mentioned below- just plains and forests, no iron of any note beyond the small vein close to town or anything of much value.</p> <p>When thinking of the town, think 8 farms of 60-70 acres surrounding a small area with a tavern, cobbler, grain mill, and smithy.</p> <p>Pre-gunpowder medieval tech setting.</p> <p>The planet is earthlike, mid-magic setting. Think mild European climate- very rarely goes above 85*f or into single-digit territory.</p> <p>Town population totals to around 120 people, counting everyone in between the age of 10 and 50 as a working member</p> <p>There is a distant feudal lord that owns the town and the area around it, who gives the townies relative freedom as long as they pay taxes.</p> <p>Population dist. is as follows-</p> <p>10%-ish in a central town</p> <pre><code> 7% skilled labor, 3% unskilled/support labor </code></pre> <p>3% townies as a bandit watch</p> <pre><code> As pointed out below, most likely a single family or smaller. </code></pre> <p>80%-odd farmers- need to look up statistics for avg. laborers per farm</p> <p>7% as a misc. labor workforce</p> <p>Traders come through every few weeks, so that might make up for any missing resource production.</p> <p>Question- is there anything I'm missing that is <strong>essential</strong> or recommended for a small frontier town? If not, is my distribution of peoples realistic?</p> <p>Sorry for any points I didn't address, still inexperienced at making questions.</p>	[ { "answer_id": 197868, "author": "Ash", "author_id": 78800, "author_profile": "https://worldbuilding.stackexchange.com/users/78800", "pm_score": 0, "selected": false, "text": "<p>Consider:</p>\n<ul>\n<li>Brewer / barkeep. Water is typically contaminated with all sorts of nasty things in ...	2021/03/15	[ "https://worldbuilding.stackexchange.com/questions/197867", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/71795/" ]	So, my setting is a small border town on the edge of the [x] empire- beyond the town is the Eastern Reaches and is mostly unexplored. The border has been explored up to around 60 miles by the feudal lord mentioned below- just plains and forests, no iron of any note beyond the small vein close to town or anything of much value. When thinking of the town, think 8 farms of 60-70 acres surrounding a small area with a tavern, cobbler, grain mill, and smithy. Pre-gunpowder medieval tech setting. The planet is earthlike, mid-magic setting. Think mild European climate- very rarely goes above 85\f or into single-digit territory. Town population totals to around 120 people, counting everyone in between the age of 10 and 50 as a working member There is a distant feudal lord that owns the town and the area around it, who gives the townies relative freedom as long as they pay taxes. Population dist. is as follows- 10%-ish in a central town ``` 7% skilled labor, 3% unskilled/support labor ``` 3% townies as a bandit watch ``` As pointed out below, most likely a single family or smaller. ``` 80%-odd farmers- need to look up statistics for avg. laborers per farm 7% as a misc. labor workforce Traders come through every few weeks, so that might make up for any missing resource production. Question- is there anything I'm missing that is essential* or recommended for a small frontier town? If not, is my distribution of peoples realistic? Sorry for any points I didn't address, still inexperienced at making questions.	Honestly, from a medieval fantasy setting for a frontier town, I think you may have diversified your population a little too much. Traditionally, 80-90% of peasants were farmers, and I'd imagine that number climbs above 90% the further outside of a kingdom you get. Here are my thoughts: * There's probably no miners. A village on the outskirts of an empire probably doesn't mine anything because mining is specialty work that requires a lot of hidden infrastructure. You might have a dedicated potter, but if you do he probably collects his own clay in a village that size. * There's probably only one guy and his sons on bandit watch, they probably double as local law enforcement and run a store or a farmstead near the village, since a village of 120 people doesn't have a problem with local bandits, and other bandits are called "raiders" and get everyone in the town organized into a posse in order to fight them. * There's a not insignificant chance that everyone's homes are in a central village and that the farm lands extend into the land around them. A town that size likely works under 1800 acres of land (pulling some numbers from [this post](https://worldbuilding.stackexchange.com/questions/125445/size-of-family-owned-medieval-farm)), which would cover a square less than 2 miles on a side. If your town is in the immediate center, then anyone could expect to reach any plot of land. Even if they aren't communal farmers, they could divide the land into long, thin strips which is also not unheard of in that time period. Edit: see this wikipedia entry on [Ribbon Farms](https://en.wikipedia.org/wiki/Ribbon_farm) * Normally, I'd expect a village to get anything it doesn't produce from travelling merchants, but if they are on the border of the wilderness, you can just expect them to be even more poor than normal as it will be difficult to find people to trade with for even simple necessities like iron. * Edit: PcMan mentioned coal, which made me think firewood. I would expect a forest of around 20 acres to produce 4 cords of firewood from just the dead/fallen trees. That's probably more than enough to support a peasant through the winter. You could probably support the whole village on under 5 square miles of forest then. You might have a dedicated woodcutter then depending on how far from the farmland the woods are (the father the woods, the more likely there's a dedicated woodcutter).
200,192	<p>I'm currently working on developing the navy for the most advanced faction in my fantasy world and I'm stuck with the design of the largest ship, a sort of a medieval carrier ship.</p> <p>I'm talking about having a ship that would be roughly the same size and function as a modern aircraft carrier, with the main difference that it would carry smaller ships (Hunters) instead of aircraft because my fantasy world does not and will never have any sort of flying contraptions.</p> <p>The problem with this idea is to find a way for the Hunters to sail out of and into the carrier while the carrier itself is on the move. The reasoning behind this is that the carrier would be carrying and managing several dozen Hunters, which would have a relatively short range of operation, so the carrier would have to keep up with them at a reasonable pace, especially when the operation demands prolonged harassment of the enemy.</p> <p>As the carrier sails across the water, it creates a serious wake in its path and that very wake is my main design obstacle. Placing the hangar bay doors at the front of the carrier is obviously not an option, while placing them at the sides would force the Hunters to directly cut across the wake when coming in and going out every single time. Placing the hangar bay doors at the rear would force me to place the engines somewhere else and I honestly have no idea how the physics work when a smaller ship is tailgating an exponentially larger one.</p> <p>So far the only concept that somewhat resolves the issue is to apply the idea from the Japanese I-400-class submarines that was attempted during WWII. This would mean providing the carrier with several cranes that would lift the Hunters out of the water while they maintain a parallel course to the carrier and bring them in. Carrying the Hunters in and out one by one seems significantly slower than allowing them to enter and leave the hangar bay relying on their own propulsion, but if there really is no alternative to it then I guess I will have to settle with that.</p> <p>Any suggestions would be greatly appreciated...</p> <p>PS EDIT: Both the carrier and the Hunters have engines powered by reactors (power cells), so they don't require sails.</p> <p>PPS EDIT: The ships would be roughly made of the metals available to us during the pre-ww1 era. Since gunpowder and explosives don't exist, the guns on these ships are the first of their kind, basically oversized airguns.</p>	[ { "answer_id": 200193, "author": "Qami", "author_id": 51300, "author_profile": "https://worldbuilding.stackexchange.com/users/51300", "pm_score": 5, "selected": true, "text": "<p><strong>A giant catamaran.</strong></p>\n<pre><code>A top view:\n _________________________________________...	2021/04/06	[ "https://worldbuilding.stackexchange.com/questions/200192", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/84704/" ]	I'm currently working on developing the navy for the most advanced faction in my fantasy world and I'm stuck with the design of the largest ship, a sort of a medieval carrier ship. I'm talking about having a ship that would be roughly the same size and function as a modern aircraft carrier, with the main difference that it would carry smaller ships (Hunters) instead of aircraft because my fantasy world does not and will never have any sort of flying contraptions. The problem with this idea is to find a way for the Hunters to sail out of and into the carrier while the carrier itself is on the move. The reasoning behind this is that the carrier would be carrying and managing several dozen Hunters, which would have a relatively short range of operation, so the carrier would have to keep up with them at a reasonable pace, especially when the operation demands prolonged harassment of the enemy. As the carrier sails across the water, it creates a serious wake in its path and that very wake is my main design obstacle. Placing the hangar bay doors at the front of the carrier is obviously not an option, while placing them at the sides would force the Hunters to directly cut across the wake when coming in and going out every single time. Placing the hangar bay doors at the rear would force me to place the engines somewhere else and I honestly have no idea how the physics work when a smaller ship is tailgating an exponentially larger one. So far the only concept that somewhat resolves the issue is to apply the idea from the Japanese I-400-class submarines that was attempted during WWII. This would mean providing the carrier with several cranes that would lift the Hunters out of the water while they maintain a parallel course to the carrier and bring them in. Carrying the Hunters in and out one by one seems significantly slower than allowing them to enter and leave the hangar bay relying on their own propulsion, but if there really is no alternative to it then I guess I will have to settle with that. Any suggestions would be greatly appreciated... PS EDIT: Both the carrier and the Hunters have engines powered by reactors (power cells), so they don't require sails. PPS EDIT: The ships would be roughly made of the metals available to us during the pre-ww1 era. Since gunpowder and explosives don't exist, the guns on these ships are the first of their kind, basically oversized airguns.	A giant catamaran. ``` A top view: ____________________________________________________ / \ / Starboard hull \ \| Bow Stern \| \ ____ ____ ____ ____ ____ ____ / \__/ \__/ \__/ \__/ \__/ \__/ \____/ <-Hunter bays along inside of both hulls __ __ __ __ __ __ ____ / \____/ \____/ \____/ \____/ \____/ \____/ \ / \ \| Port hull \| \ / \____________________________________________________/ A side view: Structure connecting the hulls \| V Rope towing hunter through the wake ____________________________________________________ \| \ /====\ /====\ /====\ /====\ /====\ /====\ /`-. V __\|\|______\|\|______\|\|______\|\|______\|\|______\|\|______\|\|____`-. \|\ \| \| `-__\|_\_ <- Arriving hunter ~\ /~~~~~\____/~~~ \____________________________________________________/ ``` The ship has two long hulls, structurally connected above and possibly below the waterline -- above, high enough to clear the masts/highest points of the hunters. If below, deep enough to not interfere with the hunter's keels. The inside-facing sides of the two hulls have the docking bays for the hunters, which can be closed off via sliding doors in heavy weather. A system of pulleys and ropes attached to the structural supports above can assist in launching, catching and docking the hunters. Getting past/through the wake The connecting structure over the two hulls can function as a network of cranes/tracks. It may be unsafe/unfeasible for a hunter to successfully navigate past the wake by itself, but if it's being held by one or more ropes from above, you should be able to keep it steady until it's been let out far enough behind for it to navigate. To pull it back in, the catamaran can toss a floated cable/rope out from between the two hulls. Make the rope as long as it needs to be to drag a safe distance behind the wake. This rope could be caught by a hunter, and then it can be towed forward into the between-hull space where it can be more easily handled and docked.
200,675	<p><strong>Suppose two people want to transmit some binary data (a png image perhaps) by voice.</strong></p> <p>Two of my characters want to share binary data but they can only use their voice and no other form of communication is possible.</p> <p>By "voice", I mean any sounds that can be reliably produced and differentiated by average humans.</p> <p>They can use computers to encode or decode the message but the transfer of information needs to happen between them. For example: They can't use computers to encode the data to sound, play it back and let a computer on the other side record it.</p> <p>They could do it by pronouncing every single zero and one. ("One, Zero, Zero, One, ..") This is very slow and inefficient though.</p> <p>Or they could use <a href="https://en.wikipedia.org/wiki/Hexadecimal" rel="noreferrer">the hex encoding</a>. ("B, Four, F, Nine, ...") This is better, but there is still more room for improvement.</p> <p>Perhaps they could use <a href="https://en.wikipedia.org/wiki/Base64" rel="noreferrer">base64</a> to encode it. ("D, capital G, H, three, ...") But notice how they have to specify capital letters ("capital D"), this lessens it efficiency.</p> <p>What's the most efficient way to do it?</p>	[ { "answer_id": 200677, "author": "o.m.", "author_id": 6402, "author_profile": "https://worldbuilding.stackexchange.com/users/6402", "pm_score": 4, "selected": false, "text": "<p>Efficiency means something that is easy/quick to encode, easy/quick to pronounce and understand, and easy/quic...	2021/04/13	[ "https://worldbuilding.stackexchange.com/questions/200675", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/79076/" ]	Suppose two people want to transmit some binary data (a png image perhaps) by voice. Two of my characters want to share binary data but they can only use their voice and no other form of communication is possible. By "voice", I mean any sounds that can be reliably produced and differentiated by average humans. They can use computers to encode or decode the message but the transfer of information needs to happen between them. For example: They can't use computers to encode the data to sound, play it back and let a computer on the other side record it. They could do it by pronouncing every single zero and one. ("One, Zero, Zero, One, ..") This is very slow and inefficient though. Or they could use [the hex encoding](https://en.wikipedia.org/wiki/Hexadecimal). ("B, Four, F, Nine, ...") This is better, but there is still more room for improvement. Perhaps they could use [base64](https://en.wikipedia.org/wiki/Base64) to encode it. ("D, capital G, H, three, ...") But notice how they have to specify capital letters ("capital D"), this lessens it efficiency. What's the most efficient way to do it?	This problem has been much studied. While it may be difficult to define what 'best' is, there is a very efficient one already in existence, and that's [PGP Words](https://en.wikipedia.org/wiki/PGP_word_list). This method was designed for transmitting long binary keys over a voice link, each word encoding a whole 8 bit byte. It addresses a number of problems you probably haven't thought of, like reliability over a voice link. What happens if a word is missed, or a repetition for clarity is mistaken as an actual repetition or, reading from a long list, two words get swapped? With 8 bits per word, you would normally require 256 words. The system is more sophisticated than that, and uses 512 words, an 'even' table of two syllable words, and an 'odd' table with three syllables, that are used alternately. That way, a missed or repeated word, or two swapped words, can be immediately spotted as an error. Here are the first few and last few, from the wikipedia article linked above. The whole table can be printed on a single sheet of A4. They are in alphabetical order to aid the receiver. Obviously the list is optimised for English. Speakers of other languages may prefer a different list. ``` Hex Even Word Odd Word --- --------- -------- 00 aardvark adroitness 01 absurd adviser 02 accrue aftermath 03 acme aggregate 04 adrift alkali .. ...... ....... FB watchword Wichita FC wayside Wilmington FD willow Wyoming FE woodlark yesteryear FF Zulu Yucatan ``` Quote from the wikipedia article > > The PGP Word List was designed in 1995 by Patrick Juola, a computational linguist, and Philip Zimmermann, creator of PGP. The words were carefully chosen for their phonetic distinctiveness, using genetic algorithms to select lists of words that had optimum separations in phoneme space. The candidate word lists were randomly drawn from Grady Ward's Moby Pronunciator list as raw material for the search, successively refined by the genetic algorithms. The automated search converged to an optimized solution in about 40 hours on a DEC Alpha, a particularly fast machine in that era. > > > An alternative for a 4 bit nybble per word is simply to use the hex alphabet, perhaps using the ICAO/NATO pronunciation, 'zero' to 'niner' then 'alpha' through to 'foxtrot'. There are more than 16 further letters left if needed for even/odd coding. Whether the complexity of the 512 words needed for doubling the throughput with PGP words is warranted against the simplicity of hex begs the question of how you define 'best', what factors in the setup or operation of the communication are important. You could get even higher efficiency by using more bits per word. 12 bits would need a 4096/8192 long dictionary. This would sacrifice much of the hard-won inter-word phonetic distance of the PGP scheme, so would require a higher fidelity voice channel, and more careful speakers. Noting ruakh's comment, it's worth looking at the speed of the channel. His estimate is two seconds per word, which would probably be quite good for untrained users. That's 4 bits/s. If we compare that with Morse code, the minimum speed required by the FCC to grant a radio operator's license used to be 16 five-letter code groups per minute, which very roughly equates to about 8 bits/s. The difference between the two systems is that Morse Code requires training. I couldn't transcribe Morse, at any speed, without a lot of practice, and probably some tuition as well. Many English speakers could transcribe those words without practice, but what about those with a limited vocabulary, or English as a second language, or speakers of other languages? PGP words is not really training-free, if it's to be used by any human at all. It's only ready-to-go if used by people like those who invented it, educated fluent English speakers, being a programmer would help as well. It's probably a skill that's easier to pick up than Morse though. With speed in mind, it might be worth reviewing the performance of hexadecimal via ICAO pronunciation. While a word every two seconds would be good going for recording a PGP word manually, I think hexadecimal could be done at easily twice that rate, transcribing as you go, making the bit rate of the two methods equivalent. Clearly a lot of other assumptions about the training or experience of users, the setup costs, the quality of the audio link, have to be defined before the best system can be determined.
202,296	<p>D&D style dragons come out of the egg knowing languages meaning that they had to learn it somewhere. I'm not interested in that. What I want to know is, that assuming Dragon lullabies are like human lullabies, what would they sing about?</p> <p>To clarify most human lullabies are about getting the baby to quiet down and also the scary parts of the world. There's more articles about it but here's a good example: <a href="https://www.bbc.com/news/magazine-21035103" rel="nofollow noreferrer">https://www.bbc.com/news/magazine-21035103</a></p> <p>There's also a National Geographic article that was good: <a href="https://www.nationalgeographic.com/magazine/article/what-the-lullabies-we-sing-to-our-children-reveal-about-us-feature" rel="nofollow noreferrer">https://www.nationalgeographic.com/magazine/article/what-the-lullabies-we-sing-to-our-children-reveal-about-us-feature</a></p> <p>What would a dragon be scared of, for the babies or the dragons, enough to sing to their eggs while brooding over them? I'm mostly interested in Ice Dragons if you want a specific type of dragon but any dragon in general will do.</p> <p>In my world, sixty or so years ago the air became poisonous, the poison part is just hand waving because nobody knows why other then it is in the story, to sapient creatures, dragons included, other then that it's a vaguely earth centric world up to the 1970s. After that it diverged into most people dying and people, including dragons in disguise, making out living in various manners. The three largest ones are giant walls of stone that happen to block the poison in the air, the mining quarry that mines said stone, and one place that manages to pull the poison out of the air.</p> <p>To clarify, the dragons are D&D style in an earth-like world up until the 1970s after which the timeline changes.</p>	[ { "answer_id": 202343, "author": "Willk", "author_id": 31698, "author_profile": "https://worldbuilding.stackexchange.com/users/31698", "pm_score": 3, "selected": false, "text": "<p><strong>Mathematical progressions.</strong></p>\n<p>Ice dragons are asocial. They do not care about other ...	2021/05/09	[ "https://worldbuilding.stackexchange.com/questions/202296", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/85411/" ]	D&D style dragons come out of the egg knowing languages meaning that they had to learn it somewhere. I'm not interested in that. What I want to know is, that assuming Dragon lullabies are like human lullabies, what would they sing about? To clarify most human lullabies are about getting the baby to quiet down and also the scary parts of the world. There's more articles about it but here's a good example: <https://www.bbc.com/news/magazine-21035103> There's also a National Geographic article that was good: <https://www.nationalgeographic.com/magazine/article/what-the-lullabies-we-sing-to-our-children-reveal-about-us-feature> What would a dragon be scared of, for the babies or the dragons, enough to sing to their eggs while brooding over them? I'm mostly interested in Ice Dragons if you want a specific type of dragon but any dragon in general will do. In my world, sixty or so years ago the air became poisonous, the poison part is just hand waving because nobody knows why other then it is in the story, to sapient creatures, dragons included, other then that it's a vaguely earth centric world up to the 1970s. After that it diverged into most people dying and people, including dragons in disguise, making out living in various manners. The three largest ones are giant walls of stone that happen to block the poison in the air, the mining quarry that mines said stone, and one place that manages to pull the poison out of the air. To clarify, the dragons are D&D style in an earth-like world up until the 1970s after which the timeline changes.	Dragons vary a lot from media-to-media, but they are always the most prideful beings in the world. How could that be different, when they are the apex predator? So, naturally, their songs would be most likely about pride: ``` My Little Dragonkin (sing to the tune of bayu bayushki bayu) There are those with little mouths, that can't scare bear or boar. But rejoice, we're dragonkin, and everyone will fear your roar. There are those with no claws, that can't hunt the little sheep. But rejoice, we're dragonkin, and even giants we make bleed. There are those that have no wings, that can only dream to fly. But rejoice, we're dragonkin, and you too will rule the sky. There are those that shed some tears, 'cause they know no gold nor gem. But rejoice, we're dragonkin, and you will be richer than any men. With your hoard, in your den, Greater than any elven-king. Stand with pride, show your might, 'cause you're my little dragonkin. ``` Additional themes for dragon lullabies will include things that are unique to dragons, and put them apart from the other sentient races - their claws, their ability to fly, their magic, and their overall behavior. To give some examples: * Dragon-magic is on a league of its own. Magic that is specific to dragons and can't be emulated by beings not-related to dragons is specially rare in fiction, and when it appears it is usually for something big, almost miracle-like. Obviously, not all dragons are such exceptional magicians, but the puny humans don't need to know that. So, songs that talk about magic will definitely be a thing. * Pilling up treasure is up there in the Top 3 Hobbies for the Modern Dragon. What exactly that treasure is might change from time to time, but the bottom line is that dragons are collectors of things. Some like shiny things (gold, gems), others like darky things (skulls, bones), others like to collect maids and kids, and so on. With that in mind, it is natural to imagine that dragons will also make songs about collecting all sorts of things and making their hoards big. * Eating. Dragons can eat almost anything, including a lot of things that shouldn't be edible. Dragons don't remove the stupid metal peel of a knight before gulping them up - the poor sod just goes in whole, and the magically-enhanced stomach acid does the rest. So, songs about eating things - be it plants, animals, or other sentient beings will certainly be a thing. I can easily picture songs with themes like a dragon trying to grow big enough to eat very big things - like a tower, a castle, or the moon. * Dragon Anatomy. Dragons are very different from the usual creature - they have six limbs instead of four, they look like reptiles but are built like cats, they have long tails and powerful claws, mighty teeth and a powerful breath weapon. Songs that name those things, sang by the dragon-mom while she boops the respective wyrmling's body parts can easily be part of the repertoire. * Dragon smells. [Apparently a lot of time was wasted by several authors to write about how dragons smell like.](https://rpg.stackexchange.com/a/151881/11162). If you subscribe to the idea that each type of dragon has a specific smell, then memorizing what type of dragon smells like what can help dragons identify each other on the field, specially if they do disguise themselves like humans to keep a low profile.
202,300	<p>This is <a href="https://www.deviantart.com/toonholt/art/World-Map-w-Lost-Continents-834813033" rel="nofollow noreferrer">a map of Earth</a> as depicted by the DeviantArtist ToonHolt:</p> <p><a href="https://i.stack.imgur.com/7eKRa.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/7eKRa.jpg" alt="enter image description here" /></a></p> <p>As you can see, many new landmasses have been added, from lost worlds like Sundaland, Zealandia and Kerguelen, to fictional worlds like Mu, Atlantis and Lemuria. Some of these extra landmasses used to exist, others never did.</p> <p>But in the event that this is a map of Earth in the 21st century CE, it would require a massive point of departure, one in which humanity would be butterflied out of existence. Before we get to the geography and the climate, the first question would be:</p> <p><strong>What point of departure, chronologically and geologically, would be required for this kind of Earth to exist?</strong></p>	[ { "answer_id": 202343, "author": "Willk", "author_id": 31698, "author_profile": "https://worldbuilding.stackexchange.com/users/31698", "pm_score": 3, "selected": false, "text": "<p><strong>Mathematical progressions.</strong></p>\n<p>Ice dragons are asocial. They do not care about other ...	2021/05/09	[ "https://worldbuilding.stackexchange.com/questions/202300", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/10274/" ]	This is [a map of Earth](https://www.deviantart.com/toonholt/art/World-Map-w-Lost-Continents-834813033) as depicted by the DeviantArtist ToonHolt: [![enter image description here](https://i.stack.imgur.com/7eKRa.jpg)](https://i.stack.imgur.com/7eKRa.jpg) As you can see, many new landmasses have been added, from lost worlds like Sundaland, Zealandia and Kerguelen, to fictional worlds like Mu, Atlantis and Lemuria. Some of these extra landmasses used to exist, others never did. But in the event that this is a map of Earth in the 21st century CE, it would require a massive point of departure, one in which humanity would be butterflied out of existence. Before we get to the geography and the climate, the first question would be: What point of departure, chronologically and geologically, would be required for this kind of Earth to exist?	Dragons vary a lot from media-to-media, but they are always the most prideful beings in the world. How could that be different, when they are the apex predator? So, naturally, their songs would be most likely about pride: ``` My Little Dragonkin (sing to the tune of bayu bayushki bayu) There are those with little mouths, that can't scare bear or boar. But rejoice, we're dragonkin, and everyone will fear your roar. There are those with no claws, that can't hunt the little sheep. But rejoice, we're dragonkin, and even giants we make bleed. There are those that have no wings, that can only dream to fly. But rejoice, we're dragonkin, and you too will rule the sky. There are those that shed some tears, 'cause they know no gold nor gem. But rejoice, we're dragonkin, and you will be richer than any men. With your hoard, in your den, Greater than any elven-king. Stand with pride, show your might, 'cause you're my little dragonkin. ``` Additional themes for dragon lullabies will include things that are unique to dragons, and put them apart from the other sentient races - their claws, their ability to fly, their magic, and their overall behavior. To give some examples: * Dragon-magic is on a league of its own. Magic that is specific to dragons and can't be emulated by beings not-related to dragons is specially rare in fiction, and when it appears it is usually for something big, almost miracle-like. Obviously, not all dragons are such exceptional magicians, but the puny humans don't need to know that. So, songs that talk about magic will definitely be a thing. * Pilling up treasure is up there in the Top 3 Hobbies for the Modern Dragon. What exactly that treasure is might change from time to time, but the bottom line is that dragons are collectors of things. Some like shiny things (gold, gems), others like darky things (skulls, bones), others like to collect maids and kids, and so on. With that in mind, it is natural to imagine that dragons will also make songs about collecting all sorts of things and making their hoards big. * Eating. Dragons can eat almost anything, including a lot of things that shouldn't be edible. Dragons don't remove the stupid metal peel of a knight before gulping them up - the poor sod just goes in whole, and the magically-enhanced stomach acid does the rest. So, songs about eating things - be it plants, animals, or other sentient beings will certainly be a thing. I can easily picture songs with themes like a dragon trying to grow big enough to eat very big things - like a tower, a castle, or the moon. * Dragon Anatomy. Dragons are very different from the usual creature - they have six limbs instead of four, they look like reptiles but are built like cats, they have long tails and powerful claws, mighty teeth and a powerful breath weapon. Songs that name those things, sang by the dragon-mom while she boops the respective wyrmling's body parts can easily be part of the repertoire. * Dragon smells. [Apparently a lot of time was wasted by several authors to write about how dragons smell like.](https://rpg.stackexchange.com/a/151881/11162). If you subscribe to the idea that each type of dragon has a specific smell, then memorizing what type of dragon smells like what can help dragons identify each other on the field, specially if they do disguise themselves like humans to keep a low profile.
206,182	<p>Premise: A generation spaceship leaves Earth around the year 2060 on a journey to colonize Alpha Centauri A (ACA). In this fiction, fusion power is achieved in 2040, improved over 20 years, and used within the solar system. The trip to ACA will take 110 years. The ship will accelerate halfway, flip, and decelerate for the second half.</p> <p>I understand basic physics equations involving <span class="math-container">$F (force) = m (mass) * a (acceleration)$</span> and <a href="https://en.wikipedia.org/wiki/Space_travel_using_constant_acceleration" rel="nofollow noreferrer">simplified space travel using constant acceleration</a> giving <span class="math-container">$d=(1/2)at^2$</span>, with distance (d) in meters, acceleration (a) in meters per second squared, and time (t) in seconds.</p> <p><strong>However, this distance traveled does not account for mass loss of Xenon fuel used for propulsion. How do I set up an equation to get (at least a rough estimate of) the Newtons of thrust and kg of Xenon needed for the journey to take 110 years?</strong></p> <p>Given:</p> <ul> <li>The ship leaves in 2060: about 40 years more advanced than our current 2021 tech levels.</li> <li>The journey takes 110 years (as relatively perceived by those on board the ship).</li> <li>Ship launch mass of 1,900,000 kg.</li> <li>Each ion drive provides 30 N thrust, averaging 15 kW used per N, fuel use 75 kg of Xenon per 4,000 seconds of burn. (based on advanced versions of current drives)</li> <li>Light years to ACA: 4.37.</li> </ul> <p><strong>Edit: thanks to answers and comments : Originally, I thought they would flip the ship to decel halfway, but the ship will want to continue to burn at the same max safe thrust, and so burn near constant fuel during the entire trip. So, the latter half of the trip will see increasingly larger accel, due to decreasing mass but constant thrust Newtons. This changing mass makes the calculation more complex, because they will not simply flip at halfway point... as the decel part will be shorter due to lower mass. I am currently <a href="https://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation" rel="nofollow noreferrer">researching rocket equations</a> which account for fuel mass losses but dont have it figured out yet...</strong></p> <p>Journey with simplified acceleration if time is 110 years: <span class="math-container">$a = d/0.5t^2 = (2.06717e16) / (0.5 * (3.469e9)^2) = 0.00343556041 m/s^2 = a$</span>.</p> <p>If the ship is 1,900,000 kg at launch from Earth, and <span class="math-container">$F=ma$</span>, <span class="math-container">$1900000a = 6527$</span> N (Newtons of thrust). However this is simplified. N thrust will change as fuel mass is lost... My thinking is that the ship will want to continue to burn at the same max safe thrust, and so burn near constant fuel during the entire trip. So the latter half of the trip will see increasingly larger accel, due to decreasing mass but constant thrust.</p> <p>6527N can be provided by 218 individual 30N drives (around this number may be good even as mass lessens, for redundancy safety). Based on above givens, this requires 861,110 kg Xe fuel. Ship mass would continually decrease as Xe used, until the ship is empty of fuel and about 1,040,000 kg mass remains, requiring less force to move.</p> <p>I'm not sure how to estimate how much N of thrust and mass of Xe fuel will be needed for this journey. I am imagining two functions, with the force function relying on the lost Xe mass (which is a constant loss over time), but I am unsure how to set that up so that everything results in a 110 year journey. Should I integrate to get areas underneath both functions, then adjust until I get roughly 110 years? Ideally I'd like equations where I can easily adjust the ship mass, thrust Newtons, and so on to calculate with different variables if needed.</p> <p>Regarding initial velocity: Ideally for the story, the ship would leave from Mars orbit: <a href="https://physics.info/motion-equations/" rel="nofollow noreferrer">Linear distance can be expressed as (if acceleration is constant)</a>: <span class="math-container">$s = v_0 t + 0.5a t^2$</span>. With <span class="math-container">$v_0 =$</span> initial linear velocity (m/s) = <a href="https://nssdc.gsfc.nasa.gov/planetary/factsheet/marsfact.html" rel="nofollow noreferrer">Mars mean orbital velocity</a> in (m/s) = <span class="math-container">$24070$</span></p> <p>Regarding relative movement of both the Solar System and Alpha Centauri, I <a href="https://en.wikipedia.org/wiki/Alpha_Centauri#Kinematics" rel="nofollow noreferrer">found</a>:</p> <blockquote> <p>Using spectroscopy the mean radial velocity has been determined to be around 22.4 km/s towards the Solar System. This gives a speed with respect to the sun of 32.4 km/s, very close to the peak in the distribution of speeds of nearby stars.</p> </blockquote> <p>But without knowing ship's max v, because the ship-flipping point is unknown to me, I'm not sure how much 22.4 kps will affect the journey.</p> <p>Info and chart below from <a href="https://en.wikipedia.org/wiki/Ion_thruster#Comparisons" rel="nofollow noreferrer">https://en.wikipedia.org/wiki/Ion_thruster#Comparisons</a></p> <blockquote> <p>Ion thrusters in operational use typically consume 1–7 kW of power, have exhaust velocities around 20–50 km/s (Isp 2000–5000 s), and possess thrusts of 25–250 mN and a propulsive efficiency 65–80%.[3][4] though experimental versions have achieved 100 kW (130 hp), 5 N (1.1 lbf).[5]</p> </blockquote> <div class="s-table-container"> <table class="s-table"> <thead> <tr> <th style="text-align: right;">Thruster</th> <th style="text-align: left;">Propellant</th> <th style="text-align: left;">Input power (kW)</th> <th style="text-align: left;">Specific impulse (s)</th> <th style="text-align: left;">Thrust (N)</th> <th style="text-align: left;">Thruster mass (kg)</th> </tr> </thead> <tbody> <tr> <td style="text-align: right;">X3</td> <td style="text-align: left;">Xenon</td> <td style="text-align: left;">max 102 kW</td> <td style="text-align: left;">1800–2650</td> <td style="text-align: left;">5.2</td> <td style="text-align: left;">230</td> </tr> <tr> <td style="text-align: right;">AEPS</td> <td style="text-align: left;">Xenon</td> <td style="text-align: left;">13.3</td> <td style="text-align: left;">2900</td> <td style="text-align: left;">.6</td> <td style="text-align: left;">100</td> </tr> <tr> <td style="text-align: right;">BHT8000</td> <td style="text-align: left;">Xenon</td> <td style="text-align: left;">8</td> <td style="text-align: left;">2210</td> <td style="text-align: left;">.449</td> <td style="text-align: left;">25</td> </tr> <tr> <td style="text-align: right;">NEXT</td> <td style="text-align: left;">Xenon</td> <td style="text-align: left;">6.9</td> <td style="text-align: left;">4190</td> <td style="text-align: left;">.236 max.</td> <td style="text-align: left;"></td> </tr> <tr> <td style="text-align: right;">NSTAR</td> <td style="text-align: left;">Xenon</td> <td style="text-align: left;">2.3</td> <td style="text-align: left;">3300–1700</td> <td style="text-align: left;">.092 max.</td> <td style="text-align: left;"></td> </tr> <tr> <td style="text-align: right;">PPS-1350 Hall effect</td> <td style="text-align: left;">Xenon</td> <td style="text-align: left;">1.5</td> <td style="text-align: left;">1660</td> <td style="text-align: left;">.090</td> <td style="text-align: left;">5.3</td> </tr> </tbody> </table> </div> <blockquote> <p><a href="https://solarsystem.nasa.gov/missions/dawn/technology/spacecraft/" rel="nofollow noreferrer">https://solarsystem.nasa.gov/missions/dawn/technology/spacecraft/</a> Dawn Ion Propulsion System Number of thrusters: 3 Thruster dimensions (each): 13 inches (33 centimeters) long, 16 inches (41 centimeters) in diameter Weight: 20 pounds (8.9 kilograms) each Spacecraft acceleration via ion propulsion at full thrust: 0 – 60 mph in 4 days Thrust: 0.07 to 0.33 ounce (19 to 91 millinewtons)</p> </blockquote> <blockquote> <p>Fuel <a href="https://en.wikipedia.org/wiki/Ion_thruster#Propellants" rel="nofollow noreferrer">https://en.wikipedia.org/wiki/Ion_thruster#Propellants</a> Many current designs use xenon gas, as it is easy to ionize, has a reasonably high atomic number, is inert and causes low erosion. However, xenon is globally in short supply and expensive. VASIMR design (and other plasma-based engines) are theoretically able to use practically any material for propellant. However, in current tests the most practical propellant is argon, which is relatively abundant and inexpensive.</p> </blockquote> <blockquote> <p><a href="https://en.wikipedia.org/wiki/Variable_Specific_Impulse_Magnetoplasma_Rocket" rel="nofollow noreferrer">https://en.wikipedia.org/wiki/Variable_Specific_Impulse_Magnetoplasma_Rocket</a> [Higher energy use ok because of fusion power.] Other propellants, such as bismuth and iodine, show promise, particularly for gridless designs such as Hall effect thrusters. Krypton is used to fuel the Hall effect thrusters aboard Starlink internet satellites, in part due to its lower cost than conventional xenon propellant. FUEL USE: The Deep Space 1 spacecraft, powered by an ion thruster, changed velocity by 4.3 km/s (2.7 mi/s) while consuming less than 74 kg (163 lb) of xenon. [=4300 m/s for 75kg Xe?] The Dawn spacecraft broke the record, with a velocity change of 11.5 km/s (41,000 km/h), though it was only half as efficient, requiring 425 kg (937 lb) of xenon.</p> </blockquote> <p><a href="https://www.space.com/38444-mars-thruster-design-breaks-records.html" rel="nofollow noreferrer">https://www.space.com/38444-mars-thruster-design-breaks-records.html</a> <a href="https://www.popularmechanics.com/space/moon-mars/news/a28754/new-ion-thruster-breaks-records-power-thrust/" rel="nofollow noreferrer">https://www.popularmechanics.com/space/moon-mars/news/a28754/new-ion-thruster-breaks-records-power-thrust/</a> <a href="https://www.space.com/28732-nasa-dawn-spacecraft-ion-propulsion.html" rel="nofollow noreferrer">https://www.space.com/28732-nasa-dawn-spacecraft-ion-propulsion.html</a> <a href="https://www.nasa.gov/centers/glenn/technology/Ion_Propulsion1.html" rel="nofollow noreferrer">https://www.nasa.gov/centers/glenn/technology/Ion_Propulsion1.html</a> <a href="https://www.nasa.gov/multimedia/imagegallery/image_feature_2416.html" rel="nofollow noreferrer">https://www.nasa.gov/multimedia/imagegallery/image_feature_2416.html</a> <a href="https://space.stackexchange.com/questions/840/how-fast-will-1g-get-you-there">https://space.stackexchange.com/questions/840/how-fast-will-1g-get-you-there</a> <a href="http://www.projectrho.com/public_html/rocket/slowerlight2.php" rel="nofollow noreferrer">http://www.projectrho.com/public_html/rocket/slowerlight2.php</a> <a href="http://www.xenology.info/Xeno/17.3.htm" rel="nofollow noreferrer">http://www.xenology.info/Xeno/17.3.htm</a> Conventional Interstellar Propulsion Systems <a href="https://forum.nasaspaceflight.com/index.php?topic=34036.1060" rel="nofollow noreferrer">https://forum.nasaspaceflight.com/index.php?topic=34036.1060</a> <a href="https://www.omnicalculator.com/physics" rel="nofollow noreferrer">https://www.omnicalculator.com/physics</a> "The Martian" Hermes ship design <a href="https://the-martian.fandom.com/wiki/Hermes_Spacecraft" rel="nofollow noreferrer">https://the-martian.fandom.com/wiki/Hermes_Spacecraft</a> <a href="https://www.nasa.gov/directorates/spacetech/niac/index.html" rel="nofollow noreferrer">https://www.nasa.gov/directorates/spacetech/niac/index.html</a></p>	[ { "answer_id": 206183, "author": "Willk", "author_id": 31698, "author_profile": "https://worldbuilding.stackexchange.com/users/31698", "pm_score": 1, "selected": false, "text": "<p><strong>Halfway point mass is average of start and finish.</strong></p>\n<p>You state that you lose xenon m...	2021/06/26	[ "https://worldbuilding.stackexchange.com/questions/206182", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/83216/" ]	Premise: A generation spaceship leaves Earth around the year 2060 on a journey to colonize Alpha Centauri A (ACA). In this fiction, fusion power is achieved in 2040, improved over 20 years, and used within the solar system. The trip to ACA will take 110 years. The ship will accelerate halfway, flip, and decelerate for the second half. I understand basic physics equations involving $F (force) = m (mass) \* a (acceleration)$ and [simplified space travel using constant acceleration](https://en.wikipedia.org/wiki/Space_travel_using_constant_acceleration) giving $d=(1/2)at^2$, with distance (d) in meters, acceleration (a) in meters per second squared, and time (t) in seconds. However, this distance traveled does not account for mass loss of Xenon fuel used for propulsion. How do I set up an equation to get (at least a rough estimate of) the Newtons of thrust and kg of Xenon needed for the journey to take 110 years? Given: * The ship leaves in 2060: about 40 years more advanced than our current 2021 tech levels. * The journey takes 110 years (as relatively perceived by those on board the ship). * Ship launch mass of 1,900,000 kg. * Each ion drive provides 30 N thrust, averaging 15 kW used per N, fuel use 75 kg of Xenon per 4,000 seconds of burn. (based on advanced versions of current drives) * Light years to ACA: 4.37. Edit: thanks to answers and comments : Originally, I thought they would flip the ship to decel halfway, but the ship will want to continue to burn at the same max safe thrust, and so burn near constant fuel during the entire trip. So, the latter half of the trip will see increasingly larger accel, due to decreasing mass but constant thrust Newtons. This changing mass makes the calculation more complex, because they will not simply flip at halfway point... as the decel part will be shorter due to lower mass. I am currently [researching rocket equations](https://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation) which account for fuel mass losses but dont have it figured out yet... Journey with simplified acceleration if time is 110 years: $a = d/0.5t^2 = (2.06717e16) / (0.5 \* (3.469e9)^2) = 0.00343556041 m/s^2 = a$. If the ship is 1,900,000 kg at launch from Earth, and $F=ma$, $1900000\a = 6527$ N (Newtons of thrust). However this is simplified. N thrust will change as fuel mass is lost... My thinking is that the ship will want to continue to burn at the same max safe thrust, and so burn near constant fuel during the entire trip. So the latter half of the trip will see increasingly larger accel, due to decreasing mass but constant thrust. 6527N can be provided by 218 individual 30N drives (around this number may be good even as mass lessens, for redundancy safety). Based on above givens, this requires 861,110 kg Xe fuel. Ship mass would continually decrease as Xe used, until the ship is empty of fuel and about 1,040,000 kg mass remains, requiring less force to move. I'm not sure how to estimate how much N of thrust and mass of Xe fuel will be needed for this journey. I am imagining two functions, with the force function relying on the lost Xe mass (which is a constant loss over time), but I am unsure how to set that up so that everything results in a 110 year journey. Should I integrate to get areas underneath both functions, then adjust until I get roughly 110 years? Ideally I'd like equations where I can easily adjust the ship mass, thrust Newtons, and so on to calculate with different variables if needed. Regarding initial velocity: Ideally for the story, the ship would leave from Mars orbit: [Linear distance can be expressed as (if acceleration is constant)](https://physics.info/motion-equations/): $s = v\_0 \ t + 0.5a t^2$. With $v\_0 =$ initial linear velocity (m/s) = [Mars mean orbital velocity](https://nssdc.gsfc.nasa.gov/planetary/factsheet/marsfact.html) in (m/s) = $24070$ Regarding relative movement of both the Solar System and Alpha Centauri, I [found](https://en.wikipedia.org/wiki/Alpha_Centauri#Kinematics): > > Using spectroscopy the mean radial velocity has been determined to be > around 22.4 km/s towards the Solar System. This gives a speed with > respect to the sun of 32.4 km/s, very close to the peak in the > distribution of speeds of nearby stars. > > > But without knowing ship's max v, because the ship-flipping point is unknown to me, I'm not sure how much 22.4 kps will affect the journey. Info and chart below from <https://en.wikipedia.org/wiki/Ion_thruster#Comparisons> > > Ion thrusters in operational use typically consume 1–7 kW of power, > have exhaust velocities around 20–50 km/s (Isp 2000–5000 s), and > possess thrusts of 25–250 mN and a propulsive efficiency 65–80%.[3][4] > though experimental versions have achieved 100 kW (130 hp), 5 N (1.1 > lbf).[5] > > > \| Thruster \| Propellant \| Input power (kW) \| Specific impulse (s) \| Thrust (N) \| Thruster mass (kg) \| \| --- \| --- \| --- \| --- \| --- \| --- \| \| X3 \| Xenon \| max 102 kW \| 1800–2650 \| 5.2 \| 230 \| \| AEPS \| Xenon \| 13.3 \| 2900 \| .6 \| 100 \| \| BHT8000 \| Xenon \| 8 \| 2210 \| .449 \| 25 \| \| NEXT \| Xenon \| 6.9 \| 4190 \| .236 max. \| \| \| NSTAR \| Xenon \| 2.3 \| 3300–1700 \| .092 max. \| \| \| PPS-1350 Hall effect \| Xenon \| 1.5 \| 1660 \| .090 \| 5.3 \| > > <https://solarsystem.nasa.gov/missions/dawn/technology/spacecraft/> > Dawn Ion Propulsion System Number of thrusters: 3 Thruster dimensions > (each): 13 inches (33 centimeters) long, 16 inches (41 centimeters) in > diameter Weight: 20 pounds (8.9 kilograms) each Spacecraft > acceleration via ion propulsion at full thrust: 0 – 60 mph in 4 days > Thrust: 0.07 to 0.33 ounce (19 to 91 millinewtons) > > > > > Fuel <https://en.wikipedia.org/wiki/Ion_thruster#Propellants> > Many current designs use xenon gas, as it is easy to ionize, has a > reasonably high atomic number, is inert and causes low erosion. > However, xenon is globally in short supply and expensive. VASIMR > design (and other plasma-based engines) are theoretically able to use > practically any material for propellant. However, in current tests the > most practical propellant is argon, which is relatively abundant and > inexpensive. > > > > > <https://en.wikipedia.org/wiki/Variable_Specific_Impulse_Magnetoplasma_Rocket> [Higher energy use ok because of fusion power.] > Other propellants, such as bismuth and iodine, show promise, > particularly for gridless designs such as Hall effect thrusters. > Krypton is used to fuel the Hall effect thrusters aboard Starlink > internet satellites, in part due to its lower cost than conventional > xenon propellant. FUEL USE: The Deep Space 1 spacecraft, powered by an > ion thruster, changed velocity by 4.3 km/s (2.7 mi/s) while consuming > less than 74 kg (163 lb) of xenon. [=4300 m/s for 75kg Xe?] The Dawn > spacecraft broke the record, with a velocity change of 11.5 km/s > (41,000 km/h), though it was only half as efficient, requiring 425 kg > (937 lb) of xenon. > > > <https://www.space.com/38444-mars-thruster-design-breaks-records.html> <https://www.popularmechanics.com/space/moon-mars/news/a28754/new-ion-thruster-breaks-records-power-thrust/> <https://www.space.com/28732-nasa-dawn-spacecraft-ion-propulsion.html> <https://www.nasa.gov/centers/glenn/technology/Ion_Propulsion1.html> <https://www.nasa.gov/multimedia/imagegallery/image_feature_2416.html> <https://space.stackexchange.com/questions/840/how-fast-will-1g-get-you-there> <http://www.projectrho.com/public_html/rocket/slowerlight2.php> <http://www.xenology.info/Xeno/17.3.htm> Conventional Interstellar Propulsion Systems <https://forum.nasaspaceflight.com/index.php?topic=34036.1060> <https://www.omnicalculator.com/physics> "The Martian" Hermes ship design <https://the-martian.fandom.com/wiki/Hermes_Spacecraft> <https://www.nasa.gov/directorates/spacetech/niac/index.html>	Since you mention integrals, I know you are familiar with calculus, so I can give you the short and sweet answer. It is not always true that $F=ma$. The more complete version of Newton's equations yields $F=\frac{dp}{dt}$, where $p$ is momentum. Force is the change in momentum over time. Now, since $p=mv$, we can quickly see that if mass is constant, we get $F=m\frac{dv}{dt}$ which is $F=ma$. If mass is not constant, then you have to use the chain rule to get $F=\frac{dm}{dt}v+m\frac{dv}{dt}$, which is what is used in rocketry. Integrate that, and you get the answer you need. You aren't the first to want to do this. the [Tsiolkovsky rocket equation](https://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation) is the go-to equation for doing these calculations $$\Delta V= I\_{sp}g\_0\ln\frac{m\_0}{m\_f}$$ Why go here first, rather than integrating? Well we don't have our ship spec'd out yet. We need to understand our mass fraction before daring to integrate to get distance. But what we know is that we have to do two burns. The first burn takes us from an initial velocity (call it 0) to $v\_{\frac{1}{2}}$, the velocity at the flip point (which, as you note, isn't quite at the half way point in distance, but I'm using the subscript $\frac{1}{2}$ anyways). Then, the second burn takes us down to the velocity of ACA with respect the earth.. Once you have this, you just have to use the above complete version of Newton's law to do the integration. I'm going to give us control of "number of engines" as a variable. Now, I don't recommend actually just stacking more and more little engines. It's not always the most efficient approach. But a multiplier on the existing ion engine you described seems like a pretty good way to go! We'll call this scale factor $k$. If your ship has a scale factor of $k$, it means it produces $30k$ Newtons of thrust, and consumes $\frac{75}{4000}k\frac{kg}{s}$ worth of Xenon while active. We're also going to need the ISP. Now it looks like you mixed the numbers from several ion thrusters, and got one which is actually quite weak. Others can check my math, but I pegged it at an ISP of about 160 seconds, which is extremely low (its lower than a chemical rocket). Typically the ISP is in the thousands for an ion thruster. So let's just leave it as a variable, $I\_{sp}$, but I'll peg it to the really nice ISP of NEXT, at 4190s. Feel free to adjust from there, but that's really the dominating variable in these thrusters. You can adjust size and flow rate as much as you like, but changing ISP is incredibly difficult. You should also pick a $m\_f$. Your question listed a $m\_0$, but $m\_f$ is typically easier to work with because its bounded by the need to do something with a payload. For example, it might be all of the life support needed to support 10,000 people, or something like that. It will just be a scale factor on everything, so I won't include it... but you'll need it to turn into the question of "how hard is it to actually make this rocket." For now, I'll just assume a $m\_f$ of 1,000,000kg. We can do everything in velocities in the initial frame, so $v\_0=0$ and $v\_f$ is the velocity of ACA in our frame, [which is roughly](https://en.wikipedia.org/wiki/Alpha_Centauri)y 21.4km/s towards us, so we'll say $v\_f=-21.4km/s$ to make all of the signs line up Now, we know that our total burn is the sum of the speeding up burn plus the slowing down burn. $\Delta V=v\_\frac1 2 + (v\_\frac 1 2 - v\_f) = 2 v\frac 1 2 - v\_f$. By the rocket equation, we can now see that we can relate this to the propellant mass that we use. $$\Delta V=v\_e\ln\frac{m\_f}{m\_0}=v\_e\ln\frac{m\_f}{m\_f+m\_p}$$ $$2 v\_\frac 1 2 - v\_f = v\_e\ln\frac{m\_f}{m\_f + m\_p}$$ Here I've broken out the initial mass into a final mass plus the mass of the propellant, $m\_p$. This is convenient because we can calculate the propellant mass from the data you've given. If $k=1$, then we know that we consume $\frac{75}{4000}\frac{kg}{s}\cdot T$ fuel, where $T$ is the duration of the flight, 110 years. A quick unit conversion and a multiplication by k to $591300kT\frac{kg}{year}$ points out that this is going to be quite the high mass fraction. At 110 years, you will consume just over $65,000,000k$ kilograms of fuel. Thus for * $k=1$, $m\_p=65,000,000kg$, ($\zeta=0.984$) * $k=5$, $m\_p=325,000,000kg$ ($\zeta=0.9969$) * $k=10$, $m\_p=650,000,000kg$ ($\zeta=0.9984$) I note the mass fraction, $\zeta$ because it is a common way to measure rockets. Typical mass fractions are in the 0.8 to 0.9 range, with 0.9 being typical for the single-stage-to-orbit (SSTO). Note that one of the great challenges of SSTO is that its hard to achieve a mass fraction that high. So, when you talk about using current technology, recognize that this is quite far outside of what we're typically working with. You will be bringing a lot of fuel! Regardless, we can combine these equations to get one overarching solution: $$2 v\_\frac 1 2 - v\_f = v\_e\ln\frac{m\_f}{m\_f + \dot m\_1kT}$$ Where $\dot m\_1$ is the above mass flow rate of a $k=1$ engine. Or, rearranged slightly, $$v\_\frac 1 2 = \frac{v\_f + v\_e\ln\frac{m\_f}{m\_f + \dot m\_1kT}}{2}$$ Now this is really neat. It says that if you want to visit ACA, not just fly past it at painfully fast speeds, there's only so many ways you can do it. It says that, for any fuel flow rate ($k$), there is exactly one $v\_\frac 1 2$ that leaves you at exactly the correct velocity you need, $v\_f$. Any other 110 year long burn will leave you at the wrong velocity. This means we're really close to having an answer. We can build a plot with $k$ as our independent term, and the distance traveled, $d$ as our dependent term. All we have to do is calcualte the result of a constant-force 2 stage burn, where we burn out the first stage at the point where $v=v\_\frac 1 2$, and then we burn in the opposite direction. At this point, we could solve a bunch of integrals, but I'll leave this as an exercise for the reader. In the spirit of astrophysics, I invoke "shut up and calculate" and throw everything into a really cheesy python simulation. I just do Riemann integration at 1/10th year intervals, and trust that's fine grained enough to cover for the laughably inexact way I handle updating all of the anti-derivatives. ``` from math import log ln = log # Python's log(x) is actually the natural log. Aliasing it # for readability. mf = 1000000 # kg - my own assumption m1 = 75/4000 # kg/s vf = -21400 # m/s isp = 4160 # s T = 110 * 31556952 # s - trip length f = 30 # N - force of the reference engine g0 = 9.8 # m/s^2 - gravitiy on earth def calcDist(k): """Returns distance traveled in light years""" # step 1: for given k, calculate the ship's stats mdot = m1 * k mp = mdot * T # step 2: compute v 1/2 v05 = 0.5 * (vf - isp * g0 * ln(mf / (mf + mdot * T))) # step 3: Integrate! dt = 0.1 * 31556952 # arbitrary decision, dt is 1/10th of a year m = mf + mp # kg v = 0 # m/s d = 0 # meters t = 0 # step 3a: Burn 1 (accel) # stop at v1/2 while v < v05: a = (f * k - mdot * v) / m # rearrange force equation d += v * dt v += a * dt m -= mdot * dt t += dt # step 3b: Burn 2 (decel) # stop when out of fuel while m > mf: a = (f * k - mdot * v) / m d += v * dt v -= a * dt # note minus sign: slowing down m -= mdot * dt t += dt return d / 9460730472580800 # meters to light years k = np.linspace(100, 1000, 100) d = [calcDist(x) for x in k] plt.plot(k, d, '-k') plt.axhline(4.37, linestyle="dashed") # distance to ACA for kk, dd in zip(k, d): if dd > 4.37: plt.axvline(kk, linestyle="dotted") plt.text(kk + 50, dd - 0.1, "k=%d" % kk) break plt.xlabel("Multiple of reference engine") plt.ylabel("Light years") plt.show() ``` [![Resulting Graph](https://i.stack.imgur.com/djDwR.png)](https://i.stack.imgur.com/djDwR.png) So you will need the equivalent of 381 of those 30N ion thrusters to do the job, and 24800 kg of Xe fuel for every 1 kg of payload. (for a mass fraction of $\zeta=0.9999596$) This is consistent with the back of the envelope calculations you did. You calculated 218 to get there without slowing down. Slowing down requires 4x more thrust, so would require just under 900 engines if we didn't account for the decreasing mass. The actual answer is somewhere between the two. Note, you will have to be mighty creative to achieve that mass fraction. Your fuel tanks are going to have to be very thin, and very large, and yet still survive the 110 year journey!
209,223	<p>Toe-Ticklers are unique beings. They are around human-sized, and overall resemble tetrapods, with 2 key differences: They have 2 pairs of forelegs in sequence, each of which have a mass of dexterous tentacles in place of a manus. They are terrestrial pack hunters, with a social structure like wolves. Their most notable feature is that when they encounter a young human girl, they will often try to capture and tickle her, usually on the feet, before releasing her (usually)</p> <p>What is a plausible biological reason for this behaviour?</p>	[ { "answer_id": 209224, "author": "The Square-Cube Law", "author_id": 21222, "author_profile": "https://worldbuilding.stackexchange.com/users/21222", "pm_score": 1, "selected": false, "text": "<p>I have a dog. Whenever I am lying down on the couch or my bed, she will sit on me. She will o...	2021/08/02	[ "https://worldbuilding.stackexchange.com/questions/209223", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/75161/" ]	Toe-Ticklers are unique beings. They are around human-sized, and overall resemble tetrapods, with 2 key differences: They have 2 pairs of forelegs in sequence, each of which have a mass of dexterous tentacles in place of a manus. They are terrestrial pack hunters, with a social structure like wolves. Their most notable feature is that when they encounter a young human girl, they will often try to capture and tickle her, usually on the feet, before releasing her (usually) What is a plausible biological reason for this behaviour?	``` static The following radio broadcast is brought to you by NASAdent ingestible toothpaste. Win the day with a winning smile! News today from the world of science! Experts from around the world have gathered in Geneva, Switzerland, to discuss the growing phenomena known as TOE-TICKLERS. These large but seemingly harmless creatures have created an increasing panic as young women around the world are being abducted to apparently have their toes tickled. Religious leaders last week denounced the TOE-TICKLERS as proof that sexual relations out of wedlock will bring eternal punishment. Leading scientists aren't sure the goal of the creatures is that philosophical... ``` Ach-tung! Eet is vit the greatest pleasure, yah!, that I am today to report on da findings of the Analyse des Zehenkitzelverhaltens und der Damit Verbundenen Physiologie, yah! dah leetle toesy-ticklin' creetures like da giant feather dusters dat like da leetle girls, yah! and [im Sinne dieser Meta-Site-Frage](https://worldbuilding.meta.stackexchange.com/q/8398/40609), I announce the following data. Is exciting, yah? We conclude tha fallowing: 1. Drs. Jenkins, Volkov, Abdullahi, et al. (2020) suggested based on the tendency of the Toe-Tickler's muscles to shiver while tickling the toes of young women that the combination of toe jam with female enzymes is hallucinogenic. Apparently, tickling a girl compared to a fully-grown woman is a more intense rush. Gloria Steinhem has called a press release later this evening to elaborate on this report. 2. Caribbean housewife Alvita Reid (2021) suggested based on the tendency of the Toe-Ticklers to, well, tickle, is that they *lack the capacity for [Gargalesis](http://www.bbc.com/earth/story/20170518-why-humans-chimpanzees-and-rats-enjoy-being-tickled),* the natural tickle response leading to laughter that many mammals enjoy to one degree or another — and therefore can only experience it vicariously. Further, she's sure that their hearing must center on higher frequencies than humans, which is why they prefer the laughter of females. She's been quoted by our undercover reporter at Jamaica's famous Geejam Bushbar that she's entirely disappointed Toe-Ticklers haven't yet been found in Jamaica. 3. Dr. Emmett Brown (1985) suggested that the Toe-Ticklers appear to have no means of vocal expression. He concludes that, since the feet alone are responsible for over [400,000 nerve endings](https://www.feelyourfeet.com/engage/nerve-endings-in-your-feet/), what they must be doing is trying to communicate. He substantiates his claim by pointing out that the creatures only attempt to communicate with girls, who are known world-over to chat incessantly and are therefore the most obvious candidates for successful communication. However, in a brilliant Master's Thesis, Breathnach (2018) points out that this is unlikely because the Toe-Ticklers never take the girls' phones. 4. Dr. Sakura Chiba (2021) carefully monitored the condition of a girl while being tickled by a Toe Tickler and discovered that the increased dopamine from tickling was osmotically absorbed by the Toe Tickler as a form of bonding** and concluded that the Toe Ticklers, which are apparently all male and otherwise asexual in nature, are simply trying to get a date. 5. A classified CIA report leaked through Wikileaks reveals that an analysis of Toe Tickler behavior suggests they're trying to extort information from their victims. The CIA is now investigating the possibility that toe tickling may be a heckuva lot more efficient than waterboarding. The report further indicates that it's to remain highly classified due to the embarrasment of admitting that the agency has been materially wrong all these years. 6. Dr. Nefario (2010) claims to have definitively proven that effective toe tickling is a great way to exhaust people. He further claims to have proof that the victims who are not returned are those who fell asleep from the exhaustion. He claims to have developed a Blurp Gun that he guarantees will awaken any victim. He finally claims that the lack of ransom demands from the Toe Ticklers in no way exonerates their obvious efforts to capitalize on their natural abilities. 7. Six year old Sigríður Magnúsdóttir has suggested that Toe Ticklers aren't really real and are really a story told by her pabbi to get her to brush her teeth. According to her pabbi, the Toe Ticklers ([like cats](https://catbehaviorassociates.com/cat-myth-cats-steal-the-breath-from-babies/)) feed off the oxygen-rich exhalations associated with laughter. Local reporters doubt Sigríður's story because her pabbi says she likes the taste of... ``` Thank you for joining us today for news from the world of science... and don't forget to brush with NASAdent! Used twice a day to reduce tooth decay, non-foaming and completely ingestible NASAdent will bring a smile to your face! static ```
209,444	<p>while I was working on the language I was thinking about the planet and I don't have the mathematical data, I have a fairly done map but not the data and it would be interesting to add it. As data I only made the mass, it is <span class="math-container">$4,185×10^{24} kg$</span>.</p>	[ { "answer_id": 209446, "author": "L.Dutch", "author_id": 30492, "author_profile": "https://worldbuilding.stackexchange.com/users/30492", "pm_score": 2, "selected": false, "text": "<p>To calculate the density <span class=\"math-container\">$\\rho$</span> or the volume <span class=\"math-c...	2021/08/06	[ "https://worldbuilding.stackexchange.com/questions/209444", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/88321/" ]	while I was working on the language I was thinking about the planet and I don't have the mathematical data, I have a fairly done map but not the data and it would be interesting to add it. As data I only made the mass, it is $4,185×10^{24} kg$.	Alogrithm outline ----------------- So like L. Dutch said, if you assume the volume or average density of the planet you can do this. But the volume and average density aren't first principles values-- they themselves depend on the material and composition in a way that I'll describe shortly. As a word of warning-- I'm going to assume you understand calculus for this-- if you don't, L. Dutch's answer is about as good as you can do. So, the fundamental difficulty of this problem is that to know the mass of the planet, you need to know the density distribution. The other answer assumes that it's constant, but this isn't a well founded assumption-- the inside of the planet has a lot more pressure squeezing down on it, which leads to higher densities. So how do we deal with this difficulty? Why, with differential equations of course! Barring any funny business like a quickly rotating planet or one that's still accreting, the main equation you would use is the hydrostatic equilibrium equation which basically says that the pressure pushing up against a thin shell of material must exactly cancel the force of gravity pulling it down: $$\frac{dP}{dr} = -\frac{Gm(r)}{r^2} \rho(r)$$ where $r$ is the radial distance from the planet's center, $P(r)$ is the pressure at that depth, $\rho(r)$ the density, and $G$ the gravitational constant. $m(r)$ is a function that gives you the mass inside the sphere of radius $r$, and as such $m(r) = \int\_0^r 4 \pi r^2 \rho(r') dr'$. But we want a system of differential equations to solve, so we differentiate this to get $$\frac{dm}{dr} = 4 \pi r^2 \rho(r)$$ Now, we just want to integrate this system of equations incorporating your boundary condition. Hold on though, we're not quite ready-- there are three functions we want to determine: $\rho$, $P$, and $m$, but only two equations. We need another equation to solve this thing! That equation comes in the form of the so-called equation of state, which is where the planetary composition comes in. It turns out that for a given material, there's a function that relates the density and pressure called the equation of state (which we'll denote by $g$): $$g(\rho, P) = 0$$ I should mention first off that the EOS also relates another variable to these two-- usually temperature, entropy, or specific internal energy. However the purposes of determining density profiles, the effects are pretty small (~a few %) so you can usually just set the temp to some reasonable value like 5,000 K and pull g from along that isotherm. Now, things can get a little tricky here-- the equation of state isn't guaranteed to give rise to a one-to-one relationship between density and pressure. In other words, we can't necessarily write $P = f(\rho)$ and $\rho = f^{-1}(P)$. If this is the case, we have to use a solver for what's known as a [differential-algebraic equation](https://en.wikipedia.org/wiki/Differential-algebraic_system_of_equations). You can mimic this behavior using a [normal](https://stackoverflow.com/questions/23578596/solve-an-implicit-ode-differential-algebraic-equation-dae) ODE package available in most languages, but it might be pretty slow. Another option is the language Julia, which has a great differential equations package that can solve [algebraic-differential equations](https://diffeq.sciml.ai/stable/tutorials/dae_example/). Usually for this regime though, we can at least write $P = f(\rho)$ even though we can't invert it, which for this specific system of equations is good enough to rewrite them as: $$\frac{d \rho}{dr} = -\frac{Gm(r)}{r^2 f'} \rho(r)$$ $$\frac{dm}{dr} = 4 \pi r^2 \rho(r)$$ Now, how do we find an EOS for a given material? Well there are several ways: 1. The most common in the field of planetary science is to use a premade table generated by someone who knows more about EOS's than you do. [SESAME](https://www.lanl.gov/org/ddste/aldsc/theoretical/physics-chemistry-materials/sesame-database.php) and [FPEOS](http://militzer.berkeley.edu/FPEOS/) are two I know of-- the latter is easy to access but unfortunately doesn't have a lot of important elements (most notably iron, which is important for rocky planets). The former is more complete but you have to request access through the link I gave. Either way with this option you'll have to spend some time learning other scripts or writing your own scripts to parse the tables. 2. You can muck about the literature to find a paper with a formula or plot that you can [digitize](https://automeris.io/WebPlotDigitizer/), like [this one](https://www.osti.gov/servlets/purl/6345571). 3. You can just give some kind of empirical formula you think seems reasonable enough. Power law relationships like $P = C\rho^{\gamma}$ are often popular for this. Phew, we finally have our equations set up! Now we just need to use our boundary conditions: if $R$ is the radius of your planet, this condition is that $m(R) = M$, where $M$ is the mass you wish the planet to have. But unfortunately, since we don't know what $R$ should be we have to take an iterative approach described by the following control flow: 1. Set $m(r = \epsilon) = 0$ and $\rho(r = \epsilon) = \rho\_{guess}$. Here $\epsilon$ is a small positive number but not quite $0$ because our equations are singular there. Can probably do a change of variable to fix this but it's less physically clear what's going on and I'm also lazy. 2. Solve the two coupled equations above until you get the radius $R$ such that $P(R) = f(\rho(R)) = 0$ (since there is no pressure at the surface of the planet). Might have to use some small positive pressure other than zero for numerical reasons. 3. Check $M(R)$. * If it's close enough to the mass you want, you're done! Extract the density and pressure profiles from the ODE solution. * If it's too big, make $\rho\_{guess}$ smaller and repeat step 2 * If it's too small, make $\rho\_{guess}$ bigger and repeat step 2 And that's all there is to it! If I have time later I'll try to add a simple example script to use but hopefully that's enough to get you started. EDIT: Pictures and a simple code -------------------------------- So I made a simple python code to calculate planetary masses, the result is below. It should be pretty easy to use, all you need to do is have the appropriate packages installed and change Mdesired and the equation of state function to your liking: ``` import scipy.interpolate as interp import numpy as np import scipy.optimize as opt import matplotlib.pyplot as plt import scipy.integrate as sciint from math import pi G = 6.67408e-11 # gravitational constant in [m^3][kg^-1][s^-2] rho_guess = 1e4 # initial guess for center of planet density in [kg][m^-3] Mdesired = 6e24 # Desired planet mass in [kg] # Now we normalize units so that G, M, rho_guess=1. # This will help numerical stability. rhostar = rho_guess Mstar = Mdesired Tstar = (G * rhostar)(-1/2) Lstar = (Mstar / rhostar)(1/3) Pstar = Mstar / (Lstar * Tstar2) Mdesired = Mdesired / Mstar rho_guess = rho_guess / rhostar M0 = 0.0 eps = 1e-4 # start ODE at this value of r to avoid singularity def dudr(r, u): # u[0] = rho, u[1] = m drhodr = -(u[1]/(r2 * dPdrho(u[0])) * u[0]) dmdr = 4pir*2u[0] return [drhodr, dmdr] def P(rho): """EOS of epsilon iron phase from OSTI 6345571 """ rho0 = 8.4301e3 / rhostar beta0 = 1821e9 / Pstar betaprime0 = 5.0 eta = rho/rho0 P = 1.5beta0((eta(7/3) - eta(5/3)) (1 + (3/4)(eta*(2/3) - 1)(betaprime0 - 4))) return P rho_EOS_arr = np.linspace(0, 50, 1000) dPdrho_arr = np.gradient(P(rho_EOS_arr), rho_EOS_arr) dPdrho = interp.interp1d(rho_EOS_arr, dPdrho_arr, bounds_error=False, fill_value=(0.0, 0.0)) def found_surface(r, u): """Event that terminates ODE when surface is reached """ Psurf = 1e-7 return P(u[0]) - Psurf found_surface.terminal = True def M(rho_guess, plot=False, obj = False): """Find mass of planet given guess for density at center. Can also plot density profiles and give ODE solution object """ sol = sciint.solve_ivp(dudr, (eps, 100), (rho_guess, M0), events = found_surface, t_eval = np.linspace(eps, 50, 10000)) if plot: plt.figure() plt.plot(sol.tLstar/1e3, sol.y[0,:]rhostar/1e3) plt.title(r"$\rho$ vs $r$") plt.xlabel(r"$r$ $(km)$") plt.ylabel(r"$\rho$ $(g/cm^3)$") plt.figure() plt.plot(sol.tLstar/1e3, sol.y[1,:]Mstar/1e3) plt.title(r"$M$ vs $r$") plt.xlabel(r"$r$ $(km)$") plt.ylabel(r"$M$ $(kg)$") if obj: return sol else: return sol.y[1,-1] rhoc = opt.newton(lambda rho: M(rho) - Mdesired, rho_guess, tol = 1e-3, maxiter=200) sol = M(rhoc, plot=True, obj=True) print(f"radius is {sol.t[-1]Lstar/1e3} km") print(f"mass is {sol.y[1,-1]Mstar:e} kg") plt.show() ``` Right now, I have it set up so that `Mdesired` is the mass of Earth in order to benchmark it. Here's what it predicts for the density profile of Earth[![enter image description here](https://i.stack.imgur.com/OsztR.png)](https://i.stack.imgur.com/OsztR.png). It's not terribly wrong-- it predicts Earth's radius is ~5000 km instead of ~6400 km. It also has a somewhat similar density profile to the core. The main reason for the discrepancy is that this calculation assumes the entire Earth is Iron in the $\epsilon$ phase-- this is really only true for the core and so it describes the crust and mantle as too dense and the end result is that it under predicts the radius of Earth. To fix this, you'd have to modify the equation of state so that its value changes with $m(r)$. This is a good exercise and if you understood this at all I recommend trying it out! EDIT 2: A more accurate code ---------------------------- So I really went and [nerd sniped](https://xkcd.com/356/) myself on this one. Below is a code I developed that I think in principle can give you the exact density profiles you see in the literature (sans temperature corrections) as long as you have appropriate equations of state. I realized that I made a mistake in my last edit when describing the path forward for multiple EOSs-- if you just make the EOS abruptly vary by $m(r)$ at material boundaries, it will give unphysical results. The reason is that the code implicitly assumes a continuous density profile, when in reality it is the pressure profile that is continuous. There are a couple of ways to deal with this, but what my code does is it solves for the density profile one material at a time, stitching together at the interfaces with the correct boundary conditions. As inputs, you need: 1. A desired mass for the planet in $kg$ 2. A guess at the density in the center of the planet in $kg/m^3$. This doesn't have to be super accurate-- ~10000 will probably work, but if you're working with very high or low masses you may need to adjust to get the solvers to converge 3. A collection of materials that define your planet's composition. There are two lists corresponding to this item: one gives the fraction of total planetary mass for each material, and one is a list of equations of state for each material. I've included ones for iron and silicate perovskite which is a good approximation for Earth, but if you want other materials just peruse the literature and find more formulas. And thats it! All you need to change are the variables in the input section, everything else should do the heavy lifting. Without any further ado, here's the code: ``` import scipy.interpolate as interp import numpy as np import scipy.optimize as opt import matplotlib.pyplot as plt import scipy.integrate as sciint from math import pi ##################################### ###### INPUTS ####################### ##################################### def P_silicates(rho): """EOS of cold silicate perovskite from Bina 1995 """ Ktau0 = 2621e9 / Pstar Kprimetau0 = 4 rho0 = 4.1 1e3 / rhostar f = 0.5((rho/rho0)(2/3) - 1) xi = -(3/4)(Kprimetau0 - 4) Pc = 3Ktau0f(1+2f)*(5/2)(1-xif) return Pc def P_iron(rho): """EOS of epsilon iron phase from OSTI 6345571 """ rho0 = 8.4301e3 / rhostar beta0 = 1821e9 / Pstar betaprime0 = 5.0 eta = rho/rho0 Pc = 1.5beta0((eta(7/3) - eta(5/3)) (1 + (3/4)(eta(2/3) - 1)(betaprime0 - 4))) return Pc G = 6.67408e-11 # gravitational constant in [m^3][kg^-1][s^-2] rho0_guess = 1e4 # initial guess for center of planet density in [kg][m^-3] Mdesired = 6e24 # Desired planet mass in [kg] mat_Mfracs = [0.3, 0.7] # Mass fraction for each material type, starting from # core outward mat_EOSs = [P_iron, P_silicates] # EOS for each material type ############################################## ######## SOLVER ############################## ############################################## # Now we normalize units so that G, M, rho_guess=1. # This will help numerical stability. msum = sum(mat_Mfracs) mat_Mfracs = [val/msum for val in mat_Mfracs] rhostar = rho0_guess Mstar = Mdesired Tstar = (G * rhostar)(-1/2) Lstar = (Mstar / rhostar)(1/3) Pstar = Mstar / (Lstar * Tstar2) Mdesired = Mdesired / Mstar rho0_guess = rho0_guess / rhostar M0 = 0.0 def dudr(r, u, Mdesired, mat_props): # u[0] = rho, u[1] = m drhodr = -(u[1]/(r2 * dPdrho(u, Mdesired, mat_props)) u[0]) dmdr = 4pir*2u[0] return [drhodr, dmdr] def dPdrho(rho, m, Mdesired, mat_props): Pfunc = mat_props["Pfunc"] drho = 1e-9 P1 = Pfunc(rho+drho) Pn1 = Pfunc(rho-drho) return (P1 - Pn1) / (2drho) def end_of_material(r, u, Mdesired, mat_props): """Event that terminates ODE when the end of a shell for a given material is reached. """ cum_mass_frac_end = mat_props["cum_mass_frac_end"] return u[1]/Mdesired - cum_mass_frac_end end_of_material.terminal = True def found_surface(r, u, Mdesired, mat_props): """Event that terminates ODE when surface is reached """ Psurf = 1e-7 Pfunc = mat_props["Pfunc"] return Pfunc(u[0]) - Psurf found_surface.terminal = True def solve_one_mat(rho0, m0, Mdesired, mat_props): r0 = mat_props["r0"] last_mat = mat_props["last_mat"] if last_mat: sol = sciint.solve_ivp( dudr, (r0, 100), (rho0, m0), args = (Mdesired, mat_props), events = found_surface, t_eval = np.linspace(r0, 100, 100000), tol = 1e-8 ) else: sol = sciint.solve_ivp( dudr, (r0, 100), (rho0, m0), args = (Mdesired, mat_props), events = (found_surface, end_of_material), t_eval = np.linspace(r0, 100, 100000), tol = 1e-8 ) return sol def M(rho0, Mdesired, mat_Mfracs, mat_EOSs, plot=False): """Find mass of planet given guess for density at center. Can also plot density profiles and give ODE solution object """ cumsum_Mfracs = np.cumsum(mat_Mfracs) rho0, m0, r0 = [rho0, 0.0, 1e-7] # solver starts at 1e-7 radius to avoid # singularity P0 = mat_EOSs[0](rho0) r_arr = np.array([]) rho_arr = np.array([]) m_arr = np.array([]) for i in range(len(mat_Mfracs)): # Build the mat_props dict for a given material, this tells the # solver what material we're using mat_props = {} mat_props["Pfunc"] = mat_EOSs[i] mat_props["cum_mass_frac_end"] = cumsum_Mfracs[i] mat_props["r0"] = r0 mat_props["last_mat"] = (i == len(mat_EOSs)-1) rho0 = opt.newton(lambda rho: mat_EOSs[i](rho) - P0, rho0, tol = 1e-8) sol = solve_one_mat(rho0, m0, Mdesired, mat_props) rho0, m0, r0 = [sol.y[0,-1], sol.y[1,-1], sol.t[-1]] P0 = mat_EOSs[i](rho0) r_arr = np.concatenate((r_arr, sol.t)) rho_arr = np.concatenate((rho_arr, sol.y[0,:])) m_arr = np.concatenate((m_arr, sol.y[1,:])) # If surface is reached before we can get through all materials, # we must end the loop if len(sol.t_events[0]) != 0 and not(mat_props["last_mat"]): missed_layers = True break else: missed_layers = False if plot: plt.figure() plt.plot(r_arrLstar/1e3, rho_arrrhostar/1e3) plt.title(r"$\rho$ vs $r$") plt.xlabel(r"$r$ $(km)$") plt.ylabel(r"$\rho$ $(g/cm^3)$") plt.figure() plt.plot(r_arrLstar/1e3, m_arrMstar) plt.title(r"$M$ vs $r$") plt.xlabel(r"$r$ $(km)$") plt.ylabel(r"$M$ $(kg)$") return (m_arr[-1], r_arr, rho_arr, m_arr, missed_layers) # Solve for density at planet center that gives the desired planetary mass rhoc = opt.newton( lambda rho0: M(rho0, Mdesired, mat_Mfracs, mat_EOSs)[0] - Mdesired, rho0_guess, tol = 1e-4, maxiter = 200 ) # Solve for and plot final values R, r_arr, rho_arr, m_arr, missed_layers = M( rhoc, Mdesired, mat_Mfracs, mat_EOSs, plot=True ) print(f"radius is {r_arr[-1]Lstar/1e3} km") print(f"mass is {m_arr[-1]Mstar:e} kg") ``` Right now I have some input parameters that are roughly correct for Earth, namely $M\_{desired} = 6\times 10^{24} kg$, with a composition of 30% Iron and 70% silicates. So how does it do? Pretty well, actually! Here's the density profile it outputs: [![enter image description here](https://i.stack.imgur.com/1pIUB.png)](https://i.stack.imgur.com/1pIUB.png) Which is pretty close to the types of profiles you'll see if you do a quick google search! It also estimates Earth's radius as 6250 km, pretty damn close to the actual value of 6370 km. Hopefully this was useful for you! A couple of simplifications I've made if you want to dig in more ---------------------------------------------------------------- 1. I ignore temperature dependence. In reality, the EOS will relate 3 variables and you'll need a third equation that tells you how temperature varies with depth. This is a trickier equation because it depends on time from accretion and radioactive decay and a whole bunch of other stuff that you need to specify. 2. In reality, the form of the EOS won't be the EOS for a single material-- as you go deeper, planetary composition changes. Tbh I'm not sure how you calculate this from first principles-- there's probably some sort of thermodynamic/buoyancy argument to be made but I'm not certain. EDIT--* my second code addresses this when there are clear boundaries between material types. In reality there will be a transition zone of some thickness, but it seems like more of the literature ignores this anyway. 3. If there are other forces on your planet like centripetal forces from spinning, that can change the pressure balance equation. 4. For super heavy objects like neutron stars, you have to take GR into account via the [Tolman-Oppenheimer-Volkoff Equation](https://en.wikipedia.org/wiki/Tolman%E2%80%93Oppenheimer%E2%80%93Volkoff_equation)
209,674	<p>I made a nice fantasy map with some really interesting geographic constellations, fitting my story. The climate zones don't fit, however.</p> <p>I found the tool, <a href="https://www.maptoglobe.com/#" rel="noreferrer">Map to Globe</a> where I can upload my map to create a globe. Is there a similar tool, where I can change the pole axis and download the map again?</p> <p>Update: I found another tool, <a href="https://www.worldmapgenerator.com/de/" rel="noreferrer">Worldmapgenerator</a> that does exactly what I want, but only with Earth. I want to do the same but with my own continents and islands</p> <p>Thanks for your help.</p> <p><a href="https://i.stack.imgur.com/OdSfh.png" rel="noreferrer"><img src="https://i.stack.imgur.com/OdSfh.png" alt="this is what i have" /></a></p> <p><a href="https://i.stack.imgur.com/FkIet.png" rel="noreferrer"><img src="https://i.stack.imgur.com/FkIet.png" alt="this is what i want" /></a></p>	[ { "answer_id": 210998, "author": "rek", "author_id": 25189, "author_profile": "https://worldbuilding.stackexchange.com/users/25189", "pm_score": 0, "selected": false, "text": "<p>I can propose a sort of workaround:</p>\n<ol>\n<li><p>Redraw your map as best you can in the Fuller/icosahedr...	2021/08/09	[ "https://worldbuilding.stackexchange.com/questions/209674", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/79394/" ]	I made a nice fantasy map with some really interesting geographic constellations, fitting my story. The climate zones don't fit, however. I found the tool, [Map to Globe](https://www.maptoglobe.com/#) where I can upload my map to create a globe. Is there a similar tool, where I can change the pole axis and download the map again? Update: I found another tool, [Worldmapgenerator](https://www.worldmapgenerator.com/de/) that does exactly what I want, but only with Earth. I want to do the same but with my own continents and islands Thanks for your help. [![this is what i have](https://i.stack.imgur.com/OdSfh.png)](https://i.stack.imgur.com/OdSfh.png) [![this is what i want](https://i.stack.imgur.com/FkIet.png)](https://i.stack.imgur.com/FkIet.png)	If I understand you correctly, what you want to do is re-project an existing equirectangular map to have the pole(s) in a different location—and your title question (“transfer onto a globe and back”) is how you think this might be done, not something that’s absolutely mandatory. Am I right? That is, would something that can do the re-projection without ever showing you a globe suit you? Because there’s software that can do it for you. Two options are the [Cartopy](https://scitools.org.uk/cartopy/docs/latest/) cartography library for Python, and the [G.Projector](https://www.giss.nasa.gov/tools/gprojector/) tool from NASA that uses Java. My evaluation so far: Cartopy gives better results, but is more fiddly to install and use. G.Projector is more straightforward. I’ll go through steps for both. Here’s a world map I’ll use to demonstrate. It’s not much of a map, but it will do for our purposes. [![A fairly low-res, low-effort world map of an invented world, in equirectangular projection.](https://i.stack.imgur.com/1DuAR.png)](https://i.stack.imgur.com/1DuAR.png) We’re going to re-project it so that the new poles are on what’s currently the equator—the north pole will lie on that big landmass to the left (0°N 135°W), and the south pole on the smallest landmass in the cluster of three in the centre (0°N 45°E). But the methods shown will be fully adaptable to wherever you want your poles to be. --- Installation ------------ Unfortunately neither of these were particularly straightforward for me to install or run. Maybe you’ll have better luck? ### Cartopy 1. Install [Miniconda](https://docs.conda.io/en/latest/miniconda.html). 2. Assuming without loss of generality that you’re on Windows, open the Anaconda Prompt that should now be on your Start Menu. 3. Type in `conda install -c conda-forge cartopy` and hit Enter. I haven’t tested this method, but it should work? (I already have Python on my computer, but not through Anaconda, so I first tried installing Cartopy through pip… ★☆☆☆☆ Do Not Recommend. It’d probably go better on Linux than on Windows, but the Windows machine is what I had at the time!) ### G.Projector 1. Install [Java](https://www.oracle.com/java/technologies/downloads/). 2. Download [G.Projector](https://www.giss.nasa.gov/tools/gprojector/download/) and extract it wherever you like. 3. Again assuming you’re on a Windows computer, double-click on `G.Projector.exe` in the folder you just extracted. After a delay, you should get a file chooser window. (Give it time, and if you’ve got other programs open, Alt+Tab between your windows occasionally. I thought it hadn’t worked, and I ended up fiddling around and finding a way to open it manually, only to find while writing this up that it had opened in the background without a taskbar icon. If it doesn’t work, let me know and I’ll share the steps I took to open it.) --- Running Cartopy --------------- 4. Copy this short script into a text file and save it as `reproject.py` in the same place as your image. * Change the filenames `notmuchofaworldmap.png` and `stillnotmuchofamap.png` to be your existing image, and a new name for your re-projected image, respectively. * Also change the numbers for `pole_longitude` and `pole_latitude`, and for `figsize`, to whatever you want. ``` import matplotlib.pyplot as plt import cartopy.crs as ccrs # The image starts in a PlateCarree (equirectangular) projection, taking up # the entire globe… img_projection = ccrs.PlateCarree() img_extent = (-180.0, 180.0, -90.0, 90.0) # …but we draw the map in a RotatedPole projection. Set the pole location to # suit yourself. map_projection = ccrs.RotatedPole(pole_longitude=45.0, pole_latitude=0.0) # Load the image. img = plt.imread("notmuchofaworldmap.png") # Create a new map at a size of 720×360 pixels @ 100dpi (the default for # matplotlib). I chose these sizes because this is how big I made my sample # map; change them to suit your image. fig = plt.figure(figsize=(7.2, 3.6), frameon=False) fig.tight_layout(pad=0) ax = plt.axes(projection=map_projection, frame_on=False) ax.set_global() ax.imshow(img, origin="upper", transform=img_projection, extent=img_extent) # Save the result! plt.savefig("stillnotmuchofamap.png", bbox_inches="tight", pad_inches=0) ``` 5. In the Anaconda Prompt that you still have open from before, navigate (with `cd`) to the location of your image and the script. 6. Type `python reproject.py` and hit Enter. Here’s the result of running this on the sample map. [![The same map of an invented world, re-projected so the poles are at a different location.](https://i.stack.imgur.com/G2PHo.png)](https://i.stack.imgur.com/G2PHo.png) It ain’t pretty, though that’s mostly because my original map was so low-quality. There will be distortion, but at the very least, it’ll show you how it should look, and you can take steps to tidy up from there! One thing I haven’t quite gotten right yet is making the result have the same dimensions as the original. A decent chunk of the code up there is just to get it to stop putting borders and padding around everything, which is [apparently](https://stackoverflow.com/questions/9295026/matplotlib-plots-removing-axis-legends-and-white-spaces) [not](https://stackoverflow.com/questions/40726323/matplotlib-scatter-plot-remove-white-padding) [easy](https://stackoverflow.com/questions/8218608/scipy-savefig-without-frames-axes-only-content)! And it still comes out to 22.5% smaller than the original. This may be a side effect of the re-projection process, but I don’t see why it should be. A crude solution would be to make the output bigger… --- Running G.Projector ------------------- 4. In the file chooser that opened up previously, find and open your image. Confirm that the default import options (equirectangular, −180° to 180° longitude, −90° to 90° latitude) are correct and click “Okay”. 5. In the Projection dialog that’s open by default, change the projection to “Equirectangular (Oblique)”, and change the “Centered on” position to whatever you choose. * As the name suggests, “Centered on” sets the centre of the map, not the pole location like we did with Cartopy. * If, as in my example, you want the (old) north pole to be at the centre, then the latitude will be 90°. The longitude you choose will point up from there, towards the new north pole (so -135° in my example). 6. On the Window menu, open the Graticule dialog and change Stroke to “None”. Likewise, open the Overlay dialog and change it to “<none>”. 7. On the File menu, use “Save map as...” to save the re-projected result, choosing whatever image dimensions you want (probably the same as the original image). Here’s what I got: [![The same map of an invented world, re-projected so the poles are at a different location.](https://i.stack.imgur.com/zBnCN.png)](https://i.stack.imgur.com/zBnCN.png) This is even less pretty than the Cartopy version. But it did the job!
210,404	<p><em>Note: Apologies for any grammatical errors.</em></p> <p>I have been working on a story of mine for quite a while now. A part of that story is a viral pathogen that turns people infected with it into what is basically analogous to 'fast zombies'</p> <p>The following is a quick rundown of the details I have come up with:</p> <p><strong>1. Types of immunity:</strong></p> <p>A) Cannot be infected through inhalation of virus aerosols. Can only be infected by getting bitten or spat in the face (high virus concentration; entering through mucous membranes). Will be referred to as Group A or Alpha for simplicity's sake from now on.</p> <p>B) Can be infected through inhalation of virus aerosols as well as the other vectors mentioned above. Will be referred to as Group B or Beta for simplicity's sake from now on.</p> <p><strong>2. Modes of Transmission:</strong></p> <p>When the virus is introduced into the body through a bite from an infected, it travels from the site of the bite to the brain by moving within the nervous system. As mentioned, exposure can also occur through inhalation of aerosolized virus at high concentrations through mucous membranes (Group B). As the virus is not bloodborne, it cannot be transmitted via blood spatter.</p> <p><strong>3. Stages of infection:</strong></p> <p>Airborne infection:</p> <blockquote> <ol> <li>Subject is infected.</li> <li>After virus has moved past mucosal epithelial barriers, it establishes infection in oropharyngeal or small bowel lymphoid tissues. Virus then travels through the body until it reaches the brain. This process can last approximately 1 to 2 weeks. During this period the subjects has no outwardly noticeable symptoms. However, infection of other Beta subjects is already possible.```</li> <li>Subject can develop a cough associated with a sore throat. Headaches can also manifest during this time. Subject also becomes irritable during this time.</li> <li>Subject starts to present further noticeable symptoms. Symptoms can include: Unusually heavy discharge of nasal mucus fluid; red, irritated, and bloodshot eyes.</li> <li>Overproduction of saliva from salivary glands (Week 2 - 3)</li> <li>Subject begins to show extreme aggression toward uninfected persons</li> </ol> </blockquote> <p>Infection through bite:</p> <blockquote> <ol> <li>Virus is introduced into the body through a bite from an infected,</li> <li>Virus travels from the site of the bite to the brain by moving within the nervous system</li> <li>Stages 3 - 6 are largely the same, with the biggest difference being shorter incubation period</li> </ol> </blockquote> <p>Overall average incubation period from infection to to full onset of the disease:</p> <blockquote> <ul> <li>Airborne: 3 - 4 Weeks:</li> <li>Bitten: 6 - 20 Days</li> </ul> </blockquote>	[ { "answer_id": 210416, "author": "Trioxidane", "author_id": 77012, "author_profile": "https://worldbuilding.stackexchange.com/users/77012", "pm_score": 0, "selected": false, "text": "<p><strong>Most of it is ok</strong></p>\n<p>Most of what you are saying is ok.</p>\n<p>Viruses are mostl...	2021/08/19	[ "https://worldbuilding.stackexchange.com/questions/210404", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/88614/" ]	Note: Apologies for any grammatical errors. I have been working on a story of mine for quite a while now. A part of that story is a viral pathogen that turns people infected with it into what is basically analogous to 'fast zombies' The following is a quick rundown of the details I have come up with: 1. Types of immunity: A) Cannot be infected through inhalation of virus aerosols. Can only be infected by getting bitten or spat in the face (high virus concentration; entering through mucous membranes). Will be referred to as Group A or Alpha for simplicity's sake from now on. B) Can be infected through inhalation of virus aerosols as well as the other vectors mentioned above. Will be referred to as Group B or Beta for simplicity's sake from now on. 2. Modes of Transmission: When the virus is introduced into the body through a bite from an infected, it travels from the site of the bite to the brain by moving within the nervous system. As mentioned, exposure can also occur through inhalation of aerosolized virus at high concentrations through mucous membranes (Group B). As the virus is not bloodborne, it cannot be transmitted via blood spatter. 3. Stages of infection: Airborne infection: > > 1. Subject is infected. > 2. After virus has moved past mucosal epithelial barriers, it establishes infection in oropharyngeal or small bowel lymphoid tissues. Virus then travels through the body until it reaches the brain. This process can last approximately 1 to 2 weeks. During this period the subjects has no outwardly noticeable symptoms. However, infection of other Beta subjects is already possible.``` > 3. Subject can develop a cough associated with a sore throat. Headaches can also manifest during this time. Subject also becomes irritable during this time. > 4. Subject starts to present further noticeable symptoms. Symptoms can include: Unusually heavy discharge of nasal mucus fluid; red, irritated, and bloodshot eyes. > 5. Overproduction of saliva from salivary glands (Week 2 - 3) > 6. Subject begins to show extreme aggression toward uninfected persons > > > Infection through bite: > > 1. Virus is introduced into the body through a bite from an infected, > 2. Virus travels from the site of the bite to the brain by moving within the nervous system > 3. Stages 3 - 6 are largely the same, with the biggest difference being shorter incubation period > > > Overall average incubation period from infection to to full onset of the disease: > > * Airborne: 3 - 4 Weeks: > * Bitten: 6 - 20 Days > > >	[Para-Rabies](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7975959/): --------------------------------------------------------------------- It is rare to have a virus have significantly different modes of transmission based on host immunity (not impossible). If the virus transmits through a bite, it's likely bloodborne as well. The more things you ask a virus (very simple thing) to do, the less plausible. Bacteria can exhibit more complex behaviors, but you clearly want a virus. I'd research [rabies](https://en.wikipedia.org/wiki/Rabies), make your virus a variant of the rabies virus (does much of what you want, has established patterns, neurological, transmissible via bite, causes behavioral abnormality. To get the combination of infective pathways you want, consider using two related viruses. So as a scenario, imagine someone makes a super-rabies virus in a lab for terror purposes. Outbreaks would be horrifying but not globally disastrous. But sloppy work means the virus merges with an influenza strain in a coinfected individual and a hybrid virus emerges that is slow-incubating, looks like the flu for most of its early infection pattern, and doesn't affect anyone who had that strain of the flu previously. Developing a vaccine is only partly effective (and if no one ever made a vaccine against this flu strain prior, it could take a long time to do so).One is transmitted airborne, but a substantial percent of the populous is immune. The other is transmitted via bite, but the zombies extensively bite each other to the point that coinfection with the two virus strains is widely prevalent. A gentle breaking of the skin could even be the socializing element that ties your zombies together. If zombies accept biting from other zombies, and look for the presence of bite marks and aggressive biting behavior as the indicator of who is or isn't a zombie, you have a way the zombies know who is or isn't to be attacked. The bites physically mark them to each other (and the more a person is bit up, the faster the infection). A person who was "captured" by zombies would get repeatedly bitten (increasing the chance of the bite-transmissible strain being spread) and the zombies would keep biting until the person started biting back. The constant in-biting makes "faking it" by covering yourself in false bites possible but extremely risky behavior. The fact that not all zombies are guaranteed to have the bite-transmissible form also means people can get bitten and still convince themselves they might not be infected, increasing the likelihood they might hide the fact they were bitten to avoid being killed/locked up/ostracized.
215,306	<p>Assume that a pre-modern army numbering 50,000 men is going to campaign in a foreign territory for 180-days, during which they completely rely on their supply wagons which cannot be refilled, and each wagon is pulled by two oxen, how many oxcarts are needed supply all soldier?</p> <hr /> <p>My own research is probably way off, but I present it nonetheless:</p> <p>First, we must determine how much food the army is going to need. According to <a href="https://www.history.com/news/soldier-wartime-food-rations-battle-napoleon-vietnam" rel="noreferrer">this article</a> Roman soldiers were given 1 pound of meat every day, while it doesn't seem to be all they got, we can use it as a baseline. Therefore:</p> <pre><code>total weight of food = 1 ld × 50,000 × 180 = 9 000 000 lds </code></pre> <p>Then we must determine how much can two oxen, according to <a href="http://www.ruralheritage.com/messageboard/frontporch/5219.htm" rel="noreferrer">this</a> they can pull three times their own weight, according to Google average weight of an ox is around 2000 lds, thus.</p> <pre><code>pull weight of two oxen = 2000 lds × 3 × 2 = 12 000 lds </code></pre> <p>Then there is the cart itself and its driver. Estimating 1 0000 lds for cart weight seems fair, and driver's weight 200 lds, thus:</p> <pre><code>loading capacity of cart = 12 000 lds - (1 000 lds + 200 lds) = 10 800 lds </code></pre> <p>Which would mean that:</p> <pre><code>number of oxcarts needed = 9 000 000 lds / 10 800 = 833 oxcarts </code></pre> <p>That number seems unsurprisingly small...</p>	[ { "answer_id": 215311, "author": "Mark", "author_id": 278, "author_profile": "https://worldbuilding.stackexchange.com/users/278", "pm_score": 3, "selected": false, "text": "<p>More wagons than you can get.</p>\n<p>Pre-modern armies on the march were generally limited to 40,000 or fewer m...	2021/10/13	[ "https://worldbuilding.stackexchange.com/questions/215306", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/47028/" ]	Assume that a pre-modern army numbering 50,000 men is going to campaign in a foreign territory for 180-days, during which they completely rely on their supply wagons which cannot be refilled, and each wagon is pulled by two oxen, how many oxcarts are needed supply all soldier? --- My own research is probably way off, but I present it nonetheless: First, we must determine how much food the army is going to need. According to [this article](https://www.history.com/news/soldier-wartime-food-rations-battle-napoleon-vietnam) Roman soldiers were given 1 pound of meat every day, while it doesn't seem to be all they got, we can use it as a baseline. Therefore: ``` total weight of food = 1 ld × 50,000 × 180 = 9 000 000 lds ``` Then we must determine how much can two oxen, according to [this](http://www.ruralheritage.com/messageboard/frontporch/5219.htm) they can pull three times their own weight, according to Google average weight of an ox is around 2000 lds, thus. ``` pull weight of two oxen = 2000 lds × 3 × 2 = 12 000 lds ``` Then there is the cart itself and its driver. Estimating 1 0000 lds for cart weight seems fair, and driver's weight 200 lds, thus: ``` loading capacity of cart = 12 000 lds - (1 000 lds + 200 lds) = 10 800 lds ``` Which would mean that: ``` number of oxcarts needed = 9 000 000 lds / 10 800 = 833 oxcarts ``` That number seems unsurprisingly small...	I agree with the people who write it won't work, but with a slightly different emphasis. * The daily food allocation per soldier is almost irrelevant, but in addition to AcePL's figures for Roman soldiers, consider the [humanitarian daily ration](https://en.wikipedia.org/wiki/Humanitarian_daily_ration) at 1.9 lbs. It provides 9,200 kilojoules, while MRE are some 5,000 kilojoules (three per day). So a soldier would need some 3 lbs. of HDR per day. Compared to the Roman figure, that's close enough for government work, but I'll go with those 3-4 lbs. to account for the lack of modern preservation -- there will be spoilage. 50,000 people need about 100 short tons, slightly less than 100 metric tons per day. * I think you are grossly underestimating the weight of an oxcart. Googling a couple of sources gives about 500 to 700 kg for a roman wagon. That means 140 to 200 wagons per day. Trick question, where do they come from? * A typical oxcart could do 2 mph for 5 hours per day (random googling). * The oxen will need food. They might graze (only 5 hours of travel per day), but they will also need supplemental food if they do heavy work. And the pastures along the road will be gone soon. 18 kg per day per oxen. * So for each day, the notional oxcart would consume 5% or more of the load. After at most 20 days, all your food/fodder is gone feeding the oxen. * An oxcart could start out loaded half with cargo, half with fodder, and consume all that fodder within ten days (100 miles). That would leave you with an oxcart, the cargo, and no fodder for the return trip. * More reasonably, there are plenty of supply depots. Some oxcarts carry only cargo, others only fodder to various depots. The calculation gets slightly more complicated, especially if you turn some of the oxen into soup instead of returning empty carts. * Then there is the problem of assembling food at the starting camp. With luck, it is a (river?) port. If it is merely a fertile farming area, food/fodder will be required to collect the food. You will need well-stocked supply depots in secure terrain close to your operational area, plus constant resupply. The alternative is looting, which devastates the area rather quickly. L.Dutch mentioned that. (I don't think canned food is the key development, I think it was more due to a state that could maintain enough granaries. But that's a detail.) When I wrote that the daily ration almost doesn't matter for the calculation, it was for two reasons. First, oxen eat more than men. Second, if you have an organized state to provide 100 tons per day, a few percent more or less won't break it.
218,226	<p>In my story, a whole scientific mission will land on a desert planet whose temperature in the day reaches sixty degrees Celsius, they will land near the North Pole, specifically next to a Great extinct volcanic mountain 15 km high with cinder cone shape.</p> <p>Assuming (mostly unrealistic) that strong winds and deadly dust storms always come from the same direction, <strong>can the scientific mission be safe from the damages of these winds and storms if it uses the volcanic mountain as a shield?</strong> (That is, to land in a place where the volcanic mountain will serve as a shield protecting them from winds and storms)</p> <p><img src="https://i.stack.imgur.com/MNwKc.png" alt="Illustrative image" /></p> <pre><code>(to scale) </code></pre> <p><em>Note 1: I mean winds of about 160 to 240 kph here</em></p> <p><em>Note 2: The atmosphere of this planet is similar to that of Earth, but the gravity is slightly less</em></p> <p><em>Note 3: If you find this kind of wind unrealistic then please give me your advice (And if you don't have advice, do nothing)</em></p> <p><em>Note 4, which I think is unimportant: Specifically, the scientific mission will land at latitude 70 N or so</em></p>	[ { "answer_id": 218228, "author": "Mon", "author_id": 76192, "author_profile": "https://worldbuilding.stackexchange.com/users/76192", "pm_score": 4, "selected": false, "text": "<p>Probably not. The trouble is that while mountain <strong>chains</strong> can and do divert wind patterns a si...	2021/11/28	[ "https://worldbuilding.stackexchange.com/questions/218226", "https://worldbuilding.stackexchange.com", "https://worldbuilding.stackexchange.com/users/91159/" ]	In my story, a whole scientific mission will land on a desert planet whose temperature in the day reaches sixty degrees Celsius, they will land near the North Pole, specifically next to a Great extinct volcanic mountain 15 km high with cinder cone shape. Assuming (mostly unrealistic) that strong winds and deadly dust storms always come from the same direction, can the scientific mission be safe from the damages of these winds and storms if it uses the volcanic mountain as a shield? (That is, to land in a place where the volcanic mountain will serve as a shield protecting them from winds and storms) ![Illustrative image](https://i.stack.imgur.com/MNwKc.png) ``` (to scale) ``` Note 1: I mean winds of about 160 to 240 kph here Note 2: The atmosphere of this planet is similar to that of Earth, but the gravity is slightly less Note 3: If you find this kind of wind unrealistic then please give me your advice (And if you don't have advice, do nothing) Note 4, which I think is unimportant: Specifically, the scientific mission will land at latitude 70 N or so	Your party lands in a crater like that of Haleakala. <https://hanahou.com/14.4/quiet> [![haleakala](https://i.stack.imgur.com/9q5qZ.jpg)](https://i.stack.imgur.com/9q5qZ.jpg) > > Of course, national park status alone isn’t enough to make a place > quiet, as any visit to Yellowstone will prove. But here an unusual mix > of other factors comes into play: Huge sections of Haleakala are > almost devoid of life, so there are no leaves or animals to make > sound; the bowl and the cinder cones offer shelter from the wind; even > the altitude, which keeps the crater cooler than the lowlands, slows > and changes the way sound moves across the landscape. > > > Haleakala in Hawaii is a giant shield volcano as I imagine your volcano must be. Down in the crater, it is preternaturally quiet. The linked article does a good job of conveying both the silence. It is also eerie and bleak. Set your party down in the old caldera. They will be protected there and you can also use elements of the actual Haleakala caldera for your story. If your party then ventures out into the surrounding lands they could go up and over the edge, or through a lava tube that pierces the wall.