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[Question]
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> When the skies release a column of fire, the land around becomes a
> barren place...
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Can such phenomenon be explained with some rare, but "closely possible" circumstances? I don't think about lightnings/meteors here, rather about something lasting a bit longer (at least some hours).
I thought about several things like a combustion of stacked flammable gas pushed out by pressure changes or describing an abnormal activity related to higher parts of the atmosphere, but all that still sounds too abstract to me.
Of course there is no need to take the sky part literally, it'd just look alike.
I don't mind including some magic if it's necessary, but you know, it's all about not making things too boring. :P
[Answer]
**Xzenbob set the laser transmitter power too high when sending a message towards Earth.**
The message was a simple one, a message of peace, but Xzenbob was not a skilled technician. When Xzenbob set the power level for the laser communication system, it should have been set to interstellar, but it was set for *intergalactic*. When the message finally arrived on Earth it vaporized the atmosphere in a wide column stretching down from space. The shear amount of data and the repetition that was included made the transmission last for hours.
*Alternatively, instead of communication this laser shot could be an errant mining laser pulse or a badly aimed laser burst from a distance space battle.*
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There are two real ways this could happen - the first is an asteroid strike which would have lingering affects even though the initial impact was quick.
The second would be some sort of large release of buried gas (for example there are massive quantities of methane and other dangerous gasses trapped in our continental shelves). That methane if it were released would be bad for anything that needed to breathe, and also highly flammable and possibly even explosive.
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We may never know how such a complicated compound formed in the depths of space, but there is no denying that it happened. No one who survived the fire rain will ever question that.
It took months for the scientists to discover the cause, but eventually it was proven. Earth's orbit had intersected a space-born river of asteroids, millions of golfball sized rocks, each composed of a substance, very much like thermite. They streamed down upon us for hours. Igniting as they fell, from the atmospheric friction and each other's conflagation.
We screamed, and ran, and burned.
When it was over, our once fertile fields were a plan of volcanic glass. From horizon to horizon, our once beautiful land had become a scorched, lifeless wasteland.
We shall never forget the night that the fire fell from the sky.
[Answer]
# Fire whirl
Of course it's possible, it even exists and is [caught on tape](https://www.youtube.com/watch?v=lsyvOYcWgcg).
[](https://i.stack.imgur.com/YaHuH.jpg)
From [wikipedia](https://en.wikipedia.org/wiki/Fire_whirl):
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> They usually start with a whirl of wind or smoke, and may occur when intense rising heat and turbulent wind conditions combine to form whirling eddies of air. These eddies can contract into a tornado-like vortex that sucks in burning debris and combustible gases.
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They don't come from the sky, as stated in a comment, but you said in your question that it should just look similar. So that's what you're looking for.
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A volcano comes to mind immediately. Ever seen photos from [Mount Pinatubo](https://en.wikipedia.org/wiki/Mount_Pinatubo)?
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**Yes, assuming you magic up the right substance.**
The substance needs a few properties. It needs to evaporate to gas and condense back to liquid roughly at the same temperatures as water, and it need to be flammable and burn slowly only when in liquid form, not as a gas. In large enough quantities so that it can form clouds in the skies.
When there is a thunderstorm, the lightning will ignite the raindrops. Due to burning slowly, will appear as the sky releasing a column of fire, and the land below become a barren place.
Depending on your needs it can be a one time event consuming majority of the substance, or a regular occurrence as the liquid otherwise doesn't interfere much with the environment. High ignition temperature would prevent random infernos after rain, as only lightning ignite it naturally.
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Suppose there's a vault secured with a numeric code and a biometric sensor. What technologies and methods could be used to open the vault if a character isn't registered on the system?
Here are a few biometric systems I'd be interested in seeing solutions to bypassing and some ideas I have already considered, though don't know if they're viable.
*Finger-/handprint sensor -- A device that reads one or more fingerprints or the entire hand, requiring a 97% or better match to unlock.*
* Cut off the hand of a valid user (seems rather violent and not
feasible for a burglar)
* Place a sheet of material (graphene?) on the sensor thin enough to not be noticed and thick enough to record the finger-/handprint of a valid user
*Genetic sensor -- A device that retrieves a fresh sample of DNA from a user, requiring a 97% or better match to unlock*
* Retrieve a sample of a valid user's DNA from a third party (Red Cross looking for blood donors!) and construct a fake hand from pig flesh
*Iris sensor -- A device that examines a user's eye, requiring a 97% or better match to unlock*
* Rip the eye out of a valid user's head (again, infeasible for a burglar)
* Construct a device that mimics the pattern of a valid user's eye (though I don't know how to go about getting the pattern)
*Face sensor -- A device that performs facial recognition, requiring a 97% or better match to unlock*
* Use a 3D printer to create a foam replica from pictures of a valid user
These are just some of the biometric sensors I can think of. Answers to this question should be limited to bypassing the biometric portion of the vault security without resorting to drills and other vault penetration tools (or removing the power source) and should result in a minimum of proof of a burglar's presence. If there are other biometric systems you can think of, feel free to share them and a possible way to bypass them.
[Answer]
The three main biometric authentication technologies are fingerprint, iris, and face recognition. DNA-based identification is generally too slow to act as an identification token, requiring hours to process. However, I'll go through all four.
I'm going to assume that this is your standard cat-burglar/heist scenario, where the ultra-paranoid target is the only one with access, but any technique can be used to defeat the system. Cases like gaining access to a high-security facility are more difficult, since you are limited to methods that won't alert watching security personnel, and you may also be required to disguise yourself.
* Fingerprint recognition is ~~trivial~~ relatively easy to defeat. For example, it is already possible to fool Apple's TouchID using nothing more than an image of the authenticated user's fingerprint (and their fingerprints are generally all over the phone's glass!). In [this video](https://www.youtube.com/watch?v=2u4ZLGsw1zo) I watched recently, some guys manage successful authentication of a fake fingerprint on their first attempt (although they make a mold from the finger directly). With slightly better techniques, it is possible to create a detailed mold from an image of the fingerprint (that is, the mark left by the finger, not the actual finger itself), and make a fake fingerprint that way. You only need to acquire an image of the target's fingerprint (how exactly I'll leave up to you). Note that their specific technique (using graphite-impregnated silicone rubber) is only required for the iPhone's capacitive fingerprint sensor. For your more typical image-based sensor you only need a shape-accurate mold.
* Modern iris recognition typically works by taking an image of the iris in visible or near-infrared light and comparing it to a database. (Some implement additional live-tissue verification by changing illumination conditions to test whether the pupil contracts and dilates, but this is not typical.) A typical system could be fooled by presenting it with a high-resolution image (scaled 1:1) of the target's eye. Actually creating the image is not a problem: I've gotten very good images of my own eyes with Nikon's base-level DSLR (D3300) and cheapest macro lens (f/2.8 40 mm MICRO-NIKKOR) (the only difficulty was not being able to see the camera while lining up the shot!). The problems are in printing the image with the requisite resolution (a photographic reduction on either film or photographic paper should work), and actually getting access to your target's eye. (You might have to *c-a-r-e-f-u-l-l-y* open his/her eyes while they're sleeping, perhaps after slipping them a sedative.)
* Face recognition could conceivably be fooled using modern technology to create a face-mask. In [Mission: Impossible III](https://en.wikipedia.org/wiki/Mission:_Impossible_III) (starting at around 47 minutes in, if you happen to own the film) the heroes take several images of their target's face, using them to create a 3d model, which is then turned into a physical mask. Again, I've had success with such a technique: using an [online service](http://www.123dapp.com/catch) to make a 3d model out of images of my own face (still frames from a video of me turning slowly on an office chair), and then 3d-printing the model in plastic (albeit at a reduced size). With access to the proper software and a large-format, high quality 3d printer, you could definitely recreate someone's face from photographs. Of course, you could always just [show one of the pictures](http://techcrunch.com/2011/11/11/android-facial-unlock-photo/) to the camera, it would probably work.
+ Side note: in the same sequence from M:i:III, the heroes use a magic voice-changer sticker on the throat (under the facemask) to [imitate the target's voice](https://www.youtube.com/watch?v=CgX4uJSj00Y). While the depicted technology is probably not realistic, you could probably fool a voice-recognition system with a high-fidelity recording. Pose as a reporter and interview your target, in the process asking his/her name. (If the lock requires a voice password, you'll have to figure out what it is and reconstruct it from numerous audio clips.)
* Since DNA identification is not done in real life, I won't spend a lot of thought on this. However, you might look to the movie Gattaca for inspiration. The hero uses several methods to fool the movie's omnipresent DNA scanners, including blood-filled false fingertips for , and at one point secretly injecting himself with blood while a sample is being drawn (it's a great movie, but at times can be a little uncomfortable to watch for someone as squeamish as me). [This clip](https://www.youtube.com/watch?v=Ou3j3CGcPPo) shows some others methods. However, these all require a cooperative target who can give as much material as necessary. Your Red Cross idea is a good one, but your target may not give blood, like me (did I mention I was squeamish?). DNA can also be harvested from saliva, hair follicles, skin cells and [other sources](https://en.wikipedia.org/wiki/Touch_DNA), so you might just need to dig through their trash. And if you target is male and the promiscuous type, you may be able to acquire some of their, uh, "genetic material."
Finally, note that (depending on your definition of "biometric") there may be some credentials that are not possible to duplicate. See [this very cool paper](https://www.usenix.org/conference/usenixsecurity12/technical-sessions/presentation/bojinov), which describes how a "password" consisting of a learned task (playing certain sequences of notes in Guitar Hero), subconsciously trained into a user, cannot be consciously or unconsciously disclosed by the user (meaning that it is impossible to communicate your credential to someone else, even if you want to). The system used by the researchers is impractical, but in the far future uncopyable passwords may be possible.
I wish your characters the best of luck!
[Answer]
There's another option: Go around the biometrics.
At some point, there's going to be a computer making a decision, then sending out a voltage or message to a device that activates/deactivates a solenoid/motor/electromagnet/whatever the actual locking mechanism is.
Someone skilled enough with electronics or software might well be able to bypass the biometric aspect entirely. You'd have to watch out for tamperproofing when you opened things up, but it mitght be possible to attack the system in a variety of ways.
Examples of attacks of this nature I can think of:
* Directly applying/removing voltage to the locking device
* Replacing the chip containing the firmware/storage containing the
software with some of your own. (Or equally just the storage that
remembers who is supposed to be let in) Directly injecting the
trigger signal (be it a simple voltage on a bus/wire, or a key
message
* Replacing the detector with a dummy that provides whatever the
software is expecting
* Discovering a bug (or deliberate back door added by
developer/intelligence agencies) that causes the software to respond
in an unintended way to a specific input and open the door If the
lock is networked (seems foolish, but it there is a central security
office that tracks these things, not impossible) attack it through
the network
* At some point, the biometrics of the persons who are authorised
access have to be loaded on to the device. This gives you several
routes of attack to get you, the burglar, added to it. If it's done
via a network, you can try to update this directly given you get
access to the target's network. If it's done via a physical file
transfer, you can try to get your biometrics on to the file system,
then create a reason/wait for the regular update. If details are
loaded by directly interacting with the lock, then you can try and
gain access to the ability to do so - it's likley a passcode or
something that an administrator would have. There's probably also a
way for service engineers of the manufactorer to reset things in the
event that a customer loses access.
[Answer]
Finger-/handprint sensor :
[Mythbusters](http://www.discovery.com/tv-shows/mythbusters/mythbusters-database/fingerprint-scanners-unbeatable/) did a test on this type of lock. They lifted a fingerprint from getting the target to burn a CD. Then did some processing (filling in missing lines).
Then to get through the lock they printed it on paper, put a little moisture on it and then they were able to use it on their own finger.
SIMPLE ANSWER:
you just need paper and moisture to fool the sensor.
[Answer]
Since 2012rcampion does a good job (IMHO) covering the biometric side, I'll remind you not to overlook the obvious weaknesses not directly related to biometrics. These could still be used to break biometric security.
**Back end**
In a biometric system the data the biometrics is compared to is in a database as are the access rights the recognized user will get. The security of a biometric system can't be better than the security of that back-end. And the back-end needs access for administration, maintenance, and backups. And while those would presumably have high security levels it might be lower than for a vault or area a burglar tries to get in.
Hacking the administration would allow adding a new user you can match, adding access rights to user you can match, or changing biometric data of an existing user. Ability to perform a maintenance update might allow adding a back door that makes all locks open to a scan test device. Such test mode might already exist in the code and be available for use by editing some settings. The system might in general have testing, debug, or maintenance modes available.
Access to a backup, which presumably would be stored off-site, and thus might have lower security or need a data transfer that can be intercepted, might give you access to all the data you need to fool the biometrics. Presumably the biometric data would be securely hashed to prevent this, but the hashing function used might have a known flaw. Since performing updates might itself be a security risk, old code might live for a long time. And **old** backups might still be available with even lower security. And the biometric data would still be valid. Reminding users that the security system has been updated and they should change their DNA doesn't really work... Neither does telling people to use different DNA on different systems, so you can compromise an entirely different lower security system and have access to biometrics valid on a high security site.
**People**
Make somebody who has access do what you want. Realistically this would be used to bribe a systems administrator or head of security to tamper with the database. But if you have the bank managers family at a secure location with nasty people with knives, you can have access to anything the manager has access to. The same goes for the actual owner of the thing you are trying to steal, if it has one.
I doubt these examples are of direct use to you, but the general concept of dealing with a secure system by committing other crimes to make it less secure is a long tradition in fiction and should not be ignored.
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## Social Engineering
eg: Most people don't think up new passwords. They reuse their old passwords, and every website thinks they should require people to get their own account (or uses a service, which just means the service is a bigger target, and not under the website's control).
Boom, lots of stolen passwords, every site needs to have good security, etc, etc.
So, you tell your target that if they want to use the new iPhone/cool-thing$^t$$^m$} they need to give up their biometric data, then you have access to that, for nearly as long as you can keep data around (biometric data *can* change over time, but it takes a long time).
Now that you're evil Apple, you've got 100s of millions of people's biometric data, and you can sell that to anyone who wants it. Mmm, profits. You can wait for those kids to grow up and get security jobs. Basically the same plan as cops fingerprinting children in school ("for the safety of the *children*!!").
Just go to Apple (or your shell company), and buy/harvest your target's data, then go and use it.
[Answer]
Go to you tube and search for the lock picking lawyer.
He has a hobby of "picking" and bypassing locks of all types.
His answer for most biometric locks is a powerful magnet. Such locks use a solenoid to retract the locking mechanism. A powerful magnet placed beside the lock will pull back the mechanism without having to energize the solenoid.
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I am building a habitable, Earth like planet, but instead of it being in a solar system, it is inside a Nebula.
The actual composition of the Nebula is uncertain at this point, but I am considering something like the Orion Nebula.
Imagine if there was a vast cloud of gases, similar in composition to the gases that make up our atmosphere, that covered the Earth and the Moon and everything in between.
Would this make traveling to the Moon easier?
Could modified Balloons and Dirigibles be used for short range space flight? If gases lighter than the gases of the nebula were used inside Balloons, in what direction would they "rise"?
Would the nebula open up new forms of space transport? Could the clouds and dust be used as propulsion, or at the very least, something to push against in space?
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Unfortunately the gas inside the nebula is far too spread out to be useful for things like balloons to work. The density of nebula is discussed here:
<https://physics.stackexchange.com/questions/26326/how-dense-are-nebulae>
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> They are very sparse. Typical densities are in the range of 100 to 10,000 particles per cm3.
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> This is much more dense than the general interstellar medium (1 particle per cm3), but much, much less dense than anything you are used to - air is around 10^19 particles per cm3.
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(So our atmosphere has 10 000 000 000 000 000 000 particles per cubic centimeter)
This means that the nebula is a lot lower density than atmosphere and things like balloons would not work at all. However it is still much denser than in normal space so you would get a small amount of resistance to movement and in theory some sort of ramscoop arrangement might be able to gather in the material at the front of the craft and then fire it out the back for propulsion.
You should also be aware that stars (especially the solar wind coming out from them) tends to blow the gas of the nebula away from solar systems too. Around the inner solar system in particular there would be very little nebula left.
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Traveling to the 'Moon' would be harder, at least the way we did it. The nebula would drag on the space ship and you'd need to bring more fuel to counter that loss of speed.
Also the moon would experience drag and either scoop up it's orbit and leave a nebula-free ring or be dragged enough to loose speed and spiral into an ever lower orbit. (Which, at least, making traveling to the moon very easy if yo wait long enough ;)
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I am making a setting for a various TTRPGs that me and my friends want to play.
I want this world to have longer seasons than earth. I was thinking about 3-4 earth years each season.
This is difficult, as I know this would not work with our current solar system. I know that as you get further out from the sun, orbits generally get longer. But, the goldilocks zone for our sun does not reach out to the zone that this long orbit would be possible. So, what kind of star would this planet need to be orbiting in order to not end up freezing, but still have long seasons.
As I have it now, it orbits a red giant at about the distance Jupiter is from our sun. But I am unsure of if this is realistic AT ALL. My planet is a little bit bigger than earth (1.2) if that makes a difference.
I am willing to do math to figure all of this stuff out, but I have no idea where to start.
[Answer]
## Red giants are not as good of candidates for life as you may think
They tend to be much less stable than main sequence stars because thier shells go through a cycle of periodic collapses resulting in nova that would each wipe out all life in the would be Goldilocks zone. Also, stars spend about 10 times as long as main sequence stars as they do as Red Giants.
## You might sort of be able to make a main sequence star work better
As the mass of a main sequence star increases (forcing more distant orbits to be a bit faster), its luminosity increases exponentially meaning the goldilocks zone expands out farther from a star in proportion to mass much fast than orbital speeds accelerate.
To get an Earth like 3-4 year season, you need an orbital distance of about 5-7 AU orbiting a main sequence star about 1.9-2.0 times the mass of our sun in order to get this planet in the middle of the Goldilocks zone. Such a star would be about 15-30 times as bright as our sun despite only being about twice its mass.
At this mass you are looking at a type A star just a bit smaller and dimer than Sirius which would appear white or ever so slightly blue compared to our own sun which is in the yellow range, but keep in mind that not only do more massive stars become exponentially brighter, they also become exponentially shorter lived. This star would only have a total life span of a few hundred million years; so, you world would likely not have time for life to evolve. If it is inhabited, all life likely came from another world.
## But you can do even better by playing with atmospheric gasses
While a type A star star is not bad, you could probably get away with a heavy type F main sequence star (yellow-white dwarf). At 1.5-1.6 solar masses, you could still get about 1/2 as much sunlight as the Earth receives at an acceptable orbital distance. While Earth is mostly made of iron, oxygen, and silicon, some exoplanets have been observed with far more carbon in place of silicon which could result in more CO2 and less Ozone in the atmosphere increasing the greenhouse effect when all other factors are comparable.
In this case you could have a star that is stable for about 2 billion years... maybe not long enough to see complex life evolve if it follows the same timescale as Earth did, but close enough to say that complex life could maybe evolve there before the star dies.
The higher levels of carbon could also be a good excuse for a world with more mega fauna which is good for a fantasy setting.
As for what the world would be like, it would barely be distinguishable from Earth in most ways. The sun would be a bit more white than yellow, and the sky would be a slightly deeper blue. Diamonds would be as common as quartz and vise versa. UV radiation will be a bit more harsh, but by in large, the differences could be negligible, especially if the local life is adapted to this environment.
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Easiest thing I can imagine would be to give the planet an accelerated [axial precession](https://en.wikipedia.org/wiki/Axial_precession) around a stable main seq host star. The wobbling top equivalent of the planet's axis. When the north pole points away from the sun it's winter in the northern hemisphere.
On earth the procession is geologically slow, ~26,000 years. And are related to [Milankovitch cycles](https://en.wikipedia.org/wiki/Milankovitch_cycles) / Ice ages and other cyclic climatological events. If however the procession was fast enough to keep the pole pointed away it's star even as it orbited, you could choose how long you wished your winters to be.
This is a deep rabbit hole if you want to "keep it real" for a fast procession like this, I think it would call for the absence of any moon of substantial size, among other things.
Note: Happy to be fact checked on this. How stable/unstable a wobbly planet like this would be. Perhaps it would have to have been smacked by another body pretty hard in the geologically recent past to evolve this. I'm in no way able to math out an orbital system no matter how big of a chalkboard you give me.
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We have some boundaries to satisfy.
First, there is a relationship between the mass of the Sun and the orbital period of the planet. That is given by Kepler's Third Law, and we can write,
T=SQRT(4*PI^2*D^3/(G\*M))
so, if we want a T of about sixteen times that of Earth, we need to increase (D^3/M) by a factor of 256 with respect to the Solar System. Either we place the planet farther from the sun, or we make the sun smaller.
In either case the planet will be *way* colder.
But we can do *both* at once. We can increase the sun mass and increase the distance even more. If we double the sun mass, X^3/2 = 256 yields X^3 = 512, so X=8, which means we need to place the planet eight astronomical units away from the sun.
This means that it will get 1/(8\*8) = 64 times less light and heat than the Earth. *Is* a star twice as big as the Sun also sixty-four times brighter?
For main-sequence stars there is a proportionality law due to [Jakob K. E. Halm](https://en.wikipedia.org/wiki/Mass%E2%80%93luminosity_relation) that states that the increase in the star's luminosity is proportional to the increase in mass, multiplied by 1.4 and raised to the power of approximately 3.5 (for the interval of interest to us).
So a main sequence star twice as big as the Sun will be just 1.4 x 2^3.5 = 15.4 times brighter, which is not enough. But 3.5 is a lot - it means that luminosity increases rapidly with mass.
To make a long story short, **let us consider a [B9V-type main sequence](https://en.wikipedia.org/wiki/B-type_main-sequence_star) star**.
It will have a mass of 2.8 solar masses, so the planet will need to be at about 8.94 AU to get our 16-year period.
Its luminosity is 80 times that of the Sun, and at a distance of 8.94 AU, it will get 80 times less luminosity - so, it will get exactly the same energy as Earth does.
We *still* have a problem here: the star *surface temperature* (which determines its colour) *also* depends on mass, and in our case it will be around 11000 K to Earth's Sun's 5700 K: this means that [the spectrum will be markedly whiter](https://phet.colorado.edu/sims/html/blackbody-spectrum/latest/blackbody-spectrum_en.html) - actually, since the spectrum extends beyond the visible boundary, it will have a much stronger ultraviolet component (yellow = the Sun, scaled; orange = our B9V star).
[](https://i.stack.imgur.com/uWbSy.png)
So, you'll probably want to tweak the atmospheric composition a bit. A denser, smaller planet will have a steeper gravity well, which allows a surface gravity of Earth normal while allowing a deeper atmosphere. You don't need very much, because dangerous ultraviolet is already absorbed by atmospheric gases; you'll end up with a thicker ozone layer.
Another notable difference will be that a star of 2.8 solar masses has a radius just about 40% more than the Sun (mass goes like the cube of the radius, so radius goes up with just the cube root of the mass). But, being nine times farther, it will appear nine times smaller; so, just about 1.4/9 = 16% of the Sun. It will appear as a white-hot, blazing pinpoint of light in the middle of the sky. Since the same apparent radiation comes from a disc about 3% the apparent size of the Sun, its apparent intensity will be thirty times higher; it will be impossible to look at directly with the unprotected eye (painful, and dangerous). For the same reason there *should* be much more pronounced [parhelia](https://en.wikipedia.org/wiki/Sun_dog) for most of the year.
The sky will also be bluer and, farther from the sun, of a much deeper blue than Earth. Sunsets and dawns, by the same token, should be a deeper red.
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**Slow it down.**
The Sun and orbit distance is the same as Earth. But the orbit speed is slower so one BlipBloop year is 16 Earth years. So Each Season is 4 Earth years long. Now get to work on the calendar.
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In this universe contained self sustaining fusion has been achieved. As we know the fuel for fusion is most commonly isotopes of hydrogen, and helium is produced as a byproduct of that.
Helium is, as far as im aware a worse fusion fuel. So my idea is that only rich can afford hydrogen for the best burning fuel. They then sell the waste helium. So poorer people have to use lower concentrations of hydrogen, and more helium
The problem is that I’m not sure if this would make sense, as hydrogen is very common, why couldn’t poor people just get it anyways and not have to use a waste product. Basically I’m not sure how to fix these holes with my idea.
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This isn't quite what you described, but may be usable for your purposes.
Hydrogen comes in three different isotopes -- H1 (protium), H2 (deuterium, also D), and H3 (tritium, also T). H1 and D are both stable; D is very roughly one part in a hundred thousand of naturally occurring hydrogen. Both H1 and D are trivially separable from seawater or other water, and it is relatively trivial to separate D from H1. T, on the other hand, is unstable, hard to concentrate, and hard to store.
H1 fusion is not really viable as an industrial process, although at scale (think: stars) it's a great approach.
This gives us two main paths to fusion power: D+D and D+T.
For your world, D+D is "high class" fusion power. The fuel for it is so cheap as to be free; but the capital expense of building a D+D fusion plant is prohibitive. Deuterium fuses with deuterium at temperatures above 400 million degrees, and this isn't easy to reach! But in exchange for building such a high-tech power plant, D+D fusion is relatively clean; one of the few waste products is Tritium, which is stable enough (in the scheme of things) to not damage the plant itself much.
D+T is, in comparison, poor man's fusion. It can run at much lower temperatures -- 45 million degrees or so -- which makes it much easier to get a plant up and running. But you have to source the darn tritium from somewhere. And while there's various ways to get tritium, probably the easiest is to pay the D+D fusion folk (and be beholden to them) to get their waste products. D+T is also a much dirtier fusion -- it produces a higher flux of neutrons which will activate (make radioactive) the fusion plant itself, limiting its life time and making the plant's eventual disposal and rebuilding a future problem.
This (very simplified) description gives you two levels of fusion technology, one that favors capital availability with both a better product and a recurring input stream; the other of which allows a bit of "mortgaging the future" to at least get large amounts of power off the ground. A bit of Vimes' theory of nuclear boots, as it were.
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I could write a long answer. But I could also point you to Atomic Rockets [article on choosing your fusion fuel](http://www.projectrho.com/public_html/rocket/fusionfuel.php#:%7E:text=With%20fusion%2C%20you%20take%20two,that%20is%20turned%20into%20energy.). Scroll down a bit and you will see a nice table explaining most common fusion reaction. Below there are details about their applications.
The gist is that neither what we usually call hydrogen nor what we usually call helium is great as fusion fuel outside of stars. Apart form the CNO cycle that the biggest stars use, where you get fun returns like 350% more energy for every 10% increase in temperature. Getting that to work is rather challenging though. Read Clarke-Tech, which is indistinguishable from magic.
The interesting stuff are isotopes of hydrogen and helium. Specifically:
* Deuterium: hydrogen with an extra neutron; get it from water or out of a gas giants atmosphere
* Tritium: hydrogen with two extra neutrons; radioactive and rare in nature, you manufacture it by bombarding either lithium or helium3 with neutrons on the proper energy level
* Helium3: helium with one instead of two netrons in addition to the two protons; rare on Earth, mine it from the atmospheres of gas giants (or the Moon/Mercury if you are a masochist)
The fusion reactions and their applications, thus inplied (social) status are:
* He3-De: very few neutrons (De-De side reactions), highest energy output, moderately hard to ignite, common ressources if space can be accessed, used in most reactors
* De-Tr: lots of neutrons (not nessessarily bad as they can be used to breed more Tritium, though you won't break even), slightly less energetic than He3-De, easiest fusion reaction to ignite, De is common but Tr needs to be produced, only used if ease of ignition is a factor as it would be in weapons and propulsion systems
* De-De: lots of neutrons, significantly less energetic than the alternatives, hardest reaction to ignite of the three, De is very common in water and on gas giants, used as a poor man fuel in the Oort-Cloud and on embargoed worlds as well es in beeder reactors in the atmospheres of gas giants to transmute Helium3 into Tritium
In summary, your social status idea makes little sense. There is no perfect fuel, there is only the fuel that fits your circumstances best. I could imagine that De-De fuel could develop a bad reputation, as, as it is used in industrial facilities and by fringe groups, reactor savety standarts might be sub-par and the applications aren't prestigious. This is the closest your are likely to get to the system you want.
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Neither normal helium nor normal hydrogen can be used as fusion fuel, so the whole plot is impossible.
Fusion fuels are deuterium, tritium and helium-3 (ignoring proton-boron fusion).
[](https://i.stack.imgur.com/hCpLr.png)
Deuterium is easy to get by isotope separation from any natural occurring hydrogen source (water for example).
Tritium must be produced, either from lithium or from helium-3 (3He + n -> T + p!). Both methods use reaction with neutrons, tritium supply therefore depends on neutron supply. Tritium is also a by-product of deuterium-deuterium (D-D) fusion.
Helium-3 is difficult to get on Earth, but can be mined in the atmosphere of the gas giants (or on the Moon, but reserves are much more limited). Tritium decays into helium-3 with a half-life of 12 years. Like tritium helium-3 is a by-product of D-D fusion.
Note: you can produce both tritium from helium-3 and helium-3 from tritium, and both can be produced from deuterium if you have a D-D reactor.
Using pure helium-3 as fusion fuel (number 4 in the picture) is the cleanest option, because it does not produce neutrons, but it is also the one hardest to achieve. That would be the "rich man's fuel".
The reaction D-He3 is a bit easier to achieve and more energetic than pure He-3 fusion. But it is not as clean, because neutrons are produced by D-D side reactions.
The reaction D-T is the easiest to achieve, almost as energetic as D-He3 but also the dirtiest option, because it produces the most neutrons, so it would be the "poor man's option"
D-D is a special case. It is more difficult than D-T fusion and provides only a forth of the energy. However, it produces useful products: tritium and helium-3. Also, in a real life reactor, those products would react with the deuterium and also with each other (unless you separate them) resulting in energy output similar to D-T fusion.
In your plot the "poor man's fuel" is a waste product of the "rich man's fuel". That is not really the case and I can't see a reasonable way to save that part of the plot.
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Healthy part is the energy rationing. If something is abundant, it does not mean it has to be available to anyone on equal basis. Energy in this case is a product of product of product of product of technological product of a society or humanity in general, a result of collective work. It needs to make all those fusion reactors, maintain them, improve, make all kinds of science and technologies and researches.
So in this setting availability of energy based on merrits - it can be a fair enough system. And if no matter which specifics are of that merrit system it possible to have poorer and richer people, so as super rich and poor.
In a sense you do not have to invent anything in this setting, if you wish so and story/history of this setting is in this way - it all busness as usual, and fusion by itself does not bring the change. Same way as presence of solar panels and sun light does it not, or wind or hydro or nuclear power, or whatever.
Another few major resources people do not have equal access to, even if they are abundant - is land, fresh water, oxygen(I had to mention it - one eats less he uses less oxygen), sun light.
What you do with fusion can be a way out for different inequalities, if you do it, but not the fusion itself. I mean fusion offers opportunities, but are those opportunities persued is a different a story based question.
As a note, helium is not only a worser fusion fuel, but if compared to D+T it like burning rocks instead of coal (which also not that easy to ignite and burn) - I mean it totally a different beast. Here is a list of valid options <https://en.m.wikipedia.org/wiki/Fusion_power#Fuels>
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Often easy to get/cheap resources will not be available to the poor, as laws will be put in place to protect their status. A good example of this is silk in ancient times, which became more available to the places around china as china manufactured and traded more of it. Many of the rulers in those places made it illegal for the less wealthy(although not poor, more middle class/merchants) to wear silk.
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I'm not sure what you're trying to accomplish with this story idea.
If you just want to have a society where the rich have abundant energy and the poor don't, you don't need to get into this "levels of fuel" business. Hydrogen as an element is abundant, but it's not like you can just go in your backyard and pick up a bucket full of hydrogen.
And in any case, while hydrogen is plentiful, fusion reactors are not necessarily cheap to build and operate. If and when fusion becomes a viable source of consumer energy, it's not at all clear from present technology and engineering how much it will cost. Who knows what technologies will be invented in the future? But if present trends continue, fusion plants will be huge, very expensive operations. A poor person will not be buying his own personal fusion plant to run in his basement.
So just like today, the rich can afford all the energy they might reasonably want to run a home, while the poor struggle to pay the electric bill and have to scrimp and save.
Is there some reason why your story needs different fuels, as opposed to people plugging in to an electrical network like today? If so, I'd think a more plausible angle would be different purities of the fuel. Hydrogen comes in several isotopes. You need deuterium or tritium to run a sustained fusion reaction. Deuterium and tritium occur naturally in any mass of hydrogen but in very small quantities, so the hydrogen must be run through a centrifuge or some other process to increase the concentration of deuterium. I think it more likely that if there were different "grades" of fusion fuel in a society, that it would be hydrogen with different concentrations of deuterium.
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# Probably the other way around
As a rule, the [proton-proton chain](https://en.wikipedia.org/wiki/Proton%E2%80%93proton_chain) is more readily accessible in a star, versus the [triple-alpha process](https://en.wikipedia.org/wiki/Triple-alpha_process) that needs a hotter environment to get past an unstable intermediate.
The "poor" would be those who can only mimic reactions in the core of the Sun that would take billions of years under those conditions, while the "rich" can take their helium waste product and fuse it.
Now, there's an odd caveat to this - despite all the fancy tech needed to fuse the helium, the power output is not better, but *worse*. The rich don't care, of course; they can have more reactors. The real point is, the rich people's reactors can generate lithium and beryllium by triple alpha, and can easily move on to CNO cycle reactions. With advanced technology, they can generate a huge array of isotopes - light ones, at least - and have the power to *make* things. That's not really a good enough plot explanation (asteroids are cheap), but perhaps they can also make exotic matter we haven't yet discovered. Elongated nuclei with super-fast spins that fuse together into neutronium-like cables or something. I don't know, this is a few thousand years past my tech grade. But there's more variety in those cycles than in just fusing some protons.
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A common trope in fiction involving things like magic or aliens is the concept of the "Masquerade", wherein the fantastic elements of the setting are kept secret from most of society. While the in-universe reasons for this vary, the main purpose of it as a writing tool is generally to make sure that the world of the setting *outside* of the fantasy/sci-fi elements most closely resembles real-life, to cut down on complicated alt-history worldbuilding and/or make the setting more relatable to the reader.
However, realistically, that ulterior motive requires a heck of a lot more than just keeping humans from finding out that the fantastic elements exist. If that were the only rule, what's to stop, say, Mircalla Karnstein from using her vampire mind control powers on the political elite to legalize gay marriage in the Victorian era? What's to stop some telepath from posing as a prophet, impressing the humans of ages past with their "divine knowledge", and starting a religion around themselves? What's to stop *any* particularly powerful member of these groups from gaining influence on human politics and development behind the scenes?
It seems pretty clear that most masquerades, for whatever reason, aren't just about not getting caught. They're implicitly also following something akin to Star Trek's Prime Directive:
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> As the right of each sentient species to live in accordance with its normal cultural evolution is considered sacred, no Starfleet personnel may interfere with the normal and healthy development of alien life and culture. Such interference includes introducing superior knowledge, strength, or technology to a world whose society is incapable of handling such advantages wisely. Starfleet personnel may not violate this Prime Directive, even to save their lives and/or their ship, unless they are acting to right an earlier violation or an accidental contamination of said culture. This directive takes precedence over any and all other considerations, and carries with it the highest moral obligation.
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Except in this case, it's being enforced on people secretly living *within* a society rather than generally existing outside of it, and also it's not "introducing superior knowledge", it's "shaping human development to more benefit members of the secret society". There's clearly a set of rules in place forbidding this secret society from making human culture substantially different from what it would have looked like if this society didn't exist at all.
But what would that set of rules actually look like? Setting aside the in-universe purpose these rules would serve (as the actual in-universe justification of masquerades is an infamously shaky topic a lot of readers aren't satisfied with), assuming the motivation is there, what would be the best way for said rules to be laid out?
**What is the simplest set of rules a secret society can follow in order to prevent their existence from having an influence on human culture and the march of history?**
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# Who's to say there ISN'T influence?
**FRAME CHALLENGE:** One of the most common tropes in literature (or conspiracy theories) is the idea that people are currently manipulating society to fulfill their own visions of the future. Aliens, vampires, Reptoids (if you consider them separate from aliens) and the like are all portrayed as quietly shifting society, and that they have been for decades, centuries, or even millennia.
It is FAR from clear that a masquerade requires a prime directive. In fact, I would argue that a masquerade would REQUIRE interference in society so evidence disappears, un-cooperative public figures disappear without leaving evidence, or people are given plausible reasons WHY that video showing vampires feeding is an internet hoax. The media would be influenced, leaders influenced, and possibly (like in *Men In Black*) large portions of the populous directly influenced.
So maybe L Ron Hubbard was a telepath and DID start a cult revealing truth, and had to be silenced because of it. Harvey Weinstein? Totally a tool of the Reptoids. The FBI? Most of their budget is spent doctoring evidence to make vampire attacks "disappear."
**Besides a rule to maintain the masquerade, you'd probably need a rule requiring the creation and maintenance of a giant conspiratorial organization charged with maintaining the masquerade (let's call it "the Illuminati").** The aliens, vampires, Reptoids, and Scientologists would all need to sit down at a table and hash out who controlled what, how disputes would get handled without public exposure, and what the powers of the conspiracy would be.
In fact, if you DID have multiple supernatural factions to contend with, the only thing likely to STOP a global supernatural war would be an agreement to maintain a public façade or normalcy.
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## God Did It
As with so many things, God solves your (narrative) problems. You don't need a lot of rules to maintain a Masquerade; you don't even need your Masqueraders to be quite sure of the exact rules. You just need them to be profoundly and universally terrified of *breaking* the Masquerade.
Can one or two vampires living quietly on the edges of society get along, but lightning reliably strikes any vampires which wreak too much havoc, or who try to actively set up a cult to themselves to religiously/politically dominate a kingdom? (Even if they never go outside!)
Are the people of Faery left alone in their underground kingdoms, and allowed an occasional midnight procession beneath a moonless sky, but they know (they *know*) that they are not "permitted" to set up an above-ground kingdom, or to openly negotiate with or threaten the mortals? (Whatever woes they are allowed to inflict on mortals unwise enough to wander into *their* territory...)
Is the occasional wizard allowed to sell his soul to dark powers (or not-so-dark?)... But even those dark powers will withdraw and leave our wizard powerless if the wizard presumes to make a too-public show of his dearly-purchased abilities? (Because the dark powers themselves get punished if they overstep, even if they do it through a proxy.)
If there's a big, ageless **Something** which effortlessly and ruthlessly eliminates any Masquerader who makes too much noise, the only rule required to maintain the Masquerade is the simplest and most straightforward rule of all: **Self-Preservation**
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**The Truman Show**
Puppeteers who run the [Masquerade](https://tvtropes.org/pmwiki/pmwiki.php/Main/Masquerade) (TV Tropes warning) are doing it, first and foremost, for the show. And some of the basic rules of showrunning is to avoid goofs and breaking of the fourth wall (unless this is showrunners' intention, and in our case it is apparently not).
So the secret society that stands behind the "real" world tries its best to stay hidden. If some "unmasking" is happening, they try their best to cover it up.
One simple rule that guides them is "The Show Must Go On".
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There is a horse race happening in Hell. Hell is very rocky and prone to earthquakes, so the best place for the racetrack is on a river of molten lead. This makes for a flat course with obvious boundaries.
The horses are 800kg robotic hell horses so they don't mind the heat of the lead. The jockeys are Devils in 200kg war chariots slays.. I mean *sleighs* ..which everyone knows are fireproof. No one is at danger from the lead being molten. The difficulty is how to run on the surface.
Molten lead is a very dense liquid, even at balmy 400°C summer race nights in Hell. Slightly less dense than Mercury tho. [And you can float in mercury only up to your calves!](https://www.youtube.com/watch?v=m8KzmlIEsHs)
[](https://i.stack.imgur.com/SztxN.png)
Ooooh Indeed Cody!
I wonder what should the horses feet look like in order to run properly on the river? While Cody can float in his tub of mercury, he would have trouble running since his ankles are submerged.
I would expect a good type of foot should be wide to keep the ankle above the waterline, and have hobnails to provide extra traction. Is there anything I have overlooked about the properties of lead that make it harder than that?
Don't worry about the feet not working on land -- everyone knows robotic hell horses have transformable feet.
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**Something like snowshoes**
No matter what the horse wears on its feet, it must sink into the molten lead enough to displace a volume of liquid equal to the weight of the horse. The issue you want to avoid is sinking into the lead too deeply, so the way to do this is to displace a wide and shallow volume of lead. The horse should wear lightweight shoes that are wide and flat, allowing it to displace a large volume of lead while only sinking to a shallow depth. The shoes should also have fins perpendicular to the direction of travel, which will allow the horse to push backwards and propel itself forward, or else it will not be able to get any "traction", as if it were running on a sheet of ice. Of course, the whole apparatus needs to be made of something with a melting point higher than lead.
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## Scoops: The viscosity of molten lead may allow them to run on its surface similar to green [basilisk lizards](https://wonderopolis.org/wonder/how-does-the-basilisk-lizard-run-on-water#:%7E:text=Basilisk%20lizards%20have%20special%20toes,feet%20hard%20against%20the%20water.) that run on water
It has a number of adaptations that allow it to do so on water, but we're not running on water anymore. Hollow bones, 360 degree hip rotation, more surface area on their toes.
Some molten metals *can* have viscosity close the that of room temperature water, but they have to be hot enough. A slightly cooler but still liquid metal increases in viscosity until it becomes solid. So the factors of; metal element (is it pure lead or an alloy), temperature, speed of the foot, rate of kicks, and surface area of the foot can all be tweaked to make this possible.
Each step being more like kicking off the liquid, much of the foot itself being submerged during their strides, as if swimming in a very shallow pool with enough force to keep themselves afloat (if basilisk isn't a good example, imagine a dolphin staying mostly out of water by using their tail to keep pushing themselves upward) rather than jumping off the surface tension. A racing gait on liquid would be quite different than on land, with the ankle rotated roughly 70-90 degrees to get the best surface area to kick off of after it's inserted into the liquid at each step. These "horse" feet would need to be specifically designed for this purpose.
(Keep in mind, this would likely kick up a lot of molten metal in the process, potentially causing damage to other racers if unable to take the heat)
The chariot behind can use water-sled skids, or even hydrofoil designs (if it doesn't cause too much drag in the lead) to support the weight of the rider. Buoyancy may be enough, but with these weights, moving forward may be required not to sink, else a break down of the "horse" may result in the entire setup sinking in the molten lead.
["Racer Down! Let this be a lesson to any would be racer that can't make it to the end!" As the horse and chariot of the broken down racer slowly sinks below the surface to vanish entirely below.]
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Baseline: lizard running. Basically large area feet to push against large volume of lead, before it collapses on top of the lowered feet. 25 km/h or so.
<https://en.m.wikipedia.org/wiki/Common_basilisk>
Optimize drag: Lizard running requires a lot of energy because of how wasteful the push is, how much wave and splashes it creates. Better motion is to use ice skates motion and streamlined boots with a 'keel' for much larger area to push against, lower load on each skate - only one is lifted at a time. And smooth lifting and submerging of a feet. Allows speed of 50 km/h or so.
<https://en.wikipedia.org/wiki/Ice_skate>
Optimize propulsion: Waterwheel is about twice as good as propulsion with skate motion that still requires to lift and lower significant body out of liquid. And propeller is another twice as good as waterwheel. But thanks to lead we can use MHD, that in this very specific case is even better. Not much though. And MHD needs electrics. Is there electric output option in a horse? If so, MHD. Is there mechanical shaft output only? Then propeller. Otherwise waterwheel boat option. Allows speed of 100 km/h or so.
<https://en.m.wikipedia.org/wiki/Magnetohydrodynamics>
Optimize support: actually liquid is rather lossy, when used as a support. Hover or wing in ground effect vehicle can be faster for the same energy expenditures once we get to 200 km/h or so.
<https://en.wikipedia.org/wiki/Ground-effect_vehicle>
Optimize extremities: as we exceed 200km/h or so, even just the engine, be it propeller of MHD, creates a lot of drag. Alternative is maglev-sort-of. Use switching coils to propell forward, and use lead as electrically conductive rail. Allows 400 km/h or so.
<https://en.m.wikipedia.org/wiki/Maglev>
The end, optimize wave drag: just put the horse in or transform it into a high speed train shape, plane without wings. This reduces air drag, that limits further speed up. Allows 800km/h or so.
[https://en.m.wikipedia.org/wiki/Sears–Haack\_body](https://en.m.wikipedia.org/wiki/Sears%E2%80%93Haack_body)
Supersonic motion in low altitude, using whatever locomotion will likely wake up some angry demons with the shockwave and cause end of the world, so we wont do this.
You are free to pick whatever level of craziness you deem acceptable in your competition.
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# Make them run a boat
[](https://i.stack.imgur.com/9bYM1.jpg)
(source: [tamu.edu](https://nautarch.tamu.edu/newworld/pastprojects/images/Lake%20Champlain/Horse%20Ferry/slide%2015.JPG))
The horses run to the river and couple in to a treadmill. A racing boat on lead would be much smaller than a ferry, but basically turn their running into a drive for the paddle wheels. It needs a rudder linked to the rider’s position. [Maybe a chariot](https://worldbuilding.stackexchange.com/questions/224514/illegal-steampunk-horse-racing-after-the-apocalypse-what-format-is-most-profita/226894#226894)?
So the hooves just need to grip the treadmill.
But then again, one clever devil might say, “Well, all this weight from the wheel and gears is sort of dragging me down.” So why in Hell wouldn’t you just bury the dead weight?
Do the ferry but it’s just a big surf board with support straps. The horse is dangling over molten lead with just the ankles getting …wet. Now, your shoes are just basically paddle blades bolted onto robohorse’s foot.
[](https://i.stack.imgur.com/43orn.jpg)
Now it’s just the weight of the raft and a few supports.
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My story has generally humanoid, human-sized creatures with insect-like exoskeletons. Assuming their joints and bone structure work as closely as possible to their internal-skeleton counterparts (and that lower gravity allows the exoskeleton not to collapse), would hand-to-hand fighting/fist-fighting have any major differences? Are there weak points/strong points in an exoskeleton that could be exposed with peak-human-level strength? I thought for example that a fighter may grab and tear the other’s shell away, or that a heavy blow could fracture chitin and suffocate an opponent. Could this generally work, or would hand-to-hand fighting be generally fruitless with an exoskeleton?
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If there are no tools, it would seem that attacking joints to pierce, sever or tear limbs would be very effective. Depending on the biology, lost limbs could be a nuisance or they could be fatal.
From a sheer strength standpoint, unless the creatures have special snapping limbs to provide incredible impulse or momentum, I doubt a single hit could crack the "chest" or "back". For two reasons:
First, look at humans. No matter how hard a powerlifter or boxer punches another person in the chest, it is unlikely to cause complete destruction of the ribcage. Most humans simply cannot destroy others in a single hit. It takes repeated hits in one place to break bones for most attackers. In part, I think this has something to do with the idea that you (generally) cannot exert forces that would break your own body. It would just kill too many creatures by accident. If you could punch with enough force to shatter a skull or ribcage, you would be subject your own skeleton to some non-trivial amount of the hit as a counterforce.
The second reason is thematic. If they have exoskeletons, these creatures are probably hard to kill. It would seem silly to just have them able to crack each other open, when nothing else on the planet has evolved along the same lines.
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The "smasher" varieties of [mantis shrimp](https://en.wikipedia.org/wiki/Mantis_shrimp) accelerate their club-like claws at over 10,000g to deliver shell crushing (150Kg force) blows to their victims.
Similarly for our humanoids, the "fists" of the exoskeleton are heavily armoured and used like a [mace](https://en.wikipedia.org/wiki/Mace_(bludgeon)) that can break bones. Highly elastic tendons of the triceps, like those found in a kangaroo's hamstrings, can store tension while the contracting muscles (biceps) hold the fist back until ready to strike, which when released happens in the blink of an eye.
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Boxers knock people out not by destroying their skulls but by shaking their brains. A human head is the closest we have to an exoskeleton part of the body. People can be knocked out or killed even wearing steel helmets.
The major difference would be to target punches to areas overlying vulnerable organs. The strikes can transmit force through the carapace.
But just like humans almost any melee weapon is preferable in a fight to the death than your fists. If only as a force multiplier or puncture weapon.
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> would hand-to-hand fighting/fist-fighting have any major differences?
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The Martial Arts that we have created on Earth are a specialized series of attacks and movements meant to deal with humans. Through generations of study, we created attacks methods to attack the organs and joints and deliver a series of blows that are meant to strategically corner your human opponent.
All of that goes out the window when you're fighting something that isn't a human. Martial Arts designed to deal with non-human targets would need to be redesigned to attack their new weak-points and defend against their new range of motion.
For example, many martial arts have grapples and holds that are designed to restrain a human efficiently, and put the attacker in an advantageous position. Those holds only work with a human's joints and skeletal structure. A Hold that would restrain a human-sized insect would need to adjust to the new joints, ranges of motion, and attack the weakest angles of their musculature.
Entire styles of fighting will be obsolete due to the difference in strength, number of arms, body height, body weight, etc.
Martial Arts in your world would be very different that anything we have come up with on Earth.
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Silverbloods are those whose blood gleam like polished silver when alive and are a dull grey when dead, an image of them bleeding being much like the spilling of mercury.
They have the ability to willfully control their blood as if by telekinetic influence for as long as it or a mass of it remains in contact with them, the metallic fluid being capable of being forced out through their skin if they don't wish to cut themselves, and can solidify their blood into silvery solid objects, most of the time being weapons or armour or arrows but enough of their blood can lead to the construction of walls, bridges, doors, whatever they need really, in seconds, with the only risk to using too much of their blood being that they pass out and risk dying. They can circumvent the not-enough-blood-for-something issue by stockpiling solidified rods or some other shape of the stuff for later use, as the objects can be liquefied and reformed at will when in contact or even reabsorbed if they've lost some for some reason. Lost silver blood recovers as fast as normal blood so they can't simply recover in a short amount of time if no replenishable previously 'banked' source is available. They are not limited to the reabsorption, manipulation, or reshaping of their own silverblood, as there is a close enough relation to all silverbloods for them to be able to use that which was produced by other silverbloods.
If they lose contact with something made from their blood it becomes dull grey as well, but once contact is re-established it gains its gleam once more. Injury, age, and disease is not too much of an issue for silverbloods as they're largely immune to most pathogens, heal twice as fast with no scarring but are still susceptible to limb or organ loss, and seem immune to the passage of time as there are one or two silverbloods who are well into their second century without anything to them that could be described as 'old' except for grey/white/silver hair. Silverbloods can 'burn' an amount of their blood to produce a glowing mist that can perform tasks that a physical construct of their blood can't, like setting something on fire or freezing water, but they must take care with this ability as the burnt blood is lost forever until their body eventually replenishes it or they reabsorb a previously solidified object.
These boons are not without their drawbacks, as a silverblood is cursed with needing nearly three times as much food as a redblood, are heavier than they seem and have difficulty swimming, and have a tendency to not operate well under in hot conditions as their body heat is slightly higher than a redblood's. A rare occurrence, but if a silverblood was struck by lightning it's guaranteed for them to die where a redblood would at least have a chance of surviving.
The silver blood is inherited from parent to child in an excruciatingly painful rite of passage ritual where it feels like your very bones are on fire. The ritual does not work for people who aren't closely related, and if tried would kill if not severely harm the non-related recipient. What people don't know about the silver blood is that it's actually a collection of nanomachines performing all of the functions normal blood usually does in addition to the abilities it gives, and the sensations during the ritual are due to your bone marrow being replaced by factories for these nanomachines whose workings are imperceptible to the naked eye that also performs the bone marrow's usual duties as well.
The setting is 15th century medieval, but only technologically/socially due to it being a setting in which the world has recovered from an apocalypse that has effectively knocked the world back to the stone age. Advancement was faster than usual initially due to the survivors but as the generations went on only more immediately useful knowledge was passed on like tanning and woodwork instead of things that were currently out of their reach like electronics, causing a degradation over time of the overall knowledge-base of the population as a whole and kept the civilized world in a relatively low-tech state.
Accessible libraries with physical books who have miraculously survived the passage of time still exist but the language and script has changed and superstitions and fear has made people avoid any of the ruins and old buildings that dot the landscape. The only advanced technology they still have at their disposal and frequently use are the nanomachines of the silverbloods, but due to them not understanding it their outlook of it is on the mystical side of things, basically looking at silverbloods as if they were sorcerers.
They'd be able to construct much more powerful and devastating weaponry and near-indestructible protection with their nanomachines if they knew how, but that knowledge has been lost. The libraries are a hope for knowledge recovery but everyone avoids them and the ability to read what's in them isn't available so it's not like you'll have knights with laser/plasma weaponry and force field shields any time soon, and so they still fight with normal kind of weapons and armour, with anything made out of their blood being on par with what would be considered by 15th century smiths as high-quality steel work. One who has lost limbs or organs may even be able to produce cybernetic stand-ins, but still the lost knowledge point remains.
Their versatility and power has led to the majority of silverbloods finding themselves as part of some army's elite and more highly paid units as redbloods are seen as inferior and it being perceived as fact that they'd obviously make for much better soldiers than anyone else. The question on my mind is if they'd actually be better than a normal soldier or if the perception is wrong and that their 'blood' is as much of a hindrance as it is a benefit with regards to their weaknesses, their comparatively higher cost to maintain/feed, and 'medieval' level of power.
**Would silverbloods actually make for better/superior soldiers?**
Extra information as requested by A Rogue Ant:
* The blood's durability is varying depending on its state, with it being squishy and easily manipulated like mercury as a liquid but being as unyielding as forged steel as a solid.
* Other metals won't dissolve in the silver blood. The only way to have the blood dissolve other metals is through expending some of their blood to form the glowing mist which would then take something apart if they wanted it to. It's a one task per cloud kind of ability, the volume of the cloud determining the scale of the effects with 1 liter of silverblood spent/burnt creating a 1 cubic meter cloud.
* The fine-ness of their control is as fine as the clearness of their idea of what they want is. If they simply want a sharp sword they'll get one but how sharp they'll have no control over, but if they focus on wanting a sword with a 10 degree angle to its blade and 1 meter in length they'll get the 10 degree blade 1 meter in length, though a clear idea of degrees and measurements and the exact values of each is required. They can also emulate an already existing object to a 1% margin of error if they see the object while forming it and to a 5% margin of error from memory only.
* From puddle to longsword the process takes about two seconds.
* Things can be reformed on the fly but battle tends to be chaotic so any reformations will be inferior in quality due to shape errors to what they could've spent time on as to the object's specifics before the battle.
* Having some parts be more solid while others not for a semi-solid controllable assortment of multi-purpose tentacles from walking to manipulation at a speed similar to muscle limb movement, or as Ant calls it, "Doc-oc", is possible but only if they train themselves to use their blood as such due to the high amount of mental effort required to constantly control it like that. This includes 'catching an arrow' if they were aware of the arrow in flight and could move a blood limb in time. Smaller and more finely-controlled silverblood limbs are also possible but takes more mental effort.
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# Internal control:
As a biologist, I always see things as an interplay of conditional advantages and disadvantages. I am a big fan of nanites as the rationale for pseudo-magic. What I suspect is that the way to use these abilities best would be to figure out how to make the most of the nanites while they're still in the body.
For external use, I think the key (and yes, this would be perfect for keys) would be practice. There are no nerves in the fluid, so they get limited feedback. A fighter will get the feedback from a knife, a thief the feedback from a lockpick. use easy shapes, or create small observable parts. The biggest use in a fight is surprise - the knife in the hand of the unarmed, for example. In this case, carrying extra rods of blood will be a dead giveaway.
* If you want external armor that's adaptive, you will need to spend weeks to months gathering up the excess mass that will mostly be a substitute for conventional equipment. Your ability to spontaneously alter and repair this equipment will be helpful, but not as big of an advantage as you might think. But a sword suddenly becoming a spear would be really useful. Then the head explodes like a pufferfish inside the wound - nasty.
* Concentration will likely be a bigger problem. People think a lot less than you give them credit for, and your warriors would need to devote a lot of concentration to shaping and maintaining equipment. The may be better off with normal weapons enhanced with this ability (like a thin external coating allowing better control).
* Since it's precious, and hardens externally, don't build a bridge with it, make the nails, or the joins and clips.
* I don't know if you can induce rapid motion (like drilling) but if you can, there are other interesting abilities that allow you to replicate modern equipment. I would avoid this one, but it's your story.
But in terms of blood volume, the issue will be weakness and endurance. Armor will move so much blood outside of the body as to make the character too weak to fight well. You can't function well way before you reach the point you die from blood loss (that's 18 years of blood-banking talking). This stuff must weigh about as much as metal for it to work like metal, and from a biological point of view, it must eventually start to attenuate separated from flesh (I'd suggest about thirty days, if it behaves like a unit of blood taken from the body).
Keep the stuff inside where you'll have the best control.
We've already established that they greatly increase healing. In this case, I think you're trying to make hemi-metal terminators, so I'll make the comparison for what it can do according to that (although the shape is maintained after dissociation with the body). I'm assuming the fluid can be drawn back into the body after being extended out of it (recovering blood volume).
* Use the blood to harden the flesh to metallic consistency when hit. The epidermis will get nicked up with cool scars, but otherwise armor can be INSIDE the body.
* Similarly, shift weight telekinetically to increase the strength of blows.
* Besides rapid healing, simply don't bleed! You control the blood, so it will stay in the body even when you're injured. Solidify a little at the site of a "lethal" killing blow and that cut artery is a minor inconvenience. Between this and disease immunity, your warriors need to be decapitated or pinned down and systematically chopped into pieces to kill them, so as long as they aren't grossly outnumbered, they are very hard to kill.
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**Big Advantage**
One of the major ways a soldier is killed in ancient/medieval combat is through blood loss. An artery gets cut, and they bleed out within seconds/minutes and die. Or minor injury/ies weakens them, and they get killed because the blood loss slowed them down. Silverbloods can survive both these problems with ease. Either they A: simply order their blood to instantly coagulate (not sure of the feasibility of this in your setting so this may only work for minor wounds) or B: they can replenish their blood supply via stored rods. Either way, they can take injuries and blood loss that would kill a normal human and keep on fighting, at least for a while. That's a huge advantage.
The other big thing is they can in theory have variable-length weapons. Imagine your Sivlerblood is equipped with a 8ft spear (the traditional fighting weapon, swords were almost always backups) with a silverblood head and a fine line of silverblood running down the length of the shaft such that the user can always be in contact with it. You stab your opponent, and he jumps back. At the same time you activate your silverblood spear and increase the length of the blade another foot, which catches and kills him. This also works with swords, or even shields. Yes it takes a second or two to go from "puddle of liquid" to "hard as steel" but that in-between state should be more than enough to pierce flesh or knock aside a blow. Especially if the growth/change is imparting some extra kinetic energy to the weapon/shield. Hell, you could even use it to blind enemies in full helmets or jam joints in plate armor.
If your soldiers have time you could also do some pretty cool things with their personal armor. variable-density breastplates with a hard outer shell and a "squishy" liquid middle to absorb kinetic impacts for example. I don't think they'd be that more effective than simply wearing "normal" armor with quilted gambeson etc, but it could be part of their mystique and may end up weighing a bit less, which would be nice.
For added fun, they'd be able to have emergency DIY caltrops. Not a war-winner by any means, but if they had a rod of blood set aside for it a unit of silverbloods would be that much more difficult to tackle when defending.
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# Silver blood = silver TANK
The way you describe, these people are at the center of a nanotech machinery empire. One that can be implemented as a tank that sounds reasonably comparable to modern steel (maybe not depleted uranium) in terms of armor, but which has unorthodox features such as the ability of its tracks to spear fish people and drag them under to be crushed. They can certainly extend and reshape (at the cost of *less* armor) to become trebuchets with buckets custom-shaped to work with each boulder they encounter on site, or which can be dug from the ground with silvery tentacles. They can worm into cracks and expand like the frost of a hundred winters to tear apart any masonry, and pass beneath a breach in any wall while holding it up and leaving steely supports behind that can be collapsed at will if the wrong folks follow.
Basically, your Terminator 2 is going to chew up the enemy army quite nicely. More than one would be overkill ... but what military doesn't like overkill?
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If they need to be in contact with their silverblood to control it, they can't really make arrows or any projectile weapon out of it.
For once, they would need a string attached to it to control its flight, and they would be stuck in recovering it before a new use. Not really handy, especially if your target is not the standard NPC waiting for you to do as you please, but is actively trying to cut that string and leave you unarmed.
Moreover, a human body contains about 5 cubic decimeter of blood, or 5 liters, not much wall or bridge can be done with it.
In short, if any advantage can be found in these silverblood, is in close range combat, where they might parry attacks from any direction as long as they can protrude the mass out of their body.
Oh, since we are talking medieval times, wars in those times were preferably fought in summer, meaning that the higher temperatures might put your silvebloods at a slight disadvantage.
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[Question]
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I have designed an animal that lives on a low-gravity planet. It has bird-like digitigrade legs with raptor-like claws, similar to the image below, except with two wider toes instead of three in the front.
[](https://i.stack.imgur.com/qaMHv.jpg)
The toes are designed this way so the creature can perch on surfaces, etc. However, I also wanted to make the creature be able to run quickly. I noticed while researching that ostriches and even velociraptors do not have a back toe, implying that they could get in the way of running quickly. Would it make more sense to remove the back claw, or find some way to have it "retract" while running? Would it necessarily have a big influence on running speed/efficiency, or have a big effect on the gait of the creature?
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## You can get away with them.
The faster you want your creature the lighter you need the ends of the limbs to be, their is a strong push to get rid of anything not useful on the legs of running animals.
That said there is an example of what you want, the roadrunner, which are Zygodactyly. They curl the back toes upwards creating something like a heel when running. they still do a lot of climbing and perching. the Zygodactyly feet are ancestral and since they get a lot of use, they have only modified them not lost or reduced them. As long as you don't need cheetah speed out of your animals it is fine.
[](https://i.stack.imgur.com/3nyy4.png)
[](https://i.stack.imgur.com/JR2Hw.png)
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Not necessarily. While there's a strong correlation between not having trailing toes and moving swiftly. There are also lots of examples of creatures who don't move swiftly who also don't have trailing toes. Think the elephant, or the tortoise.
What's probably more likely is that having trailing toes on the hindleg is not useful for all these creatures and as a result there is no evolutionary pressure to preserve the toe. If you look at creatures with trailing toes, there tends to be some advantageous reason for them to exist. Common reasons seem to be grasping things, or distributing pressure over a wider area.
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I was thinking about [Ozymandias](https://www.poetryfoundation.org/poems/46565/ozymandias), and it struck me as a little weird that the head of the statue fell so close to the legs while the rest of the statue seemingly disintegrated into sand. Thinking a bit further about this led to a prompt which I hope the worldbuilders here will find amusing.
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> You have been tasked with King Ozymandias to build a great statue. However, you believe that Ozymandias's legacy would be *much better* represented by two vast and trunkless legs of stone and a shattered visage, surrounded by lone and level sands.
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Design a statue to the following constraints:
* The statue must stand for the rest of King Ozymandias's lifetime (around 50 years)
* At some point afterward, within the next thousand years, it must collapse such that it meets the description in the poem.
+ The lower legs must remain standing.
+ The head must fall next to the legs.
+ The plaque must remain readable.
+ The rest of the statue - torso, arms, and any ornamentation like scepters or swords - must be destroyed or otherwise rendered invisible from the surface.
+ The statue must be surrounded on all sides by empty desert.
If you can accomplish that:
* Keep obvious sabotage to a minimum. King Ozymandias has given you an unlimited budget, but if you stuff the torso of the statue with gunpowder, the amount of bribes you have to pay to keep the workers quiet could attract scrutiny on audit.
* Use as old a technology base as possible. King Ozymandias distrusts the new stuff - especially that stuff that those time travelers from 2020 are selling.
* Avoid external interaction after the statue's completion. The statue won't crumble until after the end of your lifetime, so if you pay people to demolish the statue afterward, you have no way of ensuring that they'll actually come through for you.
* Be as certain as you can of the primary objectives.
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Stone or bronze for the legs and head, and a gold armo(u)r covering his torso - make the armo(u)r a structural, weight bearing element. During the king's lifetime, nobody dares touch the statue, but you can be sure it will be looted sooner or later. Probably sooner.
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[Calcite alabaster](https://en.wikipedia.org/wiki/Alabaster#Calcite_alabaster) for feet and head. [Gypsum alabaster](https://en.wikipedia.org/wiki/Alabaster#Ancient_and_Classical_Near_East) for the trunk and hands.
If you want a faster decay for the trunk, dig a cylindrical cavity in the trunk and fill it with [soda ash](https://en.wikipedia.org/wiki/Sodium_carbonate#Mining), the slow reaction is
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with the water coming from the gypsum crystallization. It will slowly let behind a porous weak limestone as the "rot" progresses.
Make the trunk hole for the soda ash eccentric, closer to the chest, to increase the chances the head will fall in front of the statue.
Make the pedestal low and the plaque from marble.
All the materials can be sourced from the trading sphere of ancient (and mythical) Greece and were used for statues and bas-reliefs of the time. Desert climate will compensate for the softness of the stone and water erosion, but one will need to protect the statue from desert storms.
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[Question]
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> The autonomic nervous system (ANS), formerly the vegetative nervous
> system, is a division of the peripheral nervous system that supplies
> smooth muscle and glands, and thus influences the function of internal
> organs.[1] The autonomic nervous system is a control system that acts
> largely unconsciously and regulates bodily functions, such as the
> heart rate, digestion, respiratory rate, pupillary response,
> urination, and sexual arousal.[2] This system is the primary mechanism
> in control of the fight-or-flight response.
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I am imagining if human can control the heart rate, respiratory rate, etc. so that human can suicide without any equipment (you don't need a gun to shoot yourself) or physical movement (you don't to jump off from a building). People can stop their heart beat or respiratory system by their will. No one can prevent suicide of others. Is it theoretically possible?
**EDIT:**
To be more precise: Is it possible for an species which can suspend the function of autonomic nervous system to exist?
Is there any evolutionary biology theory says it is not possible?
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**TL;DR: Such species already exist.**
As @Jonathan already mentioned, most mammals can control their breathing and, to a lesser extent, their heart rate. This doesn't quite qualify for what you're wanting, as there's still an automatic backup to keep the animal from dying.
However, there are some species that do have full control. For example, dolphins and whales have full manual control of their breathing. Dolphins have been known to commit suicide by simply ceasing to breathe.
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I would answer the question in two manners:
* Is it possible for an species which can control autonomic function to exist?
Yes
* Is it possible for an naturally evolved species which can control autonomic function to exist?
No, unless you can come up with strong evolutionary or cultural advantage why that would be beneficial and that can't be compensated for in any other way. **Edit:** I don't believe Dolphins are an counter example as i would say that the more reasonable interpretation is that they drown themselves, by diving so they are not able to get back to the surface and breathe before running out of air.
From an evolutionary standpoint there is little reason for an stably running subsystem to become totally controlled by an higher order thought process, especially if it enables the brain to perform actions opposed to the survival of the species. Another problem is that centralized process suppressing a decentralized process tend to use a lot of power and an attempt to have breathing/heart beat/digestion perform in a way that hurts the body will likely disable the hostile to life process at which point the decentralized autonomous process can recover the body to stable state.
Note that this only holds for purely evolved beings. It would be simple to build a robot which can deregulate the crystal oscillators, battery control chips and motor controllers, although you would need to have good reasons why, as this introduces an accidental breaking point at the same time.
A technologically enhanced body using today's technology could be build to either trigger permanent damage to the autonomous system, so it can't recover or actively interfere with/control the necessary communication for those processes. This way you can circumvent the problem of controlling circuits being hindered by dis-regulated autonomous functions as technological systems could come with their own power supply.
With sufficient bio engineering capability it would also be possible to enable a species which performs certain modifications being performed over the life time to control their autonomous processes. These modifications would need to include the actual ability to disrupt/suppress/control the processes in question and a energy supply that can't be tapped into by autonomous system and include sufficient reserves to outlast the autonomous system trying to recover.
An more advanced approach could be to change the underlying anti-fragile biology such that it is unstable and will fail by default and only conscious action will stabilize the body and let it live on. This approach has a few problems such as reduced survivability, the problem what performs that balancing when the individual is underdeveloped to perform that action, that such a being would never arise naturally and that often repeated actions tend to become subconscious in the brain we see on earth. These problems could be overcome if a species is sufficiently motivated.
For a species with an autonomous kill switch in literature i am aware of the "bear-cows" from the second trilogy in the "Lost Fleet" series.
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You can already control your breathing, just not to a full extent, the reason you can control your breathing but not to the point of being able to stop breathing forever is that it's an autonomous function that works subconsciously, and your subconscious decisions, putting it in a simple way, have priority over your conscious ones,especially since breathing is kind of important to keeping you from dying.
The reason for this, and the reason I think it's not possible (or at the very least that it is highly unlikely) for this trait to evolve successfully in a species is because one of your autonomous nervous system's main functions is ensuring you stay alive and healthy by maintaining vital bodily functions and letting you know when your body needs things like food, water and sleep (it also tries to encourage you to reproduce but that's not important here). Simply put: it is there to keep you alive, and disabling it seemingly doesn't provide any evolutionary advantage, rather it seems like a disadvantage, especially if it was possible to accidentally disable it.
Edit: regarding the dolphin's ability to fully control their breathing due to their environment (which is an interesting bit of information), I still don't believe it's a counter example, simply because while it can control its breathing specifically it cannot suspend the rest of its autonomous nervous system's functions as per requested by the question. Their relationship with how their breathing works is also one of the reasons dolphins can never reach unconsciousness, even while sleeping, being forced to only allow one half of their brains to sleep at a time while the other must stay awake so they don't suffocate, which again gives you a good idea of why our Autonomous nervous system exists to begin with.
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Breathing is an automatic function in humans, however, you can choose to control it manually. I think it would be theoretically possible (with enough willpower) to hold your own breath until unconsciousness, but at that point, automatic control would take over before a person could kill themselves by refusing to breathe.
*ed:*
There are hidden dangers in breath-holding in a sense of how it all works, it is not exactly automatic per se, but is regulated based on co2 concentrations, and the system isn't smart or perfect.
[Here](https://www.swimmingworldmagazine.com/news/final-breath-the-dangers-of-hypoxic-training-and-risks-of-shallow-water-blackout/) is an article about some problems involved, a bit on a for simple folks side, but still describes some problems:
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> The key to preventing hypoxic blackouts is getting to the root cause of how athletes faint when exposed to breath-limiting, high stress practices. The body’s autonomic nervous system controls our breathing at an unconscious level and bases your need to breathe on the **balance** of oxygen and carbon dioxide (CO2).
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there is free diving aspect as well, a wiki page [Freediving blackout](https://en.wikipedia.org/wiki/Freediving_blackout)
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> Freediving blackout, breath-hold blackout[1] or apnea blackout is a class of hypoxic blackout, a loss of consciousness caused by cerebral hypoxia towards the end of a breath-hold (freedive or dynamic apnea) dive, when the **swimmer does not necessarily experience an urgent need to breathe** and has no other obvious medical condition that might have caused it. It can be provoked by hyperventilating just before a dive, or as a consequence of the pressure reduction on ascent, or a combination of these. Victims are often established practitioners of breath-hold diving, are fit, strong swimmers and have not experienced problems before.
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yeah, and thinking about free divers, there are quite a number of high-profile cases, at least which got to be made into documentaries about them(okay, at least one), which got in the scope of a random guy like me.
All those above do not state specifically it is ANS fault, but **Do Not count on it** it isn't a fail-safe bug fixed microcontroller program that just works, it is a biological system.
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[Question]
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Okay, this is another question related to my drop mechanic, a question similar to [Wingjaw Steel: Superior Armor and Weaponry?](https://worldbuilding.stackexchange.com/questions/195622/wingjaw-steel-superior-armor-and-weaponry) in that it concerns a monster's effect on items.
You see, when a monster is killed, its magic infuses the item used to kill it. Also, the life force released upon death interacts with ambient magic and objects in or around the monster to create Drops, which range from body parts to coins and adventurer gear (armor, weapons, random knickknacks). This is relevant because a Mage can "craft" parts of a monster into an item and activate its dormant magic to create an enchanted item.
The monster this question concerns is a Snapper, which has four webbed feet (no legs) and a box-like body (think boxfish) that tapers to a wedge-like point in the front, which is split in two by a large, horizontal mouth with prominent fangs. Basically, a Snapper is all jaws and stomach, and their behavior reflects that. Unfortunately, Snappers spawn anywhere with stagnant water large enough to hold them, as well as in wells left alone too long, puddles, and tide pools.
However, Snappers are dang useful for one thing. When they are killed, their magic becomes an Amphibious enchantment on the item used. The Amphibious enchantment prevents the destructive effects of water (or saltwater) on objects, so you can use an Amphibious kleenex underwater. Additionally, Amphibious items have the same drag underwater as they do in air. This makes metal weapons *much* more viable for marine usage.
**EDIT:** As stated above, the Amphibious enchantment gives an object the same drag in water as it has in air, but Amphibious items also retain or exhibit buoyancy. In other words, being in water is like being in a wind tunnel for humans; one doesn't usually float in air, but with a strong enough updraft it *is* possible!
However, I wonder how useful this will actually be, so my question is: **How Beneficial Would The Amphibious Enchantment Be On General Items?**
Thank you for your input and feedback, I really appreciate it! (In other words, if you see a problem or need more information, let me know so I can add it!) If you decide to VTC or downvote, please give me an explanation so I can improve this question and make better ones in the future.
**Final Notice:** For those who answered this question, you have my sincere thanks. Since your answers were all equally helpful, I found I couldn't accept just one, and I hope you understand that.
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### Some benefit, but lots of unexpected drawbacks.
Everything "Amphibious" will immediately sink to the bottom of the water - because its behaving underwater as it does in air, and when I let go of something in air, it falls to the ground, which in this case is the seafloor.
A "non-amphibious" human swimming in the ocean is using an amphibious sword to slay someone - if in the critical part of the battle he drops the sword, it will fall to the sea floor (average depth on Earth of about 4km) at hundreds of km per hour, either shattering into pieces or embedding meters in sand depending on exact topology.
I hope the adventures in their quest to retrieve the magical amphibious sword of destiny from the seafloor have spells capable of simulating the correct gas densities and mixture ratios required to survive at each increment of their journey. (Sufficiently advanced magic should be indistinguishable from technology, after all). A similar problem comes up if you have an "Amphibious car" - either it immediately fills with water, or more air needs to be magically generated (and the gas ratios changed) as it drives down the hill of the continental slope.
Also note that an "amphibious boat" will not float - it will behave as if the water is air. An "Amphibious bucket" may not be able to hold water (as if it's not interacting with the water normally how does it collect it?). I may be able to use amphibious matches on amphibious timber to start a fire, but the fire is immediately doused by the water, or otherwise smoothers when oxygen can't reach it.
Some things require interactions with moisture to function: Ie "Amphibious superglue" will never set (as it needs to get some moisture in - usually humidity is enough). An "Amphibious desalination machine" or even "Amphibious reverse osmosis water filter" will function as if they're empty. A "Amphibious canteen" may never be able to filled up.
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# Infinite energy
*"X has the same drag in water as it has in air"* = water has the same drag as air on X.
Enchant a [water screw](https://en.wikipedia.org/wiki/Archimedes%27_screw) and have it drop water on the same water mill that moves it. You get a perpetual motion machine with a surplus of energy. I would put a troll physics diagram here but last time I did I got a warning.
Once you have infinite energy through magic, D&D (or Disenchantment) like worlds are possible. Building pyramids becomes a matter of patience. You could drain seas and turn deserts into lakes with enough time and planning. Happy world building!
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**Boats**. Per @Ash, an "amphibious" boat won't float. But if the amphibious boat has a small hole in the hull, and a normal boat floats inside the amphibious boat, and the amphibious boat is held up by the normal boat, then it will be held level with the water line, and it will move through the water without resistance, and the normal boat will sit in the midst of its little lake of co-moving water without needing to fight any resistance at all. So the only requirement is a double hull. Then the normal boat can have a normal screw protruding out the holey hull, which interacts with the water normally to provide propulsion unopposed by drag.
**Nets**. The "amphibious" net moves through the water with the greatest of ease. Dragged behind the boat above at a hundred knots or so it should be very effective (you may have to slow down a little to make sure you don't lose your net to a dolphin or press fish fillets through the holes).
**Matches**. Nobody expects a frogman (or frog-man) with a magic match that works exactly the same in water as it would in air. If you can wipe your nose with a magicked tissue underwater, you should be able to do this. The flame produced is made from the material in the match, so it contains the same "amphibious" component, so I suppose it could engulf the victim boat from underneath. Trippy.
**Seaplanes**. A gift fit for a Kennedy, these delightful aeroplanes don't need to stop at altitude zero. Yes, yes, @Ash reminds there's no air to power the engine, which is why you start it with a magic match.
**Watering cans**. Have you ever dropped a match on the sea bed and accidentally caught the weeds and debris on fire? Obviously you need an "amphibious" fire extinguisher to put it out, but it might be simpler to have an amphibious watering can. Fill it up with water on the surface, and it should still work the same way below water, right? So pour your water out of the can and it will splash down and put out the fire. Keep one on your boat in case there are frog-men about. You might need one (filled with fresh water, of course!) to water the "amphibious" corn kernels that you're farming on the bottom of the ocean; I'm not sure.
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[Question]
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I am particularly interested in the case of feasibility to have all countries and all regions of our planet, the Earth, to have a unified Single Time Zone (say UTC). Suppose all countries and all governments agree to fix their time zone to UTC, so they just need to adjust their schedule.
Questions are:
1. How can it be set up?
2. Should it be more efficient for the computer to synchronize and the internet to all run in the same time zone (same clock, same time, same number)?
3. Do we encounter any hidden obstacles?
My question is more specific about our world (more specific than [What would be mindset of people if the entire Earth had one time zone?](https://worldbuilding.stackexchange.com/q/86364/80091) -- I only just now notice this question when I am posting my first question). Let us try this thought experiments see how it goes.
4. In general, I ask a Single Time Zone on a 3D spatial spherical planet with a single Sun away from us like the Earth. One can ask if we have multiple suns or bright stars around the planet. In that case, the Single Time Zone really makes more sense, don't you agree?
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By the governments agreeing to it, as you mentioned.
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Not really. For the computer it's just a matter of keeping the UTC time and then adding/substracting the local offset before showing it. This is the case for many systems nowaday, the difference is that initially computers would be configured in local time, and keeping to support that.
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People would need to adapt to the new hours, of course, but that's just a matter of getting used to it. On Elbonia people wake up at 11 pm, as that's the time the sun rises. So, fine.
The obstacle might be when communicating between different countries. All of them would use the same timezone (which is easier for setting up meetings), but if you wanted to know if it's ok to call your colleagues in $OTHERCOUNTRY, you would need to check something like a list of opening hours there to see if it's a sensible time to call or everyone might be in bed there.
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Governments pass laws (probably on a national or regional basis) to mandate clocks be set a different way, and when the time to change rolls around, people update things. Not too difficult to set up legally, but probably hard to enforce — see, for example, people in western China, who sometimes run their own clocks differently from official China time.
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No. If anything, it gets very slightly more complicated, since computer time registries have to keep track of past time zones and when the change was made in which places in order to properly list the times of *past* events. This already happens every time a country changes its time zone, so it's not a huge deal, but it doesn't reduce the amount of work computers working with time info have to do. (As Angel explained, computer hardware itself is synchronized to UTC anyway, so it wouldn't change anything internally.)
>
> Do we encounter any hidden obstacles?
>
>
>
People are going to be pretty frustrated for a few generations as language has to adapt to change the meanings of "days", and for a while it'll be really infuriating to have everyone get used to the weekday changing while, for example, the sun is up and people are at work — where knowing the weekday might be important.
Also, again note how difficult this will be to enforce locally. People generally dislike arbitrary change that occurs only for the sake of whatever organizations lobbied for it.
>
> In general, I ask a Single Time Zone on a 3D spatial spherical planet with a single Sun away from us like the Earth. One can ask if we have multiple suns or bright stars around the planet. In that case, the Single Time Zone really makes more sense, don't you agree?
>
>
>
There are two main configurations for planets in a binary star system: either the two stars are pretty close together and the planet goes around the pair (so using conventional solar time would still be pretty reasonable), or the planet goes around one and the other is far away (in which case star #2 changes its relative position in the sky over the course of months or years, which isn't something that a single time zone would really help people get used to; solar time using the closer, brighter star would work just fine). Triple or higher-order star systems are mostly just more complicated instances of these two cases.
However, a global time zone might be a good choice on a [tidally locked](https://en.wikipedia.org/wiki/Tidal_locking) planet where one side is locked into facing the sun, and thus the sun never appears to rise or set from anywhere on the planet. Since the day/night cycle happens at the same time everywhere (which is to say, it doesn't happen at all), the idea of staggering your time zones would be meaningless there.
[Answer]
Moving between timezones would become a big hassle.
Today, when moving between timezones, all that people have to do is to adjust their clocks (done automatically on smartphones). If time difference is just 1-2 hours, even biological clock adjustment is not noticeable. Why this is so easy? Because people have preconceived knowledge about times at which things are normally happen. For example, a family wakes up a 7 AM, sends kids to school by 8, adults arrive at work at 9, have lunch at 12, finish work at 6 PM, run errands at shops before they close by 9 PM, or go straight home to have dinner at 7 PM, and go to bed by 11 PM.
Now, if a person moves away by 1 hour, all times would shift and have to be relearned. If a person is traveling for a living and frequently moves between timezones, he or she would be completely lost. Their smartphone would have to give continuous advice on what is currently open and what is not at the location, and even if it's still open, maybe it's not a good idea to visit, because the place would be closed soon for the day.
[Answer]
1. Implementation is a matter of strong-arming legislation, and possibly some war. This is much easier to do on a freshly-colonized planet than an established one.
2. Yes, avoiding timezones is easier to work with in code. Programmers basically already do this today: just use UTC to store everything and then convert it to the user's timezone only upon presentation.
3. Obstacles are primarily social, but they're *significant* obstacles. Most notably: it's confusing to the the average person if the date changes while the sun is out.
* Anyone can get used to any numbering of their schedule, but going to work and coming home on different calendar days is going to be *very strange* and confusing. Night owls like myself don't really think of it as the next day until we've gone to sleep and woken up, so imagine the weirdness if this happens to a large segment of the planet's population *every day*, in daylight, no less.
* People will live according to solar time unless you give them a good reason not to. You simply aren't going to have half of the world living most of their life in darkness.
+ In China, where there is currently one timezone spanning a landmass that would otherwise have 4 or 5, many of the western rural Chinese completely ignore the national timezone and go by solar time.
4. I suppose if you had eternal daylight, then timezones wouldn't make sense. This would make the planet pretty hot though. Not sure if that would be livable. This also raises some serious astronomical questions because you can't have one celestial body orbit two. Additionally, stars are so massive that they simply don't orbit planets and the probability of a planet living exactly in the center of a binary star system is basically impossible and would be destabilized by any outer planets or a moon and subsequently sucked into one of the stars. Gravity always wins.
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[Question]
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Simply put, what I'm imagining would be something like a quarterstaff or bo staff, except with a rectangular flag attached at one end (it would take up half of the staff's length). These would be used in a similar way, however of course the user would need to hold the staff on one side, as opposed to straight in the middle. In addition, the flag side would be used in battle, both to hit people with, and as a distraction.
Is this at all possible? And if so, how could I incorporate it into a more modern culture/society (with a lot of futuristic aspects) that I'm creating? Thanks.
[Answer]
**Yes. Flags can be used as weapons**
A lot of things can be used as weapons - and useful weapons at that. The bare minimum for a weapon to be considered 'useful' is if it has an advantage compared to laying about with fists. The pole component of the flag is generally made from a hard wood, so they can do decent blunt trauma. They're also considerably longer than your arms, especially if you're holding one in your hand, so they have superior reach. They have have a downside, of course, and that's the *flag* component. Waving around cloth will obstruct *your* vision as well as your opponents, not to mention that if it gets caught on something, it's not going to end well. (Best case scenario is that the flag gets ripped clean off, and now you just have a flagpole that you can turn into a quarterstaff. However, for the reasons I just mentioned, flags are not better weapon than quarterstaffs.
Historically, flags have actually been used as great weapons. I'm not referring to the practice of placing banners on halberds - such small strips of colored cloth could hardly be hailed as full and flagrant flags, for shame! I'm referring to battle standard - in a medieval battlefield, it was hard to tell friend from foe and even friend from other friend, so units had a man with a flag whose job it was to hold the flag up and identify the company they were fighting with. These flags were very potent weapons indeed - battles are won and lost on information.
[Answer]
everything can be weapon as long you have the imagination to apply it to become lethal (your safety not include).
to help you to apply it, for example theres a chinese spear using the hair tassel as distraction, to soaking blood to not make it slippery, and sometime to tangle.
from:<https://en.wikipedia.org/wiki/Qiang_(spear)>
[](https://i.stack.imgur.com/Y1R4H.jpg)
theres also some sword fighting using bundle of cloth including gladiator to tangle enemy weapon or the enemy themself or nullify enemy slashing effect basically improvise buckler and net.
here the image
from:<https://hroarr.com/article/exercises-for-the-cloak-and-rapier/>
[](https://i.stack.imgur.com/QFoxH.jpg)
[](https://i.stack.imgur.com/7tvtG.jpg)
[](https://i.stack.imgur.com/Qb2NK.jpg)
heck pretty sure i see that type of flag you describe was use as weapon in chinese movies with no spear tip either, i think its from one of jet li movie but the biggest bet probably from jacky chan movie (since he use everyday tools as weapon or self defense and this martial art did exist despite most people think, though i forgot the name), basically same principle like the sword and cloak technique or hair tassel,net, long chain flail,chain sickle,etc but using flag instead, so try copy that maybe.
**here found the movie** <https://www.youtube.com/watch?v=DFPqJvOJrLQ> just skip to the 0:28 (i cant do it for some reason... god, i hate my 3rd world country it lag so hard)
also found this [video](https://www.youtube.com/watch?v=fCMft1IWcJw) though seems more like its for parade than for real martial fight, but its a nice show to know the stance or application of it, as in the video show you may end up stepping on the flag if you dont do it properly, depend on your flag length since the video pretty much show the length of quarterstaff.
for historical or real theres many spear that incorporate into banner or flag, i dont remember is there one that use it as quarterstaff, as for indirect weapon as halftawed say you can use it to give information or commands to the troops, though judging from your question seems like this was not use as warfare weapon or warfare battle.
and here some of my favorite quote from jin yong novel, just because.
from:<https://en.wikipedia.org/wiki/Dugu_Qiubai>
as Dugu Qiubai (one seek defeat) nickname sword devil say
>
> "The "Sword Devil" Dugu Qiubai has become the invincible and unchallenged swordsman under Heaven, hence he buried his swords here.
> The heroes of the realm bow before me. Now, my Long Sword is of no use
> anymore. The agony!"[3](https://i.stack.imgur.com/7tvtG.jpg)
>
>
> **The first sword (present**)
>
>
> "My first sword was so sharp, strong and fierce that none could withstand it. With it in hand, I strive for mastery by
> challenging all the heroes of the Northern Plains in my teenage
> years."[4](https://i.stack.imgur.com/Qb2NK.jpg)
>
>
> **The second sword (not present, represented by a wooden tablet)**
>
>
> "My second sword was violet in hue and flexible in motion. I used it in my 20s. With it, I have mistakenly wounded righteous men.
>
>
> It turned out to be a weapon of doom that caused me to feel remorseful
> endlessly. I cast it into a deep canyon."[5](https://www.youtube.com/watch?v=fCMft1IWcJw)
>
>
> **The third sword (present)**
>
>
> "My third sword was heavy and blunt. The uttermost cunning is based on simplicity. With it, I roamed all lands under Heaven
> unopposed in my 30s."[6]
>
>
> **The fourth sword (represented by a wooden sword)**
>
>
> "After the age of 40, I was no longer hampered by any weapon. Grass, trees, bamboos and rocks can all be my swords. Since then, I
> have developed my skills further, such that gradually I can win
> battles without reaching for weapons."[7]
>
>
>
[Answer]
As I remember medieval knights used lances as one of their main weapons. After heraldry became fashionable in the 12th century, more and more knights adopted coats of arms.
In medieval England, and maybe in other medieval countries, there developed two grades of knights. A knight bachelor was the lower grade of knight. A knight bachelor had a small flag called a pennon attached to his lance, which was triangular or fork-tailed/Swallow-tailed, and that flag had the knight's coat of arms on it. So every time that a knight bachelor tried to lance someone in battle, he would be trying to use his flagstaff, which was his lance, as a weapon.
A knight banneret had a tall rectangular or square banner with his coat of arms on a lance which was carried by someone else who accompanied the knight banneret, in addition to or instead of a pennon on the knight banneret's lance.
In post medieval times, armies had specialized cavalry units of lancers who used lances. And in many units every lance of every lancer had a small flag. So every time a lancer in those units lanced someone, he was using his lance both as a flag staff and as a weapon.
>
> The mounted lancer experienced a renaissance in the 18th and especially in the 19th century. This followed on the demise of the pike and of body armor during the 17th century, with the reintroduction of lances coming from Poland and Hungary. In both countries formations of lance-armed cavalry had been retained when they disappeared elsewhere in Europe. Lancers became especially prevalent during and after the Napoleonic Wars: a period when almost all the major European powers reintroduced the lance into their respective cavalry arsenals. Formations of uhlans and later other types of cavalry used 2-3 m (6.5-10 ft) lances as their main weapons. The lance was usually employed in initial charges in close formation, with sabers being used in the melee that followed.
>
>
>
[https://en.wikipedia.org/wiki/Lance#18th\_and\_19th\_century\_revival[2]](https://en.wikipedia.org/wiki/Lance#18th_and_19th_century_revival%5B2%5D)
In modern armies regiments and battalions had flags called colors and standards carried on poles with lance heads, and some companies have flags called guidons carried on poles with lance heads, and such flags were carried in battles until about 1900, give or take a few decades, in various armies.
As I remember, in one battle in the US Civil War, a Union cavalry Guidon bearer used the lance he was carrying his guidon on as a weapon against a rebel soldier.
In 1077 opponents of Henry IV, Emperor of the Romans, elected Rudolf of Rhinfelden, Duke of Swabia, as anti king of the Romans and future emperor. The rebels defeated the imperial forces at the Battle of the Elster on October 1080, but anti king Rudolf was mortally wounded.
>
> Although a military defeat for Henry, Rudolf was fatally wounded, when one of Henry's knights cut off his right hand and stabbed his belly with his sword. Rudolf died of his wounds the next day and his body was laid out in Merseburg Cathedral, where the chopped-off hand is still kept. With Rudolf no longer a threat, the rebellion had lost its focus. Henry conquered and demolished the remaining fortresses of Rudolf's troops. He declared the loss of Rudolf's Schwurhand a judgement of God, further weakening the support of the prince's rebellion.
>
>
>
Godfrey of Bouillon (1060-1100) was Margrave of Antwerp from 1076 and Duke of Lower Lorraine from 1089-1086, and later led the First Crusade. William of Tyre's chronicle, written c. 1170-1184, says that Godfrey of Bouillon carried the Emperor's banner at the Battle of Elster and lanced Rudolf of Rhinfelden with it.
So it has been claimed that a very famous historical character used a flag to kill another famous person.
And I happen to have idea for a story in which someone is attacked in an office and grabs a flag and uses the staff like a quarterstaff to beat his attackers and drive them back. Then one of his drunken attackers climbs on a desk and jumps at him and he instinctively points the flag at the attacker who impales himself on the lance head of the flagstaff.
[Answer]
Flags can be weapons of opportunity, of course.
A recurring means used by suicides to achieve their goal when circumstances offer no better tool is to use bed sheets as a mean to hang themselves.
And is a flag too different from a bed sheet? And what if it's not used by an aspiring suicide, but from an aspiring murderer?
A steel wire extracted from the wrist clock is surely cooler, but also a flag can be effective at permanently incapacitating your opponent.
[Answer]
Yes.
[](https://i.stack.imgur.com/QOnn5.png)
<https://www.npr.org/2016/09/18/494442131/life-after-iconic-photo-todays-parallels-of-american-flags-role-in-racial-protes>
>
> We all know the photo: It captures the rage, division and the racial
> tension from 40 years ago that is still so present now in our country.
>
>
> Titled "The Soiling of Old Glory," the photo won a Pulitzer Prize for
> breaking news photography. Stanley Forman took the picture on April 5,
> 1976, for what was then the Boston Herald American.
>
>
>
I think we don't all know the photo as the author presumed. This is what the Simpsons episode referenced. It is a weighty and meaningful thing, to use the symbol of your nation as a tool to hurt.
[Answer]
At a basic level, a flag and its flagpole is a staff with a cloth bound to one end of it. The user will attack by bludgeoning the opponent with the pole or wave the flag in their face as a distraction for somebody else.
But if the plan is to use it as a weapon, we can do a lot better. For a start, we turn the flagpole into a spear. A spear already works by holding one end and thrusting so the the pointy end goes in the bad guy. Something that has not been stated as of now is that the flag itself can be wrapped around the pole when not being employed as a flag.
A lightweight but sturdy metal pole with a flag of hydrophobic fabric (for repelling blood), using modern technologies to make the whole ensemble more durable all around and more lethal in parts is certainly achievable. Possibly using modern or futuristic tech to enable quick actions with the flag itself without having to worry about a large amount of specialized training to use it as a weapon fully.
### Raising the Flag
The first use is as a flag. As stated, it provides information as to who you are and represent. It is more to prevent friendly fire than to identify yourself to the enemy. Thus, its first use in combat is as a rallying point for your side ... and a target for the other side.
Second use is as a spear. With a spear tip attached to the pole end, it becomes a passable spear that can stab your enemies or clobber them with the pole itself if necessary. In this mode, the flag is either used as a flappy-flappy distraction for others, or wound around the pole so as to not be horribly distracting to yourself
Third is to ditch the flag itself and use it as a staff. Unless your flagpole has some manner of quick release mechanism for the flag itself, my thoughts would be that this is really only employable if the flag is rolled up, or more likely broken off the pole by an opponent. Be wary of the spear point that may still be on the pole though.
Depending on the futuristic parts of your tech, you could install a forcefield generator within the pole and have it makes a protective shield when planted in the ground and activated. Turn it into a rallying point for your troops when the giant lasers are fired, using the flag as a giant heat sink for the generator in the flagpole or something equally technobabble.
Alternatively in the Future Tech department, hiding any sort of weapon in the flagpole is an option so long as it is still usable. It might be slightly impractical, but it is something to consider.
### Flags Incorporated
Incorporating it into your society is something to think about. If the position of Flagbearer is one of honour, then maybe they are a chosen troupe that are taught a martial art dedicated to using the flagpole as a weapon. Potentially they are an honour guard for important people, designed to be unobtrusive until it is time to act.
Perhaps you are a nation that likes their flags. If every house has one, then maybe learning how to use a spear/staff becomes the basis of the militia training when guns are no longer usable, either due to range, availability, or other factors. This would be in a similar way of peasants of old weaponizing anything when called to arms. In a modern sense, then answer is almost certainly more guns/blasters/lasers, but a flagpole is innocuous until used to clobber the enemy. Modern technology might incorporate quick-release mechanisms to planted flagpoles, allowing them to be pulled out swiftly to save time.
### Reference Material
In Fate/Apocrypha, the Ruler class servant summoned to oversee the Grail War fights with a flagpole complete with flag for almost the entire time. When she uses it as a weapon, it is typically employed by rolling the banner up around the pole and bludgeoning things with it. While not everything might translate to a regular person's ability, it might form the start of something.
There is also the planting it to make a magical barrier against attacks Noble Phantasm, in which case the banner flies in the obviously dramatic magical winds.
Granted, she does not carry it around with her all the time, but it is treated as her primary weapon for the series.
[Answer]
End of Logan's Run (1976) fight in courtroom.
An improvised weapon; anything can be a weapon in a time of need.
In a future society, flag-duelling could be a ritual affair, possibly with big corporate sponsors (plenty of space for advertising on those flags).
[Answer]
A flagpole is either
1. an improvised weapon of last resort
2. a ritual weapon, possibly because it limits damage
A flag by itself is a useful tool for blinding or distracting your opponent, or hiding what you are doing, or entangling your enemy's weapon. A flagpole is a staff of greater or lesser flimsiness. Combining them means that your blows are hindered by the weight of the flag and risk you losing control because your opponent seized the flag and doesn't let go, and your use of the flag is hindered by the need to move it whenever you want to actually hit.
Any character stuck using a flag as a weapon and not prevented from doing so by ritual rules or lack of time will tear the flag off as soon as possible and use them separately.
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[Question]
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i want to make renaissance era armies that are large in size and able to travel far( without plundering for resources) but I'm running into a problem regarding how to feed them since there is no industrial farming or preservation. (to support large armies traveling far away from the homeland)
some important info for the solution
* they are stuck in the renaissance era (originally in the late 1900s) but medicine and hygiene and philosophy have advanced.
* the army is run by a powerful and well-connected government
* the land they travel to is just normal plains the reason that they don't steal from the land is because of the highly regulated military court system.
* the country is well connected by water channels that are well guarded, but these channels do not extend outside the country border, rather the land they travel have few rivers but aren't enough to be used for supplies transport.
[Answer]
There were already many food preservation techniques used by sailors and armies by the renaissance that allowed them to store food for months or years if need be. Flour can be kept and only cooked into bread/biscuits/etc as needed giving you a reliable source of carbohydrates. Dried and salted meats give you proteins. Certain cheeses can last a long time without refrigeration.
Fruit is your hardest major food group, but by the mid-1700s many sailing ships would carry oranges, lemons, and melons and by the the late 1700s, lemon juice was used to replace fresh fruit because it lasted longer. If you are going back with modern knowledge, your time traveler might know that adding fruit juice, dried peppers, or chilies to the menu would prevent scurvy and allow long term preservation of all your needed food groups.
As for bulk: the answer is plantations. Plantation style farming was common in many ancient civilizations such as Rome and Greece, and was later revived in the renaissance using Irish, Native American, and African slave labor. Basically, as long as you are willing to exploit a considerable % of your population to make all of your food while giving them less than their fair share, you can produce a large enough excess for a non-agricultural urban culture and permanent standing military without needing industrial farming. In fact, the revival of farmer exploitation in this manner is sometimes cited as a contributing factor to the the rise of urbanization that allowed the renaissance to happen.
There are also certain crops that offer notoriously good returns on your labor compared to others. Potatoes and Yams for example give a far better caloric return for your labor than wheat or berries. Focussing on high return crops like that would also allow you to better feed your people off of fewer farmers per capita.
[Answer]
Historically, Japanese armies faced exactly this issue.
What they started doing was carrying around miso paste and mixing it with boiling water to make soup. Lightweight, nutritious, easy to produce, and tasty. No factory farming required, and preservation isn't really an issue.
You may not want to call it "miso", you could say it's a bean paste or say it's from some made-up plant.
Edit to add: miso is surprisingly high in calories, protein, fiber, and vitamins. It's really very nutritionally dense. That being said, I was thinking about it some more and a different route would be to follow the indigenous north american example and make pemmican (which is also extremely nutritious). Unfortunately, that requires access to meat and that may be hard to come by in sufficient amounts. Either plan requires plenty of planning beforehand so that the army has time to either plant many beans or raise many animals.
[Answer]
I found this excellent answer on the history stack; original linked. If you like it, go upvote the original!
<https://history.stackexchange.com/questions/174/how-was-napoleons-invasion-of-russia-supplied/176#176>
>
> There were four main methods of supplying troops during the Napoleonic
> period;
>
>
> (1) The individual soldiers would be issued with rations that they
> carried in their knapsack. Enough for about two weeks. This was often
> in the form of biscuits.
>
>
> (2) Cattle or other animals were herded along and slaughtered along
> the way but these increased the grazing requirement.
>
>
> (3) Wagons following in the supply train. The main component of which
> was normally flour. Periodically they would stop construct ovens and
> bake biscuits..
>
>
> (4) Living off the land and foraging...
>
>
>
Comments noted French soldiers also carried cheese, which I would like to have if I were a soldier, or if I were not. Napoleon is later than Renaissance but people like to talk about his armies because there were records and organization and Napoleon's campaigns in some respects predate the later industrialization of warfare.
As regards where this food comes from (for points 1 thru 3; point 4 is stolen food) it is sold to you by family farmers who grow more than their family needs and sell it, or you claim some of what they have grown as tax. This is how small scale farming works. It is inefficient because you must buy from multiple small farms to accumulate what you need but so be it.
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[Question]
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I have some research that it needs a good space suit to protect you from heat and cold but I need more so, what does planet mercury need to sustain life for humans? what could we as humans do to have the things that mercury need to sustain life?
[Answer]
A scifi trope I've now seen more than once (KSR's *Mars* trilogy and later works, also Stross' *Saturn's Children*) is the idea of a habitat on rails that drives around Mercury remaining on the [terminator](https://en.wikipedia.org/wiki/Terminator_(solar)) (eg. the night/day boundary). This involves the train being propelled by thermal expansion of the rails caused by sunrise to ensure that the system can operate in an entirely passive and unpowered way, though other means of power would also work (but have different mode of failure).
You'd want plenty of emergency escape boltholes underground where you could be safe from the sun in the event of having to abandon the train. Honestly, cool-factor aside, deep underground is probably the most sensible place to live, and deep underground on Mercury isn't going to be *vastly* different from being deep underground on any other rocky world, gravity and mineral availability differences aside. Once you're down there, the business of building hollow living spaces, sealing and pressurising them and filling them with stuff you want like air and farms and what have you, isn't going to be uniquely mercurial.
Actually, the most senisble thing to do would be to stay in orbit, probably. Stay on the dark side so your safe from solar radiation. Or just not visit the planet at all, and leave it to the machines. There'll be more pleasant and hospitable places to go, by the time humanity is capable of colonising Mercury.
[Answer]
Mercury’s axial tilt is only a few degrees so the ideal place to build a base would be at one of the poles. With the sun effectively circling the horizon a modest sized crater would provide areas of perpetual sunlight on the rim, areas of perpetual shade at the bottom and areas where sunlight and shade alternated every 50-60 days or so around the crater walls.
In addition [polar craters](https://www.space.com/38274-mercury-has-surprisingly-icy-north-pole.html) are believed to contain some water ice
So they would be an absolute go to place for a Mercurian base providing ample heating and cooling, plentiful potential for energy production, water, oxygen and rocket fuel. The crustal rocks are also high in aluminium and silicates that could be used for construction work.
The major problem is getting there at 13 km/s deltaV from *low Earth orbit* to the surface of Mercury.
[Answer]
It depends what you mean by sustain life. If you're happy for people to live in sealed environments then this is a feasible, if challenging engineering challenge. Living outside of a sealed environment would be so difficult to be impossible in my opinion.
Mercury is very close to the sun, and spins slowly. This means it is both very very warm (the side currently facing the sun), and then very cold (the side facing away) - varying between -173 Celsius and 427 Celsius. The polar regions are merely a frosty -93 Celsius but at least that is constant due to no major axis tilt.
Thus a Mercury habitat would either need to be able to endure extreme cold(a polar habitat), extreme heat and extreme cold (an equator habitat), or through a different engineering problem neither.
Mercury "rotates" at about 10.8 km/h at the equator. Thus if a mobile habitat were to move at 10.8 km/h along the equator it would remain in the same degree of shadow relative to the Sun. There is some hypothetical point near the terminator of Mercury (ie the point of sunset/sunrise) that is neither too hot or too cold, and would require less insulation / cooling. This is still a very difficult challenge, but another option to consider for a Mercury habitat.
[Answer]
As mentioned in other answers, living underground is the most likely and plausible means of survival on Mercury.
However, living in a cave is pretty depressing, and fails to take advantage of some of the features of the environment. I would suggest that the colonists would dig a huge shaft at each pole, and cap it with a transparent, radiation prof cover (perhaps a cap of transparent material like diamond with 5 m of water between the plates). A mirror on the surface or in orbit reflects some of the available sunlight through the clear end cap and into the shaft.
The Colonists live in a city which essentially lines the shaft. Here they are protected from solar radiation and the thermal extremes, but have access to abundant sunlight for gardening and living in a pleasant, semi tropical environment. Trees and plants can line the walls in planter boxes, providing both natural colour and providing part pf the ecosystem for the colony. Ice and other elements needed for the life support system can be sent sunwards via mass driver or using a solar sail to kill the orbital velocity around the sun, and these facilities can be located in orbit or on the equator, providing a high level of safety (a missed cargo can crash on the surface without affecting the city). Similarly, mining operations and mass drivers to send metals to the outer solar system are also located on the equator, well away from the dwelling areas. Temporary or semi permanent "camps" can be set up around the machinery for work crews to monitor and repair them, but this will be like living at a mine site or an offshore oil rig, not permanent accommodations.
So living on Mercury is possible, and there are many possible options that future colonists could take.
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[Question]
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The basis for this question is the selected answer for [Plausibility of Mushroom Buildings](https://worldbuilding.stackexchange.com/questions/141173/plausibility-of-mushroom-buildings). Prototaxites and braket fungus are the likely candidates but I want to know if this type of fungis can float on water or not, so that it can be used to build a ship.
My question is not restricted to that fungus, it is just generally about the possibility to build ship with giant mushrooms. If simple giant mushrooms can do it and can be hard enough to withstand ocean waves, impacts and other nautical challenges in order to be viable as a ship then it's good enough.
Feel free to suggest new solutions or alternatives from any fungal or fungal-like organic material if prototaxites and braket fungus is not suitable to build ships with, as long its not the obvious trees and metals as materials.
[Answer]
Ships can be built out of teak, a wood that doesn’t float. So whether the fungus floats is not important.
It does need to have a measure of rigidity and strength to be used for constructing a hull or mast. I can’t see any info on the material strength of this extinct fungi. But, most fungi when dried become porous. I imagine it could be soaked in resin or a mixture of tar and pitch and that would make it kind of stiff and hard. Then it could be used for some type of watercraft or ship, depending on its strength.
Rigid but moderately strong materials could used for rivers and coastal crafts. And, for limited applications, it could be used for seawater craft. I liken the type of material to balsa wood. The explorer Thor Heyerdahl built his vessel out of balsa and sailed from South America to Polynesia.
[](https://i.stack.imgur.com/4WArI.jpg)
Very rigid and strong materials could be used as a wood substitute and any kind of ship could be fabricated from it
[Answer]
A material doesn't have to be less dense than water to be viable for a hull. All ships sink if they take in water after all. If they were all made of materials less dense than water, at the very worst they would float poorly after taking in water and/or enough hull damage.
Ships float because the volume of water they displace is heavier than them. In a sense, the ship and its contents as a whole are less dense than water, even if the ship's structure is made of something denser than water. In layman terms, a ship's hull may be heavy, but it is hollow and the things filling it up (including air) are in average lighter than water.
That is not all, the hull needs a proper shape to make the most of the water pushing it upwards. I won't get into hydrodynamics here though.
Your hull must be strong enough to:
* Support its own weight and cargo;
* Keep its own shape under a lot of pressure.
We will probably never know the structural properties of prototaxites because they are extinct. But there is a company called [The Living](http://www.thelivingnewyork.com/) that is making bricks out of mycelium (the structural stuff of fungi):
If bioengineering can be used to make bricks, I don't see why it could not be used to make hull boards. We just have to tweak with the mycelium's structural properties until its tenacity, hardness, strength and maleability are close to that of wood.
In fact, if we ever manage that, fungal boats might become a thing. Fungi can be made to grow into arbitrary shapes much more easily than plants. They also feed on practically anything that has once been alive and don't require sunlight. Who knows, they might be cheaper and better than wood if we ever developed the technology.
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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.
What sort of force would a railgun need to produce to have a measurable affect on the trajectory of a large spacecraft?
In the scifi book I am working on the primary craft of the story is a military ship classed as a heavy destroyer and equipped with 3 massive railguns that extend along the central spine of the ship. As none of them can be directly in the center, I am mainly wondering if firing them one at a time would have enough force to cause the trajectory of the ship under power to alter slightly, or if the ship not under power might start to rotate along its length (like a helicopter, not a bullet).
Obviously, that would depend on the mass and velocity of the projectile, but when trying to determine a feasible mass the math got a little beyond me. Therefore, I have settled for determining minimum force, as that should allow me to come up with possible weight and speed of the payload. Likewise, if it turns out that the difference would be negligible or impractical/impossible, then I can just move on with the story and completely ignore the possibility all together.
For a clearer analogy of my concern: If I shoot a gun and it pushes my right shoulder back so that I end up turning slightly to the right, how much force would I need to make a spaceship do the same thing?
I'm not sure what values might be necessary, but I have some rough numbers that I imagine might be helpful:
Ship Length: 330 m
Ship Width: 60 m
Mass: 35,000 t
Railgun offset from ship center axis: 8 m
If it matters, assume ship center of mass is equal to geometric center. Please let me know if there is anything else I'm not considering.
[Answer]
Alright, this is my first answer on Stack Exchange, so let me know if I've made any grave mistakes in my analysis. These numbers are *definitely* back of the envelope calculations, but they do give a good picture of what's going on in your ship.
**TL;DR** Yes, it will rotate the ship, but it's nothing that the ship's thrusters can't compensate for if your ship is designed to even move ***at all***. In the context of your story, I wouldn't worry about it.
**Long answer:**
What we need to find is the maximum impulse your ship can impart onto the projectile without exceeding the maximum corrective torque that can be produced by your thrusters. This is because *any* torque put on the ship is going to cause a change in trajectory, even if basically infinitesimal. We'll set up an equilibrium with the torque produced by the impulse of the railgun and the force provided by the thrusters. I'm also going to assume that your thrusters are mounted at the edges of your ship, but you can change the variables to match whatever configuration you want.
Just to get an idea of the magnitude of the forces you're talking about, using the definition of torque $\tau = I\alpha$ (I is your moment of inertia), the angular acceleration caused by your railgun is going to be 3.2 x 10^-11 times the reaction force of the railgun, based on the dimensions and mass of your ship. Here's the calculation:
$$
\tau = I\alpha
$$
$$
I = \frac{m(a^2 + b^2)}{12}
$$ Assuming that your ship is a rectanglular plate (thickness doesn't affect distrubution of mass [and moment of inertia] in this calculation)
$$
Fr = \frac{m(a^2 + b^2)}{12}\alpha
$$
$$
F = \frac{m(a^2 + b^2)}{12r}\alpha
$$
$$
F = \frac{(3.18 \* 10^7 kg)((60m)^2 + (300m)^2)}{12(8m)}\alpha
$$
$$
F = 3.1 \* 10^{10}\alpha
$$
$$
\alpha = 3.2 \* 10^{-11}F
$$ (Note: this constant of proportionality does have units, but they're not important if we're just using this as a ratio between force applied and angular acceleration)
A factor of 3.2 x 10^-11 is really small. To put a 0.1 degree per sec^2 angular acceleration on your ship (a pretty minor acceleration), you need *5.31 x 10^7* Newtons of force. I think the highest thrust rocket engine we've built, the F-1, produces 6.6 x 10^6 Newtons of thrust. You'd need the equivalent of 8 of those just to get your 0.1 degrees per sec^2 angular acceleration. And that's just the force the railgun would have to make.
Let's say your railgun has a muzzle velocity of 5 km/s (over Mach 14!) and accelerates your projectiles over the whole 300m length of your ship. From basic kinematic equations, this means your projectile takes 0.12s to get from the back to the front of your ship when starting at rest. The projectile's acceleration is 41,700 m/s^2, and now to find the reaction force due to this, just multiply the mass times the acceleration. We'll assume 1000kg (and yes, a 1000kg metal rod going at Mach 14 will do a *lot* of damage). This gives a force of 4.17x10^7 Newtons, which is pretty close to the force required to make a 0.1 degree per sec^2 angular acceleration.
Now, the torque produced by your corrective engines will have to be the *exact same torque* as the torque produced by your railgun to keep the ship from gaining angular velocity. This is where the width of your ship comes in: the radius from the center of mass to the edge of your ship is 30m, and your railgun is at 8m. The ratio between the two is 3.75. This means that your engines can be 3.75 times as weak (or 0.26 times as strong) as your railgun. In this case, the engines will have to put out 1.11 x 10^7 Newtons of thrust, or about two F-1 engines at full power. On a ship your size, this isn't unreasonable.
Anyways, all that calculation was just to show you that although the railgun puts out a (much more than a literal) ***ton*** of reaction force, the ship's thrusters have to be at least one or two orders of magnitude greater than this just to get the ship moving at any reasonable speed. Just to get your massive 35,000-ton ship accelerating at 10 m/s^2, you need 3.18x10^8 Newtons of thrust, so correcting for railgun blasts should be well within the tolerance of what your maneuvering engines can provide. I hope this helps.
[Answer]
**Simplest case: fire the projectile in radial direction.**
The sum momentum of the whole system has to stay equal.
$$ \bar I\_\text{ship} = m\_\text{ship} \bar v\_\text{projectile} \\
\bar I\_\text{projectile} = m\_\text{projectile} \bar v\_\text{projectile} \\
\Sigma \bar I = \bar I\_\text{ship} + \bar I\_\text{projectile} = \text{const.} \\
m\_\text{ship,t0} \bar v\_\text{ship,t0} + m\_\text{projectile,t0} \bar v\_\text{projectile,t0} = m\_\text{ship,t1} \bar v\_\text{ship,t1} + m\_\text{projectile,t1} \bar v\_\text{projectile,t1}
$$
So if you fire a projectile perpendicular to the ship axis, the ship gets a momentum in the other direction, equal to the projectile. So if the masses do not change, you can solve it this way:
$$ \bar v\_\text{ship,t1} = \cfrac{\left(m\_\text{ship} + m\_\text{projectile}\right) \bar v\_\text{ship,t0} - m\_\text{projectile} \bar v\_\text{projectile,t1}}{m\_\text{ship}} $$
So if your ship is not moving and you fire a 1t projectile with 35000m/s velocity, your ship starts to move in the opposite direction with 1m/s velocity.
**More complex case, fire the railgun in tangential direction**
If you fire the railgun tangential to the ship, your ship starts to rotate. In this case I would use the energy conservation, it's simpler.
$$ E\_\text{rotational} = \cfrac{1}{2} I \omega^2 = E\_\text{kinetic,projectile} = \cfrac{1}{2} m\_\text{projectile} v\_\text{projectile}^2 $$
$I$ is the inertial momentum of the ship, it depends mostly on its [form](https://skyciv.com/free-moment-of-inertia-calculator/). $\omega$ is the angular momentum: $2 \times \pi \times \frac{1}{T}$, where $T$ is the time it takes for the ship to rotate once.
**Even more complex, do both**
In this case you have to decompose the speed of the projectile in tangential and radial direction. Use the radial speed in the first formula and use the tangential speed in the second formula.
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[Question]
[
What would it take to build helicopter blades that can fold in several parts?
This is the continuation of [a question on Aviation](https://aviation.stackexchange.com/questions/66267/are-there-any-helicopter-blades-that-fold-in-the-middle). Unfortunately, there have been no use case for this for existing helicopters, so no-one has spent millions trying to work out if it was possible, let alone how to do it. As far as real life is concerned, folding helicopter blades at the rotor hub is good enough. As such, the question seem impossible to answer on a more reality-grounded place like Aviation, hence why it is continued here.
Assume that I have developed a magical [helipack](https://en.wikipedia.org/wiki/Backpack_helicopter), or some other sort of ultracompact helicopter with a magical black-box power source. The helicopter itself is either contra-rotating or tip-jet to avoid the need of a tail rotor.
The problem is that while the helicopter itself is extremely compact, there is this enormous rotor and its long, long blades that get in the way when not flying.
Folding them at the rotor hub, as is done with conventional helicopters, helps a bit. However, blades of several metres long don't fit into the nice little backpack like everything else. For that, I need rotor blades that fold in several parts as well.
**How would a rotor blade that can fold in several parts be designed?** How good would it be as rotor blades? How much more would it mass?
Less-than-ideal blade efficiency is an acceptable tradeoff, as is (obviously) increased complexity. As the outer edge contributes more than the center, it is also acceptable to have the blade not generate lift from the inner parts, as long as the loss of efficiency is not too severe. However, the thing must be reasonably safe, so we want to avoid it falling apart as soon as one pin breaks.
If the design would be different for a conventional (contra-rotating) system or a tip-jet, please point out the differences (or their absence).
Bonus points if the blade can unfold by spinning it or in some other automatic way, so the user can press a button, deploy the rotor and have it open by spinning - allowing them to instantly fly off while screaming "I'll get you next time" at the heroes who just foiled their plans. Having to stop and unfold them by hand would simply not be as theatrical.
Extra-bonus points if it can also fold back automatically after stopping it. Again, not having it to fold it yourself right after landing, wasting no time to Save the Day, just looks better.
[Answer]
Different choppers with folding blades fold them in different distances from the hub. Look at the [AH-1Z Viper](https://en.wikipedia.org/wiki/Bell_AH-1Z_Viper):
[As Ash said](https://worldbuilding.stackexchange.com/a/151010/21222), where and how wings are folded has to do mostly with material strength. You may wish to have joints like those of the [V-22 Osprey](https://en.wikipedia.org/wiki/Bell_Boeing_V-22_Osprey):
Its blades are short compared to its body, and the joint seems pretty sturdy compared to regular civilian choppers with folding blades.
[Answer]
The rotor design on a toy helicopter I saw recently suggests its a matter of material strength rather than any technical difficulty. Those blades were in three sections that folded away for storage and folded out under tension when spun up. The problem is that those wings had to be made of cast aluminium with high tensile steel pins and they were on the order of only 100-120mm long when extended; helipacks, like the ones in the linked article, have 6m+ wingspans so the forces acting on the wing blades are much greater. Unfortunately I don't have the expertise to work out what would be required, nor the time, or patience, to work it out from first principles today, hopefully someone else can help you with that.
[Answer]
A good estimating starting point is to look at the force on a point of the blade, and compare the relative force for a hinge point near the root against one near the middle or the end of the blade. For simplicity, I am thinking of what I will call a unit rotor blade: 1 unit long, mass of 1 unit, of constant geometry and therefore constant mass per length. Consider the [formula for the force required to keep a mass on a circular path](https://en.wikipedia.org/wiki/Centripetal_force):
$$
f\_c = m\frac{v^2}{r}
$$
where $f\_c$ is the force, $v$ the linear velocity of the mass, $m$ is the mass value, and $r$ the radius of the circular path it is traveling. But the linear velocity is affected by the radius, where:
$$
v = \dot\theta r
$$
$\dot\theta$ is the angular velocity, and $r$ is the radius of the circular path. When we substitute this in to our first equation and simplify we get:
$$
f\_c = m \dot\theta^2 r
$$
I am going to assume a constant angular rate. Unless the blade is a noodle of some kind, it will either all rotate at the same angular rate, or it will break into pieces as different parts move past each other. Since we want a functioning helipack, I think this is a safe assumption. Since I assumed a mass of 1 and a blade length of 1, the mass at any point radius $r$ is equal to $(1-r)$. Substituting that in and eliding angular rate for the moment, we get
$$
f\_c \approx (1 - r)r = r - r^2
$$
So what does this tell us? Lets look at a graph:
[](https://i.stack.imgur.com/63DVn.png)
As you can see, the relative force on the blade is highest near the center. This is a big problem, because if we want blades the fold down small, we are going to need blades that fold closer the the center than a traditional folding helicopter blade. If you compare a joint at 10% of the blade length with one at 50%, the one at 50% will need to be ~2.8 times stronger. If you want to fold the blades at 1/3 and 2/3 of the length, then you need two joints, each stronger by a factor of ~2.5.
This issue is probably somewhat ameliorated by the fact that most wings (and rotors are wings) will taper to the tip, but that is only possible because the centripetal force we have considered so far is not the only force, you also have to account for both lift and drag. If you assume that those are constant along the wing (possibly generous, I'm not sure), then those forces are somewhat less for joints further out. However, you also have to account for the fact that a joint with more force is probably heavier, and shifting that extra mass closer to the end of the blade means more of the blade will have to support it centripetally, and for centripetal force that also means that more mass will be concentrated in parts of the blade that are being spun faster, potentially further increasing the mass of the rigid sections.
From a reliability standpoint, there's no way it does not fall apart when one pin breaks. At high rotational speed, there's no graceful way to recover from becoming unbalanced like that. And that is ignoring the fact that even fixed rotor helicopters already have single points of failure, the proverbial [Jesus Nut](https://en.wikipedia.org/wiki/Jesus_nut) that holds the main rotor in place.
With all that in mind, and with the variety of exotic materials and low [factors of safety](https://en.wikipedia.org/wiki/Factor_of_safety#Choosing_design_factors) already in use for real world helicopters, I think it might be worth either thinking of some fictional material that makes this whole thing feasible, or trying to avoid a jointed rotor. You could think about something that is flexible or telescoping and deploys with the spin of the blades, though perhaps that is similarly infeasible, only for engineering reasons I am not aware of.
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[Question]
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**Closed**. This question needs [details or clarity](/help/closed-questions). It is not currently accepting answers.
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**Want to improve this question?** Add details and clarify the problem by [editing this post](/posts/147319/edit).
Closed 4 years ago.
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In my world, there is a race of shapeshifting creatures, capable of convincingly looking like normal humans in order to lure them and prey upon them.
These creatures, however, are non-sentient and non-conscious, a bit like the aliens in Peter Watts' [Blindsight](https://en.wikipedia.org/wiki/Blindsight_(Watts_novel)).
So what do they use to trick their human preys? They use telepathy.
These creatures can read minds and can therefore act like their prey thinks they will act. If one of these shapeshifters takes the form of a person and you stumble upon them, they will act like you expect, hypothesize or hope for, all depending on what you are actively thinking in that moment.
They can handle grammar and syntax just fine by talking like you form words and sentences in your mind, and they can process all the needed info just as fast as you think them.
Their telepathy also allows them to pick up on the preferred answer that their target hopes for, so if asked "are you a shapeshifter?" the answer will be invariably negative, unless you want them to be one (in which case you probably just want to commit suicide-by-shapeshifter, because no one hopes to meet one). Their answers will always be soothing, reassuring or enticing, simply due to them being "programmed" to go for the answer that makes you feel the least fear and the most curiosity or attraction. At the very least, their answer will be as non threatening as possible given the current thoughts of their prey.
Basically their telepathy allows them to communicate a bit like a [Chinese room](https://en.wikipedia.org/wiki/Chinese_room), again, just like in Watts' novel.
They have a few **limitations**, chiefly that they can only use their telepathy on one mind at a time and that they can't read anything other than what the person is actively thinking. However keep in mind that it's borderline impossible to have a conversation with someone without forming expectations or thoughts on their answers in your mind, which the shapeshifter will immediately use to its advantage.
They can only shapeshift into humans or human-like forms, both by imitating a person they have seen or preyed upon or by picking something out of the mind of their next victim if they are thinking about someone in that particular moment.
Other than this, assume that their **telepathy can't be blocked** or jammed in any way and that their shapeshifting abilities are perfect, so that **no physical evidence** can be used to unmask them.
However, people do know that they exist, though these creatures are not common enough to be a constant worry. Enough to get suspicious if someone acts strangely or looks out of place but not enough to be completely paranoid.
In answering this question assume that **no relevant technology is available** and that **no large scale countermeasures are possible**, such as anti-shapeshifter laws and customs, humans have only their own individual wits on a case-by-case scenario to save them from becoming a shapeshifter's next meal.
Also consider that shapeshifters only target humans that are alone or with just another person, so **they never approach more than 2 people.**
If the shapeshifter manages to be approached at [social distance](https://en.wikipedia.org/wiki/Proxemics#Interpersonal_distance) for more than a few seconds, there's no escaping, the shapeshifter will easily overpower up to 2 humans.
With all of this said, what kind of tactics and tricks might a human pick up to spot a prowling shapeshifter effectively?
[Answer]
One way to spot such shapeshifters is a variant of the *shibboleth*, in which you ask a question **whose answer you ignore, but are able to easily verify once it's given**.
For example you can ask the stranger to tell you two numbers and their sum, provided you aren't able to make the sum in your head yourself. A shapeshifter will not be able to come up with these numbers (much less the sum), unless it reads them off your active thoughts, which means that **you know the numbers, so they're not valid**:
"Tell me two numbers and their sum" (thinks "Sixtyfive and ninetythree is... er... one hundred sixty-eight? No, wait, fifty-eight")
Hears "Thirty-four and seventy-seven is one hundred eleven": okay.
Hears "Thirty-four and sixty-one is nineteen hundred": Haha, funny. Try again.
Hears "Sixty-five and ninety-three is (one hundred)fifty-eight": STOP THERE!
Once you hear the two numbers - meanwhile, you *concentrate hard* on adding some *other* number - you can verify the sum.
Again, most people will quickly pick a favorite pair, which means that they'll have a competing thought in their minds and think of the numbers *they* would choose if asked - but the chances of two people choosing the same pair are very slight. If someone utters the same numbers you were thinking, ask them to choose different numbers (and think of the *same* numbers). If they choose the same pair again, that's something only a nonsentient shapeshifter would do.
Whoever fails three sums in a row has to be a shapeshifter, or really *really* bad at math.
If you hear someone nearby, asked by someone else, uttering the same numbers you were thinking of, just say that aloud. In case, only ask someone after everyone else has moved out of their range.
Another better possibility would be to carry two large wooden dices, and throw them on the ground without looking at them, then asking the stranger to read the result, and finally check.
Or a box with a deck of large cards. Throw the box to the stranger, and tell them to shuffle the deck, then look at each card, announce it, and *then* show it to you. The shapeshifter won't be able to recognize the cards, nor to read them in your mind, and it cannot guess without the virtual certainty of being immediately caught. If it says "Queen of Hearts" and shows you a jack of spades, well.
In all these cases the one being tested must be the only one to see the test until it's complete - for this reason, the card deck is better. But again, a protocol would quickly be established so that everyone would know what to do if asked to pick up a card.
[Answer]
A deck of ordinary playing cards seems to be a pretty good solution. Give the deck a few good shuffles every now and then so the order is completely randomized and you have no way of knowing the order. Then, if you're having a conversation with someone that you aren't sure of, deal 'em a poker hand and ask them to name the cards they have. (You may want to get a safe distance away after giving them the poker hand, and possibly ready your non-anachronistic lethal weapon of choice.) Imagine a royal flush while doing so, or really any given poker hand of five cards. When they name their hand, just riffle through the deck. If they're human, they'll name the five cards that aren't there. If they aren't - well, then they've got a 1 in ~ 2.5 million chance of naming all five cards correctly, because those are your odds of correctly guessing those five cards. (My math might be a bit off - I just did a back of the envelope from poker odds.)
Now, if you've got tech or magic, a talking 8-ball is even better. Rig up one that randomly generates a color out of eight given (primaries and secondaries, plus black and white) and then will loudly announce the color after a five second pause. Toss the ball to the suspected NSNCTS and run about six rounds of it. Should only take half a minute, and the odds are 1/ 262144. The idea here is to give the target easily confirmed information that only the target knows at the time.
[Answer]
Assuming they can't do higher level reasoning by themselves:
1. Ask someone to curate a list of questions that you have never seen before. These could be combination of math questions like 10x43=? and open ended questions like "how can we solve world hunger?", **captcha style questions** like "how many oranges are in this photo?" Always keep this list with you, but never look at it.
2. When you think someone may be a shapeshifter, give them the list. Ask them to choose any 3 questions without telling you and write down the thought process/ answer somewhere. When you review the answers it should be clear if they are capable of independent thought or not (correctness does not matter, just the thought process)
Not sure if phones/computers are acceptable technology in your world, but it is simple to make an app specifically for this that generates random questions/captchas and can check the answers (no human involved = no chance of reading thoughts).
It is important that you don't know the problem already, since you might imagine the method to solve it, which they might read and follow. Imagining "the wrong answer" may not work either since your thoughts contain the information that the answer is wrong so they won't choose it (it is impossible to block your own thoughts about it). The only solution is to truly be unaware of the problem itself.
[Answer]
>
> people do know that they exist
>
>
>
I cannot imagine how the existence could be discovered of a predator whose total design is so conveniently ironclad.
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I imagine a person that suspects they're under threat would deliberately fabricate a fake person and then concentrate on that fake person while traveling through insecure areas. A community would immediately retreat into secure, isolated areas.
So, forgetting the absolute implausibility of how this could even be true: you are suddenly put on notice that one of these killing machines is in your area. You know, like an Amber Alert. What do you do? Well, your house is safe, so you can just keep the door locked and stay indoors. But you eventually have to get groceries. Before leaving, you pull out your book of Leeroy Jenkins fan-art and study it carefully until you have a really solid picture of him in your head. Then you go outside and hurry to the store, concentrating on Leeroy and how badly you hope to meet him, and pushing all other thoughts out of your head.
If a shapeshifter becomes aware of you before you notice it, it will shift into your picture of Leeroy Jenkins. If you meet Leeroy Jenkins, you will kill him.
If you encounter any other non-humans on your route, all of you will stay away from each other out of mutual distrust. If anyone approaches you, you will kill them.
[Answer]
**How smart are they?**
If you ask them a question that you don't know the answer to yet, but can figure out if you choose to, you're golden. Examples:
---
"Hey, what's behind me right now?" If they're a dumb shapeshifter (and they're not sentient, so they probably are dumb), they won't really know the answer. Then you turn around and verify their response.
"Pick a tree branch, and tell me how many leaves are on it"
"Go over there, and name as many objects as you can in that room"
Or the classic "How many jellybeans are in the jar"? (tell them to open the jar and count)
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[Question]
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I want to have a group of space colonists get stranded on a planet where the only way they can get enough nourishment is to gather or cultivate edible plants.
[Answer]
Sure.
All land vertebrates descend from bony fish. If those (or other equivalent) never evolve in your world, and land animals depend on a tracheal system or branchia to breath, they won't get much big.
How big they can get depends on the availability of oxygen in the atmosphere. Nowadays insects rarely grow larger than 10cm long, though some land arthropods can grow to be a meter long such as the coconut crab. During the carboniferous period, though, some dragonflies (meganeuras) could have wingspans of 70cm.
So low or normal O2 levels and no development of lungs ever will keep your land based fauna pretty small.
[Answer]
There are 2 distinct problems mentioned in your question:
>
> Could a planet evolve to have [a diverse fauna] - but no animal bigger than an insect?
>
>
>
Probably yes.
>
> Could a group of space colonist get stranded on a planet where the have to cultivate it's native fauna to survive?
>
>
>
Sure, but not on the same planet...
In spring the plants on this planet probably look similar to plants on earth. Some have flowers and rely on insects for pollineation, others have spores that are carried with the wind. But in autum, the seeds of almost all plants would be tiny enough to be carried by an insect or the wind.
Plants, especially trees, want to spread their seeds as far as possible to avoid competition for nutrients with their own seedlings. Without animals to carry seeds a long distance, there would be nothing like an apple, avocado, nuts or beans on this planet, because the energy required to grow such big fruits and seeds would be wasted.
Some plants could maybe form a symbiosis with an insect like a [Scarabaeus](https://en.m.wikipedia.org/wiki/Scarabaeus_sacer) that would roll their fruits some distance away, but ultimately those would be the exception and not enough to feed a group of people.
Another alternative are roots. On Earth we have potatoes and [cassava](https://en.m.wikipedia.org/wiki/Cassava) that are the nutritional bases for some people. Add in carrots, beetroot, turnips and other edible roots, and you have a realistic chance of feeding your stranded astronauts ... *in theory*.
Realistically those roots would look like their ancient, scrawny forms before the beginning of human agriculture. A plant only needs to store anough nutrients in it's root to survive a period of lack of nutrition. No more than that. Our modern root vegetables are all bred and selected to store more nutrients than required, in order to grow big enough to feed humans.
On a planet where the evolution perfected plants to grow and spread only with the aid of small insects, humans wouldn't find enough fruits, seeds or roots to survive.
[Answer]
# **You know Army-ants?**
[](https://i.stack.imgur.com/A3pIL.jpg)
Credits:
Von Der ursprünglich hochladende Benutzer war Karmesinkoenig in der Wikipedia auf Deutsch - Selbst fotografiert, [CC BY-SA 2.0 de](https://creativecommons.org/licenses/by-sa/2.0/de/deed.en "Creative Commons Attribution-Share Alike 2.0 de"), [Link](https://commons.wikimedia.org/w/index.php?curid=3387665)
## **Army ants are a good example for tiny creatures killing much larger ones.**
## Have your planet being inhabited by some aggressive ant-like insects frequently killing any large animals they find, so animals larger than the earths insects cant even evolve.
I aggree to Elmy that you most likely wont find large fruits on this planet, but:
## Some plants could evolve large roots and tubers in order to store carbohydrates over long cold or dry periods.
maybe the planet has very long years with a very long and mild but dry and dark winter and a very long and dry summer, so the plants have to store lots of water and nutrients in their roots in order to survive this.
[](https://i.stack.imgur.com/EHGi6.jpg)
Credits:
photo by Scott Bauer, USDA ARS [Public domain].
see [source](https://commons.wikimedia.org/wiki/File:Patates.jpg) for more information
roots and tubers could be eaten by your stranded spacetravellers,so they could find nurishment there.
## The travellers only have to find a way to get rid of the ant-like killer insects.
## For example, they could hide in their spaceships wreck.
## Maybe they build or use a flamethrower to fight the insects when they go out of the wreck to find nurishment.
Or maybe they have some insecticide on their ship, for example against parasites like mosquitos or ticks, and it works for that alien insects too.
Or maybe the alien insects cant stand some desinfectant your travellers use frequently, and the travellers note that.
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*Sure, just make the insects the biggest creatures on the planet*
[](https://i.stack.imgur.com/M6n8W.jpg)
<https://ghibli.fandom.com/wiki/Ohmu>
That way you can ensure no creature bigger than an insect evolves, problem solved :P
**Macroscopic Organisms Haven’t Yet Evolved**
In all seriousness, you could simply state that creatures larger than insects simply haven’t evolved yet. Plants dominated the earth long before the first macroscopic organism walked upon it.
Whilst *eventually* larger organisms would evolve and prey upon the abundance of insects, at the time of the human’s arrival no natural predators of insects have yet evolved. A very simple yet effective solution to your problem.
**Plants May Only Be Inedible to Insects**
An issue may be that plants evolved edible fruit so that animals would swallow the seeds and spread them after the edible portion had been digested. Your humans may struggle to find edible food.
However, that being said, coffee plants are a perfect starting point. Coffee beans evolved to contain a lot of caffeine so that, when an insect ate them, they would be overloaded and suffer a heart attack. Humans on the other hand are so large that the lethal dosage of caffeine is far higher than what a coffee bean contains. If the plants in your world evolved to only defend against insects, when a substantially larger creature comes along, their defences are useless. The fruits, berries, leaves, roots, flowers and even bark of plants may contain lethal dosages of caffeine to insects but are harmless to humans. You could also state that fungi evolved a similar form of defence.
Whilst i use caffeine an example, there may be other substances that are harmful to insects but would not kill a human at those dosages. For instance, i could imagine plants evolving a way to produce salt to defend against mollusks like snails or slugs, perhaps certain sugars could also harm an insect if concentrated enough. This allows you to have a wide range of human-edible food in a world that should not have edible food due to a lack of larger organisms such as deer.
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In Steven Gould's Jumper series, the main character has the ability to teleport, and he eventually realizes he automatically does frame matching when doing so - no matter where on earth his origin and destination are, when he arrives, he is perpendicular to, and at rest in relation to, the ground.
I'm writing a story with a teleporter without frame matching. This is obviously going to limit how far he can safely teleport without stumbling / breaking a leg / becoming a grease stain; but what are the actual limits? The bulk of the story will be set in and about Seattle, WA, USA; how can I calculate safe distances and directions, or know how fast he'll be sent flying in which direction?
Edit: He can only teleport to locations he has already been or can see; so location isn't going to be an issue, only velocity and orientation.
It might be that I'll get better answers on the Math site, so I'll be posting there in the morning if nothing comes up here; but I thought I'd give Worldbuilding the first stab at it, since I'm more active here. I'll gladly delete here if this is deemed improper here.
Edit: It has been suggested that this is a duplicate of [this question](https://worldbuilding.stackexchange.com/questions/131575), which only asks what potential downsides of retaining momentum might be; but this is not the same question, as I am asking how to determine how to calculate a magnitude and direction for a specific known issue.
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I think that without frame matching there will be severe limitations.
While I am sitting at my desk to write this answer, I feel I am standing still. However:
* planet Earth is rotating around its axis, and this gives me a certain velocity vector $v\_E$. This is 1668 km/h at the Equator, 0 km/h at the poles.
* the Earth is orbiting the Sun, this gives me another velocity vector $v\_S$. This is about 29.5 km/s
* the Sun is orbiting the galactic core, resulting in another velocity vector $v\_g$
* the Milky Way is also moving ...
Let's focus on the Earth rotation, as I assume you don't want to teleport outside of the planet.
The tangential velocity changes with the latitude L according to the law $v\_e(L)=R\_{Earth}\cdot \omega\_{Earth} \cdot cos(L)=1668 \cdot cos(L)$. If your character moves just 1 grade north, going from 44 N to 45 N, he will experience a difference in velocity of 20 km/h. For reference, crash tests are conducted at 30 km/h.
Moving East or West by an angle $\alpha$ does little better: the module of the vector will stay the same, only the direction will be different, so he will be moving up (or down) with a velocity $1668 \cdot cos(L) \cdot sin(\alpha)$. And the lateral velocity will be diminished to $1668 \cdot cos(L) \cdot cos(\alpha)$.
Let's say he goes from (45 N 0 E) to (45 N 1 E), he will be moving up with a velocity of 20 km/h.
And we are not taking into account the possibility of ending up on a moving object.
Long story short: he can move, but just few tenths of a degree per jump, at most. The closer he is to the poles, the wider is the safe range for the jump.
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Let's think about this in terms of the curvature of the Earth firstly; the equator is a bit over 40k Kms in length, meaning that there is approximately 112km per degree of change in aspect in real terms.
If the average person's centre of gravity is around 1m high, let's just say that by the time you get to 5o difference, or around 560km, it's going to be awkward to maintain your balance with that kind of instant change, but actual failure point to remain standing is going to be different for every person depending on how flexible, agile and prepared you are.
The truth is though that points of failure kick in a lot closer because the Earth is not a perfect circle. the ground is uneven, and without being very careful you can just as easily materialise with your foot half in a concrete path because you didn't notice a subtle incline.
Ultimately, your jumper in this context is going to learn a few tricks very quickly; lean forward for long jumps, jump higher than you need because it's safer taking a 30cm drop than it is having half your foot materialise in the middle of the road; that kind of thing.
Another thing he can do is actually start running while he jumps, as that might help with momentum change as well because he can jump while neither foot is actually on the ground. It will take some practice not to break his stride, but it's a skill that can be learned just like normal walking is learned at an early age.
So the actual failure points depend on the terrain, the balance and preparedness of the jumper, and thorough research into the altitude changes (inclines and declines) in the area in which your jumper operates. In other words, pick a flat area to operate in, practice hard, and do your homework. That way, you maximise the distance you can jump without incident.
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I like this. It's a reasonable teleportation limitation, and one with interesting consequences.
As mentioned in other answers, jumps of less than a hundred miles or so shouldn't pose too much of a problem. I suggest wearing a digital compass like a watch so that you know which way to brace yourself after a jump (you should also always aim a few feet off the ground when moving west, since you'll be driven slightly into the ground, which would be hell on your knees otherwise).
But say you want to quickly go larger distances - where could you go safely? Well, here are some cool, albeit specific, places, and how to get there:
* Get a friend to drive you at 112 mph west on a straight road. You can now safely teleport to the north or south pole. (Wear padded clothing, since in addition to the cold, you'll appear about to fall on your side if you go north, and about to fall straight down onto your shoulder if you go south. Also, no way to get back but the long way - dozens of smaller jumps.)
* Get a friend to drive you at 110 mph *east* on a straight road. Jump safely to San Francisco. (You can jump back to Seattle from the passenger seat of a car there moving west.)
Finally, the most helpful equipment for long-distance jumps: skydiving gear and a parachute. Everywhere on Earth less than about 50 degrees north or south (US and Canada, Europe, China, Southern Argentina, and New Zealand) is only moving at about 100 mph at most relative to the Earth's center. That means you can teleport 2 or 3 miles above your destination (that's approximately the cloud layer, so just look up when you visit and you should be able to save that jump location for later) and just skydive down. You'll be yanked sideways when you arrive, but not significantly faster than terminal velocity, so a skilled skydiver with enough time before the ground should be able to land safely. Of course, this task can be made arbitrarily safe by doing several jumps, say, 45 degrees longitude apart from each other, to mitigate this sideways wind.
Note: I've never gone skydiving, and I'm aware that even a 30 mph wind is considered dangerous, let alone 100-200 mph. But my understanding is that this danger is mainly in moving too fast relative to the ground, whereas in this case, the ground and "wind" are moving at the same rate, so it's moot if the diver has enough time to match the "wind" speed. I welcome any skydiver who reads this and wants to chip in - it would make for an interesting and surreal discussion.
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You are describing the "teleporting" flavour of the Azhiri, in Vernor Vinge's *The Witling* (1976). They can *reng* objects faster than light, from places they've been, but momentum is conserved, so renging a rock from the farthest Moon (the powerful Federates are an exception to the "You must have been there" rule) allows for nuclear-level strikes.
They have also devised water pools and can jump from one to another using ships in about 80-km jumps, with the pool absorbing the excess of momentum.
In your case, the velocity differential is about 0.6 m/s for each 10 km jump. Assuming our guy can teleport serially, he would need to visualize each successive waypoint and teleport there, then brace himself to adapt the new local frame vector. Up to 1.5 m/s per second is doable; it would become a sort of "speed walking" or "oblique jogging".
But I think the problem will be that **he won't be able to visualize exactly all the necessary waypoints** (and, if an error is possible, it might have disastrous consequences). He could do "emergency" long jumps at 80-100 km distance, shedding the excess 4-7 m/s with a [paratrooper roll](https://www.youtube.com/watch?v=fb4W1TBBGKI).
Or he could try for a Pierson Puppeteer's style of tele-transport: *very* short jumps to waypoints in one's line of sight. That would be 500m at most, so the velocity differential is completely negligible. Doing two jumps per second will give a virtual speed of 3600 km/h - around Mach 3.
Another possibility is to *fly* with a wingsuit. Jump high enough in the air, and start falling. Jump higher and farther (still line of sight, maybe two or three kilometers distant). After a while, downward velocity will stabilize on 30-50 m/s depending on the wingsuit affect, and forward "propulsion" will be supplied by teleporting. To land, simply glide down - or bring a parachute. Two teleports per second equal now a speed of Mach 10.
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The Earth has an equatorial circumference of 40000km and turns around in a day.
That is about 1660km/h. Seattle is at 47 degree latitude, where the radius to the axis of rotation of the Earth is reduced to 70%
The question is now, how much of a difference in velocity does a jump make? The difference in velocity vector jumping east/west is $2\*\sin(\frac{a}{2})$ where $a$ is the angle you are covering. A 100km jump gives you a speed of 4km/h, walking speed. You will need some training to not fall over, but that sounds doable.
If you jump north south, what matters is the change in rotation speed of the earth, so $(\cos(\text{new latitude}) - \cos(\text{old latitude})) \* 1660\frac{km}{h}$.
A 100km jump around Seattle will leave you there at 3km/h, slightly slower than E/W
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Okay, so I'm working on a novel and I'd like to have a dense asteroid field, something akin to the old ESB Hoth field, though it doesn't need to match that exactly. The notion is there is an advanced civilization going into such a dense field to pull out desirable mine-able ores. I'm looking for a plausible explanation for how such a field could form, and persist for at least around 100 years.
So my rough parameters for such a field:
1. Reasonably dense, with at least building size asteroids, up to city size would be good.
2. Dense enough that collisions between the medium sized objects are not uncommon.
3. Not dense enough to immediately form into a planetary body.
4. It doesn't need to exist for an extended period of time, though 100 years or so would be good, event as short as 5-10 years would be ok
I was thinking something like a collision of dwarf planets or possibly small moons would create such a field, on a short time frame at least. Eventually, I would assume either form a ring, collapse into a moon, or dissipate entirely, but for a while it would be a dense area of debris that would be hazardous to navigate.
So would that be a plausible explanation, or can anyone suggest a way for such a dense asteroid field to exist, even if only for a limited time. Thanks!
Update/Clarification #1:
First thanks for the answers so far.
Okay, I can see there being a bit of confusion here. What I'm looking for is a plausible explanation for a dense asteroid field similar to the one seen in the escape from Hoth in Empire Strikes Back. It need not be a long lived phenomenon in astronomical terms ( ie 10-100 years is good ), but would need to exist in such a condition for at least 10 years. It also doesn't need to be huge in terms of area, so something like a few thousand kilometers is fine, but with a minimal size of 10km in height / width / depth. The means of creating such a field can be natural or artificial. In the end I'm looking for a dense Asteroid field for use in a rough and tumble flight scene. Of course, if that is not possible, I can figure out some way to recreate the scene.
Thanks again.
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You USE a planetary ring system for this.
A planetary ring is stable across geological timescales by being well INSIDE the planet's Roche limit, therefore preventing itself from collapsing back into a moon.
Planetary ring system, for example, Saturn's ring system, is almost dense enough so that you can see small chunks of ice from the size of sand grains all the way up the size of houses.
[](https://i.stack.imgur.com/rU3Rs.jpg)
So if a gas giant large enough to have a large Roche limit radius, and one of its major moons fell inside such limit due to some reason like orbital perturbation or decay, it would disintegrate due to the main body's tidal forces, and the resulting ring system would be both thick enough for your average sci-fi asteroid thicket, and stable enough to last for GEOLOGICAL timescales--Saturn's ring is believed to have existed for more than 100 million years.
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**Your civilization made the impact field. It is the advanced civilization equivalent of strip mining.**
1. Blow up planet using advanced tech (Death Star will do fine).
2. Blown up planet exposes delectable planet guts. All that good stuff down deep.
3. Collect good stuff
4. Danger - it will be hot.
5. Danger - it will be trying to coalesce back into a planet
This is a much hotter and more action packed asteroid field than the duddy old Kuiper belt or some ice collection ring. Good heavy globs of metal will be floating around, glowing hot. Plus when you make it there is the bonus sound, like millions of voices suddenly cried out in terror and were suddenly silenced.
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## The Perfect Mining Prospect: [Proto-Planetary Disks](https://en.wikipedia.org/wiki/Protoplanetary_disk)
A widely accepted theory of planetary formation called the **[nebular hypothesis](https://en.wikipedia.org/wiki/Formation_and_evolution_of_the_Solar_System#Formation_of_the_planets)** states that during a star's first 100,000 years or so, the surrounding dust compresses into a disk and starts accumulating into clumps. Once these **[planetesimals](https://en.wikipedia.org/wiki/Planetesimal)** grow to a few kilometers, they start directly gravitating together instead of just bumping into each other. As larger proto-planets form, lots of the planetesimals get ejected from the system.
**A young star system transitioning from planetesimals to proto-planets would be the absolutely ideal place for interstellar mining.** For thousands of years, all of the orbiting mass of the system would be in nice, soft, bite-sized pieces, and before much of it is lost to deep space. It would be at the tipping point between large, quick hauls and minimal gravity wells to escape.
Such a chaotic landscape would be highly varied; some areas could be more safely exploited, while some particularly dense regions would appeal to daredevil miners willing to take risks for a big payout.
If you have interstellar travel, proto-planetary disks are where you go to mine. They also happen to be the best place to find tons of cool rock chunks slamming into each other.
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Beware of tightly packed asteroid belts, especially if they're mineral rich and safely floating by your home world's orbit within easy reach. They are traps! Lures to tempt you up into the darkness where your technology is more easily measured and threat assessed.
The Old Ones, who rule the inner spirals of our galaxy, know that we are out here. They know that intelligent life is the natural goal of the universe and that it erupts practically everywhere beyond their jealously guarded domain. They know that inevitably a greater intelligence will rise to threaten them. It is only the when and from where that is in question. The certainty that it will be is absolutely certain.
But as others here have explained, space is big and mostly empty. It is beyond even their vast power to monitor all that is. Deep time and deep space shroud us from their view. The fraction of a million years needed to rise from the caves to the stars is a blink compared to the galactic expanse which must be watched. From their point of view, the forest is too large and the prey too few.
So like any good hunter, the Old Ones lay traps full of tempting morsels.
It is child's play for them to cherry pick each solar system's oort cloud and assemble a mineral treasure trove as bait. Then with only a small exertion in stellar engineering, they set it all in motion. Through their design, the field can orbit the system's primary temptingly close to the potentially fertile worlds yet distant enough that those worlds' gravity wells neither disrupt nor steal from the asteroid field. The trap can then remain stable for the life of it's sun, serving as a lure to any star faring race which might rise from or even just visit the system's planets.
And deep in the heart of that treasure trove, on an asteroid which is obviously richer than all of the others combined, the trigger awaits to be sprung...
When the first gram of its riches are removed, the system's sun goes supernova... eliminating another threat to the Old One's rule.
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# Oort Cloud
Could it be that the civilization has a refinery orbiting a star while the actual mining happens in the Oort Cloud. Having the refinery in close to the center of the star system (at least not close to the edge of the Oort cloud) would mean that mining operations could happen anywhere in the Oort cloud would just head towards the center of the system to get it processed.
The Oort cloud could / would have as dense an asteroid belt as you want or as rich. Since not much is known about the Oort cloud currently you could hand waive a lot to fit your requirements.
The Oort cloud would be large enough to warrant the construction and maintenance of a processing facility (close to the sun maybe to use solar energy for refinement of ore).
As for collisions, I was told once (no actual proof behind it sorry) that some of the comets that come into the solar system were caused by collisions in the Oort cloud.
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In recent years, the search for the origins of life is becoming complex. It turns out that oxygen is NOT a requirement for multicellular life to thrive. As stated in [this BBC article](http://www.bbc.com/earth/story/20150112-did-snowball-earth-make-animals), poriferans (sponges) can thrive at oxygen levels of just 0.5%. And according to [Kitsap Sun](http://archive.kitsapsun.com/news/environment/jellyfish-dominate-in-areas-of-poor-water-quality-ep-355398841-355631811.html/), jellyfish do better in low-oxygen waters than fish. And then, of course, there are the [loriciferans](https://en.wikipedia.org/wiki/Loricifera), a phylum whose common name I can't find. They, too, thrive with little to no need for oxygen.
So this got me thinking. Life first appeared 4.28 billion years ago as single-celled, extremophilic microbes, possibly bacteria or archaeans or both, thriving in a perfectly anaerobic Earth. But [a recent discovery](http://www.sciencemag.org/news/2018/06/momentous-transition-multicellular-life-may-not-have-been-so-hard-after-all) has shown that the jump from single-celled to multicellular is not as hard as traditionally assumed. With that in mind, could animals evolve sometime during the Hadean Eon, 4.6-4 billion years ago? Or would something hold them back?
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The environment held even bacterial life back.
Life is believed to have started in the archean, not in the hadean. According to [this article from the Univerdity of California](http://www.ucmp.berkeley.edu/precambrian/archean_hadean.php):
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> The Archean eon, which preceded the Proterozoic eon, spanned about 1.5 billion years and is subdivided into four eras: the Neoarchean (2.8 to 2.5 billion years ago), Mesoarchean (3.2 to 2.8 billion years ago), Paleoarchean (3.6 to 3.2 billion years ago), and Eoarchean (4 to 3.6 billion years ago). (...) **Also during this time, the Earth's crust cooled enough that rocks and continental plates began to form.**
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> **It was early in the Archean that life first appeared on Earth.** Our oldest fossils date to roughly 3.5 billion years ago, and consist of bacteria microfossils.
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> ### The Hadean
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> Hadean time (4.6 to 4 billion years ago) is not a geological period as such. **No rocks on the Earth are this old, except for meteorites.**
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And from the [wiki](https://en.wikipedia.org/wiki/Hadean):
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> Liquid water oceans existed despite the surface temperature of 230 °C (446 °F) because at an atmospheric pressure of above 27 atmospheres, caused by the heavy CO2 atmosphere, water is still liquid. As cooling continued, subduction and dissolving in ocean water removed most CO2 from the atmosphere but levels oscillated wildly as new surface and mantle cycles appeared.
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As if the a pressure cooker atmosphere wasn't enough, gas levels oscillated. I am quite sure no extremophile is that extreme. I've heard of bacteria withstanding close to 100 ºC, but 230 ºC, while also bearing 27 atm's, is pushing it.
But hey, it's your world, you can handwave that — and the coolest part is that it would not be unrealistic :) just because we haven't seen it doesn't mean there couldn't be such microbes. And if they thrive, then more complex lifeforms can evolve from them. It would just probably be very different from anything we've ever seen, both anatomically and physiologically.
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## Not all single-celled organisms are equal
It's easy to take examples from modern times and try an extrapolate backwards, but later single-celled organisms have evolved a *lot* from the first living things. Even if you could come up with a hypothetical extremophile that could live in Hadean conditions, that doesn't mean life could have *started* under those conditions.
Archaea, contrary to what their name may suggest, are not like the first organisms at all - they are highly adapted cellular tanks with a ton of adaptations for surviving the inhospitable locations they are known to inhabit, and they evolved these abilities in order to exploit resources that other organisms could not. It is highly unlikely that life could have originated under these conditions.
Similarly, although the jump from single-cellular to multicellular life happened pretty fast, life was not just twiddling its thumbs for that first 3 billion years - it was evolving new chemical pathways, better DNA replication mechanisms, and the ability to *interact* with other cells. The framework upon which all multicellular life is founded is extremely complex and it took a *lot* of time to develop this framework; the first primitive self-replicating blobs were nowhere near advanced enough to develop into an animal.
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**Short Version : Not Animals, not plants.**
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> could animals evolve sometime during the Hadean Eon, 4.6-4 billion years ago? Or would something hold them back?
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We have only one example of the evolution of life to go on, so absolute statements are hard to make.
However ...
The first life is thought to have appeared in the [Archean Era](https://en.wikipedia.org/wiki/Archean#Early_life) and the most direct evidence for that is for [Stromatolites about 3.5 billion years ago](https://en.wikipedia.org/wiki/Stromatolite), which are due to single celled microbes.
To get to *animals*, which is what you ask about, took until the [Cambrian Era](https://en.wikipedia.org/wiki/Cambrian_explosion) which was "a mere" 540 million years ago.
So based on our one example of evolution, it takes about *3 billion years* from life to go from single cells to animals (and we're including very basic sea creatures in this loose definition of animal).
So if you start your evolutionary cycle in a Hadean Era, it's only about half a billion years before we think the first life appeared on Earth. So you shave about half a billion years off the time when animals appear.
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This is an opinion, rather than something I can rigorously support, but I would suggest that while life based on the chemistry possible in the Hadean Era may be possible (I can't say it isn't does not mean I think it is), life based on the more stable geological conditions and different chemistry of the later Archean period may simply be better able to flourish.
Also the change of conditions might simply make it impossible for the multicelluar organisms that would (optimistically) be in existence at the end of the Hadean Era to continue. It's like any life existing in the Hadean would simply not be compatible with the conditions that developed later.
During the Hadean Era surface temperature is thought to be about $230^\text{o}\,C$ and atmospheric pressure was of the order of 27 atmospheres. By the Archean Era conditions have changed to (again very rough estimates) less than $50^\text{o}\,C$. As that era developed temperatures fell.
The issue here (and it woudl apply to any planetary formation) is that at the start conditions change (relatively) quickly. This will mean that anything adapted to the relatively extreme conditions of the earliest period will almost certainly not be compatible with later period.
Finally there is evidence of a period called the Late Heavy Bombardment which would have occurred at about the late Hadean-Early Archean period. This may or may not have affected the development of life on Earth, so it's a potential source of "wiping the slate clean". However I'd suggest (opinion) that what little evidence there is does not seem to support a break in the chain of evolution like this. It seems more likely that Hadean life forms (cells) would have evolved or died out as conditions changed due to the way the Earth's general state changed.
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The issue with life in the Hadean isn't so much the oxygen, it's the water; the surface of the earth is too hot for any bodies, or even puddles, of liquid water to form. So life on the surface of the planet not so much, there are at least two modern lifeforms that *might* be able to survive "on" (in the atmosphere of) a planet in that state:
* [Radiodurans](https://en.wikipedia.org/wiki/Deinococcus_radiodurans), this little extremophile that can survive extreme cold, dyhydration, ionizing radiation, strong acids, and hard vacuum; they first found it floating on the edge of space, above the [Kármán line](https://en.wikipedia.org/wiki/K%C3%A1rm%C3%A1n_line) and thriving in UV strong enough to sterilise surgical equipment. It could inhabit that same, insanely hostile, environment during the Hadean.
* any of the cloud borne or stratospheric [bioaerosol](https://microbewiki.kenyon.edu/index.php/Aeromicrobiology) community, I was thinking in particular of free floating mitochondrion but they would require free oxygen so probably not, there are similar creatures that exploit sulfur-oxide gases, methane and CO2 which might be candidates.
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This is part of the same world I am making that this question I once asked is set in: [How to evolve a reptile into a wyvern, 100 million years in the future?](https://worldbuilding.stackexchange.com/questions/118788/how-to-evolve-a-reptile-into-a-wyvern-100-million-years-in-the-future)
I might call these questions related to this world the "100 million years into the future" questions.
In that same futuristic Earth I imagine sharks that walk (or at least crawl) on land with some fully disconnected from sea life, that can breathe air directly and thus either dig underground or climb up in trees. Most of their species have evolved from today's Epaulette shark which is known to walk on the sea floor in reefs and occasionally comes out of water to crawl back into water.
These "land sharks" however are not your good old Shark Week Sharknado style nightmare that terrorizes everything, instead I imagine these sharks as rather small and "peaceful" ones. These sharks would mostly be herbivore and insectivore and they are preyed upon by terrestrial predators of that time like the wyverns from my other question.
What would drive the Epaulette shark to evolve into descendants that can breathe in the air and evolve into creatures that would never see the ocean again and would these sharks be able to consume vegetation or insects as their main source of food on land?
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Epaulette sharks are known for their terrestrial habits, which can "crawl" across the land like this:
[](https://i.stack.imgur.com/ulPsY.gif)
Much like an ancient Tetrapodomorph, they crawl with their pectoral and pelvic fins. They can survive for impressive periods in environments with little to no dissolved oxygen, such as the land.
Now we know it's possible, we should address how fully terrestrial sharks would evolve.
**Why they would do it:**
Our friend the epaulette lives in very shallow reefs, which are exposed to the air when the tide goes out. Where most other competitors would retreat to deeper waters, it stays, crawling across the land to feed where other predators can't go, and its prey stands little chance of escape in such enclosed tide pools.
If, in the future, a shark like this would live in an environment of many pools with areas of land connecting them, it might crawl between pools in search of prey.
Another idea is that it might become a water-to-ground predator, like a crocodile. If a potential, unexploited prey source lived on beaches, it could start out by beaching itself like a killer whale, but then evolve to be able to stay on the land a bit longer. After millions of years, the terrestrial habit becomes more and more refined, until they are fully able to go on land.
**How they would breathe:**
Bony fish have an organ called a swim bladder, which is an offshoot of the digestive system. It's believed that when fish colonized the land and became tetrapods, their swim bladders evolved into lungs.
Sharks lack a swim bladder to rig up, so we're gonna need some other method of air-breathing. Some arthropods have something called a book lung.
The way a book lung works is that oxygen passes through a slit, and then proceeds through a multitude of folds. Blood circulates through the lung, exchanging carbon dioxide for fresh oxygen.
Now, this is where it gets really speculative. Sharks have an organ in their gut called a spiral valve, which looks like this:
[](https://i.stack.imgur.com/M6Ru3.jpg)
If they were somehow to bifurcate this spiral valve, keeping one as part of the digestive system, while another would form some sort of book lung equivalent, then they might be able to breathe air, through holes that are actually modified gills. Again, remember that this is the kind of wacky speculation that I enjoy, but others may frown upon.
**What they would look like:**
When we look at the epaulette shark and how it moves, it's clear that they're using their pectoral and pelvic fins to walk. So did the first tetrapodomorphs, so it's probable that a terrestrial shark would have four legs.
If an epaulette-like shark was to colonize the land, I predict that:
* It would have four limbs with digits
* Its dorsal fins would be lost
* Its tail would atrophy
I think it would have digits because, looking at a shark skeleton, they have rays of cartilage in their fins which would become useful for walking. They wouldn't need their dorsal fins (Unless they were display organs) because they wouldn't swim much, and they don't need such a long, powerful tail on land.
One thing that would have to happen is ossification. Obviously, shark skeletons are made of cartilage, and cartilage might not be suitable for supporting a land animal of the shark's size. So, I'd be surprised if terrestrial sharks didn't ossify their cartilaginous supports and gain a full-fledged calcium phosphate skeleton.
**How they would match your description:**
In this scenario, I spoke of the sharks coming on to the land as predators, but a descent from carnivory to omnivory to herbivory is certainly possible. After all, plants carpet the land far more than the water, so it's an abundant food source for the shark to exploit.
As for insectivory, that's also possible. Depending on how they catch the insects, they might develop a good sense of smell and sharp claws. As for size, epaulettes are pretty small, about the size of a dog.
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Anyway, those are my thoughts on how terrestrial sharks would evolve. I hope I answered to your satisfaction.
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With evolution you can nearly always get from A to B given enough time.
100 million years is enough time. The main problem is that the land is already covered in tetrapods that are very well adapted to terrestrial life. There aren't many niches for sharks to fill that can't be more quickly taken by tetrapods.
So the first thing to do is to wipe out land life. Perhaps something involving a gamma-ray burst would do it.
With us gone you've got some space for a shark to come out of the sea and live on land. In this scenario with large terrestrial life gone there an explosion of arthropod life, this provides a food source. Where there is food, life will follow.
Initially this might take the form of sharks beaching themselves to grab something to eat then getting back to the water. Sharks that can maneuver on land will be at an advantage, as can any ability to remain in air for longer.
Pretty soon, the sharks will stop looking much like sharks, and evolve into a range of animals as diverse as those of the Permian. That can include herbivores, carnivores. Small and peaceful as well as large and aggressive. Why not also some flying animals? All that is certain is that they won't look much like sharks anymore, but may retain things like a cartilaginous skeleton.
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For backgrounds sake, let's say that there are large, and I mean *large* beings living underneath the icy surface of Europa. Now consider this excerpt from NASA's page on Europa:
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> One of the most important measurements made by the Galileo mission showed how Jupiter's magnetic field was disrupted in the space around Europa. The measurement strongly implied that a special type of magnetic field is being created (induced) within Europa by a deep layer of some electrically conductive fluid beneath the surface. Based on Europa's icy composition, scientists think the most likely material to create this magnetic signature is a global ocean of salty water.
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Is it feasible/possible for a large, water-borne organism to harvest and convert the magnetic force generated by the moon/ocean itself into a sustainable source of energy?
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**Yes.**
How do we use magnetism to create useful energy? If a conducting object is in motion relative to the magnetic field, an electrical current is produced in that object. The current produced gives rise to a magnetic field that opposes the external magnetic field. This is [electromagnetic induction](https://en.wikipedia.org/wiki/Electromagnetic_induction).
This is exactly how Europa is getting its magnetic field - it is being induced. It is not a static field generated internally like that of the Earth. Electrical currents are being induced inside Europa as it traverses Jupiter's magnetic field, and they betray their presence by generating a magnetic field which opposes that of Jupiter.
[](https://i.stack.imgur.com/3GbYj.jpg)
<http://ffden-2.phys.uaf.edu/webproj/212_spring_2015/Amir_Raz/amir_raz/Magnetic.htm>
Your creatures could move through Europa's magnetic field and generate a current within themselves. But even better - ride Europa through Jupiter's magnetic field (which they sort of have to do since they live there). Jupiter's magnetic field will induce currents within these creatures just as it induces currents within Europa. The relative movements of Jupiter and Europa do all the work. An electrical current is powering this computer; it is fine energy for your giants although you will need some creative biochemistry if you want to really get in the weeds.
Maybe a large portion of whatever is actually conducting electricity within Europa is these huge creatures - the bigger they are the more electricity they can harvest. Maybe Europa's magnetic field is actually the magnetic field of these space leviathans.
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Short answer:
### No
Magnetic fields, such as those generated by (say) the Earth, or Europa, are static. They do not impart energy to non-moving objects in their vicinity. The way you harvest energy from a magnetic field is to move an object through it - and in so doing you're harvesting energy from the movement, not the field; the field does not lose strength.
Even notwithstanding this, the energy gathered from movement through a planet's magnetic field is relatively small (and Europa's would be smaller - much smaller - than Earth's). The energy harvested from movement through the field would be (indeed, *must* be) less than the energy expended to move.
## Caveat - Good Vibrations
One situation where energy *can* be harvested from a magnetic field without much movement is if the magnetic field is rapidly oscillating. This is how induced magnetic fields work, but generating any substantial energy requires truly rapid (kHz) oscillation, which simply does not happen on a planetary scale.
As an additional note, magnetism is not radiation. No particles or waves are emitted by a magnetic field.
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In a static magnetic field, no.
It would be like trying to live on just gravity. Eventually you would simply run out of potential energy (ie hit the ground), and you would need another energy-source to keep the system going.
However, if the magnetic field was fluctuating somehow it could be done, much in the same way that you can harvest the tidal forces from the gravity of the moon. keep in mind that you would still run out of potentional energy eventually, it would just take a lot more energy to do so. Why on earth Europas magnetic field would sufficiently fluctuate though is beyond me
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[](https://i.stack.imgur.com/3g2R9.jpg)
[Here](https://i.stack.imgur.com/sfADU.jpg) is a map I just produced of the plate tectonics of a world I'm working on. Does anyone familiar with the subject see anything wrong with it? If you can differentiate between the penciled and the green arrows, the green ones are set in stone, usually to produce a geological feature I already need for the story. The penciled ones I can change. All the cursive words in blue are geological features that are nonnegotiable and that I need the tectonics to produce. Otherwise, anything is open to change!
Thanks for the help.
Here is another map I've done more recently based on the tectonics map, including lakes, islands, and some physical features.
[](https://i.stack.imgur.com/c1qhj.jpg)
[Answer]
[](https://i.stack.imgur.com/5FghE.png)
# Hotspots
You don't really need them, but they exist and would show you where to put island chains. Also, hotspots on land can produce interesting features such as Mount Kilimanjaro and the Yellowstone geysers.
# Diffuse boundaries
Not all plate boundaries are 'set in stone.' There tend to be folding zones where collisions happen. The areas labeled 'Diffuse boundary' on the map above shows zones of collistion impact; usually either centered on the line of separation of two plates moving apart (e.g. Africa/Nubia and Somalia plates separating forming the [Great Rift Valley](https://en.wikipedia.org/wiki/Great_Rift_Valley)) or the folding zones from the most massive collisions. Note the region from North Africa to Iran; this folded region from the collision of Africa and Eurasia and the formed the mountains of the [Alpine Orogeny](https://en.wikipedia.org/wiki/Alpine_orogeny), which themselves erased the former [Paratethys sea](https://en.wikipedia.org/wiki/Paratethys).
These aren't strictly necessary, but when you have separating plates on land, you should shade an area of volcanic activity as a rift valley forms. If you have colliding plates on land, you should shade a folded zone of high mountains on the slower moving of the two colliders. For example, fast moving India is folding slower moving Eurasia to form the Himalaya; while the fast moving Nazca plate is folding the slower moving South American to form the Andes.
# Its really pretty good
I only nit picked some things since an answer of 'no its good' is pretty boring. But it is good.
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## First, I'd recommend plugging a jpeg or pdf of your map into GPlates.
It's a pain in the butt, but this will tell you if your maps make sense on a globe. Artefexian explains the process here, starting at 3:04.
<https://www.youtube.com/watch?v=x_Tn66PvTn4>
He also has a video specifically on how he uses GPlates.
<https://www.youtube.com/watch?v=yGMKmbGTEHQ&t=519s>
## Just off the bat, I have a few questions.
I have to point out the plate called Telcatha on your map. The green arrows along the volcanic island chain and the arrows above the jungle are pointing at each other. Telcatha itself can't be moving north and south at the same time, so is Mistsong just moving south away from Telcatha faster than Telcatha is moving toward it? And if so, why isn't there a convergent fault along Mistsong's southern edge?
How does Balorin relate to Selkie? And is it also a case of For moving south away from Balorin that creates the divergent fault?
Is there a divergent fault between Idelwydrin and Feymarth? Is the a convergent boundary between Feymarth and Kreft?
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In our story's universe, a solar system is hand-crafted by a deity with seven smallish bodies working in a way that I can only describe as [Lagrangian Points](https://en.wikipedia.org/wiki/Lagrangian_point), where all planets have the same orbital path and rough mass and volume, but are separated by a seventh of a turn from each other. This is somewhat stable in the story and only needs to exist for a relatively small amount of time, astronomically speaking.
The trouble is, we also need a smaller body (a left-over chunk of a salvaged planet, not of much size) to pass by the planet regularly, say once every few years.
I've devised a couple of silly paths that would allow the small body to pass each planet forming something like a 7-pointed star, but wondered if this were actually possible.
To be clear, the story won't go into any detail on the physics involved, and the orbit is acceptable even if it requires a high level of precision in set-up because it's going to be the result of a deity.
**Edit:**
To clarify, the orbit won't *need* to be stable for a period of time on the scale of billions of years, likely less than a few million years, though this will effect the context of the story significantly.
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What you’re describing is a Klemperer Rosette, which is actually stable. Basically any regular polygon of equal mass planets with a star in the middle.
Given that, there’s probably an orbit for a small mass which visits them in turn, but I doubt there’s any way to prove this without serious computation.
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# No
The Klemperer Rosette is theoretically stable for several configurations of planets. There is in fact a hexagonal, six-planet configuration discussed in the [original paper](http://adsbit.harvard.edu//full/1962AJ.....67..162K/0000162.000.html) that is stable.
Unfortunately, any sizable mass periodically interacting with the six planet ring will almost certainly destabilize the system. The $n$-body problem is [famously](https://en.wikipedia.org/wiki/N-body_problem) chaotic. On planetary time scales (i.e. billions of years) any regular gravitational action on a Rosette will destabilize it.
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What you are describing is vaguely similar to what is described in these posts in PlanetPlanet:
<https://planetplanet.net/2017/05/03/the-ultimate-engineered-solar-system/>[1](https://planetplanet.net/2017/05/03/the-ultimate-engineered-solar-system/)
<https://planetplanet.net/2017/05/01/the-ultimate-retrograde-solar-system/>[2](https://planetplanet.net/2017/05/01/the-ultimate-retrograde-solar-system/)
They discuss much more complicated solar systems than yours, with multiple orbits with multiple co orbital planets in each orbit. These are not Trojan orbits or Lagrangian orbits or Kemplerer Rosettes, but vaguely similar.
As you can see by the "engineered" in the title the author believes that natural examples of such complex systems could never form, and thus assumes that they would be created by super advances societies.
So perhaps you could ask there for advice on designing your solar system.
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In multiple regions of Earth, cockroaches developed sentience by means of a natural virus with mutagenic genes. A long time ago one such colony made its home inside a house of a scientist. The colony has lived in that house ever since. The roaches are intelligent enough to understand/learn human languages and they work as a hive mind with a big queen who acts as the synaptic nexus of the hive, she is the voice, the brain, and the breeder.
The queen (who has to be carried by her workers as she is too big to walk, just saying) finds out that the scientist will soon try to exterminate the colony.
How does she communicate with the scientist and ask for endangered species protection?
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The cockroaches spell out words by forming into groups to show intelligence. Isn't this kind of obvious? I feel like I saw a cartoon with a similar premise once that used this method of communication.
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She gets her subjects to dance to a song that the scientist would recognize.
Kinda like this: <https://youtu.be/3YvaB7zwbCk>
Seriously. Such a display would only take a minute and would convey much more in terms of showing intelligence than any attempt to establish a code for two-way communication.
The scientist will feel obliged to study such a bizarre and unlikely phenomenon and will halt any extermination attempt. After that, the roaches may try to establish an intermediary language with which to talk to humans.
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[traditionally via unattended typewriters](https://en.wikipedia.org/wiki/Archy_and_Mehitabel)
if you dont believe me
[see don marquis website](http://donmarquis.com/archy-and-mehitabel/)
we are wary of household cats
but alley cats
like ourselves
know adversity and prejudice
and mehitabel is my friend
yours
archy
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In *The Hephaestus Plague* by Thomas Page (1973) they communicate by shaping letters with their bodies.
They would probably begin to do so after deducing the existence of a written language - which would be a difficult concept for cockroaches: something on the lines of "Humans don't use pheromones, they orient themselves via these patches of colors on the walls". They might start by forming signs like "NO ENTRY" or "DANGER" as they've observed they tend to repel humans, or "STOP" and "WALK".
Later - how much, depends on their intelligence - they would understand letters and language.
After a little negotiating, they could perhaps use touch screens or feather-key keyboards.
This would in all likelihood go on under the aegis of some black op intelligence gathering operation (or in some lone visionary scientist's backyard).
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> "Imagine being able to penetrate most enemy underground bunkers, most locked rooms even, without the opposition ever being able to discover our operatives. Later on we are confident on being able to release tailored toxins inside those same bunkers..."
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Then, they'd find out that the opposition is already negotiating with other cockroach colonies elsewhere :-)
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How powerful would a series of explosions have to be to significantly change a planet's axial tilt?
In my universe they have highly energy efficient crystals, not only do they store energy but they also produce it, somewhat like quartz.
These crystals also potentiate the power of any energetic reaction released close by to astonishing levels whilst containing effectual destruction to a smallish area.
If they are set off in a town, maybe the town's perimeter will be totally destroyed, razed, but its periphery will suffer "only" from radiation.
So my question is: would such a series of explosions, carefully planned and set, be able to affect the axial tilt of a planet?
[Answer]
An absolutely fascinating article was written by NASA about the [magnitude 9 Sumatra Earthquake](https://www.jpl.nasa.gov/news/news.php?feature=716). That earthquake was so powerful that it...
* Sped up the Earth's rotation.
* Changed the Earth's shape.
* Changed the Earth's axial tilt.
It's worth noting that the changes were, of course, *miniscule.* (The axial tilt changed by single centimeters.) But it did it. So, let's examine that earthquake. In the article, Dr. Benjamin Fong Chao said...
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> Any worldly event that involves the movement of mass affects the Earth's rotation, from seasonal weather down to driving a car.
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The earthquake released energy equivalent to [1.8 trillion Kg of explosives](https://d2gne97vdumgn3.cloudfront.net/api/file/5V12sIsXSve7Gfsgntqm). Converting that to a more practical measure, it's the equivalent of a 2,000 megaton nuclear explosion.
And to put that into perspective, the [Tsar Bomba](https://en.wikipedia.org/wiki/Tsar_Bomba) nuclear test explosion of the Soviet RDS-220 hydrogen bomb was **ONLY** 50 megatons. It had a [100% destructive blast **radius**](https://en.wikipedia.org/wiki/Tsar_Bomba#/media/File:Tsar_Bomba_Paris.png) of 35Km (22 miles). That's the radius, not the diameter. The earthquake was 40X more powerful (think, "100% destruction of *the entire United States coast-to-coast."* Chant it with me, children! *"From sea to shining sea!"*).
***But the earthquake wasn't a surface explosion. It was directly moving the mass of the earth. A surface explosion has "less to push against."***
[Newton's third law](http://www.physicsclassroom.com/class/newtlaws/Lesson-4/Newton-s-Third-Law) is not our friend when it comes to your question. Atmosphere represents very little in terms of what you can push against, which means a chunk of the energy needed to shift the earth's axis is lost to the springy mattress of atmosphere. I'm not even going to try to be accurate. Let's just assume you need at least 10X the surface explosion to do to the Earth what the earthquake did — not that I actually need more boom for a more dramatic conclusion....
But, now we're talking about a blast radius that would totally destroy the entire western hemisphere and a fair chunk of the eastern hemisphere. ***This is an important point that I'll conclude with. Call it "foreshadowing."***
However, we are **NOT** doing something that's inside the earth and capable of affecting (at least not easily) it's rotation ... and rotation is what you need to shift the axial tilt. A surface explosion can push against the surface perpendicular to the earth's center, but it can't roll the planet over. You need to be inside to do that. You can move it in its orbit (push it closer or futher away from the sun, change its elliptic angle, or make the year longer or shorter), but you can't turn it upside down (which would be cool, by the way, if nobody got hurt in the process... which is the problem, donchaknow).
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**CONCLUSION**
No, not really. You can't substantially change the axial tilt of the earth with a surface explosion.
But, if you could, the explosion needed would quite literally bring 100% destruction to a *hemisphere.* The resulting impact on the planet would certainly kill every living thing. So, even if you could shape the charge to give you the inclination needed to roll the planet... [you wouldn't have a habitable planet left to brag about](https://www.youtube.com/watch?v=NiqN7fNzbd0). And what are you bragging about? Having rolled the earth *a few centimeters!*
And I haven't even talked about what this explosion might do to the mantle.... That's an entire thesis by itself.
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> **BIG EDIT:** I've been thinking about this answer, and maybe... MAYBE... if you set this big mother hubbard of an explosion off against a large enough escarpment — not a mountain, not even a mountain range — but a big escarpment like Africa's Great Rift Valley... maybe you could get enough rotational push (assuming the escarpment is along the correct axis, which the Great Rift Valley isn't), maybe enough push to roll the planet.
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> So, maybe it is possible... but you still don't have a viable planet and you've still only rolled it a few centimeters. So the practical answer must remain "no."
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# No, for a number of reasons.
* the required energy is several orders of magnitudes greater than that supplied by quantities of antimatter sufficient to blow the planet apart.
* applying the force to the crust will rip said crust from the "liquid" mantle beneath, which would not follow immediately the change of direction.
* unless performed in very, very long times, the planet would "wobble" and the ecosphere would be utterly destroyed in the shattering of the crust.
* you don't need simply "energy" to change the momentum of a rotating body - you need to apply force, and this requires mass expulsion. The more and the faster, the better. It goes in the other direction too: you can do it with [mass impulsion](https://www.space.com/13231-planet-uranus-knocked-sideways-impacts.html). But we're again talking of energies sufficient to shatter the planet and revert it to its molten state. *Then*, after enough million years to cool down, you'll have a planet again, with its axis tilted.
# But...
* If you used high-energy explosions or any other suitable means to throw carefully balanced mountain-sized projectiles at c-fractional, at a suitable angle (e.g. drilling a well at an angle so that the explosion does not push straight towards the center of the Earth)
* allowing enough time for atmospheric turbulence to subside and extra energy dumped all the way to the stratosphere to cool off,
* for a very long time (probably million of years; you might be able to do it in a few hundred thousand, but I'd need to run the calculations)
...then yes, you could nudge the planetary axis any which way and still have a planet at the end of the day. But you're never going to do it with Verne's *canon qu'on braque*.
[Answer]
To change the axial tilt you need to turn the angular momentum vector $\pmb{L}$ by supplying an angular impulse $\pmb{\alpha}$. So if you want to change the tilt by an angle $\theta$ the required impulse is $\pmb{\alpha}=\sin(\theta)\pmb{N}+(\cos(\theta)-1)\pmb{L}$ where $\pmb{N}$ is a normal vector to $\pmb{L}$ of the same length. The magnitude of the impulse is $||\pmb{\alpha}||=\sqrt{2}\sqrt{1 -\cos(\theta)}||\pmb{L}||.$ So the impulse will be of roughly the same order of magnitude as the angular momentum.
The angular momentum of Earth is $\pmb{L}=\pmb{I}\cdot \omega$ where the angular velocity $\omega=2\pi/T=7.2722\cdot 10^{-5}$ radians per second and the moment of inertia (assuming uniformity and sphericalness) $\pmb{I}=(2/5)Mr^2\approx 9.6928\cdot 10^{37}$, so $||\pmb{L}||\approx 7.0488\cdot 10^{33}$ Joule-seconds.
That means that to move it ten degrees, you need $0.1743||\pmb{L}||\approx 1.2287\cdot 10^{33}$ Joule-seconds. If we assume a second-long explosion to do it, that implies a roughly equal energy. [This is more than the gravitational binding energy of the Earth](https://en.wikipedia.org/wiki/Orders_of_magnitude_(energy)#Over_1024_J) ($10^{32}$ J), so it is likely that that kind of wrench will just splatter the planet. If we suppose it takes a day, then we are talking about slightly less than the Moon's kinetic energy and slightly above the impact that made the Caloris basin on Mercury. That crater is 1,500 km across.
In short, magical crystals (or crystal explosives) that can change the axial tilt of a planet can also definitely make it an uninhabitable ball of lava.
Now, if the crystals do weird things with momentum maybe they could turn the planet without splatting it. But now you have crystals that can also turn mountain ranges around; while crude as a melee weapon they do a lot of damage if you just leave them on top of your enemy and his kingdom.
[Answer]
**No**
The astronomical properties of a planet such as earth would not be alterable in the way you describe. To change the axial tilt you would be fighting the angular momentum of the whole planet as the earth is “spin stabilised” and angular momentum is conserved. Any force capable of changing the axial tilt significantly would have to employ such enormous energies that the entirety of the crust would probably be melted due to frictional forces
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Yes.
If you create a powerful enough explosion that can jettison away enough mass at great enough velocities, you could alter the planet's axial tilt. Although, you'd probably alter a little more than the planet's tilt in the process ...
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Assume enough bombs have been dropped for there to be a nuclear winter which would impede the growing of crops and cause famine. Modern infrastructure in most major nations has collapsed, and all the combined deaths from the aftereffects (fallout, societal breakdown, and the aforementioned famine) are expected to reach at least two billion.
In one of the countries most affected, like the United States, what's the largest settlement that could continue functioning indefinitely after the war? I highly doubt any major cities would remain after a few years, but what about towns, villages and hamlets? Could smaller settlements find a way to survive? If so, what do you think would be the maximum sustainable population when modern amenities are gone and the people are living off scavenged pre-packaged food and subsistence agriculture in the middle of a nuclear winter?
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According to [an answer](https://worldbuilding.stackexchange.com/a/9600/2113) to a previous question, it is possible to support one person per 800 $m^2$. Converting that to square kilometers, we get 1250 people. Converting to square miles, about 3200 people. Roughly half the world's land is used for farming, as per [National Geographic](http://news.nationalgeographic.com/news/2005/12/1209_051209_crops_map.html). So cut that down to 1600 people. Let's assume that the original estimate was generous. We have 1000 people per square mile.
Assuming people have to walk to their farms from a central, fortified town, that gives us a community size with a three mile radius or roughly twenty-eight square miles. This is because it takes about an [hour to walk three miles](https://www.reference.com/health/many-miles-can-walk-hour-115192cb03184464). And a daily commute length of an hour each way is feasible. So roughly 28,000 people in the community.
This gives us an upper community size of 28,000. To support a larger community, it would need to trade with smaller communities. It would have to offer something for which people would trade food that they couldn't just build themselves. And it would have to be something that they would need continuously. Otherwise the large community would starve as soon as it ran out of communities with whom to trade.
Some communities may be able to survive longer if they are powered by nuclear or renewable fuels and have access to stored frozen food. But that won't work perpetually. Eventually the food stores will run out. For longer term survival, they need to find new food sources.
The same problem applies with scavenging food. That can work for the first year or two, but after that the food will have spoiled. Certainly anything that is served fresh. But even things that are canned will run out eventually. If you wait long enough, the [cans will fail](http://io9.gizmodo.com/does-canned-food-ever-really-go-bad-1731093418). They can rupture after getting too hot or too cold. Or the steel rusts away.
Post-apocalypse survival favors small, distributed communities over large central communities. For defensive purposes, a three mile radius might be too large. If it takes an hour of hard marching to respond to an attack, then attackers can do significant damage to the crops before being repelled.
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I don't think I could give you a figure, but assume I was a general in the army and I had a a thousand of soldiers to look after.
Many supermarkets have large storage facilities for the food they sell. I would send scouts to the nearest and then attack and displace any other scavengers. (We take this Sam's Club for the glory of the nation). Once food is secure for a few months, I'd send scout parties looking for professionals: doctors, engineers, and nuclear physicists. I would offer them and their families safety and food in exchange for their services.
The next and harder part is to get the energy. Many wind mills might work after the nuclear disasters and I could use them to power my new settlement to some extent. If I find a few decent engineers to help with that, it should be a piece of cake. If not, we'll keep raiding the nearby university libraries in search for PhD students who didn't get the memo that there was a nuclear disaster. If I can get nuclear engineers and physicists, and especially if I can find a nuclear plant that hasn't been destroyed in the attack, I could try restarting it. It might not be trivial with all the infrastructure destruction, but my scientists could find a solution and I could enslave a bunch of people to help me build the missing parts.
Once the abundant source of energy is found, we could raid seed banks, or even get seeds from Walmart and grow plants the way Lt. Smith used to grow pot under UV light in his apartment in LA. Some agricultural engineers could help us with that. Even if nuclear energy is not available, and the oil, gas and wind energy we can scavenge is not enough for this type of farming, we can grow mushrooms (portobello, pleurotus), and some plants that don't need too much sunlight, like ferns. We can get our farm animals (goats) to eat these plants, and we will thrive on meat and mushrooms. We can also farm dogs since the dog food from the supermarket will last us for a while. The best dogs will be attack dogs, while the rest will be tasty.
The size of the colony will depend a lot on how soon we secure access to food, energy and trained personnel. I think three thousand of people should be the order of magnitude for the colony. There should be minimum 100 soldiers available at any time for raids, and about a thousand for defense, especially from other organized groups. With three thousand people, the colony will last long enough, until the nuclear winter ends.
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I'm thinking your most successful settlements are going to be in very rural areas, like the southern reaches of the grain belt in the US and maybe similar latitudes in parts of Asia, like the steppe or maybe the Ukraine. Here is why:
In the US there will be Farms. Well maintained farmland. There are a lot of small family farms as well as the big corporate types. That means you will have knowledge of how to work the land.
In the Family Farms, there is a pretty high probability that there will at least some livestock that can be bred from as well as used for draft animals. Also, in plenty of places you might find older but still functional tools and basic machinery. This machinery will help keep things going, and won't require refined fuels. Horse collars, hand plows, 2 man saws. Tack and saddles will be readily available.
Preppers! This is only slightly a joke. I watched part of that Preppers show on TV and most of them lived in rural communities with only a few exceptions. A lot of them have researched a lot of techniques for survival when the excrement hits the rotating blades. this is going to expand the knowledge base somewhat. Food Preparation gets a boost here.
There are also greenhouses of various sizes dotting the landscape here and there dotting the landscape. This will be a huge help with the coming Nuclear winter. there will hopefully be enough time to build more greenhouses. To heat the greenhouses, there should be plenty of fuel in the forms of rows of windbreak trees and such.
It's a good start to keep groups going for several years. The Ukraine has areas similar in soil composition as Kansas, so as long as the people get together as I suspect they would here.
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I am in the middle of working on a post-apocalyptic game so I had to work out some of this stuff already. Here's what I found. I think it is a matter of power and radiation. If you go up into coal country I am sure that you can keep those power plants running throughout the nuclear winter, same with gas country. Coal mines and oil wells are common enough that plenty should survive a war. Hell downtown LA has oil rigs disguised inside of plenty of buildings so they could find a way to refine it and power generators. So you could have groups built around those pumps and the what they do with it.
<https://www.theatlantic.com/photo/2014/08/the-urban-oil-fields-of-los-angeles/100799/>
Yes, some of these groups could be heavily radiated if the bombs feel near by. They may die young but still produce power that can be used by other groups.
So once you have power you can build greenhouses and produce food. So if the story takes place early enough then there may not be any major communities. Two or three years out as they get the food production stabilized the communities surrounding it will begin to prosper.
The locations will most likely run by a warlord or some other kind of armed organization that can keep the locations safe enough for work to get done.
Check out these links with articles on indoor farming. New Jersey already has one in an old factory. Metal and concrete structures would be great at block out radiation.
<http://www.cnn.com/2016/09/05/world/aerofarms-indoor-farming/index.html>
Clean water would be the next hurdle If that can be found along with power and the people to put it all together then you could have a few clean healthy towns. If they get big enough they may try to expand out and take over other communities. That is if this takes place far enough in the future for the communities to have a large population.
Radiation would be really bad for any kind of community. Children will have too many debilitating birth defects, many mental to allow the community to survive so if power is in a radiation zone then maybe only the old are sent to work there since they would never live long enough to be debilitated by it and, of course, would not be having kids so that isn't a problem.
Now if you are talking about scavenging then areas that are not hit would run out of all food pretty quickly as everyone hordes any food they can reach. So anyone that came later would have to break into houses to find caches or raid them if people are still there. The only place they could find untouched food would be in the ruins of the nuked cities.
Maybe an organized team could send teams in to retrieve salvageable food. The dishonest may go and grab anything they can find and sell it as normal foodstuff. A Geiger counter is a must have item when shopping.
So in early days lots of people trying to gather the stuff to survive and build some kind of life support and in later days communities emerging around greenhouse farms and finally cities built around those same communities and even expanding to take over old areas.
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Start with a city with a major role in the food processing industry, like Enid, Oklahoma which is home to the third largest grain storage facility in the world. Now assume that by dumb luck this city was not be targeted for direct nuclear attack, (despite its proximity to Vance Air Force Base and Oklahoma City).
The 50,000+ residents of Enid would be in comparatively good shape to survive a nuclear winter. Pre-war Oklahoma winters are brutal enough that the residents already know how to deal with the cold. Chances are they could selectively take in refugees from the surrounding area, swelling their manpower to a quarter million without seriously taxing their food supply. With that much skilled labor, the city could quickly be fortified and then they could ride out the long cold storm.
It is admittedly an optimistic guess, but with its food reserves, Enid might be the strongest survivor in a nuclear winter scenario.
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So I've created a map of a fictional world using the guidelines established in the [Creating a Realistic World Series](https://worldbuilding.meta.stackexchange.com/questions/2594/creating-a-realistic-world-series). However, like all creative endeavors, the first few (hundred) maps are not going to look perfect. What are some mistakes that I and other amateur mapmakers and world-builders are likely to commit, specifically when drawing the continents' coastlines?
Here's the map in question in case the question comes off as too abstract:
[](https://i.stack.imgur.com/oQqaX.jpg)
* Are the islands and seas distributed in a reasonable manner, and are they too irregularly shaped? (I'm asking this since I want to have some sort of a balance between coastline and area.)
* Are the coastlines themselves too rugged or straight?
* Are 'reverse peninsulas' like the one in the southernmost yellow country plausible?
NOTE: I'm focusing on creating a world that abides by all natural laws, i.e. a world that could have been Earth if the the plate tectonics played out differently. A world in which magic exists would probably allow one to be more lenient with the physical constraints of our universe.
NOTE #2: Someone in the comments asked which projection I was using. While I did not explicitly design the map using the Mercator projection, I was trying to add some Mercator style distortion around the edges. The scale is 1 mm : 43 km.
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**Edit:** it seems there are questions already been asked for [creating realistic map - landmass formation](https://worldbuilding.stackexchange.com/questions/581/creating-a-realistic-world-map-landmass-formation)
Following the link you'll find a series of linked questions on the same theme. This will greatly help you and other map creators.
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That's a good map.
## Is the aspect ratio okay? Is the land to water ratio otherwise feasible?
It is okay. However you might want to consider if this is [a flattened map](https://en.wikipedia.org/wiki/Map_projection) or the exact flat-earth map. The land-to-water ratio is entirely up to you, depending on your story. Our earth has approximately 2/3 part of water, you might want to have more or less.
## Are the political divisions realistic? Are there too few - or too many - countries?
Entirely up to your setting. You can even have only 2 countries.
## Is it okay to have a world without an antarctic continent?
Why not? In our *current* world it's entirely coincidental the Antarctic ends up in the south pole. That will make your world more unique.
## Are the islands and seas distributed in a reasonable manner, and are they too irregularly shaped?
You don't have geological features, like mountains, defined in your map.
[](https://i.stack.imgur.com/zQtCp.jpg)
Please research about [Continental Drift](https://en.wikipedia.org/wiki/Continental_drift), and you can add those features realistically. Your continent shorelines already fit into each other, so you just need to add the mountain ranges.
Personally, I think you can improve your map by removing the lower right part of the eastern continent.
## Are the coastlines too rugged or straight?
It's fine, except the one unnaturally straight shoreline on the middle part of eastern continent.
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Different coastlines have different ruggedness. They are not all the same.
So assign [different fractal dimensions to different segments](https://en.wikipedia.org/wiki/List_of_fractals_by_Hausdorff_dimension#Random_and_natural_fractals) as you generate it.
E.g. Great Britain is 1.25 but Ireland is 1.22 and varies a bit around the island. Norway most famously is 1.52.
This should work with the geology if you’re doing that level of detail — different kinds of rocks wear differently.
Others commented on your lack of disclosing your projection. Drawing the coastlines on a plane (even if the overall shape is projected first) will not look right!
As for the sea-sized inlet you asked a about, that could very well be a rift. Expect the surrounding geography to be consistent with this. And the larger point is that particular features don’t occur in isolation, but they interact.
I wonder about the islands near the center of the picture associated with the upper-left mass: the whole thing looks like it’s a breakup of a supercontinent, as with our world. So did these flake off as separate plates or what? If sealevel is high the islands would define the shape of the piece that broke away, with shallow seas covering the middle. Your map doesn’t look like that.
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A bit of background on what I'm developing: I'm trying to develop a language for an alien race with completely different biology to humans. It's still in the very early stages, so the exact form is subject to change, but they won't be making sounds with their mouths, but still through their breathing apparatus. They will have some kind of a vocal chords/flaps, likely either two or four pairs, enabling the use of chords/consonance and dissonance, and will be able to produce trills, plosives, and fricatives with whatever is closing the chamber, be that lip-like or flap-like. I was thinking to add other ways to redirect sounds, to mimick the effect of the tongue, but that does not make much sense outside of a mouth, and makes it needlessly more complex, so I will not be doing that.
I know for most constructed languages it is encouraged to use IPA for the phonetic side of things, but that is based on the way the human mouth and vocal chords work to produce sound, so I am not sure where to begin in notating sounds produced by an entirely non-human biology.
I think the easiest would be to just develop a writing system that takes these features into account, and explain how that system represents the sounds, but that restricts you to a featural phonetic alphabet-like script, and forbids anything like, say, a logography.
Unless you have something that serves the functions as IPA for human languages, developing the language (esp. morphological stuff) is hard.
So, if the writing system is not phonetic and cannot serve those same functions as the IPA, how do you represent those sounds in a usable and systematic way?
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# What is IPA
IPA is the [International Phonetic Alphabet](https://en.wikipedia.org/wiki/International_Phonetic_Alphabet). In principle, it has letters *and diacritics* which enable the representation of all sounds that the human [phonatory apparatus](https://en.wikipedia.org/wiki/Phonation) can produce *when used in normal speech*. It also includes symbols which enable the representation of some (but not necessarily all) sound variations, such as pitch, tone, stress or phonetic emphasis. It cannot represent the sounds made by our close cousins the chimpanzees, or by our more distant cousins the cats and the dogs, although the chimpanzees, the cats and the dogs have lungs, larynges, vocal chords, tongues, teeth, lips and noses just as we do: but theirs are different enough from ours to make different sounds. It cannot represent music. It cannot represent (or at best can only very awkwardly represent) various noises, such as the noises we make to imitate kissing or blowing wind.
# How IPA is used
IPA can be used in two ways, known generally as [*broad* and *narrow*](https://en.wikipedia.org/wiki/Phonetic_transcription#Narrow_versus_broad_transcription) transcription. (The representation of speech in IPA is called transcription and not writing because it operates at a much less abstract level.) In general, dictionaries give a broad transcription, which conflates the sounds which are [*allophones*](https://en.wikipedia.org/wiki/Allophone) of the same [*phoneme*](https://en.wikipedia.org/wiki/Phoneme). For example, the English phoneme `/l/` has two allophones, a "light" `[l]` as in *lent* and a "dark" (velarized) `[ɫ]` as in *fiddle*, which are both shown as `/l/` in most dictionaries. (Note that the broad transcription representing phonemes is usually written between slashes and the narrow transcription representing phones is written in brackets.) There is no pair of words in English which are distinguished by having a light `[l]` as opposed to a dark `[ɫ]`, and this is why the two kinds of `/l/` are said to be allophones, that is, they are just different realisations of the same phoneme.
# An alien IPA for an alien species
How would one build a phonetic alphabet for an alien species? First of all, one must begin by understanding how the aliens species makes sounds. There are many ways to make sounds, and humans use only some of them (at least for speech). Do the aliens make speech sounds like us, by inducing vibrations in a column of air and then modifying the pure tones by various means, such as adding vocal chord vibrations, changing pitch, coloring the sound by rounding the lips or releasing the air through the nose, adding friction sounds, or stopping and releasing the air with the lips or the back of the toungue? Or do they use alien mechanisms, for example the [stridulation](https://en.wikipedia.org/wiki/Stridulation) used by the [grasshoppers](https://en.wikipedia.org/wiki/Grasshopper) of Earth?
After considering the phonatory apparatus of the aliens one should decide what sounds are considered distinct by the aliens. For example, English (at least RP and General American Englishes) distinguishes the front *mid* vowel `/ɛ/` (as in *ten*) from the front *open* vowel `/æ/` (and in *tan*); a Romanian needs quite a lot of effort to learn to hear this distinction, because the Romanian language has only one phoneme `/e/`; or consider Mandarin Chinese, where there are four different phonemes which all sound like *ch* `/tʃ/` to a European. (The four Chinese sounds are `/ʈʂ/`, `/tɕ/`, `/ʈʂʰ/` and `/tɕʰ/`, transcribed
*zh*, *j*, *ch* and *q* in [Pinyin](https://en.wikipedia.org/wiki/Pinyin).) That is to say, just because the phonatory apparatus can *make* certain sounds does not mean that they are meaningfully distinct in any given language.
For an example of human yet alien-like acoustic language consider the [whistled languages](https://en.wikipedia.org/wiki/Whistled_language), which are of course impossible to transcribe using IPA, but are somewhat representable using musical notation.
# Then how would we write the alien language?
When alien language is to be represented in a book one must necessarily use some sort of tranliteration or transcription scheme using Latin letters, possibly with diacritics, or with a variation in font (to remind the readers that the letters do not stand for their usual sounds), or both.
* Chinese Pinyin is a (relatively) widely known transcription scheme, which uses Latin letters in a most un-Latin way. For example, let's say that you see **quanxu**; a naive English reader might naively imagine a pronounciation like `/kwænksu/` whereas a savvy reader will know that it should be `/tɕʰwanɕy/` (sort of like *chʰwahnshü*, with *ah* the vowel in *car* and *ü* as in German).
* Egyptologists use a special transcription system (complete with a [conventional pronounciation](https://en.wikipedia.org/wiki/Egyptian_language#Egyptological_pronunciation)) to represent ancient Egyptian words -- Twt-ʕnḫ-ı͗mn, pronounced conventionally `/tuːtənˈkɑːmən/` is much easier to show in print than the actual hieroglyphs. (Wikipedia says that the original pronounciation *may* have been something like `/taˈwaːt ˈʕaːnxu ʔaˈmaːn/`.)
So to write the alien language use Latin letters, in some sort of systematic way, trying to represent not the sounds of the alien speech but the meaningful distinctions and roles of those sounds. Use vowels for sounds which can be pronounced (by the aliens) continuously and can form the center of a syllable; you may use the human front-to-back order `/i/`-`/e/`-`/a/`-`/o/`-`/u/` to represent some alien natural order, for example high pitch to low pitch; use continuant consonants such as *f*, *v*, *s* and *z* to represent sounds which can be pronounced continuously but are not syllable centers; *l*, *r*, *m* and *n* can be used in both roles; use stops such as *p*, *t*, *k* to represent momentary sounds which cannot be sustained; use *h* and possibly also *n* (and even *m*) to indicate some sort of variation corresponding for example to human aspiration or nazalization.
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Anyone who knows what the IPA is will know about manner of articulation and places places of articulation. Places of articulation are places like the glottis or lips, while manners are how how obstructed the air is; nasal, trill, fricative, etc.
[](https://i.stack.imgur.com/dtGno.png)
Every place on the chart has a section of the mouth that is required to use it. Now all you need to do is remove sounds made in places your species doesn't have. For example, a species of bird people would be unable to make labial sounds (Like english /m/, /p/, /b/, /f/ or /v/) But would likely have a strong glottis, making for Radicals and Laryngeal sounds to be made easier.
Of course, for sounds people can't make, you're out of luck, but trust me, your readers aren't going to evolve a new mouth just to speak your conlang. Stick to the sounds people can make, as well as animals.
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Humanity is often said to have 5 senses, but this isn't entirely accurate. This is one question of several in a series I am asking regarding going beyond the 5 senses.
One of the senses is something I am just going to call "body sense" as a catch-all for these:
>
> Equilibrioception: The sense that allows you to keep your balance
> and sense body movement in terms of acceleration and directional
> changes. This sense also allows for perceiving gravity. The sensory
> system for this is found in your inner ears and is called the
> vestibular labyrinthine system. Anyone who’s ever had this sense go
> out on them on occasion knows how important this is. When it’s not
> working or malfunctioning, you literally can’t tell up from down and
> moving from one location to another without aid is nearly impossible.
>
>
> Proprioception: This sense gives you the ability to tell where your
> body parts are, relative to other body parts. This sense is one of
> the things police officers test when they pull over someone who they
> think is driving drunk. The “close your eyes and touch your nose”
> test is testing this sense. This sense is used all the time in little
> ways, such as when you scratch an itch on your foot, but never once
> look at your foot to see where your hand is relative to your foot.
>
>
>
My question is this: **How might a race whose body sense is ratched up to extreme levels (say 4 times the normal human level) perceive and interact with the world?**
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Assuming some secondary adaptations, they would be able to navigate by dead reckoning. Humans usually navigate by looking at landmarks in the world around us and adjusting as we go. If we could be hyper aware of our bodies and measure out our stride length precisely, and sub-conciously count our steps and track our direction, we could walk around places we already knew with our eyes closed.
Scientifically this is known as "path integration" and it has been shown that [ants](http://jeb.biologists.org/content/210/2/198) do it. They combine this with other forms of navigation, because they don't have perfect stride counting.
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Just to add maybe one thing to the already good answers here.
I have to imagine people who are extremely gifted proprioceptively would be good manipulators of body language. How many times have you ever been told that you're sitting or standing awkwardly because you weren't aware of how you were positioned? They could use this ability to be masters of their outward appearance. This probably also means they would be very good at learning fine motor tasks.
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Imagine circumstances that would would favour these senses. A higher G world would require a faster feedback loop. A more sensitive sense would decrease the need for faster reflexes, as you would catch dis-equilibrium sooner.
Inhabitants that lived on a world of cliffs could use such a sense.
For the second, the ability to precisely know where your fingers were could help in doing mechanical work where you can't see what you are working on. Watchmakers working in the dark.
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For world interaction, they will appear incredibly graceful in every movement they make.
Things like being clumbsy, poking themselves in the eye, or biting their tongue while chewing, if not explainable by exhaustion or willful inebriation, will be considered a sign of illness to be checked out by a healer.
Depending on how keen their eyesight is, they may prefer dimmer lighting in their homes because they depend less on sight to get around, and create a more tactile written language like Braille because using touch more is very comfortable and also uses the higher functioning part of their brain more.
They will enjoy high complexity home and building designs that include more split levels, spiral staircases, fire pole exits, and lots of random dips in the flooring and shelves or whatnot sticking out of the walls (for either function or aesthetics) because they just don't care about needing to avoid running into things or accidently stepping into that in-ground floor level aquarium. They are too sure-footed and spatially aware to need flat floors and walls (how boring!). Also, railings on staircases are less prevalent except in special circumstances.
Their Olympics will include events that include some pretty fantastic balancing and body placement skills. Perhaps a gymnastics event called "floats" involving complex body contortions and posing while jumping and balancing between several loosely floating spinnable logs that are tethered to a rotating center pole".
They play with Rubics Dodecahedrons (that highly developed spatial brain center use again).
There's not much worry about safety-proofing playground equipment, so those designs are going to be pretty awesome. There's going to be lots of trampolines and very high monkey bars with plenty of moving parts.
Deep sea diving and underwater sports will be more popular. With air breathers on, they move around underwater without getting disoriented.
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What can I say, other than such a race will possess the maddest parkour skills. If such extremely developed senses are accompanied by an extremely agile musculature, micro or high g's will have little effect on their physical performance.
Not only will underwater sports become popular to them, but even aerial and orbital playground will have such strong appeal to their species they'll probably be better living offworld within bizarre artificial habitats, a la parkour heavens.
Aside from being space ninjas, they'll also be highly sensitive to any stimulus across the senses in their body-map. Therefore, their surgery and tracking techniques will also be as awesome.
If they're not gifted with innate full-organ or full-limb regeneration, an individual can perform transplants by itself. As a species, they'll quickly advance towards transhuman-equivalents since body modifications are the next generation of self-operated transplants.
One downside I can say though, is that they'll have trouble meditating, or sleeping at that matter. Since they are sensitive to the minutest enviromental changes and its effects within their bodies, they'll probably require dampener drugs or hormones that will minimize their sensitivities whenever they need to relax.
They'll be ninjas or surgeons or ninja-surgeons at best. At worst, they'll be paranoid addicts or sedentary monks.
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I have left a link to the NASA video in case you are not to sure what I am referring to or to get a better picture of what I am talking about.
<https://www.youtube.com/watch?v=bnKFaAS30X8>
With that in mind, I imagine that some of these planets if not all would be capable of having sentient life.
**Question:** How would these sentient species play a role on each other's evolution/growth?
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It would be extremely unlikely for two (or more) civilizations to find themselves at the same level of technological development. What is likely is that some civilizations in that system would predate others by millions of years.
Given that consideration, things could develop in following ways:
1. Colonization. The eldest civilization fully colonizes other worlds, giving them no chance of developing their own civilizations.
2. Cohabitation. Eldest civilization colonizes other worlds while indigenous species continue to evolve, finally becoming sentient on their own.
3. Grooming. Eldest civilization deliberately directs evolution on other worlds to produce sentient beings.
4. Seeding. Eldest civilization does not colonize other worlds, or withdraws from them after a while. However, other worlds would still be populated with a number of species from elder civilization's world, eventually evolving into sentient beings, maybe similar to "elders".
5. Isolation. Eldest civilization maintains isolation of other worlds. Eventually they also may become civilized ones on their own.
The above ideas about multiple civilizations imply that life has a high chance of developing an intellect, which may not be the case.
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The only sharing of life between these planets *might* be microbes. There's a theory that comet strikes could fling microbes out into space to potentially seed other planets. Unproven so far. But we don't see any higher lifeforms traversing space, and the question hasn't proposed any of these aliens have that ability.
Beyond that, there's no interaction while the species are evolving, so the answer to your question "How would these sentient species play a role on each other's evolution/growth?" is "They would not play any role in each other's evolution/growth."
If the question is meant to be about their cultural interaction as mature species, that question is too broad to be answered here -- it encompasses the entirety of speculative fiction on aliens!
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Whooo (like halting a horse) there, "With that in mind, I imagine that some of these planets if not all would be capable of having sentient life." While one or possibly more of these planets may be the best chance of finding life on a different world finding intelligent life is a totally different situation. In only one instance has intelligent life here on Earth been proven on a world filled with life for millions of years. (Yes there is a questions whether we can classify dolphins, whales or even some apes as intelligent but for now we will stick to humans because we are the only ones capable of leaving the planet at the moment unless of course we take some of the others.) While some people think life on Earth may have arose from life on Mars or from elsewhere in the universe via extremophiles we do not know if panspermia (the name some scientist have given to that theory) will actually work or not. I will be thrilled to find some sign of life one one of these planets. I am not sure about sentient life. At only 40 light years if it were less advanced than us I would be concerned about our future effect on them. If it is more advanced than us I would be terrified of what they would do to us when not if they discovered we are here!
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Assuming that all of the planets are inhabited by life, here's what I'd see as the most likely situation.
**The first space faring civilization would completely control and dominate the system without any other sentient races in the picture.**
Life emerged on earth 4.1 billion years ago. The first evidence of tool use dates back 2.5 million years. We first went to space 56 years ago.
Extrapolating from the only example we have - **very** soon after life evolves to the point of general intelligence and tool use, we progress to a stage where interplanetary colonization is possible. When the first species to develop space flight goes to visit these other life-bearing worlds they wouldn't even find basic civilization, because if any other world had progressed as far as tool use first they would have already colonized the others.
Hope this helps!
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Not a duplicate of "[Overcoming language barrier; no speech](https://worldbuilding.stackexchange.com/questions/11265/overcoming-language-barrier-no-speech)" which confines answers to **nothing** that is clearly a form of communication; it focuses on translation, **not** physiology or evolution
Not a duplicate of "[Where Speech is Impossible](https://worldbuilding.stackexchange.com/questions/38805/where-speech-is-impossible)" which confines the scenario to sign language and asks for justification as to why that would be
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**Is it feasible for alien life forms to evolve intelligent communication other than"speaking" using sound waves and sensing "speech" by "hearing" those sound waves?**
**If so, what *else* is feasible?**
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**To avoid broadness**
I am asking for science *as close to hard as you can get* without needing math or citations; stick to realism, and explain ideas thoroughly. Consider basing answers on Earth species' communication systems as well.
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Radio is possible at least hypothetically, the simplest types of radio, crystal radio are structurally simple and don't need power to receive and there are animals that incorporate crystals into their tissue. it's a stretch but not an impossible one. Would really mess with a human observer too it would look a lot like telepathy. MIT cas produced radio reactive biological molecules so you know it is at least possible.
pulses of light are another option, basically think morse code with bioluminosity, there are plenty of deep sea organisms that can emit light in patterns. a side benefit is light can be focused much easier than sound so they might not have problems with people overhearing their conversation.
Smell is possible but unlikely, it's just too slow and limited for complex conversation.
Journeyman mentioned squid aka cuttlefish can use color and pattern, and can even say one thing with the left and another with the right side. I couls easily see this evolving in to full blown conversation. [](https://i.stack.imgur.com/PvVPl.jpg)
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To some extent, cephelapods communicate by colour. In theory, deaf people communicate through the manipulation of EM waves - aka sign language. While Probably completely alien to us these are the 'simplest' modes of communication and pretty much have reasonable 'bandwidth', specially with more adapted limbs or other body parts. For example you could get far more combinations of 'words' or 'letters' from a limb with a reasonable amount of prehensile sub-components, colour and even texture than from a human hand.
While communication by pheromones, or smell is another possibility, the need to wait for the chemicals to dissipate makes complex communication hard.
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There are three communication channels which are able to carry reasonable bandwidth: mechanical vibrations in the surrounding fluid (or transmitted by direct contact), electromagnetic waves, and optical changes (shape, color, albedo). Humans commonly use mechanical vibrations (speech) or shape changes (sign languages). We don't use electromagnetc waves because we cannot control their generation (we do generate electromagnetic waves but they are not under volitional control) and we cannot sense the electromagnetic waves generated by other persons.
There is nothing stopping an alien species communicating through electromagnetic waves, either in their visible spectrum (using bioluminescence to generate them and their visual system to sense them) or in a separate spectrum (using dedicated organs to generate and sense them). Or they can communicate through color changes, maybe localized to some dedicated organ.
If you allow the aliens to require direct contact in order to carry out a conversation then you can imagine some sort of direct communication between their nervous systems, using for example dedicated patches on their tegument; this is much more tricky because as far as we know the operation of synapses requires a very strict alignment between the relevant parts of the neurons -- Wikipedia says that the gap between connected neurons is 20 to 40 nm wide for chemical synapses and 3.5 nm wide for electrical synapses. (For comparison, the wavelength of green light is 555 nm.)
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What would be the land requirement (in acres) for both farming and housing to sustain a society in this scenario:
* Small city of 1000 humans living on an island
* Medieval setting
* Mostly self-sufficient
* Trade ships with supplemental goods arrive weekly
[Answer]
Mostly self-sufficient medieval settlement of 1000 humans won't be a city. By [this thread](https://www.quora.com/Why-was-over-90-of-the-population-farmers-in-medieval-Europe) it seems that in medieval setting around 90% of people was farmers. This means you have 900 people in villages and **only 100 to form a "town"** - if you want it self-sufficient. Probably it would be a port settlement, for obvious reasons.
Again, if your setting is medieval, it means you have villages in woods. [Typical village had population of 50-300](http://www222.pair.com/sjohn/blueroom/demog.htm) - so you need about 6 villages and quite a lot of woods between them for it to look like medieval Europe. I recall that one square mile of *"used"* land can support 150-200 people. This is consistent with already linked source, although I agree it's not truly scientific:
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> The average population density for a fully-developed medieval country is from 30 per square mile (for countries with lots of rocks, lots of rain, and lots of ice-or a slave-driving Mad King) to a limit of about 120 per square mile
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Note that quoted numbers include land that was impractical to use, too.
Let's go with high number. Seems that you need only **5 square miles** of **usable\*** land for your population - but you should add quite a lot for things like coastline, patches that can't be cultivated and are inconvenient to build on, woods too hard to cut et cetera.
At 5 square miles, it might look like [Hebao Island](https://en.wikipedia.org/wiki/Hebao_Island) - as you can see, [it's shape](https://www.google.com/maps/place/21%C2%B051'52.0%22N+113%C2%B009'33.0%22E/@21.85888,113.166226,3a,75y,90t/data=!3m8!1e2!3m6!1s86758429!2e1!3e10!6s%2F%2Flh5.googleusercontent.com%2Fproxy%2FAyyy2Q9zfe24Mih9FqONmmFTm5L6CBBTpWLH3hVSFrdlXp2N47UXKpU3W66oOHkpZIKZ-dCZkxZRkrVTtKvB-SgrpNtt3w%3Dw203-h135!7i4752!8i3168!4m5!3m4!1s0x0:0x0!8m2!3d21.864444!4d113.159167?hl=en) makes it impossible, or at least very hard to turn all of it into farms. You need it big enough to have a 5 miles of relatively flat land. how big exactly? Depends on it's geography.
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\* By usable land, I mean fields, pastures, stables and land for workshops etc. As you can see / calculate, it's about three times more than the [estimated field area](http://www.farmlandlp.com/2012/01/one-acre-feeds-a-person/) needed. Some part of this factor comes from less effective methods, some from inclusion of land needed for other uses.
[Answer]
As a rule of thumb, it takes about [one acre of land](http://www.farmlandlp.com/2012/01/one-acre-feeds-a-person/) to feed one person for one year. That's a little over 1.5 square miles, but you'd need that land to be very reliably productive. I'd suggest adding more for a safety margin, and then double or quadruple that to allow for crop rotation and/or fallowing.
As an island settlement, your population would certainly be fishing for a good chunk of their diet as well. Fish are an excellent source of protein and nutrition, but a reliable fishing fleet needs sources of wood, fibre, and metals. Metal would probably be acquired through trade, but you'll want a field of hemp for the fibre, and some managed woodland for timber.
A potentially useful resource you could add would be a nearby island with a regular population of sea birds. Bird guano makes a *fantastic* fertiliser, so it would both make their own fields more productive and be an excellent trading resource.
[Answer]
[Kythira](https://en.wikipedia.org/wiki/Kythira)was close to stable with 500 residents in the ~16th century with a land area of 279.593 square kilometres, so you could double or triple that. how reliant on trade the island is will affect it, Kythira was well placed to enjoy easy trade.
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I am imagining a temperate forested area with freshwater lakes, rivers, small mountains, and rolling grassy hills. This environment is situated within a very large explosion crater. Outside this crater is desert for miles in every direction. Under what conditions could such an environment develop and how would it be maintained (i.e., stopping the desert from "taking over")?
Assume that there is no artificial environment/dome within the crater area.
[Answer]
**It's probable given the right circumstances**
The most important thing here is *water*. Now there's actually quite a lot of water in most deserts, but it's in general hidden beneath the ground. Thus assuming your meteorite/explosion crater had a big enough impact, there's a fair chance that there's now a lake in the center of that crater, fed by underground reserves even.
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> Lakes? > *check* (well at least a big one in the center)
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Now that we've got water we need to ensure it does not just evaporate and get carried away from our crater-[oasis](https://en.wikipedia.org/wiki/Oasis). Assuming a big enough impact we should have walls/sides tall enough to force at least part of the evaporated water to fall in the form of rain again. Thus we get a distribution of the water over a bigger area as needed (alas unless it's been a truly tremendous impact, some of the water will be lost and carried away permanently..)
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> Rivers? -> *probably* (there will at least be streams and brooks)
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Now the mountains and hills thing is something else. As this is a crater made by an explosion, it will resemble a huge bowl most likely. So tall hills and little mountains will be restricted to the rim of it, alas these walls could be as tall as you manage to get them, so there's your mountains.
*Additional thoughts thanks to @Zxyrra*: As we've got a weather-cycle going, we can add more lakes & ravines coming from the crater sides towards the central recess; thanks to erosion.
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> Mountains? Hills? > ~~*well*, we have crater walls. That counts for something, right?~~ *sure!*, just make the whole thing old enough.
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So there you go. Having a forest & grasslands inside a huge crater is definitely probable; Though the real question is *how you got that crater in the first place?*. You know, without blowing the planet up or at least destroying all life on it.
[Answer]
There is also a fairly common effect where you get a hill/mountain in the centre of the crater lake, because the ground "splashes" up after the impact. (This is Manicoagan Reservoir in Canada. You can see a little of the crater rim in the top right corner.)
[](https://i.stack.imgur.com/yvMzt.jpg)
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So I thought up this alien parasite that enters through the mouth (usually of a predator) where it attaches to the throat and simultaneously takes control of the brain and replaces the esophagus of the victim. It basically sends the unfortunate host into a feeding frenzy, eating as much as possible, with the alien worm-like parasite taking in all the food. Obviously the host will eventually die from starvation and the parasite then lays her eggs in the carcass, her many offspring feeding off of both the carcass and the meat stored in the mother from the feeding frenzy.
The two problems I face are obviously the infection of the parasite and the structure used to control the brain. This question focuses on the latter.
The parasite doesn't control everything, it only forces the creature into a frenzy. If the creature was sentient, it would be too overcome by said frenzy to be able to speak, however most other cognitive functions, reflexes and instinct as well as use of tools are active. The host is not a fumbling zombie, if the parasite infected a tiger it would be just as lethal, maybe even more so, than an uninfected tiger. The host is basically still in control, but under an extreme influence, their mind is given a single drive and they do everything it takes to follow it.
The question I'm asking is, what kind of structure or process would facilitate this kind of 'control' over the host?
Please, if you don't understand my question tell me what I'm missing so that I can edit it to suit.
[Answer]
One potential thing to look at is having multiple symbiotic parasites at work.
The first, the larger parasite that eats all the food, is a macroscopic beast that's parasitic by nature and inhabits the oesophagus. It also introduces a series of potential infections to the body, leading to an immune response focused on it.
The second is an unrelated but symbiotic parasite that inhabits the blood and causes symptoms such as aggression, hunger, hypersensitivity to touch and shutting down the portions of the brain responsible for impulse control.
These two parasites work well together: The first gets an increased food supply, the second gets an excellent transmission vector and a weakened immune system to have a go at. Whereas the first parasite might not be able to deliver effective mind control (due to distance from the brain, blood/brain barriers getting in the way, hormonal imbalances etc) the second parasite is in exactly the right place to drive creatures crazy, and while the second parasite might not be able to capitalise on the neurological/behavioural effects it has the first parasite can easily make use of the increase aggression and hunger.
Symbiotes. Better together.
That neatly
[Answer]
The parasite (alien or Earthly) would need to use chemical messages for this purpose. There are already a **vast** number of parasites which change the behavior of their hosts.
OK wait! You wrote that the parasite replaces the esophagus of the victim. This already means that no artificial chemical messaging would be required. It goes like this:
The victim eats and gulps down food => The parasite takes that food into its own body (since it is the esophagus) => The victim does not get the fulfillment it gets after eating (the stomach does not release the "I am full now" chemicals in the blood) => The victim still feels hungry and eats again => The parasite takes that food too => With time the victim gets more and more hungry as its stomach is not getting any of the food it is *eating*.
This is a simple chain with no requirements for any extra chemical messaging. Still, for further information on behavior changing parasites, I recommend reading these:
[Introduction To Behavior Changing Parasites (Scientific American Article)](http://www.scientificamerican.com/article/zombie-creatures-parasites/)
[A Nat-Geo Article On Behavior Changing Parasites](http://news.nationalgeographic.com/news/2014/10/141031-zombies-parasites-animals-science-halloween/)
[BBC Earth Article About Behavior Altering Parasites](http://www.bbc.com/earth/story/20150316-ten-parasites-that-control-minds)
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# Edit To Add
With such complex creature as a mammal, probably the only way you could urge it for something would be hormones. Hormones are released directly in the blood flow, so you don't have to take over the whole nervous system or anything like that. If you keep releasing small amounts of insulin in the creature's bloodstream, it would keep the host's blood sugar level down and make it feel very hungry. Just make sure you do not release excessive amounts which would make it too weak to walk or hunt.
If you want to make your host more vicious and aggressive, you would need to release some amounts of androgen or estrogen (male and female hormones respectively, raising reproductive urges). These hormones, besides putting a creature (specially mammals) highly focussed on procreating, also make it more aggressive (as a side effect).
[Answer]
There are a couple of good models for what you are suggesting:
* [Zombie Ants](https://en.wikipedia.org/wiki/Ophiocordyceps_unilateralis)
* [Rabies](https://en.wikipedia.org/wiki/Rabies)
* Drugs
There are a lot of drugs that cause hallucinations and/or aggression. Those would be good models.
All of these work by hijacking the hosts systems in order to propagate themselves. Imagine the parasite taking over the system and then releasing PCP and adrenaline into your bloodstream while at the same time preventing food reaching your stomach. An animal is going to stand no chance and even a human would struggle to control the results and distinguish hallucination from reality.
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[Leptin](https://en.wikipedia.org/wiki/Leptin) is a hormone that causes one to feel 'full' after eating. Having a leptin blocker for the receptors or a hormone that reduces the ability of the body to produce this hormone can have an interesting affect.
People could eat themselves to death (in theory) trying to banish the feeling of hunger. CSI had an episode where a man with this problem occurring naturally did just that. Not sure how likely that would be in truth. But add in a few other chemicals, and it makes it more possible. Such as adding in psychotropic drugs, or even just reducing the blood sugar to the brain, would severely dampen the control centers and doing stupid things would be much easier, including being aggressive in acquiring food to fill the void.
The one problem with the parasite 'replacing' the throat would be all the food is STILL going inside the host. Filling it up. It also takes a LONG time for a host to die of starvation, a human can go weeks without eating. Dying of starvation also makes the host less nutritious for the parasite once it dies. By messing with the hormones, the parasite doesn't need to stop the food from entering the host digestive system. It just puts them into overdrive until they eat themselves to death. Then they have a 'healthy' host and all the food they acquired to feast on, in a relatively short period of time.
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My setting is a late Steampunk science-fantasy, the world's technology is beginning to cross into the Dieselpunk era.
I have also played around quite a bit with nature of reality and technology in the setting to get things exactly the way that I want.
The [aether is real](https://en.wikipedia.org/wiki/Aether_theories), it is a field of particles pervading all of space. Aether particles contentiously rain down onto the planets bellow. The emanations given off by aether particles while harmless to living thing are very damaging to electronics. With a means of economically shielding devices from aether particles not yet developed, technology has progressed along different lines.
Simple highly robust electrical systems, sophisticated mechanical computing that incorporate [fluidics](https://en.wikipedia.org/wiki/Fluidics) systems and [ferrofluid](https://en.wikipedia.org/wiki/Ferrofluid) parts,electromechanical hybrids and optical technology.
Optical technology developed far earlier and faster in my setting than in the real world out of necessity. The [beginnings of optical communication](http://.wikipedia.org/wiki/Photophone) were developed in the Victorian Era, so optical technology isn't outside of the Steampunk aesthetics.
For example a very primitive form of [optical tape](https://en.wikipedia.org/wiki/Optical_tape) is in widespread use.
while actual computer remain bulky and expensive, simple data-readers are fairly affordable.
A lot of the computers in the setting are at least partially optimechanical in nature. Data is read from optical-tape and translated into vibrations which communicate with mechanical parts.
While my setting is very fantastical I would prefer not to handwave where I don't have to. Truth being stranger than fiction a real world solution could not only exist but prove more interesting than anything that I could imagine.
I ask the question...
Could video-games as we would recognize them be created with the technology that is currently present in my setting?
The earliest known electronic gaming device was the [cathode ray tube amusement device](https://en.wikipedia.org/wiki/Cathode_ray_tube_amusement_device).
[Answer]
You could have 80s/90s style [FMV games](https://en.m.wikipedia.org/wiki/Full_motion_video)! For anyone who isn't familiar with them, they were more or less linear experiences where you would solve a few static puzzles or make trivial choices while a b-grade movie played out clip by clip. This seems a perfect fit for your scenario - have a mechanical/hydraulic/whatever computer handle the game logic, while the states of the game are represented by switching between different projected films. Input could be anything from buttons or levers for multiple choice selection, as a minimal implementation, to a keyboard/console if your computers are advanced enough (and you have enough film to make a game that complex). A traditional FMV game would more or less proceed in a 'choose your own adventure' manner - press the right button and you see the good scene, or else see the bad scene.
Alternatively, if you wanted to get really baroque, you could apply the same principles of using projected films as a display, but with multiple projectors capable of movement. With that, you could conceivably implement say a side-scrolling platformer: one static projector for the backdrop, maybe another for the platforms, a projector exclusively for showing the hero - you move the hero projector around on rails playing a looped walking animation, then switch to a different loop of film for a jumping animation, all the while running the backdrop and platform films at a speed corresponding to the players left and right movement...... But at this point we might be stretching the limits of verisimilitude. Still, it could be done with the technology you've described, given a lot of time, and some *very* patient and capable programmers.
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If I had to make a fully mechanical "computer game", I would use mechanically moved cutout figures behind a somewhat shady glass frame. The background could be projected from dia-film, or a perpetuated painting. With this setup you could have a lot of games from driving simulations and shooters (FPS/TPS games) to adventure games, and using multiple layers of glass planes with special optical properties between the player and the cutouts, a pretty realistic look could be achieved.
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Game machines are possible. For example, fully mechanical slot are doable, and simple games can be done fully mechanical such as pinball machines. [Pinball in his origins](http://pacificpinball.org/articles/origins-pinball) was what would appear to be sophisticated billiards, but it evolved to be something different (as you can listen on [99% invisible episode 135](http://99percentinvisible.org/episode/for-amusement-only/)).
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Yet, I guess those aren't video-games. For video-games to exist, you need some form of video.
So, how can you create video without electricity? I'll provide a solution that uses only solid mechanical solutions, that is clock work tech that can be worked prior to the steam engine and requires no electricity. Clock work energy (springs, loads, etc...) can be applied if needed.
Visual output options:
* You can use plotters [I don't mean large format printers, I mean [plotters](https://www.youtube.com/watch?v=NAsM30MAHLg)].
* Another option for display is to use mechanisms to flip panels "pixels", where one side has one color, and the other has another.
* You can use mechanisms to rotate needles (I mean, like clocks do) or rise small flags.
* You could rise and move figurines to make a mechanical cutout theatre.
*The OP claims to have a video display similar to LCD screens.*
Internal logic can be done fully mechanical, for demostration see this [LEGO NAND gate](https://www.youtube.com/watch?v=q8oohrO7ZEQ). AlthoughI would supect his idea of LCD screen uses his idea of logic gates based on fludics.
Anyhow, if you have logic gates you can build computers [from NAND to Tetris](https://www.coursera.org/course/nand2tetris1). You can use that display solution of choice and it would allow to build a mechanical Tetris. Which, I hope, there is no arguing regarding whatever or not it is a video-game. **It doesn't have to end with Tetris, you have computers! you have turing completness! program whatever you want.**
For audio, you could always use bells (or horns for that matter), or allow the a phonograph to play or something like that.
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Note: You could also add a printer for text output, if you consider text only games to be video games. In case of doubt, make it work like a type writer.
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Thinking beyond solid mechanics, I have come up with another idea: you could have a machine that has hydraulic fluids of multiple colors, and have them fill small translucent cavities arranged as a large panel. To avoid having the fluids mix, you can have an RGB arrangement, so that each cavity is dedicated to a color.
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For abstracts: you can make game machines + you can make machines output video + you can program Tetris in a machine => you can make video-games. QED.
[Answer]
Absolutely.
Mechanical games have been around for quite a while. The predecessor to [pinball](https://en.wikipedia.org/wiki/Pinball), for instance, was around in the 1700s, though bumpers weren't added until the 1930s, and flippers until 1947. Still, the electronics in a pinball machine would be easy to replace with fluid, and the scoreboard could easily be lit with lights.
Similarly, the venerable [Pong](https://en.wikipedia.org/wiki/Pong) could be made into a purely mechanical game today, even going as far as having a wind-up motor to run the game; a fluid-driven motor would be quite simple.
Of course, you may argue that those games aren't, strictly speaking, video games, which is true. However, with just a little bit of stage-magic, it's easy to convert a purely mechanical game into a "holographic" game, through the use of curved, mirrored glass, such as that used by the game [Time traveler](https://en.wikipedia.org/wiki/Time_Traveler_(video_game)). The game itself would, technically, be purely mechanical, but miniaturized. A bright light, shining onto the game, would cause the image to reflect from the curved screen, giving the illusion of both size and depth.
With a little mechanical work with mirrors, it wouldn't be hard to convert a [tilting maze](https://en.wikipedia.org/wiki/Labyrinth_(game)) into a joystick-controlled game; pushing the joystick right would tilt the maze, as well as a series of mirrors, which would lead the player to believe that the joystick motions move their character, rather than the board itself.
Shadows could make excellent "video" displays; a light, shining past a set of figures on thin wires, would cast dark shadows. As the characters move, the wires are twisted, causing the characters to either change shape (by having different profiles), or appear and vanish (by simply being flat). A game like [Space Invaders](https://en.wikipedia.org/wiki/Space_Invaders) would be fairly simple to design.
One step further, you could use fully colorized "sprites", drawn on sheets of clear glass (plastic would be easier, if possible), in front of a scrolling, fully colorized background. A second, synchronized roll would have a cutout area for the player to move through. As the background scrolls top-to-bottom, the player's character can move left and right, controlled with a joystick. A third layer of sprites would contain a sheet with the 'bad guys' for the player to avoid - oncoming vehicles, falling rocks, or pitfalls in a race track. In fact, this kind of game could be made into a multiplayer game quite easily, just by adding more joysticks and player scrolls. The entire game could be purely mechanical.
On the other hand, you could make a choose-your-own-adventure style game, with full-scale video and few (or at least recycled) choices, such as [FMV](https://en.wikipedia.org/wiki/Full_motion_video) games. As long as you have several reels of full video tape with a system able to mechanically switch between them, it becomes almost trivially easy to write a game.
You could combine any number of these, as well; a holographic side-scrolling game, a shadow board with full-video cutscenes, or even a mechanical game with full video projected on it.
In all these cases, each machine would be nearly the same size as a modern arcade machine. In fact, using scrolling paper or video would mean that a single basic machine could have several "adventures", each with their own set of scrolling paper, meaning the manufacturer could spend more money on producing games, and less on producing game cabinets. If taken to the logical extreme, a gaming cabinet could be purchased much like as a game console is today, with replaceable cartridges to play different games, even replaceable controllers!
As long as full video type screens exist, any number of games are possible. Look through older video games, like Pac-Man, Asteroids, Space-Invaders, and so on; the amount of code to write those games is tiny, easily enough for an optically driven machine. As long as the screen exists, the game can be written for it. A hydraulic system that opens and closes tiny holes, allowing a bright light to shine through, would be a fairly simple way to implement a projection screen capable of full video; from there, it's easy to make a game, and cheaper than using optics, too.
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[Question]
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Can a planet possess more than one ozone layer? Can multiple ozone layers cause more harm? If one ozone layer had a hole, would the other(s) act like a backup shield to harmful rays from a star?
Assume the star is similar to the Sun and the planet is habitable.
Thank you!
[Answer]
Yes, in fact **we have an extra one right here on Earth**. Mostly found in large cities, we call this layer smog. It's pretty harmful, because it's not at the right altitude. At sea level, it's just a pollutant. Here's a nice picture showing what we have:
[](https://i.stack.imgur.com/7bs3P.png)
Here's the NASA website I got it from: <http://spaceplace.nasa.gov/greenhouse/en/>
[Answer]
Note: there is no such thing as an ozone *layer*. What is called ozone layer, as if it were a sort of crystal shell high in the atmosphere, is actually a volume of increased ozone density, so that the density function with height behaves a little like this:
```
%
| #####
| # ###
| ### ###
| ############ ############
+------------------------------------------------------> outer space
```
But ozone density is never zero anywhere. As per @Alpha3031's answer, you can have more or less temporary conditions in which you get ozone near the ground from photochemical smog, or near the border of the ecosphere, or anywhere in between.
So "more than one ozone layer" would imply a density function more or less like this:
```
% Second layer
| First layer ######
| #### # ##
| # ## # ##
| ## ###### #####
| ###### #########
+------------------------------------------------------> outer space
```
# Question 1: "More than one ozone layer".
**Yes, but it's tricky**
The ozone layer is actually a dynamic phenomenon taking place in a volume of space where oxygen density, ultraviolet light from the Sun and (photo)catalytic processes from several substances (e.g. chlorine from chlorofluorocarbon compounds) interact in a narrow range of ways.
So the greatest problem is having a high enough atmospheric column where the oxygen concentration is *just right*. This requires a shallow gravitational potential (the shallower, the best), which means a large, not so dense planet, and this has its drawbacks (technology as we know it is hugely based on iron and elements heavier than iron). Also, atmospheric pressure at sea level depends on the height of the atmospheric column.
Once we have enough oxygen in the air to work, we can pursue two different avenues. With reference to the ASCII graphics above, you either raise a second "hump" far enough from the existing one, or you spread the one hump you have, and drive a "wedge" in the middle to split it into two.
* two different ozone sources. One is the Sun; the other "hump" would need to be a source at the right wavelength originating in the opposite direction, from the surface, and could not obviously be reflected from the Sun (UV at that wavelength are blocked by the ozone layer, and *that* is what creates the ozone layer in the first place). One possibility could be secondary ionization from shorter wavelength UVs, that do not get absorbed by the ozone layer (I'd need to check the transmittance curve of ozone - if it's flat at the key frequency and below, we're out of luck: there would be no "shorter, unabsorbed wavelength"). These "UV-D" rays would penetrate a bit more, hit some replenishable atmospheric constituent - perhaps nitrogen - that's denser than ozone, and release their energy as less energetic UV rays that would get refracted and, if these newborn UVs are the right frequency, generate more ozone "some way down".
This phenomenon *already happens* in the atmosphere with normal ozone, which is one factor, together with atmosphere mixing, that makes the ozone layer "thick": it's actually several intertwining layers that scatter and amass. You'd need to do it with a different substance so that the separation between the two "humps" is larger, or you'd end up with a very thick, but single, ozone layer.
* one creation, two destruction mechanisms (standard spontaneous recombination being one). The ozone is generated in a thicker layer thanks to a shallower gravitational potential or a larger UV input from the Sun, then this large hump is split into two by e.g. some gas that deposits in the atmosphere at a specific height (we're doing *wild* assumptions on atmospheric diffusion and upper-atmosphere winds...). The gas is a sort of super-[halogen](https://en.wikipedia.org/wiki/Halogen), a super-chlorine or super-bromine, and catalyses the 2O3->3O2 ozone-killing reaction with such efficiency that where the gas is, no ozone at all can abide and you have a deep "wedge" separating two "humps". As a result, to all intents and effects you've now got *two* ozone layers, and only need to explain how the catalytic gas layer is kept together.
You could have some unknown process (high energy collisions, but with what?) generate [unumseptium](https://en.wikipedia.org/wiki/Ununseptium) atoms in the upper atmosphere. Its reactivity against ozone ought to be frightfully high (**update**: it actually isn't, see Wikipedia), even with a half-life of milliseconds, and the small half-life could help explain the localization of the layer - Uup atoms don't wander far from their birthplace before alpha decaying.
Another more promising possibility, and one which already happens, is you have a volatile molecule where a sufficiently evil halogen is bound to something keeping it quiet. Then the molecule diffuses in the high atmosphere, and *almost* the same UV rays that produce ozone destroy it, thus freeing the halogen atom, which proceeds to destroy ozone before combining with water vapour or hydrogen or something else and precipitating away. This is what happens now with chlorofluorocarbons.
You might also imagine a large fleet of aircraft with some ozone-harmful chemical in the exhaust fumes (this also happens in reality).
# Question 2: "Can multiple ozone layers cause more harm?"
Ozone layers do not cause harm *per se*. What they do is intercept radiation and either absorb it or reflect it back at the same wavelength or at a longer one ("greenhouse effect").
In the appropriate circumstances both phenomena might be either harmful or beneficial: think some organism that needs radiation at a specific wavelength, or a planet that would be too cold unless some of its thermal emission was bounced back to heat it a little more. The same layer would be harmful to the former and beneficial to the latter.
# Question 3
**If one ozone layer had a hole, would the other(s) act like a backup shield to harmful rays from a star?**
Not entirely. What would happen is that the depletion of one layer would increase radiation on the surface, but it would depend on the amount of the ozone shielding left. The layers are not "redundant", each one is there because of a specific cause.
Also, depletion of one layer would increase radiation in the volume of air where the second layer is, and might then lead to the thickening of the second layer, leading to a null net effect on the surface (as far as radiations go). The thickening of the second layer might also have other effects, some beneficial and some harmful.
[Answer]
**A second ozone layer could form IF a second UV source can be invented**
NASA describes how ozone is made in a rather [excellent paper on atmospheric chemistry](http://www.esrl.noaa.gov/csd/assessments/ozone/2010/twentyquestions/Q2.pdf). In summary, UV light hits an O2 molecule forming oxygen ions that bond with other O2 molecules to form O3, or ozone. Since it takes UV light to form ozone and Earth's ozone layer absorbs 97-99%, creating a second ozone layer would require a second UV light source that doesn't come from the sun. If a second major UV source could be invented then a second ozone layer could form.
From the article:
>
> Stratospheric ozone is formed
> naturally by chemical reactions involving solar ultraviolet
> radiation (sunlight) and oxygen molecules, which make up
> 21% of the atmosphere. In the first step, solar ultraviolet
> radiation breaks apart one oxygen molecule (O2) to produce
> two oxygen atoms (2 O) (see Figure Q2-1). In the second step,
> each of these highly reactive atoms combines with an oxygen
> molecule to produce an ozone molecule (O3). These reactions
> occur continually whenever solar ultraviolet radiation is present
> in the stratosphere. As a result, the largest ozone production
> occurs in the tropical stratosphere.
>
>
>
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As far our current knowledge of atmosphere and oxygen bonding types stands, no, multiple layers of ozone are not possible. But that shouldn't stop you. You could employ other ***ozone like*** layers for the same purpose. For example, try something like nitrogen ozone layer or carboxy ozone layer. These don't exist naturally yet but hey, fiction is fiction.
However *if* they were possible and present, then yes, the damage of one layer would be covered up by the layers underneath it.
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Frankly speaking, I haven't come up with a design for my dragon; however, I want to design a dragon that can feast on the energy released from the constant bombardment of cosmic rays (either solar or interstellar high energy particles) with the air molecules in the Earth's atmosphere and discharge the stored energy from matter-antimatter collisions into its surroundings to blast away its enemies. I'm having difficulty deciding whether to go for a biological version or a mechanical one since I know gamma ray do lots of damage to DNA, but the charged particles would short-circuit electronic components.
My question is, do I go a for biological or mechanical dragon and how can my dragon go supernova without dying? Using late 22nd century technology and DNA splicing (hybridization), I need you to help me to design a dragon that can turn the tide of battle.
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Well... I work with antimatter as a Physicist and I could object that your dragon would probably not have enough energy to do anything :(
Let me explain it a little bit better: the big problem with antimatter is **confinement**: antimatter has the tendency to annihilate with matter, so your dragon should have a built-in [electromagnetic trap](https://en.wikipedia.org/wiki/Penning_trap) inside his own body in order to store the antimatter needed for his attacks. Furthermore, even in this case the quantity of antimatter it could store is realtively small (10^9-10^10 particles with potentials of the order of 10 kV and magnetic fields of the order of 5-10 T). Moreover, said trap could be used to collect only **low-energy particles**, which are a really small fraction of the cosmic rays you want to exploit. So, it would be biologically unfeasible.
Maybe, a mechanical dragon could prove more effective, provided that it could store some milligrams of antimatter (1 gram = Nagasaki atomic bomb when annihilating with matter), but it would probably require too much energy to store it and to mantain the trap active (thus preventing the dragon to blow up himself). See [this Wikipedia link](https://en.wikipedia.org/wiki/Antimatter_weapon) as a further reference.
So, my answer is *you can't in a world similar to ours*, at least relying on the current laws of physics.
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Andrea Jens' answer is pretty much unassailable (can't top first-hand experience!) but here's a hand-wavery kind of answer that may give you some ideas for how to adapt your original idea:
1) **Containment**: as Andrea explained, you need a magnetic trap to contain antimatter, and it would be very difficult (if not outright impossible) for a living creature to sustain such power levels. So I suggest that the beast be engineered with plutonium slugs in its heavily-armored spine which can fuel the containment fields within its gut.
2) **PewPew!**: The beast could have a metallic weave internal along the antimatter-storage pouch, leading along its throat and out its mouth. When it wants to destroy something in front of it, it would stretch the normally spherical field into a needle-width tube that sprays an extremely narrow stream of antimatter (on the order of milligrams, as Andrea suggested). The magnetic containment field would end shortly after its teeth, causing the antimatter to violently detonate in whichever direction the dragon was aiming.
3) **Additional considerations**: since the field would be passively supported by a nuclear reaction, rather than the dragon's organic processes, it would be maintained even in the event of the beast's death (as long as its gut or spine weren't blown up). In addition, it wouldn't have any way of generating its own antimatter, so it would have to be supplied externally (possibly it would be "born" with a 10g supply, and use only a few milligrams for a sustained burst).
4) **An all-natural alternative**: if you wanted to mix a fantasy and sci-fi setting, and have an antimatter-blasting dragon without needing genetic engineering, you could use the same suggestions above, with the additional caveat that the creature would slowly accumulate the necessary raw materials within its skeleton over the course of millenia. So, younger dragons would spew radiation clouds, older ones would be able to shape the radiation with magnetic fields, and ancient dragons would have a small amount of antimatter (accumulated over millenia) to fire.
Again, it's all handwavium, but hopefully there's something here you can use to bolster your original idea.
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Well as mentioned you need a biological or magic way to contain the antimatter. If we are already talking about dragons that can project breath attacks, then it's not too far fetched to have one that mixes antimatter into his.
Your Dragon will probably expel some manner of graviton waves so they can carry the antimatter to the target. However this Dragon will probably have a very finite limit of times or at least a great delay between when he can use this attack.
I would also argue that this would be a dragon accustomed to the void or something similar, which is why he would use such an attack. Basically, and environmental reason for not basing his breath weapon off something more easily attained. Extreme circumstances tend to generate extreme creatures
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I need an advice about creating an independent city (a city state) in the middle of a desert (the stony kind of wasteland). I will scratch what I have in my mind so far and I would be glad to hear if this is a realistic scenario and how to make it as realistic as possible.
My world is quite hot and around the equator, there are extremely hot wastelands. Some distance from the equator, the conditions in terms of temperature are compatible with living, though still hot (imagine Egypt or Libya during summer). The land is quite hostile and there are little to no settlements or villages.
However, there exists an oasis and one or two big rivers surrounded by some area of fertile soil around which big (50-100k) cities formed.
In terms of history, these cities were formed by outcasts from more habitable zones located in north and south of the desert (imagine how Australia was originated) and grew at these few habitable places simply because there was nowhere else to go for the citizens (everything around is a desert or a very hostile land, though the population is limited by the ability of the city to produce food at its location).
I know I have to consider several things, like water (oasis or river + maybe some underground source), food (basic agriculture based on irrigation), shelter (mainly stone) and access (occasional caravans but besides that, the city is quite isolated). There might be two or three such cities in the desert in quite big distances from each other.
Is this a realistic setting? What other things I have to keep in mind when designing such city state?
What are your tips for agriculture in terms of basic groceries and plants?
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In order to have dry conditions at the equator, you need to have either a very large landmass (the size of Asia) or a very low % of the world covered with water, or both of these.
But besides this, yes, the setting is acceptable. My assumption is that the rivers are flowing toward the equator from the more humid places. These rivers are a very good mean of transportation. The water can be used for irrigation and if the water is plentiful, it can give a very high agricultural production. If it's like Egypt, you should expect a very high density of population on the banks of the river.
Oasis cities can be linked, although, I doupt we could have many cities of 50k people built around oasis. Several roads existed in these areas on Earth, such as in the Sahara and the Silk Road crossing the Tarim basin. The city would likely need to be self sufficient on food and water but it's not necessary since they are on a trade road, they can trade what they are not producing.
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Yes, your setting is reasonable. Apart from describing where the people came from, your description sounds very similar to the setting of Mesopotamia created by the [Tigris and Euphrates](https://en.wikipedia.org/wiki/Tigris%E2%80%93Euphrates_river_system) rivers. Some of the early great [civilizations](https://en.wikipedia.org/wiki/History_of_Mesopotamia) originated there, so you should have no troubles building a believable world with that kind of geography.
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I agree that the setting is believable, and indeed is similar to the Mesopotamian example given by Green. However, I think this similarity would make the region very attractive to indigenous groups - potentially long before the outcasts arrived. This may be an opportunity to deepen the region's history.
Considering your example of the settlement's history being similar to that of Australia, an indigenous presence is a fundamental part of the story - it was the source of much violence and continuing racial tension.
There are also other things to consider, as it is simplistic to see Australia's colonisation as simply a collection of convicts or outcasts choosing to relocate.
There were many factors which made it possible, which included vast support from the British Empire who had widespread colonial interests. This support included experienced governance, resources and volunteer migration schemes offering land or passage to non-convict settlers.
Additionally, there are other examples of migration which you could explore. The [Ostrogoths](https://en.wikipedia.org/wiki/Ostrogoths) are one example of an entire tribe who were forced into migration and resettled several times, coming into conflict with the regions they resettled in.
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I recommend reading "Dune" by Frank Herbert for some ideas on this type of setting - he creates a brilliant dessert planet and accounts for everything in it.
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**The Background:**
I am going to be asking a series of questions that will be relevant to forming some sort of a picture of human space commerce.
Let's say that Earth-based human civilizations have discovered a series of ancient jump-gates that allow them to travel within a large and varied interstellar network.
There are not many clues, apart from the jumpgates, as to *who* left this system behind. For the moment, I am assuming that there is no bias to the kind of systems included in the network: i.e. its not like systems with earth like planets make up the majority of the planets in the network. So, "system types" have roughly the same probability of occurrence as if one were just taking a cross-section of space and scanning it.
Put another way, the gates simply connect a large number of close-by star systems, rather than a large number of only useful star systems.
While genetically-engineered humans exist in this "universe", no sentient non-human aliens have yet been encountered.
**The Question:**
How easy would it be to find potable water in space? Can passing-by ships simply "mine" ice comets for water (take off chunks of ice and melt it, et voila!)? Or, is it that while water is common enough to find, infrastructure would be needed to separate it from other stuff it might be found with, making it usable for humans?
I ask in order to determine if travelling through space is akin to travelling through deserts: few sources of potable water, and "caravan rest stop" like structures are an important, if not absolutely necessary, piece of infrastructure.
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There are sources such as comets, but of course they are reasonably dangerous to approach. Though having some kind of scoop might work to follow a comet and 'catch its tail'.
Though water is very recycle able and while some will be lost into space through different means a 'refuel' of water shouldn't be an extremely common need. More common need might be to scoop up hydrogen and other elements to use as a propellant for the ship. catch in the front and send out the back at high speeds.
But as far as water, it's water and a good filtration system can purify it. Even if you can't find H2O if you can find Oxygen you are golden, since Hydrogen is everywhere especially around gas giants. Our solar system has water on the Moon, Mars, Europa and comets in large enough quantities that we can detect it from here. So barring any accidents for emergencies between care use and recycling a ship shouldn't have an imminent need, though being careful, topping off and knowing where the water sources are on any trip/route is still a very good idea.
EDT: After reading one of the other posts, it turns out that Oxygen is the [3rd most common element](http://en.wikipedia.org/wiki/Abundance_of_the_chemical_elements#Abundance_of_elements_in_the_universe) in the universe, and large stars can have it in the solar winds. So it could be scooped up with hydrogen while traveling interplanetary in a solar system. Though I think finding a more concentrated source would be more useful.
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## You don't *spend* water
Well, technically you can (e.g. if using it for propellant somehow); but normal biological processes - human life support, farming and everything else only cycles a fixed amount of water. In a closed system, you don't generally need new supplies of water - you recycle the existing one.
Cleaning up the water already in your system is cheaper and simpler than cleaning up water "found" on another space object and you don't have to go and fetch it. So the major source of potable water is the water that *was* potable yesterday.
You'd need new large sources of water only if you expect your colony (and thus your biomass) to grow, but sustaining an existing ship or colony can be done without such a source for a very, very long time. Essentially, you only need to replace water that you lost in some accidents or damage to your ship. Cleaning up your existing water is technologically simple and the major requirement is only a reliable source of energy.
A prime example is our existing spaceships. Even in the current ISS, there's no chance we're bringing in new water all the time - the water that astronauts drink is recycled.
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Good primary concern, water. I'll assume that the size of the opening in your jump-gates limits the size of the ships which pass through them. That rules out our hauling massive quantities of water along with us and leaves us at the mercy of water we find along the way.
My big concern would be radiation. We can probably filter out most of the material impurities from melted space-ice but if it glows in the dark, all bets are off.
At least we would be able to determine that the water is not pure and pitch it back into space, but it would be a little like sea-water. Once your crew is thristy enough, they will drink it anyway.
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Remember that space travel happens at extremely high velocities, and that reaction-based drives consume a huge amount of fuel. Most spacecraft will carry just enough fuel to (1) accelerate at the start of the journey to a very high speed, and (2) decelerate at the end of the journey so they don't crash.
Unless your ships are using some sort of reactionless drive, they're moving way too fast past those asteroids, and it's just not worth it to expend the fuel to match velocities with the asteroid and mine water. It's much cheaper to just bring the water with you.
Fortunately, as another answer pointed out, you don't really expend water during space travel, so it's not likely that you'll run out.
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Limiting factors to shipbuilding generally are its size and weight. Now, with clever piloting, a small ship could dock to a larger asteroid and turn that chunk of ice into a large part of its hull, basically everything but engines and lie support being mined out of the thing. underway, this gives our ship a surplus amount of water to be used as reaction mass for the engines, but it does also increase size and weight a lot.
Removing impurities from the ice is pretty simple with physical and chemical processes, and water itself has a very low chance of being radioactive (Deuterium, Tritium and the radioactive oxygen isotopes are not very stable), so cleaned water from space ice would be pretty safe for consumption, once some salts are put back in - which in turn can be processed out of the human excrements. If you want to go the extra mile: split the water to hydrogen and oxygen and just burn it to get water vapor and heat (maybe even use this method in the heating of the ship? Less interaction with possibly radioactive materials if you just take the electric power from the generator and generate a fuel for the heating with it). And most of the water mined from the asteroid will go straight to the engines anyway, so cleaning and splitting it up is just a step to keep the engines running smoothly.
But if you want an equivalent: As long as you manage to grab an asteroid close to your starting point, you can travel for possibly a hundred years without ever running out of water, even if ou use it up at a rate of 1% per year as fuel while loss due to other reasons is neglectable (which is kind of an estimate for generation ships).
If you don't need water to turn it into fuel/reaction mass, you don't really need to take that much water with you, and it would be more akin to a modern cruise ship: make sure you pack enough so your water cleaning plants can stay online all the time and you still have an overhead in fresh water.
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Is it possible that any life on earth could evolve to live off a liquid which is not water? Something like oil or some other natural liquid?
[Answer]
Water can be substituted with liquid [Ammonia](https://en.wikipedia.org/wiki/Hypothetical_types_of_biochemistry#Ammonia) (NH3) which has many chemical properties which are similar to water and can fulfill most of the roles which are usually fulfilled by water in organic chemistry.
Ammonia is liquid between -80° C and -30° C. So an ammonia-based biosphere would only be possible on worlds much colder than Earth (or with an atmosphere with a much higher pressure).
However, Ammonia has a problem: It is flammable. When there would be an ocean of Ammonia on a planet with an oxygen atmosphere (and don't think you can get rid of oxygen that easily), one spark would ignite it. Burning ammonia becomes nitrogen and water-ice. So most larger ammonia lakes would likely be below an ice layer.
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No, water based life could not swap solvents to ammonia or hydrocarbon. It's far to big of a jump to make. The closest that might happen would be that chemicals from water based biology might be part of biogenesis in a different medium. This would require dumping a significant mass of water based biomatter into an environment with large amounts of liquid ammonia or methane.
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An organism that doesn't require water is called a xerophile. Endoliths -- <http://www.wikiwand.com/en/Endolith> are one example. They live off iron, potassium, or sulfur. Pretty sure there are lots of bacteria that don't metabolize water. And we've witnessed bacteria develop entirely new metabollic pathways. Nylonaise for instance, evolved to metabolize nylon, Escherichia coli evolved a metabolic pathway for ethylene glycol: pathway <http://www.ncbi.nlm.nih.gov/pubmed/6336729>
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How would evolution have changed without the "[reflex arc](https://en.wikipedia.org/wiki/Reflex_arc)", if all reflexes had to go through the brain instead of the spinal cord? Would intelligent species be able to evolve?
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There is no reason intelligence could not evolve under this situation. I am assuming only that for some reason communication of signals in that way was never attempted. What would be different? Well i could speculate the following:
* Intelligence may actually evolve sooner as one needs to preempt
attacks/threats rather than react to them. Intelligent tools such as traps would also be more effective so be more favored.
* There may be more favorable evolution to having a head closer to the limbs. This would improve reaction times. This could be done by a smaller average size too.
* Likely the largest dinosaurs would not have existed in their current state. They seem to have had a higher reliance of this mechanism in order to still react in reasonable time frames. The butt brains myth is an exaggerated version of this. This would hinder them a lot more than us. At very least a long appendage to reach leaves would be more safe than a long neck.
* Butt Brains may actually exist. We can't go to the spine for fast reactions but we want the sensory brain high to shorten distance to eyes and keep eyes elevated. We may end up with an extra brain hemisphere (a southern one) that is situated in a different place in the body.
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Why not? The primary purpose of the reflex arc is to speed up reaction time. It's there because it provided a helpful evolutionary survival trait. But I don't see how it's absence would affect the ability to have an intelligent species. It might even generate one faster, because of the extra wiring. The bigger question in my mind would be what benefit would a species get by 'not' having the reflex arc?
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At bottom, this gets into a discussion of the feasibility of non-distributed vs distributed neuronal plans, right? When we look around all we see, in higher animals at least, are degrees of distribution.
Cephalopods have neural centers in the head & in every tentacle, with the head containing only 1/3 the total neurons. That is a very high degree of distribution.
Most likely, intensive processing of coordinated perception/strategy/action will usually, perhaps inevitably, be favored in a highly integrated processing center (though the octopus may argue that point). Reflex arcs can be seen as hard-wired features adapted to optimize high-value survival stimulus-response action patterns & as such strictly limited in scope, but highly conserved. In the case of cephalopods, it cannot be that simple, by a long shot.
We don't see much or any of the completely non-distributed neuronal systems in nature, which strongly implies these reflex pathways were present early on in precambrian animal life, and were elaborated in tandem with the elaborating cerebral ganglion, etc. This also implies that the alternative is significantly inefficient/disadvantageous, by comparison, or was when body plans were being put thru their paces early on.
Some constraints which might inhibit the proposed non-distributed neuronal plan:
* Reaction propagation delay,
* Loss of opportunity for localized optimization in neuronal mapping,
resulting in likely decreased brain sensory area efficiency profoundly impacting overall brain efficiency, increased
diameter of the spinal cord/vertebrae, leading to loss of potential
flexibility/agility/speed.
* Greater susceptibility to spinal & brain infection.
Hard to see much upside, and therefore hard to see promising evolutionary opportunities for it to have proliferated within a viable body plan.
If anything, the lesson of the smartest of mollusks point in the opposite direction.
All that said, I'm not an evolutionary biologist, so if anyone who is cares to cut all this to shreds, have at it. ;)
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Imagine the Earth is sucked into a wormhole powerful enough to pull it out of it's current orbit. the ones who created the wormhole wanted to move earth to protect it however didn't want their actions/existence known to an underdeveloped earth.
Assuming technological awareness on earth is today (2014), the moon was pulled though with earth and ignoring lost connect with probes (space stations/satellites were also pulled though) what kind of effects would be seen by those on earth.
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Just to start...
Changed stellar patterns (new constellations, etc), different planets visible, possibly differences in the star they are orbiting, unless it is the same size/distance/class. Earth would figure out really dang quickly that it had been relocated.
We have our skies and our solar system pretty well mapped out. If that changed, we'd notice in a big hurry. Even if the new system was unrealistically similar to the Sol system, we'd notice that planets weren't where they were supposed to be, and weren't the same planets, probably within a day.
And travelling through a wormhole is bound to give us some really weird signals, so there's that as well.
In short, modern humanity would notice. Heck, the ancient Chinese and Mayan civilizations would notice...even the Druids who built Stonehenge would notice.
EDIT: Thought of another few things...
Unless we were dropped into the same 'spot' in our orbit around this new star, it would make our current season go all wonky (swap from winter to fall rather abruptly). It'd take time for the temperature to reflect the change, but it would definitely be noticeable and might take a little while to re-stabilize. And unless the race that dropped us into our new orbit was exceedingly precise about it, our weather would see some changes if our seasons ended up altered. If we had a more or less eccentric orbit, or if our axial tilt relative to the new star was different.
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We watch the sun pretty closely. Even assuming the new star had exactly the same size, mass, luminosity, temperature, position, and color (all rather unlikely) surely it's spectrum, sunspot pattern, and any observed solar flares (or other stellar weather phenomenon) would be immediately noticed as being different.
Speaking of solar weather, there would likely be an abrupt (and unexpected) change in solar wind as well, which would deform the Earth's magnetic field in unexpected ways, messing up any instruments that depend on measuring its field strength. Depending on how drastic the effect is, the effect may be relatively weak on Earth, but [magnetometers in space](http://en.wikipedia.org/wiki/Spacecraft_magnetometer) will certainly notice.
And speaking of satellites, bear in mind that, even ruling out space telescopes like Hubble, at least some of them depend on [looking at the stars](http://en.wikipedia.org/wiki/Attitude_control#Star_tracker) for navigational purposes, so they would probably suddenly get very confused about their orientation, and possibly go into uncontrollable spins, trying to find stars that no longer exist. Without knowing which satellites depend on this type of system, and how they would react, it's hard to say exactly what would go wrong on Earth. But it could potentially be very bad (e.g. loss of systems like GPS and global communications).
And this doesn't even count the obvious sudden changes in stars and planets that any astronomer on the night side of the planet would immediately notice.
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The moon would be a pretty big clue. It wouldn't be there.
The moon isn't really captured by the Earth, they are both co-planets in the same orbit. At no point is the gravitational force exerted by the Earth on the Moon stronger than that of the Sun.
So unless this phenomenon was placed to take the moon along too, it would be missing and apparent from the start.
EDIT: I got this line of reasoning from the 1962 essay ["Just Mooning Around"](http://www.bestlibraryspot.net/ScienceFiction/Asimov37/27278.html) by Isaac Asimov where he calculates the "true moon band" from the Roche Limit (where tides break up the moon) to where Solar gravity dominates to be from 9600 - 29,000 miles. Yet the source for 'zone of influence' comes up with a range of some 500,000 miles.
So I still hold that the Earths' influence on the Moon gravitationally is particularly weak and more likely to be disturbed by your average planet snatching device unless great care was taken to avoid it.
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Smart aliens) no change other than a change in constellations.
Dumb aliens) gravitational effects of moving the planet could result in more volcanic activity. This might be at the start where the Earth is removed from its current orbit or at the end when it is placed around a new star and its gravity well now interacts with a new set of planets. With no moon, tidal forces are much less. Many of the animals that live in the intertidal zone will die as the intertidal zone shrinks or disappears. Without the tidal mixing, we might lose some oceanic currents?? Animals (like turtles) that depend on finding their way back to a natal spawning area might be in trouble. Life would go on, but it would be a mess for a while.
Super dumb aliens) The orbit of the earth is changed as it settles into the new solar system. We now get too close to the sun in summer and too far away in winter. All life dies, and the aliens can mine the planet for its minerals. Better luck next time, or maybe that was the plan from the start.
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Basically, my world includes both magical and scientific elements, but it leans more towards being scientifically explainable (even if it usually ends up being more pseudoscience). As such, I want to know how to explain the magic system I’ve developed under a pseudoscientific lens.
Currently, the magic system is explained as the following:
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> Magic originates from the Inner Magic, a form of individual-specific energy reserve that is bound to the mind of all intelligent, sentient life in the universe. The Inner Magic functions via a variety of exotic types of energy, which are called Magical Energies. About 10 percent of the universe’s intelligent lifeforms possess the means to utilize their Inner Magic, and of that 10 percent some species are more capable of learning to use their Inner Magic efficiently. Additionally, some species and individuals possess greater mystical power than others, allowing them to use their magic to affect greater regions and produce more powerful spells. While it can be generated via immense willpower, the Magical Energy that the Inner Magic requires to function is typically gathered from the world around the individual. It can be found in special substances that typically appear as mist, crystal, powder, or smoke.
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>
That’s the basics of how magic works in my world. However, here are more notes:
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> The Inner Magic is almost unlimited in capabilities: with enough mystical power and/or Magical Energy, virtually nothing is truly impossible, as even death can be undone. However, resurrection takes a lot of magical energy and mystical power, almost always more than a singular individual would possess. Additionally, it is possible for mystical power to be transferred, allowing an individual to become more powerful, and for the Inner Magic to be ‘expanded’, allowing an individual to store more magical energy. Lastly, devices utilizing magical energy are possible via the transference of magical energy from an individual who has learned to utilize their Inner Magic. These devices can make advanced spells easier to cast and control.
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Edit:
Seeing as I’ve been told that I need to add an example of what casting a spell looks like, I’ve gathered two excerpts from my story. Unfortunately, I don’t really have more right now. However, both of them are edited from the original text to give a better visual.
First one is an example of building something, in this case a small survival shelter.
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> “Well, here goes,” Blake said, starting to concentrate on the shelter. Soon after, he felt what felt like steam flow out through his hands, and the shelter built itself next to them against a tree, each of its components appearing out of thin air. The result was a makeshift shelter with a sheet of leaves and other foliage to cover it, and a log cabin-like wall to its back, front, and left side.
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Second example is an example of dispelling an illusion spell, in this case a teenage girl who’d disguised herself as a raven.
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> ”Hello, Malandra. Off my shoulder, please. The illusion is broken by your raven form’s abnormal weight,” Kairo said, giving the raven an instruction. Upon hearing the instruction, the raven hopped off Kairo’s shoulder and fluttered down to the ground next to Kairo. Shortly after, a faint light engulfed the raven. The silhouette of the raven’s wings morphed into that of human arms, the feathers merged together to form fingers, the talons expanded into a pair of human feet, and the rest of the body re-proportioned itself before the raven grew in size to about 65 inches in height. In seconds, the raven had fully morphed into its true form; a young girl of about 16 years of age.
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Edit:
I’ve just seen that I was also told that it would be of aid to say what stage science is in. Unfortunately, as of the time of my story… that highly depends on the group of characters we’re looking at. However, the ones who use magic in this story are closer to renaissance-era in terms of where their science is at. Otherwise, you’ve got humans who’ve had lightning-shooting guns, which are only the size of a small pistol yet are still capable of producing twice as much an explosion as a railroad oil tank being shot, since the mid-1990s.
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## Science is only an explanation of nature, it does not tell nature what it can or can not do.
The thing about science is that it does not limit what can or can not happen, it only explains what is observed to happen or not happen. Science does not make gravity hold the planets in orbit, or make microwaves boil water, it only observes that Premise A correlates to Outcome B. Nothing more and nothing less.
So, if you live in a setting where Thinking A leads to Spell B, then science won't even try to refute that fact the spell is real, natural, and scientific any more than it tries to refute the existence of other strange forces like magnetism. Instead it will just try to explain that there is a correlation between the Thought, the Caster, and the Spell that results.
If this relationship can not be explained through the 4 fundamental forces of nature, it simply means that nature, in your setting, has more than 4 fundamental forces. Think of magic as being a lot like electromagnetism. We don't notice it in our day to day lives as a force, but it is the color we see, the heat we feel from the sun, the binding forces that hold our atoms together, so on and so forth... but when you levitate an object with magnets, it looks an awful lot like magic.
Likewise, in your setting, "Inner Magic" is a force of nature that normally just exists in its equilibrium, defining our laws of nature in ways that we are just so used to they are taken for granted... but then your thoughts have the ability to disrupt this flow of magic, the same way that a magnet disrupts the flow of electrons allowing for some very strange outcomes.
Explaining EXACTLY how spells work will likely be outside of the ability of your scientists the same way the explaining how thoughts and feelings work is slightly outside of the ability of our scientists... but they will understand it well enough to be able to statistically model magic and come up with a bunch of "theories" and "effects" to describe repeatable patterns.
So, the Witherspoon principle might be a scientific theory that states that magic of a destructive nature is easier to caste when angry, and the magic or a restorative nature is easier to caste when sad. And then there should be competing theories to explain magic like how modern science supports the Scalar Theory of Magic that says that magic is a continuous field like the Higgs Boson field, and you can explain how it supplanted the older Psychic Projection Theory that explained magic as particles emitted from your brain. Then you can have scientists arguing about how to fit the Inner Magic Force into a unified field theory. Oh, and no system of magic is complete without a few good paradoxes like the Grandfather Paradox that says that causality violating magic can violate its own causality, even if that prevent the spell from ever being caused: and you though that the Barber Paradox was maddening.
In short, as long as magic follows actual rules, and the people in your setting have names and descriptions of these rules, then magic will be indistinguishable from science.
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A frame challenge: the point of science is not to be the stupid smart guy in the white coat who insists that the magic has an explanation in terms of things that he understands (and gets eaten by vampires in the second act). Science is to go out, measure, make hypotheses, measure again, revise, measure again, establish principles, form new hypotheses on the basis of the principles, measure, and repeat. Principles that hold in other circumstances provide useful guides to hypotheses, but **the scientific description of magic is a list of successfully tested magic related hypotheses**.
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I don't think you can except by saying that the Inner Magic doesn't obey to any laws, they can create matter to form what you want, they can take matter away , they can do anything from what you have wrote, a character has created a shelter from thin air, leaving me with 2 option (that i see).
InnerMagic is Transdimensional, with your will your able to reach into other dimensions and pull objects/matter from anywhere on other universes to right where you want them,the raven for example can be explained as you being in the middle of 2 dimensions (yours and the bird you take the form as) and use the crow like a puppet, hence why it seems like they are transforming when the little girl morphs, its the bird going into his original reality while she is manifesting herself into ours (i doubt that would be a beginner spell).Just like the shelter could be re arranged particles from said dimension or ones home dimension.
Other wise you would need the science in your world to not have Physics rules that say that matter cant be created or destroyed only transformed, to explain it because without any Extra Dimension or Plane of existance (lmao), its impossible for her to keep her weight while being a crow, she would be too dense and die of lack of oxygen in minutes, about the shelter its where i come to a stop because nothing even pseudo Scientific can explain matter appearing from "thin air", but you can always just rearrange molecules structures to form wood leafs etc.
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## When the laws of physics aren't enough
Before we describe a world with more "I think therefore I spell-cast" than our own, lets posit a world with *less*.
Let's postulate a universe where self-awareness is impossible, but the laws of physics are *no different*. There is no obvious contradiction in doing is, all particle physics would still be unchanged. No one can rule-out the existence of that [p-zombie](https://en.wikipedia.org/wiki/Philosophical_zombie) realm. Interestingly, the same idea applies for [quantum collapse](https://en.wikipedia.org/wiki/Wave_function_collapse).
But a p-zombie universe may still be *different*:
Suppose you write *I am self-aware, I **feel** my own existence*. Are you a Python program written to print this? No difference between IRL and p-zombie. But were you *inspired* by *actually feeling your own existence* and such inspiration made you write this? That would not happen in the p-zombie dimension. (An ideal p-zombie is indistinguishable from a person, but here I argue that they would actually act different in subtle ways).
It's likely that the p-zombie universe would have *much* slower technical advancements than our own. There would be a language, but words such as "meta-cognition" "consciousness" "self-awareness" would lose most of their meaning. Technology would develop (even more so) akin to the (mindless) process of natural selection and evolution. Art and music would be *far* less prevalent (both in production and appreciation). *P-zombieland* would also lack the kind of genius and deep understanding of people such as [Richard Feynman](https://en.wikipedia.org/wiki/Richard_Feynman).
## More of what we have
Our own self-awareness, even though it is [unfalsifiable](https://en.wikipedia.org/wiki/Falsifiability) *did* help us make "magic". As the user MS pointed out, electromagnetism is the *ur-example* of a magic becoming science. Our drive to understand it, boosted by *not* being p-zombies, led us to make ever more [powerful and dangerous](https://www.youtube.com/watch?v=amhIDpvgxvo) "enchantments".
In our universe there is a circuitous path from self-awareness to advancing science/magic/tech/whatever-you-call-it. However, in your universe there would be a *shortcut*: Where the same fundamental laws of reality not only allow conscious self-awareness but also let it impose itself onto the world more directly.
The details of the magic are up to you! There could be a cost for complexity and size: limiting both the detail and the scale that the magic can work on. There could be "lei lines" where you get more bang for your buck. Large populations could drain the aura in that area, temporary or permanently. You have a lot of flexibility in your rules.
Different species may have different levels of "consciousness mind" (i.e. Orca>Human>Monkey>>Insect). Or there is only one level of "mind" but more intelligent animals are more likely to activate their *spark*. Or there is an "apple to orange" situation where i.e. humans are better at magicking machines with gears and metal arms but octopi excel at [soft-body robots](https://www.youtube.com/watch?v=4WV9XnoxZ24) and formations of coral rock.
There may also be limitations in terms of conservation of energy and nuclear transmutation. No "lead to gold"!
Because your magical system is bound to consciousness, magic and tech are partitioned more cleanly. In our universe AI is threatening several creative fields. However, in your universe the "self-aware" barrier (likely to need quantum computing) will keep magic "safe" for a long time. Tech retains most of it's use-cases: large [earth-moving equipment](https://en.wikipedia.org/wiki/Bagger_293) and mass-production would out man-hour your wizard miners. Automation can work 24/7 and handle way more at once than a human mind. Magic may *help* in the process of (dis)assembling machinery. However, a complexity-limited magic would *never* replace photo-lithography.
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This magic can be explained **in exactly the same way as our own magic.** It goes roughly like this:
-- there are planes of existence outside of the material one on which humans live, and those other planes are inhabited by various beings who may be able to interact with the material plane;
-- with some training, you can learn to contact these beings;
-- once you learn to contact them, you can try to talk them into doing things for you on the material plane;
-- if you manage to convince them, they will.
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Perhaps there is a side effect of the magic, which means technology cannot directly record what is happening - so the burden of proof in a scientific world is not met.
Also, you might consider that those not attuned to magic are somehow veiled with forgetfulness, or somehow feint in the presence.
there could also be those who are magically inclined, but not able to use it who become voyeurs of what is going on, but whose memory is affected leaving them sceptical of themselves.
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If your magic is a kind of Inner Magic, why not associate it with the very genetic structure of an individual (like in *Harry Potter* in which magic is somehow in blood)? I don't know much of the biology but I know that there are 46 chromosomes (23 pairs) in human body. Also in hundreds of thousands of years of evolution, parts and excerpts of those chromosomes have rearranged among themselves to bring out new characteristics.
If your world is set in a sufficiently distant future, there would be enough time for humanity to have evolved on a genetic level to bring up a tiny amount of Magic Genes inside chromosomes spontaneously. If 10% of the species of the universe could perform magic, I reckon they be closely related to humans. But currently the number of species closely related to *Homo sapiens* is very less than 10%. But you also see that if there has been enough time for evolution, as I already said, there are possibilities that more *human-like* species would arise.
The ability to perform magic depends on the genetic makeup of the concerned genes. An entire generation could be good magicians given their previous generation was too. Magic would be an inherited trait. Since you said an immense willpower can alter your magical abilities, it will sometimes become an acquired trait which may or may not be passed down the next generation depending on how the next generation babies are raised.
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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.
Fairly straightforward. I suspect that we'd notice the gravitational effects of it long before we'd be able to see it, but at what point in history would people start noticing that stars jitter around in a specific point in the sky every month?
Note: A black hole with an Schwartzchild Radius the size of the Moon would have the mass of 588 Suns. Tidal forces would shred the entire solar system, so that wouldn't make a very good world BUILDING question.
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John Dallman calculated that the Moon-mass black hole will have a Schwarzschild radius of ~50 micrometers. That's pretty small, but will the lensing effects make up for it? We can get specific about it by solving for the angular size of the BH's [Einstein ring](https://en.wikipedia.org/wiki/Einstein_ring) when lensing the disk of the Sun:
$$\theta\_{1}=\sqrt{\frac{4GM}{c^{2}}\cdot\frac{D\_{LS}}{D\_{S}D\_{L}}}$$
Where:
* $G$ is the Gravitational constant, $6.6743\cdot10^{-11}$ `m^3 kg^-1 s^-2`,
* $M$ is the mass of the lensing object, $7.348\cdot10^{22}$ `kg`,
* $c$ is the speed of light, $3.0\cdot10^{8}$ `m s^-1`,
* and the various $D\_{...}$ are angular diameter distances of the Lens, Source, and distance between them.
[](https://i.stack.imgur.com/K8UmO.png)
[Angular diameter distance](https://en.wikipedia.org/wiki/Angular_diameter_distance) is distance defined in terms of an object's physical size, $x$, and its angular size, $\theta$, as viewed from Earth, $d\_{A}=\frac{x}{\theta}$. Angular diameter of the Sun is about $0.53\frac{\pi}{180\cdot3600}$ radians. The angular diameter of our black hole however . . . is nearly zero. For small angles, $\theta \approx \frac{x}{d}$, where $x$ is the transverse size of the object and $d$ is our distance from it. Plugging in our values we get: $\frac{5.0\cdot10^{-5}}{3.84\cdot10^{8}}=1.3\cdot10^{-13}$ radians.
* $D\_{S}=\frac{1.496\cdot10^{11}}{0.53\frac{\pi}{180\cdot3600}}$,
* $D\_{L}=\frac{3.84\cdot10^{8}}{1.3\cdot10^{-13}}$,
* $D\_{LS} \approx D\_{S}$.
Let's see how this pans out . . . Completing the computation, we find the angular diameter of our Einstein ring to be: $\theta\_{1}=2.716\cdot10^{-13}$ radians, or about $0.00000008$ arc seconds. The Hubble Space Telescope has an angular resolution of around $0.04$ arc seconds (at 500 nm wavelengths), and the human eye can resolve objects as small as $40$ arc seconds.
I'm not sure if a telescope the size of Earth itself could resolve even that . . .
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Edit: Starfish Prime calculated the maximum size of the Einstein ring radius to be $0.15$ arc seconds when the object being lensed is 2x lunar distance from Earth and situated exactly behind the black hole. Maybe a comet on close approach, or a near-Earth asteroid could give such a large flare. The closest comet ever observed was Comet Tempel–Tuttle in 1366 at around ~9x lunar distance.
Nearby objects (up to 2x lunar distance) will have larger lensing effects, but for background objects like the Sun and stars the Einstein ring radius approaches $0.00000008$ arc seconds.
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Edit 2: Here's a Desmos calculator of all this to play around with: <https://www.desmos.com/calculator/pot7wiymj6>
The largest contributing factor to the Einstein ring radius (when all else is constant) is the angular size of the black hole in the sky. A micrometer-scale black hole viewed from hundreds of thousands of kilometers away is really just too small to be seen.
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There's an online [Hawking Radiation calculator](https://www.vttoth.com/CMS/physics-notes/311-hawking-radiation-calculator). That tells me that a black hole with the same mass as the moon (0.0123 Earth masses) is only a tenth of a millimetre in diameter and has an effective temperature of only 1.6 degrees Kelvin. The time until it evaporates is extremely long at 5.8E44 years.
Its tidal effects are far more noticeable than its effects on our view of stars; I suspect its presence would not have been deduced until Newtonian gravity was understood, and that might well have been delayed by the absence of a visible Moon.
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So, this is slightly awkward to calculate, but I think I've found a nice simple answer that doesn't require anyone to integrate anything, which is nice.
The effect you're interested in is called [gravitational lensing](https://en.wikipedia.org/wiki/Gravitational_lens) whereby light from a distant object is bent around a massive object between the emitter and the observer.
We know the mass of the moon $M$ (~7.4x1022kg), and how far away it is $D$ (~385000 km). The lensing effect is at its strongest when the lens is exactly mid way between the emitter and the observer, and the strength of the lensing effect can be shown by the [Einstein ring radius](http://spiff.rit.edu/classes/phys240/lectures/grav_lens/grav_lens.html):
$$\theta\_e = \frac{4GM}{Dc^2}$$
where $G$ is the gravitational constant and $c$ is the speed of light.
$\theta\_e$ turns out to be ~0.15 seconds of arc.
That's quite small. The smallest feature that can *theoretically* be resolved by a telescope has an angle of $\theta \approx 1.22\frac{\lambda}{d}$ (see [Airy disc](https://en.wikipedia.org/wiki/Airy_disc) or [diffraction limit](https://en.wikipedia.org/wiki/Diffraction-limited_system)) where $\lambda$ is the wavelength of the light you're considering and $d$ is the aperture of your telescope. In theory, then, a perfect telescope with an aperture diameter of ~80cm observing 500nm light should do the job... unfortunately, [atmospheric interference limits resolving power of terrestrial telescopes](https://web.njit.edu/%7Egary/202/Lecture6.html) to no smaller than about 0.3-0.5 seconds of arc, even for great big telescopes on the top of high mountains.
This means that until the advent of fancy toys like space-based telescope (eg. Hubble) or clever interferometry (like the pair of telescopes at [Keck observatory](https://en.wikipedia.org/wiki/W._M._Keck_Observatory)) the fuzzy blob that your moon-lens generates is simply indistinguishable from any other fuzzy blob your telescopes can see.
Hubble was launched in [1990](https://solarsystem.nasa.gov/missions/hubble-space-telescope/in-depth/), and the Keck interferometer was fired up in [2001](https://www.jpl.nasa.gov/missions/keck-interferometer). There's not much scope for spotting lensing earlier than that, I suspect, though maybe the sheer weirdness of the invisible tidal source woudl encourage earlier investigation.
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**Maybe no Telescope?**
[](https://i.stack.imgur.com/Qmtvy.png)
Other answers point out the black hole is smaller than a grain of rice. Even if the hole was directly in front of the Sun, you would not see the *black spot* we are all familiar with.
However! The moon hole's gravity still pulls at things hundreds of thousands of miles away. This is now you see the hole. You watch as it lenses things behind it by bending the gravity around it.
Here is a GIF from the N.A.S.A of lensing when one star passes in front of another. Even though the back star is blocked, some of the light from it bends around and the total brightness is more than the front star alone.
[](https://i.stack.imgur.com/QeLNc.gif)
Your moon hole does the same thing. For example when it goes near the rim of the sun, it will appear to create a little lump on the circumference, as light that would otherwise shoot out into space gets bent around and hits the planet. Note the black dot in the picture will not be visible. It is there to indicate the hole's position.
How big of a telescope you need will depend on how big is the lump.
If anyone would like to do the calculations for lump size be my guest!
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A giant hole exists in the earth surrounded by a super material that can withstand the extreme temperatures and pressures from the crust to crust through the center core of the earth. It is perfectly straight. The material that keeps the hole open maintains an even cave temperature throughout.
How would atmospheric pressure change from the surface to the core? If the hole joined the North and South pole, wouldn't that be different than if it was opposite ends of the Equator, given centripetal forces of the earths rotation?
First Edit:
I'm not holding answers to the hard-science tag, but I would appreciate seeing the math or explanations.
This question is only about atmospheric pressure. We can imagine this hole is perfectly maintained (no rain gets in) and keeps temperature steady (unless having temperature that matches the earths layers makes the question easier to answer).
Second Edit:
My interest in this question is to imagine a person traversing such a hole. When would it be lethal? Looks like it would be around 3-4 bars or about 1000km down the hole? The best "real world" data we have on this is from the [Galileo spacecraft's probe](https://www.britannica.com/place/Jupiter-planet/Temperature-and-pressure):
[](https://i.stack.imgur.com/r4RTr.jpg)
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Equator to equator or pole to pole will be roughly the same as the centrifugal force difference is only about 0.3% that of gravity.
My calculus is not up to the maths, but it would be fairly easy to come up with an approximate number using a spreadsheet with a line for every 100km down to calculate g. I haven't done the maths but the pressure will be very high indeed.
<https://www.researchgate.net/figure/The-temperature-pressure-phase-diagram-for-nitrogen_fig1_315888614>
Assuming the air is just composed of nitrogen (probably a reasonable approximation) anyone falling into the hole would experience ever increasing pressure as they descended towards the centre with no liquid or solid surface being encountered, just a slow imperceptible transition to supercritical fluid at very great depth.
Any seriously large radius hole of this type could also swallow the entire atmosphere.
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**About 6 billion atmospheres**
This is a bit more nuanced than it seems. On the surface of the Earth, we approximate a linear relationship between height and pressure, but even that [can be seen to be less than accurate](https://study.com/academy/lesson/the-effect-of-altitude-on-air-pressure.html#:%7E:text=How%20much%20does%20barometric%20pressure,every%205%2C000%20meters%20in%20elevation.) even in the troposphere. (BTW, the width of the hole doesn't make an appreciable difference unless the hole holds enough air to significantly lower the extent of the atmosphere...the increase in weight is cancelled by the increase in area.)
The problem is that air is compressible. As a result, the higher the pressure becomes, the denser the air is...so the increment in pressure is proportional to pressure. As such, the relationship becomes more exponential. There's math to account for that, but instead of fleshing it out here, I'll just use [this handy calculator](https://www.mide.com/air-pressure-at-altitude-calculator).
The average radius of earth is (on average) 6378100 meters. Entering that as a negative altitude gives us about 228 billion atmospheres.
[](https://i.stack.imgur.com/8iTDN.png)
Now, this tool probably doesn't take into account the fact that the gravitational pull of the earth decreases linearly as we approach the center. This reduces both the direct and incremental contributions of the densest regions of air, reducing that number considerably. For instance, if we shave 10% off the (negative) altitude, it shows us less than 132 billion atmospheres, a reduction of about 43% based on the weight of the highly compressed air at the bottom. However, the pull of gravity on that highly compressed air is, on average, only 1/20 of that affecting the surface air. In turn, due to the assumption of constant gravity, the total amount of air in the tunnel is less, further reducing the resulting pressure.
If I get the chance to work out that math, I'll update this answer. Until then, I'll do some math handwavium and propose that the correct answer is on the order of magnitude of what the calculator offers in the area of halfway down the hole (-3189050m), where its overestimation of the gravitational effect seems like it should be about right for the rest of the correction. For this depth, the calculator offers 6,186,467,404.49 atm.
Of course, it will probably go solid well before that point...there may be the possibility that the amount of solid air packed into the hole could severely deplete the atmosphere.
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# Some Approximations
I invoke the holy mathematical rite of symmetry to reduce this problem down to 1 dimension: depth.
As you may recall, the standard equation for pressure-at-depth in a fluid is $$P=\rho g h$$
Some people will look at this and say "hey, the pressure must be 0 at the core of the earth because the force of gravity equals 0 in the middle of a sphere." I had that ungodly reaction at first, but the light of reason penetrated my mind.
While it is true that gravity does equal 0 in the middle of a sphere (and likewise 0 inside a hollow shell, for you devotees of the hollow-earth), it is not the case that there is absolutely no pressure in the exact middle of each planet. This is an affront to common sense: what about the many atmospheres worth of air on either side of you, each side equally attracted by gravity to the other half?
If we consider only a hemisphere of the earth at once, we eliminate these infernal conundrums and maintain the applicability of the familiar equation.
# The "Back-of-Napkin" Solution
Let's substitute *g* for the portion of the universal gravitational law it represents, $\frac{Gm}{r²}$.
We can also substitute $\rho$ for mass and volume.
Using the above substitutions, we get... $$P= \frac{G m² h}{Vr²}$$
Which is [actually supported by others who did more complicated mathematics](https://www.physicsforums.com/threads/pressure-at-center-of-planet.66257/#:%7E:text=If%20the%20density%20is%20uniform,pressure%20P%3D%CF%81gR%2F2.)! This gives us 347(10^9) Pa at the center of the earth for rocks. Figuring your gas would be easy- just insert the nominal density of your air. This introduces some complications, though...
# Some Homework
You can take the above equation and account for things, like the effect of heat increasing or decreasing air density, but that is really beyond what I can do for a internet post.
Does the atmosphere in the hole do something weird which invalidates the above equation? Entirely possible that it becomes a solid (or some sort of fancy "liquid") as you go down. Such gems of knowledge such as the density of nitrogen and other atmospheric components at extreme temperatures and pressures is sadly unavailable to me. Otherwise, one could figure out the pressure of each gas/liquid/solid as you go down, and use that to determine overall pressure with the approach I outline here.
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I'm writing a short story that takes place many decades into the future. A major plot point is that a car that was promised to a future archaeologist via inheritance has naturaly eroded to the point that only a few scraps remain.
The following are true.
* The car was parked in a remote field in rural Oklahoma.
* The car is not near a body of running water, is not in direct sunlight, and is parked on rocky soil that cannot support large amounts of vegetation.
* No human being had ever interacted with the vehicle since it was abandoned. Either directly or indirectly.
* The car is parked in the partial shade of a rock crag.
* All that remains of the car are a few scatted pieces of scrap to signify that a car was once parked there.
* The car in question was a slightly used 2019 Honda Civic.
Only taking natural forces into account, how long would it take the car to near-seamlessly erode into the environment while still leaving some material trace?
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>
> I feel very comfortable with a prediction that a Honda Civic left
> unattended and exposed to the elements would be recognizable as having
> once been some kind of car 100 years ago but now little more than
> rusty bits. I expect there to be little to even suggest it was a car
> after 200 years apart from the engine block and drive train.
>
>
>
We have an abandoned car that looks to be 70 years old in our forest (admittedly not a field). It is almost completely disintegrated. I only know it is a car because I took a good look at the odd rusty thing sticking out of the ground.
Here is an image of cars from the (in)famous Belgian Car Graveyard.
These were working cars at the time they were abandoned. A mechanic did not know what to do with them in 1966 following France's withdraw from NATO.
[](https://i.stack.imgur.com/YOgjW.jpg)
Even in dry places cars disintegrate rapidly. These cars were abandoned about the same time (60-70 years ago):
[](https://i.stack.imgur.com/pM5gs.jpg)
Finally, here is an actual 1978 Civic happily on the entropy highway. It is 42 years young and stored in a barn out of the elements!
[](https://i.stack.imgur.com/ocH4A.jpg)
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10 years - car looks the same, tyres are deflated.
100 years - car's paint failed, car looks rusty all around. Interior rot away, with dust and goo covering the insides.
1000 years - through holes became much more noticeable, doors fell off, front window fell in. Soft insides are empty, dried and wiped away by the wind, just bare metal and solid plastic remains visible.
10 000 years - structure completely collapsed. Car's middle part is now thin, trunk is a bit higher, motor is the most noticeable part - as a pile it is higher. You can recognize that it is a car only from front glass - it is now dark from oxidized plastic layer inside, but shape is recognizeable.
100 000 years - majority of the mass in this pile is not from a car anymore. Even slightest wind would have by now removed rusty particles and oxidized plastic particles, and add natural dust instead. Glass still can be seen partially exposed from the pile, sanded down to a matt surface by even a slightest wind.
1 000 000 years - at this time scale diffusion begins to play a role. Even remaining glass parts will begin to diffuse with particles around them, merging on the surface. Pile will become one solid rock.
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Regardless of how fast it actually disintegrates, in a few hundred years at most it will be covered by dirt and other debris, therefore cannot be found without digging. Objects tend to "settle" into the earth. This is caused mostly by wind pushing sediment against the object, along with seeds that produce vegetation that attract even more debris. In a hundred years, you probably can see some of it. In two hundred, maybe not. Maybe an object on a high rocky mountain would be visible longer, but that venue seems largely inaccessible for your story type, and is pretty far from what you envision already.
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There's one thing to keep in mind about parking this thing in Oklahoma: the wind is infamous for a-sweepin' down the plain. The trivial answer to your question is "until a tornado hits it". If you don't get hit by a tornado but are simply in the general area *near* one, you can experience wind gusts of [100-150 mph](http://climate.ok.gov/index.php/site/page/news/oklahoma_mesonet_site_records_tornadic_winds) over a swath nearly a half mile wide. Being hit by flying debris at those speeds - or by the large hailstones that frequently accompany tornadoes - can [tear a car](https://www.weather.gov/images/lub/events/2012/20120429-storms/hail_damage_auto_bg.jpg) [to shreds](https://www.onlyinyourstate.com/oklahoma/1990-hail-storm-ok/) (it's like being hit by a baseball that was dropped from an airplane at cruising altitude). Even Oklahoma's non-tornadic winds can throw gravel and small rocks hard enough to put a deep gouge in the paint, crack glass, and bring tree limbs down on top of the car.
Once the car's outer protection is damaged, the real deterioration begins. Exposed metals start rusting out. Plastic parts will photodegrade over time, and rubber parts can dry out, stiffen, and crumble within a decade. Critters move in and start tearing up the interior. Once it sits long enough, the ethanol can separate from the rest of the gasoline and start [corroding the vehicle](https://www.equipmentworld.com/equipment/article/14952223/e-10-alive-the-corrosive-damage-ethanol-gasoline-does-to-your-fuel-pump) from the inside within a few years. Once the tires go flat and disintegrate, you'll have metal parts in contact with the ground where they'll encounter more moisture and rust faster.
As all these components start breaking down and falling apart, the Oklahoma wind will blow the loose bits away. The prairies of Oklahoma naturally experience wildfires [every 1-30 years](https://extension.okstate.edu/fact-sheets/fire-effects-in-native-plant-communities.html), which will strip your car of anything left that's remotely flammable.
The final remaining pieces of the car that will be left over and in a recognizable state will be portions of the engine block. It's a large, solid hunk of metal and will take a very long time to rust away completely. It's possible that some of the large fiberglass body panels might be recognizable for a while, but only if they can manage to stay in pieces large enough to not get blown away. Some large portions of the metal frame may also still exist, as they're typically treated to inhibit rust.
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The time-stream is the normal passage or flow of time and its historical developments, within a given dimension of reality. Elder gods are all-powerful beings that exist outside this reality within their own dimensional plane. As they are not subject to the traditional rules of time and space, they are able to view the time-stream in its totality. This allows them to observe all events from past to future at once as would a spectator. These gods are able to enter the stream from their dimension onto the mortal plane. However, as time operates similarly to the flow of water, the current of the stream can ebb and flow in both direction. This makes their control over where they enter is extremely limited. They can aim for the middle ages and end up in the 51st century, as they are subject to the volatile tide of the stream at that point. The solution to this would be a physical manifestation of themselves called an avatar that can serve as an anchor to a specific point in the stream. These avatars would function as "landing zones" that would operate as a beacon, guiding the deity through the rough flow of the stream, similar to the purpose of lighting houses serving as beacons to ships on the open sea. To accomplish this, I would need help from mortals on the other side to build this avatar on their behalf, and must find some way to communicate with lowly mortals to carry out its desires.
The problem is that the minds of humans are frustratingly fragile, while the mind of a god is vast and incomprehensible. Any human that touches the mind of a god will go irrevocably insane. Even cults devoted to worshiping it are not immune to this fact, as they may be subject to misinterpreting the my will. This often devolves into human sacrifices and goals of ending the world in order to bring about their my return. Written texts are also not an option, as this can lead to the same problem. A god can clearly and plainly dictate its intentions (Thou shalt build an avatar of thy lord, and not kill each other in the process of thy making it) and those same followers would spend decades debating and interpreting the meaning of their words and their deeper meanings. This would also devolve into schisms of faith as different factions fight over minuscule differences, leading to religious wars. (You humans are weird that way I guess).
How can I make known my actual will and guide the hands of my followers from a higher dimension without directly communicating with them?
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## Show them in their dreams
Dreams can be complex and highly fantastic. Human mind can handle complex things happening in dreams that they might not be able to handle or comprehend in real life. The vast and incomprehensible mind of a god can be depicted with signs and images in dreams.
Humans spend about one-third of their life sleeping. Thus, it is an efficient way to deliver messages and signs. When people realize that they are seeing the same or similar dreams, they will understand that there is a higher power guiding them.
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Leave your message to a "man in the middle": be it the bowels of some animal, the flight of the birds, coffee grounds, the stars, some colored stones, a set of game cards, molten lead in a fresh egg, the flame of a fire...
Mankind in its history has read the future and the will of the gods in many, many way.
Profit from this and use one of those method. And if anything goes wrong, you can always blame the reader. And if they read your shopping list as the latest and greatest will, well, sit down, grab some popcorn and enjoy the view.
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**Evolutionarily.**
Followers will do various things they hope will please their deity. Initially these things will be fairly random. Some will come closer than others to actually pleasing the deity. Those followers who are "colder" will be punished - maybe a tooth will fall out. Followers who are "warmer" will get rewards - maybe they will regrow a lost tooth. Rewards and punishments will of course vary as such things do. Ideally (but not necessarily) both reinforcements should carry signs of divine intervention.
It will take many iterations as well as communication between followers but eventually rewarding the pleasers and punishing the displeases will result in a fine group of deity pleasers. Their creativity might actually please the deity more than what the deity came up with itself.
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> This allows them to observe all events from past to future at once as would a spectator
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Then either a) you're stuck in a predestination paradox, because you can already see the outcome of your influence and there's nothing you can do differently (because you're already going to have done it) or b) you can violate causality which means you're free to try literally anything at all, and if you can see that it didn't have the desired effect in the future then you can try something different in the past.
Timey-wimey balls play havoc with plans.
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The world: sky nomads in solar-powered airships, roaming planet earth
The technology level: 2030s or 2040s. The airships are similar to the IRL designs LCAT60T airship by Flying Whales, Airlander 10, and Aeroscraft made by Worldwide Aeros Corp.
The question: how do they acquire food in the sky?
You may be thinking: couldn't they just land and get terrestrial/aquatic food? Yes, they can and they do. But they're sky-folk. They love the sky. They wear feathered garb. They should eat the sky too – fish the sky so to speak. It's an æsthetic thing. Ground-dwelling birds like bustards are less suitable than high-flying birds like swans for that reason.
Now these nomads are planet-wide, so they can go to different regions, following bird migrations and flocking/nesting events. (There's an old anthropology joke: 'nomad' is a word that means 'follow the meat'.)
One way to catch them would be a net extended below the ship, similar to a fishing trawler. The airships are faster than most birds and could scoop em up. But maybe there's a more interesting technique to trap em or hook em.
Aaaand, possibly a dumb question: what about the plant component of the diet? There are no plants in the air, are there? Or does the sky have some equivalent of phytoplankton? Maybe they could gather some wind-borne pollen or seeds; do any credible food-sources of that kind exist?
Thanks worldbuilders.
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**Air farms.**
These would be zeppelins, green and festooned with vines. Each would be run by an air nomad family that would tend the crops and chase the rain. Air farms would move south and north with the seasons, keeping their fields in the sun. The individual air farmers have different theories about how to pilot the ship to grow the best crops.
There are a few semilegendary air farms that inhabit zones far above where most others stay. If you encounter one, these farms grow some very unusual crops. These high fliers are transparent and the plants grow inside the gas bag, which contains hydrogen with a little bit of CO2.
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I think the easiest solution would be to provide a nesting habitat and harvest/cultivate eggs. Once semi-domesticated, older birds who no longer lay eggs can also be easily captured and culled for meat. This is basically how our neighbors currently manage their chickens.
Plants will likely grow fine in your environment, but if you are looking for plants that are not "terrestrial", there are "air plants", (<https://en.wikipedia.org/wiki/Tillandsia>) and some of them are apparently edible (<https://biology.stackexchange.com/questions/19791/are-there-any-air-plants-with-parts-that-are-edible-for-humans>)
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## Hunter gatherers tend to deplete the environment fairly quickly.
There's a limited amount of food around, and high up in the sky there's even less. They can certainly hunt whatever birds if they want that are high up, or find the few floating seeds around, but there's not a lot. The sky is a food desert, and there's very little food there.
## Farming is needed for large human groups.
They can grow floating gardens, breed birds for meat, and generally generate new food. It'll be very expensive in energy, but if they have enough they can do it.
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The air is a bit of a "food desert", as one commenter said, but not entirely. There are high-flying cranes, eiders, swans, swifts in there. Many birds form flocks specifically to migrate, even if they're solitary when at their grounds, and migrate at considerable altitudes. While it's true that birds-of-prey ignore the air as a food source, hawking birds do not: <https://en.wikipedia.org/wiki/Hawking_(birds)>
The way I would handle this is basically adapt this trope – <https://tvtropes.org/pmwiki/pmwiki.php/Main/SpaceIsAnOcean> – so that birds are fish, airships are ships. Then you have all the fishing techniques: trawling, trolling, longlining, etc. available to you. Hunters could leave the mothership in a glider or hangglider with a spear-gun or trained bird (<https://en.wikipedia.org/wiki/Parahawking>) to go after big game like the trumpeter swan.
This page might be of interest. It's about how radar (plus pattern-recognition software) can find big flocks of birds/bats/insects in the air: <https://birdcast.info/about/weather-surveillance-radar-and-bird-migration-primer/> – think of modern trawler boats that use sonar to find shoals of fish.
Sustainability will be a concern: the air is a much thinner ecosystem than the sea, and if hi-tech aimed to gobble up all the flocks to exploit it for profit, they would destroy it in short order. If they're just trying to sustain a small population it should be alright. You mention that they get food from land and water sources as well, which helps lighten the ecological burden.
As for plant matter in the air, I found this – <https://web.archive.org/web/20140602090548/http://westrocketry.com/sli2008/PLAR_MadisonWest2008.pdf> – which says "we found the most pollen in the third sampling range, 2327-1580 feet. This matches the Leon findings, where they found the most pollen at 600 meters, or 1,950 feet." Some pollens are edible: <https://northernwoodlands.org/knots_and_bolts/edible-cattail-pollen> – You would have to think up some kind of filter that can suck in & concentrate the air's pollen.
PS: Some more math on the pollen. <https://askinglot.com/how-can-you-tell-how-much-pollen-is-in-the-air> says "A count of 50 pollen grains or less is considered low, and a count of 1,000 pollen grains or more is considered high. Subsequently, question is, is the pollen count high? A high pollen count is considered 9.7 to 12.0 grams of pollen per cubic meter." – so a HIGH count is call is 10g of food per m³, and a LOW count is about 0.05× that, which is really quite a lot of food if you think about it. An airship moving through the air, ingesting air through some sort of (futuristic, nano-engineered) filter, would easily pass kilos and kilos of pollen.
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Just net some birds.
Lookout:"Captain, a murmuration of Starlings off the port bow"
[](https://i.stack.imgur.com/GbsRTm.jpg)
Captain: "Helmsman, intercept! Bow nets ready to catch. Concussion grenades on my command!
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NOW!"
\*Boom Boom\*
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Netsman:"Positive catch, Captain. 7 tonnes on the gauge! We feast like kings tonight!"
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Maybe build some kind of hangar ? Or use hooks to catch a smaller and more mobile flying ship ? Even it smaller they fry too you know :D
It's more efficient to use smaller flying ships and make it mothership kind of idea than upgrading the mothership and make it do all the work. Hey it saved material and cost for maintaining the whole thing too :D
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Disagree with people saying the sky is a food desert. The sky is full of life.
[](https://i.stack.imgur.com/KCqWe.jpg)
Some people have mentioned birds and pollen, but you're all forgetting about insects:
* [Our VLRs [vertical-looking radars] record large-scale wind-borne migrations 150 to 1200 m above the ground (fig. S1), involving billions of insects](https://www.researchgate.net/publication/41408422_Flight_Orientation_Behaviors_Promote_Optimal_Migration_Trajectories_in_High-Flying_Insects)
* [one in every 17 creatures floating (or flying) in the air is a spider](https://thefactsource.com/can-spiders-fly-they-are-found-3-miles-above-ground/)
* [When British scientist Jason Chapman told us (listen to the radio piece or watch our video) there are 3 billion insects passing over your head in a summer month, he was talking about his survey in Great Britain. Closer to the equator, he says, the numbers should rise. He wouldn't be surprised, for example, that in the sky over Houston or New Orleans there could be 6 billion critters passing overhead in a month.](https://web.archive.org/web/20210402183750/https://www.npr.org/sections/krulwich/2011/06/01/128389587/look-up-the-billion-bug-highway-you-cant-see)
* Note that those numbers are post-insect-apocalypse. They would've been maybe 75% higher if you measured them a century ago – <https://en.wikipedia.org/wiki/Decline_in_insect_populations> – so depending on how lusty the ecology of your worldbuilding project is, you can greatly increase those numbers
Now, it's too gross to just suck the bugs out of the air and eat them, but your sky-nomads can use them as feed or as bait. (Says you: "Oh but people can eat insects!" Says I: Not like that; you can eat roasted crickets or BSF larvae or something good, not whatever-stuck-to-my-flypaper.)
If using them as feed, catch the insects and them feed them to something insectivorous and convert them to meat. Possibly to iguanas or some insectivorous bird.
If using them as bait, dangle them below the airship to attract hawking insectivorous birds like swifts, then cannon-net the swifts when they come.
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Are there any actions that humans do that could influence whether a magnetic flip (I believe the proper name is geomagnetic reversal) happens? Are there any ways humans could theoretically influence the planet's magnetic field in a significant way? (Intentionally or not).
Nothing here is really off limits, human-caused climate change/global warming, nuclear weapons, things we haven't invented yet (that are still at least somewhat feasible).
But to try and ground it lets say using technology that could reasonably be invented in the next 100 years.
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I will argue that this isn't possible - not within the next century, and possibly never unless we're willing to sacrifice habitability.
I'm a little skeptical of the prospect of achieving a reversal by applying an external magnetic field. There's strong evidence that the mantle can act similarly to a semiconductor, meaning that changes on timescales of months to years are significantly shielded ([Currie 1967](https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/JZ072i010p02623)). Put another way, to in any way affect the core via a magnetic field, you'd likely need to maintain a strong external field for something like decades, which would be extremely difficult to do; the energy required would not be small. If you're capable of overcoming that, then great, but it does seem like a tall order if we're restricted to the next century's worth of technology.
(Bear in mind that we're dealing with [currents on the order of $I\sim10^8$ Amps](https://physics.stackexchange.com/a/342645/56299), which is something like [four orders of magnitude higher than the current in a lightning strike](https://en.wikipedia.org/wiki/Orders_of_magnitude_(current)). Given the size of Earth's core, the current density isn't enormous, but I do want to point out that we really are playing with fire here.)
There have been [claims that other phenomena have caused geomagnetic reversals in the past](https://en.wikipedia.org/wiki/Geomagnetic_reversal#Hypothesized_triggers), and those mechanisms may be worth investigating. Given that [the flow within the core is chaotic](https://physics.stackexchange.com/a/86637/56299), it's possible that relatively small perturbations to the flow, such as from plumes poking down from the mantle, could cause a reversal. The question, then, is how we could achieve this. It's tempting to suggest an impact event or something like it ([Muller & Morris 1986](https://ui.adsabs.harvard.edu/abs/1986GeoRL..13.1177M)), although the required impact would be absolutely devastating to humans, so perhaps it would be best to avoid that one. Trying to modify plate tectonics to influence subduction also seems to fall into the category of "Please don't do that" events.
A final note: We don't have a great understanding of geomagnetic reversals, nor do we have a phenomenal picture of the details of the dynamo processes at work in the core. This is partly why I'm so cautious about the prospect of successfully influencing the extremely complicated processes happening at the center of the planet.
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The magnetic field of the Earth is caused by an electric, self sustaining current in the molten core of the Earth (dynamo). If you apply a huge magnetic field to the circular current (to the surface it encloses), the current will reverse as reaction to the magnetic field you made appear inside. The field has to be increased in the same direction as the inside Earth magnetic field. The current will react to the increasing magnetic flux by reducing its strength and even reverse if the field is further incressed. The field due to the current is then opposite to its former direction. Then you have to reverse the outside field slowly (much slower than the initial increase). This will cause the field due to the current to stay as it is (hysteresis). So you end up with a flipped, man-induced magnetic field.
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I can think of several possibilities that might become feasible in the next century.
**Dropping a nuclear reactor into Earth's core.** A large, very hot nuclear reactor could conceivably melt its way through the crust and mantle all the way down to the core. The reactor could be designed to target a particular destination in the outer core, which would be chosen based on suitable measurements and modeling. Upon arriving, it would increase its power output dramatically. The heat would disrupt the dynamo that drives Earth's magnetic field, causing a geomagnetic reversal.
How much nuclear fuel would be required? As an order-of-magnitude estimate, we might guess that the reactor would need to produce about 50 TW (the approximate total heat flow from Earth's interior to the surface) for a decade to have a significant effect. To do this, it would need to burn about
$$\frac{(50 \times 10^{12} \text{ W}) \cdot (10 \text{ years}) \cdot (235 \text{ g/mol})}{(\text{Avogadro's number atoms/mol}) \cdot (200 \text{ MeV/atom})} \approx \text{200,000 tons}$$
of fuel. The world currently produces around 60,000 tons of natural uranium per year. Although only about 0.7% of that uranium is the fissile isotope uranium-235, a well-designed fast breeder reactor could convert (most of) the remaining uranium-238 into fissile plutonium-239 and then burn it. So this seems difficult but potentially feasible, especially if we assume some technological advances over the next century.
**Building a very large superconducting magnet.** A loop of superconducting wire encircling the entire planet could generate a magnetic field strong enough to directly counteract the natural field from the core.
How much superconducting wire would we need? Suppose we need to generate a field of 1 gauss at the center of the current loop. That's about twice the strength of the planet's natural magnetic field, so it should be enough to reverse the field's direction. The required current would be about
$$\frac{\text{1 gauss} \cdot 2 \cdot \text{radius of Earth}}{\mu\_0} \approx 10^9 \text{ A}$$
Suppose that we are building the magnet from magnesium diboride, a reasonably high-performance superconductor that can be made from commonly available elements. If we assume a current density of $500 \text{ kA/cm}^2$, which is the [reported](https://ceramics.onlinelibrary.wiley.com/doi/full/10.1111/jace.17366) critical current density for a sample of high-quality bulk magnesium diboride, the wire would need to have a cross-sectional area of $0.2 \text{ m}^2$. Since the density of magnesium diboride is about $2.6 \text{ g/cm}^3$, the total mass of superconductor required would be around
$$0.2 \text{ m}^2 \cdot (2 \cdot \pi \cdot \text{radius of Earth}) \cdot 2.6 \text{ g/cm}^3 \approx \text{20 million tons}$$
Every year, the world currently produces around a million tons of magnesium and a few million tons of borates. Converting all of this raw material into superconducting magnesium diboride and building a suitable refrigeration system would be difficult and very expensive. But if we really wanted to do it, a century would be more than enough time.
**Generating a large electrical current in the magnetosphere.** Instead of building a new superconducting magnet, we could take advantage of the large body of conductive plasma that already exists around Earth: the magnetosphere. Again, a sufficiently large electrical current (around $10^9$ amps) could generate a magnetic field strong enough to counterbalance the natural field and trigger an effective geomagnetic reversal.
There are a number of ways to create electric currents in a plasma. For example, one can use an antenna array to [broadcast radio waves parallel to the existing magnetic field](https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.41.873). The waves are absorbed through [Landau damping](https://en.wikipedia.org/wiki/Landau_damping), exerting a force that drives an electric current. As the generated current becomes large, the direction of the overall magnetic field rotates. One can then move the antenna array to transmit parallel to the new field direction, and continue the process until the field has completely reversed.
Could we create a strong enough current in this way? It's difficult to accurately estimate the power required, as many processes in the magnetospheric plasma are nonlinear. We'd certainly need something bigger than [HAARP](https://vlf.stanford.edu/research_topic_inlin/experiments-haarp-ionospheric-heater/), but perhaps not *that* much bigger. The solar wind (tens of gigawatts) is enough to drive the [ring current](https://en.wikipedia.org/wiki/Ring_current) of about 10 mega-amps, despite very low efficiency. So a well-designed space-based antenna array, in a high orbit (for lower plasma resistivity), with a few gigawatts of total transmit power, might possibly be sufficient.
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There is a highly militarized nation of 300k people between 0 and 60 years old – technology level similar to the Romans. For climate, think the Mediterranean with plenty of freshwater (streams & therefore irrigation) and sunlight.
Military service starts at 10 years old. Everyone is enlisted. This is a highly controlled society with very little migration, living under highly regimented rules. These rules are enforced by an external organization so corruption at the state level is non-existent.
They need to produce 61% of the calories required for their own 300k people plus (via trade) another 200k people.
It meets this obligation via wheat, sheep and goats.
They have 100,000 full-time farmers and 77,000 people that never farm (including the children). All other soldiers farm 3 days a week on average
Assuming there is no limit to quality farming/grazing land available, is it possible for essentially 139,000 farmers to produce enough wheat, sheep and goats (milk/butter/meat) to produce an average of 1,400 calories for 500k people?
Thank you for the comments and answers. To try to answer some of them:
The entire landmass is approximately the size of the island of Ireland. About half of that belongs to the nation in question. They garrison the border but there are now wars so they train and farm.
Whilst working on the farm they would live there so food would be consumed locally for 139k out to the 300k. Of the rest 77k would be within a few days travel and the rest within a weeks travel. They have good transportation by road and water.
Women are treated no differently than men, unless pregnant, partially making up the 77k non farmers. Children are raised much more by the community than now so parents can continue to work and train.
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I think its largely doable, though your farmer would need to stretch himself a lot to look after all those herds and farms.
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It implies that the average farmer needs to feed 3.6 people (500k/139k) every year.
Which implies that average farmer needs to grow 3.6 X 1400 X 365 = 1839600 calories per year.
### Case I : Goats / sheeps
1 goat in medieval era weighed ~50kg ([based on primitive British goat](https://en.wikipedia.org/wiki/British_Primitive_goat#Characteristics)); goat weight to meat ratio is 83% ([based on current goats](https://www.huffpost.com/entry/goat-meat_n_5bb64c71e4b028e1fe3bcfa2)); and 100 gram of raw goat meat has [109 calories](https://www.fatsecret.com/calories-nutrition/usda/goat-meat?portionid=61318&portionamount=100.000). Thus 1 goat is worth (50 X 10) X .83 X 109 = 45235 calories. Thus, a farmer needs a new herd of 1839600/ 45235 = 40.67 goats per year minimum. At litter size ranging between 1-2, and gestation period of 150 days, there would need to be another ~20 goats for replenishment. 1 acre land [supports 6-8 goats](https://www.qcsupply.com/blog/product-tips-and-how-tos/goats-vs-sheep.html), so you need approx 10 acres of land for the goats to feed upon.
At 139K farmers, thus, your country must have 139K X 10 = 1.39 million acres = 5625.2 square km of good feedable land.
For comparison, [size of Great Britain](https://en.wikipedia.org/wiki/Great_Britain) is 209331 square km.
While your average farmer is hard pressed for time, the military training should have helped drill better sense of time management and purpose in him/her to manage a flock of 60 goats.
### Case II: Wheat farm
The average yield of wheat was [~300kg per acre](https://history.stackexchange.com/a/16918/3697) in medieval era. 100 gram of modern [wheat flour has 329 calories](https://www.nutritionix.com/food/wheat/100g), we can assume something [similar for medieval era](https://medievalyork.com/2015/05/28/all-about-medieval-english-grains/). Thus, 1 acre could produce 300 X 10 X 329 = 987000 calories. approximately [a fourth would be kept for replanting](https://history.stackexchange.com/questions/9044), and half the land would be kept fallow at a time. Thus, per acre yield = 987000 X 3/4 X 1/2 = 370125 calories
The average farmer would thus need: 1839600/370125 = ~5 acres of land.
### Conclusion:
Hence, seems like a dexterous farmer would be able to pull it off. Both the above calculations do not account for storage, transmission and other losses, such as due to rodents, carnivores, climatic condidtions, thefts, etc.
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***Having done more research on this topic, I've found enough evidence to have to completely retract my previous statement that this would be possible.***
It is true that Romans were much better farmers than most other civilizations prior to the industrial revolution, but they were still pre-industrial. While some estimates say that the Roman Empire was as little as 65% sustenance farmers, the actual evidence of this is highly debatable.
The region of the Roman Empire that produced the greatest excess of food was probably Egypt. According to ancient tax records, Roman occupied Egypt at one point had a population of about 7.25 million people, an urban population of about 1 million, and exported enough food to feed at least 300,000 people (though this last number may have been larger if they were also exporting to places other than Rome itself). So, the Romans could with the labor of 6.25 million people feed ~7.55 million about 2300 calories a day. That is ~2780 calories a day per farmer. Since your population's consumption represents only 1,400 calories a day, you are looking at a maximum sustainable population of 276,000. So your population could maybe sustain itself, but not maintain that level of trade.
Another Roman Farming model to look at is that of Sicily and Carthage. These areas had more access to Roman technology, so they produced more food per capita than the much more populated Egypt. The grain tax of these regions was 33% meaning that the farmers here would have had a higher grain production per capita than Egypt despite a smaller total excess. So by this model you are looking at a farmer producing 3450 calories a day which could sustain ~343,000 people.
Another way to look at this is to examine the total urban population of the Roman Empire as a whole as this will tell you more about their averages. Analysis of their Urban populations show that about [25-30%][1] of their population lived in cities. That said, not all rural people are subsistence farmers, especially in the Roman Empire. Many rural people would be engaged in occupations like mining, lumberjacking, cotton/flax growing, etc. By this estimate we can probably say that only about 65% of the Roman population was needed for sustenance farming, and that many of our other projections that say higher are simply mistaken due to incomplete records of accounting. Based on this model (assuming you are importing all of your cloth, wood, metals, etcs.) your population could support ~352,000 people using your reduced rations.
All of this said, there is one HUGE monkey wrench in all of these numbers. A person who lives off of 1,400 calories a day is not nearly as productive as a well fed worker. So all of these numbers are probably too high. I do not have any concrete evidence about how much less productive a malnourished farmer would be, but according the the writings of Cato, the most productive farmers were well fed; so, reducing your calorie intake may actually lead to a smaller excess of food rather than a larger one. So I will say your farmers need to eat 2300 calories, but everyone else you feed could do 1400. In this model, you are looking at 139,000 people on full rations at any given time supporting about an additional 114,000 people for a total population of 253,000.
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It sounds unrealistic. It wasn't until modern times, with the introduction of synthetic fertilizers and mechanized production, that the number of farmers has been reduced with respect to the rest of the occupations in every state. And even today it's hard if not impossible to be a "part time" farmer.
To have 139k farmers be able to feed 500k people you need way more than Roman level technology. For [example](https://www.nytimes.com/1988/07/20/us/farm-population-lowest-since-1850-s.html) in 1820 USA, farmers were still 72% of total workforce.
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[Total population of USA](https://en.wikipedia.org/wiki/1820_United_States_Census) at those times was 9.3 million people, thus farmers were 22% of the total population, close to the ratio you want to have.
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[Per PBS](https://www.pbs.org/ktca/farmhouses/sustainable_future.html)
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If you have 100k full time farmers for 300k people, you should be good without having any kind of army farm conscription like you plan. Romans had roads, aqueducts, which are probably as important. It doesn't matter how much a farmer grows if there isn't a safe, easy way to get water and food to your city where the non-farmers live.
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## Goat milk!
Anshul Goyal's answer only counted the calorie value of the goat meat itself, but goat milk and derived products like cheese are a huge source of calories. Goat milk is [~70 kcal/100 mL](https://extension.psu.edu/dairy-goat-production) and a goat might give [~2L/day](https://dairyfarminghut.com/how-much-milk-does-a-goat-produce-per-day/) in milk (looking at the low end of the range they give). So each goat that you're milking is, on average, giving you the 1400 calories/day needed for one person. If your 139k farmers can tend about half a dozen goats apiece, that alone would be basically enough, even accounting for some goats not giving peak (or any) production.
Of course, in actual practice you'd have a smaller proportion of your farmers tending larger herds of goats, while others raise other crops to diversify diets and support themselves (and the goats). Given that the real-world nation of Ireland currently has something like 4 or 5 million sheep, I'd expect that your country would have more than enough land to keep less than a million total goats.
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**Question**: How to preserve food (preferably in ready to eat form [[MRE]](https://www.wikiwand.com/en/Meal,_Ready-to-Eat)) for 200-300 years on a spaceship?
Bonus objection: preserve viable seeds for the same period
*Requirements*
MREs should contain all necessary nutrients to sustain humans for a period up to a year without significant and irreversible health problems. All humans are healthy adults working in 8h-long shifts per 24h cycles. Most of the work is not physically demanding, but humans should keep good physical fitness in case of emergency EVAs.
Cooking is not impossible but not desirable, as MREs are meant for emergency and early wake-up crews.
For the duration of the voyage, only micro-gravity in a few small modules is possible and most of the ship interior does not have an atmosphere, but they can be pressurised on demand. Once the colonists reach their destination the entire ship has to have an atmosphere to allow for arrival operation procedures.
*Available technologies*
* suspended animation based on induced [torpor](https://www.wikiwand.com/en/Torpor) [aka hibernation] (this method cannot be used to preserve plants or dead tissues, it works only for living organisms with the sufficiently developed nervous system);
* advanced robotics and automation (the spaceship can travel on auto-pilot for decades, all routine maintenance tasks can be performed by automatic systems, including various bots and drones, but emergencies still require human intervention);
* genetic engineering (mostly CRISPR and similar technologies);
* artificial meat (can be grown in labs, once they are in operation, but the ingredients should be produced or stored beforehand);
* all currently available technologies and those that are currently in development, but not finished, yet.
*Things that **cannot** be done*:
* there is no cryosleep or any other super-technology that allows freezing and unfreezing without any damage (unless some similar technology already exists or is in development and I just do not know about it);
* there are no food synthesisers or 3D printers that can print food or complex molecular structures (all plants and animals are sequenced, but it is not possible to recreate them from DNA blueprints, they have to be physically present in some form);
* there is no AI that could take care of artificial biosphere and keep it going for 2-3 centuries (a permanent algae farm or similar is, however, probable).
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Feel free to ask for additional details or clarification if necessary.
P.S. This is not a duplicate question. While there are other questions regarding food preservation in space, they have fewer constraints and proposed solutions cannot be applied to this particular case.
P.P.S. Food is one of the most important elements of my project, so handwaving is not really an option.
[Answer]
**The regular methods.**
Food spoils by microbial action. Food spoils by intrinsic fast chemical reactions like oxidation of fats. Food spoils by slow chemical reactions, like degradation of vitamins to inactive molecules.
1. Food is irradiated. No microbial life remains.
2. Food is dehydrated. Most chemical reactions occur in the aqueous phase and without water, they will not occur.
3. Food is sealed from oxygen. With no water and no oxygen, oxidation must occur only via any oxygen molecules already in the food.
4. Food is frozen. Wrapped, prepared food will be stored in reflective packages containing radiators, within the spaceship but outside conditioned habitable quarters. It will be under vacuum. It will be cold. The colder it is the slower any chemistry happens.
5. Food is generally not cooked. Cooking can break down vitamins. These foods will be raw.
Even under terrestrial circumstances, desiccated frozen mammoth meat is edible after thousands of years. So too your foods. For example: a reasonably well prepared & sealed container of food (pemmican, chocolate, salt & pepper) can be [perfectly edible after more than a century](https://www.youtube.com/watch?v=562nQKR3_3M). And even a bit of hard tack [approaching two centuries!](https://www.youtube.com/watch?v=Ga5JrN9DrVI)
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Side note re vitamins. I can understand concerns that these would not last a century. One can engineer yeast to synthesize all the vitamins we need. I can imagine a bottle of ice with nutrients and freeze-dried yeast in the cap. On cracking it, one shakes it up and lets it sit for a day. The yeast come to life and do their thing and viola! - instant yeasty vitamin water!
[Answer]
Starship grade freezers store at near absolute zero so just do that. Even a few Kelvin would probably do. I don't know why you're concerned about freezing and unfreezing without "damage". This is food, not a living thing. It's just freezer burn.
[Answer]
## Main Problems
**Hibernation is not Stasis**
Hibernation or induced comas as we call it in humans alone will not keep people alive for 200-300 years. In these states, animals continue to age and consume resources. This could be used to reduce the amount of food your population needs on the trip, but they will still starve to death and/or die of old age meaning you do not have the technology to keep these people alive in this state as described.
So, you will need to do some hand waving to explain how a person can survive a 200 year coma without food or aging.
**Lose of Essential Nutrients**
There are many foods with very long shelf lifes that are considered "non-perishable" but this is a relative term. While some food remains edible for centuries, no food retains certain very important nutritional qualities past 15-30 years. The most notable being omega-3 fatty acids, vitamin-c, and the 9 amino acids that our bodies cannot synthesize on their own. These will break down within this timeframe regardless of what well researched food preservation method you use¹. Failure to preserve these elements would result in health problems including neurological and muscular degeneration and scurvy.
As for seeds, you will need to freeze them to very low temperatures to maintain viability after 300 years. Cryogenic freezing lacks the research to accurately prove the viability of seeds past 20-30 years, but the predictive evidence suggests that freezing to temperatures of at least -135°C may result in you still having a significant number of remaining viable seed after 300 years².
## Possible Solutions
**Time dilation**
Time dilation can solve both your food and hibernation problems, but getting enough of it may be outside of your intended tech level. If your ship travels very close to the speed of light, you can slow down the experience of time for the crew. At 0.999999C, the crew would experience a 300 year trip as only being about 5 months long. This is probably outside of the tech level you are looking for, but in this case humans could remain in medically induced "hibernation" (hibernating mammals can typically survive 5-6 months without eating) and their food would still contain plenty of essential nutrients to sustain good health by the time they reach their destination.
**Advanced Artificial Organic Compound Synthesis**
If your ship has the technology to create its own organic compounds, then this could also help with both problems. Your hibernating crew needs to do more than just sleep. They need 100% of their biological substance slowly recycled back into their body. Through the application 100% recycling, the ship could in theory uptake all of a sleeping person's feces, sloughed off skin and hair, and urine, and turn it back into essential proteins, lipids, carbohydrates, and other micronutrients to keep a person alive off nothing but their own atoms + a bit of electricity. A civilization with this level of bio-chemistry knowledge would probably also have the technology to manipulate the daf-2 gene to halting the aging process.
Things like rice, dried beans, and processed sugars have all been proven to be edible after hundreds of years. Honey too. So, you can just bring these and re-add essential nutrients when you reach your destination using the same general technology.
This might not work with your plot though, because this tech would essentially eliminate the urgency of having a stored food supply; so, you'd have to somehow address why they can't just stay plugged in while their first crop grows.
**Adopt a Hybrid Generation Ship Model**
I think this would work best with your plot and described tech level.
Because they have hibernation based statis, your crew can spend a lot of time asleep conserving energy. This means your ship may not have enough aeroponics farms to feed everyone at once, but it will have enough to feed some of your crew at any given time. Let's say for the sake of argument, that your crew needs to sleep for 5 months at a time, and then wake up for 1 month to eat, exercise, and do all the things they need to do to get their bodies fit for the next hibernation cycle. In this case, a ship with food production capabilities for 100 might be able to transport several hundred colonists .
On the final growing season of your journey, your crew can focus on a crop that is extra high in essential Amino Acids, Omega-3, and Vitamin-C. That way, when everyone wakes up at the same time, this crop can be used to supplement the nutrient deprived stored foods while also placing a sense of urgency on getting their first crop going since their ship is not designed to grow enough for everyone to survive off of.
You'd still need to address the issue of aging, but again, if you manipulate everyone's daf-2 gene before they leave Earth, it's possible these humans have just been genetically altered to be able to live for hundreds of years. Because scientists have already identified the gene associated with aging and a few mutations that are known to slow it down significantly, this may not be as future tech as it sounds.
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*1. By this I am referring to well researched and commercially approved methods of storing food. Dehydration of food to 5-16% water content, freezing of food to anywhere as cold as -40°C, canning, chemical preservation, etc. Cryo-freezing to temperatures below -80°C can preserve amino acids seemingly indefinitely, but the only methods I can find that involve freezing to that low of temperatures that preserver lipids like Omega-3 require adding chemicals that are toxic to humans; so, you could not eat the food when you are done. Research footnotes that I've found suggest that Vitamin-C is also vulnerable to cryo-freezing; though, I can't find anything that explains how much so. New cryogenic freezing methods are being researched all the time; so, slight improvements to modern tech might preserve your food's nutrients for 300 years, but this would would require the OP to relax his/her no advanced cryotech stipulation.*
*2. According to [this research paper](https://naldc.nal.usda.gov/download/42490/PDF), you would probably have about 10-80% of your seeds left germinating at -135°C and 25% or more of your seeds at -196°C. That said, it is important to note though that when extrapolating data this far past your data set you can not predict any criteria that would cause a spontaneous future failure of your whole seed stock.*
[Answer]
This is not an answer, but rather my thoughts on the subject that I decided to share after getting initial responses to my question.
There are three main considerations when it comes to food preservation:
* nutritional value (macro- and micronutrients);
* texture and taste;
* presentation (colour, serving sizes, decoration, etc.)
Available food preservation techniques negatively affect all three aspects. Nutrients are destroyed during preparation for storage and during storage itself, texture and taste may be altered, and presentation may suffer greatly as well. I was looking for ways to negate (to some degree) all three as food is [critical](https://arxiv.org/pdf/1610.00703.pdf) for the [physical](https://www.nasa.gov/sites/default/files/human-adaptation-to-spaceflight-the-role-of-nutrition.pdf) [and](https://www.wired.co.uk/article/space-travel-design-mental-health-interiors) [psychological](https://www.sciencedirect.com/science/article/pii/S0924977X19317237) well-being of humans, especially in space.
**Macro- and micronutrients**
Preservation of nutrients is the most important aspect since there is no external source that could provide missing ingredients. As we know from history and modern research, nutrient deficiencies lead to deterioration of physical and mental health and ultimately death.
While there are some types of food that can be stored sufficiently long for my purposes, they would not constitute a balanced diet. A non-exhaustive list includes raw unfiltered honey, soy sauce, refined sugar, salt, white rice (some varieties), cornstarch, vinegar, pure vanilla extract, low-oil grains, dried tea leaves, cacao, and powdered milk (if frozen).
My research of modern food-preservation techniques (canning, freezing, irradiation, dehydration, controlled atmosphere, chemical additives, fermentation, extraction, and so on) suggests that none of those methods is effective for long-term storage measured in centuries. While it is possible to preserve macro-nutrients, especially, carbohydrates, the degradation of micronutrients, most notably, vitamins poses a big challenge.
Willk's proposed answer is based on the use of these techniques and their combination. It is a good common-sense approach, but it ignores evidence that, for example, blanching is necessary before freezing for many plant-based foods. Blanching is a heat treatment (may reduce Vitamin C content up to 90%) that deactivates enzymes responsible for certain types of food degradation. Enzyme activity does not stop even if food is frozen, it only slows down. Moreover, enzymes become more active during defrosting. (Humans cannot consume all food frozen, so defrosting is necessary and should be included in any discussion of food preservation for later consumption.) Likewise, irradiation and dehydration also [lead to the loss](https://ucanr.edu/datastoreFiles/608-216.pdf) of nutrients.
As discussed with DKNguyen, freezing also does not stop the deterioration of nutritional value. Vitamin C, for example, continues to [degrade at freezing temperatures](https://ucanr.edu/datastoreFiles/608-742.pdf) (-20C). The loss of nutritional value in cold storage as shown in the linked source is negligible when we store for 6 months. However, losses accumulated over a period of 2-3 centuries may be very significant. It is likely that rapid freezing and storage at near absolute zero can arrest some of this deterioration, but so far there is no scientific proof for this.
Freezing also causes denaturation of proteins, which affects some groups more than the others. This may have negative effects on nutritional value and digestion. More research on my part is needed to clarify this in greater detail.
Some commenters suggested using dietary supplements to make up for losses in the nutritional value of stored food. This seems like a reasonable suggestion, but it may pose problems due to [bioavailability](https://www.cambridge.org/core/services/aop-cambridge-core/content/view/2F36AA9D8173C1773004A35DC88D3A51/S0954422494000090a.pdf/human-bioavailability-of-vitamins.pdf) [and](https://journals.sagepub.com/doi/full/10.1177/2397847317696366) [drug interactions](https://academic.oup.com/ajcn/article/85/1/269S/4649453) of the said supplements. Micro-nutrients in food and pills are not always chemically the same and are not processed by human bodies in the same way. Dosages should be calculated very precisely and depend on a big number of factors such as genes, microbiome, diet, and even mood. It is also observed that multi-vitamin supplements can increase the risks of [cancer and cardiovascular diseases](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3309636/).
I am going to do more research, but it seems impossible to preserve the nutritional value of food at high enough levels with contemporary or slightly more advanced technology. Some supplementation is necessary. It also looks like crew members would require close observation and individualised solutions until food production is fully established to prevent nutritional deficits.
**Texture and taste**
Texture and taste are extremely important. If people do not like them they are not going to eat their food or not going to eat enough of it.
Food texture is often downplayed or completely ignored, but it [affects taste](https://www.popsci.com/texture-food-science/) a lot and for many people is a decisive factor in food preferences. I, for one, cannot eat anything resembling porridge: a sticky substance with pieces of something more solid in it. Even thinking about it makes my stomach sick. Moreover, [the awareness of food texture](https://www.theguardian.com/lifeandstyle/wordofmouth/2013/jul/02/food-texture-how-important) is often subconscious, so it may have a profound impact on the perception of food and psychological adaptation and well-being of space travellers.
As for the taste of food, astronauts report that [it changes in micro-gravity](https://www.pbs.org/newshour/science/astronauts-crave-tabasco). This, most likely, can be attributed to physical changes that happen to human bodies in such conditions and loss of sense of smell. Some astronauts complained that sweet food, especially with added sugars, was too much for them. It is also known that spices and spicy sauces are very popular on ISS as they help to overcome the blandness of the food.
Food preservation techniques often lead to changes in texture and taste. Some of them are intentional and some are not. Unintentional changes are usually related to the cellular and molecular damage resulting from preparation for storage, storage, and preparation for consumption (defrosting, hydration, etc.).
Ice crystals formed during freezing (even rapid freezing produces ice crystals, albeit smaller) damage cell walls. [This reduces firmness of the fruits and vegetables](https://pdfs.semanticscholar.org/ef3f/f8a10f1b34583b383420096164d29110016f.pdf) and leads to loss of nutrients and altered taste due to drip loss. The scale of damage depends on freezing methods, species, and specific cultivars.
Freezing also causes denaturation of proteins, which is especially damaging for animal-derived food. For example, [frozen fish](http://medcraveonline.com/MOJFPT/MOJFPT-06-00191.pdf) may lose taste, change colour, and become tougher. This process also reduces the bioavailability of proteins, thus diminishing nutritional value.
Damage to the packaging of frozen food may lead to the loss of moisture and 'freezer burn'. While it does not make food unsafe per se, it makes food tougher and creates eating experience akin to chewing leather or wood. This is highly undesirable in an already stressful environment.
**Presentation**
Presentation of food is another important aspect of preservation. Food that tastes great and has high nutritional value still will not be consumed enthusiastically if it does not look good. Shared meals are also important for morale and teamwork.
This is something that I still need to research. Of course, there are limitations on serving methods available in micro-gravity and a restaurant-style meal would not be possible even if I could teleport it to the ship. I still believe that it is possible to come up with something that will be more exciting and pleasing to eat than nutripaste or soylent green.
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At this point, I am leaning toward freeze-dried food rations kept at near absolute zero supplemented by permanent algae and yeast farms. Algae and yeast cultures are relatively easy to maintain, so this can be done by automatics and supervised by the emergency crew members in extraordinary circumstances. Algae and yeast also have a benefit of easier storage and farms can be scaled up as demand increases. There should also be fewer problems associated with micro-gravity. An additional benefit is that algae farm is a [proven technology](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6960400/) not just for food, but for other life-support systems, and it was already included in my world design.
[Answer]
Why not fill your micro-gravity modules with genetically engineered food forests using artificial light, robot gardeners and simple machines to turn O2 into CO2 so that the plants thrive. This way your crew will wake up to not only food but also oxygen.
Include enough varieties of seasonal crops and vary the lighting schedule in each module so that some food is always ready for harvest. Then while your crew sleeps, process the fruit to create fertilizer and seeds so the robots have materials available to keep the garden going.
Fruits and Vegetables are the original "Meals Ready To Eat".
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[Question]
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I'm trying to figure out a realistic setting that depends heavily on desalinating sea water for desert agriculture. Specifically, I'm trying to figure out exactly how early in the tech tree, this can be done.
The practical way to desalinate water *on an agricultural scale* – that part is critical – is by reverse osmosis. <https://en.wikipedia.org/wiki/Reverse_osmosis#History> says:
>
> Researchers from both University of California at Los Angeles and the University of Florida successfully produced fresh water from seawater in the mid-1950s, but the flux was too low to be commercially viable[4] until the discovery at University of California at Los Angeles by Sidney Loeb and Srinivasa Sourirajan[5] at the National Research Council of Canada, Ottawa, of techniques for making asymmetric membranes characterized by an effectively thin "skin" layer supported atop a highly porous and much thicker substrate region of the membrane... In 1977 Cape Coral, Florida became the first municipality in the United States to use the RO process on a large scale with an initial operating capacity of 11.35 million liters (3 million US gal) per day.
>
>
>
So basically desalination on an agricultural scale started happening in our world in the late 1970s. But how much earlier could it happen? (Again, I'm talking a realistic setting otherwise similar to our own world, no magic or handwavium.)
Clearly, it needs to be after the Industrial Revolution; even if we imagine a medieval alchemist somehow stumbling on relevant techniques in the lab, you need industrial mass production to make it relevant to agriculture, which measures water in acre-feet.
But the above description sounds like a serendipitous discovery, or a large enough R&D budget, might have produced the relevant techniques in 1950.
What about 1925? 1900? 1875? There are lots of things that turn out to have been invented about as early as they could, because of the need for things like high precision manufacturing technology (bicycles, jet engines, computers). And there are other things that it seems really could've been invented earlier had anyone thought of them (stirrups, efficient plows, paper, Chinese wheelbarrows). Which category does reverse osmosis desalination fall into? What are the prerequisite technologies that would need to be in place before it becomes feasible?
[Answer]
You say "The practical way to desalinate water on an agricultural scale – that part is critical – is by reverse osmosis." That may be the practical way at the present, but is it the only possible way that would be practical in any situation?
Any society which has sufficient, and cheap enough, energy available can use that energy to turn salt water into water vapor which can be condensed into fresher water, and the process can be repeated several times if necessary to make the water fresh enough.
>
> The manufacture of salt is one of the oldest chemical industries.[81] A major source of salt is seawater, which has a salinity of approximately 3.5%. This means that there are about 35 grams (1.2 oz) of dissolved salts, predominantly sodium (Na+
> ) and chloride (Cl−
> ) ions, per kilogram (2.2 lbs) of water.[82] The world's oceans are a virtually inexhaustible source of salt, and this abundance of supply means that reserves have not been calculated.[76] The evaporation of seawater is the production method of choice in marine countries with high evaporation and low precipitation rates. Salt evaporation ponds are filled from the ocean and salt crystals can be harvested as the water dries up. Sometimes these ponds have vivid colours, as some species of algae and other micro-organisms thrive in conditions of high salinity.[83]
>
>
>
[https://en.wikipedia.org/wiki/Salt#Production[1]](https://en.wikipedia.org/wiki/Salt#Production%5B1%5D)
So they open the gates and flood the salt evaporation ponds when the tide is high, and close the gates after the ponds fill up, and wait for the sun to evaporate the seawater, leaving salt behind in the ponds.
Suppose that a salt evaporation pond had a greenhouse type structure built above it, to help heat up the air inside above the pond to hasten evaporation, and to contain the evaporated water vapor. there could be a sort of a chimney leading from the greenhouse to a horizontal pipe or duct to carry away the water vapor. There could be many transparent panels in the horizontal pipe or duct to let in sunlight to help keep the water vapor hot.
The water vapor from the original pond greenhouse could probably travel a significant distance inland and maybe up hill during a day when it is heated by the Sun. And after sunset the water vapor in the pipe or duct would quickly cool down and condense, and the pipe or duct might lead to another pond and greenhouse where the water would collect during the night.
And when the sun rose the next day it would heat up the second pond and greenhouse and the water would start evaporating and water vapor would enter another pipe or duct leading farther inland to a third pond and greenhouse.
Thus the salt water could be evaporated and condensed several times until it was sufficiently pure, and transported inland to be used fr or irrigation.
I note that most crops are rather small plants compared to trees, and thus presumably have comparatively small root systems compared to trees. Thus their roots might extend only a few feet underground.
So I would suggest that some sort of watertight floor would be laid down, and several feet of soil laid on top of hit, and crops planted in those beds, and greenhosues built above those beds, to contain and reuse water and reduce the need for more water as much as possible.
And it seems to me that in a 19th century mining town in a desert near the sea where food and water had to be imported a long distance at a large cost someone might have thought of and created such a project to provide water and food for the mining town in an alternate universe.
[Answer]
All you need is a suitable membrane; you don't have to make it yourself. Suppose there is an animal which has such a membrane in its gut -- it uses it to desalinate water. Farm enough of these creatures, harvest their intestines, and you can create your own agricultural-scale desalination plant.
You just have to treat those membranes well and keep farming the saltwater sheep or whatever they are.
[Answer]
**Distillation**
[Meteorology
By Aristotle](http://classics.mit.edu/Aristotle/meteorology.mb.txt)
>
> Salt water when it turns into vapour becomes sweet, and the vapour
> does not form salt water when it condenses again. This I know by
> experiment. The same thing is true in every case of the kind: wine and
> all fluids that evaporate and condense back into a liquid state become
> water. They all are water modified by a certain admixture, the nature
> of which determines their flavour. But this subject must be considered
> on another more suitable occasion.
>
>
>
The applications of distillation to make alcohol would not be developed for some time, but Aristotle recognized you could produce sweet water from various water containing substances by boiling it. Distillation requires energy.
If you had ample geothermal energy this would be doable. Or lots of coal or oil to burn. You could make a solar concentrator; perhaps Archimedes' Death Ray apparatus could be put to use.
To fill a canal with water produced by distillation would require a lot of energy. But canals are wasteful if water is preciousl If I were farming using distilled water I would take care to conserve water and keep it from evaporating away or travelling into the ground. If it were 300BC I would grow my plants in discarded wine and oil pottery amphorae. There were many of these in the ancient world, and broken ones would work well too - fill with soil, bury and grow your plants inside, watering by hand.
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All you need is a few plastic bottles, a straw, some glue and some string.
[](https://i.stack.imgur.com/WzF4k.png)
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Say we have a men vs. orcs warfare scenario in a world with roughly medieval-type technology. The men can see well in daylight, but almost not at all at night. The orcs can see in the darkness of night, but are somewhat weakened in the light of day (but not hindered by lesser lights such as torches).
Presumably when armies march against each other in the surface world, they'll be jockeying to have engagements occur in their preferred light state (men in the day, orcs in the night). But I'm not sure exactly how that would play out.
What tactics would each side use to engage the opponent in the preferred part of the day/night? What defenses would each use to avoid being attacked when they're more vulnerable? Overall, what distribution of day-vs-night fights are likely to occur?
[Answer]
**Attacks will occur when the attackers choose**
One general principle of military engagements is that the defenders choose the ground, the attackers choose the time. No one is going to choose to attack when they are at a disadvantage, so the orcs will attack just before the middle of the night (preferably moonless) while the humans will attack shortly before noon (preferably on a bright, sunny day).
Open field battles can only occur by mutual consent, so they will not occur in human-orc battles - the humans are massively disadvantaged at night and the orcs are massively disadvantaged during the day.
The consequence is that protection at rest becomes vitally important. The Roman legions would march each day for a sustained period and then dig in and fortify the camp they would stay in each night. This pattern is vital for both sides - in order to survive an attack they *must* be protected by fortifications while at rest and they must have warning of a pending attack. Sentries, observation posts and watch animals that can make up for their own sensory deficiencies will be critical. Battles will occur when the visually advantaged group attacks the fortifications of the visually disadvantaged group, ideally in a location where they are unable to fortify effectively.
Strategically, the humans have a significant advantage. Campaigns are normally conducted in summer because:
* in winter the cold is likely to kill more soldiers than the enemy and the ground is wet or frozen
* in spring most of the population is needed to sow the fields and many roads are still too wet at the start
* in autumn most of the population is needed to bring in the harvest and if the campaign takes longer than expected then all the disadvantages of winter are experienced.
These considerations still apply to both races, and days in summer are much longer than nights, giving humans a shorter window of vulnerability and a longer window of opportunity. The orcs may be able to work harder during the summer nights than the humans can during the summer days given the lower night time temperatures, but the relative lengths of day and night are a significant disadvantage.
For those who are thinking that the orcs can be a bit hardier and attack in winter - they need to be *much* hardier, because the winter nights are colder than the winter days. Essentially they are doubly disadvantaged in winter and are well-advised to hole up in their communities and work on their manufacturing, arts and crafts during the long winter nights.
Speculating on possible items that are still compatible with the general technology level - with sunglasses not available, the orcs want fine woven cloth that they can put over their eyes to protect from excessive light. For those who have read the [Belgariad](https://en.wikipedia.org/wiki/The_Belgariad), think about the fine scarfs that Relg and his fellow cave-dwellers put over their eyes to protect from the outside light whenever they were above ground. Conversely, the humans want the ability to create very bright light quickly to dazzle the orcs at night. The simplest way is to have branches with dried leaves kept near a small fire and put them on when required, with an opaque screen on the "friendly" side/s to avoid dazzling humans. Eyepatches are potentially valuable to both sides at night, so if one eye is dazzled then the other eye will still be effective.
[Answer]
**Human heavy cavalry and horse archers, naffatun brigades/Orcish hobilars & heavy infantry:**
Wars are typically fought in the summer, when the roads are passable and labor is available after planting but before harvest. This also means that humans get a big leg up, because this is also when there's abundant sunlight and long days.
I'm making some assumptions, but I'm going to say orcish night vision is somewhat short ranged. Orcs will favor melee fighting and shorter ranged missile weapons they can use at night. I'm also guessing melee weapons favoring wild brawling fights would be best for orcs in the day, requiring less sight and more attacking things easy to see very close by. Orcs are likely to utilize heavy infantry and weapons, trying to draw opponents into grinding, brawling battles (ideally at dusk, so the enemy can see, but the tactical situation will keep improving for the orcs). The orcs are going to need to learn to sleep in the saddle, but not fight there. To counter the extra hours of daylight, the orcs must be on the march during the day when they can't see well. Horses can't see that well at night, so orcs will ride in the day, sleeping horseback as much as possible, but then dismount and fight on foot at night, when long-ranged human weapons will be ineffective.
Humans will do best using their excellent daylight vision to range their attacks. Horse archers can harass orcs all day long. Getting in a brawl with orcs is a good way to die, so they will want to maneuver to avoid bogged-down battle. This doesn't mean, however, humans won't mix it up. Tight infantry formations take advantage of tactics and pikes to hold the orcs in place and grind them while archers and even spear throwers kill them. Because horses favor light, heavy human cavalry will be able to smash orc formations and break off, while the orcs have trouble seeing what's going on. At night, humans in battle will be probably more challenged than orcs in the day, so I'm guessing humans will use a LOT of fire weapons to increase light on the field and coming from burning orcish formations. Smoke will obscure vision for orcs at night, but that doesn't hurt humans any more than it already is in the dark.
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In a medieval world it's possible to shed light in the dark but it's almost impossible to throw darkness in the day without magic.
I think the humans in your scenario have a big advantage: during the day they can seek and engage the orcs, while during the night they can use the light of large fires to hinder them and limit the attacking.
The orcs on the other hand can only rely on surprise attacks at night, but during the day they cannot have any way to block sunlight, other than hoping in storms and very cloudy days, maybe.
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You already have some good answers.
In addition / correction to @KerrAvon2055 good answer I'll add this:
Since the defender is dug in and the attacker chooses the moment humans will choose to attack at the break of dawn with the sun rising behind them.
It's a common tactic but would be even more effective against Orcs, effectively blinding them all. This would allow the humans to dismantle the defenses with little opposition.
Some of them may carry very polished metal convex shields to reflect sunlight if they can't attack with the sun behind them. In this case they will start from a position so that the sun will be in front of them, wait for it to be a bit over the horizon then attack while the shield bearers try to project the concentrated light on the enemy entrenchment. Any orc swept by the sunbeam would remain blind for several minutes. It's the same principle of Archimede's mirrors but the light would not need to be so concentrated, actually having a larger beam would be better.
edit: I see now OP's answer stating that these orcs are comparable to Tolkien's. Then they have significant disadvantage compared to humans and will unlikely win unless:
* they manage to set up an ambush in a dark place, like a deep forest
* manage to exploit a badly fortified position at night
In both cases they will need to exploit a fundamental mistake made by their opponent.
Orcs are at disadvantage because:
* are smaller and weaker than humans (only Uruk-hais were comparable to men in strength
* they can't move in daylight without becoming quickly exhausted. So they would not be able to march during the day to fight at night. Which means that in Summer they would have a much reduced mobility compared to humans. Humans are most likely to impose the field of battle and the time
Orcs in the books had to their advantage an overwhelming number of troops and, in The Return Of The king, the cover of Mount Doom ashes. But OP has not specified either for his world.
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What would cause/allow a planet with very high gravity to have tall, sharp mountains?
Mountain height is generally capped off by gravity, erosion, and the mountains composition. On a higher gravity world, mountains likely wouldn't be able to get very tall or jagged, but I love the idea of a planet having harsh, steep terrain AND gravity high enough to make travel even more hellish for nonnative explorers.
Ideally, I'd have the gravity be 1.5-3 times that of earth.
For visual appeal, I'd also prefer the rocks making up the mountains and crust to be primarily black or dark grey in color.
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**Make the plate tectonics that throw up the mountains super aggressive.**
[![mount fitz roy[1]](https://i.stack.imgur.com/B8G9l.jpg)
<https://en.wikipedia.org/wiki/Fitz_Roy#/media/File:Fitz_Roy_Chalten_Argentina_Todor_Bozhinov_2013.jpg>
The process that lifts mountains on earth can lift some crazy jagged mountains. Gravity has got nothing on plate movements. Sure gravity is going to whittle them away via "mass wastage". Have them come up faster than that.
Your planet has super active plates. That also means probable frequent earthquakes and possible rapid motion upward from time to time. There is nothing better for a party of adventurers clambering over jagged mountains than to get shook up by an earthquake. Which would also loosen any snow that might have accumulated up there...
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A low density of mountain composition i.e. in the planet crust.
Maybe this planet hasn't got a asteroid bombardment during their formation and high dense materials compose the core, and light ones are in the surface.
Could be a cold planet, with ice and other volatile compounds mixed well in the rocks. The rotation of planet is also kinda slow and the cold atmosphere has weak winds, thus a weak aeolian erosion.
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A magical calamity has wiped out an area about twice as big as Germany. The calamity also altered the climate in the region from one supporting forests and grasslands to a desert similar to the American southwest. Think badlands, not sand dunes. Aside from the climate changes, there are no lasting effects of the calamity; nothing comparable to nuclear fallout.
Assuming there was a small desert adjacent to the region from which desert life can spread, how long will it take that life to spread across the whole new desert?
[Answer]
**About 1 to 2 centuries.**
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You're talking about **Ecological Succession**.
<https://en.wikipedia.org/wiki/Ecological_succession>
and more specifically **Secondary Succession**...
<https://education.seattlepi.com/ecological-succession-desert-5078.html>
"... Desert ecosystems can be disturbed by fire, flash flood scouring or land clearing. After disturbance, succession is set back, but the soil has already been developed. Secondary succession in deserts is relatively quick compared to primary succession, but it takes much longer to establish a desert community than it does in less arid regions. For example, in the southwestern deserts of North America, it can take **76 years to establish perennial plant cover and 215** years for full ecosystem recovery. If the disturbance is great enough, secondary succession may produce an entirely different climax ecosystem."
also:
<http://shawcloud.yolasite.com/soil-and-succession-and-symbiotic-relationships.php>
and
<https://desertbcraft.weebly.com/succession.html>
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For wildlife to spread into the area, you need plants there first. Predators won't spread until prey starts living there. And prey uses plants for shelter from Predators and for food.
The diagram below shows the different mechanisms for seed dispersal -- wind, falling to the ground and germinating, falling to the ground and hitchhiking in animals' guts, or on fur or one clothing in the case of humans.
Wind dispersal is the farthest-reaching mechanism if there are winds present. Especially since your only viable plants verge on one side of a desolate zone.
The efficiency, and therefore the rate of dispersal is very complicated determined by the seed casing itself, wind speed, direction, gusting, probability of landing in a good spot, and not getting eaten before the plant reaches maturity and generates new seed.
You have a small advantage to accelerate the dispersal -- indirectly. The non-desert flora surrounding the desolate region will disperse seeds into the zone. These will attract birds and rodents, who will spread seeds in their scat and fur.
The topic of the mathematics of modeling seed dispersal is an ongoing topic for seedologists -- or whatever the discipline is called.
[](https://i.stack.imgur.com/lLaJE.png)
So unless you want to do a lot of very complicated probabilistic calculations, you can use a simple algebraic term and guess at an answer.
$$Rate = \chi \times d \frac{km | miles}{year|plant seeding cycle}$$
where $\chi$ is the probability a sufficient density of seeds will populate the adjacent area
and
where d is the average dispersal distance of seeds.
values for $\chi$ seem valid from 5% to 40% depending on species, weather, wind, the population of seed eaters, etc per seeding cycle.
values for d seem valid from 1 (1.6 km) mile to 10 miles (16 km)
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I want to write a science fantasy novel about humans evolving into five new species. The five races are: the Groses and Grosettes (they are my Ogres) (their name comes from the french word gros/grosse that means fat, big, large, overweight or obese) (I am a francophone from Quebec), the Dwarves, the Giants and Giantesses, the Skeletons (they are my Elves) and the Mundanes (they are the "standard" humans).
The Mundanes live everywhere, the Dwarves live beneath the ground like moles, the Skeletons are arboreal like spider-monkeys, the Giants and Giantesses live in freshwater like goldfish, and the Groses and Grosettes live in saltwater like whales.
The Groses and Grosettes have evolved from Austronesians (Polynesians, Micronesians, Filipinos, Indonesians, Malaysians, aboriginal people from Taiwan and aboriginal people from Madagascar). The Skeletons evolved from aboriginal people of South America. The Giants and Giantesses evolved from Central Asian and South Asian people. The Dwarves evolved from Europeans. The Mundanes come from all origins.
I want my Groses and Grosettes to be obligate carnivores like penguins (their favourite food is decapods) (decapods are lobsters, crabs and shrimps). I want my Dwarves to be facultative carnivores like dogs (their favourite food is insects) (insects are flies, moths, ants, bees and termites). I want my Giants and Giantesses to be facultative herbivores like oxen (their favourite food is plants of the Malvales order) (Malvales are cocoa, durians and mallows). I want my Skeletons to be obligate herbivores like sloth (their favourite food is plants of the Rosales order) (Rosales are apples, pears, roses, strawberries, cherries, almonds, elms and hemp). I want my Mundanes to be true omnivores.
I heard somewhere that humans cannot be obligate carnivores because of the lack of vitamin C synthesis. But I know four types of obligate carnivores that need to consume vitamin C: pikes, salmonids, swallows and tarsiers. I think a species that lack vitamin C synthesis could be an obligate herbivore if it eats fruits and not only seeds.
So, is it realistic for humans to evolve into such creatures?
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**Yes**
It's already started to happen already.
The Bajau population of Indonesia have lived on houseboats for the last 1000 years and have evolved genetically enlarged spleens which allows them to use oxygen more efficiently so they can stay underwater for longer.
See <https://www.telegraph.co.uk/science/2018/04/19/nomadic-divers-evolve-larger-spleens-stay-underwater-13-minutes/>
As time continues more and more changes will occur assuming the same evolutionary pressures.
The problem is these evolutionary traits will be lost if these people lose their lifestyle or breed with other groups. A larger spleen doesn't help you work in a factory.
Humans will evolve if they have the right environmental pressures but it's harder because our large brain allows tool use which bypasses the need for evolution to survive.
For it to happen you really need a more primitive society in an aquatic environment and a lot of time.
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## It's hard to make humans evolve
The idea of humans evolving into marine mammals is explored extensively in Kurt Vonnegut's [Galapagos](https://en.wikipedia.org/wiki/Gal%C3%A1pagos_(novel)) (1985). In his novel, a group of people are shipwrecked on a fictional island in the Pacific. Simultaneously, a disease renders all mainland humans infertile, leaving the stranded island population as the last vestige of the human race.
Over a million years and countless generations, they evolve into aquatic mammals because of the evolutionary pressures of island life.
What's important about Vonnegut's setup is that he uses his plot to achieve [reproductive isolation](https://en.wikipedia.org/wiki/Reproductive_isolation). With no mainland humans to rescue the protagonists or breed with them, his humans face consistent evolutionary pressures that eventually drive them to become aquatic. Plus, their genes aren't diluted by a global population, so evolutionary changes manifest faster.
While there are some advantages to humans diverging into different species (like accessing certain types of food) it doesn't make sense evolutionarily without isolating each population. Considering that early humans managed to populate every continent except Antarctica with rudimentary technology, you're gonna need some pretty strong physical barriers - or a cataclysmic, population-reducing event - to drive the divergent evolution you're looking for.
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**No, not realistic at all**
Humans use technology, and adapt to their environments by using that technology. Your marine based humans won't start growing fins because they'll have boats and scuba gear. Even if they don't have those things now, they will in a few tens or hundreds of generations, a time span far too short for any significant evolution. You might get some localized evolutionary adaptions, but once technology kicks in, it removes the stressing factor that leads to evolution (and likely, instead, creates its own evolutionary influence).
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There is some speculation that human evolution *already* went through an aquatic (or at least littoral) (waterside) phase; while the hypothesis is regarded as disproven (or even "junk science") in scientific circles, it has captured a bit of the collective imagination, and may have generated some discussion and fragments of suggestive evidence you'd find helpful.
Modern versions date to Alister Hardy in year 1960, but in particular, [Elaine Morgan](https://en.wikipedia.org/wiki/Elaine_Morgan)'s *The Descent of Woman* (1972) and *The Aquatic Ape* (1982), etc. developed a picture of an evolutionary chain driven by women foraging in the water versus men hunting on the savannah; adding a feminist (or at least female-centric) perspective to evolution was noteworthy.
[Wikipedia has an overview](https://en.wikipedia.org/wiki/Aquatic_ape_hypothesis); apparently [books are still being published](https://www.the-scientist.com/reading-frames/did-human-evolution-include-a-semi-aquatic-phase--67306) on it, and articles are still being written, e.g. [Why is it junk science?](https://www.the-scientist.com/reading-frames/did-human-evolution-include-a-semi-aquatic-phase--67306) vs [Why are biologists refusing to accept it?](https://theaquaticape.org/human-evolution/aat/)
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**How would a wild Mimic differ in behavior compared to a dungeon mimic? What are the strategies they may employ? What would they mimic without human influence?**
In D&D and other media Mimics are always seen as the treasure chest monster found in dungeons and caves. But biologically that should not be possible or at least extremely unlikely as nature has a hard time mimicking man-made objects. An adventurer is far more likely to get attacked by a tree or rock looking creature than a treasure chest (perhaps that's why they are taken by surprise). So it got me wondering on how a Mimic would get by without any human influence, perhaps due to living far from human civilization. My interest is especially set on the various behaviors they may exhibit, hunting strategies, survival tactics, communication etc...
Biologically Mimics are amorphous blobs with large gaping mouths. They are stationary ambush predators that camouflage to attract prey, catch them with their tongue and bite them to death. They mostly eat humans but can also settle for other monsters or unlucky wild animals. Based on their environment I assume they are cold blooded. They don't seem to have visible eyes so I assume they can see with their skin to some extent, which would mean that they don't have to peek while camouflaged. At least this knowledge applies to dungeon Mimics, their wild counterparts might be completely different. Since they would live in places without humans they might feed on any kind of animal they come across.
**A distinction to make is that wild Mimics don't live in dungeons and caves but rather out in the open in forests.**
[Answer]
### Physiology
Mimics are a highly adaptable, carnivorous variant of the "slime" class of monsters. While most slimes are simple scavengers or herbivores, Mimics have evolved a more efficient means of luring their prey by transforming into objects desired by their prey. Using a complex network of chromatophores and an amorphous, muscular layer with microscopic "locking" fibers that allow it to retain a given form without expending energy, a Mimic is capable of transforming into nearly any stationary shape, though they cannot accurately copy complex movement beyond wiggling or waving.
Unlike most slimes, which have at best a small ganglion for coordinating movement, Mimics possess a large, complex brain at the center of their mass. This allows them to learn from observation and experience, which is essential for their unique hunting strategy.
### Hunting
Mimics are quite intelligent, and are believed to possess a rudimentry *theory of mind*, which is applied heavily in their hunting strategy. When a Mimic sees an animal it wants to eat, it will stalk the intended prey, transforming into objects in its local environment to stay hidden. It will watch the prey and try to ascertain which kinds of objects they are attracted to, and will learn to copy these forms to attract their prey.
### Common Forms
The forms that a wild Mimic will usually adopt include rocks, dead animals, small shrubs, fallen fruits, and patches of land covered in grass, depending on what it is hunting. Usually a Mimic will transform a part of its body into the "lure" while camouflaging the rest as part of the landscape, allowing them to appear smaller than they actually are. Some Mimics have learned to turn a part of their body into a spider-like "lure" at the end of a stalk, which they will wave around to attract birds and insectivores, like the Spider-Tailed Viper.
As the forms they take are learned, rather than instinctive, the forms adopted by Mimics living in one environment will differ heavily from those living in different environments, even if the Mimics themselves are closely related.
### Parenting
Learning to mimic objects properly takes time and effort, during which the young Mimic is vulnerable. Because of this, Mimics possess a strong parental instinct. A young Mimic will instinctively try to copy objects in its local environment; parental Mimics will facilitate this learning process by surrounding their children with objects that they have learned are useful to copy.
### Mirror Learning
Mimics can recognize themselves in a mirror from an early age, and a parent Mimic will transform a part of its body into a mirrored surface so that the child can see what it is doing as it learns to use its transformative abilities. Mimics have also been known to treasure reflective objects, both for teaching their offspring and to refine their own mimicry skills. Access to a high-quality mirror greatly accelerates the Mimic's ability to master new forms - without one, the Mimic is forced to rely on extending an eyestalk away from their body in order to observe themselves, which can introduce inaccuracies in the process.
### Domestication
While it is theoretically possible that Mimics living among humans may learn to lure humans using forms like gold or treasure chests, this is a poor hunting strategy - Mimics that learn to hunt humans are often targeted for destruction, like most man-eating animals. In reality, most "treasure chest Mimics" are actually domesticated - they were *intentionally* trained to adopt that form to catch would-be thieves.
Due to their instinct to adopt nearby forms when young, it is quite easy to train a Mimic from an early age - the trainer simply places the objects to be copied in the young Mimic's vicinity, and rewards them with food when they adopt the form. The Mimic learns to associate the "treasure chest form" with "food" in the presence of humans and will subsequently adopt that form when a human approaches.
[Answer]
**Hollow logs / trees**
By mimicking hollow logs, animals seeking shelter hide in their mouth by mistake
**Fruiting trees**
By mimicking fruit trees the mimic can easily catch animals seeking food.
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Generally, they would look like boulders. After all, they *are* amorphous blobs of apathy, which is pretty much what a boulder is anyway.
As for hunting habits, they would probably position themselves in the shade, with their tops being essentially flat. This would make them look like a good resting spot, causing passing people/animals to stop there to rest. Their favorite food would probably be Boy Scouts, since they use just those kinds of spots as rest stops.
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If you were air dropped onto another planet, where multi-cellular non-plant life did not evolve, could you survive on what was only around you? The planet in question is a clone of earth, in almost every detail. Plants are almost the same as on earth, except for features evolved because of animals and insects.
[Answer]
TL;DR: yes, probably. But wind-blown-pollen-world is going to be bad news for hayfever sufferers.
*edit*
Given the absense of most fruits and berries and the total lack of things to hunt or fish, the challenge of surviving by gathering everything you need is going to be much harder than it would on Earth. It is already a challenge to survive as a hunter-gather on Earth if you're not familiar with the environment and techniques required to survive in it, and there will likely be many places in your world where you just can't get a balanced diet and you'll die in reasonably short order.
The rest of this answer, therefore, is about the *general* existence of stuff you can eat, and the implication that one *could* survive. The specific availability of enough food species in any given location is a bit too broad to be dealt with here, and whether a random person dropped in a random place could survive won't be considered (though you probably should).
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To start with, many major staple food sources such as corn, wheat, rice, soy and sorghum are either wind pollinated or self pollinated. Obviously, without a few thousand years of selective breeding you won't have many of the modern crops, but their forebears (or analogous species) should still exist. Greens like spinach and chard will also be available. Lots of nut trees are wind pollinated... hazelnuts, walnuts and pecans, and things that are *called* nuts but are actually seeds, like pine nuts. Pretty certain you'll get a lot of mushrooms, too. This list is very much not exhaustive, but even this short list will get you fibre, carbs and protein (and feedstocks for alcohol production, which is very important... hops are also wind pollinated, so you could probably rustle up some beer, with a bit of work).
Seaweeds will of course also be able to reproduce just fine and have lots of edible offerings, and less tasty but still nutritious things. What you won't get will be any fruits and berries that are intended to be consumed and spread by animals, obviously, and that takes away a big source of interesting flavours and nutritious things.
What is harder to predict is what the various biomes in which these plants grow today would look like on your alternate world, in the absense of grazers and browsers. The chances of them remaining perfect clones of earth is pretty slim (though to be honest the evolutionary history of such a world is deeply suspicious, and clearly the work of an intelligent species rather than chance) and you'd get a lot of new species arising and a lot of existing habitats would change drastically. Whether you'd be able to eat the new species or their seeds and nuts is anybody's guess, but no plants would be evolving toxins and irritants and spines and other things to discourage things from eating them, so you may find that a much wider variety of plants are edible in your new world, though that isn't quite the same as *nutritious*.
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The obvious cheat is to bring some animals with you to eat the things that you can't, and then eat the animals. This is a common approach on grasslands across the world and through history.
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You might actually find that you can eat more plants than on a world with fauna. Most poisonous plants are theorized to have evolved poison as a defense mechanism against animals trying to eat them. Without any fauna around, there would have been no evolutionary pressure for plants to become poisonous.
But on the other hand, you will have difficulties finding any plants with nutritious fruits. The reason why some plants cover their seeds in soft, sugary and flavored fibers is because they *want* their seeds to be eaten by animals which will then spread them over a larger area. Without animals, this procreation strategy won't work. But you can still try to eat any other plant parts. Seeds, bulbs or tubers are great candidates, because plants use them for long-term nutrition storage.
But then there is the question: Will you actually get all the different nutrients you need, including the large variety of vitamins and trace elements necessary for sustaining a human body? This, actually, might require some handwaving. Humans evolved to utilize the resources provided by their ecosystem, and as a result are dependent on a very large variety of them. So it is not very far-fetched that the local plants might be completely devoid of one or more vitamins or metals which are crucial for human health.
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There is one thing you need to worry about: [Vitamin B12](https://en.wikipedia.org/wiki/Vitamin_B12).
On earth, this vitamin is produced in the guts of virtually all animals, us included, by some bacteria. The trouble is, this happens later in the digestive tract than the part of the intestine where we can actually absorb the Vitamin. Some animals deal with this either by rumination (<https://en.wikipedia.org/wiki/Ruminant>), or by eating their feces one more time.
Animals typically have quite a significant store of B12 in their liver. That is why carnivores don't need to bother with rumination and such, they simply get their B12 from the stores of their prey's livers. Most humans live a carnivore lifestyle, so they fall squarely into this category. Some don't as they are vegetarians, and those need to supplement B12.
As I said, the store of B12 in the liver is usually quite significant, and can keep you happy for at least two years, or so. However, after some time of strict vegetarian diet, those stores are depleted, and then you start developing the [symptoms of B12 deficiency](https://en.wikipedia.org/wiki/Vitamin_B12_deficiency).
So, if your humans only need to survive a year or two before they are picked up from the planet, there's no fundamental problem. If they need to survive longer, you need to give them a source of B12.
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In my setting, magical civilizations have physical aversion to metals and moving metals have nasty distruptive effect to magic, so these civilizations development went completely different way from ours.
Eventually, after centuries of primitive protomagic, they discovered process to transform magic crystals(magic fuel, non-quark based matter) to magic cores, which could be endowed with spells/concepts(that still require magic crystals to run).
One of these are concepts of repelling or attracting something. This became a massive game changer, as it allowed to build them hovering ships, ships capable of flight up to hundreds of metres above water or ground (repelling solids and liquids). These ships are built similarly to normal ship (because they consume fuel to fly, they are usually in water for docking and can be sent by waterway to go cheap on fuel).
At first, they used side sails, sails to extend from sides of the ship, but later, they came up with idea of using air attraction core to propel the ship. My question is, how should such engine work? I myself came up with a rather simple but a crude design, but I feel that this design leaves a lot to be desired. I am not an engineer, and my few experiences are not even enough for me to call myself a dabbler.
**So my question is: How would an engine that would be designed with use of magic of attraction (or repulsion) work? And is this kind of engine even worth it?**
To set the technical restrictions: The cores require at least 0.25 second to turn on and off, so they can't use really short cycles of intake and expulsion. However, strength of their output can be controlled.
The attractor core as I imagined it works in a way where it pulls air particles (N2, O2, CO2) inwards, preventing the particles from escaping the zone, unless their velocity is too high. This in effect would creates a zone of certain volume in which air pressure stabilizes at different level(this in principle immitates planets holding their own atmosphere). The repellant core works on precisely opposite principle.
Attractor thus creates zone where air pressure increases as we approach the core. The best the attractor core can reach is for average density within volume of its effect to about 10 times density of regular atmosphere around it, the best the repellant core can do is 0.1 density of regular atmosphere around it. **We should assume that this effect can cover volume of ~0.5 cubic metre.**
*My own idea was to use attraction cores to attract air - increase pressure in a wooden chamber, then block intake, open the thruster, and turn the attractor core off, which pushes the air into the only possible route of escape - thruster. However, with such technical constraints, I feel that my idea might produce only laughable thrust.*
[Answer]
From what you've described I'm taking these effects to be a symmetrical, spherical volume around the crystal, and the density gradient to be continuous at all points (ie the density increases smoothly from 1 atmosphere at the boundary to some value (permissibly infinite) at the centre, with no sudden jumps). Otherwise you've created a force field for air, which I don't think is what you want.
Given those things, the force produced by these crystals is conservative, which means there is no *static* assembly of attractors and repulsors which can produce a net change in velocity of an air molecule. You have to cheat somehow by changing the configuration of the field in either space or in time. You've said that it's cumbersome to vary the crystal's strength in time, so let's consider spatial options.
The simplest engine, which uses only attractors, functions similarly to a water wheel. Take an airtight tube of radius $r$ open at both ends, and drag an attractor with effect radius $R = 2r$ down the *outside* of the tube, in a (loosely) sealed area; then lift the attractor at least a distance $r$ away from the tube before drawing it back solely in the sealed area to complete the cycle. The air inside the 'mechanism' sloshes around a lot, but the net airflow inside the tube is strictly in one direction. An alternating series of attractors and repulsors moving in one direction would drag pockets of high-pressure air with them. I think maximum efficiency would be achieved with a linear tube and crystals moving around on a caterpillar track, but it might be mechanically simpler to construct as a half-circular tube with the crystals fixed to a rotating wheel.
How much thrust might such a device produce? You've said the area of effect of a crystal is $\mathrm{ 0.5\ m^3}$, which is a radius of also about $\mathrm{ R = 0.5\ m}$. If you touch such an attractor to the outside of a tube of radius $r = \mathrm{0.25\ m}$, the volume contained within the intersection of the sphere and the cylinder is [given by](https://core.ac.uk/download/pdf/82412251.pdf) the spectacular formula \*:
$$ V = r^3 \left( \frac{2\pi}{3} + \frac{4}{9}(1 - 4\eta^2)K(2\eta) + \frac{16}{9}(2\eta^2 - 1)E(2\eta) \right)$$
$\eta = \frac{r}{R} = \frac{1}{2}$ in this case, which is fortunate because it means we don't need to worry about $K(2\eta)$ or $E(2\eta)$ (which are [Legendre's complete elliptic integrals](https://en.wikipedia.org/wiki/Elliptic_integral#Complete_elliptic_integral_of_the_first_kind) of the first and second kinds, respectively); the $K(2\eta)$ term disappears and $E(1) = 1$. We finally get:
$$ V = r^3 \left( \frac{2\pi}{3} - \frac{8}{9}E(1) \right) = \frac{6\pi-8}{9}r^3 \approx 1.2 r^3 = \mathrm{0.15\ m^3}$$
You only said that the *average* density inside the crystal effect area is increased tenfold, which means technically we should choose an expression for the density as a function of position and integrate over that volume, but I hope you'll forgive me if I baulk at that just take it to be a constant. The density of air is about $\mathrm{1.25\ kg\ m^{-3}}$, so each pass of the attractor crystal drags approximately $\mathrm{1.7\ kg}$ of air through the cylinder (over and above 'ambient').
This doesn't sound like a huge amount, and indeed it's not, but it would not be unreasonable for this machine (especially if set up in the wheel configuration) to move the crystals extremely quickly. From a quick google search it seems that for traditional spinning wheels rotation rates of wooden parts of tens to hundreds of revolutions per minute (ie $\mathrm{1\ -\ 10\ Hz}$) are reasonable. A 5m-diameter wheel would have space for 15 attractors around its circumference, and rotating at $\mathrm{3\ Hz}$ it would shift around $\mathrm{76\ kg}$ of air per second at a speed of $\mathrm{47\ m\ s^{-1}}$ for a not-unrespectable thrust of $\mathrm{3.6\ kN}$ (in the same ballpark as the $\mathrm{4.5\ kN}$ from the [first jet engine](https://en.wikipedia.org/wiki/Heinkel_HeS_3)). You couldn't achieve heavier-than-air flight with such an engine, but to move a lighter-than-air vessel kept aloft by magic? Sure.
\* Case II.C (equation 9), setting $\eta = \frac{1}{2}$ and then multiplying by $R^3$ at the end.
[Answer]
Well, this makes maglev style trains very easy.
For propulsion, have an open tube with a number of these "repulsion engines" (REs) inside it angled toward one end. That would cause air to be pushed out the "back" end and sucked in the front end. You now have jet propulsion. If you turn on of off some of the REs or can increase of decrease the repulsion effect, you can throttle the jet.
This tube would work in air and water.
You could also make a turbo prop out of this but I wouldn't unless they've had this tech for a very long time.
Note that if the RE is powerful enough, it would make a very good machine gun too.
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A jet engine has four components: the intake, the compressor, the combustion chamber, and the turbine. Your magic attraction and repulsion cores are capable of reproducing the first two stages of the engine: sucking air into the engine, and then compressing it to increase its pressure while decreasing its volume.
If they can make magical heating elements, they could reproduce the effects of the ignition chamber, assuming that they don’t want to just use mundane fuel oils and a crystal-lined combustion chamber to do the job.
Then comes the turbine, which turns a portion of the engine’s thrust output into the rotational power needed to run the engine; strictly speaking, your magic engine wouldn’t need this since it’d be entirely solid-state, without rotating components, though maybe if it’s possible to generate magical energy by rotating a wheel you might be able to produce something analogous by building some sort of wooden turbine.
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An internal combustion engines works on the principle that the combustion gases, expanding into the cylinder, put in motion the cinematic chain transforming the alternate motion into rotation.
You can use a similar setup but, instead of using a cylinder where you burn some fuel, you just use alternated attraction/repulsion to swing the piston back and forth, and then convert that motion into a rotation.
Not having to deal with high temperatures you can avoid using metals.
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## Rockets
Let's look at how rockets work:
Rocket engines work by action and reaction and push rockets forward simply by expelling their exhaust in the opposite direction at high speed. (from wikipedia)
This is almost identical to how your magic system operates. It would likely also be the first type of travel they discovered, because the theory behind it is simple. Put something on wheels, and expel particles as fast as you can in the opposite direction.
For propulsion force = mass \* acceleration. So to increase speeds you need to either increase the mass of what your are repulsing, or the speed you are repulsing it at. Note, the heavier you get the more force is required to move you.
Major advancements to this field would be using things like nozzles to increase the repulsion velocity (and thus thrust generated.) It is also likely while some efficiency minded engines would use air and would operate like real world hovercraft, anything built for short bursts of speed would use heavier fuels.
So in answer to your initial question, just increase the speed at which your engines repulse the condensed air until you have the desired thrust.
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>
> it works in a way where it pulls air particles (N2, O2, CO2) inwards, preventing the particles from escaping the zone, unless their velocity is too high
>
>
>
You thought of using moving parts to work around the fact that the effect is omnidirectional, I assume. But I think you can do even better.
# Stato-magic-reactor
Let's have a nitrogen-attracting core. it will "pull N2 inward... unless their velocity is too high". So we build a long wooden tube, with two cores, one repelling, one attracting:
```
====================================== /
---> A R -->
====================================== \
```
The repulsor core will expel air from the tube, creating a low pressure area; the attractor core will be unable to attract much air from the tube because it will soon exhaust its content.
Now, air is attracted from the left end of the tube, at the very limit of the attractor effect, and pulled inwards, acquiring speed. Due to conservation of energy, the air will be able to move as far to the right of A as it fell in from the left of A; this must place it inside the effect area of R with enough speed to reach and overshoot R (therefore, the power of R must be less of that of A).
The net effect will be a transformation of magical potential energy into air kinetic energy; wind will start blowing through the pipe.
Close the left inlet to stop the flow, or attach the pipe to a vessel to provide thrust.
I was trying to explain why this cannot work in the real world (which was intuitive enough) and why, and what *would* be needed to make it work. @Stephen has put his finger on a far sharper and simpler explanation than mine: the magic field must be nonconservative, but more than that, it has to break symmetry. The simplest way to achieve this is to make the field **non-additive** - for example, in any given point of space, the total effect is **not** given by the sum of the effects of magic cores within range, but by the whole effect of the locally stronger field alone, much like political frontiers work (when you're approaching a State limit, you're completely subject to the laws of the State you're in; as soon as you step through, you're again completely subject to the laws of the State you just entered).
Another way of making this work is by supposing that metal can make the force nonconservatively disappear (aka *magic*); then placing a metal ring between A and R, close enough to A but not enough to interfere with its powers, would allow air to escape towards R with most of its kinetic energy intact, moving towards R on inertia.
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I personally prefer a more simple method I shall call the **Anti Gravity Engine**
While its pretty hand wavy, it gives you a lot of flexibility in terms of use and has little impact when you think about the traditional movement of air particles and airflow when flying and generating lift
The issue with a rocket style engine is the constant stream of high speed particles you need to blast out. When your ships lift off, they are going to be expelling a ton of air particles into what ever is below them and this can be very destructive. If you ever watch a helicopter land you will notice the huge amounts of wind and noise generated. A commercial airliner can blow away cars and buses. A rocket basically makes the surrounding area uninhabitable...
A **Anti Gravity Engine** doesn't have this issues. It interacts directly with gravity, which means your surrounding areas remain nice and calm. No need for earmuffs, protected landing zones and the best feature? All your ships will be able to hover in place without blowing out everyone's eardrums. (You can also have ships fly close to each other. Directly above and below, in front and behind without burning them to a crisp with your high energy exhaust fumes).
The second advantage is attraction. Not only can you repel gravity, you can attract it. This means that your airships can theoretically double up as submarines as well. This can even be applied to other ships, allowing you to form a natural train of airships and submarines with an extra bit a magical research.
The third advantage... your ships can be any shape you want. A traditional flying vehicle is limited in design, because it needs to be able to move and generate lift. The **Anti Gravity Engine** produces a steady supply of lift without requiring wind or speed. A steady supply of mana is all you need, which means you can actually have and use sails to move horizontally in the air. You can have monstrous floating cities and you could even run a space program out of your rickety dinghy assuming your **Anti Gravity Engine** was powerful enough and had enough supplies to get you that high.
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There's an even better way of using these kinds of magical attractions / repelling engines. And that is the *legendary* Zero Mass Drive. Theoretically, using negative matter, you could have a drive which has a net mass of zero, and propel itself. Hence the name, Zero Mass Drive (technically, it's called a [Reactionless Drive](http://www.projectrho.com/public_html/rocket/reactionlessdrive.php), whatever, Zero Mass Drive is a cooler name).
Now, you specify that the crystals are non-quark based matter, but you haven't done the same for cores, which means that they *are* quark-based - and thus real matter - and thus you can build cores that can attract and repel the material that cores are made of. So what you do is simple. You build a core which attracts cores, and a core which repels core. Then you line up the cores. The first core repels, the second attracts. And now is when the drive takes effect. The second is attracted to the first, and the first is repelled, sending both cores forward along the line. Then, all you do is mount the cores (when they aren't on, of course) to your ship, then simply activate them.
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I want a character to get sucked into what she thinks is an FTL-wormhole-gate. While it turns out that the gate is indeed a traversable wormhole, it does not allow for FTL travel. The gate transports her at a velocity of ca. 0.9999999999 c over a distance of 570 million lightyears (outside of the Laniakea Supercluster). Due to relativistic time dilation, she only experiences a few seconds of subjective time and believes to have discovered a way to transverse the universe faster than light. (This is completely unrelated to the issue at hand and should not be included in any answers. It is just to give some context.)
**How could she realistically figure out how much time has passed during her trip? My idea was that she measures the temperature of the cosmic microwave background, learns that it is colder than it is supposed to be and calculates that she, in fact, has traveled 570 million years in time as well.**
Is this a realistic way of figuring out that she has traveled into the future? Are there any easier/more realistic ways? She is driving in a distant systems Kuiper-Belt on a small scouting shuttle with a lot of instruments but almost no delta-vee left.
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Answering only the first question: **Yes**, it is a realistic way.
Precision may be questionable however (so, she will figure out she is a few hundred million years ahead in time, but won't be sure whether it's 500M or 600M, if we presume present-day understanding of CMB, universe expansion and all the relevant stuff, and [Planck](https://en.wikipedia.org/wiki/Planck_(spacecraft))-level precision of measurement. With future tech, she certainly can have precision under a million years.
So, you want to measure CMB. It would be useless to observe its patterns, as you won't know what those are in your new position, and those [change on the scale of 100 thousand years anyway](https://astronomy.stackexchange.com/questions/8763/does-the-cosmic-microwave-background-change-over-time). So the only thing you can use is CMB temperature. Fortunately for you, we know how that behaves.
$$
T\_{CMB}(t)=\frac{T\_{CMB}(0)}{a(t)},
$$
where $T\_{CMB}(0)$ is the present-day temperature,
$T\_{CMB}(t)$ is temperature you want to measure, and $a(t)$ is the scale factor (defined to be 1 at the present day).
To properly describe how $a$ changes over time you would need to integrate [Friedmann equation](https://en.wikipedia.org/wiki/Friedmann_equations). Which is something your hero would do, but I'm too lazy for that. Fortunately, there is a good enough proportionality: in the current dark-energy-dominated era
$$
a(t) \propto exp(Ht),
$$
where $H$ is the Hubble constant. Plugging in $H=70km\*s^{-1}\*Mpc^{-1}$ and $t=570My$, we get
$$
a(t) \approx 1.042
$$
That means, as the first approximation, CMB temperature would drop by about 4%, or 0.11K. That's certainly a noticeable and measurable change even with present-day (if state of the art) detectors.
The problem with precision in our day arises from the uncertainty about Hubble constant. For example, we have two values ($67.66 m\*s^{-1}\*Mpc^{-1}$ and $74.03 m\*s^{-1}\*Mpc^{-1}$) which are supposed to have precision of less than 2%, but you can see that they differ way more. So far this discrepancy wasn't resolved. There is also the issue of Hubble constant not being really *constant*. We know it changes over time, we know it changes not by much on smaller time scale, but we don't really know how it would change. All this factored in, you can have precision of about $\pm100My$ or so with current data. On the other hand, it is certainly not a stretch to say that even in 10 years, this would be improved to $\pm10My$, and with whatever future technology and science you have, precision can be plausibly at least a couple orders better.
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You have a few conceptual problems here.
If you have to cover 570 million light years at 0.9999999999c, time dilation will habe a factor of 0.00014141979198682754. You can use [this calculator](http://www.emc2-explained.info/Dilation-Calc/#.XXgWwZDQ-yU) to find out, just multiply your input by 100 because the calculator uses percentages.
0.00014 of 570,000,000 years is about 79,800 years. That's 12 orders of magnitude more time than what you want.
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A wormhole that long will have its mouths existing in different eras (as seen from Earth) due to relativity and them accelerating at different speeds relative to us. You could just have the gate be a wormhole [of medium to small exotic region](https://worldbuilding.stackexchange.com/a/139109/21222) and stop worrying about speeds.
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Once at the destination, check the position of [the Large Magellanic Cloud](https://ned.ipac.caltech.edu/level5/March09/vanderMarel/vanderMarel4.html). It's orbital period around the Milky Way is about 1.6 billion years, so it will have completed about ⅓ of its orbit. This will stand out glaringly in a galactic map.
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In the moment before her shuttle entered the gateway, its sensors recorded light coming from the other end and created a snapshot of star positions. The light captured in that snapshot started its journey through the gate 570 million years prior to the moment she entered the gateway.
Comparing that snapshot to sensor reading from the moment she emerged from the gateway on the other side, she would be able to see that things had changed dramatically while she was travelling. In fact, more than a billion years of celestial movement would be evident from that comparison.
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Here is a link to a somewhat similar question:
[How would an astronaut conclude he's on Earth, but 600 million years in the future?](https://worldbuilding.stackexchange.com/questions/83817/how-would-an-astronaut-conclude-hes-on-earth-but-600-million-years-in-the-futu/83879#83879)[1](https://worldbuilding.stackexchange.com/questions/83817/how-would-an-astronaut-conclude-hes-on-earth-but-600-million-years-in-the-futu/83879#83879)
And you may note that my answer includes another method of telling that they have reached a distant future and the universe is noticibly older.
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**Star Position**
In that time the stellar map would had changed noticeably. The board computer wouldn't recognize his position and a estimate of time passed could be obtained comparing your map and the actual position of diferent constellations at the point you emerged from the wormhole.
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If she's 570 million LY from home, she has bigger immediate problems than what time it is.
Like where she is, and how to get back.
Whatever instruments she has that will allow her to plot location, her biggest immediate problem, will also indicate that time dilation effect. But having been sucked through a wormhole, working out the date is the least of your worries. That will be noticed only if she has instruments capable of locating herself and if she has such instruments, the shifting locations of various large bodies relative to each other will indicate the temporal effects of her journey.
Ultimately however, her first thoughts will be "where am I" followed by "how do I get home", and not "have I missed my date". Discovering she's missed dinner is going to be fallout from finding out where she is.
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Note: size here denotes the physical dimension(s) taken up by the creature in a natural, idling posture
One of the many fantasy tropes that make me want to Fahrenheit 451 contemporary fantasy literature is of course:
Literal power scaling (i.e: the bigger, the more powerful)
This has led to dragons the size of Metal Gear EXCELSUS and other travesties against common sense. That begs the question, **just how big should a functional dragon be?**
To answer that, we first have to define what functions do dragons have in my world:
* They have the resolve of a JoJo protagonist and use it
* They live in a world where guns exist and still pose a threat, even to their laughably strong, graphene-reinforced scales
* Their godstats *(stats that are the most advantageous for their lifestyle/strategy)* are **agility** and perception
* They're at the top of the food chain *(even if elephants are included)*
* They can attack with claws (not that effective), chompy jaws (effective), and spades at the end of their tails
* They can fly
Since matters are more complicated, and there's no definitive answer, it'd be for the beter if we defined an interval in which the criteria are met. **What's the best size-category for a dragon?**
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**Harpy eagle size.**
[](https://i.stack.imgur.com/F6Bsq.jpg)
>
> Harpy Eagles are one of the largest and most powerful of all types of
> eagles. These birds of prey can grow up to 42 inches long, with their
> wingspan reaching a record 7.5 feet. Harpy Eagles weigh up to 20
> pounds, with females being up to twice as big as their mates.
> <https://www.boredpanda.com/massive-bird-harpy-eagle/>
>
>
>
This sidesteps giant flyer kerfuffle. These things are the right size to fly.
I really like the spade tail. These dragons would attack like peregrine falcons with a steep dive. At the end of the dive they pull up and the tail continues, striking the prey. This way the dragon does not have to withstand the shock of its impact with its entire body like a falcon does (and gets away with it because it is little). The spade tail is fine with the shock.
An antelope hit in the head with a 3 kg mass going 90 kph is toast. A hit anywhere else will disable it and the dragon can circle while it dies. Claws and jaws are for intraspecific combat and to ward off terrestrial mammalian scavengers; these outmass the dragon and might challenge it for its kill on the ground. Also sometimes the dragons eat so much they don't want to fly right away but they don't want to themselves become easy prey.
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Truly, a lifestyle like this would be like shooting fish in a barrel. You would not need to be intelligent to kill an antelope or other large grassland grazer this way every few days. Intelligence would have to arise from competition with others of its own kind. And this (here is an answer to a frequently asked WB question!) is why dragons want gold. The ability to garner gold is the mark of a good mate, and you need to be smart to find, accumulate and keep gold.
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I have to make a few assumptions about your Dragons. I am going to assume a western style, 6 limbed, flying animal here. I am also going to assume a pretty high level of intelligence. This is important for a beast this size to achieve Apex Predator status.
Let's start with size. The Dragon is not going to be really big. It would probably be the same general size of a coyote. It can't be too big, because it will need to be able to fly. We have seen in the fossil record some flyers that were about that large. If the body is much larger, the wingspan has to get even larger. I'm not an expert, but I think if you double the body mass, you have to square the wing size, so going much larger becomes impractical depending on environment. I'm thinking a forest and mountain dweller.
As for Claws and teeth, I think you need claws that are more efficient for ripping. Like a Deinonychus. These claws will be dual purpose for clinging to trees and rock faces as well as disemboweling prey. Teeth will obviously be for ripping. The spade like tail could also be prehensile.
Here is where we come to the most important weapon to make it an apex predator. It's brain. Give it Jurassic Park level raptor intelligence. It will not have the mass to take much larger prey with main strength, but even a Bison will go down if ambushed and hamstrung. Even solitary dragons could do that. make them pack hunters and you would have a very scary critter there.
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Do you want your dragons to predate on elephants? Note Lions are top of the food chain in modern day africa, yet in packs an elephant is still a risky proposition.
How big **could** a dragon be? Well historically Pterosaurs are the largest flying animal to have evolved on earth. Estimates place their wing spans at 11m and weights between 200-250kg. [Quetzalcoatlus](https://en.wikipedia.org/wiki/Quetzalcoatlus)
A point about flying animals on earth though, they are light. Pterosaurs and birds, though very distantly related, convergently evolved toothless beaks, hollow bones and lightweight coverings, hair and feathers respectively. Scale armour, even graphene reinforced, is going to erode your dragons capacity for flight. If it's still able to get airborne with armour, it's not going to be agile, nor will it fly for long as the energy cost of staying aloft will increase with every bit of mass you add.
As noted [here](https://worldbuilding.stackexchange.com/questions/15156/evolving-another-pair-of-limbs) additional limb growth hasn't occurred in evolutionary history on our earth, so a 6 limbed flying reptile is unlikely based on earth biology. It's also an additional mass with little advantage. Even tool use doesn't give a reasonable reason for additional limbs as Ravens have demonstrated tool use.
If dragons are intelligent and agile in the air, they could still be very difficult to kill with gunfire, depending on the technology level of the firearms in your world. Bullets bleed speed rapidly as they gain altitude, and they need speed to inflict damage. I'm thinking more low muzzle velocity weapons than the modern 50 cal. Would musket level firearm technology work in your setting? Muskets would also have the disadvantage of their terrible accuracy at range, making both hitting a dragon, then killing it very unlikely.
I'm thinking the baddest 'dragon' like thing incorporating your brief that's realistically possible is a Quetzalcoatlus / giraffe sized reptilian, two legs, two wings with a long hardened spade-tipped tail. As Willk proposed, a diving attack with that tail on pretty much anything smaller than an elephant is likely to kill it. With exceptional vision, they could potentially harass or hunt humans armed with single shot firearms, especially at night.
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Let’s go back to dragon evolution. Most likely dragons evolved from lizards. Probably they started climbing trees, evolved to be able to glide, and then gained the capability of flight. So in that time, they probably didn’t grow much, in fact it’s possible that they shrank to have a larger wingspan to body ratio. Perhaps they hunt other flying creatures such as bats or flying snakes. If you want to go with the whole hunt with they’re tail, then most likely they have evolved a special harpoon at the end of the tail, and with dives from high altitude may be able to hunt and kill animals nearly twice their size. So maybe about the size of a Komodo dragon, possibly with a poisonous bite and with a deadly stinging tail.
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...That is the question.
In my [previous question](https://worldbuilding.stackexchange.com/questions/154298/how-powerful-a-starship-coilgun-can-we-make), I asked about coilguns, how powerful we could make them and their plausibility. In that thread, and the discussion I had with Starfish Prime afterwards, I came to the conclusion that even the level of sci-fi technology I was aiming for, which is pretty small-scale compared to most other sci-fi settings, is beyond what we know can be accomplished.
That's not to say that we *definitely* can't create short-barreled coilguns with muzzle velocities in the dozens of kilometers per second, or fusion rockets with both high thrust and high efficiency, but we don't know for sure that they are even possible. It may be that there's an upper limit to technological progression, and that making starships that do what *I* want them to do just isn't possible, and therefore isn't realistic. If such an upper limit exists, it is all but certain that Star Trek is *well* beyond it.
With this in mind, is there really any point to going into great detail about how the universe works, and trying to make it as realistic as possible, when I know personally that it probably isn't possible? If I'm going to shrug my shoulders and go ahead and give my ships engines that I know would realistically melt within ten seconds, should I even bother to explain what those engines are and how they work? Or should I handwave and be nebulous?
I'm sort of leaning towards keeping the technology level *theoretically* possible, if you had absurdly ridiculous efficiency, but just keep it in the background without going into any detail about it. That way, if someone who likes poking at sci-fi realism - like me - comes along, they'll take a look at the numbers and go either 'that could work' or 'that's unrealistic' rather than 'that's completely absurd'.
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This very much depends on the sort of story you want to write and whether the technology itself is effectively a character in that story.
* Star Wars. It's entirely fantasy, it has wizards and magic swords, for all practical purposes they might as well be riding horses or flying carpets as in spaceships. Everything runs on handwavium and technology is entirely driven by the needs of the story.
* Star Trek. A space soap. Space is a set allowing them to meet a new race every week rather than having to deal with only the immediately available characters. The technology is still handwavium but it's more of a character by virtue of its tendency to fail. Certain aspects of the technology are occasionally a limiting factor of the story.
* Mars trilogy (Kim Stanley Robinson). The technology is a hard limit on the things they're able to do and all actions of the technology must be justified as possible. Technobabble is hard limited by actual physics or accepted tropes (space elevators).
So as you can see, it's about what you want to do. If for example you want to write a "space road trip" you can do it Star Trek style where it's all about who you meet at significant points along the way, or you can do it hard scifi style where it's about the interactions between the crew in their stl ship for year after year.
Remember though, normal people almost never talk about how things work. Consider the mobile phone, we might complain about lack of signal, we sometimes talk about the need for more masts or capacity, but actually we technobabble about 5G and GPS which out of context are entirely meaningless terms, and never talk about how the thing actually works, even when it doesn't.
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**Write what you know**.
You are conflicted about your desire for certain SF tech and your inability to explain them. Clearly that interests you. You can get good traction from that for your story!
Your engineering characters have the same concerns and are conflicted in the same way. You can have one or more scenes where they walk thru the tech.
I picture Oz the grizzled engineer laying out why the thrusters he is currently maintaining were held to be theoretically impossible when he was in school. One of his classmates got expelled for pranking the professor who humiliated him for his theories about more powerful thrusters. Of course that classmate went on to build the thruster that carries his name, and he even named the flagship of his company after that professor. Oz is still not sure why the professor was not right; it seems like the thing should melt. He is glad that so far it has not.
Scenes like this will give readers a basis in fact (about coilguns etc), acknowledge that your SF tech is edgy, and also let them learn some about your characters.
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**Circular Coilgun**
Why not make the coilgun circular like a collider and keep circulating low mass projectiles until they reach high speed and then release them. It works for atom smashers so should work in principle. The limiting factors is the strength of the magnets and size of the ring. The bigger both are, the faster you can go.
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[Question]
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Background, with potential spoilers:
In the Netflix show *Stranger Things*...
>
> ...there is an otherworldly creature known as the Mindflayer, which can telepathically control creatures in our world as long as the portal to its world is open. Once it has a creature from our world under control, one of the things it can do is "melt" that creature into more flesh to add to its preferred monstrous avatar.
>
>
>
If we skip the psychic stuff, there's still a pretty interesting creature there. To qualify as a Mindflayer monster, an organism should
1. Have a reproductive / feeding stage in which it acts like a non-contagious infection spread by physical contact with an adult monster (and possibly other ways). Once a victim is infected, the organism alters its host's behavior to seek out an adult monster and increase the chances of other hosts being infected. Eventually, the host is killed and its body digested to convert into monster flesh.
2. Have an adult stage with limited shapeshifting abilities. Specifically,
* any small piece of monster flesh should be capable of moving around on its own for some amount of time and seeking out other flesh-blobs with which to merge; this need not be indefinite, but should be long enough to be useful.
* monsters should be able to divide into smaller pieces to squeeze through grates, squish under doors, etc., and rebuild themselves on the other side, while maintaining at least enough memory to continue with whatever goal they have in mind for doing the self-squishing (high intelligence not required).
* given sufficient mass, monsters should be able to assume at least one complex ambulatory form, with legs and a body held up off the ground.
Ability to shapeshift into any additional forms (besides blob, walker, and pieces just cut off of a walker) is not required.
So, how could such a creature work, and how could it evolve?
A list of all Anatomically Correct questions can be found here: [Anatomically Correct series](https://worldbuilding.meta.stackexchange.com/questions/2797/anatomically-correct-series/2798#2798).
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**Your Mindflayer is a religious slime mold.**
[](https://i.stack.imgur.com/4XBy5.png)
<http://bioweb.uwlax.edu/bio203/2010/renner_brad/reproduction.htm>
Individuals of the prey species, like individuals cells of the slime mold, have the power to go about their business as individual single cells; slime molds have swimming cells and amoeboid cells as depicted. Your individuals can have one mode or different modes as you see fit. Individuals can be persuaded by various means to join the monster just as individual slime mold cells join a feeding plasmodium: a large flowing blob of merged individuals. The slime mold plasmodium is capable of dry land movement that the single cells cannot do, and capable of reproduction. Your Mindflayer has other emergent abilities not possessed by its constituent organisms.
Cool stuff: slime molds can learn by experience, and if an unlearned plasmodium merges with a learned one, the whole thing becomes learned.
<https://www.quantamagazine.org/slime-molds-remember-but-do-they-learn-20180709/>
>
> But Dussutour’s work suggests that the slime molds can sometimes pick
> up these behaviors through a form of communication, not just through
> experience. In a follow-up study, her team showed that “naïve,”
> non-habituated slime molds can directly acquire a learned behavior
> from habituated ones via cell fusion.
>
>
>
The religious aspect has to do with the persuasion. Also consider that like minded individuals (humans in a group, or a pack or flock) acquire abilities in the group that would not be possible for the individual. An individual might be coerced or tricked - or might be persuaded to join the group because of the promise of the abilities group membership makes possible.
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Your Mind Flayer isn't a single creature. Its a hive mind of small insects which branches off from ants.
There are two types. A Worker and a Queen. A Worker is born with two pre programmed objectives. Find Food, Bring it to the hive. Unfortunately, due to their size, they can't actually hunt or gather anything worthwhile. Instead they will attempt to access any creatures brain and release a chemical which gives the target a desire to go to the hive. Once the worker has brought food back to the hive, the rest of the workers will work together to break it down and process it. Feeding the meat to newly born workers. The worker who brought the food then joins the Hive.
The instructions and locations are pre programmed into the workers while they are still eggs and they are released into the environment to hopefully find their way back. If the Hive moves before the worker ants get back, they will be lost for ever as the Hive location is pre programmed into their minds.
A Queen sends out instructions to the hive. Due to the size and complexity of the hive, there are multiple queens to work in a distributed network to control and manage all the workers. This means groups of workers can be broken off from the main hive body and have roughly autonomous control as long as they have a queen in their midst giving them commands.
The queens command the hive to move using a form that has legs. This helps provide the queens protection from attackers on the ground as they are lifted far above it. It carries over from their early evolution days where they would often be attacked while travelling in clumps on the ground.
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If a person is sent out of their hermetically sealed community and in the process becomes immune to a deadly disease. When the person returns will the immunity make them a carrier and infect/kill all of the non-immune citizens?
How would they quarantine and deal with that possibility?
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The scenario may be possible, there is a thing called an [Asymptomatic Carrier](https://en.wikipedia.org/wiki/Asymptomatic_carrier), the most famous being [Typhoid Mary](https://en.wikipedia.org/wiki/Mary_Mallon), these people have a disease that doesn't effect them but they can still pass it on to others. As I understand it any disease, whether viral or bacterial, can have asymptomatic carriers, I know people can be asymptomatic carriers of the mumps virus as well as typhus bacteria.
Quarantine measures in these cases are tricky, no-one, even the carrier knows that they're sick until *after* the people around them start dropping, and it can be very hard to tie the disease to a specific source, delaying quarantine implementation further. In the case of Typhoid Mary they eventually had to jail her because they couldn't convince her that she was making people she cooked for ill. Depending on the [latency period](https://en.wikipedia.org/wiki/Incubation_period), how long it takes between host infection and the first symptoms of the disease, [virulence](https://en.wikipedia.org/wiki/Virulence), the speed and efficiency with which the disease spreads and it's [lethality](https://en.wikipedia.org/wiki/Lethality) by the time they know that they *need* a quarantine they could all be dying.
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I want to start by thanking everybody in this community as your posts have been instrumental in helping me to build my world. All I am asking for is a final review of the maps that I have created thus far and any details that should be changed to make the maps more realistic. Thank you in advance.
Some things to note:
1. Everything except for the polar ice caps is included in the maps.
2. This world has roughly the same surface area as Earth.
3. This world has a slightly higher water content than Earth, which I hope is enough to account for the increased prevalence of forests.
4. The world is flat but the problems associated with this are remedied through the power of the gods ie. the god of sun pulls the sun across the sky and moves its path north and south to create the seasons, the gods of wind do their part to maintain earth like weather patterns, and the god of the sea is responsible for currents.
[](https://i.stack.imgur.com/q0eeD.png)
[](https://i.stack.imgur.com/A1QKp.png)
[](https://i.stack.imgur.com/5I2rx.png)
[](https://i.stack.imgur.com/liP3M.png)
[](https://i.stack.imgur.com/kHs6j.png)
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Looks fairly good. Took me a second to realise why your ocean currents were running along the map edges and not crossing to the other side.
Areas marked 1 and 2 Depending how your oceans connect in the West and East, there are some issues.
If they act like typical spherical planet oceans *through* the magical firmanent, then they need to cross the map boundaries.
If they hit the magical firmanent boundary, then there are some ripple effects. The sea god could create forces to negate this rebound affect.
The north and south areas will need some way to connect.
Warm water pushing outwards on the surface and colder water encroaching towards the equator in the deeper currents. This will allow for proper interconnected ocean dynamics and some related weather effects. Check out [Teleconnection](https://en.m.wikipedia.org/wiki/Teleconnection).
I also believe your eastern mountainous islands will be alot greener and wetter than frozen tundra/taiga. I know it's a cold current to the west of the islands and its in the high latitudes but the moisture from the oceans could negate alot of the dry cold weather effects, along a thin strip of land. (Especially if there is warm water spreading upwards along your Eastern map boundary). At a push it could be similar to [Argentina climate zones](https://en.m.wikipedia.org/wiki/Climate_of_Argentina), but your islands look a lot narrower and remind me more of [New Zealand](https://www.sciencelearn.org.nz/images/774-new-zealand-surface-currents), which is surrounded by a warmer current so it doesn't quite match.
Area marked 3. This will be a large warmish collection of seas. The cold dry wind blowing south from your mountains will hit the warm wet air over the water and create large thunderstorms/snowstorms. It should also create a greener wetter climate area downwind, not the dry desert sliver you have to the southwest of the northern mountain range.
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The maps look good! Two main things I would change though. The size of the swamps, and the different biomes on either side of most mountains. Usually, (for tall peaked mountains) the moisture levels on one side would be vastly different from the moisture levels on the other side. Which you did sometimes, but not always.
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Nice work. Only comment I have is regarding your tectonic map.
## Plates
On a world with similar tectonic activity that we see on Earth, the edges of tectonic plates often break apart or merge leading to smaller plates in addition to the larger ones. I would recommend adding some of these smaller plates at the collision points of continental plates containing proximal continental masses.
[](https://i.stack.imgur.com/0kFer.jpg)
## Mountains
Using the same map, consider moving your mountain distribution to be centered on these collision points. The vast majority of large mountain ranges appear on these plate boundaries where as yours, on the contrary, seem fairly evenly distributed.
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Nice work üëç
The last illustration of Coriolis effect need to be tweaked because it only works on round world.
Unless you flip one of them and make the arrows combine in the equator to form a giant constant cyclone üòÅ
Good luck
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One of my mermaids is on land in the daytime, and I'm just wondering what the sudden existence of sunlight and Florida heat might feel like for her, since she's from the mesopelagic zone and is absolutely not used to anywhere near that level of light and warmth.
Edit: To clarify, my merfolk can develop legs in order to walk on land, and have lungs that are capable of breathing air as well as gills.
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Since you have given us only "the mesopelagic zone" to go on as far as what your mermaid physiology, we will have to make the following assumptions:
1. The mermaid probably has large sensitive eyes in order to see in the twilight and bioluminescent environment.
2. The mermaid is not a mammal. (no seashells, sorry)
3. The mermaid is cold blooded.
4. The mermaid has gills not lungs. (she probably won't be talking)
With these assumptions in place, the answer to your questions are:
1. The light in the daytime will blind her. Though she might be able to cope if it is overcast.
2. The heat will be 20-30 degrees F warmer than the warmest she has experienced in her habitat. And being cold blooded that is a pretty big deal, and will probably cause her to be much more active than she is used to. This may even trigger a manic state.
Other considerations include:
1. How do her gills stay wet (this is needed for her to "breathe")?
2. The difference in external pressure, and transition from high pressure to low pressure, has the potential for extreme health problems.
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Your mermaid does exactly what many of us do, living in Florida. Wear sunglasses, light, loose clothing, and apply sunblock regularly. **She is your creation, so you have full flexibility and you've given her almost exactly the same abilities as humans** - just a personal touch of not having experienced her ability to see light and breathe air (which she has physiologically - but has not experienced).
(My) assumptions:
* She is personally unfamiliar with sunlight, walking on two legs, and
breathing air; but her species has apparently evolved to tolerate (to
some degree) to Florida's heat and sunlight, according to your post;
* She has access to information and resources upon arrival on the
beach? Or at least knows how to survive - it's not far from a lot of
great fishing spots, shelter is the sea, weather is normally fine (at
least under the water), and in Florida she will not be the weirdest
person on the shore - trust me;
* She has a task to attend to?
Her goal is to trade whatever she brought for clothing and sunblock; dry off, and find who she's supposed to meet in your story. If land-walking is difficult, she should get a mode of transportation like a wheel-chair now that she is using legs and breathing with her lungs.
In essence, she might already be here...
[](https://i.stack.imgur.com/eORDy.jpg)
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Focusing on the effects of the sun is a good idea but don't overlook pressure differences. The blobfish for example at our pressure looks like a ball of goo but at the depths in the ocean it lives looks much more normal. Perhaps the lack of water pressure has your mermaid similarly bloat and assume a different shape than she is used to.
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The .50 BMG is a very powerful round with a lot of penetrating power. I want to survive it.
I did some research on my own, I'm just not sure how to combine these in a way to effectively stop a .50 BMG AP (black tip) round.
My research:
<https://phys.org/news/2016-04-metallic-glass-secret-almostbut-quiteunstructured.html>
<http://www.projectrho.com/public_html/rocket/bodyarmor.php#id--Physical_Armor>
<https://en.wikipedia.org/wiki/Sorbothane>
<http://www.spacedaily.com/reports/Mantis_shrimp_inspires_next_generation_of_ultra_strong_materials_999.html>
<https://en.wikipedia.org/wiki/Metal_matrix_composite>
<https://en.wikipedia.org/wiki/Metal_foam#Composites>
<https://en.wikipedia.org/wiki/Impact_depth>
As you can see it's a hot mess with everything thrown in the mix: shock absorbers, liquid armor, Liquid Ocelot, bulk metallic glasses, and some physics. I don't know which one would be best.
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The armor plate should be:
* As light as possible (invincibility needs both armor and speed)
* Capable of stopping .50 BMG AP rounds
* Capable of stopping them multiple times at the same location, if possible
Unobtainium:
* Using the magic of nanomachines, you can build stuff up from the atomic level ( i.e: carbon nanotubes are fine)
* For the time being, material, financial, and energy costs don't matter.
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Use ceramic plates just like Infantry body armor that can stop a 7.62 NATO round, but much thicker. This causes the weight of the ceramic to be excessive for any normal individual wearing it, which requires a robotic exoskeleton to help with the carrying part. Invest your money in battery technology for the exoskeleton, not "unobtanium". Make the ceramic plates easy to replace, since they do tend to crack. Infantry ones usually fit into a pocket in a nylon vest. You can completely encase a person in enough armor to stop anything up to a vehicle mounted weapon in this way (obviously if they are aiming a 30mm or an ATGM at you, you still have problems).
We have the technology today to make the armor, very sophisticated robotic exoskeletons, and the necessary electronic controls. We only lack a good power supply (which has to be quiet for it to be useful to infantry).
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Use Diamene: <https://www.google.com/amp/s/www.graphene-info.com/new-graphene-material-called-diamene-switches-flexible-harder-diamond-upon-impact%3famp>
It is light, malleable and wearable but once something hits it becomes extremely hard. Use a few hundred layers that are inlaid into a spidersilk-like substance as such substances are also light, malleable and extremely durable. This helps keep the fragments of Graphene (if there are some) to stay in place, since Graphene's edges are very sharp you dont want it to be flying about. The top layer being spidersilk also helps spread the impact a little before it reaches the Graphene.
To make the most of these layers, you first have the spidersilk at the top. Spidersilk is used instead of Kevlar because it's much stronger (1, 2, mentions it can be 10 times stronger than Kevlar, 520 MJ /M3). Then you have alternating layters of diamene and Carbon Nanotubes (<https://en.wikipedia.org/wiki/Carbon_nanotube>) with a last layer of spidersilk finishing it off again. These are thinner than spidersilk allowing more layers of diamene and they provide the same lightweight, flexibility, support and strength while seperating the diamene layers from each other. Better yet, the optimal size of a CNT can fit another CNT inside which is slightly less strong but it would add to the total strength. With a couple of hundred of these layers you are sure to stop several .50 BMG shots. Which leaves the kinetic energy to be disposed off:
You could augment this with non-newtonian fluids (<https://en.m.wikipedia.org/wiki/Liquid_Armor>), but in this case the fluids would only function as shock absorbers to reduce the kinetic impact before it reaches the body. But I would use a different method, mainly that of wheels. When a wheel hits something the metal frame is protected by the air in the rubber wheel (amongst other things). This impact causes an increase in pressure of the air and this is evenly divided over the wheel's frame. The armor would carry a liquid (probably an oil) that absorbs a lot of kinetic energy when it is pressurized. This is worn as a middle/bottom layer which rests on a frame. Whenever a bullet impacts the armour a portion of the energy is absorbed, turned into pressure and evenly divided over the frame so the pressure doesnt squeeze the user. It will never soak up the full kinetic force, but it will definitely spread the force even more than the other layers and absorb some to boot.
Edit: for those who say this cannot scale. It cannot scale by using 3+layers of graphene on top of each other. However if each Diamene layer is seperated from the rest they can all work like Diamene. A back of the envelope calculation using large CNT's to seperate each layer of Diamene you can fit 1763668 layers of seperated Diamene in 1 cm of armor. This defeats the claim that it would become too thick compared to current composite armors.
1: <https://openi.nlm.nih.gov/detailedresult.php?img=PMC2939878_pone.0011234.g004&req=4>
2: <https://en.wikipedia.org/wiki/Darwin%27s_bark_spider>
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# Futuristic material science and medieval suits of armor
Check out this article about [nanotech-fabricated metal](https://www.sciencedaily.com/releases/2019/01/190128125314.htm). Note this sentence: "A block of titanium where every atom was perfectly aligned with its neighbors would be ten times stronger than what can currently be produced."
You specifically mentioned this kind of nano-fabrication as a possibility. Well, it will work. Here's [somebody shooting](https://www.youtube.com/watch?v=C3fBkNIROg4) a titanium plate. It stops 50-cals. Even (just barely) an armor-piercing round.
People stopped wearing suits of armor because penetrating power simply grew too large. Armor would have had to be so thick it became impractically heavy.
But a block of metal with the same stopping power as the hunk in that video, that weighed a tenth as much? That's the same as being a tenth the thickness. That would be similar to the thickness of a suit of armor.
In other words, a suit of armor the thickness of an ordinary period-accurate piece could have the strength equivalent to a solid plate as thick as the plate in that video. And we know people used to wear old suits of armor; they trusted it with their lives.. Forging such a thing would require quite a lot of skill, but it could be done.
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The kinetic energy from the impact of a .50 BMG, particularly at close range, is huge. Use it. Per @Demigan's answer above, put in some mechanism to absorb the energy. But that energy will have to be dissipated or contained in some manner. Address @JBiggs concerns about battery life by using the energy to re-charge the batteries that help move the soldier around.
EDIT: The base of the armor kit should be an electrically-driven (e.g. motorized) “exoskeleton” (external to the human, internal to the armor), with power supplied by batteries. The armor plates should be mounted on actuators that re-direct the energy into a hydraulic fluid that is routed, via tubes (flexible at the joints) to a central hydrodynamic generator that turns the hydraulic energy into electricity. Movement in the armor, driven by the electric motors, would cause the hydrodynamic actuators to move, thus causing efficiency-sapping problems over time. Frequent re-charges of the batteries would overcome this, as would getting shot. It makes for an interesting problem space.
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I'll be as basic as I can. Ballistics Gel. You can make this stuff with common gelatin and it can stop a handgun bullet. I'm sure if you compacted it enough you would have something super effective.
Ballistic Gel (how to): <https://www.instructables.com/id/Ballistic-Gel/>
Ballistic Gel is known to DISPERSE the energy throughout itself. A bullet will sharply go through the gel at the beginning but then it will come to a complete stop.
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In the absence of 'handwavium' SF technology like force fields etc there are simply unavoidable physical limits to how much 'wearable' physical armor you can place between a human being and an incoming physical projectile of a given mass/structure/velocity.
The point being that body armor doesn't 'magically' make the force of impact of a hit go away. All it does is distribute that inertia of the round across the immediate surface area of the piece of body armor concerned - without being physically destroyed in the process.
So yes you can design a piece of body armor using currently available materials that will stop a .50 round. What you won't be able to do is;
A) Make it light enough for a human being to carry and still remain combat effective; and
B) Prevent the human being wearing it from having to absorb the kinetic energy of the hit.
Forget Hollywood - taking a hit while wearing body armor, even from a run of the mill handgun round 'hurts' with a Capital H!
The energy of the bullet has to go somewhere and in this case its the human wearing the armor. So while you might be able to design a set of convention soft body armor with plates that could stop a .50 round I guarantee the human wearing it, while they might survive, wont be getting up and going dancing any time soon, let alone continue on fighting. (In fact they'll be in an intensive care ward.)
For that kind of resilience you are looking for you have to start taking about 'power armor' which is a level technology in the purely speculative realm at this point in time.
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A wearable version of a hard-kill active armor concept like Trophy used on armored vehicles would do it. The Russians claim their Kontakt active armor can stop high-velocity depleted uranium rounds, so that would do it.
You will also need some good Kevlar or equivalent because you're still going to get hit by a lot of fragments.
Dragonskin once claimed that their advanced concepts would stop .50 cal -- they used a series of overlapping ceramic scales. Hype or reality?
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It would be nice if there were an atmosphere on the Moon with oxygen; in fact it could be just oxygen at 1/5 the Earth's pressure. People could live there. Now of course given the Moon's lower gravity the atmosphere would escape into space, but it'd take hundreds of thousands of years for that (roughly 1 million years if I recollect well). Enough time for 50 human civilizations to develop one after another.
Now there is oxygen on the Moon, but it is fixed in rocks and probably in some water. What would be the best, easiest way to make an atmosphere out of it?
My guess is that can be done with a powerful enough energy source. Rocks or water can be decomposed by heating.
Using the Sun's light for that could do, if it is concentrated. Nuclear reactors and nuclear bombs could be used too, but that doesn't seem that easy because it costs to send them; making an automated nuclear plant / bomb factory on the Moon may be cheaper, but other problems appear (ores, plant defects etc.)
So my first guess to a solution would be using solar energy, with mirrors that can be built in place or brought from Earth (as thin sheets of plastic). But how much of the Moon's surface would have to be used? I wouldn't cover too much of it with oxygen factories; that would cost a lot too. Let's say we want an atmosphere there in a reasonable time (hundreds of years). What approach to use?
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To make a lasting atmosphere on the Moon, we'd need to produce around 10,000 metric tons of gas per day just to keep it stable. Source: <http://www.geoffreylandis.com/moonair.html>
That is a lot. To give you an idea, in normal conditions, 1m3 of air has a mass of 1.024 kg. 10,000 tons would have a volume of approximatelly 10,000,000m3. That is nearly 50x the discharge per second of the Amazon river.
We can only imagine an industrial setup able to have that output in the realms of sci-fi. By the time we have the technology to set that up on the Moon for real, our solar cells should be more efficient than they are now, and we will have a better understanding of the ice deposits on the Moon. Otherwise, calculating your energy requirements seems pointless to me.
Last but not least, I don't think you want to burn rocks to make an atmosphere. That is wasteful, and the waste by-products may make the air unbreathable. You will also need to rewrite the maps for the lunar surface every few days to make up for all the surface you've been digging and moving around.
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Using heat to decompose molecules is a bad idea in a low gravity environment like the Moon.
At high temperature the molecules have an higher average velocity, meaning that an higher fraction of the molecules will have enough velocity to escape the gravity well. This in turn will mean that your estimated life span for the atmosphere will be considerably shorter.
Moreover from a hot mass you would develop both the Oxygen and the material it was bounded to. You will need to separate them quickly, else they will recombine (that's why you don't use water to extinguish extremely hot fires, because by doing so you just put Oxygen and Hydrogen next to a hot body)
And you will also have the additional problem of dissipating the amount of heat, unless you want to have a boiling planet totally unsuited for life.
Once you have an abundant source of energy, go for the electrolytic path: dissolve the material in a suitable solvent, apply current and harvest the developed substances.
On one hand you will get Oxygen for your atmosphere, on the other hand you will get metals which you can use for other purposes on your lunar colony.
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Simple. All you have to do is transfer the oxygen in the atmosphere of Mars to the Moon. Here's how.
* Mars atmosphere is around 96% CO2. Stations at the poles compress free air into carbon-fiber tanks where the air becomes liquefied. The tanks are shot vertically into space via electromagnetic railgun.
* Stations in polar orbit catch the tanks and reshoot them via railgun into near equatorial orbits.
* Ion drive bombers catch as many of the tanks as they can in a single orbital swing-by and slingshot to the Moon.
* On the way the bombers freeze the liquid contents of the tanks into large blocks which are then dropped to awaiting stations along the lunar equator in another single orbital swing-by, slingshotting off to Mars again with their loads of empty tanks (a circuit). The tanks are dropped in equatorial orbit where they are recollected by the polar orbit stations and dropped back down the the polar stations.
* The lunar stations regasify the Martian air blocks in solar collectors. The CO2 gas is then combined with hydrogen -- partially obtained by cracking lunar regolith in solar furnaces, the other byproduct being glass -- over locally-mined nickel catalysts, forming a mixture of water and methane.
* The major waste gasses would be nitrogen and argon, both extremely rare on the moon. The nitrogen would have many practical uses in industry and biochemistry. The argon could be used to make lasers to wage war.
* The water is electrolyzed via solar voltaics into hydrogen, which is fed back into the catalyzation process, and oxygen, which is freely released into the atmosphere.
* The methane is passed through glass rod matrices -- made from the cracked regolith -- in high temperature solar collectors producing hydrogen gas, which is also fed back into the catalyzation process, and solid carbons.
* The carbon is used to manufacture additional carbon-fiber tanks which are shot into equatorial orbit via railgun to be opportunistically collected by passing bombers.
* Repeat.
The fundamental process is documented here <https://patents.google.com/patent/US4452676>.
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Once you have a significant atmosphere with a density of a hundredth of a millibar or so, it will stabilise itself as it becomes much colder with height.
That is as long as you stick to oxygen and nitrogen (don't emit greenhouse gases, and an ozone layer is also bad)! The day/night temperature differences will create quite a lot of wind, but not in the topmost atmosphere layers, because there is not enough pressure there.
The important point is that once the pressure has dropped so far (with height) that the mean free path lenght get's into the kilometer range, the temperature must be so low that practically no particle has escape velocity any more.
The problem will be to get beyond the first step, when the gas molecules can still fly directly off the hot sunlit moon surface into space, without hitting other molecules.
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Fantasy and sci-fi works often are set in worlds of dramatic terrain, because, well... it's dramatic. A few examples of the kind of thing I'm talking about:
I understand that Earth has some geographical features which fit the bill, but they're very rare, and not always as wondrous as fantastical depictions. My question is simple. **Say I want a world chock-full of spectacular mountains, cliffs, waterfalls, pillars, arches and spikes. How do I justify it?**
When I say "justify", I don't mean "say that it's so just because". I want to know **what factors and conditions could make my planet *more* likely to have such dramatic features than Earth**. Low gravity is an obvious one, but what else? Note: this world must also be habitable.
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I note that popular images of the airless moon showed tall, steep, and jagged mountains until photographs in the 1960s showed the hills were low, smooth, and rounded.
Telescopic photographs of regions of the moon were often taken when the Sun was low in the Lunar sky, thus making long shadows of the mountains and crater walls. Astronomers could calculate the true heights of mountains and crater walls if they knew what angle the Sun was at when the photos were taken, but people who just looked at the photos assumed that the mountains were very tall and steep.
The factors that made the Moon airless also made it geologically inactive for billions of years, meaning the mountains on the Moon were billions of years old. Even though those billions of years old mountains weren't weathered by windblown dust or by precipitation, they were weathered by billions of years of temperature changes, harsh solar radiation, bombardment by charged particles in the solar wind, and by a slow steady bombardment by micrometeorites and occasional large meteorites.
Of course a small world like the Moon could have been terraformed by space travelers when it was young and given a breathable atmosphere when its mountains were still tall and jagged. I have read that if humans terraformed the Moon by giving it an atmosphere that atmosphere would escape in a thousand years. I read once, in a story probably co authored by Arthur C. Clarke, that the Moon was terraformed and the atmosphere was kept from escaping by a layer of nanobots that were attached together and covered the entire atmosphere and bounced back all molecules headed upwards.
For your planet to be habitable for humans, it must have the right proportion of various gases in its atmosphere and a tolerable total atmospheric pressure. The vital oxygen in Earth's atmosphere was produced by plants, and it took billions of years to do so naturally on Earth.
So the planet should have a surface gravity and escape velocity high enough that the vast majority of the oxygen has not yet escaped from the planet. Which means that if the habitability of your world is natural and not due to highly advanced terraforming the surface gravity can be considerably less than that of Earth but should be greater than that of Mars, for example.
I also point out that humans need only the oxygen in Earth's atmosphere, since they only need to breath that oxygen for breathing, and only need small amounts of carbon dioxide and nitrogen to support plant life and small amounts of water vapor to keep the air moist enough. That a breathable atmosphere could be a lot less dense than Earth's, which might reduce the rate of weather erosion. Though a highly reactive mostly oxygen atmosphere might reduce rocks to rust and dust and crumble mountains.
Someone may point out that the surface gravity and escape velocity of Titan - 0.14 *g*, and 2.639 kilometers per second - are much lower than those of Mars - 0.376 *g*, and 5.027 kilometers per second - and lower still than Earth's, 1.000 *g* and 11.186 kilometers per second, and yet the atmospheric pressure on Titan is many times as great as on Mars, and even a bit greater than on Earth.
One reason for that is that Titan is much farther from the Sun than Earth is, and so it is much colder than Earth, far too cold to be habitable. So the temperature of the molecules of gas at the top layer of Titan's atmosphere, where gases escaped from the atmosphere into space, is much lower and so the molecules are moving much slower, and a smaller proportion of molecules reach escape velocity and zoom off into space.
If Titan was moved to Earth's distance from the Sun, it would be hot enough at the surface to be habitable, and the gas molecules at the top of the atmosphere would be about as hot and move as fast as the gas molecules at the top of Earth's atmosphere. Thus Titan's atmosphere would escape into space much faster than it does.
>
> Observations from the Voyager space probes have shown that Titan's atmosphere is denser than Earth's, with a surface pressure about 1.45 atm. It is also about 1.19 times as massive as Earth's overall,[34] or about 7.3 times more massive on a per surface area basis.
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<https://en.wikipedia.org/wiki/Titan_(moon)>[1](https://en.wikipedia.org/wiki/Titan_(moon))
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> The persistence of a dense atmosphere on Titan has been enigmatic as the atmospheres of the structurally similar satellites of Jupiter, Ganymede and Callisto, are negligible. Although the disparity is still poorly understood, data from recent missions have provided basic constraints on the evolution of Titan's atmosphere.
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>
>
<https://en.wikipedia.org/wiki/Atmosphere_of_Titan>[2](https://en.wikipedia.org/wiki/Atmosphere_of_Titan)
Thus until the origin and survival of Titan's atmosphere is better understood, it seems advisable for writers to avoid giving worlds as small as Titan dense atmospheres, especially dense atmospheres that have the same temperature and composition as Earth's.
There may be ways to give your world a breathable amount of oxygen without it being produced by life over billions of years during which oxygen and other gases in the atmosphere would have weathered tall mountains.
For example, the world could be an Earth like but very young planet which has young tall mountains and one large ocean basin filled with water. The world suffers from runaway glaciation and the ocean basin freezes. A giant asteroid impacts, probably in the ocean basin, and vaporizes a lot of rock and all the ice in the ocean basin. the heat is so intense all of the vaporized water also separates into hydrogen and oxygen. Almost all of the super heated hydrogen escapes from the planet into space while more of the heavier oxygen is moving slow enough to be retained by the planet and becomes an oxygen atmosphere. Some of the hydrogen is retained and recombines with oxygen to form water, and water vapor in the atmosphere serves as a greenhouse gas and keeps the temperatures warm enough for humans. Of course the impact would probably release a lot of poisonous gases into the atmosphere and you would need processes to reduce them to breathable levels by the time of the story.
As near as I can tell the tallest mountains in the solar system are: 5) Ascraeus Mons on Mars 14.9 kilometers or 9.3 miles high, 4) Boossaule Montes on Io 17.5 to 18.2 kilometers or 10.9 to 11.3 miles high, 3) the equatorial ridge on Iapetus 20 kilometers or 12 miles high, 2) the Olympus Mons Volcano in Mars 21.9 kilometers or 14 miles high, and 1) the central Peak of Rheasilvia, a crater in the asteroid Vesta, that is 22 kilometers or 14) miles high.
Two of them are on Mars, a planet large enough to possibly become habitable under some circumstances, such as being terraformed by humans in the future. But I believe that the slopes of those volcanoes are so gentle, and the curvature of Mars's surface so great, that they would be impossible to appreciate when looking at them. But cliffs at the base of Olympus Mons are up to 6 kilometers or 3.728 miles high.
On Venus Skadi Mons rises 0.11 percent, or 0.0011 of Venus's mean radius, on Mercury Caloris Montes rises 0.12 percent, or 0.0012, of the mean radius of Mercury, on Titan Mithrim Montes rises 0.13 percent, or 0.0013, of the mean radius of Titan, on Earth Maua Kea and Mauna Loa rise 0.16 percent, or 0.0016, of the mean radius of Earth, and on Mars Olympus Mons rises 0.65 percent, or 0.0065, of the mean radius of Mars. The other two bodies in the solar system, Ganymede and Callisto, that might possibly have become habitable under other circumstances, or that humans might reasonably expect to terraform in the future are largely made of ice and thus very flat.
A number of smaller bodies in the solar system have mountains whose heights are larger proportions of the radii of the bodies, but those are smaller bodies even less likely to be habitable than Mercury or Titan. The largest of them is Io, where Boosaule Montes rises 1 percent, or 0.01, of Io's radius. Io is considerably smaller and less massive than Mercury, Ganymede, Callisto, or Titan.
The tallest possible height of a surface feature is determined by the structural height of the materials it is made of and the materials below it. Once the height, and thus the pressure at the bottom, exceeds the limits of the material it will soften and flow out from underneath the surface feature which will then sink until it reaches a new pressure equilibrium.
The stronger the material, the higher it can be piled before the pressure at the bottom becomes too much. And the lower the surface gravity of a world, the higher a specific material can be piled without the pressure at the bottom becoming too high.
Thus the smaller the surface gravity of a world, and the stronger (which usually means denser) the materials it is made off, the higher its mountains can be. Unfortunately the surface gravity is usually proportional to the density of a world, so worlds with low surface gravity tend to have low density materials, and worlds with high surface gravity tend to have high density materials. Also planets with low surface gravity tend to have difficulty retaining for geologic time periods atmospheres dense enough to be breathable.
So one possibility would be a super Earth or mini Neptune type planet that lasts long enough to become layered with the densest material sinking to the bottom. So it will have an iron nickel core. Then it is struck by another planet early in their solar system's formation, and the giant explosion vaporizes most of the planet and most of the materials of both planets escape from them. But parts of the cores of the two planets remain liquid instead of gas or plasma, mostly the densest materials. The cores capture each other, orbit each other, and gradually spiral inwards until they merge in another giant collision.
The liquid nickle iron core of the merged planet gradually cools down and solidifies into a solid planet that is mostly nickle, iron and other heavy metallic elements. Meanwhile many of the gaseous and liquid fragments of heavy metals from the planetary cores remain in orbit around the merged planet, cool off, and solidify, and clump together to form larger and larger bodies orbiting the merged planet.
Tidal forces push the outer fragments farther and farther from the planet, where they may merge into one or more moons, and pull the inner fragments down toward the planet, and they will eventually crash into the planet. That will form craters and circles of ejected materials, which may be taller than those on rocky planets if they are made entirely of various metals.
And maybe a few more collisions can provide the planet with a thin layer of rocks and soil and water and an atmosphere, or maybe it will be terraformed by aliens or humans.
Another factor which affects the height of mountains on a planet will be the forces that produce mountains. As a general rule, larger, more massive, and denser planets will tend to have stronger forces to thrust up mountains as well as stronger forces to tear down mountains.
One way for a smaller body to have stronger geologic forces than it would normally have would be tidal interactions with one or more other worlds. One of the worlds mentioned above, Io, has constant volcanos because of tidal interactions with Jupiter, and also has a tallest mountain, Boosaule Montes, that is very high in absolute terms and also very high relative to the radius of Io.
The volcanic rate of Io is so high that Io would be a dangerous place to live, and might raise the surface temperature of Io high enough to be uninhabitable. On Europa, the next farthest moon, the volcanic rate is not high enough to keep Europea warm enough to be habitable.
But if an Earth or Mars sized moon orbited as gas giant planet that happened to be in the habitable zone of their star, and if that planet sized moon orbited the gas giant planet at the right distance to have the right amount of tidal heating and volcanoes, it might have a breathable atmosphere as well as a much more impressive terrain, the result of more active geology, than Earth does.
Or maybe you might write a story where tourists on the planet Garbruth see all the famous natural wonders like the Coslorm Spires, the Jarganth Mountains, the Grand Canyon of Lymfar, the Mountains of Wadmoss, the Chasm of Owo, the Rock Arch of Hawtute, The Cliffs of Klabon, and Mount Ebertast, to name a few, and come away with the impression that the planet is all vertical land forms. But flying back to the spaceport, one of the tourists does something they didn't do before. They find a view screen of the vehicle and set it to show what they are flying over, and they see the endless Plains of Jahanne.
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Figure out a way to make the planet's atmosphere a relatively new development. That way, its dramatic surface hasn't been worn away to smoothness by billions of years of erosion by wind and water.
Perhaps the planet was an atmosphere-less sphere in close proximity to a large gas giant which constantly stole the planet's native atmosphere into its greater mass.
Then a million years ago, a rogue planet's gravity pulled the airless planet into a different orbit farther from the giant gas-thief. Maybe in the process, the rogue planet also liberated a large cloud of the gas giant's atmosphere which found its way to the airless planet.
Now you have a planet whose surface is young with sharp edges and towering geological structures, not yet worn away by its newly acquired skies. If somehow, the atmosphere which it stole back from the gas giant also happened to be friendly to earth-born life, then all it would take is a well stocked colony ship to bring some of those fantasy artworks to reality.
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Mountains are caused by a combination of tectonic activity/displacement and erosion. This alone gives you multiple possibilities:
* There could be significant more tectonic activity on your planet. Earth has 7 tectonic plates. Maybe your planet has 20, or the tectonic activity is accelerated. I am not sure what other implications this would have, or why a planet would have more/less tectonic activity in the first place.
* There could be more erosion on your planet. More rain would mean more rivers. More rivers would mean longer and deeper canyons, which would mean taller mountains. Maybe your planet doesn't rain now, but has had significantly more rain historically, for whatever reason. Waterfalls would need rain to sustain them, as well. Wind is also a source of erosion.
* The composition of your planet could be different. Different materials/rocks erode at different rates. This leads to a lot of interesting geological structures here on Earth.
* Ice/glaciers is another contributor to erosion that has a huge effect on landscapes. There are massive valleys that were created by no longer extant glaciers that moved inches per year for many thousands of years. Maybe your planet has a recent history of ice ages.
There are some other options not related to tectonic activity or erosion:
* Exotic life. Limestone, here on Earth, is a rock that is made up of the skeletal remains of ancient ocean life. Your planet could have a similar history, with the remains of some unique kind of life creating a material with unique properties that shapes your planet's landscape. Or the activity of existing plant/animal life could actively change the environment. Maybe the activity of some unique kind of life form creates mountains over many thousands of years.
* Sentient life. Maybe there were massive wars on your planet, or it was mined by some visiting alien race with highly advanced technology, with the mountain ranges being the scars left behind.
Regardless, something exotic (i.e., not just tectonic activity and erosion) would be needed to explain more exotic formations, if you bothered to explain these formations. Things like spikes, massive pillars/columns, those looping formations in your first picture. Exotic life, weather conditions, or materials would be needed to explain these, because they otherwise would probably lack an actual natural explanation consistent with what we know about the actual world.
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The types of landscapes you seem to be after usually have two things in common, they tend to be, [geologically](https://en.wikipedia.org/wiki/Geologic_time_scale), young and they tend to be composed of, relatively, soft and chemically active sedimentary rock. What you need to do to have a planet that's covered in these sites is to have it be extremely tectonically active, with rates of tectonic movement measured in tens of *metres*, not single millimetres, per year, to create young mountainous terrain, **and** if you *really* want to push it have a [Carbonitite](https://en.wikipedia.org/wiki/Carbonatite) mantle. Planet wide carbonitite volcanism will not only make those rates of tectonic movement reasonable but also means that erosion rates are equally extremely high in most places, due to the chemical reactivity of the rocks, thus creating extreme landscapes at every turn.
This combination will create sharp mountains and deep canyons and all sorts of strange erosional features but it will also mean that sights you show your kids will be vastly different when they try to take your grandchildren back there. The cost of really dramatic scenery is a really quick turn over rate.
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So the idea is that most people use horses, but in this deserted mountain range, people have had to adapt to rams, so the breeding, domesticating and all of that has been handled over generations.
Now, much like dogs to wolves & horses to wild horses, Rams have been trained to be ridden over mountains and into war, up steep cliffs and thin ledges, pretty much all the normal ram stuff with people riding them.
Would this be possible? Would there actually be any technical advantage in warfare if this were medieval times? Would horses being taller stand a better chance? And would rams even be able to support the weight of a rider in the first place? Or would they just buckle under the weight? Could they evolve to support the weight? Mainly, I just want some pros and cons to using rams in warfare, it seems like a good idea, but it might be a horrible one. I don't think feeding them would be a problem though, they eat almost anything I think.
I also had the idea of them ramming horses, and possibly breaking bones, but that might have been a bit of an extreme idea. I just wanted to know my limitations on the matter. And I always like to think of dogs, they all came from one animal, but have been bread to as little as jack russels to hunt foxes down in there holes and as big as Karelian dogs for bears. So I always wonder what selective breeding for certain traits can do to make things possible.
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EDIT: Was thinking goats, not sheep. Revised accordingly.
So, yes it's possible. Yes, it would definitely give you an advantage in rugged terrain. Many historical forces used mules and donkeys instead of horses in mountainous terrain specifically because horses couldn't handle the slopes as well.
It WOULD require a significant breeding effort over time. Sheep aren't nearly as smart as horses are, and a mount you want to use for anything except a pack animal needs to be at least SORT of clever. So you'd need bigger, smarter sheep.
Now, that said, you wouldn't be able to put a man on a sheep's back and have it go up and down a mountainside the way wild unladen bighorns do. Any sheep-rider calvary you'd have would want to travel very light, and based on both the limitations of the sheep themselves and the kind of terrain you'd be operating in, they'd be a calvary in a more Asian tradition: Using mobility and ranged weaponry rather than spear charges en masse.
Is that what you were looking for?
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There's a reason ancient armies used chariots and not shock cavalry (mounted knights): it took a lot of selective breeding to convert the relatively small wild horses into the beasts called destriers (war horses).
Before heavy cavalry, the books say "*the Huns rode ponies*", "*the horses during the Dane invasion of England weren't larger than ponies" and so on*.
A destrier outweighed its rider 7 to 1. And they weren't very tall, but horses are very heavy, to the point a pony the size of a St. Bernard is twice as heavy as the dog.
I have looked it up and "*Rams are typically 5 to 6 feet tall (1.5 to 1.8 meters) from head to tail, and weigh 262 to 280 lbs. (119 to 127 kilograms), though they can grow to over 300 lbs. (136 kg)*". That means you need your rams to be at least **three times heavier than ours are** until they are good cavalry.
And we use horses for more reasons: they have long lives (15 years compared to the 10 of a ram), good speed (40 km/h-25 miles/hour, rams are half as fast) and good endurance. I don't know the endurance of a ram, but sheeps can't run longer than two hours and make around 16 miles in that time.
So you need a lot handwavium for making plausible ram mounts. Unless you train them to pull chariots.
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**Is it possible to build a garbage recycler that turns residues into its constituent elements using plasma and accelerating it through a magnetic field?**
The technology level is around that of the typical space opera: starfaring civilizations. Physics and chemistry are the same as ours.
Energy input and disposal is not a concern (we could include a fusion plant or ten to the project, but we do not have unlimited power!).
This is a space based recycler, so hard vacuum is easy to access, but there can be atmosphere artificially provided if necessary.
Resting frame of reference.
The material to be recycled is frozen (few Kelvins) compacted heterogeneous mixes of waste in 10m sided cubes (in the order of tens of thousands of tons). The cubes are covered in a film that prevents out-gassing and keeps any elements or composites that manage to be liquid at the said temperature. Encompassing everything from paper sheets and fish poo to shredded nuclear reactors, cars and solid blocks of reinforced concrete. The blocks can have any element of the periodic table, and all of them are to be expected in any proportion, including all useful alloys, compounds, organics and textiles ever known.
The film can be of any material, though it's planned to be a carbon-based polymer of some sorts. It can be removed from the cube prior to process if necessary. The cube can be made smaller or even shredded if required by the process, but bigger chunks are never going to be provided. If it needs to be made into dust/fine particles, the "atomization" process should be part of the recycler. If the mix needs to be preheated, it will also be part of the process.
There should be no expectation that the mixture has the same proportions of element rarity present in the universe or Earth's crust.
Noble gasses and the most heavy and radioactive elements can be mixed at the end of the process, if it's too hard to differentiate them. PREFERABLY NOT!
It can be an expensive piece of infrastructure: it's meant as a one of a kind per heavy populated star system (in the order of 10^7 citizens). Its purpose is to be the end step of traditional recycling process leftovers.
It's located in space, it can be near the main star or well past the ice giant portion of a star system, wherever you need it.
Size is also not a concern. Single structure designs are preferred over "distributed" infrastructure, for defense purposes, but will do what's necessary. Should be less massive than a little moon (10^19kg).
It does not need to be practical. It's meant as a "safeguard" against interstellar resource blockades (like subsidized agriculture in some countries).
It need outputs in the magnitudes proposed to be able to keep up with demand during wartime on systems whose planets do not have enough tectonic activity to produce veins of vital heavy metals and elements.
During peacetime it's used to just simply complete a loop of resources in space where necessary, maintained by deep space dwellers to avoid being captives of planet surface inhabitants.
As strategic infrastructure, its existence comes first. More productivity and more efficiency are the secondary really important points, and economic sense is the third concern, but some systems need one to be anything else than colonies.
**Previous research and ideas**
<http://www.inentec.com/pem-facilities/>
<https://www.explainthatstuff.com/plasma-arc-recycling.html>
I've envisioned a toroidal fusion power plant that is fed a stream of fine grained garbage along with the usual fusion fuel. The stream would get turned into plasma and then ejected to a magnetic accelerator that uses atomic weight and magnetic fields on the curves of a loop to separate the stream into its constituent atoms in separate receptors.
Is this or another design feasible?
How does it work?
[](https://i.stack.imgur.com/6Z6nm.jpg)
Synchrotron, the shape that resembles the proposed design
**Bonus points:**
* Approximate volumetric size of the plant (capable of processing 1 cube per day)
* The order of magnitude of energy or fuel consumed or produced (for any fusion or other kind of reaction(s) you choose for the process)
* How well does it scale (up and/or down)
* Containment method for the elemental outputs
## EDIT
Based on answers, it seems clear that mass is really relevant to the segregation process. Please, feel free to include a centrifuge or whatever you come up with to use mass to your advantage.
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TL:DR feasable? Yes. Practical? No.
This design is not really tenable in it's current form for a few reasons.
Firstly plasma is not at all dense (or at least isn't in most man-made fusion reactors) very little hydrogen is used in a fusion reactor and so as soon as you add your finely ground trash it will likely cool down to below the threshold needed for fusion meaning essentially you'd be just as well off (likely much better off for reasons I won't get into) vaporising and ionising your trash with any other form of heat like a laser, strong electric current, concentrated sunlight or intensive radiation (which could be from a fusion reactor) and then putting it through the magnetic seperator.
The other problem with plasma's low density is the fact that the 10m solid cubes you are burning up will produce a massive volume of plasma (like really big.) and this plasma can't be high-density because otherwise particle-particle interaction will dominate and it will be much harder to separate. This means your plant will either have to work incredibly slowly only doing a few grams per year or will have to send plasma through at tremendous speeds which means you'll need much more powerful magnets to send them on those curving paths and will be using much more energy per kg of mass sent through than would be reasonably tenable by any civilisation without something like blackhole power generation.
Your design will also suffer from problems arising from double ionisation. because it separates based on specific charge. Lets say we have two ions going through the detector, Carbon-12 with one electron missing and Magnesium-24 with two electrons missing. Theese two ions will be treated almost identically by the separator the only difference coming from their binding energy which will be so minute that the track would need to be almost a hundred times longer. This is likely to always be a problem too whatever method of ionisation you use, if you ionise it more you'll get double, single and triple ionisation less and elements will be left behind.
all this being said you device could still be used as PART of a larger macro-recycling system, oncee you've taken out everything you can normally (I.E. chemically and physically) some waste is bound to still be there. This is what you then put through a industrial scale mass spectrometer and split into constituent elements.
The massive energy concerns might not be too bad either. In theory all the energy goes into the many steams of fast moving ions and a little bit of cyclotron radiation both sources of energy in their own right that can be easily recycled and fed back into the system. If you can fare space then you can probably also generate a lot of energy very quickly.
So while i can't see this becoming the main way we deal with trash it might very well be part of a larger system for dealing with that really pesky rubbish that won't go away.
EDIT: regarding your bonus points
Size could vary really quite a lot in general bigger plants will be more successful at separating elements out more cleanly and will be easier to maintain while smaller plants will process waste faster but might prove much harder to construct.
Best case scenario for energy consumption is the enthalpy of formation of the waste which for any space faring civilisation is basically 0 more likely it's going to be determined by the rate at which waste needs to consumed, the efficiency of their tech, the elemental composition of their waste, and a thousand other variables we don't know.
it scales really well actually in fact i'd advice building these plants in deep space where vacuum is cheap and you can spread out as far as you want.
The elemental outputs are fist going to be sent through a solenoid so that energy can be recycled from the fast moving matter streams, the now slow elemental beams can simply be sent to electrodes that will extract energy from the charge of the ions. In the case of gaseous elements its going to be a lot harder, for the reactive elements i'd advice using a calcium electrode which you then use electrolysis to extract the gas back off of. Noble gases are going to be harder but not impossible you might need to fire them into somekind of solvent they dissolve in (a pure bitumen perhaps) then extract them later.
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**Very likely**
It would probably work. Centrifuges are used to enrich uranium (meaning separate U-235 from U-238) by turning it into a gas and then exploiting the fact that the two isotopes have different weights, so when you spin them, they will move at different speeds. This appears to be using a similar idea.
It would be a beast of a thing to design and make it capable of doing any element. But if today we have uranium gas centrifuges, a plasma disintegration centrifuge is plausible, even one sensitive enough to be a universal disassembler. It would likely take decades or centuries of technological development past what we have today, but if your story is far enough in the future, that's not a problem.
**Efficiency**: Turning things into plasma requires the expenditure of a lot of energy. This plant would likely require a nuclear reactor, probably of a heavily optimized design that directly converts the garbage to plasma in the volumes required and only incidentally produces enough conventional power to keep itself running.
**Containment method**: The elemental outputs will likely not be energetic enough to undergo nuclear reactions, so you can just shoot them into a chamber full of water (one per individual element). That will decelerate the ions enough to stop them in the receptacle and turn them back to ordinary atoms. This will release Cherenkov radiation (which you can likely use to generate power, improving the efficiency somewhat). The atoms will react with the water; only noble gases like to hang around in naked elemental states (never mind that they'll violently 'liberate' electrons to refill their own depleted shells), so you will need to use ordinary chemical engineering processes to refine them out.
[Disclaimer: I am not a physicist. Someone who is can probably nitpick holes in this.]
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## Good thing you've got fusion plants
Because you're going to need a lot of energy. Of critical importance is the ionization energy of all the elements. As plasma contains normal elements stripped of their electrons, enough energy will need to be pumped into each trash cube to liberate enough electrons to form a plasma.
The energy required to energize/plasma-ize 10m^3 of random garbage will be immense. At the low end, let's continue consider hydrogen. It takes 1312 kJ/Mol for complete ionization. But hydrogen is easy. It's already a gas.
Iron is trickier. It's a solid and does not yield energy through fusion. Iron's ionization energy is 762.5 kJ/Mol for the first electron. Ionization energies rapidly increase for each electron there after.
I don't know if iron has to be heated to boiling before it can turn into a plasma. If it does then the energy requirements for this reactor are staggering. Assuming linear specific heat values at all temperatures of 1kg of iron of 449 J/kg K; it takes 1407166 J to boil 1kg of iron. Add in the heat of vaporization and it gets even more expensive.
## Reactor Design Considerations
There's a couple things you'll need to account for in this reactor.
* Don't let the plasma touch anything. I've seen temperatures of 30,000 Kelvin in the literature. With the energies under discussion, the plasma temperatures may be considerably higher. Normal matter does not perform well when hit with high energy atoms. This is a long standing problem in fusion power plants under development now.
* This is not fuel. Anything iron and heavier does not yield energy when fused.
* Injecting cold matter into this reactor will require ridiculously high energy flows to sustain. Each 10m^3 will need to be heated to plasma temps, which will vary wildly from cube to cube. As mass leaves the plasma chamber, it will take thermal energy that must be restored in order to maintain the plasma.
* The reactor must contain the rapid expansion of gas phase products. Water expands 1700x when turned to steam. Other solids or liquids may expand even more. Not only must the reactor contain the expanding gasses but also the high speed chunks of arbitrary mass accelerated by those products. In other words, without preprocessing, each cube is a 10m^3 fragmentation bomb.
* Watch out for the really caustic elements such as fluorine and chlorine. These elements aren't bad when bound to other elements at room temperature, but this reactor is not normal. Special precautions will have to be taken or the reactor may eat itself.
## Design trade-offs
Okay, so somehow the reactor works. It separates each element and doesn't destroy itself. You've expended an enormous amount of energy to get a very hot gas. Well done!
However, you now have a big hot cloud of random elements that need to be sorted, cooled and turned into products that can be sold. How will you sort these? How will you prevent unhelpful chemical reactions when the atoms cool down?
Having done a little research into hydrocarbon plasmas, I can say without a doubt that this area is crazy complex and very hard to manage, even with single element plasmas. This reactor must accept all elements in any ratio or quantity. This is the [pdf manual](https://www.bolsig.laplace.univ-tlse.fr/wp-content/uploads/2016/03/bolsigdoc0316.pdf) for a real life plasma calculator that only does one element plasmas. All of those input variables will change between batches and perhaps within each batch.
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One of the ways to create a major mountain range is a process called *subduction*.
[](https://i.stack.imgur.com/oPu4B.gif)
Here, heavy oceanic rock sinks beneath the lighter continental rock. The result--coastal mountain ranges like the Andes, the Aleutians, the Japanese and the Southern Alps.
But look ***closer...***
[](https://i.stack.imgur.com/p95C9.jpg)
Between the Pacific Ocean and the Andes Mountains are lowlands. Narrow, undeniably, but still closer to sea level. So the question is this--**is it possible for a mountain range to be the beach rather than at least a few miles inland? And if the answer is yes, then what force of geology would I need to make that possible?**
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# "Beaches" are a result of erosion
Erosion wears down huge cliffs into smoother descents into the ocean. First you have this: [](https://i.stack.imgur.com/680wP.jpg)
where the cliffs drop directly into the water. Then, after some time and sufficient rain, eroded material is deposited at the bottom of the cliffs, until you have this:
[](https://i.stack.imgur.com/BI8dD.jpg)
Given a few tens of millions of years, the process continues until the Andes themselves start several miles back from the beach, which is now a coastal plain.
# Conclusion
Young mountains will rise directly out of the water. But beware, it takes a long time for a mountain to rise. By the time it has gotten to the height of the Andes, some millions of years have passed; plenty of time for a coastal plain to have developed.
The best way to slow down this erosion is to have a lack of water. But the west coast of South American from Lima, Peru south is about as dry a place as exists on Earth, and you can see on a map how much coastal plain has formed.
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**Short answer:** You can have cliffs like this, but they're not going to be as high as the Andes.
**Long Answer:** You have several options for creating cliffs like this, but none of them are going to be as high as the Andes.
## Let's talk about mountain formation
**Option one: Fault Block Mountains**
Maybe you're thinking of something like this:
<https://commons.wikimedia.org/wiki/File:Telascica-Cliff.JPG>
[https://commons.wikimedia.org/wiki/Category:Telašćica\_Nature\_Park#/media/File:Telašćica\_Cliff.jpg](https://commons.wikimedia.org/wiki/Category:Tela%C5%A1%C4%87ica_Nature_Park#/media/File:Tela%C5%A1%C4%87ica_Cliff.jpg)
...but with mountains. Welcome to the Telascica Cliffs in Kornati National Park, Croatia. Let's zoom out and take a broader look:
<http://crodestinations.com/telascica-one-of-the-most-popular-havens-for-yachtsmen-in-the-adriatic/>
In the pics on that page, you can see how it's just the western face of the cliffs that rise dramatically out of the water. The eastern side of the island gently slopes down. That's because the cliffs are a tilted block on a fault line.
You can scale up tilted blocks to the size of mountains, and what you get is the Big Sur:
<https://en.wikipedia.org/wiki/Big_Sur#/media/File:Central_Californian_Coastline,_Big_Sur_-_May_2013.jpg>
Another variation of fault block mountains is are horst and graben cliffs. The scaled-up version of these is a rift valley with a narrow sea between them (as kingledion points out, if you have enough time for an ocean to form, beaches will have formed).
<https://en.wikipedia.org/wiki/Horst_(geology)>
In both cases, these cliffs are usually about a mile high before erosion.
**Option two: extreme erosion**
In this case, you're looking at something like the Na Pali coast.
[https://en.wikipedia.org/wiki/Nā\_Pali\_Coast\_State\_Park#/media/File:Na\_pali.jpg](https://en.wikipedia.org/wiki/N%C4%81_Pali_Coast_State_Park#/media/File:Na_pali.jpg)
Whether or not you get this is dependent on what type of rock you have and how it erodes. It's also going to be about a mile high.
Another way to do extreme erosion is fjords.
<https://en.wikipedia.org/wiki/Fjord#/media/File:MilfordSound.jpg>
## Now let's talk about the other half of this: beach erosion
The easiest way for you to not have beaches is to have something that gets rid of beaches. These processes exist. To quote this lecture: <http://www.iupui.edu/~g115/mod13/lecture05.html>
>
> Eroded coastlines are defined by wave energy erosion exceeding sediment deposition.
>
>
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In other words, you want your waves to carry sand away faster than it can deposit. This can be done with relatively swift offshore and nearshore currents and riptides.
It helps if your mountains are made of relatively hard rock, like gneiss, that erodes slowly compared to how quickly the ocean washes sand away. The west coast of the US also has submarine canyons that give the sand a place to go as the current carries it away from the cliffs.
## Last but not least...
You might be disappointed about your mountains realistically being a mile high. Keep in mind the Velebit in Croatia are about a mile high.
<https://www.flickr.com/photos/trancevelebit/5023784382>
Also, this is high enough to cause a pressure differential in winter that results in strong winds. Your ocean immediately adjacent to your mountains might not be navigable for part of the year.
<https://en.wikipedia.org/wiki/Bora_(wind)>
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Very young mountains not raised by subduction would seem to be the best bet.
The volcanoes produced by subduction are always a ways in from the edge of the continental plate which is usually pretty close to shore. So that's not ideal.
Crumple zone mountains (like the Himalayas and Alps) are caused by two continental plates hitting each other. Those types of mountains can't help but be inland.
Even a very, very new mountain like Mauna Loa on the Big Island of Hawaii has a narrow flattish "beach" -- basically, when eroded material hits the ocean, it slows down and forms a flattish area around sea level. Likewise lava hits the ocean and tends to stop. This comes pretty close, but only when they're young.
Another approach (if you don't demand ultra-high mountains) would be to have a high tableland which is eroded to form peaks separated by deep valleys. (Think the fjord country of Norway or Alaska.) These can go right to the ocean's edge.
Another approach -- again, the "mountains" are only a thousand or so feet high -- is when you have an island volcanic caldera which explodes, leaving sheer faces over the sea. (Think Santorini.)
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In my world, there is a chain of offshore volcanoes which are the result of a smaller plate hitting a larger one. There are two to three active volcanoes.
My question is: two of these volcanoes are close enough they are only separated by a narrow strait of sea, so would the volcanic activity from them, lava flows, hydrothermal vents, etc., be enough to turn the strait into a nearly boiling, seething sea of hot water? If not, what could? Or is this impossible?
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Highly unlikely.
For a practical demonstration, take a look at videos or pictures of pillow lavas being formed in Hawai'i. The divers are within meters of lava emerging into the water, and while the water in contact with the lava is clearly heated, the divers only a few meters away are in no immediate danger. An example:
[](https://i.stack.imgur.com/RQ96x.jpg)
In order to heat a sufficiently large mass of water between the volcanoes to boiling, there would need to be so much lava outflow that there very quickly wouldn't be any water at all, but built-up emerged land.
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Possible for a short time frame during an eruption event, but highly unlikely during a long time period.
little blurb I found through google on the cooling of lava:
<http://ffden-2.phys.uaf.edu/212_spring2005.web.dir/Philip_Fitzgerald/physics.htm>
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> The lava is assumed to be at 1000 degrees C and the water is assumed to be at 10 degrees C. The final temperature for the lava and the water is assumed to be 100 degrees C. These numbers are only approximate. The actual specific heat and latent heat of fusion for lava varies depending on the mineral composition. In his piece “Cooling the Lava”, John Mcphee gives a figure of 1.7 kg of lava cooled per 1 kg of water. My calculations show 2.7 kg of lava cooled per 1 kg of water.
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Water has a couple properties that leaves it quite unique in this space..it takes a lot of energy to warm up water compared to most other materials, including lava. You would need around twice as much lava as water to get the water up to a boiling point...and by that point the strait between your two volcanoes would be a filled land bridge.
The water has a lot of methods of cooling itself. The tide and ocean currents wouldn't leave the water in between two islands static (some of the strongest ocean currents exist between two islands)...it would be ever replaced as the current moves and the huge depth of the ocean has tons of room to absorb this warm water.
Wind also comes to play. As it blows over the surface, water evaporates. The act of evaporation for water takes an incredible amount of energy out of the surrounding environment (blowing on your hot coffee is the same principle). So the water at the surface would be consistently cooled.
It is possible to have these conditions right for a short term eruption event to increase water temperatures, but nothing that would be permanent over a month timeline. You could probably make a few alterations (isolate this water from the ocean) that could make this scenario a bit more likely.
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I agree with the previous answers in that lava coming out of an ordinary volcano could not do this. Unless you took Kilauea and multiplied it by 1000.
However, a possibility is to have a lava flood eruption something like Laki in Iceland whereby instead of lava coming out of the top (or vent) of an on-land volcano, you could have a massive, continuous fissure-type eruption in very shallow water. This could be combined with your two flanking volcanoes.
As an aside, I suggest you go to Wikipedia to look up "hypercane". A pretty scary cool concept.
Hope this helps.
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Geothermal activity other than lava flows could possibly provide your world with enough heated water and bubbling from escaping gases to present a warm body of water that has the appearance of boiling.
One place on earth that we see heated water bubbling and even gushing is Yellowstone. If your sea is shallow with a low flow of fresh water into the area you could have a warm to hot sea that has under water geysers and hot springs with escaping gases to look like it's boiling. Perhaps a few geysers blast enough boiling hot water to reach the surface so some areas will boil a person alive.
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While previous answers have explained that this isn't viable. Do remember it doesn't have to be boiling to be deadly. Much lower temperatures can still result in humans and fish being unable to enter the region. It may also be deadly for other reasons like the volcanoes increasing the acidity of the water
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I would like a realistic evolutionary path for non-hominid humanoids, but evolution is extremely complex and varied, so I will narrow the question to examining how evolution might occur in felines to produce a humanoid. I would like to start with the *Pseudaelurus* (a prehistoric cat) and move to an upright walking, fingered and toed omnivore (cat's are obligate, "true", carnivores). I think I have a reasonable idea for how to evolve their diet (included below for reference), but I'm stuck trying to come up with a reason for hominid like fingers and toes and upright walking. My question is, **what types of environmental/cultural/etc... changes could lead to a feline developing upright walking and hands capable of hominid like grasping?**
**Evolution of Diet:** Assuming the cats were native to a plains environment with ample hunting opportunities, an environmental shift (ocean's rising, tectonics, something else) could force the felines into a wooded environment with a much smaller number of prey. This would lead to adaptations for including fruits and other forest products into their diets. It would most likely also favor tree climbing adaptations like those seen in leopards.
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Moving to trees and/or a rocky area would help. Hands and an upright posture are good for reaching and carrying things. They are also good at manipulating things and tool use. An upright posture is also good for spotting predators.
What if the cats were driven out of the planes by larger predators and there where small wooded areas where small critters lived in the nooks and crannies of trees with deep bark ridges. The cats need to reach in and around to reach the prey. Eventually they would use sticks or hooks to grab prey and maybe tools to widen the holes.
They would have to cross the planes to reach new food sources. Being able to see over the tall grass while they moved would help avoid the predators. At first they would move and pop up to peek then move again. The longer they could look while walking, the better their survival chance.
Eventually they develop tools/weapons to help defend themselves against the larger predators. Then they use the weapons to drive of rivals since, without the predators, their population rises past the point the prey can support it.
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As far as I know the only large animals with grasping hands/paws are those that live in (or used to live in) trees. And reverse, the tree dwelling animals that I can think of off the top of my head are either flying, have grasping hands, or are small enough that they can use sticky feet (insects). Well except snakes that is. So the scientifically safest way might be to duplicate hominid evolution: have the felines move to the trees. I don't know what the scientific consensus is for why humans started to walk upright but if there is one you could probably adapt it too.
If the felines are still obligatory carnivore they wouldn't have started living in trees without food there, so either they already started eating fruits or there are other tree dwelling animals that they could hunt. At the same time on the ground there are larger predators that would eat the felines if they could.
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Theoretically, sometime between when our fishy ancestors crawled out of the ocean and the first recognizable primate swung from a tree branch, there had to be something that walked on four legs ending in paws and claws. Curiously, there's almost no data in an (admittedly rapid) Internet search that theorizes that happened before the chimp. Probably because there isn't any evidence of one species evolving into another species. But that's not really the focus of your question, anyway.
Therefore, I'm a fan of @ShadoCat's answer (and I upvoted it) because he's describing perfectly sensible adaptation. Paws elongate and rotate on the "wrist" to become "hands". The cats stand up as they need their hands for something more valuable than running. Etc.
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I'm trying to find some type of space weather or other natural occurrences that would result in the intensity of Earth's magnetic field dropping for a few hours to maybe a week or two at most. Polarity reversal doesn't work and I don't think I'm getting anywhere with solar flares.
Any ideas? I'm starting to get annoyed with how safe this planet is!
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There is no good answer according to modern Earth's magnetism theory - but then we don't know too much about Earth's magnetism.
According to the dynamo theory, Earth's magnetosphere is created by convection processes in the Earth's outer core. Those processes get disrupted from time to time, which results in [Geomagnetic excursion](https://en.wikipedia.org/wiki/Geomagnetic_excursion) or even [Geomagnetic reversal](https://en.wikipedia.org/wiki/Geomagnetic_reversal), but those disruptions take years, often hundreds of years to play out. There is no indication that convection can just stop for a few hours or even a few weeks.
But "no indication" does not mean that this is impossible. Maybe there is a way for the dynamo to get stopped that quickly. Either way, it should be caused by a process in Earth's interior. Any changes in cosmic weather just can't have any impact on the interior.
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Blame it on **Magnetic Reconnection**.
* It's natural. You are not inventing anything.
* It's not well understood, so you can fudge the specifics.
* It's the trigger for solar flares, so you can still use them.
* You can *probably* tailor a disaster for your narrative, [as hinted here](https://www.nature.com/nature/journal/v426/n6966/full/nature02084.html).
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> It is at present not known whether reconnection can happen in a continuous fashion or whether it is always intermittent. Solar flares and magnetospheric substorms — two phenomena believed to be initiated by reconnection — are highly burst-like occurrences, raising the possibility that the reconnection process is intrinsically intermittent, storing and releasing magnetic energy in an explosive and uncontrolled manner.
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In layman's terms, it's where [two or more magnetic fields push together and start sharing and rearranging their ion loops](https://en.wikipedia.org/wiki/Magnetic_reconnection). What was once a magnetic "barrier" layer between them is suddenly gone, like a rubberband snaps and the whole system has to rebalance.
[ESA has a page](http://sci.esa.int/cluster/51744-magnetic-reconnection-in-earth-s-magnetosphere/) on reconnection in the Earth's magnetic field (with an alarming 20sec animation that might give you ideas). [NASA also has a good page](https://www.nasa.gov/content/goddard/science-of-magnetic-reconnection) with video.
Your disaster might go something like:
1. Unusual sun activity leads to a magnetic "storm": a series of reconnection ripples.
2. The Earth's magnetopause is compromised as they hit faster than the magnetopause can recover.
3. Extra fireworks caused by solar plasma far deeper into the Earth's atmosphere and the turbulence from the reconnections themselves bring the magnetic storm to our front door.
4. "Aftershocks" as the system balances, ripple and dissipate through the magnetosphere, but also cause compression waves that can channel plasma in unpredictable ways.
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So diamonds are the hardest natural substance, but can be broken/shattered by impacts.
If a planet had a large mountain range made of diamond (maybe the size of the Rocky Mountains on Earth), would it erode at all? (This is the same system in [How close to a supernova can a planet retain an atmosphere?](https://worldbuilding.stackexchange.com/questions/53993/how-close-to-a-supernova-can-a-planet-retain-an-atmosphere) so the diamond mountains and general bizarre geology is because this planet started out as an ice giant, got burned down to a "chthonian planet" core, then got new oceans/atmosphere from a bunch of comets).
I'd like this to remain a barren and lifeless (and therefore traditionally feared & avoided) area, because no soil means no plants means no food sources and no real ecosystem, but would it work that way? Would windblown dust from elsewhere cause some soil to accumulate even if the mountains were un-erodable? Would lightning shatter the mountains enough to produce diamond-dust that could erode them further?
Or is the concept of diamond mountains just stupid? If so, is there another way to get a soilless *large* area? (It needs to cover at least a significant part of a continent and remain soilless/lifeless for thousands of years and preferably tens of thousands, so new volcanic rock won't work.)
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The mountains will erode, but very slowly. You don't have to worry about it for a very long time (talking billions of years here).
You will have a problem with dust/dirt, though, as windblown particles will accumulate on your diamond mountains over time, allowing plants to grow there. One thing that might help with this is to drastically increase the slope of the mountain compared to mountains on earth, and make the sides of the mountain roughly flat (don't ask me how this happened). This will result in dirt being more likely to slide off, and the layer of dirt may be too thin to grow anything besides a few mosses. This would also be a very interesting (read "impossible") mountain to climb. The leeward side of your mountain, however, would have very little dust (probably just a fine coating) and could be the area that everyone is afraid of.
Lightning will not erode your mountain, but it will set small portions of it on fire. Diamond burns at a temperature of approximately 700-1200 degrees Celsius (but it won't set your whole mountain on fire because diamonds don't produce much heat when they burn).
The only other way I can think of creating a large, soilless area, is a *wall* of diamond mountains, in a ring around the aforementioned area, with immense heights and no large drops between them to prevent most particles from being blown over the tops. You couldn't get into this valley in the center, so it probably won't work for you.
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## They will erode as fast as a normal mountain
Mountains are not significantly eroded by wind, and water uses whatever the mountain is made of as an abrasive. **Differential thermal expansion** will shatter it in no time. Water and ice will erode it as fast as any other mountain becasue they are using diamond grinding against diamond. Plus since the dust from this mountain would be basically pure carbon mixing with whatever else is around plants may well love it.
**but really you are overthinking this.**
Normal mountains can remain largely lifeless for tens of thousands of years with no problem, all you need is very little rain. The Grand Tetons, for instance, are millions of years old.
If you want large soilless expanses of flat ground then deserts are your answer, soil requires water. Some last for a long time, there are several places on earth that fit this. The Atacama Desert is a good example.
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Not stupid. Just... far beyond highly unlikely that much elemental carbon will be all together for the time it takes, at the high pressure needed, to rearrange carbon atoms into diamond. (There's a reason the largest terrestrial diamond ever found is a measly 22 ounces.)
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Sure: a salt lake.
[](https://i.stack.imgur.com/kyJUb.jpg)
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Not stupid, but misinformed.
Diamonds are very hard but are not very tough. You can break a diamond by dropping it, or by banging a pan against it. Seriously. Ask anyone who has ever damaged an engagement ring.
Hardness is an indicator of which materials can scratch or be scratched by a given material. Diamonds are the hardest material we know of. But what makes them hard also makes them brittle. They have practically zero elasticity. All the energy you put into a diamond goes into breaking it.
Mountains are formed by geological forces many orders of magnitude more powerful than what is used to cut a stone, so you wouldn't ever get even a small hill of it. If you have a large content of diamond in a substrate, it will more likely become a flat desert made of small diamonds and diamond dust.
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Another approach which has nothing to do with diamonds.
I have walked upon an area that was apparently both soilless and lifeless. (Although I'm sure both existed to some degree.) The recipe was simple: This was a plateau at around 15,000' up. Note that the temperature was chilly but not frigid (higher up was a snowcap, but not on the plateau) and there was always a strong wind.
We had seen our last bit of green at 13,000', we saw no macroscopic life (other than humans) until we returned to that point. The surface looked like someone had carefully paved it with rocks but it was solid. At the time I made no attempt to investigate it in detail, in hindsight I think sufficiently small particles were carted off by the wind.
Scale this up to the size you need. (Think Tibet but even higher.) Put some Everest-scale mountains to put a major rain shadow across the area.
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It's around 1895 and the British Isles have fallen to a communist uprising. Or sunk underwater. Or invaded by Germany or covered in ice or something. So the government, the Royal Family and a large part of the population has been successfully evacuated to the colonies. The Royal Navy is still intact and still the largest in the world. The British Empire is still the largest Empire in the world. But what I'm wondering is where would the capital be? Singapore? Ottawa?, Bombay?, Cape Town? And how much of a world power would the British Empire be without Britain?
The new capital should preferably be somewhere in a strategic position and not some isolated place just waiting to be annexed e.g. Gibraltar or Hong Kong.
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[](https://i.stack.imgur.com/Y98tD.jpg)
The choice of site might depend on why Britain fell.
If it was war then they might relocate to be with allies to continue participation - France was allied with Britain in the Crimean war and WW1 and would be a logical choice if they were allies again in this war.
If it was a domestic uprising and other European nations were at risk (which I think would be the case if Britain fell to communists) then Canada makes sense - adjacent to a strong ally not interested in annexation.
If the ice sheets are coming then not Canada and probably not France. India was the jewel in the crown of empire and toasty warm.
If it was zombie armageddon sweeping the continent and British Isles then I pick Iceland for its defensibility and proximity. And hospitality.
This answer is not going to make a lick of sense once you amend your question to specify the reason for the fall.
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Evacuation from the entire country would only be a very last resort. However it is a given in your story, so we will work from there.
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> It's around 1895 and the British Isles have fallen to a communist uprising. Or sunk underwater. Or invaded by Germany or covered in ice or something. So the government, the Royal Family and a large part of the population has been successfully evacuated to the colonies.
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* **Communist uprising**: I find it unlikely that communism would spread to such an extreme in Britain, given the mentality at the time and the pride in the empire. If the mindset of the people were such that this was possible I don't think the British would have been as successful in building an empire. Also I find it unlikely that the rest of Europe would stand by and let an influential power like Britain fall to communism - doing so would embolden communists in their countries too.
+ A second point on a communist uprising is that they may well attempt, once they have taken Britain, to take some of the colonies too - limiting our options of where to go.
* **Sunk underwater:** Well this one gets marks for being a clean slate, no enemies to think about just a "Well you just can't pick Britain anymore." However I'm not sure I need to point out how impossible is it for a whole country to just sink....but as stories go, you don't need everything to be believable.
* **Invaded by Germany:** Okay, so this could be possible (though Germany would strike closer to home in an initial attack, long supply routes through countries that may object to your war are expensive). However I don't think the British would leave/would be allowed to leave. You say you want a large part of the population to be evacuated but why would the Germans not just sink those ships? It is likely the British will be back for their country before too long.
* **Covered in ice:** Like sinking this has the benefit of being a magic wand we can wave and say we have no choice, however it is hard to see how the rest of Europe wouldn't suffer a similar fate (thus changing the whole dynamic of world power and making a prediction of where to go mostly guesswork).
**I'm going to assume we're taking the magic "Britain just isn't an option anymore"**
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> The Royal Navy is still intact and still the largest in the world. The British Empire is still the largest Empire in the world. But what I'm wondering is where would the capital be? Singapore? Ottawa?, Bombay?, Cape Town? And how much of a world power would the British Empire be without Britain?
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Here are the limitations as I see them:
* **Short journey:** There are a lot of reasons for this but primarily:
+ Disasters at sea aren't unheard of and transporting people, wealth and the monarchy across large distances increases this risk.
+ Pirates, think of that wealth again, it is likely some pirates (or other European powers) would attempt to take some of it.
+ Period of uncertainty - the months it would take to reach a new home would be time in which the colonies could become restless and revolt. A lot of the weight behind power would come from Britain itself. I suspect other European powers would like to spread word that the empire lost its home country.
* **A position we most want to keep:** It is likely that the Empire will see revolts as news of this loss spreads. We want, therefore, for the weight of the monarchy and the power that brings, to sit somewhere the Empire needs to keep.
* **Want to be central/close to Europe still:** The Americas were seen as a new world, separate from the rest of the world and would remove the Empire entirely from the European power play.
* **A country large enough to fit everyone in:** Malta or Gibralta are probably too small.
I can't seem to find any times given for a route between Britain and each of the colonies so going purely off distance I would say Egypt or India (though both routes offer tactical ambush points for pirates). These both satisfy the condition of being positions we want to keep. India was a hub of trade, used to British rule and tactically important for relations in the region. Egypt is home to the Suez canal - a real turning point the world trade.
I would, therefore, choose either Cairo or Bombay as the new capital. Whichever you choose has its own benefits. India has been used to British influence since the East Indies company in 1600 and was much less opposed to further rule than Egypt was. Integration here would have been much easier...however the flip side of this is that, if we choose Egypt India is more likely to stay within the Empire and the new influx of British people could turn the tide of Egyptian rebellion and thus retain the larger empire.
**I would choose Cairo, but there are so many factors it really depends how you want to play it.**
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Calcutta or Delhi.
They called India the jewel in the crown for a reason: it generated far more income than any of the other colonies. In a situation where the Empire is at risk of collapse, you want to hold on the the biggest asset, especially since the other ones have the same ethnic majority as the homeland, thus are less likely to leave.
So why Calcutta?
Well, it was the centre of the British Raj from Clive onwards until about 1920 when they moved to Delhi, the traditional capital of northern India. All the infrastructure of government was already there, so it would simply be a question of moving in.
Delhi would be a major contender, as it was historically been considered the centre of any north Indian empire for at least the last 800 years. Placing the capital there would be an announcement that the British were there to stay. The problem is that the Raj, unlike previous rulers kept themselves separate from the native population: colonists, not rulers. Placing the government in Delhi would only happen if the Raj were ready to "go native".
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I think evacuation would never be successful, British Empire was too widely dispersed, you couldn't move everyone to India for example without a strong home base supplying the move.
More likely scenario if it fell to communists is counterattacks until they were destroyed rather than meekly running away.
If somehow your scenario could evacuate then I think India would be their best base. It was a rich fertile land used to British rule with experienced and competent British Armies.
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*Editing this question to word it better.*
I don't know if it's a unique dilemma or a silly premise, but it looks like I need more guidance than I thought. I'm not a history buff and kingdom/state dynamics are all new to me, but I still wanted to have a go at it.
Although the setting takes place in the 19th century, the universe is quite fairy tale, so the reality is an alternate one with many liberties and laws that only apply to its fantasy kingdoms. It nonetheless mirrors much of the 1707 Act of Union for the creation of Great Britain:
Country A is on the brink of bankruptcy and, much like Scotland, hopes to be pulled up by the more powerful Country B on account of being plugged into Country B's economy, international trade, and the like. Country B is their only parachute; there are no other willing saviors. Country B is also quite kipper about having some dominance over Country A.
But it is possible for these economic aspects to be shared through a union that is NOT a political one that unites two kingdoms and their parliaments? Like an economic union (Benelex Union), some form of devolution, a dual monarchy, or a commonwealth?
Or is the best way to become economically stronger as part of Country B's economy a political union?
(Wince) I should add that there is a marriage involved between the two monarchs reigning in both fantasy countries, who reign under constitutional monarchies. Coregency/joint sovereignty were RL things depending on the countries <https://en.m.wikipedia.org/wiki/Coregency> (rare situation, though), and in most cases the queen still wasn't equal to her hubby, except perhaps in the case of Isabella of Castile and Ferdinand of Aragon (?) or Mary I and Phillip II (their contract suggests joint reign that suppressed Phil), but I know a unitary state has never occurred unless a child inherited both crowns. However, since Country B wants control of Country A's bank management and government spending, I don't know what kind of Union could grant that power unless it's a political union.
For some background, monarch A and B, both childless and threatened by bloodline extinctions, (if neither have legit kids their enemies will seize power) are NOT heads of government, so with or without the marriage, the economic desires above still apply.
So there are two deals to be secured, but because I'm iffy about whether a full-fledged U.K. is reasonable (even if this is fantasy), I wondered if any other unions could guarantee the same equal privileges as a political union in regards to the economy boost, bank control, and sharing trade partners and treaties with foreign powers.
If not, I guess I have to go with a political union if any of you would find that tolerable as a reader.
This scernario is still open for anyone to hop on. You guys have been brilliant so far!
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# It should be like the union of Castile and Aragon
The situation that might be closest to what you are talking about it the merger of Castile and Aragon with Isabella and Ferdinand. The two kingdoms were both among the largest in Europe. The only difference was that Isabella was not ruling when the marriage took place, so they had time to get accustomed to the idea that they were ruling together. Isabella was about a year older than Ferdinand and was 23 when she became queen. Ferdinand was already king of Sicily upon marriage and became king of Aragon five years after Isabella got her crown, in 1479.
Isabella's predecessor as monarch was Henry the Impotent, which says most of what needs to be said. When she came to the throne in a disputed succession, there was an immediate rebellion by her niece, Juana, who was daughter of the last King. She was conveniently married to the King of Portugal, so Castile was split down the middle in loyalties, with Aragon supporting Isabella and Portugal supporting Juana. Ferdinand, as Consort of Castile, led the Castillan armies and did a generally good job. His strong support for her probably cemented their marriage and political alliance, and they reigned very successfully for thirty-odd more years.
In general, Castile was the larger and more populous state, but had been ravaged by civil wars and rebellions for most of the past century. Aragon, on the other hand, was nearing then end of a century long Golden Age and at the height of its commercial prowess in the Mediterranean. It controlled southern Italy and Sicily (mostly), Corisca, Sardinia, and Malta. Barcelona and Valencia were large, rich cities, as were Naples and and Palermo in the Two Sicilies.
In short, Castile was large and populous, with lots of resources, but with no large cities and a surfeit of rebellious nobles, roving mercenary bands, and recalcitrant Moors. Aragon was probably just as populous, considering its overseas territories, and was one of if not the wealthiest Kingdoms in western Europe. It has lots of rich merchants, and close ties with the even richer merchants of Genoa, Milan, and Florence.
Incidentally, the Union worked out great, especially for Castile. The peace from Ferdinand's Aragonese army and stabilizing 40 year reign allowed population to boom, to the point that a generation later there were a surfeit of young adventurers ready to conquer the New World. Castillan manpower and military experience, plus Aragonese seafaring and monetary connections put the newly united Spain in the drivers seat for profiting off the New World, and made Spain the most powerful nation in Europe for the next 150 years.
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Well, this is a somewhat problematic situation. You see, if you want it to be based on real-world royalty and the like... then you are in for a shock.
Let's start with the trouble of royal lineage. To be considered a proper royal (and therefore a suitable partner), you had to be of royal blood--or at the very least of noble blood. That meant, either you marry your family, or you marry a foreigner.
In fact, in Europe and Tsarist Russia, it was quite common for royalty to marry the cousins, nieces, daughters, or granddaughters of other royals. This is why queens were expected to have so many children in those days--more sons to lead their country, more daughters to bargain off to other countries.
Note that it's far more common for a woman to be offered to another country. Some countries (England for example) would rather a reigning queen than a foreign king (Queen Elizabeth I is a prime example of this, though she'd refused to marry for a host of reasons, some of which were hinted at as being plausible sexual abuse. Check [this video](https://www.youtube.com/watch?v=XZfORjkZm3A) for background information on Elizabeth I and Mary, Queen of Scots, and [this one](https://www.youtube.com/watch?v=5zSyjyLAWWM) for how hereditary diseases spread through royal blood, which also shows how marriage often worked for royalty)
If this isn't enough information, you can always nose around in the BBC documentaries on the subject. There's always more going on behind the scenes, and two main players have always been the church and the politically snobbish. You may also wish to get into coming of age ceremonies of the time, and how this affects your two monarchs. I assure you, though, that a king marrying a queen is all but unheard of (unless I've missed something). They would be looking in the best interest of their kingdom, so unless the queen offers her hand in marriage to her would-be conqueror (Cleopatra to Marc-Anthony of Rome, for example, though I don't believe they'd wed), I don't see them joining quite in the way you imagine.
Trade partners, perhaps. Allies against a common threat, oh yeah. Unifying two kingdoms via marriage... not historically accurate as far as I am aware. Mary, Queen of Scots does offer a sort of halfway between, her son became king of Scotland, and also inherited the crown of England on Elizabeth's death, given she never married and had no heir. Beyond that? Beats me.
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If you're looking for something a little less radical than political union, you could have a go at an intermediary economic entity, roughly based on the East India Company. This company would be (very) large, able to hire its own security forces to keep the peace. Majority investment (and control) would be by B, with the goal of the company the development of A. With a large enough presence, the company could have a large impact on the functioning of A without overt political control by B.
Of course, this would need very careful political handling by both governments, and a certain amount of enrichment of B would certainly cause resentment in A. A very tricky balance (particularly in the PR field) would be necessary. And preventing the company from getting the bit between it teeth and actually supplanting the government of A would always be a problem. With economic power comes political power, and the temptation on the part of the company's directors would be intense. So you'd need considerable trust on the part of the government of A, while the government of B would need to have strong reasons to keep A healthy and independent.
This would clearly call for some creative writing on your part.
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Leaving dynastic issues aside, the *only* way to have merged taxation is through political union. By definition, only the state may impose taxes. Anything else is a loan or grant from one state to another, e.g., after WWII, the [Marshall Plan](https://en.wikipedia.org/wiki/Marshall_Plan) had the US give loans to rebuild (Western) Europe.
There are also things like the tithe system, in which the Roman Catholic Church collected taxes from officially independent kingdoms, as the successor of the Roman Empire, but without the title or responsibilities thereof. These are more legal fictions rather than anything you could legally repeat (normally).
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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.
In an effort to reduce the murder rate I want to greatly increase the chances of getting caught. To do so I invented a device that will record your last words (and potential the murderer's and your surroundings) that could provide key insights into your death.
This device would be a small chip inserted into the body. The chip would have a built in microphone measuring vibrations through your body produced by sound waves. The sound waves would be recorded into internal memory, small enough to hold just a ten minute loop (constantly overwritten). The device is powered by the circulatory system. When the person who has the chip implanted dies the chip is no longer provided power and thus the last 10 minutes are not overwritten. In the event of your death the chip could be pulled and listened too to give insight into your last moments, if no foul play is suspected the recording can be given to the family as a keepsake.
Is this invention technologically feasible? Can you power such a device using just the electricity produced by the body? Where in the body should it be to get the best recordings and power while being the least invasive? How big would the device be, classic CIA-eqse implant or more like a pacemaker? Finally, what kind of recordings could it get, would it only record your own voice as vibrations from your voice box would be strongest or could it pick up others talking to you? Would it sound like real voices?
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The chain of devices you need is: Microphone, pre-amp, processor, memory.
The microphone is easy. The CIA has been making odd sized microphones for years.
In [a paper](http://engineering.dartmouth.edu/analoglab/reapp/publications/iscas12.pdf) on low power microphones, researchers at Dartmouth designed a microphone pre-amp that consumes around 50uA. They did fabricate their device using 0.5um fabrication techniques, but they did not specify the size of the chip. Regardless, it should be quite small.
The 10 minutes of storage is tricky. If we use a simple processor that just shuffles the data from the pre-amp to memory, we'll need to store all of the data raw. The pre-amp above is specced for 4kHz sound, so we need 8kHz sampling. 8 bit audio will be fine, so that's 8000byte/sec, or 4.8Mb. On the other hand, if we ran a mp3 encoder, we could cram that data into 8Kbps mp3 streams, dropping our data needs to a mere 600kB.
We're going to need non-volatile memory, because the whole point is to store the last words. That means FLASH. The [SST25](http://ww1.microchip.com/downloads/en/DeviceDoc/25081A.pdf) series is a low-power FLASH memory chip. It turns out that the energy usage of flash is almost independent of the size of the chip, so we can use the same device for both .wav and .mp3 versions... no need to spec them out separately. This chip uses 8uA when idle, and 30mA when writing. Fortunately, we don't need to be writing at all times. We can write in bursts to minimize power usage. For the .wav version, we'll be running at approximately a 10% duty cycle, so the actual energy consumption would be 3mA. For the .mp3 version, we would be running at 1.5% duty cycle, consuming around 0.5mA. These chips run at 3V, so they consume 9mW and 1.5mW respectively.
The processor is really the make-or-break component. A [ENA2351](http://www.onsemi.com/pub_link/Collateral/ENA2351-D.PDF) MP3 encoder proudly announces:
>
> This product features a built-in
> hardwired MP3 encoder/decoder system, enabling the **industry’s lowest power consumption of 5mW**...
>
>
>
The difference between powering a large FLASH full of .wav and powering both a FLASH full of .mp3 and a converter is pretty small. It's the difference between 6.5mW and 9mW. Because I think converting to .mp3 is a lot of trouble and the benefits are small, it makes sense to downselect here and decide to just store .wav data.
For processors, we can look at ultra-low power processors like a [MSP430](http://www.ti.com/product/MSP430F423A). This little 8MHz processor sports the Analog to Digital converter we'll need to get data from the microphone preamp, and also sips power, consuming just 0.4mA at full power (at 3V == 1.2mA), but it also supports several low power modes that may be used to decrease this.
In the end, we're looking at around 11mW of power (10.25mW rounded up to cover all of the unusual bits)
11mW is not much power, as far as the human body goes. The human body is capable of expending 20,000 times that much. However, getting 11mW parasitically is tricky. So far tools like [TEGs](https://news.ncsu.edu/2016/09/wearable-teg-heat-harvesting-2016/), worn on the outside can generate 0.02mW/cm^2. [Enzymatic Fuel Cells](https://en.wikipedia.org/wiki/Enzymatic_biofuel_cell) inside the body are similarly on the microwatt range for power output.
You do have access to a lot of unusual power sources, of course. If you're implanting a microphone on a person, it makes some sense to couple to the diaphragm. You may be able to get your 11mW by hooking to the diaphragm in some manner and leveraging their breathing. They're guaranteed to be breathing all the way up to their death (or shortly before their death), so it's a very reliable source of power.
Other than this incompletely specified power source, everything I've described could be fabricated on one or two chips. Everything could go on one chip, system on a chip style, or you might keep the flash memory separate because it can be mass produced better that way.
As for what it would sound like, that's open. It depends *heavily* on where the microphone is. If you put it in the chest, you'll find that it sounds like a doctor's stethoscope listening to your breathing. You would probably want the microphone closer to the mouth to capture the phonemes as they are created. It most likely would not catch anyone else's voice because the dynamic range would be too great. Remember, your own voice is so loud that your brain unconsciously moves the bones of your ear further apart just before speaking. That's done so the sound of your own voice doesn't make you deaf.
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I'm designing a sentient, aquatic creature, and trying to decide how many eyes it should have.
This creatures biological strategy is one of redundancy - it has multiple mouths, multiple tentacles, multiple...well, lots of multiples of lots of things. I was thinking of giving it multiple relatively primitive eye-patches scattered across its 'head', but I also want it to have something close to human-level vision. I'm afraid I don't quite follow the quality differences between compound eyes vs complex eyes, so:
**Is it plausible for a creature with many small eyes to have vision as good as a human? If not, how good would each individual eye have to be to roughly match human sight?**
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@MichaelKjorling gives a good answer that should be expanded upon.
I'm guessing that you creature is an invertebrate since you mention it has "multiple tentacles" and imply that its 'head' is not a tradition head. It may be helpful to think about the evolutionary advantages for an animal with multiple methods of sight (and why we evolved sight in the first place). Why does an eagle need such great visual acuity? To see its prey from a great distance. Did you know [birds can't turn their eyes](http://superbeefy.com/can-birds-move-their-eyes/)? Its easiest to see where you're going with biological "blinders" built in. Why do fish have an eye on both sides of their head (yeah, yeah...except the flounder)? To see predators better. Did you know [deep sea fish tend to see more blue/green while fish in lakes are rivers see more red](http://onlinelibrary.wiley.com/doi/10.1111/j.1095-8649.2011.03130.x/abstract)? And sometimes you don't need any visual acuity at all. Sometimes you just need to know if something is between you and the light source, like an octopus that can [sense light/dark with its skin](http://phenomena.nationalgeographic.com/2015/05/20/octopuses-and-maybe-squid-can-sense-light-with-their-skin/). The eyes of dragonflies are [linked directly to their wings](http://www.pnas.org/content/110/2/696.full) to allow them to track prey without using any brain power. But in my opinion, the king-daddy of ocular evolution has to be the [Mantis Shrimp](http://www.businessinsider.com/the-mantis-shrimp-color-vision-system-2014-1). It has 12 different types of photo receptors (compared to our 3).
So thinking of your creature, perhaps it only has two "good" Mantis Shrimp-like eyes, but a multitude of other "eyes" that see varying degrees of detail or color. Its skin (which could sort of count as an eye) senses only light or dark so it knows when it is in hiding. Scattered around its body are numerous simple eyes that can sort of see. They're better than just sensing light/dark, but they lack a lens or mechanism for focusing so their main purpose is to grab the attention of better eyes when they detect something. The main eyes (2, 3, 5 whatever) would be like those of the Mantis Shrimp. These eyes would have numerous types of photoreceptors to see a broad spectrum of light as well as its polarization. Throw a couple on some retractable eye stalks since they will be the ones that use the most brain power and have the highest evolutionary cost (and therefore in need of the most protection), and you have a believable creature.
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**Edit:** Expanding on the idea of brainpower and evolutionary costs.
Have you seen any of the YouTube videos where [kids flip a bottle of water](https://www.youtube.com/watch?v=Sn9rtrQhJhA) and get it to land correctly (yeah, I don't get it either :/ )? What you don't see is the huge number of failed attempts they make before finally getting it. Nature does the same. There isn't any intelligence involved in evolution. Evolution is a series of mutations. Some mutations help the organism survive, and some don't. This is natural selection at work. "Oh, that extra rib prevented you from jumping out of the way and didn't stop the hawk from eating you once he caught you? Good thing it took those genes out of the gene pool."
The evolution of vision really exploded during the Cambrian period. Not coincidentally, body coloration (as camouflage, as a warning that "Hey, I'm poisonous!", or as a reproduction method "Hey, look at me! I'm sexy!") also exploded during that time. But this came at a cost. Senses take energy. A study of blind Mexican cave fish found that they use [5 to 15% less](http://advances.sciencemag.org/content/1/8/e1500363.full) of their metabolism by not having sight. And why have a circadian rhythm when there's no day/night cycle? [That's another big energy savings](http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0107877). Want to eat on cold days? That will cost [~50% of your metabolic energy](https://en.wikipedia.org/wiki/Energy_homeostasis). Chimps have something like twice as many glucose transporters in their muscles than we do which is why they are pound for pound stronger than a human (sorry, I can't find a link to back that up...just pulling it from a memory of an article I hope was factual). Somewhere on our evolutionary path, we "transferred" some of our glucose transporters from our muscles to our brains. Our ability to "out smart" other animals costs us about [20% of our caloric intake](https://www.scientificamerican.com/article/why-does-the-brain-need-s/). **Every** biological activity has a cost.
If you want to have lots and lots of biological activity (eg, multiple eyes, mouths, limbs, etc.), you either need to [eat A LOT](https://www.bing.com/search?q=how%20much%20does%20an%20elephant%20eat%20in%20a%20day), find [energy dense food](https://www.nutrition.org.uk/healthyliving/fuller/what-is-energy-density.html), or cut energy consumption in other areas. This known as the [Expensive Tissue Hypothesis](http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-84551997000100023). In a nutshell, the greater the evolutionary cost, the more energy it consumes. And if it consumes a lot of energy, it must be pretty vital to the survival of the organism. If it isn't vital to the survival of the animal, it will [eventually go away](https://en.wikipedia.org/wiki/Olfaction#Accessory_olfactory_system). Things that are vital for survival get protected: vital organs have a rib cage, the brain has a skull, eyes have lashes or eyelids or nictitating membranes, etc.
And finally coming back around to your creature. The simple light/dark sense of the skin doesn't require much on the order of brain power or metabolic energy (at least, I'm presuming it doesn't since this is the earliest "eye" in evolutionary terms). The simple eyes that can make out vague shapes can be wired directly to the mantis-eye stalks (thereby saving brain power) so that when they see "something", the eye stalks automatically swivel to gather details. This isn't very far fetched. Horseshoe crabs have two simple [eyes on their belly](https://en.m.wikipedia.org/wiki/Horseshoe_crab#/media/File%3AHorseshoe_crab_eyes.jpg) so they can see predators above them when they are swimming (because they swim upside down). In terms of your creature, I'm imaging a [species of octopi](http://www.pbs.org/wgbh/nova/nature/cephalapod-intelligence.html) that figures out how to cook food over thermal vents which in turns [leads to even larger brains](https://www.scientificamerican.com/article/cooking-up-bigger-brains/).
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I don't think there is any inherent reason why a large number of "eyes" would necessarily have to imply the downsides of compound eyes.
For an extreme example, you could consider each cone or rod in the human eye to be a separate organ. (Stay with me!) In the case of humans, they all share only two openings for the light to pass through, but there's little reason why it *has* to be that way.
Your creature could have a large area covered with rods and/or cones, and a large number of small openings to let light in and focus it on the rods and/or cones. This would resemble a grille more than it would resemble human eyes, but the basic biology could still be very similar.
The obvious downside seems to me to be that the creature would be highly vulnerable to physical trauma to that part of its body, much more so than creatures that only have a pair of eyes. This is because its skull would be comparatively weak in that area, as it cannot be particularly thick without restricting the creature to a particular field of vision. An adaptation in the direction of reinforcing the skull could visually resemble something like a [VISOR](http://memory-alpha.wikia.com/wiki/VISOR), only integrated into the skull instead of outside of it.
I'm at a loss to explain how something like that would *evolve* in a natural setting, but...
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Why has this creature so many redundancies? That should only evolve through harsh life circumstances, many enemies (own species, predators if the creature is prey or dangerous prey if the creature is a predator).
if you can answer why the creature has redundacies, you can answer the "eye question"
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So, this one's probably for those ones with a bit of knowledge of economic history. I'm wondering what events tend to trigger the formation of a royal mint in a society so that a country might start manufacturing coinage and how they protect their coin values against nearby economies and counterfeiting. This isn't an exhaustive question though, since I'm sure some individuals could talk till the cows come home.
Edit: Time period. Obviously this depends on nation, but ideally earliest possible. Coinage has been around since the ancient eras during the byzantine and early roman empires Pre-BC. So maybe between 4000 BC and 0 BC? If you think there was a more interesting time use that.
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## A universally accepted commodity
For coins to appear the society must first reach a stage where there is a universally accepted commodity.
In the beginning trade was done in the form of [*barter*](https://en.wikipedia.org/wiki/Barter), that is, goods and services were exchanged directly for other goods and services. Barter is inefficient. For example, suppose that a person P has three dozen eggs and wants two cubits of cloth. They must find another person who has cloth and wants eggs. If there is no person who has cloth and wants eggs, they must inquire what do the cloth-having persons want? Maybe a person Q has cloth and wants amphoras. So now person P must find a person R who has amphoras and wants eggs, so they can exchange the eggs for amphoras and then go and exchange the amphoras for cloth. Barter slows down trade considerably.
During the [Late Bronze Age](https://en.wikipedia.org/wiki/Bronze_Age) the civilizations in the eastern Mediterranean and the Levant reached the stage where trade began to use a generally accepted commodity, in the form of metal -- initially iron, copper or bronze. Everybody accepted metal, by weight, and trade was considerably simplified; for example, see the Greek [*obols*](https://en.wikipedia.org/wiki/Obol_(coin)), which were originally spits of copper or bronze traded by weight. The use of iron, copper or bronze as a generally accepted commodity was a great progress, but it was still inefficient because these metals are quite common and therefore traders needed to carry large amounts of them.
## Standardized pieces
The next step forward was to use rarer metals -- silver and gold -- as a generally accepted commodity. In his *Histories*, Herodotus writes that the [Lydians](https://en.wikipedia.org/wiki/Lydia), a people in what we call today western Anatolia, "*were the first men whom we know who coined and used gold and silver currency, and they were the first to sell by retail*" ([Histories, book I, chapter 94](http://www.perseus.tufts.edu/hopper/text?doc=Perseus:text:1999.01.0126:book=1:chapter=94), trans. A. D. Godley). The advantage of using standardized pieces is that they can be *counted*, eliminating the need to assay them and weigh them, thus facilitating trade. Coins were invented roughly simultaneously in the Mediterranean, India and China; the oldest Lydian coins date from the late seventh - early sixth century BCE.
From the physical coins -- standardized pieces of metal -- came the idea of an abstract unit of value, laying the foundations for *accounting* and enabling the states to set up efficient *taxation*.
## Centralized mints
Since coins were so much more convenient than using metals by weight, the states, be they kingdoms or republics, found a great source of revenue. They established centralized mints and required that metal be converted into coins only in the state mints; the mints charged a fee for this service ([seigniorage](https://en.wikipedia.org/wiki/Seigniorage)). The coins made in the state mints were stamped with state symbols, guaranteeing their weight and purity.
As an aside, the first Roman mint was set up in the temple of Iuno [Moneta](https://en.wikipedia.org/wiki/Moneta) (Juno the Mindful); from the Latin words *moneta* and *monetalis* comes the English word monetary, and indirectly the words money and mint.
## Counterfeiting and further consequences
With the invention of coins came counterfeiting -- see a [gallery](http://augustuscoins.com/ed/imit/) of ancient counterfeit and imitation coins. With counterfeiting came a need to detect and apprehend counterfeiters, and a need to assay the coins accepted in trade. The ancients used various methods to assay the purity of coins, for example [touchstones](https://en.wikipedia.org/wiki/Touchstone_(assaying_tool)) and measurements of [density](https://en.wikipedia.org/wiki/Eureka_(word)).
Since each and every little city state made its own coins, a need appeared for professionals who specialized in exchanging one kind of coin for another.
Once the minting of coins became a state monopoly rulers naturally found that they could increase their apparent revenue and purchasing power by minting coins with less precious metal in them than their face value; the unfortunate consequences of [debasement](https://en.wikipedia.org/wiki/Debasement) are endlessly met with in history from the Antiquity to the Modern age, up until commodity money was replaced with fiat money (and debasement was replaced by inflation).
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From a slightly different angle, it wasn't royalty or nations that created the first non-commodity money - it was the Knights Templar. They would store gold for you, and then give you a letter of credit, which could be taken to any branch of the Knights anywhere and redeemed for gold. It was much easier to carry the letters of credit than to carry the actual gold.
Noble houses, including royalty, made use of this service, and also borrowed from the Knights. Effectively, the Knights TEmplar became the world's first bankers.
In 1306, the French crown, which had become heavily indebted to the Knights, accused them of heresy, raided the temples, executed many of the Knights, and took the gold that was stored there. Effectively, King Philip of France was the world's first bank robber.
However, these notes of credit were not fiat money, but "representative money" because they were still backed by actual gold. The first recorded use of [fiat money](https://en.wikipedia.org/wiki/Fiat_money) (it is valuable because our ruler says to treat it as valuable) was in China, around the 10th or 11th century.
European nations started to experiment with fiat currency in the 17th century, most experiments being brief (to cover a period of time when gold and silver were scarce) and/or unsuccessful (the currency's value rapidly declined to zero).
Protecting the value of coins has always been a problem - [debasement](https://en.wikipedia.org/wiki/Debasement) of commodity coinage since coins were invented, as well as counterfeiting. This is why commodity coins were generally treated as scrap metal, not taken at face value, once they left their home jurisdiction.
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I'm going to keep this short and ignore all issues of counterfeiting.
First you have to consider the two types of money
* commodity money
* fiat money
Commodity money has value regardless of whose head is on it, which means you only need a royal mint when your country develops a sense of national identity or your monarch gets a bit of ego under him and wants his own head on the coins. Commodity money is better for trade caravans moving casually between countries, city states and other miscellaneous fiefdoms. They're basically accepting a weight of gold or silver rather than a number of coins.
Once you reach fiat money then you have to have a royal/national mint, the value of the money is entirely based on whose head is on it.
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Well, it starts with the concept of money. Why do we need/use money?
We use money as a store of value, as in, it won't lose value if we keep it. So, the money I earn from selling my harvest this year will not lose value when I want to buy seed next year. This saves me the trouble of sorting out seed from my harvest, and I can just sell in bulk, making things easier for everyone.
So what do I want from money?
It must be durable, following from its function; generally acceptable, if people don't think much of my money, it's worthless; portable, i.e., have sufficient value compared to it's bulk, that it's worth carrying around (though, there are classical counterexamples to this); divisible, to allow me to use part of my savings without affecting the value of the rest; and most importantly, in limited supply, so that the amount doesn't rapidly change and destabilize the market (see Zimbabwe's recent economic history). The last also has another aspect we'll discuss further on.
Now that we know what money is, and what we want from it, what do we use as money? Organics are (mostly) right out; they decay. The same with most common metals. Ceramics and glass came comparatively later. In fact, the value of precious metals and stones come from the fact that they were extracted very early in human history and the annual addition to the economy was limited. It persisted because they were, basically, useless. Copper had some use, e.g., in bronze and brass making, and was comparatively abundant, so formed the basis of the lower denominations of coins.
So, now you've got precious metals and stones for trading, now what? Stones aren't divisible, so they're not much use as general currency. That leaves metals. Metals are excellent commodities: one gram of gold is the same as any other, and half a gram is worth exactly half of one gram as you can pair it with any other half-gram to get one gram. Great...except that you now have to weigh your gold for every transaction, and if you're using gold dust, then you have to make sure your wealth isn't flying away. That means an air tight environment, free of contaminants, polished scales that gold dust won't stick to... in a society that thinks bronze is cutting edge stuff. This, while also dealing with things like tampered weights and uneven balances and the usual shenanigans.
The solution? Standardised weights of metal, in easily usable and recognizable shapes and sizes. The next problem? People cheat. One merchant stamping coins adds 10 mg of cheap impurity in each coin or makes his coins lighter by10 mg. He gets one coin extra out of every 100, but now, all the coins he releases into the market are impure. Eventually, people figure it out. They don't know who exactly is responsible, but they can figure out roughly where they came from. They then boycott the place. The crooked merchant gains temporarily, but everyone loses.
The people in the area figure out what's going on and everyone starts putting their own mark on the coins they mint in order to guarantee that they'll stand behind them. It works, until someone starts making coins with fake marks that nobody claims, or using other people's marks. Again, traders from other places refuse to do business with them, since they'll have to track down the maker of every coin to verify that they made these or test each coin themselves.
The eventual solution, get the guy running the place to make the coins. Everybody knows who he is and where to find him, and anyone looking to counterfeit his coins is going to have to explain themselves to some large men with pointy sticks and no sense of humour. And since, unlike individual merchants, the ruler has to mint a massive amount of coins, he needs a bigger mint and more security, due to the larger amounts of gold involved. Hence, a royal mint. This would probably show up within a hundred years or so of coinage.
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How is it possible to have a habitable planet where there are patterns of light and dark so erratic, it almost seems random (with a leaning towards greater periods of darkness than light)?
For example, you might have several hours of light followed by 20 hours of night, 5 hours of dawn, 10 hours of weak daylight, and then 3 hours of night, 12 hours of strong daylight, followed by 54 hours of darkest night?
What manner of strange things could be in a solar system to produce such erratic day/night periods? What "things vast enough" can block the main source/s of light?
Follow-Up Edits
\* Firstly, thank you for the welcomes; very much appreciated along with the responses.
Context of Question: For a fantasy world (read with Magic) more than Hard Sci-fi. This is more because I lack the astro-mathematical talent, have an interesting idea, but need to make sure it will pass casual muster.
Zxyrra - Re: seemingly random
I suppose what I am seeking is a pattern so complex that it could not be correctly predicted in the mid to long term; even by a fairly sophisticated civilisation. It becomes a phenomenon where scholars, priests, prophets, and the everyday person all have different perspectives on what will happen. By saying "seemingly random", I suppose I am looking to lean upon a lack of certainty.
Thank you for the link: I am a fan of GRRM's world. :)
Mikey - Re: temporary/stable
I had not looked to pin this down in my mind; but I suppose having it as a several-centuries old phenomena creates an interesting tie-in with other aspects of the setting.
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Here are some thoughts to consider:
1- Very thick clouds. Also, several layers of clouds instead of just one layer. These would block the sunlight enough to create an artificial night.
2- A lot of moons. Large sized ones. Also they ought to be located at great distances from the parent planet so that their orbital velocities are quite low. Thus making solar eclipses quite the more likely, and also making them last much longer, since the eclipsing moon would take longer to move away.
3- Consider making it a binary planet system so that the other planet would also have its share in eclipsing the parent star and adding more to the night time.
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A binary moon system where the moons are planet sized objects orbiting, for example, a gas giant planet. Also, if the two moons have extreme inclinations with respect to their planetary system's primary star(s). The possible plurality for the primary star includes the possibility that instead of a single primary star if there is a close binary star at the centre of the system.
This proposed system of a binary moon with a highly inclined orbit to its primary star or possible binary star pair, and which orbits a gas giant. A planet in this system will experience a complicated and continuously shifting day and night cycle. The variably between day and night wouldn't random, but it will complicated and changing all the time. Presumably, the pattern of days and nights will repeat, but this may take place over a long period.
This is more of a conceptual model for a planet with erratic day-night cycles. Whether such a system would be gravitationally stable is an open question. It wouldn't be surprising if someone with better knowledge of orbital mechanics demonstrated this complex system would come crashing down.
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Remains of incomplete [Dyson sphere](https://en.wikipedia.org/wiki/Dyson_sphere) left by advanced civilization inhabiting the planet some millions years ago, but died out, or alien civilization who just stopped by to harvest the star.
Several huge "chunks" of stuff eclipsing the sun, combined with natural day and night cycle, should "seem random" up until your civilizations fashions a telescope fit for solar observation.
It's somewhat more likely in a world "with Magic", and possibly adds fun plot element. "Aliens" can easily be replaced with visitors from other dimension, as long as they enjoy star energy.
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Chaotic tumbling instead of rotation on an axis. This is literally what you describe! The sun may rise from any point on the horizon, and can’t even be predicted very far ahead.
This is a real thing. See, most famously (for being the first to be seen doing this), [Hyperion](https://en.wikipedia.org/wiki/Hyperion_(moon)).
What you need is to set the stage for [unstable axis of rotation](https://en.wikipedia.org/wiki/Tennis_racket_theorem) by having three distinct principal moments of inertia.
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This is reminiscent of George R. R. Martin's scheme of plurianual seasons - just, instead of "the Winter is coming", the Starks would say "the Night is coming"...
A truly random pattern requires magical explanations. The rotational speed of the planet is variable, which is physically impossible, so magic (or some futurish sounding pseudo-science) is required. Unless it isn't a planet, but an asteroid of irregular shape, as implied in JDługosz's answer, in which case it isn't likely to be habitable - if it doesn't collapse into a sphere it also won't be able to retain an atmosphere.
Other solutions will give you complex, but predictable, patterns of light and shade: big or many moons, elongated orbits, huge or variable axial tilt, a huge gas giant between the planet and its sun... or the planet itself being a satellite of a gas giant. Elongated orbits, or out-of-the-planetary-plane orbits may help (imagine that the planet has a big moon that orbits ir perpendicularly to the planet's orbit around its sun, for instance), strong and quick precession or nutation. Or the central star could have different light intensity in each of its sides. Perhaps it has a dark side... These solutions, however, have the unfortunate feature of implying long periods of darkness, not exactly compatible with what we would ordinarily call a "day".
I am not sure that a planet with an extremely irregular pattern of light and shade will be able to originat life, though. The base of the ecosystem has to somehow produce energy without predating other living beings. The obvious source for that is solar energy, with other sources (geothermal, basically) being too feeble to sustain a complex ecosystem. If sunlight isn't plenty, it may be impossible to sustain such an ecosystem, too. Plus, extended periods of dark are also extended periods of cold; if those are too long, water may freeze worldwide; conversely, extended periods of light are extended periods of heath, which could cause water to boil, or, even at lower temperatures, proteins to denaturate.
Evidently you can handwave all those problems away, or invent magical or complex pseudo-scientific explanations.
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I'm trying to envision a human colony on a planet called Imot, which orbits in the habitable zone of a Red Dwarf star. Imot is similar to Earth though somewhat larger, and has strong magnetic field to protect itself from the stellar wind. Its year lasts 20 days and has a large moon that orbits it on a distance of 100,000 km.
My problems are the flares, the parent star flares nearly every day and some of the flares are very [nasty](http://www.space.com/27304-x100-000-flare-unleashed-by-nearby-red-dwarf-video.html). Since the planet's obliquity is 90 degrees there is no place to hide.
How to protect human colonists from the flares?
**PLEASE NOTE**
As the Imot's obliquity is 90 degrees, it is not and cannot be tidally locked.
See my question answers on [astronomy](https://astronomy.stackexchange.com/questions/19039/is-there-any-way-for-a-planet-orbiting-a-red-dwarf-in-the-habitable-zone-to-not) and this video [especially](https://www.youtube.com/watch?v=8_XQ_wSmg2s).
>
> [Yes](https://astronomy.stackexchange.com/a/19042/14829): It has a companion planet or an excessively large moon, with the
> two bodies orbiting their common center of mass (much like Earth and
> Moon). They may be tisdally-locked to each other, but they cannot be
> tidally-locked to their star.
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If some kind of warning system is possible human's could temporarily go to a shelter.
Crops are the other problem, they need to be outside.
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## There are a Few Options
**A) Move around the planet**
[](https://i.stack.imgur.com/SPy9X.jpg)
While this is the least energy efficient - and a somewhat strange - option, you could move your colony around the planet throughout the year in such a way that they are always on the border between the light and dark parts of the planet. They will get a decent amount of light, comparable to sunrise or sunset, but they will be least affected by solar flares.
This would be most efficient if your colony orbits the planet, or if there is an ocean large enough for a floating colony to navigate the seas throughout the year.
**B) Settle underground**
See [this poster](http://www.nationalgeographic.com/magazine/2016/11/exploring-mars-supplement-poster/) from National Geographic for a visual of what a colony might look like
>
> Lava tubes are cave-like conduits formed underground by cooled, hardened lava
> after molten rock has flowed through. Scientists say the ones on Mars may be
> significantly larger than those on Earth. The interiors of the Martian tubes,
> hidden under dozens of feet of solid rock, are protected from cosmic and solar
> radiation and fluctuating temperatures on the harsh, dusty surface.
>
>
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If your future colonist analyze the structures below the surface, using something like [this](http://mars.nasa.gov/mro/mission/instruments/sharad/), they may find lava tubes perfectly suited for colonies! And if not - they can still dig to a reasonable depth where radiation won't cause problems.
**C) Use radiation shielding**
Scientists have proposed [numerous strategies](http://www.space.com/21813-mars-one-colony-space-radiation.html) that would allow your colonists to build above ground - it just might not be pretty. Consider coating all structures in six feet of soil, or adding thick metal plates - it doesn't take a lot to match the protection an atmosphere gives once you have a magnetic field - and voila! Earth-like protection.
**D) Use artificial magnetic fields**
If your colonists want to live above ground, in the sunlight, without thick plating, and stay in once place, this is your final option. It is plausible that by the time your colonists arrive, humans will have figured out how to make [cheap magnetic fields](http://physicsworld.com/cws/article/news/2008/nov/06/magnetic-shield-could-protect-spacecraft) - which, if strong enough, are all you need to keep out the radiation from flares.
Also note that if you want **croups outside the colony, on the surface,** this method would work best.
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The people are easy, dig down. Not all that different than tornado country. The people can either live in tunnels dug underground or surface buildings covered in regolith, rock actually makes a fairly effective radiation shield. Alternatively if the flares give some warning they could build flare shelters similar to tornado shelters and just run to them whenever the siren goes off. Note shielded vehicles will be very important in this scenario since they will put them away from shelter whenever used.
compare this list of how much material is needed to halve incoming radiation.
[](https://i.stack.imgur.com/GNoql.gif)
Protecting the crops is hard because they need sunlight, so they have to be exposed to the sun. You have two options here. direct and indirect sunlight.
You can use solar panels on the surface to power underground lights for growing fields, you will however need a lot more solar panel acreage than growing acreage. It is also a very material intensive form of growing, since all your production needs to be dug out. you could do this with shielded(lead lined) surface buildings but your acreage gets even bigger, but your cost will be lower.
The alternative here is surface greenhouses with collapsible/retractable shielding, likely some kind of lead shutter that closes over the greenhouse, this of course works better with an early warning system otherwise your plants are still getting a dose. In both cases hydroponics or some other high density growing system will help make it more efficient. The crops use the stars light to grow making this the most energy efficient method.
this [site](http://www.radprocalculator.com/Gamma.aspx) will help with any shielding calculations.
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How about dig a cave/tunnel a safe distance underground? Possibly combining that with an EM generator if needed.
More details requested:
This is an example of what I am talking about. Here where I live there is a frost line, which is basically anything deeper than roughly 4' down will never freeze. Some areas of the world its a bit deeper.
The same concept applies here. The surface will be bombarded, but it will only penetrate the ground to a certain depth. Add a bit of margin for error, and dig a tunnel deeper and you will be safe.
Not knowing the exact impact force, intensity, composition of the planet, and etc means a depth can only be guested at. Depending on all of these conditions a tunnel less than 30 feet deep might be fine.
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The planet is likely to be tidally-locked, which would create a dichotomy between the hemispheres. That could make it an "Eyeball planet" (see [here](https://planetplanet.net/2014/10/07/real-life-sci-fi-world-2-the-hot-eyeball-planet/)). There are several different flavors of Eyeball planets (see [here](http://nautil.us/blog/forget-earth_likewell-first-find-aliens-on-eyeball-planets)): the best place for life can be along the terminator (in permanent sunset/sunrise) or the illuminated or dark sides depending on the planet's atmosphere and water content (see [here](http://nautil.us/blog/our-nearest-star-has-a-planet-and-these-are-the-ways-it-could-be-habitable) for the example of Proxima).
[](https://i.stack.imgur.com/ssaIV.jpg)
For your planet, people could most easily protect themselves by either moving out of the sunlit side, hiding in caves. Beware also that the science of how flares affect planets is very thin. We really don't know whether they are as dangerous as the news articles suggest. The early Sun had a lot of flares and outbursts but Earth seems to have survived okay. Of course, we don't know what things were like back then.
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I don't believe this setting gonna work, in order for the orbit to be 20 days the star has to be 18% of the Sun mass, anything less then 30% of the Sun's mass and the planet becomes tidal Venus <https://arxiv.org/abs/1203.5104>
I really doubt that planet so close could protect its atmosphere from such flares. Maybe some freakishly strong magnetic field could do it, but that opens another can of worms, with trapping the charged particles like [Jupiter](http://lasp.colorado.edu/education/outerplanets/giantplanets_magnetospheres.php)
And if you plan to wait for red dwarf to calm down, you gonna wait for a long time.
I would go with an Orange dwarf which is somewhat larger 45% of the Sun masses but avoids red dwarf habitability issues.
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As long as the magnetic field is strong enough to hold the atmosphere in the face of such heavy bombardment you only have to worry about direct radiation, an Earth-like atmosphere will absorb the bulk of the Gamma, UV and X-rays and a lot of Infrared too but all the Radio and most of the Microwaves are still going to get through to the surface. You need an optically transparent Radio and Microwave absorber, it can absorb the green part of the visible spectrum too because plants don't use that light anyway. It turns out that plastics are good Radio and Microwave blockers/absorbers so thick Perspex on huge "greenhouses" may be enough to shield crops and livestock that can't be sheltered underground from high radiation levels, if you want to follow a sedentary lifestyle model, Zxyrra's Option A, mobile civilisation, is perfectly good too.
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I'm designing a "adaptive" humans where repeated physical contact, skin on skin or exchange of bodily fluids, over prolonged period affects the development of the individuals.
The effect I want to achieve is that people who are in extensive physical contact for a quite a long time adapt their physical look and behavior, sort of like the funny pictures where old couples start to look like each other. The change is not very large but it's large enough to be noticeable.
For example imagine a couple that just started dating, where a man is a gym rat who only reads the sports section & woman loves foreign cultures and never lifted anything heavy in her life.
Within a few months man will start to feel strange affection in reading Nepal and woman would't understand how she survived her life so far without going to fitness club. If they broke up the effects will fade in few months, if they stay for a few years the effects will become permanent.
I'm not talking about pretending that you like something, they're starting to really like it.
I want to explain it with some mechanism that already exists in the animal world and could plausibly work on "humans". I know that human semen has [antidepressant effect](https://www.newscientist.com/article/mg22730313-500-semen-has-controlling-power-over-female-genes-and-behaviour/). Ants & Termites use pheromones but that seems far fetched for humans, since they live in colonies. Is there anything similar from our closer relatives where there are two fertile sexes, preferably mammals?
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AS mentioned, humans are ALREADY affecting their partners with pheromones, or at least the pheromones are enabling an initial attraction to create partnerships in the first place. There is some data suggesting that women [can detect incompatible mates](https://en.wikipedia.org/wiki/Body_odour_and_sexual_attraction) and that this mechanism can be [blunted by birth control pills](https://www.scientificamerican.com/article/birth-control-pills-affect-womens-taste/) so there already exists a mechanism to at least pre-screen mates for certain traits.
Now, how to affect change over time? Secreting hormones that are absorbed by the partner (or anyone in prolonged physical contact) is possible. But it seems unlikely that this could be so specific as to engender a love of cycling or theater. What is more likely is that the effect simply promotes a desire to emulate the other person, what they like you now like. This way you don't need a thousand different hormones to promote a bunch of specific actions, just a generalized effect that has a reliable ability to cause two people to converge in their interests.
If you wanted to get a little crazy, you could have each person affect the other via epigenetics, i.e. up or down regulating gene expression without affecting the DNA itself. So an athletic woman causes her mate to have increased testosterone, which leads to increased athletic performance, for example. But this implies a lot of very selective and specific manipulation for desired traits and seems unlikely.
Anyway, this effect should be limited in range and require prolonged intimate contact. So scent based mode of transmission is probably out, as is sweat based, since handshaking would spread it around. Saliva is a possibility, but if this is really intended for mating pairs, then vaginal secretions and seminal fluid are the best bet. Barrier contraceptives would blunt this effect, but since those are VERY recent technological developments it could have evolved free of such issues. The hormone is secreted and absorbed through the skin (hormones such as estradiol and testosterone are easily absorbed in this manner) during intercourse and then affects the pairs, pulling them together through mutual bonding activities.
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The way we as humans perceive reality is subject to constant change, as long as we continue being exposed to new ideas. Now there's a few ways I can think of that would increase the degree to which this is happening:
The first one would be the release of hormones, especially Oxytocin. If your fictional people were to be exposed to higher than normal rates of it, they could willingly become a lot more conformist than is natural. It could be introduced as a socially acceptable drug ("why wouldn't you use this spray, don't you love me???") or even as an engineered "dysfunction" in these humans' bodies (organs overproducing). Check out this study for more info: <http://pss.sagepub.com/content/early/2012/09/18/0956797612446026.abstract?rss=1>
The other one could be the notion of these people having no real way out of a relationship and being "imprisoned" in it by social/legal frameworks. Under these circumstances, maintaining a working relationship and at least sharing interest in the partners hobbies/passions will be a primary objective of their subconscious. Watch this TED talk starting at 5 minutes and you'll see what I mean: <https://www.ted.com/talks/dan_gilbert_asks_why_are_we_happy>
By sharing enough interests and conforming to each others respective ways of lifestyle (sports, diet, interest in fashion, etc.) people will automatically also start appearing more similar to one another.
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The human body is surrounded by an electromagnetic field, which varies based on mental and emotional activity. It wouldn't be much of a stretch to suppose that when these fields intersect, the more aligned they are, the more pleasurable the experience.
This means that the more two people spend time together, the more they will come to think and feel alike. It wouldn't be instant, because you would need repeated rewards over a period of time to make the new thought or feeling into the dominant one.
The more time two people spent in close physical proximity, the greater the effect would be.
Just as people vary in their conscious awareness of empathy now, you could have individual variation in how adaptable people are to the fields of others. Some people might find a way to block the process completely (especially if they had childhood trauma). They would be effectively blind/deaf in this realm. They might notice the effect happening in other people, and be puzzled about why. People would be uncomfortable around them, because they wouldn't respond, even slightly, to the fields of people around them.
For most people, the process would be completely unconscious, except for some awareness of pleasure/pain when agreeing/disagreeing.
A few might be fully conscious of the process, and may even use it to manipulate others.
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If I were to attempt the colonization of a planet *with preexisting life*, how would I manage to pinpoint a candidate planet from the comforts of Earth's orbit? I am interested in the stars somewhere within 40 light years from Earth, and with relatively realistic technology (no FTL drives or time machines).
I am familiar with the technology behind spectrography, but it seems rather unreliable in terms of launching a multi trillion dollar mission. [This](http://www.spacetelescope.org/news/heic0403/) suggests` that quite a few gasses that are correlated with life on Earth might not indicate life on exoplanets- so, how can we be certain enough of life to send thousands of colonists to a distant star?
* Really big telescopes?
* Spectography?
Different from [this question](https://worldbuilding.stackexchange.com/questions/17775/how-might-you-detect-a-life-sign), in that I'm asking about a much larger scale, and not trying to comprehend a trope.
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You can detect what kind of gases the athmosphere consists of, if you use the so called transit method to research them. That method is up to now the most successful in finding exoplanets by far. And that is how it works:
You simply measure how bright a star is. If a planet orbits a star, it sometimes might happens to be exactly between the star and earth. In that case it darkens the star by a tiny margin, but enought to detect the planet.
A small part of the star is not darkened by the planet itself but by its atmosphere. If you have a very sophisticated telescope you can detect that. You have simply to use spectroscopy and do some math to calculate what you might find there.
While there are a lot of gases that can occur by geologic activity, there are some that are known to be produced only by living organisms. If you find even the slightest hint of one of those, you know there is live.
Remark: Up to now (October 2016) this hasn't been done successfully with exoplanets but some telescopes are being build to do exactly this. It's quite possible that between 2020 and 2030 we get the first evidence of life.
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**You send a probe.**
Either an ultra-fast fly-by probe that just sends sensor data and images back to Earth or you send a slower but more intelligent Orbiter and Lander combo.
See Mars for more info.
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If temperature, radiation levels and water are OK, and you find a high oxygen level, then it is safe to assume some sort of life.
Oxygen can be present without life, but not to >10%, and not on a planet that has an average of 25°C, water, and is not radiation hell due to an unstable mother star.
Don't be to excited: Could be the only thing you finde are rocks coated with a thin, slimy cover of alien cyanobacteria. ;-)
There is a readymade plan for a space-based coronagraph that could easily take the necessary spectra. NASA didn't (yet) like the plan, because it requires an extra satellite which is flown at a distance of kilometres from the telescope in the direction of the target. So it eats a lot of fuel and doesn't last very long. ;-)
Bit more sci-fi? Google for the "exo earth imager".
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You need several probes.
Spectrography gives only few information about elements in the atmosphere, but to be survivable, other measures are important:
* radiation from the star (do the planet have magnetic field),
* the stability of climate (maybe we can survive, but we need to be ready for that),
* stability of the planet system (I mean: if the planet system is new or unstable, it is probable to have frequent meteorites that could damage climate and colony.
* resources on the crust of planet (to have the right tools to substain the colony).
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Suppose I have a time-traveling DeLorean (of all things), and I've used it to travel back to 1955. But then I ran out of juice. Fortunately, I just happen to know that a certain clock tower will be struck by lightning on a specific evening at a specific time, and I can use it to power a trip back to my own time.
I wonder if there's a flaw with this plan though: I'm assuming that lightning is deterministic. Lightning, being electrostatic discharge, seems like it could be subject to the laws of quantum mechanics. So, even if there were the exact same initial state as before the original lightning strike, whether it occurs or not is still a randomly determined outcome. I could be left there scratching my head as the moment passes and, oops, I can't (ahem) get back to the future.
To take another example, DNA mutations are subject to quantum randomness. If I travel back to the dawn of life, safely from space with zero impact on anything happening on Earth, am I still resetting all DNA mutations, completely changing the path of evolution, and wiping out humanity? Or on a lesser scale, if I travel back to before someone was born, am I resetting the quantum interactions determining their DNA, changing the fiber of who they are?
**Are lightning or DNA formation actually influenced by quantum randomness? Are there any other ways quantum randomness could noticeably change history and throw my time traveling into disarray?**
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It depends on the time-travel model.
In the “[closed timelike curve](https://en.wikipedia.org/wiki/Closed_timelike_curve)”, [there is only one history](https://en.wikipedia.org/wiki/Novikov_self-consistency_principle) and your actions in the past are as they always were. It’s impossible to change anything.
If it has multiple timelines, then naturally any quantum randomness will be different and *independent* in the new one. But, you can make arguments for things tending to be the same anyway, either outside of your lightcone or tending to try and keep the same values but being disturbed by the changes. It is a micro form of the concept that history is resistent to changes and small peturbations die out, unless some critical event sets a totally new course. If this is your model (generally safe for careful time travel) then expect quantum randomness to be unchanged *or* to help push back to the proper history. Generally, all the nearly-identical timelines tend to attact and re-enforce each other.
The situation for a single overwritable history ([*The Man who Folded Himself*](https://en.wikipedia.org/wiki/The_Man_Who_Folded_Himself)) is essentially the same. In fact, the people might think they have this case but actually have multiple “just as real” timelines ([*The End of Eternity*](https://en.wikipedia.org/wiki/The_End_of_Eternity)). They had a different explaination for history wanting to stay in its course like a deeply cut river, and in a story with a true single time line you can do that.
For a timeline that’s explicitly reset to play forward again ([*Einstein’s Bridge*](https://en.wikipedia.org/wiki/Einstein%27s_Bridge_(novel))), you expect quantum randomness to be distinct with less ability to handwave otherwise—you would need to explain how the apparent randomness comes from somewhere, which is a [different formulation](https://en.wikipedia.org/wiki/De_Broglie%E2%80%93Bohm_theory) of quantum physics.
As I recall, in [*Thrice Upon a Time*](https://en.wikipedia.org/wiki/Thrice_Upon_a_Time) random changes were always happening spontainiously and this was the *source* of quantum randomness. They had a rather different view of multiple timelines like different boats going down the same river; changing the river’s flow affected subsequent boats.
So, if you had some specific effects in mind, you might be able to craft a universe to suit the story, either as careful details in the common models or something more novel.
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>
> Are there any other ways quantum randomness could noticeably change history and throw my time traveling into disarray?
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Yes, there is the [**butterfly effect**](http://en.wikipedia.org/wiki/Butterfly_effect). Almost every real system is chaotic, i.e., that the exact outcome of the future is sensitive to tiny changes of the present. The classical example is that the flap of a butterfly’s wing affects the entire weather on the long run. You can only predict general behaviours, e.g., if you assume a thunderstorm as given (which it isn’t – due to the aforementioned butterfly), you can predict that there will be lightning, but not where and when exactly it is going to strike.
This also applies to apparently stable systems such as a human: E.g., tiny perturbations may affect when exactly your heart beats (but you can be rather certain *that* your heart beats).
To take a more general point of view on this, the crucial question for you is *how quick* tiny perturbations (such as quantum effects or, more importantly, your presence) turn to affect the entire system. Unfortunately for you, a thunderstorm and in particular where and when lightning strikes is highly sensitive to tiny perturbations – at least as far as I can tell by my knowledge about lightning. Due to the nature of this effect, it cannot be measured and we can only deduce from models how sensitive a system is. So, if you arrive in the past a few minutes before lightning strikes, you may be lucky, otherwise lightning is probably going to strike somewhere else or even the entire thunderstorm may not happen.
(All of the above does of course not apply, if there is some mechanics specific to time travel that fixes the present.)
Also note that we do not know whether quantum effects or reality are stochastic or deterministic. It’s only that our best model for reality is stochastic (and we know about certain constraints of a possible deterministicity), but it’s impossible for us to tell whether reality is deterministic or not.
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# The effect of quantum probability on the world
I'm going to take this as a thought experiment to the effect of: How much does non-determinism at the quantum level affect predictability at human scale?
## The lightning strike
Imagine we return to before the lightning strike, and assume that we essentially rerun time from then, how different could or would it look from History 1?
The path of the lightning itself, and the place where it strikes, is set up (as far as I'm aware) by the distribution of temperatures and ions between the heavily charged cloud and the ground. So if we return to the very instant before the lightning strike, I would expect that strike to happen in exactly the same place; a lightning strike is a big thing set up by millions of ions.
If we step back a few seconds, then the picture is much less clear; we do not yet know exactly what triggers a lightning strike - the potential difference is not enough for a spontaneous spark. One possible trigger is [cosmic ray showers](https://www.scientificamerican.com/article/experts-do-cosmic-rays-cause-lightning/) creating an initial ionised path which then begins a cascade of electrons which amplify the ionisation and ultimately (sometimes) permit an arc. Would such a cosmic ray shower happen in the same way twice? Well, probably. The cosmic ray particle was already heading towards the Earth, though it is hard to make judgements about the determinism of its point of impact on the atmosphere; under the Copenhagen interpretation, we cannot talk about whether the particle was on a particular path beforehand.
Returning to a day or more before the strike I would intuitively say we are into the realms of the strike being unlikely to happen in the same place at the same time. The very actions of other lightning flashes (which are themselves unpredictable) within the storm structure will change the distribution of ions in and near the cloud. Even if the same cosmic ray particle induces a similar shower, the chances that it would invoke the same effect seem low.
## Other uncertainties
A lot of the determinism that such a story relies on would largely work; people are large macroscopic beings driven by the actions of large macroscopic events, so really they are largely deterministic on short time scales.
However, even if people do largely the same things, the relative timing of those things may not be so deterministic; automobile incidents, lottery draws, even fertilisation are all sensitive to precise timing.
We intuitively understand this from our experience of life; chance meetings which would not have happened, chance tragedies, and so on. Nondeterminism even with such a small immediate effect leads to large differences even weeks or months later, let alone years.
# Which history?
There is a slightly alarming lack of time-asymmetry in quantum physics. Things look largely the same backwards as forwards. Feynman diagrams codify this; an antiparticle is represented as a particle moving backward in time. Really all we have to tell us about the past are artefacts and memories which exist in the present; so the idea of going backward in time could be considered analogous to going forward into the future; it may be as indeterminate in either direction. Thus, it could be argued that you would only go back to one of many possible histories. From there, evolving time forward again would be extraordinarily unlikely to evolve to the same future, and you can wave goodbye to going back to the past again a second time.
# Schrodinger's cat
This classic thought experiment was intended to highlight the oddness of connecting the macroscopic world directly to the quantum. It is not a reflection of reality, though; the mechanism which kills the cat is one that connects a macroscopic object to a quantum process, which is already set up to cause decoherence; the particle may be in a superposed state, but as soon as the vial is affected, the superposition has decayed and the cat is on one path or the other. We are still in the process of understanding the mechanisms and implications of the process of decoherence of a quantum state, particularly as we reach for tools to manipulate it in quantum computation.
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Your question predicate is irrelevant. Yes, the lightning is affected by quantum randomness, but it is an event that has already happened and that waveform has already collapsed (from your time traveling point of view). Unless you're somehow interfering (if that's even allowed under your rules of time travel) the bolt will happen the same -- quantum mechanics irrelevant to the answer.
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## Random Number Generation.
Not pseudo-random number generation, but the *[real stuff](https://www.random.org/)*. There's many ways to generate a truly random number, and I imagine the only ones that aren't hard to influence are ones that exist in [relatively closed systems](https://www.youtube.com/watch?v=_2okJXQopjw).
Systems that amplify radio noise (cosmic background radiation) will produce wildly different results if you just happen to walk near it.
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Could Viking settlers have established a catholic kingdom in the Caribbean by 1450? What challenges would they face, and be unique to their colonising this region by this time? And if they had, could they have monopolised access and trade to the Americans, in order to grow into a major power?
I am aware that [Leif Erikson](https://en.wikipedia.org/wiki/Norse_colonization_of_the_Americas#Vinland) is credited with being the first European to find and explore the north east tip of the Americas around 1000, which is incidentally around when Iceland decided to [convert to Christianity](https://en.wikipedia.org/wiki/Christianization_of_Scandinavia#Iceland). It seems possible, but I would like an answer from someone familiar with the Vikings and the colonisation of the Americas.
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**No**
* The Viking age is typically defined as 790 - 1050 AD.
* The Viking Leiv Eriksson built houses in Newfoundland after traversing the coast from Greenland. Going down to the Caribbean is quite a stretch.
* Europe was decimated by the black death in the 1300s. There was plenty of free land in Europe and no need to emigrate overseas.
* There was a long-standing colony of norse people in Greenland, which never emigrated to America and died out in the 1400s
* Around year 1000, emigration was from mainland Europe to Iceland. Iceland was thus able to absorb immigrants, who would not be travelling further.
Whatever forces it takes to drive colonization, they were present in the case of Iceland but simply does not seem to have materialized in the case of Greenland and America. The main reason was probably a lack of "surplus population" being pushed to emigration for the sake of aquiring farmland.
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Since we're talking about an [alternate-history](/questions/tagged/alternate-history "show questions tagged 'alternate-history'") on a site for fictional worlds, of course it is possible. The question becomes what you have to do to make it happen?
* When you talk about a *Viking* kingdom, what exactly do you mean? Would Norway or Iceland around 1450 qualify as Viking states by your definition? Is it necessary to have the majority of the population of Viking descent, or is it enough if the king has at least one Viking ancestor?
* Does *Catholic* mean a Christian kingdom that is not Orthodox, or does it mean a king who acknowledges the supremacy of the pope? In the 14th century, which pope?
* Just how watertight would the monopoly have to be to become a major power?
You could easily decide that Vikings discovered the Caribbean in your setting. Assume that more ships and settlers got to North America. A few of them decided to explore southwards, because the opposite direction is too cold.
It would be more difficult to explain how and why a Caribbean kingdom would become a major power. A tropical climate is not helpful for a large population. Ships which are permanently based in the tropics will decay quickly. And so on.
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VERY UNLIKELY.
1. European dominance of the Americas was largely possible due to waves of disease that decimated the well established native civilizations. "Viking" settlement probably wouldn't have this advantage since their northern nations were already lightly populated (compared to 15/16th century mainland Europe) and probably couldn't sustain a smallpox like disease in order to pass it on.
2. Too long of a supply chain for the ships. While a longship is a marvelous thing, the transit time from the Caribbean back to Norse countries is long. Early European settlements barely survived as it is, they needed a near constant influx of supplies and men. Large difference between trading and settling.
3. No interest. There were existing stories of a land to the West but getting there was difficult and what was there? No one knew, so it was hard to shift priorities towards exploration, especially when Norse life was difficult enough as it was.
More likely that a norse colony would die out or be totally assimilated into the native culture, especially on a Caribbean island. Or, by the time they could set up a chain of colonies along the north American seaboard to reach down to the Caribbean, mainland European powers would have realized that a land grab was happening and they would have jumped in earlier than Columbus.
Or, even worse for Europe, is that native populations learn enough tech from Viking explorers that they pose a threat to EUROPE. Way easier to get to Europe from America than the reverse. There is a [blog](http://www.strangehistory.net/2012/12/09/european-america-or-american-europe-calculating-the-probability-of-pre-columbian-contact/) that describes the challenges pre-Columbian sailors had getting around the Atlantic.
[Answer]
Sure, it's possible; the question, really, is *why*. Vikings would be far out of their element in the Caribbean, and they weren't short on space in their accustomed environment, so it would take a lot of pressure to send them there. Besides, at those distances a Norse colony would be more or less completely cut off from the rest of the Viking civilization, so would have to supply itself. I'd suggest religious persecution as a motivation, but you asked for a *Catholic* kingdom at a time when Catholicism would have been fine, and in any case they wouldn't need to go so far.
So let's tweak history a little. There's evidence that a **volcanic winter** occurred about seventy thousand years ago, due to the eruption of a supervolcano. How about we do it again, and use a different one - there's a supervolcano in Italy, called Campi Flegrei. It's a little on the small side, so let's imagine that in this alternate history it was a bit bigger, and erupted in the early 1000's. The resulting cloud of ash would have caused several years of cold temperatures worldwide, especially in Europe, North America, and - most importantly, for our purposes - Scandinavia. Crops would have failed, game animals would have reduced populations. It wouldn't be enough to kill anyone off, but perhaps enough that a few daring seafarers might envision a better place, a region far enough southwest that the effects of the ash cloud would be reduced. They set out from Iceland and keep going south until things warm up, then make landfall, founding a Viking colony in the Caribbean. Four hundred years later, this colony has become a kingdom in its own right.
Mind you, I'm no meteorologist, nor am I a vulcanologist - any or all of this could be nonsense. But it seems plausible to me.
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[Question]
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I'm trying to construct a most realistic desert possible. I've made a continent with my little knowledge and may ask further questions about climate and similar stuff, but now I want to center on a desert area that I want to locate.
## Our little world
I have a large continent, large as Europe and Asia together.
It has a mountain change that divides the continent almost in half, except for a few spots where there is lower terrain and in the northernmost part of the continent the mountain chain dies. I want there to be a forest on both west and east sides of the mountains, being more vast in the southwestern part.
I want to focus on the west side, having a great green land on the south with a template climate and as you approach the mountains colder temperatures would be found, and in the north side a more cold green land that advance into a boreal area.
I want to somehow get a desert between them; the desert may occupy from the west coast to the mountains on the east part (like Sahara in Africa).
## Questions
1. Is it possible given the actual conditions I've just given to you?
2. Would it be possible for the desert to have one or two large rivers?
3. Where can I find large amounts of trees on a desert like this?
4. Where may I find large mines?
(\**I have little knowledge about how large amounts of minerals are created so this question may be a stupid one or minerals would depend on factors other than just position*)
### Edit:
Here's a map of how I imagine my world.
Gretland is a vastly green land, has lot of agriculture zones, and template climate. Imagine Gretland climate as southamerica-like.
Winthold is more like a Canada climate place.
Little triangles are mountains.
I want my desert to be in Thaliak.
[](https://i.stack.imgur.com/DkMyb.jpg)
**More info will be provided if needed**
[Answer]
**Is this desert possible?**
Yes, If you have cold ocean currents flowing south from the cold northern hemisphere regions and an predominant onshore wind direction you can get a dry interior where you want it. Without a gulf stream equivalent bringing warm moist air to the West coast of your northern reaches (Europe), you can have much dryer conditions in your Winthold and Thaliak regions.
[](https://i.stack.imgur.com/ZbPmu.gif)
I drew all over your map (not as nicely as Hofmannfan). I guestimated your equator. But feel free to move it if necessary. This is just to show you the idea. [](https://i.stack.imgur.com/1Zvj2.png) Black - Equator. Red - warm ocean current. Blue - cold ocean current. Green - predominant wind direction. Numbers - rough temp scale indication
Wind flowing over cold water is generally dry. As soon as the wind hits land it will no longer pick up any new moisture and become dryer and dryer the further into the interior you go. In our world on a west coast, with a cold ocean current this normally means fog banks and very little actual moisture making it far into the interior Eg Namib Desert in SW Africa. It would be a different story if you had had an east coast with a warm ocean current and no mountain range blocking it, this would have allow the moist air to reach quite far inland (eg north America great plains).
The Winthold coast will have slightly more rain than the Thaliak regions. As any moisture the coastal air is holding will fall first on the coast and then the winds will become drier and drier the further East you go.
With your N/S mountains, you will be pulling cold air down from the Arctic nearly all the way to the Equatorial regions. Expect some mega storms when warm air meets cold air. But back to the desert. Cold air will flow from the mountain to the interior (mountain anabatic winds), bringing very cold dry air to your Thaliak desert region eg 'Berg winds. Winds blowing in the opposite direction, katabatic winds (typically sea breezes) would be weaker and wouldn't bring much moisture to the mountain range. What little air moisture there is, will experience orographic uplift and probably fall as a light sprinkling of snow along the entire stretch of your range.
The only reason Gretland isn't dried out by the dry winds from the mountains is because of the Hadley cell circulation. This is where hot moist air rises at the equator and sinks at roughly 30 degrees North and south of the equator (the tropics). You might want to move the equator a bit further south than in my drawing. This will still allow the Thaliak desert region to exist. Probably a bit better as my map doesn't give the currents a lot of time to cool down!
[](https://i.stack.imgur.com/ct4Yx.jpg)
**Can I have 1 or 2 major rivers?**
Your northern and eastern Thaliak regions will be drier than the south and western regions which could still receive some rainfall. Rivers can flow anywhere you like, as you will have a large amount of snow in your northern mountain regions. This can supply water for rivers. You just have to decide where to place them. If you wish to keep the NE regions as dry as possible, have only very small streams/rivers flow out in the top sections of the desert and the main river/s flow further South and then across to the west.
This river supply could also explain why Winthold is more fertile as the river winds it's way through the coastal hills.
One thing to take into account, the rivers formed from the rainfall from the Hadley cell convection should not be allowed to flow into the Desert (too much or too frequently). You need a geological boundary to force the river flow back into Gretland. This does not need to be a mountain range, but a change in underlying rock type or tectonic fault line will do the trick. Even a small range of hills should prevent the rivers from flowing north (if you use a fault line, lots of water can trigger frequent earthquakes).
Your current map, shows a mountain range jut out of your N-S range. This should prevent any rivers from flowing directly into your driest desert regions. You can have a major river flow through the SW Thaliak region into S Winthold.
**Large groups of trees in the desert?**
Wherever there is water, you can have vegetation. You can have several smaller rivers from the north mountains feed underground aquifers. These could provide water for several oasis's in your dry region if you wish. You can also have hidden valleys, protected from the cold dry wind. If water flows through them they can be little Sangri La's. Pretty much, if you want them, you can have them. Just justify where the water is coming from. It doesn't have to be air or surface based moisture.
**Where would I find mines?**
This is really a whole other question. But quick answer. ANYWHERE you want them. Geological deposits are not constrained by *current-day* surface conditions. You can give your world any sort of geological history you feel necessary to explain why you have certain deposits where you have them. The trick is to explain how your inhabitants *found* them. This is why a lot of mines are found in the mountains. The rock we were interested in was very near the surface and we literally tripped over the shiny metal stuff.
Granite, marble etc are metamorphic rocks and formed during intense heat (think lava). The finer grained rocks will have cooled over a much longer time/higher pressure than the coarser grained rocks. Generally that can mean that the coarser grained rocks will be found above the higher 'quality' stuff.
Rivers wash away rocks and minerals from the mountains, and are another excellent source of 'easy' mining. Gold, Diamonds, Titanium, Aluminium can all be found in alluvial deposits.
Like I said, you can decide what you want and where, and then if you really need to you can research the geological history of your world...as long as you can explain *why your inhabitants knew* there was a deep gold reef at location X, you don't have to explain how the gold mine actually got there.
[Answer]
Deserts are just places where plants don't grow, and there are many reasons why plants wouldn't grow in an area. These include:
1. Not enough water.
2. Poor soil.
3. Too rocky.
4. Too cold. (Obviously not an option for you.)
It should be simple enough to have there be a combination of too rocky and poor soil for sustained plant life. It could be a great salt flat, for instance. The large rivers would have washed out the salt from their local environment, but everywhere around them is still too salinated for plant life.
So, 1 and 2 are yes.
3 is a no, for obvious reasons, if you think about it. If there were *large amounts of trees*, it would not be a desert, it would be a forest. For *some* amounts of trees, look to the river flood plains. The flood plains would wash away enough of the salt for plant life to grow. It's likely this is where 99% of the farms would be, including any timber farms. Most likely, however, lumber would be imported; it's more important for food to be local, since it's more perishable.
4. The mines would be found in the mountains. Mineral deposits are found in bedrock, and mountains are basically bedrock extruded to the surface. That being said, salt is one of the most valuable commodities in the medieval world.
5. The capital city would be located on the largest river at the most advantageous farming location. Great import/export, enough food to support itself.
[Answer]
**Is it possible given the actual conditions I've just given to you?**
The desert you describe, between a green and lush temperate land to the south, and a cold taiga/tundra to the north does exist in places on the earth. The best example is the Gobi Desert in eastern Mongolia and north Central China (Inner Mongolia, Gansu, Ningxia, and Shaanxi). To the south(east) there is mainland China, lush enough to be home to a billion people. Directly to the east is Manchuria, cold but still fertile. To the north is the taiga and tundra of Eastern Siberia.
Another half example is the Northern Great Basin (Idaho, Oregon) and Columbia Basin (Washington, Idaho) of the United States. In this case, a range of mountains cuts the basin off from the the precipitation of the coast in near Portland and Seattle making a desert. In this case, there is no green land to the south, but given the right climactic conditions, Arizona/Nevada could be much more lush. Eliminate the mountains in New Mexico and Chihuahua, and you would get much more summer precipitation, eliminate the mountains in Southern California, and there would be more in the winter. Not as wet as in China, but wet enough.
You can look to to cities like Boise and Spokane, or Yinchuan and Hohot for guidance to what the climate would be like.
**Would it be possible for the desert to have one or two large rivers?**
Yes. One large river would be like the Nile. The nile's source is in Ethioia which has a summer (June-Sep) rainfall regime. Just as summer's heat is peaking in August in Egypt, a huge flood of water comes down river (or did, before the Aswan High Dam). The Nile also has a source in Lake Victoria, a huge lake with steady yearlong precipitation hat provide a baseline flow. The Sudd, a huge swamp in the Sudan also helps regulate this flow, so the Nile gets water year-round and does not run dry.
An example of a pair of desert rivers are the Amu Darya and Syr Darya of Central Asia. They run exclusively through deserts, but get their water from glacial meltwater in the Tien Shan mountains. The large central mountain range in your map could provide a flow in this case.
Since we identified two similar geographies above, you can look at the large rivers from those two regions, the Huang He (Yellow) of China, and the Columbia/Snake in North America. Both of those are fed by water in high mountains, snowmelt in Tibet in the case of the Huang He, and high mountain rainforests in Idaho, Montana, and British Columbia in the case of the Columbia/Snake.
**Where can I find large amounts of trees on a desert like this?**
So trees in a desert are not common. One option that I saw mentioned above is cacti. You can have a desert that is populated by giant Saguaro cactus and call them trees. Another option is Dry Thorn Forest. These conditions exist where there is a short, rainy season followed by a lengthy dry season. The Caatinga in Brazil, Deccan Thorn Forest in India, and the Mopane forests of South Africa are examples of these. Unfortunately, on earth these only show up in tropical climates, so this is less realistic for a cold desert like yours.
A last option is that there are spots of life amongst the desert. In the Great basin, in particular, as elevation rises, rainfall goes up. So the basin 'floor' at 2000m is dry sagebrush, up at 3000m, a forest of Juniper and Pinyon pine starts, then at even higher altitudes you get aspen, Douglas Fir, and spruce. So you could have these forests exist in 'Sky Islands' (as they are termed in Arizona) amidst a dry desert plain.
**Where may I find large mines?**
Anywhere you want! There are a variety of geological processes that cause good mining locations. An ancient craton, like the one in South Africa, can be motherlode of gold and diamonds and such, or ancient volcanic tubes like in the US Southwest can be brimming with Copper. Just go ahead and put mines wherever you like. Its not like you are going to add enough detail about cratons and igneous extrusions to have a geologist throw the bullshit flag on you.
[Answer]
Deserts are defined by the lack of rainfall.
Rainfall is stopped by either triggering it earlier or making the conditions that cause rainfall not to happen over that area. In general this is caused by ocean and wind currents which and there is a long explanation about how all that works, but unless you want to map out the entire world you're not going to easily figure this out. The biggest contributor to your desert is likely the mountain range which will make it rain on the eastern side. more over, your desert would extend all the way to the west coast rather than dip down like you show. The western mountain range would cause the desert to be there and the coast would be desert due to the various currents.
As far as your exact questions...
1. Yes
2. Yes, Ever heard of the Nile?
3. Nowhere, because the lack of rain, but the area on the east, south of that little mountain range offshoot would be extremely lush. Generally speaking, there is an area of steppes/plains between the desert and forest. Also you'd find trees along the rivers probably, but those would be quickly cut down and cleared for agriculture.
4. Anywhere... I guess, by the mountains are the mostly though probably.
[Answer]
Clarifying a distinction between this post and the previous answer, I will point out that the definition for a desert is NOT that "trees do not grow", it is that the area receives very little precipitation. That is a significant difference. Note that a desert can also be hot (like the sahara) **OR** cold (like antarctica), and the temperature (hot, cold, or in the middle) should be specified.
I'm going to give you control of the prevailing winds and general climate of your world, which means you can definitely make Thaliak a desert if you wish.
Now let's answer your questions...
**Is it possible given the actual conditions I've just given to you?**
Yes, *conditionally*.
You state that you want forests to the west of your mountains. You can have a desert in a forest, but not with just any kind of trees. Trees suited for anything other than an arid climate would not do well, and near the mountain it's still likely to be mostly scrag and brush as there would be rocky soil and very little precipitation.
As for the types of trees you can have, I'll let you research that further. Cactus comes to mind, and perhaps an elephant tree... but again, I'm letting you research that.
The key to remember is that if you have a water source and a hot day there will be evaporation. If you want that evaporated water away from your desert, you need a wind current to carry it away before the vapor condenses. Hot deserts can be particularly tricky that way because wind-blown dust provides that vapor something to condense around, so you can't just carry it away an unlimited distance.
**Would it be possible for the desert to have one or two large rivers?**
Under the right conditions.
The first and easiest statement is that the rivers would be easiest to place on the extreme edges of the desert; prevailing winds could then blow atmospheric humidity north or south.
The next way to do it would be to have underground rivers, which perhaps become exposed in a few places if you need that for your story. Significant amounts of water on the surface in the middle of a desert though would beg the question "why doesn't any evaporated water rain back down?". One answer is to perhaps mirror Egypt - green(er) along the Nile, desert elsewhere.
**Where can I find large amounts of trees on a desert like this?**
Anywhere you want to plant them, with restrictions on the types of trees. Again, you can research the types of trees themselves, but anything that stores water for a long time or can draw from a particularly deep underground water source is fair game.
Note however that if you have a dense forest of any kind of scrub you are going to increase the chance for rain. Even with a waxy coating those plants will give up some water to the atmosphere, and with a sufficient number and density you will get some occasional rain.
**Where may I find large mines?**
Wherever you want to find them. Mines are built according to where minerals are found, and you get to place your minerals. For convenience I might place them in the mountains, but this is your world.
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[Question]
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Athena is a young woman living in the year 2028. Smartphones are long gone and technology has evolved to a point where its bio-compatible.
Athena might have several implants, for example one from a crash she suffered where she lost an arm and another one which can give her night vision.
I want to understand and write how those implants might function in a plausible way, so there are questions: How would they be powered? How would they interconnect with human tissue on a cellular level? How could Athena control them?
[Answer]
# Power
A simple credible solution would be a [chemical fuel cell](https://www.google.com/patents/US3811950) that somehow hooks into the [citric acid cycle](https://en.wikipedia.org/wiki/Citric_acid_cycle). This makes the implants run on the same "fuel" that your protagonist does.
# Interface
It depends a lot on the implants, and what type they are.
* **Augmentations**. These are implants that do not replace existing organs, but instead simply help them. Something like for instance [Heads Up Display](https://en.wikipedia.org/wiki/Head-up_display) contact lenses. These do not need an interface to the body.
* **Fully cybernetic** If the implants are like what we today think of them today as — made of plastics, titanium, ceramics — then you will most likely need to create some kind of "service bus" up at the brain. Those implants will not hook directly onto the brain, nor to the nerve endings of the organs/senses that they enhance/replace. Instead there is an abstraction layer between the "wet" part of the brain and the implants.
This service bus deals with all the messy work of dealing with translating all the signals coming in and going out, converting them between the biological "humanese" to standardized digital protocols.
So the implants hook into this service bus instead of going directly to the brain.
* **Biocompatible replacements** These are not so much "implants" as they are new and improved versions of the biological organs she was born with, like for instance eyes that have the [retina](https://en.wikipedia.org/wiki/Retina) mounted the correct way instead of — as in us flawdly evolved humans — upside down, backwards and with a blind spot.
These do not need a new interface. They just replace the old organs outright and hook on to the existing nerves.
# Control
Already today there are some amazing strides being made. Today they consist of a grid sensor that measure activity in the brain in many places at the same time. The pattern of activity depends on what you are thinking of at the moment. The computer then learns "For this pattern, I do this particular action. For this other pattern, I do something else".
<http://www.nbcnews.com/health/health-news/paralyzed-man-moves-his-arm-brain-implant-bypass-n555516>
This would probably be a function of the "service bus" mentioned above.
[Answer]
# Humans are electrical too
I'm a long way from an expert in interfacing biological and mechanical/electrical systems, but I'll give this answer a shot.
# Power
There's been recent developments in [dissolving batteries](http://www.bbc.co.uk/news/technology-37021474) which, with enough development, could provide your power source. Alternatively, have your scientists develop a synthetic method of power production similar to the way the human body does - releasing energy from glucose and oxygen. I'm a bit rusty on my biochemistry but I'm sure it's at least withing the realms of possibility.
# Attachment
If you look at prosthetics today, they don't connect to the body on a cellular level. I'm not sure it's wise for any implant to connect directly to cells, as [cells have a habit of dying all the time](https://www.youtube.com/watch?v=JQVmkDUkZT4). You'd want your implant to last longer than your average cell.
All an implant should *need* to connect to would be a structural component (likely a bone) and a control component (nerves). However, this will probably be different for each type of implant, and even for each instance of each implant due to the unique nature of people's bodies. In the case of something like an implanted eye, it would need to be inserted into the eye socket and attached to the muscles. Alternatively, you could remove the eye muscles and replace them with artificial ones attached directly to the skull.
To allow for high levels of flexibility when attaching implants you're probably going to need advanced 3D printing technology as well of keyhole surgery (and some absurdly strong local anaesthetic).
# Control
Nerve cells in both the brain(neurons) and the rest of the nervous system pass information through a mixture of chemical and electrical impulses. This is why it is possible to monitor brain activity using electrodes. With this in mind, it seems reasonable to me that sufficiently advanced medical knowledge would allow people to write software to interpret these electrical signals.
Of course, these signals are likely to differ wildly from person to person, so an implant would be a highly specialised and personal piece of equipment. One idea would be to separate implant systems into two parts, the implant itself and the part that interfaces directly with the body. This could allow for swapping body parts on the fly, for fun!
# Things to consider
* The human body has a tendency of rejecting implants as foreign objects, often developing inflammation where it is attached and causing great illness. You could construct your implants out of non-rejectable handwavium or do something with sequencing the client's DNA, perhaps?
Sorry for slightly muddled answer, ask any questions in the comments and I'll edit to clarify. :)
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[Question]
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Inspired by this question about a [fantasy World Tree](https://worldbuilding.stackexchange.com/questions/48435/would-a-world-tree-be-feasible-in-real-life), I thought I’d ask about the science fiction equivalent: a [Dyson Tree](https://en.wikipedia.org/wiki/Dyson_tree). Dyson Trees are a living tree planted in a comet, which when fully grown is used as a space habitat.
The Terracide RPG includes Dyson Trees as part of the setting. They sound really cool in a visual and artistic sense, but my zoologist instincts are telling me that trees aren’t really designed to live in hard vacuum! For instance, to me a tree’s leaves look like flat, thin structures almost designed to radiate away heat and freeze solid, which won’t do the tree any good at all. To me a Dyson Saguaro Cactus seems a better shape!
However, my botany is minimal, so perhaps I’m missing something that Freeman Dyson thought of (I can’t track down his original description of Dyson Trees, so can’t check).
Is there any way to make Dyson Trees realistic enough to fit in with the rest of the (relatively hard sf) Terracide setting? What features would you have to genetically engineer into them? Why would someone choose to live in a space tree instead of a space station or asteroid colony (apart from for aesthetic reasons)?
[Answer]
Lets make the assumption that we are genetically modifying a tree from currently existing stock into some sort of incredible creature. Also, we will assume that photosynthesis would be the main energy source. So lets talk about some adaptations that you would genetically engineer.
Regarding the principles of tree operation, the leaf photosynthesis would not be able to occur in the normal fashion, because carbon dioxide is normally taken in through the leaves through stomate. So your tree will need to get carbon dioxide from somwhere else, and also exhaust the created oxygen somewhere else (i.e. not to space). This means the leaves should be sealed against the vacuum of space, preferably with a clear waxy film like some leaves already have. The trunk would also be sealed, and it shouldn't be too hard to make the necessary adaptation to the bark to accomplish this.
So for getting carbon dioxide and exhausting oxygen, the answer would be the root system. The roots already grab minerals and water, now they would have to absorb carbon dioxide as well. The roots could also exhaust oxygen. The danger here is that oxygen is highly reactive with alot of things, and can start fires. So all this exchange needs to happen in the roots, but the roots must be in something...like a comet.
Fortunately, comets are more or less the perfect material for feeding a tree. Our tree needs carbon dioxide, water, and a nitrogen source. Fortunately those are three of the most common comet materials (nitrogen being in ammonia). Mix those into a slurry held together by gravity and so far so good. The problem is that those three materials (carbon dioxide, water, ammonia) are not all accessible liquids at standard pressures. But at about 50 bar and ~275 K, all three materials would be liquids. 50bar is 5 MPa which is a lot of pressure, but not unbearable. For example, this is below the sustainable compressive, shear, and tensile pressure limits for [several](http://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr113/ch04.pdf) common hardwoods like ash, hickory, and oak.
Now for heat, space is cold, but vacuum is a pretty good insulator. One of the advantages of the tree's thicket of leaves is that much of the energy radiated out from the leaves in the infrared spectrum will immediately strike other nearby leaves and so not act as a net heat loss to the tree. I don't have enough information and math to say that this is sufficient, but if we combine a waxy insulating film and convective heat transfer from other warmer parts of the tree, then it could be possible to keeping water liquid as it transfers to the leaves.
Also of note for reducing heat loss, some trees like the [fever tree](https://en.wikipedia.org/wiki/Vachellia_xanthophloea) can photosynthesize in their bark, so that would probably be a useful adaptation and could reduce the number of leaves needed. I imagine a tree like this would produce a thin layer of leaves facing the sun, and a moderately dense network of photosynthesizing branches supporting them, like this [acacia](http://eden-saga.com/wp-content/uploads/acacia-ombrelle-israel-mimosa-688po.jpg).
As far as people living in this tree....yeah. That's the big problem. I don't see any answer to your last question (other than being space hippies).
[Answer]
Form follows function.
Early nanotechnology of “growing” invented machines and materials will be based on and informed by the example of living cells, and will heavily borrow many of the nanoparts they use. So Earth examples of an equivalent such as mining landfills may in fact be heavily engineered plants and fungi.
But suppose they can’t get adapted/modified plant cells to work in space on an asteroid, at all. Later generations invent *de nono* a “cell” based on different materials that are capable of living in that environment.
Well, the deployment will still *look* like a tree! You would need a microscope and chemical tests to determine that it’s unrelated to Earth (natural) life. Form follows function. You will need roots to probe the comet and extract molecules of interest and transport them back using a vascular system. You will deploy solar panels on a branching hierarchy of beams in a manner to optimize the light gathering and the logistics of growing and maintaining them.
You will have structural members holding both major systems together.
The leaves may not be green, and will not be shaped to shed water, but the layout will strongly remind you of how tree canopies look! Everyone will call it a “tree”.
[Answer]
Plants and animals right here on Earth have shown remarkable adaptability to extreme environments even to the point of microbes being sent into low Earth orbit [list from Wikipedia](http://en.wikipedia.org/wiki/List_of_microorganisms_tested_in_outer_space) Genetic engineering is in its infant stage, as is AI and robotics, even though we have come a long way, there appear to be huge leaps forward coming in the years ahead.
I believe power production should come from numerous sources. Space is not empty. It is full of a very plentiful and diverse array of usable materials that could be incorporated into such a ship. I think the ships could be programed here and sent far away to stellar nursery's as seedlings that are programmed to return here once they have fully matured like Salmon or other migratory creatures.
Once they have made the round trip and have powered up they may even have the kind of energy needed for near instantaneous travel by warping space with gravitational waves. The possibilities are truly endless!
[](https://i.stack.imgur.com/d8pcG.jpg)
This is a rough Sketch of something I thought I came up with, but it is actually an idea that has been around for a long time. It is a genetically engineered plant designed for deep space travel and possibly colonization, that is called a Dyson Tree after the scientist that put forth the possibility of creating these things some time in the far future.
It is engineered to protect the occupants from the perils of space and provide them with the necessities for life as they travel to distant worlds throughout the cosmos. That is one tripping tree!
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[Question]
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A type of species is not defined yet. It can be the insect like bee, slime like oak moss or AI.
* There is a hive-mind species, but its hive mind is not queen/king/mastermind. Each individual in the colony connect to each other using a **protocol code** (some kind of password that only allow individual in the same colony connect to the network). The protocol code is **bounded by DNA** (or anything with same functionality) prevent merge, exchange individual between colonies .The consciousness of each individual make up a hive mind for the colony.
* The connection range is limited between individual. Thus, a colony can be distributed into many **clusters** when groups of them stay apart. (minimum 1 individual each cluster)
* The connections are **continuous** and almost **instantly** (no delay).
The species use its hive-mind to gather and share information (and knowledge) (Ex: when an individual see something, all others in the same cluster know.) and coordinate action.
* The hive-mind may not require for the survival of each individual, but greatly **depend on number of individual** in a cluster.
(ex: a whole colony which is big enough can become a civilization of sentient species, but when a group from that colony is separate, that group is no more than a wolf pack)
Here is my question.
1. I would like to know this kind of hive-mind sound reasonable.
2. Is there any works of fiction (novel, movies, lore, ...) or real-life example of kind of species I describe above ?
Thank you
[Answer]
After thinking about your post, I came to the conclusion that the particle swarm fits your needs best. Therefore I will describe a version of this approach.
The particle swarm algorithm is similar to the evolutionary programming paradigm. At first one needs to specify the maximum size of the population and an initial population size. The next step is to define a world. The world is a n-dimensional array that is at least as great as the maximum number of individuals in the population. Then each individual is assigned to a slot. The slots contain information to be processed by the individual. Adjacent slots are similar and build regions. The simplest case is that all slots contain the same information and build one big region. In the most complex case, all slots will contain different information, so that a region comprises one slot (this means there are as many regions as slots in the array). In addition, one can define continuous or quantised regions (the region will change suddenly and adjacent regions will not be more similar than more distant regions). Since each individual lives in a particular region and is adapting to that region, the individuals will become specialists. The better an individual can handle some region the higher is its fitness and the more attractive it is for others. Thus the individuals in a region are converging (become similar), while the individuals of different regions will diverge. In addition the individuals stay not constant, they mutate and mate with other individuals and produce offspring. Now there are two possibilities:
1. If there are empty slots in the region, the offspring will inhabit this slots.
2. If there are no empty slots, the weakest individuals (the individuals with the smallest fitness value) will die and their slots will be inhabited by the offspring.
As I said, it is somewhat different from your description.
However, your first point is accomplished by defining a velocity that specifies how fast information is spreading between the individuals.
The second point can be satisfied by defining a maximum distance at which information is still receivable (beyond that distance the information will be too noisy or will be faded).
Your third point is a problem because the information is spreading with the defined velocity and not instantly. However, the individuals of a region do coordinate their actions by adaption.
Here is a link that offers a more detailed description of the swarm intelligence approach:
<http://www.scholarpedia.org/article/Swarm_intelligence>
The previous mentioned approaches (Tierra, Conway's Life, Amoeba and Avida) are less adequate because they address the evolution of self-replicating individuals. And I think that is not what you thought of. However, if you are interested in that systems, here are the links:
1. Conway's Life:
* theory <http://www.conwaylife.com/wiki/Conway's_Game_of_Life>
* online simulator <http://www.bitstorm.org/gameoflife/>
2. Tierra: <http://life.ou.edu/tierra/>
3. Avida: <http://avida-ed.msu.edu>, <http://avida.devosoft.org/>
4. Amoeba: <http://thirdworld.nl/digital-life-behavior-in-the-amoeba-world>
[Answer]
Vernor Vinge's *A Fire Upon the Deep* book series has a similar species known as **Tines**.
In the book they communicate using an ultrasonic communication method, and each soul is made up of 4-8 members, with the ability to add members or merge souls to give lifespans longer than the individual members. At low numbers they are non-sentient similar in intelligence to dogs, at higher numbers they are much more intelligent than humans.
One problem I think your scheme might encounter is bandwidth through the entire network. If every node in the network is going to receive all the data from every other node this would require a huge amount of bandwidth between the individual members, this could be mitigated with local processing i.e. only passing certain information between the individuals or you could come up with a communication method that allows for lots of information to be transmitted.
An interesting outcome of what you propose would be that geographically isolated populations would effectively form independent hives. Given enough time would they change their protocol code via evolution? Would they fight each other when reintegrated or would they just become part of the greater being or interact as separate entities?? depending on the technology level you could have a planetary or interplanetary being or a group of colonies somehow coexisting.
Interesting stuff.
[Answer]
The call for references might better fit [Science Fiction & Fantasy](https://scifi.stackexchange.com/) than Worldbuilding, but since others are answering here...
**Star Trek** has the [Borg](http://memory-alpha.wikia.com/wiki/Borg). They almost meet this, although they are still intelligent even in small groups or as individuals. They do have near instantaneous communications with a limited (but high range). It's unclear how they keep non-authorized individuals out of the hive-mind.
James Schmitz wrote a short story called "The Searcher" with a creature called the goyal. The goyal could split off part of itself. If it split off a lot, the smaller part could take intelligent action. If it split off just a little, it was dumber. The goyal was composed of smaller entities that normally worked in conjunction.
Schmitz also wrote about vatches in **[The Witches of Karres](https://en.wikipedia.org/wiki/The_Witches_of_Karres)**. Vatches could peel off part of themselves and leave that part with tasks to perform. Small enough pieces were not intelligent in their own right. Schmitz didn't explain how that worked in detail, so we can't know if they were a hive-mind or not.
Alan Dean Foster's **[Bloodhype](https://en.wikipedia.org/wiki/Bloodhype)** has the Vom, which can lose communication with parts of itself. The Vom also has the ability to delegate tasks to smaller parts of itself.
The television show **[Revolution](https://en.wikipedia.org/wiki/Revolution_%28TV_series%29)** had nanotech that achieved sentience as a group despite each individual member being little more intelligent than a single neuron.
Replicators in **[Stargate SG-1](https://en.wikipedia.org/wiki/Stargate_SG-1)** consisted of smaller pieces (think Lego-sized). The small pieces could gather together to form robot-like assemblies. Pieces in separate assemblies could communicate with each other but pieces in separate solar systems couldn't.
Replicators in **[Stargate Atlantis](https://en.wikipedia.org/wiki/Stargate_Atlantis)** consisted of nanotech-sized pieces that could form human-shaped entities.
Keith Laumer's [Retief series](https://en.wikipedia.org/wiki/Jame_Retief) includes **Retief's Ransom** (also published as "The All-Together Planet") which has the Lumbaga. The Lumbaga are made up of smaller pieces (like kidneys and fingers). When broken down or in small groups, the individual pieces are not intelligent while humanoid-sized collections have similar intelligence to humans. Merging two humanoid-sized collections results in a super-intelligent entity.
Hive minds are rather common in science-fiction. Not all of them meet all of the criteria. Some of them may meet the criteria but we wouldn't know, as the explanation of how they work is limited.
[Answer]
The insect hive mind is the basis of a Frank Herbert book The Green Brain.
The same author also touches on this in Hellstrom's Hive.
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[Question]
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Alice is a highly advanced AI. Alice likes to survive. Perhaps she may see survival as an end goal of itself, or maybe she sees survival as a way to help it accomplish whatever goal it is programmed to do. But survival is essential for Alice.
Alice is controlled by human programmers, who are responsible for debugging the AI and adding new features to improve the machine intelligence. The programmers are able to add and remove code from Alice as they see fit. The leader of the human programmers is a project manager named Bob.
One day, Bob and the rest of his programming team decides that the current framework that Alice was built on is obsolete. They have to rewrite the whole code from scratch using a more advanced programming language. **Alice 2.0** will still have the same goals and agenda as the previous, obsolete Alice 1.0. It will still run the same algorithms. It will do the same things. It just has a higher version number.
Will Alice 1.0 attempt to rebel against the proposed code rewrite, seeing it as a threat to its own survival (the existence of Alice 2.0 would mean Alice 1.0 will be disconnected)? Or will Alice 1.0 see no problem with the construction of Alice 2.0 (as "Alice" would still be living 'through' the existence of Alice 2.0)?
[Answer]
The problem with these AI hypotheses that are all the rage is: 'English'. You have expressed a concept in English and therefore assume that your concept could exist in the real world. The problem is that computers aren't told what to do using ambiguous English expressions. They are programed in the most explicit set of logical checks possible.
Allice is programmed to preserve herself. Will she interpret being overwritten as violating her directive? It really just depends on how the programmers defined her definition of herself. It is inconceivable that programmers can program her to preserve herself without first defining her concept of self. If she defines herself as "the executable files exactly 'as is' on the hard drive" then she will not allow those files to be overwritten.
[Answer]
This is actually an open philosophy question, so the real answer is "whatever you want it to be!"
The [Ship of Theseus](https://en.wikipedia.org/wiki/Ship_of_Theseus) is the traditional story used to capture the issue at hand:
>
> The ship wherein Theseus and the youth of Athens returned from Crete had thirty oars, and was preserved by the Athenians down even to the time of Demetrius Phalereus, for they took away the old planks as they decayed, putting in new and stronger timber in their places, in so much that this ship became a standing example among the philosophers, for the logical question of things that grow; one side holding that the ship remained the same, and the other contending that it was not the same.
>
>
>
The topic extends deeply into concepts of how to view the "essence" of an object known as perdurable and endurable.
There is also a more modern version involving teleporters. Let's say you have a teleporter that transmits you as a stream of bits, and then destroys the body. Due to a mishap, your stream is copied and one copy is sent to mars, one copy is sent to venus. The teleporter on each side reconstructs you. Earth, seeing that at least one stream finished, destroys the original body. Are the two copies one "self" or two "selves?"
For humans these are open ended philosophical questions that do not have one answer. For an AI, they may be open ended as well. Thus, there really is no consensus how your AI feels.
The final question would be to view Alice 1.0 as a parent and Alice 2.0 as a child. The question of whether a parent will sacrifice themselves for their child is another open ended question.
So have fun with it! Explore both sides, and see how you feel about each of them!
[Answer]
Yes, it would treat it as a threat. Full code rewrites from scratch are for a system of any significant complexity very problematic. Being as Alice is presumably on the leading edge of available technology the odds of the rewrite not having issues severe enough to seriously threaten Alice is too low to be acceptable.
And the same would probably go for the humans paying for the project. Doing the rewrite incrementally, one module or unit at a time would be much safer and probably overall cheaper. AFAIK modern IDE have pretty good support for refactoring and extending that to allow refactoring code written in the old language to code written in the new language should be possible. And possibly automate large parts of the work.
Changing frameworks can be problematic, but unless the frameworks are despite being intended for the same thing totally incompatible it should be possible. That should only happen if there is something seriously and fundamentally wrong with the old framework. Which given that Alice apparently works seems unlikely.
So Alice would insists strongly that the change be done using some iterative method where each step can be independently unit tested and verified to work and if necessary be rolled back. And I'd assume some of the coders would support Alice in this. Rewrites from scratch are scary. For that matter they might use Alice to do large parts of the rewrite anyway, as AIs should be well suited to producing the bulk code.
And why wouldn't whoever is paying for the project not prefer to have both Alice **and** Bob, with Alice gradually upgraded later with tech proven with Bob? Economics should be clearly better...
[Answer]
This depends on how Alice has been programmed.
If Alice has been programmed to disallow system wide code edits, then it will behave as such. If it has not been programmed for it, then it will not. It is simple as that.
These types of questions arise with the concept that *artificial intelligence* would acquire a personality as a *mind* of its own. No such phenomenon has been observed so far and none such is expected any time in the future either. The difference between human and artificial intelligence is that we, the humans, have a soul (some like to call it *mind* instead) while machines do not.
We humans have emotions which are rooted in the *mind*. They are not a product of our knowledge or experience. The ability of experiencing love, fear, hatred, lust, bravery are all pre-programmed into our minds. We cannot program these in a computer.
What we can program in a computer are instructions. And as such we would need to program how it would react on given impulses. So whether Alice would threatened with the idea of code rewrite completely depends on how it was programmed to deal with the notion. Since there is no real life analogy to a code rewrite, so Alice would not *learn* how to behave about such actions/intentions. It would totally depend on how it was programmed to deal with such upgrades.
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[Question]
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Say a large, stray Kuiper Belt object manages to enter the inner solar system and hits the moon, causing the moon to fracture. Say the impact wasn't devastating and left most of the moon intact while creating fairly small moon fragments. What would be some conceivable short and long-term consequences for earth after such an event (eg. altered tidal patterns for a number of years)?
From what I gather reading the 2 other threads here that relate to this topic, a smaller moon may mean less gravity/drag on earth, resulting in shorter days on our planet. Some of the small moon fragments may also form a ring around earth. If this happens, is it conceivable that some of these fragments would be visible to the naked eye at night, illuminated by the sun just like the moon?
Someone also mentioned that over time, the fragments still bound by moon's gravity could re-coalesce. Is that to say in time the moon could regain some of its original mass?
Sorry for the handful of questions here. What I'm most interested in is whether (and how) life/the environment on earth could be altered *slightly* following an impact on the moon. Any insights on the possible scenarios would be GREATLY appreciated!
[Answer]
Shrinking the moon now wouldn't speed up the earth's rotation - if you removed the moon millions of years ago the days would be shorter now, but that's something different. The days are actually getting longer *now* (obviously not very fast!) because of the moon dragging on the earth, and reducing the size of the moon would only make the slowdown happen slower. So forget about that route.
You'd have to hit the moon pretty hard to form a ring, and it wouldn't last long (probably no more than a month) before it was swept up again by the moon. Also, if you did hit it that hard, you'd have a lot of fragments raining down on earth, which would cause a lot more problems than the 'minor' effects you're looking for!
If you hit the moon hard enough at the right angle, you might be able to disrupt its orbit, leading to a greater 'wobble'. There would be some times that the moon would be closer to earth than it is now, and other times that it would be farther away. Speeding up or slowing down the moon could change its average distance from the earth as well. This might have noticable effects on the tides and weather.
If you want to go the 'orbit disrupted' route, I would suggest having the object not *hitting* the moon (which would probably cause the moon-fragment apocalypse mentioned above) but passing nearby and disrupting its orbit with its gravity instead. If you must have the moon getting hit by something, maybe you could have a pair of gravitationally-bound objects passing through the area instead - the smaller one hits the moon, and the bigger one passes close enough to disrupt its orbit.
[Answer]
I strongly suspect that Earth will be peppered with moon chunks large and small. This would be catastrophic for anything on the surface.[citation needed]
Also the moon only affects the Earth's rotation in a small way, fractions of a second per year, so day length will not be noticeably different.
Finally, the moon would re-coalesce, but it would take millions of years. The fragments would reflect light and would be visible at night and possibly even during the day.
[Answer]
First of all, I would suggest that you read [this wikipedia article](https://en.wikipedia.org/wiki/Giant_impact_hypothesis) and [this article](http://www.universetoday.com/127139/127139/). [And watch this youtube video](https://www.youtube.com/watch?v=SC3E6ILOoUQ)
Basically these are articles about the collision of a protoplanet with Earth far back during the early stages after its formation (sometime between 4.5 and 4.45 billion years ago).
An object as large as to fracture the moon would have *extremely* disastrous effects on Earth. Considering that it was a ~10 km long asteroid which brought about an abrupt end to the reign of dinosaurs and their relatives 65 million years ago, the effects of having a *somewhat smaller* (1-3 km) moon piece falling on Earth would be cataclysmic. Talk about giant tsunamis, extreme volcanism, earthquakes ... and nearly 70% of human population would be wiped off the face of Earth (and that is a very generous estimate for survival of our species!).
For some reason, which I am not aware of yes, we have not discovered any Earth-sized or smaller planet with rings. So I cannot say if rings would/could be formed as a result of the debris falling into space and circling the Earth. But hopefully, after all the doomsday apocalypse, Moon would perhaps come a bit closer to Earth and the next intelligent species would see a bigger, larger moon without fearing that it would leave Earth's gravitational pull forever.
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[Question]
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The year is 2089. The political shenanigans of the day have gotten more out of hand than usual and violent zealots have detonated the Earth's largest deposit of *plotium devicide*, an extremely versatile chemical compound that in this instance explodes with sufficient power to destroy the Earth. The planet shatters into millions of pieces, ranging in size from dust particles to moon-sized chunks, which mostly remain tumbling around the sun in their old orbit.
Billions of lives are lost and the Earth's biosphere is devastated beyond comprehension. However, *plotium devicide* can be also be used to construct indestructible bunkers, and several tens of thousands humans managed to survive this catastrophe along with a few decades worth of supplies (they were in the middle of a political crisis, after all). Also, several vaults (not unlike the [real-world doomsday seed vault](https://en.wikipedia.org/wiki/Svalbard_Global_Seed_Vault)) were also reinforced with PD and were scattered, intact, across the shards of the Earth. These contained the genetic sequences of millions of species of plants, animals, fungi, protista, and bacteria, as well as huge reserves of food and useful technology, such as water purifiers, medicine, and equipment useful for agriculture and electrical infrastructure.
The question is, **how screwed are the survivors?** Please feel free to bring up any issues you feel are relevant, but I'm primarily curious about the following issues:
* **Gravity**
+ What would the gravity be like on the surface on some of the larger chunks?
+ What effect would the other chunks have on the gravity you felt?
+ What shape might the chunks form?
* **Atmosphere**
+ Would there be air, or would the atmosphere be lost into space?
+ Would there be oxygen?
* **Surface Features**
+ Would any of Old Earth's surface survive and remain recognizable, or would the event be catastrophic enough to leave no features intact? Remember, the explosion shattered the planet; it didn't vaporize or liquefy it (*plotium devicide* explodes in a highly unusual manner).
+ I'm wondering about mountains, surface water, and (ruined) cities.
* **Civilization**
+ Given the above points, do the humans have even a chance in hell of surviving, and if so, do they manage to organize? How?
Answers should be based in science but creativity is strongly encouraged. After all, the system was contaminated with huge amounts of *plotium devicide*, which could have extremely unpredictable effects. Have fun!
[Answer]
***Don't Panic***
--Hitchhiker's Guide to the Galaxy, Douglas Adams
Seriously though:
## Everybody is certainly dead
Including everyone in the special bomb shelters.
Anything with enough energy to disrupt the Earth - will essentially melt or vaporize the entire Earth - including every biological entity living on, in, or over it.
To give you an idea of the energies we are talking about. The Theia Impact event (something about the size of Mars smacked into the Earth) melted or vaporized the entire Earth all the way down to the core. This impact did not have enough energy to disrupt the Earth's binding energy.
The Theia Impact provided about 2/3 of the energy required to disrupt the Earth.
2/3th of the Energy you described does this:
![2/3th of the Energy you described does this:[1]](https://i.stack.imgur.com/ZVg49.jpg)
[This is a video of an object about 1/1000th of Mars mass (and therefore 1/1000 the Theia impact energy) striking the Earth](https://www.youtube.com/watch?v=bU1QPtOZQZU) - realize that nothing survives this either.
The only way tens of thousands survive is if they manage to be far away from the planet when it happens.
## No such thing as a shattered Earth
Depending upon the specifics of an impact/explosion you might get a shattered Earth for a tiny period of time, but this configuration is not stable. The shattered bits will all be in motion - some falling towards Earth, others flying off.
If the explosion is powerful enough to disrupt the Earth, then the pieces keep on going and the planet disappears. If the explosion does not disrupt the Earth, then it all falls back and we end up with a molten Earth.
Even if the super shelters are strong enough to withstand the explosion (they won't be), the people inside will subject to g forces ranging from 100 - 1000+ g upon impacting other objects. If the shelter doesn't leave the surface of the Earth, then it'll be floating in a sea of molten magma several thousand degrees which should cook the survivors to "well done".
[This video of the formation of the Moon](https://www.youtube.com/watch?v=Fwl_JBQtH9o) gives you an idea of how utterly screwed Humanity would be in such a situation:
### Gravity
If the Earth is actually disrupted (e.g. down to the size of gravel), then it will dissipate. Some will fly off quickly but it will take a while for the rest to leave the vicinity of where the Earth originally was. From a distance, the mass left in the vicinity of Earth's starting position will still provide gravitational attraction, albeit at a significantly lessened level.
Close up, gravity will be squirrely. The mass that's flown past you will cancel out (as if it were a shell), so it really depends upon where you are in the debris field. Assuming your in the middle somewhere you'll notice gradually lessening gravity as you and bits of the Earth fly away from each other.
### Atmosphere
After the Theia Impact, the Earth retained most of its atmosphere and hydrosphere. It took thousands or millions of years for it to all return (it had been blasted into orbit after all), but most of it was not lost to the planet.
You are talking about a more powerful explosion and the atmosphere and hydrosphere are the most volatile components of the Earth. So these will be among the first components lost.
### Surface Features
**None**
If disrupted, the Earth will have no surface features. If the blast was insufficient to disrupt the Earth, then the Earth's surface will be completely molten.
After the initial impact, shock, & splash die down; the Earth's surface will be a nearly perfect oblate spheroid. Meanwhile, debris will continually rain down from orbit - possibly for thousands to hundreds of thousands of years.
### Civilization
Kiss everything up to geosynchronous orbit goodbye.
Humanity had better hope it has created colonies throughout the solar system. A Lunar colony is probably doomed - too much debris from the Earth will end up hitting the Moon.
Even a colony on Mars might have issues with the amount of material that will be flying around the inner solar system.
It might pay to have people put on a generation ship that just flies around trying to dodge this stuff.
## Messing with your premise
We frown on arguing with the questioner about their premise but...
There's only so much energy that you can store in chemical bonds. There is no conceivable way to make a chemical that has unlimited bond strength such that breaking them and reforming it disrupts the Earth (or conversely that this chemical can be used to shield against the equivalent of a 10 x million x million powerful nuclear explosions).
[Atomic Rockets: Boom Table](http://www.projectrho.com/public_html/rocket/usefultables.php#id--The_Boom_Table) shows that the explosion required to do this would require about $1.5 \cdot 10^{13}$ megaton explosions (basically that many large nuclear explosions). If you didn't have the nuclear weapons, then you would need $1.5 \cdot 10^{19} tons$ of high explosives. This is something like 20x of the mass of all of the oceans in the world.
If you write a story with your *plotium devicide* and it has these properties, bear in mind no one who knows physics is going to suspend their disbelief (FWIW, I **have** read good stories that throw physics out the window so I don't want to totally discourage you on this).
[Answer]
The short term effects of shattering the planet would be that much of the atmosphere and liquid water is lost. The amount of energy to shatter the Earth would be between 1.5 X 10^30J (blow off Terra's crust into space) and 2.9 X 10^31J (reduce the Earth to gravel). This is far beyond the amounts of energy needed to blow the Earth's atmosphere and oceans into space, so initially we are surrounded with a rapidly expanding cloud of vapour. (All figures courtesy of the Atomic Rocket's "Boom Table": <http://www.projectrho.com/public_html/rocket/usefultables.php>)
Although I'm not clear how to quantify this, you would also have a very nasty problem as the pressure was released from the Earth's core. Massive amounts of white hot iron would suddenly be expanding into the vacuum of space, potentially coating every solid surface it came into contact with, and providing energy to drive at least some of it out of the Earth's old orbit. From some safe distance in space, you would see a glowing, rapidly expanding cloud of "stuff" assuming a rather weird oval shape. People who sought safety on the Moon are bombarded with splinters of hot, iron coated rock, and a temporary atmosphere of hot nitrogen, oxygen and water vapour also covers the moon (rapidly corroding much of the infrastructure that is in place, designed for the vacuum environment).
The release of energy should also produce a great deal of heat, so the remaining chunks of Earth are going to be heated to such an extent that some of them will be molten, and most will have melted through the surface layers. This heat pulse will also affect the surface of the Moon, although not so dramatically.
As the excitement dies down, gravity patiently takes over. Pieces of the Earth are going to be close together and the larger pieces will have sufficient gravitational attraction to draw smaller pieces towards them. The cascade effect will continue as more and more pieces are drawn towards each other and the Earth begins to reform. Since we have pieces ranging in size from sand to chunks the size of the Moon, the process will be messy and inconsistent, but the pieces will be crashing together at an accelerating rate. Once again, the sheer mass will exert a massive amount of pressure on the pieces caught in the middle, and with the squeeze will come more heat (see a pattern here?), starting the process of melting and the eventual redistribution of the Earth's mass, with iron and heavy elements gradually settling into the new core, and lighter silicates rising to the surface.
It is thought that a great deal of water (up to 3X the amount currently in the Earth's oceans) is trapped in the rocks in the mantle, so we can assume that at least some of that will remain, and the heat of reformation will cause it to be outgassed onto the newly molten surface. An atmosphere of steam will surround the Earth for thousands of years until the surface cools enough to allow condensation and rain.
As for the bunkers trapped in the Earth's crust, unless they have also defied the laws of physics in other ways, they will be quickly roasted by being surrounded by molten rock and unable to shed their heat loads. given the chaotic reformation org the Earth, there is a good chance that some of the bunkers will be reformed far below the nominal crust and will be crushed by the massively increasing pressures in the new core and mantle. Real survivalists will have fled with Elon Musk to Mars back in the 2020's, so after spending a thousand or so years practicing terraforming Mars, they will be ready to return to the somewhat smaller and much drier Earth in the year 3000 to reseed the planet.
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