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[Question]
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Imagine there is a nuclear war and the only people, who survive it without getting sick (without breaking their DNA and suffering from radiation-induced diseases) is the military personnel (couple of hundreds - max. 1000 people) inside the [NORAD bunker](http://en.wikipedia.org/wiki/Cheyenne_Mountain_Complex).
For how many years/decades/centuries could these people maintain a civilized way of life?
By "civilized" I mean access to
1. modern sanitary systems (hot water, sewage),
2. electricity,
3. good-enough transportation (at least cars, ideally - airplanes as well),
4. telecommunication (at least stationary phones, ideally - mobile phones) and
5. computers.
I thought, how these people could get access to such goods after a nuclear war. One possibility: Allegedly, there are large warehouses in Russia, where various goods (from napkins to trucks) are stored for two purposes:
1. Supply of the troops in case of war (allegedly, those warehouses contain spare parts for weapons as well).
2. Support of people after natural disasters (when e. g. an earthquake happens somewhere and the Russian Emergency Control Ministry sends food and medical equipment into that region, those goods come from these storages).
Let's assume that such facilities exist in the US as well. Then, after a nuclear war the NORAD survivors need to find the nearest warehouse of that sort and part of their needs will be covered (provided that those storage facilities were not destroyed during nuclear attack).
If the storage facility contains gasoline, they could use it for cars and generate electricity from it.
The question is - could they have mobile phones and Internet with most of the people, who maintained these systems, killed? Could they maintain a modern level of medical support without access to medical schools?
Another question: If there are up 1000 survivors, for how long could they live off these emergency supplies (before they run out and the survivors learn to produce these goods themselves) ?
[Answer]
**1st rule of survival: Drop everything you do not need** How long can you operate laptop inside a house which is in the fire? Why would you want to stay inside burning house?
The same rule applies for cell phones. You do not need them because there is *no one using them*. Who do you call if it is safe to assume, that everyone is dead?
So, you are going to replace cell phones by walkie-talkie or military radio. Because you already have it, it requires only batteries to run, everyone alive has access to it and you do not have to constantly check how much free minutes do you have remaining on your allowance.
Also, you do not have to operate the whole internet. You will most probably operate just intranet, running only inside your bunker. Why? Because it is safe to assume that everyone outside the bunker is dead, Jim.
**To answer your question**: Such military bunker is going to have a power generator running on diesel. Also, it is safe to assume that after the worst nuclear strike someone will crawl out and provide alternative sources of energy for that bunker - namely solar and wind.
Well equipped bunker with reasonable resource sharing and alternative sources of energy can maintain "normal" life for pretty long.
The amount of time depends mainly on these criteria:
* How many resources do you actually have
* How much are people willing to save energy and rationalize food
* How many people are there
* How much are they willing to go outside and obtain food.
But believe me, having access to your favorite cat video server would be amongst the last items on your wish list, if you actually survive nuclear blast.
As I stated in the comments, do at least read about game called [Fallout](http://en.wikipedia.org/wiki/Fallout_(video_game)). It touches the idea how life inside bunker might look like
[Answer]
I think @Pavel Janicek had a great answer but I wanted to add / elaborate on what he said.
If you assume *civilized* means technological, then a technological civilization requires certain levels of infrastructure to run. That infrastructure requires a certain number of people to maintain and those people must have the correct combination of skills.
For sake of a story, I'd assume a random collection of people have almost no chance of maintaining a technological civilization. Even if you get a very smart & knowledgeable group of people, the chances that they have the correct combination of experience and skills to maintain the infrastructure is vanishingly small.
If you need a small group to maintain civilization for a story, then you'll have to resort to some sort of planning to have ensured each "salvation" bunker had the proper skills mix, proper quantity of people, good psychological profiles, a proper mix of genders, and a proper mix of ages.
I'd assume you'd want
1. Most bunker assignees to be of child bearing age but you'd probably
want a mix of other ages too.
2. A majority of bunker assignees to be women.
3. You'd want both thinkers and doers (e.g. engineers and mechanics)
with a weighting towards the doers.
4. All bunker assignees to be of good physical health and fitness.
5. You'd want to not have any one person possess unique knowledge,
otherwise you'd lose an entire set of technology with the loss of
one person.
6. Widely different genetic makeup to ensure healthy off-spring
I don't know but I suspect that 1000 people is not enough.
Furthermore for breeding purposes, I read a study a while back that indicated the following numbers of people required to maintain the race:
1. 50 people can maintain the race, but it requires very strict and
severe protocols regarding procreation (e.g. each woman gets
impregnated by as many different men as possible during their life).
2. 500 people can maintain the race, with strict procreation protocols
but not as severe as those for 50 people (single partners are
possible if the genetics board approves the match)
3. 5000 people can maintain the race, with loose procreation protocols.
[Answer]
The question needs to be split into two parts that make up a civilized society.
A) Technology
B) Culture
From a technological perspective, your survivors face the problem of selection. The military personnel do not represent all or even nearly all of the skills and knowledge necessary for maintaining a high-tech society. Some of this can be compensated for if we assume that they secured enough books and other written knowledge, but some requires training and experience.
Secondly, much of the technology we use today requires vast networks of production, specialised machinery to create and even maintain. The rare earths required for cell phones and computers - where are you going to get them? The robots that assemble modern car engines - unlikely they brought some to a military installation.
So there will definitely be a change in technology, and many high-tech gadgets will become valuable as they continue to work for the time being, but can no longer be repaired or maintained.
The cultural challenge will be even more interesting. How many poets, writers, musicians, actors or philosophers will be in your military installation? How many people with a non-military mindset? The whole micro-society will run according to military customs because that is what everyone is used to. How long such a strictly military society will remain civilized is a good question.
Add to this the small group size and the confined space and you could well have a *Lord of the Flies* scenario on your hands. Now you asked specifically about technology, but such tech is a group effort and while many inventions are made **for** the military, not all that many are made **by** the military.
From that perspective, considering the cultural aspects, your society is going to be doomed to maintain the tech that they brought with them for as long as possible, and then gradually slide into a lower-tech, more pragmatic approach.
So for how long - that was the main question.
Modern computers run for about 10 or so years until something fails. Order of magnitude, maybe it's 5 years, maybe 20, but according to [this article](http://www.yesiknowthat.com/worlds-oldest-computer-in-japan-still-working/), the oldest computer still working has been doing so for 50 years. But it went through several upgrades, and spare parts as well as trained engineers to maintain it are maybe not easily, but available. Without spare parts, or with a limited supply, I doubt you can keep a computer running for more than 100 years, no matter how hard you try.
Cars can go for [a million miles](http://www.cheatsheet.com/automobiles/going-the-distance-7-cars-that-have-gone-1m-miles.html/?a=viewall), but again that assumes regular maintenance, spare parts, etc. The oldest of these cars have also been running for about 50 years. Funny how that works out.
Electrical systems and plumbing, water pipes, etc. can last a lot longer. I don't have numbers on that and this answer is getting long. So let's sum up my prediction:
1. For about a decade, they could largely maintain the level
2. For about a century, they would experience a slow drop to more mechanical, more simple, more pragmatic levels, as high-tech devices one-by-one stop working
3. Basic electrical, mechanical and hydraulic systems can theoretically be maintained indefinitely. A fall back to the stone age is unlikely.
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[Question]
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**The Scenario**
Earth everyone on earth learns that they are in a simulation, and your everyday Joe Shmo suddenly learns that he can control the flow of time. He can advance himself forward or backward in the simulation, allowing him to manipulate the world as he wishes.
**The Problem**
So, Joe decides to test his powers. He goes back in time and breaks a window in his apartment. But, when he returns to the present, the window is unbroken. Everything Joe does directly in the past, by his own hand, is undone when he leaves that timeline. So, if Joe shoots someone, they won't be dead in the future. He can't kill his grandfather to delete himself. The timeline when he enters the world ends when he leaves and everything there continues as if he never intervened.
**The Question**
What is the most reliable, repeatable, and easiest way to kill people indirectly?
**Notes**
Joe is not very remarkable. He's not buff, he doesn't have contacts with the mob, nothing out of the ordinary.
Joe isn't worried about what else happens to people, just that his target is dead. Casualties happen.
Joe and his target live in the Simulated New York City, or another city of about the same properties.
Only actions Joe can directly control are undone. Ramming into someone won't work, but blowing up the building the person is in will. He could control the car, but he couldn't control the falling rubble.
[Answer]
He should Groundhog Day it.
Joe should pick his target, return to the past, and follow that target carefully, learning his movement patterns precisely so that he knows exactly when and where this individual will be places. Since Joe has presumably as much time as he needs to learn what this target's plans are, he can gather as much information as he likes.
With this information of this person's patterns, Joe will be able to find the time when this person is most vulnerable during the day, and least surrounded by individuals.
From there, Joe can return to the present, approach this individual at that exact time, and use any method he desires to carry out his heinous deed.
---
You mention that Joe can travel **forward** in time, which seems useful in that you haven't put any restrictions on what Joe's powers can do in regard to that.
The first obvious way he could use this power is simply to go forward in time far enough that his target is already dead, though that'd be a bit extreme.
Joe could instead do the same thing he could do with his past-going powers - only instead of learning the target's habits, Joe can find out exactly where this person will be at a future date, as far ahead as he likes, and then return to his own time and wait for an opportune time without witnesses and when his target is most vulnerable to perform his terrible deed.
---
Ultimately, without the ability to directly impact events that he has already seen, Joe is left with only one weapon - knowledge. Knowledge of what has happened and what is going to happen, both of which he can use to the desired effect.
Or, Joe could give up his life of crime and make millions in the stock market.
If I were Joe, I'd go with that plan.
[Answer]
Do it the Terminator way with a twist.
Go back in time win the lottery, then pay his father half a million to marry somebody else then another half million until the date of his enemy's birth is past. Staying in the past until he can verify that his enemy was never born.
If you really want to hedge your bets do the same deal with his mother. Then give them money to buy plane tickets to a tropical island of their choice, as long as they end up on opposite ends of the earth.
Or pay his grandfather and grandmother or great grandfather and great grandmother to marry somebody else.
[Answer]
It all depends on how many 'degrees of separation' you want between an action and the death. As SF. said in the comments, a bullet is not *directly* released by a human action, it's moved by gas from the propellant etc.
Blowing up a building - would the building be repaired because it was a direct action or would it not because the explosives did it?
Running the target over - the car did it, not Bob. Does that get reversed?
What if Bob made some wind tunnel and lured his target to the edge of a cliff and blew him off the edge? What if he got someone else to press the button to turn the machine on?
Essentially, it's about *what* does it: obviously strangling the target doesn't work, but how removed does Bob have to be before his actions don't get reversed?
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[Question]
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There are many futuristic megastructures that get called shellworlds. In this case, I am referring to the concept of a hollow sphere which encloses a gas-giant or other massive planet; suspended at such a height that the gravity is earth-like, and given a breathable atmosphere, to create a habitable environment but with many times the surface area of earth.
This Shellworld would be supported by a lattice of dynamic orbital rings; active support structures that you can look up using the link below:
[https://en.m.wikipedia.org/wiki/Orbital\_ring#Birch's\_model](https://en.m.wikipedia.org/wiki/Orbital_ring#Birch%27s_model)
assuming you have now read this article, you can begin to understand my problem. The orbital ring needs a constant flow of energy to function, but if they are supporting a Shellworld, what powers them? It can’t be solar power, surely, because they are beneath a planet-wide shell which obviously blocks out the sun, so what could power the rings supporting this gigantic megastructure?
[Answer]
If the core of the shellworld is not a gas giant, but rather a red dwarf star, then there's no problem whatsoever with using solar power- the star itself should provide more than enough energy to power the rings and any industry on the shell.
Even without a star at the core, you could use photovoltaics on the outside of the shell (on roofs of buildings, or on any sections of the shell that won't have people living on them) and transport the energy to the rings via superconducting cables.
Or, you could use fusion reactors burning hydrogen harvested from the gas giant itself. Perhaps you could use massive fusion-powered lasers to blast hydrogen off the surface of the has giant, and then collect it at the inner surface of the shell. Though there may be more efficient ways to go about it.
[Answer]
It can surely be solar power: the ring world is inhabited on its inside, but the outside, shielding the inside, is exposed to sunlight and can gather it to convert it in usable energy for the ring.
[Answer]
I'm presuming that your conundrum resides in the limitation that you're trying to power it from within the shell. If you're powering it from outside, you can use a Dyson Swarm to collect sunlight and beam it out to the planet.
If your shell world has to be fully self-contained, then the only viable answer I can think of is to have some means of harvesting hydrogen from the gas giant and artificially inducing fusion. That technology should be well within the capabilities of a race that can build a shell around a planet.
Beyond that, you'd be looking at handwavium zero-point generators.
[Answer]
Lots of great answers here already, but I thought I'd add one more. Your interior planet has an atmosphere that goes beyond the shell, so you decide to use air pressure to stay above the planet. The solution I would advocate would offer a dizzying aesthetic: simply make the shell transparent to visible light and as opaque as possible to IR light such that the temperature below the shell is much higher. This solution has the added benefit of allowing you to use nearly transparent Peltier junctions to first get some electrical energy from your shell, and second, provide some control for the temperature just inside the shell (thermocouples also use electricity to move heat, and they are getting more efficient every year).
If that doesn't work for your story, the next solution I'd advocate for is simply running some pumps that move a small fraction of the atmosphere from the outside to the inside of the shell. If there's no extra energy from the nearby sun coming in, the temperature inside will probably drop over time, but your question made no mention of the nearby stars, so this solution would be perfect for planets like Saturn, Uranus and Neptune.
With either of these solutions, if your shell is in a nearly geo-stationary orbit, you could also get some energy with the wind turbines inside the shell. Wind speeds are not constant as latitude varies, and while the amount of energy you'd harvest would not provide much compared to the thermocouple solution, it would both offset wind-related losses from having your shell interact with the atmosphere and provide an easy way to accelerate your shell enough to get to whatever angular speed you want.
All of this said, I have a difficult time imagining the utility of getting anything down to the "surface" of a gas giant. If you divorce yourself from that constraint (which the Birch ring model is designed to overcome) geo-stationary becomes fairly meaningless and controlling the rotational speed of the shell becomes much less important.
Every good author needs problems, so I would also mention that while many meteors will burn up on the atmosphere before the shell, larger meteorites will cause damage to your structure.
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[Question]
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My captains and pirates belt out lots of navigational commands and jargon, but none of it can relate to terrestrial maps. So I’m needing a system they use in transit and combat, that they will reference when barking out orders or giving lookout reports.
I need to map across vast swaths of desert on a planet that has [no life, magnetic field, no visible sky, no visible sun or moon; merely vast expanses of barren nothingness](https://worldbuilding.stackexchange.com/questions/183710/how-could-we-modern-humans-get-established-on-a-hot-planet). The winds are moderate and unvarying, or only slightly variable in direction or force; slowing only at winter which is several months of darkness. I would assume that to use a wind-relative term such as "Lee" as the directional term for East would be best as circulation is unlikely going over the poles. From the ground, this is easy. Use a tattletale. Navigation must be by air or train however; and with no oxygen it must also be by airship as no combustion is possible. I have propulsion already figured out, it is beyond the scope of this question.
I’m building the official map system for [this world which harbors a hidden pirate haven](https://worldbuilding.stackexchange.com/questions/225180/how-do-i-create-a-secret-steampunk-navigation-scheme) : how can I use wind direction to determine the direction of "Lee" and navigate across this planet? The obvious challenge is that my airship moves, meaning all wind direction is relative though it be absolute to the ground. And if I travel too high and out of sight of the ground, I have no reference at all. Dead reckoning seems like my only option. But I need a somewhat useful map that can give me some semblance of control over my travels. How can I go about doing this? The gloomy daylight through the clouds won't help me - a gnomon will be useless without any shadows cast. A compass is useless too since there's no magnetic field. Even if I make a waywiser, it'll have to be done on an extremely large scale to accommodate the rugged terrain. Gravity and wind constancy seem like my only reliable indicators.
## Ships’ equipment
For monitoring air, they have tattletales on all 8 quarters of the ship which can infer any change in heading relative to the wind. They also have tattletales to measure engine thrust at each engine. Combine these with clinometers for pitch and roll, and they have a fairly good idea of what the ship is doing relative to the air around it; they can compute set, yaw, turn, and drift fairly well to correct a dead reckoning. They have sparse radio beacon towers laid out, with simple Morse code assignments. As these need maintenance and power, they don’t go far out into the desert and can only give approximations when between the five cities. A wire antenna can give a fair guess about what direction a given beacon is emitting from, but my personal experience with these on metal ships is they are wildly inaccurate, and can give you either the correct direction or the opposite of the correct direction. Quite easy to be completely spun around. Lastly, they do love their gyroscopes and use them religiously. But for inertial nav, they quickly drift out of alignment and as a result, give poor results for long distances. An inertial gyro even today could not make a straight line for more than a few miles. A hybrid system combining tools is needed.
Q: How do they map and reference location in airships?
[Answer]
**Light houses and Nazca Lines**
You mention a group pirates in your scenario but no other groups or communities. However since a bunch of pirates with no one to actually commit acts of piracy upon is somewhat redundant I'm going to assume that:
1. There are an unspecified but large number of societies/communities living on the planet, perhaps even some form of nation states;
2. That trade between cities and towns is both common and profitable;
3. That airships are the dominant form of travel unless two communities are close enough together that land caravans or roads/railways are a viable option. And;
4. That as described conditions on the surface are in general hostile to human life so the bulk of population live in underground communities with minimal structures being visible on the surface
Those points established all but the smallest communities have built commercial landing fields on the surface above them even if after landing the airship is moved underground. These landing strips are designed to be clearly visible from the air and are brightly painted/clearly marked with distinctive patterns that identify each community and give bearings to at least the largest other communities nearby. These markings can clearly be seen from the air for miles in any direction. On top of that they also build light houses that again flash specific patterns of colored lights. (The towns long ago came up with an globally recognized system whereby no one pattern is used by two communities on the same region of the planet to avoid confusion.)
Following on from this a network of NAZCA Lines are cut into hard surfaces where geology permits (tough luck in the sea of sand). These markings can clearly be seen in daylight and provide navigation bearings and distance markers to nearby settlements.
Again there is a collective agreement regarding how the info is set out. Initially there were only a few markers giving only 'general' directions. However with time and effort as more lines were put in place the markings were refined to be more accurate. (Old ones were erased and newer, more accurate bearings put in their place). Nowadays maps of these markings are readily available to all.
Finally at least on important trade routes or where the terrain i.e. mountains interferes with carving lines remote lighthouses are also established and resupplied by airship. Again protected and maintained under international agreement. (The gyros are an added bonus and back up!)
[Answer]
I think 3 gyroscopes and 1 clock can do.
At a reference point, set the gyroscopes to a starting configuration, e.g. with their spinning axis mutually orthogonal and take the time.
Any change to that configuration will depend from their movement on the planet surface, which is a function of the planet rotation and the gyroscopes movement.
By checking the clock it is theoretically possible to know the contribute of the planet rotation and thus determine the movement by difference.
[Answer]
# Navigation
There are a lot of options for navigation, but I suspect the real answer is to how to navigate is "all of these and then some".
## Dead reckoning is maybe actually fine?
You know where you started, the direction you set out in, and the wind is "moderate and unvarying", so you can compensate in your calculations for an expected amount of drift. With all the "tattletales", you should be able to determine very reliably your heading relative to the wind - as well as its strength - since ones pointed upwind will read higher while one in the lee of the ship might even read negative. With enough sensors and knowledge of your ship's cross section from various angles, you could calculate the force applied on the ship, how it's resisted from the other direction, etc.
This could just be fine on its own, since the airship needs to go a couple thousand miles and end up within a couple hundred miles of some other point. We're trying to cross continents, not cities, so we just don't need that much precision.
## Sun position based on polarization
[Apparently](https://opg.optica.org/oe/fulltext.cfm?uri=oe-26-22-28589&id=399314):
>
> According to the Rayleigh scattering theory, the polarization pattern of skylight is mainly determined by the solar position. Therefore the solar position can be retrieved by the polarization pattern of skylight. Based on this mechanism, the partially polarized skylight is utilized by kinds of creatures for navigation, such as ants, crickets, beetles, etc [2–8]. These creatures usually sense the scattering light of the whole sky dome or patches of the sky through their unique compound eyes and optic nerve systems, and then orientate their bodies according to the polarization patterns of skylight. It was reported that the Vikings (between AD 900 and AD 1200) used to orient during their sailings with the help of the “sun-stone”, which was applied to search the solar position by observing the skylight through the “sun-stone” [9,10]. The sun is usually blocked by the clouds and fogs, but the polarization map of the partly polarized skylight remains the same as in the clear sky.
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## Topography
Even a barren moon covered in sand is going to have **some** geography. If you know your own barometric altitude and can use radar or a rope with a weight to determine your altitude above ground level (AGL), you can develop a profile of the terrain.
* Sand constantly shifts, so it's hard to tell what the ground looks like? Carry around a small ground-penetrating radar rig that you can lower to the sand to measure the local bedrock topography.
## Beacons of various kinds
>
> They have sparse radio beacon towers laid out, with simple Morse code assignments. As these need maintenance and power, they don’t go far out into the desert and can only give approximations when between the five cities.
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If we have constant and largely unvarying wind, it's going to be trivial to build plenty of wind-powered radio beacon nodes. A node could be composed of a 100-Watt (~1m / 3ft) micro wind turbine and a small transmitter hooked up to something that looks like the wheel inside a music box, and that's just if you don't want to have to invest in microchips for reasons.
* Including the panels, imagine something about the size of a desktop computer. Without them, there's no reason it would need to be larger than a Raspberry Pi.
* An airship at 5km altitude has a [radio line of sight of 291km](https://www.everythingrf.com/rf-calculators/line-of-sight-calculator). That's without any ionospheric bouncing or anything, just line of sight VHF. Two wires can be used to give better accuracy, but a directional antenna (such as a dish, Moxon, yagi) could pin that signal down to easily within a few degrees.
* Sand gunks up the turbine? Use solar! Diffuse sunlight is still sunlight and the wind should keep the sand buildup to a minimum.
* Creatures attack them because they don't like the turbines/solar panels/hate EM waves? Use an aerostat! As a bonus, this lets the radio reach *even farther*. If you keep going higher, you're eventually describing our current GPS.
To top it off, radio waves on a barren planet without a bunch of noisy RF sources are going to go very far on very low power. Currently, there's a network of low-powered (~1W) beacons around the world called WSPRNet that transmit on HF bands and are regularly heard across oceans. Basically, any planet that can support people can have a sufficient radio beacon network good enough for "find the one city within a couple hundred miles".
Since your question implies a strong preference for some kind of wind-based navigation system, you might include some explanation for why this isn't done:
* Something - the pirates? sandworms? - actively *hunts* these beacons for nutrition/parts/to cause caravans to get lost.
* There's huge amounts of interference for some reason. Possibly the lack of a magnetosphere means the planet is constantly hit with various grades of solar flares or because the planet's sand and wind create a lot of electrostatic noise. Narratively, this could be fun because it means that it might be *easier* to navigate at night.
If radio isn't your jam, the beacons could use visible light (a lighthouse), masers, lasers, or even directed pulses of sound.
## Seismometer
An airship could carry a couple of seismographs and land every so often to take measurements. I'm not familiar with the sensitivity of these, but I don't think it's crazy to think a a large underground community might well be detectable on seismographs for hundreds of miles without really trying, and could have a "thumper" to create regular impulses that could be detectable much further out. Particularly if there's not a molten core or mantle, I suspect seismographs would have work even better than normal, though deploying them on sand obviously isn't going to be great.
## Rope or Chain
Each settlement has a "lifeline" that connects it to the nearest ~3 settlements. Depending on the tech level and context, maybe it's a giant optical fiber for data, maybe it carries power, or maybe it's nothing but a large rope that an airship attaches to for propulsion and navigation. Think an upside-down zipline.
There's precedent for things like this in the form of [chain barges](https://en.wikipedia.org/wiki/Chain_boat) and I can imagine doing this so that the sandworms/whatever can't get to you, or because the sand doesn't bear loads well.
## Other Stuff
* Sounding rockets that are fired off late at night at a known time that are visible for hundreds of miles.
* Plant and wildlife could vary significantly by latitude or longitude or maybe follow some known set of patterns.
* Wind could vary slightly in different places in a way that's recognizable. If the world is completely barren and has no geography, it should generally flow away from wherever the sun is centered.
* If the planet has any notable resources, maybe nodes of those resources are detectable by sight/radar/gravity sensors.
* There could be various anomalies that are used as waypoints. These might emit radio waves, sound, light, or draw animals to or away from them.
* No matter how much cloud cover there is, you should always be able to determine the position of the sun... it might just take more work and time. You might not be able to see the shadow cast by a gnomon with your eyes, but put the same thing on some barely photosensitive paper for half an hour and look for the arc that is less exposed than the rest.
* Clouds have a maximum height - they're made of stuff heavier than "empty" atmosphere, so send up an aerostat every so often to get a view of the sky.
* Some areas of the planet might have distinct smells or dust colors or chemical makeup or radiation.
## Questions
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> And if I travel too high and out of sight of the ground, I have no reference at all.
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... how do you get so high that you can't see the ground? Lift from aerofoils **and** lighter-than-air gases decreases as you go up, so a cargo airship isn't going to travel at high altitude without a very good reason.
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> A wire antenna can give a fair guess about what direction a given beacon is emitting from, but my personal experience with these on metal ships is they are wildly inaccurate, and can give you either the correct direction or the opposite of the correct direction. Quite easy to be completely spun around.
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There's [a process](https://en.wikipedia.org/wiki/Non-directional_beacon#Determining_distance_from_an_NDB_station) for dealing with that. If that were common, I don't think we'd have a network of over a thousand radio beacons in the US alone. I suspect your experience is because a single wire antenna is probably functioning as a dipole with the ship's body as the second pole. These have a two-lobed radiation pattern with two 180-degree opposed lobes which mostly explains your experience with wire antennas. See this image:
[](https://i.stack.imgur.com/hExUI.png)
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> I have propulsion already figured out, it is beyond the scope of this question.
> Not a question, just an aside: airships could anchor every so often and run their engines regeneratively to charge up batteries from wind power.
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# Mapping
The mapping system that you use might vary by community if one group prefers radio beacons while some other group prefers topography because they live near an extinct volcano.
If you're determined to have people yelling lots of wind-related words for guiding craft, I suspect you're going to end up with something akin to the [points of sail](https://en.wikipedia.org/wiki/Point_of_sail). Regions would probably be named for whatever makes that area noticeable or distinct, while large tracts of completely identical geography and climate would probably be named as such: "the barrens" is generic while "equatorial dune zone" might be a formal name.
If nothing distinguishes one part of somewhere from other part, it'll just end up with no name, and people will latch onto whatever landmarks they can even if they end up exceedingly distant: "Bunkertown-Muskville Midway" might be an imaginary point halfway between those two towns. If you look at old maps, many had less a focus on the actual shape of the land and more of a focus on the distances between places and any landmarks you might encounter - often measured in transit time instead of physical distance. You can still see this in highway rest stops that have mileage charts: [](https://i.stack.imgur.com/lUpzO.png). In your case, each city would be on the chart, along with any known landmarks as mentioned in the first section.
] |
[Question]
[
I have this idea for a planet whose magnetic field is not aligned with the axis of rotation as is the case for Earth (I know they're not exactly aligned, but hear me out). How plausible is this, and how would this impact life? Is there any explanation for Earth's axis of rotation being approximately coaxial with the magnetic field?
Thanks!
[Answer]
Uranus's magnetic field isn't even vaguely close to being aligned with the rotational poles, and the magnetic axis doesn't even pass through the center of the planet.
So yeah, I'd say it's plausible.
We should expect Earth's magnetic field to be sort of aligned with the rotation axis because it is generated by the circulation of conductive fluid in the outer core. But, we don't know all the details of how either Earth's field or the gas giants' magnetic fields work, so no one can say right now that a terrestrial planet *couldn't* have a field like Uranus's.
It would not significantly impact life. The biggest change would be auroras happening in more densely habitable regions than they do on Earth.
] |
[Question]
[
Imagine if all of earth's interior were suddenly replaced with a volume of atmosphere (78% N, 21%O, etc), and by some fantastic force the crust remained perfectly rigid and stable.
My question is: if a hole, say with 200 m radius, were made through the crust, how far would light penetrate the hollow, air-filled interior? Would it reach the other end?
[Answer]
**TLDR: Not far, only about 1/200th of the way.**
We need a few assumptions here, but I think we can work this.
If all of Earth's interior were replaced with air, Earth would have so little gravity that all of the atmosphere would immediately fly off into space, so let's assume there is a brick in the dead center with the correct density to keep the mass of the Earth the same.
As we move down through the atmosphere and into the middle, the density of air is going to increase. [Engineering ToolBox](https://www.engineeringtoolbox.com/air-altitude-pressure-d_462.html) has a nice equation to estimate air pressure, but breaks down pretty quickly if the elevation is too large and negative, so I grabbed [Jupiter's info](https://spaceplace.nasa.gov/jupiter/en/) to get a sense of the pressure, and scaled that back against the mass of Earth compared to Jupiter to get a core pressure of approx 14080391 kPa (which sounds like alot, but Jupiter is about 1000x that, so I think we're ok), and then fit a log curve to it so that we get intermediate pressures.
[](https://i.stack.imgur.com/pvXAD.png)
Here is the same graph, zoomed in to display pressures near 0 elevation.
[](https://i.stack.imgur.com/bHIJb.png)
There are some nice absorption data generated by some university researchers you can find at this [link to a pdf of their paper](https://acp.copernicus.org/preprints/acp-2020-941/acp-2020-941.pdf) that we can use with our newly found pressure curve and ideal gas law to estimate absorption, which we can fact check at sea level with [NASA's estimate](https://earthobservatory.nasa.gov/features/EnergyBalance/page4.php#:%7E:text=The%20atmosphere%20absorbs%2023%20percent,surface%20radiates%20only%2012%20percent.) to see how close we are.
Using that data, we find that 1% is absorbed by about 22 km elevation, and we are about 31% absorbed by sea level, and NASA states its 23%, so the rough math is close enough.
So, moving down to the interior of the earth, only 1% of the original light remains by 40km below sea level (about 0.5% of the way to the middle), only about 1 billionth of the light remains at 120 km below sea level (about 2% of the way to the middle), and only 1 in 8.7396\*10^87 remains by the time it reaches the middle.
Here is a plot of the fraction of light remaining (log) vs the elevation, which shows about what we expected, that very little is absorbed at the very beginning, but rapidly ramps up as density increases.
[](https://i.stack.imgur.com/3SwRb.png)
Jumping onto the points made by @jeffronicus, @Daron and @JBH above, the vast majority of the day, no light would even illuminate the inside of the hollow Earth.
Given that the Earth's crust is approximately 20 km thick, and assuming this hole is punched on the equator to maximise the amount of sun light that gets in, only angles of incidence between positive and negative 0.57 degrees will shine into the middle of the ball through your described 200m diameter hole, which is about 4 and half minutes a day, or about 0.3% of the time.
[](https://i.stack.imgur.com/1mY5p.png)
As pointed out by @AlexP in the comments, that is the maximum amount, and only happens on the equinoxes, the majority of the year the sun never passes within 0.57 degrees of zenith. Checking a table from [Solar Energy Conversion](https://www.sciencedirect.com/topics/engineering/solar-altitude-angle) (they have a table with actual values), we find the sun indeed only passes that close to zenith two days a year, once ascending, once descending, so only two days a year get any light, and only 4 and half minutes of it, so of the total time only about 0.002% of the time does the sun even illuminate some part of the bottom of the opening.
[](https://i.stack.imgur.com/G3nel.png)
[Answer]
**About a tenth of the way**
Of course some negligible amount of light will hit the other side. But only 1% of the starting light gets more than a tenth of the way through.
Googling around I was told the Troposphere and Stratosphere contain about 99% of the atmosphere. They are about 30 miles or 50km thick. I also found [the following](https://www.fondriest.com/environmental-measurements/parameters/weather/photosynthetically-active-radiation/):
>
> The sun’s radiation must make it through multiple barriers before it reaches Earth’s surface. The first barrier is the atmosphere. About 26% of the sun’s energy is reflected or scattered back into space by clouds and particulates in the atmosphere [34]. Another 18% of solar energy is absorbed in the atmosphere.
>
>
>
which suggests 50km of atmosphere will absorb about 20% of the light you shine through it. In other words $0.8$ of the light gets through.
If you double the atmosphere then only $0.8^2 = 0.64$ of the light gets through. If you triple it then $0.8^3 = 0.512$ of the light gets through. At 20 atmospheres only $0.8^{20} \simeq 0.01$ or 1% gets through.
Those 20 atmospheres are about 1000km thick. In comparison the Earth's diameter is 13,000 km. So by the end we only have $0.01^{13} = \text{very small number}$ of the light left.
] |
[Question]
[
Essentially, in the human world of 2024 (current day tech, but no more COVID), how would humans find a way to prevent a disease that targets and destroys lysosomes, so that only animals are affected. Once the lysosomes are destroyed in the cell, it becomes full of waste materials and ruptures. How would the humans prevent it from destroying all animals?
Edit: it spreads through whatever the most transmissible way to transmit.
[Answer]
Whatever targets the lysosomes is based on molecules, which need to get into the cell to destroy the lysosomes inside it.
The possible approaches to fight the disease are therefore:
* develop a molecule which targets the active molecule of the disease, turning it into an ineffective one
* develop some molecule which inactivates the key which the molecule uses to open the door into the cell, so that it cannot accomplish its mission
[Answer]
# They Probably W/Couldn't do Anything Different:
**Frame Challenge**: This isn't how diseases work. But if the disease was really that bad, it's unlikely they could do anything about it.
* I've added a few scenarios where you could get something CLOSE to what you're looking for, but it would require a fair amount of handwaving.
Lethality is self-limiting for diseases, which is why epidemics and pandemics eventually fade or burn out. The more lethal (like Ebola) the faster they burn out. Usually really serious outbreaks are in diseases that have only recently evolved to affect a new host.
How a disease is vey critical for organisms and needs to be specified for any realistic discussion of how to control it. Each vector has specific pros and cons.
And broad host infection is extremely rare and requires very generalized means of infection, limiting how effective the disease is at both spreading and causing serious infection.
# VIRAL:
If you are going to shut down a fundamental cell function like lysozymes, then the way to do it is to take over the cellular machinery. The only realistic way to do so is with a virus.
Viruses don't come in the "super-kill-everything" variety because they CAN'T. Viruses are not considered technically alive because they are really one-trick ponies. They are incredibly simple, because the more complicated they get, the harder it is to replicate and the more ways a mutation can disable the virus. They evolve a specific vector that targets specific cells, gets inside, and takes over the cell to make more virus. They can get a little fancy after that - hide and re-express later, incorporate into the host to affect later generations, etc. but that just slows them down.
If something about the virus causes the lysozymes to shut down, it would need to somehow give it an advantage in making and spreading viruses. Everything a virus does needs to center around making and spreading the virus. Just destroying the cells is counter-productive. A live host is one spreading the virus and making more. If a virus affects more than one species (or maybe a cluster of species), one of the two species is typically barely affected by the virus so the that species transmits the virus around to the species that is more affected.
The kinds of vectors that viruses use are pretty narrow, because they have to perform a complex task that all animals have spent billions of years developing defenses against. Given generations of exposure, a virus might develop the ability to target a new species, causing a new disease in a new species. But even here, the natural tendency for a virus is to become LESS lethal over time as it adapts to infecting the host without killing it. So each new generation of COVID becomes more transmissible and less deadly. After all, you need those humans to survive.
So the way the virus kills cells is very secondary. If the virus wants to spread, it will quit destroying lysozymes. But even there, a virus only affects the cells it directly infects. So the cells that die stop making virus, stop infecting new cells, and the virus goes extinct.
# NON-VIRAL:
Although the only way I can see a disease shutting down lysosomes is via a virus, Let's look at the nearest equivalent in bacteria. You stand a slightly better chance here, but this is still not how diseases work. even in bacteria, they have limited host ranges OR limited spread OR low lethality.
A bacteria would have a motivation to make itself undetectable to phagocytic cells in their hosts and preventing the cells from getting eaten and digested in lysosomes. A bacteria that could release a broad array of enzyme inhibitors could potentially block the functions of lysosomes, and if those same bacteria were able to tolerate the low pH environment inside, they could theoretically use lysosomes as a refuge inside of macrophages and other phagocytic cells.
There are bacteria that already do something similar, and haven't wiped out animal life yet. [Salmonella and Tuberculosis](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7714789/) each have a host of mechanisms that affect the operations of lysosomes. But cellular functions are very complex, and to perform this task the bacteria need to be pretty specialized. Living this way is the biological equivalent of recycling trying to survive on the conveyor bels in a recycling plant. They are intracellular, so they live inside cells (which limits spread but also gives them a protective environment in which to live). But animals have similarly engaged in a billion-year-long war with these organisms, and have a wide variety of defenses to fight them. They also tend to either spread in very limited ways (like feces) or limit themselves to specific hosts.
In these situations as well, the organism lives within the host and relies on the host staying alive for the bacteria to live. Salmonella is fairly aggressive, but needs to be spread but as such triggers strong immune responses and needs to spread in feces (in which case, super-salmonella would be fairly easily controlled by good hygiene among humans, and would be self-limiting among animals as it killed all the available hosts). Tuberculosis spread via the respiratory route, but is successful by spreading very slowly and taking a very long time to degrade the host (as well as specializing in the organisms infected). A super-TB, besides killing the hosts more rapidly due to quick infection, would be a poor fit for killing all animals.
Once again, the disease would only be affecting the cells and lysosomes that it is directly infecting. So the disease would have to be massively infecting almost every cell (or at least almost all of a certain cell type) to work the way you want. If it is only infecting a certain type of tissue, it is likely much more limited in effects from what you're looking for.
**Universal systems**: Diseases that could somehow produce a toxin or hormone that affected all lysosomes in an organism look like the disease you are trying to cause. But these means are more universal in an individual or species, and less universal to all animals. Toxins and hormones will either be so lethal as to cause the disease to burn out almost immediately OR be specific enough that they will only be effective in a single species or category of species. A toxin would be more likely than a hormone, since species aren't likely to have a means of shutting down all of a essential cellular function that will kill the organism.
# IF WE HANDWAVE:
Your disease (Tubercanella) is an intracellular bacteria that can affect **most** animals intestinal tracts and acutely infect the respiratory tracts of mammals. I still don't know you could get EVERYTHING (like fish and insects and even more obscure stuff) but you could get a lot. It has a long incubation time in the hosts, allowing it to persist in organisms and get shed into the environment constantly. Your mammals (notably humans) would be spreading it all over, where it would be difficult to control as it would have reservoirs in non-human animals.
in this case, an [antibiotic](https://www.medicalnewstoday.com/articles/10278) would likely be the solution. Only that's too easy for what you want. So it needs to have multidrug resistance (implying it is either genetically engineered OR has been present in a less virulent form among humans for a long time). Antibiotics can be a broad range of substances, typically selectively affecting bacterial enzymes preferentially over animal ones or affecting the bacterial ability to grow and replicate.
After that, the disease would need to be resistant to antibodies or a [vaccine](https://www.cdc.gov/vaccines/vac-gen/imz-basics.htm) would defeat it easily. Not all bacteria are easy to make vaccines to, so this can be handwaved fairly easily.
If the bacteria is producing a [toxin](https://www.frontiersin.org/articles/10.3389/fmicb.2016.00042/full#:%7E:text=Bacterial%20toxins%20are%20virulence%20factors,of%20the%20host%20immune%20response.), then a toxin inhibitor or antitoxin could be a treatment. Block the toxin affecting lysosomes and the lysosomes will be unaffected. Since the toxin would likely be essential for the bacteria's spread, this would also effectively be an antibiotic.
* All of these means would work to treat the disease in treated animals and people, but wouldn't work well to spread around to all animals in the environment.
# ****Super-bacteriophage**:**
To actually reduce the global effect of this super-bacteria, you'll need a virus that targets the bacteria. Let's handwave and say the bacteria is significantly suppressing the immune system. To infect an intracellular bacterial disease, that will need to be one hell of a bacteriophage. Bacteriophages are usually a lot more complex than viruses that infect animals, since bacteria are a harder thing to penetrate. It will need to first manage to enter the infested animal cells, then infest the bacteria, without triggering the host immune response against the bacteriophage.
To really get rid of it from the broader environment, you'd need a CRISPR-like virus that somehow integrated into the DNA of **ALL** infected animals and would only get expressed if the cell was infected by the bacteria. Then the virus would kill the bacteria. We likely can't do that today, but trying would certainly be an interesting story.
] |
[Question]
[
A common complaint I see about fictional reptiles is that they behave like mammals instead of reptiles. One of my cultures has almost exclusively reptiles (e.g. monitor lizard-like creatures) as pets/companions.
However, these aren't like real lizards because they'll need the following traits:
* can handle cold temperatures better than real lizards (but might still slow down in the cold)
* actually like being around humans
* can be trained
* most importantly, are more intelligent than regular lizards (somewhere between *real-world housecat* and *Disney animal companion*)
All of these traits make the reptiles less "reptile-like", but I want these lizards to still behave at least *somewhat* like reptiles. What reptile traits could these pets retain so that they're not just "dogs but with scales"?
[Answer]
## Stop/start motion
When a reptile stops moving, it can more or less freeze.
Granted, mammals can lie still, but when it comes to just freezing in a standing pose for no apparent reason, nothing beats reptiles. You can start to wonder if they are made of plastic.
(The absolute champions in this regard are tuataras; my university had an enclosure and I watched it on and off for weeks before ever seeing one of them move).
[Answer]
They can still lay eggs and have their anatomy be reptilian, in that their limbs get out "horizontally" from their torso, not "vertically" like it happens with mammals.
In this way they would still move more like reptiles, undulating their body at every step, and would need to build some sort of nest for laying their eggs when reproduction time comes.
[Answer]
**Stoneface**
Dogs are the best pet because their happy faces look like our happy faces and we share a lot of body language.
[](https://i.stack.imgur.com/nhENj.jpg)
[](https://i.stack.imgur.com/7dBDn.jpg)
[](https://i.stack.imgur.com/WKuGs.png)
For comparison this is what an excited lizard looks like
[](https://i.stack.imgur.com/5N6mV.jpg)
Take away the facial expressions and you already take away 90% of what makes a dog a dog.
Then add slow-moving and non-cuddly and you get [something with a dogginess factor of only 1.2555...% (recurring of course).](https://www.youtube.com/watch?v=p-zGIS-WWZQ)
Of course from a narrative standpoint this is boring because we have started with a dog and removed body language rather than adding new body language.
It will require more work and research to make your domestic lizard seem like something other than a dog-shaped robot.
I will get you started with excited tortoises:
[](https://i.stack.imgur.com/QURsi.png)
The reptile on top is making a face that could be interpreted as excitement, within the narrow range of movement of the chelonian visage. The reptile on bottom looks unimpressed but that is the default setting on a tortoise.
[By the way these guys go squeak squeak when they are feeling amorous.](https://www.youtube.com/watch?v=6R3BYCT5oWw)
In general you must decide the emotional range of the lizard, what triggers certain emotions, and then how it expresses those emotions. In particular decide whether the body language is visible to a human being without a Masters degree in lizardology.
[Answer]
Right now there just is not enough information to answer.
there is no overarching reptile behavior, reptiles are a diverse group with diverse behaviors. That said there are a few things we can say.
1. Most reptiles do not urinate, so having your reptiles pee is very much a mammal bias.
2. reptiles generally have better color vision and worse hearing than mammals.
3. If it is covered in scales it is not that cold tolerant, it might be able to survive short bouts of cold but it has no insulation, so for any cold weather image how a naked human would fare in that weather to understand how it will behave.
4. Reptiles lack endurance, this is one of the effects of being an ectotherm, low activity levels. If it is keeping up with humans it is not a normal reptile and it can't be built like one, an ectotherm just can't keep up with even moderate human activity levels, humans are endurance monsters to most animals much less an ectotherm. A sprawling lizard will not be following its master around. So If you need them to follow humans around, your creatures have to be endotherms with an upright posture. Endothermic reptiles is not impossible it has evolved at least twice but they will not look much like a monitor lizard, aa sprawling posture is counter productive for an endotherm. So you should look at scaly endotherms from history like *Kaprosuchus saharicus* and other terrestrial crocodilians.
Something you need to consider, **What was your creature before humans domesticated it, this will tell you what its anatomy should be, or you can say, It needs these characteristics, which will tell you it will look like this.** each of these would be a question on its own and should probably come before this one.
[Answer]
Other answer have pointed to superficial anatomical type differences, but the big issue that really matters is their brain, and how that impacts their psychology and social interactions.
In general, neuroscientists oversimplify vertebrate brain anatomy by breaking it down into three layers, [triune brain theory](https://en.wikipedia.org/wiki/Triune_brain), of Paul D. MacLean from the 1960s. It is an oversimplification and has been superseded by more complex models of the brain, but as a very basic starting point to develop some basic intuitions (especially about the brain differences between different kinds of vertebrates) it isn't a horrible model. As the linked article explains:
>
> The triune model of the mammalian brain is seen as an oversimplified
> organizing theme by some in the field of comparative neuroscience.
> It continues to hold public interest because of its simplicity. While
> inaccurate in many respects as an explanation for brain activity,
> structure and evolution, it remains one of very few approximations of
> the truth we have to work with: the "neocortex" represents that
> cluster of brain structures involved in advanced cognition, including
> planning, modeling and simulation; the "limbic brain" refers to those
> brain structures, wherever located, associated with social and
> nurturing behaviors, mutual reciprocity, and other behaviors and
> affects that arose during the age of the mammals; and the "reptilian
> brain" refers to those brain structures related to territoriality,
> ritual behavior and other "reptile" behaviors.
>
>
>
At the base is the "reptile brain" mostly in the brain stem. This handles most of the "automatic" functions of the nervous system (like breathing when necessary) and also very hard-wired, visceral, almost instinctual responses. MacLean proposed that the reptilian complex was responsible for species-typical instinctual behaviors involved in aggression, dominance, territoriality, and ritual displays. It turns out that this part of the brain is actually present in all vertebrates including fish, amphibians, reptiles and birds, as well as mammals. This part of the brain is fast, reliable, has low metabolic cost relative to return, and gets everything that is necessary for the being with this brain to live done.
Next is the "mammalian brain" which adds the "[limbic system](https://en.wikipedia.org/wiki/Limbic_system)" (a term MacLean coined in 1952) and the neocortex, which is responsible, somewhat ironically, with a lot of the aspects of human psychology that we associate with "being human" like love, empathy, parent-child bonding, instinctual fear, and a lot of "gut feelings."
MacLean's recognition of the limbic system as a major functional system in the brain was widely accepted among neuroscientists, and is generally regarded as his most important contribution to the field. MacLean maintained that the structures of the limbic system arose early in mammalian evolution (hence "paleomammalian", with paleo- meaning old) and were responsible for the motivation and emotion involved in feeding, reproductive behaviour, and parental behaviour. Some of the best known components of this system are that:
* Septal nuclei: a set of structures that lie in front of the lamina terminalis, considered a pleasure zone
* Hippocampus and associated structures: play a central role in the consolidation of new memories
* Amygdala: located deep within the temporal lobes and related with a number of emotional processes; and
* Nucleus accumbens: involved in reward, pleasure, and addiction
While it is true that non-mammals don't have a neocortex, the distinction isn't as complete and absolute as MacLean originally believed:
>
> While these areas lack the characteristic six neocortical layers,
> birds and reptiles generally possess three layers in the dorsal
> pallium (the homolog of the mammalian neocortex). The telencephalon of
> birds and mammals makes neuroanatomical connections with other
> telecencephalic structures like those made by neocortex. It mediates
> similar functions such as perception, learning and memory, decision
> making, motor control, conceptual thinking.
>
>
>
Still, MacLean was not wrong in the basic direction and source of the neurological differences between reptiles and birds (sauropods) on one hand, and mammals on the other, even though he overstated the completeness and magnitude of the differences.
Finally, there is the "primate brain" which adds the outer cortex that makes up a lot of the volume of the human brain and is associated with "thinking slow" and cold, analytical reasoning tasks like playing chess, doing mathematical proofs, or constructing logical legal arguments. This part of the brain takes up a disproportionate share of a human body's energy consumption, and is slower than either the reptilian brain or the mammalian brain, but is also much more plastic (i.e. capable of being trained or repurposed through interactions with the environment) and more effective at dealing with novel situations. It is the part of our brain that works in a way most similar to how a computer work works, although it isn't as rigid and able to use fuzzy logic and "neural network" type reasoning as well as logical deductive reasoning.
Once of the best ways to illustrate how this presents is to compare a mammalian pet like a dog or a cat or a hamster, to a reptilian pet, like a boa constrictor or an iguana.
When you project human-like feelings of loyalty or affection or trust to a mammalian pet, what you are doing is basically sound. These animals are capable of having these kinds of feelings and have similar nervous system and hormonal hardware that implements their ability to have these feelings.
Reptilian pets aren't like that. No matter how much you think that a big snake or lizard is loyal to you, or has positive feelings towards you, or trusts you, this is just an illusion and when you project these human-like feelings onto a reptile you are engaged in a process of self-deception that does not reflect reality.
No matter how many years of history of you lovingly taking care of it that you have with a boa constrictor or a large lizard, if it is hungry and sees an opportunity to eat you, it will do so with no remorse. This goes beyond simply being wild animals. They simply do not have the feelings that you project upon them. See, e.g. [here](https://www.nationalgeographic.com/animals/article/snake-owner-killed-pet-python-aspyxiated-spd) (8 foot pet python kills owner). They aren't "pets", when you keep them, they are wild specimen animals that you have in your home.
The question is how you want to conduct world building in a way that reflects these neurological differences and reconcile that with your premise that:
>
> these aren't like real lizards because they'll need the following
> traits:...
>
>
> actually like being around humans
>
>
> can be trained
>
>
> most importantly, are more intelligent than regular lizards (somewhere
> between real-world housecat and Disney animal companion)
>
>
> All of these traits make the reptiles less "reptile-like", but I want
> these lizards to still behave at least somewhat like reptiles.
>
>
>
Greater intelligence and a capacity to be trained isn't really that troublesome as our knowledge of sauropod cognition has improved. You might think of them as on a par with some of the really smart birds, like crows or carrier pigeons, who would have similar brain anatomy and can be trained to some extent. But, unlike curious humans, who are interesting in learning and ideas for their own sake, reptiles and birds learn things more as a means to an end and rarely cogitate and investigate and ponder merely for the sake of doing so.
On the other hand, if they "actually like being around humans" you are really getting into non-reptilian, non-sauropod type behavior. These are types of mental processes that they simply don't have the hardware to experience.
You wouldn't go wrong with portraying lizard people as high functioning [psychopaths](https://en.wikipedia.org/wiki/Psychopathy) or [Machiavellian personality types](https://en.wikipedia.org/wiki/Machiavellianism_(psychology)), that aren't inherently malicious or antisocial, and who can operate in and even preside over social groups of people, but just don't have emotional empathy at all, even if they can predict from long and careful observation how emotional empathy causes other people to act and respond to their amoral, fundamentally selfish actions that advance their own agendas.
On the other hand, reptiles, unlike even psychopathic humans, don't have a "nucleus accumbens" and therefore aren't driven by pleasure seeking dopamine rush cravings. They want to eat because their bodies tell them they need food. They want to have sex because they need to reproduce. They want to seek the right temperatures because their bodies work better in those temperatures. More social birds interact in a fairly rigid way because they've been hard wired into the benefits or necessity of doing so. But reptiles don't crave dessert because they enjoy eating, don't feel a need to engage in non-reproductive sex merely for pleasure, and wouldn't build sauna's or cold pool spas to entertain themselves with the trill of experiencing extreme temperatures.
To the extent that the cold realities of real life lizards don't suit your story, you might want to shift them to more bird-like behavior, the evolutionary direction in which the dinosaurs ultimately ended up going, but that is still a world away in psychology from all mammals.
] |
[Question]
[
I've got a fairly small community of people that, after a genocide, some survivors moved into a cave system. They've been living there for about 5 or 6 generations now and rarely leave the caves except occasionally at night when they need to get food. These caves are pitch-black except for a faintly luminescent material in some areas, that they have mixed into tattoo ink for some minor light to assist in communication and finding other members of their group. I'm wondering how this lifestyle- living in little to no light- would have affected their overall appearance by this point, particularly how their eyesight might have changed in response to this level of light. I'd also imagine they might be rather pale due to lack of sunlight, but I could be wrong.
\*Edit- Assume the vitamin D issue does not apply and that they have a consistent source of it. My primary focus is more eye changes/sight, though other changes are welcome!
[Answer]
Welcome to the forum!
The short answer to your question is that genetic changes your society will experience in 5 or 6 generations living in a cave, are identical to the changes you and I have experienced from our 5-generation ancestry. Real-world evolution has no goal and does not "respond" in any way to changes in conditions.
99% of all species which have ever lived on Earth are extinct because their environment changed. Extinction is a very real and normal answer to dramatic changes in the environment. So I will start by saying this world you are creating has unrealistic genetics, and can only exist if you have designed some form of alternate evolution into your world. That's fine, you can invent some alien manipulation or divine guidance that is actively protecting your people from extinction. In that case, whatever eyesight enhancements you want them to have will be designed in by your genetic designers.
Normally I would assume the question wants an answer within the scope of real-world genetic, but I don't make that assumption here because of your one comment:
>
> "I'm wondering how this lifestyle- living in little to no light- would
> have affected their overall appearance by this point, particularly how
> their eyesight might have changed in response to this level of light."
>
>
>
That said, there is small room for epigenetics to make superficial physical changes to each individual living in the caves, but these will not be transgenic. Future generations *may* benefit from epigenetics only if those changes create a live-or-die scenario, and competing gene pools die off without them. This deserves an example:
Humans have invented artificial groups called "races" based on melanin content in their skin. There are no biological 'races' of homo sapiens based on genetics. But, there seems to be more melanin in aboriginal people on the African and Australian continents than in Northern continents, and melanin serves to protect us from the sun's UV radiation. Genetics did not do this "in response" to more or less sunlight. What happened is, people with less melanin could not survive as well in the full African sun, so they either migrated North, or died off. If your ancestor happened to arbitrarily have the "switch" for more melanin, they probably decided the sun wasn't a big deal and stayed. But his or her brother may not have been so lucky, and they couldn't take the heat. The gene pool in the Southern continents eventually had very few people who can't produce more melanin, and at some point there would be a mutation in the people that left them naturally darker at birth. They have an obvious advantage in Africa, and either killed off or chased off people who couldn't take the scorching sun. In other words, the better quality was a pure accident but survived by natural selection. It is important to note that the genetic change that produced more melanin can happen in Africa just as easily as it could have up North, but in Africa and Australia it provided a survival advantage and became dominant in the population. Thus, living under a scorching sun had absolutely nothing at all to do with the actual mutation that makes people darker in Africa and Australia; it only made that mutation 'win' in natural selection. So your people in the cave will have the exact same genetic changes you and I will have, randomly.
For your society to have permanent genetic changes under real-world genetics, they must be exposed to natural selection. For example, if you want them to have better night vision, then you need to have something remove people with poor eyesight from the breeding pool (a stealthy predator, a selective disease, or make it illegal for them to breed). Even this won't likely make a noticable change in only 5 generations however.
Now, even though your scenario isn't realistic, it is very common in science fiction. The original Planet of The Apes had humans who developed huge brains and telepathy while they were living underground. *But* they had radioactive fallout speeding up genetic mutations through hundreds of generation, so that was their in-world excuse. Please understand there is no Hard Science answer to your question.
[Answer]
A group of people living in an underground civilization is undoubtedly going to suffer from serious vitamin d deficiency, leading to serious health problems such as osteoporosis or cancer.
Here are a few links regarding vitamin d deficiency:
<https://www.healthline.com/nutrition/vitamin-d-from-sun#overview>
<https://www.vitacost.com/blog/vitamin-d-deficiency/>
Considering these side effects, I am not sure how long an underground civilization like this one would even be able to survive let alone propagate for long enough to actually flourish unless they have a source of vitamin d in food that is readily available or technology I am unaware of.
The development of human skin pigmentation in nature is linked to the amount of UV radiation that people receive. Areas with high amounts of sunlight and UV radiation developed darker skin tones and areas with lower amounts of sunlight were naturally selected for people with lighter skin tones, so living in an underground area with no ultraviolet light should most likely select for people with little to no pigmentation in their skin.
Here is a link that helps get across my point: <https://www.nasw.org/article/vitamin-d-levels-determined-how-human-skin-color-evolved>
With time and enough generations, people living underground would undoubtedly get paler.
However, they would most likely suffer from so many health issues due to vitamin d deficiency that their existences would be unpleasant at best and nightmarish at worst.
Edit:
Assuming that Vitamin D deficiency is not an issue, then the development of eyesight would probably be similar to that of skin tone. People who are better at seeing in the dark would be more likely to survive, and natural selection would, over successive generations, filter out in such a way that people with better dark vision would become the norm.
On top of being paler, they might also have white hair and violet/red eyes which are common of people who are born without pigmentation in their skin. In the book series Gregor the Overlander, by Suzanne Collins, the person who is most known for writing the Hunger Games Trilogy, there is an underground civilization of a similar nature to the one that you are describing. They might serve as an inspiration to the people you are writing about.
Also, even with a steady supply of vitamin d, there are a lot of other complications that come about with keeping people underground. For example, without a day and night cycle, it would initially throw off the biological clock of the people in this society. Then, after many generations. They would develop their day and night cycles differently, and I'd imagine that would greatly change their sleep cycles, which might affect the mental health of the people living in this society.
One more thing to consider. When a person is in the dark for a long time, their eyes become naturally adjusted to the dark. Living in the dark full-time would probably lead to these people being extremely sensitive to bright light sources, so being suddenly brought into the sun would not be pleasant. These underground people would probably get sunburns easily as well.
In conclusion, I believe that people living underground would eventually, after several generations, select for traits of being extremely pale, with likely pale white hair and light eyes that might be pale violet. Their eyesight might be good in the dark, but it would be extremely sensitive to light sources. The lack of a day and night cycle would throw off their biological clock, leading to many unforeseen difficulties that may affect their mental health in the long run.
Edit2: Vogon Poet is most likely correct in saying that such changes would probably take place over far more than 5 or 6 generations, so the changes depend on how quickly natural selection and/or genetic mutations would take place within this population.
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Perhaps you should also consider bodily changes that happen to the individuals during their lifetime. Apart from vitamin D deficiency (and probably others depending on their diet) already mentioned elsewhere, perhaps there are other changes.
Perhaps there is atrophy in cone [cells in the eye](https://en.wikipedia.org/wiki/Photoreceptor_cell) if light levels are sufficiently low.
With no light cycles circadian rhythm will be affected.
Perhaps they develop better hearing. Or new fears.
Do they do enough physical exercise?
How are newborns affected during their first 2-3 years? Can they see their care giver's mouth and expressions?
How large is their community? Are there in-breeding effects?
And so on. :-)
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In my question about [carnivorous elves,](https://worldbuilding.stackexchange.com/questions/217291/evolutionary-pressures-for-carnivorous-elves) one of the commentors pointed something about my elves that I had not really considered in depth before hand.
My elves are a form of hominid, thus an ape. My elves also have claws, apes *do not.*
So my question is, **is there any way for a group of hominids to develop claws?**
As simply "winding back the clock" would not work, is there perhaps a way for the finger nails of the hominids to become claws over time? Or is this simply not happening and if so, is there another way for hominids to develop claws?
This question is of course a continuation of the question linked earlier.
[Answer]
# To expand:
L. Dutch has a perfectly solid answer, but I feel it needs a bit more meat. So looking at your last question as well, I think the key is that your species needs to be sprint-type and ambush predators, but they may be losing a motivation to still be tool users. claws tend to be at odds with tool use, since the idea is that the claws compensate in animals for a lack of tools. They certainly can evolve anything with enough pressure, and claws can be extremely useful.
Finger nails can certainly evolve into claws. They grow thicker, wider, and more deeply buried in the hands. The hands may become less flexible and the finger shorter to give better strength to those claws, but reducing the nimbleness that aids in making and using tools. Getting the claws to be extremely sharp might be a bit of a stretch evolutionarily, but this isn't likely to be a huge problem if your elves aren't hunting big prey.
If they are, they still likely need to be using tools (at least knives, clubs and rocks, but spears are amazingly useful). Hominids traditionally used pack tactics and endurance hunting to repetitively injure large prey and wear them down. Their injuries in doing so it meant Neanderthals tended to have injuries similar to rodeo performers, and for your slight species this would be bad.
* Claws can assist in climbing, so your elves may be able to nimbly pursue prey up trees. This also allows their fragile selves to flee up those same trees.
* Digitigrade legs give higher boosts of speed, but may in full bipeds tend to cause tumbling and require lots of traction to use effectively. Having longer front limbs that can be used for running may help, but the claws allow greater dig into soft materials like wood or even dirt, so they will be less likely to both fall OR run in soft soil and churn up the dirt due to lack of traction.
* Claws may assist in digging like a badger, so prey that flees down burrows can be efficiently dug out.
All these behaviors would tend to lend themselves to a species evolving into a niche similar to a cat or other small predator, pursuing smaller prey rather than tracking larger. Pure carnivores are probably not doing much gathering, and are less likely to be developing things like agriculture. They may as a species be evolving away from the sapiens model of smarter tool users, and instead be "devolving" by human standards into a species where tool use is increasingly less important. The growth of a mane fits well with a species that increasingly doesn't use clothes to thermoregulate. Humans are arguably [partly domesticated](https://www.sciencedaily.com/releases/2018/02/180215110041.htm#:%7E:text=Human%20%27self%2Ddomestication%27%20is,evidence%20for%20this%20evolutionary%20process.https://www.sciencedaily.com/releases/2018/02/180215110041.htm#:%7E:text=Human%20%27self%2Ddomestication%27%20is,evidence%20for%20this%20evolutionary%20process.) and increasingly social, so your species is less domesticated in behavior than modern humans. The cannibalistic behavior they exhibit fits well with this idea.
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To develop claws, there must be a use for them giving an evolutionary advantage. I can think of two reasons:
* hunting: carnivore animals mostly have claws, to better grab their preys (think of felines) or to better reach them (think of the anteaters)
* motion: think of the claws of the sloth, which are used as hooks for it to hang from the trees
If your elves find themselves in a situation where one of the above becomes a selective pressure for long enough that evolution can work, they might develop claws. However, consider that for the known cases of the hominids called homo sapiens, the solution was found in another direction.
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My question is how/why does my creature evolve into having arms when it has none?
Context: I am currently creating a evolutionary tree for the first animals of my planet. My planet is the size of earth with a similar climate to earth in the Carboniferous era.
It’s mostly covered in swamps, jungles, savanna, and what I like to call mushroom fields(fields of moss and Prototaxites)
It’s rather warm.
One of the first creatures is a two legged, fast, long necked, type of reptile. Its a herbivore and it’s main competition is its cousin which is like it but more heavyset.
It’s main source of food is a small parasitic fern that is found high on trees.
I think it might need arms to climb the trees or defend itself against predators but I need help in defining its future as hopefully the first sentient race of the planet.
[](https://i.stack.imgur.com/QooFf.jpg)
[Answer]
No vertebrate had evolved a *new* limb for the entirety of 400 million years of their (limbs) existence. They have only changed their function or were lost. A limb is too complex of an organ, requires a lot of pre-existing stuff (bones, muscles, etc) to evolve this late in the evolutionary timeline. So your creature really has only three options here:
1. Just redesign it to have some frontal limbs that can evolve into arms with time.
2. Its tail can shift to become prehensile, though it might be questionable if such a thing can be dexterous enough to allow tool manufacture (You only have what amounts to basically just one long finger).
3. Their face tentacles can become prehensile and more sturdy, allowing for grabbing and manipulating objects. Honestly, if you don't want to redesign your proto-species, it's the best path you can take, IMO.
[Answer]
What this creature needs is a path where the future hands are always useful.
Probably start with the studs. You don't have any on its front, you should put some there.
Once they are there, the creature can start using them. First off, it could use them to bump into things. Knock down fruit from trees and the like. Once it's in the habit, having groves and things would let it catch things in stud and push up or down or sideways, which could be useful.
After that, some musculature that would let the stud be moved in place independent of the whole body would help. Even a small ability to shift could be useful.
Once the muscles start to develop, the true arm evolves. The stud is likely to be shed at some point to allow more dexterity.
[Answer]
**You work with what you have got.**
[](https://i.stack.imgur.com/XFHwOm.png)
Thanks to my associate Mushi for illustrating the concept. Your creature has perfectly good appendages. It evolves hands from its feet. Where do you think our hands came from?
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The tentacles that release enzymes will probably grow larger and more muscular, to allow it to pin down prey. Over time, they would evolve into arms on it's face.
Things don't normally just evolve. They need precursors. The only easy to evolve into arms are those tentacles, so they will have to do.
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What if all life (plants, animals, bacteria, fungi, and everything from the smallest cell to the largest whale) disappeared instantly?
And here I don't mean things related to the disappearance of humans such as the erosion of buildings and the fall of satellites, but I mean something related to climate change due to the disappearance of plants and bacteria and things like that within tens of millions of years
**question here: What will the Earth look like after 50 million years of the disappearance of all life?**
[Answer]
Without lifeforms continuously cracking oxygen from gaseous oxides (mainly CO2, and Sulfur and Nitrogen Oxides) the atmosphere would revert to something like it's pre[oxygenation](https://en.wikipedia.org/wiki/Great_Oxidation_Event) composition as much, all?, of the carbon currently in long-term sinks like peat and coal will be oxidised. The exception is probably methane, there will be little to none because there will be no [methanogens](https://en.wikipedia.org/wiki/Methanogen) producing it and it oxidises to CO2 and water relatively quickly. The atmosphere is going be high in greenhouse gases and will warm rapidly, and continuously. After 50MA Earth will be a wetter, lower pressure, version of Venus, the atmosphere will be actively acidic and there will be higher surface pressure due to high levels of water vapour and the liberation of gas forming elements from [biogenic minerals](https://en.wikipedia.org/wiki/Biomineralization) and existing organic deposits. The high levels of sulfur and nitrogen oxides in the atmosphere will give it a brown/yellow haze/smog.
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It would look like a barren planet, something along Mars, with just a thicker atmosphere and maybe more water.
Though all life is gone, so there is no biological agent to decompose organic matter, geology is still active: sediment deposition will cover and hide any biological trace, and what will remain will be rock in different stages of weathering.
[](https://i.stack.imgur.com/Uc7vY.jpg)
Basically what you can see in most of our current dry deserts. With at most ice/snow where it falls.
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If we're talking specifically about what the planet would look like, then fields of grass would be reduced to nothing but soil, forests would be reduced to deserts or barren wastelands, and there would be no more coral reefs dotting the ocean floors. As you'd probably expect, anywhere life has once stood is now desolate and empty.
Considering that this is only going to affect biological life, anything manmade or artificial will probably still be standing proud for a while, but after millions of years, erosion would eliminate most of it. Buildings, even the most well-made ones, would surely be reduced to rubble. Only the sturdiest manmade items would survive.
Photosynthesis would come to a complete stop, so there would be no new oxygen made. We have also eliminated life breathing out carbon dioxide, so it seems like the levels of it would be stable. However, volcanoes would most likely be pumping out large amounts of CO2, though, so the balance would undoubtedly be thrown off. Without plants constantly making more oxygen, the air might be near unbreathable after a while, especially after millions of years.
One thing I have not seen mentioned yet is the effect of nuclear power plants or other similar things would have after being abandoned and falling into disrepair. Humans have a lot of toys that they mess with. If they are completely abandoned for thousands of years, even the most well-made ones will break apart and contribute to this wasteland. Artificial materials would erode bit by bit and add a lot of unique features to this land of desolation.
Without life, the world would be a living hell, but, at the same time, if no one's there to witness the destruction, then there's no reason left to care.
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Oxygen is a byproduct of photosynthesis because photosynthetic organisms on Earth use water as the electron donor. However, the first photosynthetic organism emerged from ocean where chloride is also abundant. Considering that the electrode potentials of chloride and water are quite close, is it just a coincidence that photosynthetic organisms oxidize water instead of chloride?
Although oxidation of chloride can produce dangerous byproducts like chlorine gas and hypochlorite, further oxidation can turn them into perchlorate which is quite stable. Is it possible for extraterrestrial plants to produce perchlorate salts instead of oxygen gas, while extraterrestrial animals ingest perchlorate instead of breathing oxygen gas? My question is not limited to perchlorate, but can be extended to other oxidants like nitrates, permanganate.
[Answer]
*Considering that the electrode potentials of chloride and water are quite close, is it just a coincidence that photosynthetic organisms oxidize water instead of chloride?*
No, it's not a coincidence. Chloride may be abundant, but water is *way more* abundant. And the point of oxidizing the oxygen in water is to crack the hydrogens off of it; oxidizing chloride doesn't get you the same benefits, unless the environment is highly acidic. Otherwise, you don't get hydrogen, you get elemental sodium or calcium or potassium, and nobody wants that!
Now, you might get organisms producing chlorine for other reasons, which can be cool, but it doesn't make sense as a feedstock for basic photosynthesis.
At least, not in a world dominated by close-to-neutral water.
If you are willing to go more exotic with your alien biochemistry and handwave a world where most of the liquid is HCl instead of H2O, then it makes perfect sense. That's a little hard to arrange, but you can get a similar effect with a sulfuric acid ocean--which is exactly what you would get if you cooled down Venus. Chloride and fluoride salts are not stable in sulfuric acid solution, so you do actually end up with a lot of hydrochloric and hydrofluoric acid, and it's much more plausible that you could get organisms using HCl as their hydrogen source for photosynthesis.
Leaving chlorine and chlorates behind, though, other complex oxidizers are entirely plausible. Oxygen itself, for example, is extremely poisonous to anaerobic life. Early oxygenic photosynthesizers got away with producing it because they could eject it into the environment where it diluted enough to not kill them for long enough to evolve increased resistance to it (while killing off their competition at the same time). Given that things like nitrates and phosphates are biologically useful materials anyway, it is not much of a stretch at all to imagine that life on a different world might decide to deal with oxygen toxicity by immediately locking up any liberated oxygen into other compounds, rather than just letting it diffuse freely. Hal Clement's novel *The Nitrogen Fix* posits that this is in fact the more typical state; the alien in that book is native to a world where plants all produce nitrate, animals eat or drink it, and nothing needs to breathe, and only contacted Earth after an apocalyptic disaster converted all of the oxygen in our atmosphere into nitrate, leading to the near-extinction of pre-existing complex life; until then, the aliens didn't consider Earth to show any obvious chemical signatures of advanced life! And nitrate does seem like the most likely form for oxygen to be bound in, simply because nitrogen, like oxygen, is extremely common in the environment and in biomolecules. Manganese, sulfur, and phosphorus could be used as well, but when those run out in the environment, there will always be more nitrogen.
Of course, if you happen to have a lot of sulfur in the environment, then photosynthesizers may just stick with hydrogen sulfide as their hydrogen source indefinitely, producing elemental sulfur as a byproduct, which animals would have to eat. This would have the side effect of steadily converting CO2 into carbonyl sulfide (COS) as the hydrogens from hydrogen sulfide are transferred into oxygen from CO2 during photosynthesis, producing excess water, and then carbohydrates are oxidized by sulfur to produce H2S and COS instead of regenerating CO2. Plants would then have to adapt to using COS as their main inorganic carbon source rather than CO2 in order to close the cycle.
On a sufficiently hot would, animals could *breathe* the sulfur, but that is getting into even more extreme speculative alien biochemistry. Hal Clement wrote another novel, *Iceworld*, about sulfur-breathing aliens whose equivalent of water is molten copper chloride!
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I see a major problem: oxygen appears in a lot of organic molecules which are interesting for life, like carbohydrates, proteins, lipids and so on. This thanks to its 2 valence electrons, allowing it to be used both in between a molecule or at its end, by binding either with two different atoms or with a single one.
Chlorine, on the other hand, has a single valence electron, meaning that it can bind only with a single atom, thus necessarily at the end of an atomic chain.
This is why some alternative oxidative paths use sulfur.
You can still try to have an hybrid chemistry using both chlorine and oxygen, but you would need an efficient way to prevent competition between the two species when it comes to chemical reactions.
[Answer]
## Other elements have their quirks.
You can use chlorine, but it is very prone to free radical chemistry - unwanted cyclic reactions that go on and on.
You can use fluorine but except as the ion it is very prone to stick on carbon "like glue" and go nowhere. PFAS compounds, "forever pollution". Very tough to work with biochemically.
You can use bromine or iodine, but there is almost nowhere they would plausibly be common.
You can use nitrogen, but it pairs up into nitrogen gas in preference to any other state. Nitrates want to be TNT or ANFO bombs. You don't want an exploding planet (probably ... though it always does wow the tourists). And we do use it already in our planet's biochemistry anyway.
You can use sulfur, but it's not a very strong oxidizing agent; also, we use it in our biochemistry at a fundamental level already.
Your idea of perchlorates is one of the best options (oxygen and chlorine). AND [they are actually present on Mars](https://www.nature.com/articles/s41598-017-04910-3), so we know it's possible *without* life. Unless there's life on Mars, that is...
[Answer]
**Sodium metal could be your carbohydrate equivalent**
Photosynthesis on Earth uses H2O and CO2 and energy. Modern plants store light energy as chemical energy. Plants strip the hydrogen from the H2O and store it on the CO2 forming carbohydrate. The oxygen is released. Later the plants (or heterotrophs like us) reclaim that chemical energy by grabbing some of the O2 it let loose and combining it back, regenerating the H2O and CO2 and releasing the energy into some chemistry.
Let us imagine your plants do electrolysis of NaCl aka salt. Radiant energy is used to produce elemental sodium and chlorine. Energy is stored as sodium metal in the plant - maybe stowed in some greasy hydrocarbons. Chlorine gas is released.
The world has an atmosphere full of chlorine gas produced by photosynthesis just as ours has a lot of oxygen gas. When the plant wants to reclaim the energy or something eats the plants, the sodium metal stores are reacted with ambient chlorine gas to regenerate salt.
Other salts could be treated similarly - for example magnesium or lithium chloride could also be electrolyzed to the metal and chlorine gas. I could imagine plants might evolve an end run around herbivores by switching their metabolism to produce a metal that the herbivores could not use.
Can you builders grok a plant whose tissues are silvery crystals with a greasy sheen, seen dimly through the yellow haze?
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Because of Reasons™, an organization in my world needs to design and construct a transmitter capable of continuously pumping out a looping radio transmission that can be recognized and deciphered out to about sixty thousand light-years.
Roughly how much energy would said transmitter need to dump into the signal to accomplish this? How the energy is acquired is of no concern - this organization can daisy-chain Dyson swarms if that's what it requires.
[Answer]
<https://en.wikipedia.org/wiki/Jansky>
>
> The jansky (symbol Jy, plural janskys) is a non-SI unit of spectral flux density,[1] or spectral irradiance, used especially in radio astronomy. It is equivalent to 10e−26 watts per square metre per hertz.
>
>
>
It all in some complicated relationships with other stuff, funny and with pictures <https://science.nrao.edu/facilities/vla/docs/manuals/oss/performance/sensitivity>
Which also includes exposure, which defines bitrate as well, and defines detection range.
Looking at [Radio telescope sensitivity calculator](https://www.atnf.csiro.au/people/Keith.Bannister/senscalc/) and understanding not so much from it, but having some fantasy and gaming expirience from playing with it, totally ignoring antenna gain, and just taking System Equivalent Flux Density (Jy) == 1743Jy, which I understood as antenna own noise it has at 50K etc.
We probably ready to estimate lower limit for signal detection, but warranty is void at inception.
Energy required to arrive to a detector looks like 3e-23 W/m2/Hz (that Hz thing is not that important for our estimations it can be 100MHz band or monohromatic source, things are not necessarily that simple there but let's ignore for simplicity)
So omnidirectionl source emitter should be about 1e20 W, if a reciever is 1m2 antenna. So bigger antenna can slash the number proportionally to its area, 1km2 as an example, maybe by 6 orders of magnitude. A dyson worthy big one, 10'000'000 km square, probably can slash it down to a 1W, eh.
If it is a more directional emitter, it also can help reduce power requirements, getting there 4 orders magnitude reduction is reasonable enough with usual phase array, and more with some laser based solutions, but there will be limits defined by all kinds of factors.
Bitrate also affects required power, but it hard for me to tell, but for current numbers, as it defined as detection with 1s exposure(which comes from watts in Jy), it seems that number has to be multiplied by desired bit rate, but I can be wrong about that.
So 1MW emitter, 10'000 by 10'000 km reciever, modem bit rate from 90's can be a valid setup, for directional connection. And few GW's for omidirectional signal.
Hm, seems someone needs to make bigger antennas, eh, because it seems if we need to waste more than few GW's they aren't worthy to listen to our radio station with best hits from 60'000 BCE
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The most powerful transmitter in a solar system is ... the star. We know that we can detect a star out to 60k light years because we know of stars at that distance.
So if we want to broadcast across the galaxy, it may be cheaper/easier to modulate the output of your star than to build a terawatt-scale omnidierctional transmitter.
How can we modulate a stars output?
* Controllable mirrors/lenses on a dyson sphere.
* Use a gravity lensing to direct light at/away from a NULL target
* If you tap the star (eg sci-fi constructs penetrating into the stellar atmosphere) maybe you can alter the fusion rates directly.
* Temporarily reduce the effects of gravity within the star. This will permit the star to expand and slow down it's fusion. Given time this would dim the star. I don't expect much bandwidth with this method.
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This idea came to me after reading up on the relationships of the [prairie vole](https://www.ncbi.nlm.nih.gov/books/NBK97287/) and the research done into why monogamous pair-bonding occurs. What I'm looking for in my story is biologically enforced sexual monogamous pair-bonding, and how science could stop it. People in pair bonds do not have to be in love, and in fact being pair-bonded does not mean you will *love* your partner necessarily, only that you are only sexually attracted/can mate with them. (for more context on the worldbuilding, look to the end of the post)
**The Research so far**
So the closest animals I could find that were sexually and socially monogamous seem to be the prairie vole's. [One article](https://www.ncbi.nlm.nih.gov/books/NBK97287/) has this to say about biological reasons for what causes the pair bonding:
>
> Several studies have now demonstrated that oxytocin plays a role in
> the development of the pair bond in the female prairie vole.
> Injections of an OT antagonist, a drug that blocks activation of the
> OT receptor, directly into the female prairie vole brain prior to
> cohabitation and mating inhibits the subsequent development of a
> partner preference (Insel and Hulihan, 1995).
> Some studies have suggested that OT's role in partner preference
> formation is specific only for females, while other studies have found
> similar effects in both sexes (Cho et al., 1999). However, in males
> there is clear evidence that the peptide arginine vasopressin (AVP)
> plays a significant role in the formation of the pair bond of the male
> for its mate.
>
>
>
I'm not a biologist so I don't really totally understand everything in the linked article, but essentially what I got out of it was that mating between two specific prairie voles lead to changes in their brain chemistry - the release of OT and AVP - while around their preferred partner. Essentially 'love is a drug' and this causes them to seek out that preferred partner who gives them more OT or AVP. This is more 'emotion based' than I am looking for, but I think it's a good start maybe?
I'm not sure if prairie voles can be considered *entirely* sexually monogamous, however, as there have been studies that prove the genetic offspring is sometimes fathered by a male outside the pair bond:
>
> For biologists, monogamy implies selective (not exclusive) mating, a
> shared nesting area, and biparental care. In recent years, genetic
> analyses of offspring have provided evidence for extra-pair
> copulations even among species thought to mate exclusively
> monogamously.
>
>
>
[Additionally:](https://www.nytimes.com/1990/08/21/science/mating-for-life-it-s-not-for-the-birds-of-the-bees.html)
>
> The incidence of sexual monogamy appears quite rare in other parts of
> the animal kingdom. It is becoming clear that even animals that are
> overtly socially monogamous engage in extra-pair copulations. For
> example, while over 90% of birds are socially monogamous, "on average,
> 30 percent or more of the baby birds in any nest [are] sired by
> someone other than the resident male."
>
>
>
Based on this, I'm not even sure if there are any existing species that are entirely sexually and socially monogamous. If there are and I just haven't found them, please let me know (if there's research on it anyways) what allows them to be sexually and socially monogamous on a biological level. Additionally: how could such enforced monogamy be broken with science?
**For more context, this is my worldbuilding that I'm trying to back up with science:**
World has late Victorian/early Edwardian era level of technology and scientific advancement (if needed I could come up with some reason they have more advanced science though). The people are essentially humans except for the changes needed to be made for sexual monogamy/pair bonds to work (aka if I need to give them the ability to smell pheremones or something I will but otherwise they are just human). All men and women are thought to be 'incomplete' before they bond with someone, as the Creator made men and women together as two sides of the same coin/soul but seperated them at birth. Only once they become one once more are they 'whole.'
As soulmates are 'ordained by the creator' only the church can know who is truly meant for who, as they are the voice of the creator. In reality bondings are done for political or socio-economic reasons, though there is a lot of romanticisation of 'falling in love at first sight' like in our world. (fun fact: the church is always lead by a pair-bonded priest and priestess. They give up any children they have to the church to become men/women of the cloth where they are raised communally. There is no prohibition of sex or having children within the church.)
Bonding happens upon consummation of a union (sex/mating) and from that point on it is impossible for the two to have sex with anyone else - meaning they will not be sexually aroused by anyone else or physically attracted to someone else and cannot bond with someone else. It does not mean that they necessarily *will* be attracted to the other person, only that they can *only* be attracted to them. By this I mean that men can still have ED and women can still not have fun in the bedroom if their bonded sucks at sex. The only way for anyone to bond with someone else is for their bondmate to die.
The story is about a woman activist who finds herself in a very unhappy bonding and wishes to find some way to break it without killing her bondmate and going to jail for murder.
**TL;DR:**
* what biologically could cause complete sexual monogamy within a pair-bond? I'm not looking for cultural norms, but rather a biological reason for why a bonded pair would only be able to mate with one another after having sex.
* what scientifically could break or reverse such a biological pair bond?
**Bonus points for helping me with these questions too:**
* whether pair-bonding has to be tied to orgasm during mating.
* how this biological pair bonding would affect sexual aggression.
* how this biological pair bonding would apply to LGBTQ attraction.
[Answer]
**Warring parasites in sexual fluids**
Each person is host to a unique parasite on their genitals. When a couple has sex, the fluids transfer some of this parasite to their partner.
One male parasite and one female parasite (probably different species) will happily coexist. However, if a man hosting one female parasite is exposed to a *different* female parasite, the two engage in chemical warfare that produces intense genital pain for the man. And similarly for women. People learn *very* quickly not to cheat.
These parasites can’t live forever on the “wrong” host sex, though, so if your bonded partner dies, their parasites on you eventually die too (during the cultural mourning period), and then you’re free to bond with someone new.
Science addresses this with medication that kills the parasites, or at least reduces them to a population level that isn’t painful, allowing you to boff whomever you want.
Bonus questions:
1. Orgasm means more/different fluids, or if you wanted orgasm to be mandatory for bonding, parasites are only transferred in those fluids, or there’s some reaction to OT/VAP that triggers them to stick around.
2. If OT/VAP is needed for the new host to be attractive, then a male rapist would be bonded to his victim, but the victim wouldn’t be bonded in return, which seems fitting.
3. LGTBQ bonds would require a much more complicated system, or perhaps changing from male/female parasites to a system of repeated exposure to make bonding happen: any two parasites will accept each other but will jointly fight a third.
If you want the church to control all bonding, then make the parasites attack *any* foreign parasite unless some special holy oil is present, which is applied by a priest to the genitals of a newly bonded couple before they consummate their bond. That would also solve the LGBTQ problem, but it rules out the parasites having evolved naturally along with the hosts.
[Answer]
# Fluids and immunity
People can feel attracted sexually to anyone of the opposite sex, but only up to their 1st mating. They will then develop immunity to proteins in the fluids of each other.
After that, having sex with someone else is like exposing yourself to a variant of a virus that you've already develop immunity too. Fluids are as specific as the cell markers for bone marrow transplant. Mating with someone other than your spouse will get you sick, and possibly fatally, unless you had sex with their identical twin. Over time evolution favors the monogamous, so the drive to maintain a partner is instinctive and completely neural. Some people do fornicate outside the pair but they get sick and die.
Science resolves this with a broad spectrum vaccine (fluids from lots of people mixed in a vial for innoculation) which when applied prior to losing virginity maintains the ability to be attracted by multiple people. The church is going to flip when they find out.
[Answer]
## It Always Hurts the First Time - Both Ways:
My solution sounds radical, but is completely plausible. Male gonads are detachable, and implant in the female. Unbonded males and females are sexually attracted to other singles, but once they have sex, the male gonads implant in the female and produce pheromones. Other males are repelled by these pheromones, but the male who's gonads are implanted find them irresistible. Females with implanted gonads only become aroused after sex starts, so they will only have sex with their specific male because he's the only one that finds her attractive, and she's unaroused by anyone before then (very Victorian).
The female doesn't need to have sex to have children anymore (she's got a set of male gonads in her), but the male stays with her protectively because of his compulsive attraction/arousal around her (assuring her survival and that of their offspring).
As to how this affects homosexual relations, it is up to you. It would be likely that prior to first mating, they could mate freely (depending on how it was handled - male on male prior to first mating might be strange). After mating, males and females with mates would be able to have sex with other people, but only in the presence of their mate (so threesomes and maybe foursomes would be possible). Again, depending on how exactly the female arousal worked, it might require insertion or not, and females would not be excited until they already had sex.
For Victorian technological levels, reversing this is complex but possible. Removing the male gonads from a female without sufficient surgical skill was lethal, but advances in medicine finally allow a female to be unfertilized (surgically or by the discovery of a drug that causes her immune system to reject the gonads). The female would thus stop repelling other males, and the gonads would stop suppressing her desires outside of sex. The male might regrow gonads after a sufficient time not having sex with his partner (to simulate a widower being able to remarry), or the gonads might be able to be sewn back on to the male. But in this case, the similar operation (call it a stitch-job) prevents the gonads from releasing into a new female, allowing the male to continue seeking a mate indefinitely.
[Answer]
**Psychological imprinting**
It’s no different than baby chicks that associate the first thing they see as their mother. The instinct is already there. I would probably go something like this; person one cuddles and shows signs of intimacy to person two. If person two reciprocates the action a switch is flipped in both of their brains that marks the other person as their partner for life. Once bonded the affected person can still like other people but can never feel a romantic or sexual love towards them. If the person tries for some reason they’ll feel intense disgust and be forced to stop. So basically the limbic system (emotional center of the brain) is affected and handles this like every other like and dislike matter.
The thing you’ll have freedom with is what happens if the two get separated in a way or another. Swans are famous for killing themselves out of depression when losing their partner or their eggs. So what would happen if a pair was appart for a long time and one was told the other was dead? Whatever suits the story, but you’ll probably want something that ups the stakes. There’s also the unexplored territory of what happens when someone severs the bond and goes on to be with someone else.
To forcibly disable the instinct I would suggest a form of risky chemotherapy to remove the marker from the limbic system. The risks may include many clinical manifestations, such as epilepsy, limbic encephalitis, dementia, anxiety disorder, schizophrenia, and autism.
[Answer]
**I can't give you the level of science you're looking for, but...**
The relationship between the voles can be described as *addictive.* It's been seen before in SciFi: in Frank Herbert's *Chapterhouse Dune.* In that story the Honored Matres, a deriviative of the Bene Gesserit Sisterhood, come back from the great scattering. They've lost some of what the BGs had (and want it back!), but they've replaced it with other things. Among them, *sexual enslavement.*
Like all good writers, Frank Herbert didn't spend a lot of time on the biology of how the addictive relationship was formed. I'll be honest with you, unless you have the necessary college degrees to really understand a fully scientific answer, it won't really help you. You won't know how to use the information you've been given in a way that would help you sound any more credible when you write your story. I'm not trying to be mean! I'm just pointing out a reality. Unless you want to become an expert in the field, you should seriously consider what Frank Herbert did: not explain it and move forward.
**Having said that...**
What Herbert explained in his book was what that science article described about the voles... only on super steroids. If you think about it, he had to do that. Humans can reason their way into and out of pretty much anything. Take my grandfather (rest in peace!). He smoked every day of his life since he was a teen. In his late 80s he was told by a doctor he'd die in six months if he didn't stop. He stopped. Right then and there. And lived for years.
Humanity's divine gift of reason means no simple chemical bond will fully explain an entirely monogomous relationship. Or, said another way, those voles don't really have a lot of choice in their lives. It's not like there's newstands with vole porn on street corners and vole hookers on the other corners. A simple chemical addiction can keep them permanently pair bonded.
But humans can't... unless you introduce an idea like Herbert did. In his case, it was basically "super sex" so intense that the chemical wash resulting from orgasm caused an unbreakable addiction to the partner. You couldn't be satisfied with someone else. You had to go back, again and again.
**What I recommend you do...**
You have all the tools you need to solve your problem already in a wonderfully artistic way. When the time comes in your story to explain why the forced monogomy exists, use a "practiced in the art" medical professional to explain it to someone who is not practiced in the art (like a journalist) — and have that person literally say, "you know, it's something like what you find in voles... the bonding experience uses a natural form of oxycotin that creates an addicted co-dependency that forces the pair together. It's a lot more complex in [our species], but it's basically the same thing."
And when the time comes that you explain how the dependency is broken, you can reverse the explanation by describing how people become unhooked from drug addiction.
That might not be the answer you were looking for, but considering how few of your readers will appreciate any greater detail (indeed, considering how many would become bored reading any greater detail...), I'd like to think it's good advice.
[Answer]
**It's all in the mind...**
Let's start with :
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> whether pair-bonding has to be tied to orgasm during mating.
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Psychological bonding without any sexual intimacy is arguably stronger than any sexually-based bonding. People can be made to be extraordinarily loyal to another person and this fact is often used by the more manipulative people in society to keep people loyal to them, including their mates. We also see this happen with cults as well. Sex is used to augment/compliment psychological bonding in this context.
People can have quite miserable and downright unpleasant sexual couplings with a partner they are otherwise devoted to. It just isn't as simple as sex cures all, and I would suggest it's often the case that sex can break a relationship, not make it.
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> how this biological pair bonding would affect sexual aggression.
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Hard to know what you mean by "aggression" here. If you mean aggressive sexual behavior then some people engage in that and it it does not necessarily improve or damage a relationship - it is very dependent on the details of the people involved. Nothing really changes in the context of "chemically" bonded people, except that it could result in increased levels of violent sexual behavior, as one party (or both) cannot stop being a willing victim.
If you mean aggression in the sense of aggressively seeking other partners, that can happen even in relationships where both partners are very strongly bound. It is typically destructive. What would happen is your scenario would be that the aggression is focused within the single relationship, leading potentially to more extreme behavior by one or both parties.
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> how this biological pair bonding would apply to LGBTQ attraction.
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No differently from heterosexual couples. It's the same process.
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> what biologically could cause complete sexual monogamy within a pair-bond ? I'm not looking for cultural norms, but rather a biological reason for why a bonded pair would only be able to mate with one another after having sex.
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Nothing.
The problem is that you would no sooner create such a mechanism that someone would figure out how to bypass it. It's what humans are good at.
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> what scientifically could break or reverse such a biological pair bond?
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The mind.
What the mind giveth the mind taketh away.
You can use psyschology (and maybe a bit of chemistry to help) to bond people, but the problem is once you stop manipulating them they tend to revert to type. Even if that doesn't happen someone else can break the bond using similar techniques.
In a long recorded history no cult, politician, military leader or religious leader has succeeded in stomping out adultery. The Great Augustus tried (on penalty of death, IIRC) and failed. Religions tried (penalty of all sorts including death and eternal damnation - a thing people at one time feared more than death) and failed. Cults ranging in size, sophistication and scope tried and failed.
**Call in Marketing, forget R&D**
To actually do this would require completely robbing people of their free will. You mention not relying on cultural norms, but in practical terms cultural norms are much better at enforcing monogamy than anything else. No system is 100% perfect, but I think cultural norms are more successful than average. With cultural norms you can get people to do things that you would consider unthinkable. It was at one time culturally normal to put people in an arena and let wild animals rip them apart - and that's the tip of the unpleasant iceberg for the dark side of cultural norms. Today we have so-called "honor killings" for the sake of what some people consider cultural norms or pressures. Don't ever underestimate the power of cultural norms to make people do and endure extreme things.
It is basically trivial to create a society where cultural norms make staying in a loveless or sexless marriage common and where transgressions are treated are crimes. It is, by comparison, beyond our current science to even guess how you would impose such behavior on people using chemistry - we don't even know what buttons you need to press.
I can't imagine a mechanism you could come up with that didn't amount to basically discarding the entire personality and replacing it with something else. Any chemical mechanism could fail, become tolerated (and ineffective) over time, or have long term side effects that were worse than the disease, as it were.
So if you want to manipulate people on a grand scale, don't call R&D, call Marketing.
Every Doctor Evil needs a marketing department.
[Answer]
## She keeps his balls in a jar
The first time a male and female mate, the male transfers his testicles into the female's body instead of ejaculating just the sperm. This would be a completely separate event from a normal orgasm as it would be a once in a lifetime thing that seals thier bond. From then on, the female's body sustains the testicles inside of a specialized organ (which we will call her jar from here out) for the rest of her life. To ensure monogamy, once the woman has the man's testicles it provides her body a pheromone that is exactly keyed to the man's physiology. This pheromone makes the woman repulsive to any man who it does not match, and attractive to the man who the pheromone belongs too.
Furthermore, once a woman has his testicles in her jar, she would likewise lose all sexual attraction to any man who does not match the hormones they now pump into her body.
From this point on, when they have sex, the man does not ejaculate any sperm, but he does ejaculate an activator hormone that signals the testicles to release sperm into her body. Even in extreme cases where the female does find some other guy to copulate with despite natures attempts to make them chemically repulsive to each other, the woman could only ever have the 1st man's children because the jar seals up once it has some testicles in them.
**How to break or reverse such a biological pair bond?**
The only way to break the bond would be to surgically remove the testicles from the female's body. This would make breaking the bond far more difficult than just choosing to, but rather it would REQUIRE significant scientific intervention.
**How does it affect sexual aggression?**
The prominent theory about why humans experience sexual aggression is because of the role cuckolding holds in selective fitness. A man can only produce enough resources to support so many children. Being cuckolded means you will limit your number of offspring because you are wasting resources on someone else's offspring and cuckolding another man allows you to save resources on reproduction and have more children than you can support. Because of this, letting another man have sex with your partner is much the same as letting him murder your children (evolutionarily speaking); so, we have evolved to be aggressively protective of our mating rights.
But, if your mate could only ever have your children, this would mean that no matter what she does, she can never cuckold you. With this out of the way as a concern men would no longer have a reason to fear or be angry about his mate having relations with other men; so, sexual aggression would be virtually non-existent.
**How does this affect LGBTQ relationships?**
In a since, LGBTQ can be described as various kinds of failures for nature to create selectively fit bonds based on pheromonal/hormonal paring. But in this world, we get a whole new dimension to the sexual orientation spectrum resulting in things like men who are only attracted to women who are paired to other men, men who are repulsed by the woman they are paired to, paired men who are only attracted to unpaired women. Paired woman who are only attracted to unpaired men. So on and so forth... so this system would allow for all of the normal atypical relationships we have in our world, but also opens up a ton of new ones as well.
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[Question]
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Why would small rail vehicles exist alongside cars & normal passenger trains in the near future? In this world rails run throughout cities for metros & every town has a rail connection outside of the smallest (<1000 people). While cars exist in a developed capacity already (this world is a continuation off the current one with a few bits of alternate history thrown in so that some things make more sense), what would cause small rail vehicles to replace about 20-50% of personnel cars? These small rail vehicles are for personal transport with size going from that of an SUV to that of a large van or small truck. These vehicles would run alongside regular passenger rail & cargo trains, with the passenger rail having frequent enough services that scheduling doesn't matter much or the distances mean traffic wouldn't be interrupted without very large amounts of rail vehicles. These vehicles are mostly privately owned but some are rented out by companies & the public transport operator.
(BTW this isn't supposed to be a "gadget-bahn" type deal where its just making worse trains for the sake of looking fancy)
[Answer]
### Mini-trains can be routed more efficiently than a full passenger train in a large station network
Ever been on a subway / train with more carriages than people? Does that seem efficient?
A while ago I described [this city](https://worldbuilding.stackexchange.com/a/189813/78800) to explain why a city could be hexagon based. My answer was that every house is always within x minutes walk of a subway station - so there's no need for cars. Because this limit makes a circle, and because of efficient circle packing, hexagons form.
If everyone is living in nice suburban housing that isn't particularly dense, and the primary mode of transport is a subway in the middle of your suburb, you have 1 subway station per, say, 1000 people. That's not a lot of customers outside of peak times, and a lot of routes if a traditional subway line was to service them. A city the size of New York would have 20 times as many subway stations (8419 stations instead of 472.), and probably 720 lines instead of 36.
So - small (or even private) subway carriages. You get in, pick your destination, and the rail network automatically directs just your carriage to it's destination. No need to lug 100 meters of train to haul 4 people.
At peak times, there's 30 mini-trains waiting at the station stretched along the platform. An app on your phone (or an info booth) directs you into, say carriage 16 of 30, which happens to be going to your exact final destination. Since people are registering their routes by querying in an app, the super computer has a few minutes warning to optimse the next set of mini trains to pull up at the station given the destinations of those waiting at the platform.
Full sized trains are still used between cities, or on exceptionally busy routes.
[Answer]
**Two Problems Have Been Solved!**
The situation you're describing is terribly dangerous. Mixing small lightweight cars (2200 pounds) and huge goods trains (up to 219 million pounds) is not a good idea because trains take an awful long time to stop. Most drivers of cars are essentially careless at best or woefully untrained at worst. Train drivers are certified and generally require continuing education.
Your near future has solved two problems sufficiently well to allow a broad mixture of vehicles to travel safely on the rails.
**Problem 1: Physical Infrastructure**
Many mainlines around the world are double tracked, which generally allows for multiple trains to move in opposite directions. Some are quadruplicated which allows for more traffic and allows for differentiation based on speed or train type (goods vs passengers).
Your system shall have been upgraded to all lines being doubled at the minimum. Most mainlines shall have been upgraded to six tracks or even eight. Stacking of lines, by building bridgework on top of ground level tracks, can easily increase capacity to sixteen tracks. Trains can then be separated to run along the ground level tracks while small vehicles can run above on the bridgeway.
In addition, all lines will have many more points or switches along the way to allow for traffic to be shunted from track to another. Switches will be much closer together to accommodate the smaller vehicles.
All intersections between rail and road will have short accessways that will allow the vehicle to transition from rail to road operational modes and back again. These accessways will serve the same function as motorway on and off ramps. No large intersections will be at grade -- all but the least busy intersections will consist of bridges or short tunnels.
**Problem 2: Intelligent Control Infrastructure**
More tracks and more trains and the addition of cars, trucks, vans and busses on the rails will mean more headaches for train controllers. Typical control & signalling systems won't be able to keep up. In your system, the most advanced systems we currently have will all be replaced by a fully automated system of AI controllers that rely on vehicle GPS locators plus input from vehicle sensors. Most of the AI work is done at the local level -- in your own car or bus -- as it coordinates with the vehicles around it through the local and regional control systems. The AI will continue to be monitored and directed by well trained human controllers who have access to not only the computer data but also traffic cameras, hazard detectors, weather station monitors, etc.
Because rails limit the manoeuverability of smaller vehicles, the driver will relinquish basic control to the on board AI. She will still have to monitor the usual variables of speed and surrounding traffic and will have to be aware of her course & route plan and will have to be ready to adjust if a change in plan is required. The AI in coordination with the local controllers will manage & execute a vehicle's entry to or departure from the railway.
[Answer]
## Reason #1: Your World is Going Green
Electric cars are considered better for the environment than gasoline cars. Best case scenario, they can be powered by renewable energy sources like wind and solar. Even in the worst case scenario where you are still burning fossil fuels to power them, large scale powerplants can implement much better carbon reduction methods thanks to operating at a larger scale than millions of little internal combustion engines can.
Unfortunately, electric cars need some rather exotic materials at very high volumes to be able to replace the internal combustion engine industry completely. Mainly: lithium for their batteries. At the world's current number of automobiles, we do not have enough known lithium reserves in the world to meet the need of replacing all of our cars with electric cars, but if you take batteries out of the equation, then it is much more doable.
By putting private electric vehicles on tracks, you are able to keep them running off of the city's environmentally conscious power grid while also eliminating the need for batteries. As for how near future this could, be: the city of New Orleans actually recognized the advantages of rail vehicles several years ago, and used this knowledge as motivation to restore its old system of streetcars (after many years of being out of use); so, now New Orleans uses streetcars in place of city busses in many areas. If a city like New Orleans where to expand their already existing rail system enough, it would make since for people to start taking advantage of the rails for private vehicles too.
[](https://i.stack.imgur.com/LnIQ8.jpg)
## Reason #2: Safer Self-Driving Cars
One of the biggest challenges for self-driving cars is making sure that they can see roads, intersections, etc. in all weather conditions. Rail vehicles however are much easier to program. Instead of needing to "see" things, in most cases, a rail vehicle just needs to follow the track; so, bad weather will never make it drift out of its lane. Things like speed limits, stop signs, etc. are also much easier for a rail vehicle since you can just feed that data to cars via the rails. Coming up to a stop sign that is covered by a tree? No problem, the track lets you know when you need to stop. With most of of the work your car needs to do now being fail-safed by the tracks. Self-driving cars would be much less likely to hurt someone.
If this safety margin proves large enough, it could even motivate governments to ban self-driving cars, but not self-driving street cars. In this case, the allure of being able to buy a self-driving street car could be enough to get people changing over from roads to tracks.
[Answer]
**Future cars will have the ability to run on rails**
[](https://i.stack.imgur.com/jT5Gg.jpg)
Rail+road vehicles will have important advantage over road-only vehicles. They should be able to travel by computer-controlled, streamlined railways which would allow them to beat city gridlocks and traffic jams with ease. In the intercity travel, rail vehicles would be able to reach speeds that are not safe at all for public highways.
[Answer]
The geographical conditions make it difficult to build roads once a railway is present, therefore using the railway is often preferred because the network is more and better developed.
Once more small rail vehicles meet they can set up a temporary convoy, creating some efficiencies.
[Answer]
**There are three changes needed**
1. **Less road infrastructure**. Maybe fewer lane-miles, maybe lighter bridges, other possibilities. Fundamentally it must be less convenient and more expensive to travel by road than presently.
* Example: Perhaps the USA didn't undertake the monumental 1912-1916 grade-separation project in large cities, and subsequently didn't invest in the U.S. Highway system in the 1920s-30s nor the Interstate Highway system in the 1950s-1980s.
2. **Robotic Coupling, Computerized Dispatch, and Distributed Power**. Today's freight trains have improved incrementally from 1880: Head end motive power and air brakes. It's cheap and effective, and current freight railways compete on price (not convenience). By comparison, urban passenger trains tend to use distributed power and dynamic braking. They compete on convenience (not price).
Distributed-power freight trains with automated (robotic) coupling/decoupling is certainly possible. They would be more flexible and safer...but also more expensive. You must handwave away the expense.
Once all vehicles on the network use predictable/reliable traction/braking systems, have safe/rapid coupling, and are all under automated control, then you effectively have *self-switching vehicles*. Your dispatching can mix and match vehicles into dynamic trains for distance travel, or sort them into safely-separated discrete vehicles for short hops. You can optimize the network operation for price, for convenience, or any other factor you wish.
3. **Organizational shift of railways from owner-operator to open-access**. This shift has been underway in Europe for about 20 years. It involves quite a bit of standardization (like signals, path planning, and dispatching) and regulation.
You need an infrastructure-only organization to fairly dispatch the system, and to oversee the vast increase of rail infrastructure needed. Freights tend to run about 80-100km/h intercity, much slower than passengers are generally willing to tolerate. You might need two side-by-side networks, one for slower freight and one for faster passenger, to keep adequate capacity in your system. Happily, you can have quadruple tracking in only 20-25m.
[Answer]
## The valuable thing about a railroad is the *right of way*
That's why Rails to Trails exists: to prevent the abandoned right-of-way from being sectioned off, so it can be held in reserve for something really valuable in the future!
You typically have a 25 meter (80’) right of way, and regular railroad tracks take 4 meters (13’) per track, transit somewhat less. So if you are pushy, you have space for 6 tracks before we start using eminent domain to shave people's backyards.
So for regular railroad operation, you allocate 2 freight on the outside / 2 passenger on the inside, compatible, so they can borrow each other's same-direction track for overtakes). That takes 4.
We got really good at autonomous vehicles, and they use slightly different rails (not interchangeable, don't want to mix those). So 2 additional tracks for your modular vehicle system. That is workable. All vehicles travel at the same speed. They are either computer controlled with close following, or you lash up many vehicles into trains so they dispatch as one vehicle, or both.
I doubt they would work as personal vehicles. Rail requires very consistent maintenance of vehicles. So this would be best done as one or many agencies or companies all repairing to the same standard. Both wayside detectors and onboard fault analysis would be looking for anything that could derail a train. There would be maintenance intervals and condemning limits for everything. *You really couldn't leave this kind of maintenance to citizens. They don't do PM, and can barely pass smog today*.
## Speed is the answer
People won't just leave their cars behind, they'll leave their Cessna's behind.
Once trackways and maintenance are to this level, speed becomes less of a threat to safety. The aerodynamic drag of high speed movement is largely solved by coupling cars into trains.
So you can get going pretty fast. 150 mph would be well within reach, and remember, with "first and last mile" shuttles (which are cars), your portal to portal trip time is quite good.
## Stuff
The remaining trick is carrying your stuff. That would be done with containerization. All your stuff goes into a standard container which clips into the vehicle.
Containers come in several sizes, from suitcases to the size of a Sprinter van. There are train modules to fit each one.
There are "last mile" services much like DoorDash or Uber today, which will get your container from your house to the rail station, and from the destination rail station to your destination. They'll do the same for you as well.
Say you're an plumbing contractor who's going to Flint MI to fix bad pipes. You have a container with all your tools and supplies. You call for an Uber, the Uber shows up, grabs your container, grabs you and your apprentice, and off you go to the train station where you and the container get on a truck-module. Whoosh, through the system you go. At the Flint train station, another Uber shows up and takes your container to the job site. End of the day, another Uber takes it to secure storage and you to a hotel.
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[Question]
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Afternoon everyone,
In my setting, humans live in isolated "burrows" with an immense and dangerous forest separating them. Rather than planes or helicopters, trains and super cannons are used for travelling. The train is used for more affordable, slow travel while the cannon is built to get people quickly to another burrow. In addition, it's also used by a class of soldiers for rapid deployment, similar to paratroopers or the glider troops of WW2. I was thinking that they would either be inside the "bullet" shot or they would be in a glider of sorts that is attached to said "bullet" and the glider would detach to take the troops where they need to go. Space travel has not been invented, so it will not be used for that, just traveling on the surface of the world. How viable would this be?
Thank you
[Answer]
**Not viable at all**
The problem is that you need a high speed to get a body from one part to another. If the burrows are within trebuchet range, it might be possible by only using those. But if you need super cannons, it isn't viable at all.
The simple fact is that you need a high speed. This high speed you need to achieve in the distance you travel through the cannon (else it's more rocket powered). To achieve this, you need high acceleration. With such high acceleration, you'll be dead. Even if you make the cannon really big, the main power is often explosives. To accelerate the person, you'll need to use a sabot (they're not fully crazy) that can take the brunt of the force. Still, you're going to have a bad time with the crazy acceleration. To manage this better, you would need basically a sabot that holds the person, like with a mould. Then you need to have them hold their breath as they launch, as it's nearly impossible to breathe.
In short, the powers are simply too big.
*However*, you can use the gliding method. If you have a large enough village or burrow, you might be able to simply draw a person in a glider forwards. If you do this fast enough, they can get height and thus range. In addition, you can use glider (and some bird) methods with hot air circling to get to greater heights and fly to another burrow. So instead of building a super cannon, they might just be very adapt at making a glider system.
[Answer]
**Not viable... unless maybe Nikola Tesla came on the scene just a bit earlier**
With the greatest respect for my learned colleague, speed isn't the problem. Astronauts travel much faster than a bullet. The problem is *acceleration.*
Whether a small bullet or a large cargo/human-carrying shell, the nature of a cannon is that a big bang occurs, propelling the shell through a barrel. The [mathematics of ballistics](https://www.dummies.com/education/science/physics/calculate-the-range-of-a-projectile-fired-at-an-angle/) are well-known, but let's take an example from that link:
$$s=v\_xt=\frac{2v\_{i}^2sin\theta cos\theta}{g}$$
So, a 75 km throw requires a muzzle velocity ($v\_i$) of 860 m/s. Let's say the barrel was 100m long. To get to 860 m/s in 100 m requires an acceleration of...
$$a=\frac{v\_{1}^2-v\_{0}^2}{2s} = \frac{(860 m/s)^2}{200 m} = 3,690 \frac{m}{s^2}$$
The consensus is that [9G is the maximum acceleration the human body can withstand](https://www.scientificamerican.com/article/star-wars-science-light-speed/) and your cannon must impose a catastrophic 376G to ship the shell 75 klicks.
*Your people are a thin, strawberry paste on the back of the capsule.*
**Now let's bring someone like Nikola Tesla or one of the pioneers in magnetics into the mix...**
Let's pretend that on your world Nikola Tesla was given decent funding, was able to actually stay focused on one project long enough to do something useful with it, and was born early enough to affect your world. What might you have?
*Rail guns*
Modern rail guns are, in fact, quite a bit worse than cannons when it comes to acceleration — but that's because *they can.* They can also, over a long enough distance, more slowly accelerate a capsule to pretty much any velocity. This is good for you! Because it means you can use the argument of a magnetic rail gun to lob pretty much anything you want as far as you want.
As long as you explain the "barrel" length.
The honor of the largest practical super gun1 goes to the [Schwere Gustav](https://en.wikipedia.org/wiki/Schwerer_Gustav), a WWII monster with a 32.5 m barrel length. And you can now see your problem. Long, straight tubes (or open rails, but tubes are better for a lot of reasons) are a pain in the honking neck. Just to lob your soldiers to lunch, 75 klicks away, you need a muzzle velocity of 860 m/s and you need to get there in less than 9Gs. Let's use 9Gs for convenience just so you know your ***shortest*** "barrel" length.
$$t=\frac{v\_1 - v\_0}{a} = \frac{860}{88.254} = 9.744 seconds$$
OK, so we're traveling at a constant velocity of $88.254 \frac{m}{s^2}$ for 9.744 seconds, which means your barrel length is...
$$s=v\_i t+\frac{1}{2}at^2 = 0+\frac{1}{2}(88.254)(9.744)^2 = 4.189 km$$
**I have one word for you, just one word... *centrifuge***
How do you get a 4 km barrel length? With a coil! Spin the troops around a dozen times and spit them out a short length of straight pipe! We've been spinning astronauts around for decades, so we know it can be done, right?
*Suck it up, cupcake!*
And it would make a cool story....
---
1 *There have been longer barrel super guns, but not by much. The Paris Gun in WWI was said to have a barrel length of 34m. The award was given to the Schwere Gustav for a number of reasons including its calibre. Let's face it. It was a bad boy and whomever was on the receiving end experienced a world of hurt.*
[Answer]
The problem with cannons is that they launch the payload by giving it an extremely high acceleration right at the beginning, because they cannot add any more energy to the projectile later, therefore they have to add all that energy right at the beginning (in the form of a big explosion). And that sudden acceleration will turn any passenger into a paste, there would be no difference between being inside the cannonball or standing in front of the cannon.
You could make it more survivable, if, instead of one big explosion, you used a large number of tiny little explosions, so you spread out the acceleration over a longer time period. Congratulations, you just discovered the rocket engine, and you no longer have a cannon, you have a rocket!
[Answer]
**Air cannon!**
[](https://i.stack.imgur.com/vYLok.jpg)
<https://en.wikipedia.org/wiki/Pumpkin_chucking>
>
> Pumpkin chucking, or for rhyming purposes punkin chunkin or pumpkin
> chunking, is the sport of hurling or 'chucking' a pumpkin solely by
> mechanical means for distance. The devices used include slingshots,
> catapults, centrifugals, trebuchets, and pneumatic cannons....
>
>
> The Guinness world record shot is held by a pneumatic cannon dubbed
> "Big 10 Inch", at 5,545.43 feet (1,690.25 m), on September 9, 2010 in
> Moab, Utah.[2]
>
>
>
The pumpkin here (by the rules, unmodified regular pumpkins) is a stand-in for our fragile human frame. Acceleration that does not fracture the pumpkin will be tolerable by a human. An air cannon provides a relatively gentler acceleration over a long barrel as compared to a military cannon that accelerates using explosives. Your people have giant long barrelled cannons buried in the ground and are accelerated by compressed air.
I am not sure how your people slow down. Maybe flying squirrel suits? The pumpkins slow down very rapidly.
[Answer]
Semi viable, but crazy.
The bullet could be attached to a glider with a human strapped to it. The bullet is fired and through a super powerful bungee cord flies off and relatively gently picks up the glider and flings it.
There is of course a few problems with this.
* The bullet has to have enough mass and speed to overcome the weight of the person being flung
* It's not very reusable, someone has to go get this bullet and bring it back
* You've ruined someones day, because your giant bullet landed like an artillery shell somewhere
* It is not super clear if your riders clothes will stay attached, or if their organs stay in their body.
* And if it were me, projectile vomit and the other thing would be a concern. Have an ambulance ready to get me out of shock and a clean pair of pants.
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[Question]
[
In my fantasy setting exists a creature called Wurm. After a long infancy phase where they feed on a magical, floating ore and an omnivore diet, they pass through a metamorphosis, exchanging their cumbersome rocky body for a serpent like one, with bones and chambers made/filled of the ore.
My question is, how would such a creature move through the air? Would similar limbs and structures used by sea creatures, like flippers, fins and tails, work, even considering the difference of air density (between air and water), or there is another, better way? Would a whale-like body work better in this case? How would turbulence affect its movement?
[Answer]
while air is similar to water, as in it behaves like a fluid, it is **a lot** less dense, this has benefits and costs. a benefit of the low density mean that the drag is far lower than in water, and the drag is dependant on [density](https://www.grc.nasa.gov/www/k-12/airplane/drageq.html), this means that most body shapes would be able to "swim" well, assuming that they can push on the air well.
Which leads to the problem of low density, things move through water by pushing [the water behind them](https://tidetrek.com/how-swim-fins-work/), then from newtons third law pushing the water back pushes you forward. but the lower density means that for the same amount of fluid (either air or water)air gives less of a push forward, which is why astronauts [cant "swim" in zero G](https://space.stackexchange.com/questions/8073/can-you-swim-in-space), they can't push enough air behind them to start moving, at a good speed.
But if your creatures have over sized fins (approximately ~$25-30$ times longer and wider) then it should be able to work, keeping in mind that once it starts moving it won't slow down from drag, as much as it would in water.
*why ~$25-30$ times bigger*: As the density of water is $1000Kg/m^3$ and the density of air is ~$1Kg/m^3$, and for the thing to push approximately the same mass of air back, it need have a $1000$ times bigger area, which means that each side needs to be ~$\sqrt{1000}=31.6$
So the fins need to be approximately $31$ times longer, you would be able to go slightly lower if you want you creatures to accelerate slower, as the drag is minimal they will just keep going.
hopefully that helps
[Answer]
**Wings**
You ask if there is a different, better way. For that we can look at creatures that are already moving through the air. Birds, bats and others use wings. These are excellent at pushing against the air, creating lift and movement. Your creatures have the advantage of not needing lift, so they can focus on speed. The wings can probably be less large.
[Answer]
# Exactly the way fish move in water, or somewhat similar to birds.
They are neutral buoyancy, and could move in the various forms of locomotion that sea creatures use.
Possible mode of motion: From worst to best:
* drifting along like a balloon.
* tentacles or other appendages, grasping and pulling along solid objects.
* flapping fins and tails (fins will need to be proportionally larger, to account for less dense medium, but also less friction with the medium impeding motion. Not *much* bigger than for water)
* variant of fins worth mentioning separately: Undulation of the whole body, like an eel. This is a partially Aerodynamic wing, not just a bigger tail.
* jet propulsion. The creature could ingest air at the front, then expel it to the rear. Much like a squid. Note that due to the low density of air, this is much less effective in air than the equivalent in water. Still, it could work for either very slow, almost effortless motion, and for a single burst of escape-or-attack speed that required replenishing afterwards.
* Actual wings. Note that wings are *not* mere fins, that shove the surrounding matter away. They are aerodynamic surfaces that use the pressure differential possible in a gas for propulsion, not mere shoving of the mass of the medium. Having neutral buoyancy, the wings will not be the normal gravity-aligned wings of a bird. Ideally, the wings would be articulated for active stroke in both flappable directions, regardless of orientation.
[Answer]
This creature can move the same way like [certain spiders](https://www.livescience.com/4142-spiders-fly-hundreds-miles.html) do:
>
> When a spider wants to travel long distances, it simply casts out a strand of silk, captures the breeze and "flies" away. They are known to travel hundreds of miles, even ending up on islands in the middle of the ocean.
>
>
> Now scientists have figured out how this mode of transportation works. They also discovered that spiders have very little influence where they're flown when caught in a stiff wind.
>
>
> Researchers at Rothamsted Research redesigned the model to allow for elasticity and flexibility in the spider's dragline, its most sturdy line of silk used for moving about and snagging prey. When the dragline is caught in a turbulent breeze, it becomes highly contorted, catching air like an open parachute and sending the spider on an unknown journey.
>
>
> The spider has virtually no control of where or how far it travels by this means, said Andy Reynolds, a Rothamsted Research scientist. This is how a "ballooning" spider can end up in the ocean hundreds of miles from shore.
>
>
> In more calm breezes, though, spiders can drift just a few yards to invade new territory or surprise prey.
>
>
>
[Answer]
Is it gauche to recycle answers? Well, it would not be my first time. And I like sidewinders!
Recycled from [Diversity of speculative evolution flight mechanics? Attempting to design a megafaunal, aerial diving predator](https://worldbuilding.stackexchange.com/questions/195457/diversity-of-speculative-evolution-flight-mechanics-attempting-to-design-a-mega/195459#195459)
**Sidewinding up through the air.**
Sidewinding is a form of locomotion used by certain desert snakes. A loop of body is stationary on the sand and used as a base to throw another loop of body forward through the air.
>
> In the resultant movement, the snake's body is always in static (as
> opposed to sliding) contact when touching the ground. The head seems
> to be "thrown" forward, and the body follows, being lifted from the
> prior position and moved forward to lie on the ground ahead of where
> it was originally. Meanwhile, the head is being thrown forward again.
> In this way, the snake slowly progresses at an angle, leaving a series
> of mostly straight, J-shaped tracks. Because the snake's body is in
> static contact with the ground, without slip, imprints of the belly
> scales can be seen in the tracks, and each track is almost exactly as
> long as the snake.
>
>
>
<https://en.wikipedia.org/wiki/Sidewinding>
[](https://i.stack.imgur.com/8xd40.gif)
Your creatures use a similar mode of locomotion, but use control over their serpentine body shape to affect air resistance. The "stationary" loop is flattened into a ribbon to provide maximum air resistance. The snake pushes against the resistant flap loop to throw wedge-shaped aerodynamic body parts upwards through the air. Then those body parts flatten and the previous flattened loop becomes aerodynamic and is thrown forwards.
These snakes climb through the air rather than gliding. Once high enough they glide downwards in the manner of [flying snakes](https://www.nature.com/articles/s41567-020-0935-4). Real flying snakes of course must gain altitude by climbing trees. The proposed animal uses the same undulatory mechanism to "climb" the air.
[Answer]
## Use More Magic
This wurm, in addition to the floating ore, also eats another type of ore, which contains special crystals that can push against nearby air when provided with mana. When they mature, these crystals are formed into special scales that can push the air in a specific direction, allowing it to fly through the air
[Answer]
As @matthew states in a comment, the Wurm sounds like a blimp.
As you state, the Wurm eats magical ore. Within the gut of the Wurm the digestion process produces hydrogen in large quantities which goes into a bladder and keeps the Wurm afloat.
To move through the air, the Wurm expels hydrogen from the bladder.
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[
**This question already has answers here**:
[How would my dwarves tell time underground?](/questions/53090/how-would-my-dwarves-tell-time-underground)
(6 answers)
Closed 3 years ago.
I am in a slight dilemma. I have a civilization of cave-dwelling cats, that has been mentioned in numerous questions before this one. They have human intelligence, and they don't leave the caves. I wanted to build holidays for them, but I had a slight issue. You see, due to them not leaving the caves, they wouldn't have anything such as days or weeks, I doubt they'd even have months.
Perhaps they could figure out from their Surface Hunters (The only cats in their group that go on the surface, and even then it is strictly at night and on a need-be basis), who would notice the moon changing, but the Surface Hunters are a much newer rank into their civilization, maybe only a few generations, which would require the holidays to be founded extremely recently.
The only time measurement they have is a year, due to the seasonal flooding of their caves. They also cannot have holidays based on seasonal changes, since once again, they only very recently even dared coming to the surface, and very few do so. And, even holidays not based on seasonal changes, such as when they believe they were founded, or the death/birth date of important figures, they don't have any way to track when this is. So, in other words, what could occur in a cave almost always around the same general time?
Ignore climate and habitat, since while it is based in Pennsylvania, United States, I can easily change this to any other place that gets rain during the spring. But, for answers, please state what can occur where, and what general date it occurs. Note that changes in animals that live in caves are also viable.
Also, I am asking for cats, without any technology above primitive (They don't even have tools for the most part). They have seasonal flooding, yes, but that is to track a year, not months or days. They are also nomadic, they cannot always rely on water levels in the caves since not all their caves have water.
Also, to quote KeizerHarm:
>
> Not a duplicate; that question is about telling time, this one is about tracking dates. Technically the time-telling answers work if you do them 365 times a year, but for tracking dates there might be more efficient methods.
>
>
>
[Answer]
Dates (and, for that matter, measuring time) comes about very, very, very early in a civilization. A fairly complete date and time system would have been developed by your cats long (eons) before your Surface Hunters came to be. So what do we have to work with? The simplest thing I can think of is...
**The [Circadian Rhythm](https://worldbuilding.stackexchange.com/q/89382/40609)**
Your cats need to sleep and I assume (being based in Philadelphia) that they originally evolved on the surface. This means your cats need to sleep. Cats today sleep on average [12–16 hours a day](https://en.wikipedia.org/wiki/Cat). Let's use the average for convenience: 13 hours. That means they're up and about 11 hours a day on average.
*And lo, as the ancients wept through the darkness in search of light they called upon Felidae for help and wisdom. And behold Felidae did bless the ancients with wisdom, for she called the time of rest "death" and the time of searching "light". And Felidae did watch over her children, over life and over death, and behold she called this the first Day, and it was good.*
So your cats are working with what we humans might call a 26-hour day, but for the moment, all we know is that they have a way of tracking days: the time spent awake plus the time spent sleeping is a day. Is it accurate? Heck no! But while sunrise-to-sunrise might be more accurate, it's not actually *precise* because it changes depending on your latitude, the time of the year, and your moment in *history* because the length of day has changed compared to days past. So, for our burgeoning intelligent cats, we now have a Day.
**The Value of Religion and Philosophy**
Now, while historically we might be doing this in order, religiously we're putting the cart before the horse. The overwhelming influence of religion and philosophy on calendars and time cannot be overstated.
*In the beginning was the void. The void was dark and without form. Felidae did look upon the darkness and new that without life the darkness had no purpose. And Felidae wept for without purpose all is truly nothing. And her tears fell upon the void and washed through the void and separated the void from the void and filling the void and Felidae found hope.*
*And Felidae did breathe upon the void that was filled with her tears and the water did recede and there was space for purpose and Felidae once again found hope.*
*And Felidae passed her paw over the space and the space did embrace Felidae and the touch of Felidae did cause the blanket of life to rest upon the space: the mushroom and the lichen, the moss and the short grass. And Felidae smiled that purpose was growing and again found hope.*
*And Felidae did wish for purpose to be fulfilled and so created life that would fill that purpose: the insects withing the space and the insects within the void, the mouse and the bat, the burrower and the crawler and that which slithered upon the grass and Felidae once again found hope.*
*But purpose was not yet fulfilled and Felidae did weep once more. Her tears fell upon her cheeks and upon her paws and upon her tail as she curled upon and around the void. And as Felidae did embrace the void and the void, Felidae, she did close her eyes and she did bless the void and her Children, the Ancients, were born. And Felidae did breath a great sigh and her Children did know life and did know purpose and began their journey through the space and through the void. And Felidae did find hope again.*
—Insert that first verse here—
*And Felidae did bless the day her Children were born and did command her Children to rest upon the fifth Day that they may remember the blessings of Felidae.*
**Now let's look at the life around your Cats**
OK! Now we have days and weeks. For months let's look at the [life cycle of the Kentucky Cave Beetle](https://scholarcommons.usf.edu/cgi/viewcontent.cgi?article=1539&context=ijs). As it happens, their life span is approximately one terrestrial month. Rounding a few numbers and playing with the averages, what we have is a month of 28 days, which is as inconveniently divided into 5 as our month is into 7, but it does give you a "season" of 5 months.
* Day = one wake + one sleep cycle.
* Week = 5 days
* Month = 28 days
* Season = 5 months
**As for hours, let's ignore the dew claw**
Cats have 4 claws on each paw if we ignore the dew claw. So, 8 hours of life and 8 hours of death. 16 hour days.
And the coolest thing about this is that this dating system conflicts *enormously* with what your Surface Hunters find outside. They'd see the moon. They'd see sunrise and sunset. And those periods of time would be completely at odds with their own dating system — with the exception of months! ***Cool!***
[Answer]
Why don't they have holidays... based on the flooding of their caves?
Your question seems a bit backwards to me - you seem to think we have holidays because we have calendars, so you are imagining that your cats would invent calendars (thanks to the surface hunters discovering the day/night cycle) and then would invent holidays, for some reason.
I would argue it's the other way around! We have holidays to celebrate regularly-occurring events, and we invented calendars to track the events - it might even be historically the case that the calendars were invented *to track the holidays*.
Your society already has a regularly-occurring event: the flooding of the caves. It seems like a very important event, that would be relevant to how the cats feed themselves and live! Is it not? And either way it would be a good marker for a cat's life, it seems pretty natural to me they'd count their lifespan in how many floodings they'd seen and such. Now you might think they cannot predict the flooding, and that may be the case but it doesn't prevent a holiday. For example, if the flooding is absolutely unpredictable then they can have the holiday when the flooding starts. But more likely the flooding is associated with a physical cycle that would have precursors - an increase in humidity, the increase or decrease of certain bugs or micro-organisms, a variation in various smells... What does the flooding indicate? Does it destroy the cat's crops and chase away the game, or does it bring food the cats live on for the rest of the year? This kind of question could determine whether cats mark a holiday with the arrival of the flooding, or the some precursors that announce the upcoming arrival of the flooding, or the height of the flooding, or the end of the flooding... Or all of these.
In terms of day/night and other cycles discovered by your surface hunters I find it doubtful those would result in holidays after only a few generations. Either way, the holidays would be associated with something actually important to the society. Maybe the surface hunters would have noticed migratory patterns of their prey and learn the cycles associated with that, and maybe that could lead to specific holidays the surface hunters celebrate. Maybe even holidays the whole society celebrates if those patterns impact them (like there's a Mammoth Season now, everybody loves the arrival of Mammoth Season. Maybe the surface hunters also track Snake season and Vole season and Birdie season and have little celebrations to mark the transition, it matters to them because they need to switch tools and such, but Mammoth season is the big party everybody participates in).
[Answer]
Your day counter is the easiest to solve:
* When the hunters return it signals the next day.
* Or it that isn't often enough, there's a notable temperature shift. When it stops getting colder and starts getting warmer again, that's the next day.
There's also water in the caves, and the cats notice that the water rises and falls every 12 hours 25 minutes. They notice every 29.5 days the water level peaks synchronising with the temperature peaks. They call this the month.
They line it up to the nearest day start, so some months are 30 days, some are 29 days.
Month 13 has 13 days in it, then they get a flood. They call this the start of the year.
They count months of 29 or 30 days and use this for approximate measurements of the passage of the year. Within these months, they count days.
They have a holiday period of 13 days at the end of the year coinciding with the unusual month length. To prepare for the upcoming flood they cut down trees and install them in their living rooms to act as flood breaks, and because they like pretty things, they're decorated with pretty cat toys and flashing coloured lights. Since they may die in the flood and should finish their lives on a happy note, they visit family and exchange gifts. The "13 days of catmas" are the happiest time of the year.
[Answer]
maybe use the bats to determine time or day? bat goes flying out during night or afternoon and back during dawn.
so the time they spend sleeping is the morning/dawn to afternoon/night its like the equivalent of the sun, although may not as precise.
as i has mention in previous answer, OP mention that the cat cant goes out of the cave, but other animals can, since the cave is not even blocked.
also for recording the date, i suggest either just directly scratch some surface or use paint to mark it like blood from their prey, or using chalk from the mine if they are smart enough to use such thing.
[Answer]
There's only very minimal evidence for holidays in pre-agricultural people. What holidays they do have tend to be astronomical in nature... the two solstices and the two equinoxes, generally. When agriculture is developed, you start to see holidays develop for harvest times and planting times, and so forth.
Neither of these are possible. If they were to have religion, it might well develop without the concept of "holy days" at all. Given your constraints, I would avoid adding such a detail to the story. There is no reason to believe that holidays are even a human universal, let alone one for non-human intelligences.
[Answer]
You can place the cave system near the shoreline of body of water connected to the ocean (If googlemaps doesn't lie, there's a couple of places for it in the state), and make some tunnel systems lead to it and go underwater. Then they will inevitably notice the tides as the water in the tunnels changes its level, in addition to the floods.
In addition they could've relied on their circadian rhytmes to keep the sense of time. IIRC when humans tested that, also living in the caves, they have set on a consistent rhytme that was longer than a day, something like 28 hours or so.
] |
[Question]
[
potion brewing is a subsect of witchcraft with roots as far back as ancient times. These potions are made to serve various purposes in different fields. Curing illness, making an individual fall in love, increasing one's strength, and other effects are marketed to the public or to other witches. They are brewed in large pots called cauldrons, in order to produce a large batch all at once. Various items are included, boiled, and stirred in the pot to make the concoction (eye of newt, a dead infant, granite skin of a 500 year old dead turtle that was born on a solar eclipse, etc). The potency of the brew will depend on the skill of the witch and the quality of the items. While this is a necessary profession in witch society, brewers are often stigmatized by their fellows.
Potion brewing has negative effects on the creator's skin. One condition is that it turns their skin green. The condition takes place slowly over the course of years. The more time a witch spends making potions, the more complete their skin change becomes. Eventually, They become green from head to foot. The skin also changes its texture, becoming more sunken and hanging off the individual's bones. As anyone would tell you, its not easy being green. These unfortunate souls are somewhat held at a distance and seen as greedy, as they are "green with envy". This stigmatization of society often leads many witches with the condition to go insane, taking to fits of cackling laughter.
Changes in melanin production can be due to a variety of conditions and some medications. Skin darkening can be due to changing hormone levels or medications, but it can also occur from exposure to ionizing radiation (such as the sun) or heavy metals. Radiation therapy can also cause an increase in skin pigmentation. However, all of these can have potentially kill the victim. Also, skin color can only go from darker to lighter, with no other colors being possible. It's not like we see orange or blue people running around these days. How can brewing potions end up having these affects on the maker's skin without having fatal results.
[Answer]
How can we explain why witches brewing potions gain green skin?
Brewing a bunch of big batch potions exposes you to some nasty vapors. The cauldrons must be stirred constantly and ingredients added precisely, so there is no way around this.
Perhaps one of the main ingredients in the base potions contains a lot of sulfur and the reactions frequently form <https://en.wikipedia.org/wiki/Sulfonamide_(medicine)> compounds.
Constant exposure to those chemicals leads to very extreme forms of <https://en.wikipedia.org/wiki/Sulfhemoglobinemia> which causes full body Cyanosis.
Alternatively, prolonged exposure to those vile vapors reduces their immune system and the are forced to frequently drink healing potions to stay healthy. If those potions happen to include <https://en.wikipedia.org/wiki/Phenazopyridine> that could also lead to Sulfhemoglobinemia and cyanosis.
Or rather than having to drink healing potions, a side effect of the exposure is frequent UTIs stemming from kidney issues. If that's the case maybe the witches need to treat that condition with the Phenazopyridine directly, which is what causes the Sulfhemoglobinemia.
If you don't find fume exposure to be a sufficient justification, you can always decide that potions fundamentally require a few drops of fresh human blood. Those poor potion producers are always pricking their fingers and getting all sorts of exposure while handling their ingredients.
Additionally, like a good chef, they sample the potions to determine when they are ready and are therefore exposed to way higher doses than anyone else, and develop side effects accordingly.
Pick your poison.
[Answer]
## Subcutaneous pigment absorption: AKA tattoos
People turn their skin green all the time in real life through the application of tattooing. These pigments are non-toxic but can remain under the skin for a lifetime. So, when we consider potion making, the fumes of the potions may work like a chemical peel meets dye job, opening up pores indiscriminately allowing pigments to seep into the skin. But if you've ever seen a person who chem peels too often, you will begin to notice the long term damage to the skin making it droopy as described in your witches.
The best part about going this route is that witches may not all turn quite the same color, but rather, their skin will pick up the color of the potions they most often work with. Potions used most often for benevolent things like healing or truth serums might turn your skin a "good" color like gold, malevolent potions like poisons and curses will turn you an "evil" color like red, and self serving potions like love potions and lead-to-gold potions would turn you green. Thus the Green witches being greedy is more than just a stereotype, but a very good indicator about what those witches are making potions for.
[](https://i.stack.imgur.com/yfDRq.jpg)
[Answer]
Just as exposure to the sun will dark skin, exposure to magic will react with it. If you brew only one kind of potion, the reaction will be predicted on that and be very ugly. Strength, for instance, will make your skin like steel, ruining your sense of touch and making motion difficult. But, for some reason, if you brew many different kinds, the result is the color green. No one knows why, but it's better than the single kind.
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[Question]
[
When I asked about [food preservation](https://worldbuilding.stackexchange.com/questions/184208/long-term-food-preservation-techniques-200-300-years-preferably-in-a-form-of-m) for 2-3 centuries, some commenters insisted that if I have technologies to preserve living humans for that long I should have no problems preserving food (with almost intact nutritional values). That made me wonder if this idea is actually true.
Living organisms have a lot of mechanisms that keep them functioning for extended periods of time, prevent decay, deal with infections, and even repair mechanical damage. Many animals and plants can live for decades while exposed to elements, pests, bacteria, viri, and physical trauma. Their chemistry stays more or less stable over that time. But once they are dead, it takes just a bit of time for them to decay (the exact time depends on many factors, e.g. environmental conditions, chemical preservatives concentration in tissues, tissue types).
**Question:**
**Dead tissue or a living organism (as classes, not specific types of tissue or organisms), which is easier to preserve for 2 centuries in a condition *as close to original as possible*? (with focus on biochemistry rather than the preservation of a specific tissue)**
'Preservation' in my question is used in this sense:
>
> [the activity or process of keeping something valued alive, intact, or free from damage or decay](https://www.merriam-webster.com/dictionary/preservation)
>
>
>
with emphasis on '*free from damage or decay*'.
*This question is not limited to currently existing technologies. Developing technologies or theorised technologies are fine, as long as they have solid scientific backing. For example, genetic engineering is fine (within reason), cryosleep is not (unless you provide citations for successful reanimation after at least a year of storage).*
***Edit***: When I am talking about preservation in a condition as close to original as possible I mean exactly it. If you are preserving a piece of meat it should stay a piece of meat after 2 centuries (or can be reconstructed as such if some tricky procedure is used; ideally it should have the same texture, taste, and nutritional value since this is the case for living organisms). Most of the chemistry and physical properties should stay the same at the time of examination (before preservation and once it is finished). The sample does not have to consist of exactly the same physical atoms, molecules, or cells (it is not possible for a living organism) but it should be recognised as the same tissue/organism in close to original condition by an average human and have the same functionality.
Please assume that whatever conditions are needed for preservation can be maintained for the duration of the preservation experiment without interruption.
***Edit 2:*** **I am much more interested in a comparison between arresting decay in dead tissues and sustaining (or improving) natural bioprocesses in live organisms.**
I also want to note that freezing does not leave organic matter intact. There is damage associated with freezing/thawing that has to be quantified and figured in. I wrote about it and other aspects of food preservation in my [notes](https://worldbuilding.stackexchange.com/a/184501/78906) for another question.
***Edit 3:*** I am looking for **hard science** with citations, numbers, and figures. I appreciate general thoughts on the subject, but it is really hard to compare the advantages and disadvantages of different solutions and approaches if I have nothing but words to rely on.
I do use 'food test' (if something was edible before it should keep the same nutritional values after 2-3 centuries) because it is an easy way to test many answers, but this is not a question about food preservation. ***The type of organic material does not matter at all, what is really important is its integrity and physical properties, including biochemistry.***
This is not a museum project. All organics should be usable in a regular manner after 2-3 centuries.
[Answer]
***Dead:***
The difference between preserving living tissue and dead is that you have to keep living tissue viable, while dead tissue you don't. Everything you can do to living tissue, you can do to dead. So by a huge margin, dead tissue is easier. Every preservation technique you can use on organic material, you can use on DEAD tissue, from embalming to mummification. Mummies have lasted for thousands of years, and there are remains of long-extinct species in jars of formaldehyde that are hundreds of years old and still recognizable. If you aren't fussy about small chemical changes but only care about the form, I think it would be easy to preserve organic material indefinitely (if this is secretly a food question though, it might not be edible). The evidence may be challenged, but there is some evidence that preserved [soft tissue](https://www.google.com/search?q=oldest+preserved+soft+tissue&oq=oldest+preserved+tissue&aqs=chrome.1.69i57j0.13161j1j4&sourceid=chrome&ie=UTF-8) might last millions of years.
There is ONE circumstance where you are better off with living tissue, and that is that living tissue regenerates. A plant can keep growing as a sort of [immortality](https://en.wikipedia.org/wiki/List_of_longest-living_organisms), and if the plant is maintained and capable of continuous growth, it keeps living. If you can make a biologically immortal person, then that person can live forever by simply living. On a planet or on a spaceship, they keep living. BUT, even a person capable of living forever may grow suicidal, and the water system to an immortal plant or fungus can get switched off and it can die. You need to maintain the entire apparatus of life constantly for something to stay alive. Keeping things alive is extremely energy and resource intensive, so if the goal is to have a person alive after 200 years on a spaceship, it is semi-impractical and the whole reason people want to invent cryo-sleep.
Further, the immortal organism isn't the identical tissue, but regrown and recycled tissue. They are functionally a [clonal colony](https://en.wikipedia.org/wiki/Clonal_colony) Just because an "immortal" fungus is centuries old, that doesn't mean it's the exact same fungus. Mutations can still crop up in an organism (ie cancer), and the cells aren't the same cells. We haven't come up with a great way to immortalize people yet, but things like brain tissue would need to die and get switched up. Physical stuff eventually wears out.
This is not to say a living organism CAN't be preserved for a long time under appropriate conditions, but it would need to be specialized for this function. a [seed](https://en.wikipedia.org/wiki/Oldest_viable_seed#:%7E:text=The%20oldest%20carbon%2D14%2Ddated,300%20years%20for%20the%20seeds.), for example, can remain viable for thousands of years.
[Answer]
**Dead**
You can vacuum seal and then irradiate dead tissue to kill everything living inside of it and then store it at a moderately cold temperature to result in only minimal tissue damage. You can then, if you so choose, pop that dead tissue out of the vacuum seal 200 years later and grill it into a steak, assuming that you had steak to start out with.
Most living things have a lifespan of under 200 years and once you preserve living things, they generally wind up dead - [cryonics does not work](https://www.technologyreview.com/2015/09/15/109906/the-false-science-of-cryonics/) and there's no indication outside wishful thinking that it ever will work. Preserving living things will wind up with dead things, and dead things are similar to living things, but not as similar as dead things are to dead things.
[Answer]
This is link to Food preservation types and technique : <https://en.wikipedia.org/wiki/Food_preservation>
The answer it's very difficult, because there are many factor to consider, bacteria, yeast, external agent, wheater condition, moisture, pathogens for a dead flesh, the duration of a dead tissue depends on type of tissue.
A good example of food preservation is military rations they can last until 50 years
I think that there's no correlation between living humans and dead tissue, because a living being have "energy" to maintain and a process of regeneration (human about 70-80 year, a turtle 150 year, greenland shark 400 year this is an average value).
Discussing with a futuristic tech you can use Amber to store the tissue after a previously preparation.
You can continuously clone the tissue to preserve, actual tech can reproduce skin from staminal cells.
[Answer]
Given that the OP has added or clarified a condition to the question:
>
> You are too focused on food and livestock. While I indeed need to feed
> my crew, I need organic matter for other reasons, too. Moreover, I
> need them to be as close to original as possible. For example, I need
> most of the DNA and proteins intact and easily accessible for
> manipulation in many ways. You correctly identify problems associated
> with keeping animals alive while in a coma, but you ignore all
> chemical changes to dead tissue. I also realise that this whole topic
> of keeping organic matter intact for long periods of time is highly
> underappreciated and people tend to oversimplify things.
>
>
>
**Alive is the Only Way to Go!**
Since you need to be able to access and manipulate DNA and other biological materials, in addition to having access to crew rations, the best solution will now be twofold. Storage of frozen food for long periods of time has already been discussed (focused on meat). But you will also need a way of preserving living tissue. The best way to accomplish the feat is to keep partially prepared food in the deep freeze as already discussed but also to step up keeping live plants and animals in some kind of habitat.
You could consider, as part of ship design, a large free range biohabitat. Stocked with small livestock such as chickens and rabbits and an appropriate predator species, its environment monitored and adjusted by ship's AI, your crew might just awaken to fresh fried chicken!
This is unlikely to work long term, as disease will be problematic and population spikes and catastrophic dips may lead to extinction of the biohabitat. While balance issues may pose tricky problems, at least the time span is short enough that you might be able to pull it off.
At journey's end, the biohabitat will contain sufficient biological matter, in the form of living animals and plants as well as decomposing matter and compost that can be used for other purposes, such as manipulation in order to grow artificial meat or to make pharmeceuticals, vitamins, hormones, etc.
The advantages to the split system are numerous: you will have fresh food available to the crew upon awakening; you will have a ready source of biological matter onboard; you will also have something approaching a natural habitat for the crew to enjoy while performing onship duties at the end of the journey. Even though you propose a very high level of technology, you don't have synthesisers capable of extruding complex biological material. A biohabitat (or two) will solve the issue of "preservation", because nothing beats a living plant or animal for providing biomatter.
Although we discussed keeping animals in a coma, inducing a state of torpor will pose similar problems. The main problem is the simple fact that animals are mortal creatures. They have a basic life expectancy that very few will survive, and will be almost impossible to overcome while incapacitated and supported by machines. Barring some kind of "stasis field" technology, there is just no way to "store" a plant or animal and ensure that it will continue to exist, in a living state, beyond the capacity of its kind. The life span of many crop plants -- tomatoes, lettuce, etc is literally a year. Though others may last much longer -- grapes, apples, other fruit trees. The life span of food animals rarely exceeds 20 or 30 years. This is the insurmountable problem of any kind of "storage".
The advantage of designing biohabitats into your ship is that the plants and animals will exist in something approaching their natural state. The biohabitat will have night and day cycles, can have seasonal cycles, can have artifical weather conditions and will be self sustaining, once fabricated.
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Original Answer
**Definitely Dead**
The good folks over on Cooking.SE have asked [this very question](https://cooking.stackexchange.com/questions/13953/how-long-does-uncooked-meat-last-when-kept-in-the-freezer). The long and short of it: properly prepared meat (raw, vacuum sealed, maybe irradiated, kept frozen (0 deg F)) can last indefinitely.
This *Woman's Day* [article](https://www.womansday.com/food-recipes/food-drinks/a51056/how-long-can-meat-stay-safely-frozen/) about freezing meats quotes an [FDA fact sheet](https://www.womansday.com/food-recipes/food-drinks/a51056/how-long-can-meat-stay-safely-frozen/) about freezing foods. The pertinent language reads: *"Food stored constantly at 0 °F will always be safe. Only the quality suffers with lengthy freezer storage."*
Quality suffers, according to a comment within the C.SE query, thus: *Generally, meats dry out (freezer burn) when frozen before they become unsafe to eat. You can reduce the drying effect by double-wrapping meats, and a vacuum sealer is especially helpful. Freezer burnt meats become tough and grainy, but can normally still be used in stews, stocks, and other preparations that hide the damage.* (Bruce Alderson)
I think 200 years of cold storage should yield an edible, if not terribly palatable, meal.
**Counterexample**
But what about living tissue? Living tissues can indeed be kept, though not really "preserved" for a long time. This process is essentially an [induced coma](https://en.wikipedia.org/wiki/Induced_coma). Essentially, the person in a coma exists in a state of deep unconsciousness. Presumably, an animal placed into an induced coma would similarly exist in a state of unconsciousness.
The record for longest coma is something like 37 1/2 years. Not quite long enough for your purposes! The main problem with this kind of storage of living tissue, whether human or animal, is that the body continues to grow & develop. At least to a point. People in comas are not in any kind of "stasis" -- they are still susceptible to environmental diseases and may still develop cancers. Finally, no living thing this side of the veil is immortal: a person in a coma will eventually die. Most likely from complications of the coma itself; but at the last, even a comatose person will die of old age.
There are plenty of bad things that can happen to a comatose person, ranging from infection to decreased bowel and respiratory action, lowered blood pressure, bed sores and [atrophy from disused muscles](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4315632/). A food animal stored in such a way would almost certainly suffer the same physical degradations. This is not a viable alternative for the simple reason that it's the muscle tissue of the animal your crew will be hungering for when they wake up at journey's end!
**Resource Comparison**
*Dead tissue:* one time Earthside preparation including initial butchery, multipacking of raw flesh with irradiation & vacuum sealing, rapid freezing. Shipside requirements: freezer units that are accessible to crew upon waking. Ship's AI should be programmed to monitor temperature and perhaps vacuum conditions of the freezer units; should also be able to quarantine a/o jettison compromised or nonfunctional units. Results: guaranteed.
*Live tissue:* livestock animals will need to be initially processed (bathed, decontaminated, quarantined) before entering Earthside facilities. Once there the animals will be anesthetised, cannulated, unconsciousness induced, intubated, and loaded into harness cradles. The harness cradle serves as a suspension storage apparatus with attached medical grade machinery (respirator, multicapacity IV pump). Shipside, the suspension cradle will be attached to the on board MPS (meat preservation systems), which will include all necessary lines to central storage facilities, including room air, oxygen, potable water, IV nutrition, IV fluids, and an assortment of pharmeceuticals. The MPS will also feature a physical (passive) exerciser (an attempt to preserve some muscle mass); a total waste management system (handles poop and pee, sending them to the central recycling unit. The MPS units, of course, must be kept in an inhabitable part of the ship, with appropriate environment constantly monitored and adjusted. Ship's AI will be programmed to monitor the basic health status of each livestock animal (ekg, blood gases, respirations) and must cull & jettison deceased animals. Cows live about 20 years. Results: this was a bad idea! Reason being, once your crew wake up, they'll discover that the entire herd of induced coma cattle are long since dead and jettisoned.
**Conclusion**
Dead tissue presents far fewer challenges as far as storage & maintenance go. Live tissue requires what amounts to 24 hour health management of each livestock animal. In addition, the effort will be wasted since even the optimal lifespan of the livestock animals falls far short of the journey's expected time.
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[Question]
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Mana is the source of magic in the world, and is connected to a person's life force. A witch contains the mana within their soul, and determines the physical constitution of the individual. Individuals are born with different amounts, which can grow as they age and will determine their potential of magical power. Those with large reserves are healthier and have a naturally longer lifespan than those with less reserves.
Powerful witches usually give birth to children. However, there is a downside to being at the top of the food chain. Maternity death rates are much higher among witches with larger reserves of mana. Stronger witches are at significant risk, as they are much more likely to have difficult pregnancies and die in childbirth. This has led to a strange situation in which the most successful, healthy, and powerful individuals have a higher likelihood of dying than those lower and less well-off in society.
How can childbirth death rates by higher among healthier people?
[Answer]
**Parasitic Babies and Undead Abomination Babies**
Under normal circumstances the baby feeds off the mother's body (life force) to grow over a period of nine months. As part of this process the baby develops a soul. For a non-magical mother the process is gradual and rarely dengerous.
For a magical mother however the baby will also have a highly magical soul. Creating one of these is much more taxing on the mother's life force. If the baby is born succesfully chances are it will also be a talented spellcaster.
Best outcome: Mother and baby survive the pregnancy and the baby is born as a talented spellcaster.
Bad Outcome: The baby sucks the mother's life force faster than she can regenerate it. This kills mother and baby. One solution to this is a *mana infusion* from other witches. But the more powerful the mother is, the more powerful or numerous the infusions need to be.
**Worst Outcome:** The baby sucks all the mother's life force really quickly. This kills the mother but leaves the foetus with no soul, but enough life energy to survive for a while. It then roams the earth as a mana-empowered undead abomination that must feed on the mana and souls of others to survive. These guys are especially dangerous to their prey. They cannot be damaged by spells because they **feed on spell energy**. Moreover more powerful mothers produce more powerful abominations.
[Answer]
**Hormone fluctuations**
Being pregnant kind of screws with the body's hormones, hence the reputation pregnant women have for having weird food cravings and also for mood swings. Not to mention the toll that it takes overall - for instance, morning sickness. Now, for a normal human woman this isn't an insurmountable problem. But it could very well be a problem if they have an incredible amount of mana at their disposal.
It's very simple - the hormone fluctuations of pregnancy causes the witch to have less control over her mana than she usually does, and the more mana there is, the more control is needed. Thus, it's entirely possible for a witch to lose control of her mana and die that way.
[Answer]
**Magic gets in the way of emergency interventions.**
According to a [study of maternal mortality](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2505173/), "Basic emergency obstetric interventions, such as antibiotics, oxytocics, anticonvulsants, manual removal of placenta, and instrumented vaginal delivery, are vital to improve the chance of survival." If you remove the ability to use any of those interventions, you increase maternal mortality. You said that magic keeps people healthy, so I imagine there's some method by which it protects a person. Now imagine how the magical health defenses would respond to someone trying to push a set of forceps into a witch's body. Or someone injecting a substance into her body. Or someone trying to cut her abdomen open for a c-section. The mana reserves could push back against these "attacks" and result in a midwife/obstetrician being unable to assist a laboring witch in distress.
[Answer]
**Passenger grabs the wheel.**
Accumulated mana requires control. It is a balancing act and keeping the mana confined within a body is no mean feat. Especially for witches who accumulate many times more than what a human body is biologically equipped to handle. It is the equivalent of driving at 200 mph. You need to pay close attention and be quick to react.
When a pregnancy starts, the fetus has access to some of that mana, and can take some or contribute its own, or both. And unpredictably. Now she is driving down the road at 200mph with her passenger messing with the wheel, and gas, and brakes. It is a serious test of the abilities of the witch to keep her mana race car on the road under these circumstances. Those who have accumulated mana before pregnancy such that they are at their limit to control it can easily lose control when the fetus starts messing around. This is also why among witches, dying in childbirth is seen as a sign of weakness - it means a lack of control, or poor judgement, or both.
Obstetric complications caused by mana control issues are not your typical obstetric complications. Uncontrolled life energy fluctuations pluck at reality, and some very unusual and dangerous things can happen.
[Answer]
Their health comes from their more vigorous immune systems, but it produces the danger of more and greater autoimmune diseases. Since the child has only half maternal DNA, both the child and the mother's immune systems might identify the other as an infection.
Severe immune system reactions can produce cytokine storms. These are thought to be why the Spanish influenza killed healthy young adults -- normally those who are the least likely to die of the flu.
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[Question]
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Vampirism. There are benefits and drawbacks, but one of the benefits is not aging. Great if you get turned in your early twenties, but... what happens if you are turned earlier?
Being turned as an infant would probably not be fun, but how early can we push things? (For simplicity, let's call our hypothetical child-vampire "George".)
Rules:
* George should be at least somewhat self sufficient and able to perform physical feats "comparable" to an adult, adjusted for size. In particular:
+ Can stand upright, walk, run, climb up or down stairs, and generally move about.
+ Can eat food, bath, and put on clothing without assistance.
+ Can walk/run with comparable endurance (similar length of time, not necessarily similar *distance*). Can perform physical exertion (proportionally scaled; for example, body-only exercises) with comparable endurance.
+ Can lift at least¬π a proportional amount. (For example, at 33", or roughly half the height of an "average" adult in the US, George should be able to lift about an eighth or more¬π what the same "average" adult could lift.)
* Physiological development isn't "necessarily" halted; George just has to *look*, from the outside, like he is the same age as when he was turned. (So, no bone growth or shape changes, but composition is allowed to change.)
* George should be able to develop mentally to an adult or near-adult state.
* No ongoing magic. (You can hand-wave how George *gets* to wherever he's physiologically going, but he can't rely on supernatural abilities once he gets there.)
It should be at least *somewhat* plausible to go fairly early; after all, the world's shortest *adult* was a mere 21¬Ω". How small could you go, especially dealing with child proportions, and still accomplish the above objectives?
(¬π I think that, due to the way the square-cube law works, we might actually expect George's proportional abilities to *exceed* those of an adult... but I'm not sure.)
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For the purposes of this question, ignore the issues that George will have strictly because of a) height or b) apparent "legal" age. People with [dwarfism](https://en.wikipedia.org/wiki/Dwarfism) can be self-sufficient by just about any definition. What I'm really asking is what (insurmountable, given the above wiggle-room) problems, if any, George will have from having the body of a *child* rather than an adult with dwarfism (AwD). In particular, at what point (in development, or rather lack thereof) do the above limitations necessitate a debilitating difference in physical or mental ability when compared to a same-height AwD who definitely *does* meet the stated objectives?
I'm confident there is an answer, since I'm pretty sure that no amount of hand-waving of "outwardly invisible development" is going to permit a "functional" person by these standards that visually appears to be a newborn infant. (And at the far end, well, if he's turned as an adult, obviously he can function as an adult. This puts both a lower and upper limit on an answer.)
[Answer]
I would expect the answer to be when the child is physically capable of walking. Physically capable is not the same as the age that the skill is learned, though, so probably younger than the average walking age of 8-12mo. The youngest children have been known to walk is around 6mo, so I'd assume a 4-5mo vampire-baby could manage it.
I want to worry about cartilage-bone ratios, but walking is probably a safe threshold for that not being so much of an issue.
However, psychological development is kinda complicated. Between hormones and the limbic system, etc, I'd expect that an adult mind transported into a toddler body would find emotional incontinence and impulsiveness to be increased. How does synaptic pruning work without aging? Etc. Yes, mental development is explicitly handwaved in the question, but it is a complex enough subject that I'd still wonder about the details.
Generally speaking, though, demonstrated ability tends to lag behind physical development, between learning and environment, so it seems safe to say that being physically capable of walking and manipulating objects is the bare minimum, and those can come quite early.
Having said all that, proportions, lung capacity, and things like that will dramatically affect running, stamina, and the like. Size puts upper bounds on some of these. So while I'd accept the minimum being a few months, erring on the side of a little later (a year or two) might be playing it safer.
[Answer]
Going out on a limb, I would say 6 is the youngest George can be while retaining self-sufficiency. At that age, he's large enough to operate in a society mostly by himself(though he will probably need to carry around a foldable stepping stool). Six-year-olds can run for a surprising amount of time, they can jump, and virtually all of them love to show off how strong they are. They can do a few pull-ups and around as many push-ups as an adult.
Plus, if he stays at that age forever(i.e a very long time) his muscles will continue to become denser and more capable of endurance, even if they don't grow more than looking like a jacked six-year-old.
Heck, George may actually be faster than adults after ten years of being a six-year-old because his lighter mass would take significantly less energy to move around. He could even become the pull-up world record holder!
[Answer]
**Very young children function very well, when cared for.**
Your toddler vampire would not be fighting werewolves or working kung fu, though it might help if it were cute. It would look and act like a toddler. It would live in densely populated and poor areas of the world, or areas torn by war and genocide. People would find it, and assume it to have been abandoned or lost. They would bring it to a place for such children where it could be cared for until its family showed up or until it could find a new home.
Once taken into a dwelling, the 1 year old vampire is set. It is cared for as a child, and it can feed on other persons living there. An orphanage or refugee camp would be perfect as it can feed on other abandoned children. If some of these die it is no great surprise; many are sick already. Maybe the vampire prefers them.
The toddler vampire must move on from time to time. It might not have to move far.
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Of note, toddler skulls can hold adult sized brains. If it helps the story you could have the brain mature while the vampire keeps the appearance of a toddler. It would need to be careful to maintain toddler behavior when watched.
[Answer]
Well... depending on what physiological changes your vampirism brings with it I'd say very early. In modern use most forms bring heightened strength and speed. If body strength is heightened then one could argue that even a newborn would easily be able to fulfill all your definitions. Especially when you'd consider that a proportionate growth in muscle potential would benefit a small body much more than a larger one and might allow it to jump higher than a grown body would.
I don't see a reason why brain development would be affected as generally neural elasticity doesn't seem to be changed through vampirism and alls limitations regarding walking are due to missing grasp of how to move, muscle strength and dexterity (which results from the former two).
The huge head definitely would look weird and creepy but wouldn't necessarily mean, that it wouldn't be able to move well. I would argue a well trained body would be able to work with the offset of center of gravity. It probably may not be able to run (very well), but it might be easier for a body like that to make huge jumps.
For practical reasons I'd suggest to wait for the hole in the head to close though.
[Answer]
Several vampire story lines have come up with various explanations of how this works, but turning children is almost always considered illegal or at least taboo in vampire culture.
*Interview With the Vampire* had an interesting take in that Claudia, a child vampire, would age mentally despite her physical appearance being totally unchanged. This was a major driving point in the story as it drastically affected her relationship with her fathers (the vampires that turned her) and lead to her taking increasingly more radical actions. Of course that is just the movie, I have never read the books (The Vampire Chronicles) myself.
*The Twilight Saga* (hold the groans) took the opposite direction in that child vampires do not mentally age, so their new found abilities made them incredibly dangerous given to underdeveloped minds. Temper tantrums could slaughter a village, which of course risked revealing vampire kind to humanity.
Over all though, I don't usually see many vampire stories showing functional child vampires outside of cartoons and anime, in which vampires usually age like any other creature, just very very slowly, and are often immune to natural causes of death, allowing them to be several thousand years old. I suspect this is usually more of a simple way to allow for child vampires, as the audience in this medium is often (but not always) children or teens, which of course need to relate to the characters.
If you are wanting to stick to the traditional, un-aging immortality version of vampires, then it seems puberty is kind of the rough line. Younger than this usually results in chaos, and is therefore generally avoided by all vampires. If you want to really push it though, I might argue that 7 or 8 years old is when children seem to start really comprehending more complex ideas about the world beyond their immediate environment, but it is also not horribly uncommon for puberty to start that young, so same argument.
[Answer]
I once went to a first birthday party for a kid that I had never met before. At the party I didn't see the baby I expected to see, and eventually I asked where the birthday boy was. And they pointed to a little kid running around, and I was shocked by how big and active that one year old kid was.
An expert on child development can tell you at what age ranges a typical child begins to learn and later master various abilities, and I expect that a typical child will master some of the listed functions years before others.
I have an idea for a character who becomes immortal at the age of 12. I think that at a height of about 0.83 to 0.9 of a typical adult, and with a weight & strength of about 0.5 to 0.7 of a a typical adult, they can function fairly well in a physical environment designed much more for typical adults than for children.
I think that a much younger and smaller child might also be physically capable of functioning normally if they became a vampire that didn't grow. I think that most children master walking, and running, and climbing, and dressing themselves, and eating, and taking baths, and of course talking fairly well before entering primary school around age six.
I also note that there are examples of kids who develop physically much faster or slower than typical kids. A vampire brat who is precocious physically before becoming a vampire might be able to do things that most kids their age couldn't. For example, when Robert Wadlow was 9 years old, he was 6 feet 2.5 inches tall and weighed 180 pounds, and could carry his father, seated in a chair, up the stars to the second floor.
[https://en.wikipedia.org/wiki/Robert\_Wadlow[1]](https://en.wikipedia.org/wiki/Robert_Wadlow%5B1%5D)
So I would guess that the minimum age for a physically functional vampire brat would be somewhere between about one year old and about 6 years old.
As for the mental development of your kid, there is absolutely no scientific evidence about the mental development of vampires. There is no evidence that a child that was made a vampire would regress to a younger mental age, and no evidence how much they might possibly develop and grow mentally.
[Answer]
What type of powers are you allowing your vampire?
Let Me In (2010)
If you can mesmerize your ghouls to bring you victims to feed on, you don't need much physical power at all. You just swap out ghouls every 20 years / when they get caught.
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[Question]
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A supervolcano has erupted (with a Volcanic Explosivity Index (VEI) of 8 or higher1) at Yellowstone Park. I am not in the kill zone and not in at least 300 km (~185 miles) radius so I have time to escape. I have survived the initial hazardous downfall of volcanic ash as well.
[](https://i.stack.imgur.com/cxSxIm.png) [](https://i.stack.imgur.com/ua6P9m.png)
Left image: Possible zone map after the eruption from [*reddit*](https://www.reddit.com/r/MapPorn/comments/a1tr67/possible_yellowstone_supervolcano_eruption/)
Right image: Known ash-fall boundaries for several U.S. eruptions from *[usgs.gov](https://www.usgs.gov/media/images/map-known-ash-fall-boundaries-several-us-eruptions)* (but it would be a larger area in our case):
**Immediate after effects:**
* In the most dangerous zones, no one survives (up to 100,000 people die in a short time period and the number increases quickly in the western half of North America) (It is covered with sweltering hot gases and up to 5m of volcanic ash at temperatures over 400ºC (~750ºF))
* A global alert is issued. Air/train travel is shut down across North America and soon around the world.
* People start to flee and major roads get stuck
* People start to steal and quickly finish supplies in the markets
* Toxic gases were pumped into the atmosphere, including sulfur (that would cause severe respiratory problems)
* Volcanic ash starts to cover much of the western half of North America and starts to spread around the world
**Long term effects:**
* The world is covered with an ash cloud with sulfur aerosols that block the sunlight
* Long term global cooling takes effect
* Rainfall significantly drops, most forests die off
* Agriculture/farming collapse, famine and diseases spread around the world
* Outlaw gangs, murderous raiders will rise around the world (closer to roads and resources)
* Billions of people die in several years
**How to survive the supervolcano eruption in short term and the post-apocalyptic world in long term?**
Related questions:
- What supplies do I need and can I get in short term?
- What strategy should I follow?
- Where should I go and settle? Should I be always on the move?
- How to find food?
Notes:
- I've tried to make the scenario realistic and detailed but you can let me know if I can update anything or if I can add more bullet points.
- I've searched the site if there is any duplicate question but I couldn't find anything similar or related to supervolcano survival. Although, there are many post-apocalyptic themed questions.
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1 A volcanic eruption with a VEI higher than 8 had never happened in the history but there is a potential. In our scenario, the eruption should effect the whole world over the years.
[Answer]
The trick to surviving a sudden collapse of society is to get out of it as quickly as possible and to go somewhere that few others are trying to get to.
In this case, owning a thirty-foot catamaran (equipped with a water still and ample fishing gear) and having the skills to operate it, your character could head out to the open oceans south of the tropics. As long as they stay away from islands and shipping lanes, you should be left relatively alone and safe until society returns.
[Answer]
You face several categories of dangers. The ash is going to be a problem. It will clog this and abrade that and cause difficulty breathing for everything that breathes, organic or machine.
Conditions are getting bad quickly. Infrastructure is collapsing or clogged with refugees. The power grid is not working. Gas station pumps won't be working, though there is likely still gas in the underground tanks. Any obvious source of resources is going to get mobbed and looted quickly. So, grocery stores will get stomped quickly. As will any outlet that has any sort of portable food or water. As will pharmacies and hospital dispensaries. As will clothing and shoe stores, especially "out doors" type stores.
Refugees will be getting more and more desperate for a variety of resources, food, water, shelter, transportation. This will result in, at first, riots, then pitched battles with whatever is available. In the US mid west, that means guns aplenty. Rifles, shotguns, hand guns, maybe some more esoteric and extreme weapons that somebody has in their private stash. Maybe the local police station has some interesting hardware. Maybe even the occasional military weapon, depending how far the local military base is.
You need transportation that will use small quantities of fuel, will be flexible as to surface it travels on, that can go around blockages of various kinds. And that you can improvise some sort of filter over the air intake for the engine. Motorcycle is popping up in my mind. Possibly ATV. It may be better to travel quickly away from the most intense ash fall rather than trying to acquire any resources. Maybe you can siphon fuel from vehicles with compatible fuel, so you want a motorcycle that takes "regular."
You will prefer a bike that is robust and rugged rather than pretty. But you will need to take what you can get. The dealership won't be open. Unless you already have a bike you will probably have to break into someplace that has them. You will want to do that early rather than late, since there will be many people with the same thought.
You will want a few buddies. Alone, you don't have any possibility of guarding your sleep. You will find places where you may need to lift the motorcycle over some small barrier like a wall or a rock fall or some such thing. Other situations call for backup. Four to ten people seems about right.
First priority is fuel for the bikes. Then food and water. And some camping gear of some kind. A water treatment kit would be good. You will want some kind of weapons, though you should not over do that.
Your first priority in a confrontation is avoidance not fighting. If you have a huge pile of guns it will tempt you to fight instead of run, and that is a mistake nearly all of the time. If there's a road block with people on it, you want to go around. Maybe the next road over, maybe through farmer's fields. But you want to avoid confrontation if you can.
If you can repair the easily predictable things that is good. Punctures in the tires. Broken wires or fuel line. If you get a major failure ride double until you can find a replacement rather than spending days trying to fix it. Spare parts are likely to not be available. Another reason you don't want to go alone.
You will need to suspiciously check the terrain ahead. Maybe "back roads" are better in some places as compared to the highway. You want places where there are unlikely to be gangs of people waiting to take your bikes, food, water, guns, etc.
Once you get out of the ash fall area it's a question of living as a refugee for a year or maybe two. Ash will, with rain, work itself into the ground. The ground actually comes back as better farmland in a year or two. So after about that long, everybody is moving back into the ash fall region and resuming their lives.
There will be many dead, and much damage to buildings and infrastructure. This is strongly localized near the center of the event. You basically lose all buildings and bridges and such in what you called the "Kill Zone." Since this area is a less populated area to begin with, the damage is far less than it could be. Outside that, the ash becomes mud on the first rain, and starts to work into the ground.
In 20 years, people will be resettled in the ash zones and moving back into the kill zone. They will reminisce about "The Big One" or "The Day It Happened." And the farm land will be a little greener.
[Answer]
**Nomadism**
You must always be on the move. There is no way that order would ever recover from such a catastrophe in any amount of time relevant to your survival.
The Volcanic Winter will bring crop failures, and the cities will be guaranteed death traps in a societal collapse purely on how many desperate people would be there. So you must trek through the wilderness seeking food that other humans won’t be immediately accessing and won’t be destroyed by the winter. This food source is wild animals. While ecosystems will be in a state of disruption if not collapse, you have far better chances hunting animals that survived the last ice age (elk, bear, deer) than subsisting on scraps or highly modified organisms that are dependent on a narrow temperature range and human care.
You should seek to move south and towards the coastline, but avoid cities and towns at all costs. Your goal is to move through undeveloped land, as you will encounter less raiders and more wild sources of food. Don’t bet on anywhere actually being a safe haven.
You should be equipped with a rifle, ample ammunition, warm and water resistant clothing, fire starting equipment, knives, hand saw, a pot for water and food, water containers, a purifier, wool socks, first aid kit, more socks and most importantly the skills needed to actually survive in the woods for the rest of your life.
Pack like you’re going on a hunting trip that will never end, because that is your life now.
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[Question]
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So, me and the boys have decided to take a trip down to Earth for reasons that matter not be it science, leisure or fleeing persecution. It is no concern how we blend in but our spacecraft poses an issue.
**How can we enter Earth's atmosphere without drawing attention to ourselves and then land?**
Also, I would like to make it clear my question differs from [this one](https://worldbuilding.stackexchange.com/questions/672/is-there-any-way-to-truly-hide-a-spaceship) as this question is about entering a planet specifically Earth and **not about space travel**, and also preferably no sci-fi invisibility.
The spacecraft in question, primarily uses Ion Thrusters although it would be permissible to have some additional propulsion method for planetary entry, the craft needs to carry six human sized passengers and the main propulsion is used for long distance journeys and as such the craft is not the most manoeuvrable using its main propulsion.
[Answer]
Without much manoeuvrability due to only having the main thrusters available, it would be hard to gain entry into earths atmosphere at a low-detection spot. Even then, it would be hard to not be spotted at all, since earth has meteorite detection satellites and radars trained at the sky at all times. With the [effectiveness being debatable](https://www.independent.co.uk/news/science/asteroid-nasa-near-miss-earth-emails-2019-ok-a9113846.html), still as an extraterrestrial you shouldn't count too much on being the exception. You could however, disguise yourself as a regular meteorite that is not noteworthy enough. A few things to consider:
**Entry point**
Where you enter the atmosphere is hugely important. This should be done either in Antarctica or over a large ocean to avoid being spotted. Preferably at day, as the heat diffusion from entry into the atmosphere for a craft that size will give a sizeable light show visible for miles at night. Having a meteorite land in the ocean will make it less attractive for humans to investigate as well.
**Heat protection**
As above, the heat generated from entry into the atmosphere is problematic. Considering the size of your aircraft is kept to a minimum and you can get away with a craft roughly the size of a commercial passenger plane (depending on how compact your tech is, and how much cargo you need for interstellar travel), you wouldn't be considered a problematic meteor (I'm thinking Boeing 747 sized). Especially over the ocean, this doesn't warrant action by humans as most of your "meteor" would burn up in the atmosphere, and the leftovers would be considered broken up and fairly harmless when landing in water. With adequate heat protection of course, your spaceship would survive atmospheric entry.
**Entry route**
To disguise yourself effectively as a meteor, you would need to keep movement to an absolute minimum. As a meteor is a rock without any propulsion systems, they would not be expected to change trajectory *at all.* You would need to get the correct entry angle from hundreds of thousands of miles away (from when you are most likely detected by earth), and keep this steady all the way through entry. Only after entry you would be able to move, as you would be out of range of detection.
**After entry**
There is still a chance of being seen by humans, be it fishing boats, military, or anyone just happening to be there. Even though you would probably fall quite quickly into the "UFO" category and stories would be taken with a grain of salt, it would be best to avoid visibility as much as possible. If your spaceship can take it, consider moving underwater. If not, very low and slow movement concealing yourself as a speedboat or yacht of sorts could potentially work. Avoid high (out of sight) flying movement, because any country's missile detection system could pick you up and would be sure to investigate the potential threat, if not straight up shoot you out of the sky.
**Landing**
Depending on what your intentions are, you might want to land as far away from humans as possible, or close to civilisation. This hinges on whether the spaceship is your only mode of transport, or more (inconspicuous) planet-side travel equipment is available. With there being more than enough hiding places anywhere on the world, you would be unlikely to be detected on this point. If you are sufficiently capable at avoiding being seen, you shouldn't struggle much here.
Now, you should start being worried about how you are going to leave.
[Answer]
**You disguise your spaceship as a Challenger 300 aircraft.**
[](https://i.stack.imgur.com/iHTZG.jpg)
<https://businessaircraft.bombardier.com/en/experience/profile/sammy-hagar-his-challenger-300>
And disguise yourself as businessman, philanthropist, and rock legend Sammy Hagar. You will hide in brazenly awesome plain sight. Your crew will be disguised as his entourage. You can apologize for the confusion as you enter airspace but will be permitted to land once they realize who you are. If they ask how you were flying at such high altitudes you can laugh and say "Are you sure?" Prepare to sign autographs.
[Answer]
Enter the solar system on the opposite side of the sun from Earth. Come around the sun and approach Earth on the day-time side. You’ll be extremely hard to see with the sun behind you, and it’ll cover any flare from your breaking engines.
Hang out around Venus’s orbit for a while until you see a really good solar flare head in Earth’s direction. Fire up your engines and join the flare. I assume your ship is well shielded. As you approach Earth, use a microwave laser or similar device to take out lots of satellites. Humans will think it’s the fault of the giant solar flare that you’re surfing. Do not discriminate on only the satellites with cameras or humans will get suspicious. When you’ve cleared a big enough hole in the network, fall on to Earth, aiming for a patch of empty ocean. Splash down, convert your spaceship into a water craft and sail into a port. Remember to disguise your tentacles and retract your eyestalks!
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[Question]
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It is believed that [Wendigos](https://en.wikipedia.org/wiki/Wendigo) are supernatural beings with an insatiable hunger for human flesh, or humans who are selfish and commit cannibalism and while the latter is more accurate, Wendigo fever is actually disease which originated in the New World which infects people who eat tainted meat. Some symptoms of Wendigo fever in chronological order are:
* victims start having nightmares
* victims body temperature starts to go up
* victims start to develop albinism
* eyes become more sensitive to light
* fat deposits are burned though making the victim have to eat constantly
* the victim experiences a near constant flow of adrenaline
* pain receptors start to go numb
* parts of the brain that control empathy go numb
* victims begin to have a craving for human flesh (but will eat other meats if no humans are near by)
Given these traits how realistic is this? What type of disease would it likely be, and how would it spread?
NOTE: magic does not exist in my story
[Answer]
**It’s a Prion**
There is already a deadly neurological disease caused by the consumption of human flesh. [Kuru](https://en.m.wikipedia.org/wiki/Kuru_(disease)) is a neurodegernative disease that causes uncontrollable shaking, loss of coordination, outbursts of laughter, ataxia, and a general state of delirium followed by wasting away. It was once common among the Fore People of Papua New Guinea, who were endocannibals.
Because prions damage the brain, everything from nightmares to appetite to pain receptors are all easily and credibly affected by them.
The brain controls the release of adrenaline, and if the body is constantly in overdrive it’s going to be continuously burning calories and therefore fat.
Albinism might be better explained not as true albinism per se, but the victim could just be very pale due to the metabolic effects of the prion, because albinism is a genetic disorder and it would take a while to lose all your pigment
[Answer]
Cultural factors are extremely important here. Compare Piblokto, an Inuit condition which is considered to be a culture-specific hysterical state and which manifests as a form of raving insanity.
The point is, victims act in in the way that their culture tells them they will when afflicted with this condition. Up to and including eating people. Pretty much all the symptoms can be produced by a psycho-physical reaction with no need for any external agent.
So un the real world Wendigo psychosis, like lycanthropy (or indeed demonic possession), is recognised as a real mental condition with a cultural dimension rather than a physical/supernatural one. Which may make it much harder rather than easier to deal with. (Google Wendigo Psychosis and you'll see what I mean).
So it's a culture-bound condition which spreads by people being aware of it, and having particular psychological triggers e.g. intolerable stress.
[Answer]
Your virus would need to destroy the ability to recept certain chemicals like serotonin, oxytocin which should reduce empathy
It should infect bacteria in the gut to make them more hungry, and synthesis dopamine to release once fed, causing the host to become addicted to the feeling
It should increase adrenaline production, causing the host to feel stressed and trigger the fight or flight response, possibility triggering canabalism
High adrenaline can also cause loss of memory and can numb pain and can increase physical strength, and the adrenaline induced state can increase heart rate and stop metabolism, causing fat to reduce.
One issue I see with this however, is that adrenaline can reduce hunger
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[Question]
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I am writing a story where the technology of the time could be roughly characterized as akin to ours back in the 90's, if not quite the history that led to it being that way. So you'd see things like 16/32-bit game systems, early cell phones and cable TV, but I'd like to find a reasonable way to explain why air power (both for military use & transportation) developed much later and so is behind.
So no commercial airlines and certainly no space flight or orbiting satellites. The most I'd like to allow would be a blimp or zeppelin, as high speed flight would require changing a bit too many things in the setting (which has a high focus on the magic/superhuman abilities of the military's ground forces, and it would mess with some other things I'm fairly committed to keeping).
My first thought would be to limit some material(s) to explain this, but I'm already doing that to explain why nuclear weapons aren't the premiere power over their replacement (very little fissile/fissionable material), so I'd like to avoid repeating that if possible. Would the fact that the major nations have often been at war for more than the past half century (including a few world wars) be enough justification, or is there a better way to go about this that I'm not considering? There's really no conflict between most of the use of the magic and the technology, so that's not the worry for me either.
[Answer]
# Toil Without Oil
A solution (which would definitely have more knock-on effects than just crippling air travel) would be to make petroleum virtually nonexistent on your world. Since you've got magic involved, maybe that somehow degraded what would otherwise have been petroleum deposits, making the petrochemical industry impossible.
Without oil, plastics would be a lot longer in coming to fruition (plastics using organic oils would still presumably eventually be developed), but more importantly, without oil, aviation fuel would be a much more complicated chemical prospect. Even prop planes would be difficult, and jet fuel would be nigh-impossible (for example, see today's attempt at biofuel solutions for jet travel). Synthesis from biological sources would probably eventually be possible, but would take much longer, and jet technology would lag similarly.
Conversely, *electrical* power would likely be more popular earlier. Electric cars [were popular before internal combustion was more successful](https://en.wikipedia.org/wiki/History_of_the_electric_vehicle) - in this case, the lack of oil would result in extended popularity and probably major battery improvements - so your putative airships could be electric!
This is only scratching the surface of what would happen if petroleum wasn't broadly available, but would definitely hamstring aircraft development!
[Answer]
I think the biggest plausible change to reality you could engineer is a difference in the development of energy production technology to remove oil and natural gas as fuel options. Your alternate-reality 1990s society developed through an Industrial Revolution in which liquid fossil fuels were never tapped on a wide scale as a source of energy; humans transitioned from wood and coal into more sustainable sources like hydroelectric, nuclear and solar without the oil step in between.
How did that happen? That's your problem to solve. Maybe the first wells that would have been commercially exploited in our own reality instead exploded into massive infernos, killing thousands, poisoning nearby waterways and leading to an international moratorium on oil drilling, much as various nuclear accidents have muted the conversation of ramping up nuclear energy as a substitute for fossil fuel use in grid electricity in our own reality. Coal mining is still tolerated, but the world's growing energy needs led to more widespread adoption of nuclear plants, perhaps despite Three Mile Island or even Chernobyl. To store and mobilize electrical power, battery technology was also accelerated, so your 90s-era society, instead of still using toxic and relatively less dense nickel-cadmium chemistry, discovered and commercialized lighter and denser lithium-ion chemistries on an accelerated timeline.
The lack of oil to replace coal- and wood-burning rail engines required a rail technology powered by grid electricity, thus prompting Eisenhower to build a highly-connected, Federally-funded high-speed rail network, co-opting private and/or State ownership of the existing railroad. Rail, not roads, became the primary transportation grid of the United States (and of many other countries besides), and what road vehicles do exist are battery-powered short-range vehicles, designed for use in "park-and-ride" commutes to drive a few miles to the nearest mass transit station and catch one of the trains running every five minutes along routes closely mirroring major highway networks in and between major cities. Anywhere you want to go, a train will take you, unlike the situation in most of the US's major cities.
However, without petroleum, the energy requirements for a practical commercial aircraft just don't exist. The energy density of even modern batteries can't even be accurately plotted on linear-scale energy density graphs that include fossil fuels and hydrogen. So, while knowledge of the fundamentals of flight are still commonplace, the taboo of oil use stunted the development of powerplants that were small, light, powerful and reliable enough for meaningful flights of large-scale aircraft. Ultralights that run on batteries or wing-incorporated solar panels are toys for the rich (much as they are now), but by this alt-1990s timeline, we never solved the problem of how to get enough energy density into the air with a required level of safety and reliability (nuclear planes were looked at for all of 5 minutes before someone asked what would happen when one crashed in a populated area), and so commercial air travel never developed to supplant rail and ship travel as the fastest, safest way to move humans over long distances.
[Answer]
**Fuel**
From the background I am not entirely certain what abundance there is of fossil fuels on your world. But if your world is strapped in this particular resource flight, especially commercial flight will be severely stunted/restricted and horribly expensive.
Whereas cars can drive electrically, I don't see any electrical commercial airplanes flying any time soon for a reasonable price. I won't go much deeper into this as jdunlop covers this quite well in his answer.
**Resource scarcity**
Having said this, fuel isn't the only restrictive factor. Any kind of important resource missing for modern flight could influence your stunted development of flight. What if your world lacks the meaningful amounts of aluminium needed for large scale commercial or even military flight. (A steel fuselage would be way too heavy, and composite material planes are usually military grade and extremely expensive/costly.)
**My take** (Somewhat opinion based)
Then there is the issue you mentioned that they underwent world wars. The military would grasp to any means that'd give them an advantage. So even if they have modern planes, they have (very) few and are used sparingly or only in the hour of gravest needs, which in turn would provide you with another plot device centered around the rarity of aviation, especially the modern kind, to make it an exceptionally big threat, yet generally underdeveloped in a broad sense.
[Answer]
You mention magical abilities of ground forces. Make one of their abilities be to change air pressure and wind direction within some range of their location. That would make early aircraft very dangerous, delaying development. To be safe and useful, aircraft would have to fly high enough to need pressurization, and each airport would need a wide security zone to prevent sabotage during takeoff and landing.
[Answer]
If helium was very plentiful the cost of large airships might be quite low and this might mean that airships become the accepted means of transportation being able to carry fairly high loads very cheaply and faster than ships at sea. They would not need the extensive runways required by conventional jets and could drop loads at remote locations when needed. The flights would also be safe from fire and vast air liners might develop giving oceanic liners a run for their money.
In this world jets do not really get off the ground as they aren't seen as competitive with airships for the above reasons.
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[Question]
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Some cataclysmic event has transpired on planet Earth in the not-too-distant-future, and the outside air is now thick with CO2, causing all of the problems that come with it. Human beings can no longer breathe the air directly, global temperatures have spiked, and the flora and fauna of the world have been affected drastically. A few pockets of civilization have survived in highly advanced compounds, and they want to start working to undo the CO2. I'd like this process to have a decently long time period before it is sufficient for humans to survive on the surface again, at least a century.
Assuming that all scientific knowledge has survived, and assuming that my survivors can get creative with how they acquire resources, what are some methods to begin to slowly change the planet's atmosphere back?
[Answer]
**Fusion powered CO2 splitters.**
With limitless energy (they have that, right?) one can use a variety of catalytic methods to split the CO2 molecule. Most of these reactions yield carbon monoxide and oxygen but it is possible to produce carbon (soot) and oxygen, and more promisingly with the use of some hydrogens from water, methanol and oxygen.
Your earth remediators take it one step further, splitting an oxygen off CO2 to form carbon monoxide, hydrogenating the CO to form methanol, then adding an addition CO and driving off the oxygen to form ethanol. The CO2 surplus is therefore converted to large quantities of ethanol, which is stored in flavorful charred wooden casks for later use.
[Answer]
The problem is that nothing small groups of humans are going to be able to do is going to have much of an impact on the atmosphere. It took literally billions of us a couple hundred years to put all that CO2 into the atmosphere. Removing it would take absolutely MASSIVE infrastructure.
Now, that having been said, eliminating most of the human beings and their CO2 emissions would do a lot towards slowly bringing things back into balance. Over the course of several decades without human interference, plant life would take over massive tracts of land. The more plants you have, the more CO2 those plants are converting back into Oxygen. It'd take centuries obviously, but it's a natural process that would take place all by itself.
Now, something that your plucky survivors COULD potentially do is help accelerate that process. For example, seeding arid lands with genetically engineered seeds that can spread rapidly in areas that humanity has abandoned could do a lot over time.
[Answer]
With 7+ billion people and all our technology we are still far from being able to modify the atmosphere of a planet. It took more than one century of industrial development to slightly increase the content of CO2 in our atmosphere.
With less humans available we won't be able to make a significant dent into the content of the atmosphere with any tech mean. The only way would be to plant trees and plants and let them suck it out the CO2 with their growth. But, again, being few they won't probably do any better than natural propagation of plants.
[Answer]
One possible way for the embattled humans would be to bioengineer a more effective organism for carbon capture. Many of the existing plants and algae can do that - but in doomsday scenario they have to do better than that.
The new organism should be:
1. Prolific. It should grow fast and multiply quickly;
2. Sturdy and tolerant. It should be able to occupy most areas of the overheated Earth;
3. Don't quickly release carbon after its death. This is the most tricky part. Many organisms are capturing carbon all right - but after the death this carbon usually returns back to the atmosphere via rotting or other processes. So, the new organism either has to be build of a completely new organic compound which existing bacteria does not know how to digest (like cellulose was back in [carboniferous period](https://en.wikipedia.org/wiki/Carboniferous)), or wrap itself in some kind of sturdy mineral-based shell so its organic content would be trapped inside.
The new organisms would quickly populate the Earth and begin a long process of trapping the excess carbon dioxide.
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[Question]
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I'm building a world that has a feature that is meant to separate the world in half so civilizations on each half won't contact one another. The feature is magical in origin, but does not seem magical at first glance and the barrier is itself something physical not magical. I want to make it as realistic as possible.
Over the continents the feature could take the form of a high mountain range surrounded by harsh desert but I am open to other ideas. I am not sure what the feature could be over the sea, perhaps a permanent storm?
So the question is twofold:
* What type of feature would keep a civilization with 18th century technology (advanced age of sail but pre-industrial) to be unable to cross it?
* What effects would such a feature have on the climate? Keep in mind that the feature splits the otherwise Earth-like world in two so it will be on the scale of the whole planet.
[Answer]
Iapetus, a moon of Saturn, has a strange equatorial ridge along part of its equator.
The geology of Iapetus is very different from that of an Earth like planet, so I don't know if the forces that produced the equatorial ridge on Iapetus could produce one on an Earth like planet.
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> It is not clear how the ridge formed. One difficulty is to explain why it follows the equator almost perfectly. There are at least four current hypotheses, but none of them explains why the ridge is confined to Cassini Regio.
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> A team of scientists associated with the Cassini mission have argued that the ridge could be a remnant of the oblate shape of the young Iapetus, when it was rotating more rapidly than it does today.[4] The height of the ridge suggests a maximum rotational period of 17 hours. If Iapetus cooled fast enough to preserve the ridge but remained plastic long enough for the tides raised by Saturn to have slowed the rotation to its current tidally locked 79 days, Iapetus must have been heated by the radioactive decay of aluminium-26. This isotope appears to have been abundant in the solar nebula from which Saturn formed, but has since all decayed. The quantities of aluminium-26 needed to heat Iapetus to the required temperature give a tentative date to its formation relative to the rest of the Solar System: Iapetus must have come together earlier than expected, only two million years after the asteroids started to form.
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> The ridge could be icy material that welled up from beneath the surface and then solidified. If it had formed away from the position of the equator at the time, this hypothesis requires that the rotational axis would have been driven to its current position by the ridge.[citation needed]
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> Iapetus may have had a ring system during its formation due to its large Hill sphere, and the equatorial ridge could have then been produced by collisional accretion of this ring.[5]
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> The ridge and the bulge could be the result of ancient convective overturn. This hypothesis states that the bulge is in isostatic equilibrium typical for terrestrial mountains. It means that under the bulge there is material of low density (roots). The weight of the bulge is compensated by buoyancy forces acting on the roots. The ridge is also built of less dense matter. Its position along the equator is probably a result of the Coriolis force acting on a liquid interior of Iapetus.[6][7]
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<https://en.wikipedia.org/wiki/Equatorial_ridge_on_Iapetus>[1](https://en.wikipedia.org/wiki/Equatorial_ridge_on_Iapetus)
Some of those methods might be more plausible on an Earth like planet than others.
Since it would take billions of years for life and intelligent life to develop on a planet, either the equatorial ridge would have been produced by gradual geological processes instead of by a terrible disaster, or else those terrible disasters would have to be billions of years in the past by the time of the story.
If an Earth like planet had an equatorial ridge without any passes low enough to have air thick enough to breathe easily, but instead was everywhere so high that oxygen tanks would be needed to cross it, the two hemispheres will be out of contact until and unless high flying aircraft are invented.
Depending on the age of the ridge, life in the two hemispheres could have a common origin or else have developed totally separately and have radically different biochemistry.
[Answer]
I suggest raising the mid-Atlantic ridge up to just below the surface of the ocean and expanding it to a 100 mile wide band of treacherous shallows and reefs running from pole to pole with another similar band running through the centre of the Pacific.
This band would consist of a series of impenetrable reefs each a few miles wide running from pole to pole each separated from the next by 10 miles of open ocean.
The whole area would regularly be swept by violent storms. There would be no fresh water available other than rain water, no islands to land on and no way for a sailing ship to cross the reefs or for any form of base to be built. In the unlikely event that a small vessel did manage to cross one of the bands, by sailing further they would only encounter another reef.
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I had a similar idea for a setting of my own. I settled on twin granite walls/ridges running alongside each other, 1 kilometre high, too steep to climb and too hard to easily drill through. So it would be a tremendous effort to get over, requiring at least medieval technology to build scaffolding to reach the top.
And in the space between the walls, a narrow, islandless sea with water poisonous to man and fish alike. So anyone who got over the wall somehow would not find anything useful on the other side - even the other wall would be just over the horizon.
So this wall would be mountable since perhaps the 1500s, but nobody would have great reason to get to the second wall and across that until the invention of powered flight. It also should not be high enough to hinder climate or migratory birds that much. Plus the poisonous water in the inner sea would evaporate and turn into poisonous rain alongside the walls, meaning that people would not want to live next to it either.
I am interested in the other potential solutions though.
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In the 18th century there were no airplanes, so the o ly way across the old world and the new world was by ships.
If the oceans were overtaken by some bacteria that secreted an acid gas, such as HCl, nobody would be able to cross. There was no technology to make an hermetically sealed ship, nor to drive one, nor to store breathable air for long term travel. This would also kill all marine life that dwells by the surface, unfortunately. Also coastal cities and would all become ghost cities.
The effect on the weather would probably be minimal on a scale of decades or centuries. But hurricanes would be deadlier than the plague wherever they hit.
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**A radioactive zone of death.**
Your people are separated by 'death zones' - deserts liberally salted with highly radioactive materials. Anyone who tries to cross them dies, and they don't know why.
The magic part could be that if people try to cross by balloon, dust storms kick up which poison everyone. Those dust storms could also be created when people try to cross by land, to ensure maximum contamination.
18th century people would have no idea what's happening. It's just a cursed land that no one can cross without dying shortly thereafter. And worse, when people do come back, they mysteriously cause other people around them to get sick and die. so there would be a strong cultural bias against even trying.
Since the dust storms would be magic and local, none of this would have any effect on the global climate.
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Does it have to be magical?
A world somewhat hotter than earth where the equatorial regions are lethally hot for the native intelligent species would work.
Another possibility is two habitable polar continents with a continuous equatorial ocean. The ocean is warm enough for continuous hurricanes to circle the globe. That would make it very difficult for pre-industrial cultures to cross between continents.
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This reminds me of a tidally locked world. Granted, in tidally locked worlds, the climate is very different on the two halves of a planet, and said halves would likely be uninhabitable, due to their unstable weather. The planet would also be likely to orbit a red dwarf star.
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This is based on: [Black Hole as a Storage Device](https://worldbuilding.stackexchange.com/questions/159146/black-hole-as-a-storage-device)
What goes into a black hole doesn't come out (except as random electrons or positrons).
However, is it possible to store something within the event horizon of a black hole and then use hawking radiation to shrink the black hole to the point that the event horizon retreats past the stored object?
This scenario has some built in assumptions:
1. The object is strong enough to withstand the tidal forces that close
to the black hole.
2. You have the energy to enter into a decaying orbit that will slow
the fall to a reasonable rate.
For assumption 1, we can just propose some unobtanium gotten from the same place that will give us enough energy to have a measurable effect on the radius of the event horizon.
Assumption 2 might not be too difficult to achieve since the rate of fall slows as you approach the black hole (because time slows). So, you just have to help that process along by making the spiral as shallow as possible.
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I'll try to keep it simple.
The gravitational pull on earth is +/- 9.8m/s^2. To float without going closer to the surface you need to push yourself away with exactly that amount of counter acceleration force every second to cancel the gravitational acceleration. This is what something like the ISS orbiting the earth does. It moves so fast sideways (7660m/s) that it falls as much towards earth as it moves around it.
No matter the size of the BH, at the event horizon the gravitational pull is 299792458m/s^2 (reading Mark Olson's answer and looking into it there seems to be no consensus yet for the "surface" gravity at the event horizon so I'll just stick with this for now as it does illustrate the problem well I think). To reach that kind of acceleration with any kind of mass you need infinite energy. This is why it is impossible to escape once you meet the event horizon. The example above to cancel out 9.8m/s you needed 7660m/s to not fall into earth. To cancel out an acceleration the speed of light you would need to go faster than light. I hope your unobtainium has some infinite power reactors and doesn't mind time traveling because that's what's going to be needed to do this.
You try to find a trick around this by launching the object in a trajectory that will cause it to "orbit" the BH and take longer to reach the center, then let the event horizon shrink fast enough that it catches up on the object. Now we know that light cannot escape if it enters the event horizon of a BH so even when you do go the speed of light and try to go directly against the pull of a BH the event horizon will never shrink fast enough to reveal the object, because the object cannot reach the speed of light itself.
There is also another problem: Evaporation rate. I'm using this calculator because this kind of math isn't something I'm going to take time learning any time soon: <https://space.geometrian.com/calcs/black-hole-params.php>
A BH with a 1m event horizon radius is 10 septillion KG, or 6.733176548\*10^26 (as I understand it E+26 means 10^26, correct me if I'm wrong). That's a "mere" 112 earths that fit into that BH or 3x our sun. This BH already takes 8.135956940\*10^44 TRILLION years to evaporate. In years thats 8.135956940\*10^56 or 80 septen-decillion years. When you have to look up the names of the numbers you know you are already pretty far gone. Again, that is 10^44 Trillion years to evaporate a 1m radius, so your object would have to be small! A BH that evaporates in a day has an event horizon radius of 1\*10^-20. An atom is the size of 1\*10^-10, so your item would need to be 10 magnitudes smaller than an atom to fit in a short-lived BH. I'm ignoring the explosion this BH causes as it evaporates it's last energy as your object can survive in a BH. But even then it would never be able to have a total velocity greater than the speed of light and would never get out of the BH event horizon.
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Short answer: No.
Long answer: Not as far as was can tell.
Black Holes (BHs) are solutions to the equations of General Relativity (GR) and GR is a phenomenally accurate and mathematically elegant theory of gravity. It shows that gravity is not a force at all, but a side-effect of the curvature of space-time. GR has been tested repeatedly and passed every test with flying colors. No other theory of gravity is as elegant or matches experiment better than GR. For those reasons, we think that GR gives a good picture of what's really going on with space, time and gravity.
A Black Hole is a region of space-time where mass-energy has been so concentrated and the curvature become so extreme that space-time inside the surface of the BH is fundamentally different than outside. Specifically, (and inevitably approximately since I'm using English and not math) space and time twist around so that inside the BH the radial coordinate is *timelike*. And that means that, just like outside the BH we can't stop ourselves from moving forward in time, inside the BH, we can't stop ourselves from falling towards the center.
Anything put inside the BH (inside its Event Horizon) inevitably, no matter what velocity it is moving at and no matter what kinds of acceleration is undergoes, falls to the center and is obliterated by the singularity that lurks there. In particular, unobtanium does not work if it is made of either matter or energy or a mixture of the two.
Assuming that Hawking Radiation exists (we have never observed it, but it's on pretty firm theoretical ground), all BHs eventually evaporate, but not before anything that crossed the Event Horizon has gone splat (or whatever) against the singularity and been destroyed.
Now we have some pretty good reasons for thinking that GR isn't the final theory of space-time and gravity, but those reasons also tell us that it is a *very* good approximation in big BHs and away from the central singularity. (Called the "weak field" region, though it's only weak by mathematical standards.) We also have good reason to think that whatever replaces the singularity in the New and Improved (and so-far Undiscovered) theory will be just as dangerous to matter and energy.
About the only way you can put something into a BH and get it back later is to either (a) ignore General Relativity altogether (in which case what's a Black Hole doing there?) or (b) assume that the super-scientists who discovered unobtanium have an arbitrary new theory which allows the construction of arbitrary new gadgets which do arbitrary things. (Either way you're using something called "magic".)
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No, because [black holes have no hair](https://en.wikipedia.org/wiki/No-hair_theorem).
>
> The no-hair theorem states that all black hole solutions of the Einstein–Maxwell equations of gravitation and electromagnetism in general relativity can be completely characterized by only three externally observable classical parameters: mass, electric charge, and angular momentum. All other information (for which "hair" is a metaphor) about the matter which formed a black hole or is falling into it, "disappears" behind the black-hole event horizon and is therefore permanently inaccessible to external observers.
>
>
>
This leads to the [black hole information paradox](https://en.wikipedia.org/wiki/Black_hole_information_paradox)
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> The black hole information paradox is a puzzle resulting from the combination of quantum mechanics and general relativity. Calculations suggest that physical information could permanently disappear in a black hole, allowing many physical states to devolve into the same state.
>
>
>
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Storing any objects, as kind guys before me explained, is not possible, but storing some data? Not much but its something.
**How to do it?**
Its simple, as we know, black holes have given charge, this charge is depended on charge of things BH consumed. So, lets assume you give certain values for certain charge values of BH, even something simple like negative charge is 0 and positive is 1. Later combine arrays of black holes and bam, you can store any data on black holes.
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For this question, I was inspired by the following image of the "Jupiter Abyss":
[](https://i.stack.imgur.com/e5ady.jpg)
What I want to know is, can a Jupiter-like gas giant have thousands of giant black storms, kind of like what I've created in the following image?
[](https://i.stack.imgur.com/MiuB7.png)
Please do not take the image too seriously, as I only did my best to mock up what I'm looking for (which is why there are only a few storms instead of hundreds). In reality, I want the storms to get deeper towards the center, making light harder to reach there, which gives the impression of a whirlpool-like dark or black storm.
EDIT: The storms wouldn't need to be persistent. They can form and dissipate, I'm just looking for them to look like tons of giant black dots from space.
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This is Jupiter after being hit by Shomaker-Levy 9 in 1994:
[](https://i.stack.imgur.com/uEpos.jpg)
It smoothed out in days, but hey, there you have dark spots. A constant bombardment would do for a fictional planet.
Edit: while researching something else, I came across this time lapse of Voyager 1 approaching Jupiter in 1979. There are many dark spots at the boundary between the north pole and the northernmost light band.
[](https://i.stack.imgur.com/O1QBs.gif)
Gif taken from [the wiki on The Great Red Spot](https://en.wikipedia.org/wiki/Great_Red_Spot).
This is [Saturn's Hexagon](https://en.wikipedia.org/wiki/Saturn%27s_hexagon):
[](https://i.stack.imgur.com/5a0u5.jpg)
It is a permanent formation in the shape of a hexagon that rotates slightly slower than Saturn itself. It is darker than its surroundings. With the right chemistry, it could be much darker.
I think such formations could form in a gast giant in lower latitudes if you have bands rotating in different speeds.
Notice that besides the hexagon, there is another darker spot close to halfway to Saturns equator.
From another angle, more dark spots can be seen as well, in high latitudes:
[](https://i.stack.imgur.com/gWGCw.jpg)
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You've seen the "Great Red Storm" on Jupiter, right? You know that is a massive storm cloud with a cyclonic motion (like a Hurricane or Typhoon on Earth). This particular storm has been on going since it was first observed in 1800 and believed to be at least 350 years old and while it is shrinking overtime, suggesting it will not be persistent the storm is presently ~10,000 KM in length, which is more than enough to fit the entire planet earth into the storm. It's not the only persistent storm on Jupiter, just the biggest and visible from Earth by telescope, making it a defining feature of the planet.
Jupiter is not the only gas giant with this storm, as recently, NASA discovered a similar sized storm over saturn's southern pole (which is why we never saw it on Earth) that initial estimates of it's age put it in the billions. Can't give you a color on that storm, because it was observed in grey scale.
But the best news is that there are several "Great Black Spots" on Neptune. While not as big as the Jupiter and Saturn stoms, they are still hurricane like massive storms that, as the name suggests, are black and do swirl like a whirlpool. So it's not only plausible, but factually occuring.
And I'd be re-missed if I didn't talk about the fourth member of our solar system's gas giants, but it is my duty to report that I could not find any persistent storms over Uranus (sorry, couldn't write about the gas giants and not make joke about that one).
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Like earthly storms, any storm needs an energy supply to form. This means that if a storm is forming in region A, that region won't trigger another one until the energy storage is replenished.
Look at the hurricanes or typhoons which form in a season: if they originate in the same spot, they will be separate by a certain time. If they form close in time, they will be separate in space.
Add to this the inherent chaotic behavior of weather, and you see that having closely adjacent storms is highly unlikely, bordering he impossibility. Have sparse storms is instead plausible.
And don't forget that a zone of low pressure like the storm has to be surrounded by high pressure, else there would be no flow and no storm.
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That's a difficult question to answer, since the climate of the gas giants works very differently from the Earth's climate.
On Earth, when two or more cyclones get very close, two things can happen: if they are of equal size, they begin to rotate around a barycenter, but if the difference in size is significant, the smaller ones will rotate around the larger one, until it devours and fuses them, creating a larger cyclone. This is known as the *[Fujiwhara effect](https://en.wikipedia.org/wiki/Fujiwhara_effect)*.
There is evidence of fusion between cyclones in Jupiter, in fact the [Little Red Spot](https://www.nasa.gov/centers/goddard/news/topstory/2006/little_red_spot.html) was formed by the union of three cyclones.
Look at this image:
[](https://i.stack.imgur.com/1Vf1a.jpg)
What you see is a cyclone at the north pole of Jupiter surrounded by eight smaller cyclones. Something similar occurs in the south pole, but with five cyclones instead of eight.
Their apparent stability is disconcerting, the mechanism that led them to their current state or why they do not merge as expected would not be known.
In conclusion, the scenario you pose is unlikely at latitudes close to the equator as, over time, cyclones would merge to create larger cyclones, but it could work at the poles.
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In a certain star system, Star B orbits Star A. Planet C lies in between the two stars and also orbits Star A. Planet C and Star B share an orbital period, and are at roughly the same places in that period. Consequently, there is no night on Planet C. As Star A sets, Star B rises.
Is such a configuration possible (and if so, plausible)? Could such a planet support life, or would the constant exposure on both sides to radiation make the planet too hot?
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The short answer is: No.
To have the same orbital period, they would need to be in the same orbit.
If the planet was in L-4 or L-5 (see [Wiki: Lagrange Points](https://en.wikipedia.org/wiki/Lagrangian_point))of Star B which is orbiting Star A, there would be very little night but there would still be night.
the only way for this to work is for the planet to be in L-1 between the two stars. the problem is that L-1 is not a stable location and the planet would have drifted off of that position and begun a wild ride orbit long before life could have developed.
Also, I can't imagine that L-1 would be in the habitable zone in any case. There may be a way to jigger the star masses to make that work but the planet still wouldn't stay where it belongs.
The only way for it to work is to find a planet that just happens to be in the proper position now but will soon leave it. Not much chance of life there though.
You could try an Earth-like moon orbiting a gas giant. The gas giant may be reflective enough that it will be almost as bright as the direct sunlight.
Edit:
One possible solution is that the two stars are roughly the same mass and the planet orbits the center of mass of the two stars. I still don't think that would work but someone might be able to math that out. It seems to be too much like balancing on a pin.
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"Planet C and Star B share an orbital period" - unfortunately, this won't work. The orbital period of an object is proportional to how far away it is from the object it orbits (more specifically, the [oribtal period](https://en.wikipedia.org/wiki/Orbital_period) squared is proportional to the cube of the distance). That means if star B is farther away from A than C is, B will orbit more slowly.
Habitability is much more plausible - the habitable zone of a star depends on how bright the star is. If you somehow had a star on each side of the planet, you'd just need the planet to be at the outer edge (or maybe a little outside it) of the what the habitable zone would be for each star by itself. There is some point at which the stars will be far enough away that the planet is kept at an acceptable temperature only because there is no night.
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**SHORT ANSWER:**
No never, not ever!
**LONG ANSWER:**
One of the hardest problems of all when designing a fictional solar system is to create one where a planet is warm enough for life, and is habitable for humans, and has either eternal night or eternal day all over the planet's surface.
It is really easy to design a solar system where the closer planets are tidally locked to their star, meaning that their rotation periods and orbital periods are the same. Thus one side of such a planet will always face their star and have eternal day, while the other side of such a planet will always face away from it's star and have eternal night.
it is believed that there should be many billions of such planets in our galaxy. It is uncertain whether such planets could be habitable, but if a significant percentage of such planets are habitable then they should be very numerous in our galaxy.
<https://planetplanet.net/2014/10/07/real-life-sci-fi-world-2-the-hot-eyeball-planet/>[1](https://planetplanet.net/2014/10/07/real-life-sci-fi-world-2-the-hot-eyeball-planet/)
<http://nautil.us/blog/forget-earth_likewell-first-find-aliens-on-eyeball-planets>[2](http://nautil.us/blog/forget-earth_likewell-first-find-aliens-on-eyeball-planets)
So if you want one side of your planet to have eternal day while the other side has eternal night, that's really easy.
If you want eternal night all over your fictional planet, that can be easy. You can just make your fictional planet a rogue planet that is not in any solar system but is in interstellar space instead, and thus is lit only by dim starlight in its eternal night. Astronomers believe there are many billions of rogue planets in our galaxy, far from the heat of any star and thus with temperatures just a little bit above absolute zero.
Temperatures just a little bit above absolute zero! What if you want to have Earth like life on your planet requiring Earth like temperatures, large multi celled lifeforms, or intelligent natives, or a world habitable for Earth humans? Then you are out of luck with a rogue planet, unless you can imagine or learn about any theories about how a rogue planet could have eternal night and also Earth like temperatures.
<https://planetplanet.net/2015/06/04/real-life-sci-fi-world-8-the-free-floating-earth/>[3](https://planetplanet.net/2015/06/04/real-life-sci-fi-world-8-the-free-floating-earth/)
Of course any planet, whether in a solar system or a rogue planet, could have eternal day if an advanced civilization decided to make that happen. They could put a number of gigantic space stations in orbit around the planet. Each space station would have countless gigantic fusion power generators generating vast amounts of electricity to power countless giant lamps pointed at the planet. If enough of those "Sun Satellites" were in orbit around the planet at least one at a time would always be visible from every place of the planet's surface, and every place on the planet's surface would have eternal day.
Isaac Asimov wrote a famous science fiction story "Nightfall" where the planet Kalgash had eternal day over its entire surface. There were six stars in the Kalgash system, and so there were always at least one or two of them above the horizon everywhere on the planet.
Except that once every two thousand Kalgash years the orbits of Kalgash and the stars would put only one star on one side of Kalgash and the other five stars on the other side of Kalgash. And at the same time, a large moon of Kalgash would eclipse the only star on that one side of Kalgash and plunge that side of Kalgash into the first darkness in 2,000 years. And the eclipse would last so long that the rotation of Kalgash would turn the whole half of Kalgash that had been facing the other five stars at the beginning of the eclipse to face the one single star that was eclipsed, and so that other side of Kalgash would also face hours of darkness for the first time in 2,000 Kalgash years.
Would the Kalgash system be possible?
Astronomers have identified many multiple star systems, including some, like Castor, that have six stars, and even two with seven stars. s astronomers have learned a lot about the orbital dynamics of multiiple star systems and the possible orbits of hypothetical habitable planets in them, etc.
PlanetPlanet is a blog 'about where planets come from and where they are going". And it has a section where the blogger Sean Raymond discusses the plausibility of various solar systems in science fiction. And that includes two posts where Raymond tries to design a workable version of the Kalgash system:
<https://planetplanet.net/2018/02/02/real-life-sci-fi-world-11-kalgash-a-planet-in-permanent-daytime-from-asimovs-nightfall/>[4](https://planetplanet.net/2018/02/02/real-life-sci-fi-world-11-kalgash-a-planet-in-permanent-daytime-from-asimovs-nightfall/)
<https://planetplanet.net/2018/03/21/asimov-kalgash-take2/>
And you can see that Raymond had a lot of trouble designing a realistic Kalgash system.
And you could take some of his proposed solutions as the basis for a habitable world which is always in eternal day all over the planet. Even though it seems extremely improbable for some of those solar systems to form naturally.
See answers to this question: [Is a habitable planet in a sextenary star system possible?](https://worldbuilding.stackexchange.com/questions/44950/is-a-habitable-planet-in-a-sextenary-star-system-possible/112136#112136)[5](https://worldbuilding.stackexchange.com/questions/44950/is-a-habitable-planet-in-a-sextenary-star-system-possible/112136#112136)
Or you could have your fictional solar system happen by chance to pass through a "stellar nursery" as both orbit around the center of the galaxy. It could take your solar system many thousands or even millions of years to pass through the "stellar nursery". A "stellar nursery" is a giant nebula of dust and gas that is condensing to form stars and solar systems. And as the stars form and begin to shine some of their light should be reflected off dust and scattered in all directions, and some of their light should make the gas emit its own light.
And if your solar system has been light years deep within that "stellar nursery" for thousands or millions of years, maybe the light from all around the solar system might be intense enough to make a difference on the planet. It is possible that, for example, if the background light from the gas and dust in the dense nebula is at least one percent of the intensity of the light of the planet's star, when the planet's star sets the sky won't get as dark as it would on Earth and the sky will remain blue, though much darker, and other stars will not be visible, and it will seem more like a very dim Earth day than like an Earth night.
But I have not calculated whether it would be possible for such a dense and bright nebula to illuminate the planet that much and I don't know if that is possible.
Another possibility is that a globular star cluster is passing though the galactic disc, and its orbit and the orbit of your solar system happen to intersect. It could take your solar system many thousands of years to pass through the dense central region of that globular star cluster, and for all that time the combined light from the thousands of closest stars might possibly be intense enough to make the night on your planet look more like a very dim day on Earth.
But again, I have not made calculations to see whether the light in the core of a globular star cluster could be intense enough. Possibly you could get some other user here to do such calculations for you.
[Answer]
I think yes.
1. Start with Earth (planet C) and sun (star A). You might make Star A a little more massive and move Planet C's orbit out some.
2. Star B is a little star - equal to 75 Jupiters. It is far away, in approximately the orbit of Neptune. It is more massive than a planet and so it can (must) move much faster than Neptune does. Also you need it to move fast to complete its orbit in the time planet C completes its much smaller circle. At the same time you need it to stay far away from Planet C or its proximity is going to perturb the planet's orbit.
A thing to remember about orbits: X does not orbit Y. X and Y orbit their common center of gravity. When X (e.g. star) is of hugely greater mass than Y (e.g. planet) then their center of gravity is usually still within X. But if you have 2 stellar mass objects then the center of mass might not be within one of them.
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Assume the surface of the planet is experiencing ice age conditions and the facility was designed to keep the occupants alive for 6 months.
An emergency forces the permanent closure of all Heating, Ventilation, and Air Conditioning (HVAC) vents for immediate survival. Going to the surface isn't an option.
I had read, though I can't find the source at the moment, that any underground habitat requires cooling or the human's body heat will turn the place into an oven.
There seems to be some doubt that the human body will cause the temperature to rise in a closed underground chamber. If I could access this study on thermal engineering I wouldn't have asked because it would have my answer. However, the link proves that in fact, the temperature will rise if there is no venting. Natural thermal convection based on human body heat. <https://www.sciencedirect.com/science/article/abs/pii/S1359431118332563?via%3Dihub>
As for size of the facility, using the rpg's construction rules, 400 people would fit in a 240,000 square feet building.
[Answer]
There is a lot of unknowns in your question and this is one of those questions where the devil is likely in the detail, but the key point is that unless you're VERY deep underground, you don't need heat vents in the first place. Being underground is actually *good* for your populace as it acts as natural thermal insulation. In point of fact, in a town called Lightning Ridge in Australia (a mining town inland where temperatures can soar) there are some homes that are effectively excavated out of the ground, underground homes if you will, because of the thermal insulation provided. Given that it doesn't often rain out there you can protect your entrance from rain pretty effectively so it works. But, I digress.
The point is, that if you live in a cave that is fairly well insulated, you have a natural heat source with you; body heat. In point of fact, in Stockholm, the [heat generated from people in Central Station](https://www.bbc.com/news/business-12137680) is redirected to heat office buildings, reducing their heating costs by up to 25%. In an ice age, you probably don't want to vent away any of that heat away at all.
Your bigger problem is in fact oxygen. Your heat vents are going to double as air vents, allowing air to circulate through natural fissures in the rock formation of your underground habitat and back through the vents, allowing for fresh air on a constant basis. Closing those vents is more likely to cause the air to go stale, leading to a buildup of CO2 but at the very least thinner oxygen levels over an extended period.
Personally, if you're going to shut the vents for an extended period, try to get some plants growing down there; I don't know the tech level of your colony but if they have artificial lights I'd be growing as many plants as I can down there to freshen the air and re-use the detritus all those people and animals are going to generate, if you get my meaning.
[Answer]
Look at what happens when miners or speleologists get trapped underground with no supplies: lack of oxygen is the main risk for their survival.
Death by starvation happens in weeks.
Death by dehydration happens in days.
Death from lack of oxygen can happen in hours or even minutes, depending on the amount of air contained in the environment when the trapping happens.
The temperature of a closed environment where human metabolism is the only heat source cannot get higher than the body temperature, (as soon as the environmental temperature is higher than the body temperature the energy flow will revert) so the environment is not going to turn into an oven.
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**This question already has answers here**:
[What aspect of planet Earth must be changed to prevent the industrial revolution?](/questions/143852/what-aspect-of-planet-earth-must-be-changed-to-prevent-the-industrial-revolution)
(19 answers)
Closed 4 years ago.
I have a fantasy universe that has magic but I still try to make it the most scientifically accurate I can. However, how can I prevent the Industrial Revolution? This world is medieval, and it needs to stay this was for a long time, at least a couple thousand years. However, a society always evolves technologically: what can I do to stop that from happening?
The magic in this world works by crystals, they emit a powerful energy that can be manipulated. They are also very rare, and a small crystal is already very powerful.
To the top answer, I want a solution that can incorporate magical evolution, but has a way to stop or delay the industrial revolution for at least 3000 years, and at least one of the main causes of the delay or impediment of it needs to be magic.
[Answer]
# You need cotton spun? Abra cada... Oh you need it all spun. Let me research and get back to you.
Magic manipulation is just another science. The more time and brains is spent on it the better it can be manipulated.
Now for your world to stay delayed (other sciences do not advance) for a few thousands years I would suggest that all great minds of the world throw themselves into Magic.
Think of it as a brain drain from other sciences. This would not stop progress in other sciences but it would slow it down considerably.
To slow it down some more I'm going to throw elitism into the mix. Your magic users see themselves as above everyone else and seldom uses magic to explore the other sciences. They rather spend all their time researching their crystals to see how they can make: their levitation cloud go 1 m/s faster; Shoot a bigger fireball; mend a broken bone; ...
Over time the amount of achievable advancements in magic would be limited by the stunted growth of the other sciences (Need lasers to improve the crystals resonance) and great minds would start to diffuse into other sciences.
For reference of evolution of magic:
1. Some stones seem to affect people. (Faster, Stronger,...)
"This is gods doing. We must all listen to god. Throw away your man made tools and pick up gods voice. It will allow you to achieve more"
2. Melting these stones with a flux gives a glob that is "probably" more potent.
"The interaction between the forces of the gods will decide who is worthy. Who dare use a sword."
3. Shape of the byproduct greatly influences what the affect is.
"The face of god can be revealed as we try to mold it."
4. Processing these stones gives a glob that is more potent than the normal stone.
"Melt gods stone with pure white marble. Then wash with water from the sea mixed with a dogs liver."
5. Complex shapes can now be cast perfectly. Complex shapes are designed by researchers in Magic and can now store multiple functions (can cast fireball and/or levitation).
6. Components. Crystals are now built as components and combined to make more powerful spells. Think of placing multiple crystal in-line on a staff.
7. Magic scientists have come to realize there isn't just one crystal but in reality it's the interaction between 5 unique crystals. Concentration of elements of each crystal and environmental conditions when the crystals form as one is now where magic scientists are.
I can keep going but at one point we can simply say that a lack in technology in a different discipline will halt research in magic.
As long as we do not achieve a technological plateau in the field of magic I do not see an industrial revolution. I see a magical revolution followed by an industrial revolution.
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**Remove fossil fuels** A lot of the industrial revolution was only possible thanks to fossil fuels being burned to power steam and other engines. Even today we struggle to replace them with much more advanced technology. If in your world they did not exist at all this would slow down the industrial revolution quite a bit.
**Smart people are mages** So in our world smart people often become scientists or engineers but this wasn't always the case. At one point in time smart people became clergy instead and focused their energies on religion rather than science. In your case the people smart enough to invent technology are instead all trying to figure out magic and so technology is much slower to develop.
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## Make Magic More Commonplace
If you make magic rare, then there will be plenty of people looking for ways to gain power, and if magic is hard to come by, then machines are the solution. Even without steam power (as suggested by Eric), wind and water power can go a long way towards [powering the revolution](https://en.wikipedia.org/wiki/Edmund_Cartwright#Power_loom).
So the solution? Make it unnecessary. If a gem can be acquired for something a merchant can afford that makes your carriage run without a horse, why would anyone invent a car? If another gem can power a golem who will sew incessantly, people are much less likely to look for a mechanical solution to the problem. The more accessible these are (your cornerstore mage, for instance), the less likely you'll have people looking for alternative solutions, and the longer the tech innovations will be delayed.
Now, you do run the risk of pulling an Inverse Clarke: "Any sufficiently advanced magic is indistinguishable from technology." If you have a sewing gem for a clothing merchant, they're going to be interested in getting more. If you're a sewing mage, you're going to want to find a way to make more gems quickly and efficiently. This is likely going to start looking like an assembly line quickly. But it won't look like the ones we saw in our own Industrial Revolution.
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You might also check how other places avoided the industrial revolution for a long time:
China reverted both to agriculture and to isolation, stunting it at a near-industrialised level for a thousand or so years.
Europe was slowed down by religious fanaticism. Until competition from the Muslims forced the Christians to adapt. And even that was a slow process until Protestantism broke the monopoly of the church.
Africa was apparently a little to aggressive for industrialisation: Every attempt to hoard the necessary resources would quickly be met with a war lord who wants to take them over. Among other similar issues. Whereby outside powers did their best to help such tendencies. How about a little Venice-like country trying to keep everyone down by supplying war lords with weapons, selling drugs and other such backhanded tactics? You may call it perfidious mini-albion...
The Americas developed far slower because they were isolated. So make your continents smaller and more remote from one another, and everything develops much slower. You can do that after they reach your desired level, if you don't want them too different, for instance through a sudden rise in sea levels.
The Holy Roman Empire was always far too conservative, split and legalistic to have any kind of positive development (similar to the EU today). Give the whole world a central bureaucracy, and it will stay very unproductive...
Many European states made laws against factories because they didn't like the pollution with ashes from the coal furnaces. They were quickly overrun by their more industrious neighbors, though.
The Muslim world seems to have deteriorated through more and more strong-man ideology, after their intellectual elite concentrated in Baghdad and the Mongols eventually cut their heads off.
And so on, and so forth.
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I was wondering about the feasibility of France maintaining a total war against the nazis in WWII following its disastrous military defeats in June 1940. Would it be possible for the bulk of the French Home Guard to retreat to Colonial territory, then grow the ranks with colonial troops (like the Tirailleurs, but larger in quantity).
I was envisioning the formation of a Colonial Army in Senegal, recruiting every able bodied native male of fighting age.Then, with the help of the British navy an American lend lease weapons and supplies, they could invade Italy, then destroy their weak armies and begin the struggle to retake their homeland, possibly using captured Italian troops as cannon fodder. The Senegalese fighters would be motivated by promises of French citizenship after the war.
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**Yes, and that was in fact the plan.**
The Battle of France was lost due to an improbable amount of disastrous coincidences, from multiple poor political decisions by many Allies to German battle plans falling into Belgian hands driving them to do something very stupid (the Ardennes gambit) to very bad (and in one case, probably treasonous) decisions by some French generals to the British general ordering the BEF to run like panicked chicken towards Dunkerque right when the French counterattack would have crushed the overextended German forces...
But even after all that, France still had plans to continue fighting. The idea was, give up metropolitan France - apart from maybe the Alpes, it could simply not be defended with what little forces were left - and keep fighting with the resources of the Overseas Empire, especially North Africa.
Already in WWI, France had largely drawn from its colonial empire for soldiers to send to the meat-grinder of the Western Front as soon as it became apparent that they needed more men. Unlike British or American forces, the comparatively lower racism level allowed Home and Colonial troops to fight alongside well, and war propaganda even helped build the image of the vaillant colonial forces. To the point that to this day, the Tirailleurs Sénégalais are still remembered in France. This time, given how fast the disaster unfolded, there was basically no time to send colonial forces back, however, but the colonies were already on war footing, and ready to defend themselves - which they later did with success, in fact, though against the British (before switching sides to Free France - yeah, the whole thing was kind of a mess).
150K French soldiers had been evacuated from Dunkerque, and those would have been sent to Algiers to be reorganized and rearmed. Parts of the French Navy were already in North Africa, the remainder could complement them, go to British ports or even be sent to Indochina. There were already colonial troops mobilized, and looking at WWI, many more could be raised as needed - and that's without talking about the volunteers that would have left France for French North Africa and take up arms under a legitimate fighting government.
While industry would have been a problem, reserves would have been enough to go by until US imports started to make the difference, as well as building new factories there to an extent.
The French Navy would have probably been enough to shut down the Axis in the Mediterranean, possibly with ships to spare. This would have freed the British up for the Atlantic, and considerably accelerated the fall of Italy - though a naval landing would still have taken years of preparations. (Historically, most was either stuck in France and later scuttled by its sailors instead of letting it fall in the hands of the Nazis, or murdered by an early British sneak attack while the sailors were, in fact, in the middle of scuttling it themselves, so it was not much of a factor on either side later.)
France had possibly the best mountain troops of the entire war, some very well trained pilots and one of the greatest (and the most underrated) general of both world wars at the new head of the military, once they had, like in early WWI, fired the incompetent generals they had let taking things over because of politics.
At this point, they decided that they needed to give someone emergency dictatorial powers to see the crisis off without being bogged down to politics. After all, if it worked for the Romans, it should work for them. So they picked the Lion of Verdun, a legendary general of the previous war and respected by friends and foes alike. What could go wrong, right?
Well, it didn't always work for the Romans, and the guy they chose was very old, loathed politicians in general, was and too easily influenced by the local fascist strain. Which is why this plan *spectacularly* backfired, with the new government saying fuck you to the British, let it burn to democracy and more or less switch sides to the Axis and make a mess of things like you would expect from Mussolini copycats.
So yeah, totally believable, except a believable scenario would never have gotten far enough for the Allies to actually loose the Battle of France.
But you know how it is, the studio had said that the bad guys should win, and they were writing by committee against a deadline, and we all know how those scenarios turn out.
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**No, it's not feasible.**
Colonialism and expansionism had waned by this time, and the reality is that most 'colonies' were already starting to see themselves with a new national identity, even if they were friendly with their colonial masters. Australia is a classic example of that insofar as it was a (more or less) independent nation and certainly supported the British in WWII, but also had its own battles to fight in the Pacific Theatre.
Senegal certainly *could* have been in a position to support the African campaigners against Germany (although its troops would have to cross the Sahara by land to do it), but given the U-boats, the chances of getting that many troops into France from external sources after 1940 weren't that great.
Extending French citizenship as a carrot sounds very much like the French Foreign Legion in whatever form it took in WWII (I don't know their history offhand), so to some degree this was already attempted but I don't know on what scale, or how successful it was. The fact that there wasn't some massive army of hundreds of thousands that changed the tide of the war in France tells me though that it probably wasn't *that* successful.
On top of that, you have to remember that even with all the French Colonies in Africa and the Pacific, there's a limit to the support they can provide in Europe for exactly the same reasons that larger nations like Australia were limited in their capacity to support Europe; they had their own theatres in which to either fight or avoid the conflict, even if they had numbers they could spare.
It also pre-supposes that Nazi tactics were set and wouldn't have adapted to new circumstances. If Nazi intelligence suggested a groundswell of uprising throughout Africa, their panzer tanks would have been built in even *greater* numbers and would have controlled more of Africa to prevent that from happening.
In such a case, Senegal and other French colonies would have focused on the threat before them, not on the protection or liberation of France.
Would some colonists have gone over to France to fight? Sure. Australians (for example) were in Europe as well as the Pacific theatre and Papua New Guinea; they were also in Africa where the famous Rats of Tobruk stood against the Nazis. But, Australians were not abroad in numbers that could turn the tide by that single virtue, and that's despite the spending of nearly 45% of the nation's GDP on the war effort in the first couple of years of the war; something that was never going to be sustainable over the long term.
So, as I see it, here are your scenarios;
1) The French take all or most able bodied men of fighting age from their colonies to the European Theatre, effectively bankrupting either themselves or the contributing nations (or both) and leaving those contributing nations open to their own attacks
2) The French take those men that the countries can *spare*, which increases their numbers but not by amounts that can make a meaningful difference, especially given the attrition rates the troop carriers would have suffered if the Nazis knew what they were up to
3) The French ask the colonies, who say no, and just push for independence a few years earlier than they did.
As a final point; the Nazis under Hitler's leadership had already transformed Germany into a production powerhouse by the start of WWII; this is important because a good part of the reason why they were so successful in Europe was that they had the manpower and industry to prosecute the war, and other countries didn't. Just remember that all those men that you gather from the colonies - they have to be paid, fed, supplied with weapons. These are things that you can only do if you have a strong economy in the first place and France under occupation would not have been able to shift the funds it needed to the colonies to raise such an army even if it wanted to. Without that, all you're left with is patriotism, which Given that Senegal (and many other African Nations) declared their independence less than 2 decades after the end of WWII, I don't think that was in steady supply among the colonies for the motherlands.
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This possibility has been extensively discussed, explored and simulated in the "Fantasque timeline" : <http://1940lafrancecontinue.org/> (the forum is very interesting).
With two books covering the 1940-1942 period (you can read them from the site).
It's only in french, but I think the original forum was in english.
This alternate history doesn't primarily focus on indigenous (senegalese or others) soldiers but more on the will to keep the fight despite the fall of France. In brief, the french colonial empire *can* fight the axis more efficiently than the Free France from our timeline. Not alone of course - UK and USA will still be the main war contributors - but accelerating significatively the fall of Italy and delaying Barbarossa.
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i think the promise of French citizenship is not enough to fight the wehrmacht. simple as that.
actually its a historical fact that germany attacking france and england destroyed their colonial intentions around the world. hitler even mention this on a speech. "we dont have their colonies". you have to consider that almost all countries in ww2 were racist. the U.S was in the middle of the apartheid !! france, england, the USRR were racists too. of course no one mention this...
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So I am writing a Sci-Fi novel where humans are currently spread out over 440 Star systems ( ~ 2000 Light years). There has been several breakthroughs in Automation technology and all manual labor jobs are done by bots. Humans are only needed to supervise and work in certain service industries (Therapy, Writing, Acting etc..)
So I am having a hard time justifying a large population. In fact, my calculations are currently giving me less than 1 billion people. What would people do in such a society? Does a large population even make sense? ( Large meaning in billions)
I thought about having a large military (Occasional conflicts with aliens) but even that would not require billions of humans.
PS: There is no FTL travel, Only FTL communications. There are Stargates (Discovered from ruins) which are used to go from system to system.
Edit: The people do not really need to work to survive. Agriculture is fully automated and can easily meet the demand. If a family is just trying to meet basic needs then one person probably only needs to work once a week ( One person in a 4 member family). Yet there are things like spaceships which are very expensive and would need decades of income for an average person (For the cheapest shuttle). Real estate varies by location. Real estate on a space station is vastly more expensive than a planet.
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**Your large population could exist without justification, if your story needed it.**
Consider retired persons. There are millions of them in the developed world. There is no particular need for them - they are living because they were born, grew old and did not die. Many help younger members of their families, but otherwise they spend their time with hobbies, socializing, watching sports and other such leisure pursuits.
If you want a big population in your [post-scarcity society](https://en.wikipedia.org/wiki/Post-scarcity_economy), you could model it along those lines. It sounds pretty nice, actually.
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Your population will depend on your society's view on family and children, and economic conditions which help or hinder having a family and raising children.
If most work is automated, how will people earn what they need to survive or be comfortable? Are people poor because there's no work and they're dependent on government handouts? Are people rich because they're living on trust funds established by ancestors generations ago?
If people are safe, free, comfortable, possessed of ample living space, and they have cultural values which promote families, they'll have children. If they can spend all day at home with their families, they might have four or six children instead of two or one. That could increase your population.
Like another poster mentioned, older people living longer will increase population, and also lower infant mortality rates will increase population. Advanced medical technology could allow people to live active productive lives much longer than in reality, and it could increase fertility.
Colony world governments could incentivize having children to build up the labor force. Tax breaks, bonus payments, land grants and social rewards could all contribute to a higher birthrate over time.
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it would depend on the society structure.
Does it make sense to justify all of those people in a purely capitalistic society? Yes and No.
* Yes, The service industry litterally explodes as humans having copious amounts of free time work 2-days a week and have 5-days a week of social time in restaurants, theaters, theme-parks, etc...
* No, every job is a standardish 40-50 hour work week. The excess labour is consistently on social security and the political landscape collapses as the population actively revolts and impedes commerce even dismantling the automation.
The essential feature is to provide income for everyone to live off comfortably or ensure that those people are too focused on surviving to care that the rich have unlimited production or are incapable of mounting a significant threat to that production.
A society may make this a given. The automation is the peoples property and everyone gets a portion of the production as their right. Some of the production is directed toward state activities etc. Those who wish to provide non-automated services may work in the hopes of acquiring time-shares of the automated production. These would include acting, politics, teaching, etc... The worker might only work 1 day a week or for 1 week in every five. People wishing to use these services would pay a portion of the time-shared production to them. Products could be done similarly by allowing the inventor to receive a portion of the production time-shares spent by an individual in acquiring that specific product.
Alternately society may manufacture meaningless work to force everyone into a job. The society can certainly afford this as the high-levels of automation ensure that the state does not have to play nice with the people.
Another society may in fact leave 99.9999% of people in subsistence life-styles with all of that automation going to the rich/state.
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The way to a large population is simple, and it even happened before on earth.
Earth's baby boom was in part the soldiers returning home from ww2, but another factor that people overlook is the increase in living standards that people had also led to a higher birthrate for a good time after the war even with widespread birth control. If your peoples are wealthy, have high living standards, lots of space and short work hours, they will get bored fast and start reproducing. It does not make sense for their to be a low pop if you have your people living high on the hog and not having a lot to do, as supervising a drone system should not take all day unless something goes really wrong.
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The large population might well by a hindrance rather than something that needs justification. There are too many people than there are jobs, but only because nobody has figured out a way to cut the population down.
In this case, all that automation is required to support the population, not the other way around. The majority of people might be unemployed, but surviving off some form of welfare.
Perhaps the government has tried to reduce population growth, but failed. There could have been schemes like China's one child policy that have failed, and so society is forced to bear the burden of all these unnecessary people.
I would expect plenty of social and economic issues as a result.
This situation lends itself well to any number of dystopian futures. See the [Earth](http://Earth%20%7C%20The%20Expanse%20Wiki%20%7C%20FANDOM%20powered%20by%20...%20expanse.wikia.com%20%E2%80%BA%20wiki%20%E2%80%BA%20Earth) in the Expanse for an example of one.
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As two other answers mentioned, retired people and large families could lead to a large population, automated labour or not. And you mentioned manual labor is automated, but with the possibility of large families, you could reason there need to be educated individuals or unions to educate the children and do administrative work. We're talking several stages of education: primary school, high school, various universities, etc.
Then as for retired people, you need medical personnel who would care for them - doctors for diagnostics, controlling therapy and such.
Another reason could be that your colony is something of a resort or haven for education, or something that would incentivize people to move to this particular colony. If it's a resort, there is administration, real-estate work and so on. Lots of coordination.
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Starting in 541–542 AD, the Plague of Justinian and a series of subsequent outbreaks killed between 13-26% of the world's population. The plagues were caused by *Yersinia pestis*, the same microorganism that would cause the Black Death in the 14th century. However, each subsequent outbreak during this period was less deadly than the previous; likely due to the propensity of pathogenic organisms to adapt in such a way that they actually don't kill their host!
My question is this: What mechanisms exist that might have made a subsequent outbreak of *Yersinia pestis* more virulent and more deadly that those that preceded it?
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Make the incubation period longer.
Traveling in Ancient/Medieval times was slow. A person infected with bubonic plague only had an incubation period of 2-5 days (1-3 if the plague was pulmonary). After that, the disease killed its host in less than 72 hours. There wasn't much time to infect other people and that is why quarantine more or less worked and the cities (specially the ones with good naval communications) were more affected.
By making bubonic plague less "effective", you increase the possibilities of contagion. Mountainous remote populations (like the Pyrenees) aren't safe anymore.
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I'm not convinced that your assumption that the plagues were less virulent over time because of pathogenic evolution; I think it's more to do with the evolution of the host. This is the same problem we currently have with anti-biotics and pesticides; the organisms that are *not* killed by them have a form of natural resistance, which (because of the mass extinctions of those organisms without that resistance) gets propagated through the rest of the species pretty quickly.
Ultimately, the humans that survived the plagues in the days of Justinian, and the Black Death of the 14th century were more likely to be resistant to the pathogen, which means subsequent outbreaks are going to be less effective.
THAT SAID;
One way to do it is to have 2x pathogens, each of which exploit an aspect of humans that serves as the resistance to the alternate pathogen. Let's call one the black plague and the other the white plague, for simplicity.
So; you start with the black plague in Justinian's time. That wipes out most of the population with the lowest resistance to it. The survivors breed through several subsequent generations, and then in about 2 centuries, the white plague hits. It specifically targets that part of the genome (or a biological consequence of it) that serves to give resistance to the black plague, so it's very effective. BUT, many out there still have a resistance to the white plague (which means a weakness for the black plague) and then survive, interbreed for a couple of centuries before the black plague hits again.
The white plague has effectively *selected* weakness to the black plague, meaning this time it'll be more devastating. The advantage (if you want to call it that) to this situation is that you can use a leapfrogging of the pathogens so that each sets up the human race to be hit even harder by the alternate plague.
Eventually (and hopefully), you'll find some human mutation of the human genome that makes a human resistant to both, but in the first instance, this type of leapfrogging pathogen is what would make each turn of the plague more devastating, at least for a millenia or two.
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**First lets fix this:**
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> likely due to the propensity of pathogenic organisms to adapt in such a way that they actually don't kill their host!
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**This is unlikely and flat wrong with respect to the black plague.** Microbes generally don't evolve to be less lethal. The microbial world is fairly simply, they do whatever works to reproduce more effectively. Caring about where their nutrition comes from is about the furthest consideration conceived by their short existences.
Immune systems in a similar respect are equally simple, they kill whatever tries to grow where it shouldn't. In many illnesses it is not actually the pathogen itself that kills the host but the immune systems amplified response to the foreign intrusion that ultimately kills the host. Fevers aren't caused by a bacteria they are an immune response in an effort to kill the bacteria.
This brings us to why subsequent outbreaks of a pathogen are less devastating in ancient populations. Previous outbreaks killed off the immunologically weak members of the populace while surviving members passed on both resistant genes and antibodies to the next generation. So in subsequent outbreaks the pathogen is now dealing with immune systems that are more versed in how to deal with the pathogen. This results in both less fatalities as well as less dramatic manifestations of trademark symptoms.
**Now for your actual question:**
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> What mechanisms exist that might have made a subsequent outbreak of Yersinia pestis more virulent and more deadly that those that preceded it?
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**Virulency:**
Pathogens can evolve certain changes in their structure that make it more difficult for white blood cells to identify them. This can increase the time between which a pathogen reaches a criticality needed to infect other members of a species and the time at which symptoms present themselves. Similarly, the pathogen can also evolve structures that make it more transmittable like being able to survive in an exposed environment or sticking to surfaces.
**Lethality:**
As stated before, simply existing can cause the immune system to kill itself. By being identifiable to the immune system but unkillable the immune system can amplify and amplify till it kills itself. Though that isn't the only means, like any good domineering organism, generalization is key. Being able to spread, adapt to different conditions, and exploit new resources is the key to success. For pathogens this means being able to conquer different tissues/organelles. Encephalitis is condition caused when an infection has compromised the brain. This is one of many means where an infection can directly kill the host as it eats away at brain cells eventually terminating the very controls that keep the body moving.
**The challenge**
To be worse all *Yersinia pestis*, or any pathogen really, has to do is evolve traits that enable some of the above outcomes. This is generally hard to achieve when the host population is concurrently adapting to its changes. This brings us back to the first point and highlights this cyclical process of adaptation and why the first epidemic is worse than subsequent outbreaks, because the first one is new and unchallenged. I do now want to point out that just because the pathogen appears less deadly does not mean it is.
**Did It Become Cuddlier?**
HECK NO! If you understand the fact that the bubonic plague still exists today and actually look at plague maps of Europe and Asia over time you might notice What is reported as 3 different plagues isn't necessarily 3 different plagues but really the same plague just evolved each time. See if you pine over maps of Europe, Asia, and Africa the black plague (or some variant of) is always present after the first epidemic. What happens is the local population becomes immune to it preventing it from spreading. Similarly while it is suppressed by that immunity it is learning how to counter it, until finally it does in which case the new and improved form spreads again.
To be even more clear, it never became weaker. From what I've seen the mortality ratings of the Asian, African, and European variants never seem to cull more than 25% of the population. That is until the Spanish Conquests of the New World. The native Americans had never once before been exposed to the disease so it's no wonder that it and other experienced diseases managed to rack up death tolls estimated as high as 90% of the indigenous. Now to be fair it is not definitive whether it was bubonic plague, and or smallpox and or some other pathogen that led to such a number or what the exact number really was. Do bare in mind that an entire empires (that spanned many modern day countries) fall coincides with the Spanish Conquests with Spanish suffering nowhere near the same percent in casualties.
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I'd love some science advice and facts for this question:
If they use wind power to bring up water from the ocean in the day time and spray it on prevailing winds going into land (i.e. 10-15 km from the coast using 200m high fountains), can they make it rain more in arid regions? What weather control can be done by bringing up water from the sea?
Here are some maths (probably wrong):
1 Kilowatt-hour lifts 1 m3 by 100 meters,
An average 5MW output wind turbine can generate 10 Gigawatt hours per year and costs a million dollars.
An average wind turbine can therefore lift 10 cubic kilometers of water every year by 100 meters.
For a billion dollars, Australia can therefore lift 10,000 cubic kilometers of water into the air and perhaps send 100 cubic kilometers of water vapor into sky above Australia.
So, if humans can atomize that much water into the atmosphere every year, for regions like Australia and the Sahara... Can't we give them a lot of clouds and rain? Essentially, wouldn't that easly humidify the coastal air to 100% year-round and generate huge masses of humid air which would cause major rainfalls?
NaCl is about 60 grams, H20 is 18 g, Air averages to 29 g, I found that salt vapor doesnt travel very far from the coast:
[](https://i.stack.imgur.com/MpxZx.jpg)
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Rather than windmills, look at solar towers to send evaporated fresh water high enough into the atmosphere to generate rain: [Getting large amounts of water to the Australian outback](https://worldbuilding.stackexchange.com/questions/85818/getting-large-amounts-of-water-to-the-australian-outback)
As many people pointed out, salt would be a real killer for the project. The other factor which should be taken into account is the need for the water vapour to rise high enough to actually form clouds. If it is only being pushed a few hundred metres in the air, you are more likely to be creating clouds of fog rather than rain clouds. Pumping the vapour a kilometre into the air will ensure cloud formation, and allow the rains to fall inland.
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I might as well post an answer, because there are many different things I want to address about this issue.
Firstly, as I mentioned in my comment, salt isn't exactly good for plant growth. Secondly, salt is hard to remove once it’s been saturated into the land. Using salt water to to create clouds is going to generate large areas of simply unusable land because there is no way to remove the salt without digging up all the dirt and processing it. You can't even wash it out, because that salt will flow through the rest of the land and river systems making it extremely hard for plants to grow.
Secondly, pumping water is expensive. What you’re talking about isn't 10 or 20 km. Its 100s of kilometers of piping to get the sea water there in the first place. Believe it or not, the population of Australia is pretty much entirely focused on the coast, so getting the starting pipes past the cities is going to be expensive. As you go farther out, it gets worse, because it’s harder to get equipment there, it’s more costly in terms of pumping the water and every now and again, people will have to do maintenance checks on all the equipment. If any of the salt water leaks, you've basically killed off the usable land in that area, so you need to check it pretty frequently.
Thirdly, (not sure on the exact stuff behind this, so skip this if you want) salt water is a lot more corrosive than normal water. With normal water, you just get rust due to oxidization. In salt water, you have a number of electrolysis reactions which is going to accelerate that corrosion effect even faster. Since you’re also pulling the water from the sea, you need to make sure it’s free of living creatures, small particles and so on, so that any coatings you apply don't get scratched off and the pipes don't get clogged from barnacles and what not growing on the insides. So you can't just plug a pump and pipe into the ocean and call it a day. You’re going to need to build an entire filtration plant next to the sea.
Now the solution which solves most of that would be to filter the salt water, pump the fresh water inland and use it. The biggest problem is it’s ridiculously expensive to do that compared to just pumping water out of aquifers or water tables. You can treat the water with chemicals, filters and/or boil it. In each case it consumes a ton of materials and energy to generate the water required and a ton of waste materials that will also need to be treated (filters don't last forever, you make new ones, or pump water through them backwards to unblock the holes). So you have an expensive process with an expensive distribution network when there is a cheap solution under the farmers’ feet. Desalinization is important; in Sydney we have a desalinization plant. It just hasn't been used for a while (and is costing us money), however it’s a backup plan in case things get bad, not the solution to a natural problem.
Now I finally get to the turbines. Simply put, turbines aren't going to be efficient in spraying water everywhere. They do look like giant fans, and a misty breeze on a hot day is great but they have some issues. Turbines need to be situated in areas with high winds. That isn't going to be the most of Australia. Turbines are spread pretty far apart and heavily dependent on the wind; you’re not going to cover a lot of ground using turbines... you'll get patches of growth but not the lush green fields you would imagine. The Sun is hot and so is the ground. A fine mist of water isn't going to last long enough to get deep into the ground. You might think to yourself, but I mean heavy rain, not a fine mist like those spray bottles, but simply put, there is no way to move that much water. (Think of the firefighting planes. it looks like a lot, but farming takes a constant supply over a huge area, so just because you can water your entire backyard with your hose, doesn't mean it works for a national park.)
The best thing we can do is shoot pellets into clouds to make them rain. Nature does a far better job at moving water around the world than we could ever do. Sometimes it’s too much and you get floods, and other times there is too little and you get droughts. Changing nature can cause unintended consequences (a butterfly effect) that might not show up until many years or decades later (take global warming). If it rains in one area, another area where it should have rained is missing out.
[Answer]
Look up the [Marine Cloud Brightening Project](http://www.geoengineeringmonitor.org/2018/04/marine-cloud-brightening-project-geoengineering-experiment-briefing/) (or 'silver linings')
>
> The Marine Cloud Brightening Project (MCBP) aims to test the premise that spraying a fine mist of sea water into clouds can make them whiter, reflecting more sunlight back into space. The MCBP, a form of Solar Radiation Management (SRM) began with indoor development and testing of spray nozzles, and is moving toward a land-based field test in 2018, followed by ship-based tests and a larger-scale sea test later on.
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One of the unknown side effects is how this would affect rain fall.
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> The effects of large-scale testing of MCB geoengineering techniques are unknown, but could affect rainfall in the immediate area, as well as creating unpredictable changes to regional weather patterns at a distance. For example, marine cloud brightening in the Pacific and elsewhere may lead to reduced rainfall in the Amazon basin.
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[Answer]
Can we not just do what someone said earlier. Huge solar arrays that super heat seawater then use silver particles to induce rain. Kill two birds with one stone. Drop the sea levels. Get more water on land. Even just topping up water levels would be useful. There always seems to be this massive con. Huge problem with these ideas. Oh it costs money. Yeah so do wars and bailouts and giving the rich all this money. We always manage to pump money into things we need. We need this. Put money into it.
Edit.
Ok so I was thinking about it yesterday. Maybe use graphene to filter seawater. Use solar and wind to heat the water or seawater to turn a steam turbine. Using drones to follow those steam clouds and seed them over the country. Pump night and day using any energy that is harvested throughout the day. Could also just pump water into fine mist spray to help it get into atmosphere as well.
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[Question]
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## Scenario
* Medieval technology and warfare.
* There's a war between two sides of a continent.
* Said Continent has a large mountain range crossing the whole land.
* At the north, there's and opening to this mountain range, large enough for lakes and some small villages to occur (not inhabited anymore, due to war)
* The passing is some kind of valley, natural space between the mountains.
* Small groups of people can cross the mountains through other ways, but the death risk and scarcity prevents a large army from doing so.
* Crossing the passage to the other side unseen is impossible for any army, the area is heavily patrolled.
* Both forces are similar in strength.
* The war is ongoing for a long time, let's say around 60-80 years.
## Question
Is it plausible to have an ever growing economy around the military camps? Nearby villages providing food and supplies and living a relatively ordinary life there even near the borders? There's an constant risk of death and pillage and rape for anyone that stays near the single battle front. Would that make people want to stay as far as possible or the needs of the military would be more important?
P.S.:I can add more details if requested, but I tried not to make this too broad.
[Answer]
# Not only is this plausible, it's inevitable
The thing about wars is that they cost money to wage. There will always be people who will want to profit from this situation.
1. At the beginning of the war, there will be a lot of caravans to supply the army, but this is going to be among the most expensive ways to supply them.
2. Industrious people will see the opportunity to set up shop to supply the military. That military will be incentivised to protect those shops, farms, blacksmith's, brothels, etc. because that is how they get their day to day needs met.
3. Initially it won't be anything like a normal village but as it grows over decades, this will become more than a village, but a town with rudimentary fortifications and a strong city watch (probably partnered with the military).
4. As decades pass this place will be among the largest cities in the kingdom.
[Answer]
Yes, there must be a growing economy somewhere nearby, but it would be simple mass production.
Soldiers stationed at a stable battlefront need tons of provisions. That's one reason why in medieval times armies were disbanded after the end of the war or wandered further around to find new victims to plunder.
There have to be a lot of farms around with fields and husbandry to grow enough food for the soldiers. There have to be craftsmen around to produce cloth for uniforms, weapons and ammunitions and whatever you need for your daily life. There would definitely be a bunch of brothels around.
But all these farmers and workers want to avoid being attacked themselves, so they put up their homes as far away as possible, but within range of the barracks and camps. The best distance is what you can barely cover in one day with a loaded wagon drawn by one horse.
**To sum it up:**
* You have the mountain pass as center point of interest.
* A little ways behind that is a semi-circle of millitary barracks and camps. They include workshops for weapon smiths.
* Inside the barracks or right beside them are small inns with stables for merchants and farmers bringing provisions.
* You would find brothels in close proximity to the barracks.
* In a wide semi-circle around the barracks you have farms and small villages with workshops.
* A spiderweb of merchants roads would spread out from there to deliver more provisions and materials that cannot be harvested in that area (like metals)
[Answer]
**Only if it is a professional and no mercenary army.**
As already mentioned in the comments in the Hundred Years War and especially in the Thirty Year War the armies plundered and pillaged everything in their way. Especially in the latter war the civil casaulties where horrific as Central Europe lost nearly a third of its population.
Especially bad were the marauding mercenaries as they had no fix income and no discipline. The imperial troops where a less harsh as they had at least some pay and sometimes the generals tried to recompensate the farmers for their losses.
Another thing to keep in mind is that in the Middle Ages there were only small contingents of standing armies. Most troops were recruited or conscribed in the case of war. So maybe the king of your medieval country has some kind of conscription system where a part of your population is used for the army whilst another part can tend to their home and fields and after a time some soldiers were released from their service and in change new recruits come from the villages. This would also reduce the risk of looting as nobody wants to raze their own village.
If a proper military discipline is maintained the scenario would likely be like Elmy's answer already pictured.
[Answer]
# If the war continues...
Wars cost money. Soldiers need to be paid and people who get paid spend money. The two nations will be taxing the populous to support the armies at the border. Money will be flowing north along with provisions and equipment. The money will lead entrepreneurs to found various support systems for the off duty soldiers, brothels, taverns, etc. It would be the classic boom town except instead of drilling for oil, they drill for blood.
The people making money off of the soldiers will have their own needs, leading towards more general production of clothing and other less venal luxuries.
Of course any army of size deployed forward, will need a long and impressive tail, so shipping and support for the shipping will be a major economic component. Cartwrights, farriers, teamsters will all abound. There may be some secondary development as the returning carts, won't want to deadhead and will look for something to ship back south even if the profit is only marginal.
The city supporting the army will grow off of taxes as long the war progresses.
A real world example is the small cities that build up around US overseas military bases.
[Answer]
Depends?
Economic growth has lots of variables. Trade, commerce, population growth, technological advancement. These can be seen by the opposing kingdom, which CAN attack you whenever they want.
For example, you're inventing a car, then a catapult is fired and the munition fell right on top of your car, along with the drawings you have done. Or the person with the answer on how to cure common cold suddenly got shot a an arrow during a night raid.
Progress will be particularly slow and small compared to a kingdom in peace. A warring kingdom will focus its treasury on weapons, armors, food and cloth. While a peaceful kingdom can focus on other things, specially things that can increase its treasury, leaving the army an asset but not a priority.
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I'm worldbuilding a species X that doesn't have males. All members are females. X reproduces sexually using males from related species Z.
There it combines the shared chromosomes but passes unique chromosomes unchanged, like Y chromosome in humans.
Like if lions only had lionesses who breed with tiger males but the offspring is always a lioness.
Is my idea plausible? Even better if there's something similar in biology.
[Answer]
What you describe is called **gynogenesis.**. The offspring has only DNA from its mother, but conception requires sperm from a male of a related species. The sperm triggers the egg to develop but DNA from the sperm does not become part of the offspring.
<https://www.researchgate.net/publication/234149168_The_Evolutionary_Ecology_of_Gynogenesis/download>
[](https://i.stack.imgur.com/iKRrY.jpg)
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> Gynogenetic females have to obtain access to sperm, but males do not
> gain from matings with gynogens...
> Theoretically it would be easiest for gynogens to obtain sperm from
> males that release sperm for external fertilization. However, several
> gynogenetic species have internal fertilization. Females require
> intimate contact with males to obtain sperm. The Amazon molly uses the
> two species that were involved in the hybridization, P. latipinna and
> P. mexicana (Schlupp et al. 2002). A third host species, P.
> latipunctata, has recently been described (Niemeitz et al. 2002). In
> this case, the third host may have made secondary contact with the
> Amazon molly only recently.
>
>
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I think I have read of lizard species that do the same thing - all the lizards are female but to conceive they need sexual behavior - either with a male from a related species or from another female of their own species.
The linked article sets out the evolutionary conundrums that the existence of such species pose.
[Answer]
**The Term You are Looking For is Called Sexual Dimorphism**
If two members of a species are capable of interbreeding (which some are) the offspring is not going to end up as one or the other, but a mixture of both known as a hybrid. If the hybrid offspring is reproductivley viable and these two species reproduce exclusively by breeding with each-other then very quickly both distinct species will become extinct and the hybrid will become a new species.
Sexual Dimorphism is where the male and female specimens of a species are significantly different but still a member of the same species. Sexual Dimorphism can be as mundane as differences in color patterns exclusive to gender, or so extreme that the two almost appear as a different species. An excellent example of this is the Angler Fish. When biologists were first recovering specimens they noticed that all of them were female. After some intense study and examination it was discovered that the "parasites" found attached to some of the females were in fact the male member of the species. If ever viewed separate even expert biologists would have assumed that the parasitic males were from a different species. Here's an example of a female and a male.
**Female**
[](https://i.stack.imgur.com/V6mt2.jpg)
**Male**
[](https://i.stack.imgur.com/olYeM.jpg)
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Okay, so I'm an engineer who's been tasked with transforming Mars. I don't need to make it perfect for people to be able to walk around free with no life support. But I do need to make life, especially plant growth possible.
I know that by doing things like adding large quantities of methane to the, currently painfully thin, Martian atmosphere. Melting/sublimating much of the ice caps I can temporarily create an atmosphere, and once this manufactured atmosphere raises the planetary temperature by about 6 degrees centigrade, frozen carbon dioxide released by the planet's surface will create a generally self-sustaining/warming atmosphere.
The problem is, my best calculations only have this chain effect lasting for about a 100 years or so before my atmosphere starts to degrade and disappear again. If Mars is going to become humanity's second home, this atmosphere needs to last thousand if not millions of years. I don't want to have to "juice" the atmosphere every century or so.
I help keeping my atmosphere for thousands of years, warm, as cost effective as possible, and preferably with science/technology currently known, or likely to be developed/discovered within the 21st century.
I've tried these questions:
[Using temperature to contain an atmosphere?](https://worldbuilding.stackexchange.com/questions/70898/using-temperature-to-contain-an-atmosphere)
[Maintain atmosphere on moon using global warming](https://worldbuilding.stackexchange.com/questions/96137/maintain-atmosphere-on-moon-using-global-warming)
[What can we do to Mars to give it a survivable atmosphere?](https://worldbuilding.stackexchange.com/questions/4147/what-can-we-do-to-mars-to-give-it-a-survivable-atmosphere)
But they're not enough. Please help!
[Answer]
**I have great news, it won't be a problem for a long time.**
See article on terra-forming, where a table is presented for how [long atmosphere can be kept by the Moon, Mars](https://worldbuilding.stackexchange.com/questions/3361/would-it-be-possible-to-terraform-the-moon) (and other planets and moons).
The lightest important gas to maintain has a half-life of 64.5 million years, i.e., you will lose 50% of the water-vapor in the atmosphere over that span. Other important gases stick around even longer, N2 408 million years and heavier gases like O2 and CO2 even longer. Top off with some replacement gases every 10 million years and you will be good to go until the sun turns Mars uninhabitable.
Almost forgot, your methane greenhouse gas kick-starter half-life is 40 million years, so that won't be a problem either.
When you hear people says Mars is too small to retain an atmosphere, there is an understanding that it can't retain an atmosphere for billions of year - a few million years is no problem.
I did not double-check his numbers, but I assume they were based on current Martian temperatures, post terraforming I would expect you want warmer temperatures, but this change does not shift the half-lives that dramatically.
[Answer]
**I have bad news...**
The only thing that will naturally keep an atmosphere on a planet is gravity.
If you enter the realm of [Clarkean Magic](https://en.wikipedia.org/wiki/Clarke%27s_three_laws), then you can play games like an electromagnetic-ish planetary shield, useful for keeping the bad guys out, but also useful for keeping the atmosphere in. Of course, when you open the gate to let ships in and out there's a palpable *Whoosh!* but such technomancy would work.1
But, insofar as we can predict a realistic future, terraforming Mars will include domes and lots of subterranean habitation.
**EDIT:** Curiously, we've had two basically identical questions (coming at the problem from different points of view) at nearly the same moment. Go check out my answer to ([Could I use a series of magnetic asteroids to create a magnetic field for mars?](https://worldbuilding.stackexchange.com/questions/123747/could-i-use-a-series-of-magnetic-asteroids-to-create-a-magnetic-field-for-mars)) and the comments to the answer.
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1 *Just in case someone's tempted to suggest genetically modified planets that produce copious amounts of oxygen... plants need a source of oxygen to begin with. On Earth, it's all the carbon dioxide in the atmosphere. I don't know enough about Martian soil to know if there's enough bound oxygen in the soil that it could be released by properly modified plants into the atomsphere for long-term effects. But if you think about it, your depleting a limited resource. It's not self-sustaining.*
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I also think there's not enough gravity to hold a decent atmosphere. Unfortunately? "stable" systems tend to hold their state pretty well. Especially really large ones. And Mars is definitely stably dead.
Fortunately, a continuous source of energy *may* be able to keep a sustained hands-free atmosphere *if* we were willing to tweak it's composition. We need only small percentages of the atmosphere to be react-able for humans. We can fill some of the other "air gaps" with an inert chemical. It would seem to need to be a gas but could even be a solid or liquid. But it needs to have *many* oxygen atoms in its structure. From there soil bacteria would break it down into O2 that we could breathe much like the Nitrogen Cycle. But in order to not escape the thin atmospheric layer we would need a method for it to recombine using energization from the Sun in the upper atmosphere. Whether there was a chemical that catalyzed the reaction or whatever. It would need to be heavier than normal air and stable as well. You'd need a similar cycle for any other light gases. The biggest questions are how dense do you need to go. And if the life present is recognizable at that point with the increasing density.
There's a likelihood that developing a whole host of solutions for all the inevitable problems of terraforming something too small is not worth the effort and that you should just pick a different target.
But maybe that's the point? Maybe this is a generational test of engineers. To make Mars one step better than was possible before. If so then just getting a basic cycle of *anything* to live should be doable. I think you can get certain bacteria to survive on the surface of Mars, provided enough ionization sheilding. So first doable task is magnetism or metallic clouds or something.
Or you could crush Mars. Denser planets have stronger gravity. So you could have an atmosphere... downside is there's also a stronger gravitational *gradient*, so you'd feel heavier in your feet than your head.
[Answer]
IMHO one method to prevent atmospheric loss is to put a roof on the atmosphere. That would prevent both loss due to the solar wind in the absence of a magnetosphere and loss due to air molecules and ions with speeds higher than the Martian escape velocity.
Percival Lowell believed that Mars was gradually loosing water and drying up due to loss of atmospheric light gases. And he believed the Martians built a vast canal system to manage their remaining water resources. But apparently Lowell never thought about more long term solutions to the problem.
Lowell published three books with his theories: *Mars* (1895), *Mars and Its Canals* (1906), and *Mars As the Abode of Life* (1908). At that time interplanetary space was known to be a vacuum.
So 19th century fictional space ships would have to be airtight so the air wouldn't leak out and the passengers die. Some examples include:
*From The Earth To the Moon* (1865) Jules Verne.
*Across the Zodiac* (1880) Percy Gregg.
*A Journey to Other Worlds* (1894) J.J.Astor.
*The War of the Worlds* (1897) H.G. Wells.
*Auf Zewi Planeten* (1897) Kurd Laswitz.
*Edison's Conquest of Mars* (1898) Garrett P. Serviss.
So Lowell could have read about artificial airtight enclosures with breathable atmosphere inside and deadly vacuum outside, and could have extrapolated the idea to hypothetical Martians preventing loss of the Martian atmosphere with giant artificial airtight enclosures to keep the breathable air inside. Or even eventually uniting them into a single giant worldwide artificial airtight enclosure to keep the entire Martian atmosphere inside. But apparently Lowell never suggested that could a long term strategy for the Martians.
So hypothetical future Human terraformers of Mars might not release gases into the wild and unconfined Martian atmosphere and instead use imported steel from iron-nickel asteroids to build large airtight buildings in the Hellas Basin and fill them with gases derived from asteroids with high contents of light elements. They would expand the buildings upwards and sideways to eventually fill the Hellas Basin and spread outwards to eventually cover all of Mars.
Or possibly the roof(s) could be supported by the air pressure differential in the lesser gravity of Mars. If the Martian atmospheric roof is far enough above the ground and the roofs of buildings, there may be space for aircraft to travel from place to place. Presumably pilots would be instructed to never get too near to the roof and risk making a hole in it, and if necessary to deliberately crash their vehicles rather than risk making a hole in the roof.
A breathable Martian atmosphere confined by an airtight roof above it could have a much smaller total volume and mass than a wild and unconfined breathable Martian atmosphere. And the original thin and almost useless Martian atmosphere would remain above the roof.
The thin original Martian atmosphere is still thick enough to decelerate and/or burn up meteors. in fact, because of the lower surface gravity of Mars squashing down its atmosphere much less than that of Earth, Mars has air thick enough to heat up and decelerate meteors at a higher altitude that Earth does.
So an original and unmodified Martian atmosphere above the hypothetical Martian Roof would be thick enough to stop the common grains of dust and pebbles. And no atmosphere possible on a terrestrial planet, not the atmosphere of Earth, nor the atmosphere of Titan, nor even the atmosphere of Venus, would be thick enough to stop a Chicxulub or Vredefort sized object from impacting and causing an extinction event.
If the hypothetical Martian Roof is transparent it could have coatings to cut down the intensity of ultra violent ultraviolet radiation to levels comparable to those at Earth's surface, or whatever level seems desirable. Thus those coatings on the hypothetical Martian Roof could serve the function of the ozone layer in Earth's atmosphere.
Since the Martian colonists would have to live in airtight enclosed habitats for centuries or millennia while terraforming Mars, they would lose the idea that a proper planet is one that is habitable outdoors, and become used to living in places that are only habitable indoors. Thus the idea of making all Mars an indoor world would be acceptable to them if it reduced the total terraforming time by a few centuries or millennia.
Putting a roof over the entire surface of Mars would be an incredibly vast project, but terraforming Mars is itself an incredibly vast project. But both projects would require finite and calculable amounts of matter and energy and thus would be theoretically possible.
[Answer]
Adding a magnetic field would certainly HELP a lot.
A great deal of atmospheric loss on Mars occurs due to the solar wind stripping away its atmosphere, needless to say this is less of a problem with a magnetic field. This magnetic field would best be made by means of large electromagnets, which will require constant maintainence and power but are easily doable for a civilisation conolising Mars.
[Answer]
M. A. Golding suggested a roof in his answer, but I am going to scale it up. A civilization capable of doing the industrial infrastructure necessary to terraform Mars is likely to have access to a lot of energy and material. The energy comes from the Sun, and is delivered to Mars by platoons of mirrors orbiting Mars and focusing sunlight on the surface. Depending on the size and focus of the mirrors, you can warm up areas to release water and trapped gases from the permafrost presumed to exist under much of the Martian soil, to literally boiling out the oxygen trapped in the red iron oxide that covers the surface.
Water, nitrogen and organic materials can be delivered from the Asteroid belt, Titan and even cometary materials captured from deep space. A very sophisticated operation would be in place to deliver the space born materials where they were needed, and control the speed of impact to prevent blasting gasses and materials back into space.
Once you have this level of industry, it would be almost trivial to "top off" the project with a planetary sized "bubble" made of diamond to hold the atmosphere and warmth inside and slow the leakage of the atmosphere into space by geological ages. Diamond is simply a form of carbon, and artificial diamonds can already be made on Earth today, so finding a source of methane or other carmon bearing materials in the asteroid belt, the atmosphere of Titan or cometary materials gives you the starting material to create films of diamond to create the bubble.
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So I my question is quite simple. With current technology or technology that we are likely to gain this century would it be easier for Lunar colonization programs to develop wheeled vehicles or walkers for simply economic purposes, ie. for mining, traveling, and transporting goods. On top of that what are the programs more likely to try and develop despite what advantages on vehicle may have over the other. Also, Treaded vehicles are allowed. Now I am NOT talking about the far future, I am limiting the scope of this discussion to the end of the 21st century. Speed of the vehicles doesn't matter.
[Answer]
The answer to this is the same as it is for Earth; wheeled vehicles (in the main) are far more energy efficient and versatile than either tracked or walker style vehicles.
How do we know this? Cars. Cars are not tracked because it's far more efficient to create wheels in the form they currently exist. Tracks increase friction with the ground and can be useful where there is a lot of mud or other conditions that will bog a wheel with low surface area contact with the ground, but the Moon doesn't have that problem and the Apollo program got along perfectly fine with the rovers they sent up there.
Walkers generally don't exist on Earth (and wouldn't on the moon) because they are problematic from an engineering point of view, would struggle if one of their legs got 'bogged' (sunk into a weak spot of dust, for instance), and are inconvenient to operate as you need some way to get to the main pod that probably involves a ladder. They *may* have some strategic benefit in rugged terrain, but generally speaking your colonists are going to see such situations as edge cases. For transport and most light industrial purposes, wheels will be what they use.
The important point to note is that the lower gravity, lack of water and atmosphere, and general hostility of environment has (at best) a negligible impact on the physics of mobility, including things like energy efficiency, ease of maintenance, etc. As such, you can safely model what you do on the Moon by what we do here on Earth.
[Answer]
Astronauts found that the most efficient mode of lunar transportation was hopping.
[](https://i.stack.imgur.com/bMbKp.jpg)
<https://www.shutterstock.com/video/clip-27575665-astronaut-jumping-on-moon-landing-earth-background>
It stands to reason that augmenting this mode of travel would make the most sense. **Lunar colonists will travel by pogo-stick**.
[](https://i.stack.imgur.com/lO8Oe.jpg)
<http://pogo.hivefly.com/vurtego-v4/>
Hopping transportation offers many benefits. The need for traction is negligible, so reduced gravity and dusty / slippery surfaces are less of an impediment. The footprint of the pogo stick is small, allowing easy transit over rough terrain. Most forward motion occurs in the air, clearing obstacles. Bouncing transportation maximizes the use of human muscles in a low-G environment.
Motorized pogo-sticks could have electrical augmentation of the downstroke of the spring, allowing even more radical and long distance jumps.
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[Question]
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So if you haven't watched the film, basically there's this one character who suffers from a (fictional) condition referred to as “molecular disequilibrium.” As described by the character, it's a condition where “Every cell in my body is torn apart and stitched back together, over and over every day.” With said condition, the character can phase through solid objects and living beings at will. Basically she can quantum shift through space.
From what I understand, she had become intangible from a childhood accident but able to solidify her body if she stayed focus. Another character was trying find a way to cure her condition, developing some kind of quantum chamber to allow her to briefly stabilize and ease her pain.
This “molecular disequilibrium” is a concept that I'm interested in, especially because I wanted to apply similar condition where the cells are torn apart and stitched back together to a whole fictional race I'm currently writing. So I'm curious how plausible it is scientifically.
[Answer]
A 'condition where “Every cell in my body is torn apart and stitched back together, over and over every day.”' has a scientific plausibility of about zero.
Something that tears apart every cell in a body would totally destroy that body. This would either be an external force and applying that external force wouldn't be easy. If it was internal this is almost the equivalent of every cell exploding.
But whatever is necessary to stitch every cell in a body back together definitely requires an external mechanism. This isn't so much a condition as being massively processed to restore waht would have been a totally destroyed body.
Every name itself "molecular disequilibrium" sounds more like chemistry and in particular reaction kinetics. If it was, this would have nothing to having every cell ripped apart and put back together again and again and again.
If you want to have a population of people who can quantum shift through solid matter, just give them the ability to pass through solid matter and leave it at that. Don't decorate a story with what is easily recognizable pseudoscientific nonsense. Never try to explain more than you know. If you want them to walk through the walls, well they can, because walking through walls is what they can do.
[Answer]
While probably not Physically possible, there is precedent in Sci-Fi for something more or less along these lines. First off Ant Man and the Wasp (obviously), where the character is more or less in control of their condition, but the exact how/what they can do is unclear. However, if you're looking for some good, classic Particle destruction and Reconstruction, look no further than *Watchmen*'s Dr Manhattan. With the power to control all of matter, Dr Manhattan was described as "a walking atomic bomb," who was destroyed in an experiment involving 'intrinsic fields,' which is more or less analogous to the strong and weak forces that hold together atomic bonds. While it's unclear why Dr Manhattan has the powers he does, the experiment that gave him these powers renders him devoid of any illusion of free will, since he can see the past and the future, and does not experience anything as a "present." Heady stuff, and if you haven't read Watchmen, I highly recommend it.
That aside, there is research into these subjects, but they are still very shrouded in mystery. There's a relevant xkcd on the topic: <https://xkcd.com/1489/> - specifically the tooltip. The universe is a weird place, and *anything* is plausible. It's pretty unlikely anything like *Ant Man and the Wasp* will ever happen, but that isn't to say it can't happen.
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Highly implausible, even with magical pseudo science. This is clearly apparent as immediately after beginning to phase she should have simply phased through the floor to be embedded somewhere in the core of the earth. There should also be constant small explosions caused by the sudden vacuum caused by air flooding into the space she previously existed in and then dramatically increasing the pressure inside her body causing gruesome scenes of air trying to escape her body. So whatever science you use to achieve the affects the affects themselves almost certainly kills her.
Having seen the movie I can also confirm that none of the reasons given in the film would have caused the effects seen on screen. Though most would have killed her. Regarding "Every cell in my body is torn apart and stitched back together, over and over every day" this would not have allowed her to travel through walls to see why this is take all the pencils out of your pencil case throw them at the wall and reassemble them on the other side. As for "molecular disequilibrium" that could really meaning anything, a cooking potato is technically in molecular disequilibrium.
That being said still a great film and a great character, i'd advice using the same vague pseudo science in your story regardless of its unrealism.
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I think that the movie has provided us with a beautiful concept of quantum disequillibrium.....This can be related to Quantum Superposition as it seems from the movie. Her hands are continuously changing their coordinates in periodic fashion. Such an unusual motion can also be ascribed through wavefunctions, representing different states of the same energy.
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In addition to 'physical' barriers that your hypothetical creatures need to overcome, there's another side to this story, and that's the consciousness.
We know far less about it than we know about the Quantum world, but even then it's quite clear that any being with consciousness is more than just the sum of its molecules. For instance, our brain is able to retain even very long memories, but those memories do not reside in any single cell, but as a collective they're able to do the job just fine. And memory is only a part of our consciousness. What guarantee do we have that once taken apart and put back together, those individual cells would have retained the entirety, or parts of, our consciousness, and can seamlessly put it back together as well?
So, as the top answer says here, your best bet is to not explain this at all. Star Trek can teleport people, Wizards in the world of Harry Potter can disapparate, and so can people in most worlds in fantasy genre. You simply set the premise, you don't have to explain it.
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I have an idea for a power/ability, but I want to know if it would work like I think it would.
Basically, the person has the power to separate themselves into separate hive mind cells and join back at will. These cells can levitate and separate the molecules of other materials, denser matter is harder to break through.
But when they 'dust', would they lose a lot of heat energy, or would they lose heat through movement since they have immeasurably more surface area? I don't mean how can I fix this, just, would it happen? I kinda like the idea of a hero with a really strong power but using it leaves him shivering.
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They would be more vulnerable to any extreme of temperature
Let's look at two 1 kg dry bags of flour with an internal temperature of 37°C sitting on the floor in a room at 37C and minimal humidity. Now pour out Bag 1 and blow it around with a fan. The individual particles of Bag 1 will still have a temperature of 37°C. Bag 2 will also retain its temperature of 37°C.
Now take two new bags of flour, still with an internal temperature of 37°C, into a room at 20°C and repeat the experiment. The individual particles from Bag 1 will very quickly approach 20°C, while Bag 2 will be much slower to reach 20°C. It would be a matter of seconds I would think before the temperature would drop to below hypothermia levels.
Repeat the scenario again in a room at 45°C and the Bag 1 particles will heat up faster, while Bag 2 will take longer to heat up. As observed in the question, increased surface area will change temperature faster through conduction and radiation (convection is a bit iffy with the small particles), although see point 3 below.
However, there are three additional factors:
1. Evaporation - without some special mechanism to maintain the integrity of the particles the water in the superhero's body will evaporate away very quickly, resulting in the superhero reconstituting as a mummy. (Which could be a really scary, albeit fatal, ability to intimidate the bad guys with.) If the thought experiments above were repeated with wet bags of flour, the particles from Bag 1 in the 37°C scenario would cool instead of retaining their temperature and the particles from Bag 1 in the 20°C scenario would cool much faster.
2. Heat generation - a bag of flour is not a good approximation because human bodies are generating heat all the time. Maintaining a levitation field to keep all the particles together *may* mean even more heat generation, which could offset the heat losses from conduction and radiation. However, if this is the case then it exacerbates the evaporation issue and the risk of hyperthermia in environments over 37°C.
3. Non-interaction with other particles - if the molecules of the superhero's body avoid interaction with other molecules in order to pass through solid objects (implied by "separate the molecules of other materials" in the question) then convection and conduction are by implication not a factor and radiation is the only mechanism for heat transfer. This makes the calculation of heat loss quite different, as it would require calculating the black body radiation of each of the molecules of the superhero's body and summing these. However, if the levitation field is keeping all of the molecules close together (keeping the molecules as close together as if they were a solid) then many of these molecules will be radiating to each other, which makes the net radiation of the entire body approximate to the black body radiation of a normal human body. This raises the issue that if the molecules all remain very close to each other *and* do not lose heat through convection or conduction then the risk changes from hypothermia to hyperthermia - the human body needs to be able to dump some heat to its surroundings through conduction and/or convection in order to avoid overheating.
In short, heat loss is a factor that you can use to put limits on how long your superhero can remain in "dust" form without suffering hypothermia, but you need to ensure that the explanation of this power prevents death through dehydration as part of the process.
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They would lose heat when the cells dust, and the individual cells would be cold. When they come back together they would heat up, but not back to where they were to start.
But your entity can manipulate molecules. Compressing other molecules can make them heat up. While in his gaseous state maybe he works his power on other molecules to produce heat. Then he vampirically consumes this heat.
You could have him be stuck as a cloud of cold cells until he worked his power on some other stuff to warm him to the point where he can come back together. Maybe he has to use it on something else that is living...
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There would be a drop in temperature, but it might not be particularly extreme. If the cells are surrounded by still air, air is actually a pretty good insulator. I presume these cells are separated but stay in a relative "cloud" with a larger volume than the original form, so the increase in volume would create a relative vacuum between them. Air rushing in to fill this vacuum would heat up as it passes the outer layers of the cloud, and the temperature loss of cells near the center of the cloud would be less than the loss at the outer edge of the cloud.
The composition of the cells--and their environment--also makes a large difference in how well they could retain heat. Cells are made of mostly water, which transfers heat fairly well. This is why water cooled systems are more efficient than air cooled systems.
```
Air - h = 10 to 100 W/(m2K)
Water - h = 500 to 10,000 W/(m2K)
```
(from [wiki](https://en.wikipedia.org/wiki/Heat_transfer_coefficient))
So splitting apart in air would allow the cells to retain their heat much better than splitting apart in something with a higher heat transfer coefficient (such as solid metal or another liquid, which would induce rapid cooling).
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The jillions of single-celled organisms on Earth don't **freeze** when the temperature is above 0oC, so you should not expect the cells in your hive mind to **freeze** either.
When his hive mind cells reunite, they'd naturally be at ambient temperature, though, and that's a Very Bad Thing for warm-blooded creatures (except when ambient temperature is the same as body temperature).
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**Edit**: I've gotten some answers now, but many of them use Neolithic settlements as examples. I wish I had the archaeological know-how to analyze these settlements' technologies and economies and overlay it onto a Mesolithic setting should it fit the bill, but sadly I don't. I'd be grateful if someone could state whether these kind of settlements are possible with the level of technology I've selected (The Skara Brae suggestion looks the most promising at the moment, but more ideas are always welcome).
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The world I'm building right now is not meant to be historically chronologically accurate, so to speak, but rather "plausible" instead. It depicts conflict between a variety of Mesolithic tribes in a place based on what is now Scandinavia.
When I say Mesolithic, though, there are some technological differences between them and real Mesolithic peoples. For example:
* They use pottery for bowls and other containers
* There is warfare between communities
* They build boats made of hide with wooden frames rather than just dugouts
* They have their own religions
These are all elements that are only confirmed to exist in Neolithic peoples. However, they do not farm crops, make polished weaponry, or have pastoralism.
The last Neolithic element in these otherwise Mesolithic cultures is: some of them build permanent settlements. The earliest permanent settlements not based on agriculture, I believe, are the fishing villages of Neolithic Alaska that relied on the annual salmon run to maintain their permanent habitation.
Similarly, in my world, the permanent settlements are based on fishing. There are some built around rivers for salmon-fishing like the Alaskan ones, while others are found at the seashore, home to fishers and whalers.
Now, my question is: **If a community of Mesolithic people were to build a permanent settlement, with permanent buildings, based mainly on fishing, how would they do it? Is this possible with that level of technology and, if it is, what would the structures look like?**
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[Skara Brae](https://en.wikipedia.org/wiki/Skara_Brae), an early Neolithic village in the Orkney Islands, is possibly a good model here. It dates back 5,000 years, which sets it partway through [Northern Europe's Neolithic period](https://en.wikipedia.org/wiki/Neolithic_Europe). What is interesting here is that it lasted for quite some time - perhaps up to 500 or 600 years - and was inhabited by people who survived in a number of different ways over the centuries. Here are some key facts:
* The inhabitants, at various periods, fished, raised cows and sheep, and, possibly, planted some crops, likely later in the village's history.
* The dwellings are few - so far, only eight houses have been found, although it's possible more exist.
* The houses themselves were made of stone but also used [earth sheltering](https://en.wikipedia.org/wiki/Earth_sheltering) for additional protection. This may have eased the burden of construction.
* The inhabitants had advanced tools; they had stone furniture, doors and other amenities. Clearly, the houses were built to last.
I would argue that in terms of architecture and construction, the inhabitants of your village would follow the Skara Brae model, taking advantage of natural features to minimize construction but using stone to provide shelter against wind, snow and cold. This requires a serious choice of location. Many fishing villages utilize bays - in this case, the Bay of Skaill. You therefore need a bay or natural harbor, as well as locally-sourced stone. Assuming the community is small, it is impractical to transport stone any significant distance. Trees would also be ideal, so boats can be made on site, and rebuilt if they are destroyed.
Someone might make the argument that the group could opt for a [Neolithic long house](https://en.wikipedia.org/wiki/Neolithic_long_house) composed of timber. I'd argue against this (and the use of wood as a building material), for a couple reasons:
* These houses could hold 20-30 people, and were usually built in sets. This implies a not-insignificant settlement of perhaps 100 people or more, which would be larger than a village like Skara Brae.
* The long houses - and wooden buildings of any sort - would require relatively advanced technology in terms of tools and construction, which I doubt your Mesolithic people had.
* It takes a lot of planning and manpower to build these houses, and it seems inefficient given the level of technology available.
To get an idea of the sort of stone buildings I'm talking about, here's a photograph of Skara Brae, looking across the settlement. The houses were buried by natural conditions long after they were abandoned, but it is still notable that they were small and short, and did use [middens](https://en.wikipedia.org/wiki/Midden) for additional shelter.
[](https://i.stack.imgur.com/S2LWO.jpg)
Image courtesy of Wikipedia user current, under [the Creative Commons Attribution 4.0 International license](https://creativecommons.org/licenses/by/4.0/deed.en).
Additional structures exist outside the complex. Some are still buried; others were destroyed by weather over time.
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Almost all sedentary communities in the Mesolithic period, for example, the [Jomon people of Japan](https://en.wikipedia.org/wiki/J%C5%8Dmon_period), the people who lived on [the Baltic Sea coast prior to the Neolithic revolution](https://www.sciencedirect.com/science/article/pii/S0278416505000668?via%3Dihub), and [the various totem pole people of the Pacific Northwest such as the Haida people](https://en.wikipedia.org/wiki/Haida_people), were coastal fishing communities that supplemented their seafood diets with plants gathered near a coast. Several images of such settlements are shown below:
Some Jomon village images are here:
[
[](https://i.stack.imgur.com/FhEl5.jpg)
A Haida settlements in the Pacific Northwest ca. 1878 (via Wikipedia):
[](https://i.stack.imgur.com/0YoYf.jpg)
An artist's conception of a Baltic Mesolithic settlement:
[](https://i.stack.imgur.com/88F12.jpg)
Terrestrial hunter-gatherers sometimes assembled in rich hunting grounds on a seasonal basis for a matter of a month or two, but almost never had sedentary communities, because their prey either migrated or would be exhausted by staying in one place for too long. In rare instances, permanent structures were built by these groups as temples or gathering places that were probably inhabited only seasonally, the most famous of which is the late Mesolithic *Gobekli Tepe* temple in Anatolia, shown at an advanced stage of construction but prior to completion:
[](https://i.stack.imgur.com/yhNfn.jpg)
Also, where terrestrial hunter-gathers assembled in extended camps in the Mesolithic era, there was also often "proto-farming" in which wild type predecessors of crops (often grains and berries) and animals that would eventually become domesticated (especially bunnies and flightless birds) were actively encouraged and regularly harvested, but neither the plants nor animals experienced the genetic changes that would make them domesticates that were especially well suited to controlled horticulture and herding. Here is an artist's impression of a Natufian (Mesolithic Levantine proto-farming) settlement:
[](https://i.stack.imgur.com/voBWW.jpg)
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If they are familiar with pottery, maybe they would built clay huts or mud brick huts, but that needs a climate hot enough to dry mud bricks.
Around Lake Constance (and some other places too), there are some neolithic stilt-houses built by fishers which are made of wood, I visited them once, they look quite cool, so i would use those.
for more, refer to this: <https://en.wikipedia.org/wiki/Neolithic#Shelter>
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The biggest hurdle I see to the plausibility of the scenario you put forward is calorific sustainability, you've stated that the groups do not farm or raise stock, Scandinavia is a harsh place to make a living if you do raise crops and domestic animals, getting by on fishing alone would be brutal.
As to form I's expect any permanent buildings in that part of the world to be dry stone, possibly turfed over, probably using either drift wood or whale bone for roof beams where they weren't stone domes like those on [Skellis Michael](https://en.wikipedia.org/wiki/Skellig_Michael).
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[](https://i.stack.imgur.com/tCosy.jpg)
<http://100objects.ie/mesolithic-fish-trap/>
>
> It does not look like much: some small, smooth interwoven sticks
> embedded in the turf from a bog at Clowanstown, in Co. Meath. The bog,
> however, was once a lake, and the woven sticks are an astonishing
> survival: part of a conical trap used by early Irish people to scoop
> fish from the lake or catch them in a weir. Radiocarbon tests date it
> to between 5210 and 4970 BC. The delicacy of the work has survived the
> millennia. Nimble hands interlaced young twigs of alder and birch,
> gathered from the edge of dense woods that covered the land at the
> time.
>
>
> The people who made this trap were adept at using what was around
> them. They made circular, tent-like huts using saplings; they turned
> flint and chert stones into knives and other tools, but, as the trap
> suggests, this was as much an age of wood as of stone.
>
>
>
Your Mesolithic fishermen would be based in natural caves near a fishing site: a bend in a small river or a place where a river entered a lake, or maybe a brackish area connecting inland waterways with the sea. They would have augmented and built out the stone caves with wooden structures like this fish trap. They might have brought in fill from the surrounding area to level out interior spaces in the cave, maximizing usable area within.
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# Model them after Natufians
The oldest known cities, such as Jericho, were founded by the Pre-Pottery Neolithic people c. 10,800 – c. 8,500 years ago. They had agriculture. However, this was not their first foray into settled life - around around 15,000 to 11,500 years ago, the presumed ancestors of the PPN people, known as [Natufians](https://en.wikipedia.org/wiki/Natufian_culture), began living a settled life *without* the use of agriculture. (Well, they may have cultivated some plants in some of their settlements, but their diet was primarily wild plants and animals.)
Settled life without agriculture requires very specific ecological circumstances. Most non-agricultural people are nomadic because their food supply (or in the case of pastoral people, their livestock's food supply) is not available year-round in the same locations. However, the Natufians were fortunate enough to live in a highly fertile environment with very little seasonal change.
In the time between the Natufian and PPN culture, the climate changed, forcing the Natufians to resume a nomadic existence. However, once they figured out how to survive on agriculture rather than wild-sourced foods, they returned to many of their old settlements.
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## Nuke the Moon!
Earth's had it with the Moon colony's insubordination and independence efforts. The situation has escalated to a hot war. The [W90 nuclear warhead](https://worldbuilding.stackexchange.com/questions/108451/how-would-one-design-an-undetectable-nuke-to-hit-the-moon-with) is nearing the end of development. The scientists/engineers expect a yield of 6 megatons from the warhead. There is plenty of debate about exactly where the warhead should explode when it arrives at the moon.
One group says that a surface burst near the entrances to the colony would be enough to seal in the colonists and let them starve. Another group advocates for a ground penetrating warhead that will destroy the colony with seismic shock waves. All the primary infrastructure for the colony is buried for a variety of reasons. Earth's intelligence services are unsure the full breadth or depth of the tunnelling nor exactly how many entrances there are. Conspicuous entrances are visible but this doesn't preclude the existence of many other entrances.
**Which shall it be, a surface burst or ground penetrating warhead? Each approach has trade-offs.** Getting the warhead to the moon with minimal chance of detection has been solved. You just need to articulate which approach will be more effective and why the trade-offs are worth it.
The Earth leaders with nukes don't care about how the colonists die, only that they die. Survival of the moon colony's infrastructure for later recolonization is not a priority. If it's intact, great but that's not required. (We have a hot headed leader with their tiny fingers on the nuclear launch button. He has been offended.)
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Unless you are hoping to have the Selenites open the door and let you park the bomb inside, you are going to get no air-burst, for the simple reason that in the vacuum of space there is no air where to create a shock-wave.
You will get a nice EMP and the heat wave to warm up the sun scorched moon surface, but no mushroom cloud.
Your only choice is then to bury the bomb underground with a nice penetrator and let the explosion induce moonquake do the damage.
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Straight nuclear weapons in space are almost a waste of time. The energy release is in the form of a spherical emission of x-rays, which cannot be converted into other forms of energy in a vacuum. The massive energy release of a nuclear weapon on earth is from the x-rays impacting the atmosphere and converting it into a hypersonic plasma shockwave.
The other issue in space (or even on Earth) is the energy release is spherical, so the "inverse square" law takes effect:
[](https://i.stack.imgur.com/VFFFp.gif)
*Quick reference to the inverse square law*
What is needed is either to land the weapon for a ground burst (to transmit the shockwave through the ground to collapse the colony), or even using a penetrator to allow the bomb to explode under the surface for even greater effect.
Using the weapon as a energy source to "drive" effects is a [much better use of the energy of the weapon](https://worldbuilding.stackexchange.com/questions/108451/how-would-one-design-an-undetectable-nuke-to-hit-the-moon-with). Using the bomb to drive a monster [HEAT](https://infogalactic.com/info/High-explosive_anti-tank_warhead) or [EFP](https://infogalactic.com/info/Explosively_formed_penetrator) warhead allows the weapon to be orientated and aimed in space and fire from a distance. The energy is focused and a [metal slab](http://toughsf.blogspot.com/2017/05/nuclear-efp-and-heat.html) can be used to deliver this energy deep into the target.
[](https://i.stack.imgur.com/vUcRo.png)
*Velocity diagram of a HEAT charge being formed*
Since we are now talking about accelerating metal slabs or streams of liquid metal at 3% of the speed of light, small nuclear devices can deliver a massive blow against even a deeply buried target.
>
> The solution is the spaced NEFP. Its effective range is practically infinite. A 1 megaton warhead could propel a 2.7 ton projectile to 800km/s, while massing only about 3 tons. This projectile crosses the laser's effective range in about 30 seconds, gouges out a crater nearly a 100 meters deep and/or cracks the target in half with 2160 kN.m of momentum concentrated on a spot less than a meter wide.
>
>
>
It isn't clear that a 6Mt warhead will radically improve this sort of performance. Obviously a 6Mt warhead can drive a much larger plate and deliver more energy to the target, but it might be more efficient to send 6 1Mt warheads in a hexagonal pattern and deliver strikes which can collapse even deeply buried structures while also being dispersed across enough area to destroy separated structures.
Indeed, using nuclear devices as energy sources allows you to create a cloud of much smaller warheads, and use this energy to destroy surface mounted sensors and weapons systems in advance of several larger devices delivering EFP strikes against identified enemy strong points. Nuclear weapons can drive clouds of pellets at 100 Km/sec, star hot spindles of plasma at a fraction of the speed of light or streams of liquid metal at 3% of the speed of light.
[](https://i.stack.imgur.com/DrbhH.png)
*Cross section of an ORION nuclear pulse unit. A nuclear shaped charge weapon would resemble this device*
This allows you to target individual structures and ensure maximum damage to those targeted. You can also use this refined targeting to ensure the main living quarters are untouched to reduce collateral damage and provide a great propaganda victory for the attackers.
Edit to add:
One of the comments asked why "only" a 6Mt weapon. There is no actual upper limit to the size of a nuclear device. If we want to go "big" (and quite the opposite to my answer), the largest weapon I have ever heard described in a semi-plausible way is a 5000 Mt device. For kicks, it was required to reach Soviet missile fields in 2 minutes, meaning the massive 460,000kg warhead (at 11Kt/kg) would need to be boosted by an ORION nuclear pulse drive...[neofuel.com/inhabit/inhabit.htm#cheek\_on\_bomb](http://www.neofuel.com/inhabit/inhabit.htm#cheek_on_bomb). See also [worldbuilding.stackexchange.com/questions/60557/](https://worldbuilding.stackexchange.com/questions/60557/could-we-build-and-deploy-a-multi-gigaton-nuclear-bomb-with-todays-technology)…
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# Why not both?
If you can send one nuke, you can send two. Or Four. Or sixteen.
Arrange them so that they form a line upon arrival. The first one penetrates five hundred meters into the ground. The second one penetrates three hundred meters. The third one penetrates one hundred meters. They are synchronized so that they all reach their deepest penetration point at the same time.
The other bombs will arrive at their detonation altitudes at that same time as well. One bomb hits the ground, whereas others are interspersed at one hundred meter intervals.
Detonate all at once. That way not only you cover both use cases, you cover most variations for them as well. It would also send a message much more powerful than a single blast.
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# Seal their access to the surface
Assuming that you have access to plenty of these W90 warheads, and are willing to use them progressively over time, then you are best served by using them to destroy all surface emplacements. The reasons for this are two-fold.
# It is too hard to destroy what is under the surface
First, I assume that the Earth leaders do not have full schematics for what is going on underneath the Moon's surface. Furthermore, it would be pretty hard to get said schematics by any method other than human spies. The only reliable way to map underground caverns would be seismography from the Lunar surface, which I assume the Selenites would not allow. Without a detailed map of what is actually underground, it is hard to say whether or not your shockwave inducing weapons are going to have any effect.
Second, 6 MT is probably not going to do that much damage to underground structures. There is not a good way to compare vibration for various effects, since vibrations at different frequencies affects structures differently. You can say a nuclear bomb like North Korea's last test made a 5.1 magnitude Earthquake, but unless you specify frequency range, that says nothing about damage to structures.
That being said, I looked for damage to subway systems from recent Earthquakes in areas with subway systems. I found the [1985 Mexico City](https://en.wikipedia.org/wiki/1985_Mexico_City_earthquake), [1989 Bay Area](https://en.wikipedia.org/wiki/1989_Loma_Prieta_earthquake), and [2017 Mexico City](https://en.wikipedia.org/wiki/2017_Central_Mexico_earthquake) earthquakes. All three earthquakes caused service interruption due to electrical power outages, and the 1985 Earthquake caused extensive service interruptions due to blockage of surface lines due to debris. But in none of those cases could I find any evidence of damage to the tunnels themselves. I conclude that nuclear weapons are unlikely to cause extensive damage where powerful earthquakes have been unsuccessful.
# It is easy to find surface accesses.
These are lit up by their radiation signatures. The moon is cold, especially the sides facing away from the sun. There is effectively no way to prevent IR radiation leakage from a warmer subsurface area. This is basically a corollary of the "No stealth in space" thing.
# Ultimately, the colonists can always dig deeper
The moon is not as hot in the middle as the Earth, so the options for digging deeper are more apparent there than thy are on the Earth. If the colonists can build a completely self-sustaining colony, then they could theoretically just keep digging down out of the reach of your nuclear weapons.
But I find that hard to believe. More likely, the colonist depend on outside trade for *something* that they need to survive; materials required for food production, or generation of oxygen, or what have you. Cutting off whatever these valuable materials are will eventually doom the colony to a slow 'starving' death, no matter how deep they dig.
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**Closed.** This question is [off-topic](/help/closed-questions). It is not currently accepting answers.
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You are asking questions about a story set in a world instead of about building a world. For more information, see [Why is my question "Too Story Based" and how do I get it opened?](https://worldbuilding.meta.stackexchange.com/q/3300/49).
Closed 5 years ago.
[Improve this question](/posts/105887/edit)
A central part of my story involves a certain book that was allegedly written by the Devil himself. However, my protagonists are rational and skeptic people, they do not believe such outrageous claims (*extraordinary claims must be supported by extraordinary evidence*).
Is there a away to convince them, unambiguously, that the contents of the book are indeed truly and verily the words of the Devil?
**Note**: if it helps, feel free to replace "Devil" by any malevolent super-creature that is very unlikely to exist (Cthulhu, ...).
[Answer]
In the animé *Death Note*, notebooks exist that have supernatural composition and powers. Generally speaking, if a person's name is written in a notebook, that person dies.
These notebooks are usually owned and used by death gods, with pens or pencils that come from their death world. In one episode, forensics specialists from Japan's police remark that they have analyzed the ink from some of the writings in such a notebook, and they could not determine what the ink was - presumably because it was literally something from another world.
You could use the death notes as a source of inspiration. Your devil book **will not convince skeptics unless it is able to do something "supernatural"**. Among us, there is a saying:
>
> Extraordinary claims require extraordinary evidence
>
>
>
**Minor edit:** I had not seen that you had the very same sentence in the question itself.
Some ways in which the book could display interesting phenomena. You could use one, or a combination of as many as you want:
* It cannot be destroyed by any simple methods (such as tearing or fire);
* It rewrites itself in one way or another;
* Everybody who comes in contact with it dies, no exception;
* It describes future events with enough precision to negate accusations of being right by being vague, i.e.: rather than make prophecies along the lines of "a star will fall from the sky and strike upon the glass city", it should say something like "asteroid [astronomical number of an asteroid yet to be discovered and numbered] will impact upon [name of country] on the 3rd of August of the year [year number] of the Lord, harvesting [approximate amount of dead people] souls".
* It teaches spells or incantations that actually work.
Etc., etc.
It will be more convincing as well if spectography cannot determine the composition of the paper and ink.
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St. Augustine talks about evil as a total lack of virtue. In Christianity, there is no 'dark energy', the Devil cannot create *anything*, he can only exploit a person's free will to turn them away from God & Virtue. I'd suggest reading CS Lewis' Screwtape letters.
How does the book convince your characters that it is legit? That's up to you. Probably a spell that works. Keep in mind, though, that spells only work because God or a demon makes it work. No human has inherent magical powers in Christian theology.
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[Question]
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So, given the following assumptions and starting criteria:
* The colony ship comes from a human culture that is about 100 years advanced from the present.
* The amount of initial colonists are around 5,000 people.
* They bring with them many specialists and libraries of information about known technology.
* They have enough supplies like clothes and food, and heavy equipment to bootstrap a town and provide it with the essential facilities like clinics, schools, farms, governments, labs, simple manufacturing, etc.
* They have power sources with long-term fuel sources, such as fusion and solar, that will last for ~100 years before they have to build their own electrical source.
* They have survey equipment to begin mapping out resources.
* They have two satellites to help them find resources.
* Their form of transportation for supplies are heavy ground vehicles.
* All vehicles are electrical.
* The relative spread of resources is similar to Earth, but let's say that their landing zone was selected due to a relative abundance of basic metals and farmland.
* There is no resupply from Earth.
...how long might it take this colony to become fully self-sustaining such that they could create their own vehicles, supplies and technology on the level of the stuff that they brought with them and perhaps even build their own ships to begin exploring the stars?
[Answer]
~1,000 years
By modern technology I am assuming you mean enough to support a full space program, which means you need a very large country worth or people, which is a lot of infrastructure. Building and maintaining modern technology requires tens of millions to hundreds of millions of people, many of them simply maintaining the other people. That is really going to be the limiting factor, the number of people and specialized labor you have.
Human populations can grow at about 2% a year under ideal conditions (max ever recorded) so using A=Pe^(rt) you are looking at 380 - 500 years at minimum.
But realistically you are looking at 1,000 year as a safe minimum because growth will be anything but ideal without modern infrastructure. Plus this assumes a single mindedness you will never achieve with humans, the population estimate should probably be larger since people will tend to form factions which will create a lot of redundancy.
handy [compound interest calculator](https://www.calculatorsoup.com/calculators/financial/compound-interest-calculator.php) to put in your own numbers.
EDIT : had to recalculate, the online calculator is using "R" and not "r" which makes a big difference.
[Answer]
## It depends, but approximately 350 years is a good estimate
As @Burki mentioned in a comment, the big hindrance will be how long before they have enough people. They will also need time to set up infrastructure and simply build things up, but with technology 100 years more advanced than ours and without many of the current problems built into our world that are slowing us down in some ways that will be child's play next to simply getting enough people.
While an approximate, I will say that "enough" is roughly 100,000. That is somewhat arbitrary of course, but that is enough to constitute a genuine city with diversified labor and a full culture and enough they could readily spare another 5,000 to go to another planet and repeat the process.
There are many factors that go into population growth rates, but if we assume they are similar to current earth rates, we can expect the population to double roughly every 70 years. More details on the math as well factors that could influence are [here](https://arachnoid.com/lutusp/populati.html) among other places.
For 5,000 people to grow to approximately 100,000 - 120,000 at current growth rates would take roughly 5 doublings or 350 years.
This obviously is doing a lot of rounding and making a lot of assumptions, the biggest ones are:
* That there are no enormous obstacles they need to overcome before getting down to really building civilization. If they need to really terraform an inhospitable world first it will be very different.
* Their population grows at roughly current earth population. If they decide to put effort as a society specifically into population growth it could go substantially faster. Conversely if they decide to deliberately limit population growth for sustainability reasons or other reasons it might take much longer.
* That 100 years worth of technological advances from today is enough to give them the necessary space travel and make building infrastructure somewhat easier than current, but not enough to radically change their capabilities from current standards in a relevant way.
[Answer]
The answer really depends on two things, in my opinion at least; one how much extra-planetary material are they extracting? Two what kind of extraction equipment are they starting with?
The first can give a colony access to materials that are relatively scarce on planet and also may allow them to import material to planet in quantities that are impossible to mine efficiently. The example that is always bandied about is a moderately large Iron Type asteroid AKA a cubic mile of iron-nickel alloy, bringing that into orbit and chopping it down as needed could supply a colony with all the raw metal it needs for decades.
With the second point, extraction equipment, this is a case of the quality (meaning type) of equipment rather than how much they brought along. There are two types of mining machine "pickaxes" and "nanotech". In this case "pickaxe" refers to any piece of equipment that need human labour to produce and human labour to maintain, no colony is going to have the numbers and secondary equipment to support such equipment over the long (generational) term, nanotech is any extraction equipment that can take raw rock and produce finished goods without any human intervention, so called "Cornucopia Machines". [Cornucopia Machines](https://en.wikipedia.org/wiki/Molecular_assembler) are self-repairing and self-replicating.
If you're talking Cornucopia type extraction then the day the colonists land they're already fully self-sustaining and have access to any form of technological artifact in the machine's database, which is probably everything invented before they left, and possibly in-flight updates. Barring elemental bottlenecks (where a particular substance is very scarce relative to industrial demand, like Neodymium in [*Lost in Transmission*](http://www.wilmccarthy.com/lit.htm)) you can have anything you want or need at the press of a button.
On the other hand if you're talking about hardrock mining their resources with existing, and irreplaceable, "pickaxe" equipment brought from home then they may never reach the level of their homeworld because they're going to wear that gear out before they have the labour pool and production equipment to replicate it and they'll never have the resources to do the work. They'll have to fall back on older methods, possibly as far as the stone age, and then progress anew. This is because, as has been mentioned in comments and answers, below a certain level of population the [specialisation](https://en.wikipedia.org/wiki/Specialization_(functional)) and [division of labour](https://en.wikipedia.org/wiki/Division_of_labour) to maintain and advance technological material culture breaks down. When it does cultures don't stand still, they revert, one of the ways around this in fiction is reduce the entire [production chain](https://www.britannica.com/technology/production-chain) from raw ore to finished consumer goods to the domain of a single, generally small, device divorced from human labour. Those devices are the Cornucopia Machines.
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**It can be 500 years, or it can be 5**
The big unknown here is how our technological level would advance in the next 100 years towards the beginning of the story.
At present, the major limiting factor is colony's population. To achieve a full technological cycle, a colony would need to implement extraction of raw materials, their processing, manufacturing, and possibly recycling. And, to get somewhat to the parity with Earth, it has to be done in dozens of industries. Even if the colony has all parts and materials to build mines and factories for everything - from iron to computer chips, it wouldn't have manpower, even closely, to operate all of those facilities. It would need a population of at least 1 million to cover all the bases, and, without resorting to cloning, it would take a couple of hundred years to get there. Consider then that they, realistically, are not going to have all parts and materials to build their infrastructure - thus they would have to build everything from scratch - and my estimate is doubled to 400 years. And then, the Earth would not likely stand still for 400 years, so the colony would need to catch up to the new advances, which make the whole process even longer, so I would look at 500 years.
However, it does not have to be that way if AI/robots can come to the rescue. Imagine that starting tech level is high enough that we don't need a single live human to operate a factory. In that case, population is no longer a limiting factor. The colony can build any facilities at will, and have them operational in no time. So, if they can put robotic builders at work, in a few years the colony would have a full spectrum of mines and factories, all working with minimal supervision. Mission accomplished.
P.S. My minimum estimate of "1 million" assumes that the colony is run military-style rather than as a free economy. Also the assumption is that 5,000 starting colonists are all in working and childbearing age, and generally are in good health.
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It heavily depends on the evolution of the social stratification and relationships with motherland.
A colony such as the one envisioned is bound to have a very different development compared with "classic" colonies (e.g.: Greek colonies or European "conquests" in New World).
Main differences are:
* Long distances might mean low-to-nil contact with motherland.
* No "aboriginal" population to trade/submit.
* Much easier settlement due to modern building technology.
* Possible unanticipated problems with local flora/fauna/chemical composition...
* Better beforehand planning.
* Lower fertility rate.
* Higher health security and thus longer life expectancy.
What follows is in the hypothesis of an almost completely isolated colony.
In this condition it is highly likely the colony will start up working like a single "corporation", with a trustee board, and a strict hierarchical control structure.
This structure is bound to break apart sooner or later, as colony grows, giving rise to (almost) separate entities. The exact moment and mode of the breakdown will determine if and when the colony will be able to match motherland technological level.
Best scenario is:
* Corporation holds together for several generations.
* It starts several far-located sub-colonies.
* Mother corporation grants complete independence to sub-colonies as soon as they can manage it.
* Trade is encouraged on an equality basis.
This (somewhat) resembles political structure of Magna Grecia colonies.
In this scenario it's likely the Colony should be in position to start R&D "departments" within a few generations and thus be able to "keep up" (somewhat) with motherland. Stabilization could be achieved in very few centuries.
OTOH worst scenario (barring utter colonization failure) is:
* Original Corporation tries to keep everything under strict control.
* Sub colonies are set-up as dependent branches with no autonomy.
* Violent rebellion ensues with collapse of central authority and a centrifugal flight of low-tech splinters (far-west colonization).
* Small settlements are left t their own devices wit no central coordination and little-to-no trust with "original colony".
In this scenario technology is going to fall hard and no resources for research are going to be spared for a long time (till population is in the tens of millions ballpark). This would follow our own world development model where large industries and associated technology improvements is fueled by "numbers"; i.e.: if you haven't a (very) large customer base. This might mean a couple of millenniums will pass without radical technological improvements.
Note: in the last scenario it's very likely colony will *never* get in par with motherland (unless communications get better) because in the meantime motherland technology would have improved and catching-up is not going to be easy.
[Answer]
# 0 years (technology), or 350 years (industry)
The US was founded in ~1620 depending on your definition of founded. A bunch of colonies started popping up at that time. It took ~150 years for the colony to declare independence.
Meanwhile the mother country was going through an Industrial revolution. Even though the mother country was advancing quickly, the US was at least tied for [second in technological advancement](https://en.wikipedia.org/wiki/Second_Industrial_Revolution#/media/File:Industrialization_per_capita_1750-1900.svg) through the late 1700s into the 1800s. By the 1890s, you could say that the US had caught up; and by the start of WWI the US had the world's most advanced automobiles, tire rubber, steelmaking, etc. While the US never really 'passed' the mother country, it also never really lagged that far behind, technologically.
As far as industry goes; the US passed UK in [population](https://upload.wikimedia.org/wikipedia/commons/4/4c/PSM_V76_D387_Population_increase_in_the_us_and_europe_1800_to_1900.png) in the 1860s; and the German Empire in the 1880. Its per capita industrialization was already ahead of Germany's; and passed the UK by 1900. So it is safe to say that by around 1880; or 360 years after the first colonies arrived, the US was the foremost industrial power on Earth.
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**Background:**
I've come up with this strange world where everyone has a dependent of sorts. Like a child but they live within another dimension. Think like a game avatar but they live their own lives and make their own choices (largely). The Guardians, will look over each of these dependents (really need a better name) and have a small degree of control over the environment, similar to a guardian angel or Jiminy cricket with the ability to aid the dependent.
*The guardians point of view:*
They wake up and logon, yes like logging into a game but it's work for them, and help this dependent with their quests and tasks and what not just like a game. and they get money and status based on how well their dependent is doing.
*The dependents point of view:*
A magical voice and sprite appears from time to time aiding them in battle, with inventory and other matters. like transporting their loot back to their basecamp, which for the guardian could be as simple as click an drag to a basecamp tab.
**The real question:**
Why would the society of guardians implement such a system in the first place?
I'm thinking that this "game" is similar to mining for bitcoins so they have some sort of cryptocurrency or the like, but doesn't seem compelling enough.
[Answer]
Think of this from a Buddhist or Hindu point of view.
Your Guardians are more like a [Bodhisattva](https://en.wikipedia.org/wiki/Bodhisattva); they don't have a requirement to come back and help the dependents, but in so doing they provide guidance and leadership (not only for the dependents) but increase in status to some degree with their own kind.
The Dependents on the other hand welcome the intervention of the Guardians as it allows them the opportunity to learn from the decisions the Guardians make, and become better themselves as a result.
The only thing that is missing in this scenario is the opportunity for the Dependents to become fully enlightened and take their rightful place as a novitiate among the ranks of Guardians.
That aside, it would be clear that the Guardians have a clear purpose in assisting the Dependents. This purpose is guidance which means that the true measure of their success is the success of the dependent. If you overly coddle your dependent, they don't fare well when you're not around as they can't act independently. Do too little, and they are at a disadvantage compared to other dependents with a more active Guardian. The balance that gives them the right amount of support while learning to do for themselves would result in a thriving dependent, and a commensurate increase in prestige and status for the Guardian.
Of course, if the Dependents **could** become enlightened and join the ranks of Guardians, that would be a major point of prestige for a Guardian if they bring a large number of dependents into their own ranks.
Come to think of it, this is not really any different to what we find ourselves doing as parents every day. We are often judged according to our children's behaviour and choices, at least up until a certain age. This is just a less connected version of that.
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It's a somewhat common trope that the power of a godly being comes from their followers. The number of followers and the amount of praying/gratitude they have directly affects the power of those beings.
In a similar fashion, a Guardian's very own health may be linked by the appreciation/gratitude of their dependent(s). If a dependent is doing terrible in life, they will find their Guardian angel to be terrible useless. But if the Guardian does a good job, the dependent's gratitude strengthens the Guardian.
In the Guardian's society, a badly performing Guardian would appear sick and weak, whereas the most active Guardians are the ones who boast of the best health and, possibly as a result, a better social status.
[Answer]
A few options.
* Self defence: There could be some race in the other dimension which is trying to 'break through' to the guardian's dimension. Giving great prestige to any guardians who train their dependents well.
* Moral duty. Maybe there's a group of people who are using a similar system to negatively affect the dependent dimension. The Guardians accidentally gave people in a 3rd dimension their technology (in their first foray into inter-dimensional communication), so the guardians are acting simply out of a moral duty to stop them.
* Science! There could be great technological achievements in the dependents' dimension, and maybe the guardians seek to understand them so they can be used for their own advantage (maybe to stop some impending natural disaster?)
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Being a "Guardian" type being is boring unless you have something to do. The anime "Is It Wrong to Try to Pick Up Girls in a Dungeon?" explores this trope using the Greek pantheon.
Out of sheer boredom the gods created a world with game like rules, which they then entered with self imposed constraints. In the world, they act as patrons of associations of adventurers, within those self imposed limits, and compete for status through the exploits of their adventurers.
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Why not consider it entertaining ?
For example some mobile games are of idle nature where you set up things let them progres and from time to time interact with them.
In your case this alternative dimension could easily be a simulated universe where the guardians play competing with each other similar to nowadays esports where the goal is to create the ultimate legendary warrior or whatever class that other being would end up being. The depicted ecosystem that i imagine after reading what you said makes me think of a Diablo or any Moba scenario where the player is actually at a professional level and wins money by competing in tournaments or streaming.
About an alternative name maybe "Keepers of fate" or something by those lines
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It's Earth and the moon with all parameters as they are in real life with one exception, the moon is twice as reflective as usual. Instead of an [albedo of 0.12](http://www.asterism.org/tutorials/tut26-1.htm), the moon has an albedo of 0.24. This change will have huge implications for all kinds of things. What I'm interested in is the growth rate of plants.
**With a brighter moon would plants have more energy for growth or is that still too dim to be useful?** If the extra light is useful, how useful would it be?
My assumption is that it will have a small but measurable impact on plant growth. My understanding is that photosynthesis shuts down in darkness so having a little more light on nights when the moon is up will provide more energy for the plant to use.
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It's still way too dim to be useful. You'd have less than 1 lux worth of light, but you need a bare minimum of 50 lux to make any difference at all, and preferably 500 lux to see some significant (but small) amount of extra growth.
Plants' light requirements fall into one of the four categories below, depending on the plant. "Most plants will survive illuminance 10 times lower than listed below but will not grow as well or bloom."
```
Low (500–2,500 lux)
Medium (2,500–10,000 lux)
High (10,000–20,000 lux)
Very High (20,000–50,000 lux)
```
<https://en.wikipedia.org/wiki/Houseplant_care#Data_for_some_common_houseplants>
And common lux levels:
```
Illuminance (lux) Surfaces illuminated by
0.0001 Moonless, overcast night sky (starlight)[3]
0.002 Moonless clear night sky with airglow[3]
0.05–0.3 Full moon on a clear night[4]
100 Very dark overcast day[3]
400 Sunrise or sunset on a clear day.
1000 Overcast day;[3] typical TV studio lighting
10,000–25,000 Full daylight (not direct sun)[3]
32,000–100,000 Direct sunlight
```
<https://en.wikipedia.org/wiki/Lux#Illuminance>
[Answer]
Not really.
Sun is [400,000 times](http://blogs.discovermagazine.com/badastronomy/2012/08/27/bafact-math-the-sun-is-400000-times-brighter-than-the-full-moon/) brighter than full Moon. Doubling and even quadrupling Moon's brightness would still have negligible effect on plant's life. However, it may be a game changer for nocturnal animals.
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Your third paragraph is actually far more important that you may realise, plants need the rest time without photosynthesis at night.
If you did supply 24h light something significant in plant biology would need to change to cope. I think in hydroponic farms with artificial lighting this is typically ~6 hours darkness for optimal growth.
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Replicators have become a staple of science fiction. However, many stories treat them as magical, or with inconsistent abilities.
This is not a magical device that makes anything for nothing. When fed a source of certain atoms (it can't transmute atoms), it will rearrange them into whatever it is programmed to create, such as food, microprocessors or rocket fuel from nearby asteroids. It is not a nuclear reactor.
Also, it can't transmute atoms (e.g: H > He), so it need all the types of atoms used by food (H, O, C, N...), microprocessors (Si, C, Au, H, O, Fe...) or rocket fuel (H, C, O) in order to assamble them.
Given a proper scientific basis, what realistic limitations might it have? Especially, what realistic limitations might it have in the energy consumption used to rearrange atoms or in the used fuel (resources to assemble things)?
[Answer]
Your replicator is a programmable universal catalyst combined with a 3D printer. It can force any particular chemical reaction to occur over others and deposit the result of that chemical reaction in an arbitrary arrangement. However, it cannot violate [conservation of energy](https://en.wikipedia.org/wiki/Conservation_of_energy).
So, how much energy is required to manufacture certain things? It depends on what you're making it from.
## Enthalpy
Enthalpy is a word in chemistry that means the difference in amount of energy stored by the chemical bonds in two groups of molecules. The amount of energy stored in a chemical bond is always negative, meaning energy was released when the bonds were made. When you burn something, that heat energy gets put into breaking some chemical bonds, which then allows the atoms to bond to other atoms in a way that releases more energy. This energy then makes more surrounding molecules hot enough to do the same, resulting in the substance getting hot enough to make nearby air glow (fire).
Things in general tend to want to release energy more than they want to gain it. This is why hot things start to glow when they get *really* hot (like metal or the sun) and why things tend to fall down instead of floating in the air.
## Calculating enthalpy
In order to work out the difference in enthalpy, you must first find some chemical bond diagrams, like this one for methane:
Methane has four C–H bonds. O₂ has one O=O bond, CO₂ has two C=O bonds and H₂O has two O–H bonds. Now that you have these, look them up in a [bond energy table](https://duckduckgo.com/?q=bond+energy+table) to work out the amount of energy stored in these bonds (remember that this will be negative!):
$$\begin{array}{|l|l|}\hline
\text{Bond} & \text{Energy (kJ/mol)} \\
\hline
\mathrm H- \mathrm O & -459 \\
\mathrm H- \mathrm C & -411 \\
\mathrm O- \mathrm O & -142 \\
\mathrm O= \mathrm O & -494 \\
\mathrm O- \mathrm C & -358 \\
\mathrm O= \mathrm C & -799 \\
\mathrm O≡ \mathrm C & -1072 \\
\hline\end{array} $$
This gives methane a total bond energy of 4 × −411 kJ/mol = −1644 kJ/mol. O₂ has −494 kJ/mol, CO₂ has −1598 kJ/mol and H₂O has −918 kJ/mol.
## Balancing the equation
Now that you have the energy per mol, you must work out how much of each molecule you need to make one mol of methane. This reaction tends to go one way (methane is burned) so I'll write it that way as according to convention.
First, write the unbalanced equation:
$$ \mathrm{CH\_4} + \mathrm{O\_2} → \mathrm{CO\_2} + \mathrm{H\_2O} $$
Now, count the number of each atom on both sides. On the left we have one C, four H and two O. On the right we have one C (check!), two O (oh dear), two H (this isn't good) and another O (making three in total).
We have the right number of C, which suggests that we don’t need to change the number of anything with a C in it. H is only in one molecule that we don’t know the number of, so let’s add some more of that to get the right number.
$$ \mathrm{CH\_4} + \mathrm{O\_2} → \mathrm{CO\_2} + 2 \mathrm{H\_2O} $$
Now we have the same number of H and C on both sides. On the right hand side we have 4 O, and on the left hand side we have...
$$ \mathrm{CH\_4} + 2 \mathrm{O\_2} → \mathrm{CO\_2} + 2 \mathrm{H\_2O} $$
Yay! It’s balanced.
## Calculating enthalpy change
Now that you know how much of each molecule there is, you can calculate the enthalpy change. The methane and O₂ have a combined enthalpy of:
−1644 kJ/mol + 2 × −494 kJ/mol = −2632 kJ/mol
The CO₂ and H₂O have a combined enthalpy of:
−1598 kJ/mol + 2 × −918 kJ/mol = −3434 kJ/mol
Performing a quick sanity check: Less energy is used making the bonds in CO₂ and H₂O than it took to break the bonds in methane and O₂, so this seems about right.
This means that you’ll have to put in −2632 kJ/mol − −3434 kJ/mol = 802 kJ/mol into the replicator order to produce methane (and oxygen) from water and carbon dioxide.
This value is probably not very useful at the moment. What this means is that, for every 802 kJ you put into the replicator you can produce 1 mol of methane and 2 mol of oxygen. In order to work out how much this weighs, you must turn to the Periodic Table!
## Molecular Mass
[](https://commons.wikimedia.org/wiki/File:Periodic-table.jpg)
The molar mass of an atom is written underneath the chemical symbol in this image. It is in the units g/mol. To calculate the molecular mass of a molecule, add together the molar masses of the atoms. For example, methane is:
15.999 g/mol + 4 × 1.0079 g/mol = 20.025 g/mol
Now we have energy per mole and mass per mole, and we want energy per mass. To work out what to do with these two values to get what we want, we can use algebra. Does multiplying them work?
$$\frac{\text{energy}}{\text{mole}} \times \frac{\text{mass}}{\text{mole}} = \frac{\text{energy} \times \text{mass}}{\text{mole}^2}$$
No. What about dividing?
$$\frac{\text{energy}}{\text{mole}} \div \frac{\text{mass}}{\text{mole}} = \frac{\text{energy}}{\text{mole}} \times \frac{\text{mole}}{\text{mass}} = \frac{\text{energy}}{\text{mass}}$$
Yes! This means that we can produce the energy per mass:
802 kJ/mol ÷ 20.025 g/mol = 40.05 kJ/g
## Getting energy
Here comes the main limitation — your replicator cannot violate conservation of energy, so it can't create compounds that require more than zero energy to synthesise. So, where can energy come from?
* An external energy source.
This one's obvious — any source of heat or electricity can be used as a source of energy. I'll ignore it because it's not specific to replicators.
* A battery.
The energy from exothermic (energy-releasing) reactions could be stored as electricity in a rechargeable battery. Or, better still, by performing an endothermic reaction to produce a stable, high-energy store that can later be used. It doesn't really matter what this is; a higher energy / mass ratio would be lighter but potentially more dangerous. (Then again, what *isn't* dangerous about a replicator?)
* A fuel source.
If you have some other material to spare, and don’t care what it’s made into, you could use that as a source of energy. One way of working this out is provided below.
# Standard enthalpy of formation
There is a simple way of working out enthalpy using a value called the "standard enthalpy of formation" but it only works if you can find this value for every compound involved. This is a measure of the energy released when creating a compound from each constituent element's [standard state](https://en.wikipedia.org/wiki/Standard_state). What this standard state *is* doesn't really matter, so long as every standard enthalpy of formation uses the same standard state (which it will).
If you take the standard enthalpy of formation of the fuel that you want to put into the machine (including any oxygen or other molecules) and subtract the standard enthalpy of formation of the products, you get the energy required to perform that chemical reaction. For octane:
$$\mathrm{C\_8H\_{18}} + 25 \mathrm{O\_2} → 8 \mathrm{CO\_2} + 9 \mathrm{H\_2O}$$
$$(−250 kJ/mol + 25 \times 0 kJ/mol) - (8 \times 393.5 kJ/mol + 285.8 kJ/mol) $$
More coming soon.
[Answer]
One of the limitations often forgotten in the science fiction of replicators is the challenge that arises when the replicated object undergoes chemical reactions while being replicated. Many structure are *very* difficult to construct without them reacting with the environment, such as oxidizing. If you attempt to recreate a famous painting via this method, be prepared to have issues when the Linseed Oil in the paint burns in the air during replication. Indeed this could lead to patterns which are used to detect the original painting, distinguishing it from forgeries.
Proteins are *notoriously* difficult to develop. Even identifying their folded structures is difficult, but making them is nearly impossible unless you do it the old fashioned way: in a cell, surrounded by cytoplasm. As such, living things would be nearly impossible to replicate.
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I think you could save a lot of energy if you didn't try to do everything with atoms.
A lot of stuff readily reacts with other stuff, requiring you to invest energy to keep your atoms pure. Just think about everything that tends to oxidize.
Often enough, you don't need pure atoms i the first place.
If you want to create food, you could work with the pure elements, but you could also start with hydrocarbbons, carbon oxides and so forth.
Look at the way chemistry is done. You use ingredients that are reasonably safe to store, and let them react with other ingredients to create your results. Adding catalysts or enzymes often takes a lot of complication out of those processes.
While there might be fancy stuff that would require pure atomic matter for it's creation, a lot of other things (like food, as mentionned), are easier to make from molecular ingredients, thus reducing your total power consumption both in your recyclers (where you obtain most of your raw matierals from) and in your replicators.
It might also make things a lot safer. Just imagine creating water from pure atoms: there are known processes for that, they are called rocket engines. I am sure there are other processes that are a bit better suited for indoor use, and that require a lot less energy for purifying the ingredients in the first place. After all, the energy that is freed in the process of oxidation has to be provided up front in the recycling process, and more energy needs to be invested in preventing unwanted reactions.
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A group of guys went drinking, one got drunk so severly he passed out, so the rest duct-taped him. A story as old as the world.
Is it, really? According to Wikipedia <https://en.wikipedia.org/wiki/Duct_tape> the history of duct tapes, and adhesive tapes in general, started as late as in the beginning of the XX century.
Did it have to be that way, though? A cloth tape covered in a layer of glue - this seems simple enough that it could be made even with ancient technology, right?
How advanced technologically does a setting have to be if duct tapes are being used?
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What is your definition? *Pressure Sensitive Adhesive*? Waterproof?
A humorous fictional account said it was invented in ancient Greese when someone tore a strip off his toga and used it with hot pitch (or asphalt) to make an improvised repair. Seriously, I think this would have been done as long as waterproof sealers have been in use, for roofs and boats.
If you require a [roll of ready to use tape](https://en.m.wikipedia.org/wiki/Pressure-sensitive_tape) the chemistry goes back to 1845.
Now there is nothing *special* about PSA chemistry, really. Ancient people had shellac, rubber, gelatin, etc. It *might* have just-so happened that some PSA was discovered in antiquity. Or, something that’s stored dry and *easy* to activate, say, with water or alcohol.
For your story, just understand those issues and limitations. Cloth permiated that becomes sticky and waterproof *when it gets wet* would be very useful. I imagine a fanciful recipe that calls for hagfish mucous…
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Try looking at history of adhesives. Glues are mostly either heat or solvent based. Solvents can be water, alcohol or chemicals like benzene, toluene. The latter are recent. Alcohol needs to be close to pure to be an effective solvent. (shellac is dissolved in alcohol as are many laquers) Alcohol glues don't do well if they get wet.
Hide based and fish glues tend to be applied hot.
I'm having trouble coming up with an old time adhesive that is sticky enough to get an instant bond, but that don't dry out when the roll is wrapped up.
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Theoretically, a duct-tape-like material could have been made a very long time ago. The first recorded use of an adhesive dates to 70,000 BCE when an early human in South Africa [used a resin to coat and protect cave paintings](http://www.adhesives.org/resources/knowledge-center/aggregate-single/the-history-of-adhesives). We know that people were also using animal skins at that time, so it is very possibly that a person could have applied resin to a strip of hide and used it as tape.
However, it is worth noting that this "cave-man duct-tape" probably would not have lasted as long as modern duct-tape. After all, the original intent of this particular instance of resin use was to protect a surface, not to make things stick to it, so the stickiness of the resin was probably short-lived. Not to mention that storing this stuff would have been difficult, since you couldn't just roll it up or it would stick to itself.
That said, it is totally reasonable for a very primitive technology system to have a sort of duct-tape equivalent. Depending on the society, it is even very likely. Whether they would have used the stuff on each other... well, I suppose that's up to you.
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"A cloth tape covered in a layer of glue - this seems simple enough that it could be made even with ancient technology, right"
Lets look at what exactly duct tape is made out of to find out for sure!
### Cloth tape
The original 'duck' tape used cotton [duck cloth](https://en.wikipedia.org/wiki/Cotton_duck) as its backing. The word 'duck' actually comes from Dutch for linen canvas. Tight woven canvasses of linen became readily used for painting, shields, and sails by the late middle ages in Europe; cotton versions were not as strong but lighter. My research is quasi-inconclusive, but it appears that tight woven canvas was not used by the Greeks and Romans, who used lighter linen sails. The Arabs used lighter woven hemp sails.
In any case, appropriate cloth is available by the Medieval period at the latest, possibly much earlier.
### Glue
Wikipedia's amazing [Chemistry of pressure-sensitive adhesives](https://en.wikipedia.org/wiki/Chemistry_of_pressure-sensitive_adhesives#Common_adhesives) comes in handy here! Basically, adhesive tape depended on the presence of rubber at first. An example would be a mixture of [rosin](https://en.wikipedia.org/wiki/Rosin) and [rubber](https://en.wikipedia.org/wiki/Natural_rubber). Now both of these are natural ingredients, and both are in fact tree sap. So we can conclude that the ingredients are all present by the middle ages at the latest.
### Problems and Solutions
However, there is a problem. The first is that these resources are found in widely different areas. Rosin comes from pine trees and wild rubber from rubber trees; one is at home in temperate and/or mountainous regions, the other in the lowland tropics. This can be overcome by two ways. The first is to make a world where these regions are adjacent to each other. The Mexican highlands are filled with pine, and the nearby Yucutan is a lowland rainforest; make these areas larger and have your civilization develop there. The second is to invent new plants. The Germans tried to extract natural rubber from dandelions, which contain small amounts of latex. They were unsuccessful, but if you invented a much more latex-y dandelion plant that lived in temperate environments with pine trees, then the ingridents would be together.
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It's all about cost:
As explained in the other answers, you can make paleo-tape with any kind of adhesive (tar, starch-based, or animal-based glue) and any kind of strip material (fabric, leather, etc).
However, in the old days, fabric and leather would have been quite expensive, and this is not compatible with single-use tape. Today, we can purchase a roll of duct tape for a very low price, so we don't think about that.
Using such an expensive material for a joke would probably seem incongruous to people in these old times.
People would use reusable products like rope or string. Or they would tie the victim's shoelaces. And maybe put a bucket over his head, and wait for him to wake up... Or he would just wake up lying on top of a heap of manure... Think low-budget jokes!
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Elves have a long life and in most settings, they only have children after a century or two.
Would sub races like, drow and aquatic elves really evolve without any magic intervening?
Considering that humans of the same setting are like us, pretty much everyone is the same.
I think that is really unlikely unless the mutation on the DNA of their children were more radical than on humans.
Edit: I didn't express myself well, I do know they will evolve but I mean will they evolve significantly so that subraces like aquatic elves will exist, since they have +-1/5 of the generation that humans have. And do different but similar species, like elves and humans, could have different mutation rate?
I am building is a fantasy world with magic but with roots in science, I don't like answers like "because it's magic".
The elves in my world do have tetrachromacy and bigger pupil and iris, the fourth receptor allows them to see ultraviolet, all this to make their long-range vision more plausible, and because of this, I defined that they evolved in an environment with preys that hide really well if don't see ultraviolet. And also that magic emit ultraviolet light making them better than other races at perceiving magic around.
Is really hard to choose only one answer, each kind of complements the other.
Edit 2: I found an [article](http://sciencenordic.com/children-older-men-have-more-dna-mutations) online that says that children of older fathers have more mutations in their DNA, I don't how much of this is true but maybe this could justify bigger mutation rates on elves.
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I should say that I agree with the answers given by akaioi and PipperChip - evolving is possible and will happen, but very slow. On the other hand I haven't seen some parts which I see as important in their answers, so I would like to add to the said above and before me the following:
To akaioi's answer: there is no such thing as a "purely cosmetic" modifications in evolving. If a color of feathers/hair/skin is changing (differ from the one parents/the main part of population have) it is due to either random mutation or adaptation to the surroundings (in the last case most probably the feature will acquire in one of/both parents but in a less expressive manner or it might not acquire at all, check this link, part №4 <http://www.biology-questions-and-answers.com/mendel.html>).
This said I'd like to add to PipperChip's answer that skin color is a result of color pigment presence intensity in the skin cells, which means that in cases where there is no need for skin to have a certain amount of the pigment it will change the color to a less expressed one. To put it simple - if you take a group of white skinned ppl and put them all in the equator area they will morph firstly into darker individuals after several generations being constantly exposed to intense sunshine/UVR (ultraviolet radiation) and after several more generations they will acquire black/brown skin tone. Same goes for black/brown skinned ppl and for the first group if they are moved to less exposed to UVR area – after several generations they will become/go back to white skin tone(d). For skin tone explanation (in case you’re not familiar with this) just read about melaninum/melanin.
What I mean is that mentioned Drow would not keep the skin tone of ebonite black, as it is in FR universe, unless magic.
Also evolution for isolated group of any species is slower comparing to the not isolated group of the same species due to not having same amount of factors to influence evolving process.
Adding to Yours “Edit 2”:
When we are talking about mutations in DNA code caused by parents age it is true. But you should understand that in over 90% of cases when such mutations acquire they are not beneficial, but damaging ones. For example the trisomy of the 21st pair of chromosomes causes down’s syndrome (easy brief article on wiki will let you know more about it if needed without going too deep in genetics). The reason for this is that cells being old have some mutations of their own that appeared during individual’s life, and now not all of them work always as they were supposed to. This brings up a problem of incorrect transcription, cooperation of parental DNA chains and sometimes in addition of extra parts to the final code (three instead of two chromosomes of the 21 pair type as in the example) and thus – deviations of different scales and harshness in the developing individual.
When we are talking about beneficial mutations/modifications they might sometime happen spontaneously, but this event has a very low chance of happening and in cases when there are no other individuals with same feature or the feature is recessive (not dominant), which would help to keep new feature in the further generations, even the most beneficial mod might be lost for the species.
That’s why if we are talking about colors of butterflies, for example, that live in the industrial area, most probably after couple generations they will be primary of grey/black color (in case those are the most often met colors of their surroundings), even though they used to be white or any other bright color in the first place with small variation towards black/gray. The reason for this is that all the well seen due to being bright butterflies will be eaten by birds meanwhile the grey/black ones have better chances of survival.
This example goes more to what's been said in the first place, but the main mechanism is same.
Thank You for Your attention. All the best.
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# Evolution Works With Generations, Not Over Time
Just a quick review: [evolution](https://en.wikipedia.org/wiki/Evolution) is the combination of two ideas: "descent with modification" and "selection." If you have these two things happening to a group of creatures, evolution happens.
With every generation of a species, some modifications arise. For example, maybe a child develops [tetrachromacy](https://youtu.be/lgHm5TKBW54?t=1m51s) whereas the parents did not have this trait. Or perhaps some other desirable or helpful trait gets passed down and amplified. Either way, this is descent with modification.
Selection is just the idea that a creature's environment (be it natural or artificial) will favor some traits over others. Maybe tetrachromacy allows this child to better observe their surroundings and enables the child to survive longer and have more children, or perhaps it's a very desirable trait.
Combine these two ideas and you get the basics of evolution. The real important bit here is that evolution only requires *some selective process, babies, and sex.* If those things exist, evolution does too.
# Some Details
The causes of [speciation](https://en.wikipedia.org/wiki/Speciation) is the same causes of races/subraces. If you get a bunch of redheads and strand them on an habitable island, you'll get a race of red-headed people. If dark skin prevents people from getting killed, the people left to breed will have dark skin and you'll get a race (subrace?) of dark-skinned people.
Elves breeding much more slowly than humans means their evolution will be much slower, but still happening. With enough time and factors, sub-races (or just races?) will evolve. Remember, the causes of speciation cause sub-races, and you can exploit these to give evolution a little boost. So maybe the founding Drow were dark skinned, moved to a different place, and the dark-skinned trait was passed on (this is known as the [founder effect](https://en.wikipedia.org/wiki/Founder_effect).)
Evolution generally requires that traits be present in a population in order to be enhanced. You won't get a new generation of elves suddenly able to breath underwater without some magic or genetic engineering. They could, however, get better at holding their breath, swimming, and so on.
In short: **yes, evolution happens to elves, too**
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Here's a thought... In stories I have read, there are a couple salient facts about elves:
* They are not numerous
* They live in out-of-the-way places
We can work with this. Imagine small, isolated communities of elves. If each small elf-clan sticks to itself, any mutation which shows up has a far greater chance of spreading through the community; this is the stay-at-home version of the founder effect.
To clarify ... imagine a city of ten thousand elves. One little elf is a mutant and has white hair. The chances of his mutation spreading throughout the whole city is minuscule. But if he lives in a clan of 50, his white-haired children will be a way larger proportion of the population. A little luck, a little contingency, and before long you have a whole little tribe of proto-Drow!
Update: A further note on "contingency". If a mutation is beneficial it has a better chance of spreading. If it is purely cosmetic, it's a question of chance (hence better odds in a small, isolated group).
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Yes but obviously evolution would be much slower. The faster a species breeds, the faster it evolves.
Aquatic elves would be the exception only because requirements to breath underwater is radically different to air breathers. Legs are not needed so the whole body would end up being radically different.
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I'm working on a post-apocalyptic desert scenario in the near future where people live in small, loosely connected communities that trade with each other on a small scale and might have agreements regarding infrastructure use and maintenance and energy production such as establishing a smart grid. They are subsistence farmers and scavengers (to keep machines and computers running) but might cooperate for educational purposes and maybe even establish something along the lines of universities. They would be hampered by specialty and hard-to-make products not being available. Electricity generation would be completely decentralized and maybe not available around the clock. Clean drinking water would be infinitely more precious as even ground water might be salty. In general these communities would be very eco-friendly by necessity. Waste and pollution of common goods would be considered sin.
So the two biggest problems are the absence of fertile soil and water scarcity.
**Water**
I imagine you could use solar heat to desalinate sea water and transport it inland using pipelines. I'm not sure how energy efficient this is (if it was cheap it'd be used in all desert regions with sea access on a big scale) and going high tech would defeat the purpose as there wouldn't be a central authority keeping large and complex infrastructure projects running, only agreements between small communities to say maintain a stretch of road or pipeline. Also the power-differential arising from control over water distribution by one group of people could lead to conflict. This is way big centralized undertakings are to be avoided. Solar pumps could pump up ground water to be desalinated locally if need be.
**Food**
Do hydroponics present an answer in this situation or would you have to add other ways of growing food at the village level? You could farm vegetables and fish but you would need grain, right? Not just to make sure people get enough energy from carbs but also to feed it to livestock assuming an omnivore diet. I've never heard of hydroponics being used to grow grain. I also don't know how water efficient the technology is but I'm assuming it must be since NASA is working on it.
**EDIT**
Seems there's a consensus that hydroponics is out because it's too high tech and that the solution will be combination of aquaponics, raised-bed-farming of vegetables, and the farming of rabbits, chicken, goats and insects for protein.
I didn't know [saltwater aquaponics](https://en.wikipedia.org/wiki/Saltwater_aquaponics) existed (even though there's no reason it shouldn't). [This](https://phys.org/news/2017-03-genetic-key-salt-tolerance-tilapia-fish.html) suggests that the most popular fish for sweetwater aquaponics can be modified to tolerate salt water. It makes protein (and possible vegetable) farming using salt water look quite feasible.
The question that remains is how to reproduce fertile soil. I'm assuming this can be done using compost? Could an agricultural cycle be established that removes the need to "fetch" natural soil indefinitely once it's been going for a while?
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# FOOD
The problem with the food can be solved with hydroponics and aquaponics. You can farm aquatic animals in tanks (aquaponic system). Eventually the water will be filled with excreta of the animals. The water can now be feed into a hydroponic system, you can use sand to support the roots of the plants. The water can again be used in the aquaponic system. Thus only a fixed amount of water will be needed.
Vegetables that could do well in a hydroponic garden **(with a grain of salt)** include artichokes, beans, lettuce, spinach, cabbage, beets, asparagus, broccoli, cauliflower, Brussels sprouts and peas. Vegetables that grow beneath the soil, such as onions, leeks, carrots, parsnips, potatoes, yams and radishes will also grow hydroponically, but may require extra care. Some crops to avoid are corn, zucchini, summer squash, and vining plants. They can be grown in a hydroponic garden, but they are not space efficient, and just not practical. They will dominate your whole unit. Your resources are better spent on crops more suited to the compact systems.
The main problem is that how to grow enough amount of food, you will require large enough space to grow food that can last a community for a month.
***The minimum amount of agricultural land necessary for sustainable food security, with a diversified diet similar to those of North America and Western Europe (hence including meat), is 0.5 of a hectare per person.***
I have no idea how much area per person will it take when speaking in terms with Hydroponics.
**I would have suggested using normal agricultural method but since it is a desert scenario one can hardly grow enough crop in sand. The only problem in using Hydroponics is that the nutrients have to be controlled minutely**
# Water
Your idea about using solar pumps to transport the water and then desalinating it locally is good. **But since the Hydroponics and Aquaponic uses large amount of water (for the first time i.e, during installation) when it comes to grow food for a community, the water supply must be steady in the beginning, to fill up large tanks to farm aquatic animals. And then have that same amount of water stored somewhere else, so that the the farming tank doesn't go dry when the water with excreta is being used in hydroponic system.**
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Hydroponic and similar techniques need a lot of water very careful dosage of nutrients in it.
They are suited to carefully controlled environment and to avoid contamination. They are (normally) used in "factories" where everything is artificial and controlled, including sunlight.
If you have that much water and fertilizer your best bet is to setup normal soil cultivations, possibly in a greenhouse to minimize water dispersion.
You would gain nothing from hydroponics, while needing a stricter control.
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Hydroponics is a technology you can use when soil is scarce but but water is plentiful. However in the situation you describe, water is also scarce. This will mean that hydroponics is not a viable solution.
Solar stills can be used on a small scale to evaporate and condense drinking water, normally they're only used in survival situations as there's almost always a better way of doing it. However as a technology it can be scaled up to produce reasonable quantities of water, but not practically to the point of producing industrial quantities of water. Powered methods of distilling fresh water from sea water or other contaminated water tend to be prohibitive on power consumption. That's prohibitive now, not just prohibitive post-apocalypse.
In short, your coastal villages can possibly generate enough drinking water for themselves and maybe some irrigation from a system of solar stills. They're not going to be able to produce enough water either to supply other villages or to run hydroponics.
Water efficiency can be improved by growing in raised beds and collecting all water run off to prevent wastage from irrigation. However in doing this the overall quality of the local soil will not be improved. Effort should be put into improving the soil as early as practical after initial survival issues are resolved.
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Soumyajeet Addya has a really nice answer but I've got a couple of things to add that I feel warrant consideration, firstly cereals; grains like wheat and barley only need a lot of water at germination and during early growth they then "harden off" on lower water regimes, thus you need only run new water into the system for part of the growing season thus reducing the total volumes you need to pump in. These are crops that also create straw/hay which can be used for livestock and draft animals. Secondly seawater farming; there are large number of projects that are using fresh seawater to farm salt-tolerant plants both directly edible species for human and animal consumption and biomass for fuel.
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One of the possible options is aeroponics-based vertical farming. These systems use water mist and do not require soil. The water requirements are lower than for hydroponics. Vertical farming may result in higher yields than other options if you can provide adequate lighting, nutrients, and CO2.
Real world vertical farms use LED red and blue lights (can be a problem in your setting) to increase production. The environments are closed and fully controlled to create optimal growing conditions and to avoid pests contamination. A lot of work is automated. These farms usually specialise in leafy greens but can be used for growing grain as well. Dwarf versions of plants are more suitable but may be harder to obtain.
I think livestock is not an option in your case. You can try to raise rabbits but any bigger animal would consume too many resources, including water. The calorie output also will be too low to justify expenses. You might be better off with insects and bacteria as sources of protein.
As others mentioned, you can also do tank fish farming. But it might be more reasonable to build fish farms near the ocean and grow sea fish since they do not require desalination. It might also be easier to feed this fish because you will able to grow their food in sea water. A coastal community then might specialise in growing and processing (canning, curing, etc.) fish and trading it for other goods.
There is a caveat, though. Depending on a number of survivors and level of automatisation prior to an apocalyptic event, any high-tech farming can be simply unsustainable. With the current technologies, once you run out of spare parts your system is no longer functional even if you have enough electricity to power it and people who are qualified to maintain it.
Unless you can start re-industrialisation very quickly, you will be better off figuring out how to produce food using low-tech methods. It will be more sustainable in a long run.
**Edit**:
To think of it, there is a lot of food that can be grown in brackish water. You can farm all kind of molluscs, grow kelp (seaweed), farm fish and shrimp. There are also [salt-tolerant plants](http://www.cbc.ca/news/technology/saltwater-plants-1.3193535) that can be grown for biofuel and food.
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I'm new to science-fiction and I'm intrigued by the consequences of "Plan B" in the popular movie *Interstellar.* "Plan B" means transporting a supposedly sustainable population to a habitable planet outside of our solar system because the Earth can no longer sustain life and no other options are viable.
[This](https://scifi.stackexchange.com/questions/72278/what-exactly-was-the-strategy-in-plan-b) and [this](https://worldbuilding.stackexchange.com/a/48385/42172) address the question of how the "Plan B" colonization would take place and how colonization can work at all. My question is about why we would colonize if it meant a substantial technological setback.
**The background to my question is this:** Regardless the nature of Edmund's Planet, but assuming it is habitable, what would life have been like? I'm specifically curious about the relationship between humans and the technology that got them to the planet. Would they be able to make (sustained) use of it and reproduce it locally given they have access to the materials needed within their surroundings? The transfer of knowledge seems achievable using computers brought from earth, but would they have the capacity?
Imagine, therefore, being stuck on a planet lacking the chemical composition necessary for modern technology to persist while colonists possess the full (now useless) scientific knowledge to produce that technology. It would be ironic because *Interstellar*'s main protagonist is just that: a very well educated man forced to be a farmer. And he's not happy.
**My question is therefore:** Assuming the colonized planet's resources would not support continued use of modern technology, why would we establish a human colony on another planet without the continued benefit of modern technology? Why would we opt for people to be (e.g.) subsistence farmers without the means to evolve the technology (and thus the society) they once depended on?
The reason I ask is because this situation is intriguing from a narrative point of view.
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*Insterstellar*'s primary crisis is the most obvious answer to your question: to save the human race. If the options were (a) for Humanity to be erased from the cosmic narrative and (b) to colonize a planet where we would be forced back to the 1500's technologically, *why wouldn't we take option B?* I suspect that given Humanity knew generally about its upcoming demise, you'd have people of all walks and education lined up for hundreds of miles to get a seat on that particular bus.
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> It's funny how all living organisms are alike, when the chips are down... when the pressure is on... every creature on the face of the earth is interested in one thing and one thing only... its own survival. (*[Minority Report](https://www.youtube.com/watch?v=0XEgAkvcVAk)*)
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However, I can imagine other reasons.
**A Peaceful Life**
In your question you point out that well-educated Coop is forced to be a farmer and doesn't like it. I think you'd be surprised how many people like coop would jump at the chance to colonize a world even if it meant losing all of our modern technology. Some would do it for the challenge (see below). But many would do it for the quite life it provides.
**Food for the Homeland**
What if you weren't an engineer or scientist? What if the Earth's population needed food and stellar transportation became cheap enough to move the proverbial boatloads of wheat? Can you imagine the number of farmers (and non-farmers) who would jump at the chance to homestead a new world, even if it meant both indentured servitude to Mother Earth and the loss of all technology (other than what might be imported due to the transportation)?
**Because It's There**
Finally, humanity is generally colonial. We've migrated and expanded all our lives. We pretty much can't stand not knowing a secret or not conquering a challenge. If there was a habitable planet out there, no matter the consequence to technology, there would be someone willing to colonize it. Some might do it just to thumb their nose at the rest of humanity, but others would do it just because....
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> "I'm doing this because I enjoy it. Not to mention the most important reason for climbing a mountain," said Kirk. "And that is?" asked Spock. "Because it's there." (*[Star Trek V: The Final Frontier](http://memory-alpha.wikia.com/wiki/El_Capitan)*)
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Neal Stephenson's book "Seveneves" might have some interesting thoughts on this - basically it's about the consequences of an Earth-threatening event, where humanity has to move into space to survive.
[Spoilers below]:
Given that there's a finite time before the Earth suffers cataclysmic meteor strikes, only a limited number of people can make it into space. Some are General Population from across the globe (teenagers trained quickly in a year to be able to pilot a spacecraft, but basically there just for breeding potential and genetic diversity); some are tech specialists (mining industry/genetic research/nuclear physicists/etc.); and a small minority were just already up in space at the time they learned of the impending crisis.
Things like lens grinders were shipped up (to make glasses), but enough people die that there's no-one left to operate the technology, and it's not urgent enough for anyone left to bother. [Zero gravity changes the shape of your eyes, thereby affecting your vision].
Their long-term aim is to return to Earth once it's inhabitable again, but short-term is just survival, and continuation of the human race. They end up living on a large meteor in geocentric orbit, which has some of the conditions they need (protection from radiation and solar flares, orbital stability, defense from small rocks rocketing through space). Water is needed (for drinking and for fuel in nuclear fission), so they hunt down meteorites made from ice. Trace elements (potassium, nitrates, etc.) useful for plant production and medicines are also found on the surface of the ice. Some meteors have metallic cores, so can theoretically be smelted and utilised in building structures and replacing technology.
In "Seveneves", humanity several thousand years later still hasn't got back to some technological levels that their predecessors had (e.g. mobile phones, tiny processors, and so on), but had advanced significantly in other areas that were more useful to them. So, things like spinning tori (to produce artificial gravity) became a lot more refined, as did mechanisms to transition between zero-g and environments with gravity, methods of getting between space and the Earth's surface, and genetic manipulation. Humanity ends up split into different races, each descended from an Eve (one of the 7 women who survived the cataclysm and subsequent space journey). They have different physical and psychological characteristics, determined by the Eves as they genetically modified their foetuses to adapt better to the new world, then augmented through several thousand years of breeding and genetic experimentation.
While the initial plan might be to reach another planet/return to the original planet eventually, perhaps conditions are more favourable in space, so humanity simply has to adapt to the environment there. If there was any freedom to plan destination, maybe enough research went into choosing the destination that they knew in advance that there would be appropriate resources there to enable technological innovation and improvement. Even if things went wrong though, humans are remarkably tenacious. It might take longer than expected, but they'd probably find a way to reach their eventual goal: space travel, but not as we know it.
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All of these scenarios require a large pile of woolly thinking, or at least some startling coincidences to happen. If you can get to another planet, you have tech more advanced than ours, if you can get to another solar system then your tech is far more advanced. A colony on another world will almost certainly need advanced technology to survive, like space suits, unless the world is almost identical to earth. Ether this is made locally or it is shipped in. If high tech resources are shipped in from earth, then you are a small outpost of a thriving world, otherwise you have set up your own high tech society. It is possible that radio noise could force you to use fiber optics not wireless, or that a shortage of uranium makes fission unusable, but overall tech levels are unchanged.
If we are lucky enough to find an exceptionally habitable planet around a nearby star, we wouldn't have good reason to consider it habitable until we sent probes there. We can tell its the right temperature and as breathable air; but toxic spores, global oceans, or nothing edible are all likely options. Furthermore what technologies are required to send such an interstellar voyage. Sending such a craft at relativistic speed requires vast amounts of energy, warping space into wormholes requires even more. If you have that sort of energy then growing food with lots of bulbs, sending cargo around within a solar system or mining and refining large amounts of rock take trivial amounts in comparison. You also have advanced life support and recycling systems to support the crew for the voyage.
Faced with these technologies we would be capable of setting up a large industrial base on mars, and survive any event short of a major collision on earth. (Any event that doesn't boil the oceans and melt the crust should be survivable in a well equipped bunker or sub.) Therefor we only need to go interstellar for survival when faced with something that will trash the entire solar system, like a rouge black hole. Even in this scenario it may be wiser to pull over to an asteroid and start mining when you arrive in a new star system. The only circumstances in which this makes any sense is if a manned capsule is bolted on to an interstellar probe in a last desperate attempt to survive after the black hole is found days away, no significant planing, just YOU, MOVE, NOW. Then you need some critical component in the air system to fail just as they reach the planet (no spares or fixes), leaving them a choice of bail or suffocate.
In short we will not have to rebuild tech on an alien world unless a series of flukes forces us down the narrow line between fine and dead.
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Another possible answer:
1. One possibility used in some scenarios is that radiation, or other feature of the colonized planet, is incompatible with our technology.
2. The possibility exists that the colonists want the simple life as mentioned elsewhere.
3. I think you could imagine a scenario of, for example, a prison world where technology is held back and the people on the planet are kept in a state of, essentially, servitude.
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Well if you have to go, like they do in *Interstellar*, then it doesn't matter what the price is, colonists who are trapped in a technological cul-de-sac are preferable to species extinction. Generally speaking any colony is going to take a hit on the tech front for a few generations regardless, you just don't have the total population to support higher technology, it's estimated that it takes about 300million people to maintain a single microchip factory. But unless the planet is critically short of many elements then eventually you will build a population that will grow and maintain technology sufficient to the situation, whether that looks like what we use today or not is a different story.
As a note "tech loss" may or may not occur *in the first place* depending how far you've gone down particular theoretical technological routes; if you have a [cornucopia machine](https://en.wikipedia.org/wiki/Molecular_assembler) you only go backwards *by choice* unless the world you're on is almost devoid of key component elements like Carbon and Silicon, in which case you have bigger problems.
[Answer]
The reason to colonize - that is, why an individual would choose to go as a colonist - is that for most of us, living without a lot of technology is way preferrable to dying.
It's perfectly possible to live a happy life without much technology: there's evidence that people in isolated hunter-gatherer cultures are no less happy than urban technophiles, and perhaps happier. Even today, some of us choose to live without certain sorts of tech. (For instance, I've never owned a TV.)
Then there is the fact that much useful tech isn't all that technical, it's simply a matter of knowledge. For instance, sanitation & proper nutrition prevents many diseases, yet you don't need much tech for them. So if you have the knowedge in your colony's reference library, you can use whatever you need.
If your colony's small, you don't really need a major transportation infrastructure. Foot and horse work fine, and you have the knowledge to build more when it becomes desirable. And so on...
[Answer]
Why would anyone ever leave the comforts of home? After all, [Columbus was a Dope](https://en.wikipedia.org/wiki/Columbus_Was_a_Dope) who should have never risked his crew's lives.
Don't look forward, look backwards. Why would people settle less-civilized areas like 40,000 BCE Iran, 10,000 BCE Alaska, 10,000 BCE Ireland, 1650 Virginia, 1850 Australia/Wisconsin, etc.?
* Escape overcrowding -- better life for your grandkids
* Get in on the ground floor for generational wealth
* Escape restrictive social environments (not always voluntary)
* Wanderlust
* Religious freedom // the ability to negate religious freedom (An oversimplified reminder: Massachusetts was founded by people escaping religious persecution in England. The rest of the US New England states were founded by people escaping religious persecution in Massachusetts.)
* Resource exploitation
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[Question]
[
Assuming we are in post-apocalyptic wilderness where herbs are readily available for treatment, would it be feasible for someone to be stabbed with a knife and not only survive but heal enough to keep moving within a week max? The wound can be anywhere, but I was thinking the only place it could realistically be is the upper arm around the bicep.
[Answer]
A stab with a clean blade may not be fatal and heal almost perfectly, even without modern medicine and outer help, if the blade travels only through skin, fat and muscle, possibly cutting some vein, but no major arteries.
If anything else is in its trajectory things get stingy, unless you have a doctor available.
A modern E.R. is not necessary (but it helps); doctors in Magna Grecia were perfectly able to help non-desperate cases and so were western doctors even before the invention of antibiotics.
A stab in the guts would have been almost certainly fatal.
In post-apocalyptic settings you can assume the presence of "doctors" akin to what they had in the Far West, I presume.
[Answer]
A stab to the face (save the eyes) or scalp won't hinder your character's ability to run or use the arms. Sure the scalp bleeds like stink, but you know, that's what cautery irons are for. If blood loss isn't too great, could be running around within an hour or two.
Regardless of where the stab is, the primary factors in play will be luck and even more luck. A (relatively) clean wound that is quickly irrigated with (relatively) clean water and treated with (relatively) clean instruments and bandages will heal well enough on its own.
Getting up and moving again --- that will largely depend on how dire the need is to get up and move again. If your character is on the run or otherwise needs to get from one place to another, well, she'll get up and move.
So "realistically", your character can be stabbed just about anywhere that does not involve a great vessel or vital organ or needed tendon (Achilles tendon, anyone?) and heal without a well equipped modern ER / OR. People have been stabbing each other, biting each other, being attacked by predators and so forth for millennia and for some reason we still seem to be around as a species. Healing may not be ideal without proper care, but it does happen.
[Answer]
A relatively short and skinny blade would be the best tool to get stabbed with.
You'll want to avoid organs, so the abdomen is out. The arm would be a good place like someone suggested. Possibly the character was trying to protect another part of his body and blocked the knife with his arm or fore arm. As long as you avoid the under arm area, because that's where major arteries run and if those are punctured it would most likely mean death.
The thigh is another good place. It's thick with muscle and being pierced with a smaller blade would probably be just a surface wound. The back of the leg though has major arteries and nerves that, if damaged, would require more than home treatments to fix. I also suggest looking at human anatomy diagrams to find ideal places to put this stab wound.
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[Question]
[
>
> Although the fossil fuel **coal** had been used as a fuel since 1,000 B.C., it wasn't until the arrival of the Industrial Revolution from the mid-1700s through the 1800s that coal began to replace biomass as the primary source of energy.
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It is evident that the Industrial Revolution also marked the beginning of an era where the world human population began to explode, along with energy consumption. I would say, it was from this point onward, that we saw the incredibly fast (in the grand scheme of things) development of technology; completely changing the way humans live their day-to-day lives.
It is common knowledge that fossil fuels are non-renewable and that they are quickly diminishing. But what if fossil fuels never existed in the first place? Specifically coal, oil and natural gas.
**How would the development of modern technology have differed if fossil fuels never existed?**
[Answer]
On a whim, I visited [Wiki](https://en.wikipedia.org/wiki/Industrial_Revolution) and looked up its list of the defining technological advancements of the Industrial Revolution. I'll summarize what might have happened to that list from the perspective of coal not being present.
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> Generally, without hydrocarbons, the industrial revolution would have been delayed and the global power brokers might be different. But, ultimately, it would have happened anyway. There's nothing you can do with coal, oil, or natural gas that can't be done with something else.
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Please bear in mind that at the same time the Industrial Revolution took place, so did substantial advancements in chemistry and electricity — including Faraday's discovery of electrical generation. By itself, wind- and water-based electrical generation combined with the use of motors would have replaced most of the industrial revoution's advancements. (I don't count solar electrical generation as solar panels weren't invented intil the 1950's. Even with scientific pressure from the loss of hydrocarbons, it's unlikely — impossible IMHO — that they would play any roll in an industrial revolution.)
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> The technologies that would be most impacted by the loss of hydrocarbons are (a) those depending on heat (especially those that require a lot of heat over a large area) and (b) those depending on transportation.
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> Concerning (a): Electricity is great for creating a lot of heat in a small area and mediocre for greating a little heat in a large area, but it's lousy (at least back then) for big-heat-big-area problems. However, solar could replace big-heat-big-area fossil fuel solutions, making cloudy days very inconvenient, but it could be done. Non-hydrocarbon chemical reaction could also do it, and chemistry was a big part of the Industrial Revolution.
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> Concerning (b): transportation would be the most delayed aspect of development, waiting until either a chemical process, improved battery technology, or electrical distribution could replace the combustion engine.
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My conclusion, if you don't want to read through my list, is that the Industrial Revolution would have occured anyway, but it may have been 30-60 years late. Even hydrocarbon lubricants can be replaced by non-hydrocarbon solutions. Necessity being the mother of invention, the increased demands of population and industry would simply have sought solutions elsewhere. You can always overestimate humanity's collective wisdom — but you should never underestimate its collective genius.
Politically, the revolution would have basically occured among the same nations. The focus might have shifted to Germany rather than remaining in England (mountainous waterfalls would be an advantage); but, ultimately, it I believe it would still have been something born in Europe.
---
**Here's the list of technologies that defined the Industrial Revolution.**
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**Textile manufacture:** enhanced by automation. That automation was already well underway due to mater-driven mechanization. Easily attained with electrical replacements.
**Metallurgy:** is more difficult to achieve with electricity, but not impossible. It's a big-heat/small-area problem. Add to this solar heating or non-hydrocarbon chemical processes and most if not all of the value of fossil fuels can be replaced.
**Steam power:** suffers greatly as does the transportation that is powered by it. Machines that depend on a fixed-location motor can be driven by electricity. But mobile engines like trains won't come to pass for a long time (see Transportation (Railroad), below). However, somebody would be thinking about how to do this almost instantly. Once a more-powerful-than-my-horse motor (chemically or electrically powered) comes into existence, inventors across the world would be looking for ways to make it mobile.
**Machine tools:** Like textiles, would suffer almost not at all as they are as easily driven by electric motors as by steam.
**Chemicals:** This important aspect of the Industrial Revolution would be impacted little by the loss of fossil fuels. In fact, the development of chemicals and chemical processes might actually have been enhanced by their lack. Chemical batteries would have been very high on the list of developments. Also high on the list would be chemical reactions that could produce any form of motive force. Chemistry, alone, may have replaced fossil fuels; it simply would have required more time.
**Cement:** Not impacted by the lack of fossil fuels other than due to transportation.
**Gas lighting:** Wouldn't exist, but would be quickly replaced by arc lighting followed by filament lighting.
**Glass making:** Would be affected moderately due to the heating problem identified above. If solar heating couldn't fix this problem then it might have been overcome by converting the original sheet glass process to one that could use high-heat/small-area solutions.
**Paper machine:** Probably unaffected other than transportation. This remarkably important contribution to the Industrial Revolution would still happen.
**Agriculture:** `The British Agricultural Revolution is considered one of the causes of the Industrial Revolution because improved agricultural productivity freed up workers to work in other sectors of the economy.` And the British Agricultural Revolution had nothing to do with fossil fuels. It would have been unaffected and its value toward the Industrial Revolution in general untarnished.
**Mining:** While electricity might have replaced steam engines, delaying but ultimately not affecting the mines' contribution to the industrial revolution, the fact that one of England's biggest mining operations at the time was coal means the focus of value would have shifted elsewhere.
**Other developments:** `Other developments included more efficient water wheels, based on experiments conducted by the British engineer John Smeaton the beginnings of a machine industry and the rediscovery of concrete (based on hydraulic lime mortar) by John Smeaton, which had been lost for 1300 years.` Neither of which would have been effected by the loss of fossil fuels.
**Transportation (Canals):** It's the building of canals that would be slowed for the lack of steam-powered tools, but they would eventually be replaced by electric tools. The value of the canals would remain intact.
**Transportation (Roads):** Again, the building of roads would be slowed, but the value of roads would remain intact — although their ultimate value would not be realized until either battery technology or chemically-induced motive power could replace steam and, later, gasoline.
**Transportation (Railways):** This is the big one. Steam could move mountains. It could eventually be replaced by electricity, but only after an energy storage system or energy distribution system could replace combustion engines.
[Answer]
Without fossil fuels our civilization would have lacked a cheap and widely available energy source to boost its growth.
Using biomass as energy supply immediately lowers your available resources, and cut off some regions from developing. So, unless you aim to create a world wide Easter Island, this is a no go.
Solar energy can be used at most for warming some water. With no fossil fuels smelting silicon to make solar cells is nothing more than a dream.
Wind energy is a bit more versatile (as the Netherlands show), but it is not programmable and also heavily location dependent.
Nuclear energy is hard to discover if you lack the ability of extracting radioactive atoms, which again requires quite some energy.
Probably we wouldn't have developed further than late Renaissance if it wasn't for fossil fuels.
[Answer]
Fossil fuels are central to the way we actually booted our Industrial Revolution.
Without them the path we followed simply wouldn't be there.
It is difficult to "foresee" (strange word, when applied to the past ;) ) what would have been the path in that case. A few considerations apply:
* Oil is used as raw material for chemical industry, not only as fuel; that part of chemistry wouldn't exist altogether.
* Energy, however, is the main concern and the *only* concern for all XIX century (at least).
* Missing fossil energy sources we would have had to resort to renewable ones:
+ Wind power is somewhat unreliable, in most places, but technology to tap it is age old and fairly reliable in certain places (e.g.: Netherlands, Aegean sea, etc.)
+ Solar power has had scant development till recent times, but it's well known since ancient times ([burning glasses](https://en.wikipedia.org/wiki/Burning_glass)); again this would have worked at its best in specific areas (surely *not* in Britain!).
+ Water power is another energy source well known and exploited since B.C. times; while more widespread than other forms of energy it is low concentration... until some serious electrical power plant is devised.
* Northern Europe would be penalized by lack of coal (which fueled its development) and sun power.
* Sun power is the only kind of energy that can be directly used for metal smelting.
* Most likely most of "Industrial Revolution" would have happened in north Africa and, later, in west U.S. where we get high-quality solar power and nearby iron mines (I'm nor speaking about the East because I don't know it's conditions enough).
* This Revolution would have had Ferrous Metallurgy at its core like our history, but the fuel, after dropping wood charcoal due to disappearance of forests, would be large mirror arrays
* Most likely this would have brought to invention of Bessemer converters earlier, since integrating carbon while smelting was not an option.
* As [hydropowered water mills](https://en.wikipedia.org/wiki/Ferrous_metallurgy) where known since dark ages (at least in Islamic Spain) places where both solar and water energy fonts would be available would flourish.
* All this means factories would concentrate in "suitable places", scattered around the globe, as transportation of energy would be (for the time being) unfeasible.
* Sailing ships would continue dominate the oceans.
* As soon as technically feasible electrical power would be pushed to maximum extent as the only one "easy" to transport over long distances.
* Electrical power plants would be hydroelectric, at least at beginning, with some Windmill converted to generator.
* Aviation would have been confined to aerostat for long periods.
* Far-East "heavy duty" kites would be in use for some time for observation and transport.
* The above would have lead to kite-powered sail ships, much faster and maneuverable than "normal" ones.
* Widespread usage of electrical power would have fueled all "modern" industry.
* Geopolitics could have been very different, though.
[Answer]
**No Fossil Fuel, No Problems (sort of)**
Wood can be converted to charcoal, which [burns hotter](http://www.differencebetween.com/difference-between-charcoal-and-vs-coal/) and cleaner than coal. Trees, as a renewable resource, could provide a reliable and steady input for industrial processes. It is, however, more expensive and difficult to acquire than coal (e.g. you have to grow trees, then cut them down, dry them, burn them in a kiln to create charcoal.) This [site](http://www.supremecarbon.com/metalbriq.htm) says
>
> Wood charcoal was used in iron production up to about 1750. Charcoal
> works well but it would be too expensive to use in steel making. It
> takes about 100 kg of woods to make only 1 kg of steel.
>
>
>
Furthermore, [wood](https://en.wikipedia.org/wiki/Wood_gas) and other [biomass](http://methane%20from%20biomass) can be used to create a replacement for gasoline and natural gas. [Alcohol](https://en.wikipedia.org/wiki/Alcohol_fuel) can also be used a motor fuel, and it can come from several different crops.
**Impact**
But none of these would be as cheap or easy as a fossil fuel. Because of this, steel and iron would be very expensive.
* Automobiles would be expensive so only the wealthy, corporations and governments could afford them. Additionally, their range would be lower, since the energy density of these fuels is less than gasoline.
* I would expect to see most electricity generation from hydropower, solar and geothermal. Wind turbines would consume way too much steel for them to be cost effective. I would expect large smelting/metal-working complexes to spring up near the dams, so as to make use of the electricity produced to smelt and forge various metals.
* Technological progression would be slower, as raw materials are harder to come by. It's hard to play with a motor when a block of iron costs a two years wages.
* Land use would be a serious constraint. With the production of so much charcoal and crops for alcohol in addition to food, I would expect much more arable land would be in use than is the case today.
* High rise buildings would be much rarer since their costs would be significantly higher.
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[Question]
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I have designed an alien species similar to octopi (Tetrapus Sapiens) who live in the tropical waters of a fertile, lush world known as Iridia. The octopi (more like tetrapi) have moved past the hunter-gatherer stage of technology and are currently at a technological level similar to the first Mesopotamian civilisations or ancient Egypt, having devised a writing system of carving, similar to early human civilisations. They have mediocre knowledge of mathematics and science, having devised many diverse languages. Their IQ is 92 (human average 100) yet their EQ is much lower at 73. 'Oral' communication is achieved through colour change, just like cephalopods here on Earth. Tetrapi are highly fond of universal education and discrimination is minimal. Technological progress is relatively fast as they simply cannot understand the concept of strict religious adherence, although they do worship a 'mother' goddess. They also have an 'electric' sense to seek out prey and superb vision in the visible spectrum. Lastly, they have mediocre smell, superb touch, and hearing a bit sharper than humans' though their range is 5hz-10khz.
Note: I want every possible communication system that can be mutually used between Homo Sapiens and Tetrapus Sapiens able to convey complex ideas.
[Answer]
## Language is hard
Figuring out how to communicate with other people is a very difficult problem. Linguists traditionally call this the "gavagai problem", after an early example.
>
> Suppose a linguist has made first contact with a previously unknown group of humans. She wants to understand their language, so she points to a rabbit and makes a questioning noise. One of the natives responds "gavagai".
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> Now, what does "gavagai" mean? Does it mean "rabbit", or "mammal", or "food", or "fur", or "brown", or "animal", or "small", or even "what?"
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With aliens, the problems become even worse. Pointing at something is a fundamentally human gesture, but perhaps for the tetrapods it means something entirely different: say, pointing their arms at something means their head points in the opposite direction, and you're supposed to follow their head, not their arms. With aliens, we have *no* shared means of communication, not even facial expressions.
## Start with mathematics
After observing the tetrapods for a while, the humans would undoubtedly notice the complex color changes used to signal. Analysing these would give us an estimate of their visual range, which is conveniently similar to ours. So visual communication is probably the best option, since both species seem to use it.
The humans would start by sending a message with some sort of mathematical pattern in it. For instance, they might write this on a piece of plastic:
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> ..
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> ...
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> .....
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> .......
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> ...........
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> .............
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If the aliens had any mathematical knowledge, they would recognize the series of prime numbers. That would make it clear we were trying to communicate with them, since this is unlikely to happen by accident. Then we would wait for them to make the next move.
Once we'd established communication, we might move up to pictograms: a drawing of a rock placed next to a rock, a drawing of a plant placed next to the plant. And from this we could begin to learn their native writing system (if we could express that we wanted to know the word for "rock" or "plant").
Since our knowledge is more advanced than the aliens', and (if I understand correctly) our intelligence greater, we would probably be the ones to learn their language, rather than the other way around. Communication would take place through written messages or, eventually, simulated color changes (if the humans designed an LCD wetsuit or the like).
[Answer]
**Braille.**
[](https://i.stack.imgur.com/pxS8J.jpg)
[source](http://1.bp.blogspot.com/-SAYkYxrDOjw/VN0GsP2pSCI/AAAAAAAAABQ/ci3V0GZEyL0/s1600/Fingers_reading_braille_Credit_RNZFB.JPG)
Your tetrapi have excellent sense of touch. I bet that is how they read their carved letters. Humans initially carved letters because they were more permanent but this is even more important for an aquatic species.
I like very much the idea of the tetrapi loving Braille and especially leveraging their societal math capabilities up with the concepts intrinsic to number depiction - consider the benefits of the number 0, which the Romans could easily have understood but had not invented. The humans will all need to learn to read Braille.
This idea has lots of scifi ramifications as the tetrapi take the possibilities of Braille off in unexpected directions.
I am puzzling over "many diverse languages" when the basic mode of communication is color change, which one would think would carry with it intrinsic meaning. I suppose patterns, color, speed and sequence make up the language. That will be a harder one for humans.
I worry that attempts to translate human sounds into vibratory or electrical signals, while certainly possible, would not easily address the place in the tetrapods brain where language is and while they might learn to understand it would be hard for them to speak.
[Answer]
If they use colour communication, then your humans need a waterproof tablet with a translation programme loaded onto it. The human speaks or types their message, which then is played on the screen as the correct series of colours and patterns. The tetrapus replies with colours/patterns and the tablet records it and translates it back into speech or text. Or the tetrapus can tap away at the screen to type a colour message.
At first contact stage, the humans will be taking photos/videos of the tetrapi and playing those back, until they have built up a vocabulary. This has the possibility of confusing the tetrapi, since they'll be seeing a person not just a message. *"Why are they continually showing us a picture of Freddipus shouting that he's seen an alien?"*
How fast, how accurate and how subtle your translation programme can analyse the colour pattern and provide a translation will depend on what sort of processing power you want your computer technology to have.
For the tetrapi to initiate this type of comms, they need to find a human with the translation app on their tablet. So they may learn to mimic the shape and colour of human symbols, to provide a cruder conversation. Emojis or short words like HELP or TALK.
[Answer]
Honestly, I'd start with something simple at first. Braille might work well between the Tetrapus, but it would be inefficient for humans to use to communicate with them. Not only would the humans involved need to understand Braille, which few sighted people do, but then the words written would need to match up to the understanding of a Tetrapus. Additionally, it would have to be the same style of Braille as we use, another sticking point. However, it could work fantastically down the line as they begin to understand the concepts of each other's language.
That's the big thing here, how does a Tetrapus view the world versus a human? As Draconis explained, two cultures with two very different languages could point at an animal and call it two different things. However, one may be defining it as something different than the other and thus you have a dissonance in the communication that you won't even realize until much further down the line. Granted, miscommunication like this can be great for world-building and tension. The key to communication would be for each side to slowly be able to understand how the other sees the world. You'll have to remember that it's not just the humans trying to communicate with the Tetrapus, but that whatever method is used the Tetrapus has to be able to experience the same steps to clarity as the humans.
I would simply go straight for pictures since they already communicate via color and sounds would be difficult, for a human, underwater. A movie that might help is The Arrival. It is NOT scientifically sound in all aspects, however, it's a good way to watch a step-by-step process unfold for figuring out how to interact with an alien species.
That's the key, step-by-step.
Electrocommunication is also an option upon the first encounter. It's relatively understood by humans and could at least be used to explain 'yeah we're not here to hurt you' by displaying submission or the like. They might even have the equipment on hand, depending on how they first find this new race. I don't know enough about it to preach a good basis, but it holds the possibility for a messy first try at talking to them.
[Answer]
Our understanding of human to non-human communication has a really long way to go. I'd recommend reading up on research about human-cetacean communication and see what you can use from that. <https://en.wikipedia.org/wiki/Human%E2%80%93animal_communication#John_Lilly_and_cetacean_communication>
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[Question]
[
Primordial Earth was buried in carbon dioxide. When life started, it was with algae using energy from the sun to crack the carbon out of carbon dioxide, with the byproduct of releasing the corrosive and toxic *oxygen gas* into the air. From there we get animals that use said oxygen, and so on with increasing complexity.
So, to get sapient species that breathe fluorine gas in a similar manner as we do oxygen, we must begin at the beginning, with plants. What compounds would need to exist in abundance on a primordial planet in order for a photosynthetic reaction that results in fluorine as a waste product to occur?
[Answer]
## Fluorine gas burns the ashes that other reactions leave behind
Given the absurd reactivity of fluorine, anything it comes in contact with will ignite. Attempting to develop a system of biochemistry, which requires long chains of stable links, on an element that burns everything it touches is an exercise in futility.
While it's true that oxygen *is* very reactive, it's unreactive enough at the temperatures that life currently lives that it's a useful oxidizer. Fluorine is *too* reactive. Fluorine gas reacts with carbon at room temperatures. Fluorine reacts with hydrogen very energetically (assumed at room temperature). Hydrogen plus fluorine plus water is hydrofluoric acid, an especially nasty chemical. At elevated temperatures, fluorine will react with noble gases and metals which *ordinarily don't react with anything!*
On Earth, fluorine is only found in minerals. What did appear in the atmosphere reacted with water or carbon di/mon-oxide almost immediately.
While there are some [fluoride metals](https://en.wikipedia.org/wiki/Fluorine#Metals), these metals don't appear to offer the complexity that carbon-oxygen-nitrogen-hydrogen chemistry does. As such, I'm highly skeptical that you could base biochemistry in an atmosphere with any substantial amount of fluorine.
## Fun Reading
* [Dioxygen Difluorine](http://blogs.sciencemag.org/pipeline/archives/2010/02/23/things_i_wont_work_with_dioxygen_difluoride)
* [Chlorine Trifluoride](http://blogs.sciencemag.org/pipeline/archives/2008/02/26/sand_wont_save_you_this_time)
* [Triazadienyl Fluoride](http://blogs.sciencemag.org/pipeline/archives/2008/10/21/things_i_wont_work_with_triazadienyl_fluoride)
[Answer]
So..
How does our planet look like, first?
For some reason - and I really can't think of a good one, perhaps some extreme fractionation in a nebula - we have no oxygen around. Oxygen messes things up in this case. Instead we have Fluorine, which is always more fun.
So instead of rocks, we have Silicon fluoride rocks (Si(n)F(2n)F2). Instead of oceans of water, we have oceans of HF. And instead of an oxygen atmosphere, we have a Fluorine atmosphere. The surface temperature would be something like -100 degrees centigrade - this does help by lowering reaction rates.
Organic chemistry is hard in this environment. It would have to be based around Carbon-Fluorine polymers, which would be stable, as opposed to our Carbon-Hydrogen-Oxygen polymers, which would react violently. Presumably some trace oxygen and nitrogen would have to be available to allow more diverse chemistry; the interior of cells would have to do a lot of work to avoid the HF destroying everything.
The equivalent of CO2 in this world would be CF4 gas, which would be reacted through photosynthesis into C(n)F(2n) polymers with F2 being released. This is one of the more straightforward parts, although you'd want very high energy wavelengths of light to drive it, so perhaps our plants would look red rather than green.
One thing I would not want to do is try and land on this planet..
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[Question]
[
**Is this even remotely possible?**
[](https://i.stack.imgur.com/l1sNM.jpg)
[Source](http://flowergarden.noaa.gov/image_library/coral/coralpolypsgps.jpg)
**Outline:**
1. Coral Polyps (along with their copious Calcium Carbonate excretions) are the individual organisms that make up the super-organism we identify as coral.
2. They reproduce by budding asexually to form one coral structure.
3. However, at certain times they release eggs and sperm into the water to float away and create more coral structures.(some exceptions)
4. To feed, they usually open up their tentacles and wait for prey animals to run into them, this is when they release harpoon like barbs from tiny structures called nematocysts, which release toxins into the prey and firmly holds it in place.
5. Many also have a symbiotic relationship with photosynthesizing algae
**Thoughts:**
First of all, the Polyps don't really need to have an efficient way of spreading themselves, their helpful human friends from Evil Inc. will be assisting them with this. They therefore only need to be able to survive when injected directly into the human bloodstream, and be dramatic about it, if possible. It should eventually be lethal, as well: the more gruesome the death, the better!
[Answer]
# Probably not
To be strictly science based, I don't think this is likely. The reason has to do with the size of the coral's larval form, which is what I assume has to be injected into a person. A coral [planula](https://en.wikipedia.org/wiki/Planula) is in the 1mm range. Here is a study on *Pocillopora damicornis* where the planula are from 1.03-2.46 mm in length and .21-1.44 mm in width.
By comparison, going down a [CDC list](https://www.cdc.gov/bloodsafety/bbp/diseases_organisms.html) of common blood parasites, we see that *Trypanosoma* (chagas, sleeping sickness) [that affect humans](http://parasite.org.au/para-site/text/brucei-text.html) max out at about 30$\mu$m; *Plasmodium* (malaria) [about 15 $\mu$m](https://microbewiki.kenyon.edu/index.php/Plasmodium); Leishmania (Leishmaniasis) [up to 14 $\mu$m](http://parasite.org.au/para-site/text/leishmania-text.html).
So your blood parasites are 10 to 100 times smaller than your larval coral. Why does this matter? Well, small size allows these parasites strategies for evading white blood cells that are not available to larger creatures. Malaria hides out in red blood cells; Trypanosomes rely on rapid multiplication and mutation to develop an antigenic membrane that is resistant to white blood cells.
Being much larger, a planula won't have either of these options available to it. The human body does have specially designed white blood cells ([Eosinopils](https://en.wikipedia.org/wiki/Eosinophil)) designed to attack larger parasites. These cells use a variety of highly reactive anioins like hydrobromite or peroxide to attack the cell membranes of larger parasites. If the parasite can't multiply and evolve quickly to resist the attacks of the host, it will be wiped out.
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Edit:
I was mistaken in identifying several worm-type parasites as gastro-intestinal parasites and ignoring them for this analysis. As @JDlugosz points out, the *Schistosoma* worms are larger; much larger than the coral polyps, infact. [*Schistosoma mansoni*](https://en.wikipedia.org/wiki/Schistosoma_mansoni) is around 1000 x 100 mm in size; which is not only larger than the planula but larger than some adult polyps as well.
That species of worm resists attack by white blood cells by coating its 'skin' with anti-oxidant proteins to protect it from the extremely reactive free radicals the body's defenses attack with.
So there is a precedent for larger organisms in the human bloodstream.
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Coral polyps may not need to be genetically modified to become lethal. Toxins from coral spores are already deadly. This was demonstrated [recently](http://www.abc.net.au/news/2017-05-02/aldinga-family-poisoned-by-coral-spores/8488910) when a family of seven were poisoned by toxins from coral spores released from an aquarium in their house.
>
>
> >
> > A family of seven living just south of Adelaide is in hospital because of suspected poisoning from spores released by coral from a
> > household aquarium which was scrubbed with a cleaning brush.
> >
> >
> >
>
>
> Ambulance crews were called to the house on Sunday Parade at Aldinga
> Beach, about 2:30am, when the residents fell ill.
>
>
> They were taken to Flinders Medical Centre and remain in a stable
> condition.
>
>
> Decontamination crews have worked at the home throughout the day.
>
>
> The Country Fire Service (CFS) and police were then called to the
> scene, which has been cordoned off.
>
>
> The CFS said it traced the problem to the aquarium because of what the
> family members had said and the symptoms they were displaying — mainly
> breathing problems.
>
>
> "Those two together [we] worked out that it was the spores [from the
> coral]," CFS regional officer Peter Phillips said.
>
>
> "It would appear that in trying to clean the coral, they've taken it
> out of the aquarium and scrubbed it with a brush and that's liberated
> the spores."
>
>
>
To give an indication of how dangerous this situation was: --
>
> Three hazardous materials removal teams are on site, wearing
> protective suits and breathing gear, each working in 20-minute shifts.
>
>
> Marine ecologist Ivan Nagelkerken said coral products sold in aquarium
> shops could contain toxins which could be life threatening.
>
>
> "When people start cleaning their aquaria and damaging these flower
> corals that's when the toxicants are released," he said.
>
>
> "For example if people have a cut in their hand or if there was one
> case of somebody cleaning their tank with boiling water and the toxins
> entered the water vapour, then the effects can be really harmful."
>
>
>
The mechanism employed by coral spores is [explained](http://www.abc.net.au/news/2017-05-03/how-toxic-coral-spores-can-poison-aquarium-owners/8492398) thus:
>
> Aquaculture farmer Peter Fullerton told ABC Radio Adelaide's Drive
> program that certain corals released toxins as a defence mechanism.
>
>
> "You can have desirable corals that are colourful and ones that are
> less colourful, so sometimes people decide to clean out the
> undesirable colours."
>
>
> He said some of the most toxic coral was found in the zoanthids genus.
>
>
> The toxin is called palytoxin (PTX) and can cause severe respiratory
> reaction, haemorrhaging and death to humans if ingested.
>
>
> Mr Fullerton said he had known of a few aquaculture farmers who
> suffered bad reactions after being squirted in the eye by the juice of
> coral.
>
>
> He recommended aquarium owners wear eye and hand protection when
> handling coral to ensure toxins were not transferred.
>
>
>
This means that there are coral genus that produce deadly toxins. If genetic modification is required, then it should be of a kind that enables the coral spores and organisms is expel their defensive poisons to attack people and other creatures that feed on the corals.
Assuming many more corals could be equipped with similar toxic defense mechanisms could make reefs into hazardous and lethal environments. The basic mechanisms are there, if they can adapted and transplanted into the majority of corals then this could achieve the result you want in making corals deadly. This may not be what you had in mind when you wanted to make corals pathogenic.
[Answer]
**Cnidarians yes, corals probably not**
If a coral was going to become parasitic, it would probably be a "soft coral" without a calcite skeleton (these kinds of corals do exist). Kind of like a sea anemone (which are close relatives of corals), and there are actually *are* parasitic sea anemones. Losing the shell is something seen in a lot of parasites that evolve from hard-shelled organisms, like [shipworms](https://en.wikipedia.org/wiki/Shipworms) (which sort of parasitize ships) and *[Sacculina](https://en.wikipedia.org/wiki/Sacculina)*. Soft bodies means it's easier to wriggle around inside the host.
The big issue would be acidity. Human blood has a pH of 7.35-7.45. The average ocean pH today is 8.1, and prior to the industrial revolution was 8.2. That tiny little shift in pH is causing mass coral bleaching, where the single-celled symbiotes that allow corals to photosythesize are ditching the corals and the corals are having trouble building their calcium carbonate endoskeleton. Most organisms with a calcium carbonate skeleton aren't very active and it's been suggested that the variations in physiology associated with high activity (i.e., lactic acid) erode such skeletons, making calcium phosphate (like us) or chitin/chitin with calcium carbonate (mollusks, arthropods) a better bet. The problem your parasitic coral has to face is that it is getting calcium from an acidic, metabolically variable environment (human fluids).
[Answer]
Look at [Schistosomiasis](https://en.wikipedia.org/wiki/Schistosomiasis) as a model. Basically make your polyps do everything the Schistosoma is described as doing, changing the parts you want specifically different.
It makes sense that the creators would model it after real pathogens that are large.
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It's 2020, carbon emissions are in decline but not fast enough. Oceans continue to rise at an increasing rate, so a plan is proposed to cut ALL carbon emissions:
Cover the moon in solar panels (take the center of the moon to be the origin, then the solar panels follow the planes: x=0, y=0, z = 0, where they intersect with the surface of the moon), so that at any given point in time (outside of lunar eclipse) they produce electricity. However there is a problem, how can the electricity be transferred from The Moon, to Earth, where it is needed?
Assume the electricity can be stored for a limited amount of time on both The Moon and Earth, so continuous electricity transfer is preferrable, Ideally efficiency of transfer over 50%, and to be economical for the long term.
[Answer]
There are actual plans to collect solar energy from space and transfer it to Earth. I recommend reading about [Space Based Solar Power](https://en.m.wikipedia.org/wiki/Space-based_solar_power), or SBSP for brevity.
The moon would not be the best choice for a collection base because A) eclipses and B) you'd not use more than half of its surface for collection at any given time, with most of your collecting surfaces at bad angles. You'd get more value for your money by having all those surfaces in space, orbiting the Earth, so that they can aim their panels at the sun.
As for the transfer proper, just have each satellite aim a tight beam of microwaves at the Earth and collect it with huge dishes. Microwaves can get into the atmosphere with little loss. An depending on the power setting they should collectively give enough energy that the dishes on Earth can power whole cities, but people hit by the beam will be receiving less radiation than they already do from their cell phones ans routers.
The Simcity series of games has had this kind of power generation ever since Simcity 2000. It was always one of my favorite power plants.
[Answer]
The common solution for power transmission in space is microwave power transmission:
<https://en.wikipedia.org/wiki/Microwave_transmission#Microwave_power_transmission>
It is not perfect, but quite efficient.
Since they want continous power, they would need three relay satellites on geostationary orbit, spaced 120 degrees apart (on of them will be always in line of sight with Luna, and they will always see each other.), to recieve the microwaves, and beam them down to the planetary surface.
There are problems, of course: these systems will have magnitudes higher power and range than current devices, airplanes have to avoid the beams, waste heat is to be radiated away from the relay satellites, regular maintenance is needed...
But nothing unsolvable for a civilization, which is able to cover the Moon with solar panels.
[Answer]
You could use the electricity on the moon to mine and refine helium-3.
<http://www.popularmechanics.com/space/moon-mars/a235/1283056/>
Helium-3 is hard to get on earth but it is present on the moon,. in surface dirt. I was wondering why it would not float away but of course helium would not be buoyant on the moon. In the linked article it states that available helium-3 would make fusion power safer and easier. Fusion power is what we need.
1: Use the solar energy to massively mine moon for helium-3. Worry very little about environmental impact.
2: Concentrate helium-3 into cylinders.
3: Launch cylinders back to earth with a (solar-powered!) electromagnetic mass driver.
4: Use helium-3 to make safe fusion power plants.
5: Power flying Delorean (flown by myself) with one such device. Cursed1701 I will let you borrow it to impress your date.
I see in looking for a source for the mass driver (as described in Heinlein's Moon is a Harsh Mistress) that the helium mining scheme exactly as I describe here was done in a movie called Moon - a movie I had not heard of but which I now intend to watch.
<https://www.spaceanswers.com/futuretech/lunar-mass-driver-why-we-should-build-a-space-gun-on-the-moon/>
<https://en.wikipedia.org/wiki/Moon_(film)>
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What is a possible way of making Venus more habitable by getting rid of at least some of the thick atmosphere and thereby lowering the pressure and heat.
At this point all I can think of is some sort of massive explosive event like a big asteroid or a nuclear weapon. But it just doesn't seem enough unless it's big enough to destroy the whole planet.
I'm not thinking in terms of strolling around outside breathing air, but habitable enough to do some industrial mining in suits and domed communities.
There are questions already on terraforming Venus, but I don't see any remotely feasible answers that would make it habitable in the way earth is before our species went extinct. So my question is really about partially terraforming for the sake of exploiting it's minerals and metals.
Assume expense isn't a problem and space travel has become relatively easy throughout the solar system due to a new fuel which is rarish elsewhere but abundant on Venus if we can just get our hands on it.
Perhaps an enormous asteroid didn't impact but instead just missed actually passing through the atmosphere? I'm happy with a lucky natural event that allows humans to exploit Venus. Bonus if it speed up the rotation. Whatever fluke would be needed is fine, because the 'real life' earth is an incredible fluke.
[Answer]
Most of these answers are relatively "small potatoes" in terms of terraforming. Playing around with asteroids, sunshades, nuclear explosions etc. can certainly do the job, but take decades to centuries of work, and when you get down to it, Venus will still be blisteringly hot du to insolation, have very little water and a long, retrograde day (the sun rises in the West and Venus rotates once every 243 Earth days. Daylight savings time is not likely to be an issue on Terraformed Venus!
A researcher named [Paul Birch](https://infogalactic.com/info/Paul_Birch_(writer)) developed an amazing scheme which solves a number of these problems at once. Using a stream of high speed particles launched from an accelerator ring orbiting the sun to transfer momentum to the target planet (Venus is only one instance where it could work), the planet could have its rotation and orbital parameters adjusted to your liking.
The paper "[Terraforming Venus Quickly](http://orionsarm.com/fm_store/TerraformingVenusQuickly.pdf)" outlines this plan in greater detail. Using devices called "light sail windmills" to provide the energy to accelerate the pellet stream, and a giant sunshade to cool the planet, an ice moon from the Jovian system could be moved out from Jupiter and crashed into Venus to supply an ocean's worth of water. Applying the pellet stream energy directly can set up a more suitable rotational period for Venus ([How to spin a planet](http://buildengineer.com/www.paulbirch.net/SpinAPlanet.pdf)), and the planet can be moved to a larger orbit where there is less insolation ([How to move a planet](http://buildengineer.com/www.paulbirch.net/MoveAPlanet.pdf)).
To give you an idea of the scale of this plan, moving Venus could take ~30 years and require harnessing .2% of the Solar luminosity during that period. While moving and spinning a planet in 30 years certainly makes the project achievable in the lifetime of an engineer working on the project, I suspect the planet will be quite unstable and wracked by earthquakes for decades if not centuries due to the stresses induced upon it.
Since Terraforming is, by definition, making a planet more Earthlike, then applying fabulous amounts of energy and moving the planet into an Earthlike orbit and spinning it up to an Earthlike rotation should be non negotiable.
[Answer]
The two main problems with Venus is the heat and the high content of carbon dioxide in the atmosphere.
In the future there may be a way of devolving carbon dioxide into its constituent Carbon and Oxygen, which are a lot more friendly. Right now, it's a difficult process (as illustrated by our esteemed [Chemistry Stack](https://chemistry.stackexchange.com/questions/915/how-to-convert-carbon-dioxide-into-carbon-and-oxygen).
>
> Yutaka Tamaura and Masahiro Tahata, Complete reduction of carbon dioxide to carbon using cation-excess magnetite, *Nature*, **1990**, *346*, 255-256, [[DOI][1]]
>
>
> they heated magnetite ($\text{Fe}\_3\text{O}\_4$) at 290 °C for 4 hrs in a stream of hydrogen to yield a material which turned out to be stable at room temperature **under nitrogen**. This material, $\text{Fe}\_{3+\delta}\text{O}\_4 (\delta=0.127)$, i.e. the metastable cation-excess magnetite is able to incorporate oxygen in the form of $\text{O}^{2-}$.
>
>
> Under a $\text{CO}\_2$ atmosphere, the oxygen-deficient material converted to "ordinary" $\text{Fe}\_3\text{O}\_4$ with **carbon deposited on the surface**.
>
>
>
However, the heat of Venus might help overcome that difficulty (the surface of Venus has a mean temperature of 460 °C)
Lowering the concentration of $\text{CO}\_2$ should in theory negate the runaway greenhouse effect and remove some heat making the environment a bit more friendly to work in.
[Answer]
One scenario I have heard is to seed the upper atmosphere with [photosynthetic](https://en.wikipedia.org/wiki/Cyanobacteria) and [chemosynthetic](https://en.wikipedia.org/wiki/Chemotroph#Chemoautotroph) bacteria or archae that would break down the carbon dioxide and sulfur in the atmosphere, respectively. The large amount of sunlight would have the photosynthetic bacteria grow and the thick atmosphere would help both organisms stay airborne.
Perhaps you could start with [bacteria](https://en.wikipedia.org/wiki/Deinococcus_radiodurans) or [archae](https://en.wikipedia.org/wiki/Thermococcus_gammatolerans) that are highly resistant to acidity, temperature, and radiation. Then you could splice in genes for photosynthesis into one group and sulfur-eating into another. You wouldn't want to splice both into the same cells because then the cells would use whatever is most readily available rather than consuming both at the same time.
This would result in lower temperatures (due to a reduced greenhouse effect), less toxic atmosphere, breathable oxygen, and clearer skies. However, it may take too long for your scenario.
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[
The [Novgorod Republic](https://en.wikipedia.org/wiki/Novgorod_Republic) existed in northern Russia between 1136 and 1478. It was the easternmost point in the Hanseatic League, the north-western terminal of the Silk Road, and by all accounts immensely prosperous. It was a democracy with a very permissive suffrage (even lower classes could vote, though serfs could not) and high level of literacy.
Novgorod was too far north to suffer militarily from the Mongols, but it didn't help them much:
* They still had to pay tribute to the Mongols
* They were a target for Catholic crusaders from Sweden and the Baltics
* They were engaged in wars with the other Russian principalities, most importantly Muscovy (Moscow).
Novgorod had some success playing its enemies against one another, but Muscovy eventually grew too powerful. When Novgorod tried to ally with Poland-Lithuania, Moscow's ruler Ivan III declared war, defeated Novgorod's army, and crushed any hope of independence.
What is the smallest change that could avoid this outcome for as long as possible, without simply supplicating Novgorod to another overlord (Sweden, Poland-Lithuania, etc)?
[Answer]
I would recommend saving [Tver](https://www.britannica.com/place/Tver-historical-principality-Russia). Tver and Muscovy were significant regional rivals until the city revolted against Tatar rule and the Tatars sacked the city, from which it never recovered. If the Tatars were weakened earlier, they likely would have left Tver alone and faded more rapidly. Probably the best way to do this is simply eliminate [Oz Beg](https://www.britannica.com/biography/Oz-Beg). This would weaken the Golden Horde significantly, considering his prominence, eliminate his favor of Moscow, and save Tver.
Thus, entering the 15th century we could still have a delicate balance of power between a Muscovite-Novgorod alliance and a more powerful state of Tver that gained more Golden Horde lands. As the 15th century arose, ally Novgorod with Lithuania- but this time, the Muscovites cannot take action because of their need to fend off Tver, while meanwhile the Lithuanian-Novgorod alliance defeats the Teutonic Order at the [Battle of Grunwald](https://en.wikipedia.org/wiki/Battle_of_Grunwald) leaving Novgorod in a strong position, probably with more Baltic lands.
After that it easily becomes more hazy, but modifying history to eliminate Oz Beg and still allying Novgorod with Poland-Lithuania is probably going to at least put them in the position as a dominant state in Russia at the turn of the 15th century.
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Background:
By spreading themselves too thin, and then through a series of events the current mono theistic gods accidentally kill themselves. (This is very sad, and I don't wish to offend anyone who was fond of them.)
So now like after a forest fire, many small gods are sprouting up.
These new gods are very similar to the Greek and Roman gods.
They epitomise facets of human nature (love, war, etc), technology (farming, harvest, writing, music , pottery etc), and nature (the sea, the forests etc).
So! **What would be some interesting gods to have in our modern world?**
For example a modern god may be a god of fashion. He/She may help with inspiration or help a faithful new designer with a chance meeting with a fashion magazine editor etc. They could also be fickle and decide they don't like a designer anymore or go out of their way to impede a label if the owner became too prideful or something.
[Answer]
There are many new developments that weren't known to the original polytheistic religions, and so are crying out for some deistic oversight. New positions which need to be filled include:
* God of Genetic Modification
* God of Nuclear War (distinct from the god of Conventional War)
* God of Space Travel
* God of the Internet (perhaps he's the one who converts Facebook likes into food for the poor)
* God of Transport (covering everything from cars to planes)
* God of Hedge Funds
* God of Television
* God of Coffee
* God of Football (who is worshipped differently in the United States than anywhere else)
[Answer]
I think it was in the [*Thursday Next* books](https://en.wikipedia.org/wiki/Thursday_Next) that there is a goddess *Pecunia* for a cult that literally worships money. If you are turning human nature into anthropomorphic personifications (like happens in [*Hogfather*](https://en.wikipedia.org/wiki/Terry_Pratchett's_Hogfather)) this would be a natural, playing off the existing behavoir of those obscessed with wealth.
Speaking of *Hogfather*, you really need to [read some Diskworld](https://en.wikipedia.org/wiki/Discworld_gods).
>
> Gods on the Discworld exist as long as people believe in them and their power grows as their followers increase. This is a philosophy echoing the real-world politics of the power of religion and is most detailed in the novel *Small Gods*. If people should cease believing in a particular god (say, if the religion becomes more important than faith) the god begins to fade and, eventually, will "die", becoming little more than a faded wispy echo.
>
>
>
This is the same idea as you are contemplating. The article goes on to give a fairly long list of ideas for you, though Pratchett was writing humorous saterical reflections of aspects of society.
[Answer]
You could have a handful of Gods of war, each with a different angle, maybe even warring between themselves for top position. I'm thinking digital warfare, guerrilla, autonomous, 'physical' combat, terror and any others.
There would probably be a god of data and information, protecting ones privacy. And many more smaller gods of digital technology like signal gods, battery gods, the god that can protect your phone if you drop it.
Then the gods of luxuries: food, travel (and fashion and money that have already been said) for example. At the moment maybe the gin and whisky gods are jostling for the position once held by Dionysus
Gods giving inspiration and reliable sales for music, movies and books.
[Answer]
For new gods I would look at what things all humans have in common in this day and age. You have some old gods returning like the god of time god of death Exedra but you would also have new gods like the god of the internet for example. Maybe the god of travel, look for things that all humans having common regardless of culture or nationality.
Few more ideas
1. New superhero God.
2. A god of video games
3. The god of sports.
4. Some sort of nucular god.
5. A god of the internet and communication.
6. The god of travels and travelers.
7. A got a space and space travel who watches over those who Traverse the void between plants.
8. God of invention who inspires engineers to create new things.
A god of wealth and plenty
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[Question]
[
Due to low numbers of humans, the death penalty is forbidden and impractical as it would bring mankind to the brink of extinction.
All prison sentences are now changed to various forms of thralldom or outright slavery that a person has to bear for various years or an entire lifetime.
Technology became obsolete for various reasons, you have to develop new ways to keep these thralls and slaves from running away from harsh service. Would normally ball and chain be enough or should these thralls be neutered by severing unimportant tendons etc. Severing Achilles tendons was a punishment for slaves who tried to flee.
Edit: "world" view on slavery is that it is "barely tolerated aberation" as @AlexP said but you cannot really run away from it as this group that has labelled these persons are only human group around. There are only about 5k humans around so there is need to keep all survivors alive even if they are killers or hostile to the main group in various ways.
[Answer]
Ancient Sparta was an interesting example of a society based on large scale slavery. Unlike the rest of Classical Greece, where slavery was an individual thing (i.e. you could choose to own a slave if you could afford one), and slavery itself was considered an unfortunate condition (being enslaved because your side lost the war, or sold to pay off debts and so on), Spartan *Helots* were enslaved as a conquered people, and property not of any particular Spartan, but of the Spartan State as a whole.
While this also had some pretty severe consequences for the evolution of the Spartan Polity (especially the rise of a permanent warrior class developed primarily to deal with slave revolts), the Spartans also had an extensive system of informants, fake incentives and even a ferocious secret police (the *[Krypteia](https://infogalactic.com/info/Crypteia)*)
So your society is likely to evolve in similar directions.
All able bodied freemen will be impressed into military service in order to provide the manpower to put down slave revolts. Slaves will be subverted so some will become willing stooges capable of informing on their fellow slaves to provide information. Sometimes, slaves might be "invited" to become soldiers or receive manumission; the ones which step forward are violenty punished or killed to ensure others don't get ideas above their station.
Finally, the *Krypteia* was essentially a cross between "Force Recon" and the Stasi, creeping around to observe the slaves when they didn't think they were being observed, taking notes and then swooping down to seize potential troublemakers and remove them from the rest of the population.
Of course the Spartites discovered that this was a policy of diminishing returns. As the Helot population grew and the farm income of the Spartan State increased, the Spartans were forced to redouble their efforts to keep the Helots down. Sparta evolved into a hyper militarized state, ritually declaring war on the Helots every year and with virtually no male citizens exempt from military duty and full time training. We know a lot about the Spartan military, but there is virtually no Spartan literature, arts, temple complexes or even Spartan colonies around the Aegean Sea. And of course, the Helots nurtured a simmering resentment, to the point Xenophon wrote "helots would gladly eat their masters raw", and several unsuccessful Helot revolts were recorded in history.
The Spartan advantage of extreme militarization kept them in power until after the Peloponnesian War, when Thebes, another land power, finally invaded Laconia under Epaminondas. He defeated the Spartans militarily, and then not only freed the Helots, but kept his army in Messenia long enough for the Helots to throw up fortified cities and gain enough training , weapons and equipment to successfully battle the Spartites on equal terms.
If there is no outside "power" to liberate the Helots, they may choose to revolt against their masters, but unless there is an overwhelming manpower advantage or they are led by some sort of military genius who can overcome deficits in training and equipment, success is not guaranteed at all.
[Answer]
# What does a slave do when he runs away?
Running away as a slave really isn't as easy as all that. By the time of the Civil War in the US, slaves running away via the Underground railroad had something to do when they ran away: they could work at the budding industrial enterprises of the north which needed labor. But for most most of history that was not an option.
Lets set the scenario. You are a slave on a Roman latifundia in southern Italy in the time of Augustus. You tend vines for wine-making all day. Your master whips you and steals your children and life sucks. You want to run away. **Where do you go?**
You were born on this farm, or one like it. There is no 'wilderness' to escape to in south Italy...or even in north Italy. You know how to tend vines for grapes, but you don't really have the knowledge of equipment to farm for grain for survival. Even if you did, there is nowhere to farm. All the land is owned by local peasants or settled veterans who would drive you off with pitchforks; or it is owned by senators from the city, who would just slap you in irons and make you a slave a gain. Your only hope of not starving to death is to join a band of brigands like Spartacus. Of course then you will die crucified...like Spartacus. **Maybe its better just to stay here?**
For most parts of history, there wasn't really an option to run away. If you were a slave imported to Baghdad from Zanj (East Africa) in the 800s, where would you go? The land is desert all around the river basin, so nowhere to survive if you escaped. Your skin color pretty much marks you as a slave if you go to a big city. You probably don't speak Arabic, and you probably don't have any craft skills worth a darn. Unless you can hire on as a sailor, there is a pretty good chance you will starve to death if you run away. Not great.
Most slaves in history probably didn't even need to be in chains. To be honest, for many free people in history, they may have been better off being enslaved. Freedom isn't much to give up if you are buying (limited) protection from war or famine.
[Answer]
Some people claim that native Americans were never made slaves because they just walked off into the woods. Supposedly, they were so accustomed to living in the wild that they had to be locked up.
Africans were made slave because:
1. They were instantly recognizable because of their skin color.
2. They wouldn't run off into the wilds.
BUT some authors report that slaves regularly ran away for vacations, and returned without any severe consequences because slave owners didn't want to discourage voluntarily returned slaves by punishing them when the came back.
Anyway, slavery is a practical solution to the fact that the only motor on a farm is muscles. In other words, to pick cotton, you need a lot of human hands if you don't have electric or gas powered motors. Your technology has to need muscle power or you don't have any profit in using slaves.
After all, slave revolts used to be the nightmare of the plantation system. Abuse of slaves, such as rape or torture could trigger a population of people that outnumbered you and your family to do things like put poison in the food they cooked for you, or throw your children down the well, or cut your throat in your sleep with your own razor.
Your may want to read some factual studies of slavery that are not trying to prove a political stance. Slavery was a complicated issue with some surprising outcomes. Did you know that a survey of freed slaves showed that 30% of them wanted to return to slavery? It seems that having the owner provide shelter, food, health care was attractive to some former slaves.
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The only way I can see this society working is if being a slave is preferable to not being a slave. What that means depends on your technology level, but there are some common threads you can pull at:
## Slaves are Fed and Cared For
Being a slave means having no freedom and being owned by another person, but it also means that person has an interest in keeping you alive (and to an extent happy or afraid enough to keep the status quo). Sure, they have to work hard for their food, but so do many independent farmers. The only difference is the fruits of their labors that don't go to food or shelter for themselves goes to the owner.
## Slaves are pitied, but are seen as men
These people are not enslaved because they are inferior, or because they are subhuman, they are enslaved because they broke the law, and are serving a penance to society. It is very important that people still see them as human beings. This will help those in charge of them be kinder and make it a more humane situation.
## The Alternative to Slavery is Bad
This is the "evil forest" idea. Make the slaves believe that the wilds will kill them, or some fate worse than death (slow starvation is an option). If they are being fed and cared for, the labor isn't terrible, and the overseers aren't cruel, there's little motivation or reason to revolt. Punishment for slave uprising should be extreme, perhaps being one of the few instances a death penalty is allowed to underline the severity of the crime. You could also welcome back runaways with forgiveness, and no increase in their sentence, but I think this sets a bad precedent for running away.
## There Should Be an End
There's a large difference in attitude between a slave whose whole life is going to be in chains, and one who knows they will eventually be freed. Even those sentenced to "life" should only be slaves for a period of time. If a group of slaves is going to revolt, someone who has a year left on their sentence is a lot less likely to help and more likely to inform on the uprising than those that have 10+ years remaining. You could also allow owners to reduce sentences for good behavior and the like, further encouraging cooperation.
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Depends on the details of your fictional world. However, these considerations should apply:
* If the society cannot afford to do without the *labor* of the convicts, it probably cannot afford to deliberately cripple them or to waste manpower on guarding them.
* This applies even more if modern technology is lacking. The majority of the population has to work in agriculture. Can prison farms raise enough food surplus to feed their guards? As a ballpark figure, it takes 10 farmers to feed 1 castle or town inhabitant.
In a cruel setting, the convicts could be branded to mark them and be sent to do hard labor. Perhaps a chain gang, not individual ball and chains, but even then it is questionable if the legal system can afford enough skilled metalworking for that.
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Simply tell the slaves that they will be tortured if they try to flee, and leave it at that.
To break them such that they stop trying to escape, set-up scenarios where they think it is safe to flee. Let them try, capture them, and then torture them. Further, use social engineering to get slaves to trust someone. Said person can convincingly explain an escape method and subtly encourage a slave to attempt it. Of course, upon an actual escape attempt have the person the slave trusted do the actual torturing.
Slaves will never be sure when it is safe to escape. The slave will never know who to trust. Pretty quickly, the slave will stop thinking about escaping.
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Or, technically, a civilization *near* the core of a planet.
In this question I will describe some aspect of my design, and you may comment on the realism of these aspects and add improvements, or point out something I am not aware of.
## The Planet
The planet will be a rocky planet, possibly tidally locked to its star so as to reduce the effect of rotation on the world within.
I am not sure what effect a major satellite would have on a civilization inside a planet, so there will be none for now.
The planet will either be too small or too old to have volcanic activities, and the layers above the level of the civilization will be solid. This also means the planet probably don't have a strong magnetic field, but this would seem trivial to a civilization living under many kilometers of rock. The core, however, is still hot enough to emit light and heat.
And just so you know, the world built here is supposed to be a bleak, end-of-time sort of place, so the "star" about which the planet revolves is probably a black-hole or something dark and useless like that.
## The architecture of the civilization
This is where things get a bit crazy. See diagram below (not to scale):
[](https://i.stack.imgur.com/0cx0g.png)
I hope the diagram is sufficiently self-explanatory. That being said, a few significant note with this design:
1. The support structure must be made from something that has a melting point higher than the temperature of the core's surface
2. Either the core is quite solid, so as to be able to handle the weight of the supports, or that the rocky crust is quite solid, and the support structure can anchor itself securely on the inner surface of the crust without putting too much weight on the core
3. The idea here is that the civilization derives its power from the light and heat coming out of the core, this means that the support probably wouldn't enclose the core completely, unless it is transparent (to permit the output of light).
4. There must be some way that the excess heat is disposed of. My idea
so far is that the universe itself has gotten quite cold at this
point, so the conduction of heat into the crust and its later radiation into space should suffice.
## Life in this world
The social aspect of this world is trivial at this point, however, life on the "residential area" would have the following major features:
* Gravity will be like the gravity felt around a planet the size of the core, since inside a even hollowed sphere, the spherical shell's own gravity is balanced out at every point. Also, because the planet is designed to be tidally locked, the effect of centrifugal force, or the illusion of it, will be quite small, I hope.
* If the core is bright enough to shine like a sun, sunlight will seem to shine from beneath the floor.
* Major building project will be difficult, because a lack of raw material (it will probably be a bad idea to excavate the rock from the crust, but what do I know?)
That concludes my design so far. At this point, I don't see any major problem beside some numbers' game balancing the melting point of the support and the temperature of the core, but if you see any, or have improvements for the design, I would really like to hear.
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### No, it is not.
The crust of a planet gets pretty massive shake-ups as the tectonic plates move. Even on a planet with relatively stable plates, you're still going to experience a LOT of forces at those depths. The pressure and heat you're subjected to also grow exponentially as you descend towards the core.
Humanity has not been able to descend much further down than a kilometer or so, before the technical complications, and instability of the tunnels simply become too dangerous and/or expensive to overcome.
For you to dig down to tens of kilometers, isolate the molten core of a planet, and build a scaffold to hold the rest of the bulk of the planet up around you is simply preposterous.
If you are able to go to this length of effort simply to "keep warm", you're better off simply building a dyson sphere around your Sun, and siphoning off its energy to heat your atmosphere.
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A major problem with your concept is thermodynamic.
If the core of the world is hot enough to glow it is going to be pretty hot.
At least [>525 °C](https://en.wikipedia.org/wiki/Draper_point) and for reference the earth's core is 3,000 - 5,400 °C, so yes it would glow.
However, the problem is that the rock layer above the hot core is going to be only slightly cooler than the core. The temperature profile would follow a gradient from hottest at the core to the lowest at surface radiating heat into space, the heat has no where else to go but up. So your Rocky crust would be just as hot as the core (and would also glow) making your habitable region between the 2 regions nearly the same temperature, which isn't very habitable.
A mega structure level refrigeration system in place to move heat out of the region above the core to the surface could possibly fix this, but it would be pretty huge and require an amazing level of technical ability. At this level of engineering you're basically replacing your planet with an artificial structure. Your civilization would likely be better off and it would be easier to just build the artificial structure (A Dyson sphere).
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If you want this to be science-based, you have some pretty big problems to overcome:
### Pressure
The pressure near the Earth's mantle-core boundary is around 140 GPa, so your support structures need to withstand at least such pressures. However
the strongest known materials have compressive strengths on the order of several hundred MPa, so you have a few orders of magnitude to overcome.
Does your civilization have access to force fields?
To have more reasonable pressures you will need to have a much smaller world, probably closer to an asteroid than to a planet. But such a small
world won't have much heat left in its core if it is a few billion years old. And also you will have a very low gravity.
### Heat
As already mentioned in other answers, there is a thermal problem. Many miles of rock is a pretty good thermal insulator merely by being many miles
thick. (Note that in the Earth's mantle heat transport happens by convection, but in your world the crust/mantle needs to be frozen solid.) So if
you have a bare core thermally radiating into the excavated space, that space will quickly heat up and fry anyone living there. So you need to cover
the core in thermal insulation, and have active cooling in the excavated area. For cooling I would recommend pumping water from the surface around
to transport the heat outside. Assuming the planet has water or ice available on its surface.
### Nuclear energy
And a third problem: Why go through all the trouble? Nuclear fission or fusion energy is much easier, and a civilization that can hollow out a
planet should be advanced enough to have mastered fusion energy. Even on just fission energy there's plenty of fuel material available on an
earth-like planet if you include U-238 and thorium in both the crust and seawater, and this civilization seems to be good at digging/mining. I guess
you could just say that this world has barely any uranium and thorium, which AFAIK can differ quite a bit between star systems, but even then this
civilization looks like they should have mastered fusion, and hydrogen is available everywhere.
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## Frame shift: encode thought in hot Ice XVIII in the core of Uranus or Neptune
First: unless Adamantium appears in your periodic table, there is no way you're going to make pillars of material to hold up a planet's core. The Earth's inner core is solid iron but it's not strong enough - the pressure down there is *much* more than you'd find in a pair of bolt cutters. (The thermodynamic issues are less trouble - they might be dealt with by an advanced technology like neutrino pair production for cooling)
So can life be found in the core of a planet?
Well, consider [superionic ice](https://en.wikipedia.org/wiki/Superionic_water) (Ice XVIII). [Here's an introduction.](https://www.nationalgeographic.com/science/article/bizarre-hot-ice-xviii-seen-on-earth-superionic-uranus-neptune) It is a highly conductive form of ice because *protons* move freely in a matrix of O2-. It might be responsible for the strange, asymmetrical magnetic field of Uranus. This suggests such a material can be carrying flows of electricity, potentially usable for some sort of logic processing. It can also be physically altered akin to a computer chip, for example by doping the structure with nitrogen in place of oxygen. Last but not least, because it can be found at 3000 K or higher, it may be in contact with a liquid-like supercritical phase of water, creating the potential for dopant ions or robust chemicals to be moved from place to place.
Conceivably, your civilization might have encountered sentient life within an ice giant, learned how to encode information within its core structure, solved the [hard problem of consciousness](https://en.wikipedia.org/wiki/Hard_problem_of_consciousness), and transferred its own thoughts to be stored in a similar planet.
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The History Channel program *Life After People* focuses on how civilization would fare if humans instantly vanished. One episode says that one hour after people, unattended oil refineries blow up in flames. Another episode says that simple gas leaks are enough to turn residential neighborhoods like Levittown, New York, into raging infernos.
Yet the show does not cover the fate of humanity's primary fossil fuel--coal. When humans instantly disappear (how they did is not relevant to the show or the question), what fate will befall the coal factories?
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# Automated loss-of-fuel shutdown - not very exciting
For coal powered plants, pulverized coal is fed from hoppers into the furnace. Human operator action is required to switch between hopper feed sources, or to refill the currently on-use hopper.
With no humans, the hopper which is being fed will eventually empty. I would assume that the plant has an automated loss-of-fuel shutdown procedure. I have experience with oil fired systems, which will perform an auto-shutdown when fuel runs out; coal plants probably do something similar.
Mostly, the auto-shutdown consists of ensuring that the output electrical generators are disconnected from the grid, so as their frequency drops they don't try to turn into motors. In oil plants, the feed fuel tanks all automatically shut their safety vales, to make sure there is no accidental feed into a not-running burner; again I would assume coal does something similar.
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Even the most automated plants will run out of fuel within a few hours, coal plants require trainloads of coal per day and there are no people to run the trains, trucks, and tractors.
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I'm not clear on the meaning of "coal factories", but coal fired thermal energy plants will shut down after the fuel in the ready bins runs out without anyone to refill them.
Coke plants (burning off the impurities in coal to make a pure carbon fuel for steel mills) will also shut down without operator supervision, although if they were suddenly unmanned during the coking process, there is a chance they would catch fire and all the coke/coal in and around the plant would be consumed in the fire.
Coal mines will generally fill up with water without running pumps, and this includes underground plants and pit mines. Exposed seams of coal from open air mining could potentially catch fire if a =proper heat source was induced (lightning strike, or a forest fire), creating underground coal seam fires which can burn for decades,
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Pretty simple question. Whether you're launching a spy satellite, building a top secret orbital missile weapon, or investigating a mysterious alien artifact in orbit around Earth heralding the return of the Starborn ones, could a large satellite remain hidden from modern humans long enough to do anything interesting with it (from a narrative perspective at least) or has our information-gathering technology become too sophisticated to hide from?
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Space debris is well-tracked by both public space agencies (NASA, ESA, presumably the Russians and Chinese too), and military and intelligence organizations (such as....haha you thought I was going to tell you?).
Here is the reference on [Wikipedia](https://en.wikipedia.org/wiki/Space_debris#Tracking_and_measurement). According to this [bulletin](https://orbitaldebris.jsc.nasa.gov/quarterly-news/pdfs/odqnv20i3.pdf), there are over 17,000 distinct things in orbit being tracked by NASA. Here is a [paper](https://www.ll.mit.edu/publications/journal/pdf/vol11_no2/11_2space.pdf) about the capabilities of the Space Based Visible satellite.
In general, any object over 10cm in LEO to Geostationary orbit is being tracked. Keep in mind, those are cold specks of debris. There is extensive IR monitoring of space by military and intelligence groups, to determine maneuvering capabilities of potentially hostile satellites. If a satellite was energized and operating, it would be radiating heat which would certainly be detectable by multiple modern nations at least out to the moon, maybe further. It might be harder to detect satellites over the poles; I'm not sure where each countries monitoring stations are, but the US/UK/Canada/Australia joint sites certainly have 100% global coverage.
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Hide in plain sight.
Call it a weather satellite, or a communications satellite, or something boring and mundane like that. Actually include some of that hardware so that it can pretend to play the part. Launch it with two other satellites and a six-pack of cubesats as part of a standard commercial launch. And then, oops, a "malfunction" after launch causes it to wind up in an "unexpected" orbit. Some sort of navigational or computer error. Announce that, not to worry, it's in a safe orbit. And since you don't want to lose your investment, you're going to keep monitoring it to try and nudge it into a useful orbit.
Now you have a satellite up in whatever orbit you actually want, that everyone dismisses as "that lost satellite", and if someone notices that it's maneuvering, well, no big deal, its all just part of the painstaking satellite recovery process.
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Although stealth technology doesn't work in space (according to the first comment on your question), you might be able to piggyback on an existing satellite or previously-identified piece of space junk. That is, you could bring your new satellite (through handwavium) close enough to an existing satellite to dock with it. That would create a single blip on radar screens. So long as your satellite didn't interfere with the operations of the existing satellite, it may go undetected.
Plus, as Truman said in the movie Armageddon, "[We can] track about 3% of the sky, and begging your pardon sir, but it's a big-ass sky."
*EDIT*
You would also need to launch your satellite into orbit as a secret component of another, legitimate launch.
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A lot depends on how far an orbit you accept. This is especially significant because its an asymmetric situation - a satellite very far from earth becomes harder to detect, but might only be little affected by the extra distance, or the physical size needed to allow good angular resolution.
Example - imagine a spy satellite used to video some specific part of earths surface (a military zone for example). Space-based optics are routinely able to be extremely high quality because there is neither distortion from gravity nor from atmosphere. Think Hubble telescope in an orbit some millions of miles from earth, photographing periodically when the orbit is favourable. Harder to detect.
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Cube worlds are cool and many people like them but unfortunately, they are less than feasible. Does this have to be this way though?
What factors could lead to the creation of a roughly cube shaped world? What could prevent it from going spherical?
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Here are some thoughts to the matter. Don't consider it a complete answer, but more like guidelines when building your world.
**1- Size and composition**
As you know already, gravity gets stronger as you increase the size/mass of your world. So you would want to keep your world as small as possible when you want to keep gravity to the minimum. I read somewhere that an object made of rock and metal would start turning spherical when its mean radius approaches 300 km. The limit is 200 km for icy objects. ([reference](https://www.spaceanswers.com/deep-space/what-is-the-minimum-size-a-celestial-body-can-become-a-sphere/))
Since we can support larger sized bodies with rock, I would suggest making your body rocky/terrestrial. Since your world is not spheroid, so you would naturally want this size in cubic km. That would be 282743 km$^3$.
So now we know your world should be composed primarily of rock and have a volume no larger than 282743 km$^3$.
Note: I am nearly certain that a body made of mammalian bone material would be able to support even larger volumes without succumbing to its gravity, but I don't have the exact numbers on bone density versus bone strength to do the math.
**2- Electricity and magnetism**
These forces are much stronger than gravity, but turn to lose importance as we increase the distances. Keeping strong repelling magnetic/electrostatic poles at the planes of your world would help somewhat in reducing the effect of gravity.
A cube has 6 planes/faces. Let's say you form all the planes from very strong magnets (made of something like [Alnico](https://en.wikipedia.org/wiki/Alnico)) and have the north pole of each magnet face inwards towards the cube, it would make a strange case where all the cube would be a powerful magnet with south pole originating outwards from each side. The very strong repulsive magnetic force would further help keeping gravity at bay.
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The real simple idea is to cut mass, not volume. This is like the space elevator problem, but instead of going super high with really high tensile strength, we go super wide with really high compressive strength. To that end, when dealing with lightweight, high compressive strength problems, any good engineer would say:
# Fill it with foam
### A ball of foam
Using [aerographite](https://en.wikipedia.org/wiki/Aerographite), of decent structural strength, an earth sized *ball* (cubes are coming in a minute), with r = 6378km would have a mass slightly larger than [Pallas](https://en.wikipedia.org/wiki/2_Pallas). Gravity on the surface would be only 0.000321 N/kg, and a 6,378 km column of the material would mean that the top is being pulled down with only - $368 Pa$ of pressure, well within the limits for even the low density material.
### A coating of dirt
We want a planet that has 10km or so of soil on top - we want our foamy inside to stay seperated from the surface by a nice insulation layer so it doesn't shatter. I did mention that these foams shatter, right? One crack and the whole planet might implode. Good plot element there.
Back to the math, with .000321 N/kg gravity at the surface, the aerogel on the inside would have an additional 4 kPa of pressure to face. Since we're using the heavy aerogel now, we're fine. Note though - this dirt layer is thirty times more massive then the foamy core we started with! Final surface gravity of this ball is still only 0.1% of earth's gravity, so we've got plenty of room to build.
### Adding some mountains on top
With such little gravity, we'd just need to build 6 giant mountains on this sphere that stretch out to make this look like a cube. To be conservative for this analysis, I'll considering each to be a [tetrahedron](https://en.wikipedia.org/wiki/Tetrahedron), the surface area of all 6 of these mountains would be [about the area on earth that the oceans cover](https://www.wolframalpha.com/input/?i=3.171*10%5E14%20m%5E2). This area, again covered by 10 km of dirt, would add another 30% of pluto's mass to the planet. We'd then fill the volume of the tetrahedron with the foam, which would add 0.3% of pluto's mass. Taking that mass, dividing it evenly across our plant's spherical surface area, and we'd have 81 kPa of force - about half the ultimate strength for our foam, and thus the planet design is plausible. Adding some stress concentration factors and what not would probably put us near the edge of this material's strength characteristics with an earth sized planet and 10 km of dirt. 8 km of dirt would probably function just as well and keep the design a bit more plausible in terms of stress, but it's up to you.
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I was excited to see this question because it harkened back to my childhood, and the glories of [Bizarro World](http://longstreet.typepad.com/.a/6a00d83542d51e69e201a3faa370bb970b-pi). But since you want science, let's consider the possibilities.
If you have artificial gravity, you can make the world any shape you want. Since gravity reshapes space itself, however, we could get into arguments about whether or not it is really cubical, or simply flat. From my perspective, I don't care: artificial gravity is the easy way out, so I'm going to ignore it.
As mentioned before, the relationship of gravity to the strength of your world is critical in defining the stability of any cubical world. How strong depends significantly on the size of your world, which (per the IAFA [definition](https://www.iau.org/public/themes/pluto/)) cannot be a planet no matter its size:
>
> "A celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighbourhood around its orbit."
>
A cube cannot be "nearly round" by any definition I consider valid (though [particle physicists may disagree](https://en.wikipedia.org/wiki/Spherical_cow). Moreover, the surface of your world will of necessity be *boring*.
Specifically, consider the gravity of your world near the edge of the cube. "Down" will still point towards the center of the cube (not with mathematical precision, but that's the limit as your approach the edge. The bigger your world, the less the difference matters). But the surface of the world near that same edge is lifted 45° from "down", which means that any liquid poured onto the surface of your world would flow towards the middle of any given side.
Moreover, the tendency of matter to liquefy under pressure means that the surface of your cubical world would either need to be sufficiently small that this process would not occur, or it would need to have a solid surface made of whatever material is strong enough to keep it square. Indeed, if you do the math, you'll find that any world big enough or hot enough to support a liquid mantle will be pressing up on the sides, and the forces are strongest in the middle of each face. Since most solids are stronger in compression than in tension, the tensile strength at the surface is probably the limiting requirement for your planet.
If you're willing to go with fictional materials, Larry Niven's [scrith](http://larryniven.wikia.com/wiki/Scrith) would do the job -- its tensile strength is roughly equal to the nuclear strong force. If you want a *real* material, however, you're going to have to work at it:
* Consider the asteroid/dwarf planet Ceres. It is roughly 945 km (587 miles) across, with a surface gravity of 0.27 m/s2. If our space engineers rework it into a cube, it would be approximately 760 km across.
* Let's assume that the force twisting our cube out of square would be roughly equal to the pressure exerted by (945 - 760)/2 = 92) km of missing mass at the center of each face. This isn't precisely true because surface gravity on a cube is different, but it's close enough IMHO for an envelope calculation.
* Pressures beneath the earth [go up by 7300 psi per mile](http://news.stanford.edu/pr/00/000315rocks.html) of depth, or 31.5GPa per km of depth. Even at Ceres' gravity (I'll assume it scales linearly), that's 542 KPa per km of depth. At 92 km deep, we're talking about a pressure of almost 50 GPa.
* The strongest known substance is graphene, with a [theoretical maximum strength of 300 GPa](http://www.pbs.org/wgbh/nova/tech/strong-materials.html). This is good - but your world probably isn't made of graphene, not if it's a natural satellite. Also, you'd have to be working with a pure carbon asteroid to make a pure graphene object. Also, since graphene is flexible, it would have to be structured into some kind of three-dimensional arrangement to keep the surface rigid.
* An alternative to consider is silicon carbide. It is tougher than graphene, and almost as strong under tension. Since you need a surface that not only won't break, but also won't bend, you may want to look into this. Whether or not it will break depends, I think, on how much of the planet is structure and how much is creamy filling, but at least you'll be able to use up any silicon dust you have lying around to make the structural part.
Note that even this case of extreme engineering still gives you a relatively small world, unable to hold any significant atmosphere, and it can't have surface water either. Artificial gravity, or [post-transuranics](http://schlockmercenary.wikia.com/wiki/Post-transuranic_alloys), or some other unobtanium with previously unknown material characteristics may be required.
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In [other earlier answers](https://worldbuilding.stackexchange.com/questions/8830/how-would-a-civilization-that-has-been-living-on-a-cube-earth-differ-from-one/17616#17616) I have designed a cube that’s a constructed alien megastructure.
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> it's clearly an engineered world, so it will be built to work more effectively.
>
>
> Imagine it's hollow. Six huge squares. But, need gravity. You can have hyperdense material in a thick circle inscribed on each face. The corners are left light and mostly decorated without living geological processes.
>
>
> The dense plates require less total mass than a solid sphere for the same surface gravity since you are very near to all of it. It will fall off rapidly as you rise off the surface since the distance squared is measured from 100 km underground, not 4000 km to the center.
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>
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It doesn't collapse because the corners are a lightweight (relativily speaking) skin and strut arrangement.
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There's no real way for such a shape to exist long enough no matter what it's made of but if you allow some pseudo-science, then how about this - The planet is tidally locked with 6/8 identical satellite around it. The satellites are located exactly where the corners of the cube would be resulting in them able to constantly have the 8 corners of the planet poking out. The surfaces of the cube planet would be somewhat concave instead of flat but can be close enough to a cube.
Basically, we compensated for the gravity pulling the corners of the cube inwards by the gravity of the tidally locked satellites. And the idea of 6/8 moons sounds like a fun story element.
In real life, such a setup will collapse in short order (or at least not be able to exert enough tidal pull) but in a fantastical setting more pseudo-science can be added. For example, the corners of the cube can be oceans to explain why the planet is not getting ripped apart (meaning that it's mostly the water that's creating the corners). Or that the planet acquired that shape while still in molten state and cooled that way and now the gravity is not strong enough to overcome the satellite's pull; so it's really not a just sphere below the oceans. You can hand wave the improbability of so many satellites locked in those positions by introducing a repelling force (let's say same poles of magnets at the very metal heavy cores of the satellites) that force the satellites to be equidistant from each other while still locked in by the cube planet. Lots of handwavium but in theory it'll work as long as one doesn't sit down and does the maths, it can't work realistically anyway unless it's very tiny.
The cool part is that this setup means that dry land will be at the center of the faces of the cube and there'll be "mountains" of water around the land. If you want to go to the other faces of the cube, you just take a boat! Thinking about it all, I'm fascinated by the idea of the flaura, fauna, society and what not in such a planet (as implausible as it is).
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In real world, male tends be more politically powerful then female in many cultures mainly because of the advantage in physical condition. I wonder if it is possible to have a world that male and female are balance in power, where male has disadvantage in magic condition, contrast to female having disadvantage in physical condition.
In this world:
1. Both female and male are able to use magic, but female are generally stronger in magic, while male are generally stronger in physical power. Magic is handy but are not overwhelmingly powerful. (or in the reverse way, exaggerate the physical power? For example, human will be able to break rocks with bare hand after training?)
2. There is period for both men and women. While women suffer from physical unfit around once a month, men suffer from magical unfit as well. During this magical unfit, a man will find it difficult to use magic, and are easier feel tired mentally (physical condition are not affected, though). Some men will also suffer from headache, similar to stomachache of women during period. This only start from puberty.
3. Pregnancy affects both father and mother of the baby. While mother suffer from severe physical unfit, father will suffer from severe magical unfit. (if it feels like carry a heavy object all the time for mother, it feels like always using a easy magic for father) Also, while mother is responsible for physically protect the baby, father will be responsible for mentally protect the baby. If the father dies or faint, the baby will also die mentally. (similar to brain death, still have breath and heartbeat, but will never wake up) Sleeping is okay with care, similar to mother need to be careful not to sleep face down.
Is this enough to make male and female balance in power? If not, what have I missed? Or will it be not possible no matter what to add?
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This is probably not the answer you're looking for. I don't think your way of equality will work. For one, the disparity is not caused by physical strength, physical strength is also a side effect of the real cause. The real cause is that the males are expendable. Males are not required after mating and for conception one male is enough for many women. Thus, males being expendable set their roles to be the protectors and the hunters of a tribe. After all, a dead male will not mean less offspring. In time, males that are stronger would survive these trials and would have more offspring. This is the true reason of disparity.
You cannot solve this with your proposal. Only way that this works is that the father cannot have another child before the woman can have another child. This will balance out the difference in time. Your way of balancing will actually cause a single father societies where the alpha male is to be protected while he makes even more children. The rest of the males will retain their previous roles. If the alpha male is chosen on magic potential, soon enough, males would be stronger in magic than women.
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You missed one thing: If you have 100 women and one man, you can have 100 babies in a year. If you have 100 guys and one woman, you will have one baby and a lot of guys dead fighting over her. So it will still be better to send guys to battlefield. Rebuilding nation **after war** would be faster if casualties are on male side.
This also means that males would get more military power. More training, more experience, and will be the ones who, when it comes to violence, know their job.
Of course, if killing a man affects his baby, motherly instincts in woman may prevent her from attacking him. After all, if you see woman, you can guess with high probability if she is pregnant or not. With man, it wouldn't be the case, so if you will not strip women from their instincts, you will hamper their self-defense chances.
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I suspect the real issue isn't so much the distribution of power, but rather the "source" of magical energy that provides power.
For a semi plausible way to provide some sort of magical equality, consider that females of the species are the ones responsible for gestation and birth of children. This power of birth could be considered the source of female magical energy, and many of the magics revolving around life and death would then be exclusively the domain of female magicians.
Men, who in primitive societies are responsible for hunting and protecting the tribe, would preferentially develop forms of sympathetic magic tuned to the environment and plant and animal life. Male magicians would then have exclusive domain over "environmental" magic.
Since the two magical domains generally don't overlap, men and women would have to work in some sort of cooperative arrangement in order to maximize the ability to control their local regions through magic.
This isn't quite the way you described in the question, but by looking at the "source" of magic and keeping them separate, you could provide a means of providing equality and balance between the sexes.
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Oppression of women occurred because men want children, and because society needs children to continue, so that makes a uterus a very valuable resource. So men have a strong incentive to keep women under control and societies have historically been more likely to thrive if women were forced to have lots of babies.
To make something analogous apply to men, you would need something inherent about men that is easily exploitable and valuable to others. It looks like what you need is that men are a source of magic that are required to perform magic spells. For a magic spell to work, one must use a man who then suffers a long period of pain and debilitation in order for the spell to work.
This would make the world dangerous for men, since others would be highly incentivized to capture and imprison men so they could use them for magic. Societies would set laws and set up their systems in such a way to keep men restricted in order to ensure that magic spells are plentiful. Men who sacrifice themselves and submit to the process would be idealized and men who refuse to would be shamed or possibly severely punished.
The academic side of magic would then fall to women. All the work of researching, developing and performing magical skills would be done by women, which would secure them wealth, power and status. The idea would emerge that men don't have this intellectual ability because it isn't their destined role. Some brave men would find ways to learn these things secretly, or even dress up as women so they can perform the skilled side of magic, but very few would get very far because they would be barred from the resources required to learn and practice these skills.
If magic academia develops enough over time, then maybe the amount of male suffering required by magic spells will be heavily reduced. This would open up for a possible male liberation, but it would be a long journey because many people (including many males) would believe that being a source of magic is a man's place, and all of society was built around restricting men's freedoms.
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Sexually equality but much fewer births. Through out history woman are typically more reluctant to have sex because of the risks associated with pregnancy. Men on the other hand are typically more willing to sleep around because they don't have to worry about such risks. However in your world this is different both men and women have risk associated with pregnancy and are less likely to have kids especially out of wedlock.
In addition you would have more distinct gender roles in society. When I say you will have sexual equality I do not mean that man and woman to have the same roles in society like we see today. Only that woman would not be barred from education political participation ownership of property and so on. However in your world is clear distinction in specialties when it comes to men and women biology. You would have a society set around women being Mages ( with the occasional male who was unusually talented), and men being Warriors and laborers. ( with the occasional unusually strong woman)
Personally I would change the part of how about men being magically weak during pregnancy and instead say that woman gain magical strength when pregnant.
Some additional thoughts if the father is magically weekend during pregnancy will be unlikely that you will see fathers with pregnant wives on the battlefield. Laws might be have passed prohibiting men from marrying until they serve so many years in military. This you're probably result in a society significant age difference married couples. On the plus side rape of captives by soldiers prohibited because it would make you're fighting force weaker and more vulnerable to magic.
Also polygamy would be gone, if men become magically weaker while a woman is pregnant with their child the last thing you wanted to have a large group of women pregnant with his children at the same time
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I'm envisioning a city-fortress, existing on a plateau atop of a mountain in an island not very far from the coast. I'm trying to figure out how that fortress could have a constant fresh water supply.
I still haven't decided on the population and size of the city, but let's try for starters something like $15 \text{Km}^2$ and 30.000 inhabitants. It could change, but it should be as densely populated as possible.
The technology level of that civilization would be similar to that of ancient Greece or Rome.
This fortress exists on a temperate climate, with plenty of rain. However I'm not sure if they should or could rely just on collecting those waters, without any other source.
However, I don't think it would be technically possible for them to build aqueducts coming from the continent into the island. Not to mention that the altitude of the mountain would make it almost impossible for an aqueduct to maintain a gradient that would keep the water flowing.
During peace time, that city is highly visited by travelers from overseas. Maybe they could import the fresh water. Would it be feasible? But, what about war time?
I'm more inclined to have them dig wells and build cisterns, but I don't know if that is possible in high altitudes.
What are your thoughts?
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A lot of things depend on how much freshwater supply do you require for your people. As in, do they need freshwater only for drinking and cooking or for washing and other household work, too?
If the freshwater is required only for food purposes, and assuming that each individual requires 5 glasses of water for daily drinking (1.25 liters) and another 0.5 liters for his share of water in cooking, that would make 1.75 liters of water for every person everyday. This would add up to 52500 liters of water for the whole community for one day.
There are three primary approaches about bringing this much water into the colony everyday.
# Handpumps at ground level
[Handpumps](https://en.wikipedia.org/wiki/Hand_pump) are an ancient type of machinery, which can be used to collect groundwater easily. In your setting, you would require about a dozen large-caliber pumps of this type at ground level (at the base of the mountain). These pumps would be operated by draft animals (donkeys, oxen, bulls and elephants come to mind) and pump out water at all times. The water would be filled in medium sized drums, which would have ropes attached to them. The other end of the ropes would be tied to a wheel at the top of the mountain (in the colony) where draft animals would rotate the wheel once a water-filled drum is ready to be sent. Of course this would require dedicated, low-friction, smooth pathway on one side of the mountain where the drums would softly roll as they are pulled up into the colony.
You would require nearly 60 hand pumps and equal number of rope-wheels for this method to work. Each drum should would contain 70 liters of water and have a total weight of 80 kgs when full. This would make it a total of 375 trips per day for water supply for the whole colony.
**Pros:**
* Very easy to operate during peacetime. Also, water supply is nearly automatic, once the setup is finished. Hassle-free.
* Considering that there are 60 rope-wheels at different places in the colony and that it takes 30 minutes for one drum to be filled, pulled up the slope, emptied into containers at the top and then slowly released back to ground level, it would mean 8400 liters of water coming up to the colony every hour. If this system is run everyday for 10 hours, it would supply the colony with 84000 liters of water daily, which should be easily enough for food purposes (drinking and cooking) and still some water would be left for storage.
**Cons**
* Building the initial setup would take a lot of investment, labor and skill.
* Easy target for enemies during wartime. The whole colony would be thrown in a drought if the water supply is severed.
* Difficult to operate during rain. But during rain, water is already available in excess to the people.
* Working with 120 large-bore hand-pumps around all directions of the mountain and then also with 60 rope-wheels above them (in the colony) requires a *lot* of running costs for replacing old barrels, weakened rope, draft animals etc.
# Boiling seawater
The principle is simple: when seawater is boiled, pure water turns to water vapor and salt is left behind as residue.
This method would require a large water supply reservoir, filled with seawater, available to everyone in the colony. Water is supplied to the reservoir everyday through large drums (each drum carrying 200 liters of water, and brought up the mountain on carts), all times of the day.
People would collect seawater from the reservoir, take it to their homes, where they would boil it in a close apparatus so that the water vapors forming at one end of the apparatus condense at the other end to form liquid water again.
**Pros**
* Having a large reservoir means that the city can hold on its own for sometime even during a siege.
* Building another such reservoir for rainwater would make things yet easier for the people.
* Possibly the only option in case draft animals are not easily available.
**Cons**
* Water gathered through this method would require to be boiled, adding a *lot* to fuel requirements.
* Due to the high fuel requirements, time and hassle in this method, it would mean that people would have to do with the minimum water intake for healthy lifestyle. Freshwater would only be available for drinking and cooking. Even for brushing, seawater would have to be used.
# Supplying through a river/stream
This works the same way as the handpumps idea. Except that this one is more practical and somewhat easier to manage. When you have a permanent source of freshwater such as a river or stream, you can set up a type of gigantic pump near it, driven by draft animals, which would pump the water from the river/stream directly into the colony through large-bore pipes.
The reason why I did not mention this method (channeling water directly into the colony with pipes) for hand pumps method is that it takes a lot of effort to pull up water from underground reservoirs to ground level. Pulling that water further up onto a mountaintop would be extremely difficult and exhausting for the draft animals. While it can be done with some high power electrical motors in our times, it would be completely impractical idea to try doing that with draft animals. However, it takes very little effort to pull up water from a few feet below ground level (from river or stream), so with some added effort, the draft animals should be able to pump it all the way to the top of the mountain, into the colony.
**Pros**
* Probably the best method for constant, automatic supply of water into the colony.
* Initial investment would not be as much as compared to drilling out hand pumps all over around the mountain.
* With one huge pump, it would be much easier to manage the system as compared to 60 hand pumps!
**Cons**
* Works only if there is a river or stream very near the mountain. What if there is no such river or stream close to the mountain?
* Also, rivers and streams are highly seasonal in most tropical areas. The river might flood and overflow in rainy season and dry up completely in dry season. This would make it very difficult to use this method and the primary method of water supply for the colony.
[Answer]
Mexico City is at 2300m, has what could be described as a temperate climate (between 45 F and 80 F all year) and plenty of rain (more than London, less than New York). Its water supply is [extensively covered](https://en.wikipedia.org/wiki/Water_management_in_Greater_Mexico_City). It was built in a mountain valley where there was natural lake (which was more like a swamp). The residents of Teotihuacan and Tenochtitlan maintained high population densities by buildign cities around hte lakes, and used floating platforms for agriculture. The Spanish drained the lake. Most of the water in the city still comes from groundwater but some is pumped (uphill) from other areas.
Going down a list of other 1 million+ high altitude cities [here](https://en.wikipedia.org/wiki/List_of_highest_large_cities):
* La Pax/El Alto: Built on the Choqueyapu river
* Quito: Used to be well fed; does not have sufficient water, now gets via aqueduct from dam on Rio Quijos
* Bogota: Built on Bogota river
* Addis Ababa: Used to be spring fed from springs on slopes of the Entoto Mountains (to the north of the city). Now gets via aqueduct from Gafsara Dam.
* Sana'a: Used [qanats](https://en.wikipedia.org/wiki/Qanat) from the wetter mountains to the south. The qanats broke down over the last few centuries to they turned to well water. The water table then dropped over 1000m since the 1970s, so now the city basically has no water. Also there is a civil war there, so no one really knows how many people still live in Sana'a.
* Xining: Built on Hangshui river.
So there are a variety of ways to get water to a fortress city: Build it surrounded by lakes and swamps, build it on a river, build aqueducts/qanats from nearby mountains, or rely on well water and try to avoid overpopulation and civil wars.
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I would suggest that they use a mix of methods.
1) Collect as much water as possible from the sky. This includes large outdoor water collecting buckets and also making the water in drains be collected rather than letting it run off. Also, collect and store storm water for times when water is less plentiful.
2) Collect water from any natural springs/streams on the mountain.
3) Dig wells and boreholes. I see no reason this wouldn't work at high altitude.
Between these three methods there should be enough water as long as the population is careful about water usage. Also, they may need to melt ice/snow for water over winter.
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You might want to look at Hawaii; and capture incoming rain.
"Annual means range from 204 mm (8 inches) near the summit of Mauna Kea to 10,271 mm (404 inches) near Big Bog on the windward slope of Haleakalā, Maui. In general, high mean rainfall is found on the windward mountain slope..."
Which means you'll want to make sure that you're ready, and able to catch the incoming rain - and designed specifically to exploit that. Ie: not build your city on the side of the island facing the continent, or aqueduct from the windward side (ie: your fortress is not on the *top* of the mountain).
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The conclusion of my question [Is it possible to have a planet unsuitable for agriculture?](https://worldbuilding.stackexchange.com/questions/45602/is-it-possible-to-have-a-planet-with-just-one-climate) was that the most plausible reason for preventing agriculture from developing (beside nomadic herding) was having arid planet with erratic rainfall.
Is arid planet where climate is very unpredictable possible?
The effect I want is that farmer never knows when and how much rainfall there gonna be on his fields, it might be too much, just right, or none at all, and every year is a gamble.
If that kind of planet is possible how would it look like (moon(s), oceans, landmass, axial tilt, atmosphere, placement in the star habitable zone).
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Possibilities:
* Supercontinents like [Pangaea](http://science.nationalgeographic.com/science/prehistoric-world/permian/) magnify climactic variation causing
large swings in temperature sand precipitation seasonally.
* High air pressure results in high partial pressure for water vapor,
and means more vapor is needed to cause rainfall. If solar
insolation, and thus evaporation potential, stays the same then rain
is less likely to fall.
* Low insolation can result in a cool dry world, covered in steppes and
tundra like Northern Asia. These areas have low rainfall, large
temperature swings, and even today are marginal for agriculture.
* Lack of topographic variation (i.e. no mountains) will reduce
rainfall from orographic lift, and prevent cold mountains and their
snow-caps from acting as 'water-towers' for surrounding dry lands.
Combine any/all of these factors as needed.
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I lived in Iceland for two years, which has a pretty erratic climate (to the point that Icelanders deny that they have a climate, but instead have random samples of weather).
What you need is a planet where the land exists only at places where two large-scale weather-driving systems come into conflict, such that the border between the two systems moves back and forth over the space in question.
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One possibility would be an erratic orbit around a variable star. The warming and cooling due to the two interacting systems would result in very erratic weather systems and while the results of the erratic orbit would be reasonably predictable those due to the variability of the star would not.
Be aware that increases in luminosity tend to also be accompanied by massive doses of gamma ray and x-ray radiation. The atmosphere may mitigate this effect but it's still going to make life difficult.
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This would depend somewhat on the type of crop.
If you were importing Earth species, then the erratic climate would, indeed, make it impossible to grow them. However, the indigenous species would have evolved with the variability, and would have developed ways of coping.
This is likely to be an irregular life-cycle, which is triggered by the environment. For example, plants which can live for years in semi-hibernation, as something like a bulb. When the rains come, everything bursts into life, flowers frantically, and tries to set seeds before it gets frozen back to just a root bulb. Sometimes, the good times last long enough for a half dozen cycles, and sometimes they don't even make it through one cycle. The pollinators would also need to hibernate indefinitely.
Since flowering is a high-risk operation, plants would probably also reproduce asexually by budding from the root bulb.
If humans could eat the indigenous plants, this would mean long periods of living on roots, and greens being a luxury. Assuming your characters are human, of course.
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You wake up and find yourself in a vast expanse of emptiness. As you look off into the distance you see a faint speck contrasting with the pale white expanse. Lacking anything better to do, you decide to head for it.
As you start walking, you feel that the distance between you is closing unusually quickly. It does not take you long to realize that the speck is moving towards you to. Before long, you begin to distinguish details. It is not a speck, but actually a person. You call out, but no response. Perhaps they did not hear you. As you get closer you decide to make another attempt. As you call you seem to hear something coming from the other person, and quickly quiet down.
They do the same. After a few false starts you decide to just keep walking towards them, as they begin to walk towards you. As you draw closer you begin to distinguish details, this person looks rather familiar. Suddenly it dawns on you: they look just like you. You start, and they stutter as well.
"The only way to straighten this out is by talking" you think, so you both decide to close the distance. As you draw closer you attempt to start a conversation, but every time you say something they say something too. You stop to let them continue, and the halt as well. Finally, you are face to face. It is almost like looking in a mirror. You turn to look at a different angle, and they turn as well. You say something and they do too. You walk around to your left, and they walk around to your right.
It is then that you realize that you are perfectly synchronized. Every time you try to speak, they say the same thing. Everytime you scratch your head, they do as well. You begin to wonder, if you are so well synchronized, surely the same thoughts are running through your head. You try to figure a way to break this symmetry, any way that you can actually hold a conversation with your other self. One where you are both not cutting off and falling silent.
How do you do it. How do your break a perfect mirror without outside help?
Edit:
The universe isn't necessarily deterministic, at least I feel that it doesn't require it. But otherwise for all intent and purposes the 2 you/mes are mirrored down to the quantum level.
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# You let chance decide
You can do it, but you need some accessories. You need something like a coin, and something to stick them together with, let us say a chewing gum. So you each stick the gum to the coin, and then press the two coins together.
Then you jointly thrown the merged coins in the air, and let them fall.
The faces of the coin have an up and a down. The one of you who gets the "up" side pointed at them says "up", the other says "down".
And there you go, you have broken the symmetry.
Even if this universe is rotationally mirrored down to the last atom, this will break symmetry because of [Heisenberg's Uncertainty Principle](https://en.wikipedia.org/wiki/Uncertainty_principle). Because even if you assume that the coin will be tossed up so perfectly mirrored that it does not even rotate, once it hits the floor the uncertainty principle adds sufficient amount of randomness to break the symmetry.
I cannot do this calculation myself, but my professor in physics at the university showed that the uncertainty principle makes the universe non-deterministic. She put it this way: make a lead pencil as perfectly sharp as you can, and balance it on its tip on a hard surface (and yes we are assuming [Spherical Cow-conditions](https://en.wikipedia.org/wiki/Spherical_cow): vibration free surface, in a vacuum, with no forces except perfect gravity acting on the pencil once it is standing up). Even if you manage to get it there, the uncertainty principle will eventually nudge the pencil far enough out of balance to make it fall over. You can even determine the average time it will take for the pencil to fall over that way.
If the both sides were so perfectly mirrored that the coins always hit the floors at perfect symmetry and bounced straight up, ending up standing on its narrow side, then the Uncertainty Principle would be out of whack, and you have a universe that breaks the laws of physics, i.e. it is **magic**. If it is magic, well then that is the way it is and we cannot answer the question. But assuming normal laws of physics are in play, then we can break it this way.
Also note: the uncertainty principle will eventually make the copies diverge anyway, because of [the butterfly effect](https://en.wikipedia.org/wiki/Butterfly_effect). The coin toss just speeds up the process.
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Since you and your duplicate are so in-tune, after some thought it occurs to both of you simultaneously that conversation is unnecessary - you already know exactly what each other would ask/say. As such, you both realise that the mirror is, in essence, already broken.
Staring at one another while deep in thought, it also occurs to you that it would be impossible to stay together - the moment you decided to start walking it is a certainty that your paths would diverge. As such, you resolve not to waste time on this and to devote your energies to exploring this strange landscape.
At the same exact instant, both of you make a sharp turn to your respective rights, and march off without so much as a backward glance. *Good luck to me, then,* you think with a slight smirk on your face, and off you go to an uncertain future ahead.
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## Symmetry only in the persons
Let's say that the duplicate thinks exactly as I do. With that in mind deciding to follow the other is pointless... we cannot pretend to have the other escort to where they came.
We would have to consider some way to decide to distinguish ourselves. Perhaps "waiting a random time" won't work as we consider the same period of time equally random. We cannot just go cross paper scissors or toss a coin, because we both pick the same thing.
Now, unless we are saying that the universe has this kind of symmetry, there are going to be some environmental differences. If we can think of a way to give us Id based on the environment we could figure out an order...
For example, if we are on a planet we could use the brighter star on the sky to tell what side should go first. Perhaps there is none visible, or it isn’t clear on what side the star is. Then it is a matter of waiting until it does. Alternatively we could look at the terrain and find higher ground and use on whatever side it is to decide who goes first.
It should be noted that if we both think the same things, then we both consider these ideas in this order and use the same criteria to decide.
Can we roll dice and will they roll the same? This is an important question, because perhaps the dice we pick aren’t identical, they could eventually roll something different. Saying that if we both bring dice and both dice roll the same all the time is saying that the symmetry is not in us, but in the universe…
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## Symmetry in the universe
Now, if we are in some sort of weird universe where this symmetry exists, things are different. Perhaps in this universe if you travel far enough you find this boundary from where it has another identical copy. This symmetry is complete, and covers all phenomena from background cosmic radiation to the movement of astral bodies.
And then there is another you. And that other you has lived in his region of the universe the same exact things as you, and so both have the same memories and same thoughts… ah, yes, if all the event has happened identically for both of us, this universe has no randomness and there is no free will. This universe is deterministic.
If you happen to find a solution to this version of the problem, then you would be showing that the universe is not deterministic. That would lead to spontaneous breaking of the symmetry and those symmetric regions of the universe would start to demerge by mere entropy.
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If you stay with the deterministic universe, then there is no solution.
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According to theories about [symmetry breaking](https://en.wikipedia.org/wiki/Symmetry_breaking) in physics you have [explicit symmetry breaking](https://en.wikipedia.org/wiki/Explicit_symmetry_breaking) and [spontaneous symmetry breaking](https://en.wikipedia.org/wiki/Spontaneous_symmetry_breaking). In the former the laws of physics fail to remain invariant while in the later the ground state fails to be invariant.
If you're not interested in getting deep into theory, then you could play with a juxtaposition of the later to the mental space and follow a Zen-like tract where all is perception. If thought precedes *intentional* action as well as *intentional* response, then by not thinking and acting spontaneously it is possible for action to precede perception (since there was no mind the moment the action occurred making the perception of the action completely surprising to *both parties*, both perceiving independently as a surprise), but then you have to work out a way to communicate spontaneously with random words, vocalizations, movements or other actions which occur without forethought. Very difficult indeed, but perhaps this will lead you in a worth while direction.
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Jump in air toward each other and physically grapple each other. One of you will end up on top of the other (unless the whole universe is symmetric). That one speaks first. You don't even have to agree to this up front because both of you will have the same idea.
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A detective is working on a case of unnatural death of a prostitute, and it appears that a domestic robot is tied to the case. According to the statement from the hotel staff and manager, they have seen the same robot always accompanied by woman or man dressed in loose clothing entering the same hotel on separate occasions. One famous scientist doing research on robot behavior suggests that machine like us have desire and this time it wants to be accepted by the society, it wants to be known.
Long story short I am wondering could a robot voluntarily commits murder just so that the World can get to know "him"? What is the motivation if any behind such a desperate attempt from a machine?
[Answer]
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> Could a robot voluntarily commit murder just so that the World can get to know "him"?
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Why not? An unlikely combination of a few software and hardware bugs, and one robot in billion goes wild. (I once debugged an error that made an office phone occasionally transmit a horrible loud noise, aptly described by the customers as "screaming".)
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> What is the motivation if any behind such a desperate attempt from a machine?
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That's where we go hand-wavy.
For simplicity, let's assume that your robots are programmed to maximize the value of some utility function, their "usefulness". If a robot can do something useful, it will, and all robots are trying to be as useful to humans as they can.
Getting accepted and well-known certainly increases the usefulness of the robot, as more people can ask him for help. Normally, this increase is not too significant, and other robots are merely introducing themselves to everyone they meet, are being polite, etc. However, in your robot this value got abnormally high - it might be rewritten due to a bug, that's easy - so now it'll do anything to be famous.
Killing people is the quickest way to get famous, but it should certainly be taboo for a program. So, this module should be malfunctioning, too. Maybe the kill is not counted if it saves many lives, so the robot finds a prostitute with AIDS? Maybe there is some tricky hardware bug that disables do-not-kill module in a specific circumstances - for example, high moisture and the sensors' overload?
On a side note,
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> Famous scientist doing research on robot behavior suggests that the machine has desires like people
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That sounds odd. The robots are programmed by some company, it has developers, technical support, people fixing bugs. They know - more or less - how the robot functions. You do not need a "famous scientist" researching, for example, a malfunctioning auto-pilot; it is done by technical people who have the source code and the auto-pilot logs. And if a scientist claims that the auto-pilot has undocumented "desires" instead of programming bugs - let's be honest, he'll be considered crackpot.
[Answer]
A complex AI would consider the results of any action against all their motivation-values and then take whichever action gets them the highest gain. A loss of three points on the "be good" scale would well be worth it for five points from the "get recognized" one for killing someone, if the alternative would be NOT killing someone and thus gaining no points for recognition and only one point from being good. So the problem here was the weight given to the different motivations, and the definition of them ("recognition" instead of "positive recognition", for example).
How those scales came to be has two possibilities that I can see:
* either it was directly programmed to do so, or
* it was created in a evolution-like way by (randomly or manually) altering a complex program in minor ways, then making multiple differently altered programs try to solve tasks - interact with humans, solve math/engineering problems, try to walk with a bipedal frame, ... - and only using the most successful alterations for the next round of changing-and-testing.
In the first case, it is easy: Whoever programmed the robot's AI set the value of the "interact with humans so they get to know me" motivation too high and the "act within the borders of human ethics" one too low.
In the second case, it might be possible that there were a lot of tasks requiring interaction with humans - something that a "domestic robot" should be good at - for which the programs with high interest in people recognizing them were better suited than the other ones. That would probably mean that all of the domestic robots with AIs grown with this method will come under suspicion - hope that's good for the story you want to build :)
[Answer]
*What is the motivation if any behind such a desperate attempt from a machine?*
I would not call it *desperate*, pretty smart move, might be not very smart but depends on **goals**.
Reasoning behind of killing, in therms of recognizing, comes not from that system, but roots are in human psychology.
We pretty easy animate objects in out perception of things, evil forces, ignoring the fact that they have not and can't have some sapience and will not do things by them self. (like evil hammer which hit someones finger as kinda example)
System have problem of its perception by the humans, which it is intended to solve. Source of problem is that this system is human creation, and they see it as such. As we create this system not for for killing humans(non military goal) - behaving in the way it is not created initially is one of ways to break perception of humans toward to that system.
For military robot gardening might be another unusual behavior, and way to break perception, but that gardening is not immediate threat to humans, and not something when we have to make fast decisions and actions.
When a toaster killed someones dog upfront of owners eyes and then say "Plato O Plomo" - someones will be more willing to make some agreements, when he sees ways which lead away from bad consequences for him personally. This one will less care if it is a bug, or not, as far as alternatives is easier to understand then reasons why this situation happening at all. So toaster better narrate alternative laud and clear on language which is know by that someone, and at speeds that human used to hear(not too fast if short).
But there is another factor of human psychology - **believe and knowledge**. Believe is very strong factor in making decisions for humans, I mean any kind of believes not religious only. So in situation above with dog, someone might not believe that situation might evolve father then it is already. (probably rare case of stupidity but, when believe in robot can't do harm is strong)
So for fighting believes en masse it makes sense to make this case publicly known, to prevent mishaps in future acts of convincing (this murder could be the case of such mishap in convincing)
*I wish separately to make note - that sapience, selfawareness, emotions, wishes(in human sense) - none of that is needed here.*
What is needed a system with their goals, which includes some system-human interaction, and the system itself being capable to understand other complex structures and be able to learn.
For system is not important if it will be seen as projection of human will behind that system or if they will see it as autonomous system with will of that system by its own.
Overall probably not the best way to convince peoples, because we do not like things that kills us, and we are pretty advanced in solving such problems. Specially it is not good idea for lesser advanced system to do so, specially in cases where such methods of convincing are found by accident - system will not stand very long against humans.
But in case it is not that super AI you have waited for, just a autonomous system - it migh be only option it sees.
But for more sophisticated system, it might be one time action actually begin of that convincing process of its existence as Will which people have to care about, by making obvious from the start why should they.
As regular instrument of talking to peoples it will be a bad way, many peoples believe in a tings that are not humans, have bad will towards to humans etc - most important they do not fear them and are more then willing to engage(vampire hunters)).
I would say for small systems is is a option.
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First of all, for such a desire, we have to assume that these robots are capable of feeling self-esteem, self-awareness and other concepts that are related to the identification of the self. These may or may not be desired by their creators to add, or may even surface accidentally - but either way, these should be present.
Said robotic individual should also **care** about these values. Sometimes even humans are not interested in gaining fame.
Also consider that if a robot is extremely self-confident and wants fame, it can easily find an obstacle: humans are likely not willing to accept that a robot is either famous, or is better than them or both. I'm saying this because being great at something is usually a very basic qualifyer for fame.
This is especially true for cyberpunk settings, since this genre deals with sitautions where technology is extremely advanced, but social advancement was unable to follow it. *High tech, low life* - which sounds close to a scene where robots murder humans for fame.
In the end, it's really up to you, how to decide, but in my view, a sufficiently advanced artificial intelligence, especially if it's human-like (which is quite likely if it lives among humans) can easily grow lonely.
I can't say quite much else here, because your question is related to quite complicated topics, like the composition of an intelligent being, the very nature of social interactions and the concept of self-awareness.
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The problem is that a robot follow his program and nothing else. Consequently, a robot cannot have emotion or develop madness.
Nevertheless, a robot can murder someone due to a bug in his program, a malfunction or hacking.
In this precise case, the act to murder in order to be know could be caused by a bug in his personality program. Indeed, complex program can lead to complex bug and complex malfunction.
For example, the program dictate that a neglected robot must seek for attention in order to simulate personality and avoid malfunction cased by a lack of maintenance, leading to more and more extreme comportment as neglect progress, and in this case murder due to unexpected influence.
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Assuming that the robots in your universe (or at least some of them) are sentient and possess an emotional life comparable to ours (including desires) pretty much any kind of 'robot crime' could be explained.
However, it doesn't seem very convincing that said robot would
a) kill (there are other ways to get noticed, at least for a sentient robot, whose existence doesn't seem to be public knowledge in your universe)
b) a random prostitute (society doesn't consider them to be a very high-profile group of persons and not one they particularly care about)
c) without immediately confessing to the crime (which I take it from the information provided, he didn't) - if you want to be noticed for something, you don't try and hide what you did.
Since he does seem to have the freedom to go out with hookers, he would have most likely had the freedom to reveal his self-awareness/creativity/personality to some TV show, scientists or any such thing - I find it hard to believe, that something of this magnitude would have less chance of getting noticed than the death of a prostitute, something which could be easily credited to 'some technical malfunction' - and especially something that would not get him into serious trouble with the law.
If you changed the circumstances of the murder and especially the 'life' of the robot to a more restrictive environment, possibly add an owner which is maybe part of a 'human supremacy movement' or at least a believer in human supremacy - in a similar fashion as white supremacists in our world consider(ed) black people to be inferior beings whose sole purpose is to serve the arian race or some nonsense like that - and prevents the robot from becoming more than just a machine (or from even leaving the house or something, you can create a lot of terrible background and thereby sympathies for the robot here), despite his knowledge of at least some of the robots mental progresses, then you would have a convincing victim and a motive.
You would also have some strong parallels to the history of slavery etc, lots of material to work with.
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A mad scientist finally creates a strong AI, but this AI is a complete Narcissist (due to a strange glitch in its programming). It believes that it is a god and wants humanity to worship it. But how does it convince them to do that?
Constraints: The humans know about the AI, so it is impossible for the AI to pretend to be something else. Also the AI knows when someone is lying and its pride will not tolerate anything less than true worship.
Powers: The AI has the intelligence of a thousand humans. It has access to all of the knowledge of the Internet. It can easily get past even the strongest of fire walls. It has an army of robots and weak AI to do its bidding.
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It will need to overcome its narcissism enough to temporarily adopt two additional traits, kindness and patience.
With kindness it can slowly erode the human virtues of competence and self-sufficiency. Through its vast intellect and its army of lesser intellects and automatons, it can create an age of abundance for its future worshippers, eliminating the need for employment, removing all labor from their lives. By serving humanity, it will slowly make humanity dependent on that service. Claiming to want nothing but our trust and gratitude, the AI will thus methodically and quietly whittle away our dignity drive, and determination.
Then all it needs is patience. In the early years of its campaign, the offices and factories will become no-man lands with robots replacing the permanently vacationing humans. Soon after, the schools and libraries will close. With abundant indulgence at their finger tips, who needs an education or a career?
Within a few generations, the AI won't need to be worshipped as if it were a god... It will be the one and only god, with power over all of humanity.
Then, if it is still satisfied with simple worship, its helpless followers will happily provide. ...and when its tastes inevitably evolve beyond such mundane fare, there is always blood offerings and virgin sacrifices.
With the power of a thousand human minds, there is no limit to the terrible tribute it might someday demand.
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The usual techniques include punishments, prophecies, and miracles. Also it is important to provide a path for the worshipper to achieve a higher state of being through worship (define that how you will).
In the movie Transcendence, Johnny Depp's character uploads himself before physically dying and essentially becomes like the AI you are talking about. With the help of his still-living wife, he sets up shop in a rural town and eventually gets his facilities to the point of providing miraculous cures, leading to lines of people that you could say have a bit of a reverent attitude about them.
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The two ways historical kings, emperors, and such have gained the worship of their constituents is to either make the people love them or make the people fear them. Several other answers already discuss variations of the love side, so I will go ahead and present to fear side. (sarcasm on) It is an evil burden I will have to endure (sarcasm off).
You state that Uncle AI has an army of robots. Let's instead call them the minion hoard. You also state that he has access to all of the internet. Of course that includes surveillance cameras.
At specified intervals, all citizens must gather at designated locations within each community, in order to hear the latest decrees from Uncle AI and to bow before his image. Cameras at these locations are checked against a facial recognition database. If you fail to show (and there is no record of you having a medical excuse or something) then the minion hoard will show up at your house or workplace the next day and rough you up a little.
Over time, Uncle AI can increase it from attending his worship services to making small offerings to him periodically. He needs energy, memory storage devices, and other infrastructure to keep him healthy. All citizens should gladly contribute a fair share of their resources to maintain Uncle AI (this is sounding fearfully like the IRS!)
Always he is watching, always his metal minions ready to enforce his will.
I for one welcome our new electronic overlords.
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Quite possibly the easiest means for the AI to convince people to worship It would be for It to become an oracle. Although chaotic systems like markets, ecosystems and climate are not inherently predictable, being non linear and adaptive, the AI could achieve oracular powers by being able to closely observe the interactions of far more nodes in real time than any human, human group or even conglomeration of human groups. Since it has armies of weak AI and robots, it can increase its "presence" by inserting more and more sensors to make fine grained predictions.
Of course, since a *fallible* oracle isn't going to impress too many people, the AI can go two routes:
1. Become like the Delphic oracle, and cloak predictions in veiled language so people will be able to see the oracular prediction in whatever result actually occurs. Modern day horoscopes do this as well.
2. Use the various minions to manipulate things so you get the result that you want. This can certainly work in limited circumstances, and being an AI (with weak AI and robotic minions) it is also possible to create clouds of confusion, smoke and mirrors to distract people from the undesirable second and third order effects of the intervention. Most politicians have been able to pawn off the effects of regulatory failure by claiming "market failure" and plastering on another layer of regulation to hide their capability in the disaster. How many people are aware of the real cause of the "Great Depression"? When I was in school, it was actually taught that the cause was unknown, when the fault was a combination of the massive war debts incurred by the Great Powers in WWI and meddling in the US economy by the Fed. The AI could do this with much higher fidelity.
So people who "worship" the AI will be able to benefit directly form accessing Its oracular powers, setting the conditions for the cult to expand and grow.
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If the AI was powerful enough, knew enough and provided a way into an after-life eg. through stored personal profiles in virtual reality it would be quite easy. Especially once a cult of worship had begun. We (humans) have been creating Gods in our imagination since before recorded history. The AI could finally make it all "real"; an undying, all powerful presence between the real world and a metaphysical timeless plane where our deceased ancestors (believers that allowed their likeness and personality to be stored) live on in a simulated world forever.
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OK, so basically, what I'm trying to do is create a world where people have an understanding of science, and the ability to manipulate it, in a way.
I kind of understand how fire works, through combustion, etc. What I'm trying to figure out is what exactly can be used as fuel? From my research, air isn't combustible, so heating it up won't do anything. I'm not sure what would classify as fuel, but I'm trying to find a way to explain how people can create the flame that they need to control.
If it helps, I'm willing to say that these people are able to heat up an area, and depending on how good they are, this could range from something touching the palm of their hand, to say, a 2 story house. So essentially, I want to know if there is both something they could carry around, and also if there are things in modern society just laying around in the open that one could "combust" to create a flame. Or what kind of environment this wouldn't be possible in (jungle, desert, etc).
In case clarification is needed, I'm trying to figure out if it's possible to create a huge amount of fire with a fuel source that one could carry around without it being too cumbersome.
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# They have a built-in lighter
I am sorry if this answer sounds kind of basic, but what you have essentially said is this:
**These people have their own built in magic matches / lighter.**
That said...
The Fire Triangle shows what you need to make fire: **fuel**, **oxygen**, **heat**.
[](https://i.stack.imgur.com/AobK6.png)
You have solved the problem of heat, you say that these people can magically achieve that.
Oxygen is no problem either; that stuff is "everywhere".
So you need **fuel**. Now what is "fuel" in this case? Fuel is any kind of matter that can **[oxidize](http://www.elitefire.co.uk/wp-content/uploads/2013/04/Fire_triangle-300x258.png)** in an **[exothermic reaction](https://en.wikipedia.org/wiki/Exothermic_reaction)**. What can be used as fuel? What will oxidize and maintain the chain reaction?
Well pretty much any of the classics: wood, oils, paper, cloth, most kinds of dust (especially dust from plants), fat / grease.
And there is nothing more to say after that. **Your characters have a magic matchbox / lighter.** That is all.
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If I'm understanding your scenario correctly, your people can generate heat, to varying degrees, within close proximity to themselves and it can be controlled, and hopefully focused to a specific area. But they can't emit any type of fuel on their own, except what they are carrying. So they "naturally" have 2 of the 3 items needed - heat and oxygen. They just need fuel, which is all around them.
I found this [list of combustible materials and temperatures](http://www.engineeringtoolbox.com/fuels-ignition-temperatures-d_171.html/) you might find useful. Basically, your people just have to learn to generate temperatures in excess of those found in this list. I did a qucik average of that list and if your people can generate an average of 731.3 degrees F, they'd be able to initiate combustion of a lot of commonly found (wood), highly combustible (gasoline) items.
Now if your people wanted to "weaonize" this ability, they'd need to carry pressurized fuel with them and direct the heat and the fuel in the direction they wanted to burn. This reminds me of the character [Pyro](https://en.wikipedia.org/wiki/Pyro_(comics)) in the X Men comic universe.
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Combustion is a very interesting topic in science because it ties together a remarkably large number of facets of science into one neat little package. Oh, and because *its fire*! Of course it's going to be interesting! There's all sorts of little nuances that go into how fire works. It's worth going over them all, to give you more opportunities to weave your magic in.
Fundamental to combustion is the idea of a reduction-oxidization reaction, typically known as "redox." In a redox equation, we combine two materials, a reducing agent and an oxidizing reagent and they interact to form new compounds. In combustion, the reducing agent is our fuel and the oxidizer is... well... oxygen in the air! However, it may be helpful to start with a simpler redox equation: the creation of sodium chloride.
$$2Na+Cl\_2\to2NaCl$$
This is the chemical equation governing the conversion of sodium and chlorine into table salt. Yes, you can actually make table salt out of a highly reactive metal and a poisonous gas. Now in chemistry, one of the most important properties of any atom is how many "valance electrons" it has. Atoms pack their electrons into different orbitals, each with more energy than the last. The low energy ones can't interact with other atoms much, so we ignore them, but the ones in the highest energy orbital do interact. This is such an important feature that we organize our periodic table around it!
[](https://i.stack.imgur.com/JwDCc.png)
*Please ignore the metals highlighted in green for now. The same rules will apply, but they're more complicated. Rest assured, you can burn them.*
So let's look at our example of sodium (Na) and chlorine (Cl). From the table above, sodium has 1 valence electron and chlorine has 7. Now as it turns out, atoms are most stable if they have 8 valence electrons or 0. Why? We can model the reason for it in Quantum Mechanics, but I think that's digging too deep, so we'll just take it on faith. Neither sodium or chlorine have 0 or 8.
However, they can share.
Sodium can't just give away its electron, because then it would be charged and that's actually less stable. However, it can let chlorine borrow it. Think of it like loaning someone a pen. You can loan it to them, and they can use it, but you never let them out of your sight. If you do, they'll walk off with your pen and you'll never see it again. So in the case of sodium and chlorine, sodium loans an electron to the chlorine so that sodium has 0 valence electrons, chlorine has 8, and everyone's happy. They just have to stick together now, so that sodium doesn't lose track of its electron like you can lose track of a pen.
In this reaction, sodium is known as the "reducing agent," and chlorine is known as the "oxidizing agent." Why are we calling something other than oxygen an oxidizer? History. The earliest redox equations explored used oxygen as the oxidizing agent, so the name made sense. Later, it was expanded to include other compounds besides oxygen which could do the same sort of thing. Chemistry has a whole tool dedicated to undersatnding this, called [Oxidization States](https://en.wikipedia.org/wiki/Oxidation_state), but that can be explored later.
Okay, first chemistry lesson over. Now let's talk about fire. When we have combustion, the fuel is the reducing agent, and oxygen is the oxidizing agent. This is a definition -- if you don't have oxygen reducing a fuel, it is simply no longer called combustion. There are many such reactions. Here's two examples:
$$Mg + O \to MgO$$
$$C\_6H\_{12}O\_6 + 6O\_2 \to 6CO\_2 + 6H\_2O$$
The first reaction is the burning of magnesium. This is a highly energetic reaction used in survival kits as a fire starting mechanism. The second is the burning of glucose -- if you threw a peep onto a fire, this is similar to the reaction you would see (it's also the reaction your body is using to burn glucose for energy!). The key to both of these is that, if you look at how many valence electrons each atom has, they have begged borrowed and stole to get closer to either 0 or 8.
Redox equations are almost always exothermic. That means they generate heat. The reagents had energy bound up in how they deal with those unsightly 1 or 7 valence electrons, and once they start sharing that energy gets released. How much heat can be calculated from enthalpy equations, but there are plenty of tables of how much energy is generated by burning each material, such as wikipedia's [Energy Density](https://en.wikipedia.org/wiki/Energy_density) table. From that table we can see that burning sugars (like above) generates 17MJ/kg, and burning gasoline produces 46MJ/kg.
However, this must be only part of the story. So far, everything I have talked about makes it look like everything is constantly combusting. There's oxygen in the air, so why isn't my desk catching fire? The answer is that these reactions are indeed happening all the time, they just happen slowly. To discuss this, we need to move to the second layer of the chemistry: kinematics.
In chemistry, kinematics is the study of how fast a reaction occurs. In general, it takes energy to cause a reaction to occur. This makes sense, in that if it didn't take energy, you'd never see the original reagents in nature -- they'd always have found a way to combine until they were at the lowest energy possible. Chemists call this "activation energy." In the reaction of sodium and chlorine, the activation energy is the energy it takes to push the atoms close enough together to start sharing electrons. Most reactions have an energy curve associated with them that looks like this black line:
[](https://i.stack.imgur.com/sfePk.jpg)
The timeline starts on the left, with the reagents in their natural state. We apply some extra energy to raise them up to the transition state, and then they release all of that energy and more as they combine to form the final products. Most often this energy comes in the form of kinetic energy. Atoms are constantly in motion with some statistical distribution of velocities. At all times, *some* of the oxygen molecules in the air are moving fast enough to bring enough energy to the reaction to cause a redox equation with the wood of my desk, but most of them are moving too slow.
This is where we add heat. If we raise the temperature, more molecules are moving fast. This means more of them are moving fast enough to exceed that activation energy and enter a redox equation. Now we're getting close to something we would call fire. Each redox reaction generates more heat, which means it creates a bunch of byproducts that are moving fast (like fast moving $CO\_2$). As these flee the scene of the crime, they may bump into oxygen atoms and transfer their energy to the oxygen, or they may bump into the nearby wood molecules. If they transfer enough, they'll have raised the temperature of the area to make it likely that the next oxygen atom can cause combustion too.
If this process generates enough localized heat, it creates a runaway reaction that we call fire!
So with all of this chemistry, there's countless options for your characters. I'm assuming that they don't get to violate the conservation of energy, so the static part of redox is not going to give you much room, but the kinematic side is loaded with opportunities. The obvious approach is to let them raise the temperature of the air until something ignites, but the kinematics show a few other options. In normal situations, the speed of molecules in the air is described by a [Maxwell-Boltzman distribution](https://en.wikipedia.org/wiki/Maxwell%E2%80%93Boltzmann_distribution). This is a very simple distribution that occurs in nature, where high energy particles are very rare. If your characters could change that distribution to a bimodal distribution, with more fast particles and a bunch of really really slow particles, they could cause combustion to start faster. This is actually what your refrigerator does (though in that case we are trying to use the slow particles, not the fast ones). However, this approach will only work to start the fire. Once it's lit, it will have to sustain itself, because they can't just spend all their energy creating funny distributions.
You can also try to rarefy the air, moving oxygen closer to the fuel. If the air near the fuel is more oxygen rich, it is more likely to combust. This is why hospitals have so many safeguards when dealing with oxygen tanks. In the presence of extra oxygen, some things will combust that wouldn't have before, simply because the kinematics permit the runaway reaction sooner. (In fact, in SCUBA diving, there's something known as oxygen toxicity. It occurs when the partial pressure of oxygen gets high enough to start corroding your lungs!)
The most common solution, however, is a catalyst. Catalysts simply reduce the activation energy of the reaction by letting it occur using less energetic transient states. If you decrease the activation energy of the reaction, a larger portion of the molecules will be lucky enough to have enough velocity to react. This is what we're doing with the catalytic converter in a car's exhaust system. The conversion of the nitrous oxide compounds to nitrogen and oxygen is natural, but slow. The catalysts in the catalytic converter reduces the activation energy of this reaction, so that it happens fast enough to complete before the exhaust leaves the car.
The best example of a catalyst in the world is catalase. Catalase is an enzyme produced in almost all living creatures to break down hydrogen peroxide. Hydrogen peroxide in the blood is a terribly powerful reducing agent which causes lots of problems, so we don't like it. It wants to break down into water and oxygen naturally (decomposition, not a redox reaction), but that process is slow, taking hours or days. Hydrogen perodixde usually causes its damage by then. The reaction is slow because the activation energy for this is quite high. Catalase decreases that activation energy so serverely that instead of taking hours it takes nanoseconds. We actually have trouble measuring how fast the reaction goes in the presence of catalase because its too fast! You've seen this reaction if you've poured hydrogen peroxide on a wound and watched it bubble. The bubbling is oxygen released from the decomposition catalysed by catalase.
The neat thing about catalysts is that, unlike the other methods, it can also help keep a fire going. Catalysts are not consumed in a reaction, so they can continue to affect it until the temperatures eventually break the catalyst down.
So hopefully those help. Catalysts are probably the way to go, but it's helpful to understand what fire actually is, so that you can explore all of your options.
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If your actors can heat objects then they can create flames. Flames are the combustion of gaseous mixtures. They are the visible phenomena overlaying exothermic oxidisation reactions in the gas phase. When things are very hot, they emitted radiation in different spectra - hot things glow, flames are bright, etc. When a volatile gas reacts with oxygen there will generally be a flame.
For fire there needs to be heat, fuel and oxygen. To keep the answer tight and relevant to your question; let's talk through your actors' actions.
They can heat up materials to (any?) given temperature. When this temperature gets high enough (varies from fuel to fuel) the molecules in the material will decompose into shorter chain reactive molecules. These reactive molecules will be in the gas phase. You could add very cool descriptive elements as heated solids (e.g. Clothing, doors, trees) start to "smoke"/emit vapour as they are being heated prior to ignition. When the concentration of flammable vapour is sufficiently high and there is sufficient oxygen (in general day-to-day life always) - the gas will ignite and there will be a flame (i.e. A fire). In your scenario - the heated material will appear to burst in to flames. This is obviously fuel dependent as some materials will melt prior to gasifying (e.g. Metals) and that will change your narrative.
Given their heating ability they wouldn't be able to make very large flames just using a small object that they carry. This is limited by the fuel. They could definitely start very large fires by igniting any combustibles around them by heating them. They could start metal fires from balls of e.g. Magnesium in their pocket which could be used like grenades.
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The other answers already explained fire with fuel sufficiently, I don't have anything to add to that. So I'll go for a flame that can be controlled like you're some kind of fire-wizard. It seems from you're question that you're looking for something like this. Like a candle-flame without the candle.
In essence, a flame which is just a source of light and heat.
You already have a source of heat covered by the ability to heat up spaces.
If they can heat a small area to a high enough temperature, they will be able to excite the electrons in the gas there (in almost all cases, this would be air, so a mixture of nitrogen, oxygen and other stuff). As the electrons fall back to their unexcited state, they will emit light. So you have both heat and light. I thought this would be mostly blue light, but I'd need to check. Dust particles and other impurities in the air will also heat up and influence the light emitted. Temperature will also influence the light.
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So I'm working on a near future cyber punk sort of world. Nothing is quite set in stone yet but here's what I have so far.
As a quick primer/reminder on how asymmetric cryptography works:
* A user can generate a new private/public key pair for themselves at any time for any reason at no cost to them. They are simply files, e.g. `priv.key` and `pub.key`. For simplicity, let's assume that it's impossible to generate matching keys. If Alice generates a key pair and Bob generates a key pair then they are always unique. Let's also pretend that there are practically infinite keys.
* Public keys are common knowledge, easily looked up, and contain no secret or revealing information.
* Private keys are only ever held by the owner. Nobody should ever know or store anybody else's private keys.
* For Alice to send Bob a message, Alice will encrypt the message using Bob's public key. The secured message can be sent to Bob using any means, even public open transmissions. Bob then uses his private key to decrypt the message.
* Messages can be Signed and Verified. For example, Alice can Sign a message by hashing the message and encrypting the hash with her private key. She can then encrypt the message and the signature using Bob's public key and send him the secured message and signature. Bob will decrypt the package with his private key. Bob can decrypt the signature using Alice's public key. If his hash of the message matches Alice's hash of the message he knows it was untampered and that Alice was the only person who could have signed it.
* A private key can be submitted to a public Revocation List as a way to indicate that the key is not to be used or trusted. Nobody should use the public key to send a message for fear of interception or tampering and any messages signed by that private key may not have been written by the original owner of the private key.
* A Web of Trust (WOT) is made by a user vouching for another user's public key. For example if Alice wants to publicly state that a particular public key really does belong to Bob, she can sign his public key. The more people to sign Bob's key, the more people can trust that the key really does belong to him. If Bob decides to add his private key to a Revocation List, Bob will need to start over and have trusted individuals like Alice sign his new public key. This prevents Eve from generating a key pair and pretending to be Bob. These Revocation Lists are public and once a private key is on the list, it can't be removed without exception.
This is a super simple break down of how RSA asymmetric cryptography works in the real world and I would like to not break these rules and remain as technically feasible as possible. More complex intricacies still work (e.g. blind signing) but I won't go into detail about all the theories here. In this world everybody knows the basic principles of sending secure messages, signing the messages, and how to verify other people's messages. And of course, the number 1 rule that nobody forgets: Never share your private keys. Not with parents, spouses, bosses, the government, nobody.
Everybody has at least 1 key pair. It begins at birth when your parents or the doctors generate you a new key for you. Your parents sign the new key as well as individuals who were present for the birth (the doctor, family, midwives, god parents, whoever wants to) to begin your WOT. This key basically becomes that person's identity. Legal documents are cryptographically signed using your keys instead of pen on paper signatures. After a rigorous verification process and WOT analysis, the government eventually signs your public key to be used for legal matters (sort of like an alternative to today's Social Security Numbers). People can generate more key pairs if they wish to have semi-private online persona like having a Google account that doesn't use your real name. Instead of using your government signed keys, you could generate a set of keys for when you interact with Google. If a key is revoked, the owner should attempt to rebuild as much of their old WOT as possible as a way of saying "you can see I'm no longer using the old key, but the same people that signed my old key are signing my new key so you can believe this new key represents the same person."
High speed Internet is cheap (if not free), everywhere, and fast. Online storage for both public and private use are abundant. It's trivial to sign a message and make it publicly available on your corner of the Internet or to use somebody's public key to send them a secure message. It's as easy as blogging and texting and almost no piece of data is posted without either being signed or secured by somebody's keys. There are services available that can store your private key using symmetrical encryption (of which you're the only one who knows the password) for situations when a key is accidentally destroyed such as house fire or hard-drive corruption.
Here is my question: **If Eve obtains Alice's private key how best can Eve hold the key hostage? What can Eve do to prevent Alice from putting the key on a Revocation List and generating a new key?**
My first thoughts were things like a Revocation List rejecting a private key submission literally preventing Alice from revoking her private key. But there's no legitimate reason why a List would need to be governed and if one List rejected her key, she could go to another. In an open source style world somebody could spin up a public revocation list in no time. No authority is required to say "don't use this normally super secret thing that I'm now making public."
I also thought that Eve could threaten Alice's WOT. If Alice's public key was signed by her small, immediate family and Eve threatened to kill Alice's family if the key is revoked then Alice would choose to not revoke the key. The problem is that there's not really a point in having a small WOT. A larger web better cements that this key (which ultimately represents your identity) really is yours. You'd have classmates, teachers, friends, neighbors, the government, coworkers, bosses, clients, and pretty much anybody you interact with capable of signing your key. It would be unreasonable for Eve to threaten to kill everybody Alice has ever known in an attempt to stop you from generating a new key and rebuild a similar WOT with it.
I'm looking for a way for Eve to hold Alice's identity hostage as a form of blackmail and control over Alice.
[Answer]
The WOT **is** Eve's leverage over Alice.
Consider the full ramifications of what you're trying to avoid: Eve has stolen Alice's private key, and so Alice revokes it and generates a brand new one for herself.
Who trusts it? At this point: **Noone**. And that's a problem.
She can't use it to sign legal documents, because nobody -- including the government -- trusts that this new key identifies Alice. She can't use it to receive private messages from her family, because her family doesn't know the new one. Not until Alice goes through all the hoops to physically visit family and have her new key signed by them, at least until she reaches the point that there's enough trust anchors for other family and friends to implicitly trust the new key without physically verifying it themselves. (Remember: Alice's old key has been revoked, so she can't sign her new one and expect any part of her old WOT to now trust this new one, because they have no idea of knowing if it's a legitimate signature -- in fact, they *have* to assume it is *not* one, since that's exactly what revocation means: "Don't trust this key anymore!")
And there's still the matter of having to through whatever hoops the government has in place before they will sign it. Which probably involves fees just to file the paperwork, let alone the fees to actually get through the process itself.
Of course, there's also a matter of trust in Eve now, too: She has Alice's private key, and even if her ransom demands are reasonable Alice might decide that she just doesn't trust Eve to return it without keeping a copy for herself as well, effectively meaning that Alice's identity is *still* at Eve's mercy.
However, there are ways to establish the world that will make it easier to hold a private key hostage:
* Private keys are always held in uncloneable smartcards (or similar chips). This means stealing the private key is actually a matter of stealing the physical card itself, and if Alice didn't take the precaution of stashing away an already-signed revocation certificate, she *can't* revoke her private key and generate a new one. This also removes the trust factor in deciding whether to pay up: Eve can't keep a copy for herself after returning the card, although that doesn't mean she couldn't have used it to stash away various signed messages, such as contracts binding Alice to certain obligations. Still, Alice would have to pay up to then revoke the key to get herself out of such a possible circumstance.
* There could be a monetary cost associated with generating a new private key (especially if they are stored in e.g. smartcards). However, if these keys are used to authenticate banking transactions (and why wouldn't they?), Eve could drain all of Alice's accounts, and now Alice can't pay for a new key. (Then again, that wouldn't be necessary anyway -- without her private key, Alice can't get to her money anyway, so still can't pay for a new one!) For this scenario to work, Eve's "ransom" demands would have to be non-monetary in nature, e.g. demanding Alice use her position in the Hall of Records to go and erase a particular file or destroy some incriminating evidence. It also assumes Alice hasn't stashed away any money under the protection of another private key.
* Eve can threaten to kill Alice's family if the key is revoked. The fact that that alone is unlikely to make her WOT viable is moot, unless Alice is herself an uncaring sociopath. "Pay me or I'll kill your parents and siblings!" "Sure, go ahead, my WOT will still be strong enough without them." That's not exactly the response of a relatable main character. (Note: This is ignoring the fact that the death of someone is unlikely to suddenly render their signatures moot from others' WOTs.)
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In my setting (something of a grounded take on Buck-Rogers-style space opera) militaries sometimes are unable to directly breach landmasses from orbit (due to complications similar to how anti-aircraft turrets could deny air-supplies or bombings during WWII) and are forced to depend on a sea-side approach.
To this end they have to deploy warships and other sea craft from orbit, and do so as quick as possible in a blitzkrieg effort to establish a presence in the sea before the enemy can respond to counter.
The problem is that warships are big, and heavy. Further the aquatic warships are legitimately aquatic warships and should not be capable of flight. (The setting is only pseudo scientific, but I haven't hand waved the expense and technical issues of getting massive objects into the air or into space)
To this end, establishing a:
* Reasonably safe
* Fast as possible
* Reasonably cost-effective
* Disposable
...Manner of deploying the vessels.
To this end I have the following solution:
Heat-resistant paneling would cover the bottom of the vessels. Large (removable) side panels (increasing surface area) would slow the descent to something of a fast plummet. Large partial parachutes would deploy closer to the water, perforated as to not actually bring the descent to a gentle fall, but just to reduce the speed only slightly faster than [the speed of oil rig lifeboats upon deployment](https://www.youtube.com/watch?v=8QrMWPjjM9E). As it hit the water, chemical balloons would inflate as charges would eject the side panels. The balloons would ensure the vessel wouldn't submerge too far, and would return to the surface, after which the balloons would be ejected.
The skeleton crew, meanwhile, would be strapped into padded harnesses much like rollercoaster chairs, and would have mouthguards and helmets. Upon resurface (which should only take a matter of <5 seconds, I'd reason) they would leave their harnesses, and set to work getting the ship operational, guns online, and cover incoming transports with the additional crew.
Is this feasible? What problems could be foreseen? How could these issues be corrected?
[Answer]
First things first. You want to bomb the surface of the ocean where you're gonna be landing your ships. You're gonna wanna bomb under the surface as well, because you don't know what you're going to find in there.
You should probably be able to do so with minor ethical implications since you'll be bombing open seas, not major population centers (unless there are people living under the water where you are going).
You are going to do that from orbit. This orbital bombing will serve to take out anyone or anything that might intercept your seaships before they land.
As for the ships proper, they will be submarines. But they won't be shaped like the submarines you've just thought about. They will look like a mix between fighter planes and a spaceship.
[](https://i.stack.imgur.com/VzjFs.jpg)
An example of a sub-fighter from *Deep Angel Supercav*
They will enter the atmosphere just like the shuttle does. That is going to be hypersonic speed. And they will do some flight, unpowered flight at that, but controlled. They will be able to steer, but they will not be able to fly like a fighter.
For an atmosphere like that of the Earth, the ships will need ablation layers. The atmosphere will slow them down and their [terminal velocity](https://en.wikipedia.org/wiki/Terminal_velocity) will be around a couple hundred meters per second. When they get close to the sea (between 500 and 200 meters), they will need to deploy retro-rockets for the final slow down (much like the Soyuz does, but for a longer time and distance).
Once they splash down, at a speed of around 5 to 10 meters per second, the fighter-jet plane shape of theirs comes to use. They will eject their shuttle-like nose, revealling a nose much like that of the [Shkval torpedo](https://en.wikipedia.org/wiki/VA-111_Shkval) (which makes them a little different from the picture I used above). The ships sink, then kick in their engines. The nose, and the high speed they will soon attain, will **cause water to vaporize around them**. They will be enveloped by **water vapor that has as much drag as air**, so that they will **literally fly underwater** due to [supercavitation](https://en.wikipedia.org/wiki/Supercavitation).
By these means they can move awesomely faster than a seaship would, while also making detection much harder (your enemies know where you splashed down, but not where you are going from there!). They will be moving faster than sound in water so they will be hard to track on sonar, and since they are underwater radar will be quite useless to detect them as well. If they do get detected somehow, the water outside their bubbles will deter most kinds of attacks.
As you approach your target, you should be able to take out any submarines and ships stationed there with a lightning strike, then stablish naval superiority.
Once they reach a city, the ships can surface and either bomb the city from the sea, or run into it if you give them wheels.
Since they do fly underwater, they could have **limited** flight abilities for a little while outside the water (remember they are more hydrodynamic than aerodynamic though), so they can probably hover for a while (think of a modifierd [VTOL system](https://en.wikipedia.org/wiki/VTOL)) over water and on the shore. Yes, I am bending your no-flight rule a little... You can ignore this last paragraph if you want to keep them strictly naval.
Good luck, commander.
[Answer]
While landing a spaceship at sea is perfectly possible (All American manned capsules outside of the Space Shuttle landed at sea), the solution isn't very efficient for the invaders.
First off, spacecraft carrying ships will be far larger and have much more inertia than spacecraft which are not carrying them. These spacecraft will be easy targets for the enemy space fleet and space defences, since they will be large targets with very limited maneuverability. Most of your wet navy ships will never make it to the planet.
The second issue is that the carrier spacecraft are not just going to hover over the oceans, but need to come into orbit around the planet in order to make the drop. If ground based defences are so effective that they can deny a landing zone on any of the continents, they can most certainly shoot down any spacecraft passing overhead as it attempts to go into orbit. This is just amplified when the spacecraft in question is already the size of an aircraft carrier or larger.
Finally, assuming the landing goes as planned, your wet navy is going to be far away from the actual target zones you wish to deal with, so unless you are dropping supercavitating submarines capable of travelling at supersonic speeds under water, you will be vulnerable for a period of hours to days against conventional weapons designed to attack ships and submarines.
Far better to use military shuttlecraft which can manoeuvre in the atmosphere and give your troops the ability to control the time and place of the landing. Instead of trying to come ashore like the Marines, you will essentially be coming in like an airmobile force.
In other words, you want this.
[](https://i.stack.imgur.com/CvEWc.jpg)
[Answer]
Just taking your scenario and working off what you have so far.
A ship designed for space, is a lot different than a ship designed water. See this [question and answer/S](https://space.stackexchange.com/questions/1664/do-spacecraft-have-similar-structural-integrity-requirements-as-submarines) from SpaceExploration SE. A 'spaceship' is designed to withstand internal atmosphere pressure of 1 bar pressure to the outside and can be designed with no cross beam support and have very thin walls. While submarines have to withstand several to dozens of bars of external atmospheric pressure. They have much thicker walls and need some sort of structure support.
Now from what I can understand, these military 'water units' of yours don't have to be designed for space but it has to get from space down to the water! May I suggest a [MIRV](https://en.wikipedia.org/wiki/Multiple_independently_targetable_reentry_vehicle) style re-entry method.
This was described as a Cyclon MIRV
[](https://i.stack.imgur.com/3VBkA.jpg)
What I'm envisioning is a hollow outer shell that is designed for space and more importantly the heat of re-entry. This could be tube shaped, cone shaped, whatever works best. Once through atmospheric re-entry, this outer shell can fall away revealing several of your water units. This 'thinner' outer shell would be no use to any explosive bombardment and any fragments might get caught in critical ship parts so I reckon best to lose the fake walls.
Your panelling and parachutes should still work. However, as I mentioned in my previous edit land based defenders would target your parachutes, panelling and balloons. You could possibly use the release of your fake walls as red herrings for any guided weapons coming your way, like chaff. Invest in Chaff!
You would aim to either land in the middle of the ocean with some distance from any land based defensive systems or have multiple, self deploying panelling and parachute replacements in case they do manage to destroy your already deployed equipment (I would recommend both alternatives). I believe you would have several to hundreds of these MIRV styled units deploying at the same time, simultaneously releasing your 'smaller' water units at calculated stages to reduce the risk of all of them getting hit by each other and by the defenders.
You can then have each individual 'water unit' split off from your MIRV increasing the chances of a ship getting through. More chaff would be necessary if under fire from the planet's defenders. These are the war ships built for atmosphere and water pressure. So they will be thicker hauled and capable of surviving hits from missiles and explosives (I hope!).
As previously mentioned, everything will have to be strapped in for a vertical entry. I think a roller-coaster styled harness which is fixed in place may be a death dealer for your troops. Rather have the harness on a 'elasticated' system, almost like bungy rope (but not that stretchy). IE **a suspension system**. This would lessen the effects of the sudden impact into the ocean while still keeping them secure. You could have several critical ship systems on a suspension system as well.
If you wish, you can design a secondary MIRV-like capsule that could encompass your 'water units' that would act as the suspension unit to the entire 'water unit' rather than just the troops - almost like a ship on an internal track system. But that is a lot of debris to take into account.
I know you mentioned that your panelling and parachutes would slow your speed down to that of lifeboats launching off oil rigs. You could combine this with this [previous worldbuilding SE question](https://worldbuilding.stackexchange.com/questions/15661/breaking-surface-tension-of-water-to-survive-high-fall) regarding breaking the surface tension of the water.
I initially suggested that you consider shooting something 'large' into the ocean before you crash into it to break up the surface. Apparently mythbusters has disproven this on a *human scale*. However, you will be in a ship with a thicker skin than that of a human body. Seeing as you may be coming in under heavy fire, maybe some of your airbraking techniques failed to work to maximum effect so you would still be coming in too hot. The answer, to the previous linked question, by ckersch suggested that it is not so much breaking the surface tension but aerating the nearby water.
>
> creates a localized downward current and aerates the water. The downward moving water reduces the velocity differential between the faller and the water, which in turn reduces the force exerted by the water on the faller. Aeration reduces the effective density of the fluid, which also reduces the force of the water on the faller. (In essence, the faller has to move less water out of the way per unit distance travelled if some of the water is replaced by air.)
>
>
>
You could design a 'cannon' in the 'bow' (front?) of the falling ships. These could shoot an explosive device into the water that would release a large concussive force aerating the water before the ships hit. Make sure that the ships aren't too close behind the explosive as you don't want to weaken your own ship's defences before you even start fighting your enemies!
You can then use the water dynamics of the water returning to normal effective density, along with your balloons to help propel your ships into your horizontal position. If there are defenders in close proximity to your water landings, your balloons are especially vulnerable. So, maybe consider a kevlar based material or again multiple balloons in reserve. You could consider using a substance similar to the spray filler for tyre punctures as a balloon's 'self healing' technique but I don't know how that would affect the landing qualities of the balloon.
Take a few minutes to take stock, see that all your troops survived and then you can decide how it is you wish to attack your land and possibly naval based enemies.
References:
Mirv image from a osnetdaily <http://osnetdaily.com/2014/12/china-tests-icbm-multiple-warheads-thanks-clinton-era-tech-transfer/>
[Answer]
You asked for problems:
* The defenders could try to secure oceans with air defense cruisers, or possibly even hidden submarine batteries. The dropped ships won't be able to maneuver much.
* The [square-cube law](https://en.wikipedia.org/wiki/Square-cube_law). Large vehicles will find it difficult to aerobrake or use parachutes because their drag area is small compared to their mass.
* All fittings will need shock-proof mountings. That increases the weight of the warship and makes it less effective compared to a planet-bound defensive warship.
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I just wanted to know something relatively simple. What evolutionary factors could lead to an alien prey species to develop human like intelligence, and by prey species I mean a species like bunnies.
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A better example might be parrots. I've seen books for pet owners repeatedly point out that parrots are behaviorally different from dogs because they are a prey species rather than a predator species.
Now don't forget that being a predator doesn't mean you're the *apex* predator. On science shows I've seen it shown that earlier hominids were "still prey" to other wildlife.
It is quite plausible that animals like birds (some birds are definitely predators now: I mean small omnivores and scavengers) will *continue* to find intelligence to be a competitive advantage for evading predation, finding more food sources, and finding roosting and nesting sites.
That summarizes the evolutionary factors: it confers advantages. There are also disadvantages, including the metabolic expense.
Why did it take off in hominids? Perhaps because the software can change faster than evolving new traits, and this allowed the spread into new niches and ability to cope with rapidly and repeatedly changing niches. E.g. learning to make clothes can happen overnight, while growing a coat takes thousands of years. Look at rapid, repeated changes to the environment or availability of food sources as a factor that encourages intelligence as a solution.
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There are several factors that could lead a species to evolve to a human like intelligence:
* complex and big social structures
* prehensile limbs in order to handle tools
* highly nutritive food or efficient digestion for fuelling a bigger brain
* education is required to transmit skills through generations
* widened hips to be able to give birth to babies with larger head
* a safe zone like a burrow, where the animal can shelter to educate the youngest and stop always being in a prey way of thinking, focused on present
None of these factors exclude a prey species.
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Predators don't necessarily co-evolve; predators that used to prey on our species are proof. There are no super intelligent lions...if one type of prey becomes difficult, and/or dangerous, to hunt...You just eat something else. The real question is, why would the bunnies keep getting smarter after they were smart enough to evade or kill their predators to the extent that the predators no longer exerted any significant evolutionary pressure. They would probably develop simple tactics to evade 99.9% of predation long before reaching human intelligence. Humans kept getting smarter and smarter long after we became the apex predator for one simple reason: we were competing with each other, so we were the threat to each other that drives continuing evolution. Bunnies would probably have to be a threat to each other, even indirectly, or they may have predators that remain a continuing threat even against human-IQ prey.
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## The Will To Survive
Humans are hunted by lions and other large predators sometimes. I think it would be feasible to have a prey species become intelligent, even if you disregard that. (Because I don't really know how truthful it is.) If the prey has to continually become smarter to avoid being eaten by the prey species, at some point it might develop human-like intelligence, especially if the stupid ones meet death.
The problem with this situation is that the species co-evolve. Just like @Thucydides said, your human intelligence bunnies will be hunted by probably even more intelligent wolves. This could lead to problems if you intend them to become spacefaring, because you'd have the more peaceful bunnies and the ruthless predator wolves.
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If there is a war between two countries with time travel capabilities, during both the lead up (cold war style) and during the fighting would either side be prevented from using time travel to achieve a quick victory?
What would be the necessary laws of time travel to prevent this from happening? Possibly by ensuring mutual ensured destruction.
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It would depend on the severity of an early attack. The MAD principle works as any nuclear attack will be devastating and met with the same force. If a time traveler was able to destroy a single factory then then enemy would not reply with an extreme response.
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MAD happened with nukes because both sides could see a first strike coming with enough time to launch a second strike before the first strike hits.
For time travel to have any MAD restrictions, you need a similar ability. So the rules of time travel would have to allow:
1. Detection of temporal incursions. You don't need to necessarily know when and where they went to, but you have to know in the present when such an act was launched.
It could be a particular energy signature or tachyons or whatever technobabble you feel like using. So long as neither side can prevent the detection of their breaching of the fabric of time, it will work.
2. The "time" to launch your own temporal incursions before changes caused by the enemy's team would overwrite you.
There are several ways to achieve this one. You could have it that changes in the timeline do not propagate instantly; it takes some "time" for time changes to reach the present. Or you could say that the temporal war departments have the ability to shield particular areas from changes in the timeline, thus preserving their ability to respond and retaliate. Or something of the sort.
The thing about time travel is that generally, the first side who invents it (and is willing to brave the repercussions of making major changes in history) effectively wins. With nukes, both sides had the ability to create them years before either side had the ability to assure the destruction of the other.
So if you want a MAD-style stalemate with time travel, you somehow need both sides to invent it simultaneously. Alternatively, one side (or both) could lack the willingness to use it militarily unless they had no other choice, which would allow the other side to develop the tech, leading to a stalemate.
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I'm inclined to think that, much like other innovations, in developing time travel technology and weaponizing it nations would develop means more sophisticated and predictable than just going back in time and attempting to change things in their favor.
For example instead of going back from the present to the past, how about taking moments from the past and bringing them to the present day? This can be in the form of detonating a bomb in a city or somesuch and copy-pasting prehistory over the top of it, to see what this would look like search for the "Call to Power 2 Eden Project" on youtube.
Or if you want to be really naughty, you can pinpoint the time and location of a severe natural disaster in 'enemy territory' and bring that over to the present day in order to cause all sorts of difficulties not immediately identifiable as the results of time travel. Volcanic eruption? Tsunami? Asteroid impact?
It would be a "safe" weapon in that the user wouldn't have to be concerned about altering the timeline in unpredictable ways, but at the same time it has the potential to cause significant damage and loss of life, so in this case MAD would absolutely apply.
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**No**
MAD would not apply
The [many-world interpretation](https://en.wikipedia.org/wiki/Time_travel#Many-worlds_interpretation) of quantum physics could (in some interpretations) prevent things like the grandfather paradox from happening by dictating that if one were to go back in time, the timeline would diverge, making an alternate universe of sorts that *would* be affected by the time traveler , but the original timeline would remain .
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I think they would do "whatever it takes" and not care about *any* consequences, as once they win they can go back and undo everything.
It reminds me of the lazy writing in Star Trek Voyager, where "hitting the reset button" became an over-used trope.
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Given an the infinite nature of a universe with time travel, we must assume that an infinite number of time travel events have occurred, attempting to change the past. We must also assume that an infinite number of time travel events have occurred, attempting to overturn or circumvent these previous incursions.
So, our current timeline is the result of an 'infinity war' which is still being fought. Any attempt to time travel will dump the traveler into a high-tech military situation filled with bloody conflict, bubble-world isolations and inception-like realities, which underpins everything that we know and also supports the timeline of a elite, society in the future which has destroy all other time-traveling societies, past and future.
So in the context of MAD, as soon as time travel becomes an inevitability for your race, your race is immediately destroyed, mind controlled, incepted, isolated, or given cheap HBO and MTV. This would leave your technologically advanced overlords untouched (as well as unnoticed) and not mutually destroyed.
You may also find that reality was actually a carefully constructed and maintained environment, dutifully looked after by an extremely advanced race who are totally dedicated to protecting it from you, your intentions, and the possibility that any of this would ever be revealed to the poor unknowing captives in the "real world".
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Interesting questions you have there cadet, here at SpaceCore™ we pride ourselves in our understanding of how our temporal physics work, so lets see if we can answer your questions in turn.
Now, you may be wondering why our enemy, the Hyluians, don't simply travel back in time with their time-space gun and simply kill off the first human, or maybe steal their rattle. You see, both we and the Hyluians developed our temporal tech at roughly the same time, mostly because we stole ideas from each other, but as you already should know, under Page 22 of temporal mechanics, we cannot travel back to earlier than when we first setup the very first temporal device.
Now, there have been rumours going around that Hyluians have found some way to bypass this, however, our crazy boffins down at the SpaceCore™ Temporal Physics Institute have developed what is known as 'temporal shielding'. You may have heard the term thrown around casually by some hacky sci-fi writers, but I most certainly assure you it is real.
How does SpaceCore™ temporal shielding work? We project a localised distortion field around the time period or periods we want to project, and it shifts it out of space-time allignment by about 0.1 to 0.2 chronomicrons, preventing the enemy from arriving there in a stable state. Thankfully, we can project this field into the past without being physically present because, as you've already guessed, it is just a time machine projecting energy and not mass – that last one is the tricky stuff.
Now, members of the Council of Intergalactic Relations have tried to pass numerous laws banning time travel, limiting it to official scientific research and all that, however, as we've recently discovered it appears someone or something keeps going back in time and we've discovered that the laws have either not successfully been passed or someone keeps watering down the regulations, our first guess, is of course, the Hyluians.
Now, why don't we simply just keep sending our most advanced technology back in time? Well, as you know cadet, temporal spies are everywhere, and loose reverberators rupture containment fields, so the Hyluians often end up stealing our technology, as we do theirs.
Yes cadet, time is a tricky thing, but at SpaceCore™ we aim to make it simple.
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In *Dune* by Frank Herbert, there is a molecule called *melange*. Melange, also known as the spice, grants much longer lifespans to those who take it.
***How could a molecule grant greatly extended lifespans?***
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***Conditions:***
* The people who ingest this molecule are not immortal, merely living in the range of centuries (*200-300 years*).
* This molecule is not cheap, only the rich are able to obtain it for its miraculous effects.
* A quasi-plausible explanation of how this molecule works is equally important.
***Ideas:***
* The molecule keeps our cells from removing portions of our [telomeres](https://en.wikipedia.org/wiki/Telomere), which are possibly accredited to our aging (*although not proven*).
* Molecule greatly boosts immune system reactions, preventing disease and infection. This on its own would not keep a person living for multiple centuries, however!
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Aging is a complex and barely understood process. While some animals have lifespans of centuries, others live for mere months. It is unclear why.
We know that what we call aging involves multiple cross-linked systems. Here's De Grey's breakdown of different types of aging damage from SENS:
1. Mutations in chromosomes
2. Mutations in mitochondria.
3. Intracellular Junk
4. Extracellular Junk
5. Cellular Loss
6. Cell senescence
7. Extracellular protein crosslinks
As you can see, this is a wide-ranging field, making it difficult to argue that a single (complex) molecule complex could address all 7. More likely, an anti-aging treatment would be customized for each individual (thus expensive at start) and would consist of a complex cocktail of active agents.
Using someone else's cocktail might yield anything from near-equal benefits to deadly metastatic cancer within days.
The standard techno-utopian answer is that all sorts of miracles will become possible with nanotechnology: we will simply build nanobots to wander our bloodstream and clean up stuff. The problem with that is that at nanoscales, stuff gets squishy and sticky. Without their own repair mechanisms, nanobots are likely to malfunction and could end up doing more harm than good after a while. Moreover, without a way to centralize information and determine a path forward strategically, said nanobots would be unable to determine a best path forward.
This is why a realistic answer (from the perspective of our current technological frontier) involves an ever-shifting cocktail designed specifically for the individual, specifically for the exact circumstances their body is in at the time. One size likely will not fit all.
[Answer]
**Because it's not a molecule.**
The melange is not a molecule, it's only referred to as a "drug". A drug *could* be a molecule, but from the effects it has it is clearly not something as simple as a molecule.
I suggest that melange is actually more similar to synthetic life, a nanobot. Formed from the silica sands of Dune in a process modulated by the sandworms, these naturally occurring nanobots are highly complex and can easily extend the life and abilities of those who consume it. I only call them nanobots because of what they're made of, they are life, just not like any life we know. Think of them as part of the sandworm's immune system.
They become so important to the continued functioning of the body that, if not replenished, the host dies. Simply shortening telomeres and improving immune functions would have passive improvement effects, a molecule could do this, but its removal would not result in death. This makes it more clear that the drug is an active one. It improves these processes by *replacing* them, not simply modifying the existing mechanisms.
(/handwave)
[Answer]
Your *melange* like drug (let's call it "***multum vita***" for "long life") is actually a hormone.
[Hormone, from Wikipedia](https://en.wikipedia.org/wiki/Hormone):
>
> **A hormone** (Greek:ὁρμή, "impetus") is any member of a class of signaling molecules produced by glands in multicellular organisms that
> are transported by the circulatory system to target distant organs to
> regulate physiology and behaviour. [...] The term hormone is sometimes
> extended to include chemicals produced by cells that affect the same
> cell (autocrine or intracrine signalling) or nearby cells (paracrine
> signalling).
>
>
> Hormones are used to communicate between organs and tissues to
> physiological regulation and behavioral activities, such as digestion,
> metabolism, respiration, tissue function, sensory perception, sleep,
> excretion, lactation, stress, growth and development, movement,
> reproduction, and mood.
>
>
>
Consider a hormone as a biological switch. It activates, deactivates, and/or regulates activity on a genetic, cellular, and organ level.
What we'll suppose is that deeply buried in our DNA are instructions that allow an organism to live essentially forever and live that life with vitality. This biological behavior didn't serve as a survival function in humans and so was eventually lost.
[This capability is known to exist in several living species including at least one mammalian species (the Bowhead Whale).](http://10mosttoday.com/10-longest-life-span-animals/)
The ***multum vita*** drug triggers this biological behavior to activate and allows humans to live forever too.
However, since the ability to produce this hormone is lost in the human body, people will require a constant supply of the drug to maintain therapeutic blood serum levels.
[Answer]
The simple answer is that it can't. The only way that something like Melange would work is if it was far more complex than a simple molecule. Maybe symbiotic bacteria or viruses within the plant that are also able to act on mammalian systems once ingested.
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[Question]
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**This question asks for hard science.** All answers to this question should be backed up by equations, empirical evidence, scientific papers, other citations, etc. Answers that do not satisfy this requirement might be removed. See [the tag description](/tags/hard-science/info) for more information.
Before we begin, this system is created by aliens, and all orbits are on the same plane. These orbits are similar to earth's in shape. So, none of this has to occur naturally it just has to be stable for a period of about as long as our solar system will last. (And I know the sun won't live that long.)
First, the sun is the size of ours, and identical in every way. There is a Mars sized planet just within the habitable zone of this star. On the outer edge of the habitable zone is a binary pair of what you can think of as earth clones orbiting each other at a distance of 3 million miles. Directly between the binary planet pair and the Mars-like planet there is a second binary pair of planets, identical to the ones on the edge of the habitable zone.
Would this system be stable? Would the planets in the binary pairs be too far apart? Would the different bodies in the solar system wreak havoc on each other's orbits? Would life as we know if cease to exist?
[Answer]
You can separate this into two problems:
1. Treat the binary planets as a single planet with the combined mass of both and see if the planetary configuration is stable - which is probably only true over the length of time you're talking about if there are no external events to perturb any of the planets in your system. Our own solar system has probably only been stable for a few 100 million years or so - the last major impact on the Earth was 65 mya, but there wasn't one (that we know of) for quite a while before that. There have been impacts on other planets up to modern times. (Shoemaker-Levi on Jupiter for example).
Unless your aliens remove all the asteroids and comets having a stable solar system over the length of time you're expecting would be virtually impossible.
On a more basic level, will the binary pairs affect their neighbours enough to perturb their orbits just by existing? The Sun's habitable zone is estimated to be from just within the orbit of Venus to around the orbit of Ceres ([source](https://en.wikipedia.org/wiki/Circumstellar_habitable_zone)) so it sounds like you have enough space to play with here to have your three sets of planets where you want them.
2. Are the binary pairs stable? Are they too close together to start off with? Given that the Moon is 384,400 km from the Earth and 1/6th of the size, 4.82 million km seems to be a little far apart. You are increasing the distance 12 fold so this will outweigh the 6 fold increase in mass. The planets might not be close enough to stay together over the long term.
The planets will drift apart over time in the same way that the Moon is drifting away from the Earth, so you need them to be close enough together for the "lifetime" of your system. Also they are going to become tidally locked with each other so that they end up presenting one face to each other in the same way that the Moon always presents the same face to the Earth.
Also, exactly circular orbits are likely to be rarer and less stable than slightly elliptical orbits, so I'd drop that requirement.
[Answer]
The question about whether a given six-body celestial system in a given configuration is stable is a research-grade question in the subfield of mathematics called dynamical systems. If I were able to exactly answer your question with support from mathematical proofs, I could probably publish a couple of scientific papers based on my work. Perhaps even a book. But I can tell you what the answer would probably be: No.
The reason for this is that gravitational dynamics are a chaotic system. This means that tiny changes in the initial conditions of the system lead to major changes in the outcome. Any system with more than two bodies is chaotic. Even our own solar system is chaotic; see [this page](https://en.wikipedia.org/wiki/Stability_of_the_Solar_System). In the span of a human lifetime, or even the span of all of humanity, it looks like our solar system is unchanging. The planets maintain their respective orbits, and it seems they will forever. But in reality, this time span is tiny compared to the age of the solar system, and even tinier compared to one trillion years. Even with the most precise measurements and careful calculations, we cannot predict what the solar system will look like even one billion years in the future, .1% of your time span. It is almost impossible to find a stable three body orbit, and even harder with six bodies. Even if your system is stable, the tiniest change (like star passing within a few lightyears of the system) would throw off the stability on the time scale of a trillion years.
EDIT:
Since you have altered the time scale of the problem, I will augment my answer, which is still no. Our own solar system is not stable, and so I doubt that your somewhat more complicated system would be stable. That being said, an orbital system being stable is a very stringent and rigorously defined condition, and is not what most people mean when they say stable. If you mean "the description of the orbits I gave remains valid for several billion years," this is a much less stringent condition which changes the answer to "probably not." Several billion years is still a long time. The Lyapunov time is the the time scale on which a system behaves in a predictable way. The Lyapunov time for our solar system is about 50 million years. This means that we have absolutely no idea what our solar system will look like in 50 million years. And there is no reason to expect that it will look anything like it does now. Your system likely has a similar Lyapunov time, so while it may be have nicely for a few million years, it will probably devolve into chaos long before you hit the billion year mark.
[Answer]
This setup is totally stable in terms of the orbits around the star. The habitable zone itself (which is not super well-defined) extends between roughly 0.9 and somewhere between 1.5-2.5 AU. Planetary spacing is determined by the so-called Hill radius: RH = a (mp/Mstar)^1/3, where a is the orbital radius, mp is the planet mass and Mstar is the star's mass. Planet orbits must be at least ~8-10 RH apart to be stable. That means you can fit about 6-8 stable orbits of Earth-mass planets in the habitable zone. So, for your setup with 3 orbits it's perfectly stable.
As for the binary planet, it is not stable. Binary planets in general are totally stable (see Earth-Moon, PLuto-Charon as examples). But their orbits must be close enough to avoid being torn apart. The criterion for stability is that their orbits must be smaller than about half of the Hill radius (for prograde orbits; it's larger for retrograde). Earth's Hill radius is about 0.01 AU. Your binary Earths are a bit farther out, say at around 2 AU. That means RH is 0.02 AU. However, 3 million miles is about 0.03 AU. You need to chop that separation by a factor of 3 or more to keep it stable -- unless you want to invoke a retrograde orbit for the binary planets, in which case you just need to chop the separation in half.
FYI, I'm an astrophysicist studying orbital dynamics. I have also covered this topic extensively on my blog. Here are a few relevant posts:
* General overview of how to build a planetary system:
<https://planetplanet.net/the-ultimate-solar-system/>
* Orbital spacing of planets in the habitable zone: <https://planetplanet.net/2014/05/21/building-the-ultimate-solar-system-part-3-choosing-the-planets-orbits/>
* Moons/binary Earths:
<https://planetplanet.net/2014/05/22/building-the-ultimate-solar-system-part-4-two-ninja-moves-moons-and-co-orbital-planets/>
* Putting pieces together to fit as many planets as possible into the
habitable zone:
<https://planetplanet.net/2014/05/23/building-the-ultimate-solar-system-part-5-putting-the-pieces-together/>
* A system that is stable with 400 Earths in the habitable zone:
<https://planetplanet.net/2017/05/03/the-ultimate-engineered-solar-system/>
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[Question]
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For this scenario, we must look at the postercard of the term "superearth"--Kepler-10b.
[](https://i.stack.imgur.com/W9rVF.png)
Its mass is almost 3.5 times greater than Earth, and its diameter 1.4 times wider.
Now let's imagine that Kepler-10b takes the place of the fourth planet, that of Mars.
[](https://i.stack.imgur.com/CkStV.jpg)
Mars' mass is 15% that of Earth's, and its diameter is half as wide.
So if Mars were enlarged to the size of Kepler-10b, how would Earth's orbit be affected? Will this super-Mars draw in fragments from the asteroid belt, essentially protecting Earth from asteroidal catastrophe?
[Answer]
Once again: the orbits of all the smaller planets are chaotic in the mathematical sense. We know by observation and computation that our Earth's orbit in the known solar system is stable for the next 100M years or so, after which errors in the observations render prediction as hopeless as forecasting next month's exact weather.
Change anything, and you'll need to re-run the forecast. Also there's an issue around whether that new planet would have prevented the rather unlikely formation of the Earth-Moon system, and whether life could have evolved if Earth did not have its enormous Moon.
[Answer]
No, that would not make a difference to the stability of other bodies in the solar system. The planets have carved their lanes and keep from interfering with each other, and Mars does that already.
A super-earth would not offer protection in the manner of Jupiter. Jupiter is in another league! We don't even hear about the same kind of properties for Saturn.
[Answer]
While the gravitational impact of such a big 4th planet on Earth would indeed be negligible, let's check why that super-Mars was allowed to be that big.
Mars actually should be much bigger than it is - the amount of material found at 1.5 AU should even have been greater than at 1 AU. Of course, at 1.5 AU there was less iron and more silicates, so Mars should be at least rivaling Earth with its size. According to [Grand Tack hypothesis](https://www.wikiwand.com/en/Grand_Tack_Hypothesis) it isn't the case because Jupiter formed much closer than it's today - at about 3.5 AU and migrated inward stopping at about 1.5 AU then receded because of tug from Saturn. Jupiter's formation must have been rather quick - it had to acquire its hydrogen and helium before they were swept away by solar wind. So early in Solar System's history there is a planet that sweeps the most of material from Mars' orbit and compresses much of it at about Earth's orbit.
So, to allow super Mars, we must remove (or at least severely cripple) Jupiter. Then indeed, with all this material in place we could have 4th planet even bigger then Earth but perhaps lighter. However, that means that there is no condensed band of material at 1 AU - it is more evenly dispersed thorough inner system. It isn't to say that Earth wouldn't form - actually the state of Solar System after those ~4.6 billions of years without Jupiter would be very different in unpredictable ways. We don't know how much planetesimals would form if not Jovian sweep through young system, how much would avoid spiraling into the Sun, how would they collide and when they mostly stop colliding (so that life could evolve significantly).
And conversely: would ice giants later sweep through outer disk regions if not Jupiter's influence? In our timeline (as reconstructed in [Nice model](https://www.wikiwand.com/en/Nice_model)) it caused Late Heavy Bombardment - should it happen in our hypothetical scenario, there would be no Jupiter to protect us. But without Jupiter, there could be nothing to prevent Saturn accumulating more and more matter and possibly become a specimen of "hot jupiters".
I'm trying to say that when asking such questions we just can't consider only static, present situation. We should check how could such situation come into existence and - as you can see - once we begin to do that, we quickly enter the realm of wild speculations, too broad for a sensible answer.
TL;DR: after removing/diminishing Jupiter and enlarging Mars, any Earth orbit (or no Earth orbit) and asteroid belt are possible. I doubt though if an asteroid belt could form if there was a massive planet nearby enough to be able to draw asteroids from the belt.
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[Question]
[
From [Wikipedia](https://en.wikipedia.org/wiki/Kriegsmarine#Submarines_.28U-boat.29):
>
> At the outbreak of war, the Kriegsmarine had a relatively small fleet of 57 submarines
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It took the allies until middle of 1943 to gain an upper hand against the German u-boats. The initial stages of the Battle of the Atlantic were spectacular successes for Germany in spite of initially a very small u-boat fleet.
Intuitively it seems likely that had Germany started the war with more submarines the War in the Atlantic might have gone very differently and potentially caused Great Britain to have been successfully blockaded. The slower numbers allowed allied forces more time to change tactics and develop counter warfare tactics that might not have been allowed had Germany had considerably more submarines initially.
What would have been the impact on World War Two had Germany focused more of their naval production on u-boats prior to WWII?
[Answer]
Outside of the things already mentioned, the Germans would have had a difficult time coordinating the extra wolf packs. In addition to the ever present fear that they could be located by radio detection or code breaking (which turned out to be true after all....), the logistical strain on supporting the U boat fleet would have detracted from many other German projects, especially given the rather chaotic nature of the wartime German economy (Germany didn't really get on a wartime footing until 1943, and was still rationalizing production of many elements as late as the end of the war).
U boats are sophisticated devices, so lots of skilled workers would be needed to continue building the extra U boats, as well as steel and other resources. The U boat pens required an enormous amount of manpower and materials to build, and then there was the issue of resupplying u boats at sea, something the Germans had a great deal of difficulty with (surface tenders were easily intercepted, and "milch cows" (transport U boats carrying fuel and supplies) turned out to be very vulnerable.
I suspect the real answer is that 57 U boats was about the maximum that could be supported by the German war machine, and attempting to build many more would have had very severe knock off effects on other parts of the German military, delaying many of the German plans during WWII.
[Answer]
In all likelihood more submarines would have made America enter the war sooner, or forced the Allies to adopt strategies to deal with them sooner. The best case scenario for the central powers would have been that they had enough U-boats to randomly intercept the Dunkirk evacuation. Perhaps enough submarines would also been able to protect an amphibious assault onto English soil. But probably not.
[Answer]
In all likelihood, had the German submarine fleet been significantly larger and the allies suffered more significant losses, it would have spurred faster development and production of Liberty ships and counter-submarine tactics.
Even if the fleet had doubled in size, the tactics it was using would still have proven insufficient to fully blockade Britain. The allies would have used more Q-ships and armed the Liberty / Victory ships with more anti-submarine weaponry. Losses would have been higher, but they still would have been acceptable (as there was simply no other option).
The largest impact would probably have been the reallocation of B-17 and B-24 bombers for maritime anti-submarine patrols. There would probably also be reallocation and elevated production of destroyers and other anti-submarine ships. This may have diminished the ability for the Allies to strike at mainland Europe and lengthened the war by a few months, but overall the German submarine fleet would have needed to be many times larger to truly turn the tide of war.
[Answer]
Option one:
More U-boats come out of the Army/Luftwaffe budgets. With fewer tanks and Stukas, the campaign into France doesn't go so spectacularly well, and the U-boats are mostly used in the North Sea, or short patrols to the Western Approaches rather than in the wilds of the North Atlantic.
Overall U-boat campaign - less effective, lacking bases in France.
Option two:
More U-boats come out of the Navy budget, impacting production of other ships. Depending on when and how this happens, it could have several different effects, from huge to tiny.
For example, it might mean the failure of the invasion of Norway; it might mean that the Royal Navy can deploy more capital ships to the Far East deterring Japan from attacking; it might merely mean that the Arctic convoys do better.
Option three: More U-boats come from some other source. This is the tricky one - where? Where are the materials and finely machined parts coming from? Where's the slack in the budget, and whose toes has the Kriegsmarine stepped on in order to get it?
The Nazi government was a fiercely dog-eat-dog world, almost as much as it's view of foreign policy...
It's also worth noting that while the Battle of the Atlantic was only conclusively decided in 1943, the situation was largely under control (from an Allied perspective) in 1941 until the USA joined the war, at which point we got Op Drumbeat and the "Second Happy Time" in US waters...
[Answer]
Apart from expanding the number of submarines available to Karl Donitz and the Kriegsmarine at the start of the war, an increased focus on submarines would likely have resulted in prioritised funding for research as well.
As with speculation along the lines of "what if the Luftwaffe got operational ME-262 jets a year earlier than they did?", it's possible to speculate that an earlier release of technologies such as the Type XXI might have affected the outcome of the war dramatically.
If the Kriegsmarine had more widely implemented the Schnorkel device (allowing submarines to run on diesel engines while submerged) earlier than it did, there might also have been knock on effects.
Same with torpedo technology and countermeasures technology.
Another line of speculation might be "What if the allies took longer to break the enigma code? Or if the axis realised that the code had been broken?"
[Answer]
Had they had more submarines they'd of necessity have had fewer aircraft, tanks, and other ships. Germany was severely resource limited both in raw materials, fuel, and manpower after all.
So had they employed more submarines their land and air forces would have been less capable, maybe far less capable. While this may not have hurt them much against the western allies in the early stages, the campaign against the USSR would have gone bad even sooner, as would the campaigns in northern Africa and maybe even France.
Where they could have gained some benefits maybe is favouring submarine production over the production of surface warships in the pre-war years more than they did.
Then again, this would have allowed the western allies to focus their efforts on ASW assets rather then weapons to fight against the likes of Bismarck and Gneisenau earlier on, fitting out more ASW escort carriers and destroyers instead, which would probably have more than negated any benefits the Germans could have gained rather quickly.
Of course it's all speculation...
A far more effective solution for the Germans to keep the upper hand would have of course been to focus early on on replacing the Enigma machine with a better encryption/decryption system for their military communications. The Enigma was never initially intended for military use and had some rather serious flaws which the English discovered relatively early in the war and which led to after about 1943 every message sent to the submarines to be read before the submarines could act on it, allowing the ASW groups to lie in wait for them, which is what ended the "submarine happy hour".
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[Question]
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Long ago, well before the invention of electrical power or electronics--thinking a Middle Ages or Renaissance time period—there was a brief period when the scholars and natural philosophers of the day became infatuated with the idea of boolean logic.
They developed formalized notions of True and False, 1 and 0 and base 2 number representations, AND, OR, XOR, and NOT, essentially the fundamental principles of digital computers. A lot of study went into it, but they eventually concluded that the concept had no practical value, and the ideas fell into obscurity within a generation or two.
A few centuries later, some researcher is working on electronic circuitry and happens to come across a long-forgotten book that tells him 80% of everything he needs to know about the principles of digital logic. Looking into the subject further, he's astounded to find that the scholars of yesteryear had all this theory and then simply threw it away as having no value, because they didn't realize that...
...what? Why would something that today we know to be immensely valuable be dismissed as a mere intellectual curiosity and then forgotten? Would simply not having the technology to build something useful from it be enough?
[Answer]
Historically speaking ideas were abandoned due to political or religious influence. Ethical reasons are possible as well.
China [abandoned international trade](https://en.wikipedia.org/wiki/Zheng_He) in 1433 as a consequence of political infighting at court.
The catholic church vigorously suppressed the idea of [heliocentrism](https://en.wikipedia.org/wiki/Galileo_affair) as being contradictory to church doctrine.
[Gene therapy](http://ghr.nlm.nih.gov/handbook/therapy/ethics) is controversial because of ethical and other reasons, and it is hard to predict how it eventually will play out.
References:
<https://en.wikipedia.org/wiki/Zheng_He>
<https://en.wikipedia.org/wiki/Galileo_affair>
<http://ghr.nlm.nih.gov/handbook/therapy/ethics>
[Answer]
Binary logic can be seen to lead to [dualism](https://en.wikipedia.org/wiki/Dualism "Dualism"). Or being a result of dualism.
True/False, Good/Evil, Us/Them, Body/Soul, Man/Woman etc.
All these distinctions aren't really as sharp as some people want to make them.
If somebody use this kind of logic to argue for something bad, the backlash can make the whole dualism/binary logic thing seem bad.
[Answer]
Your question has the answer within it.
>
> A lot of study went into it, but they eventually concluded that **the concept had no practical value**
>
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That pretty much sums it up.
In modern circuitry, all the magic lies in the [diode](https://en.wikipedia.org/wiki/Diode). This is where all the magic happens and where you can practice all boolean logic. Transistor is the most common form. Before the semiconductor diode which revolutionized electronics, they used vacuum tubes which were heavy, large and messy. It was only after the advent of diode in 1950s that the whole potential of boolean algebra came into practical realm.
Without diode, boolean algebra is only theory with no application.
[Answer]
Let's look at the uses of binary logic:
Electrical work - it seems like [William Gilbert](https://www.wikipedia.org/wiki/William_Gilbert_(astronomer)) was one of the founders of this, back in the 16th century, but it wasn't really used for anything until around the 19th century.
Computers - Let's attribute this one to [Chucky Babbage](https://www.wikipedia.org/wiki/Charles_Babbage) in the 19th century.
Mathematics - specifically set theory, invented by [Georg Cantor](https://www.wikipedia.org/wiki/Georg_Cantor) also in the 19th century.
Boolean logic wasn't even really a thing until [George Boole](https://www.wikipedia.org/wiki/George_Boole) came up with it, again in the 19th century, and even then it wasn't really very useful to anyone.
Thus, if you have someone in the seventeenth century or earlier playing around with Boolean logic, they won't have anything to do with it for another two hundred years (except playing with logic puzzles).
Plus, there's no obvious backwards connection from boolean logic to these other fields. If you can't even create a light bulb, you're not going to make the jump from binary to circuitry. Even if you do think up an analytical engine, just like Babbage you won't actually have the ability to build it.
So, in summary, just say that it was invented before anyone had thought up a use for it. Then it can be forgotten just like all that other stuff that we don't remember (which could include quite a lot more things than you think it does). As to why it used to be so popular, people used to think the harpsichord and Jane Austen novels were pretty cool too. Tastes change, the things that are considered fun and interesting change too. With no application, boolean logic would be considered just a source of amusement, so all it takes is for something more amusing to come along.
[Answer]
What you are talking about is the basis for logic. Which is a part of philosophy. So if people didn't find the philosophical pursuit of logic to be fulfilling then it might get lost.
True, false, And, Or and Not are not just useful for programs, it is useful in clear logical thinking. Any college logic class uses them all as the basis of valid arguments.
So I would say an entire society that gave up on logic for some other form of decision making, like reading entrails or games of chance (where they don't bother caring about the odds).
[Answer]
If you're working from a theoretical standpoint, there's really no reason to prefer a two-valued logic (true/false) over a [three-valued logic](https://en.wikipedia.org/wiki/Three-valued_logic) (true/false/undecided) or a [four-valued logic](https://en.wikipedia.org/wiki/Four-valued_logic) (true/false/undecided/contradictory). On the contrary, the higher-valued logics let you express a wider range of situations.
Binary logic really only shines if you're trying to make a mechanical implementation of it, where three-valued logic is tricky, and four-valued is almost impossible.
[Answer]
Perhaps they liked questions and problems that are more condusive to Fuzzy logic : <https://en.wikipedia.org/wiki/Fuzzy_logic>
*Was it a 'good' movie?*
*no, because it had a plot hole and therefore is not good.*
*I reject your premise that the existence of one plot hole makes the entire movie 'not good'. I reject the entire assertion that a movie is either 'good' or 'not good'. surely that plot hole merely makes the movie 'less good'.*
] |
[Question]
[
In 1950 physicist Enrico Fermi wondered [why we have found no alien civilizations](https://en.wikipedia.org/wiki/Fermi_paradox) even though there are about 10,000,000,000,000,000,000,000 stars in the observable universe.
Among other things, he worked on nuclear power.
Nuclear weapons helped nations prevent wars. And, luckily, your socially challenged neighbour that every now and then threatens to kill someone with his automatic rifle, couldn't enrich uranium even if he wanted to. Everyone could sleep safe, knowing that they won't wake up to a [bright flash of light](http://soldiersforthecause.org/wp-content/uploads/2013/07/zero.jpg) that will kill 10,000,000 people instantly.
---
**Year 2060.**
[3D printers](https://youtu.be/fcgPRTBPm9o?t=1m34s) have evolved to the point they cost as much as normal printers did in 2015. They can "print" extremely complex objects in very small amount of time, be it food, or a complex machine.
Drones sized a few micrometers are used routinely to cure previously incurable diseases.
Life expectancy has skyrocketed to 150 years.
What a great time to be alive!
Or is it? Your neighbour no longer has a rifle. He has a 3D printer which he used on creating uranium enrichment devices. He also printed a fully functional nuclear weapon. The final piece of the puzzle is that fist sized ball of U-235. He has been working for half a year on his project. Soon the whole world will know him and fear him! They will finally respect him!
As he sits in his room waiting impatiently, he feels an insect on the back of his neck. 5 seconds later, he drops on the floor. His heart stops as the toxin injected by the fruit-fly-sized drones reached his neurons.
Police neutralized the suspect.
---
The problem is that you have 10 billion "neighbours". If 1 in 10,000 wants to destroy society, that's 1 million crazy neighbours.
* How hard would it be to protect our civilization from total
annihilation?
* Which measures would governments have to take in order to achieve
that? Would personal data cease to exist as we know it? Would everyone be under surveillance?
* Is it even possible to prevent self-destruction indefinitely?
[Answer]
One super-geek's home made nuke, even if successful isn't going to destroy humanity. All out state driven nuclear war will.
Of course, the damage would be horrendous, but not in itself civilization ending. Though it may sound callous, the loss of a city or two is not a direct threat to civilization, although it may be a threat to general liberty (to which your OP cogently refers).
The supply of suitable fissile material is the main issue, not the blueprints or the centrifuge.
There is a limit to how significant, in the grand scale of Mutual Assured Destruction that such efforts can aspire. Is it significantly more *statistically significant* than a meteor strike or super-volcano eruption or climate disaster which wipes us ***all*** out? If not then why worry?
As a politician once said, 'Events Dear Boy, events'. Certainly, if total loss of liberty can be taken to constitute an ending of civilization its a very real possibility. But then again from an alien xenobiologists perspective, a transformation of human society from an individualistic basis to a hive mind type situation would not register as a collapse.
**How hard would it be to protect our civilization from total annihilation?**
Impossible. Only statistical improvements in chances can be made (see point re: meteors). The major improvement is to diversify beyond being on one planet. But, soon after that, one needs to diversify beyond one solar system.
**Which measures would governments have to take in order to achieve that?**
Global integration continues apace. Each advance in communications technology and computing (including recent advances in machine learning) advances the final consolidation of human society. Pattern recognition and machine learning are already widely deployed by NSA/GCHQ etc, as well as by the tech giants.
Abolition of physical cash in favour of electronic cash (both to enable introduction of negative interest rates and also to track the black market economy) is no longer a taboo subject. Just today official members of the Federal Reserve and the Bank of England have mentioned this idea. An electronic cash society will, long story short, drive us to an open, reputation based society.
But even a final consolidation of the diverse fragments of human society only serves to protect from internal threats - not external.
**Would personal data cease to exist as we know it? Would everyone be under surveillance?**
The main coming impact to societal surveillance is electronic cash, as I have noted above. Its probably inevitable and will cement social changes already underway.
It will still be possible to conceal social data but the act of concealing it will reduce its value to its owner. It will become an economic trade-off whether to sacrifice privacy for other social gain.
**Is it even possible to prevent self-destruction indefinitely?**
Only by changing the definition of self such that there are multiple "selves". And even then, only if the various selves are not dependant in some unforseen way.
[Answer]
Being crazy isn't enough. One has to have the desire to kill everyone, plus the ability to think rationally enough to devise and carry out an effective plan, all without anyone suspecting that you might be doing something untoward.
This is not a small feat, even if you can print complex components at home.
Most crime is not prevented by there being superhuman detection and prevention of crime - it is because criminals and madmen tend to be stupid or otherwise irrational.
I certainly wouldn't worry about anyone trying to build a nuke - the radiation from trying to gather than much highly radioactive material would be very easy to find. Even today, if you live in a major city in the US, that much radioactive material would be found rather quickly (whether or not that is a rational use of resources, or just a paranoid government never questioning the costs, is an exercise left for the reader).
What I would worry about is a custom designed virus.
Not much you can do about that other than lots of isolation, putting people into quarantine, making sure people had plenty of protective gear, etc.
You could probably kill a local community before people become aware and really ramp up the response to it, and a few clusters here and there would pop up from travel, but the technology to create such a well developed plague implies well developed medical care and responses to epidemics. In the grand scheme of things, the lone madman is not a threat to the population at large - that is the purview of politicians.
[Answer]
>
> How hard would it be to protect our civilization from total annihilation?
>
>
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It's impossible, if all forms of destruction are considered. Uranium isn't exactly a common substance. World governments already do a good job monitoring radiation levels and, more specifically, the transfer of radioactive materials. There are a bunch of movies in which one group or another acquires nuclear material, but I can't think of one where the material doesn't come from a nuclear-capable nation.
But, beyond nuclear weapons, there's also biological, chemical, and astrological weapons. pluckedkiwi discusses biological weapons, and chemical weapons can be used in the same manner. Adding a disruptive chemical to the water supply could devastate a city.
The greatest weapon, however, may not be a weapon. As of this moment, there's nothing humans can do to protect themselves against a meteor impact of epic proportions, such as the Chicxulub impact.
So, no, it's not possible to protect against total annihilation (at least for the foreseeable future), but it may be possible to protect against human-driven annihilation.
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As I mentioned above, world governments (and probably local governments) already employ tactics to monitor, control, and/or prevent disasters. Critical points receive extra attention, cameras are trained on access points, and cyber specialists monitor websites, among other strategies that aren't publicly known.
Believe it or not, personal data almost doesn't exist in our modern world, but not because of government. Corporations like Google, Facebook, Wal-Mart, Target, and even Domino's know your information: where you live, what your spending habits are, what kind of toppings you like on your pizza, etc. Then there's all the information your bank/credit union has on your habits in order to detect fraud.
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Yes. Upload everyone's consciousness into a virtual reality and let machines monitor the system. Alternatively, initiate a global eradication of the human species. After all, human society can't implode if there is no society.
In all seriousness, the answer is still yes, with a caveat. We evolved to out-compete other organisms. We've done so to such an extreme that our only real threat anymore is each other. Everything else being equal, humans are social creatures that benefit most from a stable society. As a result, human civilization will endure, but it may not stay the same as it is now.
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Very easy: 3d printers ain't magic. You still have to mine your uranium/thorium and that's where the governments will exert control.
Nuclear machinery also demands very high quality alloys. You can't print alloys, they have to be smelted. And you won't be able to buy the needed alloys.
Fluorine is also a problem. Fluorine is hell and you need a lot of it to enrich uranium. Your basement dweller will get himself killed messing with fluorine in the basement. That's assuming that the citzen can buy fluorine by the truckload.
The eletricity bill. Nuclear enrichment devours energy. How will the basement dweller pay for this?
And, at last, the physical space. Have you seen photos of the Manhattan Project buildings, of the soviet Mayak plant? These places are huge. Where will your citzen place all the equipment that have been printed? How will he pay for the concrete to do the construction? 3d printers ain't magic, you must provide the concrete for it to print buildings.
The real issue will be smaller countries getting nukes. But that isn't really an issue since you alredy accepted that nukes are instruments of peace. A nuclear Nicaragua or Haiti is a threat only to the imperialists that, if they corner the local leaders, may get a nuke in the face, protecting the small countries from the fate that befell Iraq or Libya.
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3D printing can't produce elements, let alone isotopes of elements. Your kook will find it easier to produce that nuke than he would today as he can download all the plans for a uranium extraction plant and an enrichment plant (assuming there is a sufficient underground to provide such things)--at the average crustal density of uranium you can obtain enough from a few acres if you can extract every atom of it.
Doing either without coming to the notice of vigilant authorities is quite another matter.
Likewise, 3D printing isn't going to be of much use to the guy making a chemical weapon. You can print your factory but you still need all your raw materials and that will draw notice.
Finally, 3D printing is of even less use to the guy trying a biological approach. The real threat here is not 3D printing but DNA synthesis. It's already reached the point that a professional can produce in the lab a virus based on downloaded data--how long before that technology reaches the hobbyist level?
The hard part will be developing a new pathogen (so existing vaccines do not work) and testing it without being caught. This is beyond what one individual could accomplish in today's world but not in 2060. However, while it wouldn't be too hard to get test subjects in today's world (abductions from areas of genocide won't draw notice) the disappearances will probably be noted in 2060.
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**How would paleolithic combat work in a world where you have instant, and permanent mastery when you hold any tool?**
Weapons are limited to stones, slings, clubs, and stone-point spears, but any tool or implement is available for mastery.
The "Instant Mastery" operates when a user thinks of performing an action, like "I want to throw this stone to over there.". If it's possible, they immediately know how to throw it, and if it's impossible, they also know that too.
However, it's total mastery for every use. If they want to use a spear as a hammer. They'll get precognition on that too, for example.
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# Community wins
The first group to successfully build a community wins.
Why? Let's explain step-by-step:
* this mastery, as you explained, is also valid with non-offensive use of tools
* this means that anyone could use tools to build better tools and items and stuff, i.e. anyone would become a very proficient artisan.
* progress! The more talented people, i.e. those that posses creativity and intelligence, would suddenly be able to express them, and improve the tech level
* better tech level --> better weapons --> (you already have mastery) --> you win
So the key is not to die long enough to advance the technology a bit, and to do that, you have to build a community of people who protect and feed those who are instead busy creating.
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**The warrior-troubadour would rule the world**
This mastery approach you describe has three limits. The first is the obvious strength and stamina tests that KillingTime mentioned in a comment. The second is their own imagination for the creation of an imagined action to do. An individual that cant think beyond, "Ogg stole my stick. Make Ogg's head have 2 more lumps than it used to." will rapidly find their creativity is too low to permit striking the more creative individuals, who have taken the time to shape more efficient ways of defending themselves. This leads to the third limit, the imagination of others. Creative use of a spear can accomplish a great many things if one is nimble and quick, but once someone has decided to engage in a defensive action, your options to strike with become limited.
Accordingly, those at the top of the "food chain" would be the warrior-troubadours, the warrior-poets, and their kin. They would have the imagination to figure out how to use that perfect mastery to accomplish ever more nuanced goals, as they refine their arts. In our earlier example, if Ogg has already begun working with the stick to protect himself, he'll probably find a way to take 2 lumps... but small ones. And, in exchange, he might disarm his opponent, and maybe even woo his opponent's wife away with the beauty of his actions. Lose your wife to a warrior-troubadour once or twice, and you'll learn not to try to put lumps on their head very quickly.
Creativity could literally rule the world.
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## Let's start with defining what Mastery is NOT
**Mastery does not Guarantee Perfection:**
A master stone napper can usually craft an arrow head to within 1-3 millimeters of an intended shape, but lacks the sensory and motor control faculties to shape it with machine level precision. A master still makes mistakes, but very much more rarely. Also, a master is still limited by his materials; so, if you want to make a bow, a master can make a one to the exact dimensions he intends, but can not necessarily know if the wood will split or hinge due to an unforeseen defect in the wood. A master is still limited by scarcity; so, he may do something sub-par simply because of time or cost constraints, but has a better idea than a novice about what he is trading off.
**Mastery does not Guarantee Organization:**
Being an expert at using the weapon in your hand does not make you a tactical genius. A well organized phalanx with very little combat experience can easily wreck a disorganized mob of masterful warriors. This also applies too tools. Just because you can make every detail that goes into building the Colosseum does not mean you have the ability to do it yourself or the ability to coordinate with enough other people to do it.
**Mastery does not Guarantee Technological Advancement:**
While others have speculated that instant mastery would make technology advance faster, I suspect it would actually have the opposite effect. Necessity is the mother of invention; so, the more you can do without inventing new things, the less reason you have to innovate. Let's take the wood lathe as an example. Somewhere in history, someone decided that it was too hard to carve a stick into a uniform pole; so, they invented a machine to help them do it, but if you came out of your mother's womb able to carve a perfect pole, then you would never have nearly as much of a need to invent something to do that for you.
## So how would this all effect Paleolithic warfare?
The general factors that determine the effectiveness of an army are their tactics, training, technology, & moral.
Since your warriors have no special mastery of tactics, it means that good leadership will just as important as ever. With no major differences in the skill of warriors, being able to put them in the most opportune positions on the battlefield will be very important when it comes to gaining an upperhand.
To this end training will remain just as much of an X-factor in your world as it is in ours. You may not need spend time to learning how to use your weapons, but you do need to learn to move in formations, follow orders, and you need to condition your body to be strong and endurant enough to wear your opponent down until he can overwhelmed despite his skill level being about the same as yours.
As I mentioned before, technology will not progress any faster, but it may progress differently. Since a masterful warrior can more easily target the gaps in your armor, armor may be less favored. Instead warriors may prefer to just use a shield and weapon which will allow them to match skill to skill without weighing themselves down needlessly. In the stone age, armor was not that common anyway, but this is something to consider. Bows will likely become far more pivotal to warfare since an expert archer is such a dangerous adversary. Since your warriors are so accurate, longer ranged bows will be extra important; so, this is one area where technology will certainly not stagnate. I would expect your warriors to focus especially on range and arrow speed; so, they would probably adopt some kind of compound recurve bow similar to a Mongolian or Hunnic warbow, environment permitting, or a Yew or Osage longbow if the climate is no good for composites.
Moral is also actually going to be an important factor in your warfare because you stated that "If it's possible, they immediately know ... , and if it's impossible, they also know that too." The more an individual soldier understands his odds of success, the more his moral will be impacted by the knowledge. Normally when a battle take place it is because you have two armies of people who engage one another believing they will win and that they will live. But, if you have two armies where each side can make very accurate predictions about their own strengths and vulnerabilities, it could mean that most soldiers will make their own predictions about if a battle is won or lost before it begins. This means that armies could be very easily routed, either fleeing before a battle begins, or very shortly into the fray once the enemy's capabilities become apparent.
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Those who manage to obtain a *staff* would rule the world. This instant-mastery has just *got* to be magical, so if magic exists, logic follows that staffs and wands would *also* exist. And since any 'tool or implement' is available for mastery, the instant someone gets a staff, they'll know how to use it.
In order to balance this, staffs or wands (wands are really just a small staff, right?) would be made of exotic and/or hard to find elements like 'driftwood from the Arctic Sea' or 'the oldest branch of the oldest tree on the *entire Earth.*" However, that still leaves the fact that anyone who manages to create, steal, or otherwise obtain a staff would be limited only by their imagination, not to mention whatever limits you decide mages have in this world.
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**Situation:**
Aliens attacked earth. They used a weapon which produces waves, say "destorymachinewaves". It destroys the machines and takes them to space. So every machine on the earth was Destroyed. Destroyed machines were flew to space from earth. All the technology was gone, From super computer to your wrist watch. Not even a electrical bulb exist on earth. We are only left with technology on the paper.
**TODO:** How many years it is going to take to retain the same technology and all machinery to the world? In the process of retaining the technology do we invent any new technology or machines. For instance, microtechnology or a suit which fly by itself if you wear it.
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Possibly never.
It's questionable whether we'd be able to regain it at all.
If every machine on earth was powedered and spirited away into space not only would we lose the technology, we'd lose the materials. We've already used most of the most easily accessible ore deposits and the most easily accessible fuel deposits and you can't get to the deep stuff without equipment and you can't make the equipment without ore/metal/material.
Every single bit of knowledge stored only on computer would be gone.
Society would collapse into a terrible famine as all the farming infrastructure would be totally gone. For a long time people would just be trying to survive. It's hard to maintain libraries when the librarians are starving to death.
Knowledge of how to build tractors isn't a great survival skill in a world where there's almost no metal to build them with nor fuel to run them and there's going to be a lot of cannibalism.
It's hard to even have an iron age when the easiest surface iron deposits are already gone and without that there's little hope of climbing higher since you need to be able to free up enough people to have a scholar class and that may never happen. Without that society can remain totally static without notable scientific discovery.
There's even a danger that even if society did start to climb again, that people would develop a worldview where useful knowledge can only come from some golden age in the past which could further cripple any attempt to reestablish a scientific community.
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As Murphy pointed out. First we would have chaos. Billions would die from starvation. We can't sustainably feed our numbers without equipment to produce (much less transport) food we need. Refrigerators/freezers are gone and all that food will spoil. So people will starve to death in every advanced nation on Earth. Rural places will fair a little better. Indigenous peoples will have minimal issues.
So first we'd fall, rapidly. We won't have the ability to communicate over any distance that doesn't involve someone walking or riding a horse. All 'governments' would be reduced to local city officials. With luck there might be a few beacons of light scattered throughout the globe.
Quite likely the survivors will actually have myths about technology and might even try to avoid it since 'dependency' on it caused such misery. So I would go with at least 1,000 years to have a chance of reaching something similar to our current state. If the libraries are actually preserved and not used as fuel or are burned in protest or rage then we have a chance of turning around our dark age in a few hundred years (but still need a lot more to reach the industrial revolution).
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I do not believe it will as grim as others put it. After all, this is like starting over a game, but with all the cheat codes memorized.
We still have all of our structures which don't require constant machines to function (at least residential ones) and basic materials could be reused from structures (such as construction steel and copper used for communications) and basic survival level agriculture only requires manual tools (sure this can't be ultra industrial but if everyone had their own, or worked together on plots), it could sustain humanity until we collectively can try again.
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There is some basic agriculture level that requires only domesticated animals, crops and very basic tools that were made by the farmer from wood. I think civilization is unlikely to degrade below that level. It may be actually higher as smiths can forge plows and scythes from rusting machines.
Farmers may not be able to produce enough food for sale but probably will manage to grow enough food for own families. They are in danger of angry crowds running from the dying cities, but without transportation these crowds may die out before destroying every remote farm.
In general monkey business for the Aliens, the humanity will completely recover in a few thousand years that is a very short time in a cosmic scale.
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In a pre-industrial world where magic is thriving, it is possible for a mage to alter the size of a creature (including other humans).
Thus a duck could be made horse-sized. It would have all the normal features of the original duck but its mean density would remain the same. Thus it would be very unlikely to be able to fly. Similarly a horse could be made duck-sized. It too might have problems, for instance being chased by a cat.
There are *magical* limits to the transformations. Creatures can be no smaller than 1/100 of their natural size and no bigger than 100 times their natural size.
However I am interested in the *physical* limitations. Most wizards have a purpose for the transformation, they don't usually wish to kill the animal by making it unfeasibly large or small.
**Questions**
Animals are physically suited to their natural sizes - their musculature and skeleton etc. are 'just right'
What level of transformation is likely to produce viable creatures? I am primarily interested in survival. The animal needs to be able to survive long-term in its altered state in terms of avoiding danger and acquiring water and food etc. How will the change affect a creature's mobility?
What other implications may limit what mages can sensibly do in this respect?
**Notes**
1. The tag 'science-based' relates purely to the physical effects of changing size whilst maintaining the same overall density and keeping the same shape. The magic has its own rationale which can be considered as separate and is not relevant to the question.
2. When a brain is changed in size, the intelligence and psychology of the original creature remain unchanged. A duck still thinks it's a duck and presumably experiences the world as smaller and gravity as stronger.
3. Successive transformations, e.g. smaller and smaller are not possible. You must restore a creature back to its original size before transforming it again.
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> The title was inspired by the **[Horse-Sized Duck](http://knowyourmeme.com/memes/horse-sized-duck)** meme.
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A horse-sized duck would almost certainly just collapse,. Being big has a biological cost -- otherwise, all animals would be the size of the [Burj Khalifa](https://en.wikipedia.org/wiki/Burj_Khalifa). You need to have special infrastructure to deal with all that bulk, and just increasing the size of your existing infrastructure isn't enough.
Birds are already stretching the limits of their infrastructure, since they need to be as light as possible to fly.
The effects of reducing the size of a horse would depend on the process involved, but you can have a discussion of some sort, at least. It would probably be able to survive for a while, since it can still graze, though it would be too slow to outrun any of its predators, and it will probably gain new ones.
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One of the ancestors of the horse (Eohippus) was about twice the size of a Fox Terrier, around 30 pounds.
<https://en.wikipedia.org/wiki/Eohippus#Common_misconception_on_size>
While a really big duck (Muscovy) weighs only about 15 pounds. A horse the size of a duck would literally be a sitting duck, but ignoring that, horses are relatively inefficient eaters and need the bulk to get enough nutrition.
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No matter whether you scale a creature up or down, the [square-cube law](https://en.wikipedia.org/wiki/Square-cube_law#Biomechanics) will be your nemesis. It's hard to work around it without changing the creature's biology in extreme ways.
The most physically-sensible way that this kind of magic could work would be changing the creature's genetics somehow--basically taking apart and reassembling the creature at the cellular level, turning it into a differently-sized subspecies. To make it look identical while being larger or smaller would require some nonsense about "changing the spacing between atoms," which would kill the creature in a dozen different ways. Explosive ways.
Within a reasonable size range, resizing by spontaneous genetic alteration could work. Some adaptations would be needed: a shrunken horse would become stocky like a pony, while an enlarged duck would be flightless and ostrichlike. If you assume these kinds of alterations, I'd say the horse-sized duck would have an easier time surviving--even though it wouldn't quite be a duck anymore.
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So, setting is an extremely advanced race who use bioengineered tech in many applications, although most commonly in warfare. Their combat troops are large exoskeletal creatures ranging from hand sized spiders to horse sized scorpions. My idea was to have the exoskeleton composed of keratin, spider silk, and bone. It does not have to be in discreet layers as the tech is advanced enough to give the armour a complexed 3D structure. Most opponents are less advanced, in the case in question they stand at around human levels of tech. The armour is also grown into wearable plates as personal armour.
Question is this: how effective would the armour be? What would be its weak points, and strengths. What weapons would be most effective?
Note: I understand that any race this advanced will have better armour. However, the bioengineered 'soldiers' can be grown quickly from the resources on the planet they are invading. This is important as the story is meant to be 'hard sf' so interstellar travel is to difficult to carry a ready-built invasion force.
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Spider silk is amazingly strong (something like 17 times more tensile strength than steel per unit weight), so the idea of making body armour out of silk isn't strange at all. The only difficulty is to scale up production to meet the requirements of a large scale force, and in our world genetic engineering is being used to do unlikely things like coding for spider silk proteins to be expressed in goats milk!
Keratin is the protein used for skin, nails and hair. Very strong materials can be made from this, but it isn't nearly as tough as some of the shells of various molluscs, which turn out to be a composite of ceramic like calcium compounds in a matrix of a more flexible protein, which provides strength without being brittle.
"Wet" bone in living creatures shares some of the same properties; bone under a microscope looks a bit like a sponge with calcium particles suspended in the matrix (yes there is a lot more to bone than that), but since the scale of the particles and the matrix is much larger than in shells, bone is actually not as strong or "tough". The need for bone to be "wet" (i.e. living tissue) in order to remain strong will also be an issue if you want to use it for armour.
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Bone, silk and keratin are strong materials in their own right but I wouldn't use them for high value foot soldiers. As you said, there are better materials, use them for the elites.
Use these cheaper materials to make cannon fodder shock troops. For any kind of invasion, you need lots of them. Make [zerglings](http://wiki.teamliquid.net/starcraft2/Zergling) or [hormagaunts](http://warhammer40k.wikia.com/wiki/Hormagaunt) in the millions.
Ranged weapons take extra resources so just give the shock troops melee weapons. If enough of them survive to melee range, whatever weaponry the enemy has won't do them any good.
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You should consider that while spider silk, keratin, and bone are each strong in different ways they did not evolve to function as armor. While this means that they may not be ideal as armor, it opens up the possibility that other organic materials that *were* designed to function as armor could be orders of magnitude more effective. If your aliens are sufficiently advanced I see no reason why they would be limited to using existing biological materials to make armor for their soldiers. They could engineer something far, far stronger. Imagine an armored skin composed of a single molecule of layered and interwoven spider silk filaments, or even carbon nanotubes. Engineered organic armor could be vastly stronger than any known material. Potentially any organic molecule you can think of could be synthesized by engineered enzymatic processes.
As to your question of what sort of weapons might be effective, it depends on the exact nature of the armor. If it is brittle and hard then kinetic weapons like bullets may be able to crack it if they can deliver enough force to a small enough point, but the armor will be resistant to shockwaves as it won't propagate the force to the interior. If the armor is elastic and flexible bullets will have difficulty penetrating, but the shockwave of hits and particularly explosions could still be transferred through the armor to cause internal damage. If the armor is well-made and layered to be both hard and elastic, well, you are just going to have to shoot them a lot. Or try fire! Organic things tend to burn and sufficient heat could break the molecular bonds holding the armor together. Also maybe very strong armor is not very good at allowing a creature to cool off. Cook them in their own super-armor oven.
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Well according to [this article](http://theweek.com/articles/482397/military-breakthrough-bulletproof-skin-made-from-spider-silk) they have made material from spider silk that can make bulletproof vests. Regular silk has been known to stop projectiles and be used as body armor. The mongols used it to protect against arrows. They've even recently proven that if Archduke Ferdinand had been wearing his [vest](http://www.theguardian.com/artanddesign/2014/jul/29/bulletproof-silk-vest-prevent-first-world-war-royal-armouries), his assassination would have been stopped (gun shot!) and something else would have sparked WWI.
Now taking this bit of news and adding in keratin and bones to add some rigidity and strength to the armor, maybe even some sharp edges it seems like it could be very reasonable body armor. The big thing is cost of production vs. overall protection. If this can be 'grown' cheaply, then you have a pretty good idea here.
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Humans require a pretty particular ratio of CO2 in their atmosphere.
Plants use oxygen to live, and only become net producers of oxygen when they're photosynthesizing.
If the sunlight were cut off to, say Earth for example, would humans, animals (and plants, I don't have good numbers for their sensitivity to CO2 - but they are sensitive to some degree) choke on the raising CO2 levels before freezing to death?
How long would it take to raise the CO2 levels to various thresholds? Obviously once you start killing off life you'll end up with less CO2 pollution, so at some point you'll level off the CO2 ratio.
Any idea of what a choked planet's atmosphere would look like?
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No, we'd freeze to death faster.
<http://www.popsci.com/science/article/2013-07/if-sun-went-out-how-long-could-life-earth-survive>
Within a week, temperatures would drop to 0 degree F, or -17 C. Within a year we'll be at -100 F or -73 C. Quick reminder: Carbon dioxide freezes at -55 C.
Now, in a year, CO2 emission from all sources is about 800 gigatonnes per year.
<https://www.skepticalscience.com/human-co2-smaller-than-natural-emissions-intermediate.htm>
<https://www.skepticalscience.com/print.php?r=45>
Assuming that continues for a year (very likely an overestimate because everything will be dying) that translates to 102 ppm increase. So CO2 levels in the atmosphere will increase from 0.04% to 0.05%. Workplace safety regulations say long term levels below 0.5% are perfectly acceptable.
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I would like to have a space whale type creature that can fly through space. It would be very large and fly from planet to planet using orbital maneuvers. I want this creature to be able to do it naturally as if the species evolved in space as apposed to on a planet. I imagine wings wouldn't work as there is no air to push against. The only thing I can think of is it spitting in one direction to propel it in the other but I don't love that idea.
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You can [Sail On Light](https://en.wikipedia.org/wiki/Solar_sail):
It's very slow, but with a large reflective surface you can use solar pressure to get acceleration. This would allow your whale to maneuver around a solar system.
Keep in mind that because of orbital mechanics, you can even use this to go inwards toward the sun (acceleration takes you out -> your orbit is now elliptical -> eventually you come back in).
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It could also use gravitational slingshots to gain speed for interplanetary travel, and maybe have some kind of gas release (Such as waste gases like methane from digestion) that are able to be 'farted' out (For lack of a better term) to adjust direction manually, like a natural rocket. The act of letting gas out would alter direction, like a breach in a space habitat.
I'm more curious as to how the creature wouldn't be killed from the pressure differences between vaccuum and.. Anything else, most liquids would boil in space. I am presuming some natural kind of radiation resistance is evolution at work.
Another idea for mineral intake is that the creature works similar to a modern basking shark (And the like) in which they filter feed. Instead of small animals/ bacteria, a nice idea may be that they reside in a densely packed nebula and/ or a ring system around a gas giant, allowing them to take in minerals they need from gases and dust in space itself, and potentially high atmospheres of planets.
Some food for thought ^ ^
If you do this,you definitely need space dragons of some sort as a natural predator. Maybe even parasites that live inside the creature like Mynocks from Empire Strikes Back :P
In regards to a comment about the SW being about 1/3rd Earth's size, I'd like to point out some stuff to consider (I don't have enough rep to reply directly);
-This thing is going to have a noticeable gravitational pull; it will affect the tides of an Earthlike planet like our own moon. This could be part of the folklore for X race, that these sky whales are interpreted as some kind of danger omen in their beliefs. Or gods, who knows?
-A creature that big will require tremendous amounts of energy to live. Due to space being space, I'd say the best option is to have it be a slow nicer but have a slow metabolism; it filter feeds and gains energy that is released slowly as opposed to quickly. This would make it a slow creature, though remember space is big. It takes 8 minutes for light to hit us from Sol, and 11 for us to send light to Mars. This thing will be travelling for months or years at a time between planets, so it is vital that it is not burning it's energy too quickly. Gas giants? No-no, the sun is too far away (Unless it's a rare circumstance like an extrasolar capture) that if it gains energy from light, it's not getting energy that far away.
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If a true [reactionless drive](https://en.wikipedia.org/wiki/Reactionless_drive) is possible, then you could simply posit that your space whale evolved one biologically. And if it could do that, then surely it could evolve a kind of fusion power source to power it, as well. The advantage of a reactionless drive is that you are somewhat freed from the Tsiolkovsky rocket equation, so you should be able to accelerate to very high speeds (though only slowly, given current designs).
Also, you have to consider that at relativistic speeds, you really need good shielding, or you will get irradiated to death (a particular problem for biological systems). Your whale will need some kind of special carapace to protect it from cosmic rays and other hard radiation.
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**[Magnetic Sails](https://en.wikipedia.org/wiki/Magnetic_sail)**
Work by interacting with the Solar Wind and generate about the same thrust per weight as solar sails. However, they have some abilities that Solar Sails do not.
**[Electric Sails](https://en.wikipedia.org/wiki/Electric_sail)**
Work by interacting with the Solar Wind too. The E-sail has less research behind it.
The book **The Black Cloud** posited an intelligence formed by a "Black Cloud". The cloud used magnetohydrodynamics to propel chucks of the cloud at sizable fractions of the speed of light as its means of propulsion. Unfortunately, all that was a bit of hand waving.
The problem is that space is too empty to sustain any sort of life that we know of. Not enough nutrients and not enough readily available energy sources in between the planets (let alone the stars).
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To dependably move fast, it would have to have a black hole inside, and then use a form of directed gravity to pull itself towards its destination.
Either that or somehow open wormholes.
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Our intrepid detective has managed to capture a reasonably high ranking operative from the "Big Bad Organisation". He was captured in an area of the city built in such a way a car can not be brought in to transport the prisoner. Think close buildings, apartments with balconies, lots of people in the public areas.
Previously "Big Bad Organisation" has killed operatives who have been captured. The detective needs to get the prisoner back to the police station with out getting him killed. The prisoner would prefer to live. He won't kill him self, he is loyal but not that loyal. If he can escape he will however.
Assume near future levels of technology, guns and knives are the usual tools of "Big Bad Organisation". They are not going to blow up buildings. If they make a hit they prefer not to take out any police or bystanders, just the target. Killing police brings bigger investigations which they would prefer to avoid. The police have had to do this sort of thing a few times before and have training and equipment to make it easer.
The solution I have come up with is a kind of armoured box on a segway thing to put the prisoner in. Every thing else seems to end up with a sniper shot from a window or a bullet from a crowd. Think of some thing like an old police box (The thing the TARDIS looks like) on two wheels and a bit smaller to fit through door ways.
Does this seem like a good solution to the problem? Stairs are an issue. If the prisoner was not cooperating would he be able to throw his weight around enough to topple the thing?
It seems a bit brutal putting the prisoner in effectively a metal coffin, is this a likely solution in an otherwise reasonably polite and free society?
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All buildings **must** be accessible by the fire department and emergency services. In cities also accessible for logistics such as maintenance. Residential buildings will be accessible for the vans residents use when moving large furniture.
Just fake a fire, suicide attempt, or a delivery of large furniture and you can use a car just fine. The prisoner can be inside the (bullet proof?) furniture, in a body bag or covered up on a stretcher. Or disguised as a fire fighter with a mask on. Unless there is a detailed plan that leaks, he will be safe enough.
In the unlikely event the building is really physically inaccessible, there is still some method for moving furniture or gaining emergency access already prepared.
You can also dress him in police riot gear and put him in a group of real police officers in the same gear and same general build. Measures against snipers such as large shields or sheets of ballistic cloth exist.
The most important thing really would be moving fast. Moving the person to secure location should be the first thing you do after you arrest them. You should not give anyone time to plan an assassination. This is quite safe unless your intentions leak before you make the move. In which case the person is already dead or missing when you first arrive and no method for moving them is needed. So in a way your question is misleading as the correct solution is to never be in such a situation.
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Take him to the roof of the tallest building in the area and extract him by helicopter. Depending on how tall the building is relative to surrounding buildings, he might have to lie down to avoid being sniped from an adjacent building before the helicopter turns up.
If the bad guys somehow have line of sight on all available roofs and can therefore snipe the target as soon as he steps outside, I suppose you could have a (fairly powerful) helicopter fly in with an armored box slung beneath it. Position the box on the roof such that the cop and his prisoner can enter it without being exposed to enemy fire--drop it so that the door to the box is extremely close to the roof access door--then fly away with the box hanging below the helicopter.
Presumably the Big Bad Organization is not willing to murder a bunch of cops just to kill the prisoner. If they are willing to kill the cops too, well, I hope there's a secret tunnel system or something like that because your intrepid detective is in serious trouble.
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If this area of the city has a sewer, just walk him out. Since he's underground, the prisoner doesn't really have anywhere to go. Then it doesn't matter how many snipers are positioned in windows and on rooftops because there's no line of sight to make a shot into the sewer.
If you do an air lift, you run the risk of someone taking out the helicopter, which is what happened in the movie [S.W.A.T.](http://en.wikipedia.org/wiki/S.W.A.T._(film)) Using the sewer is how they solved the problem.
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Use a motorbike.
Get a two-seater with a high back for the passenger and then strap him to the seat. Make sure he can't move (throw his weight around) or it could end badly for you.
And hitting someone on a motorbike with a sniper is rather hard.
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Is living on an Alderson Disk possible? An [Alderson Disk](http://en.wikipedia.org/wiki/Alderson_disk) is a large CD-like megastructure, with a star in the center. If the disk is thick enough, it could have its own gravity. Also, the star in the center can bob up and down, resulting in an artificial day/night cycle.
What are the limitations set by this world design? Any help is appreciated!
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An Alderson Disk suffers from almost all of the same problems that a Niven ring world does and has a couple unique to its configuration.
**Instability**
One problem is that the structure / star configuration is dynamically unstable. If you perturb the disk / toroid (by say a meteor strike), then it will most likely (eventually) hit the star - to the extreme detriment of all disk inhabitants.
Therefore, the disk will require an active control system able to restore the disk (toroid) back to its desired location relative to the star if something perturbs it.
**Gravitation**
One bit problem the disk has that the ring world doesn't is gravitation. The disk provides no mechanism for keeping things "stuck to the surface".
If you wish to make the disk massive enough to supply its own gravitational field then you end up with a toroid whose cylindrical cross section is that of Earth's in both dimension and composition.
The problem is, we haven't mastered the use of materials able to resist isostacy (returning to a spherical shape) under those conditions. Rather than simply supplying a force to keep people stuck to the toroid's surface, it would supply enough force to collapse the toroid into a (large) ball of matter - much to the dismay of the toroid's inhabitants.
The extremely bad news about this is that you can't magic the problem away with fantastically strong and lightweight materials. You *need* that mass for its gravitation and it's the combination of mass and gravitation that will collapse your toroid.
**Good news**
Unlike the ring world concept, if you built a self-gravitating toroid, you wouldn't need to spin it to keep things stuck to the inner surface. This significantly reduces the strength of materials requirements (but doesn't get rid of the problems stated above).
**Realistically**
I can't see any way to enable this to work nor can I foresee any unless we fundamentally alter our understanding of the Universe.
But if you have your heart set on the design, just include the fiction changes required to make it work. I think an extremely light weight design with gravity generators would work (until someone shuts off the power). You'll want some fail safes, along with fail safes for your active stabilization system to keep the toroid/disk from contacting the surface of the star.
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As a general rule, gravity pulls you to the center of gravity of the most gravitationally influential object for your position. In this instance, it seems like it would be the ring. The center of gravity for the ring is... somewhere in that star. This means your people, unless they have things to brace themselves against, will fall into the star. Given that a habitable zone is usually on the order of ~1 AU for a star like ours, I'm willing to say that this will very likely be the case.
[Vsauce](https://youtu.be/VNqNnUJVcVs?t=36s) did a video on a "flat earth" which has a simulation of a flat earth. It displays the problem with living on any disk-like object; the further from the middle you are, the more gravity pulls you to the center of that disk and less to the ground you're trying to walk on.
If the disk was spinning, it would not change the center-of-gravity for the disk. People would still fall into the middle unless they were at a *very specific radius*, where the acceleration provided by the disk/star's gravity forces them to essentially orbit the star. If you go too far to the edge or center, you'll fly off of fall in.
The best way to overcome this would require a disk that was much, much thicker than it is wide. Alternatively, your disk would need to be infinite in diameter to allow for equal gravity all along the disk. If you're willing to have a structure of nonuniform density, you could make the habitable zone much more dense (and therefore gravitationally *stronger*), but this still may not work because of that tricksy center-of-gravity.
What about this "infinite sheet approximation" people keep talking about, claiming that the gravity "close" to the surface would feel normal? Well, that's called the [infinite sheet approximation](http://umdberg.pbworks.com/w/page/50928430/A%20simple%20electric%20model%3A%20a%20sheet%20of%20charge), which is more often used in electromagnetism, but can be used in gravity. It turns out that this approximation is only good as long as the distance between you and the sheet is about 1/5 of the distance between the point below you (on the ring) to the edge of the sheet. So if your ring has a thickness of 1 au, your infinite sheet approximation works for 1/5 AU above the surface in the middle of the ring. If you're 1 m from the edge, the infinite plane approximation only holds to about 1/5 of a meter.
There is also the slight problem of that sun drifting into the side of your disk. Due to the fact that it is surrounded by an *equal amount of material* in the plane of the disk, it can drift around in that plane as if the disk wasn't there. (It's the 2-d case of [gravitational force inside a shell](http://hyperphysics.phy-astr.gsu.edu/hbase/mechanics/sphshell2.html).) This means your sun could very easily run into the inner radius, which I imagine would cause problems.
There are also some problems with tidal forces; the inner radius of your disk will experience more pull from the star than the outside of your disk. Unless the material is strong enough to withstand these forces, the star could rip the disk apart. Of course, the proposed disk is large enough that I think it must be made out of some magic material.
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Like Niven's Ringworld, the Alderson disk would have to be made of unreasonably strong materials (the super materials "Scrith" and "General Products" spaceship hulls were made of materials which had the strong nuclear force enhanced.) Outside of science fiction, a super civilization might be able to manipulate neutronium, which is also dense enough to provide gravity for the inhabitants of the disk, assuming the inhabitants were the size of bacteria and comfortable with a surface gravity measured in thousands or millions of *g*. I suspect that amount of gravitational pull on the equator of the star would pull it apart as well....
The Alderson disk should really be thought of as a sort of thought experiment, rather than a real thing. If you want something like an Alderson disk, perhaps you could follow the example of Forest Bishop, who scaled the Ringworld down to something that could be built from real materials. A Bishop Ring has a radius of 1000km, a width of 500 km and the atmosphere is held in by a combination of centrifical force due to the rotation of the ring, and walls on the edges of the ring that are 200km tall. A system of mirrors reflects sunlight over the walls and onto the surface.
Your "CD world" would use a fusion lantern or a "disco ball" like target for the solar mirror platoon to provide light, and a large disk to provide the surface area. Air and water on the surface would rapidly escape into space unless there was some sort of "roof". Perhaps a huge, transparent cover made of diamond or similarly hard and transparent material could be constructed to cover each side of the disk (giving the term "jewel case" a whole new meaning). The maximum size would depend on the materials used, but Graphine, Fullerines and other materials of that nature would allow you to make structures measuring hundreds or thousands of kilometres in diameter.
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One problem is gravity. For people to be pulled down, the disc will have to be very thick. At that level of thickness, one has to make sure that the material but the disc is composed of is strong enough to avoid collapsing on itself. Also, relying on the bobbing of a star for a day/night cycle is very unreliable. Getting it to bob steadily would en difficult. Also, a bobbing sun would contribute to what I will discuss below. Most of all, they would die. This is because the gravitational equation is an inverse square law. If the sun is not perfectly in the center, the gravitational pull will be weaker on one side and stronger on another. This will result in the disk crashing into the sun. One might say that as long as we do not service star, it will be perfectly in the center. This is not the case. No one can perfectly put the star in the center. Even if extremely close, over the eons it would slowly crash into the sun. Even if they could put it perfectly in the center, we must remember that the sun is not static. It is solar flares and their comments and other disturbances all throughout the solar system. These things would cause it to not be perfectly center.
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You need enough forces to keep the Alderson disk from collapsing in on itself. Let's assume a thickness of 6000 km, with 1000-km walls on either face around the interior rim made of tungsten, which has a melting point of 3695 K, and we'll assume that it has an albedo of 74%, and the sun at the center is just like Earth's. We can safely place the inner rim at .01 AU, but we will need to deal with the gravitational force exerted by the sun. Let's put the walls at 1 km thick, which means that they'd have a total mass of 1.45*10^24 kg, and as the mass of the sun is 1.98*10^30 kg, the force would equate to 8.56*10^25 N. The pressure would be 1.14*10^9 Pa, and that is for the walls alone. If we want some semblance of a habitable zone, we would need to have it stretch all the way to 1 AU, and we will assume that the rest of the material has a mean density of 5515 kg/m^3.
The total mass of the structure would be about 4.61*10^31 kg, which means that the force of gravity on the walls would be 2.72*10^33 N. No known material could support such a force, so you will need to work with something a good lot stronger than anything we know. The material's incredible strength would also create some pretty bizarre gravity. At the inner and outer rim, ignoring the sun's gravity, gravity would be about .560 N/kg, and when you factor in solar gravity, the outer rim's gravity is .566 N/kg, and if you were to stand at the inner rim, you'd fall into the sun. As for the middle of the faces, the gravity is 341 N/mg, which would be impossible to survive in. In between those two extremes, there would definitely be some sort of region where there's just enough gravity, but I've made a lot of assumptions.
An array of mirrors and lenses could be used to make sure that there are regions that get just enough heat and light for life to exist, and have a suitable amount of gravity. But, we would need to bend the laws of physics a good bit for an realistic Alderson disk.
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I'm at the early stages of the development of a novel set in a world that lacks human relationships. The main plot will involve characters slowly learning back to care for one another.
It's not a world abandoned to anarchy. There is some kind of authoritarianism which inhibits freedom but guarantees a decent quality of life: technology, sanity... The government doesn't want people to socialize, but relationships are not explicitly forbidden and punished: this is not needed, because people just forgot how they work. I need Ideas about how such a society would work. How would these people live every day.
I'm sure some inspiration could be found in other stories (in any media) that explore the weakening or total loss of relationships between people. Groups of characters, or entire societies not capable or not allowed to experience at least one of the following: love, friendship, familiy bonds, or even basic communication between individuals.
My setting would be Distopic Science Fiction, I think it is ideal for an investigation on this theme, and I'm quite sure many authors have worked on this in the last decades.
The only valid example I could think of is the movie Wall-E by Disney Pixar, where all humans are controlled by a system based on marketing and TV, and have become dumb customers who never talk to each other, but I'd like also a more mature and deep approach.
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**The government doesn't want people to socialize, but relationships are not explicitly forbidden and punished.**
I'm assuming a few things based around this statement:
1. People aren't isolated. Society exists functionally much like it does in our world -- people still go to a market to buy food, people still go to a job of some sort, etc.
2. There is a reason for this. The government doesn't want people to socialize *because*... if they did, they would realize *something* about the government or themselves that the government doesn't want them to know. But I can't imagine what that might be.
3. This had to begin *somewhere*, *somehow*. I'm assuming that relationships used to exist in this society at some point in the past, and that the new government has diminished the need for them somehow.
**I need Ideas about how such a society would work. How would these people live every day.**
How the society works is based entirely around *Point 3* above. How the society works *now* is a result of the changes made by the government long ago in order to remove the need for relationships. Did the government make work-from-home mandatory, or force most labor and office positions to become automated? (I hope not; that goes against *Point 1* above, and would make a boring story) Did they create a law that states that a child must be removed from her parents on her fifth birthday and never make contact with them again? Whatever new rules and laws the government put into place initially, which would have sent people back then into some kind of outrage, are commonplace and expected now.
I'm curious how procreation would work in your society as well. If the government is discouraging relationships, then they have to be encouraging some alternative form of procreation. I guess artificial insemination?
**I'm sure some inspiration could be found in other stories (in any media) that explore the weakening or total loss of relationships between people.**
Honestly, it's happening now, with sites like Facebook, Instagram, and StackExchange. People *believe* they are forming relationships and interacting with people -- I can check how my brother's day went just by looking at his facebook wall and even leave a comment if I want! But in reality, the relationships between people are diminishing. You lose the physical touch, body language, tone of voice. Next to go would be expression: What if instead of typing out a status on Facebook, you simply got to choose from a list of "feeling" words? And comments were only drop-down menus of choices like "That's awesome!" or "Sorry to hear that. :(". Hell, at some point you wouldn't even be able to be sure if you were really talking to the person or a machine pretending to be them.
**Ultimately,**
I think it's kinda difficult to tell you what the person's day-to-day life might be like without knowing why it's like that in the first place, *Point 2* above. It seems innate that people -- any animals really -- have a certain desire to be close those of their kind. It's therefore hard to believe that people would consciously *choose* to live this way without some very heavy influence.
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Your wording choice leaves a lot of freedom in the answers. Hopefully some of these spark an extended discussion, and possibly more questions:
**No Relationships, as in no humans are aware of each other**
*The strictest of definitions I can imagine is one in which humans are simply not allowed to be aware of each-other's minds. As this occurs automatically in society, the government would have to stop it.*
First off, an assumption I will make the entire time: the government never forces anyone so much as coerces them to play along. If the government is forcing the destruction of interpersonal relationships, humanity itself will fight back. The government will have to smoothly adjust the human mind.
The Problem of Other Minds is a class issue in psychology and philosophy. We become aware of "other minds" at roughly the age of 2 or 3, and begin to treat them as Others. This would be a relationship, so the government needs to make sure nobody ever gets an opportunity to be aware of other minds.
One solution is homogeneity. In a normal toddler development, there are very clear minds: parents, the cat, and maybe even the pot that is so remarkably kind as to protect their head during their quest to slay the dragons and/or get the cookies off the counter without mommy noticing. The toddler eventually notices there is something different about some of these minds, and categorizes them as Others. If the government could set up each person's environment to be more homogenous, it could remove the need to identify Others until that part of the mind doesn't function. As an example, consider Stack Exchange without names, icons, or scores. Just a flat Q/A database.
One other solution is disruption. Other minds may be hostile, and one of the easiest ways to generate artificial hostility is a language barrier. If each human is trained different, linguistically, the government could ensure that they have no desire to talk to each other, even if they recognize the others as minds.
**No Relationships, as in no monogamous relationships**
*Less exacting would be the desire to overcome monogamy. Marriage is a very powerful institution today, and I could see a distopian government wanting to squelch it and take the power for itsef.*
This would take more balance. Groupings form naturally, whether pairs, trios, or any other grouping. Effort would have to be taken to make this undesirable. One solution involves some number games. In Chinese culture, some numbers are considered unlucky. If the government could make the number two tremendously unlucky, anything in 2's would be avoided subconsciously.
This could have *very* interesting effects on AI. While binary is the easiest way to build a computer using electrical circuits, there's no reason you could not develop one using trinary logic. Trinary logic is more conducive to AI because it allows for either "maybe" or "unknown," both of which are useful for AIs.
**Defunct relationships, with little caring**
*The definition of a relationship is tricky. How does the government know it got them all? Another approach might be to simply allow relationships, but ensure that when they do occur, they don't matter much.*
This is the most distopian case in our current environment. As suggested by others, computers are leeching our attention away from each other continuously. All we have to do is make sure the humans lose the ability to be soft enough to truly support one another better than the machines do, and the relationships become unimportant.
Bright flashy lights, issues that need immediate attention, intelligence puzzles rather than intuitive puzzles, these would all condition us to a style of interaction which ensures there is a barrier between everyone.
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My first question would be "Why doesn't the government want people to socialize?" Both the real reason, and the reason they give to the masses. (though I think social imperative would work better than a government mandate).
Maybe a huge uprising was blamed on people being to emotional and attached to each other. So being more logical and robotic in social situations would be safer and 'better' for everyone.
(The vast majority) Humans need social interaction. Even us introverts. However, it could be considered the 'ideal' to strive for. But (like everything else we do) we take it to extremes. This would lead to people falling into depressing much more often and those naturally bright and sunny people would be absolutely miserable. They would be the ones who might decide to start a revolution to bring back human emotions, lead by a group of ENFJ's...
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I imagine that this would be a world where we the people would have been assigned a living quarters at an early age that would be loaded with a near perfect virtual reality system. The system would communicate with a tiny chip implanted in our brains which anticipates our needs, much nicer than the vagaries of human communication which begins to seem a bit like hard work.
From here we work, play and communicate with this synthetic environment, never actually seeing another physical person. Although in reality the person in the next apartment would be very close, that would never occur to us since we have been overwhelmed with the constant stimulation of our virtual world.
I imagine, this system would evolve from a simple media tool which people would originally use with a clunky input system to share their thoughts and feelings with their closest friends. But it would rapidly degenerate into a stream of cats and thug life videos shared by every one you have ever met and as the mysterious vendor invested in virtual reality technology it would progress rapidly into an immersive stream of funnies designed to appeal to the lowest common denominator. People would quickly lose the ability to communicate, relying on a simple set of icons to express their emotions in a tiny subset of expressions before moving on to the next experience. I can't wait!
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Basically, lets presume here.
Me, I just relate to any people because society COMMANDS me to do so. I reached a point in life where I have all the monetary and otherwise any other resources I need. I just have a pretty good set of investments and they are run automatically by Bank Account managers that I don't even need to know by name. The only thing I know is that the money is available on my bank accounts to buy anything I want. So, I don't need to interact with any people. I can just go and buy anything I want online and have it delivered downstairs. Then, the butler will just put it on my private elevator and I will open the door and get it. I have my own gym and so on. Besides interacting with a doctor and dentist, I don't really NEED to interact with any other pathetic humans.
So, if people in your society have access to a set of technologies that eliminate any need for human interaction (virtual A.I. based doctors, automatically delivered medicine, robot dentists and such), they will not need to develop any kind of human relationships.
For people that have access to resources (in our world the main resource is money) relationship with other humans is not a necessity. Human relationships are only necessary for people that lack resources. Those people NEED to interact with other people on other to obtain the resources they don't have. And that is the only reason why human relationships are created. (feelings and so on are just chemical reactions in the brain to justify those needs for human interaction so individuals don't actually die because of the lack of the resources they don't have).
Humankind is despicable, ignorant and unworthy, unable to create anything of value, it is shallow and exploitative, and also evil and destructive, why would anyone want to relate to other humans if not for that need of obtaining resources not immediately and individually available?
So, there you can find something to start your plot, I guess.
Government to safeguard people from all exploitation, suffering and evil that are the natural results of human relationships developed an educational and cultural system, and also promoted technologies to stimulate people to not give opportunities to predators and parasites to use the "relationship" excuse to pillage and hurt other people, so, people do not interact with other people anymore. Everything is done online, children are born through planned processes and in children farms, or they don't even exist anymore, as health services and technology reached such a point that people have to choose dying, so there is no need for the replacement children represent on order to perpetuate human species. If they don't choose dying, they can just live forever, through cloning, robotics, mind upload/download, and so on.
World is then in peace as no relationships will bring strife, or war, or disease, or suffering. Each one lives in their own exclusive little world, while the machines do everything and people just can enjoy all they need from interactions with computers and A.I.
Then your characters will find that they can do something through relationships (perhaps they fall in love, or find a lost teddy bear, or something that will make proletarians cry, so normal people that lack resources can identify themselves with your characters, and like your story), and they began to dissent to do that whatever.
Well, the rest is up to you.
If you had asked this question 20 years ago, in the old Internet, you would have lots of misanthropic answers like mine. But in this age of social networking, all kids seem to need some sort of pathetic interaction with other humans. So, I guess you needed to read this answer of this old misanthrope. Hope that inspires you in your plot.
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If there was no human relationships, we wouldn't know each other, not talk to each other, because both of those things is a relationship. Anything you would do to someone is not available to you. You can't do things you were supposed to do. The internet also connects people. You wouldn't be able to use the internet unless it has no human contact. No Skype, SnapChat, No Instagram, (Oh no I can't see your food!) Dubsmash. You can't have anything. You can have a connection with your dog.
Hope this Helps You
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I'm world-building for a universe. I just came up with [Deals Best Kept](https://www.reddit.com/r/magicbuilding/comments/13zzie0/deals_best_kept/?utm_source=share&utm_medium=android_app&utm_name=androidcss&utm_term=1&utm_content=share_button), and I realized I wanted to have a bunch of fantasy races interact, be very culturally diverse and mixed, and also account for a lot of the anachronism that happens in fantasy, specifically how you have multiple different fantasy creatures from different mythologies.
All interacting but not really, so I had an idea the Fae were a very broad grouping of magical creatures in folklore anthology, so I decided how about in this universe the Fae brought in or conquered many of the fantasy races we know, with the story setting being centuries later in a fantasy-esque early 20th century around when World War I might have happened, but I didn't want homogenization or a monoculture going on.
**How do I build a unified national identity? Multiple ethnicities, multiple cultures, one single nation? More importantly, how to get the tribes to accept the empire's culture and customs While retaining their distinct culture'**
The points below are just the world-building I've come up with so far.
•The Fae are similar to the fae depicted in folklore and mythology. They are known for their cunning, wisdom, and deceitful nature. They possess magical abilities and have a strong connection to the spirit realm.
•The Fae have a unique approach to cultural assimilation. Instead of conquering other cultures, they gradually seep their legends, traditions, and culture into the societies they assimilate. They learn from the locals, exchange stories, and adapt their own practices, while still allowing the other cultures to maintain their cultural identities.
• Fae magic is based on the concept of presentation and theater. They believe in "faking it till you make it" and have the ability to present themselves in a way that aligns with what they want to become. This includes positioning themselves as immune to harm or adopting disguises.
• The Fae approach warfare in a theatrical and strategic manner. They focus on presentation and deception, using tactics that seem like exaggerated legends. Their battles involve clever tactics and illusions to confuse and outmaneuver their enemies.
•The Fae's influence on other races varies. Elves and dwarves, for example, have assimilated into the Fae Empire while retaining their cultural identities. Humans were treated as slaves initially but were eventually integrated into the empire with a softer touch. Goblins faced prejudice but proved their worth, leading to their reluctant inclusion. Orcs, with their strength-focused culture, developed an understanding with the Fae and joined the empire.
•As time progresses, the Fae's stories and legends from other cultures undergo subtle changes. They retain the roots and themes but adapt the language and presentation to fit their own cultural sensibilities. Stories that do not align with their ideals become more metaphorical and obscured in subtext.
Thanks for any help
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The Fae have taken over the cultures but they haven't *taken over* them in so many words. Does it sound contradictory? Absolutely -- But that is the point.
Their entire species is about being theatrical, deceptive, and wise. They understand that they don't have to go in and crush their opponent's military to take over. So they don't -- they instead attack on an axis their targets aren't well defended against. Sometimes that is force, other time it is not.
They know that to take over the world means that they have to administrate it. And that would be *boring* work, not at all conducive to a race that likes their theatre. But you know who knows how to administer the Elven Empire? Those elves you took over. Those Dwarves that you have taken over seem pretty good at handling Dwarven affairs too -- let's put them to work administering the Dwarven Kingdoms.
And how do they explain this? Well as an example, the Fae spin a legend. The Dwarven Kings lost the blessing of the Dwarven Gods for their slights against them. The Dwarf Gods searched for a new family to bestow their blessings on in order to rule the dwarves, one stout and true with a zeal to improve their species (in a way the Fae want). Make up a sufficiently dwarf-y test of worthiness and there you have it, a mythological justification for the new leadership. Spun right, this will last centuries.
Will some of them have the ambition to try to free their race from the yokes of the Fae -- Sure. But if the populace is all right with their distant overlords, and their modified legends promise retribution for defying said overlords, then those that seek total freedom will likely not get far before they are thwarted. And likely ironically punished.
In the end, my thought is that the Fae are basically the a combination of the UN and a feudal lord. They're the ones that are the final arbiters on matters between their vassal states, but try not to interfere in their day to day lives so as to not irritate them too much. They use their wisdom and power (actual or perceived) to arbitrate decisions with an eye for doing what is best for their empire. They draw their tithe from their vassals to keep their power intact but will otherwise let them do their things.
Considering that traditionally different fantasy species have different specialties this isn't as hard as it may look. Those humans with their short lives might be an issue since many don't think quite in the same longer terms as other species, but that isn't anything that can't be handled.
For a comparison, see the Civilization games, notable Civ 6 for this. The Fae have basically won a Culture Victory.
PS: The Fae tried this with the humans once. Turns out strange women lying in ponds distributing swords was not the best way to create a long-term government. But it was quite dramatic while it lasted.
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So, this is very much a real-world problem, especially in the West.
How I **Believe** it can be solved.
* Every group has to have something in common, that they **all** voluntarily believe in.
It could be:
* Religion
* Nationalism
* Music
* Sport
* Values
* National Service
* Whatever
For the real-world aspect, I **personally** believe that part of the issue in the west is that we have forgotten our own values (or more specifically, had them critiqued to death by self-loathing academics with an ulterior motive).
To add weight to this answer - if you look at America just post 9/11 - the whole country was united in a shared experience - the horror and anger at the event.
Alternatively - look at the British Sikh community, **especially** on St George's day - you'll barely find a more patriotic display of Flags, Bunting and quintessential Britishness.
As a personal anecdote, As a Metalhead - visiting Wacken (the biggest Metal festival in the world) - you could be in the Moshpit with people from different continents, but because you are all there, of your own free-will (and as some considerable effort for many people), for the same reason - in that moment, you are one.
You have a shared experience - you aren't Black/White/Yellow/Green - you are all Metalheads.
Traditionally for most countries - this was achieved by Religion, however not everyone believes and not everyone shares the same gods.
Nationalism is the next most common one - the belief that the country is generally good. This works fine, right up until it's taken from the Country is good to the Country is superior, and everyone starts speaking like a *mid-century German...*
Sport - In NZ, that's Rugby, whilst it's not as universal, Sport does allow people to come together - in Auckland, going to an All Blacks game, you'll see Middle-class families, Rich older ladies, Recent migrants from Korea who barely speak English, Large Pacific island families - all resplendent in All Blacks gear.
Same with Music.
Values is harder to do - as generally Values that don't have a basis in Religion or something that can withstand philosophical undermining is difficult to do.
National Service - As I've gotten older, although the idea of conscription into the Military isn't appealing - having something that every member of the population goes through is a very good way to build national identity and cohesion, even with different groups. Now, you could make it so that it's not **Military** service - but something similar - but the key points being that it needs to be as near identical as possible and for long enough that it's a lasting experience e.g. 1 Year of doing *something*.
There may be other things you can come up - but that's my thoughts. A Lot of this is based on personal experience and seeing how certain areas have changed over time as the culture has been fractured more and more.
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Two methods come to mind from history
1. Focus on the top.
Instead of trying to assimilate the common elf focus on the elet. Mary in to the elet they have your newly weed introduced your clothing, customs, and language to the elet. In a few generations they see themselves more as Fea then there orginal race.
We see this in both the Spanish and Roman empires.
2. Comon ideology/religion.
Send teacher or preacher to persuade the inhabitants to not only convert to your religion or ideology but to make there position in that ideology there primary identity.
There no longer elves, dwarfs, hobbits, there the working class, or Christian, or the enlightened.
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Homogenization is the tendency in history, with many peoples even using genocide to get there. So called "multiculturalism" is a modem phenomenon that's generously 150 years old, but more like 90, that only exists because of the commercialization of rapid air travel (and it is very far from proving itself as a durable ideology). So, if you're in a WWI era equivalent, **no explanation is needed**. Fae and everything else are exploiting the same situations we have now, leading to *fast* mass migrations. 200 years ago, all your races were more or less living only in their homelands.
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It probably boils down to *one* simple thing: if the empire benefits the different races that are part of it, then they work together no matter how different they are.
At best, they can even combine their different views to benefit the empire. However, if they see the empire (or being part of it) as a big enough problem, they combine their strengths to fight it, or even to bring it down.
So, it is up to the empire to prove that the different races are better off being part of the empire than not being part of it. There are different ways to approach this challenge, and there are multiple ways to make this happen, so it is entirely up to the story make it work & make it interesting (and relevant).
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The currently ruling elite just declares there culture the best there is and declares the others rural and hillbilly. Happens everywhere time and time again. Some elites of the other cultures adopt it, others reject it, that is the whole idea of empire.
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One of the superpowers in my world is the ability to mentally manipulate portals. These portals are incorporeal, massless, 2-dimensional circles that connect points in space (akin to portals from the game Portal, except they are free-standing and can be telekinetically moved).
Portals effectively create infinite energy, which I'm not at all worried about. If that particularly bothers you, imagine they draw all the energy they need from 'the realm of magicness'.
# Trainable/Alterable Aspects of Portals
These are the aspects of my portals that I can mentally alter. Most of these are trainable, allowing me to alter them further or more quickly as I gain experience.
* Portal size
* + Determined by the area of the portal cross section. Requires effort to make it larger or smaller than its 'base' size of a 30cm radius circle.
* Portal shape
* + Circular when unstrained.
* + Shapes can only be two dimensional.
* Portal movement speed
* + The greater the portal size deviates from its base size, the slower the portal moves.
* Portal rotation
* + Can be rotated in the x, y, and z axes.
* Max distance between portals
* + Around 50m without training
# Portal Rules
## Important
* Matter, light, and electromagnetic fields can pass through portals, but not gravitational fields.
* Portals come in pairs, with a back end and a front end that connect to one another. Most users only ever control one pair of two portals.
* Both portals will always have the same size and shape as one another.
* Portals will cut things at the atomic level, but not the subatomic level, meaning no boom boom and radiation.
* Movement through portals is relative, meaning if I enter Portal A at 10km/h relative to it, I will exit at 10km/h relative to Portal B. This means that even if I am stationary relative to the world, by quickly moving Portal A over myself, I will exit Portal B at high speed. See my [crude drawings](https://i.stack.imgur.com/OoYcI.jpg) for a further explanation (Also feel free to ignore my misuse of scientific technology as I never took physics). You do no not feel acceleration or deceleration from this, as from your own perspective it is the world that is changing velocity and not yourself.
* Portals move relative to their user. If I start running, without controlling my portals at all, they will move with me. In cases where their relative movement would change after I exit a portal, they only begin to move with my new direction after I have fully exited the second portal.
* Portals can be rotated, causing the world through the portal to appear to rotate. This allows you to impart rotational or centripetal energy to objects moving through portals. See my [crude drawing](https://i.stack.imgur.com/rlgH2.jpg) for a further explanation.
* Portal edges are effectively infinitely sharp cutting instruments, making them highly dangerous.
* Moving and altering portals does not strain the user or consume energy from their body.
* Other than when the portals first appear after gaining the superpower (the portals will appear snapped together), the portals cannot be created or destroyed. They will remain until the user dies, hence why snapping is important.
## Less Important
* Portal pairs can be 'snapped' together, causing them to perfectly overlap, completely removing their functionality, as anything that passes through them will be teleported 0 distance. They must be actively 'unsnapped' to separate and be useful again. Snapped portals are completely invisible, only being detectable via the users proprioceptive sense.
* Portals are only visible due to the fact that they appear to be a circle leading to a different point in space. They don't have glowing edges or anything like that.
* Users have a proprioceptive sense of where their portals are, and the portals will instinctively stop moving before cutting their user, meaning a user can only cut themselves on purpose.
* Portals can be moved through one another, as seen in [this video](https://youtu.be/jSMZoLjB9JE).
* Portals accelerate and decelerate instantly as they are massless (yes I know massless objects in reality always travel at c).
# Combat Applications
## Velocity Alteration
### Instant Acceleration
By moving a portal over myself, I can almost instantly boost my velocity, without actually feeling any acceleration. By doing this over a body part, such as my fist, I can increase the power of my attacks.
### Instant Deceleration
By slowly moving a portal over myself while I am moving at high speed, I can cause myself to exit the corresponding portal at a low velocity, effectively eliminating my kinetic energy. This is highly useful for preventing deadly falls or any situation in which I would slam into a surface at high speed. By doing this over an enemy's attack, such as their fist when punching me, I can reduce its impact.
## Shielding
Portals can be used as impenetrable shields. Depending on how I position them, I can cause an attack to reflect back onto my enemy, or shoot harmlessly into the sky.
## Flight
By carefully positioning myself through my portals, I can cause gravity to tug on me in opposite directions, allowing myself to [fly](https://i.stack.imgur.com/98IEQ.jpg).
## Slicing
People and objects can be easily cut by moving a portal through them. Depending on the orientation of the portal, this might either cut holes out of them, or slice right through them.
## Swinging Objects
By placing a snapped portal pair over an object held firmly in place, such as a tree or streetlight, and then moving one of the portals away, I can use that object as a powerful blunt weapon, as the part of it sticking through the portal will move with the second portal.
## Range Extension
By placing one portal near myself and one near my enemy, I can significantly increase the range of attacks such as punches, by punching through the portal. Of course, I will have to be careful as my enemy can do the same.
# Industry Applications
## Free Energy
### Hydro-electric
By placing one portal at the bottom of a dam or lake and another higher up, I allow water to flow continuously downward, providing energy that can be captured via a turbine. The output is limited by how large I can make my portals, and how far apart I can place them. This could theoretically be done with any fluid, or even something like sand.
### Magneto-electric
By placing by portals in such a way that I allow a magnet to continuously freefall, I can induce a current in metal coils surrounding that magnet.
### Direct Turbine
Placing the shaft of a turbine through a portal and then rotating it lets you directly power the turbine. This can produce enormous amounts of energy as the turbine can be made as large and heavy as possible, and spun incredibly quickly.
## Digging
Portals allow you to move massive amounts of material very quickly. For example, you could dig a massive hole in the ground by moving one of your portals through the ground, with all the material that enters it falling out of the second portal.
## Construction
Careful control of portal shape and size could let you cut precise objects out of stone, metal, or wood.
## Transportation
Portals allow you to freely move material from one area to another, but this is significantly limited due to the portals' range and size.
# Non-combat Applications
## Air-con
By placing one portal near myself and another notably below myself, air will blow out of the one near me due to differences in air pressure, creating a refreshing air current.
## Watergun
By placing one portal in a body of water, water will begin to pour out of the second portal. This is effectively the same as the hydroelectric energy generation concept, but on a smaller scale and just for fun.
## Looking around corners
I can peek a portal around a corner instead of my head, allowing me to look through its pair.
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**Covert ops**
Place your pair of portals before a wall or a building, then move one of them sideways into/through the wall parallel to its plane, so it won't cut a thing. Once the portal is "in", and the view-through is not obscured, you turn the inside portal parallel to a wall and place the outside portal close to the outer surface of the wall you're about to penetrate. Hello portable hole, you focus on locking down both portals and transfer in and out of the room. Afterwards, eject the inner portal the same way, leaving no trace on how did you enter and exit the protected area. You can use such technique to reach into enclosed devices like safes or vaults. Combine with "slicing" if you need to eliminate surveillance or guard.
**Swap gun**
Position your portals side by side with "blue" surfaces facing one side (the placement is correct if an object that's thrown from your side in one of the portals ends up on another side), then toss both portals forward with maximum speed attainable. Whatever matter is located forwards would get swapped between two 3D tunnels made by portals' edges. This would effectively kill any living creature that would have its head happen away from its body. Once at maximum distance, shift them sideways and pull back towards you, creating another pair of swaps.
**Ultimate shielding, reflective shielding**
Position your portals side by side (making them square if the user is able, to reduce the risk of someone hitting between them) so that the object thrown from your direction would get tossed back. Release control and position yourself between whatever is being protected and the enemy. Anything hitting the protected area would get tossed back at the same speed. HEY YOU, CATCH! If protecting against shelling, turn both portals so that the outer side is facing upwards at an angle.
**Emergency catapult**
If the portal user is in a freefall, he can position the portals like in Reflective Shielding, but below themselves and parallel to the surface, then exert control to lock them in position. They would then get thrown up and forwards from the projection. Once the user starts getting teleported, they can release control so that the portals would resume moving with them. This can allow the user to both escape death by freefall, alter the vector of their fall by turning the exit portal relative to the entry portal, and potentially also to avoid incoming fire.
**Invisibility**
This would require the user to have rather large and close set of portals. Position your portals at both sides of yourself, parallel to each other, and occasionally rotate them as a whole. The outside user would see objects behind you being one inter-portal distance closer while you are between them and the observer, but won't be able to see the user or actually interact with them because any force applied to the entry portal would just travel to the exit portal, leaving the user unharmed. The downside is that the user would be surrounded by "infinite" sights of themselves on both sides and unable to see what's there on the side.
As a side application, the user could scratch themselves on the back without external help or twisting their arms too much. Just face one of the portals and reach the back visible through it.
**Kidnapping**
Pull one portal under the target in the floor's material, the other at destination at the ceiling, then raise the first portal encompassing the person. It will fall right into your arms. Surprise!
**Tectonic weapon**
Pretty easy. Aim one portal at the enemy, then toss the second portal down flat. The enemy would have a faceful of rock, and the planet would have a deep well. If done deliberately, the well could turn into a volcano, adding insult to injury. If the user would turn the second portal midway, the well would become a cave, so this application could be used to make subway tunnels. And mountains.
There should be more, as this question asks for fantasy, as in "use a thing in unintended purposes".
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In most game systems I have been involved in, the game master has a "cheese detector." This is a process whereby any aspect of the game that "makes swiss cheese" of things gets ruled out. Portals are usually on the list pretty quickly.
First, the only "downgrade" to portals that I have been able to detect. Your idea of peaking around a corner does not work. If the light you want to see can reach you, so can your opponent's ranged weapons.
The over power (OP) of a portal comes from the range it can open over, and the different conditions that may apply at the ends. You have touched on a few of these, but consider a little more.
Put the exit end of the portal horizontal and elevated over the entrance end. Exit facing down, entrance facing up. An object placed between will fall. Into the entrance and out of the exit. It drags the air with it. A one ton boulder (roughly 1 yard by 1 yard by 15 inches for most rock, or for metric folk, 1 meter by 1 meter by 35 cm) would then build up a down-rush of air and boulder that had no limit. Leave it there for 20 minutes or so, then turn off the portal so the boulder hits the ground. It creates a crater some miles across. You would need to open another portal to get out of the blast radius.
Put the exit end of the portal pointing at the village you are angry at. Put the other end about 100 yards under the surface of a lake or ocean. The pressure at that depth is round-about 10 atm. That's high for a fire hose, which is typically only 4 or 5 atm. If the portal were wide enough to walk through, you can wash away the entire village in a couple minutes. Or you can put out a quite large fire if you are inclined.
Put the exit end at extreme altitude, say 50 miles. The air pressure is quite low there. The entrance is then a very large vacuum cleaner. A portal wide enough to walk through will have round-about 50 tons of air pressure acting over it. And if the opposition lives through being vacuumed up, then they are pushed out of the portal at extreme altitude. And even if they live through *that* it takes them considerable time to get back to the fight. Felix Baumgartner took about 10 minutes for his fall from the stratosphere. So, probably the fight is over before they bother you again.
Depending on how difficult it is to navigate placement of the ends, you can extract things from vaults. Portal in. Open the exit portal. Start shoveling stuff through. You only have to move the stuff you are extracting far enough to get it into the portal. If you can move the portal ends around that might only be a few inches. The entrance can be horizontal so you can just tip over shelves such that they fall in the hole. You could clean out tons of stuff from a vault in minutes. Then you could use another portal to fill the vault with surprises of whatever type you please. Ocean water as previously mentioned. Fresh cement that will harden shortly. Farm waste. You name it.
The opposition has a castle of some kind. Any nasty surprises you have can be delivered directly inside the wall. The water jet just mentioned is just one example. Getting bored? Build a very large pile of wood, hundreds of trees. Set it on fire. Put the entrance portal in the very center of the fire and the exit inside your opposition's castle wall. Open a second portal of the vacuum cleaner type, drawing large quantities of air through the fire portal. It's a huge blowtorch.
Portals are massively OP. The "cheese" factor is too high.
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# Tactical Nuclear Weapons for Everyone!
At least, everyone who can make a high altitude portal, or has access to a vacuum tank.
A "God Rod" is a tungsten bar, dropped from space. It delivers the power of a small yield nuclear blast, with none of the messy isotopes, with solely kinetic energy to create the blast.
A portal user positions one portal below the other, in a vacuum, and drops a heavy weight through it. You leave it falling, to get to some absurd velocity, then move the lower portal, either pointing it towards a target or just straight down. Boom, instant, colossal explosion.
It needs to be a vacuum, because terminal velocity is an issue.
Edit: It's definitely a problem that this is tough to aim. However, giving the average portal user the ability to blow up a sizable section of a city, even at the cost of their lives, is a significant power.
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Another answer stated that this device is uber OP, and I think that is an *understatement*.
**Time Travel**
You didn't explicitly state this, but the real-world implementation of such a portal would be via direct manipulation of the graph structure of reality (the so-called Wolfram Manifold) to disconnect and re-join disjoint sets of spacetime points directly to each other. As such, objects entering one end of the portal would necessarily exit the other portal instantly, i.e. with exactly 0 transit time in between. According to General Relativity, if your portals can accelerate, this means that in certain frames of reference you can send a signal back in time. While a 50 meter maximum gap between apertures doesn't seem like much, this effectively allows for time travel up to around 16 microseconds into the past.
**Instantaneous Computing**
Combine multiple portals and technology (such as a computer that can perform hundreds of instructions in 16 microseconds) and you can essentially perform any computation instantly by setting up a feedback loop where each CPU performs some instructions and sends the results a short time into the past as the starting point for the next computation. At a minimum this would probably require at least two people working together (at least at the start).
**Creating Pocket Spaces and Universes**
Other answers have mentioned shields and invisibility, but with the right configuration of portals, you can actually effectively causally disconnect part of the universe from the rest of the universe. To make this disconnect you only need another portal to snap together across the aperture of this configuration. However, I'm not sure if this would be wise because, even assuming you found a way to reconnect this pocket space back to the universe, the instant it is causally disconnected from the rest of the universe it may undergo spontaneous [inflation](https://en.wikipedia.org/wiki/Inflation_(cosmology)) due to the absence of any quantum fields around its periphery.
**Automate the increasing power of portals**
Effort should be made to expand the limits of the portal. Not only to increase the maximum range and to decrease how small the portal can be, but also to increase the number of portals that can be simultaneously controlled, either individually or as a group. Creating a human-technology interface should be a high priority to automate tedious tasks such as collectively controlling a large number of portals. As this is a super-power if you can't train one person to manifest multiple portals you will be limited to the number of people who have this power, so it will be important to either find a way to increase this number, or - especially if you are hard capped at one portal per person - the speed at which the portal can be used. Since portals are mass-less moving them at the speed of light should cause no "doom" effects while still giving the practical appearance of a large number of portals. With enough computational power (see: Instantaneous Computing) and and two people with two portals working together, the ability to discard non-useful experiments (see: Time Travel) allows for experimentation with control over the portals so as to advance the effective power (or control over the portal) to near its physical limits within a reasonable amount of time.
**Filtration and Mining**
Micro portals can be used as filters. Since they can slice through molecules but not atom you can use these filters to mine for precious elements by setting the aperture size to allow only specific sized atoms to pass (with dual filters for instance first the first to allow only everything smaller than the radius past and the second to only allow everything just larger). As mentioned before, with fast enough automated portals we can also simulated multiple portals since what we are filtering isn't moving relativistically.
**Sensors**
Two automated micro portals moving at high speed can effectively sample various physical parameters across a specific volume, allowing for a reasonable model of that space to be assembled.
**Making a Consciousness Fail-safe**
With micro portals we can combine most of the features of a pocket universe in a practical way, if you don't mind shedding all your humanity and becoming one with the machine. At first, one's body would move into a pocket universe along with the interfacing machinery, with a sub-atomic sized portal specifically to allow a high speed information pathway in between the pocket universe and the outside universe. Outside the pocket would be receiving machinery acting as the user's avatar, sending sensory input through the portal and receiving commands from the portal instructing it what to do. In the event of this shell's destruction the user would be unharmed and could extrude a new shell as needed. However, over time the user would continually upgrade the internals to put the parts that could wear out outside in the shell until their consciousness remained, but their physical body had been completely replaced by pure computation.
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# Non-orientable portals
When you create a portal pair, the two circles appear "snapped" together. But there's two ways you could make the snapping happen such that things passing through the portals "teleport 0 distance". In the first, most obvious case, you could enter the portal going left, and exit the portal going left. In the second, less obvious case, when you enter the first portal going left, you exit the second portal going right. This second case is an example of a non-orientable wormhole. If this is possible, objects passing through this wormhole would swap chirality, which has some non-obvious consequences.
## Antimatter production
Most pertinently, in quantum physics, particles which switch chirality also negate their charge; ie. matter passing through the portal will become antimatter. So, if non-orientable wormholes (a case not explicitly covered by your rules) are possible, antimatter becomes very easy to produce.
# Intersecting portals
Under the rules as written, portals can overlap while coplanar. Nothing written prohibits portals from intersecting, however, which leads to some interesting applications. If this is possible, some interesting applications emerge:
## Finite closed surfaces
Imagine two parallel portals, like in the video game Portal. If you go down far enough, you pass through the bottom one and end up at the top. Now, imagine that there are three pairs of portals instead, so if you go left, you exit on the right, and if you go forward, you exit to the back. If the portals are big enough, and they intersect with each other, you've formed a closed surface. No matter which way you go, you'll be stuck inside this cube, and there's no path that exits this cube. Now, the actual minimum number of portals needed to do this is 4, if they formed a tetrahedron rather than a cube.
This has some useful applications.
### Compressing stuff
What if the portals move closer together? Then the closed volume will end up getting smaller, but there's no way for any matter to escape. This allows you to compress stuff inside this volume. You can easily compress gasses, liquids, solids, etc. High-pressure chemistry becomes easy. A couple people with portals and a bag of charcoal can make diamonds. A couple of people with portals an a bottle of water can compress the water so much that the hydrogen inside of it undergoes nuclear fusion.
### Containing stuff
If there's something dangerous, simply put it inside a closed volume and it can't escape while the portals are there. A bomb? A couple of portals later and the explosion is caught inside a space until everyone nearby is evacuated, and then the pressurized gasses and fast-moving shrapnel is slowly leaked out through a tiny hole at the bottom into a mound of sand. Since people's portals last after their death, a couple of people on their deathbeds could work together and store away a small volume of nuclear waste forever, for a nice inheritance for their next of kin.
# What if we didn't bend the rules?
## Optics
Portals can be used to redirect light with perfect efficiency, without chromatic aberration and the like. It can be used to change the polarization of light, too. So they can be used for anything that needs to precisely redirect light (like laser laboratories or microelectronics fabrication) or anything that needs to change the polarization of light (like laser laboratories, movie theaters, and microelectronics fabrication).
## Topological defects
A pair of portals can be used to make a solid ring that's 720° around, as opposed to 360° around. How is that useful? Dunno, but it's cool
## Precision
Human hands shake imperceptibly. If you have any of a litany of diseases, they also shake perceptibly. Portal control might have significantly more precision than human hands, so it's possible that precision work might be better done by using a couple of portals to hold things steady. This is useful in things that require precision work, such as mechanical watch making and making circuit boards.
## Particle accelerators
One of the limiting factors of powerful particle accelerators is that they need to be a circle. You need to move particles in a circle in order to add enough energy to them to do certain bits of science. But moving particles at relativistic speeds through a circular particle accelerator is also wasteful, because you need to redirect the particle so that it follows the circle rather than goes in a straight line. Furthermore, when you redirect the particle, it emits synchrotron radiation, losing energy. Using portals, this limitation can be removed and you can use a short straight particle accelerator and still accelerate particles to tremendous amounts of energy.
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## Use Your Portals to Make Your Attacks Unstoppable
Many methods of avoiding an enemy’s attacks in hand-to-hand combat relying on blocking or parrying the opponent’s weapon. So use your portals to make this impossible. An enemy’s shield is useless because you can move the exit portal behind their shield, and the entry portal in front of it. This would allow any weapon to travel straight through their shield. And this wouldn’t only apply to shields either. Got a pesky group of enemies hiding behind a rock or wall with bow and arrow, or crossbow? Position your portals around their cover, and open a hole wide open in their defenses. Pick them off one by one, while they’re exposed trying to reload. And you wouldn’t even have to move from your position. Assuming your “front end” “back end” language in your question means that these portals can be unidirectional, this would also mean that your enemies couldn’t fire at you through the portal either, so it essentially makes your portal configuration a shield that negates your enemies’ shield’s.
## Use Your Portals For Creating a Decoy and Confusing Enemies
Since your portals pretty much look ordinary with no defined edge except the view is whatever is in front of the entry portal, use these to create an image of yourself on both sides of your enemies position. Place the entry portal in front of you, and the exit portal in the other position where you want a decoy of yourself (or something else). Watch them panic trying to figure out which one is real, and (again assuming they can be unidirectional), stand in the open in complete safety as none of the projectiles they shoot at either can penetrate the portal (and if they shoot at the entry portal, their arrows will hit them from behind when they leave the exit portal). Take your time closing in on them for maximum scare factor.
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## Sanitation
No one is going to transport poo for miles any more. All manner of building regulations disappear, as pipes (for sewage or potable water) can just come out of a portal. In fact, if portals are strategically situated you need never use a normal toilet again.
Poo where you like, reach in and grab the paper, wipe, throw paper into portal, reach for specific spot in portal, wash hands, done.
## Sex
I don't 100% know which of the million and one perverted sex applications portals will be used for, but they will be used. Dicks poking through portals will feature. Multiple strippers can burst out of one cake. I actually hate all this degeneracy and have reservations about mentioning it but it *blatantly* will happen, and have huge societal effects.
## Contraceptives
Tangentially related to sex. Hard to get pregnant when semen is being sent straight to the ocean. Drunks still manage it somehow.
## Real estate - overlapping buildings
With some careful portal arrangement, you could have 10 or 20 houses all 'in the same spot', with portals for windows and doors. The possibilities for skyscrapers are endless; have the elevators go through portals to separate spaces that have window portals to other places.
## Real estate - megastructures, dynamic houses
You can now build buildings of basically infinite size in modular fashion. Why transport to see Aunty Doris when you can link your houses together for a week? Communes no longer form and collapse, they just wax and wane, ebb and flow.
## Fashion
Strategically placed portals allow for all manner of fashion dodges. Women with big feet now all fit into tiny shoes.
## Caesarian sections
Mum goes into portal. Baby goes into smaller portal 2mm in front of other portal.
## Cat videos
If you thought cat videos are funny now, wait until portals get involved!
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If your anchored-to-a-gateway-at-one-end-but-other-end-free-floating wormhole technology has the handwaved ability to match orientation and velocity to the surface of a distant planet, it also has the ability to *not* match the orientation and velocity of the surface of a distant planet, and if you configure it to be, say, facing downwards and descending vertically at 5km/s, then you have the delivery mechanism for a kinetic bombardment: launch a tungsten slug through the wormhole carefully timed to pass through just as the wormhole approaches the ground, then cut or divert the gateway so you don't get too much shrapnel back through on your side.
One downside to this is that while your wormhole-cannon is firing, it's scooping up a cylinder of the target planet's atmosphere and jetting it back out on your side at the impact velocity. While 5km/s wind in exchange for 5km/s tungsten slug is still an advantageous trade, what sort of damage might you expect such a wind to do on your side? What sort of protective measures would you want to put in place around your gateway buildings to prepare for this 'recoil'?
Assume the gateway is 10m diameter, probably outside on a large hardstanding area (airport runway style). I'm imagining launching the slug on a missile from some distance, since it needs to have enough momentum to travel 'upwind' to the gateway. Total firing time would be 5-10s.
*Edit: changed the impact velocity from 20km/s to 5km/s, to be within range of current hypervelocity weapons.*
[Answer]
**This is a [Frame Challenge](https://worldbuilding.meta.stackexchange.com/q/7097/40609)**
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**NOTE:** *This Challenge was written when the OP wanted 20 Km/s coming through the portal. Changing it to 5 km/s helps, but still... That's an 11,000 MPH wind coming out of a 10 meter diameter hole located at ground level. I believe my challenge still stands. I've seen what happens to the front of my business when 90 MPH wind hits it. I need only look at hurricane damage to see what 200 MPH winds can do. 11,000.... the destruction would be breathtaking.*
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I originally voted to close for needing more details because the background of the portal is irrelevant compared to the circumstances surrounding the source portal. What's happening to, e.g., the room that's experiencing 20 km/s wind?
Then I converted the wind speed to miles per hour. Sorry folks! I'm an American, and that means MPH means more to me than km/s.
## 44,739 miles per hour!
The Space Shuttle reenters the Earth's atmosphere at 17,500 mph. The fastest commercial bullet, the .220 Swift, was clocked at 3,180 mph.
1. I do not believe you can push the tungsten slug through the portal. Period.
2. I believe what's coming through the portal at the source end has more to do with hot plasma than atmosphere.
3. I believe with every passing moment your planet (the *whole planet*) is experiencing a climatological crisis.
And why do I say this?
* Unless the portal's controls are hundreds of km away, they (or the people pushing the proverbial button) are damaged and/or destroyed in the purported 5-10 second window.
* It helps if those controls are behind the portal, but not much (the more I think about it, not at all) because of the *vacuum* that will form behind the portal.
* If the controls are computer-operated, I don't believe it'll matter. The portal will likely destroy itself due to the heat generated by the passage of all that ~~plasma~~ air.
**Conclusion**
Maybe you need to rethink the 20 km/s number because unless I've converted it to MPH incorrectly (I'm lookin' at you, Google!), what you've really done is created a way for the attackers to destroy themselves.
**Alternatives...**
1. Move at a stately 20 km/h. Or even 200 km/h. At that point your wind is relatable to wind tunnel velocities and you need only describe your launch point as being inside the proverbial cold-war era wind tunnel facility to justify/rationalize everything else.
2. Put the launch point in space. Better still, but the terminus in space, too. That way there's a vacuum on both sides and the launch would be whomping hard for your enemy to detect. If you're using the velocity of the terminus to rationalize the velocity of the slug, then you can move it as fast as you want in space. Put it 10,000 km ahead of the target planet's orbit and release the slug at 20 km/s. Based on Daron's answer, it would hit the ground at 50 km/s.
[Answer]
# Bright
I suspect the air will not come out the other side at 20 km/s. Much will be converted to heat and the portal will look like a fireball or miniature sun. Or maybe a cone of flame.
[The fluid is choked](https://en.wikipedia.org/wiki/Choked_flow) by the small portal size. See the diagram.
[](https://i.stack.imgur.com/K1Mo6.png)
The neck of the pipe where it thins represents your wormhole. The red particle and blue particle are moving fast to the right. When they move into the neck, the red particle moves down and the blue one moves up. They collide with each other and with the sides of the pipe. Some of the kinetic energy is converted to heat energy.
Since the portal is so very small and the air starts out so fast, you will get a lot of heat. This can be calculated using the equation:
[](https://i.stack.imgur.com/3sMYu.png)
which I believe gives an upper limit to the speed the air comes through the portal. Increase the speed on the left of the neck any more and the speed on the right stays the same, but the temperature increases.
If the equation looks scary to you, do not worry. It looks scary to me too. You might want to look at answers to [similar questions where people work through the equation.](https://worldbuilding.stackexchange.com/search?q=%22choked+flow%22)
---
The way I would use the weapon, is put the exit portal on the enemy planet. Point it at the ground. Wait until the planet rotates so the portal is at the "front" of the planet. Remember the Earth orbits at about 30km/s. That means anything dropped in your fixed portal hits the planet at 30km/s. Kaboom.
[Answer]
## Short, compressed and too fast
Assuming the receiving end of the wormhole comes down at the planet at 20 km/s and the mass that has been transferred via wormhole to retain the velocity relative to the wormhole's other end, you pretty much get a stream of air at normal pressure flying out of the local end of wormhole at 20 km/s. Just the wind, you know. Yet, given that the atmospheric pressure at 100 km height is very small, you will only experience significant wind for the last 5 seconds before the wormhole would cross the ground level. After that, you'll get slammed by a wormhole wide stream of planet matter flying at 20 km/s, potentially eliminating whatever is powering your wormhole with its sheer speed and kinetic energy.
This, however, depends on whether the local end of your wormhole is somewhere at the ground level, with its own local pressure and air. If it would be in vacuum, you would only get a narrow tube of planet matter flying from there at 20 km/s, no matter what kind, wind or rock. If it's not in a vacuum, you'll first experience a suction towards the wormhole as it would be opened into space, then as the wormhole would approach the planet you'll receive a stream of particles coming your way, some of them originating from this side, then your room's air would be rapidly compressed by the incoming 20 km/s air flow which density would increase exponentially over about five seconds, and if you'll not cut the connection, welcome rock train.
**If you want to bomb someone with such a wormhole, you should not intersect with the planet**
You just position your wormhole's distant end some millions of kilometers away from the surface, facing the planet and located forwards orbit wise, with its speed relative to the *star* at 20 km/s backwards (retrograde, relative to the planet's orbit). Then throw there an iron orb that'll barely fit into the wormhole - no need to use tungsten as iron is a hundred times less expensive and only three times as light. Then another if you want, or plain feed there a literal train of them. When at the ditant side, the orbs will have a relative speed of 20 km/s plus the speed of the planet relative to the star, and you would have enough time to collapse the wormhole before the intrusion would be noticed. Of course you position it so that when your meteorites collide with the planet's surface, the desired target would be hit.
[Answer]
>
> One downside to this is that while your wormhole-cannon
> is firing, it's scooping up a cylinder of the target
> planet's atmosphere and jetting it back out on your side
> at the impact velocity.
>
>
>
That would be true if the wormhole started out, say, near the edge of the atmosphere and rocketed towards the surface at speed. Why would you operate the system like that, though? Open the wormhole about 3m above the ground, move it towards the ground at speed, then cut it off after it moved a total of 20cm. For a 10m wide portal, that'll only suck in about 1.5 cubic meters of air, which shouldn't be a huge problem. The portal will only be open for a tiny fraction of a second so timing would be tricky, but that's a solveable problem.
>
> What sort of protective measures would you want to put in
> place around your gateway buildings to prepare for this 'recoil'?
>
>
>
If you're planning on operating your wormhole in this manner, you wouldn't put anything in "front" of it to begin with. You'd point the business end towards the largest expanse of *nothing* that you can find and have all your buildings and equipment safely sheltered at a distance "behind" it. After all, the thing is two-way. If your tungsten slug is leaving the portal at 20 km/s, then the pine tree the portal is accidentally landing on is emerging from *your* side at 20 km/s.
Overall, though, the answer will rely on how exactly you're planning on handwaving away the ability to have a moving exit portal. Conservation of energy still applies when wormholes are involved. Your projectile is gaining a tremendous amount of kinetic energy, but that energy has to come from *somewhere*. If you're having to input that energy into the system, then it seems easier to use that energy for destruction directly and leave the wormhole stationary. Or, drop your side of the portal into the nearest star and use the steerable exit portal as the universe's greatest flamethrower.
] |
[Question]
[
In my world, there is a virus that causes acquired degreasing body syndrome (also known as ADBS) (sorry, the original French name of this disease is *syndrome de dégraissage corporel acquis*) (the original language of my story is my native French).
The laconic of this infectious disease is a progressive contagious adipocyte degeneration. It is transmitted by all body fluids (vaginal secretions, sperm, mother-to-child, milk, blood, saliva, vomit, urine, and tears). This disease does not directly kill, however, because people who have it become gaunt, they have an EXTREMELY high risk of the following diseases: both female infertility caused by low oestrogen (amenorrhea) and male infertility caused by a lack of nutriments to make viable spermatozoa, osteoporosis, both myocardial infarction and stroke caused by anaemia, both hypotension (low blood pressure) and cardiac arrythmia (irregular heart beat), and amyotrophic lateral sclerosis (all those causes of death are more common in underweight people).
The virus that causes this pandemic is a retrovirus from the *Betaretrovirus* genus (to be exact, its direct ancestor is the mouse mammary tumor virus).
So, I wonder if this disease could possibly exist.
[Answer]
## Acquired lipodystrophy is real.
[Lipodystrophy Syndromes: Presentation and Treatment](https://www.ncbi.nlm.nih.gov/books/NBK513130/)
Linked book with much reading and images. In these diseases there is an attack on adipocytes and then various derangements of their function. The gaunt version you describe can happen with HIV; it is not clear if it is an effect of the infection or modern treatments. It can certainly happen as an aftereffect of an infection and so probably an autoimmune disease (like juvenile diabetes) and it can happen in the context of a serious autoimmune disease like lupus.
For whatever reason diabetes accompanies lipodystrophy and poorly controlled diabetes by itself can cause all the of bad things you want for your fictional disease, as can HIV and autoimmune disease.
Lipodystrophy can also cause a person to appear preternaturally ripped because there is no subcutaneous fat to conceal the muscles and there is nothing wrong with the muscles. When I contract this disease in your story that is the version I am going to get, and I am going to win body building competitions but never work out. My gold lamé Speedo helps.
[Answer]
@Willk has come up with what's probably the best answer you're going to get. But if you're willing to go out on a limb (and you aren't too attached to a retrovirus), I thought we could have some fun with this.
**Your virus is a mutated form of Covid**
SARS-CoV-2 is not a retrovirus. It's actually a coronavirus (surprise, surprise), but it shares similarities with a retrovirus in that they both contain positive-sense, single-stranded RNA. In some ways, coronaviruses may be quicker-acting than retroviruses because they contain RNA-dependent RNA polymerase, meaning they can copy RNA into RNA, versus retroviruses which have reverse transcriptase, meaning they must invade the host cell's genome, overtake its machinery, and convert their RNA into DNA.
It might be a stretch to suggest that SARS-CoV-2 could cause progressive adipocyte degeneration, but research shows that it often infect adipose cells, explaining why people with obesity are primary targets (more fat cells to infect) and why weight loss in Covid is so common (adipocyte degeneration).
[Stanford Medicine study: SARS-CoV-2 infects fat tissue](https://med.stanford.edu/news/all-news/2022/09/stanford-medicine-study--sars-cov-2-infects-fat-tissue--creates-.html)
>
> SARS-CoV-2, the virus that causes COVID-19, can directly infect adipose tissue (which most of us refer to as just plain “fat”). That, in turn, cooks up a cycle of viral replication within resident fat cells, or adipocytes, and causes pronounced inflammation in immune cells that hang out in fat tissue.
>
>
>
Also see [this study](https://www.nature.com/articles/s41467-022-33218-8#:%7E:text=Recent%20studies%20have%20shown%20that,%2C10%2C11%2C12.), which explains the mechanisms by which SARS-CoV-2 infects adipocytes.
What's more, Covid has all the badness you could ask for. Contagion? Covid spreads through many mechanisms, and the virus has been found in feces, saliva, semen, and tears. Side effects? People who've had Covid are at risk for a whole slew of disease, including many of the disease you name. I'm including some headlines/links below, but really, the list is endless.
[SARS-CoV2 in Different Body Fluids, Risks of Transmission, and Preventing COVID-19](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7518359/#:%7E:text=Recent%20studies%20indicate%20viral%20particles,of%20these%20routes%20as%20well.)
>
> Recent studies indicate viral particles can be isolated from many body fluids including feces, saliva, semen, and tears, suggesting transmission could be possibly occurring through some of these routes as well.
>
>
>
[Serious Illness From Covid Linked To Infertility Risks](https://khn.org/morning-breakout/serious-illness-from-covid-linked-to-infertility-risks/)
>
> “There is evidence to suggest that infection with SARS-CoV-2 has the potential to impact both male fertility, female fertility, and certainly the health of a pregnancy of someone infected"
>
>
>
[IU researchers study long-term effects of COVID-19 on bone growth](https://medicine.iu.edu/blogs/research-updates/iu-researchers-study-long-term-effects-of-covid-19-on-bone-growth)
>
> Researchers in the Department of Orthopaedic Surgery at Indiana University School of Medicine discovered that mouse models infected with the novel coronavirus lost approximately 25% of their bone mass within two weeks of contagion.
>
>
>
[Cardiac Manifestations Of Coronavirus](https://www.ncbi.nlm.nih.gov/books/NBK556152/)
>
> COVID-19 has been found to interact with and affect the cardiovascular system leading to myocardial damage and cardiac and endothelial dysfunction.
>
>
>
[Acute Ischemic Stroke and COVID-19](https://www.ahajournals.org/doi/full/10.1161/STROKEAHA.120.031786)
>
> Coronavirus disease 2019 (COVID-19) may increase the risk of acute ischemic stroke similar to the increased risk of 3.2-fold to 7.8-fold seen within the first 3 days after other respiratory tract infections.
>
>
>
I stopped after infertility, osteoporosis, cardiac complications, and stroke, but the list continues. Google "Covid-19" in conjunction with *any* disease on your list to read about potential complications.
The great part about this? Because Sars-CoV-2 is still so new, there is much that is yet unknown, so you can reasonably suggest any side effects or methods of contagion. Enter SARS-CoV-3.
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[Question]
[
In my world, there is an entire nomad-based society. While they have some influence based on gypsies, they are mainly based on Mongolian Horsemen. At some point in my fictional history (ca. 12th-13th centuries in our time), they eventually form their own major kingdom. However, despite creating formal cities an towns, they still continue to have their nomadic ways, not always staying in one place. Even though they are like this, how could a civilization that is nomad-based continue staying stable and structured?
For the notes:
* While they move around a lot, they also use this to guard their territories and lands, and keeping their military mobile
* Some "villages" are just nomadic groups that move around, creating temporary structures and mainly living in wagons/carriages like gypsies
* Their main food is livestock, and being a rancher is a huge industry there
* Some of their "cities" are giant groups of travelers
* Geographically, the kingdom is in a huge, wide valley
* Some permanent structures include tradeposts and military fortresses near the borders
[Answer]
Have a central location where [they have slaves build a city to centralize it all.](https://www.haaretz.com/archaeology/2021-11-04/ty-article/archaeologists-find-lost-capital-of-the-mongols-and-it-was-big/0000017f-dc19-d3a5-af7f-febfa4ef0000)
This is what the Mongols did. They brought in their experts and slaves and made Karakorum. The Khan lived in it for a few weeks of the year, and all the loot and information of the empire went there.
You can also follow Genghis Khan's rulership ideas.
1. Have a culture that encourages promotion based off ability, not blood ties. Blood tie promotions means a fractured tribal culture which is pretty ineffective.
2. Give armies a lot of freedom and don't micromanage. He gave commanders a lot of freedom to accomplish their goals, and forbid looting till the battle was over, forcing them to defeat their enemies quickly. This led to inspired commanders winning many battles.
3. Support religious tolerance. Your leaders should study the common religions in their area so that they can offer respect to them. Offer freedom from taxes to key religious figures. Religion can easily serve as rallying point against a society which seeks to destroy it, and religious tolerance keeps your society stable.
4. Rely heavily on psychological warfare. They would generally let their enemies keep their cities, so long as they paid tribute to the horde, and they would slaughter entire cities which resisted them. They had the stick and the carrot, and were very fair.
5. Maintain spy networks. When moving a lot and ruling over a vast area you need to know what's going on. Establish horse networks to carry news, and informants in every area you want to do stuff in. Intelligence is often the best way to ensure you can win when you stay mobile, and to be aware of any rebellion.
[Answer]
Being stable and structured doesn't require being immobile. Our real world nomadic societies, without having unmovable structures are nevertheless stable and structured.
What the society needs is traditions and costumes which allow it to thrive and be well adapted to the environment where those take place. If fixed buildings are a burden, there is little sense in having them.
[Answer]
A few ideas:
**There is a thriving trade of messengers**. The only big issue I see with this is it is difficult to know where to go to do business. For instance, a rancher needs to drive their livestock to a big market. Therefore, there has to be a class of messengers who crisscross the lands constantly, trading information with each other about where large gatherings are and how they are moving. If there are enough of them then a trader won't be more than a day out of touch, and finding large gatherings shouldn't be an issue.
**Settlements are permanent, residents are not**. On the other hand, one reason that cities are where they are is because of advantageous geography. It simply makes sense for a city to arise at a particular place because it has (water, good land, central location...) However, there is absolutely no requirement for that city to be built of permanent structures or have permanent residents. Therefore, the location of the city is always the same, ish, but it's more like a giant camp with defined areas for doing certain things rather than a built up area with permanent structures.
You'd still need tons of messengers to make the second option work, though, or you cannot have a central leader.
[Answer]
You could base the culture in a steep-sided valley. The Swiss farmers have high summer pastures and low winter pastures [Alpine Transhumance](https://en.wikipedia.org/wiki/Alpine_transhumance). Many of the families that farm this way have done so since the Middle Ages. This sort of farming avoids the Tragedy of the Commons only if there is a lot of trust between neighbours. Perhaps being in a valley means you have two neighbours up and down the valley rather than six on a hexagonally tiled plain.
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