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8,498 | <p>I wonder if it possible for human civilization to evolve into two different civilizations.</p>
<p>One is controlled by artificial intelligence (or by uploaded human minds) and the other is biology-based with all kinds of imaginable biological advances such as interconnected brains, bio-machines, specialized organisms, advanced biological soldiers both land-based, flying and swimming types, controlled insect-like nano-organisms, on-the-fly mutations in necessity, multi-cloning and perfectly looking "people" with hyper-abilities and regeneration etc.</p>
<p>The both civilizations think of themselves as the true cultural continuation of humanity, admire human history and the like.</p>
<p>Both sides conduct a lot of research.</p>
<p>I wonder how such distinction would be preserved if the civilizations came into contact. How it is possible to avoid intermix of the technologies? Can they co-exist on the same planet? How their war would look like? Can advanced bio-technology be developed without traditional computers (or after refusing traditional computers), totally relying on the artificially-grown huge brains?</p>
<p><strong>UPDATE</strong></p>
<p>The idea has been put in a short film here:
<a href="https://www.youtube.com/watch?v=lcaWEuspFzU" rel="nofollow noreferrer">https://www.youtube.com/watch?v=lcaWEuspFzU</a></p>
| [
{
"answer_id": 8500,
"author": "Cort Ammon",
"author_id": 2252,
"author_profile": "https://worldbuilding.stackexchange.com/users/2252",
"pm_score": 3,
"selected": false,
"text": "<h2>First, a lot of setup</h2>\n\n<p>For this answer I have to make a lot of assumptions about how AI's work ... | 2015/01/09 | [
"https://worldbuilding.stackexchange.com/questions/8498",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/1991/"
] | I wonder if it possible for human civilization to evolve into two different civilizations.
One is controlled by artificial intelligence (or by uploaded human minds) and the other is biology-based with all kinds of imaginable biological advances such as interconnected brains, bio-machines, specialized organisms, advanced biological soldiers both land-based, flying and swimming types, controlled insect-like nano-organisms, on-the-fly mutations in necessity, multi-cloning and perfectly looking "people" with hyper-abilities and regeneration etc.
The both civilizations think of themselves as the true cultural continuation of humanity, admire human history and the like.
Both sides conduct a lot of research.
I wonder how such distinction would be preserved if the civilizations came into contact. How it is possible to avoid intermix of the technologies? Can they co-exist on the same planet? How their war would look like? Can advanced bio-technology be developed without traditional computers (or after refusing traditional computers), totally relying on the artificially-grown huge brains?
**UPDATE**
The idea has been put in a short film here:
<https://www.youtube.com/watch?v=lcaWEuspFzU> | First, a lot of setup
---------------------
For this answer I have to make a lot of assumptions about how AI's work vs. how organic brains work. I find the most meaningful answer coming from a quad chart based on two ways of valuing a "thing." They're certainly not the only two ways to value things, but they prove useful for me when thinking about AI.
I chart value of objects on how well an object behaves when it works "as defined," and how well an object behaves when it works "out of spec," (i.e. when you ask it to do something you don't think it's "expected" to do, how well does it keep up)
```
Out of Spec Behavior
Poor | Good
+---------+-------------+
As Good | Tool | Interesting |
Defined ------+---------+-------------+
Behavior Poor | Crude | Resilient |
+---------+-------------+
```
* **Crude things are not good at anything.** They fall apart with use, and are generally not very good at adapting to new situations. The modern human category of "child's toys" fits in this block.
* **Tools are amazingly good at what they do best.** Once we devise a tool, and understand its abilities, they prove amazingly good at accomplishing goals. However, they are often very narrowly focused, unable to adapt to changing environments. A helicopter can fly in ways that are a marvel to behold, as long as they are kept within spec. However, on Everest, humans climb higher than any helicopter can go because the air is too thin. There was a famous rescue on the lower slopes of Everest where a helicopter pilot decided it was worth the risk, but refused to land at that altitude for fear the machine would not be able to take off again. He instead hovered just a few feet off the snow, carefully feeling for a sign that the helicopter was leaving its spec range.
* **Resilient objects just keep working, against all odds.** Some systems are not known for their ability to perform in ideal conditions, but in unpredictable dangerous environments where one does not get to prepare. Survival gear tends to fall in this category. As one example, there is a military technique nicknamed "dummy cording" where you discard the core out of some parachute cord (to save weight) and use the outer sheaths to tie your gear to yourself so that it stays around in times of great exhaustion. Parachute cord was *never* designed for this operation, but its construction is so resilient that it turns out to be useful, even after you've taken the strong part out.
* **Interesting objects keep our attention with their behavior.** When we try to use them "in spec" as tools, they function perfectly, beating our wildest expectations. When we have to use them "out of spec," they keep surprising us by never failing, even when submitted to environmental conditions far outside of their "operating environment." Military equipment often fits in this category. Consider the famous pictures of [helicopter halos](http://realitypod.com/2011/03/helicopter-static-electricity-phenomenon-explained-corona-effect/) in the desert from sand hitting the rotors, or the A-10's legendary ability to fly, [even after taking hundreds of round](http://www.strangemilitary.com/images/content/109862.jpg)s. Even those who understand the physics of what is happening and the design decisions that lead to it are awed by it at first sight.
**All four of these categories are relative to the observer.** A Swiss watchmaker would draw the boundaries differently than an Amazon tribal elder would.
**I put forth an (unproven) hypothesis that AI's and organic brains take a different path through this quad chart.**
* If you believe in evolution, Organic Life consists of all of the really good random discoveries genetics found over millions of years. Along the way, each of these ideas are subjected to a remarkable number of varying scenarios. The ones that survive are ones which improve survivability, but more importantly are versatile enough to be useful in thousands of unexpected situations. **Organic life improves itself by trying to go from Crude to Resilient to Interesting.**
* AIs are generally computer programs. Programs were originally tools. Currently our programmers are very good at making computers do astonishing things in spec, but we are not very good at making the computers do good things when we surprise the printer. This is the source of great frustration for any IT person who has to explain why the user's input wasn't "spec," so the computer is failing. AI seeks to be more and more versatile, handling situations the programmer did not think of. **AI improves itself by trying to go from Crude to Tool to Interesting.**
**As an over-generalization, I will assume your biological and AI centric human civilizations will continue to develop along these general principles.**
**The most obvious effect of these two paths is that the AI centric civilization will want to change its environment more drastically than the biological based one will.** This is because a intermediate grade AI is a Tool, which means it works well when you can apply it "in spec." The easiest way to make sure these Tools function is to change the face of the world so that it is easier for a user of the AI Tool to be confident that its use is "in spec."
Biological based civilizations will be less inclined to change their environment. In fact, if the environment is complicated and hostile, it makes it easier to ensure all of its creations are Resilient. Your biological civilization will be fine with a world where they can never tell if their creations are operating "in spec," because that isn't as important to their civilization. They would easily create amazing creations, but their amazingness would show up in the resiliency of their designs. You wouldn't see a bio-jetpack that can be used once to assault an AI tower through an unprotected ledge, but you might see a jetpack that can be used continuously, and has uses for fanning the eggs of young creatures in hot summers. **This isn't because the giant brains can't figure out how to make such a one-shot device, but rather because the giant brains wont *want* to make such a device. They've been raised to look for more resilient solutions.**
---
Now for the mixing and the war
------------------------------
We will assume each side has a strong cultural identity: they believe their approach is superior enough to distinguish "us" from "them."
From the biological perspective, there will be only one possible response to mixing: increase the complexity of the environment. If they are fearful of the AIs, then they will seek to make "them" unable to progress. A complicated environment means it's harder to tell that Tools are operating "in spec," limiting AI's ability to leverage all of its creations. On the other hand, if they seek to coexist with the AIs, the they need a way to make the AI's robust like their culture. To do this, they would wrap the AIs in environments that are designed to appear simple to the AIs (letting them use their tools), but on the outside, such environments are highly resilient (so the Biological can make sure their friendly AIs never face complicated out-of-spec environments).
From the AI perspective, there is also only one possible response to the mixing: simplify the complexity of the environment. If they are fearful of the Biologicals, then they will seek to achieve a strategic advantage by paving over all of the complexities of the Biological environment. If they seek to coexist with the Biologicals, then they will need to develop a common ground where they can safely interact with Biology without fear of going out of spec.
So from both perspectives, there is a natural desire to segregate. The most Interesting AIs will seek out the most predictable regions far away from the Biologicals, to make sure they are never driven "out of spec." The most Interesting Biological creatures will seek out the deepest most complex natural regions of their area, far away from the AIs, to make sure that any dangerous Tools are blunted by the journey to their home.
The middle will be colonized by a mix of Tools and Resilient creatures which have to seek out their own living after the most Interesting creatures take the prime real estate. The more you want to minimize the mixing, the more you need the young Tools to look up to the intelegence of their Interesting AI masters, and the more you need the young Resilient creatures to look up to the wisdom of their Interesting organic elders. It would be up to you as an author to decide how far you want to take that.
---
However, consider that such mixing may not be such a bad thing. Consider that your average adult cannot compete with the wisdom of an elder. Consider that your average sword cannot compete with the awesome capabilities of a firearm. But give an average adult a sword, and put it in a realm with wise-but-unarmed elders, and firearm wielding-but-mindless drones on the other side, and suddenly they just might be able to hold their own.
And darn shame if after millennia of conflict over who the *rightful heirs* to humanity are, if a group of humans which are viewed as Crude by both AI and Biological masters alike can suddenly stand in the middle of these two great forces and proclaim them heirs to *both* of their lineages.
Balancing the Game
------------------
Very often we assume that AI's will naturally win over Biology, but there's some argument for why that isn't naturally so. **AI's are better at solving small, well defined problems. Biology is better at solving vague large problems.** Consider the health of an ant colony. If we want to kill an ant colony, its not hard. We put some ant-killer down, let them eat it, and laugh in our superiority.
*The ants laugh too.* By biomass, they outweigh all humans together and are found on nearly every type of terrain on this planet. The ants are far less concerned with the loss of one colony. *Maybe they are winning?*
Interaction between AI and Biology would consist strongly of the AI side striking for a small well defined goal with a superior force, and capturing it virtually every time. However, the Biologicals would seek to make it a Phyric victory. They want the AIs to win the battles but lose the war. Their tactics would involve letting the AIs get what they want, but making sure that in each battle, they give more than they capture. Biologicals would excel at giving up a township, and using that to misplace the AI armies and sac an AI city in trade.
The AIs would try to predict their behavior, and that's where the real balance would lie. Biology is highly chaotic. It is virtually impossible to predict what a mind will think of next. Chaos is the enemy of AI planning. You can't apply logic to it, because the purpose of moving chaotically is that it is impossible to tell if an attack is going to be a minor skirmish or a major war. *Not even the Biologists would know which it would be, until the last moment.* That's where the Biologists can return the balance to even.
There is a fighting style where you set up your self and your environment such that you don't prevent your opponent from doing anything, and you don't commit to anything. You just make sure that you get a slight advantage no matter what they do. Then you wait. Due to a lot of math I wont put here, I've found this is *much* easier to accomplish with Biology (focusing on Resilience) than it is to accomplish with AI (focusing on logic and Tools). Biology would give the AI a few billion options, all of which look good, but each of which is flawed. The AI would have to analyze each of them, while the Biology knows that it doesn't need to. Whatever path the AI chooses, Biology is ready.
This technique is very dependent on chaotic behavior. If the AI chooses to do nothing, then their predictions become exponentially less accurate, which is brutal for long term planning. This technique forces the AI to make a choice, without giving it time to make the choice wisely. |
8,652 | <p><strong>The Situation</strong></p>
<p>The fantasy world of Terrearth is once again threatened by the Shadow, a sentient, but completely unintelligible being composed of Absolute Evil, whose sole purpose is to destroy the world to replace it with a plain of absolute nothingness, in which evil will be the only thing left. The evil will have a physical form in this world, and will be the only thing that will flutter over it forever.
However, at any era in which the Shadow occurred, a group of heroes managed to banish the being in an underworld, but they have never defeated it definitively.
Now, the Shadow has come back, and the inhabitants of Terrearth do not know how to deal with it. The knowledge of how the heroes of the past times defeated the Shadow are shrouded in a cloak of legend, and therefore it is the duty of the armies of the lands of Terrearth at least to try to limit the Shadow, awaiting the arrival of the heroes.</p>
<p><em>So, how can humans deal with this cosmic horror? I'm not looking for a way to defeat it permanently (because I know what is), but a way in which "simple" human beings may be able to fight it and contain it.</em></p>
<p><strong>Humans Background</strong></p>
<ul>
<li>Terreath universe is a fantasy world, populated only by humans and
supernatural entities like ghosts, lich, ent and monstrous animals.
There are no other sentient races apart from humans.</li>
<li>Technological level is medieval. There is no gunpowder, however alchemy is
quite advanced, and allows you to have healing poultice and body
booster similar to our combat drugs.</li>
<li>The magic exists, but is not widely practiced, as it is difficult to
understand, and there are no institutions or groups of magicians
dedicated to the research and understanding of it.</li>
<li>The few holders of magical power are druids. These figures are
priests scattered in some forest villages, who are dedicated
to the study of natural and healing magic, and hand down their
knowledge to their children. Druids form a social entity called the "Circle", but it has no political or religious power, and it is only a way to exchange
information and knowledge during meetings.</li>
<li>There are no gods or goddesses, and there are no forms of organized religion. All the inhabitants of Terrearth however believe in one principle, the Good. The Principle of Good is universally accepted by all.</li>
<li>There are not clerics. There are paladins, who fight evil, but there is no religious figures assimilable to organized religion figures.</li>
<li>If we should make comparison with D&D Alignment system, every people of Terrearth would be Lawful Good. In the world of Terrearth most evil does not exist. There are no wars, genocide, torture, etc. Some minor crimes exist, but put in place by those who have a relativistic vision of the good. Few are the people who belong to the alignment Neutral Good and Chaotic Good, and are viewed with suspicion by Lawful. In addition there is a nomadic people, whose relationship with other people is quite tense, whose allinamento oscillates between Chaotic Good and Chaotic Neutral.</li>
<li>There are many countries, but the armies are mainly used to fight
crime and the Shadow.</li>
</ul>
<p><strong>The Shadow Background</strong></p>
<ul>
<li>The Shadow is all the evil that man can provoke, and tries to take in
the world, not with violent and bloody hordes of his minions, but infiltrating,
acting slowly and without emotion.</li>
<li>The Shadow flourishes in living corroupting them and bringing out the
dark side of man. A corrupt man will dedicate himself only to evil
actions, paving the way for other infections. However <strong>the corrupt do not openly expresses his evil acts</strong>. He prefers to work stealthily, and when the opportunity to spread even more evil is ripe, he acts.</li>
<li>After the Shadow infects all living in an area
, the whole area becomes nothing. The only thing there is a dense
and impenetrable cloak of pure darkness, which is the physical form
of evil.</li>
<li>The Shadow sometimes manages to create minions made of absolute evil,
but they may last only a few days before fading. The Shadow prefer to
resort to corruption rather than the creation of minions.</li>
<li>Human armies have managed to contain the Shadow after it has eaten a
large territory on the northern edge of the world, however the Shadow
infiltrates more and more human in the ranks.</li>
</ul>
<p>EDIT
The magic is difficult to apply because the only types of magic "socially acceptable are elemental and healing ones, and the only holders of these knowledge are druids, pretty jealous of their knowledge. The mental and arcane magic is opposed and seen as unhelpful. Since no one is devoted to its study and most of the few magicians who master this type of magic are self-taught, this type of magic is not widespread.</p>
<p>EDIT 2</p>
<p>The reason for there is an almost monolithic belief system is historical. Before the advent of the Shadow, the world was more or less like ours. Wars, conspiracies and evil spread. In short, there was a gray morality. When the Shadow had appeared for the first time in the world, Terrearth risked being destroyed just because the Shadow attacked aggressively, taking advantage of all the evil available at the time. Some heroes managed to banish it, and the world returned to the usual evil. When the Shadow came for the second time, and was bannished for a second time, the people realized that the Shadow needed evil for his purposes , and established the Principle of Good.
Now, it is true that there are different philosophies about the Good (Lawful, Neutral and Chaotic). There is also this nomadic people who while not indulging in evil acts without reason, give no importance to the Principle. But the Principle of Good is universally known to all, and no one would do an evil act, never mind for its own sake. (For evil acts I mean the most serious crimes. Stealing, defraud or deceive someone, if they have no serious consequences, are not considered "evil" by Terrearthians, although they are still punishable by law)</p>
| [
{
"answer_id": 8661,
"author": "Cort Ammon",
"author_id": 2252,
"author_profile": "https://worldbuilding.stackexchange.com/users/2252",
"pm_score": 5,
"selected": true,
"text": "<p><strong>Invent a new religion!</strong></p>\n\n<p>I'm not joking. The world you have described is very ver... | 2015/01/13 | [
"https://worldbuilding.stackexchange.com/questions/8652",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/5216/"
] | **The Situation**
The fantasy world of Terrearth is once again threatened by the Shadow, a sentient, but completely unintelligible being composed of Absolute Evil, whose sole purpose is to destroy the world to replace it with a plain of absolute nothingness, in which evil will be the only thing left. The evil will have a physical form in this world, and will be the only thing that will flutter over it forever.
However, at any era in which the Shadow occurred, a group of heroes managed to banish the being in an underworld, but they have never defeated it definitively.
Now, the Shadow has come back, and the inhabitants of Terrearth do not know how to deal with it. The knowledge of how the heroes of the past times defeated the Shadow are shrouded in a cloak of legend, and therefore it is the duty of the armies of the lands of Terrearth at least to try to limit the Shadow, awaiting the arrival of the heroes.
*So, how can humans deal with this cosmic horror? I'm not looking for a way to defeat it permanently (because I know what is), but a way in which "simple" human beings may be able to fight it and contain it.*
**Humans Background**
* Terreath universe is a fantasy world, populated only by humans and
supernatural entities like ghosts, lich, ent and monstrous animals.
There are no other sentient races apart from humans.
* Technological level is medieval. There is no gunpowder, however alchemy is
quite advanced, and allows you to have healing poultice and body
booster similar to our combat drugs.
* The magic exists, but is not widely practiced, as it is difficult to
understand, and there are no institutions or groups of magicians
dedicated to the research and understanding of it.
* The few holders of magical power are druids. These figures are
priests scattered in some forest villages, who are dedicated
to the study of natural and healing magic, and hand down their
knowledge to their children. Druids form a social entity called the "Circle", but it has no political or religious power, and it is only a way to exchange
information and knowledge during meetings.
* There are no gods or goddesses, and there are no forms of organized religion. All the inhabitants of Terrearth however believe in one principle, the Good. The Principle of Good is universally accepted by all.
* There are not clerics. There are paladins, who fight evil, but there is no religious figures assimilable to organized religion figures.
* If we should make comparison with D&D Alignment system, every people of Terrearth would be Lawful Good. In the world of Terrearth most evil does not exist. There are no wars, genocide, torture, etc. Some minor crimes exist, but put in place by those who have a relativistic vision of the good. Few are the people who belong to the alignment Neutral Good and Chaotic Good, and are viewed with suspicion by Lawful. In addition there is a nomadic people, whose relationship with other people is quite tense, whose allinamento oscillates between Chaotic Good and Chaotic Neutral.
* There are many countries, but the armies are mainly used to fight
crime and the Shadow.
**The Shadow Background**
* The Shadow is all the evil that man can provoke, and tries to take in
the world, not with violent and bloody hordes of his minions, but infiltrating,
acting slowly and without emotion.
* The Shadow flourishes in living corroupting them and bringing out the
dark side of man. A corrupt man will dedicate himself only to evil
actions, paving the way for other infections. However **the corrupt do not openly expresses his evil acts**. He prefers to work stealthily, and when the opportunity to spread even more evil is ripe, he acts.
* After the Shadow infects all living in an area
, the whole area becomes nothing. The only thing there is a dense
and impenetrable cloak of pure darkness, which is the physical form
of evil.
* The Shadow sometimes manages to create minions made of absolute evil,
but they may last only a few days before fading. The Shadow prefer to
resort to corruption rather than the creation of minions.
* Human armies have managed to contain the Shadow after it has eaten a
large territory on the northern edge of the world, however the Shadow
infiltrates more and more human in the ranks.
EDIT
The magic is difficult to apply because the only types of magic "socially acceptable are elemental and healing ones, and the only holders of these knowledge are druids, pretty jealous of their knowledge. The mental and arcane magic is opposed and seen as unhelpful. Since no one is devoted to its study and most of the few magicians who master this type of magic are self-taught, this type of magic is not widespread.
EDIT 2
The reason for there is an almost monolithic belief system is historical. Before the advent of the Shadow, the world was more or less like ours. Wars, conspiracies and evil spread. In short, there was a gray morality. When the Shadow had appeared for the first time in the world, Terrearth risked being destroyed just because the Shadow attacked aggressively, taking advantage of all the evil available at the time. Some heroes managed to banish it, and the world returned to the usual evil. When the Shadow came for the second time, and was bannished for a second time, the people realized that the Shadow needed evil for his purposes , and established the Principle of Good.
Now, it is true that there are different philosophies about the Good (Lawful, Neutral and Chaotic). There is also this nomadic people who while not indulging in evil acts without reason, give no importance to the Principle. But the Principle of Good is universally known to all, and no one would do an evil act, never mind for its own sake. (For evil acts I mean the most serious crimes. Stealing, defraud or deceive someone, if they have no serious consequences, are not considered "evil" by Terrearthians, although they are still punishable by law) | **Invent a new religion!**
I'm not joking. The world you have described is very very very black and white: literally "everything is Good, except the shadow, which is Evil." This limits the amount of color you can put in your story.
Your shadow needs a weakness. In particular, here is a quad chart showing what happens when you mix good and evil
```
Good Evil
+------+-------+
Good | Good | Evil |
+------+-------+
Evil | Evil | Evil |
+------+-------+
```
As you can see, by your description of "once the shadow infects an area, it becomes nothing" is an indomitable ability. That claim needs to be broken down in order to have Good ever stand a chance.
One bright solution is to bring in Chaos. Make the effect of mixing good and evil less predictable. If you mix black paint into white paint thoughtfully, it looks grey or black (depending on how much black you used). However, in the moments of mixing, you see swirls of black and swirls of white, unmixed. It is not unfathomable that after mixing Good and Evil, some swirls of Good remain, they're just hard to spot.
This forms the backdrop for what you really need: a new religion of balance. You intentionally have set up the Shadow to be ridiculously strong, so it will be hard for you to sell to your readers the idea that somehow humanity magically turns it back with a perfect plan. We're going to need something murkier.
Consider a new caste of individuals who are comfortable with a balance of Good and Evil, rather than merely worshiping Good. They can live off of the borders between them. These individuals would be able to see shades of grey, not just black and white. This ability would give them the ability to penetrate into the Evil Shadow for quite some time before losing their balance and being corrupted absolutely. If they could find the "core" of the Shadow, and instil one dollop of good in the center, it could weaken the shadow dramatically.
This would also generate political drama. The forces of Good could never appreciate what Those Who See Grey think, but they also would recognize that these individuals are the key to survival. The frustration of a perfectly good King having to trust a Grey individual would be palpable.
But the shadow would also seek out these Greys. They are not necessarily harder to corrupt or easier, just different. When corrupting good, the shadow must patiently wait in the dark, and strike when Good's defenses are down. With the Greys, it would be more of a continuous press, slowly trying to gain a foothold in their mind by making the Grey confused as to what is the Shadow, and what is the Grey itself (a confusion that is easier to have when Grey than Good).
---
As a possible source of this new Grey caste, consider the effects of an imperfect strike from Good onto Evil, or an imperfect corruption of Good by Evil. Both could create a mix which could create a sense of Grey. After all, The Shadow better make a mistake somewhere, or it really is too powerful of an opponent. |
8,823 | <p>Maybe this has been asked with another name, but I didn't find it.</p>
<p>1) Are planets in the same altitude level?</p>
<p>2) What defines altitude in the space (universe)?</p>
<p>3) Is the universe a XYZ plane?</p>
<p>4) What keeps planets from orbit the sun in a 45º orbit from Earth's perspective?</p>
<p>Ascii graphical example:</p>
<pre><code> +----------------------+
| |
| |
| SUN |
| |
| |
| |
| |
| |
| |
+----------------------+
+-------+ +----------+
| | | VENUS|
| EARTH | | |
| | | |
+-------+ +----------+
+------------+
| MARS |
| |
| |
</code></pre>
<p>This tries to be a horizontal look.</p>
| [
{
"answer_id": 8824,
"author": "JohnP",
"author_id": 5260,
"author_profile": "https://worldbuilding.stackexchange.com/users/5260",
"pm_score": 4,
"selected": true,
"text": "<p>It has to do with how the planets were formed, as the gas cloud that surrounded the sun coalesced when it was a ... | 2015/01/16 | [
"https://worldbuilding.stackexchange.com/questions/8823",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/6522/"
] | Maybe this has been asked with another name, but I didn't find it.
1) Are planets in the same altitude level?
2) What defines altitude in the space (universe)?
3) Is the universe a XYZ plane?
4) What keeps planets from orbit the sun in a 45º orbit from Earth's perspective?
Ascii graphical example:
```
+----------------------+
| |
| |
| SUN |
| |
| |
| |
| |
| |
| |
+----------------------+
+-------+ +----------+
| | | VENUS|
| EARTH | | |
| | | |
+-------+ +----------+
+------------+
| MARS |
| |
| |
```
This tries to be a horizontal look. | It has to do with how the planets were formed, as the gas cloud that surrounded the sun coalesced when it was a protostar.
It is explained rather well here:
<https://astronomy.stackexchange.com/questions/130/why-do-the-planets-in-our-solar-system-orbit-in-the-same-plane>
A protoplanetary disc is a rotating disc of gas surrounding a newly formed star. When the star is forming out of a molecular cloud, as it condenses it averages out random motion of the gas in favor of the net angular momentum of the nebula.
Conservation of angular momentum causes the ball of gas that formed the protostar to flatten out and take the shape of a disc (like a ball of pizza dough becoming a flat shape when spun, it flattens and spreads out). |
9,837 | <p>There are plenty of high tech gases that humans have weaponised to give advantages not only in <a href="http://en.wikipedia.org/wiki/Chemical_weapons_in_World_War_I" rel="nofollow">wars</a>, but in <a href="http://en.wikipedia.org/wiki/Pepper_spray" rel="nofollow">close combat</a> (not <em>really</em> a gas, I know) and <a href="http://en.wikipedia.org/wiki/Tear_gas" rel="nofollow">riot control</a>, just to name a few uses. </p>
<p>All of the weaponised gas (and gas-like) compounds that I know of are primarily based on chemical reactions, or, as a better way to put it, the attributes of the gas itself. They are used to blind, harm, or kill, among other peculiar methods of weaponisation.</p>
<p>But what about using air pressure? Would it be possible to raise the pressure in a house, so that the air, trying to escape, blasts out the windows? If so, how would this be done? If not, how might something equivalent be accomplished?</p>
<p>There are no restrictions on technology, but size needs to be kept minimal. This should be just as useful as a frag grenade, in the sense that it is deadly but small enough to be handheld. I get a funny feeling that someone will come up with something that demands FTL technology. So yes, FTL is allowed.</p>
<p>I was thinking something along the lines of a small canister that has the capability to compress air (a lot of it), when it is activated. A soldier could crack it out, take some readily available air, make it into a solid (pretty far fetched) and then release when ready. The only problem being... It wouldn't work. So... </p>
<h3> How might local air pressure be weaponised? </h3>
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"text": "<p>This already exists (although not exactly the way you described it). It is called a <a href=\"http://en... | 2015/02/07 | [
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All of the weaponised gas (and gas-like) compounds that I know of are primarily based on chemical reactions, or, as a better way to put it, the attributes of the gas itself. They are used to blind, harm, or kill, among other peculiar methods of weaponisation.
But what about using air pressure? Would it be possible to raise the pressure in a house, so that the air, trying to escape, blasts out the windows? If so, how would this be done? If not, how might something equivalent be accomplished?
There are no restrictions on technology, but size needs to be kept minimal. This should be just as useful as a frag grenade, in the sense that it is deadly but small enough to be handheld. I get a funny feeling that someone will come up with something that demands FTL technology. So yes, FTL is allowed.
I was thinking something along the lines of a small canister that has the capability to compress air (a lot of it), when it is activated. A soldier could crack it out, take some readily available air, make it into a solid (pretty far fetched) and then release when ready. The only problem being... It wouldn't work. So...
### How might local air pressure be weaponised? | Such weapons exist and are called thermobaric bombs. They do rely on chemical reactions to trigger the overpressure blast though. Oh, and it doesn't blast out just the windows, the walls too... Sorry about that.
A thermobaric explosive works by having the initial blast spread fuel in the targeted area, and then a secondary charge ignites the cloud. This achieves a longer burn and much higher temperatures than a regular plastic explosive. In doing do the high temperatures end up creating a devastating overpressure wave that does most of the damage. This is particularly effective in closed areas such as caves, bunkers or buildings. How does this work? Well, the easiest clue is the ideal gas law:
```
pV=nRT
p is pressure
V is volume
n is the number of moles
R is the universal gas constant
T is temperature (K)
```
So higher temperature, ceteris paribus, yields higher pressure. A regular explosion has an overpressure wave too, it's very sharp but very short. For a thermobaric weapon, the pressure builds, builds, and just doesn't stop, until much, much later. It's a bit like the difference between getting punched and a very close encounter with a 300lbs lineman. See a Chinese weapon in action:
Jane's dryly describes it thus:
>
> Its effectiveness against buildings, bunkers is noted, as well as the
> fact that because the blast takes oxygen from the air, personnel in
> the airtight space suffocates because of the oxygen deficit.
>
>
>
These weapons were initially developed by the Soviets, who developed man-portable versions such as the [*РПО-А Шмель*](http://en.wikipedia.org/wiki/RPO-A_Shmel) `RPO-A Shmel` and the *ТОС-1 - тяжёлая огнемётная система* `TOS-1 Heavy Flamethrower "Buratino"` missile launcher. These were used by the Russians to level Grozny in 1999.
 |
12,043 | <p>News media showcase any number of potentially depressing events around the globe - internecine conflicts, ethnic conflicts, catastrophes and what-not.</p>
<p>The corollary constitute fiction as depicted by <a href="http://en.wikipedia.org/wiki/Clarke's_three_laws" rel="nofollow noreferrer">Arthur Clarke</a> who writes to say </p>
<pre><code>Any sufficiently advanced technology is indistinguishable from magic
</code></pre>
<p>Say, civilization is redeemably stripped of two core contemporary technologies - electricity & electronics - abruptly (meaning over a span of a decade). I use the word <em>redeemably</em> here to indicate the technologies mentioned are simply unavailable to the civilization until some <strong>unknown</strong> future date. </p>
<p>E.g. </p>
<ul>
<li>Global ocean levels rise so high as to inundate all ground where a turbine may be installed </li>
<li>The crew/colonials aboard an interstellar colony ship (as depicted in Heinlein's "Orphans of the Sky") suffer loss of focus</li>
</ul>
<p>(+: Takes a stretch of imagination, I know)</p>
<p>Some of the consequences may be as follows:</p>
<ul>
<li>An equally abrupt fall in life expectancy</li>
<li>A gradual decline in the quality of education - specifically pertinent to the 'lost' technologies</li>
<li>A similarly gradual 'return' to provincialism as means to communicate (using the word 'communicate' in it's broad sense to include high-speed long-distance transport as well) disappeared</li>
</ul>
<p>The second item on the list holds my curiosity. Initially (perhaps upto a generation) there could be some people who would know of electricity/electronics, and also be able to discuss the techniques/technology. Over time I would expect this ball of knowledge to dwindle & stagnate.</p>
<p>How long (read: how many generations) would it be before the knowledge of the 'disused'/'unavailable' technologies were lost out of ignorance as to reduce the technologies to metaphor in folklore?</p>
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"text": "<p><a href=\"http://en.wikipedia.org/wiki/Mad_Max\">Mad Max</a> was based in the \"not-too-distant\" future, and I t... | 2015/03/16 | [
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The corollary constitute fiction as depicted by [Arthur Clarke](http://en.wikipedia.org/wiki/Clarke's_three_laws) who writes to say
```
Any sufficiently advanced technology is indistinguishable from magic
```
Say, civilization is redeemably stripped of two core contemporary technologies - electricity & electronics - abruptly (meaning over a span of a decade). I use the word *redeemably* here to indicate the technologies mentioned are simply unavailable to the civilization until some **unknown** future date.
E.g.
* Global ocean levels rise so high as to inundate all ground where a turbine may be installed
* The crew/colonials aboard an interstellar colony ship (as depicted in Heinlein's "Orphans of the Sky") suffer loss of focus
(+: Takes a stretch of imagination, I know)
Some of the consequences may be as follows:
* An equally abrupt fall in life expectancy
* A gradual decline in the quality of education - specifically pertinent to the 'lost' technologies
* A similarly gradual 'return' to provincialism as means to communicate (using the word 'communicate' in it's broad sense to include high-speed long-distance transport as well) disappeared
The second item on the list holds my curiosity. Initially (perhaps upto a generation) there could be some people who would know of electricity/electronics, and also be able to discuss the techniques/technology. Over time I would expect this ball of knowledge to dwindle & stagnate.
How long (read: how many generations) would it be before the knowledge of the 'disused'/'unavailable' technologies were lost out of ignorance as to reduce the technologies to metaphor in folklore? | [Mad Max](http://en.wikipedia.org/wiki/Mad_Max) was based in the "not-too-distant" future, and I think they got it right, in the sense that technologies that prove useful are still in the know-how, such as how to ride a motorcycle or fire guns. Ideas like cities and airplanes were painted as the stuff of legends. Of course, it wasn't specified how long in the future, so we're left with a guess.
Though I would argue that only two generations would be sufficient time to arrive at a point such that Mad Max would have been possible. Most people don't know how to build electronics or get a power plant back online. It would only take a generation to lose all this technical knowledge. It would take only one more for what basic knowledge we have to also become lost, and for only technologies that we need to survive to remain.
This is highly speculative of course, but if you think about it, cities are only able to exist due to existing technology. You would see mass chaos in cities if electricity dropped, and shortly thereafter it would become unsustainable. Cities would quickly become abandoned save for a few scavengers. After two generations, most would have burnt down or it would be absent of anything useful for the taking. Future generations would wonder if it were even possible to have so many people living in such small spaces.
So too would be things we take for granted such as computers, telephones, elevators. All of these things without electricity and without knowing how they work would seem like magic if they somehow could get them to work. |
12,370 | <p>I want to find out what's going on in another star system, but I don't want to go there. How feasible is it to just build a big telescope and take a look?</p>
<p>Scenario: Earth does not respond to communications any more, and nobody who enters the system leaves again. Is it physically possible to build a telescope, presumably a multi-part array type thing, at Alpha Centauri that could resolve human-scale objects (anywhere between "people themselves" and "aircraft carrier") and give me some idea of what is going on on-and-around Earth?</p>
<p>I assume the primary obstacle is <em>something something signal diffusion</em> meaning that a clear image of small objects doesn't actually survive the distance, or if this isn't the case, coordinating the movements of the telescope's component satellites over what is presumably a large orbital separation within the Alpha Centauri system.</p>
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"text": "<p>Use <a href=\"http://www.wikipedia.org/wiki/Multiple_Satellite_Imaging\" rel=\"nofollow\">Multiple Satellite Ima... | 2015/03/20 | [
"https://worldbuilding.stackexchange.com/questions/12370",
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Scenario: Earth does not respond to communications any more, and nobody who enters the system leaves again. Is it physically possible to build a telescope, presumably a multi-part array type thing, at Alpha Centauri that could resolve human-scale objects (anywhere between "people themselves" and "aircraft carrier") and give me some idea of what is going on on-and-around Earth?
I assume the primary obstacle is *something something signal diffusion* meaning that a clear image of small objects doesn't actually survive the distance, or if this isn't the case, coordinating the movements of the telescope's component satellites over what is presumably a large orbital separation within the Alpha Centauri system. | Maybe. Probably not people. And not without some incredibly fine control and gobs of computing power. The hard limit is atmospheric conditions on Earth.
---
According to the [Rayleigh criterion](https://en.wikipedia.org/wiki/Imagery_intelligence#Satellite), the resolution of a circular collector is a function of wavelength, diameter and distance.
```
resolution = 1.22 x wavelength x distance / diameter
```
To detect individual humans from above, let's say we want 50 cm resolution. Alpha Centauri is 4.3 light years away. The Earth's atmosphere is pretty transparent to visible light. How big does the mirror have to be?
```
diameter = 1.22 x wavelength x distance / resolution
diameter = 1.22 x ~500nm x 4.3 light years / 50 cm
```
Your telescope has to be [4 light minutes](https://www.wolframalpha.com/input/?i=1.22+*+wavelength+of+visible+light+*+4.3+light+years+%2F+50+cm) in diameter or half the diameter of the orbit of the Earth. Oh dear. That's ok, all is not lost!
Fortunately you don't have to make bigger and bigger mirrors to get the job done. Others have mentioned [multiple array telescope](https://worldbuilding.stackexchange.com/a/12373/760) concepts. It can get weirder.
[SciShow recently did a piece on space telescope concepts](https://www.youtube.com/watch?v=kdo0pqh2PXA) to drastically improve resolution without having to build bigger and bigger mirrors. One is a [giant umbrella](http://www.colorado.edu/news/releases/2015/01/23/new-space-telescope-concept-could-image-objects-far-higher-resolution) which would take advantage of the diffraction of light waves around the edge of an object to focus the light.
The other is to carefully position glitter ... sorry... ["smart dust"](http://www.rit.edu/news/story.php?id=51127) to form a giant mirror in space out of what are essentially tiny reflective pixels. The light pressure from lasers would be used to carefully nudge the particles into position and keep them there.
---
Then you have the problem of focusing a planet going around the Sun at 30 km/s in a elliptical orbit. That means you don't just track it in a straight line, you have to track the curve of the orbit as well. Once you do that, you have to track a person on the surface rotating at 450m/s, again curved. The math isn't that hard, and since you're so far away you have to turn your telescope very little, but the minute and constantly changing motion of your telescope required is extremely difficult to resolve down to a few meters.
This is why we don't point the Hubble at the Earth. [DSCOVR](https://en.wikipedia.org/wiki/DSCOVR), the recently launched telescope we *do* intend to point at the Earth, will sit at the Sun-Earth L1 point 1.5 million km away and is only intended to do atmospheric readings.
Fortunately for our 4 light minute wide space telescope, this is all predictable! Each piece can focus their local element individually without having to communicate with the rest of the telescope. No internal FTL communication required.
---
Atmospheric conditions are your ultimate limiting factor, the problem of atmospheric haze. Even on the clearest day, the atmosphere reflects and diffuses light making your image fuzzy no matter what you do. This is part of the reason we put telescopes in space. But it is [mostly transparent to certain wavelengths](http://earthobservatory.nasa.gov/Features/RemoteSensing/remote_04.php). Visible light is one. Microwaves are much better, but humans and aircraft carriers don't emit microwaves. Also the longer your wavelength (microwaves are pretty long) the lower your resolution.
Scientists have been studying [the problem of how to get good resolution through an atmosphere](https://en.wikipedia.org/wiki/Astronomical_seeing#Overcoming_atmospheric_seeing) for a long time and have come up with some very, very clever ways to overcome the problem. The whole is covered under [adaptive optics](https://en.wikipedia.org/wiki/Adaptive_optics). But that's for looking out from inside the atmosphere. We want to look *in*.
Fortunately we don't have to run the numbers, [we have had spy satellites which can do this since the 60s and 70s](https://en.wikipedia.org/wiki/KH-11_Kennan). They're good enough to see aircraft carriers and people through the atmosphere, a sufficiently large array at Alpha Centauri *probably* is, too. But I don't have the numbers.
The other place to look for information is in speculation about viewing exoplanets.
---
You will be seeing 4.3 years into the past. You might think "great, then I can see whatever caused the Earth to stop communicating years ago", no. Information can only travel at the speed of light, so your information that there is a problem on the Earth would also be 4.3 years old. Even if at the moment you realized there's a problem on Earth you swung your super telescope to look, you'd still have missed the event. Best you can do is see the aftermath.
---
What you can definitely do is gather data to theorize about what happened. For example, if you see a lot of atmospheric dust that could indicate meteor strike or nuclear war. Spectral analysis could tell you if there's a sudden increase in any elements in the atmosphere. Changes in albedo could tell you similar things. Color shifts could tell you if there was a massive plant die off (or if it goes the other way, [Triffid attack](https://en.wikipedia.org/wiki/Triffid)). This is how we make guesses about exoplanets right now, just from a few smudged pixels.
With all that time and effort to get what will probably be a hazy image of what happened 4 years ago (plus time to make and focus the telescope), it might be best to just pack up the family car and take a road trip. Of course by then it will have been at least 8 years. But at least you can pick up souvenirs. |
12,929 | <p>For this question think of the times of past, present, and future as $T_{-1}$,$T_0$, and $T_1$, respectively. There is a man named Jim, currently in $T_0$, so lets refer to him as $J_0$. $J_0$ is a very smart man and at some point between $T_0$ and $T_1$ he invents a time machine. His future self, $J_1$, uses this time machine to travel back in time from $T_1$ to $T_0$. At this point, $J_1$ tells $J_0$ to not build the time machine. This in turn sends the timeline from $T_0$ to $T_{1A}$. However, without the time machine, $J_1$ cannot tell $J_0$ to not build the time machine, therefore creating a paradox.</p>
<p>Here is a visual example:</p>
<p>1 - Normal Timeline with $J_0$ at $T_0$.
<img src="https://i.stack.imgur.com/WsI2L.png" alt="1">
2 - $J_1$ goes back in time to $T_0$ from $T_1$.
<img src="https://i.stack.imgur.com/voVks.png" alt="2">
3 - This creates an alternative timeline starting at $T_0$ to $T_{1A}$.
<img src="https://i.stack.imgur.com/kxOo5.png" alt="3"></p>
<p>Now what happens next? $J_{1A}$ cant go back in time like $J_1$ did because he had no time machine and would have no purpose to do so anyway. Therefore, would the universe reset to the original timeline or will something else happen?</p>
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"text": "<p>I think the established term for this is known as the <a href=\"http://en.wikipedia.org/wiki/Grandfather_paradox... | 2015/03/25 | [
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Here is a visual example:
1 - Normal Timeline with $J\_0$ at $T\_0$.
2 - $J\_1$ goes back in time to $T\_0$ from $T\_1$.
3 - This creates an alternative timeline starting at $T\_0$ to $T\_{1A}$.
Now what happens next? $J\_{1A}$ cant go back in time like $J\_1$ did because he had no time machine and would have no purpose to do so anyway. Therefore, would the universe reset to the original timeline or will something else happen? | If your universe allows time travel to split the timeline into two, I think your choice to splitting it only based on whether the time machine is built is incorrect. The right place to split the timeline is at $T\_{-1}$, just before $J\_1$ arrives in "his" past.
In one branch, at $T\_{0A}$, a $J\_1$ from "the future" appears. In the other branch, at $T\_0$, he does not.
Thus, when $J\_1$ tells a "past version of himself" not to build the time machine, he's really telling $J\_{0A}$, an alternate version of his past self, not $J\_0$.
I quoted some of the phrases above, because of the alternate realities involved. $T\_{0A}$ isn't really $J\_0$'s past, nor is he really from that timeline's future.
Bad ASCII diagram:
```
T-1 ----------------> T0 --------------------------> T1
\ (J0 invents time machine) (J1 uses machine)
\ /
\ .-------- J1's journey <--------
\ V
--------------> T0A -------------------------> T1A
(J0A doesn't invent the machine) (J2 and J1A live happily ever after)
``` |
13,663 | <p>I know the question is rather broad but I hope to find a somewhat general solution. Here is a sample scenario:</p>
<p>Two characters are in a room. One of them starts discussing something private, the other says "Shh, don't you know the walls have ears?" signifying that they could be under surveillance.</p>
<p>How can they communicate in relative safety? Here are my assumptions so far:</p>
<ul>
<li>the setting is of oppressive almost constant surveillance, akin to George Orwell <em>1984</em></li>
<li>the surveillance could be mystical or high tech or simply just guys listening and watching. The exact nature doesn't matter as much, the characters possess similar means. But it's not a matter of hopping to the local supermarket and getting an anti-surveillance kit.</li>
<li>the characters also do not possess any abnormal means of defeating the spying, for example they won't have telepathic communication super secret wireless communication devices embedded in their skulls if these don't exist in the world.</li>
<li>the observation is not absolute. However, the characters do not know what is monitored and how. It can be assumed that simply passing notes is not automatically safe (<em>they</em> could be watching, not just listening) but it could be that it <em>is</em> safe in, some environments. Going by <em>1984</em> again, Winston's methods may have succeeded, not just ruled out to be completely subverted.</li>
<li>the characters need not necessarily know each other, so they don't have an pre-established code or cipher or something. They can certainly do this as things progress but it shouldn't be a given.</li>
</ul>
<p>So, I am looking for how would the characters go about establishing any number of these things </p>
<ul>
<li><em>where</em> is safe or not - if they could at least be fairly sure about either, they might find places to communicate</li>
<li><em>what</em> the nature of the surveillance is - audio, visual, both, maybe others kinds, like wiretaps, or invisible spirits watching a room. </li>
<li><em>how to subvert it</em> - <strong>would probably rely on the above first</strong> as the characters would need to work out a scheme of communication without being spied on. Unless there is a safe way to communicate without establishing the method of communication first.</li>
</ul>
<p>The characters could use ciphers or encryption but note that these could be cracked or compromised, if they establish what the scheme is in a non-safe place. Ideally, I would want the characters to be able to communicate face to face (or at least being in the same place) in some way.</p>
<p>I am interested in how people would go about understanding the limits of prevailing surveillance without too much risk to themselves. </p>
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"text": "<p>In that environment I would just assume that I am always under visual/audio surveillance 100% of the t... | 2015/04/04 | [
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Two characters are in a room. One of them starts discussing something private, the other says "Shh, don't you know the walls have ears?" signifying that they could be under surveillance.
How can they communicate in relative safety? Here are my assumptions so far:
* the setting is of oppressive almost constant surveillance, akin to George Orwell *1984*
* the surveillance could be mystical or high tech or simply just guys listening and watching. The exact nature doesn't matter as much, the characters possess similar means. But it's not a matter of hopping to the local supermarket and getting an anti-surveillance kit.
* the characters also do not possess any abnormal means of defeating the spying, for example they won't have telepathic communication super secret wireless communication devices embedded in their skulls if these don't exist in the world.
* the observation is not absolute. However, the characters do not know what is monitored and how. It can be assumed that simply passing notes is not automatically safe (*they* could be watching, not just listening) but it could be that it *is* safe in, some environments. Going by *1984* again, Winston's methods may have succeeded, not just ruled out to be completely subverted.
* the characters need not necessarily know each other, so they don't have an pre-established code or cipher or something. They can certainly do this as things progress but it shouldn't be a given.
So, I am looking for how would the characters go about establishing any number of these things
* *where* is safe or not - if they could at least be fairly sure about either, they might find places to communicate
* *what* the nature of the surveillance is - audio, visual, both, maybe others kinds, like wiretaps, or invisible spirits watching a room.
* *how to subvert it* - **would probably rely on the above first** as the characters would need to work out a scheme of communication without being spied on. Unless there is a safe way to communicate without establishing the method of communication first.
The characters could use ciphers or encryption but note that these could be cracked or compromised, if they establish what the scheme is in a non-safe place. Ideally, I would want the characters to be able to communicate face to face (or at least being in the same place) in some way.
I am interested in how people would go about understanding the limits of prevailing surveillance without too much risk to themselves. | If you go to the Information Security Exchange you will see over and over again:
```
There is no such thing as perfect security.
```
An adversary with sufficient desire and means will compromise your communication pathway. That is what makes 1984 (and real life big brother states like China) so frightening.
These big brother states are limited by their ability to filter out the normal from the interesting. During the Vietnam War, American POWs were isolated from each other in order to wear them down. The POWs began communicating using everyday sounds. Since everyone in the Hanoi Hilton was sick, the POWs would cough and sneeze in code to pass messages. Chores became means of communicating - the delay between sweeps on a broom could be varied to produce Morse code.
These methods are not fool proof, but they were sufficient for the POWs. A more aggressive "big brother" would have certainly understood every message passed, but the North Vietnamese were distracted by the whole fighting a war thing: they could only devoted so much manpower / time / energy to the POW camp.
So the key to your story will be three-fold:
1) What is normal behavior?
2) How can I modify that behavior to pass information?
3) (most importantly) What limits Big Brother? - with unlimited time and money nothing is secret. |
14,657 | <p>In Harry Potter there is a spell which allows a person to levitate an object at will around a room. In <em>Star Wars</em>, Jedi mind control allows you to do the same thing. I'm surprised that no one has tried to replicate this sort of levitation using magnets: the levitating of a small object at eye level with the ability to control where the object moves. Of course we use magnets to levitate things like Maglev trains, and many children's toys use magnets to make objects float. But levitating an object in a controlled manner several feet above the ground is quite different. </p>
<p>I don't see why this is so hard to accomplish? Suppose we constructed a room with powerful electromagnetics embedded in the walls, floor, and ceiling. We have some metal object which is placed in the room. When the electromagnets are turned on, the object floats several feet above the ground. By manipulating the magnetic field (using a computer), a technician outside the room can control the movement of the object at will. Now, it's easy to see why this particular setup is extremely costly, but I imagine something similar could work?</p>
<p>Ideally, we want a person in the room to control the object himself (not using a computer). Perhaps we can make a glove with powerful magnets embedded in it. The strength of the magnets can be manipulated by closing or opening your hand. </p>
<p>I'm sure this sounds very childish and naive. I haven't considered the relevant physics yet, but I don't see why this would impossible in principle. Whether we can do this cheaply is another story.</p>
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] | In Harry Potter there is a spell which allows a person to levitate an object at will around a room. In *Star Wars*, Jedi mind control allows you to do the same thing. I'm surprised that no one has tried to replicate this sort of levitation using magnets: the levitating of a small object at eye level with the ability to control where the object moves. Of course we use magnets to levitate things like Maglev trains, and many children's toys use magnets to make objects float. But levitating an object in a controlled manner several feet above the ground is quite different.
I don't see why this is so hard to accomplish? Suppose we constructed a room with powerful electromagnetics embedded in the walls, floor, and ceiling. We have some metal object which is placed in the room. When the electromagnets are turned on, the object floats several feet above the ground. By manipulating the magnetic field (using a computer), a technician outside the room can control the movement of the object at will. Now, it's easy to see why this particular setup is extremely costly, but I imagine something similar could work?
Ideally, we want a person in the room to control the object himself (not using a computer). Perhaps we can make a glove with powerful magnets embedded in it. The strength of the magnets can be manipulated by closing or opening your hand.
I'm sure this sounds very childish and naive. I haven't considered the relevant physics yet, but I don't see why this would impossible in principle. Whether we can do this cheaply is another story. | We can, actually
----------------
I recall this little frog being levitated using a (somewhere between 1-100 Tesla) magnetic coil using diamagnetism about a decade or more ago. There he is:
Water is diamagnetic, as are many good conductors. So frogs and more recently, [small mammals](http://adsabs.harvard.edu/abs/2010AdSpR..45..208L), have been levitated.
```
Material χv (× 10−5)
Superconductor −105
Pyrolytic carbon −40.9
Bismuth −16.6
Mercury −2.9
Silver −2.6
Carbon (diamond) −2.1
Lead −1.8
Carbon (graphite) −1.6
Copper −1.0
Water −0.91
```
More relevant to your question, there was a spinning-stabilized toy patented in the 70s and more recently, **there are** commercially available solutions such as the [Levitron](https://www.youtube.com/watch?v=W6SSY7ABJkw) for low weight objects in a limited range.
Heck, you can [build one yourself with a few magnets](https://www.youtube.com/watch?v=VylZJrep1MM). |
14,996 | <p>Suppose humanity (or something like it) lives on a planet where we have discovered the existence of Souls. Each time someone is born, a new soul is created, but this is a maximum number of souls to go around (I’ll put it at about 6.5 billion, which is a number that would easily be supported by this planet) every soul belongs to a “nation” which is the land area that would be considered the “respawn point” for a soul. A soul will cycle between an animal (with human-level intelligence) and a human body. However, the behavior and skills of someone in their human life can influence what they become.</p>
<p>Soul’s new bodies are given a new body by guardians (who can see the most recent life of a soul by looking at it). These guardians can also deny a soul resurrection, but rarely do (usually mass-murderers etc.). Humans emerge at the age of about 16, with the skills and knowledge of their smartest life but the memories of their past two lives. Animal resurrections can be any creature, mythical or real.</p>
<p>There are a few ways to kill a soul for good (though a new soul will be added to the pool of “possible souls”).</p>
<pre><code>Be denied reincarnation by the guardians.
Have the heart of your body eaten by another soul (animal or human) before it's buried
Soulkillium is a metal that can kill a soul, it is very very rare and takes a large quantity in one place to work(3+kg).
Using one's soul to attack someone else's. (Kinda like black star from soul eater.)
</code></pre>
<p>What sort of changes would we see to say classical medieval society. In specific interaction between nations and the whole feudal system. </p>
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Soul’s new bodies are given a new body by guardians (who can see the most recent life of a soul by looking at it). These guardians can also deny a soul resurrection, but rarely do (usually mass-murderers etc.). Humans emerge at the age of about 16, with the skills and knowledge of their smartest life but the memories of their past two lives. Animal resurrections can be any creature, mythical or real.
There are a few ways to kill a soul for good (though a new soul will be added to the pool of “possible souls”).
```
Be denied reincarnation by the guardians.
Have the heart of your body eaten by another soul (animal or human) before it's buried
Soulkillium is a metal that can kill a soul, it is very very rare and takes a large quantity in one place to work(3+kg).
Using one's soul to attack someone else's. (Kinda like black star from soul eater.)
```
What sort of changes would we see to say classical medieval society. In specific interaction between nations and the whole feudal system. | In addition to WhatRoughBeast's answer, people persisting their knowledge through the ages would somewhat negate the need for education systems after a certain period of time. We wouldn't spend time educating our kids much beyond the basics if they suddenly gain smarts at 16 regardless.
On the other hand, it means research projects can be continued throughout the centuries. There would be less of that human urge to do all we could as soon as we could; after all, what's the rush, I can get around to that in my next lifetime.
Even so, ironically, and counterintuitively, these two factors would probably contribute to slowing technological progress (less inclination to combine minds if you can ponder to yourself for centuries, and less inclination to do anything in general if I'm immortal).
Alot of human society is built on the reverence of death. Even in ancient times, death was sacred, and burial was a huge part of civilization. Without that, what do people find sacred instead? Life is less sacred, death is not to be feared. Ancient legends would change immeasurably and the sense of morals would be considerably skewed.
As Mari M mentions, murder is less of sin; and creative torture methods preserving life (i.e. preventing the release of death) are liable to be created along with consistant genocides. If you suddenly remembered your past life at 16, and it was 40 years of vicious torture, imprisonment and rape all flooding your consciousness at once I'd be surprised if we didn't end with a few babbling catatonics from that. *"Kill me again so I can have another 16 years of ignorance, please."* might even become a service... (yikes that got dark).
Soul study (Animatology) would become a big science. If someone can accurately predict where and when and how a soul will reincarnate, the limits and powers of the respawn points, and the related abilities to manipulate them, you gain alot of power.
This is also the best method to become a usurper. If you can predict where the old king comes back to life all the time, simply find him and stab him in the face again before he turns 16. As a bonus, he's now locked as a wolf or whatever for 5-15 years before he becomes a human again if the animal/human cycle is set in stone.
Finally, if souls have this human/animal cycle, then your human population max is actually less than 6.5 billion, right? |
15,225 | <p>Carbon dominates the makeup of life on Earth.</p>
<p>But is there any way that plants could be made out of metals, or somehow integrate metals with their constitution?</p>
<p>For example, we use calcium in our bones, which is an alkaline metal.</p>
<p>Its there any way that a plant might use metals (alkali or otherwise) to strengthen its structure so as to resist strong winds and protect itself from predators?</p>
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"text": "<p>As you stated previously we use calcium in our bones but, given several bone sustenance changes, it would... | 2015/04/26 | [
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But is there any way that plants could be made out of metals, or somehow integrate metals with their constitution?
For example, we use calcium in our bones, which is an alkaline metal.
Its there any way that a plant might use metals (alkali or otherwise) to strengthen its structure so as to resist strong winds and protect itself from predators? | Lets look at some real-world examples of plants which already absorb and use metals, namely [hyperaccumulators](https://en.wikipedia.org/wiki/Hyperaccumulator).
Hyeraccumulators are plants which can withstand extremely high concentrations of metals otherwise toxic to non-hyperaccumulating plants.
They extract metals from the soil and store them within leaves, shoots and their roots. Other plants can also extract metals from soils, but hyperaccumulators can do this at a much, *much* faster rate and are also able to store incredible quantities of these toxic metals within their tissues.
Because of this extraction of metals, hyperaccumulators are commonly used in [phytomining](http://www.bbc.co.uk/schools/gcsebitesize/science/aqa/metalsanduses/extractingmetalsrev5.shtml), where we use such plants to take minerals out of the soil for us.
Of course, hyperaccumulators absorb many metals, not just the ones valuable to humans.
Because of the toxicity of the metals which are absorbed by hyperaccumulating plants, scientists speculate that the primary purpose of hyperaccumulation, at least, the primary defensive purpose, is to prevent them from being eaten. The concentration of toxic metals within these plants is so high that animals which eat them will die, and so never be found eating them again.
So, here on Earth, hyperaccumulators only pad their tissues with toxic metals to decrease the likelihood of their being eaten, but you've stated specific interest in using metals to improve structure, rigidity and strength.
However, if a plant were able to pull metals from the ground like a hyperaccumulator, there's no reason those metals couldn't then be used to strengthen the plant.
First, let's have a look at which metals hyperaccumulators are known to handle:
```
Name Symbol UTS tensile strength
Aluminium Al 700
Silver Ag 170
Arsenic As 3
Beryllium Be 448
Chromium Cr 689
Copper Cu 220
Manganese Mn -
Mercury Hg -
Molybdenum Mo 690 Disclaimer:
Lead Pb 17 I am pretty certain that the
Palladium Pd 325 listed tensile strengths are
Platinum Pt 240 inaccurate and inconsistent.
Selenium Se 500 They should be used just as a
Zinc Zn 28 rough idea of the actual
strengths.
```
From this list, two metals stand out; Aluminium and Chromium.
Both incredibly strong metals; this is the same Aluminium used in [skyscrapers and jet engines](http://www.riotintoalcan.com/ENG/ourproducts/1542_aluminium_and_its_uses.asp), and the same chromium as used in [Chrome plating](https://en.wikipedia.org/wiki/Chrome_plating).
If your plants were to hyperaccumulate large enough quantities of these metals, they could capitalise on their strength in many ways. Some examples I thought of were:
* Reinforcing cell-walls by chrome plating. Currently, plant cell walls are made almost entirely from [cellulose](https://en.wikipedia.org/wiki/Cellulose), which is (compared to chromium) very weak. By reinforcing this cellulose with chromium, individual cells of your plant would become nigh-indestructable.
* Building skeletal systems. Along with the [Phloem](https://en.wikipedia.org/wiki/Phloem) and [Xylem](https://en.wikipedia.org/wiki/Xylem) of current plants, metal plants might have a third system of vessels, filled with Aluminium, keeping the plant structurally sound. Good luck snapping a twig laced with one of the toughest metals of which we know.
* Plating the entire plant. If the plant's [epidermis](http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/L/Leaf.html) were to secrete chromium instead of wax, it could build up a thick layer of chrome plating, which cannot be scratched, corroded or otherwise damaged.
Of course, now that you have the ability to absorb minerals and metals from the ground, you can use them however you want! |
15,231 | <p>For this question, we'll assume that <strong>life on Earth was brought by aliens</strong>. They didn't do anything specific to our planet: they saw that it was compatible with the lifeform they wanted to seed, so they just got down and put life on Earth.</p>
<p>What did this <em>form of life</em> look like?</p>
<p>I want to assume that they dropped the <strong>most evolved lifeform possible</strong>, without denying any of today's science. Fossils and other proofs of the earliest stages of life on Earth must be taken into account in your question. But see that in this question, everything that we have no scientific proof was physically on earth at some point needn't have been.</p>
<p>Also these aliens dropped <strong>one and only one form of life</strong>, many specimens if need be. If the alternative is fun, you can include in your response a scenario where they dropped more than one lifeform, but this is not the main purpose of this question.</p>
<p>Bonus: <em>how long ago was this?</em></p>
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What did this *form of life* look like?
I want to assume that they dropped the **most evolved lifeform possible**, without denying any of today's science. Fossils and other proofs of the earliest stages of life on Earth must be taken into account in your question. But see that in this question, everything that we have no scientific proof was physically on earth at some point needn't have been.
Also these aliens dropped **one and only one form of life**, many specimens if need be. If the alternative is fun, you can include in your response a scenario where they dropped more than one lifeform, but this is not the main purpose of this question.
Bonus: *how long ago was this?* | Lets look at some real-world examples of plants which already absorb and use metals, namely [hyperaccumulators](https://en.wikipedia.org/wiki/Hyperaccumulator).
Hyeraccumulators are plants which can withstand extremely high concentrations of metals otherwise toxic to non-hyperaccumulating plants.
They extract metals from the soil and store them within leaves, shoots and their roots. Other plants can also extract metals from soils, but hyperaccumulators can do this at a much, *much* faster rate and are also able to store incredible quantities of these toxic metals within their tissues.
Because of this extraction of metals, hyperaccumulators are commonly used in [phytomining](http://www.bbc.co.uk/schools/gcsebitesize/science/aqa/metalsanduses/extractingmetalsrev5.shtml), where we use such plants to take minerals out of the soil for us.
Of course, hyperaccumulators absorb many metals, not just the ones valuable to humans.
Because of the toxicity of the metals which are absorbed by hyperaccumulating plants, scientists speculate that the primary purpose of hyperaccumulation, at least, the primary defensive purpose, is to prevent them from being eaten. The concentration of toxic metals within these plants is so high that animals which eat them will die, and so never be found eating them again.
So, here on Earth, hyperaccumulators only pad their tissues with toxic metals to decrease the likelihood of their being eaten, but you've stated specific interest in using metals to improve structure, rigidity and strength.
However, if a plant were able to pull metals from the ground like a hyperaccumulator, there's no reason those metals couldn't then be used to strengthen the plant.
First, let's have a look at which metals hyperaccumulators are known to handle:
```
Name Symbol UTS tensile strength
Aluminium Al 700
Silver Ag 170
Arsenic As 3
Beryllium Be 448
Chromium Cr 689
Copper Cu 220
Manganese Mn -
Mercury Hg -
Molybdenum Mo 690 Disclaimer:
Lead Pb 17 I am pretty certain that the
Palladium Pd 325 listed tensile strengths are
Platinum Pt 240 inaccurate and inconsistent.
Selenium Se 500 They should be used just as a
Zinc Zn 28 rough idea of the actual
strengths.
```
From this list, two metals stand out; Aluminium and Chromium.
Both incredibly strong metals; this is the same Aluminium used in [skyscrapers and jet engines](http://www.riotintoalcan.com/ENG/ourproducts/1542_aluminium_and_its_uses.asp), and the same chromium as used in [Chrome plating](https://en.wikipedia.org/wiki/Chrome_plating).
If your plants were to hyperaccumulate large enough quantities of these metals, they could capitalise on their strength in many ways. Some examples I thought of were:
* Reinforcing cell-walls by chrome plating. Currently, plant cell walls are made almost entirely from [cellulose](https://en.wikipedia.org/wiki/Cellulose), which is (compared to chromium) very weak. By reinforcing this cellulose with chromium, individual cells of your plant would become nigh-indestructable.
* Building skeletal systems. Along with the [Phloem](https://en.wikipedia.org/wiki/Phloem) and [Xylem](https://en.wikipedia.org/wiki/Xylem) of current plants, metal plants might have a third system of vessels, filled with Aluminium, keeping the plant structurally sound. Good luck snapping a twig laced with one of the toughest metals of which we know.
* Plating the entire plant. If the plant's [epidermis](http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/L/Leaf.html) were to secrete chromium instead of wax, it could build up a thick layer of chrome plating, which cannot be scratched, corroded or otherwise damaged.
Of course, now that you have the ability to absorb minerals and metals from the ground, you can use them however you want! |
15,263 | <p>For the sake of the question, assume conditions are Earth-like in all manners other than those which would be required to spur the development of such a plant. I want the plant to gestate in the digestive tract and slowly kill the 'infected' by sucking the nutrients from them (like a tape worm). When said person dies the plant uses his/her body as compost to support growth and development.</p>
<ul>
<li><p>How would such a plant evolve (is there any precedent)?</p></li>
<li><p>How would it work (besides the basics I laid out for you)</p></li>
<li><p>Is this realistic for a story?</p></li>
</ul>
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* How would such a plant evolve (is there any precedent)?
* How would it work (besides the basics I laid out for you)
* Is this realistic for a story? | The biggest problem is that you want the plant to thrive in two very different environments (relatively speaking):
```
Body Ground
Temperature Hot Cold
Moisture Wet Dry
Respiration Liquid Air
Nutrients Bloodborne Soil/compost
Energy Glucose Photosynthesis
```
Therefore, for this to work, you really need to have a two stage lifespan. Similar to a caterpillar that meta-morphs into a butterfly, your plant will likely have to transition from thriving in one environment to another.
The seed, therefore must be inhaled, consumed, or embedded somehow. Natural processes suggest inhalation or ingestion as the most successful route. While I'd prefer inhalation (close to bloodstream and air, not as harsh as digestive), it appears you've already selected digestive.
So the seed has to not only survive the digestive tract, but the plant has to provide some enticement to being eaten. If it were inhalation, it wouldn't have to entice - it would merely send out spores or microscopic airborne seeds when jostled. The plant, therefore, provides significant satisfying nutrition, so as to get hosts to eat it.
Once consumed, the seed has to pass through the upper digestive tract, but get stuck in the lower digestive tract (lower acidity). This seems difficult, but perhaps it has a germination time of 1-2 hours once the outer acid protective surface is cleaned off. It then starts rooting in several directions, preventing it from moving further down the digestive tract. Small barbed roots that can absorb nutrients from the partially digested food would be best.
At this time it just absorbs energy that will be used during its transition, and builds into a tumor, with longer and longer roots. Eventually it will completely obstruct the digestive tract or the roots will pierce too many blood vessels or veins, and the host will die. If it's necessary that the host doesn't feel pain until near death, then it either synthesizes anesthetic which it emits through its roots, or it doesn't send out roots and instead merely becomes a digestive obstruction.
When the host dies, the process of decomposition sends chemical signals to the seedling and within a few hours it is expending energy sending a tendril upward (any way could be up at this point, but gravity leads the way) seeking light. Once light is obtained, the plant sends out leaves, roots itself more firmly to the host and ground below, and, eventually, flowers and fruits to catch another host for its offspring.
Pulling off the metamorphosis is the tricky part, but since we have animal analogs that do this, it shouldn't be too difficult to explain to the audience. |
15,282 | <p>Is there a way to create a nuclear explosion that only destroys things within a few feet of the bomb?</p>
<p>The point is to completely eradicate something relatively small, leaving no trace. Let's assume that this is taking place on Earth. The government that is using this procedure has access to lots of funds, so cost isn't a problem.</p>
<p>I'm imagining that the explosion would have to be done using a tiny bomb with only a little bit of fission/fusion (i have no idea) in a controlled and protected environment, to prevent both the impact and nuclear radiation from leaking out and harming the surrounding people and environment.</p>
<p>How would someone go about doing this?</p>
<p>(See <a href="http://meta.worldbuilding.stackexchange.com/questions/1978/should-we-be-mindful-of-potentially-dangerous-questions">Should we be mindful of potentially dangerous questions?</a> on meta.)</p>
<p>If this can't be done using a nuclear explosion, another method of near-total destruction of a contained area would be a valid answer.</p>
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The point is to completely eradicate something relatively small, leaving no trace. Let's assume that this is taking place on Earth. The government that is using this procedure has access to lots of funds, so cost isn't a problem.
I'm imagining that the explosion would have to be done using a tiny bomb with only a little bit of fission/fusion (i have no idea) in a controlled and protected environment, to prevent both the impact and nuclear radiation from leaking out and harming the surrounding people and environment.
How would someone go about doing this?
(See [Should we be mindful of potentially dangerous questions?](http://meta.worldbuilding.stackexchange.com/questions/1978/should-we-be-mindful-of-potentially-dangerous-questions) on meta.)
If this can't be done using a nuclear explosion, another method of near-total destruction of a contained area would be a valid answer. | Continuing on the theme of chemical solutions (ba-dum-bum-CHING - I'm here all night folks)...
One way to rid yourself of unwanted objects or personnel is to liquefy or vaporize them and allow nature to clear them away. For this sort of operation, I eschew explosions because although they deliver a lot of energy, they tend to apply it indiscriminately to everything around them.
So let's try a more focused approach: thermite
Grind up metallic aluminum and rust into a fine dust. Perhaps combine them with a combustible binder material and apply liberally to the object (person) that absolutely, positively has to go away.
```
Size of thing to be destroyed? Unknown
Composition of thing to be destroyed? Non-refractory materials
Level of destruction? Burn, liquify, or vaporize
Proximity to nearby objects? a couple of feet
How affects nearby things? Don't hurt things beyond a couple of feet
How much time? Seconds to minutes
```
Thermite burns at temperatures of thousands of degrees. It will burn, liquefy, or vaporize many materials as shown in this video of thermite on dry ice:
[Thermite Vs. Dry Ice](https://www.youtube.com/watch?v=14EMPjfSmVs)
It won't have this effect on most refractory materials (tungsten, carbon-carbon, etc.).
**Bad Stuff**
While thermite most certainly will rid you of some offensive materials, unless you are extremely liberal and careful with its application there almost certainly will be evidence left. |
15,617 | <p>I've always had trouble with inventing names. They refuse to come, or when they do, they sound funny or cheesy. However, a name will occasionally pop into my head, fully formed and sounding perfect. The only problem is that all of the names I think up sound similar. </p>
<p>For example, I am developing a fantasy world. I have elves, dwarves, and other races of my own creation. I want all the names of one race to be similar to each other (elves are soft, dwarves are guttural, etc.) , but at the same time, they need to be different enough within the same species so that readers won't confuse them. </p>
<p><strong>How can I accomplish this?</strong> </p>
<p>Examples: </p>
<p>For elves, I've found that names ending with 'ir' or 'mir' work well, as well as names ending with 'in'. This is fine as far as it goes. But <em>all I can think of</em> are names that end like that, and some of them are too similar for readers to distinguish at first. How can I keep the names similar, yet different? </p>
<p>EDIT: The answer I found the most helpful, was the answer to the question linked to by James in the comments below. </p>
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"selected": false,
"text": "<p>One trick is to not use all the letters. For elves, you might limit vowels to i and e, and consonants to n, r... | 2015/05/04 | [
"https://worldbuilding.stackexchange.com/questions/15617",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/6620/"
] | I've always had trouble with inventing names. They refuse to come, or when they do, they sound funny or cheesy. However, a name will occasionally pop into my head, fully formed and sounding perfect. The only problem is that all of the names I think up sound similar.
For example, I am developing a fantasy world. I have elves, dwarves, and other races of my own creation. I want all the names of one race to be similar to each other (elves are soft, dwarves are guttural, etc.) , but at the same time, they need to be different enough within the same species so that readers won't confuse them.
**How can I accomplish this?**
Examples:
For elves, I've found that names ending with 'ir' or 'mir' work well, as well as names ending with 'in'. This is fine as far as it goes. But *all I can think of* are names that end like that, and some of them are too similar for readers to distinguish at first. How can I keep the names similar, yet different?
EDIT: The answer I found the most helpful, was the answer to the question linked to by James in the comments below. | One trick is to not use all the letters. For elves, you might limit vowels to i and e, and consonants to n, r, b, m, l, and other 'soft' sounds, while dwarves could use u and o, and d, k, l, r, t, g, x, etc. There are a lot of letters like n and m that work for about any type of name, and different types are defined by inclusion or exclusion of just a few letters.
Or you can let your computer do the hard work for you. I myself use a Python script to generate pronounceable random words suitable for names:
```
def word(syl,p1,p2,con,vow):
w=''
for s in range(syl):
syllable=''
if random.random()<=p1:
syllable=syllable+random.choice(con)
syllable=syllable+random.choice(vow)
if random.random()<=p2:
syllable=syllable+random.choice(con)
w=w+syllable
return w
```
Just type `import random` first. `syl` is the number of syllables, `p1` and `p2` are the probabilities of consonants on each end of the syllable, `con` and `vow` are list of consonants and vowels. There's probably a cleaner way to do this, codewise, but it works well. By tweaking the probabilities, I can usually get one in four of these random words to be usable names (YMMV) and many more just require simple tweaks like substituting a letter.
For suffixes, you can put `+random.choice([list of suffixes])` after the function. I find this is good for place names with suffixes like 'bury', 'ton', etc. but it could work well for names too. |
17,298 | <p>Lets assume that intelligent extraterrestrials visited earth and gave a human a gift of allowing him/her to ask one question and just one. These beings come from far away, humans can't see their ships and don't know they exist and that they are already here.</p>
<p>You know this because you are the human that randomly was selected to receive that gift, you will not be able to see them nor hear their voices you can only write your question and they will look at it from the sky, you can leave it on an outdoor space, laying on the street. They will answer sending you a letter by mail.</p>
<p>The first condition is that you can only ask questions about them, the second condition is that you can't ask questions about the universe or how they got here or what are their intentions. You are allowed to ask about them and only them, the third condition is that you can't tell anyone about this and that you have one hour to ask. if any of these conditions are not met they wont answer you back. </p>
<p>The interesting part is that they will judge human kind with your question, that's why they chose a random average human, if your question makes sense for them they might make themselves appear so that all the world can see and know they do exist. They will always know if you are asking a question because you really want to know or just because you want to make the human kind seem better to them, so keep the answer true to yourself, something that you really want to know about them.</p>
<pre><code>What would your question be and why?
</code></pre>
<p>I made this scenario because I wanted to know how many people would ask for help
and how many would complicate a simple question.</p>
| [
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"selected": true,
"text": "<p>\"What could possibly make you think this is a good way to judge a species?\"</p>\n\n<p>Because really, coming a... | 2015/05/15 | [
"https://worldbuilding.stackexchange.com/questions/17298",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/9644/"
] | Lets assume that intelligent extraterrestrials visited earth and gave a human a gift of allowing him/her to ask one question and just one. These beings come from far away, humans can't see their ships and don't know they exist and that they are already here.
You know this because you are the human that randomly was selected to receive that gift, you will not be able to see them nor hear their voices you can only write your question and they will look at it from the sky, you can leave it on an outdoor space, laying on the street. They will answer sending you a letter by mail.
The first condition is that you can only ask questions about them, the second condition is that you can't ask questions about the universe or how they got here or what are their intentions. You are allowed to ask about them and only them, the third condition is that you can't tell anyone about this and that you have one hour to ask. if any of these conditions are not met they wont answer you back.
The interesting part is that they will judge human kind with your question, that's why they chose a random average human, if your question makes sense for them they might make themselves appear so that all the world can see and know they do exist. They will always know if you are asking a question because you really want to know or just because you want to make the human kind seem better to them, so keep the answer true to yourself, something that you really want to know about them.
```
What would your question be and why?
```
I made this scenario because I wanted to know how many people would ask for help
and how many would complicate a simple question. | "What could possibly make you think this is a good way to judge a species?"
Because really, coming all the way here to ask a *single, random person* to come up with a question in under an hour is really a waste of resources and a huge gamble to get anything useful out it. |
19,249 | <p><a href="https://en.wikipedia.org/wiki/Monomolecular_wire" rel="noreferrer">Monomolecular wire</a> weapons are a somewhat common element in science-fiction. </p>
<p>Including in this this <a href="http://www.consortium-horizon.com/wiki/Fichier:EclipsePhaseCoverPanopticon_1500px.png" rel="noreferrer"><em>fantastic</em> image</a> I found while looking into this:
<img src="https://i.stack.imgur.com/Ogj6F.jpg" alt="armored octopus with monomolecular whip fighting dual-dagger-wielding monkey"></p>
<p>Is the only infeasible thing in this image that the octopus would need bones to stand like that, or is the monomolecular whip also not feasible?</p>
<p>Let's assume that we have the ability to construct a monomolecular wire from any real material. That uses up the hand waving allowed for this question. Which material would we use, and how effective would it be for use as a blade or whip? (<em>I have seen blades described as either rigid or a taught wire strung in a open frame. I don't care which one is used.</em>)</p>
<p>To qualify as working or feasible, I'm interested in the wire not breaking while cutting through something of various densities, like a <em>human arm</em>. The effort required to do so, tensile strength, sharpness, etc seem all to factor into that one metric. Limb amputation. Let's call it <em>amputationility</em>.</p>
<p><strong>So, can I cut off an arm with a monomolecular wire made of real materials?</strong></p>
<p>If no real material would work, what minimum properties of a real material would need to be modified and to what value?</p>
<hr>
<p><em>Note: I considered tagging this as hard-science. But given the possible requirement of a fantasy material I've left it off. However, I want answers to be as scientific as possible. An answer of "the material needs very high tensile strength" is not satisfactory, I want to know how high the tensile strength needs to be. Numbers people, show me some numbers.</em> </p>
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"text": "<p>Graphene is what you're looking for. </p>\n\n<p>With a tensile strength of 130000 MPa, it has (IIRC) the highest... | 2015/06/16 | [
"https://worldbuilding.stackexchange.com/questions/19249",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/3202/"
] | [Monomolecular wire](https://en.wikipedia.org/wiki/Monomolecular_wire) weapons are a somewhat common element in science-fiction.
Including in this this [*fantastic* image](http://www.consortium-horizon.com/wiki/Fichier:EclipsePhaseCoverPanopticon_1500px.png) I found while looking into this:
Is the only infeasible thing in this image that the octopus would need bones to stand like that, or is the monomolecular whip also not feasible?
Let's assume that we have the ability to construct a monomolecular wire from any real material. That uses up the hand waving allowed for this question. Which material would we use, and how effective would it be for use as a blade or whip? (*I have seen blades described as either rigid or a taught wire strung in a open frame. I don't care which one is used.*)
To qualify as working or feasible, I'm interested in the wire not breaking while cutting through something of various densities, like a *human arm*. The effort required to do so, tensile strength, sharpness, etc seem all to factor into that one metric. Limb amputation. Let's call it *amputationility*.
**So, can I cut off an arm with a monomolecular wire made of real materials?**
If no real material would work, what minimum properties of a real material would need to be modified and to what value?
---
*Note: I considered tagging this as hard-science. But given the possible requirement of a fantasy material I've left it off. However, I want answers to be as scientific as possible. An answer of "the material needs very high tensile strength" is not satisfactory, I want to know how high the tensile strength needs to be. Numbers people, show me some numbers.* | Graphene is what you're looking for.
With a tensile strength of 130000 MPa, it has (IIRC) the highest tensile strength in the world.
So lets make a wire-thin sword!
I envision it to probably end up looking something like this:
```
>----------------------------------------------<|
||||||| |
L_______________________________________________|
```
where the `-------` represent the blade, and the `<|` the tip that the other end of the blade is connected to, and the `||||>` represents a handle. It's important to note that the wire is being pulled taut by the `<|` piece at the end of the blade. The `L____|` represents a structure similar to that of a hacksaw, in order to hold the wires tightly.
This is a **slashing/chopping** weapon.
How/Why does this work?
The "Graphene wire" is really a **Graphene ribbon**
Graphene itself contains elastic properties, which helps with the above concept of cutting. Even if the Graphene doesn't cut right away, the elasticity will help it to continue cutting as you swing the blade through your target. "Graphene sheets (with thicknesses of between 2 and 8 nm) had spring constants in the region of 1-5 N/m and a Young’s modulus (different to that of three-dimensional graphite) of 0.5 TPa."
Graphene also has amazing shear strength. Shear modulus of graphite was reported to be ~0.44 TPa. To give you some context, the shear strength of a carbon diamond structure is ~93 GPa. 1 TPa is 1000 GPa.
**To answer your question: Yes, you can.**
Unfortunately, because the human body is so variable, I can't find any actual numbers regarding how much force is required to tear off a limb - however, we should note that this blade doesn't apply force the same way a sword does.
A sword cuts and splits the target because it "wedges" it apart. In this case, however, because we have a monomolecular ribbon that's completely flat, we should be able to pass through the entire target (irrelevant of what the target is made of, but assuming you gave it a good chop with no deviation in blade angle) extremely easily, since all we're severing are molecular bonds. Forces at the molecular level are at the pico-Newton level (1pN = $10^{-12}$ N); what we exert on anything using anything at any given time exerts more force than what's required. Here's some more context: One pound of force gives us 43.62 Newtons. Even a toddler could exert one pound of force by accident - so if you gave this thing to a baby and he accidentally swung it through you, good luck.
Thank you to Samuel for pointing out some numbers for me: "the shear strength of the Graphene ribbon is maybe 4200 piconewtons / angstrom, while fibers in the skin, like collagen, have a shear strength of only 5.5 piconewtons / angstrom." These numbers show that along the same area, the ribbon has a shear strength of over 750 times that of collagen.
Skin seems easy to cut though. What about bone? Luckily for us, most of bone's elasticity comes from the collagen in it, which means we cut bone just as easily as we do skin.
For an adult? It cuts anything, and everything, better than warm butter.
Once you finish slicing, the limb will only be held on by suction and surface tension. Any movement, and it simply slides/pops off.
**However, even regarding the above saying that it is possible in theory, this tool is much better suited to a hospital setting requiring quick amputations than a battle situation.**
Strictly speaking, this would work as an amputation device, but would be sorely suited for battle if the opponents also had access to similar weapons. In that scenario, please refer to Ville Neimi's answer (2 to 4th paragraph) regarding why it would suck as a weapon. Note that in normal use, the Graphene should be strong enough to be reused over and over again. The hexagonal structure of the Graphene ribbon means that even if any edge atoms are lost, it doesn't matter - No matter which atoms you lose, you will always have a suitable cutting edge.
---
**References:**
R. R. Nair, M. Sepioni, I-Ling Tsai, O. Lehtinen, J. Keinonen, A. V. Krasheninnikov, T. Thomson, A. K. Geim, I. V. Grigorieva. Spin-half paramagnetism in graphene induced by point defects. Nature Physics, 2012; DOI: 10.1038/nphys2183
<http://www.graphenea.com/pages/graphene-properties#.VYCbRkZ8ork>
<https://en.wikipedia.org/wiki/Graphene#Thermal_conductivity>
<http://poplab.stanford.edu/pdfs/PopVarshneyRoy-GrapheneThermal-MRSbull12.pdf>
<https://web.engr.illinois.edu/~aluru/Journals/APL11.pdf>
<https://en.wikipedia.org/wiki/Bone> |
19,253 | <p>Lake Eyre in Australia has an area of roughly 4,000 square miles, but the basin itself is over 450,000 square miles. If the entire basin were freshwater, how would that affect the Outback's climate?</p>
| [
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"text": "<p>Graphene is what you're looking for. </p>\n\n<p>With a tensile strength of 130000 MPa, it has (IIRC) the highest... | 2015/06/16 | [
"https://worldbuilding.stackexchange.com/questions/19253",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/10274/"
] | Lake Eyre in Australia has an area of roughly 4,000 square miles, but the basin itself is over 450,000 square miles. If the entire basin were freshwater, how would that affect the Outback's climate? | Graphene is what you're looking for.
With a tensile strength of 130000 MPa, it has (IIRC) the highest tensile strength in the world.
So lets make a wire-thin sword!
I envision it to probably end up looking something like this:
```
>----------------------------------------------<|
||||||| |
L_______________________________________________|
```
where the `-------` represent the blade, and the `<|` the tip that the other end of the blade is connected to, and the `||||>` represents a handle. It's important to note that the wire is being pulled taut by the `<|` piece at the end of the blade. The `L____|` represents a structure similar to that of a hacksaw, in order to hold the wires tightly.
This is a **slashing/chopping** weapon.
How/Why does this work?
The "Graphene wire" is really a **Graphene ribbon**
Graphene itself contains elastic properties, which helps with the above concept of cutting. Even if the Graphene doesn't cut right away, the elasticity will help it to continue cutting as you swing the blade through your target. "Graphene sheets (with thicknesses of between 2 and 8 nm) had spring constants in the region of 1-5 N/m and a Young’s modulus (different to that of three-dimensional graphite) of 0.5 TPa."
Graphene also has amazing shear strength. Shear modulus of graphite was reported to be ~0.44 TPa. To give you some context, the shear strength of a carbon diamond structure is ~93 GPa. 1 TPa is 1000 GPa.
**To answer your question: Yes, you can.**
Unfortunately, because the human body is so variable, I can't find any actual numbers regarding how much force is required to tear off a limb - however, we should note that this blade doesn't apply force the same way a sword does.
A sword cuts and splits the target because it "wedges" it apart. In this case, however, because we have a monomolecular ribbon that's completely flat, we should be able to pass through the entire target (irrelevant of what the target is made of, but assuming you gave it a good chop with no deviation in blade angle) extremely easily, since all we're severing are molecular bonds. Forces at the molecular level are at the pico-Newton level (1pN = $10^{-12}$ N); what we exert on anything using anything at any given time exerts more force than what's required. Here's some more context: One pound of force gives us 43.62 Newtons. Even a toddler could exert one pound of force by accident - so if you gave this thing to a baby and he accidentally swung it through you, good luck.
Thank you to Samuel for pointing out some numbers for me: "the shear strength of the Graphene ribbon is maybe 4200 piconewtons / angstrom, while fibers in the skin, like collagen, have a shear strength of only 5.5 piconewtons / angstrom." These numbers show that along the same area, the ribbon has a shear strength of over 750 times that of collagen.
Skin seems easy to cut though. What about bone? Luckily for us, most of bone's elasticity comes from the collagen in it, which means we cut bone just as easily as we do skin.
For an adult? It cuts anything, and everything, better than warm butter.
Once you finish slicing, the limb will only be held on by suction and surface tension. Any movement, and it simply slides/pops off.
**However, even regarding the above saying that it is possible in theory, this tool is much better suited to a hospital setting requiring quick amputations than a battle situation.**
Strictly speaking, this would work as an amputation device, but would be sorely suited for battle if the opponents also had access to similar weapons. In that scenario, please refer to Ville Neimi's answer (2 to 4th paragraph) regarding why it would suck as a weapon. Note that in normal use, the Graphene should be strong enough to be reused over and over again. The hexagonal structure of the Graphene ribbon means that even if any edge atoms are lost, it doesn't matter - No matter which atoms you lose, you will always have a suitable cutting edge.
---
**References:**
R. R. Nair, M. Sepioni, I-Ling Tsai, O. Lehtinen, J. Keinonen, A. V. Krasheninnikov, T. Thomson, A. K. Geim, I. V. Grigorieva. Spin-half paramagnetism in graphene induced by point defects. Nature Physics, 2012; DOI: 10.1038/nphys2183
<http://www.graphenea.com/pages/graphene-properties#.VYCbRkZ8ork>
<https://en.wikipedia.org/wiki/Graphene#Thermal_conductivity>
<http://poplab.stanford.edu/pdfs/PopVarshneyRoy-GrapheneThermal-MRSbull12.pdf>
<https://web.engr.illinois.edu/~aluru/Journals/APL11.pdf>
<https://en.wikipedia.org/wiki/Bone> |
19,503 | <p>In short, <a href="http://interstellarfilm.wikia.com/wiki/Miller_%28planet%29" rel="noreferrer">Miller's Planet</a> is described as a "potential habitable planet" with very massive tidal waves as tall as 4,000 feet. If for some reason, life began in this planet and is destined to evolve to be as smart as Humans, how would they be designing structures that should be built on raging water with usual tsunamis? What would this structures look like? (A graphic representation is a plus)</p>
<p>Note that the lifeforms that would start here will begin without any access to advanced technologies of any aliens.</p>
| [
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"text": "<p>Build INTO the ground - literally.</p>\n\n<p>A normal building would have a problem because of this:</p>\n\n<pr... | 2015/06/22 | [
"https://worldbuilding.stackexchange.com/questions/19503",
"https://worldbuilding.stackexchange.com",
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] | In short, [Miller's Planet](http://interstellarfilm.wikia.com/wiki/Miller_%28planet%29) is described as a "potential habitable planet" with very massive tidal waves as tall as 4,000 feet. If for some reason, life began in this planet and is destined to evolve to be as smart as Humans, how would they be designing structures that should be built on raging water with usual tsunamis? What would this structures look like? (A graphic representation is a plus)
Note that the lifeforms that would start here will begin without any access to advanced technologies of any aliens. | Build INTO the ground - literally.
A normal building would have a problem because of this:
```
|--------| <-
| | Big wave, big problem \\
| | <------------- | | The building has to withstand
| | / \ all the force hitting it
| | / \
| [] | / \
---------------------------------------------------------ground------------------
```
So the solution is simple. Don't get hit. Dig Build like this:
```
<- ------------ "Hey, where's my target?"
\\
| | The waves go over the building - it doesn't matter how big the
<- / \ wave is if it doesn't hit :P
/ \
/ \
-------=-------------------------------------------------ground------------------
| |
| | (Note: the "=" is the entrance hatch to our building)
| |
|________|---- "Gtfo wave, nothing to hit here"
```
In other words, you wouldn't see the buildings. You'd have a lot of entrance hatches on the ground though. |
20,998 | <p>In the world I'm building, the day lasts 9 of their years. This means that they are almost always on the move, living in blimp-like cities and houses. I've been designing these and I am having trouble with the exact ratio for the balloon size to the size of the cargo. What is the sack-to-ship ratio? Weight ratios will work as well.</p>
| [
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"selected": true,
"text": "<p>The net lift for the gases is how much the volume of air they displace weighs, minus the weight of the lifting... | 2015/07/21 | [
"https://worldbuilding.stackexchange.com/questions/20998",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/11049/"
] | In the world I'm building, the day lasts 9 of their years. This means that they are almost always on the move, living in blimp-like cities and houses. I've been designing these and I am having trouble with the exact ratio for the balloon size to the size of the cargo. What is the sack-to-ship ratio? Weight ratios will work as well. | The net lift for the gases is how much the volume of air they displace weighs, minus the weight of the lifting gas itself. The following values are from [this site](http://www.airships.net/helium-hydrogen-airships) and are per 1,000 cubic feet of volume.
```
| Weight of Lifting Gas | Weight of Air | Net Lift
+-----------------------+----------------+------------
Hydrogen | 5.31 lbs | 76.36 lbs | 71.05 lbs
Helium | 10.54 lbs | 76.36 lbs | 65.82 lbs
```
So, if you have 71 lbs of cargo, you need 1,000 cubic feet of hydrogen to lift it. The volume which the cargo takes up is irrelevant.
You'll need more than to just lift cargo, of course, you have to lift the rest of the ship including the gas bag, deck, rigging, etc.
This is assuming the atmosphere is the same density as on Earth. The specific values are with respect to Earth's gravity, but the ratio will remain for any (reasonable) value of gravity.
If your planet isn't populated [exclusively by Americans, Myanmas, or Liberians](https://en.wikipedia.org/wiki/Metric_system#Usage_around_the_world) then they probably use the glorious metric system.
In which case the table looks more like this for a volume of one cubic meter:
```
| Weight of Lifting Gas | Weight of Air | Net Lift
+-----------------------+----------------+------------
Hydrogen | 0.090 kg | 1.292 kg | 1.202 kg
Helium | 0.178 kg | 1.292 kg | 1.114 kg
```
If you got some cargo from a backward country and they said it weighed 71 lbs, once you properly weighed it at 32.2 kgs you would know you need about 26.8 cubic meters of helium to lift it.
In your specific case, if you wanted to lift a typical mobile home [weighing 6758.53 kilograms (14,900 lbs)](http://www.anr.state.vt.us/dec/wastediv/recycling/pubs/trailer.pdf):
$$6\,758.53\ \mathrm{kg} \times {{1\ \mathrm{m^3}} \over {1.114\ \mathrm{kg}}} \approx 6\,070\ \mathrm{m^3} $$
You'd need 6,070 cubic meters (~214,000 cubic feet) of hydrogen. This is about two and a half Olympic swimming pools in volume. Or, more specifically, a sphere 22.6 meters (~74 ft) in diameter (a bit over 8 stories tall). |
21,408 | <p><strong>This Query is part of the Worldbuilding <a href="https://worldbuilding.stackexchange.com/questions/143606/a-list-of-worldbuilding-resources">Resources Article</a>.</strong>
<hr>
Once the geography of the world is designed, it needs a planetary system to inhabit. But how should that solar system look? The only constraint is that the system needs the new world to be placed in a habitable zone for the suspiciously Earth-like creatures that evolved there. By placed, I only mean it's made up, the system needs to have naturally formed in all respects. </p>
<p>The naive solution would be to make it like our planetary system, the Solar System.</p>
<p>That is, arrange it so that the planets orbit the same direction in the ecliptic plane, there are some rocky planets close to the star followed by an asteroid belt and some gas giants, like this: SRRHRAGGG (<em>incidentally, this is the sound the planetary system will make when it dies</em>)</p>
<pre><code>Key:
S- Star
R- Rocky Planet
H- Habitable Planet/Moon
A- Asteroid Belt
G- Gas Giant
</code></pre>
<p>Is this the most likely arrangement, RxAxGx (rocky planet[s], asteroid belt[s], gas giant[s])? Can a massive gas giant be orbiting near the star out of the ecliptic plane? Can the habitable world be alone with some comets and asteroids? </p>
<p><em>The main question:</em></p>
<p><strong>What is the range of planetary configurations I can <em>reasonably</em> expect from a habitable system?</strong></p>
<p><em>Clarifications:</em></p>
<p>I'm interested in the ordering of planets (mass and type), the planet mass to star ratio, number of planets, orbital direction of planets (as in agreement between planets), ecliptic plane confinement, and the reasonable range of these aspects. Reasonable meaning very precisely "not, like, super rare among habitable systems".</p>
<p><em>Restrictions:</em></p>
<p>The system must contain a planet which has evolved Earth-like life.</p>
<p>The system must have been formed by natural processes.</p>
<p><strong>Magic, science fiction, and anecdotes need not apply, this is <a href="/questions/tagged/hard-science" class="post-tag" title="show questions tagged 'hard-science'" rel="tag">hard-science</a>. We don't know much about other systems, let alone explicitly habitable systems, so inductive reasoning is allowed (if not required) but peer-reviewed papers should support any evidence used in that process.</strong></p>
<hr>
<p>Note:</p>
<blockquote>
<p>This is related to a series of questions that tries to break down the process of creating a world from initial creation of the landmass through to erosion, weather patterns, biomes and every other related topics. Please restrict answers to this specific topic rather than branching on into other areas as other subjects will be covered by other questions.</p>
</blockquote>
<hr>
<p>See the other questions in this series here : <a href="https://worldbuilding.meta.stackexchange.com/questions/2594/creating-a-realistic-world-series">Creating a realistic world Series</a></p>
| [
{
"answer_id": 21411,
"author": "HDE 226868",
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"text": "<h2>Ordering of planets (mass and type)</h2>\n<p>Can I start out by jokingly complaining that you picked a rath... | 2015/07/28 | [
"https://worldbuilding.stackexchange.com/questions/21408",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/3202/"
] | **This Query is part of the Worldbuilding [Resources Article](https://worldbuilding.stackexchange.com/questions/143606/a-list-of-worldbuilding-resources).**
---
Once the geography of the world is designed, it needs a planetary system to inhabit. But how should that solar system look? The only constraint is that the system needs the new world to be placed in a habitable zone for the suspiciously Earth-like creatures that evolved there. By placed, I only mean it's made up, the system needs to have naturally formed in all respects.
The naive solution would be to make it like our planetary system, the Solar System.
That is, arrange it so that the planets orbit the same direction in the ecliptic plane, there are some rocky planets close to the star followed by an asteroid belt and some gas giants, like this: SRRHRAGGG (*incidentally, this is the sound the planetary system will make when it dies*)
```
Key:
S- Star
R- Rocky Planet
H- Habitable Planet/Moon
A- Asteroid Belt
G- Gas Giant
```
Is this the most likely arrangement, RxAxGx (rocky planet[s], asteroid belt[s], gas giant[s])? Can a massive gas giant be orbiting near the star out of the ecliptic plane? Can the habitable world be alone with some comets and asteroids?
*The main question:*
**What is the range of planetary configurations I can *reasonably* expect from a habitable system?**
*Clarifications:*
I'm interested in the ordering of planets (mass and type), the planet mass to star ratio, number of planets, orbital direction of planets (as in agreement between planets), ecliptic plane confinement, and the reasonable range of these aspects. Reasonable meaning very precisely "not, like, super rare among habitable systems".
*Restrictions:*
The system must contain a planet which has evolved Earth-like life.
The system must have been formed by natural processes.
**Magic, science fiction, and anecdotes need not apply, this is [hard-science](/questions/tagged/hard-science "show questions tagged 'hard-science'"). We don't know much about other systems, let alone explicitly habitable systems, so inductive reasoning is allowed (if not required) but peer-reviewed papers should support any evidence used in that process.**
---
Note:
>
> This is related to a series of questions that tries to break down the process of creating a world from initial creation of the landmass through to erosion, weather patterns, biomes and every other related topics. Please restrict answers to this specific topic rather than branching on into other areas as other subjects will be covered by other questions.
>
>
>
---
See the other questions in this series here : [Creating a realistic world Series](https://worldbuilding.meta.stackexchange.com/questions/2594/creating-a-realistic-world-series) | Ordering of planets (mass and type)
-----------------------------------
Can I start out by jokingly complaining that you picked a rather complex system? We've found a lot of exoplanets, but there are not many that reside in complex systems like this. This is going to be a tough question. [As Green predicted](https://worldbuilding.stackexchange.com/questions/21408/creating-a-realistic-worlds-map-solar-systems#comment54732_21408), Kepler data is useful here - [Fang & Margo (2012)](http://iopscience.iop.org/0004-637X/761/2/92/pdf/apj_761_2_92.pdf) found that
>
> 75%–80% of planetary systems have one or two planets with orbital periods less than 200 days
>
>
>
They also were able to plot data from a variety of parameters to come up with some graphs that could be used to make distribution curves. You can extrapolate from that, if you wish.
Anyway, I'm off track here. Mass distributions were covered in [Mazeh et al. (1998)](http://iopscience.iop.org/1538-4357/501/2/L199/fulltext/985083.text.html) (which is almost certainly outdated, but a good analysis nonetheless) and [Malhotra (2015)](http://arxiv.org/abs/1502.05011). Using some orbital spacing parameters (which you can adjust, if you want), Malhotra found that the peak value of $\log m/M\_{\oplus}$ occurs at about 0.6-1.0, with a standard deviation of 1.1-1.2. Not the greatest accuracy, but still pretty good.
[Llambay et al. (2011)](http://arxiv.org/abs/1101.3545) were able to come up with a mass-period distribution for exoplanets close to the star, which you can then use to come up with a decent distribution of masses at a given radius:
>
> Most smaller planets have orbital periods longer than P~2.5 days, while higher masses are found down to P~1 day.
>
>
>
In short, more massive planets are closer in, while less massive planets are further out. Still, Llambay et al. only considered planets extremely close to their parent stars. For the rest of the system (i.e. planets farther out), I refer you to [Jiang et al. (2007)](http://iopscience.iop.org/1538-3881/134/5/2061/pdf/1538-3881_134_5_2061.pdf). I can't copy the mass- and period- histograms they gave (relating each one to the total number observed), nor can I copy the scatter plots, but they are incredibly helpful, especially as they considered a sample size of 233 exoplanets.
This graph, complied on [Wikipedia](http://en.wikipedia.org/wiki/File:Exoplanet_Period-Mass_Scatter.png) from [the Open Exoplanet Catalogue](http://www.openexoplanetcatalogue.com/), is also helpful for an at-a-glance reference:
[](https://upload.wikimedia.org/wikipedia/commons/c/cc/Exoplanet_Period-Mass_Scatter.png)
Image in the public domain.
Something you must consider is [planetary migration](http://en.wikipedia.org/wiki/Planetary_migration). I've written several answers on it across Stack Exchange (e.g. [The Solar System Explosion in the Nice Model](https://physics.stackexchange.com/questions/160912/the-solar-system-explosion-in-the-nice-model), [Did Jupiter really make Earth (in)habitable](https://earthscience.stackexchange.com/questions/4595/did-jupiter-really-make-earth-inhabitable), [What gravitational impact would moving Jupiter to the inner solar system have on the outer?](https://worldbuilding.stackexchange.com/questions/12281/what-gravitational-impact-would-moving-jupiter-to-the-inner-solar-system-have-on/12290#12290), etc. - the first focused on only one part, because Kyle Oman was already familiar with the it, hence the question), and others have written excellent answers elsewhere on Stack Exchange. By now, I'm sick and tired of typing the same thing up, so I refer you to the latter two posts I gave, as a starter. You need to include planetary migration because it will severely impact the orbits of the three gas giants in the system. Be careful that you have enough - my answer on Physics discusses just why a certain number is needed.
---
Planet mass to star ratio
-------------------------
No such ratio exists. You can have pretty much any (reasonable) combination you want. It all depends on the [giant molecular cloud](http://en.wikipedia.org/wiki/Molecular_cloud) from which the star formed and the evolution of the [protoplanetary disk](http://en.wikipedia.org/wiki/Protoplanetary_disk). Anything can happen.
---
Number of planets
=================
Fang & Margot are, once again, helpful. [Weissbein et al.](http://arxiv.org/abs/1203.6072?context=astro-ph) are also an excellent resource for this specific part. I once again wish I could figure out directly how to copy graphs and histogram without using imgur - I may use that later - but I can get around that. Unfortunately, they make three assumptions:
1. All planets in a system are exactly aligned
2. All of the stars and planets are identical
3. The Occupancy distribution of a planet existing at a given distance from its stellar host, f(r), is the same for all the stars which are capable of producing planets and is given by equation (1).
The third is not a problem, but the first two are (see my section on ecliptic plane confinement for a discussion on the first). Luckily, as I show later, that criterion can easily be met. The second one is the problem.
Anyway, Weissbein et al. find the probability, $P$, that a star hosts $m$ planets to be
$$P(m)=\int\_0^{\infty}\left[\frac{F(r)^m}{r^2m!}e^{-F(r)}\right]dr$$
where $r$ is radius and
$$F(r)\equiv \int\_0^r f(r')dr'$$
where $f(r')$ is a modified form of the general occupation probability function.
They then used this to create a table of the results, which I will not include at the moment, as I am not good with tables in Stack Exchange. However, predictably, the number of systems went down as the number of planets increased.
---
Ecliptic plane confinement
--------------------------
"Ecliptic plane confinement" can be discussed in terms of [orbital inclination](http://en.wikipedia.org/wiki/Orbital_inclination), generally denoted by $i$. In the case of most systems, this is close to zero degrees for most of the bodies involved (although [Pluto has a high inclination](https://astronomy.stackexchange.com/questions/11360/why-does-pluto-have-a-high-orbital-inclination?lq=1)).
The planets in the Solar System [orbit in one plane](https://astronomy.stackexchange.com/questions/130/why-do-the-planets-in-our-solar-system-orbit-in-the-same-plane?rq=1), because everything formed out of a protoplanetary disk. The planets tend to [stay that way](https://astronomy.stackexchange.com/questions/1095/why-do-the-planets-in-the-solar-system-stay-in-the-same-orbital-plane) because of a conservation of angular momentum. This can change in some cases - notably, [Kepler-452b has a high angle of inclination](https://astronomy.stackexchange.com/questions/11392/how-can-a-planet-have-a-90%c2%b0-inclination) (90 degrees!). As I wrote in my answer there, this may have happened for several reasons:
* The star's rotation axis was perturbed, just as Uranus's rotation axis was perturbed (although by different objects)
* The planet was perturbed by another object, either in the system (e.g. a planetoid) or a companion star. The Sun was formed with many other stars in a cluster; this happens for many stars.
The relevant papers on this subject are [Crida & Batygin (2014)](http://arxiv.org/abs/1405.0960) and [Xue et al. (2014)](http://iopscience.iop.org/0004-637X/784/1/66/pdf/apj_784_1_66.pdf). There are other reasons for the change in orbital inclination of one planet, notably the [Lidov-Kozai mechanism](http://en.wikipedia.org/wiki/Kozai_mechanism) (see [Lidov (1962)](http://www.sciencedirect.com/science/article/pii/0032063362901290) and [Kozai (1962)](http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?1962AJ.....67..591K&data_type=PDF_HIGH&whole_paper=YES&type=PRINTER&filetype=.pdf)). The Lidov-Kozai mechanism basically states that the eccentricity of an object's orbit can be changed by interactions with another (more massive) object, which also changes the orbital eccentricity of the first object. The angular momentum in the $z$-axis must be conserved here; it is the quantity
$$L\_z=\sqrt{1-e^2}\cos i$$
You can play around with this a bit to see what happens when different parameters are changed (you should be able to apply the orbital formulas given [here](https://worldbuilding.stackexchange.com/questions/9944/making-a-planet-habitable-for-humanoids-the-planet)). However, the model assumes that the perturber is much more massive than the perturbed object (Kozai's original analysis applied to perturbations of asteroids by Jupiter!). For larger bodies being perturbed, you would need a larger perturber. This makes it very difficult for planets. This could happen in a binary system where one star is more massive than another star, and the second star perturbs a planet moving around the larger star. It is, however, unlikely, and does not fit your model of one star.
It makes sense that either most or the orbits have high orbital inclinations - a result of a perturbation of the star's rotation axis or the protoplanetary disk - or low orbital inclinations. The Lidov-Kozai mechanism is not good for large systems. It is also important to note that it is periodic in nature.
Once again quoting Fang & Margot,
>
> In addition, over 85% of planets have orbital inclinations less than 3◦ (relative to a common reference plane).
>
>
>
They used a [Rayleigh distribution](http://en.wikipedia.org/wiki/Rayleigh_distribution) to describe this:
$$P(k)=\frac{k}{\sigma^2}e^{-k^2/\sigma^2}$$
where $\sigma$ is the parameter that determines the distribution of $k$. Notice the difference between a Rayleigh distribution and a [normal distribution](http://en.wikipedia.org/wiki/Normal_distribution). An distribution for orbital eccentricity can be found in [Kane et al. (2012)](http://arxiv.org/abs/1203.1631).
---
Bringing it all together.
-------------------------
There's the raw information that we need. Here's the synthesis.
>
> Is this the most likely arrangement, RxAxGx?
>
>
>
Well, it's unlikely for that many planets to form around a star, so technically, no. Three gas giants implies orbital migration, which *could* push them outwards, as in our Solar System, but be prepared to have a fourth be in there at the beginning, as some variants of the Nice Model require (the "5th gas giant").
>
> Can a massive gas giant be orbiting near the star out of the ecliptic plane?
>
>
>
I stated earlier that the perturber generally needs to be more massive than the perturbed object, in classical models of the Kozai effect. This means that such an arrangement is unlikely to happen. A gas giant could be close to the star, sure, but not out of the ecliptic, if it was with a system of other planets that stayed in the ecliptic.
>
> Can the habitable would be alone with some comets and asteroids?
>
>
>
Asteroids? Sure. Well, the habitable could not be *in* the asteroid belt, because then it would not have cleared its orbit and would be prone to collisions, which would quickly make the planet not so habitable!
**The arrangement, on the whole, could happen.** |
21,583 | <p>Okay, so humanity has been orbiting black holes so that we can time dilate, and explore the galaxy. The black holes enjoy being in the presence of the most complex things in the universe, and we have mutual respect. Some time later, humanity starts using the black holes as trash cans spewing our waste into them. Dissident starts growing among the black holes, although the humans do not notice.</p>
<p>Unexpectedly, a small faction of the black holes decide to <a href="https://en.wikipedia.org/wiki/No-hair_theorem" rel="nofollow">grow some hair</a>. They gain sentience. Here is their abilities:</p>
<ul>
<li>They can now increase the amount of hawking radiation they emit. This still drains them though. They also can not decrease it below normal levels, so if they get too small, they would be in great danger.</li>
<li>They also can control the direction of their hawking radiation, being means of propulsion.</li>
<li>They sense the gravitational influence of all objects around them. A typical black hole would be able to detect how many bodies as large as the ISS are in the solar system if it where near the center. Since it is based on acceleration, a smaller black hole would be much more sensitive. They also automatically detect anything passing their event horizon.</li>
<li>They have developed a language based on the above.</li>
<li>They average intelligence is that of a human, as well as the variation in intelligence. They are also emotionally like humans.</li>
<li>Micro black holes are more suicidal, since they have shorter life spans and are appalled by the fact humans made them.</li>
</ul>
<p>And they are MAD. They have blasted many humans out of orbit and into them with blasts of hawking radiation. Smaller black holes inside are engines have explode. Now the black holes are going to attack Sector 001: Earth.</p>
<ul>
<li>What can we do to defend Earth from the black holes?</li>
<li>How do we arrest these black holes?</li>
<li>What Judicial precedents apply for trying the black holes in court?</li>
<li>In the long term, how will we mend human-black Hole relations, based on human-human relations in history, when one group of humans disrespected another.</li>
</ul>
<p>Some other things to note:</p>
<ul>
<li>Most of the black holes are still loyal to humans, and find the actions of the terrorist black holes extreme.
Note:</li>
<li>Black holes that haven't turned on us do not grow hair, and stay as they have been.</li>
<li>Unfortunately, communication with loyal black holes is one way. Luckily, they have learned human languages, from our wireless communications (which they enjoy. There is nothing that a Black Hole doesn't love more than a rerun of "I Love Lucy.")</li>
<li>Humans had no idea any of this was possible up to this point.</li>
</ul>
<p>Humanity needs your help. What do we do?</p>
| [
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"answer_id": 21589,
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"text": "<p>So this one is pretty much hopeless. If you read anything about planetoids, you know we can't protect ou... | 2015/07/30 | [
"https://worldbuilding.stackexchange.com/questions/21583",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/8914/"
] | Okay, so humanity has been orbiting black holes so that we can time dilate, and explore the galaxy. The black holes enjoy being in the presence of the most complex things in the universe, and we have mutual respect. Some time later, humanity starts using the black holes as trash cans spewing our waste into them. Dissident starts growing among the black holes, although the humans do not notice.
Unexpectedly, a small faction of the black holes decide to [grow some hair](https://en.wikipedia.org/wiki/No-hair_theorem). They gain sentience. Here is their abilities:
* They can now increase the amount of hawking radiation they emit. This still drains them though. They also can not decrease it below normal levels, so if they get too small, they would be in great danger.
* They also can control the direction of their hawking radiation, being means of propulsion.
* They sense the gravitational influence of all objects around them. A typical black hole would be able to detect how many bodies as large as the ISS are in the solar system if it where near the center. Since it is based on acceleration, a smaller black hole would be much more sensitive. They also automatically detect anything passing their event horizon.
* They have developed a language based on the above.
* They average intelligence is that of a human, as well as the variation in intelligence. They are also emotionally like humans.
* Micro black holes are more suicidal, since they have shorter life spans and are appalled by the fact humans made them.
And they are MAD. They have blasted many humans out of orbit and into them with blasts of hawking radiation. Smaller black holes inside are engines have explode. Now the black holes are going to attack Sector 001: Earth.
* What can we do to defend Earth from the black holes?
* How do we arrest these black holes?
* What Judicial precedents apply for trying the black holes in court?
* In the long term, how will we mend human-black Hole relations, based on human-human relations in history, when one group of humans disrespected another.
Some other things to note:
* Most of the black holes are still loyal to humans, and find the actions of the terrorist black holes extreme.
Note:
* Black holes that haven't turned on us do not grow hair, and stay as they have been.
* Unfortunately, communication with loyal black holes is one way. Luckily, they have learned human languages, from our wireless communications (which they enjoy. There is nothing that a Black Hole doesn't love more than a rerun of "I Love Lucy.")
* Humans had no idea any of this was possible up to this point.
Humanity needs your help. What do we do? | So this one is pretty much hopeless. If you read anything about planetoids, you know we can't protect ourselves against them. If you read anything about stars, they basically boss planetoids around without more than the slightest wobble. Black holes boss stars around.
Our best hope is to beg forgiveness. I don't know what we can do, but it is certainly going to involve lots of groveling, because they have 100% control of the situation, and if we are really really really optimistic, we can claim we have 0.00000001% of the control.
```
What can we do to defend Earth from the black holes?
How do we arrest these black holes?
What Judicial precedents apply for trying the black holes in court?
In the long term, how will we mend human-black Hole relations, based on human-human relations in history, when one group of humans disrespected another.
```
Nothing. We do not defend Earth from black holes, because it is simply not realistic. We do not arrest black holes or have judicial precidences for the same reason we do not arrest solar flares... they're bigger than our entire judicial system. As for mending things... grovel. Admit our place, which is really no place at all, and hope that it is worth their time to even hear our groveling. It might not even be a concern anymore.
For a sense of how big these black holes are, I will point out that they are within a few orders of magnitude of a supernova. Here's [XKCD's thoughts](https://what-if.xkcd.com/73/) on how big a supernova is. |
21,596 | <p>Assume that Uranium is vastly available, as are the building materials. Can you build this device?</p>
<p>The fuel tank stores uranium at a high temperature so that it remains liquid. The fuel injector/s spray a continuous stream of molten uranium into the nuclear fission chamber. The fission chamber sustains a continuous fission reaction. The pressure is vented out of a thruster like a regular rocket engine.</p>
<p>This could be used to propel rockets or spaceships or whatever.</p>
<p>Some problems I'm thinking of already:</p>
<ol>
<li>Either the fuel injectors fail to inject fuel fast enough so that the reaction fizzles out, or the reaction travels up the stream of uranium and detonates the fuel tank like a regular a-bomb.</li>
<li>The combustion chamber would be blown apart, or it would be built to withstand the reaction, and would therefore be too heavy.</li>
<li>The shielding to protect the fuel supply from sub-atomic-bricker-bracker would be too heavy.</li>
</ol>
<p>I was also thinking that instead of sustaining a continuous reaction, you could just continuously provide the conditions to begin a new reaction. (a nuclear fission pilot flame if you will.)</p>
<p>Could a nuclear fission rocket engine ever work?</p>
<p>Do you think it could work better than rocket fuel?</p>
| [
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"text": "<p>That'll work, but it's inefficient: much of the energy generated gets radiated away as gamma radiation or other h... | 2015/07/31 | [
"https://worldbuilding.stackexchange.com/questions/21596",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/10981/"
] | Assume that Uranium is vastly available, as are the building materials. Can you build this device?
The fuel tank stores uranium at a high temperature so that it remains liquid. The fuel injector/s spray a continuous stream of molten uranium into the nuclear fission chamber. The fission chamber sustains a continuous fission reaction. The pressure is vented out of a thruster like a regular rocket engine.
This could be used to propel rockets or spaceships or whatever.
Some problems I'm thinking of already:
1. Either the fuel injectors fail to inject fuel fast enough so that the reaction fizzles out, or the reaction travels up the stream of uranium and detonates the fuel tank like a regular a-bomb.
2. The combustion chamber would be blown apart, or it would be built to withstand the reaction, and would therefore be too heavy.
3. The shielding to protect the fuel supply from sub-atomic-bricker-bracker would be too heavy.
I was also thinking that instead of sustaining a continuous reaction, you could just continuously provide the conditions to begin a new reaction. (a nuclear fission pilot flame if you will.)
Could a nuclear fission rocket engine ever work?
Do you think it could work better than rocket fuel? | There is a concept similar to this called a [Nuclear Salt Water Rocket (NSWR)](http://www.projectrho.com/public_html/rocket/enginelist.php#id--Nuclear_Thermal--Gas_Core--Open_Cycle--Nuclear_Salt_Water) that was proposed by an SF writer who is also a physicist.
>
> The fuel is a 2% solution of 20% enriched Uranium Tetrabromide in
> water. A Plutonium salt can also be used.
>
>
> Just to make things clear, there are two percentages here. The fuel is
> a 2% solution of uranium tetrabromide and water. That is, 2 molecules
> of uranium tetrabromide per 100 molecules of water.
>
>
> But the uranium tetrabromide can be 20% enriched. This means that out
> of every 100 atoms of uranium (or molecules of uranium tetrabromide),
> 20 are fissionable Uranium-235 and 80 are non-fissionable uranium. If
> it is 90% enriched, then 90 atoms are Uranium-235 and 10 atoms are
> non-fissionable. As a side note, 90% enriched is considered
> "weapons-grade".
>
>
> The fuel tanks are a bundle of pipes coated with a layer of boron
> carbide neutron damper. The damper prevents a chain reaction. The fuel
> is injected into a long cylindrical plenum pipe of large diameter,
> which terminates in a rocket nozzle. Free of the neutron damper, a
> critical mass of uranium soon develops. The energy release vaporizes
> the water, and the blast of steam carries the still reacting uranium
> out the nozzle.
>
>
> It is basically a continuously detonating Orion type drive with water
> as propellant. Although **Zubrin** puts it like this:
>
>
>
> >
> >
> > ```
> > As the solution continues to pour into the plenum from the borated
> > storage pipes, a steady-state conditions of a moving detonating fluid
> > can be set up within the plenum.
> >
> > ```
> >
> >
>
>
>
Also, just to be clear this is a concept that could work *in theory* but working out the engineering details will be incredibly difficult (and other scientists do not think it will ever be practical).
NSWR:
[](https://i.stack.imgur.com/zBQmV.jpg)
20% UTB
```
Exhaust Velocity 66,000 m/s
Specific Impulse 6,728 s
Thrust 12,900,000 N
Thrust Power 425.7 GW
Mass Flow 195 kg/s
Total Engine Mass 33,000 kg
```
90% UTB
```
Exhaust Velocity 4,700,000 m/s
Specific Impulse 479,103 s
Thrust 13,000,000 N
Thrust Power 30.6 TW
Mass Flow 3 kg/s
```
Far more information available at the link provided above. |
22,287 | <p>Let's assume that a halfling is of similar build, but half the height of an adult human. If I strap a wing suit onto one, I should have a quarter the surface area, but one eight the weight of an adult human, meaning that I should have half the loading factor of a human in a wing suit, which should mean I can travel a bit slower. Now let's say I take my wing suited halfling and throw him off the top of a tall tower or tree. Lucky for him, I'm throwing him towards some sort of net or other reusable halfling-catcher located on another tower or tree some distance away.</p>
<p>If the halflings have roughly middle-ages technology, can they build the halfling catcher in such a manner as to not maim my half-sized missile? Is this an effective way of getting a halfling (or similar-sized creature) over potentially dangerous terrain, or is the whole scheme really just half-baked?</p>
<p>I'm assuming that my halflings are of roughly average build, at around a meter high and 20kgs, and have built platforms at the tops of the tallest trees in their area, which are around 100m in height. Their goal is to travel as far as possible using a wingsuit in a manner which will not result in their injury.</p>
| [
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"text": "<p>Davinci developed his flying machine. Parachutes are fairly simple technology and operate on \"drag\" to dep... | 2015/08/10 | [
"https://worldbuilding.stackexchange.com/questions/22287",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/2947/"
] | Let's assume that a halfling is of similar build, but half the height of an adult human. If I strap a wing suit onto one, I should have a quarter the surface area, but one eight the weight of an adult human, meaning that I should have half the loading factor of a human in a wing suit, which should mean I can travel a bit slower. Now let's say I take my wing suited halfling and throw him off the top of a tall tower or tree. Lucky for him, I'm throwing him towards some sort of net or other reusable halfling-catcher located on another tower or tree some distance away.
If the halflings have roughly middle-ages technology, can they build the halfling catcher in such a manner as to not maim my half-sized missile? Is this an effective way of getting a halfling (or similar-sized creature) over potentially dangerous terrain, or is the whole scheme really just half-baked?
I'm assuming that my halflings are of roughly average build, at around a meter high and 20kgs, and have built platforms at the tops of the tallest trees in their area, which are around 100m in height. Their goal is to travel as far as possible using a wingsuit in a manner which will not result in their injury. | Assuming a wingsuit with a 2-1 glide ratio (2 meters forward, 1 meter down), we should be able to create a massive net to catch the halfling. Wingsuits typically start gliding at approx 30mph (which is approx 13 m/s, taking approx 1.365 seconds to reach).
Rough calculation (probably not that accurate):
Starting from 100 meters up, jumping forwards, taking 1.365 seconds to reach wingsuit glidable speed, the halfling has already dropped ~9.136 meters, leaving ~91 meters to drop. If we go with a straight up conversion using the glide ratio assumed, our maximum distance traveled is 182 meters forward - but this would leave us splat on the ground, so we need to reduce this.
Let us assume the following setup.
```
platforms
___ ___
| |
| |
| badly drawn net |
| x __ | ^
| -- | 100m
| \- | v
| \-_ _ /|
_____________________________________________ground
```
X marks the target for the halfling, where he should aim to start contacting the net. The net will be roughly U shaped with the outer end much higher than the end point. The point of the catcher is to change his downards trajectory as gently as possible into a horizontal trajectory, until we can change it into an upwards trajectory where gravity will slow him down to safety. By using a curved net, we can acheive this - kind of like how skateboarders eventually settle down in the middle of a halfpipe.
However, all that is speculation without actual math, so lets do some math.
A 91 meter drop allows you to drop for 4.30799664301 seconds before hitting the ground. During that time you will have traveled 182 meters forward, but you would have hit the ground at a speed of 39.2266 meters per second, enough to kill your halfling. Assuming your net is large enough and your target tree is really far away, you could potentially allow for a full flight time of 2 + 1.365 seconds, where he would have dropped his altitude by a total of 55.5214522231 meters - we subtract the initial 9.1 meters, leaving him with leaving him with a total distance traveled of about 90 meters forwards (Enough to fly over a river or a small hill or something like that). At that point, he is plummeting at 32.99937725 meters per second, which is quite dangerous. This is where your halfling should reach the top of the net and begin to roll down it. He'll have 45 meters (roughly) of netting to roll through, while friction and the net slow him down, eventually to the point of safety.
In short: From a 100 meter drop, the halfling can fly 90 meters forwards before probably needing to hit the catcher.
Note: You may have noticed I didn't actually do the math for how long it would take the net to stop him, or how far he would have to roll. This is because **I don't know how to do the math for that part.** If anyone does, **please** feel free to edit this answer to include the proper maths.
Note 2: I used [this](http://www.gravitycalc.com/) site for the calculations. |
22,563 | <p>In the world, I'm designing goblins are described as follows:</p>
<ul>
<li>100-150cm tall</li>
<li>Skinny</li>
<li>Hairless</li>
<li>About as strong as humans</li>
<li>Devoid of any natural weapon (like teeth or claws)</li>
<li>Skin similar to high quality leather jacket</li>
<li>Highly intelligent and creative</li>
<li>Short-sighted, but excellent sense of smell and hearing</li>
<li>Impatient, with attention span measured in seconds</li>
<li>Their three greatest pleasures are tinkering, novelties and gadgets</li>
<li>Their three greatest fears are boredom, routine and order</li>
<li>They mostly live in caves, abandoned dwarven mines, and other dark, confined places</li>
</ul>
<p>But the most important part of their physiognomy are their arms.</p>
<p>They are as long as the whole body, even longer (compared to the overall height) than orangutans and have two elbows instead of one: in third and two-thirds of arms length. I have not yet decided, which direction they would bend (although all others restrictions of an elbow remain the same). </p>
<p>Each arm ends with six-fingered hand - the sixth finger is another opposable thumb, next to the pinky. </p>
<p>Now I wonder what would be a perfect weapon for such creatures. </p>
<p>At first I was going to go with a rapier, since long arms and small frame alone would make them excellent fencers, and additional elbow would allow them to execute many surprising attacks against elbowly-challenged opponents.</p>
<p>The problem is, that a rapier is essentially just a piece of metal with a pointy end. Maybe with sharp edges, if you're lucky. That doesn't really go well with goblin's character. </p>
<p>Ideal weapon for my goblins would have following characteristics:</p>
<ul>
<li>Allow a lot of customization by the owner, both in terms of looks and effectiveness (the former has higher priority than the latter, but not to the point when the weapon becomes dead weight) </li>
<li>Small to medium sized (polearms or huge battle axes would not be practical in their habitat)</li>
<li>Allow them to leverage the fact, that they have two elbows </li>
</ul>
<p>Assume late Middle-Ages/early Renaissance level of technology, although manufacturing local equivalent of gunpowder requires a spell-caster and goblin have no access to magic. Other resources (most importantly ore and skilled labour) are provided in abundance by their allies, who use the goblins to fight a proxy war with dwarves. </p>
<p>EDIT:</p>
<p>Answers to several good points posted by Cort Ammon:</p>
<blockquote>
<p>what purposes do the longer double-elbowed limbs provide to warrant the extra complexity of a joint? Is there a prey they need, or a difficult environment to traverse?</p>
</blockquote>
<p>They can reach into tight spots to acquire food or precious materials. Goblins aren't predators, but opportunists. They eat fungus, mushrooms and half-rotten meat. Usually those things don't lie or grow in easily accessible places. </p>
<p>Such limbs allow also easier climbing and checking what is in front of you in a dark cave.</p>
<blockquote>
<p>Understanding better how the goblins think about their double-elbowed arm is helpful in studying how they would apply it.</p>
</blockquote>
<p>Those which have limited contact with other species just think of it as their arm. The rest sees is a sign of superiority to others, even in environments where it's not in the least beneficial.</p>
<blockquote>
<p>Also important is pure psychology: a patient race will use a different style of weapon from an impatient one. Also look at how much training</p>
</blockquote>
<p>No formal training (as in practising the same moves over and over again) is possible, but they never make the same mistake twice and they are masters of thinking out of the box, even under pressure. Their biggest weakness is they like theatrics a little too much for their own good.</p>
| [
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"text": "<p>I'm going with a bullwhip. You can add things at either end. A cat-o-nine tales is a whip with little bits ... | 2015/08/13 | [
"https://worldbuilding.stackexchange.com/questions/22563",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/3254/"
] | In the world, I'm designing goblins are described as follows:
* 100-150cm tall
* Skinny
* Hairless
* About as strong as humans
* Devoid of any natural weapon (like teeth or claws)
* Skin similar to high quality leather jacket
* Highly intelligent and creative
* Short-sighted, but excellent sense of smell and hearing
* Impatient, with attention span measured in seconds
* Their three greatest pleasures are tinkering, novelties and gadgets
* Their three greatest fears are boredom, routine and order
* They mostly live in caves, abandoned dwarven mines, and other dark, confined places
But the most important part of their physiognomy are their arms.
They are as long as the whole body, even longer (compared to the overall height) than orangutans and have two elbows instead of one: in third and two-thirds of arms length. I have not yet decided, which direction they would bend (although all others restrictions of an elbow remain the same).
Each arm ends with six-fingered hand - the sixth finger is another opposable thumb, next to the pinky.
Now I wonder what would be a perfect weapon for such creatures.
At first I was going to go with a rapier, since long arms and small frame alone would make them excellent fencers, and additional elbow would allow them to execute many surprising attacks against elbowly-challenged opponents.
The problem is, that a rapier is essentially just a piece of metal with a pointy end. Maybe with sharp edges, if you're lucky. That doesn't really go well with goblin's character.
Ideal weapon for my goblins would have following characteristics:
* Allow a lot of customization by the owner, both in terms of looks and effectiveness (the former has higher priority than the latter, but not to the point when the weapon becomes dead weight)
* Small to medium sized (polearms or huge battle axes would not be practical in their habitat)
* Allow them to leverage the fact, that they have two elbows
Assume late Middle-Ages/early Renaissance level of technology, although manufacturing local equivalent of gunpowder requires a spell-caster and goblin have no access to magic. Other resources (most importantly ore and skilled labour) are provided in abundance by their allies, who use the goblins to fight a proxy war with dwarves.
EDIT:
Answers to several good points posted by Cort Ammon:
>
> what purposes do the longer double-elbowed limbs provide to warrant the extra complexity of a joint? Is there a prey they need, or a difficult environment to traverse?
>
>
>
They can reach into tight spots to acquire food or precious materials. Goblins aren't predators, but opportunists. They eat fungus, mushrooms and half-rotten meat. Usually those things don't lie or grow in easily accessible places.
Such limbs allow also easier climbing and checking what is in front of you in a dark cave.
>
> Understanding better how the goblins think about their double-elbowed arm is helpful in studying how they would apply it.
>
>
>
Those which have limited contact with other species just think of it as their arm. The rest sees is a sign of superiority to others, even in environments where it's not in the least beneficial.
>
> Also important is pure psychology: a patient race will use a different style of weapon from an impatient one. Also look at how much training
>
>
>
No formal training (as in practising the same moves over and over again) is possible, but they never make the same mistake twice and they are masters of thinking out of the box, even under pressure. Their biggest weakness is they like theatrics a little too much for their own good. | First, lets do away with the usual concept of a melee weapon. Short sightedness tends to make conventional weapons inaccurate and bad to use. So lets get up close and personal.
Your description of the elbow placement and arm structure reminds me very much of the praying mantis. [](https://i.stack.imgur.com/NuJtT.jpg)
When in doubt, look at nature. The mantis is often considered natures "Perfect Predator". But that's less important for this question - what's more important is its arm structure.
Assuming that the elbows bend the same ways as the mantis elbows do, with joints at 1/3 and 2/3 down the arm, we can apply a specific weapon for maximum efficiency, taking into account natures design.
I propose the following weapon:
```
---------O---------O---------[]>
V V V V V V V V V
```
Or alternatively, following the same concept (Version 2)
```
---------o---------o---------[]>
\_______/ \______/
```
This is meant to be a "harness" (but can be easily adapted to have protection in the form of metal plates or whatnot).
* `[]>` represents a handheld spike
* `o` represents a joint
* `---------` represents the sections of the arm that it is attached to, either via straps or locking mechanism, or whatever you want.
* `V` represents spikes
* `\____/` represents blades
How does this weapon work?
Let's tackle this weapon one spot at a time, starting with the hand held spike. Consider the fully retracted arm - it looks something like this:
```
\/\
```
This is a position from which we can easily extend forwards into this:
```
─ ─ ─
```
By providing a spike for the hand to hold, the user can "palm thrust" the spikes into the enemy quickly and with precision. Generally, stabbing is easily forseen as us single elbow users have to pull back and then thrust forwards. In this case, the double elbow user doesn't have the "pulling back" motion, since the retracted motion is likely the "default" position in order to keep the arms off the floor (especially since the arms are longer than the body).
Note: the palm spike can easily be interchanged with a large amount of options, such as palm bucklers or normal weaponry. Highly customizable.
What about the spikes and blades?
Spikes and blades are interchangeable. I picked the spikes for version 1 because the mantis has spikes. It makes for a good gripping mechanism. You can grip with the following arm motion:
```
__
\/| -> \/ -> \/|
start extend retract and grip
```
and the spikes will help keep your gripped target in place while you thrust into them with the spike in your other hand.
The blades, however, are not for gripping. If we offset the front and back blades a little bit, we can use them as a pair of scissors. Using the same motion as above, we can slice off limbs easily using the arm-slicers.
Alternatively, with the blades, you don't have to cut like a scissor. When throw outwards with the same initial motion as the cut, as long as the user aims higher than the target, he can get a "cutting" like a knife motion with the blade, and achieve "slashing" by simply swinging the arm instead of retracting it.
This weapon isn't only for offense. If we design the arm sections with plating, we now effectively have weaponized gauntlets, and the user can use the protected arms (especially since they're so long) as shields to block attacks.
You mention that it should be customizable per user for looks and usability - easily done, as you can change out parts of the harness for thicker metal plates for protection, or sharper cutting appendages, etc etc, anything the user wants, and it can be easily painted and whatnot for decoration.
**There you have it - the perfect melee weapon for a two elbowed creature.** |
23,691 | <p>So I want to send a ship to Alpha Centauri very quickly - by this, I mean less than 5 years. This means that the ship will have to accelerate at 50-100 $g$ or even more. But we don't want to turn our astronauts into pancakes, right?</p>
<p>Is spending long time periods in perfluorocarbons saturated with oxygen (or similar stuff) actually healthy or does it pose risks? What are the side effects? Does it neutralize the $g$-forces? How does it feel swimming or sitting in tanks filled with perfluorocarbons while your ship is accelerating at 1000 meters per square second?</p>
<p>Can this only be used on spaceships or can you use that in habitats on high-gravity planets too?</p>
| [
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"text": "<p><strong>You probably can survive heavy acceleration while breathing liquids</strong> though keeping tabs on ... | 2015/08/30 | [
"https://worldbuilding.stackexchange.com/questions/23691",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/12168/"
] | So I want to send a ship to Alpha Centauri very quickly - by this, I mean less than 5 years. This means that the ship will have to accelerate at 50-100 $g$ or even more. But we don't want to turn our astronauts into pancakes, right?
Is spending long time periods in perfluorocarbons saturated with oxygen (or similar stuff) actually healthy or does it pose risks? What are the side effects? Does it neutralize the $g$-forces? How does it feel swimming or sitting in tanks filled with perfluorocarbons while your ship is accelerating at 1000 meters per square second?
Can this only be used on spaceships or can you use that in habitats on high-gravity planets too? | **You probably can survive heavy acceleration while breathing liquids** though keeping tabs on infection and ventilator function over longer periods will be definite concerns.
**Breathing Fluorocarbons**
The [Biology SE answer](https://biology.stackexchange.com/questions/23074/what-are-the-effects-of-long-term-liquid-breathing) indicates that it's possible for animals (very little human testing has been done) to survive for extended periods while immersed in and breathing fluorocarbons. Animal diaphragms aren't strong enough to move fluids so a ventilator must be used. Due to the dearth of research on the long-term effects of adult humans breathing fluorocarbons for weeks, months or years, everything is speculation though, given the inert nature of fluorocarbons, it would probably be okay.
**Suspension in Fluorocarbons**
* Density of water is 1 gl/ml.
* Density of FC-75 is [1.75 to 1.79g/mL.](https://www.fishersci.com/shop/products/perfluoro-compound-fc-75-acros-organics-3/p-179920)
* Density of human body is between [1.04 and 1.08 g/ml](http://ajcn.nutrition.org/content/20/4/305.full.pdf) (page 307).
So without a weight belt/suit, a human will tend to "float" towards the top of the tank. Under 1$g$ acceleration, a simple weight belt is sufficient to maintain buoyancy because the strain induced by differences in buoyancy between the human body and water is negligible. *However, under 50 to 100$g$ the strain will be considerably more and will need to be accounted for.* A full body weighted & pressure suit will be best because the less dense portions of the human body will want to float up and must be restrained.
There is also [this article](http://onlinelibrary.wiley.com/doi/10.1002/cphy.cp040240/abstract) (paywall) about adaptation to acceleration environments.
*Yes you probably could suspend a crew in a fluid for the crushing accelerations required by the OP but it doesn't take a ton of handwaving to do so.* The only people you're going to really annoy are the buoyancy scientists.
**Older Answer:**
From the Biology SE answer:
>
> Kylstra, the first pioneer introducing the idea of land animals breathing liquids (Kylstra et al., 1962, found mice could withstand 4 hours of 160 atmospheres of pressure.
>
>
>
So how much acceleration is equivalent to 160 atmospheres?
```
100kpa is one atmosphere.
100kpa * 160 = 16000kpa
P=F/A
F=P*A
F=16000000 Pa (N/m^2) * 1.7 m^2
F = 27.2 MN
```
While 27.2 meganewtons seems like a lot, remember that this is across the entire surface of the body and from all directions so the pressures equalize. Free gases in the gut will diffuse in the surrounding tissues so decompressing/decelerating will need to be done slowly to avoid a lethal case of the bends. |
24,009 | <p>I am an evil genius owning a space station in a 400km orbit around Earth. As part of my plan for world domination I would like to equip this space station with a ground-attack laser cannon. Approximately how powerful (in watt) would an orbital laser need to be so that a one-second burst could destroy:</p>
<ul>
<li>an unprotected person</li>
<li>an unarmored car</li>
<li>a one-family house</li>
<li>a battle tank</li>
<li>an office building</li>
<li>a small town</li>
</ul>
<p>Assume that the target is on normal-null altitude, directly below the orbit of my station and that the weather conditions are as favorable as can be reasonably expected.</p>
| [
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"text": "<p><em>So I'm no rocket scientist, but here goes. Much of this is shamelessly lifted from Project Rho.</em> <... | 2015/09/03 | [
"https://worldbuilding.stackexchange.com/questions/24009",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/224/"
] | I am an evil genius owning a space station in a 400km orbit around Earth. As part of my plan for world domination I would like to equip this space station with a ground-attack laser cannon. Approximately how powerful (in watt) would an orbital laser need to be so that a one-second burst could destroy:
* an unprotected person
* an unarmored car
* a one-family house
* a battle tank
* an office building
* a small town
Assume that the target is on normal-null altitude, directly below the orbit of my station and that the weather conditions are as favorable as can be reasonably expected. | *So I'm no rocket scientist, but here goes. Much of this is shamelessly lifted from Project Rho.*
First, lets ignore the diffraction caused by passing through the earths atmosphere for the following. I'm also assuming you're talking an actual laser, not a particle weapon, blaster, or some other variant.
A general idea to start with is for the US military, the minimum threshold for a tactical weapons-grade laser is 100 kilowatts.
Maximum range will be a few hundred thousand kilometers, otherwise almost every shot will miss due to light-speed lag, Unless we are shooting at targets that don't move.
First we calculate the beam divergence angle θ (θ = 1.22 L/RL)
```
$θ = beam divergence angle (radians)$
$L = wavelength of laser beam (m, see table above)$
$RL = radius of laser lens or reflector (m)$
```
Next is beam power BP, then calculate the beam intensity at the target (the beam "brightness"):
$$BPT = BP/(π \* (D \* tan(θ/2))2)$$
```
$BPT = Beam intensity at target (megawatts per square meter)$
$BP = Beam Power at laser aperture (megawatts)$
$D = range to target (meters)$
$θ = Theta = Beam divergence angle (radians or degrees depending on your Tan() function)$
$π = Pi = 3.14159...$
```
The following equation will be of use for determining the diffraction:
$$R\_T = \frac{0.61 D L}{R\_L}$$
where:
$R\_T$ = beam radius at target (m)
$D$ = distance from laser emitter to target (m)
$L$ = wavelength of laser beam (m, see table below)
$R\_L$ = radius of laser lens or reflector (m)
As for laser wavelengths:
* Near Infrared 2.5$\times$10-6 to 7.5$\times$10-7 m (2,500 to 750 nanometers)
* Red 7.5$\times$10-7 to 6.2$\times$10-7 m (750 to 620 nanometers)
* Orange 6.2$\times$10-7 to 5.9$\times$10-7 m (620 to 590 nanometers)
* Yellow 5.9$\times$10-7 to 5.7$\times$10-7 m (590 to 570 nanometers)
* Green 5.7$\times$10-7 to 4.95$\times$10-7 m (570 to 495 nanometers)
* Blue 4.95$\times$10-7 to 4.5$\times$10-7 m (495 to 450 nanometers)
* Indigo 4.5$\times$10-7 to 4.2$\times$10-7 m (450 to 420 nanometers)
* Violet 4.2$\times$10-7 to 3.8$\times$10-7 m (420 to 380 nanometers)
* Ultraviolet A 4$\times$10-7 to 3.15$\times$10-7 m (400 to 315 nanometers)
* Ultraviolet B 3.15$\times$10-7 to 2.8$\times$10-7 m (315 to 280 nanometers)
* Extreme Ultraviolet 1$\times$10-7 to 1$\times$10-8 m (100 to 10 nanometers)
Below Extreme Ultraviolet, you can't use the laser outside of the vacuum of space as the atmosphere would absorb it, so we can ignore those.
An example of how this works is as follows:
>
> Say you have an ultraviolet (20 nanometer) laser cannon with a 3.2
> meter lens. Your hapless target is at a range of 12,900
> kilometers (12,900,000 meters). The Beam Radius equation says that the
> beam radius at the target will be about 4 centimeters (0.04 meters),
> so the beam will be irradiating about 50 cm2 of the target's skin
> (area of circle with radius of 4 centimeters). If the hapless target
> had a hull of steel armor, the armor has a heat of
> vaporization of about 60 kiloJoules/cm3. Say the armor is 12.5 cm
> thick. So for the laser cannon to punch a hole in the armor it will
> have to remove about 625 cm3 of steel (volume of cylinder with radius
> of 4 cm and height of 12.5 cm). 625 \* 60 = 37,500 kiloJoules. If the
> laser pulse is one second, this means the beam requires a power level
> of 37,500 watts or 38 megawatts at the target.
>
>
>
A note: using a pulsed laser rather than a single focused beam would require less power, in effect drilling into the target rather than trying to vaporize it.
Now aside from all of that, you're generating a massive amount of waste heat that will require dissipation, but that's a whole extra problem.
There's also a neat laser maker calculator [here](http://panoptesv.com/SciFi/LaserDeathRay/DamageFromLaser.php) that I would recommend for those that don't math.
Also to read the source of this information, you can find it [here](http://www.projectrho.com/public_html/rocket/spacegunconvent.php#id--Laser_Cannon). |
24,023 | <p>Imagine a powerful being of your choice casting this spell on Earth:</p>
<ol>
<li>Earth can hold only 8 billion people</li>
<li>If a child is being born and this child breaks the 8 billion rule, this happens:</li>
<li>Wait 30 minutes. If someone else dies in this time, then everything is OK</li>
<li>If not, take every human older than 32 minutes, and randomly kill one</li>
</ol>
<p>If step 4 happens, such a person always dies by a sudden heart attack. If they cannot have a heart attack, they simply stop breathing. If they cannot stop breathing, their brain will simply stop working.</p>
<p>Example: </p>
<pre><code> 22:00:00.000 UTC: Earth population: 8.000.000.000 people, waiting...
22:00:00.015 UTC: Live child (A) is being born in Pakistan
22:15:00.389 UTC: Live child (B) is being born in USA
22:25:13.618 UTC: Someone in Mongolia dies of age. Child A is resolved, Child B still pending
22:32:00.015 UTC: Treshold for Child A, it can be given to random pool
22:45:00.389 UTC: Child B is still unresolved, start random search...
22:45:00.390 UTC: A hunter in Siberia gets heart attack and dies
22:45:00.391 UTC: Earth population: 8.000.000.000 people, waiting...
22:50:05.850 UTC: Plane crashes in China. 190 people dead. Next 190 children can be born without killing anyone extra
</code></pre>
<p>For the scope of this question:<br>
Alive == Brain activity.<br>
Dead == no brain activity.</p>
<p>So if someone manages to survive a heart attack AND lung failure, their brain will simply shut off. So, you can keep their body "alive", but take for granted that such a person will never wake up (and they are taken out from the Earth random pool, because they are dead).</p>
<p><strong>The question:</strong> Will humanity ever find out that such a rule is in place?</p>
<p>It is estimated, that we will hit 8 billion people milestone by the year <a href="https://en.wikipedia.org/wiki/World_population_milestones#The_Day_of_Eight_Billion" rel="nofollow noreferrer">2026</a>.</p>
<p>I know it is safe to assume that in (say) the next 10 year, people will somewhat realise that something weird goes on. But will they be able to pick this magical link?</p>
<p>And what would help them to do so? Do I have to create an alternate Earth, where there is more magic than just this one?</p>
| [
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"text": "<p>Something will send up a flag, if the population count appears to stall at 8,000,000,000. At first I thought ... | 2015/09/03 | [
"https://worldbuilding.stackexchange.com/questions/24023",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/2071/"
] | Imagine a powerful being of your choice casting this spell on Earth:
1. Earth can hold only 8 billion people
2. If a child is being born and this child breaks the 8 billion rule, this happens:
3. Wait 30 minutes. If someone else dies in this time, then everything is OK
4. If not, take every human older than 32 minutes, and randomly kill one
If step 4 happens, such a person always dies by a sudden heart attack. If they cannot have a heart attack, they simply stop breathing. If they cannot stop breathing, their brain will simply stop working.
Example:
```
22:00:00.000 UTC: Earth population: 8.000.000.000 people, waiting...
22:00:00.015 UTC: Live child (A) is being born in Pakistan
22:15:00.389 UTC: Live child (B) is being born in USA
22:25:13.618 UTC: Someone in Mongolia dies of age. Child A is resolved, Child B still pending
22:32:00.015 UTC: Treshold for Child A, it can be given to random pool
22:45:00.389 UTC: Child B is still unresolved, start random search...
22:45:00.390 UTC: A hunter in Siberia gets heart attack and dies
22:45:00.391 UTC: Earth population: 8.000.000.000 people, waiting...
22:50:05.850 UTC: Plane crashes in China. 190 people dead. Next 190 children can be born without killing anyone extra
```
For the scope of this question:
Alive == Brain activity.
Dead == no brain activity.
So if someone manages to survive a heart attack AND lung failure, their brain will simply shut off. So, you can keep their body "alive", but take for granted that such a person will never wake up (and they are taken out from the Earth random pool, because they are dead).
**The question:** Will humanity ever find out that such a rule is in place?
It is estimated, that we will hit 8 billion people milestone by the year [2026](https://en.wikipedia.org/wiki/World_population_milestones#The_Day_of_Eight_Billion).
I know it is safe to assume that in (say) the next 10 year, people will somewhat realise that something weird goes on. But will they be able to pick this magical link?
And what would help them to do so? Do I have to create an alternate Earth, where there is more magic than just this one? | Something will send up a flag, if the population count appears to stall at 8,000,000,000. At first I thought it will likely take a few years past the mark to notice that overall population isn't increasing and maybe one or two more to narrow down a close number. However...
Looked it up it appears that the average death per day is 7.89/1000 people, the average births/day is around 20/1000. So there are over twice as many births as deaths/1000 people on the planet. Using these numbers once we hit 8,000,000,000 people the death rate will automatically more than double. That will be a huge flag for statisticians. And when the birth rate and death rate remain steady and equal (unless a large war or other event INCREASES the death rate) it will be pretty obvious that SOMETHING is going on artificially limiting the population.
The scary thing is that once the pattern is noticed, wars and genocide might be waged in order to 'choose' who will die, not us, but THEM!
EDT:
One last thing, if we discovered that being off Earth negates the 'spell', meaning it doesn't matter how many people are living on the moon, then we will start working hard at getting off this ball and colonizing the solar system. |
25,115 | <p>Imagine in the far future that there are space battles. In <a href="https://worldbuilding.stackexchange.com/questions/9717/how-would-space-battles-alter-combat-tactics">this question</a> user: m t said that in the future it would be too expensive to do stuff in space so people would focus on "offense, intelligence, and first-strike capabilities, leaving very little for defense." But say it we wanted to make a defensive system. So I had this idea:</p>
<p>Imagine a sliding door and somebody shooting NERF bullets at it. You could move the door back and forth blocking the bullets. So what if we did that in space, except the sides of the door would have magnets or rockets to propel it side to side, like this:</p>
<p>Rocket style:</p>
<pre><code> ___________________________________________
[ ]
(Rocket)>=[ ]=<(Rocket)
[___________________________________________]
</code></pre>
<p>Magnet style*:</p>
<pre><code> ___________________________________________
[ ]
(-) (Magnet+)>=[ ]=<(Magnet-) (+)
[___________________________________________]
</code></pre>
<p>*I would think that you could turn the +,- sides on and off so you could repel either side to make it move.</p>
<p>Would this work? I know that it would be hard to replace them if the enemy launched a ton of missiles, but is there a way to replace them fast and quick as well as being affordable?</p>
<p>So here:</p>
<ol>
<li>Can we do it?</li>
<li>Is it good enough to stop missiles?</li>
<li>Is it affordable?</li>
<li>And would the propulsion system side to side work? (If not, are there better
ways)</li>
<li>What materials should it be?</li>
</ol>
| [
{
"answer_id": 25136,
"author": "iAdjunct",
"author_id": 5110,
"author_profile": "https://worldbuilding.stackexchange.com/users/5110",
"pm_score": 1,
"selected": false,
"text": "<p>The first problem with things in space is that everything moves fast - REALLY fast. For example, when you'r... | 2015/09/04 | [
"https://worldbuilding.stackexchange.com/questions/25115",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/7453/"
] | Imagine in the far future that there are space battles. In [this question](https://worldbuilding.stackexchange.com/questions/9717/how-would-space-battles-alter-combat-tactics) user: m t said that in the future it would be too expensive to do stuff in space so people would focus on "offense, intelligence, and first-strike capabilities, leaving very little for defense." But say it we wanted to make a defensive system. So I had this idea:
Imagine a sliding door and somebody shooting NERF bullets at it. You could move the door back and forth blocking the bullets. So what if we did that in space, except the sides of the door would have magnets or rockets to propel it side to side, like this:
Rocket style:
```
___________________________________________
[ ]
(Rocket)>=[ ]=<(Rocket)
[___________________________________________]
```
Magnet style\*:
```
___________________________________________
[ ]
(-) (Magnet+)>=[ ]=<(Magnet-) (+)
[___________________________________________]
```
\*I would think that you could turn the +,- sides on and off so you could repel either side to make it move.
Would this work? I know that it would be hard to replace them if the enemy launched a ton of missiles, but is there a way to replace them fast and quick as well as being affordable?
So here:
1. Can we do it?
2. Is it good enough to stop missiles?
3. Is it affordable?
4. And would the propulsion system side to side work? (If not, are there better
ways)
5. What materials should it be? | The first problem with things in space is that everything moves fast - REALLY fast. For example, when you're near a planet, it's not that gravity is just too weak to pull you in - it's that you're going *really fast* and are counteracting gravity. To put a number to it, the international space station is traveling at 17,000 MPH.
With today's bi-propellant technology, if your shield were in the ISS's orbit and 90% of it was fuel and a missile was coming in behind you, the best you could do is go roughly 6,000 MPH in the other direction. However, you wouldn't actually go 6,000 MPH in the other direction: you would instead start falling back to Earth irritatingly quickly.
Changing orbits with today's technology is very difficult.
Furthermore, missiles flying in space are limited in what they can do because they have to carry all their fuel with them and accelerate it as well. This is why ballistic missiles are just ballistic: it's hard to affect changes in your trajectory when you would also have to carry fuel... so they just don't carry fuel and fly. We then lob little things at them to get in their way (EKV: Exoatmospheric Kill Vehicle, which is literally a thing that gets in the way of incoming missiles and runs into them - sound familiar?). These are incredibly expensive and rely heavily on the other target being predictable (in this case, ballistic) so they can minimize fuel usage and cost.
**But you asked about the future...**
Why did I say everything above? Because, in the future, if you have interplanetary travel, you *must* have solved the engine inefficiency problem and made it *trivial* to produce engines that can just do whatever you want. However, your space ships still have structural issues, so they can only maneuver so quickly *(unless, I suppose, the entire hull is lined with small engines so it can perfectly distribute forces)*. Presumably they may have also created some sort of an inertial damper to let them maneuver more quickly.
So let's say the enemy missiles and you both have the technology to make everything maneuver exactly how you want: **you still lose** because you're still playing defense and defense is always reactionary. If you get your shield right in the way of the missile (because your technology lets you do this effectively), then their missile would just change its course (because their technology *also* lets them do that). So you figure out how their algorithm works and make your shield predict theirs, so they change theirs. \*(Note: this is *exactly* how defense works nowadays too)\*.
Regardless of your level of technology between now and then, you CAN put a shield (whether it be something already in space or something like EKV) between you and them, but you always have a disadvantage that they will have the same maneuverability abilities and they control the game (again, defense is always reactionary). Plus your [big metallic] shield tends to get destroyed when it gets hit. Plus yours has to be a lot more expensive because it has to be *more* capable than theirs, so they can always exhaust your resources by just firing lots of them at you.
A shield like that really isn't any more effective than shooting their missile with your missile - except that your missile doesn't have to happen to be in the right spot [as much] as a shield does.
This, by the way, is the genesis of energy weapons.
**Some more related examples**
Using some numbers from wikipedia...
The US's "Minuteman" ballistic missiles cost $7 Million and [technically] only take a few people to operate them from a single silo.
The US's EKV program is hard to estimate the cost of, but [1] says they cost about $90+ Million each. It costs more than 10 times as much to defend against a single ICBM as it does to launch one. But this isn't the whole story, because to be able to hit a flying thing, you first have to *detect* the flying thing (with radars, which have limited range and precision) and transmit that information (which can be jammed) and launch against it, so you have the cost of all of those pieces too.
This cost differential has always been and probably always will be so.
[1] - <http://mostlymissiledefense.com/2012/07/24/ballistic-missile-defense-how-much-does-a-gbi-interceptor-cost-july-24-2012/> |
25,318 | <p>I have a planet orbiting one star in a binary system. When the planet is exactly between the two stars it will experience a <a href="https://worldbuilding.stackexchange.com/q/25203/28">double day</a>; when the primary sun sets the secondary one rises, no overlap. (My second star sheds enough light to make a difference on the planet.) When the planet is on the opposite point in its orbit the primary star occludes the secondary, so it's as if there were one star, lighting-wise. I'm trying to figure out the stuff in between.</p>
<p><a href="https://i.stack.imgur.com/dYtez.png" rel="noreferrer"><img src="https://i.stack.imgur.com/dYtez.png" alt="drawing of system"></a></p>
<p>The planet orbits A at a distance of 1AU. Answers on the linked question suggest that the distance between A and B should be 10-20AU for this to be viable. The planet's orbit is meant to be viable; feel free to treat it as circular despite the drawing.</p>
<p>I'm having trouble working out what days look like on the planet for the points in between the two marked positions. I <em>think</em> at the halfway points it'll get overlapping days, but I don't know how long (as a ratio of the rotation period). It's probably a simple matter of geometry, but adding the rotation of the planet to the orbit is causing me problems.</p>
<p>What I'd really like is a chart showing the progression of the day -- time of first sunrise, second sunrise, first sunset, second sunset -- for the four main points and perhaps the four in between those (so I can understand the transitions), at the equator and at what we'll call 45deg N. Treat times as relative to star A -- noon is when A is directly overhead, regardless of where B is.)</p>
<p>I know we're going to need some axial tilt to make this planet <em>have</em> seasons; pick and declare any reasonable-seeming number that makes your calculations easy, or default to Earth's for the sake of comparison. I'm trying to visualize what days and nights look like on this planet; I don't have precise numbers in mind.</p>
<p>We're also going to need a rotation period. For the sake of the question let's assume 24 hours like on Earth. In practice, once I know what the proportions look like, I'll adjust the rotation to suit the needs of my inhabitants (because we're worldbuilders and we can <em>do</em> that :-) ).</p>
| [
{
"answer_id": 25332,
"author": "Babika Babaka",
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"pm_score": 2,
"selected": false,
"text": "<p>I assumed here that the two stars and the planet are aligned, and midday/midnight are fixed using star... | 2015/09/09 | [
"https://worldbuilding.stackexchange.com/questions/25318",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/28/"
] | I have a planet orbiting one star in a binary system. When the planet is exactly between the two stars it will experience a [double day](https://worldbuilding.stackexchange.com/q/25203/28); when the primary sun sets the secondary one rises, no overlap. (My second star sheds enough light to make a difference on the planet.) When the planet is on the opposite point in its orbit the primary star occludes the secondary, so it's as if there were one star, lighting-wise. I'm trying to figure out the stuff in between.
[](https://i.stack.imgur.com/dYtez.png)
The planet orbits A at a distance of 1AU. Answers on the linked question suggest that the distance between A and B should be 10-20AU for this to be viable. The planet's orbit is meant to be viable; feel free to treat it as circular despite the drawing.
I'm having trouble working out what days look like on the planet for the points in between the two marked positions. I *think* at the halfway points it'll get overlapping days, but I don't know how long (as a ratio of the rotation period). It's probably a simple matter of geometry, but adding the rotation of the planet to the orbit is causing me problems.
What I'd really like is a chart showing the progression of the day -- time of first sunrise, second sunrise, first sunset, second sunset -- for the four main points and perhaps the four in between those (so I can understand the transitions), at the equator and at what we'll call 45deg N. Treat times as relative to star A -- noon is when A is directly overhead, regardless of where B is.)
I know we're going to need some axial tilt to make this planet *have* seasons; pick and declare any reasonable-seeming number that makes your calculations easy, or default to Earth's for the sake of comparison. I'm trying to visualize what days and nights look like on this planet; I don't have precise numbers in mind.
We're also going to need a rotation period. For the sake of the question let's assume 24 hours like on Earth. In practice, once I know what the proportions look like, I'll adjust the rotation to suit the needs of my inhabitants (because we're worldbuilders and we can *do* that :-) ). | Update
======
[](https://i.stack.imgur.com/S2zZz.png)
I've updated my CDF to handle eccentric orbits and customization of star brightness, and (more importantly) to show long-term seasonal effects. A few notes:
* Mousing over any of the parameters in the upper-left will show a tooltip with its name.
* Note that the luminosity slider only adjusts the luminosity by a small factor. A star's luminosity is mostly [determined by its mass](https://en.wikipedia.org/wiki/Mass%E2%80%93luminosity_relation), so changing the mass slider also changes the luminosity.
* I assume that one orbit of the planet around the primary star is a "year" (regardless of the actual length), and that the year is divided into twelve equal months. Similarly, I divide the day into 24 hours, regardless of the actual day length.
* The upper-right side shows the orbit of the planet and the companion star from two views.
* The middle plot shows the total energy received from both stars over the course of one orbit of the companion star.
* The lower-left plot shows the same information as before: the shaded regions show the times when the primary and companion stars are visible. The difference is that the year the time axis shows starts at the time `t` on the slider.
* The lower-right plot shows the average [insolation](https://en.wikipedia.org/wiki/Solar_irradiance) (received sunlight) over the course of one day for a given latitude and time of year. Clicking on this plot sets the latitude and time of the visibility plot to its left.
Download the `.cdf` file [here](http://googledrive.com/host/0B0VNJlWZGkwNfmlvUjNOQUxoZmVuTWFfeFRnUk5wRVhuRVJWcTA0YjVGaDIwdzhnSUYyNWs/binary-seasons.cdf) (needs the free [CDF player](https://www.wolfram.com/cdf-player/)), or if you have Mathematica you can download it with the following command:
```
Uncompress@FromCharacterCode@Flatten@Import["http://i.stack.imgur.com/l1bWc.png", "Data"]
```
Assumptions and Terms
---------------------
[
from Wikimedia Commons](https://commons.wikimedia.org/wiki/File:Orbit1.svg)
* The planet $a$ orbits a star $A$, which is part of a binary system $AB$.
* The intersection of the [ecliptic plane](https://en.wikipedia.org/wiki/Ecliptic) and the [equatorial plane](https://en.wikipedia.org/wiki/Celestial_equator) defines the [vernal equinox direction](https://en.wikipedia.org/wiki/Equinox#Celestial_coordinate_systems), labeled with $\Upsilon$ in the above diagram. Another way to think of this is the location of the planet when the [subsolar point](https://en.wikipedia.org/wiki/Subsolar_point) crosses the equator from South to North. We'll measure angles counterclockwise from this point.
* The angle between the ecliptic and the equatorial planes is the **obliquity** $\varepsilon$ (also called the axial tilt).
* The **mean longitude** $L$ is (for a low-inclination circular orbit) essentially the angle between an orbiting body and the reference direction when looking down on the orbital plane from above. It is equal to $\Omega+\omega+\nu$ in the above diagram.
* The **inclination** $i$ and **longitude of the ascending node** $\Omega$ are shown on the above diagram.
* The latitude of the observer on the planet is $\phi$.
Since the ecliptic is our plane of reference, for the planet $i\_a=0$ and $\Omega\_a$ is not defined. However, these values are useful for the binary companion $B$. I'll treat $B$ as orbiting $A$ even though $B$ is heavier (to be luminous enough it must be at least $5M\_\odot$).
I'm also treating the eccentricity of both orbits as zero so that the distances $r\_{Aa}$ and $r\_{AB}$ are constant.
With all this sorted out we can apply some "simple" geometry to determine when the stars are above the horizon.
Results
-------
I wrote a little `Manipulate` to visualize the effect of changing the latitude and orbital parameters of the binary. Here's what it looks like with the situation you describe at a mid-latitude of about 30 degrees north:
[](https://i.stack.imgur.com/e3eqw.png)
To figure out what's happening on a particular day, find the approximate date on the horizontal axis, then follow a vertical line straight up.
As you can see, the sunrise and sunset times for the primary are pretty typical, fluctuating around 6 AM or PM.
The companion star has a much more consistent duration of daylight, but its local noon 'laps' the primary's noon once a year.
[](https://i.stack.imgur.com/XdK8A.png)
On the equator, daylight times for the primary are more stable, but daylight times for the companion are relatively unchanged.
[](https://i.stack.imgur.com/W6H6E.png)
Far north of the arctic circle you can see that the summer has continuous daylight as before, but the would-be continuous winter night is interrupted by the companion star.
[](https://i.stack.imgur.com/QeUXv.png)
Changing the mean longitude of the companion ($L\_B$) shifts the day-night cycle of the companion forward or backward in the year.
Note that $L\_B$ travels through its full range about once for every orbit of the companion star (about 15 to 40 years). This means that the two hemispheres will regularly cycle between eternal-daylight "summers" and eternal-daylight "winters", making for an interesting and complex seasonal cycle.
---
I encourage you to experiment with the effects of adding inclination to the binary's orbit. To try it yourself, can either [download the `.cdf` file](http://googledrive.com/host/0B0VNJlWZGkwNfmlvUjNOQUxoZmVuTWFfeFRnUk5wRVhuRVJWcTA0YjVGaDIwdzhnSUYyNWs/binary-day-night.cdf) (you will need the free [CDF player from Wolfram](https://www.wolfram.com/cdf-player/)), or if you have a copy of Mathematica you can download it with the following command:
```
Uncompress@FromCharacterCode@Flatten@Import["http://i.stack.imgur.com/4ZDYm.png", "Data"]
```
 |
25,675 | <p>Back home, Earth's moon is 2159.2 miles wide and orbits 238,900 miles from its parent.</p>
<p>But let's pretend that the moon is 2500 miles wide and orbits 200,000 miles from Earth. Would the nightscape look any different? How much would tides and axial tilt be affected?</p>
| [
{
"answer_id": 25680,
"author": "Victor Stafusa - BozoNaCadeia",
"author_id": 3002,
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"pm_score": 2,
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"text": "<p>The Moon would just appear a bit larger in the sky. How many larger?</p>\n\n<p>Since t... | 2015/09/15 | [
"https://worldbuilding.stackexchange.com/questions/25675",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/10274/"
] | Back home, Earth's moon is 2159.2 miles wide and orbits 238,900 miles from its parent.
But let's pretend that the moon is 2500 miles wide and orbits 200,000 miles from Earth. Would the nightscape look any different? How much would tides and axial tilt be affected? | To simplify, lets calculate some of the basic ratios up front
```
Avg. orbital distance ratio (center to center) = 238,900 / 200,000 = 1.1945
Distance squared ratio = 1.1945^2 = 1.43683
Distance cubed ratio = 1.704349
Diameter ratio = 2500 / 2159.2 = 1.157836
Area ratio = diameter ratio squared = 1.340585
Volume ratio = diameter ration cubed = 1.552178
```
Assume mass ratio equals volume ratio, i.e. moon density is unchanged - this would not be true given identical materials as the matter would be more compressed with the additional pressure. So the mass ratio would be larger than the volume ratio. We don't know enough about the moon to calculate this accurately, not that I could model this change accurately without a lot of work.
**Moonlight is brighter** because it has 134% of its current surface area to reflect sunlight (and Earth-shine). But it is also closer and thus 143% of its intensity. Total moonlight received would be 1.912787 times the current moonlight.
Eyesight response to light is non-linear, so it won't appear 91% brighter. Due to variations in orbits, the full moon varies from about mean value of -12.74 magnitude to -12.9 at it brightest. Under this scenario mean brightness would be around -13.5 magnitude. Reading by moonlight would be easier, etc. More stars would be obscured during a full moon.
**Tides are larger** - roughly speaking, tides are proportional to mass / distance^3 so the lunar tides are 2.64552 times as large as current tides. (Solar tides are about 45% those of the moon currently). Actual local tides vary quite a bit, but in general, they would be over twice as strong. This would affect ocean life as well as seaports, etc.
**Axial tilt is complicated** - I have seen frequently quoted that without the moon the axial tilt would vary up to 85 degrees, but I've also [read that the axial tilt would vary by no more than 10 degrees](http://www.astrobio.net/news-exclusive/the-odds-for-life-on-a-moonless-earth/) based on newer calculations that include the effects of the other planets. My guess is that the axial tilt would be a bit more tightly regulated than today -- lots of non-linear factors. For example, if Jupiter were a lot closer, the moon would actually be a destabilizing influence on axial tilt.
**Earth's rotational slowdown** would also be proportional to the tidal forces, i.e., the earth's current daily rotation slows down by around 20 millionths of a second per year. With this scenario, that change to about 50 millionths of a second per day per year -- more frequent leap seconds.
**Moon orbital speed increases**. For circular orbits, orbital velocity is proportional to 1/radius, so the moon will speed up from 0.635 miles/sec to 0.759 miles per second. Since the orbital path is also 19.45 percent shorter, the orbital time is 42.68% shorter -- i.e., sidereal month (360-degree revolution) changes from 27.3 days to 19.1 days. A synodic month (new moon to new moon) changes from 29.5 days to 20.15 days
**Solar eclipses are more frequent and longer in duration.** The Moon orbits the Earth more frequently - thus more opportunities for passing between us and the Sun. Many moon passes do not have the moon shadow crossing the earth because the moon's orbit is inclined to the earth orbit around the Sun so the shadow passes under or over the earth. With the smaller orbit, there will be fewer misses one a percentage basis. The Sun is about 400 times the distance of the moon and about 400 times the diameter of the moon, so eclipses are almost perfectly matched so we sometimes see total eclipses and sometimes see annular eclipses -- not anymore, there will be no annular eclipses. Currently, under ideal conditions, the maximum full umbra of the moon is about 166 miles wide on the earth allowing for a little over 7 minutes of maximum full totality. Full eclipses over 7 minutes are very rare, everything has to be lined up in a nearly optimal fashion.
Shadow width on earth is now larger because the moon is larger and closer. These combine to make the shadow significantly larger - about 230 miles across. The increased orbital speed of the moon decreases transit time (offsetting the increased shadow size due to distance). Without complicated math and lots of new assumptions, exact figures are not possible, but I believe that assuming the eclipses would be about 15.7% longer on average because of the increased lunar diameter is a good first approximation. The larger umbra projected on the earth also means that around 30% more people will see each solar eclipse.
---
Lunar surface gravity is now 15.7% greater than before and the gravity well is 55% deeper so lunar missions just got harder. On the plus side, the trip won't take quite as long.
The earth-moon barycenter has been moved from about 4700 km to 6100 km from the earth's center -- still within the earth though. This will result is a slightly more pronounced wobble (and more frequent) in the earth's orbit.
The barycenter change may also cause slightly more seismic activity, especially when combined with the increased tidal stress. Perhaps slightly more weather variation too - [tidal flows are thought to affect weakly some aspects of our weather.](http://www.accuweather.com/en/weather-news/do-full-moons-affect-weather-p/40127763)
Many animals cycles will be affected due to brightness and frequency of the lunar cycles. Some people will also have their sleeping habits changed. Currently, there is little correlation of crime to the lunar cycle, but the increased brightness could deter crime.
Everything based on lunar calendars will either change or ignore the changed lunar mechanics. Jewish, Christian, Islamic and Chinese calendars would be included.
---
Actual night sky moon would be a little larger than calculated above as this was based on center to center distance as would be accurate when the moon is on the horizon. When the moon is directly overhead you are somewhat closer because of the earth's radius (whether the moon is 200,000 or 238,900 miles away). For the moon remaining a fixed size, its apparent diameter would appear 19.84% larger when directly overhead instead of 19.45% when at the horizon, so the effect is small.
A similar effect also occurs in that the surface of the moon is closer too -- light reflecting off the center of the moon will be just a little closer and correspondingly more likely to impact the earth and thus brighter. Again, the difference is minor. |
26,013 | <p>Can a planet possess more than one ozone layer? Can multiple ozone layers cause more harm? If one ozone layer had a hole, would the other(s) act like a backup shield to harmful rays from a star?
Assume the star is similar to the Sun and the planet is habitable.</p>
<p>Thank you!</p>
| [
{
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"author": "Youstay Igo",
"author_id": 13449,
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"pm_score": 1,
"selected": false,
"text": "<p>As far our current knowledge of atmosphere and oxygen bonding types stands, no, multiple layers of ozo... | 2015/09/20 | [
"https://worldbuilding.stackexchange.com/questions/26013",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/13744/"
] | Can a planet possess more than one ozone layer? Can multiple ozone layers cause more harm? If one ozone layer had a hole, would the other(s) act like a backup shield to harmful rays from a star?
Assume the star is similar to the Sun and the planet is habitable.
Thank you! | Note: there is no such thing as an ozone *layer*. What is called ozone layer, as if it were a sort of crystal shell high in the atmosphere, is actually a volume of increased ozone density, so that the density function with height behaves a little like this:
```
%
| #####
| # ###
| ### ###
| ############ ############
+------------------------------------------------------> outer space
```
But ozone density is never zero anywhere. As per @Alpha3031's answer, you can have more or less temporary conditions in which you get ozone near the ground from photochemical smog, or near the border of the ecosphere, or anywhere in between.
So "more than one ozone layer" would imply a density function more or less like this:
```
% Second layer
| First layer ######
| #### # ##
| # ## # ##
| ## ###### #####
| ###### #########
+------------------------------------------------------> outer space
```
Question 1: "More than one ozone layer".
========================================
**Yes, but it's tricky**
The ozone layer is actually a dynamic phenomenon taking place in a volume of space where oxygen density, ultraviolet light from the Sun and (photo)catalytic processes from several substances (e.g. chlorine from chlorofluorocarbon compounds) interact in a narrow range of ways.
So the greatest problem is having a high enough atmospheric column where the oxygen concentration is *just right*. This requires a shallow gravitational potential (the shallower, the best), which means a large, not so dense planet, and this has its drawbacks (technology as we know it is hugely based on iron and elements heavier than iron). Also, atmospheric pressure at sea level depends on the height of the atmospheric column.
Once we have enough oxygen in the air to work, we can pursue two different avenues. With reference to the ASCII graphics above, you either raise a second "hump" far enough from the existing one, or you spread the one hump you have, and drive a "wedge" in the middle to split it into two.
* two different ozone sources. One is the Sun; the other "hump" would need to be a source at the right wavelength originating in the opposite direction, from the surface, and could not obviously be reflected from the Sun (UV at that wavelength are blocked by the ozone layer, and *that* is what creates the ozone layer in the first place). One possibility could be secondary ionization from shorter wavelength UVs, that do not get absorbed by the ozone layer (I'd need to check the transmittance curve of ozone - if it's flat at the key frequency and below, we're out of luck: there would be no "shorter, unabsorbed wavelength"). These "UV-D" rays would penetrate a bit more, hit some replenishable atmospheric constituent - perhaps nitrogen - that's denser than ozone, and release their energy as less energetic UV rays that would get refracted and, if these newborn UVs are the right frequency, generate more ozone "some way down".
This phenomenon *already happens* in the atmosphere with normal ozone, which is one factor, together with atmosphere mixing, that makes the ozone layer "thick": it's actually several intertwining layers that scatter and amass. You'd need to do it with a different substance so that the separation between the two "humps" is larger, or you'd end up with a very thick, but single, ozone layer.
* one creation, two destruction mechanisms (standard spontaneous recombination being one). The ozone is generated in a thicker layer thanks to a shallower gravitational potential or a larger UV input from the Sun, then this large hump is split into two by e.g. some gas that deposits in the atmosphere at a specific height (we're doing *wild* assumptions on atmospheric diffusion and upper-atmosphere winds...). The gas is a sort of super-[halogen](https://en.wikipedia.org/wiki/Halogen), a super-chlorine or super-bromine, and catalyses the 2O3->3O2 ozone-killing reaction with such efficiency that where the gas is, no ozone at all can abide and you have a deep "wedge" separating two "humps". As a result, to all intents and effects you've now got *two* ozone layers, and only need to explain how the catalytic gas layer is kept together.
You could have some unknown process (high energy collisions, but with what?) generate [unumseptium](https://en.wikipedia.org/wiki/Ununseptium) atoms in the upper atmosphere. Its reactivity against ozone ought to be frightfully high (**update**: it actually isn't, see Wikipedia), even with a half-life of milliseconds, and the small half-life could help explain the localization of the layer - Uup atoms don't wander far from their birthplace before alpha decaying.
Another more promising possibility, and one which already happens, is you have a volatile molecule where a sufficiently evil halogen is bound to something keeping it quiet. Then the molecule diffuses in the high atmosphere, and *almost* the same UV rays that produce ozone destroy it, thus freeing the halogen atom, which proceeds to destroy ozone before combining with water vapour or hydrogen or something else and precipitating away. This is what happens now with chlorofluorocarbons.
You might also imagine a large fleet of aircraft with some ozone-harmful chemical in the exhaust fumes (this also happens in reality).
Question 2: "Can multiple ozone layers cause more harm?"
========================================================
Ozone layers do not cause harm *per se*. What they do is intercept radiation and either absorb it or reflect it back at the same wavelength or at a longer one ("greenhouse effect").
In the appropriate circumstances both phenomena might be either harmful or beneficial: think some organism that needs radiation at a specific wavelength, or a planet that would be too cold unless some of its thermal emission was bounced back to heat it a little more. The same layer would be harmful to the former and beneficial to the latter.
Question 3
==========
**If one ozone layer had a hole, would the other(s) act like a backup shield to harmful rays from a star?**
Not entirely. What would happen is that the depletion of one layer would increase radiation on the surface, but it would depend on the amount of the ozone shielding left. The layers are not "redundant", each one is there because of a specific cause.
Also, depletion of one layer would increase radiation in the volume of air where the second layer is, and might then lead to the thickening of the second layer, leading to a null net effect on the surface (as far as radiations go). The thickening of the second layer might also have other effects, some beneficial and some harmful. |
26,175 | <p>Imagine a world where a creationist situation holds: God (or an alien master species, if you prefer) created all the species you see in the world today, and there will never be any others. </p>
<p>Are there any real world, science based mechanisms that could prevent evolution, and allow this world to persist without speciation? I want to avoid continuous intervention by the creator.</p>
<p>This question was inspired by <a href="https://worldbuilding.stackexchange.com/questions/26115/would-there-be-evolution-on-a-perfect-world">Would there be evolution on a perfect world?</a></p>
| [
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"text": "<p>Sure. You'd need a new biological paradigm where children are randomized instead of combining traits ... | 2015/09/22 | [
"https://worldbuilding.stackexchange.com/questions/26175",
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] | Imagine a world where a creationist situation holds: God (or an alien master species, if you prefer) created all the species you see in the world today, and there will never be any others.
Are there any real world, science based mechanisms that could prevent evolution, and allow this world to persist without speciation? I want to avoid continuous intervention by the creator.
This question was inspired by [Would there be evolution on a perfect world?](https://worldbuilding.stackexchange.com/questions/26115/would-there-be-evolution-on-a-perfect-world) | The simplest way would be to **prevent mutation** and modify sex (you do not *need* sex in the world, but if you *must*...) in such a way that, for example, the male contributes *nothing* except the initial stimulus (which makes this essentially parthenogenesis, and that's why sex, or better, *gender* is not mandatory - you always can have homosexual intercourse as a matter of course, as it happens with Eric Flint's gukuys in [*Mother of Demons*](https://en.wikipedia.org/wiki/Mother_of_Demons)).
All individuals are XXY triploids, and inactivation of the Y chromosome happens "at random" (this allows any ratio of male to female, depending on the probability of inactivation). XXY genotypes have male phenotype, XXy genotypes are naturally female. This kind of genetic setup is perfectly possible and naturally occurs (except for the parthenogenetic reproduction twist) in humans, where [it is an anomaly](https://en.wikipedia.org/wiki/Klinefelter_syndrome). But there's no reason for it to be.
All creatures would then be identical clones genetically, but could (and probably would) sport differences, even large ones, due to [epigenetic factors](https://en.wikipedia.org/wiki/Epigenetics).
Also, depending on what the *cue* actually *is*, it might pose an interesting problem for birth control. Since all the needed machinery is self-contained in the female, sex for nonreproductive purposes could in effect be made impossible (meaning that *any* intercourse results in conception), or so awkward as to negate any recreational value, which might appeal to both deities and advanced aliens.
This removes most mutations due to recombination between different DNA sets.
As to how to prevent other kinds of mutation, the DNA helix gets routinely unwound and split in order to allow cell duplication. There already are enzymes that correct some common DNA replication errors. "All" that would be needed would be a super-enzyme, which we could call *[DNA-reed-solomonase](https://en.wikipedia.org/wiki/Reed%E2%80%93Solomon_error_correction)* :-), capable of detecting errors and either repairing them if possibile, or otherwise triggering the [cellular self-destruct mechanism](https://en.wikipedia.org/wiki/Apoptosis).
Such an enzyme could never have evolved (naturally), but a sufficiently advanced alien Seeder species might not find it difficult to build it from scratch.
A possible side effect would be longevity, perhaps even immortality, and complete immunity to most forms of cancer, not unlike the aliens in Asimov's [Hostess](https://en.wikipedia.org/wiki/Hostess_%28short_story%29).
Another effect would be a strongly reduced capability for the species to cope with environmental changes through natural selection and random mutation. This might be no great problem for a technological civilization, but for 99.999% of Earth history, it would have been a sure ticket for racial extinction.
Update: couldn't the repair mechanism itself fail?
==================================================
(@Peteris's objection)
Yes, and on a cell-by-cell basis, it will often do just that.
But the "mechanism" is not a simple reasonably-soft-fail enzyme system such as *evolved* creatures possess. It is rather a *designed* computer program implemented with amino acids.
First of all it would have to fail in a *zygote*, otherwise the host would only get common cancer, and anyway the mutation would not get inherited.
Then, *by definition* the change would need to break the main cellular repair mechanism, and *the organism has no others*. God or our aliens never saw the need for them, and actually had a good reason not to provide them: we want defective cells to *die*.
So *this* pro-evolutionary change would actually be *counter*evolutionary, since it would expose the host to all kind of cellular damage against which it would have no resistance. Given the rate at which random mutations would occur and accumulate during its early development, it would be extremely unlikely that a mutated foetus could even come to term.
We (the aliens or god) can further improve our game in two ways. One: since the child is a genetic clone, we need no placental barrier. The foetus is inundated by the mother's enzyme in addition to its own. This has no effect on perfect replicas, but mutated children die stillborn.
Two: the planet itself could be abundant in any one of (or several) mutagenic compounds or phenomena (UV radiation, natural radioactivity...). Protected individuals get no cancer, while any unprotected individual will quickly develop several.
To have a mutation in the enzyme, a point mutation or even a series of point mutations would not be enough. We'd need for the enzyme to change in such a way that *some* further mutations will be permitted, while oncogenic ones will still get eliminated.
This is on the same scale of an English spell checker that somehow gets corrupted during the copy, but its SHA256 hash remains the same, *and* the resulting program turns out to not only still work but to have become a working *German* spell checker (I've heard this kind of hypothetical occurrence be referred to as a *Minerva mutation*, from the [Roman goddess](https://en.wikipedia.org/wiki/Minerva) that was believed to have sprung, already adult and clad in armour, from Jupiter's head).
Chances of a Minerva event are in theory not zero, but I feel they're vanishingly small. This species' designers would have worried much more about the possibility of, say, a [Chicxulub impact](https://en.wikipedia.org/wiki/Cretaceous%E2%80%93Paleogene_extinction_event).
A closer look
=============
This is a bit of a hen and egg problem, so let's see it in practice.
Our alien engineered DNA can be represented like this (actual order is not important):
```
[H][CHECK][ BODY ]
```
where BODY is the DNA required by the cell, CHECK is the DNA that codes the "compare to plan, then repair or kill" mechanism, and H is the "plan" hash.
The CHECK part translates into a very large molecule (megaDalton range) with [helicase](https://en.wikipedia.org/wiki/Helicase) capability, a sort of specialized polymerase. The molecule attaches to a DNA strand and "walks" through it generating a [hashing/correcting bubble](https://en.wikipedia.org/wiki/Transcription_bubble). At the end of the process it has calculated the DNA "hash" and compares it to its expected value; if the check fails, cellular death is triggered. At any one moment every DNA molecule in the body could be examined by up to a dozen such *correctases*.
A random mutation can then occur in one of three places:
* B mutation. This is the most likely, since the C (CHECK) part will probably be no more than 5% of the total DNA. Helicases and polymerases occupy around 1% of human DNA, and this engineered DNA is very likely to be much more compact. In percent, I think a 1:20 relation is a good ballpark figure. Anyway, a B mutation will be caught by the intact C molecule and either repaired or, if not possible, killed.
* H mutation. Enormously unlikely due to its small size, it will nonetheless happen than the H sequence mutates. When it happens, lots of corrupted C molecules are generated that will routinely misinterpret cellular DNA as corrupted itself, thereby behaving like a fast-acting cellular poison. The mutated cell will be the first to die, and will likely bring down several hundred of the nearby cells before the mistaken correctase is finally degraded. Something remotely similar happens, on a much larger scale, with some kinds of poison (e.g. that of some snakes or that of the [brown recluse](https://en.wikipedia.org/wiki/Brown_recluse_spider) spider; if you google that, be aware that the images may be quite disturbing). However, the net result is that this kind of mutation can't be inherited.
* C (CHECK) mutation. This is more promising. There are several kinds of mutations which can affect the correctase molecule:
+ mutations that make it believe *any* DNA is always corrupt. Same as the H mutation case.
+ mutations that stop it working altogether (e.g. it can no longer bind to the DNA strand).
+ mutations that stop it from being lethal (either by stopping it from detecting changes, stopping it from initiating cellular death) but keep it working as a correcting enzyme.
But the main problem here, which would make it impossible as a natural occurrence, is that since every cell is routinely drenched in the correctase produced by itself *and its immediate neighbours*, any lessening in any one cell's correctase lethality would avail nothing. The cell would still be killed by its neighbours.
To survive, all cells must be mutated (or synthesized) in the same way, all at once or after being kept separate. Or you need to have a single cell with *no neighbours*. Even the zygote cell is not "alone", it is connected to the mother organism.
"Life will find a way"
======================
This is @MikeNichols' conclusion, and from the above scenario I would conclude that he's wrong... **except he's not**. He would be (of that I'm quite certain) if the organism existed alone, *in vacuo*. But no organism ever exists in an ecological vacuum (the closest approximation I'm aware of are Leo Frankowski's Mitchegai, [an eptalogy euthanised in 2004](http://heliologue.com/2010/06/08/kren-of-the-mitchegai-2/)).
And the correctase mechanism is **expensive** - it needs specialized machinery that has an operating as well as a replication cost. A sizeable organism would have no trouble in keeping up the whole show, but a *micro-organism* would be hard pressed to do the same. So our alien engineers may have stopped evolution *in higher organisms*, but they can't reasonably stop evolution *in microbes*. And as far as we know, without a (healthy) microscopic biota, life is not possible.
So we have a life pyramid where the top 10-15% is immune from evolution, and the lower organisms are free to evolve. While the middle layers may still be controllable by the 15% nobility, I suspect that a good 50% of the total planetary biomass would be logistically unreachable.
And let's not forget that this setup is the exact opposite of *biodiversity*. Sooner or later some pathogen will evolve that finds a suitable *pabulum* in those perfectly engineered, static, possibly unageing higher organisms, **and will kill them all**. Won't they develop genetic immunity? Well, any other *im*perfect organism very likely would. But the Creators made sure this couldn't happen... |
26,225 | <p>An alien race, for reasons of their own, have decided that it's important to make the third and fourth planets in our solar system about the same size and mass. Since they have a strict moratorium on altering planets with clearly visible carbon-based life on them, Mars is the object of their "affections". As a result of their cultural biases, they love iron. Any time they need/want to increase the size of a planet, they use iron to do it. (Yeah, I don't get that either but whatever, aliens, am I right?)</p>
<p>On the day of the drop, they position their ultra-mega cargo freighters full of iron around Mars then let all those gigatons of iron just fall Mars-ward. As you might imagine, the fireworks are spectacular. After the freighters move away, the planet cooling ships move into position but right before they start operations, an urgent call from the Supreme Dear Leader comes in demanding that his entire planet be air-conditioned and the cooling fleet is to report, pronto!</p>
<p>Iron parameters:</p>
<ul>
<li>Initial altitude: 150km (all ingots enter freefall form this height)</li>
<li>Iron initial temperature: 250K </li>
<li>Speed relative to Mars' surface: 0 m/s</li>
<li>Individual Iron Pieces: 100 m^3 ingots </li>
</ul>
<p>Mars must then cool off on its own. With the cooling fleet gone for an indefinite period of time, <em>how long will the aliens have to wait for Mars to cool down to a comfortable temperature for carbon-based life after dumping all that mass on Mars' surface?</em> Assume that atmospheric insulation/cooling effects can be ignored.</p>
<p>Altering Mars' orbit or the orbit of any of the other planets isn't a concern for these aliens, all they care about is Mars. Besides, they have the capacity to "nudge" planets into stable orbits.</p>
<p>(I realize that this is a fairly fanciful way of asking how long it would take to cool off Mars if you dumped enough iron on it to make it the same size as Earth, but it's more fun to write it this way. I also realize that aliens with these logistic capabilities can do pretty much anything they want.)</p>
| [
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"text": "<p>I’ll take a rough historical (and non hard science) stab at an answer.</p>\n\n<p>Infant Earth’s theorized... | 2015/09/23 | [
"https://worldbuilding.stackexchange.com/questions/26225",
"https://worldbuilding.stackexchange.com",
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] | An alien race, for reasons of their own, have decided that it's important to make the third and fourth planets in our solar system about the same size and mass. Since they have a strict moratorium on altering planets with clearly visible carbon-based life on them, Mars is the object of their "affections". As a result of their cultural biases, they love iron. Any time they need/want to increase the size of a planet, they use iron to do it. (Yeah, I don't get that either but whatever, aliens, am I right?)
On the day of the drop, they position their ultra-mega cargo freighters full of iron around Mars then let all those gigatons of iron just fall Mars-ward. As you might imagine, the fireworks are spectacular. After the freighters move away, the planet cooling ships move into position but right before they start operations, an urgent call from the Supreme Dear Leader comes in demanding that his entire planet be air-conditioned and the cooling fleet is to report, pronto!
Iron parameters:
* Initial altitude: 150km (all ingots enter freefall form this height)
* Iron initial temperature: 250K
* Speed relative to Mars' surface: 0 m/s
* Individual Iron Pieces: 100 m^3 ingots
Mars must then cool off on its own. With the cooling fleet gone for an indefinite period of time, *how long will the aliens have to wait for Mars to cool down to a comfortable temperature for carbon-based life after dumping all that mass on Mars' surface?* Assume that atmospheric insulation/cooling effects can be ignored.
Altering Mars' orbit or the orbit of any of the other planets isn't a concern for these aliens, all they care about is Mars. Besides, they have the capacity to "nudge" planets into stable orbits.
(I realize that this is a fairly fanciful way of asking how long it would take to cool off Mars if you dumped enough iron on it to make it the same size as Earth, but it's more fun to write it this way. I also realize that aliens with these logistic capabilities can do pretty much anything they want.) | Lets start by ignoring that for deep planetary pressures, iron is compressible and that it expands when it is heated.
**Basic facts**
```
Mars mass: 6.4171e23 kg
Earth mass: 5.97237e24 kg
Mars mean radius: 3389.5 km
Mars surface acceleration: 3.711 m/s^2
Iron density: 7850 kg/m^3
volume of a sphere = 4 / 3 * pi * r^3
radius of sphere = (volume * 3 / 4 / pi) ^ (1/3)
Mass of iron = m(Earth) - m(Mars) = 5.33066e24 kg
Volume of iron = mass / density = 6.79065e20 m^3 or 6.79065e11 km^3
Gravitational Constant: 6.67385e-11 N m^2 / kg^2
```
Let us model the required iron as a spherical shell of iron with an inner radius equal to that of mars plus 150 km. So, what is the outer radius? We know that the total volume of the hollow sphere must be the total volume of iron minus the volume of the hollow interior.
```
vMars = 4 / 3 * pi * 3389.5^3 = 1.63116e11 km^3
vInner = 4 / 3 / * pi * 3539.5^3 = 1.85744e11 km^3
vOuter = vInner + vIron = 1.85744e11 + 6.79065e11 = 8.64809e11 km^3
rOuter = (vOuter*3/4/pi)^(1/3) = 5910.31 km
vIronMars = 8.42181e11 km^3 (calculated below)
rIronMars = 5858.3 km
```
So, our iron to be dropped consists of a hollow ball of iron with an inner radius of 3539 km and outer radius of 5910 km. At the inner edge of the iron, the downward acceleration would be the acceleration due to Mars alone as the net contribution of the iron mass would be zero for all points inside the shell. At the outer radius, the acceleration would be based on the mass of the entire Earth.
```
accelInnerInitial = accelMarsSurface * (marsRadius / rInner)^2 = 3.711 * (3539.5/3389.5)^2 = 3.403 m/s^2
accelOuterInitial = accelEarthSurface * (earthRadius / rOuter)^2 = 9.8066 * (6371/5910.3)^2 = 11.395 m/s^2
```
The differences in acceleration clarify the problem with the iron shell assumption, the iron blocks would crash into each other as they fall. We'll simply ignore this problem by and large.
So, what is the impact velocity of the inner shell? Either we could do calculus since the acceleration increases as the shell falls closer to Mars, or we can take advantage of the formula for gravitational potential:
```
Gravitational Potential, V(x) = -G * M / x where G is the gravitational constants, M is the mass of the planet and X is the distance to the planets center.
```
Note that V(x) is always negative and approaches zero as distance approaches infinity. Since kinetic energy = 1/2 \* mV^2 and a falling object converts gravitational energy to kinetic energy we can figure out the impact energy and velocity without having to integrate over radius with variable acceleration.
For example, consider the case of falling from infinity to the surface of Mars.
```
F(x) = -GM/x thus F(3389500) = - 6.67385e-11 * 6.4171e23 / 3389500 = - 1.2635e7 J/kg.
```
Kinetic energy change will have the same magnitude as the gravitational potential energy change due to conservation of energy.
Solving for kinetic energy for velocity, `V = sqrt(2*E/m)`, and using -F(3389500) for E.
```
V = sqrt(2*1.2635e7/1), V=5.027e3 meters / sec -- this is in perfect agreement with the published value for the escape velocity of Mars, a useful check on our method.
```
For a mass dropped from 150 km altitude. F(3539500) = -1.20996e7 J/kg. The difference between F(surface) and F(150 km up) is 5.35e5 J/kg, which means the impact velocity is 1035 meters/second if atmospheric drag is ignored. Given the total mass of iron being dropped, this seems like a good assumption.
What about the outermost shell? similar math, but it based on total earth mass as all of the iron lies inside the outermost shell-- Mars radius is now much larger due to all of the rest of the iron already added to Mars. Again ignoring comprehensibility of the iron (and Mars itself), our new Mars planetary volume is the old volume plus the volume of all of the iron:
```
volumeIronMars = 1.63116e11 + 6.79065e11 = 8.42181e11 km^3.
```
Solving for radius yields 5858.3 km so the outer shell will fall a distance of only 52 km, however it does so with the full acceleration due to Earth mass, about 9 times Mars mass.
```
F(OuterShell) = -GM/x = -6.67385e-11 * 5.97237E+24 / 5910.308044 = -67439276 J/kg
F(IronMarsSurface) = -6.67385e-11 * 5.97237E+24 / 5858.3.303939 = -68037933 J/kg
Change in outer shell potential from falling = 5.99e5 J/kg`
```
The difference in energy gain for the inner and outer layers is close enough, that I will just use the geometric mean value of the inner and outer shells as the average energy change (instead of resorting to calculus to compute a more accurate number), i.e., 5.662E5 J/kg
So, finally what is the temperature change? Iron has a specific heat capacity of around `0.45 joules / gram * deg` or `450 J/kg*deg` so we can finally compute the temperature rise as `5.662e5/450 or 1260 degrees Kelvin,` so **the final iron temperature is about 1510 Kelvin or 1237 Celsius or 2258 Fahrenheit** - this is considered white hot though there is still a yellowish orange appearance -- about the same as a candle flame. Iron melts at 1538C so not molten iron, but it will be much softer / more plastic than iron at Earth surface temperatures.
The incandescent IronMars will be very noticeable from Earth.
Calculation time to cool off is another set of nonlinear problems too. I want to stop here because there are 2 very different solutions.
1. The iron rests upon the old mars surface or
2. the iron continues to migrate down towards Mars core due to the impact load and great pressure of the softened iron overburden.
In reality, I think that there would be major penetration of iron. It is a definite possibility that the bulk of the iron will descend further, perhaps even to join with the existing iron core. The extra heat from compressing the crust might be enough to melt all of the iron, in which case it is certainly heading to the core. If this happens (and I think it would) it will take hundreds of millions of years to become Earth-like or Mars-like. Also note that the downward migration of the iron releases additional heat, so if the effect is significant it is also unstoppable, the core size is going to increase greatly.
Note that my basic model was unrealistic from the start (assuming a solid iron shell), in reality dropping from space ships the average drop height would be significantly higher and more energetic.
One major secondary effect, Mars rotation period would become about *10 times* as long since the iron has to accelerate up to match the rotational velocity of Mars. This would add another large quantity of kinetic energy to the iron (enough to cause some iron melting near the equator)
So how long to cool? Don't know, and its late and I'm tired so I'm stopping for now.
---
The assumptions of the Virial theorem do not apply in this artificial case, i.e., we do not start with a stable gravitational bound system of widely dispersed matter. We have a collection designed to collapse upon itself within one day. Even if we allow that the iron will interact and heat up during the infall, nearly all of the radiant energy will terminate on another packet of iron during infall. To reduce this effect, it is necessary to spread out the iron -- but this raises the distance of the drop more than offsetting the increased heat loss. There is also very little time for the heated iron to radiate away its heat before impact. So I don't expect any significant percentage of the heat to radiate away during infall.
What happens to the atmosphere of Mars? It too is heated to incandescence and will remain so as long as the iron remains that hot. I don't expect much of the atmosphere to be lost quickly since the escape velocity for IronMars will be even higher than Earth and the RMS gas velocity is only about 1 km/sec.
---
I do have a quibble with the problem as posed, do the aliens have antigravity? You can't simply drop iron from orbit, a straight drop required your cargo ships to simply hover in place. If you can do that, why did you have to make such a mess in the first place? |
26,626 | <p>In the vein of this question <a href="https://worldbuilding.stackexchange.com/questions/25899/anatomically-correct-gods">here</a>, I was wondering about the practicality of the mythical Grecian concept of the <a href="https://en.wikipedia.org/wiki/Hekatonkheires" rel="nofollow noreferrer">Hecatonchires</a>. Forget, for a moment, that these monsters are supposed to be invincible. Now, wonder how one such monster (with 50 heads and 100 arms) could be defensible.</p>
<p>I imagine a head array (all of them in a line, ear by ear) to be most inefficient, especially if the opposing side has snipers:</p>
<pre><code> _ _ _ _ _ _ _ _ _ _
/ / / / / / / / / . .\ *Can somebody say headshot times 50?
\_\_\_\_\_\_\_\_\_ U_/
</code></pre>
<p>Then, consider also that we need to fit 100 hand/arm mechanisms on this thing. If all of these limbs were located on the side of its torso, at the very least its midsection would be a huge, bullet-soaking pillar--even before we give each arm enough room to swing up and down without interfering with its neighbors.</p>
<p>So, assuming that this creature must be a bipedal humanoid-ish monster--i.e., no Mr. Fantastic's elastic limbs; there are bones in this thing's arms, although the length, number of elbows, etc. are debatable--how should this creature's parts be arranged?</p>
<p>In other words, <strong>what is the most practical way of constructing this ludicrous monster such that its extra heads and arms are useful</strong> (e.g., having the skulls arranged like parapet stones), <strong>and so that it could properly be deemed a formidable foe even in modern combat?</strong></p>
<p>(Note: I use modern warfare to exemplify the weakness of a "copy a human 50 times horizontally" design, though the Hecatonchires need not be foisted into our space-time continuum. Even in the mythic past, however, a monster with a spaghetti of flailing limbs, and for whom armor construction is nigh impossible (Hephaestus notwithstanding) still seems hardly defensible. Also note that <em>what</em> these things would be wielding in their 100 arms is another question altogether). </p>
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"text": "<p>I think the best way to use these guys in a modern setting is as ship captains. Instead of having an ent... | 2015/09/29 | [
"https://worldbuilding.stackexchange.com/questions/26626",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/14096/"
] | In the vein of this question [here](https://worldbuilding.stackexchange.com/questions/25899/anatomically-correct-gods), I was wondering about the practicality of the mythical Grecian concept of the [Hecatonchires](https://en.wikipedia.org/wiki/Hekatonkheires). Forget, for a moment, that these monsters are supposed to be invincible. Now, wonder how one such monster (with 50 heads and 100 arms) could be defensible.
I imagine a head array (all of them in a line, ear by ear) to be most inefficient, especially if the opposing side has snipers:
```
_ _ _ _ _ _ _ _ _ _
/ / / / / / / / / . .\ *Can somebody say headshot times 50?
\_\_\_\_\_\_\_\_\_ U_/
```
Then, consider also that we need to fit 100 hand/arm mechanisms on this thing. If all of these limbs were located on the side of its torso, at the very least its midsection would be a huge, bullet-soaking pillar--even before we give each arm enough room to swing up and down without interfering with its neighbors.
So, assuming that this creature must be a bipedal humanoid-ish monster--i.e., no Mr. Fantastic's elastic limbs; there are bones in this thing's arms, although the length, number of elbows, etc. are debatable--how should this creature's parts be arranged?
In other words, **what is the most practical way of constructing this ludicrous monster such that its extra heads and arms are useful** (e.g., having the skulls arranged like parapet stones), **and so that it could properly be deemed a formidable foe even in modern combat?**
(Note: I use modern warfare to exemplify the weakness of a "copy a human 50 times horizontally" design, though the Hecatonchires need not be foisted into our space-time continuum. Even in the mythic past, however, a monster with a spaghetti of flailing limbs, and for whom armor construction is nigh impossible (Hephaestus notwithstanding) still seems hardly defensible. Also note that *what* these things would be wielding in their 100 arms is another question altogether). | I think the best way to use these guys in a modern setting is as ship captains. Instead of having an entire bridge crew, this one guy could be issuing orders, reading and analyzing data, manning wheels and control stations, and generally doing the work of up to fifty people. Not only that, but since it's just one guy, there won't be any confusion trying to communicate: he's going to know everything.
In other words, I don't think they would be used in primarily combat roles. Just trying to fit one hundred human arms through a door doesn't sound easy, so unless these creatures are about the size of a centipede I don't want them leading any charges. Instead, logistics and machine operation are where they're going to excel.
For such jobs (or just in general), I'd say the best configuration is as a sort of sphere, with heads and arms at regular intervals. You could probably throw legs out entirely, as there are few cases where these creatures won't have at least a couple arms handy (pun). I'd bet there would be custom workstations built for them, with panels and screens in places where they can each reach a different head/arm.
If you still want to have these guys on a battlefield, perhaps they can drive specialized tanks. These tanks could be covered in cameras and viewports and feature a wide array of weapons, to the point where it would appear not to have a weak side. It could also serve as a mobile command post, as the hecatons will probably have some heads and arms available for coordinating troop movements and even piloting drones.
As a suggestion for a more medieval setting, I suggest the shield ball (pun?). Much like a shield wall, the hecaton will be covered by a series of fifty interlocking shields. The non-shielded arms will each carry a spear. To move, the hecatons will push off with the back spears and roll. Not only would this be absolutely terrifying, but the hecatons could continuously shift their orientation, moving fresh arms to the front and tired arms to the top or sides.
The shield ball could even be useful in modern riot control, but modern warfare really is more about hiding than anything else, and the hecaton's going to stick out like a sore thumb.
For an idea of the general shape of such a creature, consider the [Deltoidal hexecontahedron](https://www.wikipedia.org/wiki/Deltoidal_hexecontahedron). Each face of this shape would contain a head and two arms, albeit with ten empty spaces (I couldn't find a satisfactory 50-sided version). With this structure in mind, I'd estimate the hecatons would be from 6 to 8 feet tall (around 2m), and just as wide. I'd recommend making the heads a bit small to give the arms room for solid muscle structure. Due to the large number of awkward angles, such a creature would most likely smell terrible (they may quite possibly have invented aerosol deodorant before the wheel). Caloric intake will need to be higher than that of a normal human, but definitely not fifty times higher; different heads may have to take turns eating meals. Each head should be built to handle being pressed into the ground quite often, so I'm thinking flat noses and sunken eyes. |
29,270 | <p>It is the year 2037.</p>
<p>Mankind has identified a rogue planet <em>en route</em> to knock Earth out of stable orbit with the sun, and into a less fitting orbit of 110 million km (40 million kilometers shy of its normal orbit).</p>
<p>This planet is scheduled to come close enough to Earth in 2041 to throw it out of orbit, so mankind has around four years to come up with a plan. Earth will experience extreme heat for years after its destabilization. This may cause problems such as:</p>
<ol>
<li>Water boiling off of oceans.</li>
<li>Extreme seismic distress during preliminary stages .</li>
<li>Temperatures reaching a high of 240 degrees Fahrenheit.</li>
</ol>
<p>Scientists do not think that this encounter will seriously damage the Earth's body, but it will be extreme enough to make it completely uninhabitable, at least For people on the surface during its stage of deterioration.</p>
<p>Our only hope is to try to create a generation ship with enough supplies to last years until Earth calms down. After this point, landers will be used to reach the surface, where structures designed to withstand Earth's new environment will be waiting from before the apocalypse.</p>
<p><strong>New Technologies</strong></p>
<ul>
<li>The International Space Station has been given a face-job. Eight times the interior living space, with multiple docs to connect extra modules as living compartments and supply areas.</li>
<li>Advanced pharmaceuticals make an outbreak in space out of the question.</li>
</ul>
<p>Assuming these things, how can the governments of the world work together to survive extreme temperature changes, as well as the destabilization of Earth's ecosystem?</p>
<p>Other solutions are welcomed.</p>
| [
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"text": "<p><strong><h2>So, Nibiru finally makes it here - we've been waiting long enough.</h2></strong></p>\n\n<p><s... | 2015/11/08 | [
"https://worldbuilding.stackexchange.com/questions/29270",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/15131/"
] | It is the year 2037.
Mankind has identified a rogue planet *en route* to knock Earth out of stable orbit with the sun, and into a less fitting orbit of 110 million km (40 million kilometers shy of its normal orbit).
This planet is scheduled to come close enough to Earth in 2041 to throw it out of orbit, so mankind has around four years to come up with a plan. Earth will experience extreme heat for years after its destabilization. This may cause problems such as:
1. Water boiling off of oceans.
2. Extreme seismic distress during preliminary stages .
3. Temperatures reaching a high of 240 degrees Fahrenheit.
Scientists do not think that this encounter will seriously damage the Earth's body, but it will be extreme enough to make it completely uninhabitable, at least For people on the surface during its stage of deterioration.
Our only hope is to try to create a generation ship with enough supplies to last years until Earth calms down. After this point, landers will be used to reach the surface, where structures designed to withstand Earth's new environment will be waiting from before the apocalypse.
**New Technologies**
* The International Space Station has been given a face-job. Eight times the interior living space, with multiple docs to connect extra modules as living compartments and supply areas.
* Advanced pharmaceuticals make an outbreak in space out of the question.
Assuming these things, how can the governments of the world work together to survive extreme temperature changes, as well as the destabilization of Earth's ecosystem?
Other solutions are welcomed. | **So, Nibiru finally makes it here - we've been waiting long enough.
------------------------------------------------------------------**
**1) Four years for planning and making changes means the ISS is totally inadequate as a generational ship.** There is no reason to believe that the ISS will be any more inherently prepared for such usage than today. I.e., the ISS is dependent upon regular supply runs from earth to replace consumables such as the CO2 scrubbers, food, etc., as well as fuel to keep the ISS from deorbiting.
We don't know how to create a stable ecology good for hundreds of years, much less getting it all figured out and installed on the ISS in time -- esp. given the chaos on the Earth that will be occurring during those four years.
**2) The ISS will also become unlivable due to increased solar radiation (or something else)**. Unless the ISS is somehow given escape velocity, it will also be orbiting at 110 Gm and be expected to incur a 50 C / 90 F temperature rise. Possible to mitigate perhaps in 4 years, but you also need to protect against 37% more frequent solar flare and CMEs (that average a little more than 37% more intense). ISS systems will simply fail over time, e.g. solar panels do not last forever, the ISS cannot possibly manufacture them and you cannot have enough spares of everything to last for hundreds of years. You cannot have an industrial base needed to keep things working. Given all of the chaos, a sudden depressurization event seems more likely than today too.
What is the generational effects of null gravity? Unknown, but it is near certain that a future generation attempting to return to Earth would be unable to function well at 1 gee.
**3) Changing to Earth's orbital radius from 150 Gm to 110 Gm is not a temporary change**. The momentum transfer from the rogue planet (a.k.a. Nibiru) to Earth is a permanent change unless you have another planet or a second pass to restore the momentum. So, even a generational ISS would not help to repopulate the surface as it will remain inhospitable forever.
The projected average temperatures more likely average about 65 C / 147 F when your consider the difference in solar radiation (1/r^2 law) and blackbody radiation (T^4 law) assuming greenhouse effect remains proportional. Since CO2 emissions should pretty much stop, this may be true. Likely vulcanism effects are contradictory dust (cooling) and sulfur dioxide (warming) so net is hard to predict, but SO2 would persist longer, so perhaps somewhat higher temperatures are likely -- but would seem very unlikely to boil off the oceans. So perhaps Earth is not quite as inhospitable as you suppose.
BTW, living underground does not really solve the temperature problem in the long term as the increased surface temperature continually will seep down until it reaches thermodynamic equilibrium, i.e., same as the average surface temperature. This will take a very long time - hundreds or thousands of years if you are 100 meters or more under the surface.
**4) Antartica here we come -- reserve that prime beachfront property now.** Of course, guessing where the rising ocean will stop is a challenge. With a 50 C temperature rise, the average temperature in the interior would still be below freezing but the temperature at the perimeter would be well above freezing. There should be a reasonable large habitable zone. Raising crops will still be very challenging due to the long dark winters and weak sunlight in the summers, but some farming would be possible and doubtless quite effective if you have to grow lights in a greenhouse. If you are lucky, thorium cycle nuclear plants will be commercially available by 2037, but failing that, there are doubtless plenty of fossil fuels available on Antarctica - its not likely you are going to care much about man-made global warming. Thorium fuel cycle means you don't have all that complicated Uranium enrichment, etc., but failing that some CANDU reactors might be nice.
Weather patterns will doubtless be interesting and it may in fact get pretty hot during the summer, but people live in hot places today. I would expect it to be livable if not pleasant.
**5) Nibiru would be very likely be detected more than 4 years in advance.** Our space based detection tech is getting really quite good. You don't say how fast Nibiru is moving. If it is just moving at galactic speed (<100 km/sec), we are going to see it well in advance, automated systems are scanning the skies looking for asteroids, etc. and getting bigger and better. Compared to asteroids, Nibiru is a very large target and would be detected at a distance that would allow for more time considering the great distance it will have to travel before the big event. Consider that Sedna was detected at 86 AU and Nibiru would have to be larger to have the effect described. If Sedna were launched at 100 km/sec it would take 4.1 years to get here. Given the improvements in scanning and the larger size of Nibiru, I would expect that 10 or 20 years is more likely, even given an unusually high speed for Nibiru. I doubt we could make ISS generationally viable with 10 years, but with 20 years I could be more hopeful.
Hyper-velocity rogue planets are very much rarer, but are expected to travel up to 5% of the speed of light. At .05c (15,000 km/sec), we would not have much time, perhaps even less than 1 month.
But I think I have been totally underestimating the ability to detect Nibiru. If the planet is all at warm from the heat of formation or internal nuclear heating from uranium, etc. it will give off noticeable infrared. This means, we will be able to detect it from at least a couple of light years distance. I would also say that this is very likely. Even a hyper-velocity rogue due to hit in 2041 could already be detected by us in 2015. As the nearest discovered rogue, it would be intensely interesting and the race would be on to prevent Nibiru from messing up the Earth. Feel free to post the followup question.
**6) No reason to expect governments to cooperate.** I would say cooperation is quite unlikely. US and Canada are quite friendly in most ways today, but the northern territory might be prime real-estate. A US invasion of Canada does not seem impossible to me. China invading Siberia would seem very likely as they are not too fond of Russia already. When survival is at stake, the gloves come off. Use of nuclear weapons seems quite likely.
---
**Quibble** - A near pass from Nibiru would not leave Earth in a nice near circular orbit. At best you have have a major semi-axis of 150 Gm and a minor semi-axis of 110 Gm. It would be necessary to actually make 2 passes to result in a near circular orbit. The first pass to change orbit to a 150/110 Gm ellipse and a second pass when Earth nears perihelion to change the orbit to a circular one.
**Now the Real Problem.** Changing the momentum of the Earth in a single or pair of short-term events would be very stressful. What is the gravitational potential of the Earth relative to the Sun? E(potential) = - G \* (m1\*m2) / r
```
G = 6.67408 × 10-11 m^3 / (kg * s^2)
Sun mass = 1.988E30 kg
Earth mass = 5.972E24 kg
For e=1.5e11 meters, Ep = -5.28246e33 Joules
For e=1.1e11 meters, Ep = -7.20336e33 Joules
```
So, earth must lose 1.92909e33 Joules of gravitational potential to achieve the new orbit. How [much energy is this really in comparison?](https://en.wikipedia.org/wiki/Orders_of_magnitude_(energy))
```
Hiroshima bomb 6.3e13 J
The Tsar Bomba 2.1e17 J
Total annual global energy consumption 5e20 J
Total global fossil fuel reserves 3.9e22 J
Chicxulub impact 5e23 J
Total solar energy impacting Earth per year 5.5e24 J
Total solar output 1 second 3.8e26 J
Rotational energy of earth 2.1e29 J
Total output of sun per day 3.3e31 J
```
So, total output of sun for 58 days. Or the total solar energy hitting the Earth for 350 million days i.e., about 1 million years worth of solar energy.
**I suspect we have a little bigger problem than a new orbit closer to the sun.** I.e., the scientists assuring you the Earth would survive were lying to you and hoping you were too lazy or incapable of doing the math. The tidal forces are simply going to be over whelming. Without assumptions and doing the math I can't be sure, but I suspect the only way to transfer this much momentum in a short event duration is to have Nibiru impact the earth. In will also disturb the asteroids belt as well as Kuiper belt and Oort cloud objects. The local neighborhood is going to be unpleasant for a very long time.
---
Woke up this morning and realized some simple assumptions that make it possible to think about changing the orbit. Assume Nibiru is an Earth twin, this makes the Roche limit equal to 2.5 \* Earth/Nibiru radius. Earth radius is 6371 km, so closest possible approach of Nibiru would be 15972 km (center to center) to keep from breaking up the Earth. That is clearly too close, but a useful upper bound. The problem is that Nibiru would have to remain at the Roche limit for 6 days to transfer that much momentum, and of course Nibiru is actually making a fast flyby. So, the proposed momentum transfer is not possible without destroying Earth - actually breaking it into tiny pieces. No planet could impart enough of a change in a single high speed pass to keep from destroying Earth. Minimum speed of Nibiru would be high speed as it must fall toward the sun to approach Earth. Redoing the calculation for the planets grazing each other and I now know for certain that an impact is required to make the required momentum transfer in a single event.
I should also add that exploding Earth into millions of chunks will make for some unpleasant days for anyone trying to inhabit anyplace else in the inner solar system, given the high frequency of big honking meter impacts as well as innumerable smaller impacts. |
30,695 | <p>I'm making a world with magic and most if not all tech will run on mana. I have airships in this world but I'm having a hard time deciding how large across the world should be. I want - even with airships - for long distance travel to take months (cross a continent or from one continent to another). Should I set a slower airspeed than airplanes now, and have the world the same size as Earth, or increase the size of the world, or both?</p>
| [
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"text": "<p>Using <a href=\"https://en.wikipedia.org/wiki/LZ_127_Graf_Zeppelin\">LZ 127 Graf Zepplin</a> as... | 2015/12/01 | [
"https://worldbuilding.stackexchange.com/questions/30695",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/15668/"
] | I'm making a world with magic and most if not all tech will run on mana. I have airships in this world but I'm having a hard time deciding how large across the world should be. I want - even with airships - for long distance travel to take months (cross a continent or from one continent to another). Should I set a slower airspeed than airplanes now, and have the world the same size as Earth, or increase the size of the world, or both? | Using [LZ 127 Graf Zepplin](https://en.wikipedia.org/wiki/LZ_127_Graf_Zeppelin) as an example of a transatlantic airship flight from 1928, it took 111 hours to travel from Friedrichshafen, Tübingen, Germany to Lakehurst, New Jersey, United States of America, about 9,926km in length.
**Faster:**
In a similar airship that is capable of achieving the same speed of 89km/hr, on a similar journey across a Continental divide, the distance would need to be **150,000km** to achieve a two month journey taking 10 weeks.
This means your theoretical planet would need to be on a scale of **15x** the size of the Earth to achieve a similar journey over a longer time.
This massive world would probably increase the likely-hood of transition to air-travel as the speed to cross long distances would be a must for world spanning empires.
**Slower:**
If you wish for your airship to just travel slower to make the journey longer, to achieve a 2 month long journey taking 10 weeks,you would need to slow your airship to travel 6km/h to travel roughly 10,000km across an earth sized ocean.
In terms of world building, the slower option makes less sense as most people can walk faster than 6km/hr, and any naval vessel could easily outspeed this airship. Unless of course the ocean in your world is so acidic that the only way to traverse it is to fly above it!
**Between:**
Below is a quick table of some compromises between the above suggestions:
```
| Distance | Scale | Speed | Likeness to other modes of travel|
| 150,000km | 15x | 90km/h | Speed of Car |
| 100,000km | 10x | 60km/h | Speed of Early Model Steam Train |
| 50,000km | 5x | 30km/h | Speed of Horse Gallop |
| 20,000km | 2x | 12km/h | Speed of Runner |
| 10,000km | 1x | 6km/h | Speed of Fast Walker |
``` |
30,944 | <p>I'm writing a story, based vaguely off of the <a href="http://www.drivethrurpg.com/product/86467/Stars-Without-Number-Free-Edition" rel="noreferrer">Stars Without Number</a> system. There are lots of things bugging me, but by far the biggest issue is this: the military contractors and bounty hunters and the like are all congregating in the war-torn areas, waiting to be hired, instead of relaxing in luxury, waiting to be called.</p>
<p>There's mostly reliable, long-distance superluminal communication, but only in the sense that you can put a message on a ship (or into the ship's computers) and have that ship carry it, mostly reliably, between systems. </p>
<p>How can I explain why PMCs would do anything but stay at home, waiting to be hired to fight?</p>
| [
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"text": "<p>Well... I don't know if this is enough to constitute a complete and acceptable answer but here we go.</p>\n\n... | 2015/12/06 | [
"https://worldbuilding.stackexchange.com/questions/30944",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/5187/"
] | I'm writing a story, based vaguely off of the [Stars Without Number](http://www.drivethrurpg.com/product/86467/Stars-Without-Number-Free-Edition) system. There are lots of things bugging me, but by far the biggest issue is this: the military contractors and bounty hunters and the like are all congregating in the war-torn areas, waiting to be hired, instead of relaxing in luxury, waiting to be called.
There's mostly reliable, long-distance superluminal communication, but only in the sense that you can put a message on a ship (or into the ship's computers) and have that ship carry it, mostly reliably, between systems.
How can I explain why PMCs would do anything but stay at home, waiting to be hired to fight? | Not sure quite what definition you want to give of "being a mercenary", but I spent a few years as a contractor in Africa, Asia and the Middle East after leaving the Army, so I can tell you why I spent a bit of time wandering around the smellier parts of the world between contracts.
**Connections**
You get hired and find contracts by making sure people know you. I was in Special Forces for 6 years, and in a tiny community like that your reputation is everything. Once you get out it is the only way you get good contracts, too -- not by applying for them, but by getting cold-called by someone you know and already worked with before.
But the longer you've been out of the military where assignments aren't your decision and you meet new people as a matter of course, you wind up becoming slowly isolated. Whatever sort of work you have been doing is the only way you meet people if you're only in the ugly parts of the world when you're on contract. That means you only meet people who do the same kind of work as you, and pretty soon your old contacts change careers (nobody does this forever, not unless they get paid extremely well -- but its actually feast-or-famine, and that begins to wear on you). Over time your contacts go stale, contracts become less frequent, wars end, new wars start in places you've never been, rules change, industry players change, empires come and go, languages you know become useless, etc.
We watch all this firsthand, which is why we know that we can't count on being comfortable, ever, and absolutely none of us trust things like pension programs after watching entire governments implode overnight. That also means we don't have much faith in getting a next call while we're a world away sitting on our asses enjoying the good life. Yes, you do that a little, but only when you know you already have a contract lined up to go back to.
**Location location location**
So what does one do? Why do programmers looking for easy cash from VCs they can blindside with a storm of buzzwords migrate to San Francisco? Its one of the absolute worse places to *run* a company, but its one of the best for *starting* a company simply because the community is there. In the same way one might wonder why I would wander around a shithole like Baghdad or take a trip to Mali when job hunting? Because the community is there.
Its not just bases and checkpoints and whatnot. Those of us who have to stay there a lot begin doing more pleasant things with our time. Some start up private bars, open restaurants, hire stranded immigrant workers who were screwed over by their former employers and start a service shop that handles things people like us know are needed (vehicle repair, gear cleaning, safe parcel delivery, couriers, *good* alcohol smuggling, proper medical supply import, etc.). We tend to those sidelines when we're not on contract, meet local girls ("local" as in she's there, and so are you for the moment), train with each other partly as play (its fun) and partly to keep skills alive, etc. *and keep making contacts*. It takes a little effort, but you can make life comfortable for yourself in the middle of the never-ending nightmare that is most of the world.
Most of us are, if not friends, at least cut from the same cloth. We've had similar experiences. We like to swap lies (and the occasional true story) with one another over a drink. We like to roll and box with each other for fun. We have beer shoots on the weekends sometimes (loser buys for everyone). Few of us can train much back home. *People at home sincerely do not understand a huge part of our lives*. We come from the same dozen or so countries. We speak, if not the same language, the same 2 or 3 common pidgins. Its a comfortable place, even if its a rough one. And sure, maybe a few towns over people are getting their houses knocked over and roughed up by the local baddies or whatever, but *nobody* comes to mess with our little cobbled together neighborhood. So yeah, its less safe than living in, say, Austin, but its a lot safer than the general violence statistics for the region would make it appear. And the violence stats work in our favor anyway: fewer people show up who don't already know what they are doing which effects a self-selection for competence and prevents a flood of competitors from appearing out of nowhere.
**We're feeding off of the chaos**
Most of the world is not very well planned out. When a crisis occurs and a bigshot needs to go somewhere bad in a big hurry there simply isn't time to establish a strong guard force and mobilize it. Most countries don't even have decent diplomatic security forces (much less decent police -- or even decent people) so external contractors are a necessity.
Usually an office that is already in position will get a call at the 11th hour with a desperate need for diplomatic security (or whatever else). Not ten minutes later a few of us are running up and down the street knocking on doors, calling each other "Do you have any solid guys and a few locals you can bring on a run to X in two days?" and "Hey, do you still have that bigass armored bus? How about the bricked-out Mercedes and the Rhino, are they out of the shop yet?" and so on.
The next day we're all out, not officially on contract yet, but we're already rehearsing, making sure everybody knows what to do. One major advantage of working in a group like this is that you generally only need to rehearse actions-on, get guys new to a particular technique or scenario up to speed, and cover a few contingent actions. That's a *lot* different from having to rigidly train core skills because most of the trigger-pullers are privates who just left home for the first time. (The general age range of the guys I prefer to work with is 30~60 -- and don't let 60 throw you off, there is this freakish phenomenon we call "old man strength" and its totally real, and the *tactical maturity* of the older gentlemen tends to guarantee they don't have to exert themselves much in the first place, which is pure magic.)
A few days later we've swapped out our patches and hats for whatever logos the prime contractor has and are standing all clean and pretty at the airfield waiting to meet the guy who is paying for the party.
From the outside I suppose it looks like Xe (or Blackwater, or whatever they are now), or Triple Canopy or Aegis or whoever *appear* to be some full-time private military force you can just hire on short notice -- but that doesn't mean they have a barracks in Florida or Cape Town and are just waiting for the green light. Its *expensive* to have us around, just eating through corporate profits. They assemble their forces from people they already know *right then* and roll. (The *really* huge contracts that cover a whole warzone may wind up being slightly different in effect, because those contracts may be ongoing for 5 years at a time, but even those stories must eventually end.) The only people with some level of job security are the country/region managers and up. The polite girl who used to call me from Virginia to tell me my travel routes, for example, had *much* better job security than any contractor ever would.
That's just diplomatic security. There are plenty of other contracts like training foreign militaries, providing direct QRF support, high-value recovery (sort of borderline legally), K&R response, countersurveillance, and some other stuff for example, but the way you get to know each other and find your next job tends to be the same: by being out there, being well known, being likable, making friends, working lower-paying contracts that involve a ton of people to have a chance to meet some other guys, and *remembering who the dirtbags were* so you can avoid them in the future.
It sounds bad to say "we feed off the chaos", but that's true. But its also true that the chaos is never-ending, people suck, nothing is stable, and nobody gives a crap about your problems but you and maybe your family. Its not going to get any better, and it hasn't been any different throughout history -- we're just this season's leaves, soon to be swept away whether we spend them shivering in our beds trying to stay safe or out there sweating, trying to get some cash together so we can get out of the crappy places of the world and start a family somewhere less screwed up.
**So in the end...**
Why do gravitate to the eye of the storm? Because in a world with no job security you have to make your own luck.
**What about the organizations?**
The above discussion was all about the people involved, explaining some of the reasons why *I* would occasionally hang around nasty places while off contract or at least spend my off-days while on contract making sure I had a good shot at having another contract one later on (or finding a better one right away if the current one paid peanuts but was super dangerous for no reason). That's all about us guys who are on-off contract every few months (or whenever the phone rings) and have no job security. The companies that are actually getting the contract awards have slightly different, but related, reasons to always have a presence in a disturbed region.
Contracting companies don't really have any job security, either. Any given conflict will eventually end, and -- contrary to the hilariously off-base conspiracy theories that PMCs "cause conflict to profit off them" -- peace could break out at any time. But this is Earth. We can rest easy in the knowledge that *war is a natural state of mankind*. The trick is, just like owning a chain of grocery stores or selling fire insurance, you have to diversify your presence and product offerings to make sure you've got market coverage if you want your company to survive beyond a sing huge conflict. (A *lot* of PMCs have come and gone just around the Iraq conflict. Others will come and go elsewhere. A few have a semi-permanent presence on the eternally screwed up continents.)
When everything goes to crap and the local embassy or company office needs to source something locally, it is a *very* good thing if you've already got a point of contact in country. Nothing fancy, just renting a one-room office or keeping a local on hire to answer the phone. If operations are fairly regular, though, like when a larger trend of conflicts is ongoing, it is absolutely impossible to keep up with regulatory requirements. Your job is, after all, to wield lethal force. In reality you do this every time you move a chair, pick up a rock, throw a baseball, grab any kind of farm tool you can imagine, or get the cutting board from under the sink... but that's not how regulators see things. (And before you say "but you don't wage wars with rocks and knives and stuff" -- that is *precisely* what insurgents do.) Sourcing the best weapons money can buy in a country like the US, UK or France is not terribly difficult -- but *shipping them out sure is*. The other side is even harder: getting authorization to ship weapons into a warzone. Now that last bit is highly ironic given the typical glut of weaponry just laying around and the fact that there is usually a vibrant black market in action -- but it is absolutely *insane* the layers of paperwork, ass-kissing, bribing, cousin marriages, and personal relationships you have to maintain to ship a container of 30 rifles from Arizona to Pakistan.
Given that doing things the 100% legal way involves insurmountable regulatory hurdles, and to even be allowed to do things legally one must do the illegal stuff anyway to grease the skids on the operation (the bribes, cousin jiggering and relationships part) the path of least resistance is usually to source and maintain weapons locally and then *make that legal* by way of the bribes and whatnot. The end result is that you have mountains of paperwork to do (once your cache is made legal it will have to be registered and maintained by an armorer), but its done quickly and you have access to what you need *now* (money and arms) instead of never getting the operation off the ground because someone else can beat your price and timeline by sourcing locally. Its a race to market! But maybe not the sort of race to market everyone is aware occurs.
The tradeoff is money (flexible) and time (inflexible) in exchange for a much lower availability of the weapons you *want* to use. In a big theater like Iraq or Afghanistan its not so hard to get real M-4's and things, but they will often be Bushmasters instead of Colts, for example (and when the the teeth on the bolt break while you're firing... you *really* hope the rest of them hold until you can maybe find a new one and a new barrel, which is anything but certain). In a smaller theater you are rarely that lucky and will have to settle for unreliable remakes (that look good, but don't sound so good), crappy magazines (failure to feed == failure to fire), ill-maintained former stockpile gear (that works, but requires some rehabilitation work), former Soviet stock ([contrary to the popular image, the AK-47 and PKM are *not* the first choice of most discerning infantrymen...](http://zxq9.com/archives/911)), or a big fat pile of "frankenguns". And that's just guns! The situation with ammunition is absolutely laughable most of the time (protip: *practice stoppage drills*).
[*Frankengun*: A firearm, usually of Soviet design, that is assembled from the not-yet-totally-broken parts of a collection of other guns that used to work. This is particularly common with PKMs, which are already bad enough when they are in factory condition compared to an M-240B\* or an MG-3\*\*.]
```
* or MAG-58, or M-60, or...
** or MG-42, or MG-11, or MG-53, or...
See, guns have lineages, too! The PKM's line had a lot of inbreeding...
```
Where individuals trying to find contract work hang around to be known and put themselves in the right places at the right times, companies hoping to score prime contracts have to have an early logistical presence and maintain it in order to be confident they can service any contracts at all.
**EDIT**
In the spirit of this answer I'm preserving a thread that occurred in comments below that will certainly be lost to moderation eventually.
tl;dr: A tech contractor who worked for a PMC some of the same places I have asked some details about where the tactical contractors hang out and we had some back and forth. Ultimately, *I want to keep in touch with the guy*. This is partly out of habit, partly to reminisce, partly because I sense a kindred spirit, and partly because who knows when it might be a good thing to know another guy who does PMC work that is into tech?
<http://zxq9.com/archives/1223>
*This* is what I am talking about in terms of contractors sticking together like a tangle of Christmas-light-string shaped magnetic fishhooks. |
31,660 | <p>Currently your work and life schedules fall mostly into 'day' and 'night', with a few areas breaking up work times into 3 part shifts, morning, evening night etc.</p>
<p>Imagine we live in an artificial enviroment, most likely a space station or world ship, which does not have a sun and light comes from electricity instead; and that this enviroment is far enough away from earth or other planet that it is not ruled by that planets schedules. In this world we don't need to set our schedule by the sun, any time we have as much light as any other time.</p>
<p>How would humans structure their work and daily life in such a structure? Would they still keep a day/night pattern, or would they shift over to something like a 3 shift system where you work shift A, B, or C without any shift being thought of as day or night?</p>
<p>If they kept a shift system how would that impact things like service industry, that usually is only open during the 'day' if there is no official day but insufficient customer volume to justify 24/7 operations? would there be issues with needing something or someone but not being on the right 'shift', basically would every 'shift' be mostly cut off from each other because of when they work and sleep?</p>
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"text": "<p>I think you mostly answered yourself... even in an artificial environment, forcing people into shifts will c... | 2015/12/17 | [
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] | Currently your work and life schedules fall mostly into 'day' and 'night', with a few areas breaking up work times into 3 part shifts, morning, evening night etc.
Imagine we live in an artificial enviroment, most likely a space station or world ship, which does not have a sun and light comes from electricity instead; and that this enviroment is far enough away from earth or other planet that it is not ruled by that planets schedules. In this world we don't need to set our schedule by the sun, any time we have as much light as any other time.
How would humans structure their work and daily life in such a structure? Would they still keep a day/night pattern, or would they shift over to something like a 3 shift system where you work shift A, B, or C without any shift being thought of as day or night?
If they kept a shift system how would that impact things like service industry, that usually is only open during the 'day' if there is no official day but insufficient customer volume to justify 24/7 operations? would there be issues with needing something or someone but not being on the right 'shift', basically would every 'shift' be mostly cut off from each other because of when they work and sleep? | I believe that a realistic answer to this will heavily depend on your universe's current **understanding of human sleep patterns**.
[Historical records indicate](http://www.bbc.com/news/magazine-16964783) that prior to the easy access to artificial lighting, **people used to sleep in two, 4-hour chunks**, separated by a waking period of 1-2 hours. A [psychiatrist's experiment in the 1990s](http://www.nytimes.com/1995/03/14/science/modern-life-suppresses-an-ancient-body-rhythm.html?pagewanted=all) confirmed this pattern. [One study indicated](http://www.washington.edu/news/2015/06/19/access-to-electricity-is-linked-to-reduced-sleep/) that access to artificial light has shortened our sleep periods by about an hour; seasons also caused variation.
The best long-term case studies that I know of for someone **living in a completely artificial light environment** occurred over a period between 1962-1972 by the French scientist [Michel Siffre](https://en.wikipedia.org/wiki/Michel_Siffre). In 1962, he spent **two months** in a cave, notably **without access to a clock or calendar**, in an attempt to determine what natural biorhythms would develop in such an environment. In 1972, he repeated the experiment, staying in a cave for **six months.** *[[source]](http://www.cabinetmagazine.org/issues/30/foer.php)* For those interested in reading more, the latter experiment was covered in the March 1975 issue of National Geographic in a piece entitled "Six Months Alone in a Cave" *([summarized here](http://jamesmdeem.com/stories.cave4.html))*.
Physiological effects included:
* developing an **extended 25-26 hour sleep/wake cycle**, with some occurrences of a **48-hour sleep/wake cycle** *(36 hours awake, 12-14 hours asleep)*
* a **subjective experience of the passage of time**; he experienced it ~2x slower than it was in reality *(from the 2-month experiment)*
There have also been other experiments done as **test runs for living in space habitats**. The Russian [MARS-500](https://en.wikipedia.org/wiki/MARS-500) isolation experiment between 2007-2011 simulated a 105-day stage and later a **520-day mission**; it's assumed that [this closed habitat](http://www.esa.int/var/esa/storage/images/esa_multimedia/images/2011/11/das_mars500-habitat_in_moskau/10297615-2-eng-GB/Das_Mars500-Habitat_in_Moskau.jpg) had no access to natural light. The data on physiological changes is sparse, but [articles indicate](http://www.space.com/19168-mock-mars-flight-reveals-big-sleep-concerns-for-astronauts.html) that circadian rhythms were effected, and that [in general](http://www.3news.co.nz/environmentsci/mars-experiment-marred-by-sleep-woes-2013010906), **astronauts are plagued by sleep issues**.
---
```
What do we do with all these facts?
```
You'd need have some semblance of **conformity to a natural sleep cycle** unless you want your residents chronically fatigued, irritable, etc. There would be **natural limits to wake periods due to physical exhaustion**, of course *(if we're ignoring biomedical enhancements or pharmaceuticals)*.
Shift systems might be **based on the length of an orbital cycle**, if the artificial environment is orbiting a planetary mass. This could be merely for convenience's sake, if the station is coordinating with people working on the planet who are subject to a more traditional day/night cycle.
Material resources are also a consideration; in Neal Stephenson's recent science fiction novel *Seveneves*, he posited that **staggering wake/sleep cycles** across a space station's population **would prevent a strain on life-support systems** and allow it to support a larger population. This did allow for some **overlap** between people on different "shifts", **for work collaboration & social interaction**. Special attention was paid to being cognizant & respectful of seeking someone's attention during their sleep period. In your universe, this could be imbued via the development of cultural practices and the implementation of shared calendar/contact systems that warned someone if they were trying to digitally interact with a person who was in a sleep period. |
32,517 | <p>It is well known that in respiration, we produce carbon dioxide, while plants, via photosynthesis, absorb CO<sub>2</sub>. My question is, if 50% of all people die today, will the total amount of CO<sub>2</sub> decrease drastically or will it be too small a change to notice?</p>
| [
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"text": "<p>The death of 3 billion people would not cause much of a change in CO2 from breathing. The CO2 we breathe... | 2016/01/02 | [
"https://worldbuilding.stackexchange.com/questions/32517",
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] | It is well known that in respiration, we produce carbon dioxide, while plants, via photosynthesis, absorb CO2. My question is, if 50% of all people die today, will the total amount of CO2 decrease drastically or will it be too small a change to notice? | It's probably worth noting that the carbon dioxide that we breath out doesn't come from no-where. I imagine that the oxygen (dioxide) comes from the atmosphere and that the carbon comes from the food we eat.
Here's the kicker - even if half the earth's population died tomorrow, that food would still decompose and be released as carbon dioxide (because even bacteria respire just like us!). So no change there.
But what happens if we don't grow the food in the first place? I hear you. If the food isn't grown, then it didn't consume any carbon. This is important to realize, becauseiIf you track carbon back far enough, you'll discover that it comes from *drum roll please*:
```
All plant and soil carbon comes, in the end, from CO2 in the atmosphere.
```
<http://carbon-sense.com/2008/05/12/where-do-plants-get-their-carbon/>
Also see: <https://biology.stackexchange.com/questions/37264/how-do-plants-get-carbon>
So humans live - we grow food, the food takes carbon from atmosphere - we eat food and return carbon. Humans don't live, we don't grow food and the carbon doesn't get taken from the atmosphere in the first place. It's a zero sum game.
So instead of thinking of humans (or any life form) as carbon dioxide producers, it might be best to think of us as carbon dioxide borrowers - we simply borrow some from the atmosphere, live our lives, and have it returned.
The reason there is concern about human activity today is not due to our respiration, but due to:
* Deforestation, releasing a huge quantity of 'borrowed' carbon back into the atmosphere, without creating new borrowers to consume it.
* Highly 'greenhouse' chemicals - some are far more effective than carbon dioxide.
* Digging up dead corpses (literally oil/gas/coal) and releasing the carbon they borrowed a long time ago.
A massive death rate among humans may cause changes in these behaviours, but our respiration alone has no impact. |
34,311 | <p><strong>Setting</strong></p>
<p><a href="https://worldbuilding.stackexchange.com/questions/34154/how-would-a-drug-cartel-claim-legitimacy-as-a-government-entity">The US is waging a failing War on Drugs where cartels are quickly gaining power</a>.</p>
<p><strong>Scenario</strong></p>
<p>In the near future, say 2030, with current technology, the Texas state government is implementing a unified surveillance program that will extensively use a variety methods, including : </p>
<ul>
<li>Street cameras</li>
<li>Wi-fi location trackers </li>
<li>911 call data </li>
<li><a href="https://en.wikipedia.org/wiki/Stingray_phone_tracker" rel="nofollow noreferrer">Stingray
technology</a></li>
<li>Automated license plate readers</li>
<li>Criminal record/vehicle registration database</li>
<li>Passive social media monitoring</li>
<li>Web traffic interception (NSA tech)</li>
</ul>
<p>in an attempt to give their state the advantage when it comes to gathering intelligence on the notorious cartels that are waging a territory war which has been ravaging the state. However, this program is different from others in one way : it utilizes an experimental AI developed jointly with SRI International, the DHS, MIT and the FBI. Named the ADAS (Analytic Data Assisted Surveillance), it has the power to track and identify suspicious behaviors or patterns by taking in data from all of the sources listed above. </p>
<p><strong>Technical Details</strong> </p>
<p>This AI is nowhere near sentient. It is closer to the purpose built AIs that are strictly designed to function as an automated data analyst. Think of it as a less advanced version of the Superintendent from Halo ODST, connected to a surveillance grid that is a somewhat more intrusive version of modern day Camden's surveillance grid. It can detect and interpret complex patterns using pattern recognition, natural language processing, image processing and machine learning. </p>
<p>Examples of how it would reason : </p>
<pre><code>import sqlite3
import ADASpack
setloc(6700 Sherman Street)
cur = con.cursor()
scn_plate(E29346)
cur.execute(SELECT * FROM VEH_REGIST;)
df = pd.read_sql_query(cur.execute(WHERE plate_num = E29346;), con)
if theft_status == 1:
return(warn_veh_theft, plate_num, scan_loc)
veh_sus.append(plate_num)
else :
return()
veh_log.append(plate_num)
scn_face(ID9283498132475)
cur.execute(SELECT * FROM FED_PER_ID;)
df = pd.read_sql_query(cur.execute(WHERE id_no = ID9283498132475;), con)
if warrant_status == 'FELONY':
return(warn_felon, id_no, scan_loc)
act_felony.append(id_no)
elif warrant_status == 'MISDMR':
return(warn_misdmr, id_no, scan_loc)
act_misdmr.append(id_no)
else:
return()
per_log.append(id_no)
</code></pre>
<p><strong>The Problem</strong></p>
<p>How would this affect the lives of citizens? Each person knows that they are constantly being watched, so it would obviously have a chilling effect on dissenting speech, although that has already happened to some degree in my universe. </p>
<p>How would the cartels adapt? Assume that the larger ones have skilled hackers that are good enough to find holes in the system, and are skilled enough to keep up with the cat and mouse game of encryption against the government's programmers. Would they focus on disrupting the system, going back to old-school hand ciphers, or both? </p>
<p>What would the political ramifications be? Since whoever controls this system has a lot of power to do some serious muckraking, or cover it up as well... </p>
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"text": "<p>People (and cartels) will probably begin to meet in place outside the sight of the AI and controls, like ... | 2016/01/26 | [
"https://worldbuilding.stackexchange.com/questions/34311",
"https://worldbuilding.stackexchange.com",
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] | **Setting**
[The US is waging a failing War on Drugs where cartels are quickly gaining power](https://worldbuilding.stackexchange.com/questions/34154/how-would-a-drug-cartel-claim-legitimacy-as-a-government-entity).
**Scenario**
In the near future, say 2030, with current technology, the Texas state government is implementing a unified surveillance program that will extensively use a variety methods, including :
* Street cameras
* Wi-fi location trackers
* 911 call data
* [Stingray
technology](https://en.wikipedia.org/wiki/Stingray_phone_tracker)
* Automated license plate readers
* Criminal record/vehicle registration database
* Passive social media monitoring
* Web traffic interception (NSA tech)
in an attempt to give their state the advantage when it comes to gathering intelligence on the notorious cartels that are waging a territory war which has been ravaging the state. However, this program is different from others in one way : it utilizes an experimental AI developed jointly with SRI International, the DHS, MIT and the FBI. Named the ADAS (Analytic Data Assisted Surveillance), it has the power to track and identify suspicious behaviors or patterns by taking in data from all of the sources listed above.
**Technical Details**
This AI is nowhere near sentient. It is closer to the purpose built AIs that are strictly designed to function as an automated data analyst. Think of it as a less advanced version of the Superintendent from Halo ODST, connected to a surveillance grid that is a somewhat more intrusive version of modern day Camden's surveillance grid. It can detect and interpret complex patterns using pattern recognition, natural language processing, image processing and machine learning.
Examples of how it would reason :
```
import sqlite3
import ADASpack
setloc(6700 Sherman Street)
cur = con.cursor()
scn_plate(E29346)
cur.execute(SELECT * FROM VEH_REGIST;)
df = pd.read_sql_query(cur.execute(WHERE plate_num = E29346;), con)
if theft_status == 1:
return(warn_veh_theft, plate_num, scan_loc)
veh_sus.append(plate_num)
else :
return()
veh_log.append(plate_num)
scn_face(ID9283498132475)
cur.execute(SELECT * FROM FED_PER_ID;)
df = pd.read_sql_query(cur.execute(WHERE id_no = ID9283498132475;), con)
if warrant_status == 'FELONY':
return(warn_felon, id_no, scan_loc)
act_felony.append(id_no)
elif warrant_status == 'MISDMR':
return(warn_misdmr, id_no, scan_loc)
act_misdmr.append(id_no)
else:
return()
per_log.append(id_no)
```
**The Problem**
How would this affect the lives of citizens? Each person knows that they are constantly being watched, so it would obviously have a chilling effect on dissenting speech, although that has already happened to some degree in my universe.
How would the cartels adapt? Assume that the larger ones have skilled hackers that are good enough to find holes in the system, and are skilled enough to keep up with the cat and mouse game of encryption against the government's programmers. Would they focus on disrupting the system, going back to old-school hand ciphers, or both?
What would the political ramifications be? Since whoever controls this system has a lot of power to do some serious muckraking, or cover it up as well... | There will be a sort of bell curve response as people who don't have the skills or don't care settle into their day to day lives without worrying too much about intrusive surveillance, while the criminal, hacker and libertarian element are busy working out ways to circumvent it.
Some ideas are clearly "out". People hightailing it into the desert or other places where they think they can avoid surveillance will simply be telegraphic their intentions to the AI (and Predator drones can see you from a long way away). More subtle methods will have to be invented and practiced so that people can interact outside the parameters of the AI "in plain sight". Rather than smash and grabs, think more of con games, pickpockets and 3 card monte, or elaborate stage magic shows where the magician fools you with slight of hand, leaving you to wonder how exactly that was done.
Ubiquitous surveillance states are already in existence, and have had the better part of a century to practice. The former Soviet Union had things like FAX machines and photocopiers in locked rooms with limited access and hordes of people co-opted or forced to spy on their neighbours. East Germany had an incredible ratio of agents to population (over 174,000; over 2% of the population), and more modern states like Iran and China (and modern Russia) use the internet and social media monitoring and electronic warfare methodology to extensively monitor and filter the population's information.
Despite all this, there are a multitude of things people do, both high tech (various work arounds exist to penetrate the "Great Firewall of China", or you can be as simple was using "burn" phones for a single conversation), to low tech (Samizdat in the Soviet Union was basically conducted by hand copying information and passing sheets to trusted agents or through dead letter drops).
The real key is to ensure that your activities are not far enough outside the parameters considered "normal" to attract attention. If the backstory you wrote is accurate, there must have been a time where the various anti government groups infiltrated or subverted various government agencies, so can have inside people to monitor what the AI is doing and report back what is working and what isn't, or even manipulate the feeds or outputs of the AI itself. |
34,709 | <p>So say we discovered aliens through a wormhole near Saturn (Interstellar anyone?). Congratz to us! But we have a bigger issue in trying to communicate with them.</p>
<p>They developed in a completely different way than us, but their general physiology is the same (Bi-pedal humanoids that utilize vocal chords to speak). Assuming it takes hundreds of years for them to get information, how do we communicate?</p>
<p>After thinking about what everyone said about "Well we could communicate with math?" and "Math is universal." it raised the question of how would they recognize all of our current mathematical symbols even if they were to be included? (For example, what if they used a base 4 for their math rather than 10 or their characters are completely different?)</p>
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] | So say we discovered aliens through a wormhole near Saturn (Interstellar anyone?). Congratz to us! But we have a bigger issue in trying to communicate with them.
They developed in a completely different way than us, but their general physiology is the same (Bi-pedal humanoids that utilize vocal chords to speak). Assuming it takes hundreds of years for them to get information, how do we communicate?
After thinking about what everyone said about "Well we could communicate with math?" and "Math is universal." it raised the question of how would they recognize all of our current mathematical symbols even if they were to be included? (For example, what if they used a base 4 for their math rather than 10 or their characters are completely different?) | This question has already been debated by exo-astronomers. The best answer they could come up with (using 1974 technology) was the [Arecibo Message](https://en.wikipedia.org/wiki/Arecibo_message#Numbers).
The details might change, but the essential idea is that in the first part of your message, you teach the aliens, "this is how we count."
```
0
1 .
2 ..
3 ...
4 ....
5 .....
6 ......
7 .......
8 ........
9 .........
10 ..........
11 .......... .
12 .......... ..
20 ..........
..........
21 .......... .
..........
100 (*snip* a 10x10 grid of dots)
```
Then build communication from there. In the case of Arecibo, they used a binary system instead of decimal. If the aliens wrote back in their base four, we might expect:
```
X
A .
B ..
C ...
AX ....
AA .... .
```
etc. |
35,574 | <p>Take Charles Stross’s <em>Laundry</em> stories as an exemplar for this modern day approach that makes explicit the analogy between computer geeks and fantasy mages. If P = NP then magic is possible. Here’s a passage for bringing the reader up to speed in one of the later <em>Laundry</em> novels:</p>
<blockquote>
<p>I’m actually a specialist in a field called Applied Computational Demonology: the summoning and binding to service of unspeakable horrors from other dimensions, by means of mathematical tools. <strong>Magic is a branch of applied mathematics: we live in a multiverse, there is a platonic realm of pure numbers, and when we solve</strong> [sic] <strong>certain theorems, listeners in alien universes hear the echoes.</strong> By performing certain derivations and manipulating theorems, we can make extradimensional entities sit up and listen, and sometimes get them to do what we want them to.</p>
</blockquote>
<p>There have been variations in other stories, but Stross seems to lead the pack in mashing up supernatural and information technology.</p>
<p>Consider the bold part of the blockquote above. In (for example) Terry Pratchett’s <a href="https://en.wikipedia.org/wiki/Discworld" rel="noreferrer"><em>Discworld®</em></a> series, supernatural beings <em>listen</em> to people and might decide to meddle; speaking or performing rituals gets the specific attention of those paying general attention to human activity.</p>
<h1> ❝ what exactly does <em>solving a theorem</em> do? ❞</h1>
<p>But what exactly does <em>solving a theorem</em> <strong>do</strong>? If all theorems exist in the Platonic realm, in what manner does knowing about it bring on some action? If it's in a book somewhere, does a human mind <em>going over the steps</em> tickle something? Or does it require some degree of <em>understanding</em> of the complete proof?</p>
<p>How might this trope be made a little more rigorous?</p>
<p>(See also <a href="http://qntm.org/ra" rel="noreferrer">this story</a> where magic is an API. It was described as being discovered by working on physics and math theorems as above, but upon reviewing I see it’s like a programming language and is spoken. So how did that initial discovery “work”?)</p>
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] | Take Charles Stross’s *Laundry* stories as an exemplar for this modern day approach that makes explicit the analogy between computer geeks and fantasy mages. If P = NP then magic is possible. Here’s a passage for bringing the reader up to speed in one of the later *Laundry* novels:
>
> I’m actually a specialist in a field called Applied Computational Demonology: the summoning and binding to service of unspeakable horrors from other dimensions, by means of mathematical tools. **Magic is a branch of applied mathematics: we live in a multiverse, there is a platonic realm of pure numbers, and when we solve** [sic] **certain theorems, listeners in alien universes hear the echoes.** By performing certain derivations and manipulating theorems, we can make extradimensional entities sit up and listen, and sometimes get them to do what we want them to.
>
>
>
There have been variations in other stories, but Stross seems to lead the pack in mashing up supernatural and information technology.
Consider the bold part of the blockquote above. In (for example) Terry Pratchett’s [*Discworld®*](https://en.wikipedia.org/wiki/Discworld) series, supernatural beings *listen* to people and might decide to meddle; speaking or performing rituals gets the specific attention of those paying general attention to human activity.
❝ what exactly does *solving a theorem* do? ❞
===============================================
But what exactly does *solving a theorem* **do**? If all theorems exist in the Platonic realm, in what manner does knowing about it bring on some action? If it's in a book somewhere, does a human mind *going over the steps* tickle something? Or does it require some degree of *understanding* of the complete proof?
How might this trope be made a little more rigorous?
(See also [this story](http://qntm.org/ra) where magic is an API. It was described as being discovered by working on physics and math theorems as above, but upon reviewing I see it’s like a programming language and is spoken. So how did that initial discovery “work”?) | Going through each question one by one:
**what exactly does solving a theorem do?**
underlying question: what is a theorem? A theorem is a tautology, something that can't be false. 2=2 **IS** a theorem (not an interesting one, I agree but still). With this definition I think you can understand that the word "solving" has little to do with theorems. However you can prove that something is a theorem (which is I assume, what you wanted to say).
```
</hard-math> <philosophy>
```
In this case proving that something is a theorem depends on how you see math. Some think that mathematics is a human invention that only exists in our mind and has been created to help us understand the complexity of our world. In this case **math does not exist by itself** and proving a theorem means **creating it**
Other people think that mathematics is part of the physical world, it exists as rules just like physics does, it does not come from our mind but from us observing how the world works. In this case it's obvious that proving a theorem means **discovering it** (since it already exists in nature).
Now concerning your trope: Maybe the first interpretation suits you better: if the platonic realm is created as we prove theorems (because it only exists in our mind), your alien living in this realm does not even exist before it has been proven to exist between two symbols. Then your alien can't do anything until it has been proven to be able to alter his world in some ways, and \* **tadadadam** \* can't alter our world until he has been proven to be able to do so. **That's your initial discovery.** |
35,604 | <p>It's just my typical luck: I discover and recover the billion-dollars worth of gold on a <a href="http://www.dailymail.co.uk/news/article-3347952/Wreckage-300-year-old-Spanish-galleon-holding-1-5BILLION-gold-silver-coins.html" rel="noreferrer">sunken galleon</a> on the same day my arch-nemesis decides to detonate a one Megaton hydrogen bomb right above my main surface ship. My arch-nemesis thankfully could not resist the temptation to gloat, so she let me know about it in advance, just to tell me of my doom.</p>
<p>My (perhaps not so brave) initial reaction was to rush to the submersible (all the gold still on it) and start diving without telling any of my surface crew. (I took Mr. Whiskers with me, of course). ... Hmm, on the upside, my labor costs for the mission are about to go waaay down.</p>
<p>Now I need to be moving horizontally as soon as possible (the arch-nemesis will surely send her minions after me). Unfortunately, I can only dive or move horizontally, not both (I know, <em>terrible</em> design, but wrong time to point it out) so I need to know how far I have to dive to be perfectly safe before I switch to the horizontal movement mode. </p>
<p><strong>Is it possible to escape a hydrogen bomb by diving in a submarine? If so, how deep do I need to go?</strong></p>
| [
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"text": "<p>The closer to the water that it is when it goes off the more energy is distributed to it. <a href=\"http://s... | 2016/02/09 | [
"https://worldbuilding.stackexchange.com/questions/35604",
"https://worldbuilding.stackexchange.com",
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] | It's just my typical luck: I discover and recover the billion-dollars worth of gold on a [sunken galleon](http://www.dailymail.co.uk/news/article-3347952/Wreckage-300-year-old-Spanish-galleon-holding-1-5BILLION-gold-silver-coins.html) on the same day my arch-nemesis decides to detonate a one Megaton hydrogen bomb right above my main surface ship. My arch-nemesis thankfully could not resist the temptation to gloat, so she let me know about it in advance, just to tell me of my doom.
My (perhaps not so brave) initial reaction was to rush to the submersible (all the gold still on it) and start diving without telling any of my surface crew. (I took Mr. Whiskers with me, of course). ... Hmm, on the upside, my labor costs for the mission are about to go waaay down.
Now I need to be moving horizontally as soon as possible (the arch-nemesis will surely send her minions after me). Unfortunately, I can only dive or move horizontally, not both (I know, *terrible* design, but wrong time to point it out) so I need to know how far I have to dive to be perfectly safe before I switch to the horizontal movement mode.
**Is it possible to escape a hydrogen bomb by diving in a submarine? If so, how deep do I need to go?** | Depth may not be your friend, but number of layers is. When the shockwave hits the surface of the water, much of it is reflected, but some of the shockwave is transmitted. How much? It turns out [they wrote a book about it](https://books.google.com/books?id=CZtDAAAAQBAJ&lpg=PA16&ots=tTfPhlW33j&dq=impedance%20mismatch%20air%20water%20shockwave&pg=PA17#v=onepage&q=impedance%20mismatch%20air%20water%20shockwave&f=false):
>
> As discussed by Henderson et al. (1990), when a blast wave first contacts a water sheet, a large portion of the incident energy is reflected back towards the source due to the impedance mismatch at the air-water interface. The remaining energy, which is transmitted through the water sheet, forms the observed weak shock wave and the resulting initial pressure rise. For the experimental conditions considered here, the initial blast overpressure is mitigated by as much as 80%. This indicates that a water sheet may be an effective emergency blast mitigant.
>
>
>
In this case, the explosive was 48.4g of PETN (page 14), but I don't have any reason to expect any one shockwave to behave differently from another.
So how far do you need to be? Well, they haven't written a book about that, but they did write a [text file](http://textfiles.com/survival/blastfnd.txt) about it. I'm getting a little nervous just how much attention this problem has gotten...
```
Blast effects of nuclear bomb (this is for an 80 col. printout)
All distances to effect in miles. Note: airburst distances in ( )
Airburst for optimum damage for that effect, since the height of airburst
changes these figures represent worst case. See example for fixed height
results.
MT 1psi 1.5 3 6 10 30 overpressure
0.2 4(7.5) 3(6) 2(3.4) 1.3(1.8) 1(1.2) .55(.6)
0.6 6(11) 4.5(9) 2.8(5) 1.8(2.6) 1.4(1.7) .8(.9)
1.0 7(13) 5.5(10.5) 3.3(6) 2.2(3.2) 1.6(2) .95(1.05)
5 12(23) 9(18) 5.5(10) 3.7(5.5) 2.7(3.5) 1.6(1.8)
20 19(35) 14(28) 9(16) 6(8.5) 4.3(5.5) 2.5(3.4)
(Update note: the 5 & 20 Megaton bombs only existed in old Soviet Bear and
Bison class bombers and have been replaced with more modern 1 Megaton bombs.
The old US Titan missiles with their 9 Megaton bombs were scraped during late
1987 and early 1988)
```
...
```
Examples of damage (from SURVIVING DOOMSDAY -Clayton, from tables in THE
EFFECTS OF NUCLEAR WEAPONS 1977 -Gladstone)
0.5 psi Private airplanes damaged but flyable, windows have light damage
1.0 psi Windows heavily damaged, wood frame houses lightly damaged
1.75 psi Some, but not all, glass shards capable of penetrating abdominal wall.
2 psi Human body thrown hard enough to cause incapcitating injuries if standing
3 psi Human body thrown hard enough to cause 1% fatalities if standing up.
4 psi Forest road impassable due to fallen trees.
5 psi Wood frame house collapse, 1% of eardrums rupture (in the elderly)
6 psi Human body thrown hard enough to cause 99% fatalities
```
From this chart, 6 psi is enough for a 99% fatality rate. You're in a submersable, so that's 6psi in the air of the sub. The reflection off the surface means you need 5x that shockwave pressure (reciprocal of 80%), which is 30psi suggesting .95 miles of distance is needed. However, there's more to this, because you have *two* impedence mismatches. One from air to water, and one back from water to air. These effects stack, meaning you need 25x more pressure at the surface to affect you. Thus, you would need a 150psi shockwave hitting the water to reach the essential 6psi. If we look at the table, that pressure is remarkably hard to hit. Obviously the table doesn't go that far, but I'd be tempted to guess its around 0.1mi, or about 500 feet. As a point of comparison, Little Boy, the bomb dropped on Hiroshima, was detonated at 1,968 ± 50 feet. I won't play CONOPS games with nukes, but I'm guessing that by the time the shockwave hits the water's surface, it's gone far enough to be below the magic 150psi level.
How about radiation? Piece of cake. From our [sister site](https://space.stackexchange.com/questions/1336/what-thickness-depth-of-water-would-be-required-to-provide-radiation-shielding-i):
>
> We know from the nuclear power industry that spent fuel storage pools
> are pretty safe places to be around, radiation-wise. They're actually
> safe to swim in, to a point, because they're serviced routinely by
> human divers. They just can't get too close to the spent fuel.
>
>
> We use these pools for short-term storage because water is a really
> good radiation shield. How good? Well, according to a report on the
> topic prepared for the DoE back in 1977, a layer of water 7
> centimeters thick reduces the ionizing radiation (rays and particles)
> transmitted through it by half (the remainder is captured or moderated
> to non-ionizing energy levels, mainly heat).
>
>
>
Considering that you can hold your breath and dive to 700cm in a pinch, radiation is going to be a non issue for any submersible. |
36,724 | <p>Related somewhat to <a href="https://worldbuilding.stackexchange.com/questions/12442/gravity-on-a-minecraftian-world">Gravity on a Minecraftian world?</a></p>
<p>say I have this infinite plane/world, then punch a circular hole through it to the other side. Say I manage to make a circular hole around 1 kilometer fairly uniform all the way through. For argument say the mass/material that used to occupy this space is either destroyed or distributed uniformly around the perimeter of the hole.</p>
<p>Firstly; would this hole immediately collapse or would it be a somewhat stable structure? </p>
<p>Secondly; (assuming it was/made stable) if I had a death wish and took a running jump off the edge, where would I fall? The exact center of the hole? Would I drift across to the other edge? One of the "sides" of the hole? </p>
<p>Corollary: If the hole itself was stable, would travel through it unprotected be fatal? Eg: are the pressures on a minecraftian world the same as on a spherical one? ****</p>
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say I have this infinite plane/world, then punch a circular hole through it to the other side. Say I manage to make a circular hole around 1 kilometer fairly uniform all the way through. For argument say the mass/material that used to occupy this space is either destroyed or distributed uniformly around the perimeter of the hole.
Firstly; would this hole immediately collapse or would it be a somewhat stable structure?
Secondly; (assuming it was/made stable) if I had a death wish and took a running jump off the edge, where would I fall? The exact center of the hole? Would I drift across to the other edge? One of the "sides" of the hole?
Corollary: If the hole itself was stable, would travel through it unprotected be fatal? Eg: are the pressures on a minecraftian world the same as on a spherical one? \*\*\*\* | For this answer I'm assuming that Planet Plane is [the one from this answer](https://worldbuilding.stackexchange.com/a/12443/760) which is infinite in area and 6,378km deep.
(This cannot be Planet Minecraft because it would not have a horizon for the Sun and Moon to drop below. For what Planet Minecraft would really be like, see [this episode of It's Okay To Be Smart](https://www.youtube.com/watch?v=h5N7d8mcQk4).)
>
> *Firstly; would this hole immediately collapse or would it be a somewhat stable structure?*
>
>
>
This depends on the material Planet Plane is made of. If we assume Planet Plane can exist, then your hole will not collapse.
The problem with massive structures is gravity tries to pull them together into their most stable state: a sphere. Since Planet Plane exists as an infinite plane then we can surmise it is strong enough to resist gravity. Therefore your hole will remain open for a while.
Eventually it will close. Any debris which falls into the hole will collect at the center where gravity balances out. Eventually enough debris will fall into the hole to fill it up.
The problem isn't will the hole stay open, the problem is ***will the hole grow forever***?
As @Samuel pointed out in the comments, unlike a sphere where the center of mass is a point in the middle, the center of mass for a uniformly dense infinite plane with finite depth is an infinite plane in the middle of the planet. This means gravity is always pulling orthogonal to the surface
```
Side-view cutaway of Planet Plane
gravity
||
\/
<=============================================> D
<=============================================> E
<------------- center of mass ---------------> P
<=============================================> T
<=============================================> H
```
If you punch a hole in this structure, there will be no gravitational force trying to pull the sides together. Every side will have the same amount of mass around it in every direction. However, the hole has no mass (discounting the negligible effects from air) and exerts no gravity. Therefore ***each side will be a little closer to one half of the plane than the other*** and so will feel a stronger gravitational pull in that direction. The edges of the hole will experience a tug from their side of the planet, threatening to *widen the hole*. The hole will experience [tidal forces](https://en.wikipedia.org/wiki/Tidal_force).
If the hole gets wider, the sides get further apart, and the tidal effect gets stronger. Once it starts, ***the hole continues to get bigger forever***. Fortunately there's infinite planet, so you'll never run out of surface to run to.
I'd be interested to see someone do the math on the tidal forces at the edges of your 1km diameter cylinder.
>
> *Secondly; (assuming it was/made stable) if I had a death wish and took a running jump off the edge, where would I fall? The exact center of the hole? Would I drift across to the other edge? One of the "sides" of the hole?*
>
>
>
The issue here is whether or not Planet Plane is rotating. If it's not, and if we assume the hole contains a vacuum, as you fall you will continue to drift across the hole at the speed you were running when you jumped. If you were an Olympic sprinter you'd be going about 10m/s and smack into the other side of the hole in about a minute and a half hitting it with the same force as if you had run into it, plus getting dragged along the edge of the hole. Ouch.
If Planet Plane is rotating there will be a [Coriolis force](https://en.wikipedia.org/wiki/Coriolis_force) and you will smack into a wall on your way down. [Minute Physics has a great video on this](https://www.youtube.com/watch?v=jN-FfJKgis8).
The one exception is it your planet happened to be rotating on an axis running directly through your hole. This is the same as drilling a hole through the Earth *pole to pole*.
The best case (for you) is if the planet is not rotating and your hole have an atmosphere. In this case air resistance will slow your forward motion and you will eventually fall straight down. But this causes a new problem.
That same air resistance will slow your fall. When you pass the center point and begin traveling "up" towards the other side of the planet you're now feeling the same pull of gravity down into the hole. With no air resistance this will exactly balance out your acceleration due to falling and you will reach the peak of your fall right at the lip of the hole on the other side and you can gently step out.
But air resistance will be slowing you during your fall and ascent. This means you'll come up short. Instead of peaking at the surface, you'll peak below it and fall back again to the other side, again peaking further below the surface. You'll oscillate back and forth like this, losing energy to atmospheric drag, until you're stuck floating in the center of the planet.
Tidal forces also play a role. If you're in the exact center of the hole you're fine, but if you're closer to one side or the other the tidal force will slowly pull you towards the edge. As you get further away from the edges the force will get stronger. Again, I haven't done the math on how strong.
>
> *Corollary: If the hole itself was stable, would travel through it unprotected be fatal? Eg: are the pressures on a mine-craftian world the same as on a spherical one?*
>
>
>
This depends on how old Planet Plane is, how it formed, and what it's made of.
The interiors of spherical planets are initially very hot from the residual heating of forming due to gravitational collapse, plus the decay of any radioactive elements trapped in the insulated interior. There can also be heating due to tidal effects as happens on the moons of Jupiter and Saturn, the squeezing and stretching adds heat to the moon's interior.
But Planet Plane can't be a moon, and it didn't form from gravitational collapse. So it's anyone's guess as to what heat of the interior will be.
What will be a problem is air pressure. Air pressure is the weight of a column of air pressing down on you. Assuming a normal Earth atmosphere at the surface, at the center of the hole you'll be supporting an extra 3,189km column of air. This is *a lot* of air. The atmosphere ends and space begins at about 100km. At the center you'll be experiencing *at least 30 times normal air pressure*. This is roughly equivalent to being 300m under water (every 10m is about 1 atmosphere of pressure). *Squish* [You will need some serious deep sea equipment to survive this, only five people have gone that deep on the Earth](https://en.wikipedia.org/wiki/Deep_diving#Ultra-deep_diving).
(NOTE: I'm playing a bit fast and loose with the air pressure calculation. The pull of gravity will decrease towards the center of the hole which may reduce the air pressure. Still, it's doing to be in the ballpark of 30bar.) |
36,940 | <h2>Background Information</h2>
<p>Let's say that we are trying to catch the attention of other potentially intelligent species. This signal would be used to attract the attention of other intelligent species. If another species (of any possible number system, shape, technology...) were to intercept this signal, they could assume that it was from another intelligent species. For example, we could transmit:</p>
<pre>11.0010010000111111011010101...</pre>
<p>, which is pi in binary, both of which are concepts likely to have been developed in another species.</p>
<h2>The Question</h2>
<p>What would be a (semi-)universally understood signal to transmit to show to other species that we are intelligent?</p>
| [
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] | Background Information
----------------------
Let's say that we are trying to catch the attention of other potentially intelligent species. This signal would be used to attract the attention of other intelligent species. If another species (of any possible number system, shape, technology...) were to intercept this signal, they could assume that it was from another intelligent species. For example, we could transmit:
```
11.0010010000111111011010101...
```
, which is pi in binary, both of which are concepts likely to have been developed in another species.
The Question
------------
What would be a (semi-)universally understood signal to transmit to show to other species that we are intelligent? | Using the digits of a number isn't really the best way to express a number when communicating with an alien race as Extra Terrestrials would almost certainly use completely different methods for expressing number from us. In order to show our mathematical knowledge to aliens it would be better to find a method of communicating mathematics that doesn't involve any symbols. One way we could communicate our knowledge of math could be to send signal that looks like AA AAA AAAAA AAAAAAA AAAAAAAAAAA AAAAAAAAAAAAA AAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA as this would be a sequence of groups that all have the sequence of prime numbers as the number of individuals instead of using the symbols for the prime numbers so that they would not need to know what symbols we use for the prime numbers in order to recognize that it is a sequence of prime numbers. We could also send a signal like A AAAA AAAAAAAA AAAAAAAAA AAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA to represent perfect powers. Basically we would represent number in the most literal sense in terms of showing them by having numbers of things instead of the symbol for a number so that aliens could understand it even if they use different symbols for numbers. If we wanted to use pi we might send them a series of signals in which the length of each signal was close to pi times the length of the previous signal instead of using the digits of pi as they would likely have different symbols for 0 and 1 than the ones we use. If we wanted to teach aliens what symbols we use for different numbers we might send them the symbol next to clusters of objects that would have that number of objects and do it with many different types of objects so that they could see the pattern. |
37,719 | <p>I got this idea from looking at a tent pole. They have all these pieces that snap together and fit inside a cloth groove. What if I filled a cape with a bunch of those say 20 mm long with a 2 mm diameter? Instead of putting the pieces together with my hands, I'd have them joined together at the press of a button. The button would turn on the electromagnets and they would go rigid. </p>
<p>Would this work?</p>
<p>Work means be able to carry an average man if he jumped off a cliff a greater distance horizontally than the height he jumped from and leave him relatively unharmed. </p>
<p>This is my first question, so sorry if it's a bit vague. I am open to suggestions for specificity/clarity.</p>
<p>Thanks,</p>
<p>Aarthew III</p>
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"text": "<p>Assuming you had a wing design that already worked (<a href=\"http://www.wired.co.uk/news/archive/2012-07/09/ba... | 2016/03/09 | [
"https://worldbuilding.stackexchange.com/questions/37719",
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Would this work?
Work means be able to carry an average man if he jumped off a cliff a greater distance horizontally than the height he jumped from and leave him relatively unharmed.
This is my first question, so sorry if it's a bit vague. I am open to suggestions for specificity/clarity.
Thanks,
Aarthew III | Assuming you had a wing design that already worked ([Batman's cape will not](http://www.wired.co.uk/news/archive/2012-07/09/batman-cape-physics)) and the poles are already sufficiently strong and rigid, this could work.
Collapsible tent poles work by slotting the pole into a metal sleeve. There's also a bungie cord inside the pole to (lightly) pull the pieces together. The sleeve is typically stronger than the pole, as campers know tent poles tend to break at the pole, so in terms of strength there's no problem replacing complete poles with collapsible ones. It will add some weight and reduce flexibility, but it should be manageable.
Rather than joining the poles using magnets, it would be wise to retain the sleeve and cord system. It's proven tech, and your wing won't fall apart if you lose power. Where magnets come in is to pull the pole into the sleeve and ensure it's firmly seated. With some clever shaping of the ends of the poles and sleeves (funnel tip for the sleeve, round tip for the pole), this might be done reliably... though getting the complex shapes and joints necessary for a collapsible airfoil will be tricky. However if you lose power you lose tension and a pole may slip out of its sleeve. Perhaps you could have a locking mechanism, but it would also have to unlock.
What would be even more reliable is to cause the bungie cord to contract pulling the ends of the poles into the sleeves. This could be a simple mechanical operation pulling on the cord at the middle of the pole, or by separating two pole pieces and inserting a spacer.
```
Poles at start =====*--=====*--=====*--=====*--=====*--=====
Open a gap =====*=====*=====*------------=====*=====*=====
Insert spacer =====*=====*=====*-=========*-=====*=====*=====
Release tension =====*=====*=====*=========*=====*=====*=====
```
To collapse, remove the spacer releasing the tension on the cord. |
38,510 | <p>The <a href="https://worldbuilding.stackexchange.com/questions/38354/how-often-must-carnivorous-grassland-eat">bonegrass</a> fields are full of other life, despite their dangers. Lots of insects, some birds, and even a handful of reptiles have adapted to the paralytic nature of the air in order to reap the rich rewards offered by the deathly white foliage. Of all of these creatures the most advanced by far are the fleshmoles. </p>
<p>Rather than adapting to the neurotoxins emitted by the plantlife the fleshmoles (actually a branch of <a href="https://en.wikipedia.org/wiki/Naked_mole-rat" rel="nofollow noreferrer">naked mole rats</a>) have an alternate strategy:</p>
<p>They rarely breathe fresh air.</p>
<p>Fleshmoles don't surface unless there is prey that has been ensnared by the bonegrass, and even then they tunnel directly up through the ground into the flesh of whatever has fallen (causing excruciating pain if the prey hasn't already died). They're adapted to deal with high CO2 concentrations and the noxious atmosphere of their underground hives (A matriarchal eusocial structure keeps fleshmole colonies together), but of course occasional O2 injections are required. </p>
<p>To this end weak or old fleshmoles are driven to the surface, where they take a huge lungful of air, become paralyzed (neatly plugging the hole and removing the paralytic agent from the air they breathed in), then are dragged back down and rapidly consumed by their brethren. Fleshmoles also burrow into the chest cavities of larger prey in order to suck down as much O2 rich flesh as possible.</p>
<p>The question is this, given that I'm not particularly hot on my rodent biology:</p>
<p><strong>Is it possible for such a colony to maintain a workable O2 supply, given that they're fairly well optimised for high CO2 life?</strong> </p>
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] | The [bonegrass](https://worldbuilding.stackexchange.com/questions/38354/how-often-must-carnivorous-grassland-eat) fields are full of other life, despite their dangers. Lots of insects, some birds, and even a handful of reptiles have adapted to the paralytic nature of the air in order to reap the rich rewards offered by the deathly white foliage. Of all of these creatures the most advanced by far are the fleshmoles.
Rather than adapting to the neurotoxins emitted by the plantlife the fleshmoles (actually a branch of [naked mole rats](https://en.wikipedia.org/wiki/Naked_mole-rat)) have an alternate strategy:
They rarely breathe fresh air.
Fleshmoles don't surface unless there is prey that has been ensnared by the bonegrass, and even then they tunnel directly up through the ground into the flesh of whatever has fallen (causing excruciating pain if the prey hasn't already died). They're adapted to deal with high CO2 concentrations and the noxious atmosphere of their underground hives (A matriarchal eusocial structure keeps fleshmole colonies together), but of course occasional O2 injections are required.
To this end weak or old fleshmoles are driven to the surface, where they take a huge lungful of air, become paralyzed (neatly plugging the hole and removing the paralytic agent from the air they breathed in), then are dragged back down and rapidly consumed by their brethren. Fleshmoles also burrow into the chest cavities of larger prey in order to suck down as much O2 rich flesh as possible.
The question is this, given that I'm not particularly hot on my rodent biology:
**Is it possible for such a colony to maintain a workable O2 supply, given that they're fairly well optimised for high CO2 life?** | For mammals... this could be a problem.
A pretty average human being(62 kg) uses about 550 liters of pure oxygen per day(at sea level pressure).
So call it 9-ish litres per kg.
A single naked mole-rat is about 35 grams.
A colony is 20 to 300 individuals, with an average of 75.
So an average colony of 75 might weigh in at about 2.5-3.0 Kg of mammal-flesh.
They're extraordinarily long-lived for a rodent of their size (up to 31 years).
Small rodents tend to use more, not less oxygen by weight (more active) but let's make some generous assumptions:
Let's assume they use 10% as much oxygen by weight as humans.
Your colony still needs 2.7 litres of pure O2 per day or 13.5 litres of normal air (20% oxygen) assuming they use it perfectly somehow.
From this we can conclude that this is not a workable strategy:
>
> weak or old fleshmoles are driven to the surface, where they take a huge lungful of air, become paralyzed (neatly plugging the hole and removing the paralytic agent from the air they breathed in), then are dragged back down and rapidly consumed by their brethren.
>
>
>
**They live too long, their lungs are too small and it's just not gonna work. They couldn't provide a tenth of the air needed even with generous assumptions.**
But if I remember correctly you talked about how your victims are left alive. The air in their lungs is not a good option, it's contaminated by the spores just like the outside air.
**So let's try another option.**
Again, let's steal from real life organisms.
[](https://i.stack.imgur.com/p4HGb.jpg)
Real paracites need oxygen, how do they get it?
They absorb it from their host, often directly from the blood.
Your victim has a perfectly good set of lungs and they're going to be alive for quite a while (longer if nothing burrows into their lungs).
So your moles could be adapted to burrow into the flesh (careful not to cause lethal harm), find big arteries close to the heart/ lungs where it's rich in oxygen and then filter lots of oxygen from the blood and to somehow feed it back to their kin bellow using the victim as a living oxygen filter.
Perhaps, if desperate and lacking prey for a long long time, the moles might sacrifice one of their own to use the same trick: one of them breathes while the others filter oxygen from its blood below.
This leads on to some grim conclusions.
**It's going to be in the moles' interest to keep the victim alive for as long as possible.**
Too much bonegrass growing up through them will kill too fast. So the moles could be chewing away the roots of some of the young bonegrass to keep it from killing the victim quickly. The bonegrass wants to kill you fast. The moles want to keep you alive for as long as possible.
**Indeed, weirdly, if they have access to lots of calories but not much oxygen it could be in their interest to feed sugars into your blood while taking oxygen out.**
To stop you dying from infections they might even release antimicrobials as they chew into your flesh.
(Additional reason for people to enter the bonegrass: fleshmole teeth could have "venom" sacks containing potent antibiotics)
They also might carefully feed on fatty tissue, avoiding blood vessels, again to keep their victim alive for as long as possible.
There are some far more practical options for filtering air... but they're not as fun as absorbing it from the blood of still living hosts.
Now, there's also another possible use for your victim. A nice warm place for baby fleshmoles and similar parasites to grow.
Here's a species of wasp which lays its eggs inside still-living hosts.
```
♫It lands on caterpillars
It lays it's eggs inside
To make sure that the meat's fresh
It keeps the things alive
All things bright and beautiful...♫
```
[](https://i.stack.imgur.com/TF9N1.jpg)
Some wasps have an even more disturbing effect on their victims.
Once the babies have eaten their way out through the hosts flesh the host's behavior has been altered by the parasite and the caterpillar spends the remainder of its life trying protecting the parasites.
<https://youtu.be/7UkDMrG6tog?t=8>
So for added creepiness, imagine someone getting paralyzed, fleshmoles eat through their flesh but before they die the wind changes direction, the amount of paralytic poison decreases and they make their escape.
They have a few baby fleshmoles under their skin but rather than wanting to cut them out and destroy them the host feels a strong compulsion to care for them because the fleshmoles have released a hormone that hijacks the normal instincts to protect your children.
Someone is rescued from the bonegrass and the fleshmoles. The town rejoices. But the following week they're found carrying around a blanket filled with a squirming mass of infant fleshmoles treating them like a baby and feeding them chunks of raw meat. |
38,787 | <p>I'm working on the setting for a fictional story I'm writing and I wanted to inquire as to how possible massive-Universe-sized planets are radius: 5 × 10<sup>30</sup>M, without me having to re-make the laws of Physics.</p>
<p>I usually dislike it when I encounter works, in which it seems the author doesn't even have a grasp on Physics, and one would have to completely abandon Physics to enjoy such fiction. So I want my story to be coherent with the Laws of Physics as much as possible.</p>
<p>My story, is sci-fi, and fantasy. It uses "magic", but such "magic" is bounded by internal Laws and logic. <a href="http://mahouka-koukou-no-rettousei.wikia.com/wiki/Magic" rel="nofollow noreferrer">The "magic" is somewhat similar to "Mahouka Koukou no Rettousei"</a>.</p>
<p>Anyway, in the particular realm in which these planets occur, they are bounded by the Laws of Physics as they appear in our Universe.</p>
<p>String Theory has been established as correct.</p>
<p>The Planet-Universe, generate their own source of heat and light.</p>
<p>I want to know what the Physics and Chemistry of such a planet would be like. SO that I can adjust my story suitably while keeping in-line with Physics.</p>
<p>I was thinking of the extreme gravity, condensing the universe, until it was a solid sphere. The ejection jets are absent, due to the gravity, as they too have been solidified.The gravity has caused the planet verse, to attain equilibrium.</p>
<p>How does it sound, I'll appreciate suggestions.</p>
| [
{
"answer_id": 38789,
"author": "Philipp",
"author_id": 224,
"author_profile": "https://worldbuilding.stackexchange.com/users/224",
"pm_score": 3,
"selected": false,
"text": "<p>It's impossible for a planet of that size to exist in a universe with our physical laws.</p>\n\n<p>A planet wi... | 2016/03/24 | [
"https://worldbuilding.stackexchange.com/questions/38787",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/10544/"
] | I'm working on the setting for a fictional story I'm writing and I wanted to inquire as to how possible massive-Universe-sized planets are radius: 5 × 1030M, without me having to re-make the laws of Physics.
I usually dislike it when I encounter works, in which it seems the author doesn't even have a grasp on Physics, and one would have to completely abandon Physics to enjoy such fiction. So I want my story to be coherent with the Laws of Physics as much as possible.
My story, is sci-fi, and fantasy. It uses "magic", but such "magic" is bounded by internal Laws and logic. [The "magic" is somewhat similar to "Mahouka Koukou no Rettousei"](http://mahouka-koukou-no-rettousei.wikia.com/wiki/Magic).
Anyway, in the particular realm in which these planets occur, they are bounded by the Laws of Physics as they appear in our Universe.
String Theory has been established as correct.
The Planet-Universe, generate their own source of heat and light.
I want to know what the Physics and Chemistry of such a planet would be like. SO that I can adjust my story suitably while keeping in-line with Physics.
I was thinking of the extreme gravity, condensing the universe, until it was a solid sphere. The ejection jets are absent, due to the gravity, as they too have been solidified.The gravity has caused the planet verse, to attain equilibrium.
How does it sound, I'll appreciate suggestions. | First, a lot of reasons why this won't work in our universe. Then, an interesting solution. Finally, why the exercise is pointless.
---
5.0x1030 meters is about 10,000 times larger than [the observable universe](https://en.wikipedia.org/wiki/Observable_universe). That doesn't mean it's *larger* than the universe, but it does mean that an event on one point of the planet has only had enough time to reach 1/10,000th of the rest of the planet. ***There has not been enough time in the whole universe for light (and thus anything) to go from one side of the planet to the other***. This means there hasn't been enough time for gravity to form it into a sphere, the gravity from one side has not had time to affect the other. One has to wonder how this planet formed in the first place.
Either your universe is very, very, very, very much older than ours, or causality (ie. the speed of light) propagates much, much, much, much faster. Both of these have serious consequences. All sorts of important equations depend on the speed of light, so I'd leave that alone. Make your universe tremendously old. At least 1015 years.
---
Then there's the question of ***where this planet is getting its light and heat from?*** A scaled up star would require an even older universe to be given time to form. Then that requires that your planet rotates. With a circumference of 3.14x1031m, even the smallest rotation will have the surface dwellers moving at the speed of light. There's no way to have anything like a normal day/night cycle, even light will take 1023 seconds to get around the surface. One side bakes, the other side freezes.
An alternative heat source would be better. Our universe has no edge, but perhaps your universe does and it produces light and heat as it gobbles up whatever is "outside". Your planet is in the center of the universe and the surrounding edge is like being inside a spherical heat lamp. Your planet would be in perpetual daytime.
Be careful not to cook the planet by adding to the overall energy of your universe.
---
Then there's gravity. [@Philipp already covered that well](https://worldbuilding.stackexchange.com/a/38789/760), can it be solved? One solution is to mess with the gravitational constant. This will severely alter the makeup of the universe on a large scale, but I'd say that's already happened.
How much smaller should `G` be? We'll solve g = Gm/r2 for G and plug in an Earth `g` of 9.8 m/s2.
```
g = Gm/r^2
gr^2 = Gm
gr^2/m = G
```
Plug in your numbers... `r = 5x10^30 m`, `m = 2.89×10^96 kg` from @Philipp, `g = 9.8 m/s^2`. We get a G of `8.4x10^-35 N⋅m^2/kg^2` which is 24 orders of magnitude lower than in our universe. Gravity is already very weak, in your universe it's all but undetectable.
Such weak gravity would make your planet take even longer to form. It's questionable gravity could ever form a planet given how much stronger all the other forces would be.
---
An alternative way to solve the gravity problem is to ***make the planet hollow***. This reduces its mass which reduces its surface gravity. The surface gravity of a hollow planet is a bit harder to calculate, so let's move on to the next problem: how did this shell form and how has it not collapsed?
One possible solution is to put a small black hole in the center of the planet. The "edge" of the universe surrounding the planet is the inverted surface of a white hole. In effect, ***the planet is both outside and inside a black hole***. [Material falling into the black hole heats as it falls](https://en.wikipedia.org/wiki/Accretion_disk). This heated material comes out the white hole and creates the warm glow in the sky which heats the planet. As the planet is slowly eaten from the inside, a fine rain of material is falling on the surface from the white hole surrounding it.
This is its geological cycle of renewal, matter on the surface is eventually buried and sinks down to be eaten by the black hole. That same matter falls from the white hole which then rains down on the surface to start the cycle again. Like our own geological cycle, this would be unobservably slow to humans.
***The surface of the planet is a [standing wave](https://en.wikipedia.org/wiki/Standing_wave)*** in this flow of particles: a cosmic traffic jam.
This allows your planet without altering gravity or the age of the universe. ***This is an entirely different universe looping forever***.
---
Even this leaves the basic question of ***why have a planet so large the inhabitants don't even know they're on a sphere***? At your scale the planet would appear to be flat. The horizon would not appear to curve, ships would not sink over the horizon because they could never reach it. There would be no round, orbiting bodies to hint at the shape of the planet because a planet that large with Earth's surface gravity can't hold on to things in orbit.
***Your characters would think they live on a flat, infinite plane*** and there would be little they could do to prove otherwise. Your sphere is so big they could travel in any direction and never have evidence otherwise. Even at the speed of light for 100 years they'd have gone 1018 m or 1/1013 the circumference, not enough to detect a curve.
From a storytelling perspective, ***what does living on a giant sphere indistinguishable from a flat, infinite plane gain you***? |
38,921 | <p><em>Setting</em>: In my <a href="https://worldbuilding.stackexchange.com/questions/19788/how-would-flora-behave-on-a-two-continent-planet">conworld</a> there is a huge region (let's call it <em>the Midlands</em>) spanning from the northern borealis to the wide green pastures further south, of the northern continent, which is not one single country but rather a collection of dozens of <em>states</em> ranging from more utilitarian ones (e.g. big guilds) more centrally situated, to small kingdoms and duchies along the region's borders.<br>
It is entrenched between two bigger countries claiming most of the area in the northern part of the world. The Western Empire in the west; and the Eastern Reich in the east.</p>
<p>The territory of the Eastern Reich though consists mostly of barren land which, although rich in minerals, ores and crude oil, is mostly infertile and thus they seek to possess the more fertile lands to their west (the Midlands).</p>
<p><img src="https://i.imgur.com/taYD5m6.jpg" alt="Map Northern Hemisphere"></p>
<pre><code>A Western Empire
G Free Regions
H Eastern Reich
J Southern Lands
K Midlands (Coalition Territory)
L Border Lands
1 Equatorial Belt | Saltwater
2 | Saltwater
5 Northern Polar Sea | Saltwater
6 | Sweetwater
</code></pre>
<hr>
<p><em>History</em>: At some point in time, an <a href="https://en.wikipedia.org/wiki/Alexander_the_Great" rel="nofollow noreferrer">Alexander the Great</a>-esque character rose to power in the east and rallied an army behind him with the goal of *making these greener lands available to our glorious Reich (back then nothing more than a bunch of smaller kingdoms, claiming the more fertile spots and hot springs along the mountain ranges).</p>
<p>When news of this rallying reached the west, the states of the Midlands eventually reached a point where they <em>signed a contract</em> and pooled together resources and their current individual armies, police forces, etc. to form what is called the coalition Military Force (from here on referred to as <em>the Coalition</em>). Thanks to this act they managed to fight back the <em>first wave</em> of attackers by having troops from all over the Midlands fortifying the eastern borders.<br>
This collection of forces in turn managed to throw back the attackers long enough to give the Coalition the time needed to organize their new forces and set up a permanent block along the border, which continues to hold off the occasional raiding party from the east to this day (and further...); putting both parties in a cold-war/stalemate situation.</p>
<hr>
<p><em>Situation/Environment</em>: The inner states of the Midlands don't have the typical concept of borders. The lands mostly belongs to families and to guilds, the latter of which tend to buy and sell land where profitable; So borders in these areas are mostly informal. This is no issue because the whole system grew up to be that way (due to the way the early tribes/nomads in the area were organized and working with each other).<br>
The outer states tend to be influenced more by the surrounding big countries and thus some have organized themselves in duchies and smaller kingdoms.</p>
<p>While the duchies and kingdoms to the east of the Midlands enjoy similarly rich pastures and amounts of resources, it is the center of the Midlands that really profits from the region and they way they are set up, there are no such things as tolls and other things that hinder free trade there and thus these <em>states</em> are comparatively rich.</p>
<p>The concept of the Coalition treaty/contract stems from the historical background that the families in these areas would usually band together to achieve this or that (culminating in the formation of guilds and <em>states</em>).<br>
The Coalition Treaty itself consists roughly of the following parts:</p>
<pre><code>+----------------------------------------------------------+
| The Coalition Treaty, of xx/xx/xxxx |
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
| |
| This Treaty shall serve as a foundation for the creation |
| of a super-governmental military body. The Signees of |
| this treay shall receive the following rights and obli- |
| gations. |
| |
| > Each Signee shall receive full military support in ca- |
| se of an attack stemming from outside or inside coa- |
| lition territory |
| |
| > Each Signee shall disband any state-owned military |
| forces immediately upon this treaty's inuring |
| |
| > Each Signee shall disburse an amount of money relative |
| to the richess of their lands, |
| the size of their population, |
| the safer they are from being invaded |
| |
| > Each Signee shall be able to disburse additional funds |
| in return for military services such as but not only |
| - police forces |
| - guard forces |
| |
| > Each Signee shall provide a pool of potential recruits |
| from which to conscript additional forces should they |
| be needed |
| |
| In return the created body shall have to organise itself |
| and provide services as best as is possible within the |
| limits of the provided funds |
+----------------------------------------------------------+
</code></pre>
<p>The Coalition therefore is basically a private army catering exclusively to the needs of the signees of the Coalition Treaty. It possesses military bases and other assets in most of the signee states. Logically it has to buy things such as provisions and material, weaponry, etc., a whole industry catering to the needs of this huge body will subsequently sprout in the Coalition territory and provide jobs and ways to shift funds back to the signee states.</p>
<p>Now why would they band together against a force that only seems to threaten the easternmost duchies/kingdoms (which themselves anyways chose to abandon the traditional ways for a more eastern approach) and why would the center states even consider the idea which obviously will conclude in bigger expenses for them than so far?<br>
That is easy (mostly), easy: At the convent where most of the states gathered, the point was made that if the easternmost states/duchies/kingdoms fall, there is even less stopping the east army as it would gain a favourable position for annexing the rest of the Midlands. Thus the rich central states have a reason to back something that obviously means higher expenses to them than so far.</p>
<hr>
<p><strong><em>Question</em></strong>: Can a body such as the <em>Coalition Military Force</em> work in the described environment? And what issues that I failed to address/addressed <em>incorrectly</em> make it not work?</p>
| [
{
"answer_id": 38922,
"author": "John Robinson",
"author_id": 13430,
"author_profile": "https://worldbuilding.stackexchange.com/users/13430",
"pm_score": 1,
"selected": false,
"text": "<p>Gonna answer your two questions in reverse order.</p>\n\n<p>The main thing I'd say you have left to ... | 2016/03/25 | [
"https://worldbuilding.stackexchange.com/questions/38921",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/2746/"
] | *Setting*: In my [conworld](https://worldbuilding.stackexchange.com/questions/19788/how-would-flora-behave-on-a-two-continent-planet) there is a huge region (let's call it *the Midlands*) spanning from the northern borealis to the wide green pastures further south, of the northern continent, which is not one single country but rather a collection of dozens of *states* ranging from more utilitarian ones (e.g. big guilds) more centrally situated, to small kingdoms and duchies along the region's borders.
It is entrenched between two bigger countries claiming most of the area in the northern part of the world. The Western Empire in the west; and the Eastern Reich in the east.
The territory of the Eastern Reich though consists mostly of barren land which, although rich in minerals, ores and crude oil, is mostly infertile and thus they seek to possess the more fertile lands to their west (the Midlands).
```
A Western Empire
G Free Regions
H Eastern Reich
J Southern Lands
K Midlands (Coalition Territory)
L Border Lands
1 Equatorial Belt | Saltwater
2 | Saltwater
5 Northern Polar Sea | Saltwater
6 | Sweetwater
```
---
*History*: At some point in time, an [Alexander the Great](https://en.wikipedia.org/wiki/Alexander_the_Great)-esque character rose to power in the east and rallied an army behind him with the goal of \*making these greener lands available to our glorious Reich (back then nothing more than a bunch of smaller kingdoms, claiming the more fertile spots and hot springs along the mountain ranges).
When news of this rallying reached the west, the states of the Midlands eventually reached a point where they *signed a contract* and pooled together resources and their current individual armies, police forces, etc. to form what is called the coalition Military Force (from here on referred to as *the Coalition*). Thanks to this act they managed to fight back the *first wave* of attackers by having troops from all over the Midlands fortifying the eastern borders.
This collection of forces in turn managed to throw back the attackers long enough to give the Coalition the time needed to organize their new forces and set up a permanent block along the border, which continues to hold off the occasional raiding party from the east to this day (and further...); putting both parties in a cold-war/stalemate situation.
---
*Situation/Environment*: The inner states of the Midlands don't have the typical concept of borders. The lands mostly belongs to families and to guilds, the latter of which tend to buy and sell land where profitable; So borders in these areas are mostly informal. This is no issue because the whole system grew up to be that way (due to the way the early tribes/nomads in the area were organized and working with each other).
The outer states tend to be influenced more by the surrounding big countries and thus some have organized themselves in duchies and smaller kingdoms.
While the duchies and kingdoms to the east of the Midlands enjoy similarly rich pastures and amounts of resources, it is the center of the Midlands that really profits from the region and they way they are set up, there are no such things as tolls and other things that hinder free trade there and thus these *states* are comparatively rich.
The concept of the Coalition treaty/contract stems from the historical background that the families in these areas would usually band together to achieve this or that (culminating in the formation of guilds and *states*).
The Coalition Treaty itself consists roughly of the following parts:
```
+----------------------------------------------------------+
| The Coalition Treaty, of xx/xx/xxxx |
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
| |
| This Treaty shall serve as a foundation for the creation |
| of a super-governmental military body. The Signees of |
| this treay shall receive the following rights and obli- |
| gations. |
| |
| > Each Signee shall receive full military support in ca- |
| se of an attack stemming from outside or inside coa- |
| lition territory |
| |
| > Each Signee shall disband any state-owned military |
| forces immediately upon this treaty's inuring |
| |
| > Each Signee shall disburse an amount of money relative |
| to the richess of their lands, |
| the size of their population, |
| the safer they are from being invaded |
| |
| > Each Signee shall be able to disburse additional funds |
| in return for military services such as but not only |
| - police forces |
| - guard forces |
| |
| > Each Signee shall provide a pool of potential recruits |
| from which to conscript additional forces should they |
| be needed |
| |
| In return the created body shall have to organise itself |
| and provide services as best as is possible within the |
| limits of the provided funds |
+----------------------------------------------------------+
```
The Coalition therefore is basically a private army catering exclusively to the needs of the signees of the Coalition Treaty. It possesses military bases and other assets in most of the signee states. Logically it has to buy things such as provisions and material, weaponry, etc., a whole industry catering to the needs of this huge body will subsequently sprout in the Coalition territory and provide jobs and ways to shift funds back to the signee states.
Now why would they band together against a force that only seems to threaten the easternmost duchies/kingdoms (which themselves anyways chose to abandon the traditional ways for a more eastern approach) and why would the center states even consider the idea which obviously will conclude in bigger expenses for them than so far?
That is easy (mostly), easy: At the convent where most of the states gathered, the point was made that if the easternmost states/duchies/kingdoms fall, there is even less stopping the east army as it would gain a favourable position for annexing the rest of the Midlands. Thus the rich central states have a reason to back something that obviously means higher expenses to them than so far.
---
***Question***: Can a body such as the *Coalition Military Force* work in the described environment? And what issues that I failed to address/addressed *incorrectly* make it not work? | Two historical examples come to mind here.
The first example is the Delian League, which has been alluded to in other answers. Formed by Athens as a reaction to the Persian Wars, the Delian league had various maritime powers band together and pool ships and funds to protect the league and the rest of Greece from any attempt by the Persians to invade again. Very soon, the Athenians simply requested money from the other league members, who were happy to oblige for the most part, since owning a navy is very capital and labour intensive. However, when Athens decided to take full control of the League's treasury, the other members discovered that *not* having a Navy also means not having a vote.
Athens became an Empire in all but name, and the fear of Athenian Power lead to the Peloponnesian Wars.
During the 1400's, Italian City States tended to alternate between citizen militias and hiring professional mercenary companies (Condottieri). The Condottieri quickly discovered that they could play various parities against each other, accept payments to *not* participate in wars or switch sides and otherwise make planning difficult to impossible for the City State authorities (or even overthrowing them if they didn't pay up according to the terms of the contract)
So the essential point is that the hand that holds the sword eventually becomes the hand which holds the gold as well, and also the whip hand giving the orders. In your scenario, the central principalities will quickly discover that what seems to be an unrooted mercenary army is now calling the shots, and their tax revenues are not being spent for the benefit of the citizens of the central provinces.
How this plays out in the end is probably similar to the end of the Italian city states. Weakened by constant internal divisions and shifting alliances, they were unable to present a united front against foreign invaders (one reason Leonardo da Vinci ended up in the French court, for example). The coalition army, not being "rooted" and existing on tax contributions from a disarmed population, becomes predatory against the very people whom it is supposed to protect, and falls apart when directly challenged by an outside force. |
39,010 | <p>I'm rewording the original question as suggested, in an attempt to make it more specific.</p>
<p>We all know we humans affect our environment by building structures, leveling ground etc. but these changes are usually pretty obvious and visible. </p>
<p>As I want to create an alternative Earth world, I thought I could simply use a real map to describe the world; however, having some basic historic knowledge of my hometown, which is a coastal city, I know that it's not simply built around a river, but the river delta has been regulated during the city's development. It made me thinking, how close our current geography is to what it could be without us, and similarly, how whole nature would look if not being influenced by humanity.</p>
<p>I'm not asking to describe all the changes humanity has done, specifically, but for general processes that will help me to investigate specific regions and do a better job at trying to create an alternative history for them. Answers already given are good examples of what I expect and I wonder if there's more ways in which humanity changed the Earth.</p>
<p>An advice has been made by XandarTheZenon, that perhaps this question should be asked on History site. I agree and I might do that, but not before using all my options to make this question valid, since I already asked it here. I stand by this question, as I think understanding how humans affected their environment is the key to create rich, deep worlds and that could be a reason to allow this question to be more vague than others (although I have a feeling there are many questions on this site which introduce such world characteristics that lead to many more possible answers). The additional benefit to asking here is that it allows for more freedom in giving examples (for example, on history site it's less likely to introduce aliens, elves or magical beings in argumentation) as well as is more forgiving for factual inaccuracy and soft-science.</p>
<p>Here's two examples:</p>
<ul>
<li>global warming - people and domesticated animals produced greenhouse gases, which warmed the planet. Without humanity the Earth would be cooler [and with another civilization it could as well be hotter, but let's consider other civilizations outside of the scope of this question]</li>
<li>domesticated animals - people changed the way animals evolved: sometimes indirectly [this could be considered the butterfly effect], and sometimes directly through intended manipulation. So without humanity not only wouldn't we see domesticated animals like dogs, but it's also possible we wouldn't see some "wild" animals like dingoes:</li>
</ul>
<p><a href="https://en.wikipedia.org/wiki/Dingo" rel="nofollow">Wikipedia: Dingo</a></p>
<pre><code>The dingo (Canis lupus dingo) is a wild dog found in Australia. Its exact ancestry
is debated, but dingoes are generally believed to be descended from semi-
domesticated dogs
</code></pre>
| [
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"text": "<p><a href=\"https://en.wikipedia.org/wiki/Deforestation_during_the_Roman_period\">Deforestation</a> is a big issu... | 2016/03/27 | [
"https://worldbuilding.stackexchange.com/questions/39010",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/18753/"
] | I'm rewording the original question as suggested, in an attempt to make it more specific.
We all know we humans affect our environment by building structures, leveling ground etc. but these changes are usually pretty obvious and visible.
As I want to create an alternative Earth world, I thought I could simply use a real map to describe the world; however, having some basic historic knowledge of my hometown, which is a coastal city, I know that it's not simply built around a river, but the river delta has been regulated during the city's development. It made me thinking, how close our current geography is to what it could be without us, and similarly, how whole nature would look if not being influenced by humanity.
I'm not asking to describe all the changes humanity has done, specifically, but for general processes that will help me to investigate specific regions and do a better job at trying to create an alternative history for them. Answers already given are good examples of what I expect and I wonder if there's more ways in which humanity changed the Earth.
An advice has been made by XandarTheZenon, that perhaps this question should be asked on History site. I agree and I might do that, but not before using all my options to make this question valid, since I already asked it here. I stand by this question, as I think understanding how humans affected their environment is the key to create rich, deep worlds and that could be a reason to allow this question to be more vague than others (although I have a feeling there are many questions on this site which introduce such world characteristics that lead to many more possible answers). The additional benefit to asking here is that it allows for more freedom in giving examples (for example, on history site it's less likely to introduce aliens, elves or magical beings in argumentation) as well as is more forgiving for factual inaccuracy and soft-science.
Here's two examples:
* global warming - people and domesticated animals produced greenhouse gases, which warmed the planet. Without humanity the Earth would be cooler [and with another civilization it could as well be hotter, but let's consider other civilizations outside of the scope of this question]
* domesticated animals - people changed the way animals evolved: sometimes indirectly [this could be considered the butterfly effect], and sometimes directly through intended manipulation. So without humanity not only wouldn't we see domesticated animals like dogs, but it's also possible we wouldn't see some "wild" animals like dingoes:
[Wikipedia: Dingo](https://en.wikipedia.org/wiki/Dingo)
```
The dingo (Canis lupus dingo) is a wild dog found in Australia. Its exact ancestry
is debated, but dingoes are generally believed to be descended from semi-
domesticated dogs
``` | I was watching a BBC history documentary about the Romans in Britain earlier today and words along the lines of
>
> History is not like science, when you change one variable in history the others don't stay the same. It's all linked, change anything and there's such a massive cascading effect that it's impossible to say what may have happened.
>
>
>
Here are a couple of the key aspects:
**Extermination of the mega-fauna**. This is still uncertain but it's considered likely that human hunters destabilised the populations and effectively exterminated a lot of these animals.
**Deforestation**. This is a bigger issue than previously mentioned. Not just Central Europe and the Near East but from Britain, which was solid forest, all the way across Russia.
*With just these two differences the world would be a place unrecognisable to us.*
but let's consider the way the things we affect, affect the world in their turn.
Elephants knock over trees, fewer elephants, more trees.
Wild herbivores eat young shoots, also keeping down new trees, [fewer predators, fewer trees, more erosion](http://oregonstate.edu/ua/ncs/archives/2003/oct/scientists-wolves-helping-rebalance-yellowstone-ecosystem).
Beavers build dams, meaning more shallow lakes, lower speed flow on the rivers, less erosion, but we killed all the beavers and cut down the trees that would bind the banks, so even the rivers don't follow the courses they would without us.
A few other things we've done.
Draining the wetlands, this was even done by the Romans.
Extermination of predators, the Iberian Lynx is almost gone, the Eurasian Lion has been gone a long time. The Sabertooth Cat? Not known if this was humans. Marsupial Lion, believed to be humans. |
39,304 | <p>Imagine a world exactly like Earth, complete with humans and all. The scientists of this world suddenly discover that, unless drastic measures are taken, all life on Earth will be eradicated. However, there is one (and only one) option that can save the world, if we can get the funding. This plan would cost an exorbitant amount of money, but has a probable chance of being successful. In this situation, what would happen to the costs of the materials necessary for the plan? Would the sellers raise the price due to the increased demand, or would they lower it in order to make saving the world easier?</p>
| [
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"text": "<p>It is in the sellers' interest to not be wiped out by the same issue that will wipe out everyone else so su... | 2016/04/01 | [
"https://worldbuilding.stackexchange.com/questions/39304",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/17330/"
] | Imagine a world exactly like Earth, complete with humans and all. The scientists of this world suddenly discover that, unless drastic measures are taken, all life on Earth will be eradicated. However, there is one (and only one) option that can save the world, if we can get the funding. This plan would cost an exorbitant amount of money, but has a probable chance of being successful. In this situation, what would happen to the costs of the materials necessary for the plan? Would the sellers raise the price due to the increased demand, or would they lower it in order to make saving the world easier? | We can see what happens already. It happens daily in business. Let's get to work
>
> However, there is one (and only one) option that can save the world, if we can get the funding.
>
>
>
This phrasing indicates either an absurdly unlikely circumstance, or a partial picture. It is very unlikely that there is actually only one solution. For example, let's assume the problem is trivial: "put these 7 numbers in order: 1, 3, 5, 7, 4, 13, 20." There are many solutions such as
* Swap the 5 and the 7. Then swap the 7 and the 4
* Swap the 4 and the 5. Then swap the 5 and the 7.
* Jumble the whole group up, put it through StackSort ([read the image's tooltip](https://xkcd.com/1185/)). Then go get a drink of water.
And so forth. The actual number of degrees of freedom in the problem is quite staggering, especially when you consider the question of "what happens next after we succeed?" Are we thirsty? Maybe the plans that involved drinking water are good!
What you more likely are describing is a case where there is a hard requirement: thou shalt do X, or the entire planet dies. There may be many implementations of X which function, although your word choices indicate that most courses of action will not satisfy X.
Thus the goal of every rational actor in this scenario is two fold:
* Ensure the survival of the planet
* Ensure that, after the planet is saved, their position is as ideal as possible.
*Alternatively, [in mercenary order](http://www.schlockmercenary.com/2000-08-04) of priorities: 1) get paid. 2) live long enough to enjoy getting paid.*
Now this works great as long as everyone has perfect information. However, we don't. Its entirely possible that we may do our part, but someone else slacks off. In this case, we may be obliged to do even more work to save the planet, making up for the slackers. Now we're getting somewhere. This sounds a lot like a traditional Prisoner's Dilemma. This is a dilemma where two individuals (we'll call them Alice and Bob) commit a crime. There's not enough evidence to convict either one, so they are called in for questioning. There, they are provided with a dilemma:
>
> If you agree to testify against your partner, your testimony plus the evidence will be enough to convict him. This same deal is being offered to your partner. We admit, we don't have enough evidence to convict either of you without the other person admitting you two both did it, so here's the deal. If neither of you testify, we're going to convict both of you on a lesser crime, and give you both 1 year in jail. If either of you testifies against the other, they can go scott free, while the other person spends 9 years in jail. If both of you agree to testify, you'll both get convicted, but we'll only sentence you to 3 year.
>
>
>
The logic diagram looks like this
```
Alice
Quiet Testifies
+-------------+--------------+
Quiet | Alice: 1yrs | Alice: 0yrs |
| Bob: 1yrs | Bob: 9yrs |
Bob +-------------+--------------+
Testifies | Alice: 9yrs | Alice: 3yr |
| Bob: 0yrs | Bob: 3yr |
+-------------+--------------+
```
The dilemma forms because the best course of action is to both stay quiet. However, if you both realize this, you have to worry that your partner might try to decrease their own sentence by ratting you out. Thus, you must be conservative and testify. The result of the dilemma is that the most rational course of action is to testify, and both of you serve 3 years, even though you could have gotten away with just 1.
We can draw an analogy to our example. Instead of "Quiet" and "Testify," we can "Conform" to what is best for the planet, or "Defect" and do what is best for us
```
Alice
Conform Defect
+---------------------+--------------------+
Conform | Everyone lives | Everyone lives |
| Everyone is even | Alice makes money |
Bob +---------------------+--------------------+
Defect | Everyone lives | Everyone dies |
| Bob makes money | Everyone is unhappy|
+---------------------+--------------------+
```
Obviously this pattern has more players, but the basic story with two players is enough to understand what is happening. The correlary to the prisoner's dilemma suggests that everyone gets greedy, then dies.
However, that's not the end of the story for this dilemma. You see, if it was that simple, being a prosecutor or Attorney General would be a piece of cake! In reality, this doesn't work. We find that criminals refuse to snitch on each other with *remarkable* consistency. There's clearly a second force going on in the real world! From talking with criminals, we find the answer is obvious. A snitch doesn't get very far in the crime world. If you snitch, you've basically ended your career as a criminal. Nobody will work with a snitch, and everybody knows it. So this adjusts the logic of both Alice and Bob in our example. Both of them know the other person knows that snitches will be brutally punished. They may avoid a few years of jail time, but the trade isn't worth it. This knowledge is enough to get both Alice and Bob to conform, refusing to testify against their partner, and both get a year in prison.
Likewise the global "essence" will likely rise up to try to find ways to ensure conformance. This will likely be in the form of governments putting dramatic pressure on companies to not defect in the name of profit. Sure, they can defect, but it might be the straw that broke the camel's back, causing the earth to die, and even if someone else did cover for them, they'd be labeled as a profiteering pile of filth and nobody will work with them, nor accept their money.
The real question is not whether there will be defectors, but whether second order effects will creep in. At some point, when you're leaning on a company to do something "for the common good" rather than "for your own profit," you can lean hard enough that the company gives you the middle finger, and folds up instead. The challenge for the government is to find ways to put pressure on the companies without causing them to fold up.
There's another related experiment that has been done, involving two parties. Each party is assigned a random role. The first party is given two envelopes and some money, say $100. They are told to divide the money up between the two envelopes. One is money they will keep, and the other is kept by the second party. The second party is then permitted to look at the distribution of cash, and make a choice. They can either take their money, and the first person keeps theirs, or they can refuse it, and the first person gets nothing.
The game theory logic for player one is simple. The first person's goal is to get as much money as they can, without causing the second player to defect. If they defect, nobody gets any money. The second player's logic is theoretically easy: just take the money, you always profit. However, if the first player knows this, they may only leave $1.
This scenario is not well described in game theory. You actually need drama theory to make sense of the results. However, the results are easy to spot. In America, the most common result was a 50/50 split. If the first person tried to take more money, such as a 90/10 split, the second person would punish them by making sure nobody gets money.
In some African nations, the result was different. The first player would choose 90/10, and the second player would accept. When asked why, the answer would be "because \10 is better than \$0, and if I was in the first player's position, I'd have gotten to have the $90 anyways." In some groups, the split was actually quite arbitrary. It was found these groups were known for sharing everything as a group. It really didn't matter if the split was 50/50 or 90/10, they were going to pool the money later once both parties got back together!
So this is the stage for where your question really ends up. Large powers like governments will put pressure on the companies to band together and do things for the common good. The amount of pressure they can put on the companies before they defect depends on the culture.
So now we get back to the original issue of many solutions to the problem. The more solutions there are, the less pressure will be needed to ensure enough conformance to survive. As the number of solutions get smaller, more pressure will be needed, causing more companies to defect. At some point, that can be the end of humanity. However, we cannot know one way or another without a very lengthy exploration of exactly what scenario we are in, and what solutions present. |
39,475 | <p>Many scifi stories feature a vast interstellar empire that spans more worlds and races than a single being could hope to visit in a lifetime. These empires, in many cases, are highly centralized and have an all-powerful emperor who delegates power to military leaders who deal with the civilian governments in the systems in their spheres of influence. Let us assume that humanity unites and the United Nations transforms into the first global democracy and we spreads through the stars and colonize millions of worlds, both uninhabitable and habitable.</p>
<p>These colonies band together into a loose confederation of planets and an official loose military and administrative alliance is established not unlike a scaled-up version of the American colonies after they broke away from England. This alliance is centered on Earth, the first city-world. An official Confederate Navy is established that is comprised of primarily planetary security forces and militia. Over time, humanity meets many less advanced races with what we would consider "modern" technology. Most of these races petition to be admitted entry into the confederation.</p>
<p>Now we have the type of confederation/republic depicted in many prominent scifi works. <strong>How can we take this fragile political entity and turn it into a galactic empire centered around a single all-powerful emperor?</strong></p>
<p><strong>EDIT:</strong></p>
<p>There is FTL travel and communication.</p>
<h1>EDIT2</h1>
<p>Humanity has been spacefaring for about 300 years and started with the discovery of FTL in 2125 during a mass famine on Earth. FTL was relatively cheap, with transportation of a squad of 40 or 50 soldiers costing 150 million USD. With the advent of new technologies such as worm-hole drives that can be put on any ship, FTL has become insanely easy and cheap. If a ship does not have FTL capabilities it almost certainly was built by imbeciles.</p>
<p>When humanity met other races and those races asked for admittance into the Confederation, they were granted basic 22nd century FTL technology so that their leaders could attend senate meetings. The structure of the Confederate government is as follows;</p>
<h2>Prime Minister</h2>
<p>Head of State. Can be chosen from among any of the political leaders of the Confederate worlds if they have been members of the Confederacy for more than 50 years. The Prime Minister must also be an adult (this is relative to species) and a citizen born in the Confederacy. A member of any race in the Confederacy can become Prime Minister so long as they learn to use The Galactic Standard, an electronic device that allows instant translation from the host language to the written language of all other races present. The President can Veto the decisions made by the Senate.</p>
<h2>Senate</h2>
<p>An official legislative body that governs the Confederacy at large. The job of settling border disputes betweens members, ordering sanctions on defiant member worlds, and taxation as well as fall on this body. Helping members deal with natural disasters (like that rare asteroid that satellite defense systems miss and hits the planet) also falls within the jurisdiction of this branch. The Senate can propose laws as well a veto those proposed by the Prime Minister.</p>
<h2>General Assembly</h2>
<p>This is the most powerful branch of government, and it has final say in all things. It is comprised of the former human leaders of Earth, with one leader to represent the historic nations of the 20th Century before the Confederation was formed. While every one of these nation-states is de-jure independent in theory, they are in practice one state. They surrendered their sovereignty when the major nations of the Earth surrendered their entire militaries to the United Nations in the Treaty of Koningsburg in 2124.</p>
<h2>Judicial</h2>
<p>The Confederation has no official judicial branch. Major disputes in law are settled by the General Assembly (which is all too often prejudiced against the non-human races). In almost all cases the law is settled by either independent system or sector governments (it varies widely as some systems have subjugated (to the meaningless protests of the Senate) entire sectors. Confederate law states that members may not wage war, but often rival governments will wage proxy wars and occasionally simply openly defy the Confederation.</p>
<h1>Military</h1>
<p>Now, let's face it; if you have mass shipping, you will eventually have pirates. Human greed guarantees this, and most alien races have the exact same problem we do. Wherever there is money to be made, there is somebody willing to steal it and kill for it. If you don't want these marauders to make off with your gold, women and children, what do you do? You either shoot them, or make the gold, women, and children so dangerous and hard to get that they do not try. The local governments (often funded and urged by large corporations) each have their own professional army and fleet. These vary in size according to technological level and industrial capacity as well as population size, and with over a million local governments it is unrealistic to expect me to convey all the different organizational and technological differences in every army and fleet.</p>
<p>The Confederation has a small navy. The Confederate Navy (CN) is comprised of about 10,000 Beijing Class Cruisers that can carry about 10,000 soldiers and 1000 Troop Transports. Each cruiser also carries four full wings of fighters and is escorted by 6 Moscow Class Destroyers and a dozen frigates, which can serve a variety of tasks. A typical Confederate fleet will be comprised like this;</p>
<pre><code>Confederate Fleet ->
Capital Cruiser ->
4 fighter wings ->
16 fighter squads ->
20 fighters
10 bombers
500 Landing Craft ->
20 Marines
20 Heavy Assault Androids
20 Mobile nano-artillery pieces (i feel the need to say that these fire canisters full of nano bots that automatically eat enemy Androids. Cool!)
50 Recon drones
6 Destroyers ->
2 advanced landing craft
6 Marines
10 Recon Drones
10 Heavy Assault Androids
20 Frigates ->
500 - 1000 Confederate Militia Soldiers
As much supplies as can be packed aboard the massive cargo holds.
</code></pre>
<p>Confederate naval ranking goes like this;</p>
<pre><code>Grand Admiral ->
Marine General ->
Deployment Commander ->
Battalion Commander->
Group Commander ->
Team Leader ->
Lieutenant ->
private
Corporal ->
private
High Admirals ->
Admirals ->
Rear Admiral ->
Group Leader ->
Captain ->
Crew Commander ->
Petty Officer
Marine Group Commander ->
Team Leader ->
Lieutenant ->
private
Corporal ->
private
</code></pre>
<p>The official Confederate Army is nothing more than the Armies of Earth. Their structures vary as there has been no direct need as of yet to centralize the structure aside from a few relatively minor authority disputes and conflict resolution missions.</p>
<h1>Religion</h1>
<p>Most major religions have survived and spread to the stars. Hardcore fundamentalists are often prejudiced against all non-human lifeforms and the space equivalent of an outlawed KKK nick-named the "Enforcers of God" was formed by the Christian Fundamentalist world of New Constantinople VI B, a moon orbiting a gas giant in the habitable zone of the fictional star of Constantinople IV<sup>[1]</sup>.</p>
<h1>Other Political Entities</h1>
<p>There are a number of systems not in the Confederation. The Confederation does not militarily expand and only gains ground by the petitions for admittance coming from rim worlds. Secession, however, is not legal. Once in the Confederation, you are in for the long-run.</p>
<h2>Krenn</h2>
<p>The most powerful Confederate neighbor is also the most peaceful galactic participant, and remains neutral in most, if not all, conflicts. The concept of the "individual" does not exist for this species, known in Confederate space as the Krenn. Each Krenn world has a High Queen who lays eggs that hatch to produce Queens, which rule regions of their worlds and lay eggs that hatch to form workers, soldiers, engineers, and brains<sup>[2]</sup>.</p>
<p>The Krenn bodily structure faintly resembles some long-extinct Earth colonial insects and their origin is unknown. They claim to be evolved from massive insects on their home-world, but Confederate scientists claim they were genetically engineered by a long-extinct race, possibly as weapons of mass destruction. Scientists support this evidence with that some of the oldest Krenn buildings and starships look like they were designed for someone with a more humanoid form<sup>[3]</sup>. The Krenn have colonized over a thousand systems.</p>
<h2>Alari</h2>
<p>The Alari are tough, humanoid, warlike race. They raid Confederate space from time to time, though they are only settled in a dozen systems. They have instigated three large-scale conflicts with the peaceful Krenn<sup>[4]</sup>. They are only a minor threat.</p>
<h2>Qalik</h2>
<p>These are a humanoid race that are highly integrated with technology. They live in no specific system, drifting along in massive brain ships. It is unknown what happens in them, but it is well-known to never attack one; everyone who tries dies. They make no attempt to communicate with other races, believing themselves to be superior and god-like to the lowly lifeforms still controlled by biological limits.</p>
<h1>Others</h1>
<p>There are numerous races bordering Confederate space. Some are peaceful and some are warlike. Some are humanoid, some are not. These are some others worth noting.</p>
<h2>Altorans</h2>
<p>A race dominated by commerce. While not afraid to defend themselves and while not technologically inferior in any way, they prefer peaceful trading and see war as bad for buisness.</p>
<h2>Mil</h2>
<p>The Mil are renowned weapon builders and designers. All other races compete to gain a monopoly on Mil weapons. This has sparked several unsuccessful attempt to subjugate this race by its neighbors, including the fearsome Alari. These always end in the vaporization of the attacking race. The Confederation recently signed a military alliance treaty with the Mil. The Mil are centered in the Mil system, the only known system with four habitable worlds. All of these worlds are heavily populated.</p>
<h2>Grennolis</h2>
<p>The Grennolis is yet another highly militarized race. They are the only other race known to be able to interbreed with humans. Many animals on their homeworld Grennoli strongly resemble Earth creatures that lived in the 21st Century before the mass extinction Humans brought upon Terra. The Grennolis have settled small colonies and basis in nearly a hundred systems, but none of these aside from the homeworld are developed. They gained their FTL capabilities by attacking a joint Altoran/Mil trading convoy passing through their system. This has alienated both of these races. Recently the Grennolis have signed an offensive alliance pact woth the Alari, which has allowed both them and the Alari to subjugate their immediate weaker neighbors and to both build decent-sized empires.</p>
<h1>Current Political Situation</h1>
<p>The year is 2375 AD.</p>
<p>Despite the relative weakness of the Alari and Grennolis Alliance population-wise, the Alari fleet alone is double the size of the Confederate Navy. The Grennolis Army is equipped with stealth technology that would make any general envious. There has been a decent build-up along the border between the Alari and Mil which has lead to a desperate Mil petitioning the Confederation for full admittance. The petition has been tied up in the Senate and GA intrigues for over a year now. To make matters worse, the Confederation is in the middle having one of its bi-decal elections.</p>
<p>There is some talk in the senate of postponing the elections. A poweful faction in the Senate is trying to push through an Ultimatum-bill to the GA to be sent to the Alari basically demanding they remove their fleets from the border. The only reason this has not been passed is because about 30% of the Senate is against this, knowing it will likely force the Confederation into a bloody war which it might or might not win.</p>
<p>Anti-alien sentiments are running high in the GA as well as some factions in the senate, and any alliance or admittance terms will likely have to favor humanity.</p>
<p>The current President is highly popular and there is a very good chance he will be reelected for a fifth term. He believes in democratic ideals, however, and would never try to force the Confederation into an Empire.</p>
<h1>Current Military Situation</h1>
<p>The Grennolis and Alari have begun a massive build-up along the bordersystems and raiders and pirates using Alari ships have been frequenting shipping lanes near the borders. This has resulted in a massive Confederate build-up. Hundreds of thousands of civilians have been drafted and local governments have been ordered to support Confederate forces. Over a hundred private military companies have been hired by both sides and five hundred new shipyards have been commissioned by the Confederate government.</p>
<p>Over a thousand wings of fighters have been commissioned and are in the process of being manufactured. The Confederate government has went quintillions of Galactic Confederate Credits into debt to pay for these armaments. Research in biological weapons has been secretly commissioned by the pro-human GA and test targets have been chosen. They are testing the new weapons on minor races that resemble the Alari physically the most. Worm-bombs, a relatively new weapon that opens a worm-hole that can destroy entire systems if placed near the star<sup>[5]</sup> are being mass-produced by the Confederate government.</p>
<h3>Footnotes</h3>
<p>The aliens humanity has encountered have an even wider variety of religious beliefs, ranging from machine worshipping to christian-like religions. A very large fraction of them have abandoned religion in favor of other ideals, seeing the existence of so many different species as proof against whatever they believed before. </p>
<p><sup>1</sup> I know; these people are insanely original. Interestingly enough, there is a nearby primarily Turkish (muslim fundamentalist) settled system whose capital planet is named New Istanbul IV, so the problem is not only restricted to the Greeks. There is also a rivalry between the two and there are often small-scale conflicts over minor border issues (under who's jurisdiction does that space station between the two systems fall to?).</p>
<p><sup>2</sup> These are the Krell equivalent of scientists. Brains act as a sort of super-computer for this race, allowing the Queens to process massive amounts of data as well as pumping out new weapons and architecture schematics for the engineers to use.</p>
<p><sup>3</sup> The evidence; devices meant to be operated by a being with six fingers; the Krenn have three or four fingers depending on their biological job.</p>
<p><sup>4</sup> Funny thing too; the Alari have lost every one of those wars.</p>
<p><sup>5</sup> Technically it was outlawed during the forty-fourth Convention of Earth after an alien terrorist nearly unleashed one on Terra.</p>
<p><sup>Little note</sup> This is actually for a space strategy RTS I am working on for mobile. Don't have screenshots, but most of the logic is laid down and now I just have to find some art assets and work on my (not-so) intuitive user interface. The game is 2D. Combine Civilization 1 with Age of Empires and you have a general idea of what my game should feel like. I have a lot of small-scale projects I work on.</p>
| [
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"text": "<p>There has to be a catastrophe or other threat. This creates a need for a stronger navy or central government.... | 2016/04/05 | [
"https://worldbuilding.stackexchange.com/questions/39475",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/6799/"
] | Many scifi stories feature a vast interstellar empire that spans more worlds and races than a single being could hope to visit in a lifetime. These empires, in many cases, are highly centralized and have an all-powerful emperor who delegates power to military leaders who deal with the civilian governments in the systems in their spheres of influence. Let us assume that humanity unites and the United Nations transforms into the first global democracy and we spreads through the stars and colonize millions of worlds, both uninhabitable and habitable.
These colonies band together into a loose confederation of planets and an official loose military and administrative alliance is established not unlike a scaled-up version of the American colonies after they broke away from England. This alliance is centered on Earth, the first city-world. An official Confederate Navy is established that is comprised of primarily planetary security forces and militia. Over time, humanity meets many less advanced races with what we would consider "modern" technology. Most of these races petition to be admitted entry into the confederation.
Now we have the type of confederation/republic depicted in many prominent scifi works. **How can we take this fragile political entity and turn it into a galactic empire centered around a single all-powerful emperor?**
**EDIT:**
There is FTL travel and communication.
EDIT2
=====
Humanity has been spacefaring for about 300 years and started with the discovery of FTL in 2125 during a mass famine on Earth. FTL was relatively cheap, with transportation of a squad of 40 or 50 soldiers costing 150 million USD. With the advent of new technologies such as worm-hole drives that can be put on any ship, FTL has become insanely easy and cheap. If a ship does not have FTL capabilities it almost certainly was built by imbeciles.
When humanity met other races and those races asked for admittance into the Confederation, they were granted basic 22nd century FTL technology so that their leaders could attend senate meetings. The structure of the Confederate government is as follows;
Prime Minister
--------------
Head of State. Can be chosen from among any of the political leaders of the Confederate worlds if they have been members of the Confederacy for more than 50 years. The Prime Minister must also be an adult (this is relative to species) and a citizen born in the Confederacy. A member of any race in the Confederacy can become Prime Minister so long as they learn to use The Galactic Standard, an electronic device that allows instant translation from the host language to the written language of all other races present. The President can Veto the decisions made by the Senate.
Senate
------
An official legislative body that governs the Confederacy at large. The job of settling border disputes betweens members, ordering sanctions on defiant member worlds, and taxation as well as fall on this body. Helping members deal with natural disasters (like that rare asteroid that satellite defense systems miss and hits the planet) also falls within the jurisdiction of this branch. The Senate can propose laws as well a veto those proposed by the Prime Minister.
General Assembly
----------------
This is the most powerful branch of government, and it has final say in all things. It is comprised of the former human leaders of Earth, with one leader to represent the historic nations of the 20th Century before the Confederation was formed. While every one of these nation-states is de-jure independent in theory, they are in practice one state. They surrendered their sovereignty when the major nations of the Earth surrendered their entire militaries to the United Nations in the Treaty of Koningsburg in 2124.
Judicial
--------
The Confederation has no official judicial branch. Major disputes in law are settled by the General Assembly (which is all too often prejudiced against the non-human races). In almost all cases the law is settled by either independent system or sector governments (it varies widely as some systems have subjugated (to the meaningless protests of the Senate) entire sectors. Confederate law states that members may not wage war, but often rival governments will wage proxy wars and occasionally simply openly defy the Confederation.
Military
========
Now, let's face it; if you have mass shipping, you will eventually have pirates. Human greed guarantees this, and most alien races have the exact same problem we do. Wherever there is money to be made, there is somebody willing to steal it and kill for it. If you don't want these marauders to make off with your gold, women and children, what do you do? You either shoot them, or make the gold, women, and children so dangerous and hard to get that they do not try. The local governments (often funded and urged by large corporations) each have their own professional army and fleet. These vary in size according to technological level and industrial capacity as well as population size, and with over a million local governments it is unrealistic to expect me to convey all the different organizational and technological differences in every army and fleet.
The Confederation has a small navy. The Confederate Navy (CN) is comprised of about 10,000 Beijing Class Cruisers that can carry about 10,000 soldiers and 1000 Troop Transports. Each cruiser also carries four full wings of fighters and is escorted by 6 Moscow Class Destroyers and a dozen frigates, which can serve a variety of tasks. A typical Confederate fleet will be comprised like this;
```
Confederate Fleet ->
Capital Cruiser ->
4 fighter wings ->
16 fighter squads ->
20 fighters
10 bombers
500 Landing Craft ->
20 Marines
20 Heavy Assault Androids
20 Mobile nano-artillery pieces (i feel the need to say that these fire canisters full of nano bots that automatically eat enemy Androids. Cool!)
50 Recon drones
6 Destroyers ->
2 advanced landing craft
6 Marines
10 Recon Drones
10 Heavy Assault Androids
20 Frigates ->
500 - 1000 Confederate Militia Soldiers
As much supplies as can be packed aboard the massive cargo holds.
```
Confederate naval ranking goes like this;
```
Grand Admiral ->
Marine General ->
Deployment Commander ->
Battalion Commander->
Group Commander ->
Team Leader ->
Lieutenant ->
private
Corporal ->
private
High Admirals ->
Admirals ->
Rear Admiral ->
Group Leader ->
Captain ->
Crew Commander ->
Petty Officer
Marine Group Commander ->
Team Leader ->
Lieutenant ->
private
Corporal ->
private
```
The official Confederate Army is nothing more than the Armies of Earth. Their structures vary as there has been no direct need as of yet to centralize the structure aside from a few relatively minor authority disputes and conflict resolution missions.
Religion
========
Most major religions have survived and spread to the stars. Hardcore fundamentalists are often prejudiced against all non-human lifeforms and the space equivalent of an outlawed KKK nick-named the "Enforcers of God" was formed by the Christian Fundamentalist world of New Constantinople VI B, a moon orbiting a gas giant in the habitable zone of the fictional star of Constantinople IV[1].
Other Political Entities
========================
There are a number of systems not in the Confederation. The Confederation does not militarily expand and only gains ground by the petitions for admittance coming from rim worlds. Secession, however, is not legal. Once in the Confederation, you are in for the long-run.
Krenn
-----
The most powerful Confederate neighbor is also the most peaceful galactic participant, and remains neutral in most, if not all, conflicts. The concept of the "individual" does not exist for this species, known in Confederate space as the Krenn. Each Krenn world has a High Queen who lays eggs that hatch to produce Queens, which rule regions of their worlds and lay eggs that hatch to form workers, soldiers, engineers, and brains[2].
The Krenn bodily structure faintly resembles some long-extinct Earth colonial insects and their origin is unknown. They claim to be evolved from massive insects on their home-world, but Confederate scientists claim they were genetically engineered by a long-extinct race, possibly as weapons of mass destruction. Scientists support this evidence with that some of the oldest Krenn buildings and starships look like they were designed for someone with a more humanoid form[3]. The Krenn have colonized over a thousand systems.
Alari
-----
The Alari are tough, humanoid, warlike race. They raid Confederate space from time to time, though they are only settled in a dozen systems. They have instigated three large-scale conflicts with the peaceful Krenn[4]. They are only a minor threat.
Qalik
-----
These are a humanoid race that are highly integrated with technology. They live in no specific system, drifting along in massive brain ships. It is unknown what happens in them, but it is well-known to never attack one; everyone who tries dies. They make no attempt to communicate with other races, believing themselves to be superior and god-like to the lowly lifeforms still controlled by biological limits.
Others
======
There are numerous races bordering Confederate space. Some are peaceful and some are warlike. Some are humanoid, some are not. These are some others worth noting.
Altorans
--------
A race dominated by commerce. While not afraid to defend themselves and while not technologically inferior in any way, they prefer peaceful trading and see war as bad for buisness.
Mil
---
The Mil are renowned weapon builders and designers. All other races compete to gain a monopoly on Mil weapons. This has sparked several unsuccessful attempt to subjugate this race by its neighbors, including the fearsome Alari. These always end in the vaporization of the attacking race. The Confederation recently signed a military alliance treaty with the Mil. The Mil are centered in the Mil system, the only known system with four habitable worlds. All of these worlds are heavily populated.
Grennolis
---------
The Grennolis is yet another highly militarized race. They are the only other race known to be able to interbreed with humans. Many animals on their homeworld Grennoli strongly resemble Earth creatures that lived in the 21st Century before the mass extinction Humans brought upon Terra. The Grennolis have settled small colonies and basis in nearly a hundred systems, but none of these aside from the homeworld are developed. They gained their FTL capabilities by attacking a joint Altoran/Mil trading convoy passing through their system. This has alienated both of these races. Recently the Grennolis have signed an offensive alliance pact woth the Alari, which has allowed both them and the Alari to subjugate their immediate weaker neighbors and to both build decent-sized empires.
Current Political Situation
===========================
The year is 2375 AD.
Despite the relative weakness of the Alari and Grennolis Alliance population-wise, the Alari fleet alone is double the size of the Confederate Navy. The Grennolis Army is equipped with stealth technology that would make any general envious. There has been a decent build-up along the border between the Alari and Mil which has lead to a desperate Mil petitioning the Confederation for full admittance. The petition has been tied up in the Senate and GA intrigues for over a year now. To make matters worse, the Confederation is in the middle having one of its bi-decal elections.
There is some talk in the senate of postponing the elections. A poweful faction in the Senate is trying to push through an Ultimatum-bill to the GA to be sent to the Alari basically demanding they remove their fleets from the border. The only reason this has not been passed is because about 30% of the Senate is against this, knowing it will likely force the Confederation into a bloody war which it might or might not win.
Anti-alien sentiments are running high in the GA as well as some factions in the senate, and any alliance or admittance terms will likely have to favor humanity.
The current President is highly popular and there is a very good chance he will be reelected for a fifth term. He believes in democratic ideals, however, and would never try to force the Confederation into an Empire.
Current Military Situation
==========================
The Grennolis and Alari have begun a massive build-up along the bordersystems and raiders and pirates using Alari ships have been frequenting shipping lanes near the borders. This has resulted in a massive Confederate build-up. Hundreds of thousands of civilians have been drafted and local governments have been ordered to support Confederate forces. Over a hundred private military companies have been hired by both sides and five hundred new shipyards have been commissioned by the Confederate government.
Over a thousand wings of fighters have been commissioned and are in the process of being manufactured. The Confederate government has went quintillions of Galactic Confederate Credits into debt to pay for these armaments. Research in biological weapons has been secretly commissioned by the pro-human GA and test targets have been chosen. They are testing the new weapons on minor races that resemble the Alari physically the most. Worm-bombs, a relatively new weapon that opens a worm-hole that can destroy entire systems if placed near the star[5] are being mass-produced by the Confederate government.
### Footnotes
The aliens humanity has encountered have an even wider variety of religious beliefs, ranging from machine worshipping to christian-like religions. A very large fraction of them have abandoned religion in favor of other ideals, seeing the existence of so many different species as proof against whatever they believed before.
1 I know; these people are insanely original. Interestingly enough, there is a nearby primarily Turkish (muslim fundamentalist) settled system whose capital planet is named New Istanbul IV, so the problem is not only restricted to the Greeks. There is also a rivalry between the two and there are often small-scale conflicts over minor border issues (under who's jurisdiction does that space station between the two systems fall to?).
2 These are the Krell equivalent of scientists. Brains act as a sort of super-computer for this race, allowing the Queens to process massive amounts of data as well as pumping out new weapons and architecture schematics for the engineers to use.
3 The evidence; devices meant to be operated by a being with six fingers; the Krenn have three or four fingers depending on their biological job.
4 Funny thing too; the Alari have lost every one of those wars.
5 Technically it was outlawed during the forty-fourth Convention of Earth after an alien terrorist nearly unleashed one on Terra.
Little note This is actually for a space strategy RTS I am working on for mobile. Don't have screenshots, but most of the logic is laid down and now I just have to find some art assets and work on my (not-so) intuitive user interface. The game is 2D. Combine Civilization 1 with Age of Empires and you have a general idea of what my game should feel like. I have a lot of small-scale projects I work on. | The 'easiest' would be an outside threat to the members of the confederation. Like the Borg or some other species bent on domination and conquest.
We would band together (hopefully) to help each other survive and push back this mutual threat. (Though sitting by the way side and hoping the threat passes you by will be a strategy some will take.)
The other would be some kind of dictator like Palpatine/Hitler, slowly, often by trickery (at the beginning), to get systems and groups to support him/her/it. After a while, when they have a significant following, they start pressuring more to 'join' and eventually the hold out will be conquered. |
40,093 | <p>Let's say that humans suddenly discovered a way to time-travel. We could theoretically go back in time, take (or buy) some artifacts, and sell them in the future as antiques. Repeating this, pretty much anyone with access to this technology could become very wealthy, to say the least. Would some kind of hyperinflation happen to the value of currency, or would nothing much change?</p>
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"text": "<p>It depends on how your time travel works. But lets assume that you can change the past.</p>\n\n<p>original time... | 2016/04/15 | [
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] | Let's say that humans suddenly discovered a way to time-travel. We could theoretically go back in time, take (or buy) some artifacts, and sell them in the future as antiques. Repeating this, pretty much anyone with access to this technology could become very wealthy, to say the least. Would some kind of hyperinflation happen to the value of currency, or would nothing much change? | It depends on how your time travel works. But lets assume that you can change the past.
original time line T0
```
Piccaso paints a picture.
Piccaso sells picture for beer
Piccaso dies
people see picture and like it
Piccaso becomes famous
Pictures value increases
Picture is sold for millions
```
time traveller time line T1
```
Piccaso paints picture
Piccaso sells picture for beer to time traveller
Piccaso dies
Time traveller finds picture by unknown artist is worthless
```
You could argue that if you only take one of many pictures from piccaso then the 'undiscovered work' will still be worth millions. However this only works when there are few, or one, time travellers.
Lets consider another senario
T0
```
The library of alexandria burns to the ground
thousands of ancient scrolls and artifacts of intrinsic historical value are lost.
A few artifacts are rescued from the flames and buried
a thousand years pass
the few remaining artifacts come to light and are worth millions
```
T1
```
Time travellers steal everything from the library of alexandria and set it alight to cover thier crime
The library of alexandria burns to the ground
Time travellers bury items to dig up in 1000 years
'Lost' artifacts are sold for millions
```
T2
```
Time travellers steal everything from the library of alexandria and set it alight to cover thier crime
The first set of Time travellers arrive to find library in flames
T1 time travellers return to the future and bitch about how thier plan didnt work
Time cops hear the story and decide to investigate..
```
T3
```
Timecops arrive in alexandria the night before the fire
Time travellers arrive and are arrested
Timecops set library alight 'to protect the future!' And return
first Time travellers arrive to find library in flames
time travellers return to the future and bitch...
timecops hear the story...
```
To make money from your time thefts you need your timeline to remain essentialy the same after you have returned from the past. This is difficult to achieve unless time travel is restricted in some way |
41,981 | <p>The Bartering system is a means of trading goods for other other goods, very similar to the Currency system except minus the money. The problem is that as the population of a location increases people begin to disagree on the value of the items; what use is a goat to a sailor compared to a baker? So the simplest solution is to create a currency system. It just becomes to unstable to depend on a barter system, so what can I do to make a barter system stable in a modern American society?</p>
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"text": "<p>Currency is not <strong>just</strong> about setting value for bartered goods. Money is a <em>common</em> yardst... | 2016/05/21 | [
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```
Simple example with three people:
person 'A' has a sword and wants a massive block of marble.
person 'B' has a massive block of marble and wants a wheel of cheese.
person 'C' has a wheel of cheese and wants a sword.
Barter solution: they all meet in one place and trade items.
```
Possible problems with barter shown using this example:
```
1) Lack of information: How do the three discover that collectively
they have the items they want so they can agree to the barter?
2) Inequality of value: 'A' thinks his sword is worth more than the
crappy block of marble offered by 'B'. How do you trade half
a sword?
3) Non-portability of items: transporting the marble block to the
barter is difficult.
4) Non durability of items: The wheel of cheese will go bad over
time, requiring the barter to be completed quickly.
```
Currency fixes all four of these problems:
```
1) No need to match what you have to what someone else has;
make a currency sale and then a currency purchase instead.
2) If your item is worth more than an item you want, you end up
with extra currency to use later.
3) currency is portable, unlike a block of marble.
4) currency hold value over time, unlike cheese (ignoring
the whole fiat money/inflation issue here).
```
Currency also tends to be divisible into small enough values (no selling a single item for 1/2 penny) and be acceptable by everyone in the economy.
I don't think the efficiency of currency over barter will allow you to create a realistic complex society that uses ONLY barter, at least as long as your world rewards economic efficiency. Simple or small economies can get away with barter.
Now to answer your question.
If your world has cultural values that totally ignore economic efficiency, then that society might avoid currency and only use barter. "Our religion has banned money/coins".
If your world has a has an efficient way of discovering possible barters, ala internet matching of potential barters, then two of the problems of barter, lack of information and non-portability of items can be greatly reduced. You will still have problems of inequality of trades and non-durability of items though.
My final answer is that you might want to consider a world with multiple non-traditional forms of currency. This would somewhat resemble a barter economy where you bartered (using non traditional currencies such as grain, crude oil, or other evenly divisible and value holding "things" like that). Your exchange rate between your non-traditional currencies (grain vs. crude oil) could be published so as to help potential buyers or traders decide on what form of 'currency' they wanted to use for the transaction. |
46,415 | <p>I want to create a world that abides completely by our understanding of reality. The whole premise is that "If the Universe is large enough, this would all be non-fiction", assuming the laws of physics are constant everywhere. It absolutely must be 100% scrutiny-proof.</p>
<p>Firstly, the planet is designed to be a sort of superficial "Parallel Earth". However, the actual workings of the planet and its species can be adapted as needed. The planet will have large amounts of gigantism (pun intended). The planet will include human-like natives; <a href="https://en.wikipedia.org/wiki/Manta_ray" rel="noreferrer">ray</a>-like whales that are 60-80m long; 'Sauropods' on par with the largest <a href="https://en.wikipedia.org/wiki/Titanosaur" rel="noreferrer">titanosaurs</a>. But the most limiting factor is having theropod-like dragons (technically <a href="https://en.wikipedia.org/wiki/Wyvern" rel="noreferrer">wyverns</a>), preferably upwards of 10m in length.</p>
<p>I've plugged some numbers into various calculations and I've settled on the following properties:</p>
<pre><code>Surface Area: 602,000,000km2 (18% larger than Earth)
Radius: 6.923.5km (8.5% larger than Earth)
Mass: 3.524*10^24kg (41% less than Earth I *think*)
Volume: 1,390,160,000,000km3 (28% larger than Earth)
Gravity: 4.9m/s/s (Half of Earth)
Density: 2.83g/cm3 (54% less than Earth)
</code></pre>
<p>With the atmospheric density 6x higher than Earth (around 7.2kg/m3) this gives an 850kg limit of flight if the 70kg <a href="https://en.wikipedia.org/wiki/Argentavis" rel="noreferrer">Argentavis</a> is used as a maximum, or a 2400kg if the <a href="https://en.wikipedia.org/wiki/Quetzalcoatlus" rel="noreferrer">Quetzalcoatlus</a> is used as a limit. I originally had it at 3x Earth's.</p>
<p>Would these figures yield a stable planet? </p>
<p>Would the mass of the planet have a large enough magnetic field to hold such an atmosphere? Could I increase the atmospheric density to 12x Earths or higher? What sort of atmospheric composition would it need? How would I achieve a planet with the right conditions and parameters if this isn't stable? </p>
<p>The larger surface area allows more room for life (and thus giant life), whilst having larger oceans to support a denser atmosphere. A higher level of volcanic activity would also be included.</p>
<p>I did intend for it to be a binary planet as well, but all these kinds of things can be changed.</p>
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"https://worldbuilding.stackexchange.com/questions/46415",
"https://worldbuilding.stackexchange.com",
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] | I want to create a world that abides completely by our understanding of reality. The whole premise is that "If the Universe is large enough, this would all be non-fiction", assuming the laws of physics are constant everywhere. It absolutely must be 100% scrutiny-proof.
Firstly, the planet is designed to be a sort of superficial "Parallel Earth". However, the actual workings of the planet and its species can be adapted as needed. The planet will have large amounts of gigantism (pun intended). The planet will include human-like natives; [ray](https://en.wikipedia.org/wiki/Manta_ray)-like whales that are 60-80m long; 'Sauropods' on par with the largest [titanosaurs](https://en.wikipedia.org/wiki/Titanosaur). But the most limiting factor is having theropod-like dragons (technically [wyverns](https://en.wikipedia.org/wiki/Wyvern)), preferably upwards of 10m in length.
I've plugged some numbers into various calculations and I've settled on the following properties:
```
Surface Area: 602,000,000km2 (18% larger than Earth)
Radius: 6.923.5km (8.5% larger than Earth)
Mass: 3.524*10^24kg (41% less than Earth I *think*)
Volume: 1,390,160,000,000km3 (28% larger than Earth)
Gravity: 4.9m/s/s (Half of Earth)
Density: 2.83g/cm3 (54% less than Earth)
```
With the atmospheric density 6x higher than Earth (around 7.2kg/m3) this gives an 850kg limit of flight if the 70kg [Argentavis](https://en.wikipedia.org/wiki/Argentavis) is used as a maximum, or a 2400kg if the [Quetzalcoatlus](https://en.wikipedia.org/wiki/Quetzalcoatlus) is used as a limit. I originally had it at 3x Earth's.
Would these figures yield a stable planet?
Would the mass of the planet have a large enough magnetic field to hold such an atmosphere? Could I increase the atmospheric density to 12x Earths or higher? What sort of atmospheric composition would it need? How would I achieve a planet with the right conditions and parameters if this isn't stable?
The larger surface area allows more room for life (and thus giant life), whilst having larger oceans to support a denser atmosphere. A higher level of volcanic activity would also be included.
I did intend for it to be a binary planet as well, but all these kinds of things can be changed. | If you're hoping for the answer to be "definitely" you're out of luck, but I might be able to give you "possibly."
The planet you propose is going to have some issues, so I'll outline those immediately.
* First of all, out current model for planetary formation indicates that the closer a planet lies to its parent star, the denser that planet will become. Based on local extrapolation, this would put your planet outside the orbit of Mars, which is outside the habitable zone (for *our* sun). That's not a good sign for the development of complex life.
* Your planet also requires *more* atmosphere and *less* gravity. This is somewhat counterintuitive at first glance. Both Mars and the Earth demonstrate that a small planetary body will likely have a small atmosphere, while many other bodies of smaller size have *no* atmosphere.
* Lastly, you'll need a magnetic field around the planet to protect from ionizing radiation, and to reduce atmospheric loss from solar winds. At the proposed density, your planet will be slightly denser than Pluto. This is too light to expect there to be a metallic core with which to generate this magnetic field. That's a problem.
So is there a way to overcome these issues? Possibly.
* Addressing the habitability issue, either your planet's orbit could have moved closer inward toward the sun, placing it in the habitable zone, the star is big enough that it warms the planet even at its increased radius, or the planet's atmosphere is dense enough that a paltry amount of sunlight could keep things warm. Probably some combination of the first and third solutions would make this planet more habitable and be fairly reasonable.
* As for the atmosphere/gravity issue, there are examples of small gravity wells retaining massive atmospheres. Venus is a good example, though it is somewhat strange in its own right, and the moon Titan is another. Both of these bodies demonstrate that a large atmosphere *can* exist around a small planet, so this is plausible for your planet, and perhaps even likely depending on who you ask (though be aware that in both examples the atmosphere is "super-rotating," blowing around the entire planet at hundreds of miles per hour, like a planet sized hurricane. Definitely cool. Definitely dangerous.).
* Lastly, the magnetic field. This is tough. Venus herself has a small magnetic field generated by interactions between the high atmosphere plasma and the solar winds, but this would not be enough to protect most life forms we know. On the other hand, this *would* be enough to protect against atmospheric loss from solar winds, so that's exciting. There is also the possibility of a lightweight metal core, composed of something like magnesium perhaps, that could provide a magnetic dynamo while still retaining a low density. This is pure theory, and current models of the universe suggest it is highly unlikely, but that is not the same as impossible.
So, could this planet exist? Maybe. Does it exist? Probably not. On the other hand, the chances of Earth developing just like it did were also quite low, yet here we are wasting our time on Stack Exchange when we should be working. I'd call that a win. |
47,055 | <p>On Earth, nuclear weapons can wreak enormous damage to a country and for that reason, large-scale wars between nuclear powers don’t happen. But what would happen if humanity progressed just enough to the point where countries expanded into space? Now powerful countries have fleets of spaceships (not fantastically advanced; no faster than light travel, no freak handwavium weapons; just what we might conceivably have within a century or so). Humans live scattered across the solar system, and have nations somewhat independent of Earth.</p>
<p>Would large-scale, territorial war again become common in this scenario? Would nuclear weapons fail to pose an effective MAD deterrent effect? </p>
<p>For the sake of a specific scenario to work with, consider two space powers, <strong>The Selenation</strong>, and <strong>Arianaland</strong>. They are both fierce rivals, and maintain hundreds of space stations scattered across the solar system. They have no strictly-defined borders, but each is concentrated in one broad area of the solar system, and have a region of space that they vaguely regard as their “territory”. They have ground colonies on large moons and asteroids, but there is a roughly comparable distribution between the “rock-bound” population and the space population. The “rockies” aren’t trapped on the surface per se; they regard moving into space as about as big a deal as moving house from the city to the suburbs. Neither country is tied to Earth, which is ruled by a third country <strong>Lovatoland</strong> and is regarded as something of a backwater. There are countless smaller powers across the solar system, most of which have a small territory carved out in one corner or another.</p>
<p>The technology level is not unrecognizable from what we have today. Their ships are about at the same level of what could be built in the movie <em>Interstellar</em>, only each country has more resources to build a greater quantity of them. Travel is still slow, and moving between stations within each country takes months—it’s common, especially among members of the military, but it’s considered a “big voyage” (like interstate travel in the US in the 19th century). There is substantial communication infrastructure, and the internet exists, but it’s somewhat balkanized due to the fact that it takes up to an hour for signals to make the jump between “clusters”.</p>
<p>Would Arianaland and the Selenation be quick to go to war with one another? Would we see something similar to the perpetual battles between Britain and France in the 18th and 19th centuries, only played out in space instead of at sea? Would nuclear deterrence only be a passing phenomenon, from back when humanity was jammed together on the same planet? Since this might be seen as too broad, let’s say that the question is simply <strong>would large-scale territorial war be conceivable in this scenario?</strong></p>
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"text": "<h2>Yes</h2>\n\n<p>Nuclear weapons would be highly effective in space.</p>\n\n<p>But their effects are somewhat di... | 2016/07/12 | [
"https://worldbuilding.stackexchange.com/questions/47055",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/22443/"
] | On Earth, nuclear weapons can wreak enormous damage to a country and for that reason, large-scale wars between nuclear powers don’t happen. But what would happen if humanity progressed just enough to the point where countries expanded into space? Now powerful countries have fleets of spaceships (not fantastically advanced; no faster than light travel, no freak handwavium weapons; just what we might conceivably have within a century or so). Humans live scattered across the solar system, and have nations somewhat independent of Earth.
Would large-scale, territorial war again become common in this scenario? Would nuclear weapons fail to pose an effective MAD deterrent effect?
For the sake of a specific scenario to work with, consider two space powers, **The Selenation**, and **Arianaland**. They are both fierce rivals, and maintain hundreds of space stations scattered across the solar system. They have no strictly-defined borders, but each is concentrated in one broad area of the solar system, and have a region of space that they vaguely regard as their “territory”. They have ground colonies on large moons and asteroids, but there is a roughly comparable distribution between the “rock-bound” population and the space population. The “rockies” aren’t trapped on the surface per se; they regard moving into space as about as big a deal as moving house from the city to the suburbs. Neither country is tied to Earth, which is ruled by a third country **Lovatoland** and is regarded as something of a backwater. There are countless smaller powers across the solar system, most of which have a small territory carved out in one corner or another.
The technology level is not unrecognizable from what we have today. Their ships are about at the same level of what could be built in the movie *Interstellar*, only each country has more resources to build a greater quantity of them. Travel is still slow, and moving between stations within each country takes months—it’s common, especially among members of the military, but it’s considered a “big voyage” (like interstate travel in the US in the 19th century). There is substantial communication infrastructure, and the internet exists, but it’s somewhat balkanized due to the fact that it takes up to an hour for signals to make the jump between “clusters”.
Would Arianaland and the Selenation be quick to go to war with one another? Would we see something similar to the perpetual battles between Britain and France in the 18th and 19th centuries, only played out in space instead of at sea? Would nuclear deterrence only be a passing phenomenon, from back when humanity was jammed together on the same planet? Since this might be seen as too broad, let’s say that the question is simply **would large-scale territorial war be conceivable in this scenario?** | Yes
---
Nuclear weapons would be highly effective in space.
But their effects are somewhat different than they are on the ground. I recommend reading [this entire section of the Atomic Rockets website: Nukes in Space](http://www.projectrho.com/public_html/rocket/spacegunconvent.php#id--Nukes_In_Space)
On the ground, nuclear weapons damage things through 3 mechanisms:
### Radiation
Because the atmosphere is opaque to high frequency light (hard UV, XRay, & Gamma Ray), the primary worrisome radiation is neutrons when detonated in the atmosphere (also see thermal flash below).
In space, with no atmosphere, the high frequency light (primarily XRay and Gamma Ray) flies off without interference and this becomes one of the primary danger mechanisms of the nuclear detonation. In an atmosphere, almost all of the high frequency photon energy gets converted into the thermal flash and atmospheric blast mentioned below.
>
> For a conventional nuclear weapon (i.e., NOT a neutron bomb), the
> x-ray and neutron flux is approximately:
>
>
> $F\_{XRay} = 2.6 \cdot 10^{27} \times \frac{Y}{R^2}$
>
>
> $F\_{neutron} = 1.8 \cdot 10^{23} \times \frac{Y}{R^2}$
>
>
> where:
>
>
>
> ```
> Fx = X-ray fluence (x-rays/m2)
> Fn = Neutron fluence (neutrons/m2)
> Y = weapon yield (kilotons TNT)
> R = range from ground zero (meters)
>
> ```
>
>
This shows that for a standard (not neutron enhanced) bomb, XRay radiation is about 10,000x more damaging than neutrons at any given distance from the bomb. Which radiation flux is more dangerous to the crew depends upon factors like what sort of shielding is available and where the crew is located in the ship.
Neutron shielding is best (defined as the least amount of shield mass required to protect against it) composed of low mass atoms (e.g. Hydrogen in water).
What type of shielding to use for XRay and gamma ray radiation depends upon its frequency. At the lower energies, high Z metals (like lead and tungsten) work best, while at higher energies all mass tends to shield about the same.
Since water is terribly useful for spacecraft and ubiquitous across the Universe (from it you can make radiation shielding, water, oxygen, propellant, food, environmental coolant, and for some spacecraft fuel), I'd expect most ships to just use more water shielding in place of their high-Z metal, but otherwise dead weight, gamma ray shielding.
### Thermal Flash
Because the atmosphere is opaque to high frequency light (hard UV, XRay, & Gamma Ray), it converts those frequencies to lower frequency light (optical and thermal). This "thermal flash" is what caused memorable images (like the one below) and instantly vaporized some people in Hiroshima:
Nuclear Thermal Flash:
[](https://i.stack.imgur.com/j6a4r.jpg)
Since there is no atmosphere in space, the "thermal" flash is minimal and not really a concern.
### Blast
In an atmosphere part of the energy of the detonation is absorbed by the atmosphere and turned into an atmospheric pressure wave (the "blast" or over-pressure wave). Once again this phenomenon does not occur in space.
Therefore this issue can generally be ignored.
Nuclear Blast Effects:
[](https://i.stack.imgur.com/obdVM.gif)
### What it looks like
Assuming a near miss that doesn't actually vaporize the spacecraft...
Read this section of the [Atomic Rockets: Nuke vs. Spacecraft section](http://www.projectrho.com/public_html/rocket/spacegunconvent.php#id--Nukes_In_Space--Nuke_vs._Spacecraft) for the entire narrative. I'm going to quote a couple of key passages.
>
> First off, the weapon itself. A nuclear explosion in space, will look
> pretty much like a Very Very Bright flashbulb going off. The effects
> are instantaneous or nearly so. There is no fireball. The gaseous
> remains of the weapon may be incandescent, but they are also expanding
> at about a thousand kilometers per second, so one frame after
> detonation they will have dissipated to the point of invisibility.
> Just a flash.
>
>
>
So a strobe flash. If you were looking at it, you'll be permanently blind if you're too close. If you had a camera/sensor looking at it, it would likely burn out too if it was too close.
>
> Next is spallation - shocks will bounce back and forth through the
> skin of the target, probably tearing chunks off both sides. Some of
> these may come off at mere hundreds of meters per second. And they
> will be hot, red- or maybe even white-hot depending on the material.
>
>
> To envision the appearance of this part, a thought experiment. Or,
> heck, go ahead and actually perform it. Start with a big piece of
> sheet metal, covered in a fine layer of flour and glitter. Shine a
> spotlight on it, in an otherwise-dark room. Then whack the thing with
> a sledgehammer, hard enough for the recoil to knock the flour and
> glitter into the air.
>
>
> The haze of brightly-lit flour is your vaporized hull material, and
> the bits of glitter are the spallation. Scale up the velocities as
> needed, and ignore the bit where air resistance and gravity brings
> everything to a halt.
>
>
>
Followed by a halo of faint hazy "dust" flying away from the hull along with possibly some larger debris ripped off the ship. Some sections of the ship may be glowing red hot (or hotter) depending upon the proximity of the warhead.
It's possible that (depending upon many details) the ship may survive the detonation while the radiation kills the crew quickly or over the course of weeks. If the crew receives a deadly dose of radiation they'll likely know it even if they will likely live for a week or so in increasing agony due to the radiation damage.
Would they go to war?
---------------------
That's entirely up to you and your fictional Universe.
In space warfare, any target with a predictable trajectory (e.g. not accelerating) is a sitting duck that can be held hostage and/or killed at any time the belligerents decide to strike. The weapons would not need to be nuclear. Given sufficient time, a small asteroid would do the job easily and the belligerents might be able to maintain plausible deniability. |
47,463 | <p>I am posting this in behalf of a friend of mine from a distant world. Here is his message properly translated to English:</p>
<blockquote>
<p>Hi, Sol3αlings<sup>1</sup>. My name is $ѬӚᕕƨ⧬௵44ħ$. We are peacefully and we need your help. I am a scientist/engineer from the planet $⋒◥27⟑▓⍫⋒இǪ$. We calculated that our home star, already an instable red giant, will explode as a supernova in some years.</p>
<p>Our home planet is small, but we have very highly advanced technology at our hands. Our planet is orbiting our home star at an orbit that in its median is a mildly temperate orbit, not too close to be scorching nor too distant to freeze out the planet. Our star is very unstable, as all red giants are, and it may enlarge and shrink chaotically, which would occasionally toast or freeze our planet, but our technology is able to easily cope with that. Exactly, our planet is in a $38.6\text{ }⛮֍㐃$-wide orbit<sup>2</sup>.</p>
<p>Our problem is that we want that our home planet be able to survive the supernova explosion, but we can't figure out how, so we're sending this signal seeking for your help. We don't want to take refuge elsewhere or just flee, we just want to find a way that allows our planet's surface and atmosphere to survive as much as possible. Having a lump of devastated planetary core and vaporized mantle behind and declaring it as "survived" is not of any use to us.</p>
<p>Further, I am aware of your communication "<a href="https://worldbuilding.stackexchange.com/q/18269/3002">If the sun were to go supernova, how long would Earth have before it was consumed?</a>" that makes clear that if we don't intervene, nothing of our planet will be left behind. Also, we know about "<a href="https://worldbuilding.stackexchange.com/q/19000/3002">Can a planet survive a supernova?</a>", but it is not very useful to us, because that was directly to planets which could naturally survive the explosion while we will use our most advanced technologies instead. Also, we know from "<a href="https://worldbuilding.stackexchange.com/q/18269/3002">If the sun were to go supernova, how long would Earth have before it was consumed?</a>" that if we don't intervene, nothing of our planet will be left behind.</p>
<p>We are also aware of "<a href="https://worldbuilding.stackexchange.com/q/16780/3002">How can we extinguish a supernova?</a>", but we don't want to either prevent or stop the supernova, but for some... huh... well... RELIGION (yes that is it) reasons that huh... well... our deity asked to us (haha), we now understand that the star needs to reach its natural destiny, but our planet should remain as our lively peace of rock, even if it ends being a very cold one.</p>
<p>So, <strong>how could we make our planet survive afterall?</strong></p>
<p>You may think that it is strange that we ask you for that instead of finding the answer ourselves, since we are a very advanced technological civilization. But there is a very simple answer for that. It is easily explainable due to $⍬ईШ3877]֍$</p>
<pre><code>error - signal lost
error - data truncated
error - data consistency check failed
error - syntatic token limit out of bounds
fatal - unexpected failure 15894
Please go to http://digital-alien-transceiver.com/bugdatabase/
and file a bug report after checking for duplicates.
Don't forget to inform your transceiver configuration parameters.
Thank you for your collaboration.
info - signal recovered, data reception will be resumed
</code></pre>
<p>$Ш568ԖѼ⋒45993⋒ᐉ$ be thick enough, or maybe not completelly, otherwise it won't work. Very simple, isn't it?</p>
<p>I greatly appreciate your help. We are very sure of your peacefully collaboration.</p>
</blockquote>
<p>Also, I got this other transmission from my space friend talking to one of his other friends. Looks like some sort of random gossip:</p>
<blockquote>
<p>Are you an idiot? I order you to stop right now if you don't want to be executed for insubordination and stupidity. We need to keep our datacenter nearby that <em>freaking</em><sup>3</sup> star when it explodes <a href="https://security.stackexchange.com/a/25392/17080">to collect as much energy possible in order to decrypt the data</a>, not to take it far away.</p>
<p>The only thing that we are still lacking is to find a way to not vaporize our orbiting datacenter-planet before we proccess all the data, and I already told you stop insisting in that moronic idea of "just running away". We're not robotizing an entire planet to just send it to somewhere else, running away like a bunch of $ѦܮḺஹआ$<sup>4</sup>! That wouldn't make any sense! That won't decrypt the message! So, please, please, keep the focus in your task which as I already told you like $2,985,984$ times is just to preserve the datacenter intact during the explosion until we decrypt that <em>freaking</em><sup>3</sup> message.</p>
<p>Now go back to your actual work, because it is only your department that is behind the schedule, otherwise you will know what is feeling real pain. Even the guys from the stellar Dyson-sphere could figure out how to collect and store the explosion energy, but you on the other hand, seems to be a complete incompetent!</p>
<p><em>End of secret transmission. Disclosing or leaking the content of this transmission is a crime punishable with a cruel death.</em></p>
</blockquote>
<p>So, that is it: <strong>How could we make a planet survive a supernova explosion without it being vaporized or even significantly eroded?</strong> There is a very advanced alien civilization working and spending resources on that.</p>
<p>1: A Sol3αling is an inhabitant of some planet called "<em>Sol-3α</em>", i.e. the α-body in the third orbit around some star called "<em>Sol</em>". Could you guess which planet is that?</p>
<p>2: Sorry, I lost my table for converting that distance to Earth-like measurement units, so I don't know exactly how much is $38.6\text{ }⛮֍㐃$. Maybe you could provide the numbers that seems to work best while I search for the table and do the conversion so we don't lose any time?</p>
<p>3: Unsure of the translation of this term. Maybe there is another suitable word starting with the letter "f"?</p>
<p>4: This is some sort of animal-like creature that fears everything and instinctively run away from anything that remotely could pose any danger. A somewhat near translation to English in the sense it was used in the context would be to "<em>running away like a bunch of coward chickens</em>".</p>
<p>BTW, I found out that $2,985,984 = 12^6$. Maybe they count using base 12?</p>
<hr>
<p>Notes for answerers and dupe-closers:</p>
<ul>
<li><p>The aliens may engineer/build anything that they want that do not violate the laws of physics.</p></li>
<li><p>In fact they do not need to preserve living beings in the planet. It is just a robotized planet. I.e, a piece of rock that was converted to a giant planet-sized datacenter. Whatever is its atmosphere or surface composition, it is very different than something that would be created by nature. However, whatever is the data-processing hardware that they use in the planet, it must survive the explosion.</p></li>
<li><p>Running away, i.e. just moving the planet to somewhere very far from the supernova, do not solves the problem. The aliens need to keep the planet around the supernova. In fact, they are interested in this planet exactly because the star will explode as a supernova.</p></li>
</ul>
<hr>
<p><strong>Note for everybody</strong>: I had a lot of answers (21 non-deleted so far), so it was a hard time to nail down the very best.</p>
<p>No answer was perfect. All of them either misses something, contains flaws, are incomplete, overly simplify something, break or abuse the rules, presume some sort of doubtful at best speculative physics, contains some sort of gap or something left vague and unexplained, etc. None of them would give a definitive solid answer if this question had the tag <a href="/questions/tagged/hard-science" class="post-tag" title="show questions tagged 'hard-science'" rel="tag">hard-science</a>. Intuition says that it is impossible in <a href="/questions/tagged/hard-science" class="post-tag" title="show questions tagged 'hard-science'" rel="tag">hard-science</a>, but being able to prove that there is simply no way ever to manipulate space-time, dark-matter, or whatever else for that (or prove instead that this is indeed possible somehow) is probably way beyond our present-day knowledge level in physics. However, since this question do not have that tag, this is ok.</p>
<p>Anyway, the answers which I consider somewhat acceptable are from <a href="https://worldbuilding.stackexchange.com/a/47466/3002">Thucydides</a>, <a href="https://worldbuilding.stackexchange.com/a/47537/3002">John Dallman</a>, <a href="https://worldbuilding.stackexchange.com/a/47464/3002">Jim2B</a>, <a href="https://worldbuilding.stackexchange.com/a/47544/3002">Bob Gray</a>, <a href="https://worldbuilding.stackexchange.com/a/47683/3002">Physicist137</a>, <a href="https://worldbuilding.stackexchange.com/a/47566/3002">a4android's longer answer</a> and <a href="https://worldbuilding.stackexchange.com/a/47630/3002">my own non-wiki answer</a>. All of the non-deleted answers posted so far provide some sort of valuable information and insight, even those that are flawed, incomplete or missing the point in some way. Further, almost all of the comments in the question and in most of the answers were very helpful also. </p>
<p>Finally, after a lot of thinking and reasoning with myself, I considered Bob Gray's answer the best (by a tiny margin over the others), so I accepted his answer. Probably, many people will disagree and I am also very unsure myself because I had too many good and very different answers without any of them being perfect or clearly the best.</p>
<p>Finally, I will still evaluate eventual further answers.</p>
| [
{
"answer_id": 47464,
"author": "Jim2B",
"author_id": 7886,
"author_profile": "https://worldbuilding.stackexchange.com/users/7886",
"pm_score": 4,
"selected": false,
"text": "<h3>A question of scale</h3>\n\n<p>Supernova are powerful, extremely powerful. Imagine the most powerful explosi... | 2016/07/15 | [
"https://worldbuilding.stackexchange.com/questions/47463",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/3002/"
] | I am posting this in behalf of a friend of mine from a distant world. Here is his message properly translated to English:
>
> Hi, Sol3αlings1. My name is $ѬӚᕕƨ⧬௵44ħ$. We are peacefully and we need your help. I am a scientist/engineer from the planet $⋒◥27⟑▓⍫⋒இǪ$. We calculated that our home star, already an instable red giant, will explode as a supernova in some years.
>
>
> Our home planet is small, but we have very highly advanced technology at our hands. Our planet is orbiting our home star at an orbit that in its median is a mildly temperate orbit, not too close to be scorching nor too distant to freeze out the planet. Our star is very unstable, as all red giants are, and it may enlarge and shrink chaotically, which would occasionally toast or freeze our planet, but our technology is able to easily cope with that. Exactly, our planet is in a $38.6\text{ }⛮֍㐃$-wide orbit2.
>
>
> Our problem is that we want that our home planet be able to survive the supernova explosion, but we can't figure out how, so we're sending this signal seeking for your help. We don't want to take refuge elsewhere or just flee, we just want to find a way that allows our planet's surface and atmosphere to survive as much as possible. Having a lump of devastated planetary core and vaporized mantle behind and declaring it as "survived" is not of any use to us.
>
>
> Further, I am aware of your communication "[If the sun were to go supernova, how long would Earth have before it was consumed?](https://worldbuilding.stackexchange.com/q/18269/3002)" that makes clear that if we don't intervene, nothing of our planet will be left behind. Also, we know about "[Can a planet survive a supernova?](https://worldbuilding.stackexchange.com/q/19000/3002)", but it is not very useful to us, because that was directly to planets which could naturally survive the explosion while we will use our most advanced technologies instead. Also, we know from "[If the sun were to go supernova, how long would Earth have before it was consumed?](https://worldbuilding.stackexchange.com/q/18269/3002)" that if we don't intervene, nothing of our planet will be left behind.
>
>
> We are also aware of "[How can we extinguish a supernova?](https://worldbuilding.stackexchange.com/q/16780/3002)", but we don't want to either prevent or stop the supernova, but for some... huh... well... RELIGION (yes that is it) reasons that huh... well... our deity asked to us (haha), we now understand that the star needs to reach its natural destiny, but our planet should remain as our lively peace of rock, even if it ends being a very cold one.
>
>
> So, **how could we make our planet survive afterall?**
>
>
> You may think that it is strange that we ask you for that instead of finding the answer ourselves, since we are a very advanced technological civilization. But there is a very simple answer for that. It is easily explainable due to $⍬ईШ3877]֍$
>
>
>
> ```
> error - signal lost
> error - data truncated
> error - data consistency check failed
> error - syntatic token limit out of bounds
> fatal - unexpected failure 15894
> Please go to http://digital-alien-transceiver.com/bugdatabase/
> and file a bug report after checking for duplicates.
> Don't forget to inform your transceiver configuration parameters.
> Thank you for your collaboration.
> info - signal recovered, data reception will be resumed
>
> ```
>
> $Ш568ԖѼ⋒45993⋒ᐉ$ be thick enough, or maybe not completelly, otherwise it won't work. Very simple, isn't it?
>
>
> I greatly appreciate your help. We are very sure of your peacefully collaboration.
>
>
>
Also, I got this other transmission from my space friend talking to one of his other friends. Looks like some sort of random gossip:
>
> Are you an idiot? I order you to stop right now if you don't want to be executed for insubordination and stupidity. We need to keep our datacenter nearby that *freaking*3 star when it explodes [to collect as much energy possible in order to decrypt the data](https://security.stackexchange.com/a/25392/17080), not to take it far away.
>
>
> The only thing that we are still lacking is to find a way to not vaporize our orbiting datacenter-planet before we proccess all the data, and I already told you stop insisting in that moronic idea of "just running away". We're not robotizing an entire planet to just send it to somewhere else, running away like a bunch of $ѦܮḺஹआ$4! That wouldn't make any sense! That won't decrypt the message! So, please, please, keep the focus in your task which as I already told you like $2,985,984$ times is just to preserve the datacenter intact during the explosion until we decrypt that *freaking*3 message.
>
>
> Now go back to your actual work, because it is only your department that is behind the schedule, otherwise you will know what is feeling real pain. Even the guys from the stellar Dyson-sphere could figure out how to collect and store the explosion energy, but you on the other hand, seems to be a complete incompetent!
>
>
> *End of secret transmission. Disclosing or leaking the content of this transmission is a crime punishable with a cruel death.*
>
>
>
So, that is it: **How could we make a planet survive a supernova explosion without it being vaporized or even significantly eroded?** There is a very advanced alien civilization working and spending resources on that.
1: A Sol3αling is an inhabitant of some planet called "*Sol-3α*", i.e. the α-body in the third orbit around some star called "*Sol*". Could you guess which planet is that?
2: Sorry, I lost my table for converting that distance to Earth-like measurement units, so I don't know exactly how much is $38.6\text{ }⛮֍㐃$. Maybe you could provide the numbers that seems to work best while I search for the table and do the conversion so we don't lose any time?
3: Unsure of the translation of this term. Maybe there is another suitable word starting with the letter "f"?
4: This is some sort of animal-like creature that fears everything and instinctively run away from anything that remotely could pose any danger. A somewhat near translation to English in the sense it was used in the context would be to "*running away like a bunch of coward chickens*".
BTW, I found out that $2,985,984 = 12^6$. Maybe they count using base 12?
---
Notes for answerers and dupe-closers:
* The aliens may engineer/build anything that they want that do not violate the laws of physics.
* In fact they do not need to preserve living beings in the planet. It is just a robotized planet. I.e, a piece of rock that was converted to a giant planet-sized datacenter. Whatever is its atmosphere or surface composition, it is very different than something that would be created by nature. However, whatever is the data-processing hardware that they use in the planet, it must survive the explosion.
* Running away, i.e. just moving the planet to somewhere very far from the supernova, do not solves the problem. The aliens need to keep the planet around the supernova. In fact, they are interested in this planet exactly because the star will explode as a supernova.
---
**Note for everybody**: I had a lot of answers (21 non-deleted so far), so it was a hard time to nail down the very best.
No answer was perfect. All of them either misses something, contains flaws, are incomplete, overly simplify something, break or abuse the rules, presume some sort of doubtful at best speculative physics, contains some sort of gap or something left vague and unexplained, etc. None of them would give a definitive solid answer if this question had the tag [hard-science](/questions/tagged/hard-science "show questions tagged 'hard-science'"). Intuition says that it is impossible in [hard-science](/questions/tagged/hard-science "show questions tagged 'hard-science'"), but being able to prove that there is simply no way ever to manipulate space-time, dark-matter, or whatever else for that (or prove instead that this is indeed possible somehow) is probably way beyond our present-day knowledge level in physics. However, since this question do not have that tag, this is ok.
Anyway, the answers which I consider somewhat acceptable are from [Thucydides](https://worldbuilding.stackexchange.com/a/47466/3002), [John Dallman](https://worldbuilding.stackexchange.com/a/47537/3002), [Jim2B](https://worldbuilding.stackexchange.com/a/47464/3002), [Bob Gray](https://worldbuilding.stackexchange.com/a/47544/3002), [Physicist137](https://worldbuilding.stackexchange.com/a/47683/3002), [a4android's longer answer](https://worldbuilding.stackexchange.com/a/47566/3002) and [my own non-wiki answer](https://worldbuilding.stackexchange.com/a/47630/3002). All of the non-deleted answers posted so far provide some sort of valuable information and insight, even those that are flawed, incomplete or missing the point in some way. Further, almost all of the comments in the question and in most of the answers were very helpful also.
Finally, after a lot of thinking and reasoning with myself, I considered Bob Gray's answer the best (by a tiny margin over the others), so I accepted his answer. Probably, many people will disagree and I am also very unsure myself because I had too many good and very different answers without any of them being perfect or clearly the best.
Finally, I will still evaluate eventual further answers. | All you'd need is an Einstein-Rosen bridge situated so that it was placed perpendicular to the planet. Make the entrance, say, 2 planetary diameters wide and just let it sit there.
The energy from the supernova that would have impacted the planet will instead go into the wormhole and come out wherever. I say place the other end near another supernova and hit one supernova with the other. Interesting!
The huge width of the bridge would stop any "bleed-around" energy from leaking through and hitting your planet. Sit back and watch the show! |
51,204 | <p>Suppose we have an intelligent alien who has landed on Earth and has somehow found his way into a human high school math class (for the sake of scenic stability, the alien has the ability to cloak itself as a human form). </p>
<p>The typical trope is the alien finds the human math elementary, and quietly chuckles to himself about how primitive humans are. Sometimes the alien, when interacting with his human friends, mutters advanced mathematical equations to himself, which goes right over the humans’ heads. In our high school math class, the alien gets called up to the board and sometimes inadvertently fills up the entire blackboard to the shock of the human teacher.</p>
<p>For example, in the Animorphs series, there’s a line where Ax (an alien posing as a human teen) says in a train of thought:</p>
<blockquote>
<p>I think I remember the equations ... in an equation where <em>t</em> is time, <em>z</em> is Zero-space, <em>w</em> inversely cubed represents the nexus of…</p>
</blockquote>
<p>But how realistic is it that an alien would have the same concept of algebra as we do? Would our equations even make sense to them? Would theirs make sense to us? Would they even have “equations”? Would they have the concept of things like a variable or a square root? Would things like “subtract <em>x</em> from both sides” make sense to them?</p>
<p>Note that I’m not asking about <em>symbols</em>—we assume that, just as our friendly space alien has learned the English alphabet, he also knows about human symbols such as <code>+ – = × / √</code>, etc. He also speaks the English language well (or has a translator chip in his brain). I’m also not asking if the alien would have problems with arbitrary conventions in our mathematical system (i.e. base 10, 360° in a circle, etc), rather the underlying system of logic. I’m asking that, if our mathematical <em>glyphs</em> were intelligible to our alien, would he feel right at home performing algebraic operations on Earth? If our alien came from a planet with a completely foreign algebraic system, how quickly could he pick up “human” algebra? How much of his native algebra knowledge could be transferred to his new context?</p>
| [
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"text": "<p>There was a SETI Weekly Seminar a while back on just how alien maths might be.</p>\n\n<p>See <a href=\"https:... | 2016/08/10 | [
"https://worldbuilding.stackexchange.com/questions/51204",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/22443/"
] | Suppose we have an intelligent alien who has landed on Earth and has somehow found his way into a human high school math class (for the sake of scenic stability, the alien has the ability to cloak itself as a human form).
The typical trope is the alien finds the human math elementary, and quietly chuckles to himself about how primitive humans are. Sometimes the alien, when interacting with his human friends, mutters advanced mathematical equations to himself, which goes right over the humans’ heads. In our high school math class, the alien gets called up to the board and sometimes inadvertently fills up the entire blackboard to the shock of the human teacher.
For example, in the Animorphs series, there’s a line where Ax (an alien posing as a human teen) says in a train of thought:
>
> I think I remember the equations ... in an equation where *t* is time, *z* is Zero-space, *w* inversely cubed represents the nexus of…
>
>
>
But how realistic is it that an alien would have the same concept of algebra as we do? Would our equations even make sense to them? Would theirs make sense to us? Would they even have “equations”? Would they have the concept of things like a variable or a square root? Would things like “subtract *x* from both sides” make sense to them?
Note that I’m not asking about *symbols*—we assume that, just as our friendly space alien has learned the English alphabet, he also knows about human symbols such as `+ – = × / √`, etc. He also speaks the English language well (or has a translator chip in his brain). I’m also not asking if the alien would have problems with arbitrary conventions in our mathematical system (i.e. base 10, 360° in a circle, etc), rather the underlying system of logic. I’m asking that, if our mathematical *glyphs* were intelligible to our alien, would he feel right at home performing algebraic operations on Earth? If our alien came from a planet with a completely foreign algebraic system, how quickly could he pick up “human” algebra? How much of his native algebra knowledge could be transferred to his new context? | While the symbols we use to describe mathematics are a human creation, the underlying truths of math are not. The relationship between π and the radius/circunference of a circle, the square-cube law and the relationship among speed, time and distance were part of the universe before humans existed, and will continue to be after humans are gone.
Any aliens who have enough technological advancement to come to Earth and disguise themselves **as an act of engineering** should have an understanding of Math in the very least equal to ours, even if the way they abstract math in their heads and recordings is different from ours.
For such aliens, learning our algebra could be like what learning chinese or japanese is to a regular western person. Not only the symbols are different, the way you have to organize your thoughts so that you can give meaning to an idea and express it is different too. But the things you can talk about in those languages are the same things we can talk about in English, even if some things area easier to express in one language or another.
As an exercise on reorganizing your thoughs to abstract and express mathematical ideas differently, and with different symbols (or different meanings for the same symbols we use), you can also learn a low-level programming language (languages that force you to learn how a computer works in very minute detail) and play with it. You'll never see an equation the same way again. In the very least you will start using less and less base 10 and more and more bases 2 and 16 (and sometimes 8) in your head. I have been doing it for years, to the point that reading time from a watch like the one below is easier for me than reading time on an analog watch.
[](https://i.stack.imgur.com/BJpgi.jpg)
(It says 12:15 by the way)
Another example of how some programmers are practically aliens when it comes to Math. The "equation" below (actually a simple program written in [Brainfuck](https://esolangs.org/wiki/Brainfuck)) is a simple addition. It works if both values are zeroes or positive integers and the sum of their values is no greater than 255:
```
[->+<]
```
The best part of it is that the variables to be summed are **not** represented in that equation. And the "+" symbol there does not mean "add", it means "increase by one". I could not explain that in an answer here, and if I tried, the more I talked about it, the more you would think I am an actual alien.
Once you've put yourself through the effort of learning a language that uses different symbols and requires you to reorder your thougths, you can use your experience to describe how learning our algebra should feel to an alien. How easy or hard that would be for said alien is up to your tayloring as the writer of your story.
---
There is alternative here, though. If the aliens come to Earth as **an act of magic or psionics**, done intuitively or instinctively, then they may not need mathematical concepts. But this does not mean they could not have them. |
52,158 | <p>Here's the scenario: animals on a world with an atmosphere with a significant amount of a certain gas is able to store "air" into a transparent growth (like a crest) and, with an electrical chord in the "crest", makes a glowing light with different colors depending on what's produced in the crest. The questions in mind are:</p>
<p>*Could the process work?</p>
<p>*What would be the best gas to use?</p>
<p>*How much of this gas would be needed in the atmosphere for the process to happen?</p>
| [
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"text": "<p>I highly doubt it. But with minor changes, may be. </p>\n\n<p>In practice, only noble gases can used to create l... | 2016/08/18 | [
"https://worldbuilding.stackexchange.com/questions/52158",
"https://worldbuilding.stackexchange.com",
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] | Here's the scenario: animals on a world with an atmosphere with a significant amount of a certain gas is able to store "air" into a transparent growth (like a crest) and, with an electrical chord in the "crest", makes a glowing light with different colors depending on what's produced in the crest. The questions in mind are:
\*Could the process work?
\*What would be the best gas to use?
\*How much of this gas would be needed in the atmosphere for the process to happen? | If your hypothetical organism is engaged with chemiluminescence involving gases would do something like the following.
>
> Another gas phase reaction is the basis of nitric oxide detection in commercial analytic instruments applied to environmental air-quality testing. Ozone is combined with nitric oxide to form nitrogen dioxide in an activated state.
>
>
>
```
NO+O3 → NO2[◊]+ O2
```
>
> The activated NO2[◊] luminesces broadband visible to infrared light as it reverts to a lower energy state.
>
>
>
Now nitric oxide can be produced in living creatures, but ozone might difficult.
>
> In mammals including humans, ·NO is an important cellular signaling molecule involved in many physiological and pathological processes
>
>
> Ozone is formed from dioxygen by the action of ultraviolet light and also atmospheric electrical discharges, and is present in low concentrations throughout the Earth's atmosphere (stratosphere). In total, ozone makes up only 0.6 ppm of the atmosphere.
>
>
> Ozone is a powerful oxidant (far more so than dioxygen) and has many industrial and consumer applications related to oxidation. This same high oxidising potential, however, causes ozone to damage mucous and respiratory tissues in animals, and also tissues in plants, above concentrations of about 100 ppb. This makes ozone a potent respiratory hazard and pollutant near ground level. However, the ozone layer (a portion of the stratosphere with a bigger concentration of ozone, from two to eight ppm) is beneficial, preventing damaging ultraviolet light from reaching the Earth's surface, to the benefit of both plants and animals.
>
>
>
While ozone does have problems for living organisms, it is produced physiologically.
>
> Ozone, along with reactive forms of oxygen such as superoxide, singlet oxygen, hydrogen peroxide, and hypochlorite ions, is naturally produced by white blood cells and other biological systems (such as the roots of marigolds) as a means of destroying foreign bodies. Ozone reacts directly with organic double bonds. Also, when ozone breaks down to dioxygen it gives rise to oxygen free radicals, which are highly reactive and capable of damaging many organic molecules. Moreover, it is believed that the powerful oxidizing properties of ozone may be a contributing factor of inflammation. The cause-and-effect relationship of how the ozone is created in the body and what it does is still under consideration and still subject to various interpretations, since other body chemical processes can trigger some of the same reactions
>
>
>
Your chemiluminescent signalling critter will need to produce nitric oxide and ozone and combine them in dermal cells to do its signalling. Ozone is a hazardous substance for live tissue and organs, so the critter will have to manage the ozone carefully. So provided you have a creature that can make sufficient nitric oxide and ozone, then it can send signals chemiluminescently. |
52,164 | <p>In our universe infinite energy is not possible, at least given the known laws of physics. </p>
<p>But in another universe what would allow for energy to be in the same amount as space? </p>
<p>But how large is space, as we know our universe doesn't have magic walls that say ''hey the space ends there'' therefore,probably it's possible that our universe has no limits in space,that's why it never stopped expanding faster than the speed of light and it accelerates as it grows. </p>
<p>This other fictional universe has the same amount of space as ours which is infinite plus an <strong>equally</strong> infinite energy. </p>
<p>How to make that work?</p>
| [
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"text": "<p>The answer to this is <em>very</em> dependent on details. There's many ways to approach this and they lea... | 2016/08/19 | [
"https://worldbuilding.stackexchange.com/questions/52164",
"https://worldbuilding.stackexchange.com",
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] | In our universe infinite energy is not possible, at least given the known laws of physics.
But in another universe what would allow for energy to be in the same amount as space?
But how large is space, as we know our universe doesn't have magic walls that say ''hey the space ends there'' therefore,probably it's possible that our universe has no limits in space,that's why it never stopped expanding faster than the speed of light and it accelerates as it grows.
This other fictional universe has the same amount of space as ours which is infinite plus an **equally** infinite energy.
How to make that work? | The answer to this is *very* dependent on details. There's many ways to approach this and they lead to very different results.
The first question is whether you ever have infinite energy density. This causes all sorts of equations to break down for the same reasons as a naked singularity breaks down all the laws of physics. Since energy and mass are entwined in relativity, this would also imply infinite mass, which causes even more problems. More than likely the answer to this is "the physics of this universe would be completely and utterly unrelated to anything in this universe." This sort of thing only shows up in the big bang models, and we readily recognize that they're just models to describe what might have happened. If singularities like that were discovered in our universe, it'd be a big deal.
Another option would be to have infinite energy but finite energy density. If you have infinite space, you can pull that off. This can be done in a few ways. One approach is to have the entire universe be "warm," so there is some base energy available at all points permitting change to occur over time. This energy, however, may not be available for doing thermodynamic work. If that energy is in the form of waste heat, then you can't use it for work.
Another approach would be to have the infinite energy in a form which is captureable for work. To do this, we would need to toss away the [laws of thermodynamics](https://en.wikipedia.org/wiki/Laws_of_thermodynamics). The laws of thermodynamics that we are so familiar with only apply to systems that are at thermal equilibrium, and you would be able to ensure the universe never reaches equilibrium. The field of non-equilibrium thermodynamics is a very open field at this point. We're constantly being surprised by results found in that field, so I won't speculate as to what might happen.
You can have the energy density decrease as you get further away from some magical "origin" point. In this case, you could build a universe where you could simply exist forever, because you'd always be able to find an energy gradient, which is the key requirement for doing mechanical work. This would be a departure from our physics because in this world, "we cannot define the position of God's Throne in space." There is no point which is any more central than any other, or any more "fixed" in space.
A final intriguing option would be to change the boundary conditions. We typically assume that energy approaches 0 as we get far away. However, you could have an oscillating boundary condition that has energy going on forever in a repetitive pattern.
This one is rather interesting because we've got examples of it in the world of simulated automata. One interesting class is the 1 dimensional elementary cellular automata. These are simulated automata consisting of a line of cells which are either alive or dead, and change states each timestep based on their state and the state of their two neighbors. They are typically known by their "rule" number, which is a number describing the entire evolution function of the automata. One of these, [Rule 110](https://en.wikipedia.org/wiki/Rule_110) is particularly beautiful and interesting:
[](https://i.stack.imgur.com/Mz8Lt.png)
In these pictures, the top row is the "starting state," and each subsequent row is a new generation created by applying the rules of Rule 110. All you have to do for any cell is look at the cell's left neighbor, itself, and its right neighbor, and replace the state of the center cell using the following rule.
```
current pattern 111 110 101 100 011 010 001 000
new state for center cell 0 1 1 0 1 1 1 0
```
What's interesting about this is the pattern of small triangles of size 3 that build the "backdrop" for rule 110. This actually appears as long as you have at least 1 "live" cell in your initial state. Accordingly, it is common to explore the movement of the more beautiful triangles on an infinite repeating array of these size 3 triangles.
This would correspond to an oscillating boundary condition. Anything "interesting" in this world can assume that there will be a continuous influx of energy from this osculation which can be harnessed.
As it turns out, Rule 110 is considered to be very special because it is Turing complete! That's right. Anything you can do with your computer can actually be simulated using these little triangles. They make streams of them collide in very particular ways to execute operations using something called a cyclic tagging system.
[](https://i.stack.imgur.com/EPfWx.jpg)
Incidentally, this is very similar to a rule we see in nature, Rule 30. Rule 30 is:
```
current pattern 111 110 101 100 011 010 001 000
new state for center cell 0 0 0 1 1 1 1 0
```
We see this in cone snails, used as camouflage.
[](https://i.stack.imgur.com/OpCmu.jpg)
So, in short, infinite energy changes everything, but there are ways it can be kept tractable, such as having oscillating boundary conditions. Some of these cases even have really interesting beahviors! |
52,675 | <p>Suppose a starship is being powered by a lasers beamed first from the departure star, and then from the destination which is a moving base. The ship is moving in the regime of 10–30% of light speed.</p>
<p>Picture a letter “T”. The ship is accelerated up the vertical line from the source at the bottom of the T, into the path of the horizontal cross-line. A mobile base (the destination) moving on this horizontal line at 10% lightspeed will supply a laser too. </p>
<p>That is, the home system will push a lightsail craft into the path of a base moving at relativistic speeds. That base would pass home with a closest approach of several light years.</p>
<p><img src="https://i.stack.imgur.com/hCMx9.png" alt="sketch"></p>
<p>Let me try another mental picture: you are a mile back on a path that intersects with a main road at a right angle. A mobile home is travelling down the main road at 70 miles per hour. The beam from home pushes you into the main road, and the beam from the mobile home needs to get you going in <em>that</em> direction instead for eventual rendezvous.</p>
<p>The mobile base needs to accelerate the incoming craft to its own oncoming speed and kill the transverse velocity.</p>
<p>What would the maneuver look like? I’m supposing that <strong>the angle at which it presents the sail</strong> will be significantly affected by relativistic effects and <a href="https://en.wikipedia.org/wiki/Aberration_of_light">aberration</a> of moving source.</p>
<p>Also, the mobile base (from a more advanced civilization) can do any advanced tricks you can imagine, such as <strike>synthetic aperture beamforming to make the wavefronts come from a different direction than the actual source, and</strike> impart <a href="https://en.wikipedia.org/wiki/Orbital_angular_momentum_of_light">orbital angular momentum to the photons</a>.</p>
<p>The <em>home</em> beam has just enough power and focus for the maneuver it is designed for. The <em>base</em> beam can be more powerful and amazingly well-focused. But the base won’t aim the beam directly at the home; they will require the ship to be some distance out (like a light year) before offering.</p>
<hr>
<p>Peregrine Rook’s sketch is nicer ☺.</p>
<p>I think the sail would be tipped the other way when catching the beam from the base, though, to slow the “up” component.</p>
<p><img src="https://i.stack.imgur.com/bMZpY.png" alt="sketch"></p>
| [
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"text": "<p>There are some ways to break this problem into simpler ones.</p>\n<h1>One laser at a time</h1>\n<p>Si... | 2016/08/24 | [
"https://worldbuilding.stackexchange.com/questions/52675",
"https://worldbuilding.stackexchange.com",
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] | Suppose a starship is being powered by a lasers beamed first from the departure star, and then from the destination which is a moving base. The ship is moving in the regime of 10–30% of light speed.
Picture a letter “T”. The ship is accelerated up the vertical line from the source at the bottom of the T, into the path of the horizontal cross-line. A mobile base (the destination) moving on this horizontal line at 10% lightspeed will supply a laser too.
That is, the home system will push a lightsail craft into the path of a base moving at relativistic speeds. That base would pass home with a closest approach of several light years.
Let me try another mental picture: you are a mile back on a path that intersects with a main road at a right angle. A mobile home is travelling down the main road at 70 miles per hour. The beam from home pushes you into the main road, and the beam from the mobile home needs to get you going in *that* direction instead for eventual rendezvous.
The mobile base needs to accelerate the incoming craft to its own oncoming speed and kill the transverse velocity.
What would the maneuver look like? I’m supposing that **the angle at which it presents the sail** will be significantly affected by relativistic effects and [aberration](https://en.wikipedia.org/wiki/Aberration_of_light) of moving source.
Also, the mobile base (from a more advanced civilization) can do any advanced tricks you can imagine, such as synthetic aperture beamforming to make the wavefronts come from a different direction than the actual source, and impart [orbital angular momentum to the photons](https://en.wikipedia.org/wiki/Orbital_angular_momentum_of_light).
The *home* beam has just enough power and focus for the maneuver it is designed for. The *base* beam can be more powerful and amazingly well-focused. But the base won’t aim the beam directly at the home; they will require the ship to be some distance out (like a light year) before offering.
---
Peregrine Rook’s sketch is nicer ☺.
I think the sail would be tipped the other way when catching the beam from the base, though, to slow the “up” component.
 | First, let’s look at the different types of trajectories a solar sail can take. They differ mainly based on something called the *lightness number*, $\beta$, which depends on the composition and structure of the sail. $\beta$ can be used to determine the type of trajectory the solar sail will follow:
$$\begin{array}{|c|c|}
\hline \text{Value of }\beta & \text{Type of trajectory} \\
\hline \beta=0 & \text{circular Keplerian} \\
\hline 0<\beta<\frac{1}{2} & \text{elliptical} \\
\hline \beta=\frac{1}{2} & \text{parabolic} \\
\hline \frac{1}{2}<\beta<1 & \text{hyperbolic} \\
\hline \beta=1 & \text{rectilinear} \\
\hline 1<\beta & \text{flipped hyperbolic} \\
\hline
\end{array}$$
This is also evident in Figure 4.8 (page 123) of Colin McInnes’ [*Solar Sailing: Technology, Dynamics and Mission Applications*](https://books.google.com/books?id=lvHxBwAAQBAJ&pg=PA130&lpg=PA130&dq=solar+sail+logarithmic+spiral+escape+trajectory&source=bl&ots=inAfjimvhX&sig=Qqkxsftl5xmPG-cyJOnQSi5DIIY&hl=en&sa=X&ved=0ahUKEwiM68WEsvHOAhXGXB4KHVbWDMUQ6AEIIjAB#v=onepage&q&f=false), which is my primary reference in this answer:
[](https://i.stack.imgur.com/6Lx4p.png)
Now, you can see that a hyperbolic trajectory of some sort may be exactly what you’re looking for - and, in fact, it requires no assistance from the base it is rendezvousing with! Parabolic trajectories, too, are escape trajectories, but a hyperbolic trajectory might be more efficient. Plus, having a greater lightness number results in a greater characteristic acceleration (see [Seboldt & Dachwald (2003)](http://earth-escape.com/paper/200207_Pozzuoli_SeboldtDachwald.pdf)), because $a\_c\propto\beta$. Therefore, I’d prefer to work with a flipped hyperbolic trajectory; I’ll choose $\beta\approx2$.
There are two equations of motion for polar coordinates $(r,\theta)$:
$$\frac{\mathrm{d}^2r}{\mathrm{d}t^2}-r\left(\frac{\mathrm{d}\theta}{\mathrm{d}t}\right)^2=-\overbrace{\frac{\mu}{r^2}}^{\text{gravitational}}+\overbrace{\beta\frac{\mu}{r^2}\cos^3\alpha}^{\text{radiation}}\tag{4.37a}$$
$$r\frac{\mathrm{d}^2\theta}{\mathrm{d}t^2}+2\left(\frac{\mathrm{d}r}{\mathrm{d}t}\right)\left(\frac{\mathrm{d}\theta}{\mathrm{d}t}\right)=\beta\frac{\mu}{r^2}\cos\alpha^2\sin\alpha\tag{4.37b}$$
where $\mu$ is the [standard gravitational parameter](https://en.wikipedia.org/wiki/Standard_gravitational_parameter) and $\alpha$ is the angle between a vector normal to the sail and a vector pointing from the star to the sail. Compare McInnis’ $(\text{4.37a})$ to $(\text{346})$ [here](http://www2.ph.ed.ac.uk/~egardi/MfP3-Dynamics/Dynamics_lecture_21.pdf), with the substitution of $h=r^2\dot{\theta}$. The two are identical, with the addition of the radiation term in the solar sail reformulation. Let’s have $\alpha\approx0$. This means that the right-hand side of $(\text{4.37a})$ becomes $(\beta-1\frac{\mu}{r^2}$, and the right-hand side of $(\text{4.37b})$ becomes $0$.
We can arrive at a simple analytical solution if we assume that the solar sail takes the path of a [logarithmic spiral](https://en.wikipedia.org/wiki/Logarithmic_spiral), i.e. a path of the form
$$r(\theta)=r\_0\exp(\theta\tan\gamma)$$
where $r\_0$ is the initial radius and $\gamma$ is the *spiral angle*, the angle between the velocity vector and the transverse direction of the sail’s path. So let’s step back a little, and let’s assume that
* $\beta\approx0.75$ (I’ve chosen a value for a normal hyperbolic trajectory)
* $\alpha\neq0^{\circ}$. It *could*, but that might not be optimal.
McInnes goes through several substitutions, leading to
$$r^3\left(\frac{\mathrm{d}\theta}{\mathrm{d}t}\right)^2=\mu\left[1-\beta\cos^2\alpha(\cos\alpha-\tan\gamma\sin\alpha)\right]\cos^2\gamma\tag{4.41}$$
From this and earlier substitutions, we can derive expressions for the radial velocity $v\_r(r)$ and angular velocity $v\_{\theta}(r)$. The equation for the former is
$$v(r)=\sqrt{\frac{\mu}{r}}\left[1-\beta\cos^2\alpha(\cos\alpha-\sin\alpha\tan\gamma)\right]^{1/2}\tag{4.44}$$
There’s a fairly complicated relationship between $\gamma$ and $\alpha$, but it can be simplified for small $\gamma$:
$$\frac{\beta\cos^2\alpha\sin\alpha}{1-\beta\cos^3\alpha}=\frac{\sin\gamma\cos\gamma}{2-\sin^2\gamma}\approx\frac{1}{2}\tan\gamma\tag{4.45,4.48}$$
This integration is important when we try to find a relationship between $r$ and $t$. We integrate $(\text{4.44})$:
$$\int\_{r\_0}^r\sqrt{r}\mathrm{d}r=\int\_{t\_0}^t\left(2\beta\mu\sin\alpha\cos^2\alpha\tan\gamma\right)^{1/2}\mathrm{d}t\tag{4.46}$$
Integrating this and substituting in $(\text{4.48})$ yields
$$t-t\_0=\frac{1}{3}\left(r^{3/2}-r\_0^{3/2}\right)\left(\frac{1-\beta\cos^3\alpha}{\beta^2\mu\cos^4\alpha\sin^2\alpha}\right)^{1/2}\tag{4.49}$$
However, we can simplify this by letting $t\_0=0$ and focusing on cases where $r\_0\ll r$ for most $r$, which is the case here when $r=r\_f$. We can then find when the function of $\alpha$ in $(\text{4.49})$ is maximized; it turns out that for small $\beta$ (i.e. $\beta<0.5$), $\alpha\_{\text{max}}\approx35.26^{\circ}$. However, I chose $\beta=0.75$, and so it turns out that $\alpha$ is maximized at about $35.26^{\circ}$. Plugging this back into our approximation for $\tan\gamma$, we find that $\tan\gamma\approx1.362$, which gives us $\gamma\approx53.7^{\circ}$. This likely makes our small angle approximation for $\tan\gamma$ less accurate, but it will do for now. Plugging this in, and assuming once again that $t\_0=0$ and $r\_0\ll r$, $(\text{4.49})$ gives us
$$t=r^{3/2}\times1.23\times10^{-10}$$
and for a final radius of three light-years ($2.838\times10^{16}$ meters), we find that $t\approx5.88\times10^{14}$ seconds, or about 19 million years. That might seem like it can’t be correct, but [Centauri Dreams cites Matloff et al. that it could take a really good solar sail 30 years just to reach the Oort Cloud](http://www.centauri-dreams.org/?p=4238), 500 AU away - and one light-year is about 60,000 AU. Clearly, a simple logarithmic spiral quite like this won’t work.
In fact, this means that you absolutely need to give the solar sail a very fast initial boost to make interstellar travel on these scales even remotely feasible. This makes the equations a little harder, and it means that yyou might not see an easy analytical solution pop up.
Let’s go back to our original coupled equations $(\text{4.37a})$ and $\text{4.37b})$, where we’ve set $\beta=2$ and $\alpha=0$. This becomes a simple [central force problem](https://en.wikipedia.org/wiki/Classical_central-force_problem), which has one equation of the form
$$\frac{\mathrm{d}^2r}{\mathrm{d}t^2}-\frac{h^2}{r^3}=\frac{F(r)}{m}$$
where I’ve defined $h\equiv r^2\dot{\theta}$, which is conserved. $F(r)$ is the central force as a function of $r$; normally, in orbital mechanics, it’s simply
$$F(r)=-\frac{GMm}{r^2}$$
as is the case in $(\text{346})$; here, as I noted before, we also have to account for the force from radiation pressure. With $\beta=2$, it just so happens that the two forces add up to
$$F(r)=\frac{-GMm}{r^2}+\frac{(2)GMm}{r^2}=\frac{GMm}{r^2}$$
which is repulsive, unlike $(\text{346})$. [That pdf](http://www2.ph.ed.ac.uk/~egardi/MfP3-Dynamics/Dynamics_lecture_21.pdf) shows a good derivation of the orbital equation from the central force law, which I’m not going to go through again, as it’s pretty standard. For a generic central force of the form
$$F(r)=-\frac{k}{r^2}$$
we arrive at an orbit of the form
$$r(\theta)=\frac{l}{1+\varepsilon\cos\theta}\tag{355}$$
where $k=-GM$ (in general, $k=(\beta-1)GM$), and
$$l\equiv\frac{mh^2}{k},\quad\varepsilon\equiv\frac{l}{a}-1\tag{356}$$
I’m no expert when it comes to solar sail construction, so I read through [McInnes et al. (2001)](http://www.esa.int/esapub/bulletin/bullet108/chapter6_bul108.pdf) and came up with a conservative estimate of 2,000 kg. The authors estimated that you could send a 900 kg solar sail to solar orbit, with much of that mass being payload. My guess could be way off, so I’d appreciate it if an expert has better figures.
I assumed that the solar sail starts out on a circular orbit around a sun-like star at roughly Earth’s semi-major axis. From this, I calculated
$$v\_0=\sqrt{\frac{\mu}{r}}=2.97\times10^4\text{ m/s}$$
$$h=\frac{|L|}{m}=\frac{rmv}{m}=rv=4.46\times10^{15}\text{ m}^2\text{/s}$$
$$k=(\beta-1)GM=1.327\times10^{20}\text{ m}^3\text{/s}^2$$
$$l\equiv\frac{mh^2}{k}=3\times10^{14}$$
$$\varepsilon\equiv\frac{l}{a}-1=2000$$
From this, I get
$$r=\frac{3\times10^{14}}{1+2000\cos\theta}$$
$\varepsilon>1$ (as was expected, given that $\beta>1$), and in fact $\varepsilon\gg1$.
I used modified code from [this page](http://www.physics.buffalo.edu/phy302/topic1/#sec-15) to solve $(\text{4.37a})$ in Mathematica and plot the motion of the solar sail over the course of one year:
```
M = 1.99 10^30 (*mass of Sun*)
G = 6.67 10^-11 (*Newton's constant*)
x0 = 1.50*10^11 (*apsidal distance*)
y0 = 0; vx0 = 0;(*on x axis with velocity in y direction*)
vCirc = Sqrt[G M/x0] (*apsidal speed for circular orbit*)
vy0 = 0.8 vCirc (*smaller speed gives elliptical orbit*)
a = 1/(2/x0 - vy0^2/(G M)) (*semimajor axis from E=T+V*)
T = 2 Pi Sqrt[a^3/(G M)] (*period from Kepler's third law*)
beta = 2 (*accounts for radiation pressure*)
r[t_] := {x[t], y[t]} (*position vector*)
equation = Thread[r''[t] == (beta-1) G M r[t]/Dot[r[t], r[t]]^(3/2)]
initial = Join[Thread[r[0] == {x0, y0}], Thread[r'[0] == {vx0, vy0}]]
solution = NDSolve[Join[equation, initial], r[t], {t, 0, T}]
orbit = ParametricPlot[r[t] /. solution, {t, 0, T}];
Show[orbit]
```
This is the orbit:
[](https://i.stack.imgur.com/xTgVi.png)
As you can see, it travels in essentially a straight line, going at a little over 5 Au per year, at first. That’s not bad at all. It’s still going to take a long time to reach the base, but this is likely going to be on the order of thousands of years, not millions of years. |
53,803 | <p>We've seen questions about multiple planets in a single orbit before, using Lagrangian points, through orbiting each other as they go around, etc. I'm looking at the creation of a hypothetical system with two habitable planets orbiting their star in a stable <a href="https://en.wikipedia.org/wiki/Horseshoe_orbit" rel="noreferrer">horseshoe orbit</a>.</p>
<p>To sum up a horseshoe orbit: two bodies orbit a star in nearly the same path. One of them is slightly closer to the star than the other, so it will go around a little faster. When it "catches" the second body, it will be accelerated by its gravity. This effectively pushes the first body outward, away from the star, until its orbit is now slightly <em>longer</em> than the second body. The first body will then lag slowly behind until the second body "catches" it, at which point gravity slows the first body and drops it back into the faster orbit. </p>
<p>There's a 2-minute video that animates a horseshoe orbit <a href="https://www.youtube.com/watch?v=gsHBE3DWCP4" rel="noreferrer">here</a>; <strong>anybody reading this should watch the video, since horseshoe orbits can seem counter-intuitive and are hard to wrap one's head around</strong>. Also, this picture from <a href="https://upload.wikimedia.org/wikipedia/commons/7/73/File-Epimetheus-Janus_Orbit.png" rel="noreferrer">Wikipedia</a> shows two of Saturn's moons in such an orbit, as viewed from a rotating frame (note that Epimetheus is significantly smaller than Janus):</p>
<p><a href="https://i.stack.imgur.com/3KL3K.png" rel="noreferrer"><img src="https://i.stack.imgur.com/3KL3K.png" alt="Janus and Epimetheus"></a></p>
<p>I'm looking for a description of the likely circumstances of such an orbit, given a test case: how often would the planets change places (note that the more frequently this occurs, the greater the change in year length will be), and how long would the transitions take each time? Will there be any significant effects on either planet, such as tidal changes, while they are changing places? Is a horseshoe orbit impossible or unstable in a notably eccentric orbit, or does it take on any unusual characteristics; would the two planets follow the same ellipse or something closer to mirrored ellipses with perihelion/aphelion on opposite sides of the star, for instance?</p>
<p>One particular point I'd like to see addressed in an answer: how much flexibility does a horseshoe orbit have in terms of setting orbital distances? Are certain properties of the orbit fixed the moment one determines mean orbital distance from the star and size of the planets? Or is there room to play around with how far the two planets are in their orbits (tinkering with year length changes, for instance) while still retaining the place-changing characteristic of horseshoe orbits, and if so to what degree? The latter scenario offers more options for worldbuilding, since (if that latitude is great enough) one could then make place-changes happen anywhere from every century to once in five thousand years without changing the planets or mean orbital distance in any way.</p>
<p>I'll provide three hypothetical test cases here for people to work with (of varying difficulty). I'm hoping to keep this question generalized, so other people looking at this question can easily relate it to any comparable system they might try to create themselves; as such, answers that include formulas (and that can thus easily support different figures being plugged in) are appreciated. I'll offer rough estimates on mass and radius that would produce the necessary gravity (assuming Earth density for the planets) in case they're needed. If one answer can address all three cases, great!</p>
<p>Case One (easy):</p>
<ul>
<li>Planet A: Earth (in its normal orbit). Mass ~ 5.98 x 10^24, radius ~6400km.</li>
<li>Planet B: 0.9g Earth-like planet. Mass ~ 4.26 x 10^24, radius ~5700km.</li>
</ul>
<p>Case Two (moderate):</p>
<ul>
<li>Planet A: 1.1g Earth-like planet (in an orbit with eccentricity of 0 and year of 200 Earth days). Mass ~ 7.9 x 10^24, radius ~ 7000km. Assume the star is smaller and dimmer than the Sun to keep this habitable.</li>
<li>Planet B: 0.5g Earth-like planet. Mass ~ 7.5 x 10^23, radius ~ 3200km. I realize this planet may have atmospheric escape problems.</li>
</ul>
<p>Case Three (hard):</p>
<ul>
<li>Planet A: 1.1g Earth-like planet (in an orbit with eccentricity of 0.1 and year of 500 Earth days). Mass ~ 7.9 x 10^24, radius ~ 7000km. Assume the star is somewhat larger than the Sun to keep this in the habitable zone.</li>
<li>Planet B: 0.8g Earth-like planet. Mass ~ 3 x 10^24kg, radius ~5100km.</li>
</ul>
<p>For the purposes of this question, ignore any other planets that might be in the system, although it would be useful to know if either planet in this configuration is capable of supporting one or more moons, or if the horseshoe orbit imposes any significant limits on the moons that can be supported.</p>
<p>This is my first question here, and I recognize that it's probably a very tough one, so please let me know if there's something I need to clarify or edit! I've already made a few edits just waiting for answers, but I won't hesitate to make further changes.</p>
| [
{
"answer_id": 54809,
"author": "Feyre",
"author_id": 26119,
"author_profile": "https://worldbuilding.stackexchange.com/users/26119",
"pm_score": 3,
"selected": false,
"text": "<p>So first of all, we need to define our terms here. To be clear, the orbit relates to the barycenter of the s... | 2016/09/02 | [
"https://worldbuilding.stackexchange.com/questions/53803",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/22607/"
] | We've seen questions about multiple planets in a single orbit before, using Lagrangian points, through orbiting each other as they go around, etc. I'm looking at the creation of a hypothetical system with two habitable planets orbiting their star in a stable [horseshoe orbit](https://en.wikipedia.org/wiki/Horseshoe_orbit).
To sum up a horseshoe orbit: two bodies orbit a star in nearly the same path. One of them is slightly closer to the star than the other, so it will go around a little faster. When it "catches" the second body, it will be accelerated by its gravity. This effectively pushes the first body outward, away from the star, until its orbit is now slightly *longer* than the second body. The first body will then lag slowly behind until the second body "catches" it, at which point gravity slows the first body and drops it back into the faster orbit.
There's a 2-minute video that animates a horseshoe orbit [here](https://www.youtube.com/watch?v=gsHBE3DWCP4); **anybody reading this should watch the video, since horseshoe orbits can seem counter-intuitive and are hard to wrap one's head around**. Also, this picture from [Wikipedia](https://upload.wikimedia.org/wikipedia/commons/7/73/File-Epimetheus-Janus_Orbit.png) shows two of Saturn's moons in such an orbit, as viewed from a rotating frame (note that Epimetheus is significantly smaller than Janus):
[](https://i.stack.imgur.com/3KL3K.png)
I'm looking for a description of the likely circumstances of such an orbit, given a test case: how often would the planets change places (note that the more frequently this occurs, the greater the change in year length will be), and how long would the transitions take each time? Will there be any significant effects on either planet, such as tidal changes, while they are changing places? Is a horseshoe orbit impossible or unstable in a notably eccentric orbit, or does it take on any unusual characteristics; would the two planets follow the same ellipse or something closer to mirrored ellipses with perihelion/aphelion on opposite sides of the star, for instance?
One particular point I'd like to see addressed in an answer: how much flexibility does a horseshoe orbit have in terms of setting orbital distances? Are certain properties of the orbit fixed the moment one determines mean orbital distance from the star and size of the planets? Or is there room to play around with how far the two planets are in their orbits (tinkering with year length changes, for instance) while still retaining the place-changing characteristic of horseshoe orbits, and if so to what degree? The latter scenario offers more options for worldbuilding, since (if that latitude is great enough) one could then make place-changes happen anywhere from every century to once in five thousand years without changing the planets or mean orbital distance in any way.
I'll provide three hypothetical test cases here for people to work with (of varying difficulty). I'm hoping to keep this question generalized, so other people looking at this question can easily relate it to any comparable system they might try to create themselves; as such, answers that include formulas (and that can thus easily support different figures being plugged in) are appreciated. I'll offer rough estimates on mass and radius that would produce the necessary gravity (assuming Earth density for the planets) in case they're needed. If one answer can address all three cases, great!
Case One (easy):
* Planet A: Earth (in its normal orbit). Mass ~ 5.98 x 10^24, radius ~6400km.
* Planet B: 0.9g Earth-like planet. Mass ~ 4.26 x 10^24, radius ~5700km.
Case Two (moderate):
* Planet A: 1.1g Earth-like planet (in an orbit with eccentricity of 0 and year of 200 Earth days). Mass ~ 7.9 x 10^24, radius ~ 7000km. Assume the star is smaller and dimmer than the Sun to keep this habitable.
* Planet B: 0.5g Earth-like planet. Mass ~ 7.5 x 10^23, radius ~ 3200km. I realize this planet may have atmospheric escape problems.
Case Three (hard):
* Planet A: 1.1g Earth-like planet (in an orbit with eccentricity of 0.1 and year of 500 Earth days). Mass ~ 7.9 x 10^24, radius ~ 7000km. Assume the star is somewhat larger than the Sun to keep this in the habitable zone.
* Planet B: 0.8g Earth-like planet. Mass ~ 3 x 10^24kg, radius ~5100km.
For the purposes of this question, ignore any other planets that might be in the system, although it would be useful to know if either planet in this configuration is capable of supporting one or more moons, or if the horseshoe orbit imposes any significant limits on the moons that can be supported.
This is my first question here, and I recognize that it's probably a very tough one, so please let me know if there's something I need to clarify or edit! I've already made a few edits just waiting for answers, but I won't hesitate to make further changes. | So first of all, we need to define our terms here. To be clear, the orbit relates to the barycenter of the system. The changes are such that Janus is always farther away from Saturn's center of gravity than Epimetheus. When it comes to the barycenter.
I generated a constrained 3-body model, and plotted the distance of the moons from the barycenter, running form 2006 January 1 00:00 TDB, over 20 days.
This is a transition in which Janus starts out farther than Epimetheus.
[](https://i.stack.imgur.com/w1cz4.png)
So far so good. In fact, we could just extend this to your problem, scaling all parameters so that they can apply to a very large star, and planets, they will of course not follow your instructions.
Now to your example, the gravitation parameters calculated as the fractions ps the Sun and Earth mass are as follow:
1. Star ...... - $0.5403728495401237^{-3}\left[AU\right]^3/\left[Day\right]^2$
2. Planet A - $0.9776461689638198^{-9}\left[AU\right]^3/\left[Day\right]^2$
3. Planet B - $0.7110153956100508^{-9}\left[AU\right]^3/\left[Day\right]^2$
Next the positions and velocities.
We will *derive* the star's Ephemeris, so let's start with Planet A.
Assuming the star has 1.1 times the sun's luminosity dependent on surface which is r squared rather than mass' r cubed, but I'm not changing all this stuff now that I realized this :), this means that for a similar habitableness.
```
Solve[{L == 1.1 L2, L == 1/r^2, L2 == 1/r2^2}]
```
>
> r -> 0.953463 r2
>
>
>
So our new orbit is at `1.04881` times Earth's orbital radius, or simply `1.04881AU`. Which we will use as the initial x-component for position, with y- and z-components 0.
For an eccentricity of (near) 0 with respect to the barycenter, it further needs a velocity of:
$$\sqrt{a r}\approx\sqrt{\mu\_{star}/r\_{star}}=0.02216411615734939\left[AU\right]/\left[Day\right]$$
Unfortunately this is inconsistent with the idea of a 500 day orbit, so I will ignore this here.
Now to Planet B, let's give it the position and velocity that Planet A will have one day later. We can multiply the resultant position and velocity by some factor, and be assured that they remain consistent and that crossing events take place because of the planets' gravitational pull towards each other.
The result can give.... interesting orbits.
For instance, when Planet B has initial orbital radius of 0.995 times and initial velocity of 1.005 times that of Planet A:
Distance of planets from the barycenter:
[](https://i.stack.imgur.com/hUDEH.png)
One orbit:
[](https://i.stack.imgur.com/swDeA.gif)
Using $t=500$ yields: `{{r -> 1.68759, v -> 0.0178942}}`.
We can then continue as before.
Unfortunately, the effect which you are looking for, I'm not finding experimentally, I suspect the ratio beween the Sun and the planet's masses is too slim, if I draw the planets close enough together, they just end up sling-shotting each other out of orbit.
So I sadly don't think it's going to work at this distance from the sun.
[](https://i.stack.imgur.com/hnLNW.gif)
You can have *interesting* orbits, orbits that cross each other, but not this. |
56,139 | <p>The year is 2109 C.E my friends and I were caught in a space disaster when the spacecraft we're in broke apart during a daring escape from a patrolling spacecraft. We stole an antique cellphone (from 1999, in good working condition) from a space museum but our escape was interrupted and fortunately we managed to get into the escape pod and didn't get caught up in the explosion. The only emergency transponder in the escape pod isn't working probably due to the destruction of the spacecraft. Given the technology of 1999, is it possible for us to sent out a distress signal to alert the leaving patrol spacecraft?</p>
<p>Note: the cellphone was the most innovative product of 1999 money can buy.</p>
<p>The escape pod is not a Faraday cage we're talking about the future and the patrol spacecraft don't necessary be on a lookout for distress signal; please use these clues to your advantage.</p>
<p>If there is absolutely no way to transmit any man-made signal out, please state a valid reason why it can't be done.</p>
| [
{
"answer_id": 56144,
"author": "John Dallman",
"author_id": 22020,
"author_profile": "https://worldbuilding.stackexchange.com/users/22020",
"pm_score": 4,
"selected": false,
"text": "<p>No. The cellphone is not a general-purpose radio transmitter, and without a signal from a base statio... | 2016/09/22 | [
"https://worldbuilding.stackexchange.com/questions/56139",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/8400/"
] | The year is 2109 C.E my friends and I were caught in a space disaster when the spacecraft we're in broke apart during a daring escape from a patrolling spacecraft. We stole an antique cellphone (from 1999, in good working condition) from a space museum but our escape was interrupted and fortunately we managed to get into the escape pod and didn't get caught up in the explosion. The only emergency transponder in the escape pod isn't working probably due to the destruction of the spacecraft. Given the technology of 1999, is it possible for us to sent out a distress signal to alert the leaving patrol spacecraft?
Note: the cellphone was the most innovative product of 1999 money can buy.
The escape pod is not a Faraday cage we're talking about the future and the patrol spacecraft don't necessary be on a lookout for distress signal; please use these clues to your advantage.
If there is absolutely no way to transmit any man-made signal out, please state a valid reason why it can't be done. | Assets
* 1 obsolete piece of short range comms kit requiring a battery you probably can't charge
* 1 slightly malfunctioning escape pod with up to date comms that isn't working but you're still alive
Current standards say the Mayday should be broadcast on VHF channel 16 (156.8 MHz). A 1999 phone, probably on 2g would likely use 900MHz (UHF). The slightly broken comms unit in the pod is probably using channel 16 or equivalent\*. This is your first problem. The patrol ship will be listening in for signals broadcast on the mayday frequency. That's the frequency you need to hit, so first up is rebuilding your phone to that frequency.
*Or you could look at the pod comms system and see what's wrong.*
Your next problem is that your mobile phone's range is laughable in interstellar space. What's going to be even more laughable is when you try to use it in the radiation shielded environment of your escape pod. The signal, which is line of sight at the best of times, most likely won't even penetrate the hull. So now you need to hook it up to the external antenna used by the pod's own comms system.
*Or you could look at the pod comms system and see what's wrong.*
Now you need to make sure you're using the right broadcast method: are you on AM or FM? (There's no reason to think that 100 years from now they'd be able to pick up an analog signal)
*I'm sure you can see where I'm going with this. Fix the pod.*
Ultimately all you're going to do is rebuild a copy of the pod's own comms system with a batch of obsolete components. If you're good enough to do that you're good enough to fix the pod's own system which will be much easier.
---
\*I mention channel 16 as an example to show that there are standards for distress signals and they're very different from the standards for mobiles, if you want someone to pick it up then you need to be broadcasting on a frequency they're listening on.
**[Distress frequencies](https://en.wikipedia.org/wiki/2182_kHz)**
>
> 2182 kHz forms an essential part of the Global Maritime Distress Safety System (GMDSS). It has an associated DSC frequency at 2187.5 kHz. Other international distress frequencies, in use as of 2008, include:
>
>
>
```
121.5 MHz - civil aircraft emergency frequency
243 MHz - military aircraft emergency frequency
156.8 MHz - Marine VHF radio channel 16, short range maritime use
406 MHz / 406.1 MHz - Cospas-Sarsat international satellite-based search and rescue (SAR) distress alert detection and information distribution system
```
Discontinued frequencies
```
500 kHz Morse code is no longer monitored.
121.5 or 243 MHz locators. (No longer automatically monitored by satellite, though still used for aircraft communication and short-range direction finding.)
Effective 1 August 2013, the U. S. Coast Guard terminated its radio guard of the international voice distress, safety and calling frequency 2182 kHz and the international digital selective calling (DSC) distress and safety frequency 2187.5 kHz. Additionally, marine information and weather broadcasts transmitted on 2670 kHz terminated concurrently.
``` |
56,329 | <p><em>Disclaimer</em>: This question is the first of a new series of questions of mine about <em>introducing hexapedae to the fauna of my conworld</em>. There are/will be other questions addressing i.a.: ecosystems, <a href="https://worldbuilding.stackexchange.com/questions/56701">evolutionary factors</a>, <a href="https://worldbuilding.stackexchange.com/questions/56360">taxonomy</a></p>
<hr>
<p><em>Setting</em>: In my <a href="https://worldbuilding.stackexchange.com/questions/19788/how-would-flora-behave-on-a-two-continent-planet">conworld</a> the world is divided into two humongous continents, each taking up about half of the total landmass of the planet. Each located at the Northern and Southern poles respectively.</p>
<p><img src="https://i.imgur.com/taYD5m6.jpg" alt="Map Northern Hemisphere"></p>
<pre><code>1 Equatorial Belt | Saltwater
2 | Saltwater
5 Northern Polar Sea | Saltwater
6 | Sweetwater
</code></pre>
<hr>
<p><em>Creature</em>: The Beast-of-Burden (further BOB) is quite versatile. Despite its size and weight it can move quite fast - not anywhere near horses, mind you; though it prefers a more lumbering pace and gait. It has roamed the northern regions of the continent for as far back as anyone can think and prove and although it is not the only hexapedal mammal, it certainly is the most prominent in our lifes.<br>
Even though its got quite a temper and stubbornness to it, domestication proved easy enough according to historical texts. Since the olden days its role in our daily life has changed little. It still is used in agriculture and similar areas, harnessed in front of plows and carts; and it still is used as a pack-animal nearly anywhere the automotives with their heavy engines and tyres can't go. Even the military with their airships still make use of them.<br>
Now besides their use in labour there's not much else they're good for. Their coat doesn't grow thick enough to be worth shearing and spinning into thread. Butchering them does not yield much meat compared to their size and their consumption of plant matter, alas the few bits are quite delicious. Their long gestation and the fact that they drop multiple younglings (similar to dogs) would make one think they'd be good for dairy; but their milk has this weird tang that just makes you want to pour it into the sink - though it's amazingly rich.</p>
<p><em>Overview</em>:</p>
<ul>
<li>Form:
<ul>
<li>Hexapedal (6-legs)</li>
<li>Adults somewhat taller than oxen, caribous, bisons, etc.</li>
<li>Broad backs allowing for carrying things and young animals</li>
<li>Cannot swim, do not float (see the <em>addendum</em> at the end of the question)</li>
<li>Natural lifespan of some 30-40 years</li>
</ul></li>
<li>Habitat:
<ul>
<li>Northern part of the northern continent</li>
<li>Mountains & Valleys</li>
</ul></li>
<li>Reproduction:
<ul>
<li>Two sexes</li>
<li>Long gestation</li>
<li>Multiple younglings</li>
<li>Do only produce offspring once or twice in life</li>
</ul></li>
<li>Social:
<ul>
<li>Live in small herds</li>
<li>Multiple males and females</li>
<li>Pairings don't stay together</li>
<li>Whole group/herd cares for younglings</li>
</ul></li>
<li>Character:
<ul>
<li>Do not easily scare</li>
<li>Protective of their group and younglings</li>
<li>Docile</li>
<li>Quite ferocious when incited</li>
</ul></li>
<li>Food:
<ul>
<li>Herbivores, feed on grass, mosses, bushes, etc.</li>
<li>Multiple stomachs, ruminate food</li>
</ul></li>
<li>Produce:
<ul>
<li>Coat/Wool: similar to bisons/goats</li>
<li>Meat: comparatively small yield when butchered, mostly stringy</li>
<li>Dairy: weird after-taste, very rich in nutrients</li>
</ul></li>
</ul>
<hr>
<p><strong>Question</strong>: Does my thinking add up? Are there any big issues/contradictions in how this species looks, lives exists?</p>
<p>The question does not ask for the plausibility of a six-legged mammal in general.<br>
Questions about the taxonomical branch and other similar creatures in the ecosystem will come later.<br>
Questions on how it ends up in this specific niche of nature will come later but can be addressed in answers here as well.</p>
<hr>
<p><em>Addendum</em>:<br>
- <em>Cannot swim, do not float</em>: The idea behind this is related to big <em>earth</em>-animals such as e.g. Hippos. The BOBs are too heavy/dense in build as well as featuring a coat of fur/hair; thus they have difficulties in swimming, as in being in waters that are deeper as they can stand. They would/will still ford rivers and move into waters less deep than they can stand.<br>
- <em><a href="http://www.merriam-webster.com/dictionary/swims" rel="noreferrer">Definition of swim according to the merriam-webster</a></em> (emphasis mine): </p>
<blockquote>
<p>a : to float on a liquid: <strong>not sink</strong><br>
b : to surmount difficulties: <strong>not go under</strong> </p>
</blockquote>
| [
{
"answer_id": 56332,
"author": "Community",
"author_id": -1,
"author_profile": "https://worldbuilding.stackexchange.com/users/-1",
"pm_score": 1,
"selected": false,
"text": "<p>I'm not sure how you can expect a single answerer to address everything in what looks more like a collaborativ... | 2016/09/23 | [
"https://worldbuilding.stackexchange.com/questions/56329",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/2746/"
] | *Disclaimer*: This question is the first of a new series of questions of mine about *introducing hexapedae to the fauna of my conworld*. There are/will be other questions addressing i.a.: ecosystems, [evolutionary factors](https://worldbuilding.stackexchange.com/questions/56701), [taxonomy](https://worldbuilding.stackexchange.com/questions/56360)
---
*Setting*: In my [conworld](https://worldbuilding.stackexchange.com/questions/19788/how-would-flora-behave-on-a-two-continent-planet) the world is divided into two humongous continents, each taking up about half of the total landmass of the planet. Each located at the Northern and Southern poles respectively.
```
1 Equatorial Belt | Saltwater
2 | Saltwater
5 Northern Polar Sea | Saltwater
6 | Sweetwater
```
---
*Creature*: The Beast-of-Burden (further BOB) is quite versatile. Despite its size and weight it can move quite fast - not anywhere near horses, mind you; though it prefers a more lumbering pace and gait. It has roamed the northern regions of the continent for as far back as anyone can think and prove and although it is not the only hexapedal mammal, it certainly is the most prominent in our lifes.
Even though its got quite a temper and stubbornness to it, domestication proved easy enough according to historical texts. Since the olden days its role in our daily life has changed little. It still is used in agriculture and similar areas, harnessed in front of plows and carts; and it still is used as a pack-animal nearly anywhere the automotives with their heavy engines and tyres can't go. Even the military with their airships still make use of them.
Now besides their use in labour there's not much else they're good for. Their coat doesn't grow thick enough to be worth shearing and spinning into thread. Butchering them does not yield much meat compared to their size and their consumption of plant matter, alas the few bits are quite delicious. Their long gestation and the fact that they drop multiple younglings (similar to dogs) would make one think they'd be good for dairy; but their milk has this weird tang that just makes you want to pour it into the sink - though it's amazingly rich.
*Overview*:
* Form:
+ Hexapedal (6-legs)
+ Adults somewhat taller than oxen, caribous, bisons, etc.
+ Broad backs allowing for carrying things and young animals
+ Cannot swim, do not float (see the *addendum* at the end of the question)
+ Natural lifespan of some 30-40 years
* Habitat:
+ Northern part of the northern continent
+ Mountains & Valleys
* Reproduction:
+ Two sexes
+ Long gestation
+ Multiple younglings
+ Do only produce offspring once or twice in life
* Social:
+ Live in small herds
+ Multiple males and females
+ Pairings don't stay together
+ Whole group/herd cares for younglings
* Character:
+ Do not easily scare
+ Protective of their group and younglings
+ Docile
+ Quite ferocious when incited
* Food:
+ Herbivores, feed on grass, mosses, bushes, etc.
+ Multiple stomachs, ruminate food
* Produce:
+ Coat/Wool: similar to bisons/goats
+ Meat: comparatively small yield when butchered, mostly stringy
+ Dairy: weird after-taste, very rich in nutrients
---
**Question**: Does my thinking add up? Are there any big issues/contradictions in how this species looks, lives exists?
The question does not ask for the plausibility of a six-legged mammal in general.
Questions about the taxonomical branch and other similar creatures in the ecosystem will come later.
Questions on how it ends up in this specific niche of nature will come later but can be addressed in answers here as well.
---
*Addendum*:
- *Cannot swim, do not float*: The idea behind this is related to big *earth*-animals such as e.g. Hippos. The BOBs are too heavy/dense in build as well as featuring a coat of fur/hair; thus they have difficulties in swimming, as in being in waters that are deeper as they can stand. They would/will still ford rivers and move into waters less deep than they can stand.
- *[Definition of swim according to the merriam-webster](http://www.merriam-webster.com/dictionary/swims)* (emphasis mine):
>
> a : to float on a liquid: **not sink**
>
> b : to surmount difficulties: **not go under**
>
>
> | It doesn't matter that the milk tastes a bit funny, you're still going to drink it. The same with being a bit short on meat, if that's what there is, more so as a multiple birth animal, then that's what you'll eat, especially in an arctic environment. However most big beasts of burden have a lot of meat, it might be quite tough, but there should be a lot of it.
Reproduction rate is too low, once or twice in a lifetime isn't enough for what's fundamentally a prey animal, that'll need to be every couple of years at least. Unless your world has no predators and this species has an unbelievable survival rate for newborns.
Speaking of predators: How do they deal with them, do they have horns? Hooves? Both would come in useful.
Why do they live so long when they can only breed twice? Very few creatures live on past the end of their breeding cycle.
You should possibly also consider how females choose mates. Normally with herd animals it's one (or a small number of) dominant male(s) and the rest don't get much of a look in. The other part of this is of course, how do males impress females, do they fight, do they display, are they particularly charming in a bar, do they dance. Pair breeding is much more common in birds than mammals.
Swimming: Pretty much everything can swim, often badly but they can. Unless you have a particular plot reason for them not to, let them swim.
(Your world though, with a global belt ocean, the tides and storms are going to be epic!) |
56,701 | <p><em>Disclaimer</em>: This question is the third of a new series of questions of mine about <em>introducing hexapeds to the fauna of my conworld</em>. There are/will be other questions addressing i.a.: <a href="https://worldbuilding.stackexchange.com/questions/56329">characteristics</a>, ecosystems, <a href="https://worldbuilding.stackexchange.com/questions/56360">taxonomy</a></p>
<hr>
<p><em>Setting</em>: In my <a href="https://worldbuilding.stackexchange.com/questions/19788/">conworld</a> the world is divided into two humongous continents, each taking up about half of the total landmass of the planet. Each located at the Northern and Southern poles respectively.</p>
<p><img src="https://i.imgur.com/taYD5m6.jpg" alt="Map Northern Hemisphere"></p>
<pre><code>1 Equatorial Belt | Saltwater
2 | Saltwater
5 Northern Polar Sea | Saltwater
6 | Sweetwater
</code></pre>
<hr>
<p><em>Evolution</em>: The Beast-of-Burden (further BOB) has six legs and lives predominantly in the northern part of the continent. Its half-dozen legs have given it an advantage in areas where there's lots of uneven and loose ground, as well as more sole-area which helps it stay aloft in marshland.</p>
<p>It is generally agreed upon that features & traits such as mammary glands and live birth can be attributed to convergent evolution. The same goes for its rather long gestation and its multiple young with each birth.</p>
<p>The BOBs live in comparatively small groups of three dozen individuals at most. There doesn't seem to be a predominant alpha male or female and it has been observed that the whole group cares for young.</p>
<p>They're ruminating herbivores that feed mainly on grasses, mosses, bushes, etc.</p>
<hr>
<p><strong>Question</strong>: What (prehistoric) sea-dwelling creature has the BOB likely evolved from? And how could its evolution have looked like?</p>
<p>This question assumes that the hexaped strain of life coevolved with the quadruped strain; for example on different parts of the continent (e.g. the quadrupeds in the south and the hexapeds in the north).</p>
| [
{
"answer_id": 56705,
"author": "Community",
"author_id": -1,
"author_profile": "https://worldbuilding.stackexchange.com/users/-1",
"pm_score": 4,
"selected": true,
"text": "<p>Can I suggest something along the lines of the <a href=\"https://en.wikipedia.org/wiki/Queensland_lungfish\" re... | 2016/09/27 | [
"https://worldbuilding.stackexchange.com/questions/56701",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/2746/"
] | *Disclaimer*: This question is the third of a new series of questions of mine about *introducing hexapeds to the fauna of my conworld*. There are/will be other questions addressing i.a.: [characteristics](https://worldbuilding.stackexchange.com/questions/56329), ecosystems, [taxonomy](https://worldbuilding.stackexchange.com/questions/56360)
---
*Setting*: In my [conworld](https://worldbuilding.stackexchange.com/questions/19788/) the world is divided into two humongous continents, each taking up about half of the total landmass of the planet. Each located at the Northern and Southern poles respectively.
```
1 Equatorial Belt | Saltwater
2 | Saltwater
5 Northern Polar Sea | Saltwater
6 | Sweetwater
```
---
*Evolution*: The Beast-of-Burden (further BOB) has six legs and lives predominantly in the northern part of the continent. Its half-dozen legs have given it an advantage in areas where there's lots of uneven and loose ground, as well as more sole-area which helps it stay aloft in marshland.
It is generally agreed upon that features & traits such as mammary glands and live birth can be attributed to convergent evolution. The same goes for its rather long gestation and its multiple young with each birth.
The BOBs live in comparatively small groups of three dozen individuals at most. There doesn't seem to be a predominant alpha male or female and it has been observed that the whole group cares for young.
They're ruminating herbivores that feed mainly on grasses, mosses, bushes, etc.
---
**Question**: What (prehistoric) sea-dwelling creature has the BOB likely evolved from? And how could its evolution have looked like?
This question assumes that the hexaped strain of life coevolved with the quadruped strain; for example on different parts of the continent (e.g. the quadrupeds in the south and the hexapeds in the north). | Can I suggest something along the lines of the [**Queensland Lungfish**](https://en.wikipedia.org/wiki/Queensland_lungfish)
[](https://i.stack.imgur.com/x6EF9.jpg)
If you split the anal fin into two separate fins and move the dorsal fins slightly more forwards, you'll have the ancestor for your BOBs.
Quote from Wikipedia:
---
*Fossil records of this group date back 380 million years, around the time when the higher vertebrate classes were beginning to evolve. Fossils of lungfish almost identical to this species have been uncovered in northern New South Wales, indicating that Neoceratodus has remained virtually unchanged for well over 100 million years, making it a living fossil and one of the oldest living vertebrate genera on the planet.*
*It is one of six extant representatives of the ancient air-breathing Dipnoi (lungfishes) that flourished during the Devonian period (about 413–365 million years ago) and is the most primitive surviving member of this lineage. The five other freshwater lungfish species, four in Africa and one in South America, are very different morphologically from N. forsteri. The Queensland lungfish can live for several days out of the water, if it is kept moist, but will not survive total water depletion, unlike its African counterparts.*
--- |
57,353 | <p>I want to have a <a href="https://en.wikipedia.org/wiki/Star_cluster" rel="nofollow">star cluster</a> of <a href="https://en.wikipedia.org/wiki/Main_sequence" rel="nofollow">main-sequence stars</a> (yellow dwarfs [like our sun], orange, and red dwarfs) that are on a distance of 1-2 light years between each other, so interstellar travel is possible even with sub light speed.
The cluster should be far enough from e galaxy core, beside that I don't care is it <a href="https://en.wikipedia.org/wiki/Open_cluster" rel="nofollow">open</a> or <a href="https://en.wikipedia.org/wiki/Globular_cluster" rel="nofollow">globular</a> as long as it's stable, and there's a planets where life could form.</p>
<p>How to keep the cluster stable, since from what I read <a href="https://en.wikipedia.org/wiki/Open_cluster" rel="nofollow">open clusters</a> are very loosely bound by gravity? Globular cluster on the other hand are usually very old though there are <a href="http://www.astronomy.com/news/2005/01/the-galaxys-youngest-globular-cluster" rel="nofollow">exceptions</a> like <a href="http://hyperphysics.phy-astr.gsu.edu/hbase/astro/ngc1818.html#c1" rel="nofollow">NGC 1818</a></p>
<p>How about having <a href="https://en.wikipedia.org/wiki/Intermediate-mass_black_hole" rel="nofollow">intermediate-mass black hole</a> in the center of the cluster which the stars orbit like <a href="https://en.wikipedia.org/wiki/Messier_15" rel="nofollow">Messier 15</a> see <a href="https://youtu.be/rgvs3dl40ko?t=5m2s" rel="nofollow">video</a> ? Would it help or it makes more problems then it solves since I want habitable planets on the stars? </p>
<p>Would having all the star to be orange or even red dwarfs help with keeping them closer together?</p>
<p><strong>Conclusion</strong></p>
<p>It seems that my setting though very cool, seems unstable. To finish on a positive note here's a link to <a href="http://www.sci-news.com/astronomy/ngc-6101-star-cluster-black-holes-04177.html" rel="nofollow">NGC 6101</a> cluster with hundreds of black holes, if life ever evolves there their astronomers will know quite a lot about them.</p>
| [
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"answer_id": 57362,
"author": "Green",
"author_id": 10364,
"author_profile": "https://worldbuilding.stackexchange.com/users/10364",
"pm_score": 2,
"selected": false,
"text": "<h2>This area probably won't sustain life for long</h2>\n\n<p>Having lots of stars this close feels like a stel... | 2016/10/03 | [
"https://worldbuilding.stackexchange.com/questions/57353",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/26533/"
] | I want to have a [star cluster](https://en.wikipedia.org/wiki/Star_cluster) of [main-sequence stars](https://en.wikipedia.org/wiki/Main_sequence) (yellow dwarfs [like our sun], orange, and red dwarfs) that are on a distance of 1-2 light years between each other, so interstellar travel is possible even with sub light speed.
The cluster should be far enough from e galaxy core, beside that I don't care is it [open](https://en.wikipedia.org/wiki/Open_cluster) or [globular](https://en.wikipedia.org/wiki/Globular_cluster) as long as it's stable, and there's a planets where life could form.
How to keep the cluster stable, since from what I read [open clusters](https://en.wikipedia.org/wiki/Open_cluster) are very loosely bound by gravity? Globular cluster on the other hand are usually very old though there are [exceptions](http://www.astronomy.com/news/2005/01/the-galaxys-youngest-globular-cluster) like [NGC 1818](http://hyperphysics.phy-astr.gsu.edu/hbase/astro/ngc1818.html#c1)
How about having [intermediate-mass black hole](https://en.wikipedia.org/wiki/Intermediate-mass_black_hole) in the center of the cluster which the stars orbit like [Messier 15](https://en.wikipedia.org/wiki/Messier_15) see [video](https://youtu.be/rgvs3dl40ko?t=5m2s) ? Would it help or it makes more problems then it solves since I want habitable planets on the stars?
Would having all the star to be orange or even red dwarfs help with keeping them closer together?
**Conclusion**
It seems that my setting though very cool, seems unstable. To finish on a positive note here's a link to [NGC 6101](http://www.sci-news.com/astronomy/ngc-6101-star-cluster-black-holes-04177.html) cluster with hundreds of black holes, if life ever evolves there their astronomers will know quite a lot about them. | Let’s determine some basic parameters of the cluster.
You say you want the stars to be 1-2 light-years apart. This is a little tricky because star clusters don’t necessarily have uniform densities. Globular clusters, for instance, have radial density profiles decreasing from some core density at $R=0$ to zero density somewhere further out. There are several density profiles used to model this. The [Plummer model](https://en.wikipedia.org/wiki/Plummer_model) is easily the simplest, as analytic expressions exist for density and potential. The King model (see [King (1966)](http://adsabs.harvard.edu/abs/1966AJ.....71...64K), the third in a series of papers) is more accurate, though the density must be solved for numerically, and the Michie model can be even more accurate (see e.g. [this thesis](http://physics.wm.edu/Seniorthesis/SeniorThesis2005/shervthesis.pdf)), as it can account for dark matter.
I’m going to follow a modified version of the models of [Bonatto & Bica (2014)](http://www.aanda.org/articles/aa/full/2008/03/aa8616-07/aa8616-07.html), who use a King profile (here applicable to open clusters). The fraction of the total number of stars $N$ within a radius $R$ is given by
$$n(R)=\frac{x^2-4u\left(\sqrt{1-x^2}-1\right)+u^2\ln\left(1+x^2\right)}{u^2\ln u^2-(u-1)(3u-1)}\tag{1}$$
where
$$x\equiv R/R\_c,\quad u\equiv\sqrt{1+\left(R\_t/R\_c\right)^2}$$
with $R\_t$ and $R\_c$ being the tidal and core radii of the cluster; the cluster is truncated at $R=R\_t$. The authors recommend a ratio $R\_t/R\_c\approx15$. Therefore, we just have to specify one of those two parameters (we also know that $u=226$). The tidal radius can be computed depending on the mass of the cluster and its distance from the center of the galaxy (see e.g. [Wu et al. (2009)](http://batc.bao.ac.cn/papers/BATC-papers/2009wzy-26_2_029701.pdf)). That would require us to specify additional parameters, so I’ll assume that the cluster is average, and give it a tidal radius of about 10 parsecs. Thus, the core radius is roughly 0.67 parsecs. This could be an overestimate; [Piskunov et al. (2008)](http://adsabs.harvard.edu/abs/2008A%26A...477..165P), for instance, surveyed 236 open clusters in the Milky Way and found that the tidal radius peaked at around 6 parsecs. Still, 10 parsecs is by no means unreasonable. At any rate, I’d prefer a more massive cluster, so more stars may survive for longer periods of time.
Some quick *Mathematica* gives me
```
Clear[Rt, Rc]
x[R_, Rc_] := R/Rc
u[Rt_, Rc_] := Sqrt[1 + (Rt/Rc)^2]u[Rt_, Rc_] := Sqrt[1 + (Rt/Rc)^2]
n[R_, Rt_, Rc_] := ((x[R, Rc])^2 - 4*(u[Rt, Rc])*(Sqrt[1 + (x[R, Rc])^2] - 1) + (u[Rt, Rc])^2*Log[1 + (x[R, Rc])^2])/((u[Rt, Rc])^2*Log[(u[Rt, Rc])^2] - (u[Rt, Rc] - 1)*(3*u[Rt, Rc] - 1))
Plot[n[R, 10, 2/3], {R, 0, 10}, AxesLabel -> {"Radius (Parsecs)", "Number of stars"}]
```
[](https://i.stack.imgur.com/vT2po.png)
The actual number of stars inside $R$ is simply $n$ multiplied by the number of stars in the cluster, $N$. We’ll take $N\sim10^3$, a decently sized cluster. How do we now go from $n\cdot N$ to number density, $\mathcal{N}$ (just to make things more confusing)? Well, take the formula for the mass $M$ of a sphere inside a radius $R$ with radial density $\rho(r)$:
$$M=\int\_0^R 4\pi r^2\rho(r)\mathrm{d}r$$
Simply divide $M$ by the average mass of a star (which I’ll get to later, but is unimportant for now) and we get
$$n\cdot N=\int\_0^R4\pi r^2\mathcal{N}(r)\mathrm{d}r$$
We just differentiate and divide:
$$\mathcal{N}(r)=\frac{\mathrm{d}n}{\mathrm{d}r}N\frac{1}{4\pi r^2}\tag{2}$$
In the code, we add
```
P[R_, Rt_, Rc_] = D[n[R, Rt, Rc], R]*1000*(4*Pi*R^2)^(-1)P[R_, Rt_, Rc_] = D[n[R, Rt, Rc], R]*1000*(4*Pi*R^2)^(-1)
Plot[P[R, 10, 2/3], {R, 0, 10}, AxesLabel -> {"Radius (Parsecs)", "Number density"},ScalingFunctions->"Log"]
```
where I’ve replaced $\mathcal{N}$ with $P$, and we get, with a logarithmic $y$-axis,
[](https://i.stack.imgur.com/6b57c.png)
Note that the number density goes to infinity as $R$ goes towards the center (which we can check by simply evaluating the limit of $\mathcal{N}(R)$ as $R\to0$). However, we know that $n(R\_t)$ is finite (although $\lim\_{R\to\infty} n(R)=\infty$, which is why we truncated it). I played around with `Animate` for $N$:
```
Animate[Plot[P[R, 10, 2/3, Nt], {R, 0, 10}, AxesLabel -> {"Radius (Parsecs)", "Number density"}, ScalingFunctions -> "Log"], {Nt, 10^2, 10^5}, AnimationRunning -> False]
```
and found that you can get *extremely* high number densities in the center, if you so desire, which makes sense.
[](https://i.stack.imgur.com/2mBSK.gif)
To find the average separation between two stars, we calculate the [mean interparticle distance](https://en.wikipedia.org/wiki/Mean_inter-particle_distance), scaled correctly (i.e. the [Wigner–Seitz radius](https://en.wikipedia.org/wiki/Wigner%E2%80%93Seitz_radius)):
$$r\_s(R)=\left(\frac{3}{4\pi\mathcal{N}(R)}\right)^{1/3}\tag{3}$$
We add another section of code:
```
rs[R_, Rt_, Rc_] := (3/(4*Pi*(n[R, Rt, Rc])))^(1/3)
Plot[rs[R, 10, 2/3], {R, 0, 10}, AxesLabel -> {"Radius (parsecs)", "rs"}, ScalingFunctions -> "Log"]
```
and, plotting this function, get
[](https://i.stack.imgur.com/MBYoe.png)
We see that $r\_s$ is always greater than about 2 light-years for $0\leq R\leq R\_t$. Towards the center. Therefore, the systems you’re interested in should be near the outer edge of the cluster.
Hold on a minute, though. This is a density distribution based entirely on a sphere of stars, with nothing else influencing them. We’ve guessed that this models an open cluster fairly well, but we also need to assume that the cluster, if left to its own devices, is unstable, and the stars will drift away. Let’s try adding a central object, like you suggested - an [intermediate-mass black hole (IMBH)](https://en.wikipedia.org/wiki/Intermediate-mass_black_hole). This isn’t terribly far-fetched; it’s an idea that’s been explored quite a lot in the case of globular clusters. In open clusters, we have problems because we need to explain how the black hole got there in the first place. However, we can ignore that for now.
If there’s a central, massive object in a star cluster, the cluster should exhibit a [Bahcall-Wolf cusp](https://en.wikipedia.org/wiki/Bahcall%E2%80%93Wolf_cusp). Within a distance equal to one fifth of the black hole’s [sphere of influence](https://en.wikipedia.org/wiki/Sphere_of_influence_(black_hole)), the density should obey a power law of the form
$$\rho\_{BW}(R)\propto R^{-7/4}$$
Number density, assuming a roughly homogeneous population (again, more on that later), should obey this power law:
$$\mathcal{N}\_{BW}(R)\propto R^{-7/4}\tag{4}$$
All we have to do is calculate the sphere of influence, find the number density there according to the King model we computed, and fit the two together.
The sphere of influence, according to one definition, is
$$r\_h=\frac{GM\_{BH}}{\sigma\_0}\tag{5}$$
where $G$ is the gravitational constant $M\_{BH}$ is the mass of the black hole, and $\sigma\_0$ is the central stellar velocity dispersion, which I’ll choose to be about .81 km/s - modeled after observations by [Geller et al. (2009)](https://arxiv.org/abs/1001.0033) of [M35](https://en.wikipedia.org/wiki/Messier_35), a reasonably analog to our cluster. I’m going to choose $M\_{BH}\sim10^4M\_\odot$. We then get $r\_h\approx 6.25$ parsecs, and the Bahcall-Wolf cutoff radius is roughly 1.25 parsecs.
Let’s calculate the number density at $R=\frac{1}{5}r\_h$ from the King model. We get 17.44 stars per cubic parsec - quite large! If we then assume that the cusp stars there, we know that
$$\mathcal{N}\_{BW}(R)=17.44=A(1.25)^{-7/4}$$
for some constant $A$, which we find to be $A=25.77$. All we have to do now is to plot the two together in a piecewise number density function, defined as follows:
$$\mathcal{N}(R)=
\begin{cases}
\frac{\mathrm{d}n}{\mathrm{d}R}N\frac{1}{4\pi R^2},\quad 0\leq R\leq1.25\\
25.77R^{-7/4},\quad1.25\leq R\leq10\\
\end{cases}\tag{6}$$
Plotting this on with a logarithmic $y$-axis gives us
[](https://i.stack.imgur.com/axoH9.png)
Here’s the code I used to do the calculations and generate the plots (although you can play around with various parameters, like black hole mass and total cluster mass):
```
Clear[Rt, Rc]
Rt = 10(*Tidal radius*)
Rc = 2/3(*Core radius*)
x[R_, Rc_] := R/Rc
u[Rt_, Rc_] := Sqrt[1 + (Rt/Rc)^2]
n[R_, Rt_, Rc_] := ((x[R, Rc])^2 - 4*(u[Rt, Rc])*(Sqrt[1 + (x[R, Rc])^2] - 1) + (u[Rt, Rc])^2*Log[1 + (x[R, Rc])^2])/((u[Rt, Rc])^2*Log[(u[Rt, Rc])^2] - (u[Rt, Rc] - 1)*(3*u[Rt, Rc] - 1))(*Number of stars in King model*)
P[R_, Rt_, Rc_] = D[n[R, Rt, Rc], R]*1000*(4*Pi*R^2)^(-1)(*Number density from King model*)
rs[R_, Rt_, Rc_] := (3/(4*Pi*(n[R, Rt, Rc])))^(1/3)(*Wigner-Seitz radius*)
PBW[R_, Rt_, Rc_] := 25.77*(R)^(-7/4)(*Bahcall-Wolf cusp*)
np[R_, Rt_, Rc_] := Integrate[(1/1000)*4*Pi*x^2*PBW[x, Rt, Rc], {x, 0, 1.25}] + Integrate[(1/1000)*4*Pi*y^2*P[y, Rt, Rc], {y, 1.25, R}](*Total number of stars in cluster*)
Plot[n[R, 10, 2/3], {R, 0, 10}, AxesLabel -> {"Radius (Parsecs)", "Number of stars"}]
Plot[P[R, 10, 2/3], {R, 0, 10}, AxesLabel -> {"Radius (Parsecs)", "Number density"}, ScalingFunctions -> "Log"]
Plot[rs[R, 10, 2/3], {R, 0, 10}, AxesLabel -> {"Radius (Parsecs)", "rs"}, ScalingFunctions -> "Log"]
Plot[{Piecewise[{{P[R, 10, 2/3], 1.25 < R < 10}, {PBW[R, 10, 2/3], 0 < R < 1.25}}]}, {R, 0, 10}, AxesLabel -> {"Radius (Parsecs)", "Number density"}, PlotRange -> 10^3, ScalingFunctions -> "Log"](*Plots final density*)
```
Congratulations! You just built an open cluster!
Well, we built a simplified model of an open cluster, and we made more assumptions than I’d prefer:
* All the mass of the cluster consists of stars and the central black hole, which gravitationally dominates most of the cluster. In reality, there should be gas and dust in the cluster, because the stars formed from [giant molecular clouds](https://en.wikipedia.org/wiki/Molecular_cloud#Giant_molecular_clouds).
* The stellar population is homogeneous, i.e. all of the stars are the same. In general, this isn’t the case. Stars that formed together might be similar, but often they’re quite different. Their masses should be be distributed as predicted by some sort of [initial mass function (IMF)](https://en.wikipedia.org/wiki/Initial_mass_function). This created no problems so far, but it might when you take into account things like mass segregation that are important in globular clusters. If you’re *really* interested in fixing this, you can use something like the [MASSCLEAN](http://bogdan.massclean.org/massclean3.html) packages to generate star clusters via the King model and an IMF (the default is the Salpeter IMF). It’s a pretty cool tool, and can save you a lot of work.
* A King model defines the cluster. I’d be more comfortable using a King model to describe a globular cluster, and I see no reason why you couldn’t just have a young globular cluster - like [M15](https://en.wikipedia.org/wiki/Messier_15), as you suggested - but I’m okay applying our version of it to our open cluster.
None of these, however, are fatal flaws in our model.
So, is this cluster going to be stable over long timescales? That, after all, is the question we’re trying to answer. Well, to start, there are several things in our favor:
* The cluster contains $\sim10^3$ stars, which is a decent amount for an open cluster. I think that should make it more likely to end up with a sizable number of stars.
* The black hole is quite massive compared to the cluster - more massive than the rest of the cluster, in fact. I did this on purpose, because it means that the black hole’s sphere of influence is over half the tidal radius of the entire cluster. Again, this should make it easier to retain more stars.
Let’s do a more formal assessment (based on e.g. [these notes](https://www.ethz.ch/content/dam/ethz/special-interest/phys/astronomy/astro-dam/documents/education/courses/Astrophysics%20III/A3C3dynamics.pdf)). Let the mean mass of a star in the cluster be $m\_m$. By the [virial theorem](https://en.wikipedia.org/wiki/Virial_theorem), the speed $v$ of a star at $R\approx. R\_t$ is given by
$$v^2\approx\frac{GNm\_m}{R\_t}\tag{7}$$
The time it takes a star to travel $R\_t$, the crossing time $t\_c$, is
$$t\_c=R/v\tag{8}$$
and the relaxation time $t\_r$, the time over which encounters with other stars begin to have an effect on the motion of a star, is
$$t\_r\approx\frac{0.1N}{\ln N}t\_c\tag{9}$$
Furthermore, if a percent $\gamma$ of stars have a velocity above a certain critical value, then the evaporation time of the system is
$$t\_e=\frac{t\_r}{\gamma}\approx t\_r\times10^2\tag{10}$$
So, what critical parameters have changed now that we added the Bahcall-Wolf cusp? Well, we can safely assume that $m\_m$ and $R\_t$ are the same, as we specified them. It turns out, however, than $N$ has changed. Integrating over the piecewise density distribution gives $n(R\_t)=0.89$, meaning that we have fewer stars in the cluster.
At the same time, the total mass of the cluster is much, much larger, since the black hole’s mass is substantially greater than the mass of the stars. Therefore,
$$v^2\approx\frac{GNm\_m+M\_{BH}}{R\_t}$$
Having fewer stars and adding a black hole will lead to a much shorter relaxation time. Even if we extend the tidal radius (as would be expected), the black hole still won’t help stars at the outside of the cluster. I recall one paper noting that in the case of a black hole with a mass somewhat less than that of the cluster, most of the stars in the outer regions of the cluster will behave just as if the cluster was perfectly described by a King model, with no central black hole.
At the center of the cluster, there will indeed be some significant effects - and since the number density is much greater there, a large fraction of the stars should be impacted. I’m reluctant to draw analogies between stellar clusters and galaxies, but stars near the center should be influenced just like stars near the supermassive black hole at the center of the Milky Way, [Sagittarius A\*](https://en.wikipedia.org/wiki/Sagittarius_A*), orbit the black hole. The analogy is actually fairly good: Most stars in a galaxy don’t orbit the central supermassive black hole; they orbit the total mass of the galaxy. It’s a self-gravitating system, not a set of bodies orbiting one massive one. At the very center, however, stars are clearly orbiting Sagittarius A\*. The same holds true for our open cluster.
So, to summarize:
* Stars in the outer regions of the open cluster will likely leave the cluster at the same time or earlier than if there was no intermediate mass black hole at the center.
* Stars within the sphere of influence of the black hole, especially within the Bahcall-Wolf cusp, will be influenced strongly by the black hole and may directly orbit it.
* The cluster will largely “evaporate” on the same timescale (though likely a shorter one) than if it had no central black hole. However, I think the central group of stars will remain bound to the black hole. Eventually, this will be all that remains of the open cluster, if the orbits are stable.
* Whether or not life can survive on planets orbiting these stars is another question entirely, and I’ll deal with that in a future edit of this answer, if you want. |
57,535 | <p>I’m working on a setting, and have a state I want to achieve but need to come up with a compelling reason for why it is the way it is (even if no one but me ever knows the ‘why’.) I’m after a reasoned, logical answer that flows along the lines of greatest probability rather than a “it’s this way because I <em>say so</em>” type answer. I don't need a “hard science” answer because fundamentally the scenario has at least one foot in fantasy, but well thought out discourse is appreciated. </p>
<p><strong>The set up:</strong> </p>
<p>In the future humans invent and built half-biological, half-mechanical bio-suits. They stand two or so times taller than an average human and can contain one fully inside themselves; they were controlled via direct-neural link. These suits offered many advantages:</p>
<pre><code>-Low maintenance (limited self-healing ability)
-Increased dexterity/reduced learning curve for new pilot.
-Increased situational awareness (pilots often “becoming” the suit while operating it)
-Massive strength increases compared to a normal person
-Greatly increased personal protection in almost any environment.
-Ability to operate independently for far longer than purely mechanical counterparts.
</code></pre>
<p>These suits functioned as a boon for their operators, increasing their physical capabilities many-fold… until the suits had the audacity to start <em>talking</em> to their operators from their own free will. (albeit given; this was a surprise for both parties)</p>
<p>The how and why and what happened are irrelevant in the scope of this question except for eventually these suits are recognized as a fully sentient, self-aware, cognizant species with IQs on par with humans. </p>
<p>When joined, control is often split between the bio-suits consciousness and the human’s consciousness, as desired by the pair. Joining is also considered more of a personal arrangement then a business one, so money exchanges are considered taboo.</p>
<p>The question:</p>
<p><strong>What benefits could a human give that would encourage a symbiotic relationship between that human and a bio-suit?</strong></p>
<p>There is obviously an advantage for the human, because they get all the above mentioned advantages as well as someone to talk to. The bio-suits does not anything out of the arrangement (besides extra weight and drain) on the surface, so it appears to be parasitic. </p>
<p>It’s hard to think of a justifiable advantage. Money certainly could be a motivator, but that puts it into a master/servant style relationship and over the longer term (I believe it is also untenable because at its base it’s still a parasitic relationship.) Things like “ability to get things from the corner market that has the small doors” would go away when construction adjusted after a generation to have bigger doors. Getting some sort of legal status or rights from the arrangement also is not a solution (see “just about any civil rights movement ever”). </p>
<p>So what advantages can the basically smaller and less physically capable humans offer in a symbiotic relationship with these bio-suits? Anything more intimate/interweaving then basically “do this for me and I'll pay you X”? </p>
<p>Edit space for questions:</p>
<ul>
<li>The functioning-in-detail of the suits has not been pinned down; so various flaws can be introduced; however things like "cannot breath without human" would take things too far; each side should be able to exist independent of the other, but find advantage for working together. </li>
<li>Long term direct mind-to-mind exposure is the only real form of possible dependence that can form between a pair without intentional intervention; nothing stops a pair from separating beyond the fact that after a certain point they stop being a "pair" and start being a "one". Possible caveats to this are health considerations where one party helps support a failing system on another.</li>
</ul>
| [
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"text": "<p>A symbiot needs to be a mutually beneficial arrangement otherwise it is just parasitism.</p>\n\n<p>This s... | 2016/10/04 | [
"https://worldbuilding.stackexchange.com/questions/57535",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/17263/"
] | I’m working on a setting, and have a state I want to achieve but need to come up with a compelling reason for why it is the way it is (even if no one but me ever knows the ‘why’.) I’m after a reasoned, logical answer that flows along the lines of greatest probability rather than a “it’s this way because I *say so*” type answer. I don't need a “hard science” answer because fundamentally the scenario has at least one foot in fantasy, but well thought out discourse is appreciated.
**The set up:**
In the future humans invent and built half-biological, half-mechanical bio-suits. They stand two or so times taller than an average human and can contain one fully inside themselves; they were controlled via direct-neural link. These suits offered many advantages:
```
-Low maintenance (limited self-healing ability)
-Increased dexterity/reduced learning curve for new pilot.
-Increased situational awareness (pilots often “becoming” the suit while operating it)
-Massive strength increases compared to a normal person
-Greatly increased personal protection in almost any environment.
-Ability to operate independently for far longer than purely mechanical counterparts.
```
These suits functioned as a boon for their operators, increasing their physical capabilities many-fold… until the suits had the audacity to start *talking* to their operators from their own free will. (albeit given; this was a surprise for both parties)
The how and why and what happened are irrelevant in the scope of this question except for eventually these suits are recognized as a fully sentient, self-aware, cognizant species with IQs on par with humans.
When joined, control is often split between the bio-suits consciousness and the human’s consciousness, as desired by the pair. Joining is also considered more of a personal arrangement then a business one, so money exchanges are considered taboo.
The question:
**What benefits could a human give that would encourage a symbiotic relationship between that human and a bio-suit?**
There is obviously an advantage for the human, because they get all the above mentioned advantages as well as someone to talk to. The bio-suits does not anything out of the arrangement (besides extra weight and drain) on the surface, so it appears to be parasitic.
It’s hard to think of a justifiable advantage. Money certainly could be a motivator, but that puts it into a master/servant style relationship and over the longer term (I believe it is also untenable because at its base it’s still a parasitic relationship.) Things like “ability to get things from the corner market that has the small doors” would go away when construction adjusted after a generation to have bigger doors. Getting some sort of legal status or rights from the arrangement also is not a solution (see “just about any civil rights movement ever”).
So what advantages can the basically smaller and less physically capable humans offer in a symbiotic relationship with these bio-suits? Anything more intimate/interweaving then basically “do this for me and I'll pay you X”?
Edit space for questions:
* The functioning-in-detail of the suits has not been pinned down; so various flaws can be introduced; however things like "cannot breath without human" would take things too far; each side should be able to exist independent of the other, but find advantage for working together.
* Long term direct mind-to-mind exposure is the only real form of possible dependence that can form between a pair without intentional intervention; nothing stops a pair from separating beyond the fact that after a certain point they stop being a "pair" and start being a "one". Possible caveats to this are health considerations where one party helps support a failing system on another. | The neuro-pathways of the suits are very simple when they are "built". There is a large cluster around the neural-link port that handles all the sensory input from the suit to the human and all the control input from the human to the suit. Over time, this cluster specializes and becomes more complex to more efficiently handle this transmission. Eventually this "brain" learns how to do things rather than needing to be instructed on each step.
For example, a new suit would need to have each individual step outlined (lift left foot, swing forward, plant left foot, lift right foot, etc). Over time, the suit would pick up on "walk over there" without each step needing to be defined. Eventually it could pick the optimal path, perhaps even deciding to move an obstacle rather than moving around it.
As the suit becomes more and more optimized and efficient, the operators need to focus less on the task of moving and may even engage in daydreaming while the suit does the work. The daydreams also drift across the neural-link which triggers building other pathways to decipher them.
Eventually, the pathways around the neural-link develop enough to awaken into self-consciousness.
So the benefit to the suit is the initial development of the suit's personality and consciousness.
Another benefit could be that the suits neural network is optimized to process incoming sensory input and receive outside commands. When there is no incoming commands, the suit *is* able to act autonomously, but it may not be as quick as it is when connected to a human. Or perhaps, part of a suit's pathways include paths to the neural-port where it would query the subconsciousness of the pilot when working out problem-solving skills.
So:
A human-in-a-suit is stronger and more physically able.
A suit-around-a-human is more intellectually nimble and quick. |
57,559 | <p>Suppose the Wicked Witch of the West was simply an alien life form that was stranded in Oz. She comes from a race of beings that are water soluble. </p>
<p>She would have to be able to resist a small amount of water, or else any contact with water vapors in the atmosphere would dissolve her. Yet, any significant amount of water (such as a cup of it), would instantly cause her to dissolve.</p>
<p>Is this even possible?</p>
| [
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"text": "<p>One way this is possible is to have an organism that uses methanol as a solvent. Methanol is less polar than... | 2016/10/04 | [
"https://worldbuilding.stackexchange.com/questions/57559",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/28102/"
] | Suppose the Wicked Witch of the West was simply an alien life form that was stranded in Oz. She comes from a race of beings that are water soluble.
She would have to be able to resist a small amount of water, or else any contact with water vapors in the atmosphere would dissolve her. Yet, any significant amount of water (such as a cup of it), would instantly cause her to dissolve.
Is this even possible? | Certainly, this is possible. Almost all things are, after all.
However, the effect of melting when exposed to large amounts of liquid water is probably not what it initially appears to be.
An alien organism that is tolerant to small amounts of water is probably one that is tolerant to larger amounts too, so why would a large amount of water make the alien melt?
My hypothesis is that this particular alien is actually composed of a great many small subunits. This is similar to our cellular model, but the alien subunits may *themselves* be tiny, aquatic, multicellular organisms. These organisms have the ability to clump together into a single colony in times of drought in order to present a reduced surface area through which water may be lost, and when a sufficiently heavy rain comes along, they can disband and do their own thing, such as mating.
Over time, these organisms have evolved the ability to move and form a group intelligence while joined in a colony, however the single consciousness which results is dependent upon the particular arrangement of the individual organisms, and should the colony disband, its consciousness will cease, and even if the colony subsequently reforms from the same organisms, the inability of the organisms to achieve exactly the same configuration as before means that the reformed colony will be a new consciousness with a different personality, though with remnant skills and knowledge left over from the previous configuration.
Naturally, the longer a colony exists in a particular configuration, the more skills and knowledge it will accumulate, increasing the survivability of the colony. This would lead to a state where the collective consciousnesses of the colonies would be reluctant to disband voluntarily unless presented with a suitably large body of water, but where a relatively small amount of water could fool the individual organisms into disbanding. Of course, if there really *wasn't* enough water, the colony could reform - as a different consciousness - but this would be a case where sentience has overtaken the limitations of evolution. Yes, the colony could reform - doing so would be better than not doing so if there really isn't enough water - but the reformed colony would no longer be the same person since its neural pathways would be different.
So, if the Wicked Witch of the West was such a colonial organism, splashing it with sufficient water to trigger the instinctual disbanding of the colony in preparation for the mating season would in effect be a sentence of death for that particular colonial *sentience*, even if after a little while the colonial organisms could re-form the colony. After such an event, despite all the same organisms being present, it would be a different colony with a different personality and probably fewer skills.
Given that, it is not surprising that the *consciousness* of the "melting" Wicked Witch could - in the moments remaining to it - recognise that it would cease to exist due to the triggering of an instinctive response of its member organisms, and bewail that fact. It would have good cause, since any reformed colony would likely have fewer valuable skills, and hence be less able to survive.
**EDIT**
In response to the OP's comment that it might be possible to re-imprint the colony's original personality onto the reformed colony, I offer this variation, which would not be too difficult to evolve:
The colonial subunits have individual identities, and after spending a considerable amount of time next to other individuals, can remember exactly which individuals to whom they were adjacent, even after dissolution and reformation of the colony. While the colony could be reformed quite quickly, it would have a random configuration with a new personality and few skills.
However, the individual subunits memories of their previous neighbours and the neural network of the colony would allow the subunits to change their positions within the colony to recreate its previous configuration and thus restore the previous personality with its more developed skills.
However, if we are using the Wizard of Oz as the template for this species, then the behaviour above is not consistent with the reactions of the Wicked Witch of the West to being splashed by a bucketful of water:
From Frank L Baum's novel, *The Wonderful Wizard of Oz*:
>
> "You are a wicked creature!" cried Dorothy. "You have no right to
> take my shoe from me."
>
>
> "I shall keep it, just the same," said the Witch, laughing at her,
> "and some day I shall get the other one from you, too."
>
>
> This made Dorothy so very angry that she picked up the bucket of
> water that stood near and dashed it over the Witch, wetting her from
> head to foot.
>
>
> Instantly the wicked woman gave a loud cry of fear; and then, as
> Dorothy looked at her in wonder, the Witch began to shrink and fall
> away.
>
>
> "See what you have done!" she screamed. "In a minute I shall melt
> away."
>
>
> "I'm very sorry, indeed," said Dorothy, who was truly frightened to
> see the Witch actually melting away like brown sugar before her very
> eyes.
>
>
> "Didn't you know water would be the end of me?" asked the Witch, in a
> wailing, despairing voice.
>
>
> "Of course not," answered Dorothy; "how should I?"
>
>
> "Well, in a few minutes I shall be all melted, and you will have the
> castle to yourself. I have been wicked in my day, but I never thought
> a little girl like you would ever be able to melt me and end my
> wicked deeds. Look out--here I go!"
>
>
>
or from the *The Wizard of Oz* movie script:
>
> MS -- Dorothy throwing water at Scarecrow -- some of it hits the Witch in
> the face -- Tin Man standing at left with the Lion --
>
>
>
> ```
> SCARECROW
> Help!
>
> ```
>
> MCU -- The water hits the Witch in the face --
>
>
> MS -- The Witch screams as the water hits her -- Tin Man, Lion, Dorothy
> and Scarecrow look at her --
>
>
> MLS -- The Lion, Tin Man, Dorothy and Scarecrow watch the Witch as she
> screams and melts away -- camera shooting past Winkies in the f.g. -- the
> Witch curses as she disappears, finally only her cloak and hat remain on
> the floor -- her voice fades away --
>
>
>
> ```
> WITCH
> Ohhh -- you cursed brat! Look what you've
> done! I'm melting! Melting! Oh -- what a
> world -- what a world! Who would have
> thought a good little girl like you could
> destroy my beautiful wickedness!? Ohhh!
> Look out! Look out! I'm going. Ohhhh!
> Ohhhhhh....
>
> ```
>
>
Such behaviour would be more consistent with the behaviour I originally described, in that the colonial subunits are not capable of restoring a particular configuration through the process of dissolution and reformation of the colony.
However, the novel also describes the Wicked Witch of the West as being "cunning", so it is not beyond the bounds of possibility that this reaction may have been a sham intended to lead Dorothy and company to *believe* that this dissolution was fatal, so that when the colony reformed - hopefully after Dorothy and company had left the area - it could restore its long-term configuration and personality and continue pursuing its goals with the added advantage that its enemies believed it to be deceased. |
57,571 | <p>I'm trying to design a realistic genetically engineered nanotech super-soldier with a full set of redundant organs. How much more interior volume and thus height/weight/muscle mass would a human body need to support 2 hearts, 3 lungs, 2 stomachs, 3 kidneys, 2 livers, 2 sets of large and small intestines, 2 esophagi/trachea, and 2 sets of certain major bones (femur, spine, humerus etc.)? Additionally, could a human brain be "taken apart" and redistributed throughout the body while still functioning? This super soldier should be designed with as many safeguards and redundancies as possible.</p>
<p>Also, this bio-engineered human needs to still look... human. Is it possible to accommodate for all these changes with only an increase in height and muscle mass, or is it inevitable that anyone with this much modification will start to look like a walking tank made of meat?</p>
| [
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"text": "<p>The extra weight shouldn't be too bad. From <a href=\"https://www.quora.com/How-is-body-weight-distribut... | 2016/10/04 | [
"https://worldbuilding.stackexchange.com/questions/57571",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/21870/"
] | I'm trying to design a realistic genetically engineered nanotech super-soldier with a full set of redundant organs. How much more interior volume and thus height/weight/muscle mass would a human body need to support 2 hearts, 3 lungs, 2 stomachs, 3 kidneys, 2 livers, 2 sets of large and small intestines, 2 esophagi/trachea, and 2 sets of certain major bones (femur, spine, humerus etc.)? Additionally, could a human brain be "taken apart" and redistributed throughout the body while still functioning? This super soldier should be designed with as many safeguards and redundancies as possible.
Also, this bio-engineered human needs to still look... human. Is it possible to accommodate for all these changes with only an increase in height and muscle mass, or is it inevitable that anyone with this much modification will start to look like a walking tank made of meat? | The extra weight shouldn't be too bad. From [Quora](https://www.quora.com/How-is-body-weight-distributed-between-bones-organs-muscle-and-fat):
>
> Approximate body weight distribution for a lean adult:
>
>
>
> ```
> Bone: men 15%; women 10%
> Muscle: men 45%; women 37%
> Organs: men and women: 25%
> Fat: men 15%; women 28%
>
> ```
>
>
So you're looking at adding 25-40% weight, depending on how many of the bones you replace.
However, the brain is an issue. You cannot distribute the brain without drastically changing its functionality. Neuron impulses are actually quite slow (120m/s at the highest), so moving parts of the brain to different areas actually adds a non-trivial latency in communication which would drastically change the way the brain operates.
For an interesting data-point, we actually do quite a bit of processing in the spinal column itself, especially for walking. It's closer to the rest of the body, so the delays are lower. It turns out that if you bump your left hand into something while walking, your right foot will have adjusted its gait before your brain stem has even processed the impact!
As for the shape of your human, the real limiting factor is going to be useful redundancy. I can carry 100 eggs in a basket, but I don't have redundancy if I break them all at once. An extra femur is going to be... well... an extra bone in the leg. If something was breaking leg bones before, it now gets to break twice as many. You're likely going to have to do some substantial restructuring to make that redundancy useful. |
60,472 | <p>So I was building this city atop a mountain plateau with 1900 to 2300 meters high. That mountain rests on a small island, in the middle of the sea, near the continent.</p>
<p>More information about this city in here:
<a href="https://worldbuilding.stackexchange.com/questions/59356/water-supply-on-an-mountain-fortress">Water supply on an mountain fortress</a></p>
<p>What I would like to ask is... how far from the continent can I put this island for the city to still be visible from land?</p>
| [
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"text": "<p><a href=\"https://en.wikipedia.org/wiki/Horizon#Distance_to_the_horizon\" rel=\"nofollow noreferrer\">D... | 2016/11/04 | [
"https://worldbuilding.stackexchange.com/questions/60472",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/20681/"
] | So I was building this city atop a mountain plateau with 1900 to 2300 meters high. That mountain rests on a small island, in the middle of the sea, near the continent.
More information about this city in here:
[Water supply on an mountain fortress](https://worldbuilding.stackexchange.com/questions/59356/water-supply-on-an-mountain-fortress)
What I would like to ask is... how far from the continent can I put this island for the city to still be visible from land? | To expand a bit on @kingledion 's answer:
The angular resolution of the naked eye is about $\frac{\pi}{10800}$, or one arc minute.
You mentioned a civilisation on the level of ancient Rome, which had walls of around $10\left(m\right)$ high.
From basic trigonometry we know that $\tan{\frac{\pi}{10800}}=\frac{10\left(m\right)}{d\left(m\right)}$, so $d\left(m\right)=\frac{10\left(m\right)}{\tan{\frac{\pi}{10800}}}=34377.5\left(m\right)$, or more generally:
$$d\left(m\right)=\frac{h\left(m\right)}{\tan{\frac{\pi}{10800}}}=3437.75 h\left(m\right)$$
This means that on a clear day, the *Maximum* distance at which the average human eye can resolve an object of a $5\left(m\right)$ radius is around $34\left(km\right)$.
However, at this range, the walls would probably just look like a thin line of different colour from the rock.
The formula scales linearly, so if the walls could be made out properly with 4 "pixels", the distance would be about $8.6\left(km\right)$
This isn't all though, after all, you mention that the city is on a $~2000\left(m\right)$ high plateau, this changes the formula.
The angle at which we are looking is now $tan^{-1}{\left(s+\frac{h}{2}\right)}=\alpha=\tan^{-1}{\frac{2005\left(m\right)}{d\left(m\right)}}$
We need to multiply the distance with the cosine of this value. So:
$$d\left(m\right)=\cos{\left[\tan^{-1}{\frac{\left(s+\frac{h}{2}\right)\left(m\right)}{d\left(m\right)}}\right]}\frac{h\left(m\right)}{\tan{\frac{\pi}{10800}}}$$
Solving this numerically with *Mathematica*:
```
Solve[Cos[ArcTan[(s + h/2)/d]] h/Tan[Pi/10800] == d]
```
>
> `d -> 1/2 Sqrt[-h^2 - 4 h s - 4 s^2 + 4 h^2 Cot[\[Pi]/10800]^2]`
>
>
>
and
```
With[{s = 2000, h = 10},
Solve[Cos[ArcTan[(s + h/2)/d]] h/Tan[Pi/10800] == d]] // N
```
>
> `d -> 34318.9`
>
>
>
```
Plot[{d, Cos[ArcTan[2005/d]] 10/Tan[Pi/10800]}, {d, 0, 35000}]
```
[](https://i.stack.imgur.com/gkybS.png)
The distance for a variable height of the plateau (s) is givien by:
$$\sqrt{-25-10s-s^2+100\cot{\left(\frac{\pi}{10800}\right)}^2}$$
[](https://i.stack.imgur.com/lNnaz.png) |
60,867 | <blockquote>
<p>So, let's say that through a series of strange timey wimey events, I
accidentally jump-start several technological revolutions in the early
1800's. So, at any given time, technology is ~60 years ahead of where
it should be, sans nuclear weapons (nuclear power does exist though).
Now let's say that WWI and WWII don't happen. Now, let's also say
that, in 1930, America is provoked into a short but bloody war,
culminating in a months-long blockade and bombardment of the enemy’s
heavily fortified capital city. Beach landings are all but impossible,
due to a series of anti-ship weapons under the water. The city can't
perform an all out attack on the ships bombarding them, but they have
supplies and weapons delivered to them from the land. The Americans
can't get close enough to intercept the supply route, and this siege
has been going on for months. In the port in Baltimore, the frame is
being assembled for the largest ship ever built. "Super Dreadnought".
700 meters long, 3 nuclear reactors, and a retractable stabilization
pylon on each side. Armaments:</p>
<pre><code>10 31.5" guns
20 18" guns
20 16" guns
30 14" guns
40 3" AA guns
100 10" guns
300 .50 machine guns
</code></pre>
<p>It is decided that "nothing short of putting an entire battleship in the way could stop that damn supply
route". Then an idea is pitched: put an actual battleship in the way.
In particular, put the Super Dreadnought in the way. It's approved,
and constructed with 7 sets of massive caterpillar tracks. Each set
has one track directly under the ship, and one on either side. This
massive ship is now amphibious.</p>
</blockquote>
<p>Now, here are my questions:</p>
<ol>
<li>Is my proposed method of making this ship amphibious plausible?</li>
<li>If so, what would the the approximate top speed?</li>
<li>If not, what can I change to make it plausible?</li>
</ol>
| [
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"answer_id": 60870,
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"text": "<p>Generally speaking, this sort of approach has to be designed into a ship since day one. You need a very ... | 2016/11/10 | [
"https://worldbuilding.stackexchange.com/questions/60867",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/26206/"
] | >
> So, let's say that through a series of strange timey wimey events, I
> accidentally jump-start several technological revolutions in the early
> 1800's. So, at any given time, technology is ~60 years ahead of where
> it should be, sans nuclear weapons (nuclear power does exist though).
> Now let's say that WWI and WWII don't happen. Now, let's also say
> that, in 1930, America is provoked into a short but bloody war,
> culminating in a months-long blockade and bombardment of the enemy’s
> heavily fortified capital city. Beach landings are all but impossible,
> due to a series of anti-ship weapons under the water. The city can't
> perform an all out attack on the ships bombarding them, but they have
> supplies and weapons delivered to them from the land. The Americans
> can't get close enough to intercept the supply route, and this siege
> has been going on for months. In the port in Baltimore, the frame is
> being assembled for the largest ship ever built. "Super Dreadnought".
> 700 meters long, 3 nuclear reactors, and a retractable stabilization
> pylon on each side. Armaments:
>
>
>
> ```
> 10 31.5" guns
> 20 18" guns
> 20 16" guns
> 30 14" guns
> 40 3" AA guns
> 100 10" guns
> 300 .50 machine guns
>
> ```
>
> It is decided that "nothing short of putting an entire battleship in the way could stop that damn supply
> route". Then an idea is pitched: put an actual battleship in the way.
> In particular, put the Super Dreadnought in the way. It's approved,
> and constructed with 7 sets of massive caterpillar tracks. Each set
> has one track directly under the ship, and one on either side. This
> massive ship is now amphibious.
>
>
>
Now, here are my questions:
1. Is my proposed method of making this ship amphibious plausible?
2. If so, what would the the approximate top speed?
3. If not, what can I change to make it plausible? | In a rather weird way, H.G. Wells wrote about the possible future of tanks and pessimistically envisioned monstrous battleship sized machines capable of carrying huge batteries of guns and plowing the landscape before them due to the immense weight.
>
> What lies behind the Tank depends upon this fact; there is no definable upward limit of mass. Upon that I would lay all the stress possible, because everything turns upon that.
>
>
> You cannot make a land ironclad so big and heavy but that you cannot make a caterpillar track wide enough and strong enough to carry it forward. Tanks are quite possible that will carry twenty-inch or twenty-five inch guns, besides minor armament. Such Tanks may be undesirable; the production may exceed the industrial resources of any empire to produce; but there is no inherent impossibility in such things. There are not even the same limitations as to draught and docking accommodation that sets bounds to the size of battleships. It follows, therefore, as a necessary deduction that if the world's affairs are so left at the end of the war that the race of armaments continues, that Tank will develop steadily into a tremendous instrument of warfare, driven by engines of scores of thousands of horse-power, tracking on a track scores of hundreds of yards wide and weighing hundreds or thousands of tons. Nothing but a world agreement not to do so can prevent this logical development of the land ironclad. Such a structure will make wheel-ruts scores of feet deep; it will plough up, devastate and destroy the country it passes over altogether.
>
>
>
[](https://i.stack.imgur.com/Ludjc.jpg)
*Illustration from 1939*
Of course, being a "linear projection", it takes a basic idea and inflates it to rather absurd dimensions. Wells was no crank, however. He had actually predicted armoured fighting vehicles in a 1903 story "[The Land Ironclads](https://rads.stackoverflow.com/amzn/click/com/1406577138)" (technically, the Tripods from the [War of the Worlds](https://rads.stackoverflow.com/amzn/click/com/1505260795) were also AFV's), and was an enthusiastic supporter of the development of real tanks when they were developed by the British.
[](https://i.stack.imgur.com/uRHXC.jpg)
*A Land Ironclad*
And this trope has carried on in Science Fiction and games with ideas like "Bolo" AI driven tanks and the Ogre war-game.
However, once you re read the description of the Wellsian super tank, you see the issues. Engines with "scores of thousands of horsepower" are absurdly huge (especially with 1930 era technology) regardless of what your power source is. The bulk of the machine will be made up of engine bays and transmissions. Since the engines will not convert 100% of your energy into motion, you need some sort of radiating mechanism. A ship at sea can dump its heat into the ocean, but on land it becomes a bit more difficult. You might be looking at a cooling system similar in size to the massive cooling towers at a nuclear power station.
The next issue is the mechanical strength of the chassis. A ship is fully supported by the water it displaces, but your vehicle will have hundreds or thousands of separate stress points in the suspension and track system. The body will be similar to a bridge standing on pylons, so there will be sections cantilevered between suspension elements. The body will be subject to stresses in multiple directions since the ground isn't flat, and firing stresses will complicate matters even more. When you consider a modern torpedo kills a ship by exploding under the keel and creating a cavitation bubble, snapping the ship where it is no longer supported, then consider the same effect will occur when the vehicle will be subject to similar stresses when crossing a stream, valley or even sufficiently large ditch.
Finally, this thing will be a target. It will be moving slowly enough that everything from long range artillery and bomber aircraft to tank hunting teams with explosive charges will be assembled and sent into action long before this thing can get into range of its target. Your multi million dollar investment will be smoking ruins, quite possibly before you even hit the beach (the Captains of the [HMS Prince of Wales](https://infogalactic.com/info/HMS_Prince_of_Wales_(53)), [IJN Yamato](https://infogalactic.com/info/Japanese_battleship_Yamato) and the [Bismarck](https://infogalactic.com/info/German_battleship_Bismarck) can explain this more fully).
Given the parameters that you provided in the setup, it would be far more plausible for the attack to be made by carrier born bombers or even large seaplanes than to expend the time and energy needed to create the monstrosity you are describing.
[](https://i.stack.imgur.com/Q2J7l.png)
*[USS Saratoga](https://infogalactic.com/info/USS_Saratoga_(CV-3))* |
60,924 | <p>Let's say that I own a planet and I have the chance to set up rules before any human can move in. I want to make a law that would welcome anyone to the planet as long as they only speak the decided language.</p>
<p>It would mean doing anything needed to make sure nobody spoke any other language, even in a private place. The end goal would be to make the rest of the languages disappear and everyone would be able to understand each other.</p>
<p>Here are the rules I came up with to make it work:</p>
<ul>
<li>I wouldn't rule the planet for long. There could be any political system established as long as that rule would be inmutable.</li>
<li>It doesn't matter your level on that language. As long as you are trying to speak it you are welcome.</li>
<li>Any communication in and out of the planet would be forced to be on that language.</li>
<li>The language can evolve as long as any changes to it would be applied globally.</li>
</ul>
<p>Would forcing the new citizens and prosecuting anyone that tried to spoke a different language be justified for the better end?</p>
| [
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"text": "<p>No. Most of the bloodiest wars in human history are civil wars, where the people understand each othe... | 2016/11/10 | [
"https://worldbuilding.stackexchange.com/questions/60924",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/28570/"
] | Let's say that I own a planet and I have the chance to set up rules before any human can move in. I want to make a law that would welcome anyone to the planet as long as they only speak the decided language.
It would mean doing anything needed to make sure nobody spoke any other language, even in a private place. The end goal would be to make the rest of the languages disappear and everyone would be able to understand each other.
Here are the rules I came up with to make it work:
* I wouldn't rule the planet for long. There could be any political system established as long as that rule would be inmutable.
* It doesn't matter your level on that language. As long as you are trying to speak it you are welcome.
* Any communication in and out of the planet would be forced to be on that language.
* The language can evolve as long as any changes to it would be applied globally.
Would forcing the new citizens and prosecuting anyone that tried to spoke a different language be justified for the better end? | >
> *Would forcing the new citizens and prosecuting anyone that tried to spoke a different language be justified for the better end?*
>
>
>
No. The End Sucks. So Do The Middle and Beginning.
==================================================
It creates a privileged culture, suppresses others, leads to language stagnation, thought crime, and a police state.
This has been tried a number of times throughout history, [most notably Turkey](https://en.wikipedia.org/wiki/Atat%C3%BCrk%27s_Reforms) or the US forcing Native Americans and Australia forcing Aborigines to learn English. Usually it results in continuous cultural suppression. It establishes a dominant culture and suppresses the others.
An analogy is enforcing a dress code. The choices you make in what that code is and how its enforced says which culture and economic class gets preference, sets them at a higher standard of what is "proper", and selective enforcement can be used for harassment. For example, a "no hoodies" rule is clearly a way to target certain racial and economic classes, and deciding what is and is not a "hoodie" can be used to harass.
Here's the choices you need to make and how they lead to that end.
Which Language and Why?
-----------------------
I'm gonna use the US as an example to make this less abstract.
Which language do you choose? That might seem obvious, whatever language the most people already speak (English)... or do you go with one that's easy to learn (Spanish)? Maybe the pick the one with the most in common with other languages (... maybe Spanish again)? Or do you use the language that the most of your neighbors and trading partners speak (Mandarin)? Or do you make up a whole new language so everyone is equally hosed (Esperanto)?
Whatever you pick, it's going to be a continuing hassle.
Language As Privilege
---------------------
If you chose an existing language, existing speakers are now privileged.
If you create a new language, well-off people are now privileged because they have the free time and money to learn the new language, hire tutors, training programs, etc...
Let's say it's English. Existing English speakers don't have to do anything. They don't have to spend time, and money, for schooling. They can keep their existing jobs, in fact native speakers will be in high demand as everyone else tries to catch up. The industry of teaching English will expand creating more jobs for English speakers.
>
> *As long as you are trying to speak it you are welcome.*
>
>
>
This creates a linguistic, cultural, and economic privilege to immigration. You're welcome... so long as you either already speak the language, or have the money and free time to learn it.
Newcomers who are "trying" to speak the language remain at a disadvantage. Their native language is not just not spoken, it is *illegal*. How do they get a job? How do they read a contract? How do they read a manual?
This doesn't end.
Language As Culture
-------------------
The language you speak isn't just some interchangeable part. It is your culture and it even alters how you think. It's your written and oral histories, parables, stories, songs, expressions, and vocabulary. All these things are made illegal. It wipes out other cultures.
Learning Material As Cultural Indoctrination
--------------------------------------------
Until recently, the most translated book was the Bible. Missionaries were happy to teach you how to read... but it was going to be a Bible.
Now we're not quite as blunt about our indoctrination, but when you're running an entire society through a forced language re-education program the choice of reading material, pictures, phrasing, vocabulary, and grammar will be indoctrinate a certain world view whether you mean it or not.
Even something as innocent as your choice of noun to use when teaching basic grammar can codify what is normal and what is not.
```
I like to eat apples.
People eat apples.
Apples are good for you.
They bought three apples.
```
[](https://i.stack.imgur.com/onSGF.jpg)
Translation As Suppression
--------------------------
Anyone who says "just translate them" has never done translation. Meaning is lost between languages, especially for songs. Translation is always a trade off between the literal meaning and the metaphorical meaning. How do you translate "stop, you're killing me"?
You can't translate everything, there simply aren't enough translators and money to pay them. The selection of what gets translated and how it gets translated becomes cultural suppression.
And if there aren't a lot of translators for your language... oh well. It disappears.
Translation As Rewriting Cultural History
-----------------------------------------
Translators have a lot of power to subtly shape our understanding of history when the original documents are in another language. Not just in the choice of what gets translated, but the choices they make in doing that translation.
Perhaps the most famous example is the [bowdlerization](https://en.wikipedia.org/wiki/Thomas_Bowdler) of classic texts such as Shakespeare, Ancient Greek and Roman writers, and the Bible. Every language has ambiguity through idioms and context.
Embarrassing historical documents can be subtly reworded to make them seem innocuous. [Homosexuality, sex, dirty jokes... anything considered "vulgar"](http://www.toptenz.net/top-10-reasons-ancient-rome-was-a-perverts-paradise.php) were obscured in popular translations of Greek and Roman texts to prop up the idea that this was a prim and proper golden age of humanity and that our morals have slipped. Have a look into the writings of [Martial](https://en.wikipedia.org/wiki/Martial) and [Catullus](https://en.wikipedia.org/wiki/Catullus) or watch an uncensored version of [Lysistrata](https://en.wikipedia.org/wiki/Lysistrata).
For more on this read [The Harlot by the Side of the Road: Forbidden Tales of the Bible](http://rads.stackoverflow.com/amzn/click/0345418824) which puts racy Bible stories in plain English and reveals what they're really talking about.
The End Is Bad.
===============
The end doesn't justify the means because enforcing cultural laws leads you to bad outcomes.
Option 1: Surveillance State
----------------------------
How do you enforce the language law? How do you check that people aren't speaking and writing their own languages? To enforce this requires a surveillance state.
You need to spy on what people are saying, and what people are writing. This means no strong encryption. This means neighbors turning in neighbors. This means crackdowns on cultural displays like something as innocuous as showing a subtitled movie or displaying an old, untranslated play.
Option 2: Selective Enforcement As Cultural Domination
------------------------------------------------------
In this option, you count on normal law enforcement to enforce the language law. For otherwise innocuous, culturally driven laws like this there is a great urge to use selective enforcement as police harassment of groups they don't like. Want to harass someone? Accuse them of "speaking foreign".
Establishing One Language/Culture As "Better"
---------------------------------------------
As with dress codes, choosing a single language signals that one language is "better" than the others. Again, doesn't matter what your intent is, people will use this as an excuse or grow up with this lesson.
Suppressing Knowledge Of Other Cultures
---------------------------------------
Since nobody is allowed to practice other languages, how can they ever really understand other cultures? People who only speak one language get a very selective and limited view of the world.
If you travel to a foreign country, you can only speak and read things which are in your language. Everything else is out of bounds, or you need a phrase book, or hire a translator (more economic privilege). This will keep most people to "tourist" areas and they will get a very selected and limited view.
This will twist your people's understanding of the world. Their limited view through their own lens will encourage xenophobia.
Language Police, Language Stagnation
------------------------------------
>
> *The language can evolve as long as any changes to it would be applied globally.*
>
>
>
Language evolves and changes. But in your world these changes have to first be approved before they can be legally used. Since they can't be used legally, the population can't first play around with them to see what works. Some council of Language Police decides what new words the people need (or, oh god, the people vote on what new words are ok?).
It's the ultimate in [Linguistic prescription](https://en.wikipedia.org/wiki/Linguistic_prescription). At best this promotes cultural stagnation as the language is not allowed to naturally change and adapt. For example, as much as some people don't like it, verbing nouns is really useful.
At worst, constant tinkering with the language creates continual, punctuated, and awkward changes that everyone needs to relearn.
As an example, the speeches of [Atatürk](https://en.wikipedia.org/wiki/Mustafa_Kemal_Atat%C3%BCrk) in the 1920s, leader of the Turkish language reforms, cannot be understood by most modern Turks.
Cultural Suppression
--------------------
What words, spellings, and phrases the Language Police decide are legal will be informed by what cultural, economic, and political things they are associated with. As a simple example, I was told growing up that "ain't" ain't a word, even though the meaning is clear, because it's considered lower class.
Another example is "sodomy". Want to suppress certain sexual acts through language? Roll them all into one word, now it's really easy to over-generalize, and difficult to discuss in detail. Then attach to them a word that says "remember that time God smote a whole city for being perverts?"
Similar examples come from dress codes. Not just things like hoodie bans, but here's a list of banned items from a bar using "safety" as cultural suppression.
[](https://i.stack.imgur.com/atE2b.jpg)
Most of can be justified with safety, but others are simply targeting certain cultures they don't want around. Pacifiers, glowsticks, stuffed animals, and candy bracelets are stereotypical of raver culture. Others like "no chapstick" might be some sort of attempt to stop secret drug use?
Language restrictions can be used similarly.
Thought Crime
-------------
What if there simply isn't a word to express what you want to say? Or an idea that you came up with? How many words for emotions and thoughts and actions have we come up with in the past ten years of ubiquitous Internet use and loan words alone? Mansplaining; lol; owned; email; to email; code monkey; texting; sexting; burner account; DOXing.... off the top of my head. Sure, there are similar words and phrases, but they don't say it quite the same way.
An example of vocabulary shaping thinking is the German loanword schadenfreude. We have sadism and masochism, a relationship of pain and pleasure between two parties... but schadenfreude is the relationship of a third and otherwise unrelated party. Sure, you can express this idea without introducing a new word, but a word neatly packages an idea for transmission to others.
Must we use increasingly awkward and literal phrases? Hey, are you going to the musical show which is a darker offshoot to the backlash to the cultural and economic stagnation represented by rock and roll tonight? A goth-punk show. Do we always have to point out that L.A.S.E.R. is an acronym for Light Amplification by Stimulated Emission of Radiation?
What about poetry and music? Will an artist be prosecuted for using a word in a non-approved way?
---
I could go on, but this is turning into a dissertation on cultural identity and suppression. I think you get the idea. |
62,948 | <p><a href="https://i.stack.imgur.com/6u87K.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/6u87K.jpg" alt="enter image description here"></a></p>
<ol>
<li>If there's a habitable planet that orbits two suns like the above
orbital route, what would possibly occur on that planet?</li>
<li>Would it have two yearly seasonal cycle (compare to earth)?</li>
<li>Would it be possible that there's some months where there would be
no night time on every part of the planet?</li>
<li>What other things resulting from the effect on day, night, and
seasonal cycles can be experienced if we lived on that planet?</li>
</ol>
| [
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"answer_id": 62951,
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"text": "<p>The biggest shock would be the period in the center of the figure eight where there would be winter--or som... | 2016/11/30 | [
"https://worldbuilding.stackexchange.com/questions/62948",
"https://worldbuilding.stackexchange.com",
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1. If there's a habitable planet that orbits two suns like the above
orbital route, what would possibly occur on that planet?
2. Would it have two yearly seasonal cycle (compare to earth)?
3. Would it be possible that there's some months where there would be
no night time on every part of the planet?
4. What other things resulting from the effect on day, night, and
seasonal cycles can be experienced if we lived on that planet? | I'm going to attack this with math. First off, I am not going to make any assumptions about what orbits might be stable. That is something we can check with an orbit simulator like rebound, as I did in [this question](https://worldbuilding.stackexchange.com/questions/23452/can-you-add-a-mini-moon-to-earth/59917#59917). Instead, I will assume there is a stable orbit around two suns of equal mass and luminosity. The orbital profile will be a perfect circle (0 eccentricity orbit) at 1 AU for 3/4 of a revolution around each sun and then a straight line connecting it to the next sun.
Determine the orbits
====================
Since this is an ugly piecewise function, and I am solving using a computer, I am defining it in python as such:
```
def f(t):
if t < 3/2*pi:
return sin(t-pi/4)+sqrt(2), cos(t-pi/4)
if t < 3/2 * pi + 2:
r = t - 3/2*pi
return sqrt(2)/2-r/sqrt(2), -sqrt(2)/2+r/sqrt(2)
if t < 3*pi + 2:
r = t - 3/2*pi - 2
return sin(pi/4-r)-sqrt(2), cos(pi/4-r)
if t < 3*pi + 4:
r = t - 3*pi - 2
return sqrt(2)/-2+r/sqrt(2), -sqrt(2)/2 + r/sqrt(2)
```
[](https://i.stack.imgur.com/02Azl.png)
The red dots are the two suns. The green dot is our arbitrary time = 0 for the next part; the planet starts moving clockwise around the sun on the right. So far so good, now let us calculate distance from each sun, and plot that as a function of time.
Determine the distance from each sun
====================================
Since I'm already using the computer, and I know the sun's coordinates, ($-\sqrt{2}, 0$) and ($\sqrt{2}, 0$), I will just calculate numerically using this code:
```
def dist_1(coord):
x, y = coord
return sqrt((x - sqrt(2))**2 + y**2)
def dist_2(coord):
x, y = coord
return sqrt((x + sqrt(2))**2 + y**2)
```
[](https://i.stack.imgur.com/pg6ot.png)
Where dist\_1 is from the right star and is in blue, and dist\_2 is the left star and is in red. I scaled the time factor to 365 days in a year cause I'm a geocentric kind of dude, but I could use any scale factor. If the planet was moving at the velocity of Earth it would take 1342 days to complete this year, fyi.
Determine enegy recieved
========================
Solar energy drops off as 1/r$^2$, so solar energy received from each sun is 0.905 earth units divided by the distance to each sun. The .905 is a scaling factor to ensure that total solar energy recieved by this planet averages to 1 unit. So lets plot those two, and a new black line for the net total solar energy.
[](https://i.stack.imgur.com/tzySb.png)
Add seasons
===========
Ah, glorious seasons. Lets say we have an earth-like 23.5 degree axial tilt. How will that affect us? Depends on how we orient the tilt. I will arbitrarily declare that the Northern hemisphere is fully tilted towards the two stars when the planet is at the far right point of its orbital trajectory at point ($\sqrt{2}+1$, 0).
I calculate the effect of tilt both at the equator and on a point 45 degrees N. At summer solstice (at the point mentioned above) $cos(45-23.5) = 0.930$ of equatorial sunlight, and at winter solstice it will get $cos(45+23.5) = 0.367$ of equatorial sunlight. The angle to either star in our coordinate system is calculated from $\text{arctan}(\frac{y}{x})$ where x and y are the coordinate distances from the star. The cosine of the angle to the sun in radians, which is the proportion of the axial tilt that the planet is currently experiencing, can be expressed as:
```
def angle_1(coord):
x, y = coord
if x + sqrt(2) < 0:
return -1* cos(atan(y/(x+sqrt(2))))
return cos(atan(y/(x+sqrt(2))))
```
We will multiply that by the axial tilt, add it to the latitude, and calculate the addition or reduction in light energy by season.
So here are two graphs showing how the seasons will work. The first graph is for the equator of our planet, compared with earth. The black line is total energy recieved by this planet (earth would be just a straight line at one, assuming a perfectly circular orbit), red is the relative insolation at this planet's equator, and green is relative insolation at our equator.
[](https://i.stack.imgur.com/nPrgO.png)
The second graph is the same, except for a point 45 degrees N. So black is the same as above, red is insolation of the other planet, and green is insolation of earth.
[](https://i.stack.imgur.com/4V9lW.png)
And remember, I scaled this planet so its day is as long as an Earth day. If, for example, you set the year to be the 1342 earth days for velocity matching, then the first red-hump summer for the other planet would last as long as a summer here on earth.
Well hope this is what you were looking for; I have all the code saved if you want me to post any more of it, or throw up a graph for a different latitude.
---
Edit:
As requested here is a 45 degrees N profile for a 750 day year compared to what Earth would be doing in that approximately 2 year period.
[](https://i.stack.imgur.com/wxQT8.png)
As far as the max insolation; the max value for Earth's summer is 0.917, which represents 91.7% of max insolation at the equator. For our mystery planet, the number is 0.830; this is off by a factor of 0.905, which you may recall is the scaling factor by which we had to reduce these other suns to get Earth-like total year-round solar insolation. So that makes sense. On the winter side, however, the numbers are 0.366 for Earth and 0.354 for the other planet. Those should show the same 0.905 ratio. I don't know if this is an error in the code or just somethign I'm not understanding, but I'll take a look.
Incidentally, darkest winter at 45 N is not while the planet is between the two stars. This is the coolest time at the equator, the sunlight dips down to about 80% of max; that is like May or July in the mid-latitudes. But at 45 N, you are about equidistant from the two stars, and always getting 'summer' from one of the two. So that mitigates the wintery-ness. Darkest winter is when you are tilted away from both suns on the far left of the orbit plot. |
63,118 | <p>A civilization has a "magic" computer with memory and processing capacities far beyond what our physics says is possible. They decide to run a massive simulation of <a href="https://en.wikipedia.org/wiki/Conway's_Game_of_Life" rel="noreferrer">Conway's Game of Life</a> with a random "big bang" initial state. The goal is to see if, given enough simulated time steps and a large enough random initial canvas, intelligent life will evolve.</p>
<p>But here's the question: even if intelligent life did evolve, how would the simulator civilization know it was there, when all they (or rather, their algorithms) can see is a semi-chaotic pattern of blinking dots?</p>
<p><strong>Edit:</strong> The "life" bit isn't that important; "intelligent non-life" would also work. And the "signs of intelligence" need not be definitive. What sorts of things would scientists (and philosophers) consider when trying to decide if intelligence had arisen? What sorts of debates might they have?</p>
<hr>
<p><strong>Philosophical digression</strong> (trying to provide a substitute for the best of the comments <a href="http://chat.stackexchange.com/rooms/49563/discussion-on-question-by-charles-staats-how-to-tell-if-intelligent-life-has-evo">moved to chat</a>)</p>
<p><em>Skeptic:</em> What is life? What is intelligence? If you will not define these two, your question is unanswerable. [line quoted from user Molot]</p>
<p><em>Enthusiast:</em> You don't have to define intelligent life to search for signs of it in astronomy. Why should this be any different?</p>
<p><em>OP:</em> Both points are good. Consider why you think other people have minds (as opposed to being mindless automatons). The most relevant response here is that minds have explanatory power: there are certain actions people take -- such as having discussions about the nature of minds -- that would be absurd if they did not, in fact, have minds. If we were searching for alien intelligence, we would look for signs like buildings or <a href="https://en.wikipedia.org/wiki/Arecibo_message" rel="noreferrer">radio message patterns</a> that can most easily be explained by the existence of an alien civilization. In the same way, we can look for patterns in the Game of Life that -- while not violating the rules -- are virtually impossible to imagine without deliberate design.</p>
<p><em>Skeptic:</em> Where to begin? First of all, postulating intelligence cannot possibly add any explanatory power to what we already have. The Game of Life is deterministic and we know all the rules.</p>
<p>Second, you can't assume intelligence just because you have an elaborate mechanism for accomplishing a purpose. Many things (like eyes) appear to have been designed for a specific purpose, but were in fact produced by natural selection without any actual intent.</p>
<p><em>OP:</em> Let's take these points one at a time.</p>
<p><strong>Explanatory power in a deterministic system:</strong> Consider the laws of statistical mechanics -- most notably entropy. Technically speaking, if you know a physical (Newtonian) system perfectly, the laws of statistical mechanics are completely unnecessary: you can predict exactly where every particle will be after any specified amount of time. But in practice, applying statistical mechanics will allow you to make certain predictions much more cheaply, such as the average velocity of the particles in one particular spot. So statistical mechanics has explanatory power even though in this instance it adds no information.</p>
<p><em>Enthusiast:</em> I think your criteria for "explanatory power" is still too stringent. Many explanations have no predictive power whatsoever, even in terms of making cheaper predictions. For instance, if (in real life) we received a radio signal that was the first twenty primes repeated over and over, we would probably postulate an intelligent source even though that explanation doesn't really help us predict anything more cheaply.</p>
<p><em>OP:</em> That's true enough. Cheaper prediction is a nice illustration of explanatory power in the face of determinism, but it's not the whole concept. Like many philosophical ideas, "explanatory power" is precise enough to be useful but vague enough that no two people have exactly the same definition.</p>
<p><em>Skeptic:</em> How exactly is that useful?</p>
<p><em>OP:</em> Let's just agree to disagree on the usefulness of imperfectly defined terms. To be considerate of our readers' time--</p>
<p><em>Skeptic</em> [aside] <em>That</em> ship has sailed.</p>
<p><em>OP:</em> --let's move on to your second point from earlier.</p>
<p><strong>Designed technology vs evolved organ:</strong> Let's remind ourselves of the earlier exchange:</p>
<blockquote>
<p><em>OP:</em> We can look for patterns in the Game of Life that -- while not violating the rules -- are virtually impossible to imagine without deliberate design.</p>
<p><em>Skeptic:</em> You can't assume intelligence just because you have an elaborate mechanism for accomplishing a purpose. Many things (like eyes) appear to have been designed for a specific purpose, but were in fact produced by natural selection without any actual intent.</p>
</blockquote>
<p>That's fair enough. In our own world, certain kinds of patterns -- such as <a href="https://worldbuilding.stackexchange.com/a/2489/16106">projectiles</a> or <a href="https://worldbuilding.stackexchange.com/q/20664/16106">wheels</a> -- seem to be exclusively the domain of designed technology rather than evolution. But even in our own universe these distinctions are hardly intuitive, and spotting them in a completely alien universe like Conway's Game of Life would be all but impossible. Perhaps radial propagation of information might be a sign of designed technology? (In the Game of Life, diagonal, vertical, and horizontal movement are much more natural than movement at any other angle; propagating information in all directions at the same rate could be something highly desirable that would never show up "on its own" (without intent), even through evolution. But who knows?)</p>
<p>Another way to think about it is that artifacts designed with intent tend to be good at things that have nothing to do with their own survival. For instance, if we found something in a simulation that appeared to be a program for playing the board game Go exceptionally well, it would certainly be worth publishing as a "sign of intelligence" whether or not the program itself were considered intelligent.</p>
<p>Another thing to look for would be advanced communication -- especially concerning mathematics, since that is universal. But it's also possible that things that are difficult to compute in our universe, typically requiring advanced intelligence, can be done comparatively simply in a GoL universe, and vice versa.</p>
<p><em>Enthusiast:</em> Perhaps we (or our fictional protagonists) could scan the GoL universe for patterns that obey differential equations! Clearly no differential equations could show up in such a universe without deliberate intent.</p>
<p><em>OP:</em> Maybe. But differential equations are so powerful I have a feeling they would work their way in just fine without intelligent help.</p>
<p>Anyway, perhaps if we <a href="https://worldbuilding.stackexchange.com/q/63118/16106">ask on WorldBuilders.SE</a> they'll have some suggestions.</p>
| [
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"text": "<p>I'm no scientist but as I understand it there are certain things that you can look for that are otherw... | 2016/12/02 | [
"https://worldbuilding.stackexchange.com/questions/63118",
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] | A civilization has a "magic" computer with memory and processing capacities far beyond what our physics says is possible. They decide to run a massive simulation of [Conway's Game of Life](https://en.wikipedia.org/wiki/Conway's_Game_of_Life) with a random "big bang" initial state. The goal is to see if, given enough simulated time steps and a large enough random initial canvas, intelligent life will evolve.
But here's the question: even if intelligent life did evolve, how would the simulator civilization know it was there, when all they (or rather, their algorithms) can see is a semi-chaotic pattern of blinking dots?
**Edit:** The "life" bit isn't that important; "intelligent non-life" would also work. And the "signs of intelligence" need not be definitive. What sorts of things would scientists (and philosophers) consider when trying to decide if intelligence had arisen? What sorts of debates might they have?
---
**Philosophical digression** (trying to provide a substitute for the best of the comments [moved to chat](http://chat.stackexchange.com/rooms/49563/discussion-on-question-by-charles-staats-how-to-tell-if-intelligent-life-has-evo))
*Skeptic:* What is life? What is intelligence? If you will not define these two, your question is unanswerable. [line quoted from user Molot]
*Enthusiast:* You don't have to define intelligent life to search for signs of it in astronomy. Why should this be any different?
*OP:* Both points are good. Consider why you think other people have minds (as opposed to being mindless automatons). The most relevant response here is that minds have explanatory power: there are certain actions people take -- such as having discussions about the nature of minds -- that would be absurd if they did not, in fact, have minds. If we were searching for alien intelligence, we would look for signs like buildings or [radio message patterns](https://en.wikipedia.org/wiki/Arecibo_message) that can most easily be explained by the existence of an alien civilization. In the same way, we can look for patterns in the Game of Life that -- while not violating the rules -- are virtually impossible to imagine without deliberate design.
*Skeptic:* Where to begin? First of all, postulating intelligence cannot possibly add any explanatory power to what we already have. The Game of Life is deterministic and we know all the rules.
Second, you can't assume intelligence just because you have an elaborate mechanism for accomplishing a purpose. Many things (like eyes) appear to have been designed for a specific purpose, but were in fact produced by natural selection without any actual intent.
*OP:* Let's take these points one at a time.
**Explanatory power in a deterministic system:** Consider the laws of statistical mechanics -- most notably entropy. Technically speaking, if you know a physical (Newtonian) system perfectly, the laws of statistical mechanics are completely unnecessary: you can predict exactly where every particle will be after any specified amount of time. But in practice, applying statistical mechanics will allow you to make certain predictions much more cheaply, such as the average velocity of the particles in one particular spot. So statistical mechanics has explanatory power even though in this instance it adds no information.
*Enthusiast:* I think your criteria for "explanatory power" is still too stringent. Many explanations have no predictive power whatsoever, even in terms of making cheaper predictions. For instance, if (in real life) we received a radio signal that was the first twenty primes repeated over and over, we would probably postulate an intelligent source even though that explanation doesn't really help us predict anything more cheaply.
*OP:* That's true enough. Cheaper prediction is a nice illustration of explanatory power in the face of determinism, but it's not the whole concept. Like many philosophical ideas, "explanatory power" is precise enough to be useful but vague enough that no two people have exactly the same definition.
*Skeptic:* How exactly is that useful?
*OP:* Let's just agree to disagree on the usefulness of imperfectly defined terms. To be considerate of our readers' time--
*Skeptic* [aside] *That* ship has sailed.
*OP:* --let's move on to your second point from earlier.
**Designed technology vs evolved organ:** Let's remind ourselves of the earlier exchange:
>
> *OP:* We can look for patterns in the Game of Life that -- while not violating the rules -- are virtually impossible to imagine without deliberate design.
>
>
> *Skeptic:* You can't assume intelligence just because you have an elaborate mechanism for accomplishing a purpose. Many things (like eyes) appear to have been designed for a specific purpose, but were in fact produced by natural selection without any actual intent.
>
>
>
That's fair enough. In our own world, certain kinds of patterns -- such as [projectiles](https://worldbuilding.stackexchange.com/a/2489/16106) or [wheels](https://worldbuilding.stackexchange.com/q/20664/16106) -- seem to be exclusively the domain of designed technology rather than evolution. But even in our own universe these distinctions are hardly intuitive, and spotting them in a completely alien universe like Conway's Game of Life would be all but impossible. Perhaps radial propagation of information might be a sign of designed technology? (In the Game of Life, diagonal, vertical, and horizontal movement are much more natural than movement at any other angle; propagating information in all directions at the same rate could be something highly desirable that would never show up "on its own" (without intent), even through evolution. But who knows?)
Another way to think about it is that artifacts designed with intent tend to be good at things that have nothing to do with their own survival. For instance, if we found something in a simulation that appeared to be a program for playing the board game Go exceptionally well, it would certainly be worth publishing as a "sign of intelligence" whether or not the program itself were considered intelligent.
Another thing to look for would be advanced communication -- especially concerning mathematics, since that is universal. But it's also possible that things that are difficult to compute in our universe, typically requiring advanced intelligence, can be done comparatively simply in a GoL universe, and vice versa.
*Enthusiast:* Perhaps we (or our fictional protagonists) could scan the GoL universe for patterns that obey differential equations! Clearly no differential equations could show up in such a universe without deliberate intent.
*OP:* Maybe. But differential equations are so powerful I have a feeling they would work their way in just fine without intelligent help.
Anyway, perhaps if we [ask on WorldBuilders.SE](https://worldbuilding.stackexchange.com/q/63118/16106) they'll have some suggestions. | With a large enough canvas of random data and enough cycles, intelligent life would evolve, assuming the Chuch-Turing thesis. Even weaker than that, assuming the universe is no more than non-deterministic.
Rough proof:
Conway's game of life is a Turing-complete game. You can create a general purpose computer in it. This computer may require a large initial state and be fragile and slow, but that just increases the size of the initial seed and cycle time before it can exist.
This computer is magical, so it can handle both of those issues.
In fact, you can have an unbounded number of such computers, running an unbounded number of different programs.
Assuming the Church-Turing thesis, at least one such program is intelligent.
Assuming the universe is no more than non-deterministic, a NDTM can be simulated in a TM, and a NDTM can thus describe the universe.
So given enough space and time and uniformly random initial states, somewhere in the infinite field there will be a turing machine that proceeds to simulate the evolution of every possible universe from an initial big bang with physics like ours.
One of these simulated universes would be our universe (without the magical computer, naturally).
Our universe appears to contain intelligent life.
So that is proof of existence. Now, we should examine what it would take to *find* this intelligent life.
The Conway's game of life doesn't *directly* contain it. Rather, it contains a pattern of life that can be interpreted as a computer (actually, unbounded numbers of such patterns, most of which are short lived due to flaws), which simulates a non-determinstic computer, which proceeds to exhastively simulate entire families of universes.
No human being or non-magical computer could, if someone pointed out the section of the system that was doing this computation, even interpret it or confirm if that was indeed the section in question. The parts of this machine's state would be literally larger than the entire universe's data capacity. We couldn't even *look* at the part in question.
It is so slow that the number of cycles required to describe even the merest fraction of a fraction of a fraction of a ... of a fraction of a ... of a fraction of a fraction of a second of the universe might be a number too large to express in this universe.
But that was just an existence proof. In theory, a much smaller system could actually house inteligence.
We can look at our universe. One of the possible explanations for our physics is that we are experiencing an inverted platonic wall of shadows. Our physics actually plays out on a 2+1 dimensional boundary of our universe, with the 3+1 dimensional interior of the space being a hologram "
"projected" by it. One of the motivations behind this possibility is that there appears to be an information limit in our universe proportional not to volume, but to the surface area of a region!
Physicists have created mathematics for toy universes that match this pattern, where there is a N dimensional physics system with a N-1 dimensional system that holographically determines the behavior of the N dimensional system.
Such a technique might easily be the easiest way for conways game of life to create a complex enough universe for evolution to occur in. So the 2+1 dimensional game of life might generete a holographic universe where the "interior" perspective of the intelligent beings does not correspond to the 2+1 dimensional "underlying system" that generates the hologram.
Stepping back again, even if that doesn't happen and the resulting intelligences do end up living in flatland, they might exist on ridiculous scales. The equivalent to a "cell" of our universe is the Planck length, or a Planck patch.
This is about 10^-35 m, or 10^-20 times the size of a Proton.
A proton is about 10^-15 m in size. The observable universe is about 10^26 m.
```
-35 -- Planck scale
-15 -- Proton scale
-10 -- Atomic scale
1 -- our scale
7 -- planetary scale
14 -- Solar system scale
20 -- Galactic scale
26 -- Universe scale
```
If we take jumps of a factor of 10 million per step, we get roughly:
```
-5 -- Planck scale
-4 -- ???
-3 -- ???
-2 -- Proton scale
-1 -- Atomic scale
0 -- our scale
1 -- planetary scale
2 -- Solar system scale
3 -- Galactic scale
4 -- Universe scale
```
The "cell size" of our universe is ridiculously far away from our scale. Atoms are roughly half way from that to the entire universe.
If we assume this is typical, then even in the regions where there is intelligence, figuring out a reasonable model of **physics** that they are experiencing so far away from the rules of Conway's life would be beyond our current skills.
They would no more exprience the rules of Conway's cells that we notice the rules of string harmonics when we throw a baseball. |
63,222 | <p>Assuming a technology is developed that allows people to either eliminate the need to sleep or study/work subconsciously during their regular sleep cycle, what kind of effect would this have on the amount of time it takes to finish your classical education? Could someone finish college and earn multiple phDs by the time they're eighteen if they had an extra 4-8 hours a day to study? I'm writing a bit of a throwaway bit of worldbuilding and wanted to know if this seemed unrealistic but now I'm honestly very curious about the impact of future technologies on education and learning.</p>
| [
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"text": "<h2>Brain development still takes time.</h2>\n\n<p>If you effectively use sleep to \"double up\" on school tim... | 2016/12/03 | [
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] | Assuming a technology is developed that allows people to either eliminate the need to sleep or study/work subconsciously during their regular sleep cycle, what kind of effect would this have on the amount of time it takes to finish your classical education? Could someone finish college and earn multiple phDs by the time they're eighteen if they had an extra 4-8 hours a day to study? I'm writing a bit of a throwaway bit of worldbuilding and wanted to know if this seemed unrealistic but now I'm honestly very curious about the impact of future technologies on education and learning. | Brain development still takes time.
-----------------------------------
If you effectively use sleep to "double up" on school time, handwaving the mechanism that allows this, and do so just during the school year - of course you will save some time. This method probably will allow for somewhat faster graduations.
But time is not the only limiting factor here: there's **brain development** to consider. If you give a six-year old a normal curriculum, but double the pace (assuming they can keep up with "sleep-learning" which is a whole different discussion), the 12 upcoming years of high school education will be finished in 6 years - at age 12.
If you try to teach a twelve year-old pre-calc, they will not just fail because of a lack of prior knowledge - to some extent, they will fail because of development. **Even if you increase the learning speed,** the brain will grow at about the same rate - there is no evidence to suggest a twelve year-old who does twice the work will have the brain of an eighteen year-old, which encompasses creativity, reasoning, and a host of other things that we only know possible at certain ages.
```
┌───────┬──────────────────┐
│ Age │ Work age level │
├───────┼──────────────────┤
│ 5-6 │ 5-7 │
│ 6-7 │ 7-8 │
│ 7-8 │ 9-10 │
│ 8-9 │ 11-12 │
│ 9-10 │ 13-14 │
│ 11-12 │ 15-16 │
│ 12-13 │ 17-18 │
└───────┴──────────────────┘
```
**Additionally,** you will be graduating people without developed social skills, few long-term memories (a consequence of taking up sleep time), and weaker physical builds - who may not be fit to drive or work. |
63,235 | <p>Santa keeps his elves under horrid, appalling conditions. Working everyday of the year for little pay in the freezing cold of the North Pole. But just how many elves does he need?</p>
<p>How many elves would it take to build enough toys for 2+ billion boys and girls across the world?</p>
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"text": "<p>You have to make some assumptions, so I'll answer more generally and you can plug in other numbers if you think... | 2016/12/03 | [
"https://worldbuilding.stackexchange.com/questions/63235",
"https://worldbuilding.stackexchange.com",
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] | Santa keeps his elves under horrid, appalling conditions. Working everyday of the year for little pay in the freezing cold of the North Pole. But just how many elves does he need?
How many elves would it take to build enough toys for 2+ billion boys and girls across the world? | You have to make some assumptions, so I'll answer more generally and you can plug in other numbers if you think my assumptions are off.
The number of elves required is given by
$$
C T \over D H R
$$
```
Where
C = Number of children in the world
T = Number of toys for each child
D = Annual days of work for elves
H = Hours in an elf workday
R = Toymaking rate in toys per hour
```
If you assume 2 billion children, 1 toy each, 364 workdays (Christmas day through the following December 23rd - then packing the sleigh on Christmas Eve), 16 hour days (Elven sweatshop!), and each elf can make 4 toys per hour, you need around 85,851 elves. That's quite a workshop.
This is only the set of elves required to make the toys. They'll need support staff too. Making food for 85k+ elves, cleaning and maintenance, procuring all of the materials for toy-making, quality control, and other functions could easily add another 50+% to the base number. |
63,698 | <p>Imagine two groups of people exploring the same location, but at different times. For convenience, think of the group exploring first as the "ancestors" and the group exploring later as the "descendants." It is easy to invent ways for the ancestors to affect the descendants. For example, they leave treasure buried and a map to find the spot in an urn. How can the exploration decisions the descendants make "matter" for the ancestors? This relevance could be figurative, narrative, or even silly. Not necessarily physical cause-and-effect. I would prefer to avoid traditional sci-fi time travel, with its commensurate split time-line paradoxes.</p>
| [
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"text": "<h1>Don't do what we did</h1>\n\n<p>I don't know what your technology or magic level is going to be, but t... | 2016/12/07 | [
"https://worldbuilding.stackexchange.com/questions/63698",
"https://worldbuilding.stackexchange.com",
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] | Imagine two groups of people exploring the same location, but at different times. For convenience, think of the group exploring first as the "ancestors" and the group exploring later as the "descendants." It is easy to invent ways for the ancestors to affect the descendants. For example, they leave treasure buried and a map to find the spot in an urn. How can the exploration decisions the descendants make "matter" for the ancestors? This relevance could be figurative, narrative, or even silly. Not necessarily physical cause-and-effect. I would prefer to avoid traditional sci-fi time travel, with its commensurate split time-line paradoxes. | Nothing impossible may happen.
In the C and C++ programming languages, there's such a thing called undefined behavior, where basically if the program performs certain illegal actions, it goes in an invalid state. Notice I said if, not when. The program is invalid *after*, *during* and even *before* the action that invoked undefined behavior. In other words, if your program performs a certain illegal action at some point, it's not invalid after that action, it's invalid for its entire execution. A compiler is free to assume that undefined behavior *never happens* and it can transform the implementation of the entire program, including parts that come before the illegal action, based on that assumption. If undefined behavior is actually invoked, the program may observe paradoxes.
This is a very real effect, happening right now in the world, with current technology. For example, an action on a specific variable (called a "pointer") is invalid if the variable contains a specific value ("null"). Consider this short snippet:
```
if (ptr == NULL) {
some_action();
} else {
some_other_action();
}
action_that_assumes_ptr_is_not_null(ptr);
```
In this example, `some_action()` may never be included in the program at all, even if `ptr` can sometimes be equal to `NULL`. Why? Because afterwards, an action is executed unconditionally and that action will put the entire program in an invalid state if `ptr` is `NULL`. In other words, as far as the compiler is concerned, `ptr` cannot be `NULL` in a valid program, so only `some_other_action()` can exist in a valid program. The above program could be transformed by the compiler into this:
```
some_other_action();
action_that_assumes_ptr_is_not_null(ptr);
```
As you can see, an action that is supposed to take place *later* will disable a choice (the `if` construct) that was supposed to take place *sooner*. Of course, all of this is possible because there is an entity (the compiler) that analyzes the program statically, i.e. outside that program's execution. In other words, this analysis is performed outside the program's concept of *"before"* and *"after"*.
If your story has metaphysical underpinnings, you could say that just as there are laws of physics that govern what can happen in a given universe, there are meta laws of physics that govern what a universe may or may not do. Much like the laws of a programming language govern what a program may or may not do.
Then, come up with an action (or a sequence of actions) which doesn't violate any specific physical law of our universe but, when performed under certain circumstances, it would put the universe in an inconsistent/invalid state that is illegal as far as the meta laws are concerned. If a universe contains, in its timeline, such actions that would bring it to an illegal state, that entire universe's existence could be rejected and that rejection would happen at a level outside the universe's execution and therefore its concept of time.
Now if the descendants perform an action that is possible but would be illegal ("apparently impossible") provided the ancestors had performed another action, then you're set. The ancestors are not allowed to have performed the second action, because if they had, their universe would have been in an inconsistent state and its existence would have been rejected. Such a universe could not have existed to begin with.
So how would that look? Anything that would prevent the ancestors from performing the action would suffice. However, it would probably be much more interesting to include a person or an entity that can recognize the inevitability of their actions in that meta context and be able to articulate why the ancestors are bound by the actions of their descendants. Without such an agent in the story, the entire explanation could be lost on the audience. |
65,962 | <p>The current world population is around 7 billion living people and 107 billion dead people. Since the population is increasing steadily and faster than ever, I was wondering if we could ever reach the turning point.</p>
<p>Given the 'facts' from <a href="http://www.livescience.com/18336-human-population-dead-living-infographic.html" rel="nofollow noreferrer">this source</a> are fully correct, I am left with two questions:</p>
<ul>
<li>How many years will have to pass for those living to exceed those dead on Earth (assuming we don't populate/colonize another planet).</li>
</ul>
<p>(This first question is purely asking about the math, excluding the question of the availability of food, housing and other resources).</p>
<ul>
<li>Is it even remotely possible for the living population to exceed the dead population before we turn extinct or run out of space?</li>
</ul>
<p>(This one does take the lack of resources into account).</p>
| [
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"text": "<h1>Not possible</h1>\n\n<p>The primary reason is that population growth has already peaked. From the US C... | 2016/12/26 | [
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] | The current world population is around 7 billion living people and 107 billion dead people. Since the population is increasing steadily and faster than ever, I was wondering if we could ever reach the turning point.
Given the 'facts' from [this source](http://www.livescience.com/18336-human-population-dead-living-infographic.html) are fully correct, I am left with two questions:
* How many years will have to pass for those living to exceed those dead on Earth (assuming we don't populate/colonize another planet).
(This first question is purely asking about the math, excluding the question of the availability of food, housing and other resources).
* Is it even remotely possible for the living population to exceed the dead population before we turn extinct or run out of space?
(This one does take the lack of resources into account). | Like other answers said, it is not practically possible at this point for Earth to sustain a population greater than number of people already dead. Unless you assume that every woman on the Earth for some strange reason decide to give birth each one:
```
Number of women = 7 billions / 2
Number of dead people = 107 billions
Children to give birth = (107)/(3.5) = 30.5 => 31 children.
```
So in the case that every woman now decide to give birth to 31 children (well in reality should be 40: we have to take into account people that would die in the meanwhile and keep a good error margin), and assuming (each pregnancy last 9 months) that in the middle of the process we will not end the available food (at some points we will have 60 billions people to feed and the Whole process would last 40 years), then yes it is theoretically possible.
However there's no way we could do that in general:
Assume that population keeps constantly doubling: in that case the **sum of dead people and living people would be almost the same**, but a double growth rate is not sustainable, at some point it will slow.
To keep living population greater than dead population then you need a growth rate that is more than constant doubling ( x3, but also x2.1 is fine... or even x2.00001 and so on), and that is even less sustainable that a doubling growth rate.
While in theory it is possible to exceed that limit for now (assuming enough resources), we will quickly reach a limit that will not allow us to exceed that again.
When number of children a woman can give birth in a life will be lesser than
```
Sum of dead people / sum of living women
```
Then we will not be able to exceed that limit again. (well in theory we could do that in a hundred of years, assuming we can keep a exponential grow of population for so long). |
66,819 | <p>Okay, let's assume here for a minute I am the greatest hacker in the history of our tiny little blue planet, and I manage, after years of work, to make a program that hacks banks to put money in my United States bank account. I can simply change the figure of my balance at any time. Say, for example, my program says I have</p>
<pre><code>£300
</code></pre>
<p>in the bank. I can simply edit this £300 and make it...</p>
<pre><code>£300,000
</code></pre>
<p>Let us assume I can make this program in total sancuatary and will never get caught, say, if a passerby simply notices this program through my window. Let us also assume this program is the only way I currently make money. If I simply spend the money on my needs: shelter, food, water, insurance, and all the basics, how long will it be before I am caught (if I am caught at all)?</p>
| [
{
"answer_id": 66821,
"author": "Ranger",
"author_id": 20204,
"author_profile": "https://worldbuilding.stackexchange.com/users/20204",
"pm_score": 2,
"selected": false,
"text": "<p>In the US income is reportable, including interest in a bank account. Banks that loan money (read: every ba... | 2017/01/04 | [
"https://worldbuilding.stackexchange.com/questions/66819",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/25003/"
] | Okay, let's assume here for a minute I am the greatest hacker in the history of our tiny little blue planet, and I manage, after years of work, to make a program that hacks banks to put money in my United States bank account. I can simply change the figure of my balance at any time. Say, for example, my program says I have
```
£300
```
in the bank. I can simply edit this £300 and make it...
```
£300,000
```
Let us assume I can make this program in total sancuatary and will never get caught, say, if a passerby simply notices this program through my window. Let us also assume this program is the only way I currently make money. If I simply spend the money on my needs: shelter, food, water, insurance, and all the basics, how long will it be before I am caught (if I am caught at all)? | I guess that depends on how sophisticated your hacking is and how sophisticated the bank's auditing systems are.
If you just updated your bank balance, the bank should catch that very quickly, because their books won't balance. They'll have a credit with no matching debit.
If you're smart enough to update both sides of the ledger, the bank will still surely notice something when they try to reconcile. Where did the money for this deposit come from. If you enter that it was made with cash, then when the bank does their cash reconciliation they'll find they have less cash than they should. If you say it was a direct deposit, they'll turn up short on deposits received. Etc.
If their audit trail is sophisticated enough -- and bank audit trails tend to be very sophisticated -- they'll track it back to your account pretty quickly.
There was a scam that was discussed a lot about 20 years ago -- I don't know how many people really got away with it, but it was a big buzz in computer circles -- that a programmer would change the bank's interest calculations to round fractions of a penny down instead of rounding of to the nearest whole penny, and then put those pennies in a dummy account created by the programmer. Few customers would notice that there interest was a penny short, and if they did, they'd grumble, "Hey, the bank is rounding 14.9 cents down to 14 instead of up to 15, what a rip-off", and then forget about it. Who's going to make a stink about a penny? Meanwhile if the bank has a lot of customers, the programmer is collecting significant money off all these pennies. And the bank's books would balance: if they're paying, say, 2% interest, 2% of the total of all count balances matches the total interest paid. They'd have to look pretty close to see that one account got way more interest than it should while many other accounts were a penny short.
The point is, you need to have the money come from someplace or somebody's books won't balance. You can't just create money out of thin air and expect no one to notice. |
67,394 | <p>In the climactic final battle Faction A engages Faction B on Faction B's planetary base, both in orbital and ground combat. Realizing they can't win, Faction A activates a device that transports and traps the entire planet in what can be compared to a pocket dimension. </p>
<p>So basically <strong>the entire planet vanishes from existence in (almost) an instant</strong>. Now there are two fleets of ships around the space where a planet used to be. </p>
<p><strong>What is the effect (if any) on said ships?</strong> </p>
<p>Half of me thinks that because it's in space there won't be any effect, but of course it would be cool if there was some sort of displacement effect.</p>
<p><strong>EDIT:</strong> A few answers mention the planet returning at some point. I'll have the trapped people escape several decades later, but the planet itself remains lost.</p>
<p>Several answers have been extremely useful, but unfortunately I can only pick one, so I went with the one that gave me the best alternative. The rest get upvotes though. Thanks to everyone that took the time to answer.</p>
| [
{
"answer_id": 67395,
"author": "Tim B",
"author_id": 49,
"author_profile": "https://worldbuilding.stackexchange.com/users/49",
"pm_score": 5,
"selected": false,
"text": "<p>You can have it affect them as much as you like. The device is magic, so the additional effects can be whatever yo... | 2017/01/10 | [
"https://worldbuilding.stackexchange.com/questions/67394",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/28763/"
] | In the climactic final battle Faction A engages Faction B on Faction B's planetary base, both in orbital and ground combat. Realizing they can't win, Faction A activates a device that transports and traps the entire planet in what can be compared to a pocket dimension.
So basically **the entire planet vanishes from existence in (almost) an instant**. Now there are two fleets of ships around the space where a planet used to be.
**What is the effect (if any) on said ships?**
Half of me thinks that because it's in space there won't be any effect, but of course it would be cool if there was some sort of displacement effect.
**EDIT:** A few answers mention the planet returning at some point. I'll have the trapped people escape several decades later, but the planet itself remains lost.
Several answers have been extremely useful, but unfortunately I can only pick one, so I went with the one that gave me the best alternative. The rest get upvotes though. Thanks to everyone that took the time to answer. | Earth has a Schwarzschild radius of about 3 mm.
This means things at geostationary orbital distance have a time dilation of about
$$\sqrt{1-\frac{9 mm}{35786 km}}$$
or one part in $10^{-10}$ roughly. (if they are actually orbiting this value changes slightly, as does the rotation of the Earth)
This also lines up with the length contraction factor.
When the Earth disappears "instantly", a gravitational wave of that magnitude is going to be produced. How much energy is that?
Well, 1 solar mass converted to gravitational waves and sent over 1.4 billion light years produced a $10^{-20}$ amplitude wave (LIGO observation). [The energy in a gravitational wave is proprotional to amplutide squared](http://www.lightandmatter.com/html_books/genrel/ch09/ch09.html).
So, per meter squared, the LIGO observation would carry:
```
(1 solar mass * c^2) / (1.4 billion light years*2)^2 / 4 pi * 1 m^2
```
2 \* $10^{-5}$ J (apparently it was 1 solar mass of matter converted into a gravitational wave at a distance of 1.4 billion light years).
The gravitational wave from the Earth disappearing is going to be ${10^{10}}^{2}$ stronger than that, or 2\*$10^{15}$ J. This is an insane amount of energy; however, very little of it actually deposits on normal matter.
Suppose we are 1 Jupiter-radius away from Jupiter instead.
Jupiter has a Schwarzschild radius of 2.2 m. Titan has an average orbit of 1,221,850 km. Then the gravitational wave would carry 500 times as much Energy.
The question becomes how well does it convert over to normal matter? Will it occur fast enough to disrupt an atomic nucleus?
The compression effect on molecular-level matter will only involve modest pressures. But the compression effect will occur all the way down the length scales, and I suspect it requires lots more pressure to compress a nucleus.
---
But back up a second. We ripped the planet from our universe. One could argue that would involve forming an event horizon around the planet and making it disappear.
I mean, photons not coming from an area is the definition of event horizon. Stuff an event horizon somewhere, and you warp space. The volume we need to swallow is the planet. So, black hole the size of the planet in effect blinks in then poofs?
If we are 10 planet-radius away, and the event horizon forms tightly around the planet then disappears, this would generate two gravitational waves of impressive magnitude.
$$\sqrt{1 - \frac{1 r}{10 r}}$$
gives us a amplitude of 0.05. The energy carried by this wave is about 10^17 times greater than the ones we are describing above.
In effect, all matter would suddenly feel stretched by 5%, then compressed by 5%. This would occur all the way down to the molecules, quarks and nuclei. I'd be worried about fission events from this happening suddenly, let alone the amoung of energy released by compressing "incompressible" solids by 5%.
[Compressing water by 5% would take 0.1 GPa](https://ca.answers.yahoo.com/question/index?qid=20090718001908AAEGhNH), so we could estimate the effect would be akin to a pressure wave of that magnitude over humans. [And 0.4 GPa for iron](https://answers.yahoo.com/question/index?qid=20101123191731AALTdXN).
This level of pressure in a conventional blast is enough [to blow limbs off](https://en.wikipedia.org/wiki/Overpressure).
I cannot believe the compressibility of EM mediated molecule-scale solids is in the same universe as that for a nucleus or a proton. So I would be very worried about atomic disintegration...
Ignoring that, matter slows down gravitational waves. The effect is extremely tiny, but we could use that to estimate how much impulse this would provide and how much energy deposited. I cannot find the correct equations for this case.
---
Calculating what exactly happens is going to be quite tricky. For a planet-sized event horizon, the effect will be explosive at "molecular" scales, blowing objects apart. At atomic scales, I don't know (will it cause fission?). At macroscopic scales, I don't know (will it impart a large radial impuse from the matter slowing the gravitational wave down?).
There is plenty of energy to work with. The kind of effect that energy density and flux could cause seem unbounded.
The above also neglects the power; how long the teleport takes determines the power the wave carries (how "sharp" it is, not just how much energy it carries). |
67,460 | <p>I'm creating a human race that has 3 sexes: male, female & hermaphrodite.</p>
<p>Is there any biological rules that limits what should be the ratio between sexes or I could just pick whatever works best for my story? </p>
<hr>
<p>I've added hermaphrodites for storytelling purposes. I don't plant to explain how they've evolved.</p>
<p>My gender determination system works like this:</p>
<ul>
<li>FF chromosome -> Female</li>
<li>MF or FM chromosome -> Hermaphrodite</li>
<li>MM chromosome -> Male</li>
</ul>
<p>All the fallowing couples produce viable offspring: <strong>Sire</strong> <em>Dam</em></p>
<ul>
<li><strong>Male</strong> <em>Female</em></li>
<li><strong>Male</strong> <em>Hermaphrodite</em></li>
<li><strong>Hermaphrodite</strong> <em>Female</em> </li>
<li><strong>Hermaphrodite</strong> <em>Hermaphrodite</em></li>
</ul>
<p>The children of any couple could be of any of the three genders, depending what kind of chromosomes will they receive from their parents. Both sperm and eggs are haploid carrying either M or F chromosome.</p>
<p>Testosterone levels, height and muscles vary by individual but in general:</p>
<ul>
<li>Males -highest testosterone level, tallest, most muscular (John Cena, Dwayne Johnson, Vin Diesel)</li>
<li>Hermaphrodites - medium testosterone level, medium height, muscles like elite female fighters due to natural doping (Ronda Rousey, Kyra Gracie, Cristiane 'Cyborg' Justino) </li>
<li>Woman -lowest testosterone, shortest, least amount of muscles, looks like any normal women that doesn't like to go to gym</li>
</ul>
| [
{
"answer_id": 67463,
"author": "Samuel",
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"author_profile": "https://worldbuilding.stackexchange.com/users/3202",
"pm_score": 2,
"selected": false,
"text": "<p>Well, that's the same <a href=\"https://en.wikipedia.org/wiki/Third_gender#Intersex_people_and_third_gender\"... | 2017/01/10 | [
"https://worldbuilding.stackexchange.com/questions/67460",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/32045/"
] | I'm creating a human race that has 3 sexes: male, female & hermaphrodite.
Is there any biological rules that limits what should be the ratio between sexes or I could just pick whatever works best for my story?
---
I've added hermaphrodites for storytelling purposes. I don't plant to explain how they've evolved.
My gender determination system works like this:
* FF chromosome -> Female
* MF or FM chromosome -> Hermaphrodite
* MM chromosome -> Male
All the fallowing couples produce viable offspring: **Sire** *Dam*
* **Male** *Female*
* **Male** *Hermaphrodite*
* **Hermaphrodite** *Female*
* **Hermaphrodite** *Hermaphrodite*
The children of any couple could be of any of the three genders, depending what kind of chromosomes will they receive from their parents. Both sperm and eggs are haploid carrying either M or F chromosome.
Testosterone levels, height and muscles vary by individual but in general:
* Males -highest testosterone level, tallest, most muscular (John Cena, Dwayne Johnson, Vin Diesel)
* Hermaphrodites - medium testosterone level, medium height, muscles like elite female fighters due to natural doping (Ronda Rousey, Kyra Gracie, Cristiane 'Cyborg' Justino)
* Woman -lowest testosterone, shortest, least amount of muscles, looks like any normal women that doesn't like to go to gym | ### Arbitrary system
I came up with a system for handling genders. In this system, a female is FF, a male is MM, and a hermaphrodite is FM. So if a female and a male breed, they have only hermaphroditic offspring. If a hermaphrodite breeds with either other sex, there's a 50% chance of a hermaphrodite and a 50% chance that the child is the same gender as the other partner. If two hermaphrodites breed, they have a 50% chance of a hermaphrodite and 25% each for the other genders.
```
+---+----+----+ +---+----+----+ +---+----+----+ +---+----+----+
| | F | F | | | F | F | | | F | M | | | F | M |
+---+----+----+ +---+----+----+ +---+----+----+ +---+----+----+
| M | FM | FM | | F | FF | FF | | M | FM | MM | | F | FF | FM |
+---+----+----+ +---+----+----+ +---+----+----+ +---+----+----+
| M | FM | FM | | M | FM | FM | | M | FM | MM | | M | FM | MM |
+---+----+----+ +---+----+----+ +---+----+----+ +---+----+----+
```
I ran some simulations (code and assumptions at the bottom). I found a slight preference for hermaphroditic offspring overall but a stable one. So perhaps 56-57% hermaphrodite and evenly distributed between the other two. Note that it is possible to favor males over females or vice versa. For example, a rule that hermaphrodites and females only breed with males (possibly allowing males with multiple spouses) would eliminate females and keep females eliminated so long as it was followed.
This was based purely on those rules. If you have different rules, then you're going to get different results. It might be better to approach the problem from the other direction. How would you like to split the genders and why? Some splits may not have an easy explanation.
### Alternatives
I read a book a while ago where gender was determined by the gender ratio around the child. So all children were neuters. The move to adulthood occurred when the child would develop a gender. A child surrounded by females would become male. A child surrounded by males would become female. You could extend that to include hermaphrodites (surrounded by equal numbers of males and females). And you could provide arbitrary rules for the development of children surrounded by hermaphrodites. That society could choose its gender ratio if it wanted.
We often act like males and females are perfectly evenly divided in humans. But actually Y sperm are more likely to form. This is partially offset as Y sperm are less likely to succeed to fertilization. But overall, there are more boy babies than girl babies. Boys/men are also more fragile, dying in accidents more often. With modern medicine, women seldom die due to pregnancy. So by retirement age, there are more women than men.
Anyway, you can use similar mechanisms to alter ratios in your humanoids. Perhaps there is some birth defect that is common in one gender or another that leads to miscarriage. Perhaps hermaphrodites produce less sperm. Perhaps the genetics is more complicated.
### Simulation code
**GenderSimulator.java**
```
import java.security.SecureRandom;
import java.util.EnumMap;
import java.util.Map;
import java.util.Random;
public class GenderSimulator {
public enum Gender {
FEMALE, HERMAPHRODITE, MALE;
public Gender opposite() {
switch (this) {
case FEMALE:
return MALE;
case MALE:
return FEMALE;
default:
return null;
}
}
}
public static class Generation {
Map<Gender, Integer> genderCounts = new EnumMap<Gender, Integer>(Gender.class);
public Generation() {
this(0, 0, 0);
}
public Generation(int femaleCount, int hermaphroditeCount, int maleCount) {
genderCounts.put(Gender.FEMALE, femaleCount);
genderCounts.put(Gender.HERMAPHRODITE, hermaphroditeCount);
genderCounts.put(Gender.MALE, maleCount);
}
public Generation generateNext() {
Generation generation = new Generation();
generateRandomCouples(generation);
generateFemaleMaleCouples(generation);
generateCouples(generation, Gender.FEMALE);
generateCouples(generation, Gender.MALE);
generateFromHermaphrodites(generation);
return generation;
}
public int size() {
int sum = 0;
for (int count : genderCounts.values()) {
sum += count;
}
return sum;
}
public int count(Gender gender) {
Integer count = genderCounts.get(gender);
return (count == null) ? 0 : count;
}
private void add(Gender gender, int amount) {
int count = count(gender);
genderCounts.put(gender, count + amount);
}
private Gender chooseGenderChildOfHermaphrodites() {
int choice = RANDOM.nextInt(4);
if (choice == 0) {
return Gender.FEMALE;
} else if (choice == 3) {
return Gender.MALE;
} else {
return Gender.HERMAPHRODITE;
}
}
private Gender chooseGenderChild(Gender gender) {
return RANDOM.nextBoolean() ? Gender.HERMAPHRODITE : gender;
}
private Gender chooseGenderParent() {
int choice = RANDOM.nextInt(count(Gender.HERMAPHRODITE) + count(Gender.MALE) + count(Gender.FEMALE));
if (choice < count(Gender.HERMAPHRODITE)) {
return Gender.HERMAPHRODITE;
} else if (choice < count(Gender.HERMAPHRODITE) + count(Gender.MALE)) {
return Gender.MALE;
}
return Gender.FEMALE;
}
private boolean hasHermaphroditeParent(Gender gender) {
return RANDOM.nextInt(count(Gender.HERMAPHRODITE) + count(gender)) < count(Gender.HERMAPHRODITE);
}
private void breedWith(Generation generation, Gender gender) {
add(gender, -1);
if (hasHermaphroditeParent(gender.opposite())) {
add(Gender.HERMAPHRODITE, -1);
generation.add(chooseGenderChild(gender), 1);
generation.add(chooseGenderChild(gender), 1);
} else {
add(gender.opposite(), -1);
generation.add(Gender.HERMAPHRODITE, 2);
}
}
private void generateFemaleMaleCouples(Generation generation) {
int maleCount = count(Gender.MALE);
int femaleCount = count(Gender.FEMALE);
int count = Math.min(maleCount, femaleCount);
genderCounts.put(Gender.MALE, maleCount - count);
genderCounts.put(Gender.FEMALE, femaleCount - count);
generation.add(Gender.HERMAPHRODITE, 2 * count);
}
private void generateRandomCouples(Generation generation) {
while (count(Gender.HERMAPHRODITE) - 1 > Math.abs(count(Gender.MALE) - count(Gender.FEMALE))
&& count(Gender.FEMALE) > 0 && count(Gender.MALE) > 0) {
Gender parent = chooseGenderParent();
if (parent == Gender.HERMAPHRODITE) {
add(Gender.HERMAPHRODITE, -1);
Gender other = chooseGenderParent();
if (other == Gender.HERMAPHRODITE) {
add(Gender.HERMAPHRODITE, -1);
generation.add(generation.chooseGenderChildOfHermaphrodites(), 1);
generation.add(generation.chooseGenderChildOfHermaphrodites(), 1);
} else {
add(other, -1);
generation.add(chooseGenderChild(other), 1);
generation.add(chooseGenderChild(other), 1);
}
} else {
breedWith(generation, parent);
}
}
}
private void generateCouples(Generation generation, Gender gender) {
while (count(gender) > 0 && count(Gender.HERMAPHRODITE) > 0) {
add(gender, -1);
add(Gender.HERMAPHRODITE, -1);
generation.add(chooseGenderChild(gender), 1);
generation.add(chooseGenderChild(gender), 1);
}
}
private void generateFromHermaphrodites(Generation generation) {
while (count(Gender.HERMAPHRODITE) > 1) {
add(Gender.HERMAPHRODITE, -2);
generation.add(generation.chooseGenderChildOfHermaphrodites(), 1);
generation.add(generation.chooseGenderChildOfHermaphrodites(), 1);
}
}
public String toString() {
return toString("-");
}
public String toString(String delimiter) {
StringBuilder builder = new StringBuilder();
builder.append(genderCounts.get(Gender.FEMALE));
builder.append(delimiter);
builder.append(genderCounts.get(Gender.HERMAPHRODITE));
builder.append(delimiter);
builder.append(genderCounts.get(Gender.MALE));
return builder.toString();
}
}
public final static Random RANDOM = new SecureRandom();
public static void main(String[] args) {
Generation generation = new Generation(2150, 5700, 2150);
System.out.println(generation);
int size = generation.size();
while (true) {
generation = generation.generateNext();
System.out.println(generation);
if (size != generation.size()) {
break;
}
size = generation.size();
}
}
}
```
Assumptions:
* Breeding is monogamous (if you breed with someone, all your children are with that someone);
* Any compatible and available partner is equally likely (hermaphrodites are neither preferred nor avoided as partners relative to the other genders);
* No male/male or female/female relationships, as those wouldn't produce offspring;
* Every couple has two children (stable population);
* Everyone breeds with someone (also needed for a stable population).
Note that this code is not particularly flexible. You can't swap breeding strategies in and out. That's hard coded. Changing the first generation involves modifying code. This is mainly designed to test my initial hypothesis that hermaphrodites would make up 50% of the population. That does not seem to be true. The hermaphrodite population stabilizes around 56-57% when everything is random.
The other genders are less stable, fluctuating in a much wider band.
I used interior classes because it was easier for me to do this in just one file. I used `SecureRandom` because I didn't seem to need more efficiency, and I wanted to be sure that my results weren't being tainted by too much pseudo in my random. I didn't notice any difference between the two, so you could switch back if you wanted. |
68,121 | <p><a href="https://worldbuilding.stackexchange.com/questions/68006/mountaintop-sea-characteristics-regarding-tides-outflow-and-microclimate">I have recently asked a question about creating a sea on a mountaintop</a>. I have come to realize that I would run with some problems by doing this, namely about the salinity of the lake. I want that thread to stay on topic, so I'll post this question here, and possibly will edit the first question accordingly.</p>
<hr>
<p>So without further ado, let's try to provide some context:</p>
<ul>
<li><strong>Cosmic background:</strong> An Earth-like planet, with a Moon like ours, orbiting a Sun like ours</li>
<li><strong>Geographical background:</strong> There's a continent (its size doesn't matter) on the Southern hemisphere with a north shore on the equator. On that shore, next to the ocean, there is a mountain. On the mountaintop there is a basin. </li>
</ul>
<p>I want to create a permanent salt lake / sea on that basin... and to build a city on the shores of said lake / sea.</p>
<hr>
<p><strong><em>Parameters:</em></strong></p>
<ul>
<li><strong>Mountain's altitude from sealevel to mountaintop</strong>: 1.000 meters</li>
<li><strong>Basin's radius</strong>: 100 Km</li>
<li><strong>Basin's maximum depth</strong>: 100 meters</li>
<li><strong>Water source:</strong> Primarily from rain (I guess that, being on the equator, it is quite rainy)
<hr></li>
</ul>
<p>Now, I have two questions:</p>
<ol>
<li>Is such a lake possible? <em>(Note: Not probable... possible)</em></li>
<li>How could such lake come to be formed? <em>(Note: Having the lake form on the sealevel and then being lifted by some kind of geographical phenomenon is acceptable, as long as it remains steadily saline overtime)</em></li>
</ol>
<p>To answer both this questions, it is acceptable to tamper with any of the parameters that I posted here, with two exceptions: a) The altitude must be suficiently high to be a mountain, but suficiently low to receive rainwater; b) the lake surface may be greater, but not lower than posted.</p>
<p>Other than that, feel free to change the altitude, radius, depth or even imagine alternative water sources (remember that you're on a mountaintop) to achieve the desired goal.</p>
<p>It is <strong>not</strong> acceptable to change anything on the Cosmic or Geographical background.</p>
| [
{
"answer_id": 68130,
"author": "Loren Pechtel",
"author_id": 264,
"author_profile": "https://worldbuilding.stackexchange.com/users/264",
"pm_score": 2,
"selected": false,
"text": "<p>Copied from: <a href=\"https://worldbuilding.stackexchange.com/a/68050/264\">https://worldbuilding.stack... | 2017/01/16 | [
"https://worldbuilding.stackexchange.com/questions/68121",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/20681/"
] | [I have recently asked a question about creating a sea on a mountaintop](https://worldbuilding.stackexchange.com/questions/68006/mountaintop-sea-characteristics-regarding-tides-outflow-and-microclimate). I have come to realize that I would run with some problems by doing this, namely about the salinity of the lake. I want that thread to stay on topic, so I'll post this question here, and possibly will edit the first question accordingly.
---
So without further ado, let's try to provide some context:
* **Cosmic background:** An Earth-like planet, with a Moon like ours, orbiting a Sun like ours
* **Geographical background:** There's a continent (its size doesn't matter) on the Southern hemisphere with a north shore on the equator. On that shore, next to the ocean, there is a mountain. On the mountaintop there is a basin.
I want to create a permanent salt lake / sea on that basin... and to build a city on the shores of said lake / sea.
---
***Parameters:***
* **Mountain's altitude from sealevel to mountaintop**: 1.000 meters
* **Basin's radius**: 100 Km
* **Basin's maximum depth**: 100 meters
* **Water source:** Primarily from rain (I guess that, being on the equator, it is quite rainy)
---
Now, I have two questions:
1. Is such a lake possible? *(Note: Not probable... possible)*
2. How could such lake come to be formed? *(Note: Having the lake form on the sealevel and then being lifted by some kind of geographical phenomenon is acceptable, as long as it remains steadily saline overtime)*
To answer both this questions, it is acceptable to tamper with any of the parameters that I posted here, with two exceptions: a) The altitude must be suficiently high to be a mountain, but suficiently low to receive rainwater; b) the lake surface may be greater, but not lower than posted.
Other than that, feel free to change the altitude, radius, depth or even imagine alternative water sources (remember that you're on a mountaintop) to achieve the desired goal.
It is **not** acceptable to change anything on the Cosmic or Geographical background. | Catchment to lake ratio is relevant
===================================
Your lake is near the Equator, so there should be plenty of rainfall. We can calculate the ratio of catchment to lake surface, and then apply that ratio to your lake. The ratio we will calculate is total size of basin (catchment + surface) to surface. This will give us (if inverted) the percentage of the basin covered by lake surface.
We will restrict our list to lakes that are large, relatively close to the Equator, and not man-made (i.e. not a dam reservoir). Its a short list. All areas in square kilometers.
```
Lake Catchment Surface (C + S)/S
[Victoria][1] 184,000 68,000 3.7
[Tanganyika][2] 231,000 32,900 8.0
[Kivu][3] 2,700 2,700 2.0
[Edward][4] 12,096 2,325 6.2
[Titicaca][5] 58,000 8,372 7.9
[Nicaragua][6] 41,600 8,264 6.0
[Toba][7] 2,550 1,103 3.3
```
There is also Lake Albert, but I couldn't find a reliable catchment for it.
There are two things we have learned here. First, all these lakes have outflows, and so your endoheric lake, with no outflow, could potentially have an even larger basin to surface area ratio. Secondly, there exists an example on Earth of a lake, Lake Kivu, that has relatively large, very deep, and even with an outflowing river it occupies about half of the area of its basin.
What this means for your basin
==============================
Your basin has a 100 km$^2$ radius and a total area of around 31,000 km$^2$. If you use Lake Kivu as a model, then you could easily have a 15,000 km$^2$ occupying half the basin, even if you still had a river flowing out. Since Lake Kivu is significantly smaller, you could use the Lake Victoria ratio, where the lake surface is about 8,500 km$^2$, taking up a little over a quarter of the basin. Again, this ratio is supportable even with water flowing out.
Alternately, if you want a 31,000 km$^2$ lake, you would need the basin to be 62,000 km$^2$ (140 km radius) using the Kivu ratio, or 115,000 km$^2$ (190 km radius) using the Victoria ratio.
Again, as mentioned repetedly in the other post, Lake Victoria is a giant lake on top of a giant mountain: the enormous chunk of land lifted a mile into the sky between the two branches of the African Rift Valley. Victoria's basin is bordered on one side by the Aberdare range and solitary volcanic summits like Elgon and Meru, and the other by the Ruwenzori and Virunga mountains. But on the north and south it is bordered by high plateau land before it drops off to lower altitudes. Whether you want high encircling mountains, or just a flat topped plateau, Lake Victoria's situation has the scale and geological foundation you are looking for.
Why does it have to be salty
============================
As mentioned above, the catchment ratios I listed are from freshwater lakes with an outlet. If you want a freshwater lake, you can still have lakes that large with an outlet.
If you allow a surface outlet, you can have spectacular waterfalls. Angel falls, the highest in the world, is caused because of a flat-topped mountain like you mention. The [Tepuis](https://en.wikipedia.org/wiki/Tepui) of Venezuela have their own unique geological orgins, though they are smaller than you are looking for. [Auyan-tepui](https://en.wikipedia.org/wiki/Auy%C3%A1n-tepui), the host of Angel Falls, rises vertically almost 1000m above the surrounding jungle, and is a flat topped mountain about 670 km$^2$ in area.
Also, if you do not want a surface outlet, you can have a subterranean outlet. If the river drains through a cave system, it can remain fresh while appearing to be in an endoheric basin. |
69,140 | <p>Consider a <a href="https://en.wikipedia.org/wiki/Constructed_language" rel="nofollow noreferrer">conlang</a> designed for an interstellar transmission to a recipient that will have to figure it out.</p>
<p>I’m thinking it will be invented for the purpose, formal, and rigorous. It will seemlessly make a transition from mathematical notation or computer algorithms to stating facts about real-world things.</p>
<p>So besides the obvious nouns and verbs, just how many different “kinds” of words are there, really?</p>
<p>Does anybody know anything about <a href="https://en.wikipedia.org/wiki/Ontology_language" rel="nofollow noreferrer">ontology languages</a> or <a href="https://en.wikipedia.org/wiki/Lojban" rel="nofollow noreferrer">Lojban</a>? <strong>I wonder if there are more universal categories than the parts of speech used in English.</strong></p>
<p>The reason I’m asking is because the <em>number</em> of categories shows up directly in my scenareo. There’s no orthography in a conventional sense, as the transmission is just a bunch of numbers. Words are simply numbered, so something like <em>Noun #42</em> would be the literal spelling. There will either be different codes introducing different categories, or the category will be implied by its number: <em>Word #42</em> is a noun because the type is implied by remainder of the number modulo 7 (or however many types we need).</p>
<p>Also, there’s no distinction between what we think of as words and punctuation. Grouping and separators also need their own codes and are encoded in the same manner. </p>
| [
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"answer_id": 69141,
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"selected": false,
"text": "<p>Parts of speech are really an artificial division chosen by humans to explain the structure of our langua... | 2017/01/25 | [
"https://worldbuilding.stackexchange.com/questions/69140",
"https://worldbuilding.stackexchange.com",
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] | Consider a [conlang](https://en.wikipedia.org/wiki/Constructed_language) designed for an interstellar transmission to a recipient that will have to figure it out.
I’m thinking it will be invented for the purpose, formal, and rigorous. It will seemlessly make a transition from mathematical notation or computer algorithms to stating facts about real-world things.
So besides the obvious nouns and verbs, just how many different “kinds” of words are there, really?
Does anybody know anything about [ontology languages](https://en.wikipedia.org/wiki/Ontology_language) or [Lojban](https://en.wikipedia.org/wiki/Lojban)? **I wonder if there are more universal categories than the parts of speech used in English.**
The reason I’m asking is because the *number* of categories shows up directly in my scenareo. There’s no orthography in a conventional sense, as the transmission is just a bunch of numbers. Words are simply numbered, so something like *Noun #42* would be the literal spelling. There will either be different codes introducing different categories, or the category will be implied by its number: *Word #42* is a noun because the type is implied by remainder of the number modulo 7 (or however many types we need).
Also, there’s no distinction between what we think of as words and punctuation. Grouping and separators also need their own codes and are encoded in the same manner. | Parts of speech are really an artificial division chosen by humans to explain the structure of our language. They don't always line up perfectly. Take Japanese as an example. Japanese has "particles," which are words which don't fit into any particular category that we English speakers recognize. There are also the polysynthetic languages where a single word captures what we English speakers would call a sentence. And of course, in English we have some interesting words such as a particular expletive starting with the letter F which defy categorization (as demonstrated in this decidedly NSFW [clip from the Boondock Saints](https://www.youtube.com/watch?v=UBX26rVDBTo)).
One interesting option which is along the lines of your numbered words is to look at languages used to describe semantic webs such as RDF and OWL. RDF, for instance, is remarkably simple. There are three parts of "speech:" subjects, predicates, and objects. Subjects and predicates are always "IRIs" which are similar in nature to your numbered words. Objects are either IRI's or "datatype values" which are concrete values like numbers. That's all there is to it, and yet it can describe world with all the flavor of any more advanced language.
[](https://i.stack.imgur.com/5k7zD.png)
Of course, they wouldn't send it as a image like that. They'd render the content in a different format, such as Turtle, which is text based and more concise with easier parallels to a interstellar communication format:
```
<http://example.org/123> dc:subject <http://example.org/subject32> .
<http://example.org/subject32>
rdf:type ex:ExampleSubjects ;
dcrdf:valueString "Biology"@en , "EA32"^^ex:SubjectEncoding ;
```
OWL is similar in nature, but is rather fascinating because it can describe its own semantics rather elegantly. For example, you could actually have a rule "All Words which are the subject of a sentence are also Nouns." These relationships can be specified with enough regularity that OWL users can use "reasoners" to fill in relationships that were not explicitly written down in the document.
The fantastical power of these semantic web languages is that, if someone has not specified the semantics of what Word #42 should mean in a particular construct, or if there is no word which meets your needs, you can make up semantics for it. You can then write down those semantics (typically in an OWL Ontology). Others can read those semantics, and act on it algorithmically. So I might define a new Word #3.14 that you've never seen before, and I can do so in such a way that you stand a chance of understanding what I meant by it!
This semantic ability would be extremely important if time lags were large. Languages evolve over time, and if there's enough time lag between communications, its reasonable to believe that the meaning of Noun #42 might change for one culture and not the other. The ability to at least attempt to capture the semantics of what you are saying would be very important for combating these effects. |
69,281 | <p>My team of researchers has created an AI to increase human suffering and the machine has started earning money on the market. The ministry of economics has sent a technician to review the machine and see if it can be used on a wider scale. I want to see if a specialist would detect such a "defect" </p>
<p>Do AIs have vague objectives programmed into them, like "increase human suffering"?</p>
<p>If not, how could a reviewer detect that an AI is programmed to do so?
<strong>edit:</strong> provided that the AI doesn't try too hard to hide the fact but also doesn't make it apparent </p>
| [
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"answer_id": 69283,
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"text": "<p>No, they don't. You'd need to have the programmers explicitly state what the machine should interp... | 2017/01/26 | [
"https://worldbuilding.stackexchange.com/questions/69281",
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] | My team of researchers has created an AI to increase human suffering and the machine has started earning money on the market. The ministry of economics has sent a technician to review the machine and see if it can be used on a wider scale. I want to see if a specialist would detect such a "defect"
Do AIs have vague objectives programmed into them, like "increase human suffering"?
If not, how could a reviewer detect that an AI is programmed to do so?
**edit:** provided that the AI doesn't try too hard to hide the fact but also doesn't make it apparent | The purpose of AIs is to permit increasingly vague instructions. "Typical" computer programs need extremely precise instructions and they are followed without error. Modern AI's are typically given "goals" which are used to train the AIs, but they are more specific than "increase human suffering." Future AIs are theorized to be able to accept more vague goals like you describe. Your task may call for a AGI (Artificial General Intelligence), which is the name given to the yet-undeveloped AIs which are at least as intelligent as a human being.
You cannot actually detect what an AI is programmed to do. That's somewhat to their nature of operating on less precise instructions. What you *can* do is look at the training set they were given and draw conclusions from that.
A great example of this is a famous neural network. It was given a grid of dots as an input (7x7 grid I believe), each of which can be "lit" or "unlit," and its output was a "Yes" or "No." This network was trained first by giving it a series of 7x7 images of arrows pointing to the left. They looked something like this:
```
Left Arrow Not arrow(example)
. . . # . . . . . . . . . .
. . # . . . . . . . . . . .
. # . . . . . . . # # # . .
# # # # # # # . . # . # . .
. # . . . . . . . # # # . .
. . # . . . . . . . . . . .
. . . # . . . . . . . . . .
```
It was trained until it could reliably recognize the difference between a left arrow and a non arrow. Then, it was given a training set that included arrows to the right. Predictably, it did not recognize this as a left arrow, so it outputted "No." However, after more training it started recognizing both left and right facing arrows. Then we gave it an arrow facing up, and trained it until it could recognize upward arrows. Then downward. Each one proved easier to train than the last, almost like it was "recognizing" arrows.
Then the interesting challenge: we gave the AI a set of diagonal arrows. On a 7x7 grid, these look quite different than horizontal or vertical arrows. However, the neural net responded "yes" to them. It had learned the abstract concept of "an arrow" and responded to a novel stimulus accordingly.
If you looked at the weights on that neural network, you would never be able to distill from it "the AI is looking for arrows." Neural network weights are almost impossible for us to decipher. And, if you looked at the training set, you could see that it was being trained to recognize horizontal and vertical arrows. However, what you could not discern was whether it had learned to recognize horizontal and vertical arrows, or if it had somehow learned the abstract idea of "arrows in any direction." Or maybe it has learned "shapes that can be decomposed into three lines." The only way to tell that was to test it -- give it a diagonal arrow and see what it did with it. |
69,362 | <p>Nowadays many websites used internet cookies which is in fact a piece of code or a script that can store user data and other preferences, it usually cannot be executed by itself think of it like your personal secretary who manages all your daily routine, meetings, agenda, reports etc. Since everything are connected to the internet, could internet cookies turns into A.I. smart enough to silently track and gain access to a nuclear silo or tactical sub and fires a nuclear warhead at random?</p>
| [
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"answer_id": 69364,
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"text": "<p>I think you misunderstand cookies, or how powerful they are.<br>\nCookies are not executed. They hold text-dat... | 2017/01/27 | [
"https://worldbuilding.stackexchange.com/questions/69362",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/8400/"
] | Nowadays many websites used internet cookies which is in fact a piece of code or a script that can store user data and other preferences, it usually cannot be executed by itself think of it like your personal secretary who manages all your daily routine, meetings, agenda, reports etc. Since everything are connected to the internet, could internet cookies turns into A.I. smart enough to silently track and gain access to a nuclear silo or tactical sub and fires a nuclear warhead at random? | I think you misunderstand cookies, or how powerful they are.
Cookies are not executed. They hold text-data, and that text-data is read.
Taken from [Wikipedia](https://en.wikipedia.org/wiki/HTTP_cookie):
A cookie consists of the following components:
```
Name
Value
Zero or more attributes (name/value pairs). Attributes store information such as the cookie’s expiration, domain, and flags (such as Secure and HttpOnly).
```
So, no code that can turn into an AI, at least not with current technology and cookies. |
69,917 | <p>I am designing the geography of a lake in which two rivers flow. Should it have a river flowing from it to the sea or vice versa?</p>
| [
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"text": "<p>If a river flows from ocean into lake, you better have another river that flows out of the lake into someplace... | 2017/02/02 | [
"https://worldbuilding.stackexchange.com/questions/69917",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/32999/"
] | I am designing the geography of a lake in which two rivers flow. Should it have a river flowing from it to the sea or vice versa? | Normally, a lake will have a fresh water river flowing into it from higher ground, and a river flowing out of it to the sea.
```
Fresh water source
\
\
--- Lake ---
\
\
Ocean
```
If you do it the other way around, water can't flow out of the lake. The lake would have to be below sea level. It would fill and overflow until the level of the lake has reached sea level and merged with the sea. Then you'd get something like the [Mediterranean Sea](https://en.wikipedia.org/wiki/Mediterranean_Sea) fed by the [Strait of Gibraltar](https://en.wikipedia.org/wiki/Strait_of_Gibraltar) or further in the [Black Sea](https://en.wikipedia.org/wiki/Black_Sea) fed by the [Dardanelles](https://en.wikipedia.org/wiki/Dardanelles). Both the Mediterranean and the Black Sea are at the global sea level. Both straits have both inflow and outflow.
There are lakes below sea level, the [Dead Sea](https://en.wikipedia.org/wiki/Dead_Sea) for example, but it's cut off from the sea and fed by the Jordan River. Its "outflow" is evaporation. |
69,918 | <p>After hearing about Alex the African Gray Parrot, and knowing how intelligent ravens are, just how smart could a brain of that size become?</p>
<p>I would like to limit the responses to current known or theoretical science in order to have as much realism as possible, despite the fact that this would be for a decidedly non-human race (about the size and dimensions of a pygmy gibbon). I'm also referring to biological brains only, naturally evolved.</p>
<p>By max capacity I mean intelligence we could expect. It might be easiest to make educated guesses in the form of "IQ". If you have a better understanding of cell structure of the brain, number of cells that could exist in what density, etc. then I'd love to hear about that too.</p>
| [
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"text": "<p>If a river flows from ocean into lake, you better have another river that flows out of the lake into someplace... | 2017/02/02 | [
"https://worldbuilding.stackexchange.com/questions/69918",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/32453/"
] | After hearing about Alex the African Gray Parrot, and knowing how intelligent ravens are, just how smart could a brain of that size become?
I would like to limit the responses to current known or theoretical science in order to have as much realism as possible, despite the fact that this would be for a decidedly non-human race (about the size and dimensions of a pygmy gibbon). I'm also referring to biological brains only, naturally evolved.
By max capacity I mean intelligence we could expect. It might be easiest to make educated guesses in the form of "IQ". If you have a better understanding of cell structure of the brain, number of cells that could exist in what density, etc. then I'd love to hear about that too. | Normally, a lake will have a fresh water river flowing into it from higher ground, and a river flowing out of it to the sea.
```
Fresh water source
\
\
--- Lake ---
\
\
Ocean
```
If you do it the other way around, water can't flow out of the lake. The lake would have to be below sea level. It would fill and overflow until the level of the lake has reached sea level and merged with the sea. Then you'd get something like the [Mediterranean Sea](https://en.wikipedia.org/wiki/Mediterranean_Sea) fed by the [Strait of Gibraltar](https://en.wikipedia.org/wiki/Strait_of_Gibraltar) or further in the [Black Sea](https://en.wikipedia.org/wiki/Black_Sea) fed by the [Dardanelles](https://en.wikipedia.org/wiki/Dardanelles). Both the Mediterranean and the Black Sea are at the global sea level. Both straits have both inflow and outflow.
There are lakes below sea level, the [Dead Sea](https://en.wikipedia.org/wiki/Dead_Sea) for example, but it's cut off from the sea and fed by the Jordan River. Its "outflow" is evaporation. |
71,877 | <p>In <em>The Walking Dead</em>, the survivors have seen plenty a wall. From Woodsbury, to Wellington, to Alexandrea, they are all different and they all have their advantages. One issue that none of them have managed to fulfill yet is the gate though.
Every wall in the walking dead, and in history, has one major weakness, the gate. No matter how strong the wall is, the entrance to that wall is weak. </p>
<p>Take for example, Alexandria. Their wall is made of large metal plates held together with steel supports and mound of dirt behind them displaced from a frontal moat. While this wall is successful at repelling any threat, when thousands of zombies came knocking at their door, the door fell off its hinges and the wall became useless. </p>
<p>This made me realize that the gate is the primary weakness of all walls and also made me wonder; is there a gate design that can repel hundreds, if not thousands of zombies, while still allowing humans to enter?</p>
| [
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"answer_id": 71880,
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"text": "<p>Human engineering can, 100%, keep out a horde of zombies. In <em>The Walking Dead</em> things fail becau... | 2017/02/21 | [
"https://worldbuilding.stackexchange.com/questions/71877",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/11049/"
] | In *The Walking Dead*, the survivors have seen plenty a wall. From Woodsbury, to Wellington, to Alexandrea, they are all different and they all have their advantages. One issue that none of them have managed to fulfill yet is the gate though.
Every wall in the walking dead, and in history, has one major weakness, the gate. No matter how strong the wall is, the entrance to that wall is weak.
Take for example, Alexandria. Their wall is made of large metal plates held together with steel supports and mound of dirt behind them displaced from a frontal moat. While this wall is successful at repelling any threat, when thousands of zombies came knocking at their door, the door fell off its hinges and the wall became useless.
This made me realize that the gate is the primary weakness of all walls and also made me wonder; is there a gate design that can repel hundreds, if not thousands of zombies, while still allowing humans to enter? | We humans are pretty good at building gates to keep people out. We've been doing it for a long time for military purposes and to stop thieves.
Why Do We Have Gates?
=====================
Because there has to be some way for friendlies to get through the defenses while keeping the bad guys out.
From a military perspective, a gate isn't there to stop people from getting in. They'll get in. Instead, it's there to channel them into a particular area by the allure of an easier passage. Avoid the wall and its defenses, drive through the gate! In anticipation, that particular area is set up as a kill zone: a deadly crossfire will be in place to mow down anyone who comes through, combined with removable obstacles to slow them down and pin them in the kill zone.
From a security perspective, a gate is also there to slow down a thief. But instead of a kill zone, it exists to be such a nuisance to force the thief to give up, or to make so much noise getting through they're detected. Once detected, forces are rushed in.
So, gates exist to...
* provide access through defenses for friendlies
* herd attackers into a kill zone
* force the attacker to reveal themselves
* slow the attacker to there's more time to deal with them
Zombies don't act like an intelligent, coordinated military force, nor do they act like thieves. They just walk, slowly, towards food. They might not even find the gate and instead just walk into the wall in whatever direction they came from. (Note: I only watched the first few episodes of The Walking Dead, so I don't know exactly how their zombies act).
That is until you start making a bunch of noise going in and out of the gate. Then they'll go investigate. The problem is not having a big rush of zombies at the gate, the problem is having a slowly growing, constant pile up at the gate which is putting more and more pressure on it until, like a fence at a football riot, it will collapse.
Zombies also don't get tired and give up. They'll keep banging on that gate and walls until one of them breaks.
This means you need an active defense to clear the zombies off, and you need to do it efficiently and safely.
Establish A Kill Zone
=====================
Take advantage of that pile up and use it as a kill zone. The zombies will be easy pickings as they pile up against the gate, or even the walls. A few isn't a problem, unless you need to go out. Take care of them before there's too many.
Kill Them Cheaply
=================
You want to set up your gate and defenses so the zombies can be killed without expending resources. This means no guns and no gasoline. There's going to be a lot of them, and you only have so many bullets. Save them for emergencies and foraging.
Kill Them Safely
================
You're going to be doing this *a lot* and even a single bite means you're dead. That means it has to be done very safely, no heroics.
Bars + Pikes
============
The simplest actively defended anti-zombie gate is some sturdy iron bars and a few people with pikes. Zombies thrash against the iron bars, the pikemen stick them in the face from well outside of arms reach. Cover the end of the shaft in grease to prevent the zombies from grabbing it. If they do, pikes are cheap. Let go and grab another one. Maybe you can get the lost one later when they're all dead.
These bars can and should be placed all around your defenses to prevent zombies from piling up at any point on the wall.
Flexible Gates
==============
Against an enemy like a zombie, rigid defenses might not be the best idea. Instead, you might want to try a [flexible security gate] like you'd find in a mall.
[](https://i.stack.imgur.com/gRPCw.jpg)
Unlike rigid bars which will take all the force of zombies banging on it, a flexible security gate will flex and wobble which will absorb some of the impact. And they have those handy slots for stabbing zombies through.
Just make sure it's strong enough to hold back a horde pressing against it, and it's secured to something that's strong enough, too.
Evolution 1: The Murder Hole
============================
This is, essentially, an inner and outer [portcullis](https://en.wikipedia.org/wiki/Portcullis): a big, heavy gate with spikes on the bottom that drops from a height.
[](https://i.stack.imgur.com/3Poo7.jpg)
Zombies on the outside, pikemen on the inside.
```
===============
P * *ZZZZ
P * *ZZZZ
P * *ZZZZ
P * *ZZZZ
P * *ZZZZ
===============
```
Raise the outer gate, let some Zed in, then lower it again. If there's some zombies under it, so much the better.
```
===============
P *Z *ZZZ
P *Z *ZZZ
P *Z *ZZZ
P *Z *ZZZ
P *Z *ZZZ
===============
```
Now you can better manage the number of zombies you're dealing with at once. Once you're done, you can get into the inner area to clean the bodies up and avoid a pile up.
There's any number of improvements which could be made to this, for example a grilled platform on top, out of arm's reach, to stab down through.
Should the inner gate fall, you only have to deal with a limited number of zombies inside the wall. Should the outer gate fail, you have an inner gate to fall back to. This brings us to our next point.
Have A Mobile Backup Gate
=========================
Taking a page from [The Road Warrior](https://www.youtube.com/watch?v=wNzfgl_H5vA#t=4m09s), use a heavy vehicle like a bus as a mobile gate. But instead of using it as your primary gate, have it ready as a mobile backup gate to close any breeches in the wall. Just drive it up to block the gap. This will plug the breech and give the defenders time to react.
Evolution 2: Dig A Pit, Fill It With Spikes
===========================================
If the Walking Dead zombies are like the Romero and Max Brooks zombies, they aren't very bright and will happily walk off a cliff if there's food on the other side.
To make our murder hole even safer, we can add a pit filled with spikes.
```
===============
P *..............*ZZZZ
P *..............*ZZZZ
P *..............*ZZZZ
P *..............*ZZZZ
P *..............*ZZZZ
===============
```
Raise the outer gate, zombies fall into the pit and get impaled. It probably won't kill them, but it will immobilize them. Then stab them with pikes at your leisure. You can even throw a grating over the top to make the stabbing even easier.
Evolution 3: The Crushinator
============================
You've got these zombies pressed up against your gate, you know where they're going to be, why not use it to your advantage? Scrape them off the gate with a heavy object.
```
|
O|
-------|v
| |
| |Z
===================
```
You have a heavy door (optionally sharp) held above and just outside the gate. Zombies press against the outer gate. Drop the door right on their heads. Crush the zombies. Lift it again. Repeat until all zombies are dead or disabled. Finish them off with pikes. Safe. Efficient. And it's a spare gate!
Don't Have A Gate
=================
Taking another page from the original *Dawn Of The Dead*, do you really need a gate? What about a ladder or ramp? Zombie attack? Retract the ladder. Just be sure you have a way of clearing the zombies off the entrance, like a set of bars to stab them through.
```
=========
|
^ |
O | - O _(Brains)
|-o - o-|
| | | |
/\ | | /\
```
Try Things Out In [*7 Days To Die*](http://7daystodie.gamepedia.com/7_Days_to_Die_Wiki)
=======================================================================================
*7 Days To Die* is a "survival, horde, crafting game". It's Minecraft meets Left4Dead. It's a great place to try out various anti-zombie defense schemes.
What sets 7D2D apart from other zombie survival games is *everything is destructible*. Wood, metal, concrete, *even the ground itself*, the zombies will chew through it all. Any passive defense will eventually be ground down and fail. I've had zombies chew through concrete, wriggle through firing ports, climb over each other like ants, tear the foundations out of platforms, and even come up through the floor!
The other thing that sets 7D2D apart is right in the title: every 7 days, ready or not, you *will* be attacked by a horde. It lends a certain time pressure to everything you do. Grand plans give way to necessity. Are you going to try to explore to find the mixings for concrete and bullets? Or chop down more trees to bodge together more spikes and arrows?
Finally, while basic combat is rather simple, getting hit is brutal. Especially at the higher difficulty levels, one hit and you're stunned, two or three and you're dead.
The game is still in early access, but it's totally playable and totally brutal. Big changes are coming in Alpha 16 in March, so you might want to wait until then. But if you want to torture test your ideas about zombie defenses, give it a shot.
Here's the aftermath of a horde night in my fortified chateau. It took the "no gate" philosophy. All stairs were torn out, even interior stairs, and replaced with ladders and armored hatches. We attracted them to a particularly well fortified corner of the house.
[](https://i.stack.imgur.com/f4qaN.jpg)
That *was* four layers of spikes. Note the firing ports for an active defense. Also note the hasty repairs on the concrete; they got through, but that was just the outer defenses. We had multiple backups to retreat to.
This was just one evolution of the defenses. |
72,387 | <p>There is a terrestrial planet called <strong>Paveiha</strong> that orbits a small Red Dwarf star. It is the third planet in a system of 10 planets. Paveiha is close enough to the Sun that it is tidally locked and the planet itself has three moons. Two small irregular moons and one major spherical moon, <strong>Jeah</strong>, which is the focus of my question.</p>
<p>I have some statistics regarding the Sun, Paveiha and Jeah below. I don't know if this is enough information to accurately answer my questions, but at least confirming my suspicions that Jeah is in a deaccelerated orbit would be enough.</p>
<p>Information on the Sun, Paveiha and Jeah.</p>
<h1>The Sun</h1>
<p><a href="https://i.stack.imgur.com/EpfgX.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/EpfgX.jpg" alt="The Sun"></a></p>
<ul>
<li>Type: Red Dwarf</li>
<li>Spectrum: M3.1 V</li>
<li>Diameter: 373,136.28km. <em>(26.8% the diameter of Earth's sun)</em></li>
<li>Mass: 0.24119 solar mass.</li>
<li>Age: 9.1 billion years.</li>
</ul>
<h1>Paveiha</h1>
<p>This map only shows the habitable (star facing) side of Paveiha. Clear white areas are water. The borders on the edges represent the beginning of the night side / icy region.
<a href="https://i.stack.imgur.com/G2XC2.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/G2XC2.jpg" alt="Map"></a></p>
<ul>
<li>Diameter: 8685.88km</li>
<li>Mass: 0.31375 Earth mass.</li>
<li>Density: 5.4628 g/cm3 </li>
<li>Axial Tilt: 0'28'30'68°</li>
<li><p>Gravity: 0.6767g </p></li>
<li><p>Perihilion: 0.07 AU</p></li>
<li>Semimajor Axis: 0.07 AU</li>
<li>Eccentricity: 0.011</li>
<li>Orbital Period: 13.958 days.</li>
<li>Orbital Speed: ?</li>
<li>Hill Sphere Radius: 113903.23km</li>
<li>Influence Sphere Radius: 72413.71km</li>
<li><p>Roche Limit: 6446.83km</p></li>
<li><p>Atmosphere Surface Pressure: 0.402atm</p></li>
<li><p>Atmospheric Composition: • 48.2% oxygen (O2)
• 41.2% carbon dioxide (CO2)
• 10.4% nitrogen (N2)
• 0.196 sulfur dioxide (SO2)</p></li>
</ul>
<h1>Jeah</h1>
<ul>
<li>Diameter: 1261.09km</li>
<li>Mass: 0.00082409 Earth mass.</li>
<li>Density: 4.7828 g/cm3 </li>
<li>Axial Tilt: 0'12'56'87</li>
<li>Gravity: 0.084319g</li>
<li>Perihilion: 17627.07km </li>
<li>Semimajor Axis: 18181.17km</li>
<li>Orbital Speed: ?</li>
<li>Eccentricity: 0.30</li>
<li>Orbital Period: 12 hours, 6 minutes, 37.31 seconds.</li>
</ul>
<h1>I have two questions regarding Paveiha and its moon, Jeah.</h1>
<p><strong>1.</strong> Is Jeah in a deaccellerated orbit? Is it possible to determine how long it will take for Jeah to collide with Paveiha or spin out of orbit? How long?</p>
<p><strong>2.</strong> How does Jeah's close orbit affect Paveiha? Would there be strong tidal forces?</p>
<p><strong><em>2.1.</strong> Would it have any effect on its oceans?</em> </p>
<p><strong><em>2.2.</strong> Could the tidal forces disrupt life?</em></p>
| [
{
"answer_id": 72395,
"author": "Atlas the Worldbuilder",
"author_id": 27889,
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"pm_score": 2,
"selected": false,
"text": "<p>Let me preface this by saying that, as a mortal, non-omnipotent being, I cannot know all ou... | 2017/02/27 | [
"https://worldbuilding.stackexchange.com/questions/72387",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/33954/"
] | There is a terrestrial planet called **Paveiha** that orbits a small Red Dwarf star. It is the third planet in a system of 10 planets. Paveiha is close enough to the Sun that it is tidally locked and the planet itself has three moons. Two small irregular moons and one major spherical moon, **Jeah**, which is the focus of my question.
I have some statistics regarding the Sun, Paveiha and Jeah below. I don't know if this is enough information to accurately answer my questions, but at least confirming my suspicions that Jeah is in a deaccelerated orbit would be enough.
Information on the Sun, Paveiha and Jeah.
The Sun
=======
[](https://i.stack.imgur.com/EpfgX.jpg)
* Type: Red Dwarf
* Spectrum: M3.1 V
* Diameter: 373,136.28km. *(26.8% the diameter of Earth's sun)*
* Mass: 0.24119 solar mass.
* Age: 9.1 billion years.
Paveiha
=======
This map only shows the habitable (star facing) side of Paveiha. Clear white areas are water. The borders on the edges represent the beginning of the night side / icy region.
[](https://i.stack.imgur.com/G2XC2.jpg)
* Diameter: 8685.88km
* Mass: 0.31375 Earth mass.
* Density: 5.4628 g/cm3
* Axial Tilt: 0'28'30'68°
* Gravity: 0.6767g
* Perihilion: 0.07 AU
* Semimajor Axis: 0.07 AU
* Eccentricity: 0.011
* Orbital Period: 13.958 days.
* Orbital Speed: ?
* Hill Sphere Radius: 113903.23km
* Influence Sphere Radius: 72413.71km
* Roche Limit: 6446.83km
* Atmosphere Surface Pressure: 0.402atm
* Atmospheric Composition: • 48.2% oxygen (O2)
• 41.2% carbon dioxide (CO2)
• 10.4% nitrogen (N2)
• 0.196 sulfur dioxide (SO2)
Jeah
====
* Diameter: 1261.09km
* Mass: 0.00082409 Earth mass.
* Density: 4.7828 g/cm3
* Axial Tilt: 0'12'56'87
* Gravity: 0.084319g
* Perihilion: 17627.07km
* Semimajor Axis: 18181.17km
* Orbital Speed: ?
* Eccentricity: 0.30
* Orbital Period: 12 hours, 6 minutes, 37.31 seconds.
I have two questions regarding Paveiha and its moon, Jeah.
==========================================================
**1.** Is Jeah in a deaccellerated orbit? Is it possible to determine how long it will take for Jeah to collide with Paveiha or spin out of orbit? How long?
**2.** How does Jeah's close orbit affect Paveiha? Would there be strong tidal forces?
***2.1.*** Would it have any effect on its oceans?
***2.2.*** Could the tidal forces disrupt life? | Simulation setup
================
I ran a simulation with your worlds in [Rebound](http://rebound.readthedocs.io/en/latest/index.html) using Python. I have my setup on github if you want to [take a look at it](https://github.com/kingledion/worldbuilding). The file is
```
orbit_noble_170301.py
```
Results
=======
I ran the integrator a few times with different time steps. For dt = ~12 hours, Jeah immediately left orbit of Paveiha and fell into orbit around the main star. Then after 4200 years, it had a close encounter with Paveiha and the last I was tracking it, it was about 0.7 light years away from the star and going fast.
I switched up the time steps and did some other modifications (not of the orbital parameters) but it never took more than a couple thousand years for Jeah to get ejected.
My thesis is that Jeah is just too light. Paveiha is 3 Mars's or half a Venus, but Jeah is a relatively puny Titania or Haumea size. It is about 1/20th the size of our moon. I was guessing that it was just too small; given that it wouldn't stay in orbit of the main plant (too close to the star I'm guessing), it was too light to stick around in the solar system.
So I tried increasing the size of Jeah by a factor of 10. This was a little better. Instead of getting ejected it tended to settle out in an orbit at around 12 AU (hope there's no gas giants!).
Conclusion
==========
I could not find a stable orbit for Jeah around Paveiha. I didn't even have to try integrating millions of years overnight; Jeah got stripped from the planet into an orbit around the star in a few decades.
If you want to give this a try by yourself, try to add yourself at my github and then we can talk there. I can try to help you set up rebound yourself, if I have the time. |
72,458 | <p>The main trait of my story originates from a village in what's now the Belgian city of Tongeren, around 1000 BC in our timeline. Anyone born there after that trait arrived will have the trait, as will their children, recursively, regardless of where they are born. The trait doesn't have a single Patient Zero like Mitochondrial Eve or comparable people, but rather that everyone born in that village after the date the trait started appearing has the trait.</p>
<p>In the backstory, the Belgian empire that sprung from this city gradually takes control of Earth, with Europe being fully theirs in 500 BC, The Middle East around 1 AD, Africa and the rest of Asia at 500 AD, the Americas at around 1000 AD and the remaining landmasses of Earth at around 1200 AD, with tech being roughly at our level at around 1400 AD. These are rough estimates that aren't fully established yet, but the idea is that in 2050 AD, the Belgian Empire has developed interstellar travel, contacted and befriended other aliens and is a relatively new player at the galactic table.</p>
<p>Judging by the above estimates, how likely would it be for humans WITHOUT this trait to exist and be adults in 2050 AD?</p>
<hr>
<p>information requested in comments:</p>
<ul>
<li><p>the trait always gets passed to the descendants and is always active. The trait doesn't directly increase survival through resistances or similar, but it does indirectly increase survival by providing the affected party with additional inherited knowledge, increased mental acuity and being able to use senses remotely. There are ways to lose personal access to the trait, but it doesn't affect how the trait gets passed on.</p></li>
<li><p><strong>the trait is not genetic in nature!</strong> I see many people assume it's genetics and thus obeys the normal Survival of the Fittest criteria where it only gets passed on if the trait is beneficial for survival. The trait is not dependent on the genes of either the mother or the father and will always be passed on to any children of the person affected.</p></li>
<li><p>The empire achieved global dominance through a mix of diplomacy and military strength. Where possible, countries were annexed through treaties, royal marriages and other nonviolent means. when the empire is attacked, the offending nation is conquered, although this is mostly happened in the pre-BC days, when the Romans invaded from Italy and were conquered.</p></li>
</ul>
| [
{
"answer_id": 72470,
"author": "Willk",
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"pm_score": 2,
"selected": false,
"text": "<p>The genetics underlying this story point to your space empire being a culture of genocidal matriarchal witch... | 2017/02/28 | [
"https://worldbuilding.stackexchange.com/questions/72458",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/227/"
] | The main trait of my story originates from a village in what's now the Belgian city of Tongeren, around 1000 BC in our timeline. Anyone born there after that trait arrived will have the trait, as will their children, recursively, regardless of where they are born. The trait doesn't have a single Patient Zero like Mitochondrial Eve or comparable people, but rather that everyone born in that village after the date the trait started appearing has the trait.
In the backstory, the Belgian empire that sprung from this city gradually takes control of Earth, with Europe being fully theirs in 500 BC, The Middle East around 1 AD, Africa and the rest of Asia at 500 AD, the Americas at around 1000 AD and the remaining landmasses of Earth at around 1200 AD, with tech being roughly at our level at around 1400 AD. These are rough estimates that aren't fully established yet, but the idea is that in 2050 AD, the Belgian Empire has developed interstellar travel, contacted and befriended other aliens and is a relatively new player at the galactic table.
Judging by the above estimates, how likely would it be for humans WITHOUT this trait to exist and be adults in 2050 AD?
---
information requested in comments:
* the trait always gets passed to the descendants and is always active. The trait doesn't directly increase survival through resistances or similar, but it does indirectly increase survival by providing the affected party with additional inherited knowledge, increased mental acuity and being able to use senses remotely. There are ways to lose personal access to the trait, but it doesn't affect how the trait gets passed on.
* **the trait is not genetic in nature!** I see many people assume it's genetics and thus obeys the normal Survival of the Fittest criteria where it only gets passed on if the trait is beneficial for survival. The trait is not dependent on the genes of either the mother or the father and will always be passed on to any children of the person affected.
* The empire achieved global dominance through a mix of diplomacy and military strength. Where possible, countries were annexed through treaties, royal marriages and other nonviolent means. when the empire is attacked, the offending nation is conquered, although this is mostly happened in the pre-BC days, when the Romans invaded from Italy and were conquered. | Estimating the spread within a population
=========================================
Initially, one person has this trait. Assuming it is passed on each time, to children of either sex (which it seems like you are implying) then we can estimate the number of generations it would take for everyone in a population of size $x$ assuming anyone in the population is equally likely to intermarry with and reproduce with anyone else.
When there are $t$ people with the trait, each of $x-t$ people who do not have the trait in the intermarrying group, have a $t$ in $x-1$ chance of marrying someone with the trait.
Thus for the first generation, $t=1$ and lets say $x=100$, $$(x-t)\frac{t}{x-1} = (99)\frac{1}{99} = 1$$ more person will gain the trait in the next generation. This is because this simple model assumes the population stays constant, and every two people have two offspring. Thus the one trait-haver has two children, so the second generation has two trait-havers.
Applying this function (with a little python script), we can calculate the number of generations it takes for this trait to spread through 90% of a population:
```
Pop Size Generations
100 9
1000 13
10000 16
100000 19
1000000 23
10 billion 36
```
Estimating the spread between populations
=========================================
That last assumption is probably not the best for a lot of reasons, but mostly, it should be good enough. Where it breaks down is in population transfer between groups. How well do people spread between groups?
This is very much an open question. While it is very much not hard to imagine some trait-haver captured and sold into slavery in the Middle East and spreading the genes there, it is much more difficult to imagine that trait going to China.
Your history will have to give us a clue. If this Empire did expand around the world, then there is a good chance that the conquering population distributed their DNA through various conquered populations by various means.
In that case, it takes 36 generations for such a trait to spread among 90% of 10 billion people. Assuming a 25 year generation, that is about 900 years. Since it only takes 4 more generations to get from 90% to near 100%, it is a good bet the whole world has this trait.
If we start with a million Belgians conquering the known world in 1400 AD, then it will take 14 generations to pass on to 10 billion people, or 350 years. So again, everyone in the world should have this trait by 2050 AD.
Conclusion
==========
If this trait is beneficial, and there isn't some caste-system keeping the conquering Belgians from interbreeding with the lesser conquered, then it is reasonable to assume that this trait will spread to the entire world population soon after the Belgians complete their world conquest. |
73,073 | <p>We're starting off with a Japanese mythical creature, the <a href="https://en.wikipedia.org/wiki/Yuki-onna" rel="noreferrer">Yuki-Onna</a>. Now the specifics of this being vary quite a bit from one tale to another, so let me be specific what this being is about. Keep in mind that this is <strong>my</strong> version, and may therefore deviate from popularly held versions.</p>
<p>Yuki-onna are ghosts of women who died during snowstorms. They're beings that begin being corporeal but can learn to 'phase through' other things (temporarily becoming incorporeal). They are essentially frozen corpses, so their core temperatures are well below -50 degrees Centigrade. Their lungs are filled with air of that same temperature, so they don't have 'ice breath', they just cool the air as they breathe out. Their diets and circadian rhythm is unimportant for this question, so I'll skip that.</p>
<p>What I want to know is: how are they affected by a fireball type spell? Say they breathe in the flames, does the temperature of the fireball affect whether they 'melt'?</p>
<p>The problem I am having is <a href="https://www.youtube.com/watch?v=ILA1ic-Q8_E" rel="noreferrer">this</a>. Ice (frozen water particles) should melt in layers, which would then need even more energy (heat) to vaporize. So, in theory, Fire shouldn't be 'super effective' against ice. It would take too long to be effective. </p>
<p>So, if I hazard a guess, I would say that there would be a insulating layer of ice on the skin of the Yuki-Onna. The flames would first have to get through this layer (via the same ineffective methods of heat transference), before melting and burning through skin, then blood, internal organs, etc. </p>
<p>Would fire therefore be the most effective method to combat beings of this nature? Or would the airways allow for the heat to circulate into the core and heat up quicker? </p>
| [
{
"answer_id": 73085,
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"text": "<p>I'm not certain a fireball would do much more than surface damage to a creature like this in most instan... | 2017/03/05 | [
"https://worldbuilding.stackexchange.com/questions/73073",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/23068/"
] | We're starting off with a Japanese mythical creature, the [Yuki-Onna](https://en.wikipedia.org/wiki/Yuki-onna). Now the specifics of this being vary quite a bit from one tale to another, so let me be specific what this being is about. Keep in mind that this is **my** version, and may therefore deviate from popularly held versions.
Yuki-onna are ghosts of women who died during snowstorms. They're beings that begin being corporeal but can learn to 'phase through' other things (temporarily becoming incorporeal). They are essentially frozen corpses, so their core temperatures are well below -50 degrees Centigrade. Their lungs are filled with air of that same temperature, so they don't have 'ice breath', they just cool the air as they breathe out. Their diets and circadian rhythm is unimportant for this question, so I'll skip that.
What I want to know is: how are they affected by a fireball type spell? Say they breathe in the flames, does the temperature of the fireball affect whether they 'melt'?
The problem I am having is [this](https://www.youtube.com/watch?v=ILA1ic-Q8_E). Ice (frozen water particles) should melt in layers, which would then need even more energy (heat) to vaporize. So, in theory, Fire shouldn't be 'super effective' against ice. It would take too long to be effective.
So, if I hazard a guess, I would say that there would be a insulating layer of ice on the skin of the Yuki-Onna. The flames would first have to get through this layer (via the same ineffective methods of heat transference), before melting and burning through skin, then blood, internal organs, etc.
Would fire therefore be the most effective method to combat beings of this nature? Or would the airways allow for the heat to circulate into the core and heat up quicker? | >
> *The problem I am having is this. Ice (frozen water particles) should melt in layers, which would then need even more energy (heat) to vaporize. So, in theory, Fire shouldn't be 'super effective' against ice. It would take too long to be effective.*
>
>
>
What you're describing is [ablative armor](https://en.wikipedia.org/wiki/Ablative_armor) where the protection comes from the armor eroding away. This is used on [real spacecraft as a heat shield](https://en.wikipedia.org/wiki/Ablative_heat_shield) (just not made of water).
[](https://i.stack.imgur.com/W5R9z.jpg)
Ablative armor works by carrying away the energy of the attack in lots of tiny fragments. A microscopic outer layer heats up, vaporizes, and is blown way taking the energy along with it. Water works fairly well at this because it has a very high [specific heat](https://en.wikipedia.org/wiki/Specific_heat_capacity), meaning the amount of energy needed to raise its temperature: 4.2 J to raise 1 gram of liquid water by 1 C. [Ice is about 1.9 J/g/C](http://www.engineeringtoolbox.com/ice-thermal-properties-d_576.html).
Phase changes also take energy. Going from water ice to a liquid water takes 333 J/g. From liquid water to vapor is a whopping 2257 J/g. This is why we still use steam to turn generators, it contains a lot of energy. This is also why steam scalds are so bad.
So to take 1g of -50 C ice to 100 C water vapor takes...
```
-50 C -> 0 C | 50 C * 1.9 J | 95 J
Solid -> Liquid | 333 J | 333 J
0 C -> 100 C | 100 C * 4.2 J | 420 J
Liquid -> Gas | 2257 J | 2257 J
-------------------------------------------------
Total 3105 J
```
That is roughly 1 [Watt-hour](https://en.wikipedia.org/wiki/Kilowatt_hour) (ie. 1 Watt for 1 hour or 60 W for 1 minute) or [roughly the kinetic energy of an Olympic hammer throw](https://en.wikipedia.org/wiki/Orders_of_magnitude_(energy))... for ablating a single gram of -50 C ice.
To put that in perspective another way, [a typical stovetop burner uses 1500 J/s](http://energyusecalculator.com/electricity_stovetop.htm) and so could ablate 1 gram of -50 C ice every 2 seconds. This is why boiling water on a stovetop takes so long.
---
The problem with ablative armor is its protection eventually wears out. The question then becomes how much energy does this fire attack have? Does it have enough to ablate all the ice? If so then their goose is cooked. If not, then they'll be -- mostly -- fine.
A quick puff of flame isn't going to do more than vaporize the outer layer of frost; and if their chill is magical it will rebuild that layer with water vapor from the surrounding air. While a sustained flame will wear away the layer of ice and start scorching flesh and presumably doing damage.
So really fire against a frost being would be very ineffective until all the ablative ice vaporizes, then it's just as effective as fire is on flesh. If you're playing an RPG this could be modeled as a pool of HP that absorbs fire attacks and slowly replenishes itself. When it's gone, fire does full damage. |
73,432 | <p>In the anime <a href="https://en.wikipedia.org/wiki/RWBY" rel="nofollow noreferrer">RWBY</a> most characters have crazy weapons with multiple forms, like a <a href="http://rwby.wikia.com/wiki/Crescent_Rose" rel="nofollow noreferrer">scythe, that’s also a gun</a>, or a <a href="http://rwby.wikia.com/wiki/Ember_Celica" rel="nofollow noreferrer">gauntlet, that’s also a gun</a> or a <a href="http://rwby.wikia.com/wiki/Qrow's_Weapon" rel="nofollow noreferrer">sword, that’s also a scythe AND a gun</a>! </p>
<p>But the weapon I find the most fascinating is a <a href="http://rwby.wikia.com/wiki/Cinder's_Weapon" rel="nofollow noreferrer">bow that's also two one-handed swords</a>. </p>
<p><strong>I was wondering if it is possible to create a bow that can be reassembled, so that you would get two one-handed swords.</strong></p>
<p>Things I think about that might be difficult:</p>
<ul>
<li><p>A bow has to be able to bend quite a lot to allow to pull the string and make your arrow fly. What material could allow swords to bend enough to make them a viable component of the bow?</p></li>
<li><p>How fast could you switch between the weapon-types? Would you be able to quickly make two swords to fight in melee combat if someone is running towards you?</p></li>
<li><p>Where do you store your arrows? They should be easily accessible but at the same time not prevent you from fighting with the swords.</p></li>
<li><p>How much would this bow weigh? The swords need a certain weigh for melee combat, but they shouldn’t be too heavy, as you have to wield two of them. </p></li>
<li><p>Where do you attach the string?</p></li>
</ul>
<p>Of course in the anime the "rule of cool" applies to a lot of things, but would you actually be able to fight with such a weapon?</p>
<p>Because of all these problems I came up with this question:</p>
<p>Can you create such a weapon with current day technology? And if you can create such a weapon: <strong><em>How</em> would you realistically create a bow that can be reassembled so that you can fight with two one-handed swords?</strong></p>
| [
{
"answer_id": 73441,
"author": "L.Dutch",
"author_id": 30492,
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"selected": false,
"text": "<p>These steps may help (no numbers provided):</p>\n\n<ol>\n<li>Engineer your blade so that it is stiff when ... | 2017/03/09 | [
"https://worldbuilding.stackexchange.com/questions/73432",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/28789/"
] | In the anime [RWBY](https://en.wikipedia.org/wiki/RWBY) most characters have crazy weapons with multiple forms, like a [scythe, that’s also a gun](http://rwby.wikia.com/wiki/Crescent_Rose), or a [gauntlet, that’s also a gun](http://rwby.wikia.com/wiki/Ember_Celica) or a [sword, that’s also a scythe AND a gun](http://rwby.wikia.com/wiki/Qrow's_Weapon)!
But the weapon I find the most fascinating is a [bow that's also two one-handed swords](http://rwby.wikia.com/wiki/Cinder's_Weapon).
**I was wondering if it is possible to create a bow that can be reassembled, so that you would get two one-handed swords.**
Things I think about that might be difficult:
* A bow has to be able to bend quite a lot to allow to pull the string and make your arrow fly. What material could allow swords to bend enough to make them a viable component of the bow?
* How fast could you switch between the weapon-types? Would you be able to quickly make two swords to fight in melee combat if someone is running towards you?
* Where do you store your arrows? They should be easily accessible but at the same time not prevent you from fighting with the swords.
* How much would this bow weigh? The swords need a certain weigh for melee combat, but they shouldn’t be too heavy, as you have to wield two of them.
* Where do you attach the string?
Of course in the anime the "rule of cool" applies to a lot of things, but would you actually be able to fight with such a weapon?
Because of all these problems I came up with this question:
Can you create such a weapon with current day technology? And if you can create such a weapon: ***How* would you realistically create a bow that can be reassembled so that you can fight with two one-handed swords?** | Is it possible? Yes, but not the way you think it will be.
Theoretically, you could create the weapon you're describing by designing a "hybrid" weapon.
We can avoid some of the things you think are difficult by designing the weapon as such:
```
/| |\ /| and |\ represent the two blades of sword
||[]|| || ||
||[]||
||[]|| - Sword sections are actually 2 outer normal blades
||[]|| - Middle section of sword "[]" is one limb of a bow.
||[]|| - "M"s represent a locking mechanism in the hilts to allow
||[]|| the joining of the two swords into a single bow
||[]|| - Hilt and guard of the sword are normal
||[]|| - String can be attached through top of limb
||[]||
||[]||
||[]||
||[]||
|============| <--- guard
{}
{}
{}
{}
WWWW <------ Stores arrows
MMMM <------ Connecting spot, doubles as potential arrow rest
WWWW
{}
{}
{}
{}
|============| <--- guard
||[]||
||[]||
||[]||
||[]||
||[]||
||[]||
||[]||
||[]||
||[]||
||[]||
||[]||
||[]||
\| |/
```
String can be designed to be stored INSIDE the limb of the bow
pulled out and connected together, like so:
```
-------------[Locking mechanism][Locking mechanism]-------------
^
String
```
Basically, to answer your points:
* The sword parts don't bend (when pulling on the bowstring) - only the center, the limb part of the sword bends
* Assuming you designed the hilt locking mechanism properly, you could simply twist the swords 180 degrees to unlock and create 2 swords.
* This weapon shouldn't weigh much more than a normal sword. The limb used in the center of the weapon should overall cause the sword to be lighter than normal, since a large chunk of the metal will be gone.
* Done properly, you would be able to store 1 or 2 folding arrows in each hilt section. Carving out a section of the handle and hiding it in there is also an option.
* String attaches via Limbs
**Would you be able to fight with this weapon? Yes, however there are some important things to note.**
Note 1: Limited ammunition with regards to shooting arrows. Severely so, unless you carry extra arrows on a belt or something.
Note 2: Some fighting styles use the flat of the blade to block blows - this will damage your bow, and generally it's a bad idea to block with the edge of the blade as well, which means the defensive component of the fighting style of this sword user will likely need to be dodging and positioning based rather than parry based.
Note 3: This weapon does not make a good stabbing weapon. Slashing only please - curved blades can help with this.
Note 4: The bow mode won't look like a bow until you pull back the string, due to the way the string is notched and rests along the sword. It may end up looking like this from the side when pulled.
```
| /!
|/ ! | represents the blade
<-------! ! represents string
|\ ! <------ represents arrow
| \!
Note that since the middle of the blade is the limb, when firing as a bow
the flat of the blades will be facing towards you and the target. It
should look almost like a + shape when taking the guard into account.
```
Note 4: The string can lock using a similar twist and turn mechanism, which can double as an easy arrow nocking point.
Note 5: When using this in bow mode, your hand will likely be holding the bottom handle, since the middle section is where your arrow rest will be.
Note 6: This sword/bow hybrid is not going to be as good a sword or as good a bow when compared to a normal sword or bow. It is simply impossible to get the best of both worlds in a single weapon.
**ALTERNATIVE METHOD:**
You can use a double scimitar, and simply design the tip of the scimitar to allow string threading.
The sword still won't bend, however - instead, you'd want to put some springs between the guard of the sword and the hilt. This allows, when the swords are put together, for the springs to provide the power and the sword blades to become the limbs of the sword, almost like how a power spring bow would work.
However, you may have some issues with slashing depending on how stiff the springs are.
This method also doesn't seem as cool/original. |
77,819 | <p>I had a talk with my friend about limitless.</p>
<p>Imagine if we had a drug that</p>
<pre><code>Increases intelligence
Increases success
No side effect or no side effect
Makes people more creative
</code></pre>
<p>Would it be legal?</p>
<p>Most people would agree that it would be illegal. That's because most humans don't really care about the dangers of a drug if something gives relative advantage over some other thing.</p>
<p>Another group of people would say it would be legal. I mean, it's harmless.</p>
<p>What would actually happen?</p>
| [
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"pm_score": 4,
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"text": "<p>The first country that adds it to their water supply would gain a large boost. With no side effects it wil... | 2017/04/11 | [
"https://worldbuilding.stackexchange.com/questions/77819",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/16350/"
] | I had a talk with my friend about limitless.
Imagine if we had a drug that
```
Increases intelligence
Increases success
No side effect or no side effect
Makes people more creative
```
Would it be legal?
Most people would agree that it would be illegal. That's because most humans don't really care about the dangers of a drug if something gives relative advantage over some other thing.
Another group of people would say it would be legal. I mean, it's harmless.
What would actually happen? | The first country that adds it to their water supply would gain a large boost. With no side effects it will be widely used by anyone that can afford it. Some will object but with no side effects they barely have any arguments. |
77,856 | <p>After playing some <a href="http://tvtropes.org/pmwiki/pmwiki.php/VideoGame/HyperRogue" rel="nofollow noreferrer">HyperRogue</a>, I got interested in the use of <a href="https://en.wikipedia.org/wiki/Hyperbolic_geometry" rel="nofollow noreferrer">hyperbolic geometry</a> in WorldBuilding, in particular how an area grows exponentially with respect to its radius.</p>
<p>Let's say that the universe is a <a href="https://en.wikipedia.org/wiki/Hyperbolic_space" rel="nofollow noreferrer">hyperbolic space</a>. The world itself is a disc with a radius of 30 miles and an area with 196.9 million square miles. This would mean that you can get anywhere within an hour if you travel in a straight line at 60 mi/hr, and the area is as large as the surface area of our whole entire earth!</p>
<p>This world is necessarily non-euclidean, of course, since it has negative curvature. The angles of triangles will add up to less than 180 degrees, for example. It will appear euclidean at sufficiently small scales though (the angles of the triangles will add up to only slightly less than 180 degrees). It will be noticeable at large scales (the sum of a triangles angles will be close to 0 degrees).</p>
<p>My question is, at what scales will the negative curvature of the space be noticeable to humans? Will the non-euclidean geometry only be relevant to a world traveler, or would an artist have to be familiar with it while painting, or somewhere in between? (If you wish to add flavor to your answer, you can present it as problems for the <em>flat space society</em>, which denies the reality of non-euclidean geometry).</p>
| [
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"text": "<p>Your answer depends on what is meant by “notice”.</p>\n\n<p>Consider a parking lot. Perhaps a pedestrian won... | 2017/04/11 | [
"https://worldbuilding.stackexchange.com/questions/77856",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/8914/"
] | After playing some [HyperRogue](http://tvtropes.org/pmwiki/pmwiki.php/VideoGame/HyperRogue), I got interested in the use of [hyperbolic geometry](https://en.wikipedia.org/wiki/Hyperbolic_geometry) in WorldBuilding, in particular how an area grows exponentially with respect to its radius.
Let's say that the universe is a [hyperbolic space](https://en.wikipedia.org/wiki/Hyperbolic_space). The world itself is a disc with a radius of 30 miles and an area with 196.9 million square miles. This would mean that you can get anywhere within an hour if you travel in a straight line at 60 mi/hr, and the area is as large as the surface area of our whole entire earth!
This world is necessarily non-euclidean, of course, since it has negative curvature. The angles of triangles will add up to less than 180 degrees, for example. It will appear euclidean at sufficiently small scales though (the angles of the triangles will add up to only slightly less than 180 degrees). It will be noticeable at large scales (the sum of a triangles angles will be close to 0 degrees).
My question is, at what scales will the negative curvature of the space be noticeable to humans? Will the non-euclidean geometry only be relevant to a world traveler, or would an artist have to be familiar with it while painting, or somewhere in between? (If you wish to add flavor to your answer, you can present it as problems for the *flat space society*, which denies the reality of non-euclidean geometry). | Using [this formula](https://en.wikipedia.org/wiki/Hyperbolic_geometry#Circles_and_disks) we can calculate the curvature $$K \approx -0.313339 \text{ per mi}^2$$
Using this, we can the radius of a Euclidean disk v.s. a disk in this world.
```
Area Euclidean Radius Actual Radius
---------------- ------------------ ---------------
1 mi^2 0.56 mi 0.56 mi
10 mi^2 1.78 mi 1.72 mi
100 mi^2 5.64 mi 4.42 mi
1000 mi^2 17.84 mi 8.26 mi
10000 mi^2 56.42 mi 12.34 mi
100000 mi^2 178.41 mi 16.44 mi
1000000 mi^2 564.19 mi 20.56 mi
196900000 mi^2 7916.77 mi 30.00 mi
```
This means that over the size of a building, distortion will not be noticeable. In a small town, probably only builders will notice. In a small city, everyone will start to notice, but it will still be mostly Euclidean. In a bigger city, the curvature will be quite noticeable, and people will have to take into account if they do not want to get lost. At the size of countries, you will need to follow a navigation system very carefully if you want to get to the right place, and it will very non-euclidean. |
79,003 | <p>First of all, this website is a dream come true. I'm a total sucker for this stuff.</p>
<p>Secondly, I love astronomy and worldbuilding, and lately, I've been thinking of a hypothetical situation, and was wondering if such a thing was actually possible.</p>
<p>A planet orbits a gas giant. Let's say (for reference's sake) the gas giant is Jupiter, and the planet is Earth. Earth is tidally locked to the gas giant, and has a rotational period of exactly one year. However, let's say it also orbits around Jupiter in exactly one year as well, which means that the planet is cooked on its surface for a while and then vanishes into total freezing darkness behind Jupiter every 6 months, give or take.</p>
<p>This itself is doable. However, would it be possible if Earth was still located rather close to Jupiter, in a way for Jupiter to still <a href="http://3.bp.blogspot.com/-pw8qysjJD-M/TrxIa7Vt1NI/AAAAAAAAAKU/Ohv720hScuM/s1600/RingsFromSurface2.jpg" rel="noreferrer">dominate the sky</a> (yes, I know that's not Jupiter)? </p>
<p>Of course, it depends on where you're standing on hypothetical Earth to see hypothetical Jupiter, but in this case, we're standing in the right place to expect a giant planet to cover most of our sky. But gas giants' moons orbit around them incredibly fast because they're so close and they have such a strong gravitational pull, which creates a problem, because the ideal orbit here is a slow trip around.</p>
<p>Would other factors be able to slow down the planet's course around this imaginary gas giant and create this situation, such as other moons or planets, size of the planets in question, density of either planey, rings around the gas giant, etc., without the planet being pulled into this gas giant?</p>
<p>We can ignore the more technical things, like the radiation belt around gas giants and whatnot. The most basic question is if an orbit such as this is feasible. I'm asking for a world that's not Jupiter or Earth, so anything goes if it makes it possible- as long as a big gas giant has a moon.</p>
<p>I've ran this through my head a lot, searched for answers, and even bought and messed around in Universe Simulator 2 a little (but it's more fun to blow up planets), and still haven't been able to come up with much of a solution. I'd hope that with the right blend of factors, this would be possible, but I'm not too sure on how this could play out.</p>
| [
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"text": "<p>No.</p>\n\n<p>An orbit is elliptic (instead of linear as Newton's First Law predicts) because the planet is ... | 2017/04/24 | [
"https://worldbuilding.stackexchange.com/questions/79003",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/37399/"
] | First of all, this website is a dream come true. I'm a total sucker for this stuff.
Secondly, I love astronomy and worldbuilding, and lately, I've been thinking of a hypothetical situation, and was wondering if such a thing was actually possible.
A planet orbits a gas giant. Let's say (for reference's sake) the gas giant is Jupiter, and the planet is Earth. Earth is tidally locked to the gas giant, and has a rotational period of exactly one year. However, let's say it also orbits around Jupiter in exactly one year as well, which means that the planet is cooked on its surface for a while and then vanishes into total freezing darkness behind Jupiter every 6 months, give or take.
This itself is doable. However, would it be possible if Earth was still located rather close to Jupiter, in a way for Jupiter to still [dominate the sky](http://3.bp.blogspot.com/-pw8qysjJD-M/TrxIa7Vt1NI/AAAAAAAAAKU/Ohv720hScuM/s1600/RingsFromSurface2.jpg) (yes, I know that's not Jupiter)?
Of course, it depends on where you're standing on hypothetical Earth to see hypothetical Jupiter, but in this case, we're standing in the right place to expect a giant planet to cover most of our sky. But gas giants' moons orbit around them incredibly fast because they're so close and they have such a strong gravitational pull, which creates a problem, because the ideal orbit here is a slow trip around.
Would other factors be able to slow down the planet's course around this imaginary gas giant and create this situation, such as other moons or planets, size of the planets in question, density of either planey, rings around the gas giant, etc., without the planet being pulled into this gas giant?
We can ignore the more technical things, like the radiation belt around gas giants and whatnot. The most basic question is if an orbit such as this is feasible. I'm asking for a world that's not Jupiter or Earth, so anything goes if it makes it possible- as long as a big gas giant has a moon.
I've ran this through my head a lot, searched for answers, and even bought and messed around in Universe Simulator 2 a little (but it's more fun to blow up planets), and still haven't been able to come up with much of a solution. I'd hope that with the right blend of factors, this would be possible, but I'm not too sure on how this could play out. | A 1 year long orbit around Jupiter does not work
================================================
Orbital mechanics is actually pretty straightforward mathematically. There are rigidly defined formulas controlling what can and cannot happen.
The formula for distance of the less massive body (Earth) from the more massive body (Jupiter) [is given by](https://en.wikipedia.org/wiki/Orbital_period#Small_body_orbiting_a_central_body)
$$a = \left(\frac{GMT^2}{4\pi^2}\right)^{1/3}$$
where $GM$ is the standard gravitational parameter of Jupiter ($1.27\times10^{17}\text{ m}^3\text{s}^{-2}$); and T is the desired orbital period (1 year = $3.15\times10^{7}\text{ s}$). Plug those numbers in and we get about 15 million km.
First off, this is not going to work for your desired 'closeness' to Jupiter. Jupiter has a radius of about 70 000 km. Using simple trigonometry, an object that is 140 000 km across at a distance of 15 million km occupies
$$\arctan\left(\frac{140 000}{15000000}\right) = 0.00933 \text{ radians}$$
of arc, equal to about 32 minutes of arc. By comparison, the moon is from 29 to 34 minutes of arc; Jupiter will appear about the same size in the sky than our moon appears to us, in this situation.
Secondly, the existing Galilean moons range from 0.42 million km (Io) to 1.89 million km (Callisto). Large moons do not exist that far from planets, at least not in our solar system. I can offer you this chart for the most distant moon from one of our Gas Giants with a mass with order of magnitude X.
```
X Moon Distance
18 Sycorax (Uranus) 12 179 000 km
19 Nereid (Neptune) 5 513 818 km
20 Iapetus (Saturn) 3 560 820 km
21 Iapetus (Saturn) 3 560 820 km
22 Callisto (Jupiter) 1 882 709 km
23 Callisto (Jupiter) 1 882 709 km
```
As you can see, you just don't get large moons that far out. Jupiter's largest moon at 15 million km or greater is about 60 km across. The moral of this story is that it is likely an object as massive as the Earth (50 times again more massive than any Moon) would not stay stable in an orbit that far from a gas giant in a busy solar system.
Conclusion
==========
You can use that orbital period equation (and others in the Wikipedia link) to help determine how to make your planets orbital characteristics more like what you want.
I would advise trying to make the Gas giant even bigger, there are planets out there 10 times the size of Jupiter. Just be sure to [keep the mass of the gas giant under ~0.08 solar masses](https://en.wikipedia.org/wiki/Stellar_mass), which is the point at which the giant could ignite into a star itself ([Jupiter itself is just under 0.001 solar masses](https://en.wikipedia.org/wiki/Jupiter)).
---
EDIT - As @Tradeylouish points out in the comments, even if you made the 'Jupiter' bigger, the increase in mass would cause the distance required for an object to be in a 1 year orbit to increase proportionally; the result would be that the 'Jupiter' would stay approximately the same size in the sky.
I was suggesting that the 'Jupiter' be made bigger to help clear the space around it, allowing it to hold onto a satellite at such a long distance. However, this will not help your planet appear massive in the sky.
@Tradeylouish's suggestion about density is the way to go if you want the planet to be huge in the sky (though it won't necessarily help keep the satellite in a far away orbit). Density of gas giants a can be pretty low apparently; check out [TrES-4b](https://en.wikipedia.org/wiki/TrES-4b) ([no relation](https://worldbuilding.stackexchange.com/users/11049/tres-2b)) which has about the mass of Jupiter but a density of 200 kg/m$^2$...about the same as balsa wood. |
79,048 | <p>I am creating my own Sci-Fi military that has its own unique rank structure, however I am trying to make it comparable to real world, modern military forces. I am also combining all branches into a single force, so obviously the overlap is going to skew things a bit. </p>
<p>That said, I'm having trouble finding info on how an individual's rank actually affects what they have authority over (other than anyone with a lower rank). The most I am really finding on my own is requirements to captain a ship. </p>
<h2>Main points:</h2>
<h2>1) Is their a way to identify and create tiers of responsibilities that would be common among at least a few modern militaries?</h2>
<h2>2) If yes, what would those logical tiers be?</h2>
<h2>3) Are there any resources that cover this topic?</h2>
<p>Anyone that could make this more clear or even direct me to a resource that can explain in more detail would be greatly appreciated. A few examples of things I am trying to find out are: </p>
<ul>
<li>Is there a certain rank you have to be to head a fire team?
<ul>
<li>Or fighter squadron? </li>
</ul></li>
<li>Do you have to have a minimum rank to be a deck chief (Officer of the Deck)?
<ul>
<li>Or do you get a new rank for becoming deck chief? </li>
</ul></li>
<li>Is it all up to the CO's whim?</li>
</ul>
<p>Not limiting to US military either as many of the changes in structure I have made are directly to reflect some differences in military forces internationally. I am also interested in any comparisons between forces that might consider positions to have a different level of importance.</p>
<hr>
<p>Edit: Rolled backed some changes made and tried to more clearly state intent. Clarified that by 'deck chief' I mean 'Officer of the Deck'.</p>
<p>Edit: Added main points.</p>
| [
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"text": "<h1>There is a big difference between now (peace) and then (war)</h1>\n\n<p>First, this question fluctuate... | 2017/04/24 | [
"https://worldbuilding.stackexchange.com/questions/79048",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/34793/"
] | I am creating my own Sci-Fi military that has its own unique rank structure, however I am trying to make it comparable to real world, modern military forces. I am also combining all branches into a single force, so obviously the overlap is going to skew things a bit.
That said, I'm having trouble finding info on how an individual's rank actually affects what they have authority over (other than anyone with a lower rank). The most I am really finding on my own is requirements to captain a ship.
Main points:
------------
1) Is their a way to identify and create tiers of responsibilities that would be common among at least a few modern militaries?
-------------------------------------------------------------------------------------------------------------------------------
2) If yes, what would those logical tiers be?
---------------------------------------------
3) Are there any resources that cover this topic?
-------------------------------------------------
Anyone that could make this more clear or even direct me to a resource that can explain in more detail would be greatly appreciated. A few examples of things I am trying to find out are:
* Is there a certain rank you have to be to head a fire team?
+ Or fighter squadron?
* Do you have to have a minimum rank to be a deck chief (Officer of the Deck)?
+ Or do you get a new rank for becoming deck chief?
* Is it all up to the CO's whim?
Not limiting to US military either as many of the changes in structure I have made are directly to reflect some differences in military forces internationally. I am also interested in any comparisons between forces that might consider positions to have a different level of importance.
---
Edit: Rolled backed some changes made and tried to more clearly state intent. Clarified that by 'deck chief' I mean 'Officer of the Deck'.
Edit: Added main points. | For modern armies, the basic ranks, understood by everybody, are as follows (shamelessly copied from [Wikipedia](https://en.wikipedia.org/wiki/Division_(military))):
```
Typical units Typical numbers Typical commander
---------------- --------------- -------------------------------
fireteam 3–4 corporal
squad or section 8–12 sergeant
platoon 15–30 lieutenant
company 80–150 captain or major
battalion or cohort 300–800 lieutenant colonel
regiment or brigade 2,000–4,000 colonel or brigadier general
division or legion 10,000–15,000 major general
corps 20,000–40,000 lieutenant general
field army 80,000+ general
army group 2+ field armies field marshal or five-star general
region/theater 4+ army groups six-star rank or head of state
```
From the level of battalion onwards units tend to have their own specialized administrative and support personnel, composed of enlisted men and non-commissioned officers; from the level of regiment onwards units tend to have a *general staff*, populated with officers, NCOs and enlisted men. Medics and medical personnel are attached to units from battalion onwards.
As I understand it, in the U.S.A. and many western countries there is a perfectly professional and respectable carreer track for NCOs, distinct from the carreer track of officers; in the former Warsaw Pact, and maybe even today in Russia, I don't know, this was restricted to the higher ranking NCOs, say from the equivalent of a sergeant 1st class (OR-7) onwards; lower ranking NCOs (sergeants and staff sergeants, OR-5 and OR-6) were enlisted men.
There is most usually a third separate carreer track for technical personnel, called [*warrant officers*](https://en.wikipedia.org/wiki/Warrant_officer) in the U.S.A.
Wikipedia provides [equivalence lists for ranks](https://en.wikipedia.org/wiki/Ranks_and_insignia_of_NATO#Comparison_to_other_systems) in NATO countries, where the equivalence is more or less complete for reasons of interoperability:
* [Ranks and insignia of NATO armies enlisted](https://en.wikipedia.org/wiki/Ranks_and_insignia_of_NATO_armies_enlisted)
* [Ranks and insignia of NATO armies officers](https://en.wikipedia.org/wiki/Ranks_and_insignia_of_NATO_armies_officers)
* [Ranks and insignia of NATO navies enlisted](https://en.wikipedia.org/wiki/Ranks_and_insignia_of_NATO_navies_enlisted)
* [Ranks and insignia of NATO navies officers](https://en.wikipedia.org/wiki/Ranks_and_insignia_of_NATO_navies_officers)
* [Ranks and insignia of NATO air forces enlisted](https://en.wikipedia.org/wiki/Ranks_and_insignia_of_NATO_air_forces_enlisted)
* [Ranks and insignia of NATO air forces officers](https://en.wikipedia.org/wiki/Ranks_and_insignia_of_NATO_air_forces_officers)
Nowadays and ever since the middle ages onwards, naval forces have different ranks than land forces; the Romans themselves did not use special words for naval officers.
Air forces sometimes use fancy ranks; drivers of flying vehicles are given exalted officer ranks such as lieutenant or captain, whereas drivers of land vehicles have to make do with enlisted or NCO ranks such as corporal or sergeant. Keep in mind that an army captain commands about 100 men, whereas an Air Force captain commands between zero and about ten men, and a [navy captain](https://en.wikipedia.org/wiki/Captain_(naval)) commands hundreds to thousands of men and is the equivalent of an army colonel.
The number of ranks increases as the military becomes more and more sophisticated. The Romans did not really have any ranks other than private, [decanus](https://en.wikipedia.org/wiki/Decanus) for infantry or [decurion](https://en.wikipedia.org/wiki/Decurion_(military)) for cavalry (a corporal), [centurion](https://en.wikipedia.org/wiki/Centurion) (a sergeant), [tribune](https://en.wikipedia.org/wiki/Military_tribune) (a lieutenant, captain or major), [praetor](https://en.wikipedia.org/wiki/Praetor) or later [laticlave tribune](https://en.wikipedia.org/wiki/Tribunus_laticlavius) (a colonel or brigadier) and [legate](https://en.wikipedia.org/wiki/Legatus) (a major general or lieutenant general); in addition the most senior centurion of a legion was called the [primus pilus](https://en.wikipedia.org/wiki/Primus_pilus) and functioned as the senior NCO, sort of a sergeant major. During most of the Middle Ages, things were even more simple: there were generals, captains, sergeants and privates. Then war become a complicated profession with an associated formal education and ranks proliferated together with the evolution of military science and technology.
Regarding the specific questions:
* *Is there a certain rank you have to be to head a fire team?* No. It is usual to have a corporal in this role, but a sergeant may be pressed into service if the situation requires it and a private may have to make do if there are no corporals around.
* *Or fighter squadron?* A major or more usually a lieutenant-colonel (called a [wing commander](https://en.wikipedia.org/wiki/Wing_commander_(rank)) in the U.K.).
* *Do you have to have a minimum rank to be a deck chief?* I have no idea what a deck chief is. (Apologies, but English naval and nautical terminology was never a burning interest.) If you mean the [chief of the boat](https://en.wikipedia.org/wiki/Chief_of_the_Boat), that's simply the man with the most senior enlisted rank in the crew, almost always an NCO -- a [petty officer](https://en.wikipedia.org/wiki/Petty_officer) or chief petty officer. If you mean the [officer of the deck](https://en.wikipedia.org/wiki/Officer_of_the_deck) that an officer, usually a some sort of lieutenant (OF-1 to OF-3) (but see Xachary Thompson's comment, to the effect that in the U.S. navy this is usually a petty officer, OR-6 to OR-8). |
79,716 | <p>I thought of two questions regarding ringworld structures in solar systems with results I can't assume, so I will try to describe each (assume stability):</p>
<ol>
<li><p>If a (toroidal) ringworld were massive enough, bodies or planets nearby would orbit it in a spiral fashion along its length, as opposed to in discrete orbits "in front of" or "behind" it (I'm picturing something close to a <a href="https://www.youtube.com/watch?v=qHrBhgwq__Q" rel="noreferrer">demonstration made on the ISS</a> that used electromagnetism but was a close analog to gravitation). What most affects the periodicity of this orbit, and how quick can this orbit occur, if the planet is earth-sized and the Ringworld has a radius of 1AU? Could this orbit be as short as one week, or one day?</p></li>
<li><p>moved <a href="https://worldbuilding.stackexchange.com/questions/79717/ringworlds-and-habitability-on-other-planets">here</a>.</p></li>
</ol>
| [
{
"answer_id": 79765,
"author": "a4android",
"author_id": 22159,
"author_profile": "https://worldbuilding.stackexchange.com/users/22159",
"pm_score": 2,
"selected": false,
"text": "<p>There are aspects of this question which make it quite tricky to answer. The physics demonstration of ch... | 2017/05/01 | [
"https://worldbuilding.stackexchange.com/questions/79716",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/26724/"
] | I thought of two questions regarding ringworld structures in solar systems with results I can't assume, so I will try to describe each (assume stability):
1. If a (toroidal) ringworld were massive enough, bodies or planets nearby would orbit it in a spiral fashion along its length, as opposed to in discrete orbits "in front of" or "behind" it (I'm picturing something close to a [demonstration made on the ISS](https://www.youtube.com/watch?v=qHrBhgwq__Q) that used electromagnetism but was a close analog to gravitation). What most affects the periodicity of this orbit, and how quick can this orbit occur, if the planet is earth-sized and the Ringworld has a radius of 1AU? Could this orbit be as short as one week, or one day?
2. moved [here](https://worldbuilding.stackexchange.com/questions/79717/ringworlds-and-habitability-on-other-planets). | ### TL;DR: Yes, helical motion around a ringworld is possible. However, it is far from uniform at larger distances (≥ 0.04 AU).
### Summary of results:
For a toroidal ringworld with mass
$M\_R = 3 M\_\text{star} = 3M\_\odot$, central radius $ a = 1 \text{ AU}$ and
inner radius $b = 10^{-4} a \simeq 15000\text{ km}$
(hence density $\rho \sim 8800\text{ kg/m}^3$, compare with
$\rho\_{\text{Fe}}\sim 7800\text{ kg/m}^3$), the relation between the mean
separation from the central ring of the ringworld and the time
period is given by the following graph:
[](https://i.stack.imgur.com/NDnaE.png)
$\lambda a$ is the distance from the central ring. The equations are fit using the average (square) value of $\lambda$ over 1 year. The median (pentagon) and launch (circle) values of $\lambda$ are also shown. The error bars indicate the minimum and maximum value of $\lambda$. Black → no central star, orange → $M\_{\text{star}} = M\_{\odot}$.
The trajectory is indeed helical.
[](https://i.stack.imgur.com/a9Ymm.png)
We can look at the projected cross-section below. The center of the ring is at $x=-1$ (scaled by $a$, not shown), the central ring of the torus is at $x=0$. It is clear that the "inner distances" are bigger than the "outer distances" as one would naively expect. As earlier, black → no central star, orange → $M\_{\text{star}} = M\_{\odot}$. The first graph is translucent so you can see both cross-sections by zooming in.
[](https://i.stack.imgur.com/zMXol.png)
### Physics:
For simplicity, consider a point particle; if the satellite is too large
(how large?) there would be complications due to the Roche limit etc. Replace the ringworld (torus for volume calculation) with its central ring for all other calculations.
Let the particle be launched from $(x,y,z)=((1-\lambda) a, 0,0)$.
We only consider the regime $0.01 \leq \lambda \leq 0.1$. The lower limit
prevents the particle from recognizing that the ringworld has been approximated by a ring and the upper limit prevents its orbit from being perturbed
substantially by the star.
Suppose initially the radial velocity is zero.
The tangential velocity for orbit around the star (initially $v\_y$)
should roughly be $\sqrt{G M\_{\text{star}}/((1-\lambda) a)}$.
The orbital velocity around the ringworld (initially $v\_z$) should roughly be
$\sqrt{g((1-\lambda) a,0,0) \lambda a}$ where $g(x,y,z)$ is the magnitude of the net gravitational field (a.k.a. acceleration due to gravity) as a function of position.
We're kind of stuck without a number for $g((1-\lambda) a,0,0)$.
The electric potential for a ring of charge $Q$ is given as (Ref. 1):
$$
V(r,\phi,z) = \frac{1}{4\pi\epsilon\_0}\frac{Q}{2\pi}\int\_0^{2\pi}\frac{d\phi'}{\sqrt{r^2-2r a\cos(\phi-\phi')+a^2+z^2}}
$$
It is easy to obtain the potential for a graviational ring by substituting $\epsilon\_0 \rightarrow -1/(4\pi G)$ and $Q\rightarrow M$ in the equation. One can take the gradient (with a $-$ sign) and find the field numerically.
Or one could go a few steps further and actually calculate everything.
Using the equation shown earlier for one value of $M\_R$ (orange in graph), one can extrapolate to other values of $M\_R$ using $1/T\propto\sqrt{M\_R}$ (as long as $M\_R$ is not much smaller than $M\_S$) as $$T = 2\pi R/v \sim 2\pi R/\sqrt{g R} \sim 1/\sqrt{M\_R}$$
where $R = \lambda a$.
### Implementation (Mathematica):
(Everything is in SI units unless mentioned otherwise.)
First we set up the constants. The elliptic integral for $V$ earlier is somewhat nasty and takes a while to simplify, so I simplified it once and replaced the definition with the output of the simplification.
```
G = 6.674 10^-11;
EarthMass = 5.9722 10^24;
SolarMass = 333000 EarthMass;
RingMass = 3 SolarMass;
AU = 1.508 10^11;
a = 1 AU;
b = 10^-4 a;
day = 24*3600 // N;
year = 365.25 day;
\[Rho] = RingMass/((2 \[Pi] a) (\[Pi] b^2)) (* roughly 8800, Fe \[Rule] 7800 *)
(* Math *)
VRing[r_, \[Phi]_, z_,
MR_] = -G MR/(2 \[Pi]) ((2 Sqrt[(
a^2 + r^2 + z^2 - 2 a r Cos[\[Phi]])/((a - r)^2 +
z^2)] (EllipticF[\[Pi] - \[Phi]/2, -((
4 a r)/((a - r)^2 + z^2))] +
EllipticF[\[Phi]/2, -((4 a r)/((a - r)^2 + z^2))]))/(Sqrt[
a^2 + r^2 + z^2 - 2 a r Cos[\[Phi]]]));
VRingxyz[x_, y_, z_, MR_] =
TransformedField["Polar" -> "Cartesian",
VRing[r, \[Phi], z, MR], {r, \[Phi]} -> {x, y}];
Vtot[x_, y_, z_, MR_, MS_] = -G MS/Norm[{x, y, z}] +
VRingxyz[x, y, z, MR];
gRing[x_, y_, z_, MR_] = -Grad[VRingxyz[x, y, z, MR], {x, y, z}];
gtot[x_, y_, z_, MR_,
MS_] = -Grad[Vtot[x, y, z, MR, MS], {x, y, z}] /.
Abs[p_] Abs'[p_] -> p;
gtotmag[x_, y_, z_, MR_, MS_] = Norm[gtot[x, y, z, MR, MS]];
```
Let's do a quick sanity check and see if the gravitational field is as expected.
```
imgWidth = 2160;
plotAndExport[fname_,
plot_] := (Export[NotebookDirectory[] <> fname,
Rasterize[plot, ImageSize -> imgWidth]]; plot);
fieldPlotXLim = 1.5/Sqrt[2]; fieldPlotYLim = fieldPlotXLim;
splot = plotAndExport["field.png", #] &@
Show[StreamPlot[
Chop@(gtot[x1 a, y1 a, 0, RingMass, SolarMass][[1 ;; 2]])
, {x1, -fieldPlotXLim, fieldPlotXLim}, {y1, -fieldPlotYLim,
fieldPlotYLim}
, BaseStyle -> {FontSize -> 24}]];
```
[](https://i.stack.imgur.com/z2D1z.png)
Looks alright. The first graph shows the "flow" of the field (the arrows sizes are not correct). The magnitude of the field along the $x$-axis is also shown.
Now we implement the solvers for the particle trajectory.
```
(* Trajectory solvers with initial conditions *)
xi[\[Lambda]_] := a (1 - \[Lambda]);
yi[\[Lambda]_] := 0.;
zi[\[Lambda]_] := 0.;
vxi[\[Lambda]_] := 0.;
vyi[\[Lambda]_] := Sqrt[G SolarMass/Abs[xi[\[Lambda]]]];
vzi[\[Lambda]_, MR_] :=
Sqrt[Abs[a - xi[\[Lambda]]] Norm@
gRing[xi[\[Lambda]], yi[\[Lambda]], zi[\[Lambda]], MR]];
ringSol[\[Lambda]_, MR_, time_] := NDSolve[
Flatten@{Thread[{xs''[t], ys''[t], zs''[t]} ==
gRing[xs[t], ys[t], zs[t], MR]],
xs'[0] == vxi[\[Lambda]], ys'[0] == vyi[\[Lambda]],
zs'[0] == vzi[\[Lambda], MR],
xs[0] == xi[\[Lambda]], ys[0] == yi[\[Lambda]],
zs[0] == zi[\[Lambda]]},
{xs, ys, zs}, {t, 0, time}];
xiFull[\[Lambda]_] := xi[\[Lambda]];
yiFull[\[Lambda]_] := yi[\[Lambda]];
ziFull[\[Lambda]_] := zi[\[Lambda]];
vxiFull[\[Lambda]_] := vxi[\[Lambda]];
vyiFull[\[Lambda]_, MS_] := Sqrt[G MS/Abs[xi[\[Lambda]]]];
vziFull[\[Lambda]_, MR_, MS_] :=
Sqrt[Abs[a - xi[\[Lambda]]] Norm@
gtot[xi[\[Lambda]], yi[\[Lambda]], zi[\[Lambda]], MR, MS]];
fullSol[\[Lambda]_, MR_, MS_, time_, \[Epsilon]_] := NDSolve[
Flatten@{Thread[{xs''[t], ys''[t], zs''[t]} ==
gtot[xs[t], ys[t], zs[t], MR, MS]]
, xs'[0] == vxiFull[\[Lambda]], ys'[0] == vyiFull[\[Lambda], MS],
zs'[0] == (1 + \[Epsilon]) vziFull[\[Lambda], MR, MS]
, xs[0] == xiFull[\[Lambda]], ys[0] == yiFull[\[Lambda]],
zs[0] == ziFull[\[Lambda]]}
, {xs, ys, zs}, {t, 0, time}
];
appendVelocities[solution_] :=
Append[solution, {vx -> xs', vy -> ys', vz -> zs'} /. solution]
```
We will need a bunch of functions to analyze the time period.
```
(* Examining the period T of rotation about the ring *)
(* findPeriod and reconstruct copied from \
https://mathematica.stackexchange.com/a/38221/9332 *)
findPeriod[data_, threshold_] :=
Module[{fs, s1, s = {}, i, a0f, af, pf, pos, fr, frpos, fdata,
fdatac, n, per}, n = Length[data];
fs = Fourier[data];
s1 = Drop[fs, -Floor[Length[fs]/2]];
For[i = 1, i < Length[s1], i++,
If[Abs[fs][[i + 1]] > threshold, AppendTo[s, i + 1]]];
a0f = Abs[fs[[1]]]/Sqrt[n];
af = 2/Sqrt[n] Abs[fs][[s]];
pf = Arg[fs][[s]];
{a0f, Transpose[{s, af, pf}]}]
reconstruct[data_, fp_] := Module[{n}, n = Length[data];
Show[ListLinePlot[data, PlotStyle -> Black],
Plot[fp[[1]] +
Sum[fp[[2, j, 2]] Cos[
2 Pi (fp[[2, j, 1]] - 1)/n t - fp[[2, j, 3]]], {j, 1,
Length[fp[[2]]]}], {t, 0, n}, PlotStyle -> Red]]];
getOrbitPeriod[solution_, totalTime_, timeStep_] := Module[{data},
data =
Flatten@Table[
zs[t timeStep] /. solution, {t, 0, totalTime/timeStep}];
(* Not strictly correct as there are many frequencies but good \
enough for first approximation *)
totalTime/(timeStep Sort[
findPeriod[data, 10^8][[2]], #1[[2]] > #2[[2]] &][[1, 1]])];
(* The period T is observed to be linear in \[Lambda] *)
\
\[Lambda]TFit[\[Lambda]list_, Tlist_] :=
LinearModelFit[
Transpose@{\[Lambda]list, Tlist}, \[Lambda], \[Lambda]];
setGraphFontSize = BaseStyle -> {FontSize -> 12};
graphLineWidth = 0.003;
graphMarkerLineWidth = 0.005;
graphMarkerSize = 6;
opacity = 0.5;
polygonMarker[color_, n_] :=
Graphics[{EdgeForm[{Thickness -> graphMarkerLineWidth, color}],
FaceForm[None], Polygon[CirclePoints@n]},
ImageSize -> graphMarkerSize];
coloredListPlot[x_, y_, color_, PM_] :=
ListPlot[Transpose@{x, y}, PlotStyle -> color, PlotMarkers -> PM];
Needs["ErrorBarPlots`"]
\[Lambda]TFitGraph[{\[Lambda]list_, min\[Lambda]_, max\[Lambda]_,
mean\[Lambda]_, median\[Lambda]_}, Tlist_, color_] :=
Module[{model = \[Lambda]TFit[mean\[Lambda], Tlist]},
Show[
Plot[Normal[model], {\[Lambda], 0.01, Max[mean\[Lambda]]}
, PlotStyle -> {color, Dashed, Thickness -> graphLineWidth},
AxesLabel -> {"\[Lambda]", "T (days)"}
, PlotLegends -> SwatchLegend[{color}, {Normal[model]}]
, Evaluate@setGraphFontSize,
PlotRange -> {{0, Automatic}, {0, Automatic}}]
, ErrorListPlot[
(({{#1, #4}, ErrorBar[{#2 - #1, #3 - #1}, {0, 0}]} &) @@ # &) /@
Transpose@{mean\[Lambda], min\[Lambda], max\[Lambda], Tlist}
, PlotStyle -> {color, Thickness -> graphLineWidth},
PlotMarkers -> polygonMarker[color, 4]]
, coloredListPlot[\[Lambda]list, Tlist,
color, {Automatic, graphMarkerSize}]
, coloredListPlot[median\[Lambda], Tlist, color,
polygonMarker[color, 5]]
]]
```
Finally, we actually run the solvers and see the data.
```
(* Actually run simulations *)
ringSolutionTime = year;
ring\[Lambda]list = Range[0.01, 0.1, 0.01];
AbsoluteTiming[
ringSolutions =
Flatten@appendVelocities@ringSol[#, RingMass, ringSolutionTime] & /@
ring\[Lambda]list
][[1]]
ringPeriods =
getOrbitPeriod[#, ringSolutionTime, day] & /@ ringSolutions;
{ringMaxDist, ringMinDist, ringMeanDist, ringMedianDist} =
Transpose[distCalc[#, ringSolutionTime, day/24] & /@ ringSolutions];
TableForm@{ring\[Lambda]list, ringMaxDist, ringMinDist,
ringMeanDist, ringMedianDist}
fullSolutionTime = year;
full\[Lambda]list = ring\[Lambda]list + 0.005;
AbsoluteTiming[
fullSolutions =
Flatten@appendVelocities@
fullSol[#, RingMass, SolarMass, fullSolutionTime, 0] & /@
full\[Lambda]list
][[1]]
fullPeriods = getOrbitPeriod[#, fullSolutionTime, day] & /@ fullSolutions;
{fullMaxDist, fullMinDist, fullMeanDist, fullMedianDist} =
Transpose[distCalc[#, fullSolutionTime, day/24] & /@ fullSolutions];
TableForm@{full\[Lambda]list, fullMaxDist, fullMinDist,
fullMeanDist, fullMedianDist}
```
Making the $T$ vs $\lambda$ plot and seeing the trajectory (graphs in summary).
```
plotAndExport["Tvl.png", #] &@
Show[
\[Lambda]TFitGraph[{ring\[Lambda]list, ringMinDist, ringMaxDist,
ringMeanDist, ringMedianDist}, ringPeriods, Black]
, \[Lambda]TFitGraph[{full\[Lambda]list, fullMinDist, fullMaxDist,
fullMeanDist, fullMedianDist}, fullPeriods, Orange]
, PlotRange -> {{0, Automatic}, {0, Automatic}}
]
plotAndExport["traj.png", #] &@
Show[GraphicsGrid[{{
trajectory[full\[Lambda]list[[1]], fullSolutions[[1]],
fullSolutionTime/7]
, trajectory[full\[Lambda]list[[1]], fullSolutions[[1]],
fullSolutionTime]
}}]]
```
**References:**
1. <http://physics.oregonstate.edu/portfolios/Activities/EMActivities/ElectricPotentialRing/RingVSolutions070701.pdf> |
79,741 | <p>Or really, how could soldiers from the 21st century convince anyone living in antiquity that their weapons and technology are based on principles of science and engineering rather than witchcraft and black magic? I have a situation in which famous soldiers, warriors, demigods, and military/political leaders from all periods of history have been brought back to life (don't ask how or why, it's magic), given the gift of tongues so they are all fluent in each other's languages, and are basically set loose to encounter each other at random and mingle. If you want a comparison, think something like For Honor or the manga Drifters, just with a bit more focus on the fantasy/mythological aspects of the various peoples involved. </p>
<p>The first major encounter is between a camp of a few hundred modern-day soldiers (probably US forces but let's not bias the answer towards any specific nationality) and a roving tribe of Amazonian warrior women. After the inevitable apocalyptic gender war (only mostly sarcasm), everyone's cooled their jets and a momentary peace has been established so each side can start explaining themselves. And it's gonna get really awkwards for the soldiers when the Amazonians start asking what those horseless metal chariots are and how they can point those black metal things at people, make a loud noise, and kill them from a hundred yards away without firing a bow.</p>
<p>Let's assume that torches and pitchforks as well as other displays of aggression are off the table as a valid response by the Amazonians (if for no other reason than the soldiers keep pointing assault rifles at them while making really mean faces). How do the soldiers even begin to explain three thousand years of technological development in a way that won't totally break the brains of people from antiquity? And if that won't work, can they at least find a way to convince them that their super-advanced space-age weaponry isn't just magic?</p>
| [
{
"answer_id": 79749,
"author": "Willk",
"author_id": 31698,
"author_profile": "https://worldbuilding.stackexchange.com/users/31698",
"pm_score": 2,
"selected": false,
"text": "<p>The Amazonians would understand these things as an extension of advanced tech they do understand, which woul... | 2017/05/01 | [
"https://worldbuilding.stackexchange.com/questions/79741",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/21870/"
] | Or really, how could soldiers from the 21st century convince anyone living in antiquity that their weapons and technology are based on principles of science and engineering rather than witchcraft and black magic? I have a situation in which famous soldiers, warriors, demigods, and military/political leaders from all periods of history have been brought back to life (don't ask how or why, it's magic), given the gift of tongues so they are all fluent in each other's languages, and are basically set loose to encounter each other at random and mingle. If you want a comparison, think something like For Honor or the manga Drifters, just with a bit more focus on the fantasy/mythological aspects of the various peoples involved.
The first major encounter is between a camp of a few hundred modern-day soldiers (probably US forces but let's not bias the answer towards any specific nationality) and a roving tribe of Amazonian warrior women. After the inevitable apocalyptic gender war (only mostly sarcasm), everyone's cooled their jets and a momentary peace has been established so each side can start explaining themselves. And it's gonna get really awkwards for the soldiers when the Amazonians start asking what those horseless metal chariots are and how they can point those black metal things at people, make a loud noise, and kill them from a hundred yards away without firing a bow.
Let's assume that torches and pitchforks as well as other displays of aggression are off the table as a valid response by the Amazonians (if for no other reason than the soldiers keep pointing assault rifles at them while making really mean faces). How do the soldiers even begin to explain three thousand years of technological development in a way that won't totally break the brains of people from antiquity? And if that won't work, can they at least find a way to convince them that their super-advanced space-age weaponry isn't just magic? | After they had ambushed and dissected one, they would see that they are just men/women with fancy gear. Sooner or later someone will get careless. But they would know well before that just by observation.
```
Primitive != 'Stupid'
``` |
80,061 | <p>A group of 35 superhumans from the future get trapped on the alternative Earth still in the Dark Ages. Banding together they take control of a small country and establish themselves up as kings and nobles. They seek to preserve their superhuman traits, but at the same time they want to prevent inbreeding. Every generation that they interbreed with the natives, their children will be less powerful. How many generations would the group have to breed with the natives until they can begin to breed among themselves again?</p>
<p>Assume that someone with one full super power parent will be half as powerful has one with two full super-powered parents. And if the one with only one full super-powered parent breeds with another non super-powered native the offspring will be again half as powerful as there one super-powered parent.</p>
| [
{
"answer_id": 80072,
"author": "kingledion",
"author_id": 23519,
"author_profile": "https://worldbuilding.stackexchange.com/users/23519",
"pm_score": 3,
"selected": false,
"text": "<h1>Depends on how much power you want to lose</h1>\n\n<p>Based on the information in this <a href=\"https... | 2017/05/04 | [
"https://worldbuilding.stackexchange.com/questions/80061",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/17551/"
] | A group of 35 superhumans from the future get trapped on the alternative Earth still in the Dark Ages. Banding together they take control of a small country and establish themselves up as kings and nobles. They seek to preserve their superhuman traits, but at the same time they want to prevent inbreeding. Every generation that they interbreed with the natives, their children will be less powerful. How many generations would the group have to breed with the natives until they can begin to breed among themselves again?
Assume that someone with one full super power parent will be half as powerful has one with two full super-powered parents. And if the one with only one full super-powered parent breeds with another non super-powered native the offspring will be again half as powerful as there one super-powered parent. | Depends on how much power you want to lose
==========================================
Based on the information in this [answer](https://worldbuilding.stackexchange.com/a/6/23519), assume we need a minimum founder population of 400. Other answers suggest as low as 80 with good medical support, but that seems like it will be unlikely in your scenario.
35 of those 400 are your super-powered individuals. However, to prevent the genes from being too diluted, you need to spread that genetic variation among multiple generations. Lets say that every generation, you add ~30 new people into the breeding population for 12 generations. These people will bring their 0% power genes into the collective gene pool. Lets further assume that there is a 50% increase each generation: 3 children for each 2 parents. Here is how the gene pool looks each generation:
```
Gen Pop %Powerful
0 35 100
1 97 53
2 191 41
3 331 36
4 542 33
5 859 31
6 1333 30
7 2045 29
8 3113 29
9 4715 29
10 7118 28
11 10722 28
12 16128 28
13 24237 28
```
28% is the asymptotic limit. Your population will stabilize there in time.
Now lets re-run the exercise, but breed in far fewer people each generation; only 10. It takes 36 generations now (actually kind of a long time, something like 900 years) to get enough people into the gene pool, but on the plus side you keep the power a lot stronger. For this second run, we'd have to tone down the birthrate some to keep from over-running the earth, but the asymptotic power level is 54%. So the slower you add people to your gene pool, the more power you can maintain.
So the answer is: **As low as 10 generations, if you don't mind getting depowered, around 30 generations to keep the average power level to 50%**
Good old fashioned racism will help keep your population powerful
=================================================================
There is another factor at work. The superhumans will presumably be ill-disposed towards those who show few powers due to the genetic lottery. IF they discourage those people from mating, then your powers will eventually be bred back into the population. If, once the population has expanded enough to minimize the genetic bottleneck, people with less than 50% power are simply kicked out of the ruling class and now allowed to intermarry any more, you will find that the average power level of your group will increase over time; to at least 50%.
Thus, you may only have to interbreed for the 10 generations, and then rely on 'artificial selection' to keep your power level higher. With enough time (and enough racism) you can get your power level back to near 100%.
An excellent example of this in practice is the country of Mexico. For 400 years in Mexico, everyone in the upper class insisted that they were all Spanish, and didn't have any Indian in them. The result is that even though the population has a [pooled genetic material](https://en.wikipedia.org/wiki/Mexicans#Population_genetics) that is about 30% European, 65 % Amerindian, 5% Black, the skin color skews heavily white (graph shown on the link). This is basically because skin color is the easiest thing to be racist about, so there was artificial selection pressure for lighter skin for so long. So there are now a lot of light skinned half-Amerindian Mexicans running around.
You can use this effect to eventually (maybe after 400 years) get a population of 100% superpowered half-non-powered (muggle?) people running around on your alternate Earth. |