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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.
On earth there can be hours where the moon is up during the same time the sun is in the sky (daytime moon) due to the combined rotation of earth and orbit of the moon. I would like to have an earth-like planet which never has the moon and the sun visible in the sky at the same time from any point of the planets surface. Is this possible without too much interference with the earth-like state of the planet?
Ideally the reason for the lack of simultaneous visibility does not effect the stabilising function of the moon for the planet's hability as well as has no significant effects on the planets seasons and day and night cycle. In general consider the planet, the moon and the whole solar system to be the same than ours.
EDIT for clarification: Ideally the planet has a
* similar axial tilt than earth (necessary for similar seasons)
* similar rotation period than earth (no tidal lock, necessary for similar day length and day-night cycle)
* similar orbit than earth (necessary for similar seasons)
* similar gravity than earth
If deviations from the former are necessary than I prefer
* stronger variations in seasons (stronger axial tilt) to less sesaons (axial tilt)
* longer rotation period (longer days) to quicker rotation period (shorter days)
* different orbit is ok (but please state the effect that might have on the planet)
EDIT 2: For the sake of this question "visible" means visible to the naked human eye and/or technology available in the late medieval period of our world (ca. 15th century).
A solution using atmospheric conditions are perfectly fine as long as this does not infringe on the habitability of the planet and these conditions are the same from any point of the planet.
EDIT 3: There are no restrictions on the perceived colour of the moon in the sky. It can be any colour, as long as it stays visible in the night and still give some light during the night.
You can postulate any changes to our system that have no or marginal effects like described above and achieve the desired result. If this effect is not achievable with the restrictions declared above, please state why.
[Answer]
**Decrease the brightness of your moon, and make it invisible during the day.**
By making the surface of your moon darker, you reduce its brightness due to light reflection (albedo). Cover it with black lava fields or dark stones. If it's dark enough, your moon should be only visible during the night or twilight.
You can give your moon the same apparent magnitude of objects that appears after sunset.
On Earth, the twilight sky allows the visibility of objects with magnitudes from -2.5 to +4.5.
-2.5 is also the apparent magnitude of the new moon, invisible during the day. Even if we can't see it, the new moon is not totally dark as it reflects the earthlight. But it's hidden by our atmosphere brightness.
An object of similar magnitude would be visible during the night.
According to [Handbook of practical Astronomy](https://books.google.fr/books?id=PLzWUuJbjBcC&printsec=frontcover&dq=handbook%20of%20practical%20astronomy&hl=fr&sa=X&ved=0ahUKEwjMktDflrDaAhVBnBQKHZLSAuoQ6AEIKDAA#v=onepage&q=handbook%20of%20practical%20astronomy&f=false) (p. 402, 403), during a total lunar eclipse, the Moon's magnitude is -2 when the sky is clear, and totality is rather light and still visible. Your full moon should look similar in brightness, except that it won't have the red/brownish color of our Moon (due to the eclipse), it should be dark grey instead.
So, we can imagine having a black moon with a very low albedo, that reflects a very small percentage of sunlight, and that should be invisible from sunrise to sunset.
Of course during the night it won't be as bright as our own moon, and will look more "greyish" than white...
But if it's as big as our moon it should be easy to spot it anyway.
With such a moon, your nights should be quite dark, even during the full moon. You may not see your own shadow. The behaviour of nocturn animals/bugs should also be different, because the moonlight won't be as bright as what we know on Earth.
[Answer]
**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.
There's actually a way to make this happen, but it's done by following the letter of the request rather than the spirit: Have a large, low-density moon that sits in the planet's L1 point (the Lagrangian point between the planet and the sun.) If the moon is big enough and steady enough, the sun is always in eclipse and since the sun can be seen nowhere on the planet, it is also true that nowhere on the planet can both the sun and the moon be seen.
(That's a bit of rules-lawyering, and it wouldn't work for long anyway since the L1 point isn't stable (it's metastable). Also, I'm not sure what you'd make the moon of to be big enough and light enough.)
Taking what I think is the spirit of the question -- with the sun and the moon each visible for some part of the planet -- you come closest with the moon sitting in the planet's L2 point which will keep it opposite the sun in the sky. Unfortunately, that's also only metastable. Also, since the planet has an atmosphere, there will be a thin band around the world halfway between the subsolar point and the sublunar point where atmospheric bending probably makes and edge of the sun and an edge of the moon both visible.
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Is a large moon necessary to stabilize the axial tilt of an Earth-like planet and keep it habitable?
This article suggests that the lack of a large moon would not make a planet uninhabitable:
<https://www.npr.org/2011/11/18/142512088/is-a-moon-necessary-for-a-planet-to-support-life>[1](https://www.npr.org/2011/11/18/142512088/is-a-moon-necessary-for-a-planet-to-support-life)
This article suggests that the super high tides when the Moon was much closer to Earth may have caused life to evolve in vast tidal flats. Thus a large close moon might have been necessary for life to appear.
<https://www.scientificamerican.com/article/moon-life-tides/>[2](https://www.scientificamerican.com/article/moon-life-tides/)
This article also suggests that the early Moon started plate tectonics and plate tectonics may be necessary for life on Earth.
<https://phys.org/news/2015-11-moon-life.html>[3](https://phys.org/news/2015-11-moon-life.html)
So a large close moon early in a planet's life may or may not have been necessary for the planet to be habitable and for life to form. And a large moon much farther out billions of years later may or may not be necessary for the planet to have stable enough climate for life.
So turn your attention to the planet's atmosphere for a moment.
Earth's atmosphere scatters sunlight making it appear to come from every direction and making the sky appear blue. An object has to be brighter than the sky's background brightness to be visible in broad daylight. And during twilight it has to be brighter than the twilight sky's background to be visible.
In the apparent magnitude scale lower numbers signify greater apparent magnitude. It is said that the objects visible when the sun is less than 10 degrees above the horizon have to have an apparent magnitude of -2.5, while the faintest objects visible while the Sun is high in the sky have to have an apparent magnitude of -4.0. The apparent magnitude of the Moon varies from -12.90 when full down to -2.50 when new.
<https://en.wikipedia.org/wiki/Apparent_magnitude>[4](https://en.wikipedia.org/wiki/Apparent_magnitude)
Since the new moon is seen when very close to the sun in the sky, it should never been visible unless the Sun is about to set or has already set, and so should hardly ever be visible when the Sun is. The much brighter full moon should always be opposite in direction to the Sun and thus only been seen at night.
So if the sky scatters enough light to become a few magnitudes brighter, its scattered light should be enough to drown out the light of the moon and make it invisible. Right?
I remember late one afternoon I was near Convention Hall, on the boardwalk of Cape May, New Jersey, and saw what looked like a full moon, as far as I could tell with the naked eye, rising low over the Atlantic Ocean.
And then I thought that a full looking Moon should be nearly 180 degrees from the Sun. But I was seeing a full looking Moon, close enough to full that I couldn't see the difference, not in the night sky, not even in twilight, but in the afternoon in broad daylight with blue sky.
So I turned around and looked back, and there was a red setting Sun low in the sky, opposite to the Moon. Because the Earth is a sphere, and not flat, the ground falls away in the distance, and one can sometimes see objects more than 90 degrees lower than the zenith of the sky. And atmosphere refraction makes objects near the horizon appear to be several degrees higher. Thus I could see the Sun and an apparently full Moon in the sky together.
Bu there's more!
One time I was in a low place, surrounded by hills, buildings, and trees, with much less than a full hemisphere of the sky visible, about 9 or 10 in the morning. And I saw the moon, and it looked round and full as far as I could tell. And of course the Sun was also visible. And it looked like the Sun and the Moon were much less than 180 degrees apart, despite the Moon looking full as far as I could tell. And if the Moon was close enough to full to look full to me, its apparent magnitude was probably close to -12.50.
So the problem is to increase the light scattering of the atmosphere of your planet enough increase the brightness of the sky so that the apparent magnitude of the full moon of your planet is reduced by about 8 magnitudes when the Sun is high and reduced by about 10 magnitudes when the Sun is low in the sky.
So you may need an atmospheric expert to calculate how much water vapor, dust, various gases, etc. you may need to add to your planet's atmosphere to make your planet's full moon invisible in the day sky, and whether that atmosphere will still be breathable.
And you can make your planet's moon a bit dimmer, which would help a bit. Since we don't know for certain how important a large moon is for planetary habitability you might decide to make the planet's moon much smaller than Earth's Moon, or might be afraid to make it too much smaller than Earth's Moon.
But you should be able to reduce the mass of the planet's moon to be considerably less than that of Earth's moon. Then increase the average density of the planet's moon so that the same mass can be within a smaller volume. Those two effects should make the planet's moon significantly smaller than Earth's Moon and thus it would look much smaller and be dimmer at the same distance as Earth's Moon.
And you can lower the planet's moon's albedo, the amount of light it reflects, to make it dimmer. Unfortunately, Earth's Moon already has a low average albedo of 0.137. Dark solar system objects like comets and asteroids have albedos down to 0.05 and 0.05. This can significantly reduce the apparent brightness of your planet's moon.
When the Moon is new and near the Sun in the sky, the Moon's visible side is almost totally in shadow. But sunlight reflected from the Earth, and thus becoming Earth light, does light up the Moon a little and make it a little brighter when it is new. The albedo of the Earth is about 0.30 to 0.35.
Decreasing the albedo of your planet would decrease the amount of light the planet reflects back onto it's moon when the moon is new, and thus will make the moon somewhat darker when new. It would also mean the planet could be slightly farther from its sun and have the same temperature as the Earth. Thus there would be less sunlight for the planet's moon to reflect back to the planet, making the moon dimmer.
I am not sure how well decreasing the planet's albedo would fit in with making the atmosphere scatter more like and obscure the light of the moon during daylight.
So changes in the atmosphere and in the planet's moon might make the planet's moon visible in the night sky and invisible in the day sky and even at sunset.
So making the planet's moon less bright and making the planet's atmosphere obscure the moon more might be enough to make the planet's moon visible during the night and invisible during the day.
[Answer]
Previous answers touch on many of the reasons why it is difficult to accomplish this particular orbital arrangement. I think I can come close but not quite to achieving the arrangement without anything beyond orbital mechanics, so I'll leave this here perhaps as inspiration for further work.
**First Try - Tidal Locking Orbit to the Planet**
My first guess was to tidal lock the Earth and Moon to each other, so that the Moon's orbital period around the Earth was equal to the Earth's rotational orbit. This achieves your desired arrangement, but only for half of the planet. Half of the planet never sees the Moon (so they can never see the Sun and Moon together, but unfortunately the other half always sees the Moon.
**Second Try - Slow Down the Moon's Orbital Period**
Okay, so that didn't work, but there might be another way. What if we slowed down the Moon's orbit more and more (of course at the same time pushing it further from the Earth)? It takes about 1 month for the Moon to go around the Earth, but what if we made this longer and longer until it took approximately a year for the Moon to go around the Earth?
First let's look at what happens to the background stars as the Earth orbits the Sun. On June 20th (summer solstice) at midnight on the Equator we see a specific set of stars corresponding half of the sky. The stars we can see at midnight change ever so slowly due to the Earth's orbit around the Sun until, on December 21st (winter solstice) at midnight, we can no longer see any of those stars. Instead we see the half of the night sky we couldn't see in June. These visible night sky continues to change until, on June 20th of the next year, when we're back to the same night sky we saw the previous June 20th. This is how we define a complete orbit around the Sun.
So now let's consider the a frame of reference with Earth at the center; we are ignoring the sun for now and focusing on just the Earth. The Earth is rotating, but we can also ignore this for now, since it is not important. The winter solstice night sky is to the left and the summer solstice night sky is to the right. From here on out we'll call the summer solstice night sky stars, Distant Stars. Place the moon in the center of the winter solstice sky, to the left of the Earth and let it orbit. We have the configuration, Moon, Earth, Distant Stars. In 6 months the moon has moved the center of the summer solstice sky, i.e. the configuration is now Earth, Moon, Distant Stars. In another 6 months the moon has moved back to the center of the winter solstice sky, back to Moon, Earth, Distant Stars. But the Earth is going around the Sun! What does the entire Earth, Sun, Moon system look like?
We are now going to put our two scenarios together. To aid in visualization I've included this following image.
[](https://i.stack.imgur.com/hszSR.jpg)
In this image, the winter solstice sky is again to the left and the summer solstice sky (Distant Stars) is to the right. We know how the Moon, Earth, and Distant Stars change over a year, so we can use this image to help add the Sun in. On Day 1 (in the picture) the order is Moon, Earth, Sun, summer solstice midnight stars. 6 months later, we know Moon needs to be between Earth and the Distant Stars, but the Earth is also now on the other side of the Sun, and we have the order Sun, Earth, Moon, Distant Stars. In both cases the Moon is opposite the Sun! And if we think about it a bit longer we realize that the Moon is always opposite the Sun!
To see how the Moon moved in a single day, we can return to the image. If you continue the line from the Sun point to the Earth, beyond the Earth you can place the Moon there. You can see the Moon is still rotating around the Earth, with respect to the Distant Stars, but is doing so at such a slow rate that the amount of rotates around the Earth exactly matches the amount the Earth has rotated around the Sun!
**Alas, Houston, We Have A Problem**
In theory you can obtain your desired arrangement by slowing the Moon's orbit down to be 1 year, as I have shown. However there are a few problems. Due to Kepler's Third Law, the Moon is now approximately 5.6 times further away than before. It is probable the Earth cannot hold onto the Moon that far away, given the gravitational effects of the other planets, or the Sun. Even if the Earth can keep a grip on the Moon, at those distances the effect of the Earth's gravity compared to the Sun's gravity may be close enough in magnitude, that you might need to treat this as a full 3-body problem! This means we cannot use Kepler's Laws or simple assumptions like treating the Moon and Earth as a single 2-body problem, and then the Sun and Moon+Earth as a separate 2-body problem.
Apologies if this is a little rushed, if there are questions I can return to elaborate and maybe work on some more of the math.
[Answer]
**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.
If the planet is massive enough and its orbital period around its star short enough then it may be possible. If the moon is orbiting around the planet in the same prograde as the planet around the sun, and the moon's orbital period lasted exactly a year, then it would be plausible for the bodies to be permanently eclipsed (theoretically), however, practically, it is not actually stable because there is nothing keeping the moon in check. But you never know; our moon has almost the exact same apparent size as the Sun, allowing for a very cool solar eclipse, and that's completely by chance. While perhaps improbable, it is certainly possible that the Moon could stay in that state for quite some time under these circumstances.
EDIT: just saw your edits mentioning the planet being similar in gravity and orbital period to Earth, so this won't work for your purposes.
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I think the answer is straight-up no. For the moon to be constantly on the opposite side of the Earth from the Sun, it could not be in orbit around the Earth. I would have to be
1. in orbit around the Sun,
2. but further out with a greater orbital radius (to be on the other side of the Earth), and
3. it would have to have the same [angular velocity](https://www.vcalc.com/wiki/vCalc/Angular+Velocity+Magnitude) going around the Sun to stay on the opposite side of the Earth.
It all falls apart on the third item. You can use [Kepler's Third Law to calculate the orbital periods](https://www.vcalc.com/wiki/vCalc/Keplers+3rd+Law), and it is impossible to have the same period and different radii.
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You can put the Moon in a [Molniya](https://en.wikipedia.org/wiki/Molniya_orbit)-like orbit. A Molniya orbit is a very eccentric Earth orbit which turns with the sun. An small Moon can have an eccentric orbit that keeps it in the day side of the planet at apogee (therefore invisible due to distance and presence of Sun) to fly by the night side at perigee.
However there are a couple of caveats:
* To synchronise that orbit with the Sun, the real Moon is also needed. Therefore, that satellite won't be "the Moon" but just a lesser satellite.
* It may still be possible to see Sun and that satellite at sunrise or at sunset.
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[Question]
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The scenario: an alien crew has a shuttle landed on Earth in the 1980's. Their main ship is extremely damaged and beyond reach somewhere in the Milky Way. Their shuttle cannot escape Earth's atmosphere. They are in an unpopulated forested area to avoid encountering the locals, which would be both a galactic crime and unsafe. Earth's gravity is uncomfortable but livable. Their air composition is similar to ours but with slightly different composition.
The shuttle is mainly for scientific observation, transportation between ships and space stations, and emergency evacuations. Its weaponry is limited to its scanners being adapted into energy weapons. It is designed to survive entry into a planet's atmosphere, but it is not capable of escaping its orbit.
The crew has begun transmitting a distress signal, hoping it reaches a stealth satellite belonging to the galactic republic that Humanity doesn't know about. Humanity is seen as a primitive pre-FTL race and as such their solar system is analogous to a nature preserve. Nobody will come save the stranded aliens if they don't make contact. This galactic republic has done some research and common Human languages are in the catalog for the crew's universal translators.
Their level of technology is somewhere between Star Trek and Star Wars - they have FTL travel, but limited replicator technology (it can't rearrange matter at the atomic level) and no transporters.
So back to the question: what would this shuttle be equipped with to facilitate survival? The gear mostly assumes the use of the shuttle as a home base. Here are things I have come up with so far:
* Training materials. Like videos or holograms with an AI acting as the lecturer. Teaches the crew about survival and the legal ramifications of cultural contamination.
* The shuttle has various scanners built in to study the surrounding environment. They also are able to get biological samples and have them analyzed, which in turn allows them to create drugs and immunizations.
* Atmospheric filters, making the outside air breathable to the crew inside the shuttle.
* EVA suits for the crew and a decontamination area before exit/entry of the shuttle.
* Various rations (similar to MREs) and liquid filtration systems for food and hydration. Cooking equipment. They also have a decontaminated tent to set up outdoors which has a bioengineered fast-growing nutrient-rich algae to farm if the local vegetation is inedible.
* weaponry similar to our survival rifles (except energy-based) and knives for hunting and self-defense. Also, fishing rods, slingshots, nets, etc.
* Various tools like shovels, flashlights, fire-starters, compasses, multitools and the like.
* Power cells for energy devices and solar energy gatherers.
* Medical and personal care equipment.
* Storage and gathering equipment.
* Climbing gear and harsh-weather clothing.
* Entertainment sources.
I eventually want the aliens to leave the shuttle and not need the EVA suits while on Earth, so I imagined that being accomplished in one of two ways after scanning the environment: genetic modification or some form of technological enhancement. For the former, maybe the shuttle AI can develop gene therapy and apply it to the crew via some sort of vector (viruses or nanomachines perhaps). For the latter, maybe a cloud of nanomachines fills their lungs and makes the outside air breathable.
Anyway, are any of these ideas too implausible? What do you think would be in their survival kit?
[Answer]
The existence of replicators means you don't need most other tools. They would carry a stock of elements to use with the replicator. If they decide they need ropes, they replicate ropes, etc.
Their main provision would be **information**. Things they don't need to know in normal situation, such as many different ways of making tools and materials with limited and specific selection of local feedstock. For example, they ask for climbing rope, and the regolith outside the door that they shovel into the hopper is completely lacking in phosphorus and nitrogen. It can’t just spit out polymer fibers, but needs a recipe to handle that.
Or, they need rope **that works in local conditions** of temperature, pressure, corrosive environment, etc. So it needs a recipe that won’t melt in the stuff that falls as rain, get too brittle at night, etc.
They would also have information stores for building up larger scale industry than the replicator can handle directly. The replicator can spit out steel when fed ore, but that’s only a few grams at a time and takes time. They want tons…so it replicates parts for machines to fabricate parts to build a smelting furnace. And the instruction manual of what to do with the stuff and effect the bootstrap process of larger scale machines.
[Answer]
## An alien survival kit would be stocked in line with the prevailing philosophy of the culture behind it...
Cultures such as those frequently featured in the Star Frontiers RPG or Andre Norton's various sci-fi novels of exploration and discovery (for example, the Solar Queen series) would focus on survival, communication, and trade items:
* Emergency food and drink
* Purifiers for local edible materials
* Anti-poison / fungal medicine plus other common medicines / first aid items
* Distress beacon and/or communicator of some kind
* Energy conversion / storage units for powered devices
* How-to and DIY records for using primitive materials, tools, and methods to survive, should such not be standard training
* Defensive and/or offensive items
* Trade items that might catch the attention of 'primitives' (sparkles such as gems, beads, glass, marbles crystals and other non-biological stuffs such as stone or metals that won't cause an allergic reaction, and perhaps a musical instrument, though that can be fraught with social risk)
* Portable shelter
* Useful tools
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Cultures which follow a philosophy more like Star Trek's Prime Directive (non-interventionist) would focus on different things, depending on to how extreme a degree they took such a philosophy:
* Hiding and stealth options
* Items which can be destroyed or decomposed into non-useful and non-revealing remains
* Suicide / self-destruct options
* Assassination tools
* Hacking tools
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Finally, a culture that focused on conquest might also provide tools for a forcible uplift of a primitive society:
* Detailed records on how to achieve a high tech level in the shortest possible time
* Weapons and armor guaranteed to secure the position of local war-lord
* Drugs for mind-altering / mind-control
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A culture that espoused a Survival-of-the-fittest philosophy might not provide anything in the way of a survival kit at all, expecting that any stranded individual had better make it out on their own, or they don't have the right to live in the first place.
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**Given your lower-end replicator technology**, the following would be critical:
* a stock of rare and supplemental elements not commonly found in nature,
* an extractor unit of some kind to collect and sort elements,
* a detector unit of some kind to find sources of elements and distinguish various grades and concentrations,
* a power source / converter / collector of some kind which can gather and store power with which to recharge the other units,
* most importantly, a data unit with replication templates to convert the various elements into. A backup would be wise.
* some sort of repair unit would also be a good idea to upkeep all the units.
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Other possible combinations are possible, as each unique culture would add or omit items based on the predominate philosophy of the culture, or organization, from which the stranded aliens come from. After all, a civilian survival kit would differ drastically from a military kit, which would again differ from a spy's kit.
Of course, it would not do to omit the most universally useful item of any and all survival kits anywhere in the universe...
## ...The Towel
[Answer]
On top of @JDlugosz answer (upvoted) I would point out that, since the aliens are not allowed to make contact with "aborigens" for many reasons, including legal ones, there are a few concerns:
* Some way to mask their operations from locals inspection (our planet is constantly monitored for anomalies both locally and from space).
* Better communication equipment than a generic "distress signal" which sounds akin to a message in a bottle thrown int the ocean. If you need them to be trapped for extended period of time, for plot reasons, you should justify why they can't "phone home".
* If their marooning on Earth is to last they will need some way to interact with "locals" without being recognized, either via effective disguise or via some purpose-built android.
* Rationale is they might need "refueling" for their replicator or things it cannot produce; chance of this happening (or replicator breakdown) increase with time, of course.
* Alternatively they could start another wave of "vampires" plaguing some already "infested" region (e.g.: Transylvania) and disguise it as a P.R. trick to attract tourists. Many variations on the theme are available.
As always much depends on your plot needs.
[Answer]
# Multi-purpose
I once read a Sci-Fi short story which title I cannot recall and most details are also blurred in my memory. What they did extremely well was the generalisation and multi-purpose use of the tools of a similar escape bot. Actually, the only detail I can recall is *a fishing rod* nee *local transmission antenna* nee *tent stand* nee *metal rod for self-defence*. What was is really? A telescopic thin tube of metal, similar to a rod antenna, sturdy enough when collapsed, long enough when extracted.
I would guess that all tools in your survival kit would be either this insanely multi-purpose (even if troubling some of the functions) or made on spot with some super-tech.
# Experience
At least on Earth all survival and tech repair kits are supplemented basing on the experience of survivors. So expect these some items that are not really plausible, but may have helped once someone to survive.
There was another short story by Divov (Russian Sci-Fi kicks back!) when during a mysterious course of events, astronauts/cosmonauts in a space station only survived because one of them smuggled a sledgehammer (sledgehammer, Karl!) on board. The guy who did it was severely punished. But since then a sledgehammer is an integral part of a tool kit on the station.
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So, I would expect things like "why are they packaging hundreds of square meters [insert your galactic units instead] of a thin isolating plastic film that also doubles as a photovoltaics battery, can be used as emergency blanket, and can repair holes in space shuttle walls if combined with *that* superglue?" Don't we have our super-proton-fusion reactor on board for power? (It was improvised sometimes earlier by a stranded group whose reactor broke.)
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Beyond the obvious rations, weapons, water, medicine, shelter and clothing, you would have to have some means of hiding from the indigenous life like a portable holographic generator, invisibility cloak or better still a [SEP field](https://en.wikipedia.org/wiki/Somebody_else%27s_problem) generator.
The other thing you would need is some kind of interstellar [EPIRB](https://en.wikipedia.org/wiki/Emergency_position-indicating_radiobeacon_station) so you can get help because space is very big and finding someone is extremely difficult.
I doubt they would rely solely on replication because it would require significant energy and would be tapped into the ship's power supply which might not be working.
[Answer]
**Nothing.**
Supremely competent boy scout aliens are boring. They are well prepared for every eventuality and deal efficiently with their situation, blah blah. Where is the story?
No, these aliens are the victims of a disaster. The shuttle was being used as a storage shed, was not ready to go and the refugees made it away from the ship by the skin of their teeth. The aliens themselves are mostly pure scientists who expected to have a scientifically and professionally rewarding sojurn observing Neptune; they are impractical, irascible geniuses with soft hands. By good luck the escapees include the ship's hydroponics expert and the sexologist, who are a little more capable.
Everything they need must be MacGyvered up from things that happened to be on the shuttle (what's in those boxes, anyway?) and what they can find, steal or trade for on Earth.
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[Question]
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## Prelude
**Prelude TLDR; A fleet of ships is passing through our galaxy, stopping off at particular stars and causing small dips in the light from stars.**
This is related to a couple of other questions (and a little suspension of belief to make it fit the story I want). The other questions are [refueling](https://worldbuilding.stackexchange.com/questions/79376/refueling-from-stars) and [detection](https://worldbuilding.stackexchange.com/questions/79543/detecting-objects-around-other-stars).
So the idea is that explorers from another galaxy have sent a fleet of their ships into ours - the ships need to refuel regularly by [collecting fusion fuels from red giants](https://worldbuilding.stackexchange.com/a/79406/36817) (I've decided the ships also use the light and heat from the stars so I can 'explain' using stars rather than gas giants for fuel).
The fleet$^{\dagger}$ obscures some of the light from a star as it collects the fuel, making a [small dip](https://worldbuilding.stackexchange.com/a/79545/36817) in the intensity of the light we receive from that star. Then it moves on, using up fuel to power cryo, travel, AI etc and then stopping to survey and refuel at the next red giant.
$^{\dagger}$ One big ship can have a large volume without presenting such a large area to block out light. As explained in [this answer](https://worldbuilding.stackexchange.com/a/79545/36817) we need a large area...so I'm making it a fleet with a main mother ship rather than one big ship.
## The situation to reality check
As the fleet pass through our galaxy they obscure very small amounts of light to the point where they're *almost* lost in the noise of solar flares, sun spots and general brightness changes (I'm going to say they orbit their chosen star fairly quickly so we can fold the data and get a better signal).
A scientist in my story has come across this unusual trend of a small but very regular dip which appears for a specific amount of time, then disappears and turns up in another system...this trend seems unnatural to our scientist but has been overlooked by others. For the sake of argument I'm going to say that, so far, the ship has passed three star systems in the hundred years of data our scientist has but if you think he needs more I can change this.
**I want our scientist to decide this is a sign of intelligent life and track the path of their ship (joining up the dots of red giants) and send out a message to them by predicting where they will be when a message can get to them.**
(I want this message to include information about the star system he thinks they'll be in and information about ours so they can find us...but that is just background and for another question).
**So how realistic is it that he would be able to track their path? Does he have enough information about their movements to predict where they will be?**
(I'm aware he will be long dead before the aliens reach us, I want to give humanity generations of expecting the Aliens before they actually arrive).
**Edit: I was imagining slower than light travel between stars and the initial group of red giants being close to each other.**
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My first issue is: A hundred years of data - in a hundred years, detection and filtering technology should advance a lot (if we start from a point during which a large fleet around a distant star is observable), so it might be a bit hard to justify that fleet being "almost lost in the noise" both at the beginning and the end of that timespan. But maybe funding for space sciences was cut and no new developments were made.
Second: three sightings is definitely not enough. If it's almost lost in the noise, other possibilities would be considered more likely and that scientist would be seen as a nutjob - those three stars were probably close to each other, so anything from a thin nebula crossing the line between us and them (dimming the light slightly) to those stars having various separate reasons to dim (planetary collission throwing up debris and dust? stellar activity variations? who knows) would seem a more likely explanation than "a fleet large enough to dim a star". I don't know where I'd draw the line, but we'd definitely need more than three sightings. And the "nebula with varying density between us and those stars" theory would likely hold power well into the double digit of data points.
Third: tracking their path... tracking would be simple, but not prediction. For this they would need a clear goal they're working towards, rather than going to the nearest interesting-seeming star. Or very specific criteria for "interesting". If they're coming right for us (or planet XYZ) and only deviating slightly from a straight line to refuel, it would be doable. If they're always going to the nearest yellow star that wouldn't require backtracking, then too. Exploring with a wider area of possible interests would seem too erratic for a clear prediction.
And lastly: how far away do you want that fleet to be when it is detected? Our closest neighbouring star is 4 light-years away, but the edge of the galaxy (the close edge, mind you) is some... 24 thousand or so light years away, I think. Any signal he could send without FTL-technology would take a year to travel a lightyear, so if he discovers them while they're still far away, he'd better be REALLY good at his predictions, have a VERY strong signal source, and be very lucky to have those aliens listen for exactly the kind of signal he intends to send, too. If he has to hit them with the signal while they're between star systems it gets even harder - less crew awake, ships likely in power conservation mode, and less time spent in any given location than while they orbit a star. And he might have to do that, since he can't slow down or speed up his signal so if the aliens are X lightyears away, the signal will travel X years. If the aliens will be right between two stars in X years and it will take them years to decades to get to the next star, would he be willing to wait those years or decades before sending his signal?
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# Time is against you
The [nearest red giant](https://en.wikipedia.org/wiki/Arcturus) to Earth is 37 light years away, so the signal he has is at least 37 years late but more likely about 10,000 years late. His signal to them has much the same problem.
Your scientist is looking for the dips in light from specific stars, the light from those stars takes 1 year to reach him for each light year it is distant from him. Hence the use of light years as a measure of distance. Considering him to be on Earth, the nearest red giant is 37LY away, so 37 years before the dip in light from that star reaches us. Given that the Milky Way is around 100,000LY across, even if the passing fleet is *relatively* close to Earth, only 10% of the galaxy away, the fleet would have passed 10,000 years before the scientist would be in a position to notice that it had done so.
Assuming that any species capable of intergalactic travel won't be moving STL between stops:
* If they're moving towards him, they're already past him by the time he notices they're coming.
* If they're moving away from him, his signal can never catch them.
My instinct says that he can never get a message to them, due to the double lag of starlight and speed of light messaging.
* If they don't go straight overhead then the light from the stars has to travel further and slower.
* If they do pass straight overhead then they're travelling faster than the light anyway, so he still doesn't detect them until they're gone.
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I'm no astrophysicist / astronomer, but wouldn't your scientist chalk this abnormality up to some combination of:
1. Observation error / Statistical anomalies
2. Solar system debris (meteors, comets, kuiper belt objects, asteroids, and etc.) transiting between the target stars and Earth
The odds of them believing they've just observed evidence of a massive fleet of space ships seems infinitesimal. The odds of them ever even mentioning the data anomalies -- much less claiming they're alien ships -- seems even smaller.
If they tried to make the scientific claim that they were intelligently powered devices, that could well be the end of their professional career.
Also, given the three dimensional nature of space, how hard would it be to even get this effect to be observable from Earth, across stars in a pattern we could see? Remember, stars are not equidistant, so the ships might transit one star from our point of view, but then go behind the next three before transiting another (for example).
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As mentioned; we already know there are rogue planets and possibly even black holes out there. Is the fleet in question cover an area the size of Jupiter?
Why wouldn't the better explanation be that these red giants have large planets orbiting them, with total orbit duration > 100 years? We already know most stars have planets.
Plus, a straight line to Earth eyes may be a triangle in 3-d space; and a closest-neighbor walk for the aliens would seem like a drunken walk among stars to us; until we map them in 3-D to see a clear path.
**That said,** I think a solution to your problem may exist: Make the changes to the Red Giants, as made by the aliens, produce a more permanent feature which your scientist can observe, and might plausibly be the first to measure. for example, a particular signature combination of reduced or increased elements in the spectra of the red giant; or something else permanently observable about the star. As if the aliens extract something useful from the star necessary for their propulsion, or manipulate the star in some way.
Then your observations can be *millions* of years old; covering hundreds of stars, and your scientist's measurement clearly partitions red giants into Mined vs. UnMined, and furthermore he can see the nearest-next-red-giant path in the 3-D map. There is no natural explanation for such a well defined path; it must be due to intentional selection.
Then further than that: He can see, by comparison of current spectra to spectral observations taken less than 100 years ago, that the last two red giants on only one tail of this path were the most recently changed, just a few decades apart, the last point just a few years ago, so the **next** star on that path is one we could signal in time to communicate with these aliens before they arrive.
Perhaps further plot developments allow him to measure the trip-time between red giants, say he discovers a subtle decay rate in the spectral signatures, and using that he discovers the aliens sometimes travel at light speed, but other times take decades longer than expected before arriving at the next red giant: He concludes they must stop and visit places for some reason, perhaps they discover life, or just something else worth mining besides red giants.
Feel free to use that if it is useful; I am just spit balling here...
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You would need to observe the giant all the time to notice it.
And MOST IMPORTANT. They would not see it. Because there is a thing called lensing. The armada would need to be very close together to obstruct the light from star. The closest to star they are the smaller portion they cover.
Than, it's also another problem. Your scientists would need to be specialist in the field of sunspots to distinguish the ships from the real sunspot.
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**I don't see this working out**
To cause a measurable dip in the light curve of a star, you need to blind a non-neglible area of its surface. The choice of red giants makes this especially hard, since they literally are giants with a giant radiating surface. We can currently barely detect super-earth size planets orbiting *small* stars closely.
Also, short time orbits around a red giant are completely impossible. The sun, for example, is expected to expand to somewhere near earth's orbit when it reaches its red giant phase. That means the shortest possible orbit will be around one year. And thats assuming the ships basically scrape on the surface.
Then there is the issue of stellar winds, red giants have strong stellar winds, causing condensation of tiny dust particles in the winds which can dim the starts light easily enough to be detectable (observed decades ago). This makes observing any transiting bodies harder, as there are more sources of noise. Same goes for the star itself, red giants have a very thick outer layer where energy is transported through convection, adding another source of noise.
Then you are assuming an unlikely distribution of stars:
"I was imagining slower than light travel between stars and the initial group of red giants being close to each other."
Red giants are comparatively *rare*. There are multiple reasons for this, one is that small stars, namely red dwarfs (which form the majority of the galaxies population) do not go through a red giant phase, and those that have enough mass will not do so before the universe is many more billion years old. Next is that the red giant phase is short, compared to a stars lifetime spend on the main sequence. This means three red giants *close* to each other is not common. Another good indicator is that there are no red giants in the suns immediate neighborhood.
The general problem is that its hard to believe the fleets combined coverage area would be, lets say as large as the moon - unless you plan the technology level to be in the realm far beyond current physics, ships will not be moon sizes, not even large asteroid sized. The absolute upper limit would be where the gravity from their own mass *forces* them into spherical shape (for natural bodies this is somewhere around 400km diameter).
You propose a *fleet* of smaller ships instead, this relaxes the problem a bit, since the physical structural limits do not apply to small ships, and you get more surface area for less mass. But it brings up new questions: Each ship would have its own systems, making it largely or entirely self reliant. So why would the fleet consist of a huge number of ships? The logical way to build the individual ship would be to make it just as large as needed to perform its mission. Splitting functionality between multiple ships (e.g. tankers, maintenance and passenger ships) would only worsen their mass efficiency and make the system more complicated, as it adds the requirement to interact with each other frequently).
Then there is the aspect of signal travel time. By the time your scientist would observe whatever effects of the alien fleet, the observed position would be decades to millenia old. Then sending a message to the fleet takes the same amount of time it took the light from the fleet to travel to the scientist. By the time he could possibly get an answer he would have already died of old age. The galaxy is *huge*, the light from stars in the center takes approximately 27000 years to reach earth. So if your alien fleet isn't in the immediate neighborhood of earth (or wherever your scientist lives) this will not work, the timespans involved are just too long.
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The best way to travel to another galaxy is to go very fast. The actual time is long but the subjective time is not.
Once you get to the new galaxy you have to slow down. Red giants may be good for that; they are not dense so you could be going literally through their outer layers. This could be observable depending on the size and weight of the ship. I think a moon sized ship plowing through a red giant star at nearly the speed of light would be noticeable. Perhaps smaller for a less noticeable affect.
Lets also assume they are by chance heading nearly straight toward the observer and by the time they get close their speed is perhaps 1/2 the speed of light or less.
Given these conditions, signalling them would definitely be possible. The line would be pretty straight due to the momentum so you could predict the path, especially if you were pretty sure they were aiming for the next red star in the line.
The initial encounters would arrive at nearly the same time since both are so close to the speed of light, the latter events would have more and more time lag as they slow down.
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Imagine you had a flat earth scenario, in which the world is essentially a giant disc floating in space (I know that in reality any such world would be pulled into a sphere by gravity, but for the sake of the question assume that gravity just pulls "down" instead of towards the center of mass). Now direct your attention to the edge of the disc: without something to stop them, all of the air is just going to pour over it, leaving the planet incapable of supporting life.
What measures could be taken to prevent that from happening? One thing I've thought of is placing giant mountains along the entire rim, tall enough to hold in the whole atmosphere, but I'm interested in whether there are any other passive solutions that would work in the real world (ie, no magic or teleportation).
**EDIT:**
A recurring question seems to be "why wouldn't the Earth and everything on it be falling at an equal speed?" Let's hand-wave it away by saying that the Earth is already at the "bottom" of the universe, and so cannot fall any further. Things on the top, however, can still slide, jump, or fall off and then descend through space until they reach the "bottom" too. Arbitrary, yes, but I think it allows us to focus more on the question itself: *how* do we keep the atmosphere on top of the flat surface, besides adding huge mountains around the edges?
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The whole universe could be filled with air. That would also explain why the world isn't just in free-fall (and thus effectively gravitation-free): It is going at the limit speed where air resistance equals gravitational pull. Of course it would still not explain why the air doesn't fall as well.
Note that the effect for an inhabitant of the world would be that beyond the border of the world there's a strong *upwards* wind. Probably eddies would cause an outwards wind near the edge of the world.
**Edit:**
In response to your edit of the question:
If the universe has a bottom, and the flat earth rests on it, the filled-with-air universe gets even more plausible. Especially, there's no need for it to be *completely* filled with air; the air just sits on the bottom of the universe, and the flat earth is inside that universal atmosphere. For an observer on the flat earth, the only difference between that and the eternal-falling earth model is the absence of the off-earth wind (and the absence of needing to hand-wave away why the air is not falling as well; it's not falling because there's a bottom).
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If your flat earth has a somewhat normal gravity, whether artificial or by having something like a super dense ring at the edge that balances the normal center-of-mass direction, **the atmosphere would just be present on both sides of the disk and around the edges**.
There would likely be intense storms at the edge because of clashing jet streams, so to the inhabitants, the other side would be invisible. If the bottom side is also inhabited, an occasional unlucky explorer might mysteriously end up on the top side, thrown there by a storm.
From your edit, I assume that the "gravity" of the Universe overpowers that of the earth itself, causing anything that is not at the "bottom" of the universe to fall down. That of course leaves the question of how much air is reaching the bottom or is already at the bottom, and what else is there.
If the "bottom" is like an infinite flat plain that only receives some pockets of matter when a flat planet or gas cloud reaches the bottom, the air falling off the earth would spread out so thin it would not be noticeable, essentially lost forever.
If on the other hand the amount of air having reached the bottom of the Universe is big enough to create measurable pressure, the air could be reclaimed in some way at the bottom of the flat earth. That might be true if the bottom receives new air and water in balance with the natural dispersion on the bottom. Of course, that would also mean the earth gets new air and water falling on top of it.
A kind of stone with thin channels might absorb the water (and air dissolved in it) through capillary action, though I'm not sure it would work against this universal gravity.
Or there are world trees growing roots down to the bottom, where they absorb water and air through osmotic pressure, after which they evaporate/expel the water and air from their leaves as part of their metabolism.
Neither of them would seem to balance the loss of atmosphere from the sides if there's not *some* barrier there, though they would make up for some loss.
Since you have already handwaved away some major physical laws, you could perhaps declare that air pressure isn't a thing in that universe. So the air is not pushing itself to the edges, it only falls off when it some bit of it is pushed over the edge.
Finally, if the flat earth is artificial, it could have either some force field (solving all issues by handwaving again) or an air recycling system where the air falling off the sides is captured some way down along the the edge, filtered (to extract any intrepid explorers and their balloons) and transported to a mountain or otherwise in the middle of the disk's surface. This would result in a constant wind from the center of the disk to the edges, making any air travel one-way and very risky.
The problem with reclaiming air in any way is "what is out there past the edge of the planet?", because no regular pump or suction device is going to compete with a vacuum out there. The closest I can imagine is a combination of strong ionizing radiation and shaped magnetic fields to force the now charged particles into openings in the side of the disk.
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Assuming your 'planet' orbits a star you will need your flat earth to rotate in someway to get a day/night cycle.
I can see several possible methods. Please don't shoot me on the science behind them, there are just theories.
1) The Frisbee.
Your flat earth rotates around the central point. This will bring certain points closer and further away from the sun over the 'day/night's cycle. This scenario doesn't really give you full night.
There is also the orientation of your flat earth to take into account with the Frisbee. Is the whole surface facing the sun, or is the sun perpendicular to the flat earth. So the rays are coming side-on. The first would give you more an eternal day while the second would give you more of a night time(twilight) than face-on.
This rotational around a central point will also create different gravity fields the further away from the centre you get. Think of artificial gravity fields in rotating spacestations.
2) The Frisbee Wobble.
Combined with the Frisbee method above, but with a wobble. This will allow the sun to be blocked by the raised edge of your flat earth.
3) The Coin Spin.
Your flat earth is spinning on its edge. This spin will allow full day night cycles.
You can have your spin perpendicular to the sun (but that doesn't really give you your day/night cycle). I'm going to work with the spin axis in line with the orbit axis.
**Rotation combined with atmosphere.** So now you know how your flat earth spins. You can use 'simple' gravity and physics to work out how your atmosphere and water etc will stay on 'planet'.
With the Frisbee, the rotational effects should limit the atmosphere from flying off into space. Think of spinning a bucket of water around your head. The water stays inside even though it is horizontal. Hmm, this relies on a bottom to the bucket. So this would be your mountain range you mentioned.
The wobbly Frisbee may be more helpful. Here you would have the atmosphere spinning around, as it spins it extends further into space. However this time, the upward wobble of the flat earth rotation *could* increase the friction and create a 'temporary' barrier to the atmosphere. It then slides back onto the earth and moves towards the downward facing edge. By the time it gets there...It will be upwards facing again. This will likely make your central regions have more atmosphere than your outer edges. So the outer edges could have the same affects on plant and animal life that very high altitudes do.
The spinning coin has the chance to completely encapsulate your Flat earth planet in an atmosphere -much like it does for a round ball shaped planet. The atmosphere would be thicker on the opposite side to the direction of the spin. Ie, if your spin is left to right, the thicker atmosphere should always be on the right hand side of the coin.
Any water that fell over the edge of the flat earth would be caught back in the underlying section of the 'planet'. It wouldn't be lost. The same for erosion. Your flat earth could potentially erode along the edges but the rotation spin could move sediments from the one side to the other. You could have some countries growing smaller, while their far distant cousins on the other edge could be growing. Gives a new meaning to country stability! But erosion like that takes thousands of years so it would not be too noticeable.
This atmosphere could even cover the bottom edge, and with such a spin you could actually walk over the edge of your planet and walk 'upside down' on the underside. So you can use both sides of your flat earth (gives a whole new meaning to digging a hole to China!).
Regardless of which rotational device you choose, it would be very windy on your flat earth. Good luck working out the climate!
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Does gravity still push down if you are on the other side? Maybe, gravity will still pull things towards the ground, so that things that fall off of the disc will stay near it. As for the world eroding at the edges, it could be that if you get far enough from the edge, gravity shifts in direction to push you back towards the world.
I know that this does go beyond real world physics, but you did already establish that the direction of gravity can be changed, so it doesn't go beyond the physics of your world.
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Maybe it doesn't matter if the air "falls off" as long as enough air is "falling on" at a suitable rate. Think of a waterfall filling a lake while at the same time the lake is draining into a river.
This could also be extended as an idea to explain various seasons on your world caused by the rate of falling air changing.
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Sounds similar to: [What would make scientists realize they were on a flat world?](https://worldbuilding.stackexchange.com/questions/42387/what-would-make-scientists-realize-they-were-on-a-flat-world/42567#42567)
In your classic flat earth model, everything revolves around the earth. The atmosphere stays in place because it's already as close as it's going to get to the earth, so there's nowhere for it to move *to*. You'll still need a ring of mountains around the edge to present dissipation/evaporation, but that's it. Think of it as a shallow bowl.
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If this is a three dimensional earth (just very thin, but with tall three dimensional structures on one (only one?) of its surfaces, then I have no answer.
If, however, this is a two dimensional earth existing in three dimensional space/time, then the very nature of gravity in this scenario prevents the air from escaping off the "side" of the disk earth.
My argument is: Imagine a two dimensional rubber sheet as space. Two dimensional earth sits on this sheet and its mass distorts it through a third dimension, causing it to sag down forming a cylindrical depression. The depression represents the gravitational field. The field occurs at every point on the surface, which is hard to visualize, but that is not what we are interested in. We are interested in the effect at the edge, which is easy to visualize; any particle trying to exit the side of the earth encounters the steeply curved space/time sheet and must climb out to escape. Which means any item trying to escape the edge of the earth encounters a gravitational field that resists its escape. Or, to put it another way, escape off the edge encounters the same gravitational resistance as escape up (even though "up" doesn't mean a thing to the denizens of this world).
Or maybe its better to say, the vector of escape in such a world is off the edge, not "up".
As I said, however, this is a solution for a two dimensional world in three dimensional space time. Perhaps, however, this will suggest a solution to someone else...maybe using spacial distortion as part of the solution.
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Two different answers spring to mind.
First, the world is the 'flat' of a petri dish. This is how we deal with providing 'flat worlds' for our experiments with bacteria - we supply walls to stop the agar from dripping off.
But that's not very interesting...
How about the flat earth not having edges at all? If you walk far enough south, you end up in the far North... If you walk far enough East, you end up in the far West... The world is flat, Jim, but not as we know it...
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So here's the scenario, a mad scientist has just managed to take over the continent on his campaign for world domination (which continent I will leave to your imagination but for simplicity lets say north America or Europe). While his armies fend off any outsiders trying to intervene he must now consolidate his power before he can continue his conquest which to him means repairing and updating his newly acquired infrastructure. Among the updates is the continents old and outdated railway system, easy for a genius in the fields of physics and engineering. As he repairs and upgrades it he reaches a dilemma when he starts to draw up plans for his super broad gauge intercontinental network. Should he build his network from scratch using two conventual rails or remodel existing double track lines to accommodate his broad gauge network?
A conventional 2 rail network would be simpler to build and it would be separated from smaller standard gauge save for large freight depots and passenger stations which would share the gauge on the same track. It would also allow the lines to be built along straighter and faster routes compared to conventional rail allowing faster access from points A to B and have infrastructure designed to accommodate the size and speed of such trains (for reference the gauge our mad scientist has in mind is 14-16 feet wide). And the scheduling would be more efficient as broader gauges would move at faster average speeds and not have to worry about running into slower freight and passenger train. On the other hand modifying existing double track lines would be theoretically faster as you would just need to refurbish existing track and remodel existing infrastructure rather than build from the ground up. The 4 rails would also allow for better stability at speed and greater weight distribution for the new locomotives and rolling stock. The new equipment could even be made to interchange with smaller 2 rail standard gauge equipment. For example, 2 standard gauge locomotives could haul super broad gauge cars and a single 4 rail locomotive could haul two trains of standard gauge cars. This would allow a broader application of the new rolling stock. And the 4 rail plan has the most room for growth as our intrepid mad scientist plans to do the same for quadruple track lines and maybe even 6 tracks lines.
You may ask yourself "wouldn't highspeed rail networks and super sonic aircraft be better" and you would be right, except that this is a mad scientist were talking about so things like practicality and efficiency are very warped in his mindset. Not to mention he has access to technology that is at least 200 years ahead of anything have and the whole concept in of itself is just plain cool. So what do you think he should go with, super broad 2 track railroad, super broad 4 track railroad, or perhaps some combination of the 2 concepts?
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If he uses a pair of existing standard gauge tracks as a four-rail single track, he's going to hit a lot of problems:
* The most obvious is that the spacing between pairs of tracks has been managed for different reasons to running trains on all four rails. Those include clearance on bends to avoid side-swipes due to the length and width of waggons, clearance required on straights to avoid side-swipes due to the Bernoulli effect sucking trains towards each other and the need to minimise overall width to keep costs down. Your mad scientist is going to have to get all the track adjusted before he can use it for double-width trains and doing the job hastily is likely to cause problems for single-width trains.
* The less obvious is that there are all kinds of solid objects between the pairs of tracks, such as signal posts, station platforms, and trees. So he's going to have to get the track re-organised for that.
* A painful problem is the points for switching trains between different tracks. All of that assumes that trains are occupying a single track, and most of it assumes the other track in a paired track is used in the opposite direction. This requires re-designing all the track intersections then re-laying them.
* Worst, bridges and tunnels have been built assuming that double track has two separate trains running on it, so there will often be supports between the two lines, and the height clearances won't be adequate for super-sized trains. It's very unusual for bridges and tunnels to be built over-size because it increases costs.
* All the signalling needs to be re-designed to cope with double-width trains taking up two tracks, especially if single-width trains are allowed to run on the same tracks.
* If he wants double-width trains to be able to run in both directions, he's going to need to lay new tracks anyway. The amount of long-distance standard gauge four-track line in existence is tiny. Being able to run trains in both directions increases both capacity and safety a *lot*.
Overall, it's going to be a lot easier to lay new routes. These can be super-broad gauge, or pairs of standard gauge. Designing a line that uses pairs of standard gauge tracks to allow running two standard gauge trains as an alternative to the wide trains won't be too hard, and allows all the existing rolling stock to be used on the new routes. Of course, you need more complex signalling to cope with that.
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**Let's think about the physics of rail gauges...**
1. The wider the gauge, the shallower the turn radius. The distance between wheel trucks is involved here, but the simple reality is that the wider the base of the vehicle the greater the drag on the outside wheels when turning. I don't know if trains have ever designed independent suspension and axles, but if you've ever driven in an old-fashioned 4-wheel drive truck (a real 4-wheel drive truck where all the wheels are locked to rotate at the same time) and tried to turn on a dry surface, you'll understand what I'm talking about.
*NOTE: @Separatrix points out that unlike automobile tires, rail wheels are conical. This likely increases stability (aka, helps keep the train on the tracks), but it also means the train can take a tighter turn than it would with cylindrical wheels because the outer wheel in a turn has a slightly larger diameter than the inside wheel. That's uber-cool! But it doesn't completely solve the problem. It does mean that my 4-wheel-drive vehicle metaphor isn't as useful as I thought.*
2. As the number of rails your train sits on increases, the weight an individual engine or car *could* handle increases. This is all about weight distribution. Trains already do this to a degree by adding axles to the wheel trucks, but weight-per-square-meter counts, so there's only so much distribution you can achieve by doing that on just two tracks. See issue #1 for why you can't just add more trucks (it lowers the turn radius). Having two more rails on a wider total gauge would seriously increase the weight-bearing capacity of the train. But, *conversely,* the wider you make your 2-rail wide-gauge system, the *lower* the amount of weight you can carry due to the mechanical limitations of widening the trucks.
*Note: This assumes we ignore other factors that are equally important when it comes to weight distribution: the towing capacity of the engine(s), the friction of those engines on the tracks, the grades encountered, the weight bearing capacity of the rails, the strength of the tie plates and spikes, the weight bearing capacity of the sleepers and ballast... but you could believably ignore all that as an assumed improvement that came along with the multi-rail wide gauge.*
3. The efficiency of the engine traction-to-rail system. One of the many reasons why motorcycles are so efficient is that the *drive train* (the whole power transfer from the motor to the surface of the road, not just the chain or drive shaft) is small, small, small. Your wide-gauge rail system increases the distance between the motor and the surface of the rails, lowering the efficiency of the motors. From a practical perspective, the reasons for not building super-duper sized trains are similar to those against building super-duper aircraft carriers. There comes a point where the efficiency of hauling cargo is subverted by the inefficiency of moving it at all.
**Yeah, yeah... but wouldn't multiple rails allow me to go faster?**
Not as much as you might think. What you gain in stability you'll lose in friction to the rails and wind resistance. It's cheaper from a high-speed train standpoint to have a *longer* train than a *wider* train. The only reason bullet trains aren't thinner than they are is the mathematics of center-of-gravity become ugly when the object becomes too much taller than it is wide. In other words, this wide gauge idea is great for hauling breathtaking amounts of freight, but not a useful idea for high speed transport.
*But couldn't I get around that by making my super-fast, super-wide train short? As in, a meter off the ground kind of short?*
I ask that rhetorical question just in case someone thinks of the idea. I have one word for you, just one word: *airfoil.*
**Besides, in the end, technology is almost always second to economy**
I've mentioned many times that too many worldbuilders ignore *economy.* The economics of operating a business of any kind (no matter who's paying the bill) will always drive the adoption of technology. The coolest anti-gravity fusion-powered train won't be used for anything other than an advertising gimmick until the cost of operating that train (including the consequences of derailment...) become cheaper than that of operating diesel engine trains. A hugely simplistic example is this: if the fancy-dancy engine cost 20X a conventional diesel engine, then it had better haul 20X the load or haul the same load 20X faster (rails permitting, which they aren't) or it's not worth buying.
So, would your business mogul choose a two-rail wide gauge vs. a four-rail multi-gauge? That almost answers itself, but the first question is, *would the mogul choose to use a wider gauge in the first place?*
The answer is almost certainly "no," but let's ignore that question due to *[narrative necessity](https://worldbuilding.meta.stackexchange.com/q/7281/40609).* It's already too late to turn away from the choice! In that case...
* What are the costs of converting existing track to the multi-gauge vs. replacing existing track to the single wide-gauge?
* What's the cost of replacing every engine... every car... with the new two-track wide gauge versions?
* How long can the existing track and assets continue to operate and how much will their value decline due to the inability to haul enough cargo or travel fast enough?
**Occam's Razor says economics will dictate a multi-rail, multi-gauge replacement every time**
I love Occam's Razor, the Law of Parsimony expressed by a 14th century Monk who was probably trying to impress the abbot with his efforts to get out of chores. In a simplistic (and somewhat disingenuous) paraphrase, it says...
>
> All other things being equal, the simplest answer is usually correct.
>
>
>
Not ripping up existing track will always be cheaper than ripping up existing track. Replacing it directly would require one whale of a good discount from the rail, engine, and car vendors or an equally good increase in transport revenues — which are generally unlikely, assuming the mogul could get the financing to do it in the first place.
[Answer]
>
> So what do you think he should go with, super broad 2 track railroad, super broad 4 track railroad, or perhaps some combination of the 2 concepts?
>
>
>
**Neither of the above**, really.
The problem with any form of super-wide railway is that it offers no advantages over standard gauge, but does so at higher cost. At the minimum, the right of way would need to be made wider too. If the track needs to run in a cutting or on an embankment, those would need to be made bigger, as well as any bridges it passes over. Greater stability at speeds is cheaper to achieve by tilting the track; weight distribution is cheaper to achieve by making the train long rather than wide. Coupling standard gauge and super-wide rolling stock on a two-track railway only works as long as both tracks are at a constant separation everywhere, with no inconveniences such as e.g. station platforms or bridge pillars in between them; those would need to be removed and the tracks realigned. All in all, it's just so much hassle for no good reason.
But of course the scientist is mad, so if he feels compelled to do *something*, then he would be less badly served by a separate super-wide rail network built from scratch.
[Answer]
## He will pick "the most complicated option"
Have you ever met a real model train enthusiast? The OP is assuming that a mad scientist in the process of taking over the world is choosing his train track gauge petsonally rather than letting *some other person who is a train enthusiast* choose.
The only possible explanation is that this is not only a mad scientist but a mad train enthusiast.
**Once we have deduced this, it is obvious that *the train set is the ends of world domination*, not just the means.**
He or she (just kidding, blatantly he) may be self aware, or may still believe that paying attention to the paintwork on each platform the same sort of attention as several military divisions really is necessary, but in the ultimate analysis it makes no real difference.
The train system won't be chosen for speed: "My trains aren't slot cars!". Nor for cost: "We're doing it nicely, not cheaply".
It will be chosen for some combination of the following:
1. How similar that gauge or its proportions are to e.g. 1910s Welsh Railways Ltd locomotives (insert different era here).
2. Feedback at his preferred online forum, or possibly, club day.
3. How well the gauge looks with the existing real life 'accessories' like stations, park benches, and countryside.
4. What consumes an amount of time that is maximised subject to not actually triggering a divorce.
To the non train enthusiast, this looks like making things as complicated (but oddly satisfying to look at) as possible, but that is most unfair.
[Answer]
How about the [Breitspurbahn](https://en.wikipedia.org/wiki/Breitspurbahn) ? That proposal had a 3m track and double-height rolling stock.
[Answer]
## Existing double-track doesn't play by your rules
While John Dallman's answer speaks to why a "generic" double-tracked railway (with relatively constant track centers) won't work for your contraption, real double-track/multiple-main railway lines can easily get *worse* than the "generic" case. Case in point: between Victorville and Hesperia, the main tracks of the BNSF Cajon Subdivision *cross over each other*, with one track on a bridge over the other. Quoting from the [timetable/special instructions](https://www.multimodalways.org/docs/railroads/companies/BNSF/BNSF%20ETTs/BNSF%20CA%20&%20LA%20Divs%20ETT%20%233%203-26-2008.pdf#page=13) for that line:
>
> **Rule 6.26**—The main tracks cross at the grade separation at
> MP 39.1 and are designated as prescribed by Rule 6.26 on
> either side of the crossing.
>
>
>
This isn't the only place this is known to happen either (there are three other places in the Western US alone that I know of: one northeast of the Salt Lake City area, one southeast of Tucson, and one in Colfax Canyon northeast of Sacramento that's particularly notable as one of the tracks is *in a tunnel* while the other track continues over the top of it at grade). Furthermore, even if you don't have to worry about Main 1 crossing over/under Main 2, there's no hard limit on how far apart those two tracks might be from each other, and there are quite a few places on the US rail network where they are *miles* apart. (There's also a place in Texas where the two main tracks of a double track section of line *cross each other at grade*. Think about *that* for a minute.)
[Answer]
As somebody who likes drawing broad gauge trains: I've scaled down my system's size many times. I started with 5 metres, but that was just ridiculous.
I halved that to 2.5 metres (the width of a truck is either 2.5m or 8 foot, depending on its age, but keep in mind the train is at least a metre wider than its tracks so tram lines still needed the lane they are in to be much wider than the others)
And currently, I do 2 metre gauge, which is actually narrower than Brunel's track gauge was.
So, I would recommend you do about 2.5 metres, up to maybe no wider than 3 metres. That is the gauge that a particular evil person was thinking of building in the past (as has been said by other comments)
A note: people in the answers keep using feet as a measure. Just replace every instance I said metre with "yard" and you'll be close enough! :P
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[Question]
[
Unlike mammals, reptiles lack gluteal muscles and instead have enlarged caudofemoralis muscles to extend the hindlegs. The humanoid legs, on the other hand, rely on the mammalian gluteals in order to function
Is there an alternative muscular structure that allows for humanoid legs that are moved by the musculature of a reptilian tail?
The system can't have muscles that aren't found in either reptiles or mammals, and each muscle must have a realistic amount of strength. The legs should be as strong as human legs. The tail must appear roughly contiguous with the body from the external perspective, and hence there shouldn't be any visible buttocks.
[Answer]
# Like a Frilled Lizard Baby
[](https://i.stack.imgur.com/MyB4q.png)
Frilled lizards have reptilian musculature. I know because they are reptiles. And they can run upright. [Check it out.](https://www.youtube.com/watch?v=rLY2gNiOFzk)
[](https://i.stack.imgur.com/yrhmW.gif)
[](https://i.stack.imgur.com/RTqhf.gif)
This is not exactly what you want. I don't believe the lizard can *walk* on two legs. Only run. They stay upright when at top speed.
But it proves the concept works. Just make some qualitative adjustments to your lizardman's anatomy so they can stay upright while walking or standing still.
**Edit:** In the comments @AustinHemmelGarn says the frill is unnecessary to stay upright. [Chinese water dragons](https://www.youtube.com/watch?v=HMisC_OQOwk) run like this too.
[](https://i.stack.imgur.com/ljYqC.gif)
[Answer]
## There is nothing that exists, but there is no reason it can't exist.
Upright bipedalism is unbelievably rare, even more so with downward facing femurs, so no actual examples exist.
the closest match would be therizinosaurus. Which puts right angle turn in the hips to have an upright spine and tail. But dinosaurs do not have ball and socket hip joints to their range of motion is limited. but there is no reason you could not add more musculature and have ball and socket hip and a angled pelvis with tail. Developing new muscles is very easy and happens all the time in evolution, so that should not be an issue you should worry about.
as a side note mammals have a caudofemoralis and archosaurs have glutes, they are called ichiofemoral muscles, they are just small.
[](https://i.stack.imgur.com/Bjupe.png)
Keep in mind having a tail means balance requires the body to be slung forward. so you will never have completely upright and a large muscular tail. there are several questions about bipedalism and tails, I suggest you look at them for details on how to make it work.
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[Question]
[
My setting is a standard rotating ring space station. I want some action to happen in the core, specifically for the hero to take down a "hypercom" system that is housed there. I'm trying to understand what else would be happening/functioning in the core itself.
This station is on the frontier of known human space, orbiting a planet where they are mining needed resources. There's a good-sized population on the station and it has 5 decks. The station has all the normal stuff you need to live - sleepovers, food joints, bars, stores for sundries, and even some luxuries.
I suppose I could just make up whatever - but I'm wondering for a structure like this, what would make sense to be in the center? I assumed communications equipment was one. What other functions might be there that even possibly benefit from the zero-g environment?
**EDIT: THANK YOU.**
**I just want to say I love this community. I'm a creative, and I write sci-fi, but I'm no engineer or science guy. I'm sure sometimes my questions seem basic, but they are vitally important to my story. I really appreciate the thought put into the answers and the discussion. Please know that it helps IMMENSELY. I wish I could put this where everyone would see it, but hopefully some folks see this at least. Cheers!**
[Answer]
**Like any good building, all your maintenance and infrastructure doesn't consume valuable space**
Look at today's high-rise buildings. Where do you find the HVAC, the fire suppression water storage, etc? Either in a basement or on the roof. That building is expensive! Every cubic inch of rentable office space given over to power panels and fluid controls is lost revenue.
All that stuff would be in your core.
* Energy generation, storage, and control
* Communications & computer processing
* Sewer/recycling processing
* Water storage (although in space that might be more valuable in the hull as a radiation shield, but you can never have enough water in space)
* Atmosphere processing (HVAC on Earth, a bit more complicated in space)
* Food/goods storage
* Maintenance workshops (metal working, electronics repair, etc.)
* Freight "elevators" (transport) between levels (much easier at zero-G)
I think you'd also find things not maintenance related that you simply don't want to waste simulated gravity space for.
* Security, jurisprudence, & high-value safes/vaults
* Medical (e.g., convalescence and anything else you can do at zero-G)
* Administration
Finally, never sell the idea of zero-G recreation short! Nothing would be more fun than a game of Zero-G Laser-Tag or a roller coaster that takes advantage of the environment.
I think your protagonist would find a whole lot o' stuff in that core.
[Answer]
## Docking and Storage
Rotating station designs almost always assume docking is at the core to make lining up with the station easier and to limit disruption to the station's spin. Also, since you mention this is a mining station, we can assume that it's intended to store a significant mass of cargo compared to its living space. When you add weight to a spinning station, you increase the already powerful forces that threaten to rip it apart; so, there is no reason to waste ring space on storing the countless tons of materials that your station is holding onto waiting for the next space freighter to come and take it away. This could also be very helpful for loading and unloading if your core is under dramatically reduced apparent gravity.
## Sensors, Antennas, and Other Outboard Systems
In general, the control rooms for these systems will still best be placed in the ring making them easier to use and service for human technicians, but the stuff on the outside of your station like the telescopes, antennas, and anything you would have to do a spacewalk to fix would be much better mounted to the core. Space walks are dangerous enough without the risk of being flung off into deep space... so while I don't think it makes since to make the control room for the Hypercom system in the core, it does make a lot of since to make the actual transmitter/receiver sticking off the core somewhere.
## Maybe Certain Kinds of Refining
I'm generally of the opinion that if you are mining on a planet, it is way cheaper to make your refining facilities on world, and only export the now much lighter refined materials. That said, it is possible that if your civilization has a need for very precise meta materials, that it would be better to finish refining these materials in the vacuum and/or zero G of space. So, certain refining processes may be best done in the core depending on what they are mining.
## Nothing Else of Importance
If you are using your core for docking ships, moving around massive cargo containers, and possibly running high-energy refining processes, this means that the core section is also the most hazardous part of your space station. A ship docking a bit too hard, a 1000-ton container drifting into a wall a bit too fast, a refinery explosion... these are all risks that could damage your core section killing everyone in the area, and disabling nearby systems.
It's also harder to use most tools in zero-G; so, maintaining any sort of critical inboard systems in the core becomes much harder than if they are in the ring where you can use your weight to control the tools you need to work on them.
In other words, if it does not need to be in the core, it's generally best to put in in the ring
[Answer]
# Zero G
These are systems that you'd want to put in a non-rotating section of the space station. For smaller stations, you might be able to get away with just the actual center axle, but for larger stations, you'd want a large non-rotating section (let's call this a "drum"), and trains that speed people up to rotational speed to transfer between them.
## Pressurized vs. Depressurized
This is a tech level consideration. For barely space age tech, you may not be shipping cargo around enough to make large open spaces useful. For Star Wars levels of advancement, your air lock is a forcefield, so you'll be able to move your entire ship into a pressurized space, making the point moot.
For those in between, having a hatch or gangway that people use to board and exit the space station can avoid requiring passengers to suit up, and can avoid lengthy delays while people cycle through air locks.
This is not always practical for large loads, and you may not even want to put them in a pressurized area. For that purpose, you'd want big areas of depressurized space close to where ships can dock
### Docking
The most important role of the hub of a spinning space station is the docking complex. It provides a place for vehicles to attach without having to deal with centrifugal forces trying to throw the ship off. This is always best done right at the gravitational axis for smaller space stations. For stations where you might want more than two ships docked at once, you need a drum to manage all of the docks.
### Trans-shipping Storage
As soon as you have space-based manufacturing, you have space based warehouses. This was done really well at Tycho station in The Expanse, where they had huge immobile volumes filled with trans-shipping containers that just stayed in one place. This is just a reasonable place to store goods coming off of a ship, while they wait for the outgoing ship to be available.
While there is undoubtably plenty of space to put this kind of thing outside of the station, you would want it to be close to where the cargo ships can connect to the station via a gantry. Higher value space would exist inside a [Whipple shield](https://en.wikipedia.org/wiki/Whipple_shield) to protect from micrometeorites.
### Light manufacturing
Most manufacturing facilities would want to be on a separate station/platform where they aren't in the way of docking and transportation, but there will always be some cases where a finished good is best stored disassembled, and assembly is done as close to the location of use as possible.
# Low-G areas
These are things for which a gravitational bias is beneficial for giving people something to push off on, or for keeping things sitting on a surface, but for which you don't really want full G of the outer sections.
### Environmental systems
This is partially water storage, but also the systems that provide atmosphere for the rest of the station. Just like on Earth, you always want to store your water uphill so that it goes where you want it on its own.
### Local warehousing
This would be a pressurized area where goods are stored after they've arrived, but before they're distributed. It would be full of small appliances and vehicles, building materials, furniture, and other things that are used up in the normal course of living. Pressurization makes it easy-access, and light gravity keeps things from floating away.
### Groceries and sundries
Let's face it, it's easier to push around a shopping cart if you can push against the ground, and the cart doesn't weigh too much.
### Athletics
You might want an area where the residents can do low-G obstacle courses and the equivalent of geriatric swimming.
[Answer]
## Industrial Systems
Lets imagine this space station is a massive ring and the center is slowly rotating. We can compare this to most high-rise buildings, as just like an office tower, its key to make the most of the useful space, and not waste it on pesky things like air conditioning. (Or life support.)
## The Systems
Life support. Lets check off an obvious one. Every station needs air, and by extension, lots of tanks of algae and probably some gas liquefaction and air circulation equipment.
Water and waste treatment. You'll need systems in place to burn waste, presumably with plasma torches, recyclers or just plain dumping it out the side of the station. Unfortunately, water is heavy and hard to import, so you want to reuse it as much as possible. The coriolis force might actually help with this.
Energy and information distribution. Every apartment building has some kind of power and fibre-optic distribution panel. You'll need the same on your space station. Unfortunately, you don't have a city grid in space, so you will need fusion reactors, fuel tanks and most importantly, **radiators**.
Refineries and cargo. Of course, your station orbits a mining colony. It would make a lot more sense to have a specialized station to handle all the cargo, but refining becomes easier with incredibly straight-forward access to hard vacuum and zero gravity.
You could do the heavy refining planet-side, but making advances super-materials usually require strange environments, and the processes usually need to be manned, even if the majority of the work is automated, so putting it **in** your station makes sense.
Communication and navigation. You'll need laser comms, radar, laser targeting and lots of other systems to keep orbital collisions to a minimum. You might also need it to connect to arrays of laser or kinetic close-in weapon systems around the edges of the ring to defend the station or shoot/vaporize incoming debris.
Engines and main propulsion bus. As your space station is in orbit, it experiences a tiny amount of drag and its orbit will slowly decay. To counter this, the station needs some kind of station-keeping engines, probably on the "walls" of the ring and in the core of the station.
Active shielding. Lastly, you'd want some sort of magnetosphere around your station to deflect solar wind and dampen cosmic radiation. Sure, a lot of metal between you and it helps, but putting dedicated superconducting rings around the core will give your station its own magnetic field and splash incoming charged particles to either side.
[Answer]
**Observation station.**
At the hub from the top and the bottom you can see the entire sphere of the universe, minus a small nearby area where your view is occluded by the ring of the station. It is important for the station to track incoming objects - ships doing business, possible aggressors, as well as objects which might impact and damage the station. Observations from the hub are not complicated by movement of the observation equipment, as would be the case elsewhere on the station.
The hypercom is there too, for the same reason - it has a clean shot to receive and transmit from the rest of the universe. Equipment situated elsewhere on the ring is moving, has the ring occluding part of the field of view, or both.
[Answer]
# Power Plant
The station spins to generate gravity. The middle of the station has zero gravity. It is where we make electricity, by shooting particles into each other with great speed and precision. The calculations are tricky. Best do them where sunuvabitch Isaac Newton cannot interfere.
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[Question]
[
In my world, I have these things called 'voids', for lack of a better name. These voids are absolute nothingness.
What I'm having trouble with is what they'd look like from the outside. No light = black, no color = white. Light is needed for color, so black *should* trump white, right? Whould it even look like anything, or would it be invisible?
[Answer]
**The brain of the viewer will fill the void.**
Nothing. Bleh. It is hard to make that interesting to the reader. But what if in the context of absolutely nothing, the brain stepped in to fill the void?
<https://en.wikipedia.org/wiki/Closed-eye_hallucination>
>
> Closed-eye hallucinations and closed-eye visualizations (CEV) are a
> distinct class of hallucination (technically a pseudohallucination
> since there is generally awareness that the perceived experience is
> not real). These types of hallucinations generally only occur when
> one's eyes are closed or when one is in a darkened room.
>
>
>
In your world when you look into the void, the void looks back. And you can see it looking back. In the absence of real inputs, the brain invents seen things. People know what they see is not real (it is not real it is not real) but they definitely see things down in there. Looking into the void might be a source of inspiration or meditation. Or it might be a thing to be avoided at all costs.
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Absolute nothingness is, by definition, colorless and transparent. In an area of nothingness, there is the absence of anything to emit any light (or anything else) and the absence of anything that changes the color of any light (or anything else) passing through it. In short, absolute nothingness would look like, well, nothing. Moreover, if you had a volume of absolute nothingness on your world, it would immediately cease to exist because the atmosphere and light entering it makes it no longer absolute nothingness.
Now, let's say that your volume of absolute nothingness instead instantaneously erases the existence of light, matter, and anything else that enters it. Then it would be the most perfect black possible, since no light can be emitted from such a region or pass through such a region and there is nothing within it to reflect light. If you want to see what this might look like, look up pictures of <https://en.wikipedia.org/wiki/Vantablack> ; the visual effect is very startling.
(As an aside, such a destructive void would also be rather problematic, since air would constantly be rushing into it and being deleted, not unlike a large vacuum cleaner. This would eventually consume the entire atmosphere of the planet, rendering it lifeless.)
If you want a more fantastical take on it, you might consider cribbing Larry Niven's description of hyperspace, as best I recall it: The human mind utterly couldn't comprehend it so a person looking out a window in a ship in hyperspace would perceive everything around the window but not the window itself; it was as if where one side of the window frame ended, the opposite side immediately began. One of the characters places himself in a situation where his entire field of vision is hyperspace and his mind simply locks up until another character jolts him out of it.
[Answer]
For a void to be 'absolutely nothing' it would have to be in a universe with absolutely nothing. You can not have a void when there is anything 'not void' around it.
If there was anything around the void, then it would be sending radiation of some sort through the void, and then the void would not be absolutely nothing. It would have something - the radiation going through it.
So either your void is contained in a universe that allows nothing in or out, or it can not be a void. That is, the void would have to be surrounded with some completely impervious 'membrane' that makes it, well, its own self-contained universe, with its own infinity in which there is, well, nothing, and which is surrounded by nothing, and that nothing goes on for infinity. As soon as you can 'see' anything, anywhere, in that void, even if it is on the 'outside', it is no longer a void.
So in that sense, you are perfectly entitled to have trouble with what this void would look like from the outside. There could be no 'outside' to a void since that 'outside' would result in something inside the void.
In that sense, since the void would have to be completely contained in its own universe, surrounded by a membrane which in fact does not constitute anything inside the void (you could not see the membrane from inside, there is nothing to see), you can make that membrane anything you want from the outside. You would not be looking into the void, you would be looking at the membrane, the boundary to the void. Make the membrane anything you want from he outside - invisible, opaque, red, a glowing orb, white, black, polka dots, camouflage, absolutely anything you want. It is not until you go through the membrane, or at least be part of it (sort of like putting your face right up to a bubble without actually bursting it - you see the outer surface of the bubble right up until you are part of the bubble) that you are in the void, and then you would see - nothing. Not even the way out. But then it would not be a void any more if you were in it.
But if you are interested in the human perception of nothingness, then research the [ganzfeld](https://ganzfeld.co.uk/2015/11/ganzfeld-effect).
>
> ‘Ganzfeld’ is a German word for a featureless field. The Ganzfeld
> effect is a phenomenon where a person of normal sight is unable to see
> anything after staring at any featureless, monochrome field for even a
> few seconds. This is a normal response from the (human) brain when it
> is starved of any stimuli.
>
>
>
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Absolute nothingness would be close to the conditions inside a [**sensory deprivation tank**](https://www.wikiwand.com/en/Isolation_tank) and should produce no sensory stimuli at all. Perhaps, some 'magic sense' can still be stimulated if necessary. Most likely, those voids would be invisible. However, you can opt for something else to make things easier if voids have to be detectable.
I think it could be useful for your project to take a look at various concepts of folded spaces and personal dimensions and their visual descriptions. These are especially common in Eastern fantasy (storage rings, dimensional rifts, etc.).
[Answer]
# **You want something that is LESS than nothing.**
The very essence of non-existence, not the mere absence of existence.
NO, I'm not talking about antimatter, which is merely another equally valid mode of matter that just has a politcal disagreement with normal matter.
The great sage Terry Pratchett gives us a few glimmers of this concept in his Holey Texts, yclept "Diskworld".
In these Texts he mentions the concept of approaching an absolute, and *breaking through* it to achieve the opposite thereof.
For example: Drinking enough Klatchan Coffee not only makes a drunk person sober, but over-imbibing of it takes the drinker to a state *opposite* of drunkenness, into "Knurd".
This is a prime example of what you are looking for. Something that is not merely the absence of a state, but the diametrical opposite. OP now just need to extrapolate this concept into light,darkness, and the concepts of visibility.
(The Great Sage also directly discussed the Anti-light beyond mere Dark, but quoting that to the OP would not be productive. Too direct, too easy. For after all, did the Great Sage not also say *"Build a man a fire, and he will be warm for a day. Set the man on fire and he will be warm for the rest of his life"*? )
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If it's truly nothing it won't be visible in any sense of the word: you won't see there's a space or anything missing, any gap or absence of continuity. To be nothing it must have no dimension we can perceive.
Imagine you have a park bench that sits three. Abe is sitting in the left seat, Barb in the right. In the middle: a nothing. To the outside observer Abe and Barb would appear to be sitting immediately next to each other; the only hint a void is between them would be an odd compression of the background between them.
This doesn't mean voids can't be interacted with, and Barb or Abe may try to reach over to touch the other. They'd think it odd they can't seem to reach far enough, but visual compression strikes again. Their hand and arm would appear (from their perspective) to be fully extended and still fall short, though their neighbour appears mere inches away.
[Answer]
**Black. Wait$-$**
Provided the void simply eats up everything that enters, it will also eat up light. Hence if you look directly at the void, no light can enter your eyes from that direction, either by reflecting or passing through the void. So you see a black opaque area.
**But:**
Depending on how the void eats stuff up, you will see stuff happening along the edge of the blackness. For example if the void eats up air that enters the edge, then more air will immediately rush in to fill the gap left behind and there will be a shimmering effect. On a smaller scale if the edge eats up part of an atom then the rest might shoot off and release energy. So perhaps a corona of light and radiation similar to a black hole.
Essentially the humanity sprites from Dark Souls.
[](https://i.stack.imgur.com/MqLA6.png)
[Answer]
there are two voids (and a lot of shades in between), the true absolute, which has to block everything from going there, or a false one, which is all around us, it lets things through, like particles and other things, but is nothing on its own, and there are also are many shades in between, a perfect vacuum, out of any gravitational field etc. with a perfect, wave proof material, would be a very close thing, but energy and some other forces are still there
[Answer]
This depends on a few things.
1. How long do the voids last, if they are only an instantaneous event that immediately gets filled in by the matter around them, they are transparent and are immediately followed by a loud explosive boom as they implode from the air pressure around them.
2. If they persist, then are they keeping everything out or pulling everything in endlessly and not letting anything out.
If they keep everything out and stay empty they are either prefect reflective mirror like surfaces, nothing can enter so everything must be reflected off the surface, OR they bend everything including light around them and are completely invisible except possibly for an edge effect if the edge is a gradient.
If things enter and cannot escape like small blackholes then they will look like the name implies, small pefectly absorptive black voids, take a look at vanta black to get an idea of how weird that looks, just be aware you can't see it on a computer screen. They will also be a a center of a small tornado as the air endlessly rushes into them, so you probably won't be able to see the black surface for all the dust and debris.
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[Question]
[
Nuclear fission rockets are becoming obsolete and have been superseded by the more efficient antimatter engines, which have nearly 100% efficiency and do not produce pollutants.
I'm wondering this: in a space battle that takes place within the solar system, is there any place for nuclear powered spaceships, or do they belong in space museums?
[Answer]
In wartime, quantity is a quality of its own.
You do not need ideal weapon during war time. You just need more of it than your enemy.
Given that:
* Fission fuel is easier to obtain than antimatter as you can dig it on homeworld or other celestial bodies
* There is no natural antimatter source, at sufficient quantity, in solar system
* Fission fuel is easier/cheaper to store than antimatter, as it does not explode when touched nor requires fancy EM cages
* Fission process, and its failure modes, is well known
* Ships explode from enemy fire more often than from reactor failure
* low energy/time cost to start up reactor, just move those rods a bit and you got juice
You should be able to build, and fuel, more fission powered ships which will give you an edge in combat.
However I'd suggest adding fusion to your list of reactors, as it should be a stepping stone between fission and antimatter annihilation.
* multi purpose fuel. All you need is (heavy) water to provide oxygen, reactor fuel, reaction mass
* Hydrogen is very easy to obtain (for spacefaring society) as you can get it from oceans, atmosphere, ice asteroids, gas giants, or even from solar wind
* fuel can be shared with antimatter (mother)ships
* clean energy, when compared to fission
* you need water anyway
[Answer]
(A couple options -- feel free to use either or both!)
## Stability
Antimatter is *really* finicky about how it's contained. High-G combat maneuvers and delicate magnetic bottles are not friends, and even a minor bit of battle damage to the bottle is an all-but-guaranteed loss of ship with all hands. Fission is much easier to keep stable in combat, and containment wobbles or damage have much less catastrophic failure modes.
## Expense
Antimatter drives are far more expensive compared to fission drives. So they're fine for something like a capital ship, carrier, or large transport, but smaller, short-range craft like tenders, shuttles, and fighters, and especially expendable craft like drones or missiles, still use much cheaper fission drives.
[Answer]
Yes, I think that there might be no nuclear fission powered ships, but nuclear fusion ships will still be there. Or maybe there will be hybrid ships that can run on fusion or annihilation.
The reasons:
* There are no known natural occurrences of antimatter (at least not in amounts that could be useful for spaceships), so you can't harvest antimatter, but have to produce it. The production will probably run on solar energy in a Dyson sphere or by using a fusion reactor
* On the other hand, hydrogen that is needed for fusion reactors is the most common element in space, so you can easily siphon a star to fill up the fuel tanks
* Antimatter is super dangerous. You might not want to transport your antimatter inside of your spaceship. You only need to have a failure in one of the magnetic traps or a shock that causes the antimatter to touch normal matter and your ship will be blown up. So the best strategy might be to have an unmanned reactor ship that contains antimatter and flies in a safe distance to your main ship. That ship somehow produces hydrogen and can send probes to the main ship, so the main ship can run on much safer fusion energy.
[Answer]
>
> Nuclear fission rocket is becoming obsolete and is superseded by the more efficient antimatter engine, in fact there will be no pollution and the efficiency is around 100%.
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Unfortunately no.
Firstly, you can you create your antimatter. The pesky [law of conservation of baryon number](https://www.nuclear-power.net/laws-of-conservation/law-conservation-baryon-number/) means that in most cases your maximum efficiency of antimatter creation will be 50%, because for every antiparticle your energy-to-mass system coughs up, you'll also get a corresponding normal particle. In practice, even a 1% efficiency would be astonishingly high. You'll need a vast and expensive infrastructure for antimatter synthesis.
Secondly, a 100% efficient conversion of energy release from annihilation into kinetic energy of exhaust products is basically impractical, and not just becasue thermodynamics hates you. About 33% of the annihilation energy will be in the form of neutral pions which will almost immediately decay into highly penetrating gamma rays. It will be Quite Difficult in *most* designs of antimatter engine to absorb those gamma rays into your reaction mass *and* have a high thrust engine, and in *any* design it will be impossible to both absorb *all* the gamma rays *and* have a high specific impulse (roughly: fuel economy). You'll get at most ~80% efficiency for a solid core antimatter engine, which will have a performance and Isp equivalent to a solid core nuclear rocket.
Thirdly, whilst your antimatter engine is running it will be kicking out, at a minimum, a *lot* of gamma rays. More complex designs with higher exhaust velocity will also spit out various kinds of interesting and unstable light particles which will themselves cause some issues but also eventually decay to gamma rays. Once the engine is turned off there will be a lot less residual radiation, but there will be some. A single antiparticle hitting a large nucleus (such as the tungsten core of a solid core antimatter rocket) will not annihilate the entire atom, but will transmute it and maybe even fission it. The resulting nuclides are not guaranteed to be stable!
It is at least a lot more plausible (and an awful lot safer) to use a solid-core antimatter rocket to lift off from Earth than to use a nuclear rocket of any kind. You need so little antimatter for the job that even a worse-case catastrophic accident will be quite non-destructive and there will be no fallout to be concerned about.
>
> I'm wondering if in a space battle that takes place within the solar system is there any place for nuclear powered spaceship or they belong in space museums?
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Nuclear rockets are a lot less versatile... not only are they more hazardous to maintain, but they can't be trivially turned on and off at will. This is fine for civilian purposes (where you will do be doing a couple of orbital injection burns at the start and end of your journey), or if you are making a torpedo, but it is slightly more inconvenient for a warship.
Their fuel on the other hand is almost certainly cheaper to obtain and simpler to store and a lot safer to be around once high-power weaponry starts going off in the neighbourhood.
The efficiency of antimatter is slightly less than you might think. It is up to you to determine the relative availability of antimatter vs fission fuel, which will ultimately tip the balance in favour of whichever outcome is best for your story, and we can't determine that for you!
[Answer]
Well, [someone](https://en.wikipedia.org/wiki/Jack_Churchill) during WW2 used bow and a claymore
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> John Malcolm Thorpe Fleming Churchill, DSO & Bar, MC & Bar (16 September 1906 – 8 March 1996), was a British Army officer who fought in the Second World War with a longbow, bagpipes, and a Scottish broadsword.
> Nicknamed "Fighting Jack Churchill" and "Mad Jack", he was known for the motto: "Any officer who goes into action without his sword is improperly dressed."
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> In May 1940, Churchill and some of his men ambushed a German patrol near L'Épinette (near Richebourg, Pas-de-Calais). Churchill gave the signal to attack by raising his claymore.
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Though not a large scale usage, someone can be ~~nut~~ brave enough to stitch to the good old way of fighting just for the sake of preserving traditions.
[Answer]
Check [this link](https://www.space.com/fusion-powered-spacecraft-could-launch-2028.html) for a fusion-powered spaceship that could be ready in the next decade. The *Direct Fusion Drive* (DFD) engine could take flight for the first time in 2028 or so. The minivan-size DFD could get a 10,000 kilogram robotic spacecraft to Saturn in just two years, or all the way out to Pluto within five years of launch.
Such a spacecraft would be a far better alternative than a fission-powered craft, and it is less dangerous than an antimatter drive, where storing the antimatter safely is a major issue. It uses deuterium and helium-3, and while the latter is pretty rare on Earth, it is fairly abundant in space, e.g. on the surface of the Moon, and it can be produced in fission reactors. The reactor/engine is fairly compact, as [the reactor chamber can't be more than ca. 1.5 m in diameter](https://www.space.com/37146-nuclear-fusion-rockets-interstellar-spaceflight.html). Because of this restriction in size, you will need several engines on a single spacecraft (6 is the estimate for a manned mission to Mars).
[Answer]
Antimatter will almost certainly not replace fusion because the fuel is simply too expensive to synthesize despite the efficiency. What is probably a better idea is antimatter induced fusion, if fusion power is too hard to make work otherwise.
While antimatter is 259 times as efficient as Detuerium-Helium-3, and while antimatter rockets have a theoretical exhaust velocity that is light speed, meaning that this is the upper limit on delta-v (rocket efficiency is mostly a function of exhaust velocity, with about double effective exhaust velocity a good practical limit for rockets when dealing with lower velocities not factoring relativity into account), they are not nearly as efficient as they seem.
Let's just assume that we can handwave over the problems and have a kind of crystalline magnetic bottle of anti-hydrogen (it will still explode if it ever loses power, so hope you have good batteries). Even with this, there are two big problems you can't get around.
The first is that 40 percent of the energy from antimatter becomes gamma rays, which are hard to harness and require heavy shielding. If you then tried to harness the antimatter reaction to create a plasma rocket, you would reduce your effective exhaust velocity down to 30% of light speed because of inefficiencies in magnetic nozzles. Your best bet with antimatter is actually to create a photon rocket, also known as a flashlight drive because it really is just a beam of light. This ups your exhaust velocity up to about 50%.
So, while it is possible to build an antimatter rocket, it will never have the cost efficiency of fusion power because it doesn't actually generate energy, it only stores it. Because there are no known natural sources of antimatter, it must be created artificially. It currently takes ten million times as much energy to create a unit of antimatter as that unit of energy is worth. Even with something like solar power stations around Mercury, the energy will almost certainly never be as cheap as the alternative of fusion.
So, if you're talking about using external energy, I'd say there is a better approach than antimatter. A better use of the energy is to create beam rider spacecraft. Either laser or magnetic/electric sails are a better option. Lasers are probably easier to make and more efficient over distance, but are also much more effective as weapons(known as the Kzinti lesson), which makes it easier to sell designing shorter ranged microwave installations for magnetic sails.
[Answer]
Nonsymmetrical warfare.
When nationstates go at it hammer and tongs, they use the most modern and advanced ships they can build or buy.
When the Federation battles the Pirate Loonies, however, the latter can't afford antimatter ships...but old, leaking, space-rusted fission ships are just the ticket. In fact, they refit fleets of the old monsters with autocontrol circuits, remove the shielding, and send them on suicide missions, irradiating everything they get close to before the self-destruct cycle.
[Answer]
A space propulsion system doesn't have an efficiency, it has a certain amount of thrust, and it can produce a certain amount of deltaV, and for a fixed power level you can trade of deltaV for more thrust.
This means even with antimatter powered spacecraft, you can still build defensive nuclear craft that may not match them in operational range, but can produce the same amount of maneuvering thrust in actual combat.
Alternatively, nuclear drives may be a cheaper or more compact propulsion system for range limited expendable munitions.
Further, for any real nuclear drive (that includes fission, fusion and antimatter) the primary issue is managing the heat, so the higher energy density of the fuel may not be that much of an advantage.
[Answer]
# Bonus damage
You are possibly thinking only about troop transportation. If you are willing to go kamikaze, and also for missiles, nuclear powered engines have the advantage of causing +5 radiation damage to the target. So even if the enemy spaceship is not destroyed, its crew is now growing extra limbs and glowing green.
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[Question]
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Trying to figure out how much a 1 foot tall fairy would realistically weigh using these 2 guidelines
1. Fairies are just scaled down humans.
2. Their bones are not hollow because their flight is assisted by magic.
[Answer]
For uniformly scaled down humans (as opposed to real life short humans), result would be simple as
$$m\_{fairy} = M\_{human} \* (\frac{H\_{fairy}}{H\_{human}})^3$$
Assuming the fairy is 1 foot tall and her real life prototype is 5'6" and 120 lbs we get 0.72 pounds or 11.5 ounces.
[Answer]
## **Comparison with other humans**
We can almost look at a real live example: <https://www.oddee.com/item_97186.aspx>
Edward Nino Hernandez is about 70 cm tall (~2 foot) and weighs 10 kg. We can actually use this to test the square-cube-law, proposed in other answers:
$$m\_\text{fairy} = 80\ \mathrm{kg} \cdot \left(\frac{0.7\ \mathrm m}{1.8\ \mathrm m}\right)^3= 4.7\ \mathrm{kg}$$
So they are off by a factor of 2.
## **Comparison with monkeys**
Let's have a look at monkeys: <https://en.wikipedia.org/wiki/Tamarin>
The Tamarin can grow up to $30\ \mathrm{cm}$, which is just about 1 foot and heaviest specimen weigh up to $0.9\ \mathrm{kg}$ (other units can be found in the article).
The squirrel monkey (<https://en.wikipedia.org/wiki/Central_American_squirrel_monkey>) also grows up to about $30\ \mathrm{cm}$ and has a maximum weight of about $0.95\ \mathrm{kg}$
**Comparision with a penguin**
Another animal I could think of, that is roughly that size.
Penguin (<https://en.wikipedia.org/wiki/Little_penguin>): $1.5\ \mathrm{kg}$
## **Conclusion**
So in conclusion I would estimate the human to weigh round about $1\ \mathrm{kg}{-}1.5\ \mathrm{kg}$, which is just a little over $2\ \mathrm{lbs}{-}3\ \mathrm{lbs}$.
[Answer]
Well, if they are literally just humans of the exact same proportions, but scaled up or down, we can use the [Square-Cube Law](https://en.wikipedia.org/wiki/Square%E2%80%93cube_law) to figure it out in both cases.
**The skinny version** is, if I understand this correctly, take this equation:
*V2 = V1 ( l2 / l1 )^3*
where *V2* is your new Volume, *V1* is the original Volume, *l2* is the new length and *l1* is the original length, and assume for simplicity's sake that volume exactly correlates with mass, and therefore weight.
So if a reasonably well-fed human is 6ft tall and 180lbs, then an exact scaled-up giant version at 12ft tall would be 2x the height, and therefore the weight is *180(12/6)^3*, or 1,440 lbs. That's a lot.
Turning this around, if this 6ft, 180lbs human is scaled down to 1ft tall, then we're looking for *180(1/6)^3*, which is about 0.83333.
**So your fairies would weigh less than one pound each**, with the exception of some who are enormous by fairy standards.
You can use this to get a rough estimate of weights for all sorts of creatures, big or small. Take an animal that looks the most like what you want to make, plug in its bodily proportions, and presto you have a rough idea of how much the new version should weigh. You'd be surprised just how heavy your giants are and how light the dwarfs are.
[Answer]
A 30cm fairy would need a lot less muscle relatively than a normally sized person. (Note that with a normal amount of muscle, they'd be able to jump nearly as high absolutely as a big person). They'd look probably quite skinny, and weigh less than the square-cube law would suggest, maybe 0.3kg.
[Answer]
Other answers have scaled the persons' mass by the cube of their height, and got answers of about 13 ounces. This is probably a lower bound; it assumes that a human brain can fit into a space slightly larger than a teaspoonful.
The theory of "Body Mass Index" (BMI) is that people have the longest life when their mass is roughly proportional to the square of their height. If we start with 6 feet = 180 pounds (a BMI of 24.4 kg/m²), we can extrapolate this to 1 foot = 5 pounds. This is probably an upper bound; it allows a few cubic inches for the brain.
An elliptical cylinder of water with a width of 5.4 inches, a height of 12 inches, and a depth of 2.7 inches would have a mass of five pounds. The ellipse's perimeter would be 13 inches, which is quite stout. (6 \* 13" is a 78" waist!)
An elliptical cylinder of water with a width of 2.2 inches, a height of 12 inches, and a depth of 1.1 inches would have a mass of 13 ounces, and a BMI of 4 kg/m². The ellipse's perimeter would be 5.3 inches, which is scaled down from a 32 inch waist.
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[Question]
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In my world, ten is an important number that shows up frequently. In the solar system my world belongs to, there are ten other planets beside it, and there are ten months in a year.
I know next to nothing about astronomy, but I wondered if it were possible to have people on my planet be able to see in each consecutive month a different planet and recognize it as a planet\*, maybe because the planets are brighter with clear shapes rather than points of light, or maybe because the planets' orbits take them close enough to my planet that they can be recognized.
My world is similar to Earth in size and proximity to the sun, which is comparable to our sun. The sizes of the other planets are mutable.
**Is it possible that every month a different planet could be identified as a planet without a telescope?**
\*My world has medieval-era technology, so there are no telescopes.
[Answer]
In the sense that only one planet would be in a position in the sky that made it visible, no, it is not possible.
The orbital period of a body around a center of mass depends on the mass of the body, mass of the system and the mean distance from the center of mass. In practice, stars are so much more massive and larger than planets that planetary orbital periods are proportional just to the star's mass and the mean distance involved.
As a consequence of the above, no two planets in different orbits can have the same orbital period. And if they do share an orbit, they will merge quite catastrophically in a few million years.
Since they don't all complete an orbit at the same speed, there will always be some slower and some faster, which makes it impossible to have them organized to show up at a constant rate of a single different one every month.
There is one one way to achieve the visibility you want, though. It is such a stretch and a [redacted]pull that people will stop reading your story the moment you expose this (unless it is a comedy). If each planet's rotation period is roughly 1/10 of a year, and each planet's crust is a 10% high [albedo](https://en.wikipedia.org/wiki/Albedo) surface and 90% low albedo surface, you might just have nine of them absorbing most sunlight while one reflects it just right at your planet at any day of the year. They just happen to alternate every month.
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You could also take a page from astrology, you know. The zodiacal signs are always visible and on the [ecliptic](https://en.wikipedia.org/wiki/Ecliptic). The sun is always on top of one, and only one of them at a time. Whatever it was by the time you were born is your solar sign. There are tons over tons of mysticism around this, which might just do the trick for you.
[Answer]
I am tempted to say that's not possible.
Every day, or better every night, any observer on any point of the surface of a planet swipes about half of the visible sky.
You are asking if, each month, it is possible that only 1 out of 10 planets is visible in this half of the sky, more around the equator, less at the poles. If that was possible in a particular month, it would mean, by symmetry consideration, that there would also be months were up to all planets would be visible. Even if their relative position in the system was fixed (which would happen only if they shared the same circular orbit) the planetary rotation would make visible more than 1 per night, and some would never be visible.
Therefore my conclusion is that it can episodically happen that only 1 planet is visible at night in the sky, but not regularly. The norm would be to see more planets during the same night.
[Answer]
**Maybe**
So this answer is dependent on a few hypotheticals, and a lot of luck forming the star system. The first requirement is that you need the planets to be *dark.* The concept being that you can only see another planet when it's closest to yours.
[](https://i.stack.imgur.com/9ytQl.png)
In other words, the planet can only be seen from the green planet (that's yours) from the position of the second gray circle. Note that the drawing is not to scale, and is in fact horrible, but it's just to give you the image idea.
Why can they only be seen from that angle? Because they aren't bright planets and the distance is necessary to see them. It should be hypothetically possible, if you play around with the factors. This way the planet isn't a bright dot (like say, Venus) but is more of dull one.
The second requirement is that the 10 planets travel around the sun in the *opposite* orbit, albeit since they're so far away it takes them double the time that it does for your planet, thus once every month for 10 months, the planets align. [Hypothetically possible.](https://www.nrao.edu/pr/2006/counterdisk/)
Oh, I should note that these 10 planets all all individual orbits, they do not share orbits, but they're close enough so that this will work. The orbits won't be entirely stable, in fact, thanks to the fact they're circling the other way they'll be pretty unstable from the beginning, but it should last long enough for a book to take place.
[Answer]
1. Elliptical orbits might make this possible, like if your planet was the only one going around the sun in a normal orbit and the ten others all had comet-like orbits and came in towards the sun in synchronicity with each other. your planet could even act as part of the slingshot effect for keeping this sort of timed dance going.
More research would be needed, as I won't do the maths involved: <https://en.wikipedia.org/wiki/Elliptic_orbit>
2. The other option would be using orbital resonance to note the months instead of Seeing Only One At A Time. Like in the first month you have one visible, in the second you see two in a line, in the third you see one again, in the fourth there are three visible in a row, etc. This would be dramatic-looking in the sky, and certainly would inspire religious and cultural practices.
<https://en.wikipedia.org/wiki/Orbital_resonance>
[](https://i.stack.imgur.com/TsdoO.png)
[Answer]
**SHORT ANSWER:**
This is a difficult problem for those the least concerned with scientific plausibility. At the end of a long discussion I come up with a reasonably plausible planetary set up - though it is so unlikely to occur naturally that a writer might want to have characters speculate that an advanced civilization actually arranged the planets that way.
**LONG ANSWER:**
**PART ONE: A RING OF PLANETS**
This looks like a job for Sean Raymond of the PlanetPlanet blog.
In this post: <https://planetplanet.net/2017/05/03/the-ultimate-engineered-solar-system/>[1](https://planetplanet.net/2017/05/03/the-ultimate-engineered-solar-system/)
Raymond mentions a paper that shows that it is possible for several astronomical bodies to share the same orbit around another body under some circumstances.
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> Orbital stability of systems of closely-spaced planets, II: configurations with coorbital planets Smith, Andrew W.; Lissauer, Jack J.
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> Celestial Mechanics and Dynamical Astronomy, Volume 107, Issue 4, pp.487-500
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<http://adsabs.harvard.edu/abs/2010CeMDA.107..487S>[2](http://adsabs.harvard.edu/abs/2010CeMDA.107..487S)
Their calculations indicate that at least seven bodies of nearly identical mass would have to be spaced evenly along the orbit for it to be stable. So your requirement for ten would be quite possible.
If there are ten equally spaced co orbital astronomical bodies they would be spaced 36 degrees apart along the orbit.
If those planets orbit their star at a distance of 100 units, the total circumference of the orbit will be about 628.318 units. One tenth of that will be about 62.8318 units. How close can the next planetary orbit in or out be?
According to this Wikipedia list:
<https://en.wikipedia.org/wiki/List_of_exoplanet_extremes>[3](https://en.wikipedia.org/wiki/List_of_exoplanet_extremes)
the smallest known ratio between the semi-major axis of two consecutive planetary orbits is about 11 percent, with Kepler-36b & Kepler-36c.
<https://en.wikipedia.org/wiki/List_of_exoplanet_extremes>[3](https://en.wikipedia.org/wiki/List_of_exoplanet_extremes)
So if that was close to physical lower limit of ratio the next closest inner planetary orbit would be about 90 units or fewer from the star in the system, and the next closest outer planetary orbit would be about 111 units from the star.
Thus your planet could get within ten or eleven units of a planet in the ring of planets when it passes closest to it, which would be about six times as close as the next two closest planets in the ring will be at that time.
Note that the ratio between orbits is different from the absolute difference between orbits. The smallest known difference between two consecutive planetary orbits is in the Kepler-70 system. Kepler-70c is believed to orbit only about 0.0016 Astronomical Units, or about 240,000 kilometers, beyond the orbit of Kepler-70b.
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> During closest approach, Kepler-70c would appear 5 times the size of the Moon in Kepler-70b's sky.
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<https://en.wikipedia.org/wiki/List_of_exoplanet_extremes>[3](https://en.wikipedia.org/wiki/List_of_exoplanet_extremes)
So it is possible for two planets to appear as orbs in each other's sky at their closest approach while remaining mere dots in the sky at other times.
And it is suspected, but not proved, that a third planet might orbit between Kepler-70b and Kepler-70c, which would sometimes get an ever better view of Kepler-70c.
<https://en.wikipedia.org/wiki/Kepler-70>[4](https://en.wikipedia.org/wiki/Kepler-70)
Of course the planets in the Kepler-70 system don't orbit in the habitable zone of Kepler-70. But TRAPPIST-1 does have planets in its habitable zone that do orbit very close to each other.
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> This work used the Spitzer Space Telescope and the Very Large Telescope at Paranal, amongst others, and brought the total number of planets to seven, of which three are considered to be within its habitable zone.[20] The others could also be habitable as they may possess liquid water somewhere on their surface.[21][22][23] Depending on definition, up to six could be in the optimistic habitable zone (c, d, e, f, g, h), with estimated equilibrium temperatures of 170 to 330 K (−103 to 57 °C; −154 to 134 °F).[5](https://en.wikipedia.org/wiki/TRAPPIST-1) In November 2018, researchers determined that planet e is the most likely Earth-like ocean world and "would be an excellent choice for further study with habitability in mind."[24]
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> The orbits of the TRAPPIST-1 planetary system are very flat and compact. All seven of TRAPPIST-1's planets orbit much closer than Mercury orbits the Sun. Except for b, they orbit farther than the Galilean satellites do around Jupiter,[41] but closer than most of the other moons of Jupiter. The distance between the orbits of b and c is only 1.6 times the distance between the Earth and the Moon. The planets should appear prominently in each other's skies, in some cases appearing several times larger than the Moon appears from Earth.[40] A year on the closest planet passes in only 1.5 Earth days, while the seventh planet's year passes in only 18.8 days.[37][34]
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<https://en.wikipedia.org/wiki/TRAPPIST-1>[5](https://en.wikipedia.org/wiki/TRAPPIST-1)
So the TRAPPIST-1 system is an example of a star system where planets in the habitable zone usually look like dots in the sky but sometimes pass close enough to appear as visible orbs and even appear as large as the Moon in Earth's sky or even larger.
Calculations of how close planetary orbits can be are usually based on the assumption that all planets in a system orbit their star in the same direction, which is the direction that the star rotates in. In fact, in our solar system all the planets orbit in the same direction, and they all (except for Venus & Uranus) rotate in the same direction. And many of the moons also orbit in that same direction.
The majority of discovered exoplanets orbit in the same directions as their stars rotate in, and in the same directions as any other discovered exoplanets in their systems.
So it is a safe assumption that in the majority of star systems all planets orbit in the same direction.
But how would it affect orbital stability if the planets in a star system orbited in two different direction, perhaps even alternating the orbital direction from one orbit to the next?
Sean Raymond in this post:
<https://planetplanet.net/2017/05/01/the-ultimate-retrograde-solar-system/>[6](https://planetplanet.net/2017/05/01/the-ultimate-retrograde-solar-system/)
discusses a paper calculating the stability of planetary orbits:
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> Orbital stability of systems of closely-spaced planets,
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> Smith, Andrew W.; Lissauer, Jack J., Icarus, Volume 201, Issue 1, p. 381-394.
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<http://adsabs.harvard.edu/abs/2009Icar..201..381S>[7](http://adsabs.harvard.edu/abs/2009Icar..201..381S)
Raymond mentions that Smith and Lissauer show that planetary orbits can be closer together if the orbits alternate between prograde (orbiting in the same direction as the star rotates) and retrograde (orbiting in the opposite direction).
So if the habitable planet in your story and the ring of ten planets orbit in different directions, the planet's orbit can be much closer to that of the orbital ring of planets and during the brief periods when the planet is closest to one of the planets in the ring the other planet can appear much larger in the sky.
**PART TWO: A BIG PROBLEM**
As planets orbit around their star, their orbital periods are different. The inner planets complete their orbits much faster than the outer planets do. Thee are two reasons for that.
1) The orbits of inner planets are much smaller than those of outer planets, so if they traveled at the same speeds the inner planets would complete their orbits sooner.
2) The necessary orbital speed is faster the closer to the star, so the inner planets have to travel much faster in their orbits.
The combination of those two factors means that inner planets travel more degrees of their orbit per day than outer planets do, and so complete their orbits before outer planets do.
So imagine that an inner planet and an outer planet happen to be lined up with the star in their system. Then as time passes, the inner planet will pull ahead of the outer planet and leave it farther and farther behind. Eventually the inner planet and the outer planet will be on opposite sides of their star. Then the inner planet will begin to catch up with the other planet.
When the inner planet catches up with the outer planet again, the time elapsed will not be exactly one year of either the inner planet or of the outer planet.
The time period for two planets to be in the same configuration with each other and their star is called the synodic period.
For planets outside the orbit of Earth, the synodic period relative to Earth gets shorter and shorter the father they are from the Sun, because they are travelling slower and slower in their obits, so once Earth completes a full circle around the Sun it has to travel shorter and shorter further distances to catch up with the slower moving planets.
Mars has a synodic period of 2.135 Earth years, the asteroid Ceres has a synodic period of 1.278 Earth years, Jupiter has a synodic period of 1.092 Earth years, Saturn has a synodic period of 1.035 Earth years, and so on.
So if the star is like the Sun, and if your main planet is at the distance of Earth, and the ring of planets is at the distance of Saturn, a tenth of the main planet's year would be about 0.100 Earth year or about 36.525 Earth days. A tenth of the synodic period of the ring of planets would 0.1035 Earth years or about 37.803375 Earth days.
So the planet would have same same problem basing their "months" on passing successive planets in the ring of planets that Earth has basing it's months on lunations, the periods between the moon having the same phase. The inner planet may pass all ten planets in the outer ring of planets in most years, but in some years it will pass nine planets or eleven planets.
To make the problem smaller the ring of planets can be farther out compared to the orbit of the main planet in your story.
The semi-major axis of the orbit of Mars is 1.5273 times that of Earth, and the synodic period is 2.136 Earth years.
The semi-major axis of the orbit of Ceres is 2.76596 times that of Earth, and the synodic period is 1.278 Earth years.
The semi-major axis of the orbit of Jupiter is 5.2028 times that of Earth, and the synodic period is 1.092 Earth years.
The semi-major axis of the orbit of Saturn is 9.5388 times that of Earth, and the synodic period is 1.035 Earth years.
The semi-major axis of the orbit of Uranus is 19.1914 times that of Earth, and the synodic period is 1.012 Earth years.
The semi-major axis of the orbit of Neptune is 30.0611 times that of Earth, and the synodic period is 1.006 Earth years.
The semi-major axis of the orbit of Pluto is 39.5294 times that of Earth, and the synodic period is 1.004 Earth years.
The semi-major axis of the orbit of 50000 Quaoar is 43.6916 times that of Earth, and the synodic period is 1.003 Earth years.
The semi-major axis of the orbit of 136199 Eris is 67.6681 times that of Earth, and the synodic period is 1.002 Earth years.
The semi-major axis of the orbit of 90377 Sedna is 506.8 times that of Earth, and the synodic period is 1.0001 Earth years.
<https://www.windows2universe.org/our_solar_system/planets_orbits_table.html>[8](https://www.windows2universe.org/our_solar_system/planets_orbits_table.html)
<https://en.wikipedia.org/wiki/Orbital_period#Examples_of_sidereal_and_synodic_periods>[9](https://en.wikipedia.org/wiki/Orbital_period#Examples_of_sidereal_and_synodic_periods)
<https://en.wikipedia.org/wiki/50000_Quaoar>[10](https://en.wikipedia.org/wiki/50000_Quaoar)
<https://en.wikipedia.org/wiki/90377_Sedna>[11](https://en.wikipedia.org/wiki/90377_Sedna)
Of course Saturn is the farthest naked eye planet known since ancient times. Uranus is sometimes visible to the naked eye, but was never recognized as a planet until 1781. A planet as large as Jupiter or Saturn could be recognized as a planet out to the orbits of Uranus and Neptune.
Of course planets as distant as Neptune, or even Mars, could never appear as discs as seen from Earth.
Any outer ring of ten planets that was distant enough from the main planet in the story to avoid messing up the calendar of the planet more than Earth's is messed up with months that don't fit evenly into years, would many times too distant for the planets in the ring to ever appear as orbs as seen from the main planet in the story. And at any one time most of the ten planets in the ring should be visible from the inner planet in the story, though at any moment only one of them can be close to the position opposite to the star.
**PART THREE: AN INNER RING OF PLANETS**
What about planets that orbit interior to the main planet in the story?
In our solar system there are two planets orbiting inferior to Earth.
The semimajor axis of Mercury's orbit is 0.3871 that of Earth's orbit, and the synodic period of Mercury is 0.317 Earth years or 155.88 Earth days.
The semimajor axis of Venus's orbit is 0.7233 that of Earth's orbit, and the synodic period of Venus is 1.559 Earth years or 583.9 Earth days.
<https://www.windows2universe.org/our_solar_system/planets_orbits_table.html>[8](https://www.windows2universe.org/our_solar_system/planets_orbits_table.html)
<https://en.wikipedia.org/wiki/Orbital_period#Examples_of_sidereal_and_synodic_periods>[9](https://en.wikipedia.org/wiki/Orbital_period#Examples_of_sidereal_and_synodic_periods)
And I note that the synodic period of Mercury is a fraction of an Earth years, while the synodic period of Venus is more than one Earth year. This leads me to suspect that there is a possible orbit somewhere between those of Mercury and Venus where a planet would have a synodic period equal to an Earth year.
According to my rough calculations, if a planet orbits with an orbital period of about 182.62505 Earth days, it should have a synodic period of about 365.000 Earth days, slightly shorter than an Earth year of 365.25 Earth days which should be close enough.
That calculation should be checked by someone or some program that is better with orbital calculations, and capable of calculating the semimajor axis of the orbit a planet with an orbital period of 182.62505 Earth days.
At such a relative distance compared to the habitable main planet, the ten planets in the ring of inner planets should be hellishly hot and uninhabitable for the natives of the main planet in the story. However, if the main planet in the story orbits toward the outer edge of the star's habitable zone, the inner ring of ten planets might be within the habitable zone and some or all of the planets might be habitable.
Now the problem would be how to get the planets in the inner ring visible only part of the time, so that only one of them at a time is visible from the outer planet.
The planet Mercury can be observed with the naked eye only for relatively short periods when it is separated from the Sun by the largest angles, and only in twilight skies before the Sun rises or after the Sun sets.
So if the ring of planets orbited at the same relative distance to the main planet in the story as Mercury does to Earth, it would be quite likely that only one of the ten planets in the ring would be visible at anyone time.
But unfortunately the ring of ten planets would be at a somewhat greater relative distance and so more than one of those planets should be visible at any one time. Therefore it would be a good idea to somehow make the day sky, the twilight sky, and maybe even the night sky if possible somewhat brighter than the skie sof of Earth, drowning out the light of the inner planets except when they are at extreme maximum elongation from the star in the system, thus making only one planet visible at any one time.
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Yes, but it requires an engineered solar system, it can't occur naturally.
1) Your central body needs to be a fairly massive black hole, not a star. Note that this means bright jets heading along it's axis of rotation--this should be vertical or close to it as those jets will sterilize your world if they should cross it. A thick atmosphere is recommended anyway to keep the radiation levels down. (This will make wind a more destructive force, but lower wind velocities and will reduce missile weapon ranges.)
2) Your world is in an orbit by itself.
3) Your 10 planets share an orbit. Only one at a time is close enough to show a disk, some of the others can still be seen in the distance, but only as points of light.
4) Note that this system does not permit a conventional year as you can't have an orbital period anywhere near a year to make this work. You still can have seasons, though--you will need two stars. The first is in a close orbit about the black hole, it provides most of the light and heat for your world. The second is in a slightly elliptical orbit well outside your orbit. When it's closer you have summer, when it's farther you have winter. Note that you will also have a small seasonal effect based on your orbit taking you closer and farther, without a lot of math I can't tell you what the period of this cycle is. This would be sort of like weather but predictable far into the future.
5) Unlike the other answer this requires that the planet ring orbit in the same direction as you do. I'm not sure if this is directly possible or not, if it's not there could also be a counter-rotating ring of dark worlds in between--their high orbital velocity would make them very hard to see, especially if they had dark surfaces.
6) Moons are problematic in this system, they are going to have to be close to your world if they are stable at all (the stability of this whole system is based on the high mass of the central black hole squeezing down the zone of control each planet exerts. On the flip side any moon passing within your planet's Roche limit is destroyed--see Saturn's rings for an example of a moon getting too close. Whether these limits leave a space in between where a moon can be I do not know) and thus they will have to be small to avoid catastrophic tides.
7) While it is probably not relevant to your story note that interplanetary spacecraft will have a **very** hard time reaching your special planets, doubly so if a counter-rotating ring is necessary.
8) Note that your world is moving like a flying mammal fleeing the infernal regions. This means most meteors will be far faster and brighter than what we see on Earth. (Note that they will be no more likely to survive the fire, though--do not expect any more impacts than Earth sees, but when one gets through it will likely be a far bigger bang and ones that blow in the atmosphere will do so with a far bigger bang, also. Chelyabinsk type events will be much more common.)
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I am interested in events that would so radically change Earth (for the worse) that it would be near uninhabitable for humans. The event may or may not be deadly to humans, but the world it leaves behind should be a very hard one to live in.
Note constraints:
* Anthropogenic events must be based on current science/technology (e.g. no AI overlords making humans wash their metallic feet)
* Natural events can be unlikely, but must be possible (e.g. "The Earth spontaneously blows up" is not a valid answer)
* The event must be survivable both immediately and long term, even if the chances are very slim. It's fine to get creative but the means of survival must fit present or near-present technology levels.
I would expect a good answer to consider what would be entailed in surviving on Earth during/after the given event and how unlikely success is. There is certainly more than one answer to this, but the one that leads to the lowest chances of survival for humanity will be the correct one.
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**Yellowstone Caldera Explodes**
Yellowstone exploding has been featured in several movies as well as the cause in "[Van Helsing](https://www.imdb.com/title/tt5197820/)"
It has the possibility of blanketing out the sun and causing another ice age causing famine and massive loss of life. It's not likely to wipe out humanity but wouldn't be a fun time to live through
See [Yellowstone](https://www.livescience.com/20714-yellowstone-supervolcano-eruption.html)
**Bio Weapons**
The worst case would be the accidental or deliberate release of a bio weapon. A quickly mutating airborn virus that can infect other species such as birds would be troublesome.
People may have to survive in shelters until a cure is developed or the virus burns out but if it can affect other species and mutates quickly (like the flu) a cure would be difficult to find.
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# Collision
The dinosaurs were wiped out when [a big meteor or comet hit the Earth](https://en.wikipedia.org/wiki/Cretaceous%E2%80%93Paleogene_extinction_event) (K-T extinction event). It screwed up every ecosystem, both in land and in seas, produced mass extinctions of many types of animals and plants and changed the climate. However, smaller animals, like mammals and birds, indeed survived, but it was a very catastrophic event nevertheless.
If that happened nowadays, humans would surely survive thanks to technology and intelligence, but it would be a very hard struggle. This would cause havoc in agriculture, fishing, foresting and many other essential activities, which would lead to an economical crash and famine.
If something like K-T is not enough, maybe a higher dose like the [P-Tr event](https://en.wikipedia.org/wiki/Permian%E2%80%93Triassic_extinction_event) is enough. Quoting wikipedia's article, "*It is the Earth's most severe known extinction event, with up to 96% of all marine species and 70% of terrestrial vertebrate species becoming extinct.*" It triggered a sudden 8° C rise in temperature and an increase in CO2 levels by 2000 ppm. That was more than enough to mess up with Earth ecology everywhere. Nature took some millions of years to recovery from that. The cause of the P-Tr event is unclear, but a very large bollide hitting the Earth would do that.
Now, imagine a very large bollide hitting the Earth and obliterating a large area, say, half the size of Australia, part on sea and part on land. That area would then be turned into an open magma pit by exposing the mantle. It would also cause an earthquake and a tsunami as never seen before and would also release a lot of toxic gases from the exposed mantle, from vaporized crust and also those gases that were imprisoned in the crust. Also, a lot of seawater would be suddenly vaporized.
The atmosphere becomes severely dusty, and the blocked sunlight would be more than enough to create a winter that could trigger an ice age, if it were not the greenhouse gases preventing that. Since much less sunlight reach the surface, the life of many plants and animals both in land and in sea would be screwed. Also, since there is much more water vapour in the atmosphere, and then much more clouds, so there would be still less sunlight. From that, there would be horribly severe storms, hurricanes, floods and landslides. Also, the summers would be much more warmer and the winters much more colder. This would cause a severe death toll for land lifeforms and also for many aquatic forms. And oh, since the water in the rain will combine with the dust, the rain would be acidic and it could also acidify the seas.
The death toll would create a massive quantity of rotting organic matter (imagine something like the amazon forest suddenly dieing and rotting down all at once). A large part of that matter will be washed down to waters (seas, lakes and rivers), where it will tend to deplete water's oxygen in many places triggering anoxic events that will further extinguish many aquatic lifeforms. The rotting organic matter itself would release a lot of greenhouse gases and consume atmospheric oxygen. Needless to say, having less oxygen dissolved in waters and less oxygen in air would be no good for whatever ecology that are still resisting so far.
In the following years, as the dirty settles down, the greenhouse gases are still in the atmosphere and they will warm up the planet severely, further screwing up once again the already screwed up ecosystems. The removal of much of the previous forest cover would also create large desertic areas.
Very few forms of plants and animals are able survive that, but a few surely will. Among them, a few humans surely could do, but it would be no easy task.
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> What survivable events would make Earth **least** inhabitable?
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[**emphasis** mine]
As far as I know, there is only one survivable event that makes the Earth *least* inhabitable for humans, and that is a...
## Gamma ray burst from a nearby binary star system.
Such an event could strip the Earth of its ozone layer which will cause the ultraviolet radiation from the sun to penetrate through the atmosphere with nothing to slow it down. According to NASA scientists, this would in short time almost entirely wipe out life on Earth's surface. **The only surviving organisms would be underwater or underground.**
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> [[source](https://aura.gsfc.nasa.gov/ozoneholeposter/Ozone-Booklet_woLesson.pdf):] Without ozone, the Sun’s intense UV radiation would sterilize the Earth’s surface.
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It would take billions of years for Earth to regain an ozone layer capable of protecting land-dwelling organisms again (the absence of an ozone layer is part of the reason it took so long to see land-dwelling organisms on the early Earth in the first place).
## How to survive?
Initially, this event wouldn't directly harm many persons, but the rates of cancer due to DNA damage would drastically increase and eventually no creature would be able to survive if it remained on the surface. Any human that wishes to survive would have to retreat to underground sanctuaries (or underwater ones if they can be fabricated fast enough). The mass migration of people attempting to occupy these few locations that would be available would cause mass rioting and plenty of death due to starvation as so many people travel the country-side in search of a new home.
Reclaiming the surface is largely out of the question with current technology. The blow to the resources of the planet is so great that it will be at least a few hundred years, but likely more than a millennium before the survivors could mass produce ozone and replenish the Earth's protective shell. Habitats would have to expand under the earth, hopefully expanding towards the oceans where larger settlements could eventually be constructed.
In the extreme long term, humanity could restore the ozone layer and attempt to repopulate the surface with genetically engineered surface-dwelling organisms and crops (as the originals would all be dead). The recovery from an event like this will take even longer as it will take some time before humans are in large enough populations to muster the resources required to do anything except struggle to survive. In short, this event would set humanity, and for that matter: all surface life, back to the beginning.
[Answer]
**A powerful solar storm**
I haven't seen it in any apocalyptic movie or book yet, but one did happen not too long ago : <https://en.wikipedia.org/wiki/Solar_storm_of_1859>
TLDR: a powerful coronal mass ejection from the sun hit the Earth. It was seen as auroras all accross the continents and created one of the strongest geomagnetic storms on record, causing telegraphs (the only electrical systems at the time) to fail, melting wires and killing a few operators in the process.
If it happened nowadays, replace telegraphs with 99% of our electrical grid and electronic devices (that means no cars, trains, planes or boats too). Beyond the immediate deaths from planes falling, hospital equipment falling, cars crashing... the logistics modern civilization requires to maintain itself is gone. Expect mass deaths and chaos as there is no way to supply cities with food and water anymore.
Beyond that, there is no long term effect on Earth, life for most species will continue normally and even humans will recover eventually.
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For some old classics:
**Nuclear Winter** Most of the world is a radioactive nightmare and the dust clouds in the sky block out most of the sunlight killing off most plants. Most of the survivors are in bunkers and will die when supplies run out but a few are in the rare places that weren't hit as badly and where life is still possible(if with way more birth defects and less sunlight than in the past)
**Global Warming** It keeps going or possibly speeds up and ecosystems keep dying. Mass starvation starts and leads to widespread war which kills off even more. Eventually long after there stop being enough humans around to keep polluting things level off. Much of the planet could be uninhabitable at this point and what life remains will have adapted to much different circumstances and possibly seem quite alien.
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The gmo food has had cumulative long term effects on the human population and suddenly 99.999% of the population has become infertile. It's hard to find fertile people and food that is safe to eat as nearly all the food has been modified. The food is safe to eat but you do become infertile. Well not infertile in the way that you can't have children but the children you do have are stillborn. So it's not really testable to see you are infertile. you just have to wait and see.
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A slow burn to WWIII after an arms race.
Survival of the human race is questionable in the general case but if enough people can see it's going to happen survivors are basically certain.
Most of the preppers aren't going to make it--there will be a lot more people that managed to take shelter than there will be supplies, I don't expect the preppers to survive the mobs.
However, there's another approach: Load years worth of supplies onto a ship, head out into safe waters (once the manure hits the air mover you won't have any hurricane forecasting) and wait it out. Looting will be far less of an issue because the mobs can't get there and a fight with looters likely leads to mutual annihilation (neither vessel being seaworthy) so little of it will happen.
When the skies have cleared enough that they can try to rebuild they'll be in a world without livestock or much of anything in the way of animals.
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Luckily for you, Earth has already gone through 5 mass extinction events. You can use these as inspiration for any other extinction events. Events such as a huge volcanic eruption, a meteor impact or an ice age are included here. This video should help with why/how/when:
<https://www.youtube.com/watch?v=DmPgthajlh0>
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Please bear with any confusing explanations – this is my first question on here.
I’ve started building a fantasy world with the rough geography and technological advancement of late 14th –15th century Europe. I've attempted to research resource production in this period, but I've been unable to find an answer I could make sense of and apply to my specific case.
My story is focused around an island off the Southern coast of the continent with a climate similar to that of Italy or Southern France – think hot summers and warmer winters, but with plenty of rain to keep crops growing. They’ve got two central forested mountains from which they’ve been mining gold for three hundred odd years, but most of the island is rolling plains with woodland here and there. In my head it’s roughly half the size of Northern Ireland.
(At least, that’s what I’m hoping. If the logistics don’t work I’m more than willing to change all of this.)
For my plot to work, the family that owns this island need to be rich – one of the richest in the country in fact, as the king wants to marry their daughter mostly for their wealth.
The gold mine helps with that, but it’s not consistently fruitful, and past years of scarcity have led the family to diversify into other areas. They also grow vines and make some of the best wine to be found anywhere, and breed a small number of very fine horses that they sell almost exclusively to the royal stables. These are enterprises for which they’re famed, but due to their high quality-low yield preference, I don’t think it will make them enough to keep them on the “Forbes Richest List”!
For their main area of income, I’d like the island to be one of the “breadbasket” areas of the country, who supply grains and vegetables and fruits primarily to the capital (on the coast almost directly north of the island, pop. 1million\*\*) and other nearby towns and cities. They’re not the sole provider to those areas, but they do contribute a significant enough percentage that the capital would face food shortages if the island was to stop supplying food for whatever reason – say 5% of general food, but more like 15-20% of the nobility’s food as they favour the “exotic” fruits the island can provide.
Is it feasible for an island of my envisioned size (c. 7,000km2) and climate to supply that amount of food?
Would I be better off bumping up their gold mining, horse breeding and wine production and having them grow only enough food to supply their own population (c. 50,000 people)?
Please feel free to ask me to clarify anything I’ve explained poorly.
\*\* *EDIT*: Thank you to all who've pointed out that this population is too high. I've phrased this poorly and meant to say that the 1 million population is that of the capital and towns and cities along that southern coast combined. This is still too high, so I'm going to reduce the overall number to 700,000 to be more in line with recommendations below.
[Answer]
What you actually need to make that Fortune 500 (maybe not 500, far fewer people) is a specialized product that can't come from many other places, especially locally.
So...a spice that needs a particular climate and soil composition. This island provides that.
Along with the diversity of other stuff they can and do grow, the mining, horse breeding and the exotic fruits (this, like the spice, will be a money-maker like you would not believe. A whole industry focused on drying and preserving these makes an awful lot of sense).
All you really need for the richness, is one or two unique products and a diversity of others. [Saffron](https://en.wikipedia.org/wiki/Saffron), AND/OR some kind of plant like woad, that isn't as common as woad and produces a unique color.
Wine is good because it's portable.
Part of your production problems are due to the population numbers you are starting with. Now it's true that in Rome's heyday before their fall, they did top over 1 million, but... See [this link](https://en.wikipedia.org/wiki/List_of_largest_European_cities_in_history) for charts on largest populations in Europe. If this is your model, a city of 300,000 would likely be if not the largest in the world, fairly close to that. A city of over 100,000 isn't that common either.
Paris didn't reach a population of 500,000 (or half million) until the 1600s. During the 16th century or 1500s, Paris was the largest city in Europe, with a population of about 350,000 in 1550. In 1400s, which is the century you're going for, Paris had about 280,000.
So a lot of your food supply issues will evaporate a bit when you calculate for the lower populations overall.
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This island, considering its good climate, could feed its 50 thousand inhabitants, as well as some 50 thousands in the capital. But grain production would not bring too much riches, you will need more. You have already mentioned more profitable commodities, like wine. You may also add olive oil, linens, or put a silver mine in addition to the gold one.
But the most lucrative opportunity for your island seems to be the trade. If it lies on a popular trade route, its merchants are guaranteed to be rich. You may create a Venice-type city that controls the trade for most of the continent to the north. In that case, you don't need grain, wine or even gold - just good ports and fast ships.
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If you want your island to supply 5% of this city's needs, we need to find out what those needs are. For a population of 1 million people: an average person needs ~2,200 calories per day, so ~ 803 billion calories per year. For simplicity, we can look at what 1 bushel of wheat can provide in calories. One **one-pound wheat loaf provides 1,259 calories**(<https://www.fatsecret.com/calories-nutrition/usda/whole-wheat-bread?portionid=.>.), one **bushel of grain produces 90 loafs per bushel**(<http://nationalfestivalofbreads.com/nutrition-education/wheat-facts>). Thus, one bushel of wheat can provide **~113,310 calories**. So, we need ~ 7.1 million bushels of wheat to feed your city. Therefore, an island would need to produce just over 350 thousand bushels of wheat annually to supply 5% of that city's needs plus another 350 thousand bushels for their own population for a total of **700 thousand bushels**.
For farming methods, I found the Open-Field System as a popular farming method for the middle ages. To get an idea of what your island could produce, we should look at the typical method for land distribution and production. From the article <https://en.wikipedia.org/wiki/Open-field_system>:
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> The village of Elton, Cambridgeshire is representative of a medieval open-field manor in England. The manor, whose Lord was an abbot from a nearby monastery, had 13 "hides" of arable land of six virgates each. The acreage of a hide and virgate varied, but at Elton a hide was 144 acres (58 ha). A virgate was 24 acres (10 ha). Thus, the total of arable land amounted to 1,872 acres (758 ha). The abbot's demesne land consisted of three hides plus 16 acres (6.5 ha) of meadow and 3 acres (1 ha) of pasture. The remainder of the land was cultivated by 113 tenants who lived in a village on the manor. Counting spouses, children, and other dependents, plus landless people the total population resident in the manor village was probably 500 to 600.
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For simplicity, we could round up the size of one village to ~2,000 acres of arable land with a population of 600 people. It later states in the article that. Now, how much did one acre of land produce. From the same article, it states:
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> Wheat and barley were the most important crops with roughly equal amounts planted on the average in England. Annual wheat production at Battle Abbey in Sussex in the late 14th century ranged from 2.26 to 5.22 seeds harvested for every seed planted, averaging 4.34 seeds harvested for every seed planted. Barley production averaged 4.01 and oats 2.87 seeds harvested for seeds planted. This translates into yields of **seven to 17 bushels per acre** harvested. Battle Abbey, however, may have been atypical, with better management and soils than typical of demesnes in open-field areas. Barley was used in making beer – consumed in large quantities – and mixed with other grains to produce bread that was a dietary staple for the poorer farmers. Wheat was often sold as a cash crop. Richer people ate bread made of wheat.
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Because of the ideal climate, we will take the higher side of the production per acre of 15 bushels. Based on your proposed 7,000 Square kilometers of space, that would give you approximately 1,729,737 acres to work with. Not all of it is arable as there are two large central mountains, and other forests and such. So we will say that ~60% of the land is readily usable for planting: or 1,037,842 acres. Given that you want a population of ~50,000 on your island, you could have ~84 settlements (50,000/600 per settlement) of 2,000 acres a piece for a total needed space of 166 thousand acres which easily fits in your land budget. This land would produce 2.49 million bushels of wheat in a year. Which is 3.56 times your desired amount (30% of city needs, plus your island's needs).
All of this would give you tons of room on the island for things like fruits, vineyards (easily the most profitable item you could produce short of gold depending on the reason for demand, in the middle ages, it was the church that caused a demand for wine). Keep in mind, this family would likely have to be nobility to maintain control over such an area, but that's not in the bounds of the question.
<http://www.thefinertimes.com/Middle-Ages/farming-in-the-middle-ages.html>
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There are many reasons why islands are not normally breadbaskets in real life, you could go around the size limitation by putting an old volcano on the island, some ancient eruption filled with rich red soil.
Alternatively, go for fishing. These islanders could be the best fishers around.
But island-nations are usually knwon as trading hubs, just think about the British Empire and how that one tiny island managed to conquer so much land.
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I would say it's totally possible to feed 5% of the capital's population...
During that period in France, 1km2 of crops could feed up to 100 persons (with the best crop yield).
So you would need at least 500 km2 of cropland to feed 50 000 persons.
That means you can feed your own population with at least 7% of your island dedicated to cropland.
If you use 14% of your land to produce crops, you can feed your people and also 50 000 persons in mainland (5% of capital's population).
With 21% of croplands, you can feed up to 100 000 persons abroad.
By the way I would add a few volcanoes on your island, to increase soil fertility.
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What would be the hypothetical conditions for an Earth-like planet to have tundra or taiga as dominant biomes?
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Taiga [is the largest non-oceanic biome](https://en.wikipedia.org/wiki/Taiga) on Earth. But if you want it to be even more prevalent, take your pick:
1. A thinner atmosphere unable to retain as much heat.
2. An orbit closer to the outer edge of the star's habitable zone.
3. Smaller oceans; like the thinner atmosphere it would mean less heat is retained and distributed around the globe.
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Assuming you are talking about non-oceanic biomes that is fairly simple. Just remove all the parts with wrong biome.
Basically you'd only have continents in 45° to 65° latitude in both northern and southern hemispheres. Make them old without large mountainous areas to mess things up and leave gaps to get oceanic heat transfer between the huge tropical ocean and the polar oceans.
The planet would probably need to be farther away from its star to compensate for large tropical ocean reducing albedo and for the continents being bit farther from the poles than taiga is on our world.
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I suggest that the axial tilt should be zero. That way the long polar nights can be avoided and there is a greater area for forest.
The distance from the sun should probably be moved out a little to cool the planet down.
The oceans should be arranged more in the tropics where the rain forests and deserts currently are and extra land should be provided in the northern and southern higher latitudes.
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I've seen a lot of suggestions about orbiting the planet further away from its star and reducing the axial tilt. I'd like to point out that you also have to keep an eye out for dead horse zones (<https://en.wikipedia.org/wiki/Horse_latitudes>) and other natural phenomena that will cause barren areas, or relatively warm areas.
Also, note that like on earth, people will prefer to settle in places that are hospitable. If you have any point where the temperature is warmer, or the weather conditions are good, people will want to settle there. Tundras are harsh places, and there is a good reason why they are among the least settled parts of our world.
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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.
An alien race decides to test the hability of humans to survive and engage into space travel, for whatever reason.
# The planets
The aliens prepares a pair of Earth-like planets revolving around a common center of mass around a Sun-like star. The planets are very similar to Earth in mass, size and composition, and revolves around their common center of mass in almost-circular orbits, with a diamater that is twice the distance between Earth and Moon. They are not tidally locked one to the other. Lets call those planets **Old Paradise** and **New Paradise**.
Both planets are similar, and features plentiful food sources and fresh water readily usable for humans. The air is fresh. They also features a lot of natural mineral resources. The planet is covered by seas, grasslands and forests. It has plenty and diverse fauna and flora. However, dangerous or toxic bacteria and virus are absent. There is also no poisonous plants or animals. No animal or microorganism is able to live as an human parasite. No animal is more dangerous than what a dog would be. Those planets are almost like a paradise.
There are some glaciers, volcanos, deserts and very high mountains also on the planets, but those are very far from the equatorial grasslands. The climate is milder and more reliable than what is found on Earth, but there is still some danger from heavy rains, floods, landslides, lightnings and mineral toxicity. Earthquakes, tsunamis, tornados and typhoons are rare, much rarer than what happens in Earth, but they are still present and might happen occasionally.
# The humans
The humans used in the experiment all speaks the same language. They are numbered in 100 millions. Those humans are men and women with Einstein-like intelligence, all very healthy, both physically and mentally, and aged in their mid-20s. They are also perfectly able to have children which would also be able to have children and so on.
Those people are scientists and engineers. They also feature genetic resistance against old-age illness, like pulmonary, brain or hearth diseases and cancers. Since there is no biologically pathogen available, this means that they would not naturally die before they lived beyond their 80s or 90s. However, even if nature is more forgiving than what happens in Earth, people still might die from falling off a cliff, drowning in the sea, being crushed in a cave or mine collapse, being poisoned by ingesting some dangerous mineral, being eletrocutted by incorrectly handling some machine and so on.
Many of those people have deep knowledge in physics, chemistry, math, biology, medicine, geology, engineering, economy, logistics, robotics, etc., each one to his/her own expertise. Those humans, collectivelly possesses the knowledge of everything relevant for them that humanity knows in 2015. I.E, there are a lot of people who know about how to create and study graphene and electronics, but they might not know or care about what would be the last musical hit here on Earth or what are the most recent memes being shared in facebook.
# The objective
Are you curious why the planets are names **Old Paradise** and **New Paradise**? Well, first because those planets are like paradises. Second, because the aliens warned them that in 60 years, a huge bollide will strike **Old Paradise** and kill whoever is left there, transforming it in an inhospitable wasteland with unbreatable air, lava lakes and boiling acidic seas. All the 100 millions humans are then settled in an area of **Old Paradise** called **Eden** (more on that below). Their only hope is to be able to evacuate everyone to **New Paradise**, which will be spared and sustain human life for some more millions or billions years.
Those people are very smart and they all know that they must work together the best to be able to leave **Old Paradise** ASAP. Also they all have a deep desire to survive and to be able to successfully evacuate this planet on time. This makes those people all very willing to cooperate and survive, and are very altruistic one to the other. They are also workaholic. This also means that they are really interested in not wasting time and energy with wars, crimes, greed, disputes over natural resources, endless debates about politics, making money only for the sake of making more money, dedicating their knowledge to frivolous and uneeded purposes or to anything that may distract or divert them from their evacuation objective. However they might still be interested in playing games, have parties and have fun in order to enjoy their lifes and not getting too tired or depressed. On the other hand, since they know that **Old Paradise** is going to be destroyed and should be evacuated ASAP, there is little to no need to concern about environment and natural resources preservation or about pollution.
# The Eden
The people are initially distributed in an area called **Eden** in **Old Paradise**, which features some grasslands, meadows, rivers, beaches, small mountains and small forests within a radius of something like 1500 km. This way, those people would be able to eventually contact everyone quickly enough while also being able to take food and water from the nature.
Initially, the aliens left everyone in the planet completely naked, barefoot and barehand, and there isn't anything artificial human-made or alien-made provided for them. All of what they can start to work out are plants, animals, stones, water, soil and rocks.
Also, in order to properly answer this question, you might also add watever animal, vegetal or mineral resources are present in **Old Paradise**, especially in the **Eden** area, as long as you don't add something that is not likely to be a creation of nature.
# The question
Now the question: Is it possible that they might succeed to evacuate **Old Paradise** and sucessfully settle **New Paradise** with a minimal human life loss?
The humans have full knowledge of our current digital-age technology but are left only with stone age technology available. Are they able to bring everyone to **New Paradise** via space travel in 60 years, or they are all doomed to die when **Old Paradise** becomes a hell overnight?
Further, how would their technology evolve in the mean time from being naked with barehands and barefoot to achieving hability to perform mass-scale space travel?
If in the given scenario, they are simply unlikely to be able to reach their objectives in time, what are the minimal set of changes needed that would make at least something plausible that they would be able to leave **Old Paradise** *en masse*?
[Answer]
It's not likely that they'll survive.
Think of it like baseball. I could do all the math, all the physics, all of the calculations needed to know exactly where, when, and how hard to swing the bat in order to hit a home run. But that doesn't mean I can actually hit a 100MPH fastball.
Similarly, having the requisite knowledge to build rockets capable of escaping the planet doesn't mean that they will be able to.
The key here is that they're starting from literally nothing - no clothes, no tools, no infrastructure. Let's just run through what they need and we'll see why they're so screwed.
**Metal:** They need to get a mining operation set up in order to get the metal they need to build the rockets. This will mean finding, extracting, and processing ore before smelting it into something actually usable (more on that in a bit). They need to do this without having factories, mines, even a simple pickax or shovel. They'd essentially have to get ore by bashing rocks together until they get enough ore for pickaxes, which they could then use until they got enough ore for a half-decent drill. Even still, they'd have to get a group of blacksmiths (Note: using "blacksmiths" as a generic term for "people who make stuff out of metal", because it's easier than going into great gory detail about every type of metal that would be involved) going at it because of the lack of industry, so it'd be incredibly slow work.
**Infrastructure:** Let's suppose they get lucky and find massive deposits of ore that are easily accessible so that they can get a mining operation going quickly. Great! Now how do they quickly get it from the mine to the blacksmiths? Or the finished product from the blacksmiths to the rocket assembly facility (more on that later)? Where are they getting their food? Moving rockets long distance is not feasible without tech (the crawler that NASA uses to get rockets from the Vehicle Assembly Building to the launch pad moves at a pace of 1 MPH). In order for this to work, at the very least they would need a road system in place - whoops, that's more work they're gonna have to do.
**Food requirements:** Feeding a hundred million people takes a lot of calories, especially when they're doing manual labor like mining, smithing, building roads, building rockets, etc. Implausible as it may be, we'll suppose that large herds of animals (deer, bison, etc) haven't learned to leave Eden alone and they're easy pickings for anyone with a decently thrown rock. The rock throwers will be the main source of food until they can get enough hide (leather) to use for slings, or until they can craft bows and arrows. But a hundred million is still an awful lot of people to sustain from hunting and gathering. It would take some very clever math to figure out how much you can hunt without destroying the herds entirely (because we'd like to still be eating come year 50).
**What do we do?:** They have the knowledge of what is needed. That doesn't mean they have blueprints, CAD designs, etc. They'd need to plan out how the rockets will actually work, and they'll have to have a design chosen by the time the mines get operational so that the blacksmiths know what to actually make. And they'll have to be made very well, because we're dealing with space. Challenger exploded because it was too cold for one of the parts. When Hubble was first launched, the picture quality was awful because the mirrors were out of focus by a few microns. Precision is very important with space, and they won't have many chances to get it right.
**Rocket assembly:** Okay, let's get into the actual rocketry bit. Currently the only rocket that has taken humans to another planetary body is the Saturn V, so I'll use that for estimates. They'd have to be able to get massive hunks of metal firmly in place 300 feet in the air. This will either require a crane system (which will need to be metal and strong enough to lift rocket stages - the stage at the top which held the astronauts was about 23,000 pounds, and they got heavier as they get closer to the ground.
**"How do I fly this thing?":** Again, it's one thing to know how to do something, and it's another thing to actually do it. There's a reason that astronauts train on simulators for as long as they do - if they mess up even a little bit and can't fix it, they're dead. And these things would pretty much be under manual control, unless they were able to program the computer to- oh, wait, stone age, they'd have to develop computers in order to do that.
**Population:** I'm bringing this up now because it'll tie into the next part. How many people are going up? Based on the OP, the people are in their mid-20s and will live until their mid-80s for the most part. Unfortunately, that's exactly when the asteroid is hitting the planet. So while we COULD launch people on their deathbeds to another planet, it probably wouldn't be smart. We'd want them to have had children to make it easier to establish life on New Paradise. Besides, using a ballpark of menopause at 40, they'd need enough women under 40 to be able to sustain the population But that increases the number of people we're trying to send. Let's say that people pair off and have one child per pair around year 10 (they're in their mid-30s), giving a grand total of 150 million people, then 175 million when that generation turns 20 in year 30 (as the original generation is now above 40), and then about 200 million in year 50. That generation would turn 20 after reaching New Paradise. The actual number would be a bit higher, but for hand-waving purposes we'll say not everyone gets pregnant or some people died.
**How many rockets?!?!:** Saturn V carried three people. We have 200 million. Now, we can probably cram a bit more, since it's a life or death situation, and we can remake some of the hardware (like we don't need a lander that can also leave the surface again) to fit more people. Let's say we can cram ten people into a rocket (for reference, the International Space Station usually has six people on it). That still means we need to make 20 million rockets to get everyone off the planet. Which is a hell of a lot of metal, but that's not even the biggest problem.....
**FUEL:** Ah, energy requirements, the bane of all things fun. Saturn V used about six million pounds of fuel (5.6 million in the launch stages, and I can't find numbers for how much the lander used, so I'll cheat a bit). We have 20 million rockets. That's 120 trillion pounds of fuel. Good luck with that.
**Consensus: Not Feasible**
There are just too many issues to overcome with getting from the Stone Age to the Space Age for it to happen in sixty years, even with the knowledge already there. Honestly, their best bet would probably be to have a group of them working on the laws of physics to try and find a way to rig up a teleportation device to get them from one planet to the other. And when developing teleportation is your best bet, something is wrong.
Now, what could we do to improve their chances? Obviously starting them with good tools would be good. I'd also say give them an established infrastructure system (ie roads and bridges) that they don't have to worry about building and maintaining so that they can actually get started on mining and processing ore as quickly as possible. Unfortunately there's just no real way to get around the lack of industry. Assuming a 365-day year like on Earth, they have 21,900 days to build 20 million rockets. That's just over 913 rockets per day. Give them pre-existing factories, even if they're just skeletons of buildings that aren't currently doing anything, and maybe they'll have a chance. But at that point they aren't exactly in the Stone Age.
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I'm sorry, but your human population is doomed. Regardless of their intelligence, knowledge, dedication and fear of dying, they're trying to bootstrap an entire civilisation from the stone age to high-occupancy short-range spaceflight in practically no time at all.
In fact, if all 100,000,000 of them are deposited in the same area of Old Paradise, there would be mass starvation as they stripped the landscape for everything edible, and then found that the appetite of such a huge number of people is such that they could literally not run fast enough away from Eden in order to gather enough food before everyone starved to death.
Then, when a few thousand survivors managed to escape into the wilderness and relearn the skills of being hunter-gatherers, their high-tech skills and knowledge would be worthless in the face of the daily grind to merely survive, and it is likely that with knowledge of the impending disaster, depression would set in in many, leading to a further wave of deaths from suicide.
So, far from proving that humans are resourceful survivalists, the alien scientists would be embarrassed that they have engineered a situation *impossible* for humans to survive.
In order for this scenario to be survivable for the human population, we are going to need two or three alterations - a *much lower* initial population that includes those with knowledge of agriculture and wilderness survival and a more distant deadline, on the order of 400 to 500 years. A higher initial technological level would allow a significant reduction in time.
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This answer is a bit of a stretch, and isn't *technically* the answer asked for by the OP...
Instead of trying to build sufficient lifting capacity to move an entire population - or at least part of one - to a 'moon', on being told that there was a bolide set on a collision course with Old Paradise, and that they had 60 years before impact, I can imagine that these rocket scientists would be engaging in lateral thinking.
I'm also pretty sure that at least one of these scientists would come up with a solution that these aliens may not have anticipated - save *both* planets.
How do we do that?
Step 1: Feed the starving masses. It may take a year or two, but we have to get plenty of separation between our settlements so that the land won't be overtaxed. This could be quite difficult, but we have motivated people...
Step 2. Go for high-tech manufacturing capability. This is the tough bit, but for the purposes of *this* answer, you don't need a whole lot of it. This may take forty to fifty years.
Step 3. Build telescopes and plot the local asteroids and the like. Anything big enough to do a number on Old paradise has to be big enough to spot a fair way out. It may take thirty years to get a decent telescope or three, but that should be soon enough. This can take place concurrently with step 2.
Step 4. Use the high-tech manufacturing capability to build the biggest [Ravening-Beam-Of-Death style FEL x-ray laser](http://www.projectrho.com/public_html/rocket/spacegunconvent.php) they can and place it on the highest point of the highest mountain. It would be better launched into space, but the mountaintop location may be the best that there is time for.
Step 5. When the bolide comes into sight, focus the x-ray laser on it - specifically one *side* of it - flip the switch, and keep blasting until the ejecta plume of vaporised rock/iron/whatever from the point of impact forms an impromptu rocket engine that pushes the bolide sufficiently off-course that no impact will occur. The longer the time before impact, the easier this will be. Catch the bolide a year short of impact, and you could generate a miss easily. A month? No problem. A week or less might be cutting things a bit too close.
So, this *doesn't* involve transporting the population to the other planet ahead of the impact, but it does allow them to get there in a far more leisurely manner, having averted the impact altogether. If the aliens wanted to make sure everyone tried to get off the planet on schedule, they shouldn't have been so specific as to what the disaster was going to be.
This has the advantage that a relatively small manufacturing base is needed, as opposed to that required to build sufficient lifting capacity to extract the entire population - or enough of it to form a self-sustaining colony - to New Paradise.
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This is one hell of an emergency flight. Let's see if they can make it.
For problems as these, it is best to use a reverse approach. Here's how it's done. We are not going to begin with metallurgy, but rather with spaceships and go back to prerequisites for every step and see if we can make it within 60 years!
**1- Building A Spaceship**
3 years I say. AT LEAST. Since all the population is working coherently 24/7, they can build a large enough spaceship within 3 years. Notice that the parts would have to be built on separate places, you don't have to pull all the population on one point for that.
We have 57 years left to reach spaceship building technology.
**2- High End Technology Labs And Production Units**
We have all the required material here (metal, plastics, fibers etc) and we want to build hightech production units for constructing a giant spaceship. Since they have all the knowledge and guidelines, the only headache is practical, not theoretical. There is no issue of "how to do that?" The only issue is "lets do it buddy, and do it real fast!" 7 years I say, no less.
We are left with 50 years to reach this stage where we are capable of building spaceship production units.
**3- The Industrial And Technological Revolution**
We have refined metal and plastics here and we want to make the industrial revolution happen. That is, we want large scale electricity production, we need to invent the integrated circuit, the internal combustion engine, build very large production units and start carrying out complex calculations on some really fast computers.
How much time for all this? 25 years I say. First 10 for building the electrical framework that is a prerequisite and the next 15 for building and improving the integrated circuit technology. This is the time interval required while we know WHAT exactly we want and HOW to do it.
We have 30 years left for reaching this stage where we have large metal refining and abundant plastics production units.
**4- Metallurgy**
This is not as easy you think it is! Metallurgy involves digging up a metal ore, having huge structures to roast, smelt and filter it and add additives to it for tensile strength (i.e. converting iron into steel).
10 years here. We won't be producing enough steel and aluminum to develop skyscrappers with our small metal refinement units, but we will have enough metal for building a large spaceship, nevertheless.
Once we get to refine our first 1000 tons of metal, we can develop steam engines, which will revolutionize our progress speed.
We have 20 years left to reach metallurgy stage now.
**5- Mapping The Planet**
We are a group of people limited to one region of the planet, and we need to map all the regions of this planet and it's resources. Fast, fast, FAST!
Send in parties to all directions for a distance of 2000 km from our starting point. We won't have more time than that. Yes, more than half of the planet will be left from exploration, but we can't waste more time on exploring the planet!
Since there are no dangerous animals, insects etc, our parties make their round trips within 6 months (on foot of course). This means they will have to walk 22 km per day. Not too much to ask for, if you ask me.
Now we have a limited map of our planet, marking the surface resources in our vicinity.
1 year would be required for mapping 2000 km radius circle AND recording the findings on leather parchments, wooden sheets etc.
19 years left to reach this stage where we are ready to begin metallurgy ventures.
**6- Basic Tools Production**
We need a lot of basic, prerequisite tools before we can think of the next stage. Shovels, crowbars, lots and lots of paper (leather and wooden sheets would serve for it) and things like these. These are going to be required in large amounts!
Try different wood types. Find the suitable ones. Make stone tools for woodworking. Start a large scale production of these primary tools. 3 years for this stage.
16 years left till we are able to take this first step!
**5- Develop A Colony And Establish A Social Structure**
We are a band of unruly people. But we do have a know-how of advanced social structures. Since there are no disputes between us and there are no "politicians" among us, we can successfully design a social system quickly. Since we know what we want to do, let us organize our population in categories of engineers, surveyors, builders etc.
2 years to design a social structure for our population and listing down the expertise of every individual.
14 years left from the start now.
**6- Where The Heck Are We And ... What Is This Place???**
We are freshly transported on this planet and we want to know what it is and what dangers we might face. It's everybody to himself at this stage. There are expected to be feuds, murders, anger, depression, rapes, deceit and whatnot at this stage. Once we get to understand that this planet is only our temporary abode and we must act together, crimes will stop and people will come closer (socially). A social structure can now be built.
I think 7 years will be passed in these "dark ages" era of this planet's human history.
After all the math, we are left with 7 surplus years on our table. This means that even if one stage in our evolution requires a couple more years than we anticipated, we will not hit the extinction deadline with that.
We should be able to make a last minute flight out of this planet.
**THE MAIN PROBLEM**
The pioneers of this planet are all adults within reproducing age-range. They also have full technological know-how of modern day science. Problem is that with time, people age. Of course babies will be born who will replenish the lost population count, but babies aren't born with all tech-know-how. Babies have to be taught these things. Here on this planet, there are no books. There are no science labs or libraries or schools. And even if they learn some basic things with apprenticeship, these 2nd generation people will not be as much focussed on the mission of escaping the impending doom as the first generation. These, seeing there is no immediate threat to their survival and that the environment is teeming with lush green pastures, plenty of game and food sources, are very very likely to deviate from their purpose and consider their elders as fools.
And ... by 30 (maximum 40) years, most of the 1st generation people would be dead and the project would be left for completion with the 2nd generation. These will be quarrelsome, egotistic teenagers who would want to just sneak into the lush forests with their bf/gf and do their thing, instead of focussing on the goal of their elders.
So yes, the humans on this planet are doomed. But not because they don't have enough time, but because of death and age, the task would be left with 2nd generation who don't have technical knowledge, nor are interested in designing of the spaceship.
More like people of Noah's time if you ask me. "Come on old man! Don't jinx us. A shooting star is going to fall on planet and destroy it after 30 years? Oh boy, you're getting senile, I can tell! Emily, look what Mr. Naddley is on about!"
[Answer]
You are very optimistic about our ability to survey and discover minerals, dig mines for raw minerals, develop industries to turn minerals into raw stock, find reserves of petroleum for energy, develop precision machine tools and heavy equipment, etc. It took 4 years to build the Golden Gate bridge. It took 6 years to build the First Transcontinental Railroad. It took over 20 years for Boston to complete "The Big Dig". It tooks 35 years to construct the US Interstate Highway System. These were all built with existing technology, tools, equipment, material supply chains, trained work-force, the best established industrial support infrastructure on the planet, by the richest nation on the planet.
I have a theory that the time it takes for us to develop and deploy technology is about equal to our ability to invent it. So starting from illiterate stone age people it takes about 8000 years to get two people to the moon. Starting from a planet full of highly trained engineers also wielding only stones, it would take them about 8000 years to get two people to the moon. Maybe a little bit less if nobody went on vacation and there were committees to decide who gets to get to dig the mines to extract the natural resources necessary... and there were no disagreements about work assignments.
This may sound like a stupid theory, and it's impossible to test, but I think it's a better starting point. You should **start** from the worst case scenario and then work toward optimizing your goal. Start with a presumption that it would take cavemen 8000 years.
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I have a number of intelligent alien species with a high number of limbs (from 6 up to 18) some with radial symmetry and some bilateral, in most cases the creatures can crawl using all limbs but when doing task the hind legs (3 to 6 depending on limb number) become the legs supporting their weight as the raised up front of the body uses the rest of the limbs as arms. I also have other species with very high numbers of simple appendages, similar to echinoderms.
I have some species which I have elements of their physiology but I have not decided on the limb number (although I do prefer more than 4 with 2 as arms). I believe there is a point where more is not better, as they will involve more brain power, blood/nutrient supply and sensory methods, and there comes a point where less limbs can reach all the places and carry out the tasks that more can.
These alien designs will be for my technologically advanced species, they will be spacefaring and will need to complete tasks and progress in a way that is similar to humanities path to becoming technologically advanced.
Is there theoretically a most efficient number of arm-like appendages, where anything more requires too much additional support systems that it would in efficient for a creature to evolve and supply necessary requirements for survival?
[Answer]
# There is No Number
There is no ideal number of appendages because there are too many demands made of limbs in various circumstances.
Evolution is not the "survival of the fittest" but "survival of the barely adequate." If nothing is actively selecting against or for a trait, creatures with that trait will stick around (all else being equal). This is why we have creatures with many appendages, detachable appendages (sea stars), none (some parasites), and more in between!
# Major Factors
Many factors for appendage number and type exist, but some of the big ones and things to consider are are:
* Movement: does it like swimming, mud-skipping, running, climbing...?
* Object Manipulation: has this critter the need to build shelter, hold offspring, groom themselves, contribute to world building overflow, etc...?
* Food Acquisition: can the appendage help with cracking shells, neutralizing prey, collecting floating particles, grabbing a berry, etc...?
* Predator Evasion: can the appendage help with running away, hiding, intimidating...?
* Body Plan: is this limb part of a repeating pattern?
There can be more factors, but consider these when creating the initial design of "realistic" creatures. Going lower may make sense from a locomotive perspective but not from a body plan or object manipulation perspective.
In all, limbs need to be only "good enough" for survival in whatever environment the creature finds itself in and the lifestyle it leads.
In terms of these aliens, long term spaceflight and tool use are simply *more evolutionary inputs*. If an adaptation increases their evolutionary fitness, you'll see more of it. It does not really matter if the adaptation is diminished or lost limbs, better beaks for opening walnuts, finer motor skills, or what-have-you: evolutionary pressures still apply!
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**Definitely Four!**
I, as a human who sometimes uses a soldering iron, would find it incredibly useful to have four hands. Two to hold the items being soldered together, one to hold the soldering iron, and one to stop my glasses falling forward.
The limbs doing the finer work would be higher up the trunk and nearer to the eyes so as to be seen clearly. The eyes would be above all the limbs as light generally comes from above.
In fact two very strong, vice-like appendages for rough and tough applications, plus two appendages similar to human arms and hands for doing finer work would be ideal. Beyond that number, I think that central coordination would simply be too difficult to achieve with a multi-tasking brain. The complexity of synchronisation grows more than linearly. Already we have trouble rubbing our stomachs and patting our heads at the same time. The two lower arms could be mostly static and used for holding workpieces in place.
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I most closely agree with PipperChip, but not quite.
Points:
* Best and second best are not too far apart. The advantages are not going to make pinnacle predator and extinct as much as give one more advantage in one terrain and another more advantage else where.
* In space the costs are going to be very high, and radiation is going to be the #1 adversary (by far far far). Cosmic rays are particles that have 10^20 eV and neutron radiation from cosmic-rays interacting with stationary matter kills organic material, and semiconductors, like a literal plague.
On earth we have a lot of examples, and while they may not be "everything" they are more than nothing and they tell us some important things.
* Fewer is better, because simplicity is better. Costs can be high.
Things with more than 2-arms and 2-legs or even 4-legs tend to be
very small, or require much higher oxygen and a more soupy atmosphere
to be large.
* Biology seems to find a "good enough" in the larger structure and work with more small-scale variations within it, consider how many many many insects are 6-legged (3-segmented) creatures, and consider how many insects there are.
* Biology finds bilateral (or more) symmetry to be efficient (likely because of error checking, and denser dna), so creatures tend to work in multiples of twos. (4-mammal, 6-insect, 8-arachnid, 10-decapod, ...)
There are simulations of evolution where creatures try to evolve to do mechanical tasks. OpenAI and google had a bender on them a while back. Might look at dusting that off, and trying it out on a mock-satellite or such and see what mechanical configurations show up as most useful. Let the computer surprise you, and if it does a decent job, then don't just put it in a novel, do what the "Interstellar" folks did and get it published in peer-reviewed journals. ;)
EDIT: More thoughts.
Astronauts treat water like it is zero-g, because buoyancy helps it act like that, though without radiation and with a pressurized operating fluid around it.
* You could look at aquatic micro-organisms and diatoms. [link](https://www.nikonsmallworld.com/galleries/2007-photomicrography-competition)
* the burgess shale has some very intersting paleolithic organisms [link](https://listverse.com/2017/10/21/10-bizarre-organisms-from-the-burgess-shale/) Obapinia, Hallucigenia,
* you could replace fins with solar-sails or ion engines of some sort.
* solar sails would collect atoms for use as material or fuel
* Ive thought for some time of a "universe of mind" where the brain is
a quantum antenna and consciousness isn't intrinsic to biology, but
it allows the consciousness in another sort of universe to act out,
somewhat like inter-dimensional "surrogates". It is a different take
on "soul". A space-based organism could have a very different
neurology, and maybe couple to elements of "universe of mind" that
are very different from terrestrial ones.
* scale is interesting. big things on earth need lots of food. I've wondered if suns/stars are conscious and talk to each other over millions of years. Are there carefully structured whorls and solitonic wakes in the solar ejecta that are electromagnetically active, and count as conscious mega-sized, vastly empty, gas and dust structures?
Links:
* <https://www.space.com/27539-interstellar-black-hole-physics-video.html>
* <https://techcrunch.com/2021/10/06/simulated-ai-creatures-demonstrate-how-mind-and-body-evolve-and-succeed-together/>
* <https://www.nature.com/articles/s41467-021-25874-z>
* <https://www.nature.com/articles/s42256-021-00320-3>
* <https://phys.org/news/2013-05-digital-life-openworm-source.html>
[Answer]
The optimal number isn't necessarily even, and they may not all be equivalent.
Niven and Pournelle described a roughly humanoid alien species (“[Moties](https://scifi.stackexchange.com/questions/40467/any-artists-concepts-of-moties-published-in-20th-century)”) with three differently-sized arms in *The Mote in God’s Eye*. The Moties were described as being significantly more adept than (bilaterally symmetric) humans at grasping and manipulating objects due to their having a range of different tools at hand, so to speak. They could exert a large force to hold or bend an object with their largest hand (the gripping hand), and work delicately with fine motor control with their smaller hands.
Most animals we know of are approximately symmetric (radially or bilaterally) with a few noteworthy exceptions like [fiddler crabs](https://en.wikipedia.org/wiki/Fiddler_crab) but note that the 8 arms of an octopus are not identical, any more than the 5 digits on your hand are identical. Each pair of appendages of bilaterally symmetric creature is likely to be somewhat different from the other pairs, specialized to some degree for different tasks.
[Answer]
**Two**
Regarding 2 vs 4 limbs for advanced species. With 4 limbs each is at half the strength and coordination: for the same overhead you could have 2 arms that are better. The better arms will outperform when tasks can't benefit from extra limbs. When you need 4 limbs get an assistant, improving social bonds. If extra limbs helps it needs to help the species pre-technology. After that they access mechanical augments, genetic engineering and advanced interface tech. We need only our mind and some reliable signals sent out. Thought control sounds unstable. Touch interface will stick around. Number of fingers is important.
Regarding life generally. As child I drew creatures and assigned them many abilities. Wondering why don't all creatures have venom, flying, scales, lungs and gills, excellent senses in all conditions, and being completely massive of course. Selection doesn't follow the rule of cool. It's better to cut junk. Successful species are often minimalist in design. Special abilities have overhead and force you into a niche. Multi-purpose is good. I like rats, they use their teeth to eat, carry, tunnel, fight. Hooved animals use their whole body to fight: biting, kicking, body slamming.
How good an arm is could max out. More arms will sometimes outperform less. Many tasks are muscle memory: 4 arms could easily be trained for repetitive tasks: memorizing a harp piece. Weaving or sewing leads to biting the string or cinching in knees: I always feel like a 2-armed loser.
Feet that double as graspers is pretty good. I feel like a clumsy-toed freak.
[Answer]
**The needed for the moment.**
The best body would be the one that can adapt to every situation, if he needs to grab something then he will split his arm in two, if he needs to work with something that requieres four arms then he split his arm in four.
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**Closed.** This question is [off-topic](/help/closed-questions). It is not currently accepting answers.
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You are asking questions about a story set in a world instead of about building a world. For more information, see [Why is my question "Too Story Based" and how do I get it opened?](https://worldbuilding.meta.stackexchange.com/q/3300/49).
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The time setting of this world can be from near 2000 to present day, to near future. But basically, Aliens from around the galaxy are visiting Earth...for our TV series/movies, animes-manga, and tabletop/video games. They could be doing this secretly (like buying disks or downloading them, ore even illegally-live stream them), or openly signing treaties with Earth companies to obtain re-broadcast or selling rights. And alien otakus are painting their waifus on their spaceships. The aliens are far more advance than we are, with technology to breakthrough lightspeed. The least advanced of them are at least a hundred years ahead than we are. The point is, why? Why could such a technologically backward planet conquer the whole galaxy culturally?
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Other civilizations in the galaxy are much older, more mature, spiritually enlightened. They have all achieved stable societies with unlimited access to fusion energy and resource abundance and as such spend much of their time (when not studying their scriptures) in silent meditation.
Their sense of humor necessarily revolves around regarding those who have failed to achieve spiritual enlightenment as inferior and (like our schadenfreude in a way) hilarious.
Naturally, much of Earth culture revolves around cultural/religious conflict and personal conflict in relationships, not to mention money grabbing, perverse incentives in marketplaces and the general self-centered self-deception of people trying to justify their own existence through lying and concealment of the facts.
Basically, they think we're absurd figures in much the same way as 1950's US might have viewed the Three Stooges, and serve as object lessons for the young of their races where at schools our cultures are studied and ridiculed.
Credit to J. Michael Straczynski's Babylon 5's Minbari humour for the idea.
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Why would you need an explanation at all? Obsession with foreign cultures is a thing which happens again and again on in our own world. This arguably happens more with "backwards" cultures as they are perceived as more pure and uncontaminated by modern influence. Whole tourism industries live off of the romantization of local customs and aesthetics.
Usually these are short-lived crazes, but the alien society might have a much longer trend cycle where a cultural obsession does last a lot longer.
But if you really want some booster to their endearment: Perhaps humans have physical or mental attributes which remind them of their youngs, so humans and their culture trigger a natural nurturing instinct in them. Or in other words: They think we are cute.
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# Earth media is cheaper / easier to get
The Galactic Prosperity Cooperative has an extremely burdensome set of intellectual property laws. Even in the Cooperative's early days, the laws were extraordinarily strict by human standards, and restricted creators just as much as consumers; one of the co-founding species had very strong feelings about the concept of "the sacred artist". Now, tens of millennia later, the laws have grown so complicated that only AIs can administer them properly.
The upshot is that the aliens don't produce much commercial entertainment at all anymore, and when they do, only the wealthy can afford it. Their equivalent of a movie ticket costs a month's wages for the average worker. And the poor stiffs don't even *think* about trying to pirate the stuff, because the IP AIs have both crazy DRM and crazy spying capabilities.
By these standards, Earth is practically giving its entertainment away for free.
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## Most races are forever alone herbs.
With the infinite energy of dyson spheres, endless land space of planet ships, and population control common to educated societies most aliens have never seen another alien in person. Their cultures value independence and getting all your needs from holos.
This has stagnated ideas of emotion, connection, and romance. They have very vivid medias with extreme violence or sex or base appeals to emotions, but their lack of understanding of connection means that any real connection in their media is rare.
Earth still has romance and friendship and connection, and so aliens across the galaxy value their entertainment. Not generally, mind you, enough to meet other aliens. But enough to go to earth to get their media.
[Answer]
Well, at our technology level, the aliens will have to come to us. This implies that they are likely technologically more advanced than us. The most likely cause in a general sense is that Earth culture and/or entertainments provide something that the various alien species lack or find endlessly interesting.
Each species will have their own reasons for enjoying specific cultural entertainments from Earth of course which in turn will depend on *their* culture and society.
### Creativity and Fiction are Human's "Hat"
Most aliens can create in some capacity, but humans are singularly better at it. We dedicate much research and time into improving our visual effects, training young minds in the art of storytelling and production of these stories into other mediums. There is an entire sector of our population that strives to entertain others, sometimes at their own expense.
This is not to say that the various alien species do not have entertainers, even world-class ones. It is that, on average, humans are better than them at this.
Why that is might be an object of exploration in the setting. Perhaps part of the reason is because we are not unified as a species like others are -- cultures can rise and fall, and with it new form of culture appear.
Perhaps because we haven't seen the universe in person yet and as such can only speculate on what is out there, we produce science fiction with a certain naivety that the aliens can embrace, if only for a while. Some of our wild ideas might even be feasible with the right tech even if we don't know it. Perhaps our sci-fi is so wrong, that it is actually more like absurdist comedy to them.
That we can create all sorts of magic and fantasy worlds might be breathtaking to a more advanced species whose idea of fantasy are ... well ... like us really. Swords and sorcery might be a whole new genre for a species that knows empirically that magic can't exist because they've discovered the Grand Unifying Theory and so rarely consider magic in their fictions.
But overall, we have different ideas and give a voice to a very wide variety of ideas compared to other species. Earthlings, through our many diverse cultures, have created a very wide body of cultural entertainment that there is almost likely something that will appeal to any particular alien species out there.
Perhaps the reason that we don't get past our solar system is that we are being constrained so that we continue to produce entertainment.
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# Earth has many cultures
All of the other alien societies have long ago put aside their differences and combined into one large culture. Every now and then, another alien civilization comes into contact, and their culture interests all of the other aliens. Earth is not united. There are many cultures on earth, which create many different types of entertainment. As a result, earth entertainment is diverse, and provides a much longer source of entertainment for alien visitors. This also means that there is something for everyone. Some people may like British humor, American Slapstick, or Japanese anime.
[Answer]
The aliens have very evolved abilities to model and predict - as required of long-lasting civilisations. So their artists have lost some of their more primal instincts. Perhaps alien art is extremely abstract, proceedurally generated, or computational in some other way.
Much of Earth drama/fiction, and human behavior ignores 'rational' decision making, or even introduces fantastical elements, story logic, etc - providing a novel balance of tension and surprise.
[Answer]
## Galactic Grownups
This is going to be a very broad simplification, but lets assume that any civilization capable of intragalactic exploration is more mature than humanity and not just more advanced. We could probably get to their level eventually but for now we are the equivalent of (human) children compared to the aliens being adults. So why would any alien be interested or even obsessed with our media?
Well, why are adult humans so interested in "children's" media? You can find plenty of examples of the same thing happening right here on planet Earth. Go look at the fandoms for something like Hello Kitty or any shonen anime. Hell, the biggest movies that have come out in the last decade have mostly been based on comic books, which until very recently were seen as the exclusive realm of children and emotionally stunted men.
All of this media that was originally for children also has a noticeable adult demographic and it can be for any number of reasons. Part of it could be nostalgia from when those grownups were still children, which wouldn't apply to our alien friends. But it can also be something about the visual aesthetic that appeals to us, or the story touches on some fundamental archetype that speaks to us, or even something as simple as it being a fun, mindless thing to watch when you want to turn your brain off. Aliens can have just as many different reasons for why they enjoy a less mature piece of media.
## "Isn't That Just Precious"
There is also the sheer novelty of seeing a less-developed civilization's media to consider. Half of the internet is videos of animals doing cute/funny/amazing things.I imagine that an advanced enough alien would have a similar reaction to the things that humans do. More serious academic type aliens might read the works of our best writers and analyze them through the lens of their own culture. But most aliens would probably want a simpler introduction to human thought and that would include the bulk of our visual media.
Aliens watching our movies or reading our comics or playing our games could happen at least in part because it was humans that made them, and not because they were good. Imagine if a toddler came up to you and said "I created this thing", even if the quality is lower than what you normally like you would still be impressed that they did it.
[Answer]
**Earth is on a cultural/technological sweetspot**
Advanced enough to produce appealing content,
Backward enough to be silly/funny
Too advanced civilizations produce extremely realistic experiences, but their advances also imply thinking of cultural consequences of these entertainment. Too violent? Banned, it will decrease individual's moral abilities. Too sexy? Banned too, individuals will be too inclined for reproduction, hampering with their intelectual abilities.
On the other side, too backward civilizations don't have the luxury to think of interesting entertainments, let alone capability of producing it.
Earth being on the sweetspot between the two, it produces somewhat interesting sensorial experiences, without the long term thinking that inhibits content production.
[Answer]
## Human senses are poor so human stories translate well
Humans senses are dominated by vision and sound, both of which are universal enough to translate well, there is no pheromonal subtext no magnetic impulse, no ultraviolet or other extreme parts of the electromagnetic spectrum. Humans sense are rather basic and accessible to most species. whereas most other species do have some other aspect of communication which either held back the development of entertainment technology of just makes it hart to translate. How do you translate the subtext of pheromonal signals for species that don't have it. Imagine trying to interpret bird art, which would be full of colors you cannot see, so much of the visuals would make no sense. Or imagine a book written by a dog with muted colors but detailed descriptions of smells full of subtext that just don't translate for species with a poor sense of smell.
True enjoying human stories a bit like enjoying silent films, but that's just it, you *can* enjoy silent films, you can enjoy a performance in a narrower set of senses but not a wider one. Most other species media has moved on to incorporated senses that don't translate for other species but humans media never did. Humans just happen to fall into the sweet spot of easily translatable sensory experiences. Once that advantage exists all human media gets more exposure, a rising tide lifts all ships.
Among species X their own media dominates for them but human media comes in second, for species Y it goes Y most popular Human media second, this second place spot quickly means it dominates across species, which results in more popularity as it becomes a commonality. A Vodit and a Plebert might have almost nothing in common but they both have seen Star Wars because it is easily accessible.
[Answer]
## Earth is a multi-biome planet. All the other aliens live on a single biome or limited biome planet.
>
> "If you mashed Hoth together with Tatooine, would it make a decent planet with nice weather?"
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> Kira Carsen, Star Wars: The Old Republic
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The problem is that most other aliens grew up on Hoth or Tatooine, single biome planets.
So, while they still have entertainment on their planets, none of them have quite the range of biomes to showcase, and multiple planets have to bind a bunch of entertainment bundles together so that people who want to see a planet that isn't like theirs, they can figure out the type of films and animations that are inspired by the landscape of another planet.
Earth? Earth's been doing that on their own - for the cost of access to any of Earth's many digital offerings, you can access entertainment that shows:
* Swamp biomes (In various different interpretations and time periods).
* Desert biomes.
* Rainforest biomes.
* Winter biomes.
* Island biomes.
* Desert island biomes.
* Vast ocean biomes.
* Prairie biomes.
* Mountainous biomes.
And more, not even accounting for the fantastical settings like a post apocalyptic biome setting, or fantasy settings around the idea of falling off the edge of the ocean, or space biomes.
Which leads into why aliens might want to actually invest in making their own entertainment locally on Earth - land a couple spaceships on Earth once with all the cast and crew for a film, and you can use going to different places on Earth as shorthand for going to Hoth or Tatooine biomes. You "Shoot on location", and it looks like all these other planetary biomes, maybe with some CGI to add in important landmarks.
Given all that, it'd be harder to argue that aliens would want media from *outside* Earth even if it was heavily subsidized.
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## The setting: 27th Century Alpha Centauri system
From everything I have seen, it is generally accepted that future space combat might not do very well with individual fighter-craft (similar to a modern F-22 Raptor but in space). In this narrative series, individual fighter-craft are a thing but they are rare. The pilots are enhanced humans who are modified to withstand higher G-forces than a normal human. One of the modifications is an internal fluid equalizer complete with Liquid Breathing. The goal is to allow the forces to pass through the internal organs and not catastrophically compress them during high-G maneuvers. Other modifications include a form on Mind-machine interface, adrenaline boosters and potentially faster brain processing abilities. Most of what I know I have gained from listening to Isaac Arthur (SFIA) or Project RHO, in particular [this page](http://www.projectrho.com/public_html/rocket/humanfactor.php).
Because of these modifications, the pilots are seen as gods, even among the military and special operations units. With the modifications they have, I am wondering if they would hinder them in a normal setting or would they still be better than a normal human? Something like, if their lungs and organs are set up for liquids equalization, then when there is no liquid would they be less efficient at breathing? Would they always require the liquid inside?
**Essentially, I need guidance on whether the pilots are highly specialized and only useful as Pilots, or if their special modifications will make them a super human and therefore be good at everything.**
**First Edit**
Thank you everyone for the answers and responses, lots of great ideas. I'm going to add a few more points here to clear up some of my reasoning for pilots. (Canon reasons)
* Drones were the primary fighter previously until some advances were made with MMI and biological enhancements. Also, multiple drone hacks were done so the public perception on them dwindled.
* Pilots are very rare and high value, ships will only launch them as a last resort. Each ship usually has a fee gunships (heavy and light) and then a couple fighters. The fighters are more akin to a lighter gunships with automated turrets and AI assistance than a traditional jet fighter.
* Various treaties have limited the use of drones (and other one-use large vehicles) as well as attempted to add responsibility to the fleets to limit debris in space (a large occupation sector in the series relies on scrappers cleaning up space debris).
Thanks again everyone
[Answer]
### Liquid breathing pilots are still biological. Embrace the machine and upload them instead.
Your hypothetical liquid-breathing pilots, regardless of their modifications, are still fundamentally biological beings, with biological limitations. They can still only withstand so much g-force, they have reaction times limited by the nerve impulses in the brain, and even with mind-machine interfaces, there's only so much information they'll be able to comprehend at a time.
Instead, just upload their minds and copy them onto the computers in the fighter planes. If they die during the fight, just reboot them from a backup copy on their carrier (or back at their military's HQ, if the carrier is also destroyed); if they don't die, you can just update the backup with their new memories. No fleshy limitations on G-forces or reaction times; they'll be as resilient as the electronics they're running on, and the only limitation on their reaction time is the computational power of the computer.
And, if they want to have a humanoid body to walk around with once they get back on the ship, they can just download themselves onto a humanoid drone, or access a VR system where they can represent themselves using whatever form they want.
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**Realistically they're still not going to be very good**
Liquid breathing isn't going to help with the brain which is nothing more than a mass of jelly in a hard box. You don't need to crack a skull to give a brain injury.
A Japanese dish is the Golden Egg which is basically scrambling the egg without breaking the shell.
[](https://i.stack.imgur.com/YHCUP.jpg)
Enough G-force and you'll scramble the brains anyway.
To avoid the g-force you need to either some handwavium tech like inertial dampeners or to not have the pilots actually on the fighter craft.
Personally I'd see enhanced pilots as generals controlling AI drone masses. Brain enhancements could accelerate the mind/machine interface allowing them to respond quicker and understand the entire three dimensional battlefield.
The other part is people take such a long time to produce. You have 20 years for them to mature, all the enhancements, training, and numerous washouts just to strap them to a rocket with a gun. It's better to keep the best of the best safe and let a mass produced drone do the dying.
[](https://i.stack.imgur.com/ahngg.jpg)
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**It might help some, but your pilots are not *gods*.**
When all other things are equal, or close to it, any little advantage can tilt the balance. I would think that the mind-machine interface makes a greater difference than the liquid breathing. A lot depends on your assumptions for engine technology -- you would need engines to make hundreds of m/s2 acceleration worthwhile and not just a way to expend all the fuel/reaction mass in an eyeblink.
Compare those mods with the recon commandos, who can hold their breath for hours and not excrete anything for days, and who *also* got those speed boosters, or with the operations officers who practically fuse their minds with their battle management mainframes.
As to advantages and disadvantages out of the cockpit, again concentrate on the mind-machine interfaces.
* Do they get machines to interface with out of the cockpit, or is the interface bulky enough that only the fighters have it? Would they have an interfaced computer in their hip pocket? They'd be killers at billiards, for starters, and nobody could pad their bar tabs.
* Will there be withdrawal syndromes without such a computer?
* Does their speed cause problems with interactions? To they get irritable and impartient with 'basic' humans?
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Sticking to the negatives, long term or performance enhancing total liquid ventilation hasn't been done to know what the real effects may be. TLV is better than conventional mechanical ventilation (i.e. iron lungs and modern ventilators used in covid 19 situations) in animal studies, and partial may help babies more than adults, and may actually be worse than CMV for adults, but both TLV and PLV are experimental and not common. Other uses of TLV is a better method of cooling a person after a heart attack to minimize damage. TLV is used when the surface tension of the lung's liquid to air barrier has become abnormal. Gas exchange must be monitored.
If we extrapolate this, then yes, there is probably drawbacks from long term use. By changing the liquid to air barrier ratio, the lungs could become more accustomed to it. Basically causing the lungs to dry out in normal nitrogen oxygen gas situations. Dry lungs can lead to thick mucus, asthma, COPD, pulmonary sarcoidosis and fibrosis. On the easy scale that means just needing to limit the time away from the liquid environment, or needing an inhaler or rebreather occasionally. On the hard end, your pilot needs an entire support system/backpack/tank or reverse scuba suit. It would help with the god-like/alien aspect of how they come off, but in reality, it's an extra weakness.
They can also be overly sensitive to temperature changes. The change in the lung's environment has sensitized it the overly controlled setup. Something as simple as too hot or too cold air can paralyze the pilot while it would just inconvenience non-pilots. It may require a suit or breathing aids like above.
And finally, performance based TLV means that your pilot is used to a richer oxygen. The first hours or days in the tank would give your pilot an oxygen doping sensation, but the first hours or days away from the tank would cause the pilot to experience what anyone who travels around the world might. Altitude sickness. Lower oxygen saturation and or pressure will lead to your pilot being weak, short of breathe. Climbing stairs may exhaust them. They will have a brain fog like a few shots into a good night out. Metabolism and temperature sensitivity happen too. Dehydration is common co-effect of altitude sickness, so the lung issue above can also worsen. It takes time to acclimate. So constant switching would take it's toll.
Whether you present compensating for this in a non-liquid environment as a disadvantage or not is up to you. Can someone be considered god-like if they need a suit to operate like that? It could be a hidden weakness. Only the enemy knows that the pilot needs a rebreather in public, while the public only sees a fancy mask.
[Answer]
Interesting question. Let's talk about response times. Electrical signals can propagate at close (99%) the speed of light. Let's just call that an even 300,000 meters / second. It is that fast because as soon as you give a power source a path to ground, electrons are carried by current through the conductor (wire), which is at a constant conductivity.
Nerve impulses, which are essentially also low-voltage DC signals propagate slower. The reason for this is that when the signal reaches the next nerve cell in line, there is a lag time during which the cell's internal chemistry changes from conductive to non-conductive (in an inhibitatory signal) or from non-conductive to conductive (excitatory signal). The signal propagates from cell to cell until it reaches its destination, at a speed of up to 120 meters / second. This is approximately 0.04% as fast as a signal propagating across a wire conductor.
So that said, let's assume you can somehow double the speed of the nerve impulse to 240 meters / second. I don't know how, maybe a different neurotransmitter than potassium is being utilized. You are now at 0.08% as fast as the speed of a signal on a wire. Moral of the story, a computerized autopilot is *ALWAYS* going to send its signals faster than a human one. That isn't necessarily a bad thing. A human outside the cockpit in the decision making loop (say at a remote control console on the Carrier or a planet surface) will be far more limited from the lag time in radio communications. Especially if EM radiation or jamming scrambles those communications. The speed at which a pilot makes a decision isn't really the issue. The issue in manned vs unmanned flight comes down to this:
The unmanned flight won't make any widows if it doesn't come home. It can go on one-way missions, including Kamikaze missions. A manned one can too of course but then you lose a skilled pilot. No one is going to mourn the loss of an autopilot.
So by all means, pump up your pilots with modifications. Ultimately it will just make them more valuable and make commanders less willing to risk them on manned missions. Which is kind of the direction we are already going.
[Answer]
### Humans piloting spacecraft are always going to be inferior to AI.
Humans need life support, protective structures and a whole bunch of other garbage to make them even *usable* in deep space combat. Not to mention humans tend to think in 2D planes in terms of warfare.
AI on the otherhand does not need life support or any other garbage, and the technology for such machines, isn't even really that scifi. You can also miniaturize AI space craft to be incredibly small given the lack of life support. And given both the 3D nature of space, the lack of obstacles, and zero air resistance Why have a space fighter jet when you can have a engine attached to a laser/missile launcher with an AI controlling it and an excellent IR camera (with out atmospheric distorition, and easy methods of heat dissipation that don't involve radiating heat you are very easy to see with IR cameras in space) making it hard to hit easy to mass produce and easy to manage and automate fights with. Plus you don't have to worry about losing one critical part of the ship and lose the pilot, you can even create redundant AI's. Plus computers have much better reaction times.
In the future it might get to the point you never need a human in the battlefield at all, even to give commands, and abstract battles to the strategic level "Im going to send AI starfighters here to defend this location (the AI's can handle interbattle logistics) and AI's over here to do another thing"
So why am I mentioning this if you are adamant on human pilots? Because you tagged this as science based.
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> Drones were the primary fighter previously until some advances were made with MMI and biological enhancements. Also, multiple drone hacks were done so the public perception on them dwindled.
>
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Humans are going to be in relatively short supply compared to manufacturing drones, even ignoring the fact that the growth rate of humanity is projected to flatline on earth alone. Enhancing MMI isn't going to solve the rest of the logistical problems with carrying human sized vertebrates in space either, let alone humans themselves.
And if you want to apply reactions of humans like those today to those of tomorrow, they are going to be even less receptive of sending actual humans into space than drones. The outcry of drone striking is significantly less than the outcry against the loss of humans themselves, or even humans yet to even exist!
Plus just because humans are involved doesn't mean they aren't subject to being effected by electronic warfare. You can hack communications very easily giving humans the wrong orders. Any electronics in the space ship are susceptible to hacking as well, if the corresponding drone parts were, and all they need to do is take out lifesupport.
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> Pilots are very rare and high value, ships will only launch them as a last resort. Each ship usually has a fee gunships (heavy and light) and then a couple fighters. The fighters are more akin to a lighter gunships with automated turrets and AI assistance than a traditional jet fighter.
>
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Why are they launching them like this at all? With AI's you can *just* have a fleet, with no mothership, no "last resort" needed, every scrap of metal out there can fight. They can even easily be used as fodder, no need for "rare high value ships". You don't want to lose your rare stuff.
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> Various treaties have limited the use of drones (and other one-use large vehicles) as well as attempted to add responsibility to the fleets to limit debris in space (a large occupation sector in the series relies on scrappers cleaning up space debris).
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Space is huge, like *really huge*. You would have to have trillions of vehicles and constant traffic in a sector with constant fighting for there to even be a noticeable increase in space debree for it to be worth even thinking about cleaning. For a planet it is different, but drones, given, that unlike your assumptions, would be *small* not *large* would even be less of a problem, less than your non drone space jets.
Also, treaty limiting use of drones? Why then? Why haven't we *already* had such a treaty? Drones, unlike WMDs, do not present an existential threat to humanities survival, but rather provide a similar threat to remote missiles, or really any remote kill tech. Drones are just more precise. They are coveted by modern militaries in part due to their public appeal (in the sense that less human deaths on their side take place) and ability to perform warfare with out being there.
No military in their right mind would obey the banned use of drones, even in the modern era, much less the space era. The military would have to simply not exist as we know it, as well as all the knowledge of weapons *we currently have*.
Your scenario could kind of work for a civilization not used to war with advanced HMI and human modification capabilities, which are used for warfare as a last resort because other tech is not availible, it does not work as an extension of current civilization as we know it.
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I’ve recently been playing a alien game with various alien species. After playing for a bit, I wondered whether or not a 6-inch tall intelligent race could exist.
I can already see some major disadvantages, one being the complications of requiring the necessary energy to power the body, especially the brain, but I can also see some major advantages, such as having the ability to mostly stay out of sight from far larger predators. I’d imagine that if said species were intelligent enough to make small cities and relieve themselves of their natural predators, then it would only be a matter of time for them to colonize their entire planet, and probably even avoid risks of overpopulation and excess mineral usage due to their small stature.
Now to the question:
**Could a six inch tall intelligent species ever feasibly evolve, and if so how?**
[Answer]
**Six inches is doable, but probably at the very limits of what you can get away with given what we know**
>
> The macaw has a brain the size of an unshelled walnut, while the
> macaque monkey has a brain about the size of a lemon. Nevertheless,
> the macaw has more neurons in its forebrain -- the portion of the
> brain associated with intelligent behavior -- than the macaque.
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>
> ~ <https://www.sciencedaily.com/releases/2016/06/160613153411.htm>
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Mammals do not have the most optimized brains on Earth. If you start with a brain structure like that of a Macaw and scale it up relative to that of primates, you should be able to arrive at a brain of roughly human intelligence in a package about the size of a ping-pong ball.
Smaller animals are also more structurally sound thanks to the square-cube rule; so, you can get away with a proportionally larger head. The Tarsier takes advantage of this fact to fit proportionally massive eyes in its head; so, a 6" creature of similar proportions could take the same approach to holstering an unexpectedly large brain resulting in an alien that looks... well just like an alien.
[](https://i.stack.imgur.com/AJmpe.png) [](https://i.stack.imgur.com/0U7zp.png)
As for how such a creature would evolve, I would probably go with a flightless bird... or rather, an alien that was capable of flight at some point in its evolutionary history. Earth birds evolved these super efficient brains because they had to be able to minimize weight for flight, and we know from Earth that flightless birds have retained this efficiency. You should probably start with an omnivorous flying creature similar to a pigeon or a crow. Larger stronger birds of prey force them to form societies, and build complex fortified "nests". Since a single large nest is more defensible than lots of small ones, this introduces a massive pressure for complex social behaviors and the formation of "tribes". The development of tribes leads to food scarcity which leads them to need to be able to hunt more kinds of prey to meet their nutritional needs. This puts a strong social pressure for tool usage and the development of weapons. Over this whole span of time, importance of flight becomes far less than the importance of the defensible nest; so, their heads get bigger, and their wings start to turn into hands. A few million years latter you have bird like creatures discovering fire, crafting spears and bows, farming, organizing into warbands and doing all the things humans did to set us on our own path.
**As a side note, much smaller might even be possible when you look at insects**
Insects seem to have even higher density thought than birds when you consider that they can make plans, communicate, stalk prey, build complex structures, and perform basic military tactics all with brains the size of pinheads. But their actions are all instinct, and they can not learn to do things beyond cause and effect; so, it's hard to say how well thier brains actually scale up to being capable of General Intelligence.
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It is certainly possible for intelligent beings to be only six inches tall. Of course that depends on how many feet long they are.
It wasn't specified that the aliens have humanoid shape, so I imagine that they look like centipedes:
<https://en.wikipedia.org/wiki/Centipede#/media/File:Lithobius_forficatus.jpg>[1](https://en.wikipedia.org/wiki/Centipede#/media/File:Lithobius_forficatus.jpg)
or millipedes:
<https://en.wikipedia.org/wiki/Millipede#/media/File:Millipede_collage.jpg>[2](https://en.wikipedia.org/wiki/Millipede#/media/File:Millipede_collage.jpg)
or catapillars:
<https://en.wikipedia.org/wiki/Caterpillar#/media/File:CH_Caterpillar.jpg>[3](https://en.wikipedia.org/wiki/Caterpillar#/media/File:CH_Caterpillar.jpg)
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> Arthropleura (Greek for jointed ribs) is a genus of extinct millipede arthropods that lived in what is now northeastern North America and Scotland around 345 to 295 million years ago, from the Viséan stage of the lower Carboniferous Period to the Asselian stage of the lower Permian Period.[2](https://en.wikipedia.org/wiki/Millipede#/media/File:Millipede_collage.jpg) The larger species of the genus are the largest known land invertebrates of all time, and would have had few, if any, predators.
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> Arthropleura ranged in length from only about 0.3 metres long to A. armata which was 2.5 metres long.[3](https://en.wikipedia.org/wiki/Caterpillar#/media/File:CH_Caterpillar.jpg) Arthropleura was able to grow larger than modern arthropods, partly because of the greater partial pressure of oxygen in Earth's atmosphere at that time and because of the lack of large terrestrial vertebrate predators.[4](https://en.wikipedia.org/wiki/Arthropleura)
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> The flattened body of Arthropleura is composed of approximately 30 jointed segments, each of which was covered by two side plates and one center plate. The ratio of pairs of legs to body segments was approximately 8:6, similar to some present-day millipedes.[5](https://en.wikipedia.org/wiki/Arthropleura#/media/File:Arthropleura.png)
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<https://en.wikipedia.org/wiki/Arthropleura>[4](https://en.wikipedia.org/wiki/Arthropleura)
<https://en.wikipedia.org/wiki/Arthropleura#/media/File:Arthropleura.png>[5](https://en.wikipedia.org/wiki/Arthropleura#/media/File:Arthropleura.png)
A maximum length of 2.5 meters is about 8.201 feet. So Arthropleura probably grew massive enough to support brains large enough for intelligence.
Arthropleura were limited in size by relying on passive diffusion of gas for oxygen and by having exoskeletons. A vertebrate with lungs that had the same body plan could grow much larger than Arthropleura. So intelligent beings six inches tall and several feet long and wide could evolve and exist on Earth.
And on a planet with high enough surface gravity, such a body form might possibly be the only form possible for a species with enough body mass to have a brain large enough for intelligence.
In Hal Clement's novel *Mission of Gravity* the natives of the planet Mesklin, which has a surface gravity varying between three and seven hundred times the surface gravity of Earth, are shaped like centipedes.
I note that there are seven snake species that sometimes reach weights of over 100 pounds (45.3 kilomgrams) and lengths of at least 15 feet 94.572 meters). Such snakes have sufficient body mass to support brains large enough for intelligence. So giant snakes with arms and hands could be large enough for intelligence and possibly not more than six inches high.
I note that a snake like being six inches in diameter and 100 feet long would have volume of 25 cubic feet, which is close to ten times the volume of an average human which is close to 2.5 cubic feet. A cylindrical being 10 feet long and 0.5 feet or six inches in diameter would have a volume as large as the average human and thus could support a brain as large as a human brain.
The marine bootlace worm *Lineaus longisseumus* is very thin, but sometimes grows very long.
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> Bootlace worms may grow very long but are usually only 5 to 10 millimetres (0.20 to 0.39 in) in width.
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> In 1864 a specimen washed ashore in the aftermath of a severe storm by St Andrews, Scotland, which was more than 55 m (180 ft) long,[6](https://historum.com/threads/aliens-will-more-likely-look-like-us.184076/page-4) longer than the longest known Lion's mane jellyfish, the animal which is often considered to be the longest in the world. However, records of extreme length should be taken with caution, because the bodies of nemerteans are flexible and can easily stretch to much more than their usual length.
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<https://en.wikipedia.org/wiki/Lineus_longissimus>[7](https://en.wikipedia.org/wiki/Lineus_longissimus)
A worm 10 millimeters in diameter would have a cross sectional area 78.53975 square millimeters. If it was 55 meters or 55,000 millimeters long it would have a volume of 4,319,686.2 cubic millimters, or 0.0043 cubic meters, which would be about 0.1525 cubic feet, a small percentage of the volume of a human.
If the aliens are six inch tall centaurs, they will have much more body mass than six inch tall humanoids, and thus be more likely to have brains large enough for intelligence.
Six inch tall humanoids would have about one eleventh or 0.090909 of the height, and thus about 0.00075 the volume, of average humans. That is one divided by 1,333.3333 of the volume and mass of an average human.
I suppose that the brains of six inch tall humanoids might be spread throughout their bodies and not concentrated solely in their heads, and thus could be significantly larger proportional to their stature. After all, a human brain functions well and has dimensions equal to the dimensions of a six inch tall body.
On Earth the vast majority of mammals have bodies much smaller than humans. But there are hundreds of mammal species about as large as humans or larger, and thus large enough to have brains about human size or large. A minority of those large mammal species, roughly a hundred, do have brains about human size or longer. And many of those species do exhibit intelligent behavior similar in many respects to that of humans, so that the popular idea that there is only one species of intelligent beings or people on Earth is not necessarily correct. There might possibly be between one and a hundred other species of mammals on Earth that should be classified as intelligent beings.
Animals that are not mammals and whose brains are organized differently than mammal brains, might possibly need larger brains ins some cases to have human intelligence, and smaller brains in other cases to have human intelligence, depending on how well their brain organizations optimize intelligence per brain mass. Thus it is even more uncertain with non mammal species what the minimum brain size for intelligence is.
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> Some species of birds show surprisingly high intelligence for their sizes.
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> The corvids (ravens, crows, jays, magpies, etc.) and psittacines (parrots, macaws, and cockatoos) are often considered the most intelligent birds, and among the most intelligent animals in general; pigeons, finches, domestic fowl, and birds of prey have also been common subjects of intelligence studies.
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> This is very interesting, since the entire bodies of such relatively normal sized birds should not weigh much more than the brains of humans and other higher mammals. Thus "bird brains" might be organized for having exceptionally large intelligence for their sizes. Since birds are descended from dinosaurs, it is possible that some undiscovered species of small dinosaurs evolved human level intelligence sometime before the extinction of he dinosaurs 65 million years ago.
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See my post number 32 here:
<https://historum.com/threads/aliens-will-more-likely-look-like-us.184076/page-4>[6](https://historum.com/threads/aliens-will-more-likely-look-like-us.184076/page-4)
[Answer]
A sideways take would be to say the evolution is directed and not natural. In the book "[The Age of Em](https://www.amazon.ca/Age-Em-Work-Robots-Earth/dp/0198754620)", the author postulates that human consciousness can be emulated on a silicon substrate-a computer brain.
Since the electronic impulses in a computer travel faster than the electrochemical impulses in the brain by a factor of 1,000,000 , the emulated human can think far faster than the origonal "meat" human by up to that ratio. The ratio might not be that extreme for signal processing or other engineering reasons, but the author calculated that a "kilo" Em (i.e. running at a speed 1000X faster than the brain) would actually be comfortable and productive in a body scaled accordingly - only a millimetre tall!
"Physics:
Scales
SpeedsBodiesLilliputMeetingsEntropyMiserly
Minds
The cost to run an em is proportional to speed probably within at least a factor of one million above and below human speed. Ems can afford to save archive copies at least every 5 subjective minutes. **For a faster em, a natural-to-control physical body is proportionally smaller, e.g. a kilo-em has a millimeter tall body**, to which gravity seems weaker and winds seem stronger. Ems can meet well in virtual reality when signal delays are less than reaction times; kilo-ems need to be within 15 kilometers. Ems who use fractal adiabatically reversible hardware use much less energy than do human brains for the same speed. They can temporarily vary their speed, and spend about as much renting their hardware as on energy and cooling to run it. Interacting reversible ems coordinate to reverse their interaction messages later within a reversing period".
<https://ageofem.com/>
So outside of natural evolution, technology and directed evolution could make it possible to place emulations in much smaller bodies, robotic or some sort of enhanced cybernetic organism as seems desirable. A six inch tall cyborg does not seem to be beyond the capabilities of any species capable of brain or mind emulation. All it would need is a reasonably acute sensory system to handle the inputs and sufficiently advanced dexterous manipulators (hands, tentacles, beaks and claws etc.) in order to translate thought into action. A body with the means of communication is also necessary.
While various species of octopii and even crows have demonstrated various levels of intelligence, including the ability to communicate, sense their environment, solve problems and manipulate objects here on Earth, they do seem to be somewhat larger than the six inch limit imposed by the OP. While there is reason to suspect these creatures may have the potential to evolve higher intelligence and sapience, it is not clear if changing body size or mass would support this. An engineered being can be built or grown to any arbitrary size, and can have whatever sensory and manipulative organs are desired added during the design and build stage.
So while natural evolution might not be able to come up with a 6" tall intelligent being, but an intelligent being should be able to develop technologies which can create the desired form factor, and many other different ones as well.
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[Question]
[
[Repost to condense question down] For a science fiction world of mine I am considering using a type of microscopic organism that is able to generate energy as it goes through its lifecycle, a life cycle so fast that a group of them would be in a constant state of reproducing, decaying, and producing fuel or energy.
So, could a microorganism (bacteria or otherwise) theoretically have a life cycle so fast that it can grow at a rate it can be “burned”? (This is ignoring possible overpopulation and ecological takeover.)
I would provide more details but nothing is really set in stone for my plans with it yet. I just want to try and get a good idea of if something like this is possible.
[Please note I want to stay as close to scientifically plausible as I can, but some creativity is welcome]
Edit: Thank you to everyone who answered, all of the ideas given were great! In the end I chose the one that fit the best into the story! Thank you all again for helping out and for sharing some really interesting ideas!
[Answer]
How about instead of burning the organism completely, only its metabolic byproducts can be burned with it?
I have long since thought about alternate biochemistry, but some genius actually [created life-like bubbles in the laboratory made of inorganic materials.](https://futurism.com/scientists-create-life-like-cells-out-of-metal) Those scientists put *oxometallate* drops on an *oil-based substrate*, and watched as self-contained environments reproduce into as well as integrate smaller droplets.
Two of such alternatives are silicon and sulfur.
One of the things I read about *silicon* is that if it's ever used in place of carbon, the silicon analogues of organic compounds will be a lot heavier and more heat-resistant. Moreover, silicon life is problematic because silicon dioxide, which is the equivalent of carbon dioxide, is solid instead of gas at room temperature. You don't want to form silica glass inside your body every time you "exhale".
This leads to the incorporation of *sulfur* which is a common ingredient in gunpowder, which is then, well, flammable enough.
As for *endosymbiont theory*, it's a famous theory stating that mitochondria and chloroplasts were once separate cells of their own, until a much larger cell with a much more sophisticated control system lorded over them. The ancient truce resulted in partial indigestion which allowed small cells, when swallowed whole, to be housed inside larger cells while providing resources and without being completely dissolved in enzymes.
Combining these concepts altogether, you get something a little bit like this.
### Pyrokaryotes
[](https://i.stack.imgur.com/He9kx.png)
A simple illustration of a pyrokaryote (totally made up) that is the result of an inorganic droplet being able to evolve further and gaining the ability to ignite its silicon-dioxide crystalline outer body with every sulfur-silicon-oxometallate metabolic cycle.
It's kind of like a cross between an inorganic eukaryote and a diatom, except that:
* The extracellular matrix will constantly grow and crystallized further if it didn't burn.
* The membrane contains oxometallates instead of carbon-based fats, becoming able to absorb much more heat.
* The cytoplasm which is the hot soup of materials inside the pyrokaryote is oil-based, containing more volatile polar atoms that can cause self-ignition when purged out of the oxometallate membrane.
So there, a semi-organic microorganism that should constantly burn itself if it doesn't want to crystallize towards starvation and fossilize afterwards. Imagine a colony of these, like a chromatic and oily crystal-goo spreading fire as it eats the petri dish.
Aside from the fact that all these are based on speculation, I hope pyrokaryotes satisfied your craving for fire.
[Answer]
No, I am afraid this is not possible.
Any organism will, directly or indirectly, take energy from the Sun. Thus the first limitation we have is that it cannot use more than the energy flux, which is roughly around 1000 $W/m^2$ or lower.
Even if that could be possible, there is the second limitation: mass transport. To grow the organism would need a constant supply of material and removal of waste. That would require a carefully engineered environment to ensure appropriate flow, and it is not going to happen in nature.
Last but not least, if you are able to overcome those two issues, you won't be able to output more than the input you are getting, which are those famous 1000 $W/m^2$. You can get more only if you store the produced mass somewhere, and use it all together (this is what we do with fossil fuel).
[Answer]
**Sure.**
Algae are technically protists. They grow very fast, converting CO2 into biomass. Kelp can be burned as fuel.
<https://www.theguardian.com/theguardian/2012/nov/14/seaweed-energy-fuel-alternative-1979>
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> Kelp, a prolific grower, increases by about 18 inches a day and can
> grow to more than 200 feet in only six months. Long used as a source
> of a valuable compound called alginate (used in ice-cream, soup and
> strawberry jam to provide the stiffness) kelp has only recently been
> considered as an energy source.
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> The "Ocean Farm Project," as the US Navy calls it, is being run in
> conjunction with Caltech and the American Gas Association. It involves
> growing the giant California kelp on nets covering a sea area of seven
> acres. US Navy scuba divers stick small seedlings to the polypropylene
> nets and the fully grown kelp is harvested by the divers six months
> later.
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> The harvested kelp then goes into an airless " digester " where
> microbes break it down into methane gas which is then burned in a
> generator to produce electricity. Eventually, it is planned to
> increase the size of the Ocean Farm Project to an area of 470 square
> miles. It has been calculated that the resulting harvest could supply
> the entire natural gas needs of the United States...
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Given requisite nutrients, photosynthetic organisms can fix CO2 into reduced carbon very, very fast. Seaweeds are fast but on land canary grass and bamboo can give them a run for their money. I suspect unicellular organisms that do not need to worry about support structures might be faster yet though maybe more difficult to harvest.
There is no reason you could not farm a photosynthetic organism with the intent of later burning it for fuel.
[Answer]
Certainly.
**First, lets consider how long a fire lasts.**
A torch lasts [an hour to a few hours](https://www.reddit.com/r/AskHistorians/comments/1e7adh/weve_all_seen_the_unrealistic_torches_used_in/), depending on the material made. They commonly used pitch or some similar substance that burns slowly.
[](https://i.stack.imgur.com/awuow.jpg)
**Second lets consider how fast [a slow burning creature might grow.](https://www.techiecamper.com/lifestyle/how-much-firewood/)**
Bamboo gives an answer- about an inch an hour. Three or four inches is about the size of the head of a torch.
Some hyper efficient bacteria may well be able to grow at a similar rate, producing enough of some pitch like substance that burns slowly to sustain a constant fire. It might use this as a method of breeding.
The bacteria may be a partial [hyperthermophile](https://en.wikipedia.org/wiki/Thermophile) which needs high temperatures of above 80 C to reproduce sexually. As such, it could constantly produce an oil which burns slowly as it replicates sexually, sending tough bacteria spores out to grow elsewhere when it ignites.
Imagine a black goo, slowly expanding. It draws nutrients from the earth, growing taller, forming towers towards the sky. Then, when it reaches a height of sufficient highness, it self ignites, explosive chemical reactions causing the top to ignite. It slowly burns, constantly producing oils, spreading spores far and wide with the powerful flames, the spores using the high temperatures to do rapid sexual reproduction that they cannot do at lower temperatures.
[](https://i.stack.imgur.com/c1SBc.jpg)
Humans nearby could use such a flame to warm themselves, or cook objects. Certainly, there would be swarms of bacteria around them, but these bacteria only grow at any effective rate on the very rich soils of the land.
[Answer]
# Yes but.
Since you have the "science-based" tag, we cannot ignore the laws of thermodynamics. So, your bacteria need an energy source (call it F). They use up this energy, and the available matter, to reproduce and either reform themselves into, or produce as metabolic byproduct, a substance or set of substances containing energy S.
The difference (F-S) has to be positive and is used by the bacteria and re-radiated as low value thermal energy. What part of S is accumulated inside the bacteria and what is oozed out from the bacterial mat is irrelevant.
So far, we only need that `S < F`. For the bacteria to be useful instead of a competitor in the use of energy, we need for F to be difficult to use, while S can be easily used for fuel.
For example: we have a plant that captures solar energy, as Earth plants do, and build a lignine analogue which is incombustible. It has a high energy yield, but the energy is locked inside and can only be freed by a complicated, endothermic reaction (after which you get an even too energetic exothermic reaction). So, the "wood" of this tree is useless as a fuel. The bacteria, though, can digest and use the high-energy bonds in the neolignine and convert it to fuel.
You can see something vaguely similar with the water-aluminum-gallium reaction. Metallic aluminum has a high energy content, but you cannot get at it and cannot "burn" it (actually you *can* - that's how you get thermites and thermates. But it's neither easy nor convenient, unless you want a fire hot enough to boil iron). Put aluminum in water, nothing happens because the aluminum is auto-passivating. But mix it with gallium metal, and the resulting amalgam no longer self-passivates: water oxidizes the aluminum developing hydrogen, and if you do it properly, at rates high enough to sustain flame. The bacteria could be your "gallium" to the wood's "aluminum".
The drawback, as you see, is that the bacteria won't produce fuel *per se* - they will only be able to *transform* something into fuel. So you need to carry along enough of that something.
[Answer]
The answer is complicated, and highly depend on the interpretation of your question.
If we look at a cell at a fundamental level, everything that happens is chemistry, fire is also equally a chemical reaction. So fundamentally the question could be phrased as "Is it possible for the chemical reaction in a cell to produce a substance faster, than the chemical reaction of fire would destroy said substance. The answer to that question is without a doubt no...
The caveat with the above answer is that is only for an uncontrolled environment. If the environment is controlled in a way so oxygen is limited for the fire, it would burn "slower" (the chemical reaction happens at the same speed of course, but less substance will be converted at a time leading to longer burn time)
A theoretical construct could be made, where a ball on genetically engineered bacteria (they replicate faster) with a fine mesh of artificial blood vessels running through out it to supply it with nutrients, liquids and what else it might need. Fire would only be burning at the surface, but replication of the bacteria happens throughout the while ball. Since volume increases faster than surface area when radius is increased, there should be a certain size where replication of the bacteria can outproduce the loss to fire.
This answer is based on your indication that your 'Science-based' tag is less of a "I want hard facts" and more of a "i'd prefer if it follows hard science, to the extend possible".
[Answer]
The question is very generic. Meaning: if you don't mention which amount of energy you need to produce from fire, the answer is "yes". Basically burning wood is kind of having a form of life (not microorganism, but I'm just writing an example) which takes energy from the sun and then creates a biomass we can burn.
<https://en.wikipedia.org/wiki/Biomass>
So you are asking if there is any microorganism we can dry and burn. Well, if you don't mind of the quantity of energy, almost all carbon-based organisms will fit, once dry.
Second, you didn't specified the source of energy , meaning where the microorganisms are taking energy to grow. I am assuming the sun, but we can have also environment: there are bacteria producing methane which are degrading dead plants , or manure, and they are very common in swamps. So you have already plenty of microorganism who are able to produce methane (ok, I admit this is not "burning", but they produce something which burns).
To have something similar which burns, you may try some mushrooms. They burn quite good once dry, but you need some external source of material to feed them, since they are Heterotroph.
<https://en.wikipedia.org/wiki/Heterotroph>
and most of times Saprobiontic
<https://en.wikipedia.org/wiki/Saprobiontic>
And yes, they grow pretty fast, although we could discuss about "micro".
So the very problem of the "microorganisms" you mention is: where they take energy to grow from, and how much energy you need from burning them?
If the answer is that they decompose some carcass/dead tree or similar, yes, there are many of them, although it could be questioned if burning the original biomass could give better result.
Also bacteria decomposing manure are rowing pretty fast and often produce methane: there are facilities already in use for doing that, in many farms.
<https://en.wikipedia.org/wiki/Biogas>
Of course then you need lot of manure to feed the microorganisms , which leads again "which source of energy they use to grow": there is no free energy.
[Answer]
## Yes, but it will only make sense if the people are sufficiently low-tech
It is not possible for an organism to produce more energy than it consumes in the first place. If this organism grows through photosynthesis, it will always be more efficient to cut out the middleman and get the energy directly through solar panels.
Unless, of course, the setting is one where the people did not figure out how to collect solar energy. The existence of a cheap, renewable energy source may have something to do with this.
As for the organism itself, there are limits to how fast an organism can grow. However, it is possible that the organism burns *very slowly*, in which case it may be able to burn continuously.
The problem with this is that the energy released by such a slow combustion process will be very, very small. You're not going to get a lot of heat from this fire - remember, all that is happening is that you are releasing the energy the organism acquired from the sun. It is possible, though, that this organism can grow quickly during the day and provide a little bit of heat at night, releasing the energy it used to grow during the day.
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[Question]
[
In a future world that is obsessed by not repeating the so-called errors of their fathers, there is a backwards Olympics, or Scipmylo.
All the usual disciplines are featured in reverse where it is possible to do so.
**Examples**
Catching the discus.
Dodging the javelin.
Low jump.
The easiest to measure and judge are the running sports. Contestants simply run backwards.
**Question**
Anatomically speaking, how well will the running-backwards-records rival our current forward running ones? Is there a fundamental reason why, with enough practise they shouldn't be just as fast?
[Answer]
Backwards running will almost certainly never be as fast or efficient as regular running. [A study back in 2011](https://www.ncbi.nlm.nih.gov/pubmed/20719774) showed that it should takes about [30% more energy](https://well.blogs.nytimes.com/2012/12/06/running-in-reverse/) to run backwards at a given speed. Why? It depends on how foot muscles respond during both types of strides. In normal running, landing on the balls of your feet and pushing off on the toes allows muscles to coil up and then release elastic energy, propelling you forward. When running in reverse, the muscles are unable to stretch and release in the same way.
Current world records in the backwards 5k and marathon are substantially slower than the corresponding forwards records: [19:31](https://well.blogs.nytimes.com/2012/12/06/running-in-reverse/) and [3:38:27](https://www.insidescience.org/news/running-backward-toward-marathon-world-record) compared to [12:37](https://en.wikipedia.org/wiki/5000_metres_world_record_progression) and [2:01:39](https://en.wikipedia.org/wiki/Marathon_world_record_progression), respectively. I assume that if the strongest distance runners trained for backwards running, they could improve on those backwards times, but they'd still be at a disadvantage, from an energy perspective.
## Addendum
I'm a college runner, so I figured I'd try to experiment a bit at practice today to better understand the mechanics of what's going on. We already do some backwards jogging as a warm-up drill, so I figured I'd just modify that. I ended up doing three sets of sprints on a standard outdoor track, with each set consisting of one forwards 40-meter sprint at a controlled pace and one backwards sprint of the same distance, as fast as I could go. I made some observations:
* I ended up taking about 1.75-2 times as many steps while traveling backwards, on average; I was forced to shorten my stride because my motion felt limited.
* While running backwards, I was forced up onto my toes more; if I tried to use the balls of my feet at all, I ran the risk of falling.
* I definitely felt much less spring in my step when I pushed off running backwards. It was a little bit awkward, biomechanically.
* I was able to run straight without looking over my shoulder, by keeping my head fixed on a target I was running away from. However, I was on a straightaway, and inside a lane. On a course with turns, I would be hard-pressed to stay close to the inside, like I would normally do.
Some of these could be overcome through training, especially at a young age, but I'm pretty certain that the lack of a spring in my step could be problematic. It definitely got me less bang for my buck.
[Answer]
One problem for your sportsmen and women is that human vision is forward facing.
This means that it would be very difficult for them to make sure that they are running in the correct lane going backwards, for longer races judge the curve of the track etc.
Although with training it might be possible to mitigate against this to some extent, I doubt they could ever be as fast as somone running in the same direction they can see.
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[Question]
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**How realistic is the trope that wounds received in a virtual reality (VR) transfer to our own?**
Examples: In the Matrix (movie) and Neuromancer (novel), cuts, scrapes, and bruises seemingly jump from immaterial to the material world.
Does this vary by VR type? Current VR technology doesn’t seem to transfer medical conditions, but does this change somehow?
Is this purely a mind–over–matter phenomena where a body is “tricked” into wounding itself?
In what sense could VR influence biological processes?
[Answer]
The idea that you can believe a simulated cut is real hard enough for it to magically appear on your body a la Matrix is pure bunk. But..... You could end up with real psychological trauma from simulated events. The pain itself could be simulated realistically enough that say, a guy in a war scenario with zero saftey interlocks could step on a landmine and expierience a double amputation with shrapnel embedding itself in his abdominal cavity rendered in full spectrum sensory feedback (through some sort of hand wavey nueral interface) and develop some form of Post Traumatic reaction to the expierience.
Also in the Hyperion Cantos novels theres a scene where the protagonist walks through a house where the occupants are all emaciated and plugged in to a direct neural uplink VR set. They had elected to commit suicide by shutting the saftey features off so that the system would not automatically disconnect when sleep, food, water, or other necessities were needed. Its not too far fetched from current reality, cyber-gaming cafes in asia have had customers die in thier chairs from exhaustion after multi-day marathon gaming sessions.
[Answer]
Bruises and scrapes are Hollywood magic. But there can be lasting effects.
Basically, you have to define what the VR does to actually cause the virtual reality. Typically this is some neural stimulus (such as via the jack in the back of the head in The Matrix). Thus, VR is limited to what those stimuli are permitted to do. Since you cannot consciously or subconsciously open up a wound with your neurons, VR would not be able to do these things.
However, there are a *lot* of systems that are bound to neurons in meaningful ways. You could cause someone's muscles to tighten up so violently that they break their own teeth. This is what happens with tetanus, and with some nerve agents. The eventual cause of death in these cases is that the diaphragm fatigues, and can no longer draw air in. Or, your VR might be able to get access to the ganglia which manage the act of breathing itself. Still that part of the brain, and it will kill you.
There are many more systems which can't be directly affected via nerves, but which are affected by them. The heart is designed to beat without any input from the brain at all (thank goodness!). However, it does receive input from the brain in both electrical and chemical messages, indicating to the heart what sort of output is required. The wrong set of chemicals and electrical stimulus could send the heart into a fatal arrhythmia, or drive blood pressure so high that you stroke out.
So in all, we should really be careful as to what electrodes we screw into our body. Our body is a complicated machine, and it wasn't designed to have electrodes screwed into it. But there are limits to what VR can do.
[Answer]
Other people have already made some excellent points. I would like to add that psychological and physiological trauma are not as separate as many people think. So whilst a stab wound in VR may not physically result in a stab wound in real life, there is certainly a danger that the body may respond to injuries as if they were real. For example, if you cut your hand, your immune system will kick in, with an increase of white blood cells to target the infection. If there was no physical wound, but the in-game trauma was believable, one might hypothesise about a situation where the immune system might start attacking healthy tissue, or there may be swelling due to increased blood flow to the region. Even if not, psychological trauma is known to cause unmapped physical symptoms over time, including dissociation, muscle tremors and memory issues. In this sense, PTSD is a physiological disorder, and in-game traumas may cause similar blurring of boundaries which may -- for example, in the case of a convincing simulated head injury -- be complex and potentially severe.
[Answer]
Currently we don't have Matrix-style brain connectors, so the best virtual reality we can have includes these kinds of haptic actuators:
[](https://i.stack.imgur.com/26HCK.jpg) [](https://i.stack.imgur.com/NlcZL.jpg)
*Minswho CC-BY-SA-4 <https://en.wikipedia.org/wiki/File:NullSpace_VR_Mk_2.jpg>
Nabeel9172 CC-BY-SA-4 <https://commons.wikimedia.org/wiki/File:HAPTIKA_.jpg>*
[](https://i.stack.imgur.com/tJxdE.jpg)
The software is programmed to **give you feedback** when you touch objects.
* Grab a golf ball in your hand, and the servos on each finger (or even each phalange) will skillfully come in play to make you feel like you were actually holding a golf ball.
* Years ago I used such a device that has an arm firmly stuck in the ground. With this device you could push a virtual wall and really have the **virtual wall resist you**. Even though it is not a real wall but just a solid arm linked to your haptic exoskeleton.
* With 2020 technology, upgrade that device with ultra-powerful/ultra-fast actuators, and start a car racing game. If you miss the first turn and hit the virtual wall at 50 km/h, **the hardware can inflict you an injury similar to what you would have gotten if hitting a real wall** (only *similar* because you are not actually moving).
[Answer]
Like Cort Ammon says, it would depend on how your VR functions. The brain has mechanisms that prevent what's going on in your brain to affect your body in any way: that's what happens when you're dreaming. While dreaming, you can believe yourself running, falling, getting hurt, even dying. None of this affects your body in any way. So if you want your VR to be safe, that's doable. The only thing you'd have to consider is the effects of prolonged immobility on the body. (Not moving for over 2 hours would affect circulation and cause bedsores. That's why people roll over in their sleep.)
*Can* you make the VR transfer injuries to the body? Having access to the brain, you can transfer muscle contractions, which could cause damage to capillaries (causing bruising and pain), you can damage the muscle, you can even break bones. You can arrest breathing. (Though feinting would hopefully disconnect the VR, prompting starting breathing again?) You can send the heart into a fatal arrhythmia, but that would have to be very deliberate. I do not see how you can break skin, unless you cause a person to physically do it to himself (basically induced self-harm while sleepwalking). Again, however, all of this is harder to set up than a safe VR, so someone would have to deliberately want the kind of VR that can hurt you.
[Answer]
Consider another angle...
Assuming you have a VR that somehow can transfer REAL damage and pain to you (electric shocks would be my vote) I dont see *why* you would you want to play in it (outside of sex of course, which I'm sure will one day be a market; but I digress...).
Unless...
A) what if you've been forced against your will in gladiator style VR arena?
B) what if its a contest for big prize money?
C) what if an evil programmer traps you in the VR?
D) what if they're high tech adrenaline junkies?
My point is, create an interface with the player that transfers pain/damage to them (electrodes, whatever...). Your audience will accept it.
WHY your characters are submitting (or not) themselves to said lethal damage is more important.
[Answer]
Not exactly a virtual reality answer, but by using some hand waving around "entanglement" you might be able to justify a person being in two places at the same time. Like I said, it's not virtual reality, because the other location is actual reality. But the end result is you get into some sort of machine, don't leave it, and act in another location where you can be hurt.
You can even leave something in where because the person spends half their time in either location that there is a 50% chance that ending the connection will take them home. They might have to get to a "synchronization" device in order to ensure they return to the correct location. It would also allow people to bring things back. ;)
To elaborate how this might work: (Keep in mind, this is all handwavium-technobabble)
A participant would walk into a "sender chamber" where they would have their [quantum information](https://en.wikipedia.org/wiki/Quantum_information) sent to a "receiver chamber". This is similar to being teleported without destroying the original.
You might think that this is impossible because of the [no cloning theorum](https://en.wikipedia.org/wiki/No-cloning_theorem), however, as I'll show later: we aren't cloning particles so much as we are splitting their [quantum wave function](https://en.wikipedia.org/wiki/Wave_function) between two locations.
Any movements made by the original are simultaneously made by the copy as well. The original can see what the copy sees and vice versa, they're basically the same person in two places. This information is transferred faster than light, because [entanglement](https://en.wikipedia.org/wiki/Quantum_entanglement).
This is why the sender chamber has to be dark and silent, otherwise it would be confusing to see and hear things in two places. Imagine looking through a window while a projector is beaming an image onto it.
Momentum is a problem. Because if both copies share momentum then the copy will stop when the original hits the edges of the sender chamber. If momentum is not shared, then a knife going into the copy's skin won't move the original's skin out of the way.
Another problem is why participants can't just fly around by using a lift at the original side?
You could make momentum transmit one way, like the copy's momentum transmits to the original. But then how does the copy move from the original's movements?
So far my only solution is more handwavium, unless a commenter has something better.
The entire time, the participant's quantum wave function is split between two locations and they spend half their time in the chamber and half at the remote location.
This means that if you cut the power to the sender chamber and let the waves "collapse" there is a 50% chance that the participant will still be in the chamber instead of at the remote location.
The only way to guarantee that the participant returns to the chamber when the connection closes is to have the copy enter a "synchronization" device which manipulates the [certainty](https://en.wikipedia.org/wiki/Uncertainty_principle) of the copy's position so that the wave function doesn't collapse there.
Now that I think of it, you can solve the momentum problem I mentioned by changing the positional certainty of the original. In this case, the original stops being in the sender chamber and only the ghost of their wave function remains. The participant comes back when the devices swap the certainty back. This also means that there is a 100% chance the participant will stay at the remote location when the connection closes unless that swap happens.
You can also use these synchronization devices to bring things back from the remote location by using even more handwavium.
That's it. A huge pile of BS with holes all over the place. But it's more realistic than the idea that a body will harm itself because it "believes it was hurt".
Take this BS and do with it what you will. ;P
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[Question]
[
On my alternate earth, elves originally evolved their phenotype (pointed ears) in the forests of Africa and migrated to other forest biomes afterward. After settling down they developed the racial differences we see in our world today. Darker skin near the equator, monolids in the east, etc. But all elves regardless of placement still share their trademark pointed ears with only minor changes such as size and length. Why would they still share this one trait after hundreds of thousands of years of separation?
[Answer]
If the ears don't affect the elves ability to reproduce/survive then the frequency of that trait in the population is not likely to change.
So simply put, they would all have the ears because there's no drive to evolve differently shaped ears.
EDIT:
Due to random mutation non-pointed ears may occur in individuals within this elf population. Given enough time, it is likely that you will see a minor population of non-pointy eared elves arise. Examples of this would be left-handed people and people with red hair.
[Answer]
**Traits Evolution**
We know that a population lost traits depending in many factors wich afect their chances to reproduce and be more succesfull in their environment.
**Expensive traits**
Building a natural armor around your body, spikes and shells, is very expensive. If you remove the natural predators of this ecosystem, this traits wouldn't give a edge anymore and just become a burden for the creature.
Making it disappear faster.
**Easy Genetic adaptation**
There is traits that don't require huge amounts of time to be produced, since the DNA change that is demanded to get it isn't that complex. This is deduced since some cave fish begin to lose sight way faster than expected.
For your elves, could be that this trait isn't critical, expensive or that the time that's needed to be forfeit needs to be longer.
[Answer]
There's two ways to lose a phenotype: natural selection and a genetic bottle-neck.
But the first thing I have to do is question your assertion that these separate populations have "the same" ears. It *should* be obvious to you that you can't claim the same shape and ignore "size and length"!!
So, what you're saying is that except for the characteristics you *choose to ignore* they haven't changed? Need I say more?
The most obvious reason to maintain a phenotype is because it has a significant benefit. If you take a look at rat/squirrel ears and compare them to deer ears, there's a range of shapes (together with placement on the skull, as well as skull shape and no doubt inner ear geometry). What we can potentially conclude is that there is little variation because their shape significantly helps them survive (more specifically, helps them reproduce).
This seems a bit implausible. You need to forget about time spans measured in years, for phenotype changes, you measure time in generations. If an elf lives 1000 years, then 100,000 years is only 100 generations; only very very beneficial or deleterious mutations will significantly impact the populations at those short times.
It gets even worse with sentient and technological species: their control of the environment dominates their physical phenotype. We (humans) are still evolving, and yet it isn't apparent to us. Are you *sure* that these various populations of elves haven't evolved different ears? There's more to ears than "a pointy tip". Wikipedia lists 15 visual characteristics of the human ear here: <https://en.wikipedia.org/wiki/Auricle_(anatomy)#Structure>, it's pretty implausible that in the analogous elf ear, that separate populations have maintained their uniformity across all of these phenotypes.
It may be more of the difference between our ability to recognize human faces (quite exceptional) and our ability to recognize the difference between, say, two crows. It's not that they don't have "obvious" differences, it's just that we don't notice them.
[Answer]
Elves might be an insular culture, seeing crossbreeding with round-eared species as a bad thing. This might be reinforced by an increase in deformities and so forth from such crossbreeding, such that they are called "monsters".
In such a society, where the pointiness of one's ears is a sign of genetic purity and likelihood of avoiding genetic problems in one's children, you would expect a selection force towards pointiness.
The existence of some round-ears in each generation - whether just as a random mutation, a dalliance with a human, or rape by a human hunting party - is unavoidable. But if these are treated as second-class citizens, then what elven lady would want to mate with them and doom her children to such a life?
[Answer]
Hundreds of thousands of years is fairly short in evolutionary time. If there's no strong pressure, it would be shocking if the ear shape did change. You may as well ask why no humans have pointed ears. After all, those pointed elvish ears are quite sexy. Very few elves would choose to have children with an ugly, round-eared, human-looking elf. It's a marvel that humans can hear at all with those weirdly shaped things that are far to flat to the sides of their heads.
The pointed shape allows elves to hear extraordinarily well. The pointed part catches sound and directs it to the lower ear. The ear can swivel to pinpoint the direction of the sound and hear it better. In other words, it works quite well as is, so there's little or no evolutionary pressure to change it. Perhaps the average ears are even a little bit longer than they were a few thousand years ago.
[Answer]
**Why Not?**
Evolution is not a defined cut and dry process, especially if there is no need for a specie to evolve (IE it maintains apex dominance).
As a world building creator you choose how you want flexible processes such as this to progress.
It is perfectly reasonable to say in this case: "they just didnt".
[Answer]
Who says that the Fae, as a magical race, are subject to the same rules of genetics and evolution as humans? And even if they are, they have such long lifespans that "evolution" would not be evident to a people who have lives that only last a blink of the eye in comparison.
[Answer]
You could justify the evolutive permanence of pointy ears all around the world if there's a good reason for the ears to have such points. Since, in your story, elves branched from the place where the dearth of their species happened to all over the world, and all share the pointy ears, there must be a reason for these ears to had evolved in the first place, differentiating elves and another species from a common ancestor. Hence, my suggestion:
**Pointy ears as magic antennas:** Many animals have antennas as probes to something, be them electrical fields or chemical gradients. Elves are always associated to magic, so why not let the tips of their ears to be antennas for magic fields? With such sensory organs you could nicely explain several mythological traits of elves, like their tendency to gather in places where magic is strong and to perform some simple magics.
This could be a reason for the elf speciation, when the *Homo Elficus* branched from our evolutionary tree (I'm supposing humans and elves are somewhat related, due to the very similar phenotypes). In the moment an individual was born with a magic sensory organ it could, then, benefit from this magic field, let it be for hunting, for gathering or for extending its lifespan. With time, elves became more and more sensitive to magic, to the point the could now control this magic field to their desires.
Other magic-related traits could also had evolved, like growth or regenerative factors which require magic, hence explaining their lifespan as well.
[Answer]
If they hybridize with humans a lot, it's predictable they will get more variation. Are pointy ears a dominant trait, or recessive, or something else? It isn't at all obvious how it would go, but more interbreeding would eventually result in more variation.
So they do not interbreed much. If round-ears are dominant, then halfbreeds could be killed at birth. Or considered human and thrown out of elf society.
[Answer]
On the assumption that the OP's elves are a different species, and not just a human racial group, the primary reason why a trait without other obvious utility becomes universal, and even exaggerated, is sex.
So I propose that elves have pointy ears because pointy ears are attractive to other elves. They are an erogenous zone as well as a visual attractant, and part of the act of copulation involves partners caressing each-other's pointy ears.
Without this sort of feature, other elves would look at such an individual and think - or say - 'Ew! Non-pointy ears! What a turn-off!' If humans are present in this world, this might account for speciation between humans and elves... effectively humans just aren't attractive to elves, having non-pointy ears. Maybe elves lack some other feature that humans like too... maybe male elves are too effeminate, and female elves too boyish to be really attractive to humans, and the ears just don't do it for humans the way they do it for other elves.
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[Question]
[
I'm writing about a small desert planet (about the size of pluto) that humans can live on. Is this possible?
[Answer]
So as a simple answer no.
The diameter of Pluto is only 2,390 km across. Just for comparison, that's about 70% the diameter of the Moon. And it's a fraction of the size of the Earth; about 18% of the Earth's diameter. In terms of volume, Pluto only has 6.39 × 109 km3.
As far as planetary objects go, this is tiny. Pluto is considered a dwarf planet.
In order to sustain life, you need an Atmosphere. In order to have one of those, you need gravity. For us humans we need something along the lines of earth or mars size. We can go smaller, but there are issues with retaining an atmosphere and that is the main issue here.
to keep this shortish. You'll probably wanna make it roughly Earth sized, maybe a bit smaller lets say Mars sized. Now your next question should be how to sustain human life on a desert planet. Presumably if there are no questions already asking that exact thing.
Hope this helps!
[Answer]
## Sure is
**But** this world will have to have some very specific properties. Also, I shall assume that when you say the size of Pluto, you mean its radius. [Pluto](https://en.wikipedia.org/wiki/Pluto) has a radius of 1190 km, so that will be the figure I use for this world.
Firstly, this world is going to have to be rather dense, denser than any other planet in the solar system. It needs to be to have reasonable surface gravity to hold an atmosphere. Let's say it's almost entirely iron giving it an average density of 7.0 g/cm³. For comparison, Pluto has an average density of 1.8 g/cm³, Earth's is about 5.5 g/cm³. It has a giant iron core with a thin crust of silicates.
Plugging in those values to this [calculator](http://www.ericjamesstone.com/blog/home/gravity-calculator-for-astronomical-bodies-based-on-radius-and-density/) give a planet with a surface gravity of 2.33 m/s² which is about a third of Earth's. For some perspective, [Titan](https://en.wikipedia.org/wiki/Titan_(moon)) has less surface gravity than the moon (1.3 m/s²) and yet has an atmosphere thicker than Earth (1.45 atm).
This planet would be very dry, because most of the water, if any was ever there to begin with, would be consumed in [rust](https://en.wikipedia.org/wiki/Rust). A desert may be hot or cold, so place it wherever you like around its star.
This world may, however, have difficulty maintaining its atmosphere. Low gravity does mean it's easy for the host star to [strip](http://news.nationalgeographic.com/news/2009/05/090529-sun-stealing-atmosphere.html) atmosphere. Small planets' interiors cool quickly, so the [Geodynamno](https://en.wikipedia.org/wiki/Dynamo_theory) responsible for making a protective magnetic field dies quickly too. However, a planet rich in iron may have a residual field that provides protection. This stripping is also dependent on the distance from the star and how thick the atmosphere is in the beginning.
**Summary:** you could have a small desert world that humans could live on.
[Answer]
No is the right answer, but one of the great authors of the past got around this simple impossibility by feeding an oxygen rich gas giant to a small star...
In Larry Niven's [The Integral Trees](https://en.wikipedia.org/wiki/The_Integral_Trees), the atmosphere which the humans breath takes the form of a torus in tight orbit around the star, and the ground which the characters stand on is a tree growing along the center of that gas cloud. Like your miniature planet, the tree does not have enough mass to hold an atmosphere, but some of its surface has breathable air simply because it is located at the right place and time.
I seriously doubt that Niven's creation could stand up to astronomical time, but as long as your characters didn't have to evolve on that little world, you should be okay for the length of most stories. Just give them a wrecked spaceship and a castaway origin story, and move on with writing your story.
[Answer]
Downsizing planet to size of Pluto would not work.
Nevertheless, if you want a small desert planet that still is habitable:
* Make it quite dense, with big iron core (like Mercury has)
* It's hot - actually it faced serious atmospheric escape, thus it avoided fate of Venus
* only polar regions are habitable, the rest is hell, and during day the temperature can go on equator to some insane temperatures (like over 100C)
* better low axial tilt
For inspiration, a slimer version of:
<https://en.wikipedia.org/wiki/Future_of_Earth#Loss_of_oceans>
[Answer]
Possible? Yes, but with conditions:
- Decide what combination of planetary diameter and gravity you want, and then calculate the density of the planet - upper limit is the density of osmium, but you might be able to get away with a combination of lead and iron. Note that surface gravity on a small planet will be higher than a larger planet with the same mass (because the surface is closer to the center of mass).
- Decide what kind of atmosphere your aliens require for life. Easiest is to assume they require 21% oxygen like we do, but they might be able to breathe sulfur dioxide or something else.
- Decide what atmospheric pressure you need.
- Decide how much water you want the planet to have. If the core is lead, or the crust is mostly similar to Earth's, then you won't have the water all bound up in rust, as JDługosz suggested.
- How far from the parent star? The hotter and bluer the star, the farther it can be.
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[Question]
[
In my fantasy pre-industrial world pollen production and plant reproduction has been disabled by some sort of curse.
The curse has a limited geographical span, but the region affected is very large and without bordering countries that are easy to reach. There is navigation-based commerce with other far-away regions, but it's scarce and difficult.
What kind of food (vegetables, meat, animal products like honey...) would no longer be available or become very rare/expensive? In how much time?
Thank you very much for your help and sorry for my bad English.
[Answer]
The bad news: nearly all vegetation in the area is going to die out. When talking about what would *not* be available, it's actually easier to say what *would* still be available; we're talking about a complete ecological collapse scenario.
1. Bananas. Edible bananas come from the "female" flowers, which do not need to be pollinated to produce fruit. But, this still means that you can't produce banana *seeds*, so if you want new banana trees you'll have to take a cutting from an existing tree or import seeds from somewhere else.
2. Strawberry plants send out tendrils that can go into the ground and grow into new (genetically identical) plants. But this is largely useless for food; strawberry flowers need to be pollinated to produce *strawberries*. So you can have the plant, but not the fruit.
3. Aspen trees. The largest living organism on Earth is an aspen grove in Colorado named Pando. Pando continually sprouts new trees from the roots of existing trees. An individual tree tends to live about a hundred years, but the trees are continually sprouting new trees out of the roots to replace them.
4. Potatoes (and other root vegetables). Potato plants can sprout from potatoes. This will probably be the primary food source for your people.
Problems associated with all of these plants: they're all clones, so there's no genetic diversity. If some disease comes in that they're vulnerable to, they're *all* vulnerable to it (modern bananas currently have this problem). It's only a matter of time before some disease sweeps through, and it will be *very* difficult to repopulate after such a disaster (since no local seed production).
Other avenues:
1. Lakes are rivers are probably going to be mostly fine. Algae (despite being associated with the word "bloom") does not use pollen. Small creatures eat the algae, larger creatures eat those creatures.
2. Ranching is pretty much done for. Without grasses, it's going to be far cheaper to ship in beef and wool/mutton from somewhere else.
3. Chickens, on the other hand, will probably be the farm animal of choice. Continual food production (eggs) plus the occasional meat, and their diet is very adaptive. They can eat the scraps from the plants that humans won't eat (probably not potatoes; the plants are in the nightshade family), bugs, meat scraps, mice, etc..
4. Pigs might become a "status" animal. They take a *lot* of food before they're ready to eat, but the food they *do* eat can largely be scraps of what the humans are eating (or not even scraps).
5. Ship in the seeds for most vegetables. Things like lettuce, cabbage, celery, carrots not only don't require going to seed, but are better if harvested *before* going to seed. This means you'll have to ship in 100% of your seeds (instead of letting some of your crop go to seed), but shipping in seed is a lot better than shipping in finished product (especially since finished product likes to rot).
6. Ferns, moss, lichen, and fungus (mushrooms) are all plant/plant adjacent but do not flower or pollinate. Instead, they reproduce through spores. It might be nice to say, "And now we have a fern-based ecosystem," but remember that they all require substantial water and shade. Without a healthy forest system, they can't last long on their own, so take that into consideration.
Big changes are going to come to this area. With no pollen, it won't *immediately* become a desert, but it will head in that direction. Trees will stick around for a long time, but without *new* trees replenishing the old, as the old ones die out in the coming centuries more trees won't replace them. The same thing will happen on an accelerated timeline for smaller plants like bushes. Perennials won't last long. Annuals are gone next year. Plants with even shorter life cycles will be gone before people realize what's going on.
As the plants die, the animals that rely on them will die as well. No annuals and grasses? Goodbye rodent population. Goodbye predator population that feeds on the rodent population. Goodbye most insects. Goodbye predator population that feeds on insects.
[Answer]
All plants on earth stop producing pollen.
Good news first: all allergic people will stop suffering each spring. Enjoy it as long as it last!
Bad news: no pollen means plants will no longer reproduce. This will have as a result that:
* yearly plants will not be present next year nor they will produce seeds (including crops, wheat, corn, rice, beans, etc.)
* trees and bushes will also stop producing fruits, so no apples, pears, almonds, cherries, etc.
The lack of crops will result in a famine for a big part of population whose daily alimentation is provided, directly or indirectly, by crops. Remember most of the livestocks are fed with soy, which, have a guess, is a bean...
On the long term, since no plant is massively reproducing, there will be a reduction of vegetal coverage worldwide. Only some of the plants which can propagate seedless will continue multiplicating, at the cost of reduced genetic diversity.
Reducing the vegetal coverage will have the non negligible side effect of lowering the oxygen production, but on the other side the number of breathing animals is already strongly reduced, so this is a minor issue.
[Answer]
**Pastoral living.**
[](https://i.stack.imgur.com/WKQyE.jpg)
from <https://chamimage.files.wordpress.com/2012/12/maasai-herding-cattle_20070917_001.jpg>
Without pollen you will not have seeds. You need seeds to make a new plant (except for ones that travel by cloning, like bananas or watercress).
Perennial plants come back year after year, no seed needed. Many of the good pasture plants are [perennials](http://aggie-horticulture.tamu.edu/vegetable/guides/the-crops-of-texas/forage-grasses/). They have long taproots and come back year after year. Alfalfa is a legume example. If I am a pastoral nomad, my herds do not leave a swath of dead blighted earth behind them. They leave grasses of which the above ground part has been eaten. When the herds move on the grass grows back. This is why fire is not a big deal for prairie grasses either: the above ground stuff dies and the below ground stuff grows back. Many grasses also propagate vegetatively by runners. Crabgrass and bermudagrass are familiar example but others do too. That means grasses can take over adjacent bare spots without using any seeds. In the seedless world, humans would reseed croplands with clumps of grasses that would then spread.
Clonal plants can do very well for a long time. In a given prairie huge swaths will be comprised of individual ancient clones. From <http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1297&context=bioscifacpub>
>
> Some clonal plant species have very large and very old clones, e.g.,
> Gaylussacia brachycerium 1980 m diam, Aspen tremuloides 81 m diam and
> the grass Festuca rubra 220 m diam (Cook, 1985). Many of these large
> clones are estimated to be very old, e.g., for the species cited,
> 13,000+ y 10,000+ and 1000+, respectively (Cook, 1985).
>
>
>
Grasses already compete very well and a grass that could propagate by runners and establish a huge clone would have a huge advantage in a world without pollen: no annual weeds and once you cut them down or they died, no trees either.
Humans do fine on meat and milk. People around the world still live this way. In a grassland world without seeds you would have herds of cows, sheep and goats. They would eat the grass and you would eat the animals and their milk. And maybe some blood for delicious blood sausage.
I was wondering about vitamin C. I am not sure what the pastoral nomads did to get that. I am pleased to see that [scurvygrass](https://en.wikipedia.org/wiki/Cochlearia) is a perennial also. Watercress is loaded with vitamin C. So a little salad now and then.
[Answer]
Everyone will now have to eat bananas and any other crop that we produce through cloning.
I know that bananas are grown that way. That's why whenever there is a fungus or other disease that affects bananas, they lose the entire crop. Every single banana plant has the same genetics. When that happens, researchers then look for another banana strain that is resistant to that disease and that tastes good. Then they clone the heck out of it and give it to all of the banana plantations.
There may be other crops produced the same way and many others could be. It would be a lot of work and it is likely that they will only be able to feed a small portion of the current population.
Another issue is if we can create a nutritionally healthy diet with just those plants.
OTOH, the oceans will be fine. Plankton reproduces through other means. So, most of those food chains will be untouched.
[Answer]
**Tl;dr**: Almost all of it. How long depends on what kind of ecosystem.
Think about your basic trophic trees from high school biology. If the plants don't produce pollen, they don't reproduce, eventually they all die. If the herbivores have no plants to eat they all die as well. Then the carnivores die, and then the land becomes a barren wasteland, with some algae-based food-webs scratching a living where they can.
[](https://i.stack.imgur.com/2eW4O.png)
The time frame for this will be relatively fast (on a geological time frame). Within a year or two all of the annual plants will be gone, their seeds having sprouted, grown and died. Tree and perennial species will begin dying off more slowly, depending on their lifespans. However, this process will begin to snowball, because the lack of plant life will contribute to climate change and without reproduction, any loss of life would be devastating.
Furthermore herbivores will begin eating every green thing in sight, after the grass begins to die off (this will take some time, since grass can grow to some extent without pollen), leading to further decline in the survivability of plants.
Some animal life could survive by eating non-pollen-based photosynthetic organisms, like algae. Additionally, plants that could reproduce vegetatively would last longer (like potatoes and strawberries). The issue with vegetative reproduction is that it doesn't increase genetic diversity, this leads to a population unable to respond to changes in the environment, and with all the plants dying there will be a *lot* of changes in the environment. They will last longer, but not survive indefinitely, at least not without human aid.
That being said, decomposers will have a field day for a year or two, and you can expect to see a lot more mushrooms and the like. So expect the prices of fungal foods to plummet, at least until life stabilizes to a barely-scratching-out-a-living stage.
To sum up, most food chains will collapse, but the time frame will vary greatly depending on the ecosystem of the area. Forests will have trees for many years, and grasslands will have some sustainability, depending on the durability of the grass. Somewhere like a wetland would die very quickly. Animal life would follow the death of plants relatively quickly. An ocean biome would be almost unaffected, since no oceanic photosynthesis-capable creatures use pollen to reproduce.
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[Question]
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You've traveled back in time 65 million years, with no way to return. What evidence can you leave to ensure future humans will know of your existence?
[Answer]
This is very dependent on the technology you have available.
Given enough tech my approach would be retroreflectors on the moon. Build in as much redundancy as you can, both in the number of reflectors and how each is set up.
Each reflector has a gold wire coming off it leading to a buried capsule containing your messsage etched in metal foil, layered with a different metal so the whole thing doesn't just weld together.
If I couldn't get to the moon my second choice would be to head to Namibia and hope the desert there already exists.
If so I would go to a point deep in the desert and bury several message capsules. I would then make a ring around this many miles out. Drill a deep hole, place in it a tube. On the bottom is a lump of U-235, on the top is another lump. There is a support holding that upper lump that has radioactive material incorporated into it such that the decay slowly weakens the support. Calibrate these to break in 64 million years. (Of course this won't be perfect, the actual failures will occur over time. If you can be precise enough edge it closer to 65 million years) If the tube is undamaged when the support breaks there is a decent chance you get a nuclear detonation.
(BTW, for those who think you need something more complex: This is **not** a **reliable** bomb, you have a decent chance of a fizzle. It also must be U-235, a Pu-239 bomb like this is a certain fizzle, not to mention that your Pu-239 bomb will have long since decayed. However, if even one explodes it will be noted and fizzles will be found.)
In time somebody is going to discover the remains of your bombs. While natural nuclear reactors exist there's no known way to get a natural nuclear detonation. Thus even the discovery of one bomb crater (remember, the craters aren't all that old, they'll be much more visible than anything you did 65 million years ago) proves intelligence at work and would trigger a major effort to figure out what's up. If you get three detonations you provide an indication of the location of your buried messages.
[Answer]
This was originally posted to the Puzzling SE, which means that the poster has a specific answer in mind.
Since they chose the odd value "65 million years" instead of a round number, it is probable that the intended answer is:
You should cause [the Cretaceous–Paleogene extinction event](https://en.wikipedia.org/wiki/Cretaceous%E2%80%93Paleogene_extinction_event).
[Answer]
The problem with this question is you don't say what I have available to use to send a message. If I have no modern tech, I'm probably dead before I can leave anything that lasts a few years, let alone millions. Bacteria, animals way more experienced in eating other animals, unknown flora, lack of safe food supplies... I'm in too much trouble to worry about sending a message, I'm just trying to survive the night.
If, however, I'm a fully equipped traveller from the future with food and medicine enough to last a while, I would probably do what that one answer on the dupe question suggested and smelt gold and silver into coins and scatter them all over the North American Craton in hopes one might be found. Of course, Gold and Silver are nice for chemical stability, but not very sturdy for mechanical stress, so if I was able to smelt steel I might do the same with steel roundels and ingots. I'd have to find some nice, boggy place to put my stuff, and hope somebody finds it... I'm kinda lucky, because humans have all of future history to find it.
The best way to send a message forward from 65m years ago? If I have the ability to travel back in time, with any luck I've got the technology to easily achieve orbit. Using my advanced computer from the future, I'd compute a trajectory that would put a microsatellite in the vicinity of Earth in 65 million years, and hope I have the delta-V to put it there.
Or, if I have the Delta-V, I'd try to put a metal or stone tablet at a Lagrange point; then I'd hope that somebody in the future would put a probe or park a ship there and wonder what that artifact is floating nearby. With any luck, the solar wind wouldn't have destroyed my message.
The key, though, is that 65 million years is a long time.
[Answer]
The real question is would anything be left after that long? Even metal alloys would erode incredibly in that time. Even so if you made them unmistakably intelligent shapes, it still could be un-recognizable by then. There is a chance if you made enough of the same shapes, and scattered them around the globe there would be evidence left. Personally I like the Mt. Rushmore effect. So my answer is spend your entire life, aside from time spent surviving, carving and breaking the biggest rock formation on earth, and then spend even more time burying the formation in sand and dirt. If you made a sign or symbol in the rock that was large enough, maybe even carved out of a mountain, it might just stay. especially if you buried it hoping that humans would detect it later with some sort of sonar or infrared device, we use those devices nowadays to detect oil and mineral deposits.
[Answer]
Forget metals. Gold aside, none will last 65M years. Instead, think fired ceramics.. A humble dinner-plate will survive until it is ground into dust by erosion or melted along with the rock it has become part of. It's a perfect techno-fossil.
You can easily mass-produce a message for the future using a mould or a stamp on your wet clay. Aim for quantity not quality, because you have no good way to predict where to leave your message tablets so they will survive and be near the surface 65M years hence.
That's it, really. Scatter them around and hope. We can be pretty certain there was no house-brick using dinosaur civilisation because no such fossil bricks have been found
BTW if you have the technology to make big hydrogen bombs, and are willing to unleash such on the environment, evidence of that should survive. Craters lined with trinitite and shock quartz, and various long-lived isotopes that are not found in nature. The fallout layer might be global and detectable, as was the Iridium from the vaporised meteor that killed the dinosaurs. But would you survive that fallout? And, you'd still need ceramic tablets to carry an actual message.
[Answer]
Just few things that can survive that long, and **most of them are hard to do** and require process like many had answered here.
But you can do something that's quite easy, not a hard thing to do (while it need something to be hard), and it's already imprinted on our DNA :
>
> **just breed. Fill the Earth with your offsprings.**
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>
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And then tell your saga to your kids. For sure it would change the history of earth and mankind, but you get your message to the future anyway.
[Answer]
In light of the [feathered dinosaur tail that was found embedded in amber](http://news.nationalgeographic.com/2016/12/feathered-dinosaur-tail-amber-theropod-myanmar-burma-cretaceous/), I suggest you go hunting, then write a note, pin it to the dino, cover it in tree sap, and bury it.
Do this a bunch of times and wait.
You could also just write a bunch of notes and cover them in tree sap without the dinosaurs, but that's less fun.
[Answer]
Being from the present, you could know what artifacts survived through the years from memories of looking through museums and literature in your proper time. Also you would know the location of famous fossil digs, cave paintings etc.
This would enable you to pick sites with the most potential of being discovered. Lest your meddling interfere with history, definitely make many messages, but at least you know where and what has the best chances of being found, as you've seen it happen already.
[Answer]
Why not encode a joke (or something) into the junk DNA of a lifeform you knew would have its genome encoded in the future. Something so bizarre that it would attract attention.
[Answer]
Assume your traveler bumped in the year 1999 (65m years before his original time).
What he can do to ensure his identity maintains for years and people of his time get to know his identity?
**Short Answer:**
>
> ***Be Like Nostradamus!***
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>
>
**Long Answer:**
The traveler can sensationally opt to tell and share famous good or bad internationally known events which will occur after few years of 1999 BC. People of 1999 may not believe him until they see your first story coming true. Also the word "Sensationally" is important. People ought to remember things which are said in unique or unconventional ways.
For example: He tells people of 1999 about 9/11/2001 attack in NY something like this:
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> \*Five and forty degrees, the sky shall burn:
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> To the great new city shall the fire draw nigh.
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> With vehemence the flames shall spread and churn
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> When with the Normans they conclusions try.\*
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([Source](https://en.wikipedia.org/wiki/Nostradamus_in_popular_culture) of these lines)
And in 2001 when the incident happens, you can start your marketing and publicity in full swing (indirectly via your devotees or friends of course). People will record and publish your predictions (stories) and will continue to pass on the same if the incidents he chose to tell actually kept on occuring in consecutive times.
I am sure, a future citizen of 65m years away may not even know about something that happened on 9/11/2001 but I am sure that few events stays in history textbooks for thousands of years. Take old scriptures and religious transcripts.
Your traveler can even inscribe your stories in monuments and such buildings which are mostly restricted or protected and have potential to stay for years. Even if these monuments gets damaged, their photos, transcripts and literature will be kept for future people to show them how their "ancestors" way of architecting was artistic (like Big ben or The Taj Mahal)
And if not textbooks or monuments, use people and generations to pass on your stories (and most importantly your identity which at some point of time will reach the right year to target person).
**I bet metals and monuments may not stay for such a long time but folklore and literature does**
[Answer]
The only evidence you need it your bones.
There's a chance, sure that you will corrode away and not fossilize, however there's also the chance that you will. The best way to do it, would be to die.
That way you have a chance for future archaeologists to dig you up :)
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[Question]
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So in a world where giant rock and metal golems 'spawn' naturally. These golems are the kind with a power core hidden inside their bodies, their body and limbs are held together by invisible mana threads naturally with the core's help. The golem consumes mana to move which is why they are a bit on the slow side, but can absorb the mana from the surroundings to replenish their supply.[mana exists naturally on the planet and in everything, it's invisible and highly abundant in places with much nature, humans can't manipulate nor sense the power at all]
This golems aren't exactly the brightest, they won't go like 'oh look a giant city is in my way, might be a good idea to move out of the way.' and just plow through the city, they do try not to crush too much stuff but that's like a low level priority. However they have enough intelligence to identify hostiles and non-hostiles, they will crush any that try to harm them. They are have a strictly non-aggressive[they don't really mean to destroy anything] attitude until some fool tries to do something to them.
They do have a form of mana eye that allows vision and a natural regeneration ability in the presence of mana[which is everywhere] for when they drop off cliffs and mountains in their wander. These golems have something like wanderlust but are not against settling down for a few thousand years at places with high mana density, they also don't mind walking across the Pacific Ocean.
These golems are around 5 meters tall and wide when first 'birthed' and get reach heights around 80-100 meters tall and 110-120 meters wide when full grown at around 500 years old[they grow by absorbing mana], they also have about a lifespan of about 100,000 years which means that there are around 5000-maximum 10000 golems at any given time provided 100,000 years have past since their first birth as they spawn about once or twice every 20 years or so.
They are assumed to have been made by nature to combat corrupting monsters[these are much more hostile to life and they spread corruption that is something like a deadly plaque which can be cured eventually by mana, the monsters are only on the level of fearsome wolves and saber kitties that a squad of knights can handle]
Now what methods and strategies can medieval people carry out to cope with this wandering golems to prevent them from 'accidentally' making a road through their towns and cities? What kind of adaptations does humanity need to cope with these golems? They are considered to be something akin to natural calamities.
They look something akin to this without that strange thing on its back.
[](https://i.stack.imgur.com/VMOhH.jpg)
[Answer]
Actually with the size of the golems, I'm quite sure that any respectable town with sentries would spot them from miles away. Leading to...
**Kiting**
Provided that you're not going try harm the golem seriously. After those sentries ring the bell, a small squad of knights or hunters armed with bows can set off to lure the golem off from the city. Once the city's safety has been assured, they can scramble off to lose the golems pursuit in forests.
**Killing**
I don't find much of a reason to kill these guys since they guard against the corruption but say that the humans need some raw metals and minerals or maybe the golem core can be made for something. I'm not sure whether your medieval era has cannons but placing them on large horse drawn carriages and having extra horses to replace them when the horses on duty get tired might be a good idea. I'm not sure how much damage iron cannonballs can do against a rock/metal golem but I'm sure that if you can take out the legs then your victory is guaranteed unless their regeneration ability is ridiculous. Just be careful of raining rocks and trees.
Now certain adaptations in lifestyle might happen
**Mining**
As you have said that the golems can be made of metal, humans could possibly find a way to 'mine' the golems for their metal. Not only is it inexhaustible due to a golems inherent regeneration, it's a mine that is only 'exhausted' after 100,000 years. I'm sure that if the golems don't take the mining as hostile actions, certain golem mining groups might travel with golems across countries and then sell the metals at towns and cities that the golem passes by.
**Golem Biospheres**
With its inherent size, I'm going to say that plants and animals will find a way to have symbiotic relationships with golems. They could have evolved to depend on golems to live and breed on the golems. Plants could have evolved roots that sink into the rocks and many different species of birds , lizards, snakes, bats and insects can live on them. With the golems wandering around, I'm sure that they will affect the plant life and animals on the ground and sea itself, trees could evolve to be tall and spaced out to reduce casualties from walking golems and the golems footsteps can create mini ponds and lakes. Corals could evolve to grow on golems and breathe oxygen in the air when golems rise onto land.
**Golem Sports**
Humans could have evolved a sport similar to bull fighting but with golems, taunting and provoking the golems to chase them around. Humans could also have developed hunting seasons based off golems, say there was a species of flying chickens that live on the golems, humans can go hunt them down while the golem harmlessly passes by. Golem climbing can also be a dangerous activity, won't it be entertaining to see your buddies scaling a walking hill? Or fall and become a measly blood splatter on the ground?
How fast are they btw? I'll be worried if these massive golems can move as fast as trucks. A 120 meter wide golem could probably move slightly over 40 m in one step and that's if they are walking. Provided one step took five seconds... 28.8 km/h or 17.9 miles/h. If they start running then maybe about 60m per step in about three seconds... 72km/h or 44.7miles/h.
8 km/h away from my country's road speed limit. And if they start jumping...........
[Answer]
I think the best way is to repel golems from cities. Or make cities hard to enter for golems. As you say, there is very few mana in people inhabited places, and golems has no interest in staying in this places for long.
We can build moats with water around cities with high and slippery inner coast and gentle and easy to climb outer coast.
Even if the moats are 20 meter deep, we can build a 50 m mount on the inner coast of the moat. We can use the excavated ground for it.
Building this things is quite possible even with Bronze Age level tech.
When golem enters the moat, it tries few times to climb the inner coast mound. But surface of inner coast is too slippery (maybe defendants of city spill oil on it too) and after some time golem stops attempts and roams around the city. It is worth notice that golems are not so clever to become angry on people. They do not see the link between small meatbags hanging around and the river with unsloppy coast they have to cross.
And, with high probability golem will roam aside from city - because the outer coast of the moat is sloping and easy to climb.
BTW, watching golem struggling to climb the inner coast is a great entertainment for townsfolk.
This moats can help greatly against human invaders, outlaws, "saber kitties and loathsome wolfs" carrying the corruption.
Also we can build floating cities on boats on lakes, build cities on hard to climb rocks like Meteora Monastery in Greece:
[](https://i.stack.imgur.com/VWKqX.jpg)
Other way is to make golem movement too hard. For example, make some anti-tank constructions. Probably golem is intelligent enought to pass it by. Because it can spend to much time breaking it, and even get hurt from it.
[Answer]
There are quite a few ways how to deal with this.
**Just Accept Some Destruction**
You have maybe 10.000 slow moving natural disasters that create some chaos. That is not unlike some thunderstorms or hurricanes and tornadoes. Maybe develop some religious ritual, pray you don't get hit and live your life.
**Settle inside mountains or underground**
There are quite a few real world examples where people dug their homes, churches or other structures into mountain sides. Examples include Cappadocia, China, Tunisia, America, Mali.
(see for example <http://www.touropia.com/cave-dwellings/>)
**Nomadic tent cities**
Maybe most parts of the cities are actually moveable? Nomadic tents, ships or wagoons could make it possible to move out of the way. That would have been the case for [Karakorum](http://archaeology.about.com/od/mongolia/fl/Karakorum-Mongolia.htm "Karakorum") in ancient times.
One could even be so daunting to build onto those moving giants, like you build castles to sit in on elephants.
[Answer]
We're smart. The kiting method cited above would be a great idea. However, combine that with:
**Bait/Kiting** While we might not be able to sense what attracts them, we would be highly motivated to find out and use that as bait. This can be combined with kiting, that is, once one is spotted, attack and get it to change course enough to miss your city. Or open the gates and set up a wide "golem road" so that they just pass right on through. Non combatants get inside.
**Wide Roads** Though settlements there are golem roads, or wide pathways used to herd golem on to them, and prevent too much property damage or accidental death. Because unless they sense life (which it seems like they would, what with the mana thing) they'd go right through dwellings, which would kill some inside, even if they didn't fight. If you want to retcon it so that they don't destroy the homes of living creatures because they sense them being there, then everyone will definitely be inside in case of a golem passing through, if only to guard it because they know golems don't do that.
**Travelling with Golems** So these guys are attracted to areas of abundance? And they are huge? If I were a traveller, I would definitely say "I'm with that guy." Even if they don't know it and don't care about the people who travel with them, they could be a source of protection for travellers. This really depends on how fast they move (which will vary according to their size) and if they ever stop. It's pretty unlikely that someone will fire an arrow at you if you are right next to a giant engine of destruction. They might miss and hit the golem. I imagine too, that there are some people who follow them as a sort of pilgrimage or to lead them to a place of abundance. Ships or boats might even tie line to them to get them out part of the way on the ocean--who needs the wind? It's golem-powered! (But be ready to cut the line when it gets too deep or you'll be dragged under!)
[Answer]
It sounds like the best way to defend against these golems is to attack them when they come near a city, flee around the city to the other side (the golems are slow so this should not be a problem), lead them away a bit and then hide or run away.
Not finding the hostiles anymore the golem will (presumably) sart wandering again.
Even if the golem doesn't preserve the same direction after the attack it is unlikely that it will choose one that intersects the city. Even if it should, they can just lure it away a second time.
If for any reason they have to kill a golem they'd probably use big ranged weapons (like a trebuchet) to stay out of its range and ride in on horses once it's down to retrieve the core (and destroy it or, if that's impossible, hide in a cave too small for the golem to regenerate in/with an exit too small for the golem to exit).
Traps would also be used, given that the golem can easily be lured and doesn't have the intelligence to go around them.
[Answer]
Depending on how much it is likelly that a golem moves to the side one solution would be to have no big cities. If instead there was a cluster of 250 m radius settelments/buildings/keeps spaced by 500 m or so then the goolems could pass straigh through. The space inbetween could serve ass plazas suporting market stands and other quickly movable struktures. or fields to feed the population.
another strategy is living in movable struktures, carts or boats come to mind.
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[Question]
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A caveat I will begin this question with is this: this system MUST be entirely organic. In fact it must be EVOLVED. Therefore Ghost in the Shell or Metal Gear-style nanocomms or cranial implants are a no-go, because they rely on man-made technology.
With that out of the way, here's my idea. We already know that a lot of mind-altering fungal spores exist on our planet already, including the infamous "zombie ant" fungus Ophiocordyceps unilateralis. So let's say that on an alien planet a sauropod species evolved both intelligence as well as a symbiotic relationship with a certain kind of mind-altering fungal spore that grows on their outer dermis. Any organism that inhales these fungal spores is susceptible to their psychotropic effects, which manifest when the spores begin to settle and grow in the brain's neocortex, forming a sort of biological transceiver that is uniquely tuned to the saurupod species' brain waves. Using this fungus, these creatures develop language based around telepathic communication, and can communicate their thoughts across language and species gaps, as well as control the motor functions of organisms that have been infected by these fungal spores.
On a scale of one to ten, how plausible is this as a form of telepathy? Would it work on organisms like humans that come from outside their biosphere? Would the fungus die in an organism with reverse chirality to the fungus' own mycoproteins?
[Answer]
Edit: just now I re-read the question and saw that I missed the part about the sauropods. What I describe below can apply to any species with a brain or some other form of neural network, whether intelligent or not.
Fungi and plants can communicate amongst themselves through chemicals.
Now let's handwave a bit a lot. Let us imagine a fungus that communicates through electromagnetic waves as well. Let it be in the form of microwaves. Perhaps all lifeforms on their planet evolved to communicate thus at some level. This would be to their advantage - they can react much faster to many situations if they can communicate through radio signals. This would require evolution in their planet to have taken a turn different than our own at some point.
Let's say these fungi were bioluminescent in the past, and somehow shifted the frequency of their EM radiation from visible to microwave.
This is quite possible. One reason we can't see into the microwave spectrum is because, in order to see/sense an electromagnetic wave, we need a structure that is about the size of the wavelength involved. Visible light has its wavelengths around the nanometers, and we detect it with molecules within our retinal cells that are nanometers long. In order to "tune" into the microwave spectrum, we would need much larger structures - microwaves have their wavelength between milimeters and meters, units which are a million to a billion times greater than nanometers.
That probbly wouldn't do for our cone and rod cells, but a fungus might be able to evolve such a structure.
Now let's say that some intrepid humans have landed on this planet. Someone is bound to try to eat the fungus at some time. But the fungus isn't like anything which ever evolved on Earth. Most of it will be digested... But its microscopic spores may pierce through the bowels of the mad gourmet. If this doesn't cause the human to bleed to death, then the spores will travel through the bloodstream and eventually settle on some tissue, probably destroying it. Muscles may be destroyed, limbs may be amputated, but if the spores grow in the heart of lungs that's it.
Say that our glutton of a friend was lucky enough that the fungus didn't reach the heart or lungs. It landed on the brain instead. Now the bastard will die because the fungus will grow inside his head, causing the internal pressure of the brain to go way up. Vessels may burst. Dude may go blind or deaf depending on where the fungus is growing.
Ok, so he still didn't die of that, didn't lose any motor skills or sensory capacities, just gut a little stupider than he or she already was. The body's typical immunological response to that is calcifying the strange body that has appeared in the brain.
But that didn't happen. Instead, the fungus stopped growing, and now the neurons of the brain are starting to interface with the cells of the fungus.
Such interface is possible as well. [There are people who implant magnets in their fingers so that the nerves of the finger grow around the magnet and interface with it, giving the biohacker a magnetic sense at the fingertips](http://io9.gizmodo.com/what-you-need-to-know-about-getting-magnetic-finger-imp-813537993). If neural tissue can do that with non-organic matter, it should be able to do so with a fungus as well.
Congratulations to our crazy xenogastronomer, he or she can now probably sense and/or emit microwaves.
Now all they need is to find someone else with the same combination of genes and blind luck who can eat the fungus and go through the same process, so that they can talk radiotelepathically. I say combinations of genes because there are so many immunological responses to be bypassed, and so much phisiological and physical damage to be survived, that this is truly a dangerous experiment.
At some point people can develop technology to implant a fungal structure in the brain in a safe way. Until then, telepathy will be a gift from mother nature, and the people with the genes that allow one to survive the ordeal of eating the fungus may eventually be selected into a new human species.
[Answer]
The trouble with telepathy is it cheats. It assumes the transmitter can send a telepathic message without any biological organ to do the transmission and the receiver can pick up the signal without any biological organ to do the receiving.
* You can hear me speak because you have ears and an area of the brain dedicated to processing audio information.
* You can see me speaking sign language because you have eyes, and a visual cortex to process visual information.
* You can feel me tapping out morse code on your skin, because you have touch and pressure sensors. And again bits of brain to interpret them.
A snail (deaf) can't hear me, no matter how loudly I yell. A cave fish (blind) can't see me, no matter how vigorously I wave at it. No receptor organs = no message received.
So, I think you'll have to invent a 'telepathy organ' or organs. You've covered the brain bit in the receiving creature (with your fungus), but it still needs an ear/eye/antenna to pick up the signal and direct it to the correct portion of the brain. And the sauropods need a transmitter. See a4android's answer on biological radio for the realism of this.
The other thing that telepathy tends to forget is signal attenuation. It tends to have huge range with no loss of clarity and no loss of information content. Real world biological signals mostly don't do this. Sperm whales calling in the sound channel are an exception - and that's them taking advantage of physics, not something inherent in their biology (apart from the ability to dive that deep).
[Answer]
In essence what you're describing is biological radio. All the rest about the alien sauropods and the fungal spores are surplus to requirements. Even if an organism had a transceiver in their brain or elsewhere in their nervous system, they couldn't generate radio signals strong enough to broadcast past their skin.
On a score from one to ten for its plausibility, I'd give this zero. Sorry, if that's harsh. Short of coming up with a suitable mechanism for powering a biological radio then it's no go.
[](https://i.stack.imgur.com/QkP76.jpg)
Besides the sad truth is that the biological radio concept has been solidly debunked. However, I can give two semi-plausible forms of science-based forms of biological telepathy.
The aliens have abilities like electric eels. They have build up charge in a battery of storage cells and produce short bursts of electric discharges. The aliens also possess the sort of magnetic sensory detection that again electric eels and other underwater creatures possess too. They can detect the discharges. The range won't be brilliant. The discharges might be modulated into a language.
Animals with this ability live in environments where visual contact is extremely difficult like the murky water at the bottom of rivers.
The aliens have massively developed mirror neurones. This means their capacity to read each other's emotions and behaviour would be boosted far beyond anything we mere human beings can do. This would look like telepathy. It's doubtful if they could read humans and vice versa.
[Answer]
In a scenario like this nothing is truly impossible, but some things are *improbable*.
The first thing you have to establish is how exactly these spores communicate between hosts. Thoughts are awesome and all, but we don't know of any creatures which transmit/broadcast them, or any capable of capturing those sort of transmissions. This is the main plothole in your plan as I see it.
Even if we ignore that, however, you will still be very unlikely to mind control humans. Quite simply, our nervous system, brain structure, and thoughts would be completely alien to these spores.
They may infect us with absolutely devastating consequences (no idea how our immune system might react to this foreign organism), but how would they know what signals and impulses to send in order to perform certain tasks, etc. It's like trying to get a Mac and a Windows machine to play nice - they communicate in different languages, not gonna happen (this is a very low level analogy, please don't get hung up on networking, etc.).
In closing, telepathy implies that you have way of sending and receiving signals - almost instantaneously if you're hoping to mind-control creatures directly. And even if that were the case humans would have such a different biology that most likely the spores would not work on us the same way, or at all.
[Answer]
We're "telepathic" by way of auditory communication, you could vary this to make aliens that seem supernaturally telepathic if they utilise sound above or below our range of hearing. Ultrasound (higher frequency than we can hear) has an improved information carrying capacity at the price of reduced range, although if you're trying to communicate without being overheard that's actually advantageous. Infrasound (lower frequency than we can hear) has a reduced information carrying capacity but can go further, some large animals (elephants, crocodiles, whales) use this for long range signalling.
Creating Infrasound requires a large muscular diaphram, humans have utilized not-quite-infrasound with war drums to send signals over battlefields, suffice to say your fungus no matter how energetic just isn't going to be mechanically capable of creating that kind of sound. However I imagine (mind you I'm no chemist/geologist) it might be possible for a fungus to grow piezoelectric crystals and use them as a piezoelectric transducer to create ultrasound.
Leave the EM and radiowave communications to cyborgs and robots.
[Answer]
One evolutionary path is if the fungus communicated using EM signals.
[Electrical synapses](https://en.wikipedia.org/wiki/Electrical_synapse) use electricity instead of chemicals to communicate with each other. This typically means that they have to be really close together.
But if the fungus began to develop stronger and more sensitive communication cells, then the distance between them could be larger; First basically touching, to a few nanometers apart, then a few millimeters, then a few centimeters, and so on until they developed a kind of long range mesh network.
Fungus colonies that are close together would pick up and re-transmit the signal, boosting it in the process.
The more fungus in one area, the larger the distance they can communicate, and if some new fungus moves into range of a signal, it would repeat it, extending the range further still.
As to if they would infect humans, that's really up to you. If the spores either have a coating that cause the bodies defense systems to ignore them, or maybe bypass the defense systems altogether, then why not. The spores could grow/travel along nerves until they reach the area that you want, which would cause the infected nerve paths to act as an antenna for the signal.
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There are more than one scientific problems in this case:
1. You should check if the fungus is a parasite or if it's symbiotic. The problem is that there's and advantage for the sauropod, and that's telepathy, but what's the advantage for the fungus? If it needs only the brain as food for grow, it does not need to waste energy in order to give these powers to its guest. There must be an advantage for the fungus in order to allow telepathy.
2. If you want to base telepathy on something related to science, you cannot use chemistry. It's confusing and slow and entropy of reactions is simply too much in order to follow the order needed for communicating. If you want to communicate in real-time, you need a communication channel that's fast enough. I can think for example to Ampullae of Lorenzini of sharks. They are organs that allow to read very weak electric fields to find preys (and that's reality). It take advantage by the salt water that allows to sense electric fields more accurate, but the same principle can be applied. You can have a fungus made by a substance like the jelly one of these organs, and use them to read the weak electrical signals emitted by neurons. Also this is used in reality for electroencephalography for example. This way you can have more solid scientific background for telepathy: brains emit weak electrical signal and fungus are like antennas that allows to receive these signal. The speed is high so the bandwidth of the transmission is sufficient to send brain data in real time and I suppose that the brain of sauropodes are fast enough to elaborate these signals. Fungus can take advantage from this because the guest brain is filled by nutrient during the process, or it became bigger, or something else that repay the fungus for giving the ability to the guest.
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It's pretty much impossible.
Communication **always** requires a medium that acts as a transmitter, you ruled out sound (pressure waves) and sight (visible light waves) because that would not be telepathy.
Some answers have suggested a system similar to that of plants where chemicals are spread into the air, but that would not allow for enough complexity to communicate effectively and would need a specialized organ that is exposed to the surface, which your fungus does not have.
The method we humans use for long-distance communication is radio waves, which your species couldn't produce because they require a metal antenna. A biological organism can't produce antennae. Your fungus would be too small to hold one anyway.
Even if you could, somehow, find a way to make the transmission work, interspecies communication would be impossible. Even if one species could evolve to use a telecommunication protocol (i.e. a language) based on this, there's no way another species, which evolved independently, would use the same one. This is all the more true if humans traveled to this planet and are supposed to use it without adapting to it. The brain of a human is different from that of an alien so the fungus wouldn't attach to the right parts, but even assuming it does and somehow the native fauna's neurons work exactly the same as ours, the human couldn't interpret anything. It would just seem random noise, like that of a radio that is not tuned to a specific channel (to make an analogy with sound. If our brain interpreted it as vision instead it would seem like a broken satellite tv, etc.).
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[Question]
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(This question is quite similar to [How do you prove you're from the future?](https://worldbuilding.stackexchange.com/questions/12348/how-do-you-prove-youre-from-the-future))
I am an average person in the year 2016, living in, say, the USA. However I suddenly get transported back in time to 300 BC, to Persia. I did not prepare to this time-travel in advance. To be more precise:
* I'm aware that I've just undergone time-travel.
* Only me and my clothes have undergone time-travel - nothing else (no time machine).
* I know approximately what year it is (say, within an error of century), and I know approximately where I am (mid-west Asia).
When I land in Persia, I'm near a populated city, and two Persian "policemen" approach me, with their spears. I seem very alien to them, it frightens them, so they want to kill me.
My goal is to stay alive. I don't speak their language so it's hard to communicate with them. I need to act fast. My only chance is to show them something amazing, that I learned in the future.
What can I do?
[Answer]
First of all, if you go back to the 300BC you will find yourself in the Seleucid empire which controlled the area at the time following the division of the Macedonian empire as expanded under by Alexander the Great.
If any officials approach you they will most probably be either the city guard or posted soldiers in the service of Seleucus.
Unless you've gone out of your way to look extraordinary by wearing blinky lights or the such there is no reason why these guards or soldiers would be afraid of you. They are serving in one of the most cosmopolitan areas of the time and are used to seeing people with exotic features or dress.
Depending on the mandate of the officials they might not feel inclined to deal with you unless you try to enter the city or if you are harassing people. They are keeping watch over an area that might or might not be under threat of revolt due to the presence of occupying forces. They are busy. They don't care unless you make them care.
The first thing that will annoy them about you when they do care is that you are unable to make account for who you are and what you are doing there. You might be showing them some amazing things, but you don't respond when they ask you if you intend to sell the objects in the marked and you don't seem to understand that you need to pay the tax to enter the city with merchandise. You might also be an entertainer, but your show is more confusing than compelling.
The officials are struggling to understand why you won't leave them alone. Maybe you need assistance with something, but after a while chances are that they will begin to wonder if you are a bit crazy. Maybe they will attempt to drive you off or give you a beating to make you leave them alone.
You would have had a lot better chance if you had bothered to learn a bit of one of the ancient languages spoken in the area of the time or if you had brought precious metals or gems to bribe the guards to let you into the city. Once in the city you might or might not be able to find men of science and show them enough mathematics to convince them that you were worth listening to. Then after learning and perfecting their spoken language you might after some years be able to explain the concept of moving through time. Upon which you might be deemed insane, or possibly divine depending on whether they actually believe you. Either way you would have to prepare yourself for your life being changed in unpredictable ways.
You would probably fare better in the past if you never try to explain that you're from the future at all.
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1. The minute detail of the weaving of your clothes.
2. The futuristic diseases that your body carries that they are not immune to.
3. Sand down some glass, "invent" telescope and revolutionize their world.
4. "Invent" Windmill.
5. "Invent" other things.
Don't try with predicting history. Telling what happens could rewrite it and make them suspicious when it doesn't come true.
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I wouldn't/you can't. Unless you know something specific that will happen (or be heard about) in that exact part of the world in a fairly short amount of time ahead, all you can prove is that you have strange knowledge. You can't prove that this is from the future though (as opposed to say, from magical powers).
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[Question]
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A while back I answered a question about galactic economies with a semi-joke suggestion - wishes granted by an [Elder Race](http://en.wikipedia.org/wiki/Elder_race). I'd like to explore that further with the fortnightly challenge.
Background:
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> The E'kan'se are a race at least a million years old. Their entire culture, for all recorded history, has been obsessed with a single game. In their language, it literally means "Everything".
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> Everything is nearly incomprehensible to outsiders. As is best understood, games tend to last thousands or tens of thousands of years, and the minimum number of players is measured in the millions. A core concept of Everything is that it incorporates real-world economic data in some fashion - no one except the E'kan'se seem to know exactly why.
>
>
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The problem with this is that given the size of the galaxy, there wouldn't be any economies big enough or complex enough for the game. So the E'kan'se decided to create one by introducing a galactic, fiat currency that they provide in an arbitrary measure to any race that asks. This currency is backed by wishes - you make some sort of wish, and since they have technology that's nearly indistinguishable from magic, you might even get it.
So here's my question - if you're the E'kan'se, how do you implement this system? Specifically looking for ideas on awarding the currency, how it would be redeemed, encouraging participation, and preventing people from gaming/cheating.
The primary goal of the E'kan'se is to maximize the number of economic transactions using their currency.
[Answer]
Being backed by wishes would not encourage a large volume of transactions.
If I was holding currency that could allow the granting of my greatest wishes, then what could someone possibly offer me for it that is more valuable? Obtaining the currency would result in immediately bringing it E'kan'se bank and getting my wishes. It would be worse than any rush on banks we've ever seen in our own history.
The best way to implement this would require the possibility of a wish being granted by way of *spending* the currency. Backing the currency with wishes makes the currency far too valuable, and differently so to each person. Basing the wish granting system on transactions would be a better way to get everyone to make as many transactions as possible.
The gaming of this system that would need to be kept in check would be things like trading money back and forth for no other purpose than making a transaction. A sliding scale of wish granting probability would need to be implemented depending on the value of the transaction, otherwise people would give the lowest denomination to everyone they met.
The E'kan'se would then act like the Fed, raising or lowering wish probability to encourage spending or saving respectively. This would allow them some moderate control of their game.
Additionally this makes it a system of fiat money; a currency with a backing is not a fiat system. This allows the addition of new races and civilizations without need to add new wishes or devaluing the existing currency.
[Answer]
Wishes have the problem that their effectiveness can be arbitrarily increased or decreased. Additionally, they are difficult to divide, share and trade. This means that the required input to get a single wish could be astronomical. I offer a new model - the Joule. The homonym is only a happy accident.
A standardized unit of energy transmission, without loss, can easily transcend all cultural barriers with very little miscommunication. It can boil water, power a city, put a ship in space, and accelerate so close to light speed it doesn't matter that it's not actually the speed of light.
Matter and energy have equivalence, so if you want to buy a thing, you have to be able to afford all of its components. You can save money by using natural resources to build an engineless ship, and then spending your Joules on acceleration. Mining asteroids is immediately and automatically profitable, as it gives you access to matter for trade that doesn't blow holes in your planet. Depending on how the E'kan'se feel about it, Joules may/may not be used as weapons of mass destruction from across the galaxy, but I bet they won't allow it - it is now trivial to cause an extinction level event. If you want to go to war, build weapons the old fashioned way and spend your Joules flying.
So direct matter energy trade is a thing, so what does economics between planets consist of? Intellectual property and licensing fees. If you want to create value beyond matter/energy equivalence, you have to be creative. Write a novel. Design a pastry. Make honest-to-Jibbers no-magic pants for sale. Be vintage, trendy, or counter-culture.
There are a couple of interstellar communication schemes this allows. If the E'kan'se use of Joules doesn't have to obey relativity, any user in the universe can send a message to anyone else in the universe at any time. It could be as simple as a spoken word generated by vibrating the atmosphere, for a cost in Joules. The guy who developed *that* app would get a lot of Joules. If the request can't arrive at the destination faster than the speed of light relative to the sender, that's ok - I'll bet they can bankwire Joules in and out of arbitrary accounts in real time. It turns out there are a lot of bits in "transfer exactly 123456789 Joules to [some arbitrary account number].
Now - can you *imagine* what charitable efforts would look like in a universe where you could do arbitrary things at arbitrary distance with perfect matter energy equivalence? We could make Santa a real thing. The E'kan'se would get to see what people do when they can do *anything*. That would probably make an interesting game of Everything.
[Answer]
**The Currency Itself**
I'm assuming your Wish has limits - relatively small limits, if it's to be of any real economic use. If that's true, then there's a definite exchange rate in the local economy of whatever backwater planet the Wish ends up in - one Wish is worth very roughly [whatever that wish could get you in the local economy].
The implementation of wish-granting would require the usual nigh-magical hyper-tech: nanomachines running an AI with nigh-infinite storage and computing capacity. The E'kan'se program said AI with what a wish is "allowed" to accomplish, the AI uses its own judgement when interpreting wishes, and the nanomachines self-destruct after producing the wished-for item. The nanomachines would phone home every time a Wish is granted, so the E'kan'se can a) veto the wish if those clever locals have outsmarted the AI, and b) keep tabs on what sorts of things are being wished for. This would prevent cheating: the wish-granting AI itself is clever, the AIs can collectively be networked to track trends and determine whether someone's gaming the system, and the E'kan'se would have final control if they think someone's abusing Wishes.
You'll need to determine where the line is, and which wishes will be refused. Here's a handful of things that probably cross it:
* Wishing for the eternal servitude of the wish-granting AI. Even if further wishes are off-limits, the AI is going to have to be well-stocked with nearly enough information to take a civilization post-scarcity all by itself. (This wish is equivalent to "most of the knowledge in the universe, plus somebody to curate it for me.")
* Wishing for a self-operating factory. You can tweak the exact cutoff, of course: maybe asking for a grain factory is okay, asking for a bakery is iffy, asking for an arbitrary-food-creator isn't allowed, and asking for a produce-anything-including-more-factories nanomachine factory gets you struck by lightning.
* Wishing for anything directly contrary to the E'kan'se's goals. This is nebulous, but the E'kan'se want the civilization to continue to exist, to grow, and *not* to supplant the E'kan'se.
**Earning them from the E'kan'se**
Since Wishes are worth more than anything your own pitiful civilization could possibly produce, and the E'kan'se grant them whenever they feel like it, the E'kan'se are *very nearly* running your pitiful civilization. Why sow grain, when you could wish for a grain-producing machine? Why listen to your government, when you could wish for a robot-army-producing machine? Why do anything other than *the activities that have the best chance of granting you a Wish?* Any local economy that gains access to the E'kan'se will be severely warped: a single Wish might be enough to topple a government, so if there are rebels, expect the government to fall sooner or later.
If wishes are rare, then each individual Wish will be worth fighting wars over. On the other hand, if the E'kan'se hand out wishes left, right, and center, then the economy will suddenly become post-scarcity, which is a [question of its own](https://worldbuilding.stackexchange.com/questions/2671/consequences-of-the-shift-to-a-post-scarcity-society). You'll be most interested in some sort of middle road – some people, by working hard enough, will be able to earn them, and there will be enough Wishes around that a government won't *quite* move heaven and earth to get one.
**What the E'kan'se will pay for**
The E'kan'se want to increase the size of the economy, so they'll hand out Wishes to people who do that. Depending on how capricious the E'kan'se are, they might not even tell anyone why they got a Wish, which will be a little like putting every CEO and entrepreneur in a Skinner box with a lever that dispenses Wishes. Here's the kind of things that the E'kan'se are likely to reward:
* Creating new markets for existing items of the local economy
* Expanding trade networks – ideally, off-planet or cross-galaxy
* Creating new types of [token economies](http://en.wikipedia.org/wiki/Token_economy), like gold stars or gamer points
* Inventing fads – every fad is a tiny boom-and-bust cycle that inspires the next fad
**A complete tangent**
The novel [Singularity Sky](http://en.wikipedia.org/wiki/Singularity_Sky) will interest you: the Festival, a traveling post-scarcity civilization, grants wishes if you'll tell them a story. (It causes massive havoc on any pre-scarcity civilization.)
[Answer]
**Ulterior Motives?**
How would we, unsophisticated new races, ever know whether the wish tokens were true benevolence or sinister bait by a race trying to take advantage of our naivete?
What appears to be a great boon (wishes from an Eldar Race) may turn out to be something altogether different. This is what happens in Vernor Vinge's [A Fire Upon the Deep](http://en.wikipedia.org/wiki/A_Fire_Upon_the_Deep).
In one case, the boon was a lure to catch the unwary. People attempting to "cash in" the promise of the evil Eldar Race's promises actually allow it to escape its prison.
In a more benign case, the boon was a lure to get others to serve the Eldar Race's own interests in the end.
In any case, what seems to be too good to be true, usually is. Exercising those wishes might have a cost. It might require one with a great deal of wisdom, intelligence, or experience with the E'kan'se to get the meaning of the wish filled correctly.
**Other Notes**
It might not be as easy to cash those wish tokens as some might like or encounters with the E'kan'se might be so rare that many people never get an opportunity to cash the wishes,
In such a case, trading them for some other fair value might serve useful purposes.
**Discussion of currency, coinage, and backing the currency**
Also as others pointed out, the E'kan'se tokens might be so valuable that no one actually trades these coins (or the do so rarely). The Galactic coinage might represent fractional value of one of the E'kan'se wish token. This implies that the entity making the coins is backing them by E'kan'se wish tokens. As we know our governments are not very good at keeping their word so trade in your real E'kan'se wish tokens for the fractional coins minted by local governments at your own risk.
In fact, bad currency drives good currency out of circulation so as soon as some government start minting the fractional coinage, all the E'kan'se tokens would disappear (people would hoard them). People would only trade their tokens as a last resort.
For example, when governments stopped backing their currency with gold reserves, all of the old gold backed currency was immediately kept (hoarded) and people only spent the "bad" unbacked currency.
**Treatment of similar Eldar Race in other works**
Consider the Outsiders from Larry Niven's [Known Universe](http://en.wikipedia.org/wiki/Known_Space). They trade in knowledge. How much is FTL drive worth to your species when it's losing a war for its very survival?
The Outsiders now lease one or more bodies in our Solar System indefinitely and that's barely scratched the value of their credit with terrestrial governments.
[Answer]
**The Scope**:
* The effect of the E'kan'se's fiat currency spans `the size of the galaxy`.
* The currency is doled out in `an arbitrary measure to any race that asks`. As a question has been asked about awarding the currency, I will take 'arbitrary' in a Watsonian sense; currency may be doled out according to specific rules, but from an outsider's perspective, it's unpredictable.
* This currency is `backed by wishes`, which I take to mean; you make a wish and then, depending on *factors*, the currency is 'deducted' and then, for *reasons*, wishes are granted, specifically, by the E'kan'se.
* The primary goal of the E'kan'se is to `maximize the number of economic transactions`. It is not stated whether this means 'wishes granted' or 'currency traded', but I'll assume the latter.
**The Question(s)**:
How would The E'kan'se implement this system? Award the currency? Redeemed currency for goods/services rendered? Encourage participation? Prevent people from gaming/cheating?
**My Take on Implementation**:
To prevent an immediate run on the banks, certain stipulations would need to be in place. For instance; you can not use *The Currency* in the home systems of the E'kan'se. You must travel elsewhere. Though perhaps another stipulation might grant usage within the perimeter of E'kan'se space if that usage is limited to discreet requests of a transportational nature. "My space ship broke down, I need parts/fuel/teleport/etc to get home."
The question for how it should be implemented is, in my mind, defined by the scope. The E'kan'se want *The Currency* to be widespread throughout the entire galaxy. The E'kan'se are not necessarily all pervading. Likely, they have only a few remote homeworlds. So the E'kan'se will require a method of cashing in *The Currency* for its primary commodity, wishes.
Since we're already dealing with technology that is indistinguishable from magic, let us say that this technology is capable of being exchanged remotely. There must be a way, then, to keep track of the wishes themselves; the user speaks (or perhaps even thinks with firm intent) and the wish is submitted. You make a wish, and *The Currency* itself acts as a transmitter, sending that wish detail to the "central server" (because as every MMO developer worth his salt knows; you never trust The Client).
**Inflow**:
*The Currency* must be rare to be considered valuable, but not so rare that it cannot be spread throughout the galaxy. Perhaps *The Currency* can be spread via automated drone or teleport, delivering new wishes throughout the cosmos to societies that may be prepared or able to receive and understand it.
Perhaps it is also spread by 'wishing for more wishes', though that certainly can be limited for purposes of economic balance. Perhaps also through actions considered Noble to the E'kan'se, whatever those might be.
**Outflow**:
So you make a wish. *The Currency* transmits your wish to The Server. At that point, an arbiter (either AI or E'kan'se, or both) judges the validity of the wish, and the ability of the E'kan'se to grant such a wish (Can time be 'rewound' in local areas? Can the user wish for more of *The Currency*?). Then they press the big shiny green button, and Wish Granted!
Of course, it's not as simple as that. *The Currency* needs to keep track of who owns it, so it knows whose wish to grant. It needs to be able to be signed over to a new party (which can be a process as simple as the wish itself; you wish for the third party to be the new owner of *The Currency*, and The Server is updated). *The Currency* needs to be aware of when the wish is accepted by The Server, so that it can self-destruct, or more economically feasible, return/teleport back to the E'kan'se vaults.
**Encouraging Participation**:
Items that grant wishes practically sell themselves... Even if those wishes are as technologically simple as 'emergency teleports' or 'teleport my missing car keys into my hand'. But to encourage participation, perhaps *The Currency* is gamified; spreading *The Currency* to new cultures may earn you more, at a certain ratio. Defending the E'kan'se may earn you some, as may encouraging new cultures to introduce themselves to the Elder Race that Grants Wishes.
**Preventing Cheats**:
Each individual physical representation of *The Currency* keeps an active connection to The Server, and so is potentially monitored and recorded at all times. Any new connections to the server that have an invalid history will be recorded, and any potential wishes emanating from them will not be monitored or granted.
Eh, that's all I got. Let me know if any of this needs elaboration. ;)
[Answer]
So you're going to combine credit card rewards programs and the lotto.
The Elder Race goes to the other races, and says: "Every $ spent using my digital currency device (aka, credit card) earns you in a 1-in-x chance of getting a wish." The value of x is varied by the E'kan'se depending on the individual psychologies of the target races.
The E'kan'se takes a small percentage of every transaction - this helps both to finance the empire and ensures that people do not abuse the system by simply trading $1.00 back and forth.
In cultures where winners ask for simple things there will be many winners, and little fanfare. In places where winners ask for truly incredible wishes they are rare and celebrated - perhaps flown to the E'kan'se home-world to petition the governing body in person - or maybe huge parties are thrown in their honor.
The Elder Race tailors the specifics to each target audience, but in the end everyone buys in - the cost is basically nothing and the potential rewards are great.
And the E'kan'se monitor every economic transaction that takes place in their sphere of influence...
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[Question]
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The world of Pandemonium is a world in another universe where humans may exist, that is gravitationally connected to Earth in our universe. Over the course of history since the big bang, these universes have periodically collided, transferring organised matter from one to the other, including humans... and other animals, including dogs.
On Pandemonium, the science of genetics surpassed that of our society long ago, and genetic transhumanism has become the norm, in order to adapt the humans that live there to their alien environment.
However, while dogs are a popular pet in many nations of earth, I wanted to have dogs be unpopular as pets on Pandemonium. The rationale that I came up with is that despite dogs being easily bred to have a wide variety of traits on earth, and the people of Pandemonium being expert genetic engineers, the following problems exist with dogs in the view of Pandemonians:
* Dogs are dangerous large pack predators that attack and kill humans too frequently.
* Dogs are unclean.
* Dogs are noisy
* Dogs are only suited to be working animals in industries such as security, policing and farming.
Of course, these reasons are reason enough for a society to reject dogs as pets for the most part, since it can be so because I *say* it is so, and we have real-world examples of societies that are biased against dogs. However, that's not the point of this question.
* Dogs can easily be genetically engineered to have many different traits, but their essential 'doggishness' cannot easily be removed.
I wanted this to be the primary reason why dogs are not pets Historically, the Pandemonian genetic engineers couldn't change dogs so that they were no longer dangerous, filthy, or noisy without breaking the ineffable something that makes a dog a dog. They *did* produce things *from* dogs that make good pets, but they weren't *Canis familiaris* any more. The genetic engineers *can* now genetically engineer dogs as required to make 'good pets' without having to make them into a new species, but the longstanding prejudice against dogs still exists, and they'd be ridiculed or censured for trying.
Is this genetic engineering problem a reasonable justification for "Dogs aren't Pets" on Pandemonium, or am I barking up the wrong tree?
[Answer]
I can't but feel it needs to be two things. Slight early cultural difference AND genetic manipulation issues.
I am imagining scenario, where during one of your collisions a Paleolithic dog (Canis c.f. familiaris) was transferred, partially domesticated, but not enough to immediately see the benefits. As other animals already fill the dog's role. So instead it is left to its devices, but is widely known as a wild dog, with which they have relationship like we with wolves (that is, chasing them away or outright hunting them).
When the genetic engineering became dominant, scenario as you described occurred, where they were tried and failed to turn it into a "good pet", at the same time other animals were successfully turned into suitable household pets. This early failure, when compared with successes with other animals, stigmatizes the dog as a useless animal.
When the actual Canis familiaris which is just a stone throw away from being a great pet by the optics of your wold appears during next collisions. Nobody wants to really deal with it anymore because of the stigma with the species, that resembles it way too closely for comfort.
[Answer]
Those aren't dogs, they're wolves. Kinda.
There is a bunch of discussion about the correct classification of dogs, wolves and dingos - Some folks put them all under *Canis lupus*, with the domestic dog being *Canis lupus familiaris*, while others split them at the species level between *Canis lupus* and *Canis familiaris*. This discussion exists because, while dogs and wolves are very different behavior and appearance wise, they can breed true - and their hybrids can produce offspring, which seems to indicate that they are from the same species. Whatever it might be the case, the proper classification of dogs and wolves is a complicated thing. What counts for us is that the animals are genetically close.
This is useful story-wise, as we can make it so that the genetic manipulation necessary to make the dog sturdy and able to survive in Pandemonium also makes it more wolf-like, bringing back a lot of instincts and behaviors of old that were weeded out in the domestication process - specifically, the hunting aspect.
Pandemonium dogs are primarily *pack hunters*, as their earthling ancestrals were. They can be used as work animals, as security, and even as service animals if properly trained, but they are still very prone to chew down a throat or two if they get upset for some reason. They are adapted to this new place, and this makes them look more like demonic wolves than proper dogs - which make them poor pets, unfortunately.
Some of the breeds might even be born with three heads. Go figure. Genetics are weird.
[Answer]
I think that these reasonings make sense, and are internally consistent, but one thing to note is that there are humans who keep racoons or any number of other socially-stigmatized animals as pets. If the sapients of Pandemonium are similar to humans in this way, then there may be small groups or even dedicated pan-wide-web communities insistent that non-GMO canis familiaris are amazing household animals.
[Answer]
Many societies dislike dogs for a variety of reasons already.
Dogs are one of the few creatures that will mate with it's siblings or indulge in inter-generational incest quite happily right in front of you.
Many societies view dogs as food, others as workers. Some as both. Not everyone see's them as pets.
[Answer]
It's completely unreasonable. In one statement you state they have surpassed us in the field of genetics and then state they can't do what we pretty much have done now. Your four statements aren't defining characteristics of dogs and could all be bred out and still have a dog. A small, mute, hairless dog bred to excel at finding cancer, doesn't check any of your boxes, but I would consider it a dog. Ultimately I think they category of dog is just to wide to say a master geneticist couldn't alter significant traits and have it not be a dog. It would be fine to have it just be an arbitrary dislike, but would feel like a stretch to say they lack the ability to breed out a handful of traits.
[Answer]
# Body Language
[](https://i.stack.imgur.com/7CnCw.png)
These are all good reasons not to like dogs. But they do not work in the real world, so it's hard to believe they work in the fictional world. At least without some other ingredient.
For that, I suggest the demon people simply do not recognize the body language and facial expressions of a dog. To a pandemon, the above picture is no more appealing than this:
[](https://i.stack.imgur.com/Mm3nw.jpg)
Dogs and pigs are about as smart as each other. [They can both make good pets](https://www.youtube.com/watch?v=PrJi-P61aLY). The key difference is dogs have more body language in common with humans. That's why we prefer dogs to pigs.
I suggest dogs do not share the same body language with pandemons. So they treat dogs the same as they treat pigs. As loud, filthy, smelly, dangerous animals.
[Answer]
### They dont stop barking
Dogs have a very good developed sense of smell and are sometimes used to detect various deceased, simply by smelling people.
Now you have altered people, not made by nature. It might work for us just fine, but the dog just go crazy because *something* is wrong.
Just imagine that high pitch rodent repeller, you know that one that tears your brain in two when it goes of, **all day long**. You'd loose your calm too. That, but for the dogs the smell equivelant.
Smelling is a core dog feature, turning that off ment they dont smell food anymore and simply starve, something the Pandamies just cant figure out how to fix.
[Answer]
Dogs have an exceptionally sensitive nose. Which is how some can be trained to smell cancerous cells, drug smuggling or explosives.
Perhaps one of the popular gene mods in Pandemonium make humans produce a smell that triggers some pheromone responses in dogs. If it were as simple as "I'm a bitch in heat", then neutering male dogs would be sufficient, but it is possible that there are other pheromones that would require far more invasive or morally repugnant treatments for dogs (like nose-removal that makes every dog's nose like a [pug](https://en.wikipedia.org/wiki/Pug)'s nose). One SF tale that might give you ideas in this direction would be *[The Screwfly Solution](https://en.wikipedia.org/wiki/The_Screwfly_Solution)*.
[Answer]
## It's the dogs that don't like Pandemonians
Dogs are naturally aggressive creatures that have over the course of thousands of years been breed not just to get along with humans, but to protect thier masters from other humans. Dogs can sense when a person is planning to do something bad to thier master because we get an elevated adrenaline levels that don't correspond with thier body language. When a Human has elevated adrenaline but looks calm, it makes thousands of years of carefully breed protective instincts kick in making the dog bark or even attack the untrustworthy intruder.
However, the Pandemonians have engineered themselves to be faster, tougher, and stronger than Terrans resulting in a higher resting adrenaline level. This makes them all come off as untrustworthy all the time to dogs; so, instead of bonding with their Pandemonian caretakers, they always treat them as dangerous outsiders.
[Answer]
Not genetics, because you say they are more or less masters of that art, and it would be admitting a defeat if they cannot engineer themselves around that kind of problem. There has to be some other reason, possibly something that pertains to their nature.
Maybe they think that having dogs, or pets in general, is too childish, a thing that puny humans do - having one is like an adult sucking on a pacifier, or an adult playing with a doll.
] |
[Question]
[
Needlessly long names aside, how would this weapon work?
Made from scratch with junk scavenged from a 21st century world, post nuclear apocalypse. Assume nothing was specifically preserved, only the knowledge of our protagonist(yours).
I want a projectile weapon that uses anything you can fit into it(I avoid saying "gun" because I doubt you can make one good enough for this, and even if you can, at that point get a better gun).
Think the"Junk Jet" from Fallout, only a bit more reasonable.
No fancy autoloader system needed here.
If possible, I also want to be able to retrofit it into a nice melee weapon.
All that said, using what is availible, how can ouur hero convince this set of spare parts to output the junk he inputs wuth enough force to be a weapon?
[Answer]
>
> I want a projectile weapon that uses anything you can fit into it
>
>
>
A historical example of such a thing might be a [blunderbuss](https://en.wikipedia.org/wiki/Blunderbuss)... a sort of flintlock ancestor of the shotgun which *sometimes* was loaded with stones and bits of wood and any other crud that could be rammed down the barrel. Problem is that a) jamming rubbish into your gun damaged it and b) random bits of junk tend to be quite unaerodynamic which sharply limits your range and likely reduces their ability to damage a target as well.
The Junk Jet (and its predecessor, the Rock-It Launcher) aren't afflicted with real world physics, which is why arbitrary items can become deadly projectiles. Unless you want to radically soften your setting's physics and bring in the rule or cool and/or funny, you can't make a practical weapon this way.
[Answer]
What's wrong with a [sling](https://en.wikipedia.org/wiki/Sling_(weapon))
>
> A sling is a projectile weapon typically used to throw a blunt projectile such as a stone, clay, or lead "sling-bullet". It is also known as the shepherd's sling. Someone who specializes in using slings is called a slinger.
>
>
> A sling has a small cradle or pouch in the middle of two cords (retention cords). A projectile is placed in the pouch. There is a loop on the end of one side of the retention cords. The middle finger (although some slings have a wrist loop) is placed through a loop on the end of one cord, and a knot, or tab, at the end of the other cord is placed between the thumb and forefinger. The sling is swung in an arc, and the knot/tab released at a precise moment. This action releases the projectile to fly to the target. The sling is much more than merely an extension of a human arm. By its double-pendulum kinetics, the sling (or woomera) enables stones (or spears) to be thrown much further than they could be by hand alone.
>
>
> The sling is inexpensive and easy to build
>
>
>
or an [atlatl](https://en.wikipedia.org/wiki/Spear-thrower)?
>
> A spear-thrower, spear-throwing lever or atlatl (pronounced /ˈætlætəl/[2](https://en.wikipedia.org/wiki/Spear-thrower) or /ˈɑːtlɑːtəl/;[2](https://en.wikipedia.org/wiki/Spear-thrower) Nahuatl ahtlatl [ˈaʔt͡ɬat͡ɬ]) is a tool that uses leverage to achieve greater velocity in dart or javelin-throwing, and includes a bearing surface which allows the user to store energy during the throw.
>
>
> It may consist of a shaft with a cup or a spur at the end that supports and propels the butt of the spear. It's usually about as long as the user's arm or forearm. The user holds the spear-thrower in one hand, gripping near the end farthest from the cup. The user puts the butt end of the spear, or dart, in the cup, or grabs the spur with the end of the spear. The spear is much longer than the thrower. The user holds the spear parallel to the spear-thrower and going in the other direction. The user can hold the spear, with the index and thumb, with the same hand as the thrower, with the other fingers. The user reaches back with the spear pointed at the target. Then they make an overhand throwing motion with the thrower while letting go of the spear with the fingers.
>
>
> The dart is thrown by the action of the upper arm and wrist. The throwing arm together with the atlatl acts as a lever. The spear-thrower is a low-mass, fast-moving extension of the throwing arm, increasing the length of the lever. This extra length allows the thrower to impart force to the dart over a longer distance, thus imparting more energy and higher speeds.
>
>
>
The sling in particular is great because you don't need to worry about taking a lot of ammunition with you, as long as you can find stones around you.
[Answer]
Old old OOOOOLLLLDDDD school: hands.
Nearly everybody has at least one.
They can project nearly anything as a weapon. With some practice you can use a wide variety of stuff as ammunition. Just some examples: pebbles, broken furniture, dead animals, live animals, broken guns, working guns with no ammunition, rotten eggs (for that improvised chemical device effect), buckets of sand, etc. etc. etc.
They can be used quite quietly/stealthily in case you need to avoid spooking the quarry, or its mates.
They can be used to carry home your target if it is edible.
They add little to your encumbrance in case you must walk a long distance.
From small-furry-animal, to that annoying guy with a stick, to an apple just out of reach on a tree, to the last can of peas on the top shelf, hand-thrown projectiles can be, well, handy.
[Answer]
Since you have a hopeful mention of guns I am assuming the character will have the means to produce and maintain the weapon at least initially, but lacks the material to build ammunition ("all I have is enough metal for the gun" or something similar). But does have the means to create gunpowder or other explosives to fire the projectiles he does find.
The humble but reliable Pump-Action shotgun.
As long as you have a proper sabot to carry the projectiles in you can fire pretty much anything that fits the bore. A 12 gauge is about 18,5mm size and even a shaped stone projectile(s) can be effective.
Just like a sling or other lower-tech weapon the aerodynamics of the projectile will determine the accuracy, but even if you use basic nails as ammunition your gun can be effective. Just not out to a large range. Solid slugs made from a variety of materials would also be effective, although without machine tooling the accuracy will be low, meaning that you will have to rely on ball-ammunition rather than aerodynamic projectiles.
Pump-action shotguns are more lenient and forgiving than shotguns that use other means of cycling the load, making them more reliable and sturdy. Which is what you want if you might not be able to service your weapon properly over extended periods of time.
[Answer]
**Hollow barrel crossbow.**
[](https://i.stack.imgur.com/rN2aZm.jpg)
I invented this just now, for you. The bow is a leaf spring from a truck. The string is a steel cable. You whittled the stock out of a canoe paddle. On firing, the string pushes a cylinder down the barrel. Anything you put in the barrel comes back out, fast.
Because regular crossbows are great until you can't find any bolts. Guns are fine until you can't find the right ammo. Dynamite powered blunderbusses are fine... well, they are fine. But the hollow barrel crossbow will shoot anything you can fit in the barrel including that stick of dynamite you were saving for the blunderbuss.
Suffice it to say that this thing will accept whatever you want to put in it. Its working name is thus quite short but not fit for printing here.
Original crossbow source: <https://www.youtube.com/watch?v=7Jfn5j9fadw>
[Answer]
A Blunderbuss
The precursor to the shotgun, they were meant for this kind of thing. The general idea is as follows:
1. Take a wide, un-rifled tube and securely cap one end. The other end should preferably widen in a bell shape, but it isn't necessary.
2. Bore a small hole near the capped end.
3. Stick some saltpeter-soaked cord through the hole you bored in the previous step.
4. Put some gunpowder in it.
5. Put some rocks, nails, and other small hard things in.
6. Tamp it down (carefully, so that you don't accidentally set off the powder.)
7. Point it at the target and light the cord.
They leave something to be desired when it comes to range and accuracy, but that's not really relevant in the kind combat they're used for.
] |
[Question]
[
The idea for this animal is it filters through the sand to catch small insect-like creatures that are 2-6 inches long. I'm thinking of giving it a sieve-like pouch of skin at its throat that filters out most of the small grains of sand. I'm also thinking that maybe it could have a separate track for the larger grains of sand to go through a different path in the digestive system.
Another possible way to do this is to make it only swallow the insect-like creatures and spit out the sand. Maybe a combination of all of them.
[Answer]
**Baleen whale style?**
<https://en.wikipedia.org/wiki/Filter_feeder#Baleen_whales>
>
> The baleen whales (Mysticeti), one of two suborders of the Cetacea
> (whales, dolphins, and porpoises), are characterized by having baleen
> plates for filtering food from water, rather than teeth... Baleen
> whales typically seek out a concentration of zooplankton, swim through
> it, either open-mouthed or gulping, and filter the prey from the water
> using their baleens. A baleen is a row of a large number of keratin
> plates attached to the upper jaw with a composition similar to those
> in human hair or fingernails.
>
>
>
I am thinking here of a sand eater that eats sand and bugs then spits out the sand and keeps the bugs. The flap would be like baleen to keep bugs in and let sand out. Gray whales do essentially this with their baleen - they eat giant mouthfuls of mud from the bottom of the sea and then let the mud particles and water out, keeping clams and worms.
[Answer]
There are real creatures which eat silt and sand to extract nutrients from tiny critters or dead organic matter mixed into it.
None of them (Edit: with the exception of baleen whales, which just recruit their existing water expulsion system to carry along sand and silt as well) bother with mechanically filtering out the sand. They just allow the inert, non-digestible sand to pass through the digestive system, like geological dietary fiber, and poop it out.
Depending on the precise nature of the sand, this may have very little or quite a lot of effect on the digestive system. For example, creatures which eat a lot of carbonate sand tend to lose their stomachs--the oesophagus just leads directly to an intestine, 'cause the minerals they inject would just neutralize any stomach acid anyway.
[Answer]
First things first: what do you mean by a flap? if you mean an opening, is it pulled taut? Though to me that would make sense, it wouldn't fit the definition of a flap. Is it fixed or is it movable via muscle, tendon, or other means? Is it opposable? Can the animal control the flap? Is it pure instinct or somewhere in between like breathing?
Another thing: the idea of a filter is, to put it lightly, an absurd notion. Water filters need to be replaced regularly to function correctly so an organic one would likely be useless within less than a year, not to mention the likely emergence of infections in the organism.
Though I will give you the benefit of the doubt and, rather than a pored mesh, it is a more colander-like organ that acts like a sift. If we ignore the fact that it would be inevitable that some stone would pass through the throat, as I'm assuming it's swallowing mouthfuls, and depending on the size of the animal to survive on a purely insectoid diet it would need to eat almost constantly.
Finally, according to the idea of the evolutionary arms race, the insectoid animals would gradually get closer to the size of the stone in their area and would become undetectable to the animal's organ.
This is not the final word, nor does it dismiss the interesting aspects but these are the things that came to my mind (in the realm of issues).
] |
[Question]
[
I ask this because I’ve been looking at alien designs for inspiration and on rare occasions found peculiar bone structures. The hexagonal rib cage in particular intrigues me. We know for one that honeycombs are the optimal shape for storage and are quite sturdy due to their geometry. What’s interesting is that they form from circles squished together. Even foam bubbles take this shape when close together so theres no issue growing bones in this way.
[](https://i.stack.imgur.com/mUKrR.png)
*Here’s an example, just focus on the ribs and ignore the rest. (Though it looks pretty rad.)*
**Would this be more or less viable than regular ribs? In what context would hexagon ribs be better?**
Depending on the size of the openings it may endanger vital organs, although our ribs aren’t full proof either. The interconnected ribs would also change the way the aliens breathe.
I’m curious to see what your thoughts are on the subject.
[Answer]
**Ladder ribs**
Pros:
1. Vertical and horizontal Flexibility.
2. Expansion space and elasticity for lung-like organs.
3. The breaking of a single rib piece will not affect the other ribs too much.
4. Bow-like shape allows more compressive stresses before breaking.
5. Rib cage can be compressed to decrease space between ribs and increase organ protection.
6. Easier to mend should it break, requiring at most two connective points to be stabilized and maintained.
Cons:
1. Two-point connection system makes disconnect from skeleton more likely.
2. Lateral slashes or penetrative attacks can slide past ribs and into organs.
3. Overpowering the rib connections from the outside via blunt means can make the ribs break and stab inward and puncture the organs they're meant to protect
**Hexa ribs**
Pros:
1. Greater structural integrity from all stress sources and directions
2. Greater protection for vital organs from both slashes and blunt impacts.
3. Rib breakage is less likely to damage internal organs due to force distribution lessening kinetic energy imparted into one spot
Cons:
1. Inflexible. Amount of inflexibility may vary from hard bone to cartilage, but the inflexibility will remain an issue and may impact breathing.
2. Harder to mend should it break. Requiring anything from two to six connective points to stabilize and maintain.
3. Organ protection is static. Protective range cannot be altered to further protectiveness by movements of rib owner.
4. Penetrative attacks will slide past these ribs like it's nobody's business, unless the attack happened to get stuck on the zenith of a bone which is relatively unlikely.
As for the circumstances that would lead to such ribs, I can imagine either mobile plant-like or insectoid lifeforms getting such ribs due to their breathing essentially being different as well as their structural stability requirements being less necessary to be flexible.
[Answer]
A rib cage has to protect the lungs AND allow them to expand and contract during respiration.
As you state, hexagonal cells make for a sturdy structure, which seems the wrong choice for something which has to regularly yield to the movements of the underlying structures.
The only way I see this making any biological sense is when the lungs do not operate in a alternated flow scenario (breath in - breath out) but under a continuous flow, like they do in fish gills, for example. In that case a sturdy structure doesn't prevent breathing and would actually save weight, giving same resistance for less mass. So it would make sense for a flying creature.
[Answer]
Just a different evolutionary history. ribs evolved in fish that were dorsally segmented had to flex side to side, so they are separate.
For an alien with a different evolutionary history a rigid chest might be fine, and thus hexagonal is workable.
Just give them something like bird or turtle breathing mechanism and the ribcage can be completely rigid.
[Answer]
Advantages:
* sturdier under continuous load, by distributing it more evenly
* less mass
* more opportunities for muscle insertion points that can distribute the load even better or allow faster reactions to changing the direction of movement (stronger support for jerky accelerations)
Disadvantages:
* no flexibility - place the lungs elsewhere or operate them only along the cage axis ([diaphragmatic breathing](https://www.health.harvard.edu/healthbeat/learning-diaphragmatic-breathing) - not a bad thing by itself, but it will reduce the maximal lung capacity.
* somehow brittle - if you crack one or two of the segments, the load imbalance is going to create a cascade failure
* that muscles criss-cross and thoracic cage? It spells nightmare for a surgeon trying to close after an open heart surgery.
Use whenever the mobility and reaction time of torso and arms movement is a premium. May be useful for *that* sport featuring scrummage too.
[Answer]
## It's Foundational for Protective Armor
A turtle's shell ***is*** its rib cage. The bones have changed their shape to become a shell.
But what if the shell experiences significant wear? Re-growing bone is biologically expensive.
Then you could make the shell out of something like keratin (of finger nails, rhino horn, etc.) or of a bone-cartilage material like antlers. These materials are tough, but not as expensive for the body as normal bone.
In a world where creatures need to be armored, and that armor needs to wear significantly, those creatures would want strong mount points for their armor. Deer and rhino use their skulls, which are seriously strong bones.
So your creatures use the strong, hexagonal, ribs to support their heavy keratin shells.
[Answer]
It's your world, justify it however you please ;)
If you want a semblance of 'reality' about it, bear in mind that evolution doesn't try to solve problems; it tests to see how well a random mutation works. If said mutation doesn't kill you, it might get passed on to the next generation (it can get passed on even it it does kill you, but only after you've procreated).
So, as long as you can explain how any given set of mutations haven't lead to the death of the species you can do whatever you like.
Having said that, here's a thought on how you could get your desired rib structure:
It is an ancient bit of body plan from when the proto worms were sessile sea dwellers (think sea cucumber with tubular armour). Over time things get attached to this rigid tubular trunk, like fins, legs, tentacles and eyes. It does need to flex for breathing since the beastie has adapted its gill to continuously suck air though the hole in its head and 'blow it out its ass' ;)
] |
[Question]
[
A science-fiction portal has been set up between Earth and the Moon. It uses a fold in space, so travel through the portal is effectively instantaneous. Initially there is an airlock to prevent Earth's atmosphere rushing through. Explorers and colonists move back and forth through the airlock.
Now comes the time for superfast terraforming. The plan is to open the portal completely, thus allowing Earth's atmosphere to rush through and provide an atmosphere for the Moon. Another portal from the Ocean gives a similar effect to provide huge crater lakes on the Moon.
**Question**
Suppose we wait until the air pressure equalises and an airlock is no longer needed. Will the change in Earth's atmosphere be noticeable for the average person sufficiently to change daily life?
**Note**
I have tagged both science and science-fiction. This is deliberate. The SciFi relates to the portal. The science relates to the real-life effects of such a portal were it possible.
**Assumptions**
1. Assume that the Moon will retain its new atmosphere for thousands of years at least. There are calculations that suggest this is possible but I want to assume it for now.
2. The portal opens directly onto the Moon's surface, not into domes.
3. The portals are 10 meters in diameter.
4. Please ask for clarifications before answering.
[Answer]
>
> Will the change in Earth's atmosphere be noticeable for the average person sufficiently to change daily life?
>
>
>
Hooo boy, yes. People living at high altitude will have to move downhill or die. People with respiratory issues at sea level might die too. Aerobic physical activities that used to be easy, or at least possible, will become extremely challenging. Lots of animals will be in trouble. High-flying birds will die or be geographically isolated due to problems with migration routes. Aircraft will have to change flight levels. The litany of terrible effects goes on on and on!
In short, your idea is terrible and awful, and is a nice example of how difficult and wasteful trying to make an entire atmosphere on a planet is. Get you some sensible paraterraforming plans instead... it'll be easy to fill up some nice giant domed settlements on the Moon and barely make a dent in Earth's atmosphere.
---
Right, loosely speaking, the surface pressure of an atmosphere is the weight of the atmosphere divided by the area of the planet: $P\_0 = \frac{M\_0g\_e}{A\_e}$ where $P\_0$ i sthe initial average surface pressure on Earth, $M\_0$ is the mass of Earth's atmosphere, $g\_e$ is the surface gravity on Earth and $A\_e$ is the area of the Earth. When you've linked the two bodies and waited for the pressure to equalise, you end up with
$$
\begin{align}
\frac{M\_mg\_m}{A\_m} &= \frac{M\_eg\_e}{A\_e}\\
M\_0 &= M\_m + M\_e
\end{align}
$$
where $M\_e$ is the new mass of Earth's atmosphere, and everything with a subscript $\_m$ is the equivalent value of the moon.
With a bit of re-arranging, we get
$$\frac{M\_m}{M\_e} = \frac{A\_mg\_e}{A\_eg\_m}$$
which gives a mass ratio of 0.45. To find out how much of the total mass of air each body has, you need to solve a simple equation:
$$
\begin{align}
\frac{M\_m}{M\_e} &= 0.45\\
M\_m &= 0.45M\_e\\
M\_m + M\_e &= M\_0\\
0.45M\_e + M\_e &= M\_0\\
M\_e &= \frac{M\_0}{1.45}\\
\end{align}
$$
where $M\_0$ is the total mass of air shared between the two, and the original mass of air on Earth before equalisation.
The Earth therefor has **69%** of what it used to have and the moon has the remaining **31%**. ... you need to throw a lot of air into that shallow gravity well to get enough pressure, even with such a small surface area!
You end up with an average surface pressure on Earth of ~700hPa, which is approximately the atmospheric pressure at 3025m on pre-catastrophe Earth. So not fatal, but as anyone who has spent time at altitude will tell you, you can feel it.
[Answer]
As others have noted, it would take way too much air from Earth to provide it to the Moon at the same pressure.
Earth has 5.5 quadrillion tons of atmosphere, and Luna needs 1.7 quadrillion tons to have the same pressure.
Now, Earth's oceans come to 1.4 \* 10^21 kg; if you drained 0.1% of them, you'd have enough mass to provide an atmosphere to Luna. Of course this is too much O2.
The interesting thing is that what we need to breathe is mostly O2; we can handle a lower pressure pretty well, so long as the partial pressure of O2 was correct.
21 percent of Earth's atmosphere is oxygen, which means we need 0.36 quadrillion tonnes of O2, which could be harvested from about 0.02% of Earth's oceans.
You do need a place to store all of the Hydrogen; there is a **lot** of it. Also, note that the reaction of Luna's surface to H2O and O2 (and maybe N2, but less likely) and the like will be pretty violent (O2 is really corrosive, we only don't notice because everything on the surface of the Earth is highly resistant to it due to being exposed to it for a long time).
---
So the plan would be to first pump water onto the moon. Then engage in ridiculous amounts of cracking to get the H2 out of the H2O, and bind that H2 to *something*. After consuming 0.02% of Earths oceans this way, you'll have enough O2 on the moon so that an open atmospheric portal won't suffocate everyone.
Having the correct partial pressure isn't quite right, and you'll probably want to mass produce some more CO2 for the poor plants, and maybe the nitrogen cycle will get messed up somehow...
But you can't geoengineer a planet without breaking a few species.
[Answer]
The moon is tidally locked to Earth so the laws of thermodynamics will rain on your parade.
Lets assume your portals are giant sized and they successfully transfer air and water to the Moons surface at a rate that is greater than the boil off rate. 'Behold' you now have an atmosphere - at least for a short while anyway until it leaches away. But you problems are just beginning.
The side of the moon facing the Earth receives more sunlight (via reflection of the Earth) than the dark side does. That means it will always be warmer than the dark side. (Or alternately the dark side will always be colder.) Either way the laws of thermodynamics mean that the atmosphere will try to redistribute (even out) the heat differential by circulating hot air from the day side to the dark side and cold air back the other way. The result will be cyclonic level winds - although this may be partly ameliorated by the lower atmospheric pressure (continually lowering atmospheric pressure really as all the air leaches away day in, day out).
Upshot - your new moon will be very,very windy. Think living in storm level winds permanently.
] |
[Question]
[
So, I am modding a game where the distance in pixels between star systems DOES matter on how the game calculate stuff.
We currently have a cool looking sub-way style map, with a lot of things in arbitrary places and shapes, unfortunately this caused a lot of gameplay bugs.
So I was looking around for examples of star maps, and noticed all of them, anime, movies, games, etc... is a variant of "bright dot to represent a system on a black BG".
So how someone would make a map of the stars? Even better, how someone can make a map that someone in-universe would use, for maximum immersion?
Most people can't think in 3D, so what kind of maps would represent in 2D, distances (in time, our setting has wormholes for FTL, thus NOT actual distance between stars) in a way that people would understand, and be useful in a military manner?
[Answer]
You say that:
>
> We currently have a cool looking sub-way style map, with a lot of things in arbitrary places and shapes, unfortunately this caused a lot of gameplay bugs.
>
>
>
But in the comments, you say:
>
> The artist assumed that the distance didn't matter, and so he used whatever looked better, giving arbitrary sizes and distances to things.
>
>
>
You could work on fixing that specifically. A good example I like is the map of Δv's for [KSP](https://wiki.kerbalspaceprogram.com/wiki/Main_Page):
[](https://i.stack.imgur.com/x5yk6.jpg)
source: <https://wiki.kerbalspaceprogram.com/wiki/Cheat_sheet>
The size of each "leg" of a path is not to scale, but they have numbers printed on them showing the actual Δv you need to go from one point to another. You could improve on it by making the legs to scale.
---
An alternate form is that of a grid. I've seen it in numerous board games, and in attempts to map the galaxy for Star Wars and other sci-fi franchises. The one below is for [Elite Dangerous](https://en.wikipedia.org/wiki/Elite_Dangerous):
[](https://i.stack.imgur.com/iGQJV.jpg)
Source: <https://www.reddit.com/r/EliteDangerous/comments/9ppcpg/high_res_map_of_the_new_galactic_grid_chapter_4/>
If you are not going to explore the full galaxy, you can zoom in your map to only a part of it. With a grid representation, it is also simple to represent wormhole connections.
[Answer]
There isn't any mapping from 3D to 2D that will preserve pairwise distances between all points. Using time as a measure doesn't fundamentally change anything about the problem, since instead of "distance" being measured in km/AU/lightyears, it's instead measured in hours/days/years - but you still just have a series of pairwise distances between points.
You could make a locally oriented map that accurately shows distances from your current location (A) to any other location (B or C). But this type of 2D map would *not* accurately represent the distance between B and C.
Because you cannot map directly from 3D to 2D and preserve distances, a subway-style abstraction might actually be just what you need. You simply label the subway "legs" with the true 3D distance between points, since you cannot measure the legs on the 2D subway map and get an accurate value. One just needs to be aware that there will be distances that are not reflected in the visual representation of the subway map - some points that appear close together might actually be far apart, and some points that appear far apart might actually be close together.
Note that this distortion is *exactly the point* of a subway map - it purposefully distorts distances in order to have a more visually pleasing layout. There's no reason you couldn't draw a map of the London Tube that perfectly represents the pairwise distances between all stations (it would just be a regular map), but that is antithetical to the whole impetus for the subway map in the first place. For the star map, you can't perfectly represent the distance in 2D, but you can still try to organize it in a way that minimizes distortions.
It's the job of the mapmaker to choose the representation to minimize that visual disparity, and to put those visually discordant distances in less important or less traveled legs. You can take advantage of natural "projection planes" to minimize distortions, leveraging the knowledge that galaxies and solar systems tend to be much wider than they are thick - projecting a galaxy top-down along its axis of rotation will only lose a fraction of that pairwise distance information (the projection distance is a good approximation of the 3D distance). An edge-on projection, on the other hand, would lose a great deal of that information.
[Answer]
**Use an actual map.**
[](https://i.stack.imgur.com/rFoz4.jpg)
I found this here: <https://www.distantias.com/distances-from-frankfurt_am_main-germany-to-capital-cities.htm#map2>
You plug in your city and it will show you distances to nearby cities. This has many benefits.
1: You can center your map wherever you like. I can use this same website and put Vienna in the center, or Kyoto. You can have a map for each star in your game with that star at the center.
2: The distances are real distances and so you don't need to remember them. You can check.
3: Yes, they are actually stars. You are not flying your spaceship among the canals of Amsterdam. The in game story is that this representation worked in world for your star charters and it was easy to remember. Plus instead of long numbers this automatically gives stars names: the Amsterdam system; the Kyoto system etc.
4: There are a lot of cities if you need them. Not as many as there are stars, though.
[Answer]
You can use color to add more spatial dimensions to points that you're plotting. The map would be read by taking in to account both the distance between stars in 2D and the difference in their colors. I can think of some ways to do this:
* Making it look like the stars are in a fog, so that farther stars have more of the background color than nearer stars.
* Making it look like the +z stars are white hot, cooling down to red hot -z stars.
* Use hue.
This would extend up to 6 dimensions, if you wanted (RGB + XYZ in 3D), but your application could use one gradient scale (one dimension of color), combined with two dimensions of space, to displace points in three dimensions.
[Answer]
# This is a minimisation problem on a graph
From your description, you have a set of stars which are connected by an arbitrary network of wormholes, each of which can be assigned some 'distance'. You want a two-dimensional representation of this universe (i.e. a map) which is close to accurately representing the distances.
The natural way to draw this map is as a [graph](https://en.wikipedia.org/wiki/Graph_(discrete_mathematics)), which is a set of nodes (your stars) connected by edges (your wormholes). When turning this into a map, usually a subway-style map is created, because train networks are very similar in being a set of nodes (stations) connected by edges (train lines). This point is covered in [Nuclear Wang's](https://worldbuilding.stackexchange.com/a/181753/55824) and [Renan's](https://worldbuilding.stackexchange.com/a/181759/55824) answers.
If you only need a single map created manually and you only require the distances to be approximately accurate, you could do this by hand (employing appropriate graph-drawing software to make the task easier, so you can drag around nodes until everything looks right, or better yet have it automatically place the nodes). A benefit of doing it by hand is that you can handle outliers in an intuitive manner (e.g. if you have shortcuts which cut through an otherwise well-behaved network of wormholes).
If the location of the stars can be mapped to regular space and the distance of the wormholes is simply proportional to distance, it would be easiest drawing the stars where they are in real space. This is simple and intuitive, although requires either compromise or creativity if there is a significant 3D component.
For the generic problem, where you have an arbitrary collection of stars connected in an arbitrary manner by wormholes of arbitrary length, your task becomes an optimisation problem in representing this graph. You may need to be able to construct this graph automatically (such as for randomly generated maps). For this we invoke some mathematics. Details of implementing such algorithms are beyond the scope of this site and should be asked elsewhere.
We have a set of distances $\{r\_{ij}\}$ between stars, where $r\_{ij}$ is the distance between stars $i$ and $j$. Your list of distances might only include explicit wormhole connections. Or you might like to include all pair-wise distances (so that the distances in your map are accurate even for stars not directly connected), in which case you would need to step through your graph one node at a time, building up [distance matrix](https://en.wikipedia.org/wiki/Distance_matrix).
(If the 'true' distances between two stars needs to be referred to often, you probably want to keep this distance matrix for use throughout the game and rely on it rather than checking points on the map.)
We want to find the coordinates $\{(x\_i,y\_i)\}$ of each of the stars in two-dimensional Euclidean space (that is, we want to determine where on the screen to draw them). And we want to find them in such a manner that minimises (in some way) the difference between the desired distance $r\_{ij}$ and the drawn distance $\sqrt{(x\_i-x\_j)^2 + (y\_i-y\_j)^2}$.
Perhaps the simplest way (but not the only way) to frame this minimisation problem is with [non-linear least squares](https://en.wikipedia.org/wiki/Non-linear_least_squares). We can avoid awkward square roots by squaring the distances. Then we can minimise the sum of the squares of the differences between the target and actual distances,
$$
S = \sum\_{\{(i,j)\}} \left( (x\_i-x\_j)^2 + (y\_i-y\_j)^2 - r\_{ij}^2 \right)^2,
$$
where the sum is taken over pairs of $i$ and $j$ for which you have defined $r\_{ij}$. We then minimise $S$ with respect to $\{(x\_i,y\_i)\}$. How you do this is beyond the scope of this question, although it is a well-studied problem and there are places elsewhere on the Stack Exchange network which will answer how to do this.
Once you have the coordinates $\{(x\_i,y\_i)\}$, you then get the computer to draw your stars at those points then draw wormholes between the appropriate stars.
You can add extra sophistication to $S$. For instance, you may consider that the more wormhole jumps there are between two stars the less important it is for the distance to be very accurate, so you might apply a weight to each term in the sum to indicate their relative importance. Or you might like to avoid drawing wormholes crossing each other, in which case you can add a penalty function which increases $S$ if two wormholes cross.
While you could write your own code from scratch to draw your star map, graph visualisation is an old problem. There already exists many [graph drawing software packages](https://en.wikipedia.org/wiki/Category:Graph_drawing_software) which handles a lot of the problems of creating aesthetically pleasing graphs. You will have to check which ones suit you, since some may not handle hundreds of nodes and some require you to pay. You also want to be able to take the output from the graph visualisation software and insert it into your game graphics engine. Although I have not tried it, a cursory glance through search results indicates that [graphviz](https://graphviz.org/about/) might be appropriate, since it is open source and implements algorithms which optimise the graph layout for the types of graphs you want. But check yourself if it meets your needs.
Note that, in general, it will not be possible to get the distances on the map to perfectly align to the 'real' distances. If your graph is very complicated, then it might not be possible to get even close to an accurate representation. There are two solutions here. One is to discard the old arbitrary wormhole lengths and instead re-write the wormholes to have a length equal to their length on the map. The other is to write the wormhole lengths as numbers on the map (as in [Renan's answer](https://worldbuilding.stackexchange.com/a/181759/55824)); the people (or computer) reading the map can accept that scale is approximate but rely on the written numbers being exact.
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You also ask about how people would represent these maps in-universe.
If the arrangement of wormholes is not expected to change during the lifetime of the map, then the map would likely be created in a similar manner to what I have described above. Software exists for converting graphs into pictures, and depending on the purpose and size of the map it can be partially or wholly designed manually.
Such maps are useful for transportation and travel, like our subway maps. Train lines rarely change, so the map does not have to be updated too often. Train lines also correspond to physical space, so when a new train line is added the map only has to change a little bit to accommodate the new train line.
These maps would also have military applications. Logistics is a big part of war. You want to be able to see what territory each faction controls, how spread out it is, how far it is from your own, how long it would take to get between two points, etc. While quantitatively accurate results will require calculations, a well-designed map will allow for the essential data to be intuitively grasped. For a well-behaved graph, the distances on the map may even be decent approximations for the fully accurate numbers.
You mention in a comment that the wormholes do not change throughout the course of a game. This means the aforementioned map is useful.
However, there is likely a timescale on which wormholes are created or destroyed or moved. Unless the 'distance' of a wormhole is roughly proportional to the real-space distance, creating new wormholes is likely to radically alter and invalidate a graph-based map.
Astronomical and surveyor maps will be of this type which must remain relatively unchanged despite the layout of wormholes. Such maps will try to represent the positions of stars in real space. Wormholes will be drawn as lines between stars without respecting the 'length' of the wormhole. How to draw points in 3D space on a 2D map is its own problem. The data of star positions would be stored as a list of 3D points and it will be up to each mapper to determine how to project that data onto 2D (such as [Retracted's answer](https://worldbuilding.stackexchange.com/a/182797/55824)). Or they could use 3D graphics, holograms, virtual reality or augmented reality to display the data in 3D.
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[Question]
[
This is something that confuses me with amorphous characters, monsters, robots etc... How do they compute when their particles don't have a fixed form? They are in a sense modular robots only taken to an extreme in size and number. Such a robot can freely transform, reassemble and other things. Take the T-1000 from Terminator Judgement Day. It can be blown to bits and always reform, that part is clear. What isn't clear is how it maintains memory and neural connections with such a makeup. Sure you can say that they do it wirelessly, but wouldn't there be too much interference and background noise?
This is somewhat addressed in the science newsjournal
>
> "These soft circuit systems will act more like live cells,
> communicating with each other to form new circuits and moving around
> autonomously."
>
>
>
Basically recreating an organic brain, but if a Grey Goo robot were to be blown to bits it would lose its memory. If a Grey Goo robot were to have a computer ship inside it controlling it that could not be reformed. Many questions worth addressing.
[](https://i.stack.imgur.com/uOaZy.jpg)
If there was a way to make this more realistic by giving rules to the robots makeup it would be a big help, since I don't like handwaving everything into the story. The technological requirements as a advanced as necessary, since this is a very futuristic invention. And yes, the point of this robot is to reform if damaged, otherwise any other robot would do the trick.
[Answer]
**Disclaimer**
As you imply, the oft-depicted amorphous grey goo robot doesn't make all that much sense.
Humans and animals are made of nano-robots. But we still have bones, brains and livers. We are not a homogeneous mass.
The "grey-goo robot" is a hybrid of two (probably) scientifically incompatible concepts. The "grey goo" scenario, which is a semi-realistic idea that some kind of self-replicating sludge could grow out of control and start eating everything. (Note that in the most realistic versions the sludge can't actually do anything apart from spread like a algae, not much moving or anything). This idea is "bolted on" to a robot to make the typically imaged slime-monster.
**Answer**
But the slime-monster is cool. How to we justify it in a story that tries to play some kind of lip-service to scientific realism?
Several ideas occur:
1) The mind is located "off-site", and wirelessly puppets the body. In this case the best way of defeating the invincible monster is likely to interrupt or hack the signal. We will gloss over how it moves so well.
2) If a very high level of individual programming is assumed on each "cell" of the machine then the mind could just be distributed between them. Not at all like a human mind (where the neurons are made of cells), more like a computer network with tens/hundreds/thousands/millions of "neurons" in each cell. This requires some kind of futuristic sub-atomic tech (shrink-rays or something).
3) Very resilient cells, in a very floppy body. When the thing gets hit (or shot or whatever) the damage that the individual cells take is controlled not just by how hard the hit and how strong the cells, but also by how strongly they are held in place. Its the difference between punching through a piece of paper that is held in a frame, and one that is falling through the air. If the slime-bot was very "floppy" (liquid) then attacks against it would (at a large scale) appear to have quite a dramatic effect. However that same floppyness means that the microscopic components of the robot are likely barely being damaged at all.
[Answer]
Mixing the right amount of techno-babble and science, consider that in a neural network the output of the network depends on its layers, but do not change if you swap the neurons, which individually perform the same operations. What changes is the input/output of each neuron according to its position in the network.
Your "fixed form" equals the "fixed position", while being fluid your goo is capable of changing the position of the neurons while keeping the network architecture the same.
[Answer]
**Modular computing, and flexible multipurpose components**
First point to consider is that a computing task can be broken down into very small elements, and the physical location of those elements doesn't actually matter if their inputs and results can be routed to where they are going.
Think about how simple transistors make up an actual computer. Those are fixed in place, take inputs from one part, and their outputs link to another area. In modern computers those are all laid out on tightly packed chips. On older computers those could individual chips laid out on a board and connected with traces that you could see with your naked eye.
But what if those traces on a board were replaced with flexible wires? Then you could move and rearrange the transistors, to a limited degree at least, and the computer would continue to function exactly the same.
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If we expand that into our grey-goo computer, consider if each component could reconfigure itself to meet whatever role it currently needs, or move itself to where other components need it to be.
Two 'cells' who need to communicate move apart?
* Throw an error and have a cell configured as a connector come in to fill the gap.
* Or, throw a different error, have one of the 'compute cells' move back closer to the other, can call for a different cell to take its old place.
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Clusters of cells form 'compute-groups', tasked with solving some specific kind of data processing, and all compute-groups act as flexible controllers.
As long as enough cells remain as part of a compute-group that stores the core command and control concepts, then they can always issue directions to form any other compute-group that the colony requires to function.
So even if you blast away chunk of cells and disrupt local calculations and data, the rest of the pile will maintain enough computing networks and groups to recalculate, reform, and move on.
[Answer]
We already have self-forming microbot swarms in the laboratory. If you continue the micro-miniaturisation, or simply posit self-healing synapse systems, that should take care of your organic (or amorphous) greygoo.
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It might be worth adding that when dealing with a technology level that assumes nano-scale replicators working in tandem, having any kind of a "microchip" as part of the body would be comparable to fueling a space craft with a wood stove. I don't think such a robot would have any identifiable control chip. If the nanobots that constitute this robot have enough self-contained energy and programming not to need external batteries or info storage, they likely do not need a discrete control module, either. All programming redundancy, energy sufficiency, and control mechanisms would fall to the greygoo itself. If, hiding in all that goo, there were boxy, large components swimming around and dodging shotgun blasts, the robot wouldn't be as amorphous or as resilient as it is. Might seem crazy, but you know what they say. Any technology, sufficiently advanced, is indistinguishable from magic.
[Answer]
The human brain already deals fairly well with adapting to losing surprisingly large chunks of itself.
It seems reasonable that a structure capable of re-aligning could do just fine assuming it didn't have anything else too complicated to think about while it was reforming the bits it needed for higher-order processing.
A housefly's brain is really small, but it's more than capable of responding appropriately to danger - You don't need much raw mass to provide enough intelligence to make decent decisions in clutch situations.
Even if the goo is completely disintegrated into tiny bits where no one bit is bigger than a houseflies brain, it can still eventually regain cognition by simply re-organizing it's structure. You'd inevitably lose data in this scenario, but surely any piece of grey goo large enough to do something interesting has a method of sharing information with the larger network wirelessly.
The real hand-wavy assumption bit comes in where you're talking about the manner in which the cognitive network maintains self-integrity during it's destruction and reconstruction - but it doesn't actually need to! Why would a pile of grey goo need to maintain a consistent linear concept of self-history? That sounds like a crutch. As long as, collectively, the entirety of all grey goo everywhere maintains some record of significant events it more or less agrees on within a certain margin of error, it can keep making rational decisions based on those events, regardless of the individual experiences of any cluster of cells that make up a "individual machine."
[Answer]
There are two major aspects: Computing and memory.
I'll forego the outer appearance, mostly, and just assume that the body consists of a swarm of cells that are capable of:
* Executing minor computations
* Storing small amounts of data
* Communicating over short distances (let's say a few cm), relaying messages. A larger group can group together to communicate over larger distances.
* Identifying by ID
Cells can be classified via ID. To prevent vast storage of IDs for each individual cell of a specific class, a pattern is used, depending on the amount of cells. For large amounts of cells, for example, "every cell with an even ID" would do it.
**Computing**
Computing is done in modular blocks. A small group of cells forms a processing block, multiple processing blocks can join together for more complex processing.
Computing "foremen" cells take care of this: A foreman cell announces creation of a computing block, searches for cells closeby and creates a computing block with them while informing other cells about this action. Foremen cells would primarily save computer architecture.
Since the computing blocks can move freely in the mass of cells, disintegrate and reintegrate at will, communicate with other computing blocks, replace each other, be redundant and so on, it's easy for the swarm entity change shape, move through obstacles like prison bars, ignore bullets and so on - the computing blocks will replace each other or shift in place.
**Memory**
Every cell has its own memory unit, assume it's a few kb. In the whole swarm entity, memory is stored and accessed redundantly (by pattern) - basically a computing block can say "I require the data of a cell that is a multiple of X" and any of said cells can answer or relay the question. This enables information to be stored safely even if some cells get lost. Priority information is stored in more frequent patterns, less important situation in less frequent patterns - so critical information such as the system's OS won't get lost easily while random information MIGHT get lost when a significant amount of cells is damaged, but it is still unlikely. Like the processing blocks, storage blocks could be created as well to increase storage read/write speeds.
And... that's about it. You now have a cell swarm entity that can compute things and store things, so it can work and act arbitrarily well. It can also be split up, voluntarily or not, and reassemble. In emergency situations, where it is split up into many small groups and a vast amount of cells is unavailable, it can still grow together to smaller blocks, for a processing unit, call for the most redundant memory cells and start reassembling from there - it would be smaller, weaker, have less computing power and lose low-priority memory, but it would still work.
[Answer]
Each bot must be quite a bit smarter than we can make them today. Not nearly human-smart but, say, ant-smart. So, we have trillions of well-organized "ants".
The things the whole organism knows must be divided into small "facts" that can be stored in single ants. Each ant should be able to handle maybe a hundred facts and reason about them.
Important facts are stored in millions of ants, less important facts in just a few hundred. Losing some ants really doesn't matter.
At any given time, decision-making is located in a brain-like structure consisting of a number of ants close together. If these are scattered the organism will be confused and operating on very basic instincts until a new brain is organized. It may consist of any ants, not necessarily the same as earlier.
There is a many points here where we don't know how to do this yet, but nothing fundamentally impossible.
[Answer]
## Computing is the EASIEST part of the Grey Goo Monster
We already have amorphous, distributed computing - it's called the internet, and it seems to work ok.
Computers don't need to know where other computers are in the **physical** world, they need to know where other computers are in the **logical** world. Generally, we use IP addresses to achieve this. There is a whole complex world of how we get messages from one IP address to another, involving various protocols and physical hardware.
## Self Assembling Routers
Nanobots could talk to each other using the low level protocols, and if they detect that no router is present to connect them to the other bots, they spontaneously decide to make a router using the local bots, and then seek a wider connection.
## The Real Challenges
For this to work, each grey goo bot needs to have an onboard processor, wireless or wired connectivity, and some sort of power source to move all those electrons around. **ALL** of those things are **borderline impossible** at the scale that grey goo implies.
## Working with the Challenges
If I were working on a grey goo story, I'd probably look at what kinds of restrictions those challenges would place on my goo.
Processing power - If I isolate the nanobots from each other, do they become dumb enough that they can no longer function?
Power Source - Do the nanobots require constant exposure to some field (microwaves, X-rays, whatever) to power themselves, so putting them in a Faraday cage kills them?
There's lots of ways to work within the challenges to make interesting scenarios.
[Answer]
Maybe redundancy...the "memory" or state of the machine is represented in a distributed and redundant form, so in order to destroy it, you must destroy it completely, or at least more than a certain fraction (such fraction to be determined through plot points). That adds a certain twist to combat; just "aim for the head" doesn't work anymore, you need to go for a specific amount of carnage. (Maybe progressive? 80% damage destroys, but 50% damage just messes up some childhood memories?)
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[Question]
[
The [whomping willow](https://harrypotter.fandom.com/wiki/Whomping_Willow) is a fictional tree from the Harry Potter series of books. It is a magic willow that can move its branches to punch people who come close to it.
[](https://i.stack.imgur.com/hLapk.gif)
Small animals such as cats and rats can approach without much worry; Anything human-sized or larger gets whacked. As for how strongly it can punch, one of the books has this quote in it:
>
> *"People used to play a game, trying to get near enough to touch the trunk. In the end, a boy called Davey Gudgeon nearly lost an eye, and we were forbidden to go near it."*
>
>
> —Remus Lupin
>
>
>
It also has a small knot near the base. Pressing it causes the tree to become immobilised, at least for a few moments, so it is safe to stay close to it. I don't think the books ever mention how long that lasts.
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What I would like to know is the closest thing to that we could have, in a fictional world, without magic (hence the [science-based](/questions/tagged/science-based "show questions tagged 'science-based'") tag). Doesn't have to be a plant per se: it can be a fungus or anemone. It just needs to be a living, sessile thing.
[Answer]
## Supersized land anemones
Meet the **swimming sea anemone:**
[](https://i.stack.imgur.com/v2bux.gif)
It's desperately avoiding the grasp of a nearby sea star, which is interesting but not what we're interested in. Rather, notice how it bends its ring of tentacles nearly all the way to the ground.
What if this wasn't a defensive mechanism, but rather an offensive one? Our supersized land anemones would remain quietly waiting until they detect prey pesky teenagers, either by touch or through the network of symbionts surrounding them. Once triggered, the entire crown of the tree, full of tentacles and the anemone's nematocysts, would smash down upon the prey.
### Considerations
It'll take a some handwaving to make this happen, but that's mainly to do with the transition of the anemone from sea to land. Anemones are supported by water pressure, so our land versions would only be found in the dampest areas such as swamps.
It's quite possible to imagine an anemone that ends up looking like a tree, especially if it's a strong evolutionary pressure. The stalk of the anemone might become tough, leathery and brown simply by drying out, giving a very bark-like texture. On land, zooxanthellae can be much more helpful given the higher intensity of sunlight, so they'd proliferate wildly. However, these symbionts are brown algae, so the tree canopy would remain a brownish golden color all year long
As for the prey size requirements, the anemone is unlikely to notice small organisms relative to tree height, and would therefore only trigger once a certain size threshold is exceeded. That just happens to be the size difference between small animals and humans.
## Supersized heliozoans
Heliozoans are a class of aquatic predators that look like underwater spikeballs:
[](https://i.stack.imgur.com/XyvnDm.jpg)
They act almost like underwater spiders, as they use those long, thin spines to catch prey, which are nearly invisible underwater. They're coated in a sticky substance that may have some paralyzing effects. They sit and wait for a prey item pesky teenagers to bump into a spine, at which point the spines actually retract with *incredible* speed- up to 2 body lengths per second. Prey Teenagers are then brought near to the cell body and digested.
Fortunately for us, some species already come with trunks!
[](https://i.stack.imgur.com/NlvaCm.jpg)
### Considerations
Again, these are aquatic creatures that don't like being suspended in the air. Fortunately, they also have a sporelike function that they'll use when food is scarce or the streams dry up. It's possible that such a heliozoan, once left in a dry streambed for long enough, will nonetheless try to feed. Realizing the vast amounts of food available, they'll be selected for size and eventually (with a tiny bit of handwaving) become the size of trees!
The same size-requirements apply here. The tree wouldn't worry about small things touching its bark or leaves, but instead would use its energy to deter larger creatures that might actually threaten it. The spines would be set on a large-size trigger where a certain length must be touched, or perhaps multiple spines in a short time window, akin to [the Venus flytrap triggers](https://asknature.org/strategy/leaves-rapidly-snap-shut/).
[Answer]
Mimosa pudica is well known for its peculiar feature of wrapping close its leaves when they are touched.
Expand this to branches, not only to leaves, and you have the moving ability: from the opened state they get retracted and can look like the return phase of a punch.
[Answer]
Thinking about it for a while I couldn't come up with any non-magical square-cube law defying way to create a plant capable of so much movement and intelligence.
But what if it's not just a plant, but a symbiotic creature?
This 'tree' would work more like a Stork. It stays still, acting like a part of the environment and when prey comes near it strikes to eat it. This tree might have a symbiotic relationship with a plant that does have deep roots. In times of scarcity like during winter the roots provide most of the food and energy, but in times of abundance the creature part of the tree gathers the most food. The roots can be allowed to grow through parts of the creature so that it can form leaves and use photosynthesis to support both. Additionally this tree creature could develop symbiosis with Ant's (<https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2688311/>), allowing the ants to help maintain it and feed it while the tree offers some services for the Ants like protection from birds and other things that might prey on Ants. This also means that the tree could eat things like fungi and other things the Ants could cultivate, and in times of need the creature could eat some of the Ants.
It has no eyes, limited intelligence, a thick layer of protective leather that imitates bark (Cuttlefish can do it and we don't need to change the color or texture afterwards! <https://youtu.be/pgDE2DOICuc>). So this tree only has to react to external imput, meaning it's like a giant bear in hybernation. Very fuel effecient when it's inactive.
What does it eat? We actually get an unintended hint at it in one of the movies: It eats birds mostly. Birds are the best prey for it. They actively seek out the tree for protection and rest so the tree only requires minimal movement to kill and eat the bird. It requires too much energy to slam itself on some small critter on the ground, a critter that is likely to flee before it. But something like a human... Now that is a large thing you can't pass up and will try to eat.
But what about that knob that immobilised the tree? I would actually scrap that from the tree, we know that the tree was placed to protect the entrance to the Shrieking Shack, and to get Remus Lupin to the hole he would have to expose himself to the tree each time. By adding this specific weak spot on the tree Remus's friends could deactivate it so Remus could enter safely. But if you really must have an explanation: it's where the tree stores things it's allergic to. Pushing on it causes it to be immobilised temporarily as a short allergic reaction. Since it's at the base of the tree it forces the tree upright, preventing it to attack anyone at it's base.
Tl,DR:
So in reality the tree is a muscular, large creature meant for short bursts of movement that just sits still and waits for prey all the time. It could have additional symbiotic relationships with some kind of roots and Ants if you wish.
[Answer]
I would combine aspects of two existing plants that are related to each other as closely as the Caryophyllales order.
Carnegiea gigantea (saguaro cactus) + Drosera regia (king sundew)
The Saguaro already grows to 'tree-size', without any modification at all. Though well short of what most willow species are capable of achieving, if left to grow naturally, the saguaro can easily reach sizes rivaling the GIF you used in your question, due to the pollarding done to the willow (pollarding is the repeated pruning of branches at the same place, to start new branch growth from that same area)
The king sundew provides the mobility, as it has leaves that can reach more than 2 feet long (giving it more than a 4 foot radius overall) which can coil and twist. It also provides (unexpectedly, considering its mobility) the woody aspect to the step of the overall organism. In an unmodified king sundew, this woody material is in it's stem which is generally entirely below surface level.
Combine the woody stem from the sundew, with the size of the cactus, and you have a woody trunk that is tree size. Add the mobility of the sundew's leaves to the 'arms' or 'branches' of the cactus, and you get the ability to swing in, effectively, any direction, with the woody material limiting movement progressively as you move from the tips of the leaves toward the branches and then to the trunk.
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So, a group of people have just been transported back to early 14th century England, and have angered a band of noble knights. Their armor looks like this.
One of my characters, Tim, received a hand grenade (which he was told was holy) and instead of using it against a certain rabbit, he plans on using it against the knight. Would the knight's armor protect him from the grenade enough that he would survive, or would he get killed?
[Answer]
Mail (that coat of metal rings he is wearing) is great at protecting its wearer from blunt trauma, such as that caused by swords, maces, and flails. It was relatively poor at protecting its wearer from the puncture wounds of high-velocity projectiles; this is why [the British longbow was such a deadly knight-killer](https://www.isegoria.net/2011/08/longbow-vs-armor/), and why [the spread of firearms caused iron armor to fall out of use](https://history.stackexchange.com/questions/33548/why-was-metal-armor-phased-out-after-gun-powder-was-weaponized).
So, while your mail-clad knight would be better off than a man wearing a shirt and trousers, one would still expect him to take fatal wounds from grenade shrapnel.
Plate armor would be more effective at protecting him from the grenade, but is unlikely to be sufficiently effective.
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As someone who has taken a piece of grenade shrapnel to the neck. Frag Grenade shrapnel looks like tiny egg cartons but metal. If it went off right next to them it would most likely take a few out. Only due to the actual explosion and being so close to the shrapnel going thru the armor it could. Which at that range would be most of it. at a distance of 15 feet it would stun probably make them fall but the shrapnel would not penetrate thicker metal. They are supposed to have casualty range of 15 meters. Kill at about 5. it would however go through fabric BUT i doubt it would penetrate a thick leather at more than 20 to 30 feet. Now this is only for a regular us army m67 frag grenade. The one that got me was about 75 meters and went into my unprotected neck about a 1/4 in. There are more effective grenades out there. Hope this helps.
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An offensive hand grenade produces mostly blast, a defensive grenade produces blast and fragments. Defensive grenades may have a greater danger radius than they can be thrown, so they are best used from trenches. Offensive grenades can be used by troops in the open, as long as they have strong arms.
* *Modern* defensive grenades are designed to produce many small, equal-sized fragments with good coverage and not too much range. Some are packed with small balls. *Older* defensive grenades might have uneven fragmentation with a few larger ones.
Such an older grenade might have a big fragment that punches through the helmet or the chainmail. Small pellets from a modern grenade could slip through the weave of chainmail.
* Depending on the proximity, the blast might have lethal effects as well.
You mentioned a character. Is he in a pen-and-paper roleplaying game? If so, take a look at "generic" games like [D20](https://tvtropes.org/pmwiki/pmwiki.php/TabletopGame/D20System) or [GURPS](https://tvtropes.org/pmwiki/pmwiki.php/TabletopGame/Gurps) and their rules. Even if you are using a different game, you can play through that one scenario, looking at best-case and worst-case die rolls.
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While shrapnel can be deadly, the most damage from a grenade comes from the pressure wave of the explosion. Depending on the type of grenade, the pressure wave will destroy anyone's lungs within a few dozen feet. Eardrums would burst, as well as soft tissue damage.
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It is conceivable that he could survive. He will be injured almost certainly no matter what. Other answers are correct that mail is not that good at dealing with piercing weapons. But it's not guaranteed to fail; it is possible for him to get lucky and have much of the shrapnel stopped by his mail. Especially if he isn't right next to the grenade when it goes off.
Further, any shrapnel that gets through the mail then also has to get through very thick padding. Nobody wore mail over bare skin, or even just light clothes. Whatever gets through both the mail and the padding then also must penetrate his flesh deep enough to cause a dangerous injury. Surface cuts and punctures will draw blood, but they won't take him out of the fight.
It's also conceivable that he could die. Shrapnel could go between the rings in his mail and puncture an organ. Or it could go in a gap somewhere, like the eye-slit of his helm. Or if he's very close to it he may suffer pulmonary edema from the pressure wave like Keltari said.
I think either outcome is believable, and you should decide which to go with based on what would be best for your plot.
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The Humern empire is vast, unbelievably powerful and (in certain matters) brutally authoritarian.
One such issue is that of reproduction. In order to ensure that all subjects of the Empire remain part of the same species all breeding must be done either by taking a randomly chosen fertilised egg from a Reproduction Center (random in that the egg is picked randomly from a bank of egg/sperm pairings carefully chosen to ensure forward and backward genetic compatibility) or by having the genes of yourself and your partner analysed to ensure you have a reasonable chance of producing compatible offspring (knowing your offspring may well be ‘incompatible’ and this never have children of their own).
Unless a subject goes down one of these two routes *they are sterile*. They are born sterile, live sterile and can only have sterility taken away at the discretion of the Empire. This is to prevent any breakaway faction or splinter groups being able to reproduce and split into a whole new species (and certainly not so the Empire has an iron grip on the family jewels of all of it’s colonies)
The question is how can such reversible sterility be woven into (for arguments sake) the human genetic code? It is still required that eggs and sperm be available to fill the Reproduction Centers, but the sterility must be status quo without intervention (ie removal of all eggs at birth is not an option as a rebel government might choose to stop doing it)
Answers will be ranked by how biologically complex the changes are, how hard the ‘reversal’ is without proper authorisation, and how low the chance of pregnancy becomes (because it will never be bang on 0, but rebels shouldn’t be able to breed without insane levels of luck).
Details on the biological cause of the sterility *are* required, even if they’re just an overview. More detail is, in my view, a better answer, but I understand the complexity here (I’m not asking for which proteins need editing, just methods by which this kind of sterility could be effected).
Bonus points: if the changes can be applied to an otherwise healthy human population by means of a retrovirus. Not that the subjects of the Empire won’t willingly submit to such a draconian measure, you understand...
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You could give your population [Mild Androgen Insensitivity Syndrome](https://en.wikipedia.org/wiki/Mild_androgen_insensitivity_syndrome) and in particular the variant that reduces (but does not block) the transcription of the androgen receptor. This is done by engineering a retrovirus that increases the length of the polyglutamine tract on exon 1 of the Xq11-Xq12 locus on the X chromosome ([Genetics of AIS](https://en.wikipedia.org/wiki/Androgen_insensitivity_syndrome#Genetics)). Do not increase it overmuch or you will cause disease in your male population, too little will not cause the effect you are after: male infertility due to lack of spermatogenesis (no sperm cells). Your females are all normal in every way except that they carry a copy of the defective gene on both X chromosomes. You may need to experiment a bit to find a length between 21 and 40 CAG repeats that gives the desired effect without too many nasty side effects (such as osteoporosis or male breast development or incomplete male genitalia and many others).
In your reproduction clinic you will only select females which carry the defective gene on both X-chromosomes. To make the males fertile give them excess testosterone. You cannot do this long and it needs to be monitored for adverse health effects as liver disease, prostate cancer, breast cancer, to name a few. Screen for mutations in both the parents as well as the offspring as this sequence is quite mutation prone.
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You want to prevent reproduction, not intercourse. For that you just need to cripple one of the two sexes.
For example you can damage (remove) one of the many proteins needed to have a sperm/egg cell able to fulfill its task. I.e. you could suppress the tail formation for the sperm cells, or the egg nesting ability in the female body.
For those who are allowed to reproduce, you will host them in dedicated centers, where they will be provided "reproductionally enriched food and water", where the missing proteins, that you know, is supplied in their diet.
However, this won't protect you from casual mutations, so you have to perform routine checks and updates.
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# Vasectomies are reversible
But you want something woven into the human's 'base code'. So you genetic engineer the [vas deferns](https://en.wikipedia.org/wiki/Vas_deferens) either to be too small to pass sperm, to not be connected, or to not exist at all.
This is simpler than some sort of protein change that could have other, far-reaching implications of biochemistry, and it isn't a disease that could accidentally cripple one or the other sex. This is just a part that isn't there, but isn't needed for anything else.
If you want to reverse the sterility, you put a plastic tube in there. If we you want to re-reverse the sterility, you take the tube out.
Of course, it doesn't really sound like you want sex by intercourse at all; if you are going to be just breeding people in fertility centers or whatever, then you just extract sperm from the males you want to reproduce, no vas deferns needed at all.
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Don't have males born into the general populace.
They store semen in giant freezers, sometimes they allow a male embryo to be born in a lab or the ruling family, who has their external genitalia surgically corrected into female-norm because in their society, anything else would be abnormal but can still produce sperm in a way to replenish your frozen stocks.
As to two people being able to produce offspring if they are "genetically superior" - you either need to the technology to make an embryo out of two ova or lie to them and say the child is theirs.
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Biological systems are always going to be messy and imprecise. Whatever method you choose to enforce sterility there are likely to be some exceptions that will manage to procreate. As a wise man once said, “Life, uh, finds a way”. With this understanding, it should be clear that enforcing sterility in women is much more important than doing so in men. Imagine what would happen if a rogue government manages to find one fertile male on their planet and all of the females are already fully fertile? One female escaping sterility does not represent nearly as much of a threat. Of course, the strongest barrier would be sterility in both men and women requiring two individuals to overcome their sterility and find each other which would be a much rarer occurrence.
All that said, in order to make sterile humans we don’t need to rely on existing human disorders which are necessarily imprecise and will have many side effects. There are many genes that are used in the reproductive system that are not used anywhere else in the body. All you have to do is knockout an essential gene, of which there are sure to be dozens if not hundreds of candidates, and you have complete infertility with no side effects. The only question is where to break the system to achieve the most complete infertility, the fewest undesirable side effects, and the easiest reversibility.
For males, the simplest change is disabling a gene directly required for the functioning of mature sperm. This could mean sabotaging the acrosome, the flagellum, protamines, really any gene unique to the sperm can be broken without any effect on the rest of the organism. This would result in complete male infertility reversible only by genetic engineering.
For females, the analogous simplest change could be breaking egg-specific genes and processes which would do fine, but an alternative would be preventing menstruation entirely. The menstrual cycle is regulated by various hormonal clocks. We can already manipulate this process with ingested chemicals so it would be relatively straightforward to genetically turn off the menstrual cycle entirely. This has the advantage of eliminating the general unpleasant burden of menstruation from the female population but also allows for easy reversibility with orally ingested hormones being sufficient to start egg maturation again.
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**Background**
A colony of humans has settled on a remote planet where there is little to no sunlight, but there is a plentiful amount of earth metals. E.g.- Iron, aluminium, Titanium, etc. There are high speed consistent winds that make it ideal for harvesting electricity from wind (speeds of 60 - 100mph.)
**Question**
What type of wind turbines would be ideal for this environment? I ask this as I got the impression that regular 3 prop wind turbines would rip themselves apart at these speeds. Any suggestions?
[Answer]
# A variable pitch airplane propeller
### There is no advantage to high rotor speed past a certain point
[Rotor tip speed advantage](http://iopscience.iop.org/article/10.1088/1742-6596/524/1/012087/pdf) maxes out around 80 m/s, with marginal energy efficiency gains dropping to 0 at about 110 m/s. Why do I bring this up? Because it tells us how we want to design rotors in high speed winds. Instead of a lighter rotor designed to move with the wind, we want a heavier and larger rotor designed to survive constant wear. Also, there is a certain point of rotor length in high speeds where we will lose our return on investment. THe higher the wind speeds, the faster the rotor moves, the faster the outer tip moves. THerefore, to keep the outer tip from getting too high, it would be more efficient to use smaller blades in higher winds.
### Wind turbines can already survive high speed winds
According to wikipedia, a common survival speed is 60 m/s (134 mph) while some turbines are rated up to 80 m/s (180 mph). Turbines will [lock their rotors](http://www.wind-power-program.com/turbine_characteristics.htm) at higher winds speeds to prevent damage. Commercial ones I looked at will tend to lock below 30 m/s; which is 67 mph and lower than your planet's wind speeds. A high survival speed just means that the mount and blades won't be blown down by winds of a certain speed.
### What you need is pitch variation
Pitch variation will allow a turbine blade to change the angle with respect to the wind. There are papers proposing electronic control algorithms for rotor pitch that can capture wind speeds up to 50 m/s (111 mph, good enough for your world). The reason you need variable pitch is that your wind speed changes (from 60 - 100 mph) cover a wide range. Efficient production at 60 mph won't require the same pitch as efficient production at 100 mph.
Variable pitch wind blades don't exist commercially, as far as I can tell. There have been some [research examples](https://www.sciencedirect.com/science/article/pii/S0306261908003358).
However, plenty of aircraft have [variable pitch propellers](https://en.wikipedia.org/wiki/Variable-pitch_propeller). For example, the C-130 Hercules military transport aircraft from the US has such a propeller. Your turbine design will look like a airplane propeller, with electronically controlled variable pitch rotors. Note in the picture below, each rotor has a circular attachment to the hub. This will allow it to rotate the angle between the blade and the oncoming wind.
[](https://i.stack.imgur.com/hnd0f.jpg)
# Conclusion
Airplane rotors can obviously adjust their pitch successfully in winds speeds higher than the 60 - 100 mph you propose. Algorithms for controlling pitch to optimize power production have been proposed in literature. And turbine installations can already withstand wind speeds upwards of 180 mph. Put these three concepts together to develop a successful high speed wind system.
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Short Answer: Yes.
Have a look at some of the options in [this link](https://www.popularmechanics.com/science/energy/a4428/4324331/). I think the one you're interested in would be the Windspire.
[](https://i.stack.imgur.com/xPSAo.jpg)
"This 30-foot tall, 4-foot wide turbine generates 2000 kilowatts per hour given 12-mph winds, and it can survive winds up to 105 mph."
It's also nice and compact, which makes it even more suitable for the kind of scenario you're describing. You'd probably want to scale it up for your purposes though. There's no particular reason you couldn't make them much, much larger without compromising their ability to handle your high wind speeds.
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Considering that airplane propellers go substantially faster than wind turbines but do not fly apart, I think you should be able to rig a windmill equal to your windspeed.
But how boring. Instead, make wind turbines patterned on jet engines! Those go really fast. I could only find one.
[](https://i.stack.imgur.com/k6ZZT.jpg)
<https://www.youtube.com/watch?v=ygBsb5FKyOo>
You can assert that the radial redundancy holds it together better in the high winds of your world. And it is cool looking!
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## Change the blades
Crazy easy. You go to [Clipper Windpower](https://www.clipperwind.com) and you say "Hey guys, I want your commercial off-the-shelf industrial windmills, but I have very strange atmo pressure and wind speed."
Why Clipper? Because until quite recently, Clipper was part of UTC (United Technologies), a big aerospace conglomerate. And so their Rolodexes will still be full of contacts from ...
[](https://i.stack.imgur.com/TZZL1.png)
[Who](https://en.wikipedia.org/wiki/Hamilton_Standard) is *The Very Premier* maker of propellers in the western world, having made them for everything from the Spirit of St. Louis to the evolved E-2 Hawkeye\*. Rest assured, Hamilton Sundstrand propellors have no trouble at all with your wind speeds.
Between both companies they'll easily figure out a new windmill blade for you that "bolts up" to their standard hubs and control systems, and the stock control software doesn't even need to know it's on a different planet. Which means, no new bugs.
---
\* The 8-blade prop, while aerodynamically excessive, is an even multiple of the previous 4-blade prop, and *that* greatly simplifies the rewriting of the radar software, since the rotodome and other radar systems must account for their own prop shadows).
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Human have begun colonizing the solar system using the ablative laser microwave drive, our next target is Proxima Centauri and inbetween there is basically nothing except dust and occasional asteroids which is entirely avoidable even with blindfold. What can be the reason to install plain windows onboard when almost every spacecraft is running on autopilot? The journey might span several decades... as usual no FTL nor cryogenic freezing etc you get the drift.
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If there's no FTL or cryogenics involved, there's going to be real people living on these ships. Most people don't deal well with feelings of claustrophobia; they're going to want to see outside every so often. Windows are a cheap and effective way of doing that; unless I'm mistaken, the ISS and the space shuttles all have windows to some degree. Seriously, the mental health of passengers and crew is something really important to consider; you don't want the guy repairing a leak to be badly sleep-deprived or paranoid as the result of such concerns.
Windows can also make for one form of failsafe in the event of sensor failure. Granted, if you actually have to rely on visual contact to navigate you're probably doomed already, but having an open observation deck with a few telescopes would be a good idea (as long as it's possible to seal it off from the rest of the ship in the event of a serious breach).
If you want more details, take a look at my answer to [this question](https://worldbuilding.stackexchange.com/questions/31701/what-are-the-advantages-of-exposed-bridge-on-spacecraft/48311#48311), which is concerned with the practicality of having exposed bridges (bridges with windows) on combat vessels. It would also be worthwhile to look at the other answers there.
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There is no compelling reason to have many windows in an interplanetary space ship. Windows add weight, complexity and possible points of failure, and should be avoided as much as possible.
However, there have been times where windows have proved useful for monitoring the vessel itself. Apollo 13 noticed the venting of some gas into space, providing a major clue as to what had happened and the seriousness of the event. They used reports of the position of the venting gas to help determine what it was that was leaking (they also used the thrust effects from this gas on the vehicles attitude to estimate the source).
On the ISS, commander Chris Hadfield noticed through a window that flakes of something were departing from the station. This turned out to be an ammonia coolant leak.
It can be assumed that astronauts on your vessel will need to make periodic spacewalks, to perform maintenance. It may be worth the cost of the window to be able to observe them directly from inside.
It's arguable that video cameras would provide most of the above functionality. For stellar navigation, and monitoring of the destination as it approaches, telescopes penetrating or mounted on the outside of the hull would suffice, but a window or two would provide a nice backup.
Humans, being humans, probably want a few windows to look out of, just to look out of. Psychology onboard a very long endurance mission is very important, and will in some cases override pure engineering arguments. One observatory, and a few strategically placed portholes would probably be acceptable.
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The same reason we like a cloudless night: the stars are pretty. And when they do reach Proxima, humans will want to look at it.
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People have mentioned passengers wanting to see out and the useful ability to be able to quickly see if there's anything wrong with the outside of the ship, but we're forgetting something vital here - navigation.
Sure, you're in space and there's going to be a fancy computer doing all the legwork, but in the event of a failure you need a last resort option. Even today, ships at sea should have a compass and someone who knows how to use a sextant. You can actually use similar methods to navigate in space, Michael Collins had a sextant on board Gemini 10 for this very reason (although due to atmospheric conditions it was ineffective). There's also Apollo 13, where Jim Lovell controlled an acceleration burn simply by lining up the Earth and the Sun in his window.
There would be no worse fate than suffering a navigation systems failure and knowing that you had the expertise on board to get from A to B, but without any way of looking outside.
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Suppose human beings have evolved markings covering the face and hairs. The cells contain a colony of bacterium capable of producing multiple arrays of visible light. Each bacteria reacts differently to a variety of chemicals secreted from our sweat glands. This complicated mixture of chemicals is controlled by our emotional states as well as the environmental factors such as humidity and temperature etc.
How can the complex brilliant display of bio luminescence be incorporated into our written language and what will it look like? Not to be confused with camouflage(chromatophores).
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This will have significant effects on human society, far more important than its effects on written language. Everyone basically has a [polygraph](https://en.wikipedia.org/wiki/Polygraph) built into their face. There will thus be social conventions about when it's permissible to cover one's face, and these will probably make social status very important. You need to consider this carefully in writing about these people.
I'm not sure that written language will capture much of this mode of expression. Since it's basically involuntary, and probably isn't completely standardised between different individuals, it's only really meaningful when recording an individual event, rather than the more abstract uses of language. So it may well turn into some extra descriptive adjectives, as AndreiROM suggests, or something equivalent, like emoticons.
There's an analogy in all the things we can do in speech that aren't written down as part of all text. Different tones of voice, deliberate changes in timing, different emphases, and so on let us convey a lot about how we feel in addition to the content of the words we speak. But this is rarely written down, and when it is, it tends not to be mixed in with the words.
So the effect of this on written language may not be large. The effects on how people communicate face-to-face, however, will be huge.
[Answer]
It might not have any impact. Human beings can gesture with our hands, but although we can use our hands to emphasize our speech, it doesn't really change the communications. The only non-constructed language I've ever heard of where hand position impacts the spoken words is pre-telephone dialects of Portuguese. There may be others, but they aren't common.
Just because we can use a signaling mechanism doesn't mean we will.
Or we might - facial expression, vocal pitch, and other signals DO commonly impact the spoken words. *I think this is something you as an author can play any way you want.*
[Answer]
Any number of conventions might arise. For example:
>
> I feel so overwhelmed! ***[magenta]***
>
>
>
OR
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> I feel so ***magenta***-overwhelmed!
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>
>
Alternatively, things might not change much at all:
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> The premier's message was one of unity on this dark day, his powerful message being reinforced by strong, confident hues of blue, and deep purple as he addressed the nation.
>
>
>
It really depends on how complex those bio luminescence patterns are, and what sort of depth you want to go into when describing them.
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Written language conveys ideas. For a variety of obvious reasons, writing combinations of simple symbols is easiest, and changing the situation probably won't change that result. Maybe "$" means "literally-green-with-envy", but it's still going to be an easy-to-reproduce symbol.
For storytelling purposes, you want to sidestep all this, and just use English (or whatever). As Asimov lampshades in *Second Foundation* (emph mine):
>
> The Student smiled shyly, and the First Speaker responded by saying, "First, I must tell you why you are here."
>
>
> They faced each other now, across the desk. Neither was speaking in any way that could be recognized as such by any man in the Galaxy who was not himself a member of the Second Foundation.
>
>
> ...
>
>
> The same basic developments of mental science that had brought about the development of the Seldon Plan, thus made it also unnecessary for the First Speaker to use words in addressing the Student.
>
>
> Every reaction to a stimulus, however slight, was completely indicative of all the trifling changes, of all the flickering currents that went on in another's mind. The First Speaker could not sense the emotional content of the Student's instinctively . . . rather he deduced them, as the result of intensive training.
>
>
> Since, however, it is inherently impossible in a society based on speech to indicate truly the method of communication of Second Foundationers among themselves, **the whole matter will be hereafter ignored. The First Speaker will be represented as speaking in ordinary fashion**, and if the translation is not always entirely valid, it is at least the best that can be done under the circumstances.
>
>
> **It will be pretended therefore, that the First Speaker did actually say, "First, I must tell you why you are here," instead of smiling just so and lifting a finger exactly thus.**
>
>
>
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## Verbal vs Non-verbal communication
What you are describing is just a more pronounced form of what we already deal with when it comes to written language versus spoken. Body language, tone, inflection, gestures. There are any number of non-verbal cues that we have evolved to use and understand which have them been adapted over to the written word.
In the world you describe, written language would only have to be slightly shifted to accommodate the new facial markings. If you are writing about someone who is angry you can mention their volume and tone, or that they have clenched fists, or that their face flared crimson (or whatever the accepted display for "anger" would be). Those first two would work in our society because we understand that angry people shout and make fists. The third description would work because people in your setting would know that angry people have literal red faces.
Here is a quick and simple exercise that might help you get a feel for what writing in your setting looks like: Pick any piece of writing today that focuses on character descriptions, what they are saying and doing, and then try to replace each of the descriptions with the appropriate visual cue that someone in your setting would have. Once you know what different emotional responses look like you can start to use those as replacements when talking about in-story text. Where we would say that someone sounded sad, they could say that the person looked blue (or, again, whatever the response is).
If you just need an idea of what written language would look like in your setting, that should be a good enough start. If you actually plan on showing off that written language then you would need to do a bit more work. First introducing readers to the visual cues and what causes them, and then making sure that you incorporate them often enough that it feels like a natural thing. Remember, humans have very good grasps of what these non-verbal cues mean. If you see someone grinning you know that they are most likely happy. If someone in your setting sees someone flashing yellow and pink, they would be just as confident that they knew why, and a writer would be just as likely to use that as a shortcut that the person is happy as we would say that they were grinning.
[Answer]
Bio-luminescence by the mechanism you describe would act too slowly to keep up with the pace of human verbal communication. That rules out using the colors as an extension of language, for example in place of the tones in a tonal language like Chinese and Narrow Bantu, or in place of the genders of a highly gendered language like Latin or Sanskrit. The user wouldn't be able to change 'tone' or 'gender' fast enough to keep up with speech.
Color changes would be fast enough to express emotion in speech. Irony, Confidence, Humor, Satire, etc could all be indicated by bioluminescent changes. However, this has the drawback of not being as visible during the daylight, and harder to see from a distance. If a general is giving a speech to 5000 assembled troops, its hard enough for everyone to hear him, much less to see his steely blue confidence.
The last option is as a sign language of sorts. In West Africa and among Aboriginal Australians, there are 'home sign' systems which closely replicate the full complexity of a natural language, and which some think could have co-evolved with spoken language.
The most reasonable explanation for light based communication, then, is that your people originally used bio-luminescence as a means of communication such as chimpanzees or gorillas communicate to each other. Then, as the species evolved human language with its emotions and abstract concepts (things that are absent in animal 'languages') the bio-luminescence co-evolved as a 'home sign' language. While perhaps not expressing a full range of concepts like a real language, it could express a limited subset, especially since the 'bandwidth' of sharing thoughts would be lower than with a verbal language.
Even more interestingly, it could be that the bio-language and verbal language diverged, so some groups have different verbal languages but can 'light talk' to each other when they trade. Or you could even say that the bio-language is genetically determined, and when two people can't speak to each other, they can resort to ape-like bio-luminescent communication.
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I have a city on the edge of the sea and an ancient forest. The forest was protected for generations by local rulers but current ruler get bribed by foreign guilds to allow logging. The trees are old and huge and the water for transport is near so the guilds are reaping huge profits allowing to continuously sponsor the ruler.
There are some "forest people" that oppose the logging but I want the city people to join the struggle and **I wonder what could motivate** them to take up arms in such conflict and then protect the forest later if they win?
The city people are supporting themselves most from the sea and the trade so there is not much financial incentive to fight. I would say that some would have incentive to continue logging for profit if foreign guilds monopoly would be broken.
The local ruler is passive do not have much enforcers of his own and is a vassal subordinate to higher level lord. His superior would wholeheartedly opposed to logging but have his own bigger problems and cannot afford any internal struggle at the moment. So if the guilds can be kicked out quietly then nobody would make a fuss.
The forest is considered the most beautiful in a continent and to some extent considered a cultural treasure but I think such sentiment would speak more to aristocracy and not to common people who I want to risk their lives and who do not get much direct benefit from it themselves.
The city people do not have to come up with the impulse by themselves, there some outside forces that try to rouse them but they have to have convincing argument.
The social and technology level corresponds to medieval/renaissance.
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**Clarifications**
The city people follow religion which emphasizes order and hard work, in the forest there is a sect spreading that focuses on self sufficiency and living in harmony in nature but it is foreign religion and have only handful of adherents. The local religion is well entrenched so I think making population switch is the same question - it needs some strong impulse to happens.
The woodcutters are foreigners, have similar culture and follow different branch of local religion. There are a lot of them about 2000 for a city population of 5000 (and most of woodcutters are young and strong whereas city population includes children, old and infirm).
The city "merchant" elites have reasons to oppose the logging guild but are week and few and bulk of city population is made from poor warehouse workers, sailors and fishermen.
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*Disclaimer: This is a scenario for a RPG but I feel it fits wordbuilding SE much better.*
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In Medival England common folk had the right to use commonly held woods and forests in certain ways.
Pannage-pigs could be turned out into the forest to eat acorns and other wild produce in the autumn.
Estovers-they were allowed to collect wood for fuel and to build and repair homes.
Turbary-cut turf to use a fuel.
Marl- collect clay to use as a soil Conditioner.
For medieval people's the ability to fatten their pigs for the winter, to get fuel and building materials were very important and in some cases. Were the only thing that stopped them starving.
These rights are still exist today in some places, for instance the New Forest National Park.
<http://www.newforestnpa.gov.uk/info/20089/rich_cultural_heritage/48/commoning>
There were then several Inclosure Acts that took these rights away from people that in some cases lead to unrest.
People in your city may have been using this forest in a similar sustainable way for centuries, are are now going to lose them.
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* **Tradition:** As you said, generations of previous rulers protected the forest. For that reason the citypeople feel that preserving the forest is part of their cultural tradition.
* **Religion:** The forest people could spread their faith in the city and convince the city people that the forest is holy and chopping it down is a sacrilege.
* **The foreign logging guild is unpopular:** Maybe the leader of the guild insulted the city. Maybe the guild lumberjacks regularly visit the city after work, get drunk, harass the womenfolk and start brawls. Maybe they are supporting a rivaling sports club. Maybe they are of a different race and the locals are racist. Whatever the reason, the citypeople dislike the guild for reasons completely unrelated to their logging activity and thus oppose them on principle.
* **Economic interests:** Some of the cities most wealthy and powerful aristocrats might have economical interests to oppose the logging guild for reasons which are quite indirect. The forest might not be *directly* their business, but maybe the foreign guild is competing with them for the market of other products. They want to prevent them from becoming more powerful. They might also be afraid of the slippery slope: When they allow the foreign guild to do business *around* their city, it's a very small leap to allowing them to do business *in* the city and compete with them directly. This gives them a reason to agitate the commoners against the foreigners.
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Event Sequence:
**Event 1:** The entry of the foreign guild along with its workforce displaces local population deriving sustenance from the forests(Local lumber jacks, gatherers etc.,). This is a very small minority.
**Event 2:** The guild has begun monopolizing the lumber trade, they begin hiking lumber prices in the local markets as they get better rates for exports. This begins to affect the local shipbuilding industry, which in turn affects the fishing industry causing price rises of sea produces.
**Event 3:** Petitions to the local ruler are being dismissed as he is already being paid up. Ruler's apathy begins to sow seeds of dissent.
**Event 4:** Powerful aristocrats sniff an opportunity to snatch power and establish control. They begin seeding local news and rumor mills with campaigns against the ruler.(Much like today's politicians influencing the media.)
**Event 5:** Once the scene is set, all it would take is for a bunch of people acting as members of the logging guild to do something stupid enough to rouse the people. (Maybe set fire to a few buildings or burn down a warehouse.)*[This can be done by the scheming aristocrat or the forest people.]*
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You say your city makes its living from the sea and trade. In which case, they will need timber for **ship-building**. There may therefore be all sorts of ancient and complex agreements between the forest people and the shipwrights, on when and where it is appropriate to log some trees for ship-building. Only take 1 giant tree per acre, for instance. Or to plant 100 acorns for every oak you fell.
There could be other, equally ancient agreements, which are all about forward planning. When [York Minster's roof was struck by lightning](http://www.bbc.co.uk/news/uk-england-york-north-yorkshire-28112373) and destroyed by the subsequent fire, people who owned and/or managed ancient oak forests offered their trees to build a new roof. An archaeologist told me that in one case, the forest in question had been originally planted for just such eventualities - to provide oak timber decades or centuries after the acorns were first planted.
So the foreign loggers could be violating ancient/traditional pacts and agreements. The local folks could just know about them, but not have them written down anywhere. Or you could make a plot point of someone digging out a dusty manuscript from a forgotten shelf in a local monastery/castle/guildhouse which proves that only Guild X or Family Y has the right to harvest timber from the ancient forest.
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They probably wouldn't even know it was happening. There's a reasonable chance the common people are illiterate even if there is such a thing as a newspaper, travelling any distance is pretty much unheard of for common people other than the traditional migration from country to city. This is just not a thing they'd know about and if they did, they may well not want to get involved with the problems of their "betters".
Migrant labourers have always been unpopular though, it's likely they wouldn't be allowed into the city after dark.
I'm struggling a little with your basic premise
* Timber was the greatest strategic resource of the period, it would take a lot more than bribery to allow a foreign power access to it
* Woodcutters are peasants, you don't move peasants internationally, you just find some local ones
* Rebelliousness requires free time and spare money, common people on the whole have neither in the period you're talking about, it's a luxury of the wealthy
You're going to need to bring up some real leverage to get the ordinary street people with no connection to the forest to care about something happening more than a mile from their front door in this period. One of the key ways to do this would be to **downgrade from "city" to "county town" or even "village"**, the populations of these smaller urban environments are more likely to still have a connection to the surrounding countryside and depend on it more directly for food and fuel, and Sarriesfan's considerations about common law come into play.
You'll also need a real rabble rousing speaker, these are harder to find and liable to be hanged quickly if caught. Your technological period overlaps the Bloody Code years in England where just about everything was a hanging offence.
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Another option, similar to religion, might be the fear to be cursed, if the forest is damaged.
The fear of supernatural beings was common in medieval times. Every region had their own versions of tales that were told, e.g. to keep little children away from dangerous places and to tell when drinking with others. Sooner or later most of them became so common that all people in the region believed in them. So if you can make the townspeople fear for their lives, because the "supernatural guardian of the forest" might get angry you have a reason for them to take up arms.
This might be better suited for your situation than religion because religion was normally wide-spread. So if the forest was sacred people from other guilds should know about the sacred forest, too. With a local legend of the supernatural you can make it so that only your people are afraid and not the foreign people coming to cut down your "cursed forest".
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You are stranded on Earth as it was ten thousand years ago. You have access (say, through a brain implant) to all of current human knowledge. Assume that basic survival is no issue.
Starting from scratch, your task is to create a rod, out of any material you like, with a length of one meter. The length must be accurate to one nanometer. How long would this take? How much prerequisite technology would have to be developed? Considering you have no meter-related standard to compare against (other than the current definition of the meter and physical constants), is it even possible to complete the given task in a single lifetime?
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This is a fascinating problem because it shows just how tricky it is to define units of measure. In school, we are often given the impression that the units are inviolate structures fundamental to nature, but reality shows otherwise.
This task would have been impossible before 1960. From 1889 until 1960, the meter was actually *defined* by a particular bar stored in Sèvres, France. Without access to it, it would be virtually impossible to construct a 1 meter object. Before that time, the meter was actually defined to be 1/10,000,000 of a quadrant along the Earth's meridian. Interestingly enough, the meter bar they constructed was actually 200um shorter than it should have been due to a miscalculation, but once the bar was struck, it *became* the meter.
From 1960 to 1983, the meter was redefined to be 1650763.73 wavelengths of light from a specified transition in krypton-86. This meant that, for the first time, one could have a definitive "meter" that was not bound to a physical object which could be damaged or worn down. This definition was replaced in 1983 with our present one, which is the distance light travels in a vacuum in 1/299,792,458th of a second. This definition locked the meter down to a physical constant (the speed of light), and the second.
Swallow the spider to get to the fly.... okay, how do we measure a second to within nanosecond precisions?
For the longest time, the "second" was measured as a fraction of the day. This was sufficient for centuries. However, the day actually varies slightly, so in 1956 we redefined it to be "the fraction 1/31,556,925.9747 of the tropical year for 1900 January 0 at 12 hours ephemeris time." Yes, this is how we do things in science.
Of course, it would be easy to lose track of exactly how long the period of year was back in 1900, so this was less than ideal. In 1967, after the invention of the atomic clock, it was redefined to be "the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133 atom." What a mouthful!
So these numbers are incredibly precise. They need to be. If you want to measure the second accurate to 1 part per billion (one nanosecond) so that you can measure a meter to 1 part per billion (nanometer), you need all those sig figs. If you miss just 10 of those tiny transitions in your caesium atoms, you're off by a nanosecond!
At this scale, silly things start to matter. For instance, we noticed that time was traveling faster for some clocks at different altitudes because of relativistic effects. Yes, relativistic effects matter on these scales, so the second was re-clarified in 1997 to be the rate of an atomic clock operating at mean sea level! This had about a 0.1ns difference per second, so it shows up on the scales you care about.
So to answer your question, no. A single person is not about to make an accurate meterstick in their lifetime. Your first step would be to create an atomic clock, which calls for high purity components, high vacuums, and quite a lot of high precision machining. With that, you could acquire some caesium-133 and measure a second to a high enough precision. Then you could attempt to measure the speed of light using another expensive scientific instrument to create your meter.
Finally, you could create your meter stick. Did you know that this is not easy? The machinists and metrologists that build these high precision measuring devices are extraordinary. Hopefully your isolated human sent back ten thousand years happens to have spent his whole life mastering this art!
You could try to take a step back in history, and use the krypton definition. You could build an interferometer to do this measurement. However, the transition to measuring the meter based on the speed of light was partially done because the best scientists in the world were having trouble measuring more accurately than about 0.2nm. Shifting to a definition based on the speed of light let them measure frequencies, which were far easier. If the best scientists and metrologists of our world had trouble measuring accurately on the scale you are interested in, its highly likely that you'll have trouble with it 10000BC.
Fortunately, you don't need a kilogram definition. That one is *still* defined by the IPK in France, a lump of platinum irridium. There's a current effort to change this definition, redefining the kilogram as "1000/27.9769265325 · 6.02214179×10^23 atoms of Si-28. Yes... that qualifies as a "better" definition of the kilogram. Metrology is an insane art, but you have to respect their immaculate precision!
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Trivial task, 2 days max.
Know your height, or any other size-measure? Take whatever is there (clay, wood, ...) and start churning out rods, a hairs breadth different. Hundreds, all in the eyeballed ballpark of 1m. Then hug them, or wait for nightfall. Thermal expansion will guarantee one of those to be the exact meter you need.
Task did not specify you had to point to a specific rod at specific time...
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If you knew your height, then it would be fairly easy to find the length of a meter.
*However*, generally people only know their height in meters to 3 or 4 significant digits. Getting the length accurate to a nanometer would be effectively impossible. Thus, you'd have to go back to the definition of the meter: 1/299 792 458th of the distance light travels in a second. You'd also have to know how long a second is: exactly 9,192,631,770 periods of a certain frequency of radiation from the caesium atom.
So, in effect, you'd have to build an atomic clock, an electronically-controlled (hand control wouldn't result in necessary accuracy) light source (preferably a laser), and a very, very long stretch of absolutely flat land **in a vacuum** (light travels at a different speed in air). Not to mention all the necessary technology to make refined metal, electronics, etc. You'd also have to find and purify caesium, which is rather uncommon.
I'd say its impossible in a lifetime.
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If you have to be precise down to the nanometer, probably not. The meter, as we know it, is defined as "the length of the path traveled by light in vacuum during a time interval of 1/299 792 458 of a second." The meter was first defined as one ten-millionth the length of the prime meridian, a distance you are unlikely to be able to calculate without some advanced technology. An alternate method that might be more plausible, though still unlikely, would be to construct a pendulum with a half-period of one second. The distance that the pendulum swings is approximately one meter. Beyond that, there is really no sure way to tell a meter without having some kind of meter-related measurement.
If close enough counts, and if you have the right materials, you might be able to use a sapling. If you know how much a certain kind of tree will grow in 365 days, you can figure out how long it would take to grow one meter, then cut the tree. Similarly, you could look up/remember how long one or another bone is in an average however-old human and base your ruler on that. It still won't be perfect, but it will be close. And really, who is going to call you on it?
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The easiest way to do it if you had access to all current Earthly knowledge at your hands and bronze age technology and people at your disposal (to mine and such the material) would be to do some simple volumetric math using multiple systems.
For example I would know the weight of iron, bronze, brass, copper, tin, etc per cubic meter or lbs per foot. and I can come up with about the right size for both off the top of my head. Since we can convert using ever greater accuracy if we couldn't convert from our third made up system to them both then to each other we would know that we were off and just work it out through testing and failing until we get the right dimensions.
Another way to do it, if you built a camera of some sort or had a cell phone on you that could is to just throw stuff off high places with a camera taking pictures as it fell. And again using several systems and your own you just convert and find the rate of fall which you'd know the number of once with your knowledge base, because after a certain point things stop accelerating.
Another way to determine it would be to look at the sun and measure it or moon as it moves across the sky which we know the distance of and thus could get a number from...
Ultimately though, all of the ways only would give you a meter to millimeter scale probably, but, again, once you have a rough estimate of that you can pretty easily cross reference measure to between multiple things as in the first option and and pretty easily get it pretty accurate.
I don't consider the measurement the hard part of your question, because assuming you had the tech to do it, its fairly simple given all the knowledge. Now if you asked me to machine the rod rather than tell if and when it is that precise length there would be a bigger problem, because that takes precision instruments which would require skills and materials to be built up on a civilization scale to get ahold of. Could you do it in a life time? Yes... if everyone listened to you and worked with you, you could, easily. The problem is that they wouldn't and so at best you'd only be able to write it down or try to convince those in charge that the current civ to listen to you.
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Assume that all materials, chemistry, etc is the same, you have basic technology and scientific knowledge, but that you have no artifacts: Not even your size.
Water is the same, so you can construct a thermometer with a Celsius scale.
Any suitable battery chemistry will give you a reference for a standard-Volt voltage scale.
Using the known e/m ratio of an electron, an [e/m tube](http://advancedlab.physics.gatech.edu/labs/waveparticle/images/figure5.gif) will give you a scale for a standard-Ampere current measurement.
Finally, the thermal properties of water will let you create standards for a liter and cc. From those, you can get operational kilograms and meters.
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Is it possible for nanobots to become so integrated with a creatures biology that they could be transferred via the creatures reproduction and passed on to future generations? 'Synthetic Biology' looks promising, but it did not cover inheritance of traits.
Here are some links on Synthetic Biology:
<http://www.nanalyze.com/2013/08/what-is-synthetic-biology/>
<https://www.bio.org/articles/current-uses-synthetic-biology>
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I can think of two possible ways this could work.
1. The nanobots could be physically present in the reproductive cells or transferred from the mother during gestation and would then have to reproduce and spread through the developing organism's cells.
2. The nanobots modify the host cells DNA to make the host cells reproduce them, similar to how a virus reproduces, but a more symbiotic relationship would be needed to prevent the cells death. More like mitochondria or other cellular components reproduction than viruses. This would be much more difficult to implement but could be possible.
Note: If your nanobots can spread this way, they would likely be communicable similar to diseases, not just inheritable.
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Sure, take a look at mitochondria and chloroplasts. They have their own DNA but they work as a part of cell to everyone's advantage. They once were separate organisms but were trapped in a cell and it worked out just fine.
You could also take a look at newborn babies' immune system and how it's coached by mother's immune system through breastfeeding.
If your nano-machines are self-replicating, there's a good chance that they'll replicate themselves into reproductive cells too and thus be inherited.
If they are not confined to cells but, for example, travel in bloodstream - again, while the baby is formed and his blood system is somewhat connected with mothers, they'll get there.
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If you think of bacteria as "natural" nanobots, then this already happens.
Within the womb, there's little-to-no bacteria because the placental blood barrier does a pretty good job of keeping things out, while allowing antibodies *in* so the baby can fight any infections that slip past.
During birth, however, all that breaks down and the baby acquires the standard human gut bacteria from the mother on the way out the birth canal. C-section babies tend *not* to get this bacteria, which has led to a number of hypothesis regarding natural vs. c-section babies and immunities, allergies, and college GPAs, but that's a whole other thing.
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Given a world with with absolutely no access to saltpeter (a key ingredient of gunpowder), and a wide-spread society at a medieval-level of technology, how long before this society would reach a non-medieval, Renaissance-type level of technology?
**Background**
1. No magic, although there may be "wizards" or "magicians" (illusionists) because...
2. Any other real-world chemical reactions are allowed.
3. There is a feudal system in place (a potentate, nobility, peasantry, etc.)
4. There are independent bodies of scholars.
5. Religion plays only a minor role in society, i.e., no one is beholden to the whims of the clergy.
6. Standard medieval technology
* Military: Cavalry, leather/metal armor, swords, bows, crossbows, castles, wooden catapults/siege weapons
* Civil: Horse-drawn heavy plow, architectural vaults/arches/domes, mechanical clocks, water/wind mills, basic printing
I'm working under the assumption that if gunpowder was never introduced, medieval technology would not have graduated as quickly. I'm wondering, though, what technological advances would be made regardless of access to gunpowder, and how long it might take to make those advances.
I'm interested in **all technologies**. Gunpowder is the only thing that's lacking in the world, so naturally, military technological advances would probably be hit the hardest. However, necessity is the mother of invention, right? Many of *today's* everyday goods and services were born out of modern military research, e.g., the Internet, microwaves, GPS, etc. In medieval times, if there was no gunpowder, no doubt people would still develop creative and effective ways to kill each other - but there would be no need to defend yourself from guns or cannons. A *social effect* I can see happening is that revolutions and uprsisings would be far less successful, since guns vs. guns is a much more even playing field than trained bowmen/swordsmen/etc. vs unskilled peasants... but what effect would this have on all *technological advances* during that time?
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I cannot give you a number in years. But even without gunpowder, the book press and the steam engine would be invented, and the Industrial revolution will continue just fine.
War would be different until chemists invent [Nitrocellulose](http://en.wikipedia.org/wiki/Nitrocellulose) in around 1800. Then, it is back to killing humans with gunpowder.
It would be fun to see steam-powered [catapults](http://en.wikipedia.org/wiki/Catapult) and [ballistas](http://en.wikipedia.org/wiki/Ballista) - or even human powered, just to punch some knights.
Also, there is another strategy which is independent on gunpowder, and would eliminate advantage of knight's heavy armor: [war wagon](http://en.wikipedia.org/wiki/War_wagon), developed around 1420 (some more images about [how it could be used](http://husitstvi.cz/vojenstvi/husitske-valecnictvi-trochu-jinak/vozova-hradba/) if many wagons circled to form mobile fortress (in Czech). It was nice to have guns to defend of such fortress, but defense would be almost equally effective with just [crossbows](http://en.wikipedia.org/wiki/Crossbow) (which are simpler to use and require less training and strength than bows). And if knights attack wagons (using melee attack), defenders can punch them over head with [flails](http://en.wikipedia.org/wiki/Flail_%28weapon%29) and pikes.
With or without gunpowder, the rule of knights was about to end.
One strategy will never remain effective for long, because everything always has weaknesses - opponents will develop strategies attacking those weaknesses, and the game continues.
Social effects of such wars must have been devastating to the knights: mere peasants not only successfully resisted their attack, but were superior and almost invulnerable to anything knights might throw at them.
Of course, the advantage of such mobile fortress disappeared with more effective gunpowder weapons. In your world, it's advantage would be longer-lasting. Read about [Hussite Wars](http://en.wikipedia.org/wiki/Hussite_Wars) - the Hussites defeated 5 crusades against them. Maybe with no gunpowder used against them, Hussites (unskilled peasants) would be able to resist more effectively, more effectively challenging the authority of the Roman Catholic Church.
But by 1700, the situation would be close to real-world history.
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It's actually much harder to eliminate Saltpeter then you might think as it's a relatively simple chemical in our nitrogen rich world. There is an amazing number of sources that can be used to refine it and can be created from whats found in batcaves and wood ash.
Wiki lists a couple techniques (given that it's to create saltpeter I can see some reluctance to give full descriptions):
>
> French method[edit]
> Niter-beds are prepared by mixing manure with either mortar or wood ashes, common earth and organic materials such as straw to give porosity to a compost pile typically 1.5×2×5 meters in size.[17] The heap was usually under a cover from the rain, kept moist with urine, turned often to accelerate the decomposition, then finally leached with water after approximately one year, to remove the soluble calcium nitrate which was then converted to potassium nitrate by filtering through the potash.
>
>
> Swiss method[edit]
> LeConte describes a process using only urine and not dung, referring to it as the Swiss method. Urine is collected directly, in a sandpit under a stable. The sand itself is dug out and leached for nitrates which were then converted to potassium nitrate via potash, as above.
>
>
>
Potash, as described above, is about 10% of the weight of wood ash.
Even if 'saltpeter' wasn't readily available in mined form, odds are there is some method or another to create this. Early Chinese were refining it considerably earlier than it's traditional 'saltpeter' usage...it was a salt readily found in marshes. It has uses from fertilizer to soap production as well. It was used in glass and bleach production as early as 500AD. In 1270AD, a Syrian recorded how to refine it.
It's really challenging to say a society lacks access to gun powder as it's a relatively common component of our earth and any society with basic chemistry should be able to being manufacturing from a relatively wide spread number of sources...I would assume Renaissance-type level chemistry would include the knowledge of refining potassium nitrate.
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The technological levels we associate with the modern era have more to do with *social organization* than scientific understanding. Remember that the Renaissance was literally the "rebirth", i.e. the rediscovery (and eventual surpassing) of Roman-era art, science, technology, and so on. The medieval era was a *rebuilding* of European social order from the social collapses of the Western empire that led to the Dark Ages.
It doesn't matter if you know (theoretically) how to build an aqueduct, if the largest political / economic entity that you're a part of doesn't have the resources to build one. And if the political or economic strength isn't there, then the theoretical knowledge is more likely to be lost over the generations. This problem is more pronounced in the case of large-scale technology, but still holds true for smaller-scale stuff. There are a thousand little problems that have to be solved in order to make, say, a printing press (not the least of which is making thousands of identical letters), none of which are going to be solved if the market for books is tiny because only a few people can read.
Conversely, if your social structure is diverse and complex, you have powerful nations, rulers, economic powers, and so on, then technological progress will continue apace and, even in the absence of one particular element of our conception of modernity, something closely resembling it will still occur.
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It's not clear to me that use of gunpowder is the sole element in changing warfare to have effective guns. Steel making is also important. Crude cannons or early firearms were not that effective, although the former did have a major effect on the usefulness of castles.
Remember that swords were carried by "infantry" into at least the 18th century (Culloden, 1745).
Even for cannons, steel making technology is essential in developing cannons sufficiently powerful AND mobile. Early siege cannons looked impressive and could intimidate, but took a long time to move around. The combination of shipbuilding advances and naval gunnery change that.
It's worth thinking about China and the rest of East Asia as a slightly alternate history. They *invented* firearms, but not the other advances (with a handful of famous exceptions) necessary to really move much beyond medieval technology. This is despite a high population and mostly stable political system.
With that example, a medieval-level of technology *could* last a long time.
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I don't think gunpowder is a main factor in technological development. It (and the canons, guns, bombs and firework technologies that use it), are just one set of devices which may be good against knights, who are a medieval icon, but knights don't really hold back technology, so I wouldn't say gunpowder or knights really affect technological development in general.
Nor does technology or scientific or industrial thinking necessarily emerge after a certain amount of time. It depends on culture, circumstances, and the history of ideas, which can and did take turns away from from such developments. Look at Rome, Egypt, Persia, China, Babylon, Japan... they all had centuries of prosperous intelligent cultural development, rivaling medieval Europe in some ways, but not leading to a technological revolution.
So, I would say a world could stay practically forever at a medieval level of technology, as long as the cultural, intellectual, and stability situations never went there, for whatever combination of reasons.
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Hmm, the premise of the question seems a little odd to me. I don't see how gunpowder was particularly a driver for other technologies. So suppose a society does not have gunpowder. Warfare would be different, of course. Let's get back to that. But I don't see how that would affect in any way the development of steam power, electricity, internal combustion engines, steel and other metals, etc etc. I don't see that the invention of gunpowder really led to anything else. Maybe there was some scientific knowledge that was gained by experiments that required gunpowder. I don't know of any, but I wouldn't make blanket assumptions.
The key thing that would be different would be warfare. The next question becomes, do people find some other way to kill each other that is as effective as gunpowder, or do you end up with trains carrying armored knights to the front? Soldiers riding motorcycles and carrying lances to do battle with other motorcyclists? Catapults where tension is created with electric motors? Etc. It makes for some entertaining fanciful scenes.
One could imagine cannons powered by steam -- people have built such devices. Not really as effective as gunpowder but it works. And of course once other explosives are invented -- dynamite and so forth -- there are plenty of efficient ways to kill each other again.
Would Europeans have dominated the world like they did without gunpowder? I think they had enough other technological advantages that they would still have been on top, but the process might have been slower and less complete. China and Japan might have been able to stand up to Europeans if neither had guns, for example.
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Its really not a matter of when. Technology plodded along steadily, around the world, until the factors for the renaissance luckily aligned.
Steel has been forged in China for almost two thousand years. The printing press was churning out Buddhist texts in India centuries before the invention reached Europe. Gunpowder itself was commonplace in China for many centuries before the first arquebus was invented.
The Renaissance was a cultural event resulting in technological progress. The Black Plague devastated Europe severely. The universal power of the Catholic Church was broken: those who had lived through an apocalypse could no longer believe in a merciful god as they had before, certainly not in the form of the lords and the priests. Rebellion was seeded. Rebellion against the church, the crown, the nobility, against even the culture.
The cultures of Europe were thrown off for successive generations, while technologies were eagerly imported from abroad, as well as texts, leading to the arrival of the printing press, gunpowder, and the lost classical texts, all imports from the world at large, by a Europe eager to throw off the past and move into the future.
So, to answer your question, it is not a matter of how many years, or even how many centuries. Its a question of culture and opportunity. Do you happen to have an invalidated prior culture and a truck-load of natural resources? You might be a good place for a renaissance!
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Any ant-keeping geeks out there? I know what it's like to keep ants and they are quite fascinating, I was wondering if there were giant ants (their gigantism is due to high O2 levels) could they be domesticated by humans (who are evolved suited to the atmosphere) similar to how we domesticated dogs? I know that sounds silly but could there be some chance under the right circumstances?
I would like to know which conditions need to be in favor for this to happen or is it impossible? And to specify how early the people are, the human civilization might be as old as we were when we domesticated wolves.
And about the agricultural role ants will play, do you think it's possible. Ants started farming way before we did but I'm not sure if this will work, or will the whole idea, please suggest anything that can make this possible.
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Short Answer:
Writers who don't care about how plausible or even theoretically possible their stories are don't have to read the rest of my answer. But if you want as high a score as possible in the scale of science fiction hardness you may need to read all of my answer.
<https://tvtropes.org/pmwiki/pmwiki.php/SlidingScale/MohsScaleOfScienceFictionHardness>
Long Answer: Which is sort of a frame challenge.
It is impossible to humans to domesticate giant ants, because it is impossible, or almost impossible, for giant ants to exist.
Part One: The Square Cube Law.
A science fiction writer should keep up with the latest discoveries and theories in science. As I remember Galileo Galilei (1564-1642) first wrote about the square-cube law, in *Two New Sciences*, 1638.
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> As stated by J. B. S. Haldane, large animals do not look like small animals: an elephant cannot be mistaken for a mouse scaled up in size. This is due to allometric scaling: the bones of an elephant are necessarily proportionately much larger than the bones of a mouse, because they must carry proportionately higher weight. Haldane illustrates this in his seminal 1928 essay On Being the Right Size in referring to allegorical giants: "...consider a man 60 feet high...Giant Pope and Giant Pagan in the illustrated Pilgrim's Progress: ...These monsters...weighed 1000 times as much as [a normal human]. Every square inch of a giant bone had to support 10 times the weight borne by a square inch of human bone. As the average human thigh-bone breaks under about 10 times the human weight, Pope and Pagan would have broken their thighs every time they took a step."[5](https://en.wikipedia.org/wiki/Dihydrogen_monoxide_parody) Consequently, most animals show allometric scaling with increased size, both among species and within a species. The giant creatures seen in monster movies (e.g., Godzilla, King Kong, and Them!) are also unrealistic, given that their sheer size would force them to collapse.
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<https://en.wikipedia.org/wiki/Square%E2%80%93cube_law#Biomechanics>
The exoseletons and internal muscles of insects ae less efficient than the endoskeletons and external muscles of vertibrates. So giant ants might be unable to move under 1 *g* of surface gravity, as on Earth. The tiny ants and other insects on Earth can move under 1 *g* of surface gravity because of their tiny size. Enlarging their bodies to the sizes of medium sized land mammals would probably make it impossible for them to move and thus to live.
Part Two: Another World
You could set your story on a planet with a lower surface gravity than Earth. That would enable giant ants to be larger. Of course Earth humans on that world would gradually over generations develope thinner bones and muscles, and native intelligent beings would evolve to be less musculer than humans.
It is known that long term stays in the micogravity of orbiting space stations have detrimental effects on humans. Of course a world with only one tenth of Earth surface gavity (0.1 *g*), or one hundredth (0.01 *g*), or one thousandth (0.001 *g*) should have a low enough surface gravity for giant ant species to be able to move around easily, and might possibly hav eenough surface gravity for humans to be healthy in the long term.
But nobody knows what level of surface gravity would be the limit on how low humans can tolerate for all their lives. The only way to find out would be to build permanent bases on worlds with different surface gravities, which owuld be very espensive - or build a rotating space station which would be very expensive but probably much less expensive than many bases on other worlds.
In one of the wheel shaped space stations common in science fiction, the central hub would basically have weightlessness, while the rim of the wheel would rotate at such a speed that the similated gravity in it would be about 1 *g*, and the similated gravity in the spokes would bet lower and lower the closer to the hub one got. So lab animals could be raised at different distacnes from the hub to see how well they tolerated different levels of similated gravity, and eventually humans could try living at the levels which were safe to the lab animals.
But until that is done, ther is no way to know how low the surface gravity of a world can get consistent with human habitability.
A naturally habitable world for humans would require sufficient escape velocity fo retain its atmosphere for hundreds of millions of years or billions years to for that atmosphere to be enriched with enough oxygen for humans to breathe.
And of course a world with low surface gravity will also have a low escape velocity. Fortunately the surface gravity and escape velocity don't change at the same rate. Specifically, I think that worlds which have a lower overall average density than Earth can surface gravity that is lower compared to Earth's than their escape velocity is compared to Earth.
Thus I can imagine a world with lower mass and lower density than Earth which - for example - has aboout 0.6 the escape velocity of Earth, that might be high enough to retain an oxygen rich atmosphere for geological eras of time, while having a surface gravity that might be 0.3 that of Earth.
But I have not done calculations to see what sort of world might have that surface gravity and escape velocity, and I don't know if a surface gravity of 0.3 *g* would be high enough for human health and also low enough to have ants giant enough for your question.
If you keep lowering the densities of imaginary worlds, eventually you will have to have their entire surfaces covered with oceans of some liquid that are miles deep, unsuitable surfaces for either humans or ants. And decreasing the density even more would result in planets largely composed of gas, and so having atmospherees too dense for huamns or ants to survive in.
Therefore, it is unknown whether any possible planet with a solid surface could have both a surface gravity low enough for the giant ants (and also high enough for human survival) and an escape velocity high enough to retain a dense and breathable atmosphere for many geological eras of time.
So some writers might want to be careful and set their story in a giant rotating space habitat with many levals. Giant ants might reside in some of the inner levels where the simulated gravity is very low, while humans may live in some of the outer levels where the similated gravity is much higher, similar to that of Earth. The humans would travel up to the ant levels to work at tending their domestic ants and using them for whatever purpose they use them for.
Part Three: How Much Oxygen is Neeeded?
The question says:
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> if there were giant ants (their gigantism is due to high O2 levels)
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And I have explained that high O2 levels might possibly be necessary for giant ants but they are not sufficient for giant ants, because a low surface gravity or similated gravity would also be necessary for giant ants.
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> Arthropleura (Greek for jointed ribs) is a genus of extinct millipede arthropods that lived in what is now North America and Europe around 345 to 290 million years ago,[1](https://en.wikipedia.org/wiki/Square%E2%80%93cube_law#Biomechanics) from the Viséan stage of the lower Carboniferous Period to the Sakmarian stage of the lower Permian Period.[1](https://www.rand.org/content/dam/rand/pubs/commercial_books/2007/RAND_CB179-1.pdf) The species of the genus are the largest known land invertebrates of all time, and would have had few, if any, predators.
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> A. armata grew to be 2.5 metres (8 ft 2 in) long.[4](https://en.wikipedia.org/wiki/Oxygen#Build-up_in_the_atmosphere) Tracks from Arthropleura up to 50 centimetres (20 in) wide have been found at Joggins, Nova Scotia.[5](https://en.wikipedia.org/wiki/Dihydrogen_monoxide_parody) In 2021 a fossil was reported, probably a shed exoskeleton (exuviae) of an Arthropleura with width of 55 centimetres (22 in) and an estimated length of 1.9 metres (6 ft 3 in) to 2.63 metres (8 ft 8 in).[2](https://en.wikipedia.org/wiki/Square%E2%80%93cube_law#Biomechanics) Arthropleura was able to grow larger than modern arthropods, partly because of the greater partial pressure of oxygen in Earth's atmosphere at that time and partly because of the lack of large terrestrial vertebrate predators.[6]
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So higher levels of oxygen in the atmosphere did help land arthropods grow quite large. The reason for that is that they had many tunnels in their bodies open to the air to let oxygen freely enter their bodies, and the higher oxgen levels enabled sufficient oxygen to reach deep enough into their bodies.
With the lower oxygen levels in today's atmosphere, the inner parts of their bodies could not get enough oxygen to live.
So you might want to increase the oxygen levels in the atmosphere of your fictional world to what they were in the era of giant land arthopods so your giant ants can be as giant as you want.
But the body plans of all known ants seem to be very much different from those of *Arthropleura*. *Arthropleura* were shaped sort of like hallway rugs, with bodies several times as long as they were wide, and several times as wide as they were high. Being thin in one of their dimensions vastly reduced the the distance that atmospheric oxygen had to diffuse to keep their innermost parts oxygenated.
In contrast, giant ants with the mass of *Arthropleura armata* hae much more rounded cross sections. Thus many parts of their bodies would be too deep inside to be oxygenate even if the atmospehre was as oxgen rich as when *Arthropleura armata* lived.
So some writers might think that it would be a good idea to keep on increasing the oxygen in the atmosphere of the imaginary setting until there is enough to penetrate even to the innermost parts of the giant ants.
Part Four: The Boy Who Cried Dihydrogen Monoxide
In 1997 a 14 year old student brought the greatest amount of publicity to the chemical named Dihydorgen monoxide, pointing out many examples, as others did before him, of harm caused by it. And it is true that Dihydrogen monoxide has often been deadly to humans.
Since "di" means 2, and "mono" means 1, it should be easy to figure out that a molecule of Dihydrogen monoxide contains 2 hydrogen atoms and 1 oxygen atom. Thus its chemical formula is H2O - making it water, which is deadly in some cirumstances but also absolutely necessary for life.
<https://en.wikipedia.org/wiki/Dihydrogen_monoxide_parody>
In medicine, biology, and chemestry there is a saying that "the dose makes the poison". Nothing is poisonous if in small enough quantities, and everything is poisonous in large enough quantities.
"Everything" includes oxygen. Too little oxygen in the atmosphere means that humans and most other lifeforms die. Too much oxygen in the atmosphere means that humans and most other lifeforms die.
There is a section on the atmospheric requirements of humans in *Habitable Planets for Man*, stephen H. Dole, 1964.
<https://www.rand.org/content/dam/rand/pubs/commercial_books/2007/RAND_CB179-1.pdf>
Dole discusses atmosphere in pages 13 to 19. He says that humans need an inspired partial pressure of oxygen of about 60 to about 400 millliemters of mercury, as compared to the sea level oxygen pressue of 160 millimeters of mercury. So the maximum tolerable pressure of oxygen is about 2.5 times the pressure of oxygen at sea level in Earth's atmosphere at the present.
The present oxygen partial pressure of 160 milligrarams of mercury corrisponds to 21 per cent of the volume of the atmosphere.
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> Since the beginning of the Cambrian period 540 million years ago, atmospheric O
> 2 levels have fluctuated between 15% and 30% by volume.[85] Towards the end of the Carboniferous period (about 300 million years ago) atmospheric O
> 2 levels reached a maximum of 35% by volume,[85] which may have contributed to the large size of insects and amphibians at this time.[86]
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<https://en.wikipedia.org/wiki/Oxygen#Build-up_in_the_atmosphere>
So when oxygen was 35 percent by volume, it would have had a pressure of about 266.66 mililmeters of Merury. If that was when *Arthropleura armata* flourished, inceasing the oxygenpressure could create somewhat creatures with its body plan, until oxygen pressure became about 1.5 times as great, at about the human limit.
Increasing the oxygen pressure beyond 400 millimeters of mercury to make the giant ants more giant would make the atmosphere unbreathable for humans, making it impossible for humans to interact with and domesticate the giant ants.
So perhaps you need someone more knowledgeable about such matters to calculate whether giant ants of the size you envision can interact with humans in the same atmospheric pressure and the same gravity, or whether they have to segregated by atmospheric pressure and/or gravity.
If the later is the case, then possibly your story would require the humans live in high gravity low pressure regions near the outside of a rotating space habitat and travel "upwards" and cross through airlocks and wear breathing apparatus while in the high pressure and low gravity inner regions where their domesticated giant ants live.
[Answer]
"Domesticated" means, that they are artificially bred and their behaviour is modified, by breeding, to suit our needs. So, for example, honeybees are domesticated to be less aggressive and produce a greater surplus of honey than their wild ancestors would have.
So if we can domesticate honey bees, we can domesticate giant ants. But in the a period of a few thousand years of domestication, there are limits. Just as we haven't completely removed the instinct to sting from honeybees, nor the instinct to bite from dogs, your giant ants will have many behaviours that are similar to their wild ancestors. And if your giant ants are no more intelligent than regular ants, there is no reason to think it would be possible that your domestic ants would be intelligent. They would not be trainable, or follow commands.
So think "honeybees". You ants would do "ant things", but you could imagine behaviour modifications, such as reduced aggression, that would make them more useful to humans.
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My first thought was "its impossible without being eaten". But it would actually be possible IF its the right species.
Now for this answer I am assuming these ants arent just literal scaled up ants, but properly proportioned ants that evolved to be that size (like a coconut crab isnt a scaled up normal crab).
Ants have evolved thousands of species. Some of the now extinct ones were small colonies of just a tens to a few hundred individuals, these would likely be better suited for enlargement over the millions-per-colony ants due to the food and space requirements.
Some species have cooperative relationships with other species. Like a bush that provides food in return for protection against parasites and animals that try to eat it.
Some species farm both plants and animals, picking up lice and planting them on the roots of plants so the lice are protected and the lice produce food the ants desire (and an emergency meat storage in times of crisis).
If you have a species that has for example Corvid (Ravens, Crows etc) intelligence then it doesnt have to be too large and would be fully able to create cooperative relationships with humans that provide it with regular food or support it with generating food. This would lead to the possibility of breeding as humans would be able to (attempt to) influence which ants from which colony can mate with a queen. Humans would also be able to train the ants to some degree to support agricultural endeavors, like digging and maintaining irrigation, clearing weeds, eating or scaring pest animals and providing protection to the humies that offer it food it might otherwise not have access too (say sugary goods).
If you on top of all that provide protection from the elements by building stuff over their living area's and provide the materials they need to improve their own homes they will most definitely want to support your endeavors.
So yes, with the right species and conditions ants would absolutely make for domesticated animals.
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There seems to be a trend with the oldest civilizations (Civilizations being urbanized societies with a government and social heirarchy) starting around river valleys surrounded by desert; the Egyptians, Sumerians, and Harappans as examples. The issue is, they are all located around a hot desert climate. While our Earth as we know it today has no major rivers flowing through a cold desert, my constructed world has plenty, so it'd be essential to know if that was possible.
My research in this hasn't yielded many answers, and the only thing that I've really found is that parts of the Yellow River flows through a cold steppe. This isn't really helpful to me though, since I have large rivers going through large cold deserts in my constructed world.
Basically, my question is if a civilization could develop on its own around a river valley in a cold desert climate. I apologize if the answer should be obvious to me. This is assuming a technology level similar to the ancient Egyptians or the Sumerians around 2500 bce.
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Ancient civilizations flourished around rivers in warm (Mesopotamia) or hot (Egypt) climates because the combination provided excellent conditions for agriculture.
But we do have ancient(-ish) civilizations which developed around rivers flowing through cold deserts.
* The [Tarim basin](https://en.wikipedia.org/wiki/Tarim_Basin), in the [Taklamakan Desert](https://en.wikipedia.org/wiki/Taklamakan_Desert), was the home of the fascinating [Tocharians](https://en.wikipedia.org/wiki/Tocharians) and of their mysterious predecessors from whom we have the [Tarim mummies](https://en.wikipedia.org/wiki/Tarim_mummies).
* The entire [Transoxiana](https://en.wikipedia.org/wiki/Transoxiana), the strip of land between the [Amu Darya](https://en.wikipedia.org/wiki/Amu_Darya) (formerly Gihon, formely Oxus) river and the [Syr Darya](https://en.wikipedia.org/wiki/Syr_Darya) (formerly Seyhun, formerly Jaxartes) river is a cold desert, part of the [Kyzylkum](https://en.wikipedia.org/wiki/Kyzylkum_Desert) desert, the Red Sands. Transoxiana has a long and fascinating history.
The city of [Samarkand](https://en.wikipedia.org/wiki/Samarkand), on the [Zerafshan River](https://en.wikipedia.org/wiki/Zeravshan_(river)), the "Spreader of Gold", an *almost* tributary of the Oxus, is among the oldest continuously inhabited cities in Central Asia.
On the same river lies [Bukhara](https://en.wikipedia.org/wiki/Bukhara), another ancient city with a resplendent history.
To the north, on the banks of the Oxus, lies the splendid oasis of [Khwarazm](https://en.wikipedia.org/wiki/Khwarazm). It was the birth place of [Muhammad ibn Musa al-Khwarizmi](https://en.wikipedia.org/wiki/Muhammad_ibn_Musa_al-Khwarizmi), author of the pivotal [*Book of Calculation by Completion and Balancing*](https://en.wikipedia.org/wiki/The_Compendious_Book_on_Calculation_by_Completion_and_Balancing); medieval Europe called him *Algorismus*, and translated the title of the book as *Liber Algebrae*, using the Arabic al-jabr "addition" or "completion". A civilization which gave us both the word "algorithm" and the word "algebra" was definitely *important*.
What is true is that while all these civilization appeared and endured using the resources of their cold deserts and mighty rivers, the actual *thriving* was due to trade. In the case of the examples given, the trade was the trade on the [Silk Road](https://en.wikipedia.org/wiki/Silk_Road): the Tarim Basin, Samarkand and Bukhara are directly on the Silk Road, and Khwarazm, a little to the north, was a major supplier of provisions and trade items.
In conclusion:
* Yes, we do have old civilizations which appeared and endured on rivers flowing through cold deserts.
* Remember that a cold desert usually has warm summers, exactly because it is a desert. (Unless it is located in a frigid zone, that is.) Warm summers plus river make for good conditions to practice agriculture. The cold and dry winters are a great incentive to organize a civilization!
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A large river valley is almost certainly the only location in a cold desert climate ecosystem where a civilization of any type *could* develop. There are two problems, the first of which is water. For civilizations to develop you need a location that is fertile enough and well irrigated enough to support a significant population for an extended period of time (multiple generations) in a relatively sustainable/consistent manner i.e. more average to good growing years than bad ones. And the local climate along the length of a broad river valley should be less harsh/sustain a more complex ecosystem than the desert plains around it.
The second one is domesticated crops and animals. Your culture would have to have access to at least a limited range food crops, root vegetables, grains, fruits, gourds, leafy greens etc and domesticated animals. The latter is probably not as much of an issue because cold deserts can and do a support nomadic herdsmen and hunter gathers. So your culture can inherit a tradition of animal husbandry.
The crops are another issue. I'm more than happy to be proven wrong but as far as I am aware cold desert environments don't naturally host a wide range or variety of traditional food plants. That means any crops (and you will need crops) have to be either cultivars of wild plants found growing naturally in the valley when the original settlers arrived generations ago or else be traded 'up' river or across the desert from other regions where they do grow naturally.
Your river valley doesn't have to be a 'Garden' of Eden' in terms of all the varieties of crop plants grown there but you will almost certainly need at least half a dozen different crops across a wide range of types to produce healthy/balanced diet for your citizens.
You might look at some of the crops grown by ancient South American peoples as examples of what could be grown in different climate ranges.
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**Cereals crops are must**
Any civilization needs cereals crops to survive.
**Freeze injury of rabi or winter cereal crops**
Wheat, oat, barley, gram are winter crops.
If at heading and flowering stage, the temperature goes below 0°C, the crops are severely damaged as explained [here](https://fieldcropnews.com/2020/05/how-will-the-cold-temperatures-effect-cereal-crops/).
**Suitable temperatures for kharif crops**
Rice, maize, millet are kharif crops.
As explained [here](https://www.yourarticlelibrary.com/cultivation/cultivation-of-rice-suitable-conditions-required-for-the-cultivation-of-rice-6-conditions/25491), they are grown where:
* The average temperature during the growing season is between 20°C and
27°C.
* Sunshine is abundant during their four months of growth.
* The minimum temperature does not go below 15°C as germination cannot
take place below that temperature.
**Such cultivation conditions are not present in cold deserts.**
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[Question]
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In my story, there is a character that is capable of using magic or an ability that allows them to "teleport" as long as they are in contact with the ground or the area that they want to use it on with at least one hand.
For example, in the middle of a circular arena 100m in diameter, as long as they are touching the floor (with a hand), they can teleport anywhere as long as it is "connected" or still physically part of the arena (which means that any floating rocks won't count, and they wouldn't be able to use it to get away from the arena in the case that it is floating).
What limitations can be set on it to avoid being too powerful, and with limitations in mind (or not), what would be the best type of magic/ability to use with it? (disregarding earth magic/manipulation)
My thoughts were to limit it to 75-100m and only usable every second or two, and to be used with wind magic mainly (if mist or fog can be made using wind magic).
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**Limitations in other places**
Positioning is powerful. Incredibly, insanely powerful. In any engagement this is more important that the weapon your holding, as the position in regards to your opponents dictate what is effective.
If you let someone teleport at will with some items every few seconds as long as they have contact with solid ground in even just a 50m distance, they are very hard to stop. They can move out of range, get a knife, gun or crossbow and teleport closeby to fire at the target. Before they can react effectively you're gone. You can get behind them with a knife or club and the target has so little time to react. In the movies they often teleport about with high predictability for the audience. Your teleporting person won't do that. She/he can just teleport away so the target doesn't know when you'll teleport back with whatever assortment of weapons they deem most appropriate.
Now imagine teleporting only the person. All clothes and weapons left behind. It might be more fair, but thus person is still Incredibly dangerous. Teleporting to weapons and firing/throwing them from a distance is still very powerful. Even at unarmed combat they'll be dangerous, lije a boxer that always can start behind the opponent. Medieval armour? Push them over or hit the knee from the back. Then attack at leasure with close combat for armoured and immobilised prey. More modern armour? They are still very vulnerable to many unarmed attacks.
Don't get me wrong. Being naked drastically decreases your chances. Still it has such great potential for someone learning to use this telepotation in fighting. It can even be a last resort. Fighting normally until *surprise* all clothes and weapons fall empty on the ground. While the target is confused about what just happened, the neck is twisted or a rock is banged to the head.
To decrease the effectiveness of teleportation you can do many things. A few here:
* Naked.
* Costs physical energy.
* Costs mental energy.
* Causes temporary disorientation, as the mind isn't where it expects to be.
* Telegraphing the teleport on both starting and ending locations.
* Damages the teleporter.
* Requires immense concentration.
* Can be dangerous and possibly end up inside the solid stuff that's being touched, so to reduve this chance teleportation is done sparingly.
* Decrease frequency.
* Decrease area.
* More limitations in general for teleportation.
[Answer]
Do a little twist on some old thaumaturgy tropes.
You want it to be contiguous floor or some such, so make it where a change in flooring would be a block. Tile floor acts as one piece, wood another. This sets up people who are aware of the ability to build in some limitations. If you can teleport, it's less effective if you can only do it in a two foot square because of the decorative pattern of wood, saltillo and wood tile. This is because there is no connection between the kinds of floor, so the thaumaturgical connection wouldn't work.
Another limitation could be with the cool down and cast times. If your guy has to wait 10 seconds to teleport, or it takes 10 seconds to cast and requires focus to do so, then that makes it less effective combat tool. 10 seconds is a very long time in a fight.
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Instead of true teleportation, have them move within the ground as if it were not solid. They can "merge" with it and move around really fast - maybe so fast that for practical purposes, it is much the same as teleporting.
The advantage of this is that it prevents the user from abusing this power. For example, in the teleportation model you propose, one could teleport from an arena to a floating island if a rope connects those. The user could throw a rope with a hook on a floating island, and then they could teleport at will. But if they have to physically move through the ground, this prevents them from moving through ropes, chains, or other narrow passages because their body will not fit through the passage.
An example of such "teleportation" is the [Inkling in Super Smash Bros. Ultimate](https://www.ssbwiki.com/Inkling_(SSBU)). She is able to become a puddle of splashing ink and move around the scenario. In this manner she can avoid most attacks because they will pass over her, and she can move extremely fast from one point to another, but this does not allow her to move from one floating island to another.
Another example is Zetsu, from the animé Naruto. This guy is able to practically "fly" inside rock and earth. This allows him to disappear from one place and appear in other really fast, but also does not allow him to move from the ground to a floating place (and there have been floating places in the animé).
[](https://i.stack.imgur.com/iXmBK.gif)
And finally there is King Bumi in Avatar: the last Airbender. This technique shows in the few first and few last seconds of [this video](https://www.youtube.com/watch?v=PTu5t2nhOrw).
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**Make her as powerful as you imagine she is.**
Because that is where the awesome is! You worry your character will be overpowered which means you can imagine her doing overpowered stuff. You worry she will be able to do stuff no-one can counter. And I think you like it. **Have her do that stuff!** Please! Have her totally thrash her opponents with her overpowered skills! That is what I want to read.
But then how to beat her? That will be more fun to figure out than how to limit her. You do not need to figure out how to limit the character you can imagine. You need to imagine other characters on her level. Figure out how her opponents can best her or at least equal her. Or team up with her? Woo! Yeah!
[Answer]
One of the easy ways to eliminate the more extreme abuses is a line-of-sight limitation. You can only teleport to a location if you can currently see it. That puts a hard cap on the range of the effect, and introduces opportunities for opponents to disrupt it (fight indoors, obscure their vision, etc). Teleporting somewhere you can't see isn't a really good idea anyway, because you have no idea if the laws of physics will even permit you to exist in that space (ending up inside a solid object would be game over for you).
For an extra twist, you can limit how close you arrive to your target point to be dependent on how clearly you can see that point. For example, stick out your thumb and hold it at arm's length, covering up your target. The area of your thumbnail represents the size of the area in which you might end up. When teleporting across the room, that area is only a few square inches so accuracy isn't really an issue. Teleporting to that hill far in the distance could be a problem, though. That same thumbnail-sized area is bigger than the apparent size of the hill, so you might miss your target completely and end up somewhere undesirable.
Any sort of teleportation is going to be rather overpowered in combat, simply because it lets you evade attacks nearly perfectly. The most straightforward way to reign in the usefulness would be to make teleportation not an instantaneous process. The caster has to focus/concentrate/channel for a period of time before teleporting. This prevents it from being used *reactively*, which is where most of its overpowered nature comes from. It also leaves your caster vulnerable just before they teleport, which means it has to be used much more strategically. Great for sneak attacks or initiating fights but once the fight starts, you can't fight invincibly like Nightcrawler in X-Men United.
You can even incorporate this into the lore if you want. Teleportation is a form of shadow magic. The caster channels their magic to send their shadow to a distant target location. Once the shadow reaches the destination, the caster will suddenly find themselves there as well (like how you can travel to the other room and turn on the light to make your shadow appear at *your* location, only it works the other way around). The shadow travels at a certain speed, say, 10x the speed of the caster. The caster would then have to channel for some brief minimum length of time *plus* however long it takes for the shadow to travel from A to B. That won't completely preclude its use as a combat escape mechanism, but will require your character to earn themselves enough breathing room to complete the cast.
[Answer]
### "Electrical magic"-based teleportation: requires a conductive path.
Suppose your teleportation magic makes your teleporting person act as a self-propelled surge of electrons. As long as they are in physical contact with a conductive surface or conduit, they can teleport to any other point on it with enough space for them to materialize at the other side.
This would impose pretty strong limitations on general use.
* Most dirt/rock/concrete and other surfaces one could stand on would not be immediately usable.
* Bodies of water and wet surfaces (eg. during/after rain) would be easily traversable.
* In urban settings, perhaps a likely use would be teleporting around the electrical grid between points of exposed wiring.
* To use it in non-conducting settings, the teleporter would probably carry coils of wire with throwable weights or a grapnel gun, or perhaps something that splashes water, to deploy in the field.
If you want to impose limitations based on frequency, you can consider heat generated by the teleporter's passage through the medium. If they teleport across a thin film of water on pavement, perhaps the heat of their passage would evaporate too much water for them to take the same path back. If they teleport through a normal circuit in a suburban home, perhaps they'd set off the breaker and not be able to go back through that line.
Related to this, you could add a limitation that they must know, ahead of time, where they are going to rematerialize. Perhaps in electron-surge form, they cannot perceive the world outside of their conductive conduit--at risk of death or severe injury, they must be certain they are re-materializing in a place with sufficient room for their body.
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Please be much more imaginative. Either explain or drop any difference between “using magic” and how else they might "teleport”.
Explain how a “hand” matters, rather than a foot or shoulder, knee or elbow.
A “circular arena…” is one thing. A “circular area…”; even “a circle…” very different. You might not care.
Your “floating” might have a use, or not.
If it is written that limitations should be set to avoid anything being too powerful, you might be able to Post where or when.
To disregard earth magic/manipulation when your Question is solely about “contact-based teleportation”, as explained by you as being in contact with the earth, seems like a contradiction in terms.
Limit what you want to 75-100m, usable only every second or two and with wind magic mainly.
Specify whether you’re writing about one second or two.
Name anyone who in a crisis, didn’t see all the difference in the world between one second and two.
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First, you already limited the most unfair application by limiting it to ground use :
The dropping someone off in space and coming back.
This was also only usable if you allow forced teleportation of others. Which you can limit (maximum weight, maximum volume or needing the consent of other living beings to move them)
What you were going for in your thoughts as limitations are frequency and range. And those can be linked to have an adaptive cost:
* Teleportation can take time to prepare and the longer you prepare the farther you can go. For example, by preparing 1 second you can just teleport 1m away but if you prepare 1 minute you can move 100m in one go.
* If you need reflex teleportation, you can reverse the relation to time and instead of preparing you have a cooldown during which it is impossible to teleport after teleporting.
You can also make a limitation on precision. The farther you go, the less precise the teleportation is, which could be dangerous depending on how teleporting in a wall is handled.
As for what magic to use in addition to it, I don't see why that'll be necessary, adding anything in addition to teleportation is already overkill.
You thought of Earth Magic manipulating the ground and changing what's accessible, but that's true for any magic creating/manipulating solids (Ice at least and Plants if you allow teleporting through living beings). Now if you really want to add magic, there are a few kinds that works well with it:
* Any Illusion Magic that makes it seem you didn't move yet
* Any Stealth Magic that allows to teleport undetected
* Any long range Magic that allows Hit&Run tactics
If you want another magic, that seems to combo well but still have limitations, any other contact-based magic will work well.
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There is this great and dangerous forest in this world, way more bioproductive than anywhere on earth. The climate is humid subtropical, with cold but not freezing winters. There is plenty of fruits, nuts, herbs, roots and even some wood (palmetto) to be eaten in every season, even in the winter. There is also plenty of game, from hares to mammoth-size elephants. There is also small pockets of grassland all over the place which are dragons' hunting grounds.
I want that a race of humanoids (let's call them elves for simplicity's sake) to evolve in this forest and neither agriculture nor animal husbandry are options. Any livestock could be wiped out by some predator and farm will just be free food for wild animals. The only livestock they were able to domesticate to some extent is the Giant Deer, which can be used as a pack animal, a mount and a source of milk, but feeding on them is a terrible idea, they are dangerous, more tamed than truly domesticated and can quite easily flee to join a wild herd.
The thing is, I don't think the local fauna can keep up with a permanent settlement. All things I read about hunter-gatherers seen to indicate that they will overhunt the local prey population and than they have to move to somewhere else.
Also, I've research some sedentary hunter-gatherers and they usually only happen near coasts and other water-bodies that help providing enough food through fishing. However being in a forest mean that they rely almost exclusively on the local supply of food.
To complicate things even more:
1. I want them to be carnivores, not hypercarnivores, but at least mesocarnivores (30-70% of meat in their diet).
2. They must have big enough settlements to make great stone fortresses, otherwise a elven-city is just a big stockyard to some big predator. I cannot express this enough, but even the elephants are hunted in this place and they are not even the biggest prey to be found.
To make things a little easier:
1. They make insanely good bowmen, they are stronger than humans and use this strength to power bows that shoots harder than all but the strongest crossbows.
2. They can move through the forest relatively unharmed despite the crazy amount of predators and dangerous prey.
3. The Giant Deer extends their hunting grounds greatly.
4. The forest is only sparsely populated, but again individual settlements are quite large.
5. They are quite good engineers as well, so they could easily outdo a similar-size human settlement.
6. I am trying to make the world as low-magic as possible, but I can and will use it to implement a solution that is cool enough
So, any idea on how to make this work? Either on the elven societies or on the forest itself?
Edit: some details that I forget to add but are clearly relevant
1. Alternatives to farming is a non issue, the forest are more bioproductive than any crop would be, and on top of that animals would feed on the crops just as they would in the forest, so agriculture is just more work for less food overall. The real problem is how a big sedentary communities of mesocarnivores will feed themselves without exhaust the local fauna.
2. They can and they trade with the rest of the world, but they do not colonized the forest, they evolved in it. So I think self sufficiency is a must.
3. The other problem with trade is that to any one but them, this forest is hell on earth. No merchant in their right mind will go there, the elves are the ones to reach outsiders. And when they do is for luxury goods.
4. While hunting parties are a thing, they can not go that far away. They build fortress for safety, if you go into the forest and don't come back within a week they just assume you died.
[Answer]
## Balance your town's needs relatively to its hunting area coverage
It depends a lot on the resources production/km² you can get of your land. Then balance it against how many settlers you want and the area you're willing for them to travel in. This can be summed up in three main points.
### How to reduce the town's needs?
Unfortunately, reducing a town's needs is a hard thing to balance out; Yet you can still play around a little. The first one to come into mind is by interacting with other races, like trading, which even alone can overcome any food difficulty. But you can also make the elves raiders and pillage everything that is not their own, too.
But let's say that they are the only race around -as you pointed out-, living all the same, sedentary hunters way. Everything that reduces efforts and therefore food consumption can help. For instance, have them sleep/meditate due to their culture or their genetics to reduce their needs. Then, live lazy, hunt smart! Put traps, and just let your meal fall into them. This can be applied to fruits gathering, too, similar to how Corsica inhabitants put nets to gather olives from trees without moving an inch.
One final, very important note is to give them ways to conserve food. If they can conserve it with salt or by smoking them, less waste can be made, notably after they took out that 3-ton mammoth. Otherwise, they'd better have a really big stomach! This goes along with overall careful resources management : Don't be greedy, or you'll end with nothing in your belly.
### How to increase land production
Given that they are living in an subtropical area, plants and animals should be numerous due to a good temperature and lots of humidity. This is especially true since there are giant-sized species that, by damaging big trees, helps in renewing the forest with new, smaller plants, which in turn brings new games to hunt. In general, a thriving life community with a large biodiversity will grants lots of resources naturally.
Also, you can make some big animals -or big herds of small ones- migrate in a, predictable, cyclic way. This can be further supported by giving them only one path to reach their destination, so that they will always come by your town. If food come from other places, you need less food from your own land!
### How to extend your hunting area coverage?
If you extend your hunting area, you will not only increase your land total, gatherable production, but also reduce how elves' activities will reduce it. Indeed, as your village will grow, the more people there are, yes, but preys become more likely to avoid the surrounding area of your village. Even if they're not smart, they're (usually) not fool either, and whether due to not finding their food or seeing their buddy with an arrow coined in them, they won't stay there for very long.
So hence, extend your coverage! You can set small fortress lodges several kilometers (or even more!) away and around your village and organize hunting parties ranging from two-three days long to several weeks to get food for the village. When an area is becoming empty, they go to a new, well-known location instead while the old one resplenishes. Note that you'll absolutely need a way to keep food safe and edible the longer your expeditions are.
Another way is to allow them to hunt on two (or more!) levels : If your village is standing on top of a large underground cavern complex, it multiplies the area they can find food from. Also, animals living in caves are less likely to flee the elves, since, well... They don't have much way of fleeing them : Leaving the cave as a subterranean species is not ideal, and they may not be able to dig into other caves, either.
## Tiny, hungry conclusion
All in all, it's much easier than you may think, as long as you give them a good configuration. Setting them in a tropical area is already a very good start, and you may need only one or two tools to make nice-looking villages, three or four to make a sizeable town.
[Answer]
# Forest Management as a Substitute for Agriculture:
With the abundance of foods, and an organized society, do what people have been doing with elves for years - portraying them as forest rangers and land management experts. They don't really farm the forest as much as guide it to be more amenable for their needs. The foods that support the animals they hunt are spread wide, and the plants distasteful to predators thrive. Thorn hedges divide the land into management districts run by the equivalent of nobles. The elves live in more of a symbiosis with the land, a very conscious one, where some areas are promoted to allow big prey (to keep the dragons at a distance) while some areas are protected as places for small, less appealing (to giant predators) prey animals that the elves prefer.
The harvesting of animals could be coordinated with natural conditions, like hunting seasons managed around breeding seasons, only hunting males to allow species to reproduce, controlling smaller predators through hunting to eliminate competition (while still maintaining balance). A fortress-centered, highly organized society would be running a sophisticated and highly organized program. Meat would be shipped rapidly or dried (with herbs disagreeable to predators to prevent theft/attack).
I would advise small animal husbandry, like rabbits and chickens or snails, things unlikely to be significant enough to be desirable to predators (and sheltered inside buildings) but still allowing meat production in controlled conditions.
As the elves gain control of their environment, they could potentially alter the selection of foods to the point of being able to starve out the giant predators (this is what happened to such animals as short-face bears, terror birds, and dire wolves in the Americas at the end of the Ice age - prey got small). To keep this from happening, you may need to protect the land from the Elves. I would suggest druidic magic for the Elves, as this both helps them shape nature while simultaneously giving them motivation NOT to wipe out species they find problematic.
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All life on Earth thrives on equilibrium. When a predatorial species hunts too much prey, then its next generation suffers and their numbers dwindle.
Also notice that natural selection makes sure that both prey and predator are adequate to each other. This process is called [coevolution](https://en.wikipedia.org/wiki/Coevolution):
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> In biology, coevolution occurs when two or more species reciprocally affect each other's evolution through the process of natural selection. (...) Each party in a coevolutionary relationship exerts selective pressures on the other, thereby affecting each other's evolution. Coevolution includes many forms of mutualism, host-parasite, and **predator-prey relationships** between species, as well as competition within or between species. In many cases, the selective pressures drive an evolutionary arms race between the species involved. Pairwise or specific coevolution, between exactly two species, is not the only possibility; in multi-species coevolution, which is sometimes called guild or diffuse coevolution, several to many species may evolve a trait or a group of traits in reciprocity with a set of traits in another species (...)
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The elves simply evolved (not only biologically but also culturally) to not overhunt, but rather stay in equilibrium with their environment. Unlike men, they do not take more than they need from nature.
Another possibility is:
# Trade
The elves don't farm, but maybe someone else does. Say there are dwarves living underground. They farm mushrooms, and they trade their excess of non-hallucinogenic ones with the elves in exchange for things from the forest (i.e.: the dwarves might fashion their clothes out of vines, and wear lily pads as hats). Since the dwarves live underground, they can escape the dangers of the forest and reach the elven fortresses by tunneling to them.
[Answer]
from op /farm will just be free food for wild animals/
**This is why they farm.**
Free food for wild animals means wild animals will come and that is what the elves want.
Mature forest does not offer as much food for large herbivores as open areas do - the trees shade out grasses and favored vegetation for deer and the like.
Your elves clear areas of forest and plant grasses and crops which provide food for their favored prey items. They groom the forest to favor fruit and nut trees that feed their prey species. These plots are tended to make the the forest does not reclaim them.
You can find a lot on line about managing lands to facilitate deer hunting. Most of what I see pertains to temperate forests but there is no reason a tropical forest could not be managed and even "farmed" to maximize carrying capacity for desired prey species.
[Answer]
If your worry is that local prey won't suffice all year round, and your elves are too sedentary to want to move to new hunting grounds (or travel is otherwise too difficult)
bring the food to them!
Your forest is central to a migration route. There are huge lands - or seas with habitable or nestable islands to the North (ideal climate in northern hemisphere summer) and likewise to the south, providing havens during the northern winter.
So, twice a year, at the changing of the seasons, all the food you can imagine flies overhead, or herds through the passes and traditional trails.
Perhaps deserts or a long sea crossing leave the migrants exhausted, so having to other choice they will occupy your oasis for a few days or weeks, then proceed to their safe lands.
This means a few weeks glut; and probably festival; and a communal effort to smoke, salt, dry or preserve whatever your people need to let the local fauna thrive, and get you through the lean season on smoked goose (and the occasional local rabbit) until the next migration.
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Pottery.
Pottery was vitally important in the development of society. Its weight makes it difficult to carry, but a sedentary culture can manage it even without agriculture. The sedentary hunting and gathering culture in Japan underwent a population explosion when they invented pottery. And the big thing is that it allows you to increase food supplies. This involves all sorts of aspects. For instance, you can steam open (fresh-water) mollusks. You can cook tough and unpalatable parts of meat to make it feasible for the digestive organs to extract nutrition from it. (Cooking in generally is a way to extract more nutrition, and more easily, but boiling is going to make it even better than roasting.) You can boil water with plants you can't eat until the toxins are leached out and the rest is more compatible with your mostly carnivorous digestive system.
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## They existed in history.
There ware sedentary hunter gathers in history. They lived in place of extraordinary abundance, usually places with access to very easy fishing so with just a little investment in traps food will catch itself. All you need for a sedentary lifestyle is an abundance of food. Hunter gatherer societies end up with a decent amount of leisure time in places of natural bounty. Most of these societies don't exist any more because the places that make for this are also extremely attractive to societies with agriculture and better technology.
The pacific northwest being one famous example, where abundance was so extreme the potlatch came into existence, a sort of contest of extreme waste. Florida's shellfish coast being another.
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I want to create a world were soil mining is a major industry. Imagine a vaguely Earth sized world where almost the entire surface of the planet is under, ocean, ice caps or is a hot or cold desert with nonexistent or very poor soils.
Soil or soil like organic matter does exist, but only quite deep underground and the inhabitants are forced to dig soil mines so that they can bring it to the surface for use in growing crops.
How could such a strange state of affairs come about?
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**Glaciers cover the old landscape.**
[Preservation of a Preglacial Landscape Under the Center of the Greenland Ice Sheet](https://science.sciencemag.org/content/344/6182/402)
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> Continental ice sheets typically sculpt landscapes via erosion; under
> certain conditions, ancient landscapes can be preserved beneath ice
> and can survive extensive and repeated glaciation. We used
> concentrations of atmospherically produced cosmogenic beryllium-10,
> carbon, and nitrogen to show that ancient soil has been preserved in
> basal ice for millions of years at the center of the ice sheet at
> Summit, Greenland. This finding suggests ice sheet stability through
> the Pleistocene (i.e., the past 2.7 million years). The preservation
> of this soil implies that the ice has been nonerosive and frozen to
> the bed for much of that time, that there was no substantial exposure
> of central Greenland once the ice sheet became fully established, and
> that preglacial landscapes can remain preserved for long periods under
> continental ice sheets.
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In your world, glaciers cover what used to be fertile fields. Your people tunnel down through the glacier to access those fields and their soil. Under the ice, they may find other remnants of the world that once was.
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# Post apocalypse
The asteroid that killed dinosaurs did not kill all of them by direct kinetic strike. Most of the world was affected in two ways:
* Temperature on half of the world rose too fast due to increased pressure (caused by the flying debris, which did cover almost a whole hemisphere) - this would have cooked bacteria in the upper layers of the soil, making many lands sterile for a long time;
* The Earth was then covered by clouds of ash, which not only kept sunlight from reaching the ground but which also got deposited everywhere after some time.
If the world has been hit by an asteroid like that in recent eras, it may take a million years or more for land to recover naturally. If mankind was just getting off bunkers months after the asteroid hit and the dust has settled, they'll have to dig for Earth that has good nutrients, and will have to treat that soil in order to make it arable.
*In lieu* of an asteroid, a global nuclear winter would do. You have to dig through all that radioactive ash in order to get good soil. This may also happen due to [global warning](https://worldbuilding.stackexchange.com/questions/126675/how-could-you-create-a-95-effective-global-emergency-broadcasting-system#comment393493_126679) (not a typo).
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## The planet never evolved terrestrial macroscopic life
Soil is primarily made up of the decomposed remains of other life, so a planet where plant life never made it to solid ground will have all of it's soil in water and around its bodies of water, but the vast majority of dry land will just be exposed bedrock, sand, and volcanic ash.
Furthermore, most plants do not have roots capable of penetrating solid rock; so, even in places where the ground may contain the nutrients they need, they still rely on pioneer species break up the ground enough to create arable soil, and prevent erosion. Without this, any soil that might try to build up from the remains of microbial life will just be washed away or compress into sedimentary rock.
**Is this possible?**
Absolutely. Plant life only moved to solid ground on Earth about 475 million years ago, but Earth has had aquatic life for billions of years. So, if you were to just find an Earth like world that is 500 million years or so behind us on its evolutionary path, then you will not find usable soil on most of the dry land, but you will find soil in bodies of water where the remains of microbes have gathered, and been kept soft from constant exposure to water.
Using pioneer plants, you could begin terraforming this world's dry land into soil, but this process takes a few thousand years, and most pioneer plant species are not agriculturally useful. So, in the meantime, your colonists would need to rely on dredging up soil from rivers and lakes to create artificial topsoil.
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If your planet has only very little of natural land and the rest would be covered with water, then as soon as the inhabitants reach a certain number, the would have to get creative for food production, as there is only so and so much space for farming.
The first thing to do would probably be to move all housing and industry on platforms in the sea, but once that is done and all available natural land is filled up with farms, the only way to increase space for farming would be, to put soil on the platforms and farm there.
That of course means that the soil has to come from somewhere and as you don't want to destroy more fo the farming land you already have than is absolutely necessary, digging deep comes to mind.
Now bare in mind that soil is not dirt and it takes more than to mix the right amounts of nutrients and micronutrients with sand. The little critters living in the soil are just as important as all the nutrients, because they make them available for the plants.
That is why I would start the world with a bit of good soil, so the critters can be transplanted to the artificial soil.
A world like that would have to be very focussed on recycling all the organic material that is available. As it becomes valuable soil.
So this world would not actually be mining soil, there simply is no soil underground, just rocks, gravel and minerals. They would be mining the ingredients for soil and then make it.
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That is not too far from what we do now to make our crops grow, since soil depletes quickly as you grow crops. "Crops perform better when they have nutrient-rich soil. Healthy soils contain a balance of nitrogen (N), phosphorus (P) and potassium (K). These three nutrients help plants grow in different, yet each important, ways:
Nitrogen helps a plant’s leaves grow;
Phosphorus supports a plant’s root growth and flower and fruit development; and
Potassium is a nutrient that improves the plant’s overall health."
Google Potash mines images and you will get some great ideas for what an underground "soil" mine would look like. Potash is made of potassium.
Then you'd need Nitrogen--"Nitrogen fertilizers are made from ammonia (NH3), which is sometimes injected into the soil directly. The ammonia is produced by the Haber-Bosch process. In this energy-intensive process, natural gas (CH4) usually supplies the hydrogen, and the nitrogen (N2) is derived from the air." So rather than mining Nitrogen you would be manufacturing it. No doubt human waste could help in the processing...
Lastly you need phosphorus- "Most of the phosphorus used in fertilizer comes from phosphate rock, a finite resource formed over millions of years in the earth's crust. Ninety percent of the world's mined phosphate rock is used in agriculture and food production, mostly as fertilizer, less as animal feed and food additives."
Google phosphate mining and it appears that form of mining is usually strip mining on the surface. But... creative license..
So over all you need not come up with too fantastical of an idea which the world would have to mine soil. Since we already do. Any of your ideas, Global freeze, Global flood. Global disaster...
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If you look at human evolution, and movement to cities, you could take the angle of megastructure civilizations. These massive societies all contained in a few buildings around the world would still need to grow plants to feed people and to develop things like medicines. The thing with moving everyone inside though is that the population will still increase, requiring the need for more and more soil to produce food.
To make the "outside world" uninhabitable, you could pick from almost any list, authoritarian government mandate, nuclear war, supervolcanic eruptions, the return of the glaciers, or even an atmosphere that is in heavy deterioration which leads to heavy radiation of organic topsoil.
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In my conworld, the inhabitants have futuristic technology and use armour that is made of primarily wood but will absorb bullet impacts and even armour-piercing rounds. It is cited as being very fire-resistant, though after enough time has elapsed it will burn through. What would be the conditions required to make wood this durable? Keep in mind, the planet these trees grow on is 1.5 times as massive as Earth, and the atmosphere is much richer in oxygen.
[Answer]
In order for this to work, the composition of your trees would have to be VERY different from those on earth. Even dense wood is not particularly good at stopping bullets. A handgun round will generally penetrate wooden boards as much as 2-3 inches thick, and high-velocity armor piercing rounds from sniper rifles will go through as much as a foot or more of oak.
Those kind of thicknesses are pretty impractical for body armor, so you're going to need something pretty different.
Now, something that DOES grow naturally that IS bulletproof, or nearly so, comes from the animal, not vegetable kingdom. Some species of [Mantis Shrimp](https://phys.org/news/2016-05-mantis-shrimp-ultra-strong-materials.html) form structures in their claws that have incredible levels of shock resistance, and would easily generate both the protective levels you're looking for as well as being practical for use as armor.
Instead of trees like we have on earth, imagine something much more like a coral forest where the corals form these kind of structures as they grow. Your inhabitants can harvest them and repurpose them as protection. There's all sorts of potential there.
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This question made me smile, because I think there might actually be a tree on Earth that would stop a (lowish) caliber bullet.
I cut down a Black Gum tree (Nyssa sylvatica) that was shading too much of a garden (no great loss; my land had thousands of trees.) I cut in into lengths to split for firewood. It was dense and somewhat harder to cut than most other trees/wood.
But the real surprise came when I tried to split it. It **completely** overwhelmed my heavy duty hydraulic splitter. The [grain](https://www.woodmagazine.com/materials-guide/lumber/wood-species-1/black-gum) was so twisted every which way that I had to just give up and haul the lengths into the woods.
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> Because of its [twisted grain](https://www.uky.edu/hort/Black-Gum), black gum cannot be split so it has been somewhat spared by lumbermen. The resilient wood is good for making tool handles.
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and
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> The wood of the black gum has fibers not only interwoven but twisted to boot. And while modern tools and cutting edges can surmount this obstacle, even the sharpest ax and the most expertly wielded froe [a tool for cleaving wood] of yesteryear made little headway splitting it.
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Is an ax very much different from a bullet in shape?
Consider a tree that has highly twisting and interlocking fibers. A bullet can make some headway, but nothing close to what it can do to most woods with straighter grains.
If early settlers left it alone, it had to be formidable. Make your tree a bit more so.
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There are examples of biological systems depositing glass (diatom skeletons, for instance). Glass fibers encased in lignin in between the cellulose fibers would greatly reinforce a high-density wood (like teak or boxwood). The result wouldn't be "bullet proof" any more than modern body armor is "bulletproof" -- but it would be bullet *resistant* in much the same way. Layered scales of this wood, with padding between layers (made from the self-reinforced bark of the same tree?) could gradually absorb the energy of a bullet.
The tree that would have evolved to do this would have to grow in a silica-rich region (sandy soil, at a minimum) and would have an evolutionary need to grow tall, yet stand against strong winds. Think solitary redwood or sequoia -- instead of being protected by standing in a grove of similar trees, these are simply strong enough to keep standing and hold their branches in the most violent storm. The slow growth and long life cycle of these trees would, however, make the armor made from their wood relatively rare and expensive (especially after sustainability becomes a recognized concept).
[Answer]
As an actual wood by itself with no special preparations, almost certainly not, cellulose is just too weak to do this by itself if we assume equivalent structure to real-world trees. Even the highest density woods (which are so dense they sink in water) aren't going to get you close to a proper anti-ballistic material like modern body armor provides.
However, if you do some form of multi-layer laminate, you might get acceptable performance against ball ammo (that is, ammo that doesn't have an armor piercing core). Essentially, you're making armor out of plywood, except you want a whole lot more layers, and probably want each layer thinner than typical plywood (you can pack more in, and better see any imperfections in the grain of each layer during assembly that would lead to weak points). You'll probably want hardwoods for this (more durable), but most likely softer hardwoods (if they're too dense, they won't do a good job of absorbing the kinetic energy of the bullet). Even then though, you're looking at maybe stopping handgun rounds and some light hunting rounds, probably not military-grade AP rounds, and definitely not anything larger than about 8mm coming from a rifle.
[Answer]
Hardwood already is bulletproof. In fact, properly built and with enough thickness, it is proof against small naval artillery of the age of sail. It's actually rather impressive how little outside damage a 13-kilo cannonball does to the structure as it is just about at the needed power to penetrates a reconstruction of an 1864 frigate ship hull, [as you might see here](https://youtu.be/SvSDRCMuasc). Lighter and slower projectiles will bounce off, ones with more energy will do more damage to the structure. The problem is the needed thickness of the construction: That ship hull has about one foot of oak in three layers! Or you might want to listen to [Drachinifel](https://youtu.be/lIDu7NPLbwc) talking about the gunnery and construction of ships - and how they were damaged by the size of naval artillery. 6-pounders can't pierce such 12-inch hulls.
Ship hulls go in parts to 24 inches or more...
What are the problems and solutions to wooden armor then?
## Wood splinters
When hit hard enough, the wood will splinter and aid in killing whatever is behind, adding shrapnel. To combat this, you need quite thick constructions, which are likewise bulky.
However, you can *reduce* the need for thickness by layering, and only needing to withstand smaller and slower projectiles, such as arrows on long-range.
## Wood is inhomogenous
Well, that doesn't help against handguns, but the splintering is an effect of wood being inhomogeneous. There are fibers, all rather ordered, and they are not very interwoven. Now, we could fix part of this by layering the wood crosswise, but that was already what was done with the ship hulls. So we need to do something more.
## Wood Ages
Did you know that wood ages and gets *better* at stopping projectiles? Old Ironsides, aka [USS Constitution](https://en.wikipedia.org/wiki/USS_Constitution), was built from *particularly* old boards, and was as a result much harder to wound. What happened to her wood in aging - or as the shipbuilders call it *seasoning*? Simple, the resins in the wood cure and harden, making the wood fibers much harder to break apart from one another.
## Laminated resin-impregnated wood
If our armor makers use a laminated setup of wood, possibly even quite thin boards or even strips woven into mats, and impregnate those with resin, layer and press them together, then you can end up with a structure very much akin to carbon fiber plates. Such plates are used in hard body armor at times, but generally, steel or ceramics are superior in performance in combination with flexible fibers such as Aramids.
## Conclusion
Wood isn't good to make body armor past the age of arrows and even then is mediocre compared to a metal plate or ring armor.
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The simple answer is "No".
Wood is based on cellulose, and cellulose has very low tensile strength, compared to "strong" materials like kevlar or steel. Cellulose-based materials just can't be "bulletproof" in a traditional sense (ex. to make wearable armor).
However, plants in your world can potentially be made of other fibers. You can even have some kevlar-based vines, if you like.
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[Question]
[
In my universe, humans nuked themselves in a war so thoroughly that the Earth has been rendered uninhabitable. As a result, they have to leave Earth and find a new home. They briefly tried to settle Mars, but were driven off by hostile native Martians they had neither the numbers nor the energy to fight. After this, they wandered the cosmos for another thousand years or so, inside a massive ship around the size of New York state. However, almost as soon as it arrived in this new galaxy, this ship was destroyed by a collision with a massive asteroid. As a result, almost half of the colonists went down with the ship, and those who survived were dispersed on a few dozen smaller ships that scattered themselves throughout this new galaxy, with each eventually finding and settling their own uninhabited new world.
Conditions:
-In this scenario, the humans have a technology level around the same as present-day, except with the spaceship capabilities mentioned above.
-The Martians were technologically inferior to the humans, only being able to beat them by way of sheer numbers.
**Question:** Once these humans all arrive at their new destinations, what would be a good reason for them to lose all their technology? For the purposes of the story, I need them to revert to Mesolithic levels relatively soon after they arrive.
[Answer]
# No tools to build tools.
The surviving ships had a limited supply of spare parts and no means to make more. Once the capacitor on the ciruit board of the 3D printer goes bad, that thing is completely useless.
Perhaps the engineers realized that, and tried to 3D-print old-fashioned turret lathes and printing presses with the starship workshops. But then they ran into the second problem, too few specialists to maintain a technological society. When nine out of ten people are needed in the fields because they don't have combine harvesters, nobody has time to study physics textbooks.
The immediate requirements of survival prevent scholarship.
[Answer]
It would be unbelievable if they had kept their technology after several unplanned and under-equipped diasporas. Advanced technology is not just a bunch of technical lesson plans which can be casually carried along in every ship's computer. It is also the undocumented wisdom of experienced practitioners in hundreds of distinct disciplines. Beyond that, advanced technology requires massive infrastructure for mining and refining the necessary raw materials. That is hundreds more specialties which have to be learned, mastered and applied to their raw new home world.
Don't forget clean water and dependable electricity. Even more to learn and build.
The burdens which advanced technology lays upon young colonies is only slightly less than the advantages it provides to those colonies.
With all the other challenges facing your survivors, it would be pretty amazing if they somehow managed to keep their technology alive. ...and no surprise at all if they didn't.
[Answer]
# Your premise already explains it.
>
> and those who survived were dispersed on a few dozen smaller ships that scattered themselves throughout this new galaxy, with each eventually finding and settling their own uninhabited new world.
>
>
>
The large knowledge databanks, the educational material etc., would have been in the mothership alone, of course. The smaller pinnaces would only have had navigational information and logic. They wouldn't have been designed for anything but a quick escape in case of disaster.
And, on most of those pinnaces, there was simply not enough people to know and remember how all the technology can be put together starting from zero (smelting ores, refining metals, synthesizing chemicals...). Once (most of) the technology they brought with them broke down, they were not able to recreate it.
Actually, you would have to mention in passing that they at least managed to load on the lifeboats some genetic bank cryokits (unless the colonists had been genetically reengineered to survive inbreeding): otherwise, the ships would never have been able to repopulate a world due to the size of their gene pool. In the haphazard and panicked loading of the lifeboats, no one gave thought to the educational programs for the generations to come.
[Answer]
**Only the kids survive.**
The adults die within the year after arriving on the new planet. Just as adults who catch measles can become terribly ill but kids shake it off, the adults fall victim to disease organisms endemic to the new worlds while the kids roll with it and emerge from infection scarred but intact.
The little kids who are the main survivors could barely read. The sick, dying adults saw what was coming and tried to set things up to give the kids a fighting chance of not starving - setting up chicken coops, gardens, fish ponds. This is the culture that the survivors inherit.
[Answer]
* **The people who survived aren't useful to keeping tech running.** In the *Hitchhiker's Guide to the Galaxy* series, the people who crash landed on earth were not...exactly pioneer material. They were mainly middle management. If the majority of people who went down were ordinary citizens, most would not have any technical expertise, let alone be able to figure out how to process raw materials to repair what's broken. In fact, the average person, if you dropped them on a desert island with a bit of tech simply would not be able to maintain it--and over generations, forget about it.
* "relatively soon" could mean within a few generations. Or one. Really depends on what you mean there. But, with **survival being at the fore, keeping tech repaired would take a back seat to something like eating**.
* **Power requirements/actual ship is needed.** While in space your ships and tech were self-sustaining in some way. But once you got to the planet, as you spread away from the ship, the settlers could no longer make good use of the tech because they were too far from the power source.
* **ONE THING** Like power requirements, the tech needs one thing to run. Some unobtanium that they can no longer make. The expectation would be that it could be replaced, and in a hi-tech society, with access to the main colony ship that would have been easy. But instead, they are stuck without, and so abandon the tech.
Normally, I would get specific, using atmospheric conditions, or lack of resources on the planet they drop to be the problem, but as you want ALL of them to fail in the same way, that points to an inherent fault that must be present in all of their tech, which is not consistent to their environment.
[Answer]
**They choose not to use their technology**
Given that your story starts with humanity's reckless use of technology destroying a planet, I could easily imagine a new colony making a deliberate decision to regress to pre-electric technology levels, or even further. Give it a generation or two for the old education levels to wane and you have your technological devolution.
Examples of this include:
1. The end of the TV show
>
> BattleStar Galactica, where they fly their spaceships into the sun and live with cavemen
>
>
>
2. The premise from the Safehold series, wherein humanity settles on a new world after a narrow miss with extinction at the hands of an alien race. Fearing that the aliens would find the new world, the leaders created a false religion forbidding the use of any advanced technology, and brainwiped the colonist to forget their technological past.
[Answer]
**Geomagnetic Storm**
If the planet where they settle down is in a similar solar system as our planet, then a geomagnetic storm is a way to make them lose all of their electronics in a short time.
If you check this [article](https://en.wikipedia.org/wiki/Geomagnetic_storm) you can learn more about it, but according to it says:
>
> A geomagnetic storm on the scale of the solar storm of 1859 today would cause billions or even trillions of dollars of damage to satellites, power grids and radio communications, and could cause electrical blackouts on a massive scale that might not be repaired for weeks, months, or even years. Such sudden electrical blackouts may threaten food production.
>
>
>
If you want to damage the electronics but no the people this could be a good option.
[Answer]
I feel that the premises of your question are somewhat unrealistic.
1. Firstly, radiation fades very quickly. <https://emilms.fema.gov/IS3/FEMA_IS/is03/REM0504050.htm> In that source, it says "for every 7-fold increase in time after detonation, there is a 10-fold decrease in the exposure rate." In a few weeks or months after the detonations, survivors will be able to leave their bunkers without too much danger. Cancer rates might be up for some years, but most people would be fine.
2. In general, you do not go to space to flee Earth, especially due to radiation. No matter how devastated Earth got, space is probably more hostile. In space, there is lots of radiation, along with no air, few resources in interstellar space, etc. If you have the technology to build a ship the size of New York state that can sail the void for thousands of years, you could also build underground, self-sufficient arcologies on Earth that could save a much larger portion of the population.
3. There is no way a spacefaring civilization can lose to a non-spacefaring one. Numbers just do not matter. Any spacecraft capable of travelling between stars will carry incredible amounts of power (Don't have exact numbers, but even a modestly sized ship the size of an aircraft carrier would need energy equal to over ten times the entire modern world annual's energy budget to go up to 10% of light speed). A ship the size of New York could melt the surface off Mars with its engines alone, or just fling a couple of asteroids at it fast enough to smash the crust to pieces, even if it had no weapons, and it would probably have at the very least some lasers to shoot debris with to prevent hypervelocity collisions from destroying it.
4. Even if you are fleeing earth, there is no reason to immediately head to another galaxy. If you can build or somehow found and can maintain a ship that lasts millennia, then you have no more need for planets. Even if a hypervelocity black hole flies through the solar system and eats the Earth or drags it into the void, you could just relocate to the asteroid belt or the moons of Jupiter or something. There are tons of resources there, and you could just build habitats such as O'Neill cylinders and mine the asteroids for materials to repair and expand with. You might eventually want to move out to colonize the stars, but you would only do that after you had established an industrial base and constructed a partial Dyson swarm or something like that. You gain nothing by wandering the stars immediately, as the void between them is hostile and largely bereft of resources.
5. Even if you left the solar system, you would not immediately go to another galaxy. There are many stars reasonably close to earth (according to wikipedia, 52 within 16.3 light years), while the closest galaxy is 25,000 light years away. To reach any galaxy, you would have to fly for hundreds of thousands or millions of years through empty intergalactic space, where there are almost no resources for resupplying and repairing, while to go from one star to another, you can just hop from one star system to another, resupplying as you go, with each trip taking just a few decades or a few centuries at the most. Also, there are many chunks of ice and rock, as well as rogue planets within the galaxy to resupply from, though slowing down to grab one and speeding up again might not be worth it. FTL would not change much about this. If it just speeds up travel, letting you travel at 10 or 100 times the speed of light, it would still take orders of magnitude more time to leave the galaxy than to reach a nearby star for no benefit, while if you had some sort of teleportation style FTL, you might as well just teleport to some perfect location, and you wouldn't need to spend millennia in the void.
6. Humans would find it almost impossible to survive on alien worlds with mesolithic technology. Even if they have life of their own, the conditions would probably be totally wrong. The life there will almost certainly have radically different biochemistry, and will be either indigestible or poisonous. We will not be able to grow our own crops in the soil, which will probably be incompatible to their biology. The local viruses will probably not be able to infect us, as viruses are highly specific in their hosts and can only enter the cells of specific organisms, but their bacteria and eukaryotic pathogens may be able to grow in us, and we will have no defense against them. The atmospheric composition will probably be different, making it hard or impossible for us to breathe. Life bearing worlds will probably be almost as hard or even harder than barren rocks to colonize, so their is little point in searching them out.
7. No interstellar ship is going to be hit by an asteroid. Even today, most asteroids are tracked closely, and with the sensors on any ship capable of navigating the stars, you will be able to see them and respond easily. Remember, current Earth based sensors can still spot the Voyager probes, which are over 100 AU away, and those are the size of a car and weigh under a ton. Once spotted, the asteroid can be shot with a giant laser (any ship the size of New York that can fly at a few percent of light speed will have the energy to power huge lasers), hit with hypervelocity projectiles, or simply dodged.
In conclusion, your premises are a bit flawed. Instead, maybe you could say that an asteroid was about to hit Earth, and some wormhole devices were discovered leading to worlds that were unexpectedly habitable, and they were only able to open them at the last minute so few got through, and they then had wars at the new places, causing them to lose the technology they brought with them.
[Answer]
The problem is going to be to make them lose some technology, but not so much as to prevent them from surviving.
Mesolithic people had their own technology that was very effective for small hunter-gatherer populations. They knew how to make tools and hunting weapons using local resources. They knew which parts of which plants were edible, and which could be used for purposes such a making cords and basket weaving. They knew how to butcher large animals, and dry and/or smoke the meat to preserve it even if they did not have large quantities of salt. They knew how to prepare hides to make clothing etc.
One key decision is how long do they keep access to copies of Wikipedia and Youtube. No access would prevent them from viewing videos on important topics such as "flint knapping for beginners" and how to make a watertight container from bark.
If they have a limited window they would have to prioritize learning survival skills. The generation born after they lose access would learn that there had been a golden age with all sorts of marvels, but their parents would only be able to teach the survival skills and knowledge, and a few bits and pieces of what individuals remembered but not all the intermediate steps to get from here to there.
I suggest allowing them a couple of years of access to Wikipedia and Youtube. If they have not learned enough survival skills in that time they are dead anyway.
[Answer]
**The [Aphasia](https://www.aphasia.org/aphasia-definitions/) Plague**
Some ideas were extremely difficult to discover, but are so simple to explain that they are very unlikely to be lost. The ideas behind the germ theory of disease, for example. Or the knowledge that metal exists, and can be made by heating the right kind of rock to a very high temperature. Or that food can be preserved by adding lots of salt or sugar to it.
You need something to wipe out all knowledge, or close enough. The ships will have in their databanks, for example, an entire copy of wikipedia, and archives of Youtube. This will include shows like [Crash Course Chemistry](https://www.youtube.com/playlist?list=PL8dPuuaLjXtPHzzYuWy6fYEaX9mQQ8oGr) and [Crash Course Statistics](https://www.youtube.com/playlist?list=PL8dPuuaLjXtNM_Y-bUAhblSAdWRnmBUcr) and the results of [searching for how to forge iron](https://www.youtube.com/results?search_query=how%20to%20forge%20iron).
Many of these ideas are not that hard to teach people. The contents of a grade school science textbook will be enough to keep people out of the Mesolithic.
So to make what you want happen, you have to get rid of **all** of it. The only way I can see is to temporarily destroy people's ability to transmit information.
A plague strikes the survivors. It inflicts brain damage, causing aphasia to strike 99.984 percent of the population. Over the course of (let's say) a few centuries, humanity develops a resistance to this plague.
Afterward, basically everything is gone. Computers in the ships, printouts of Wikipedia, etc. may all still exist, but nobody can understand what any of it says anymore. All the old languages are dead. New ones get created. All the ideas behind things like 'iron smelting' are lost, because nobody had the words to teach subsequent generations anything that can't be explained with simple sign language.
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[Question]
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In my pre-plastic world there is a killer who removes unblemished skin from their victims and replaces it with a non-human 'skin', so that one can't tell the replaced skin from the remaining human skin.
**What is the best candidate for the replacement material?**
Ideally, it should fulfill the following conditions:
* Not made using crude-oil-based materials
* Available in most Caucasian skin tones
* Allows fine stitching to be applied
* May be fixed to or draped across a wire mesh
* Looks as similar to the remaining skin for at least 24 hours of partial exposure to the elements (moist European climate, dressed in appropriate clothing) as possible
EDIT: The skin is only to roughly mask the mutilation and serves no permanent function. The victim is dead and will not be moving in the foreseeable future.
Victims may have almost all skin replaced apart from the face and the palm-side of the hands. Younger victims tend to have more area replaced than elderly ones due to the growth of lesions and the likes.
[Answer]
I give you two choices depending on use:
**[Mortician's wax](https://careertrend.com/how-10051629-make-morticians-wax.html):**
>
> Mortician's wax is a cosmetic wax used by morticians to cover injuries
> on dead bodies. The wax imitates the properties of human skin and is
> used to fill in gouges, lacerations and areas where flesh is missing.
> Makeup can then be applied to make the wax match the real skin.
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>
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Whilst the modern recipe contains petroleum based waxes, I see no reason why a beeswax - vegetable oil - animal fat and ground talc recipe couldn't be made that could be gently heated, applied with a palate knife, allowed to cool and then be stippled with a brush to simulate pores, then made-up to look like skin.
**If it is required to be flexible and on a moveable subject the issue becomes more problematic.**
**[Latex](https://en.wikipedia.org/wiki/Latex).**
(Edit in response to comments: Obtainable from a number of plant [sources](https://en.wikipedia.org/wiki/Natural_rubber#Varieties) worldwide: Dandelion, milkweed, rubber tree. - Found in 10% of all flowering plants.)
Latex can be applied, then made-up, but it tends to contract somewhat on drying if painted in thin layers and built up, it's more involved to give it a texture also: pre moulded latex can work very realistically.
Using a plaster of paris base, plasticene or fine clay if you prefer can be added and finely textired to make a "positive" ([youtube video](https://www.youtube.com/watch?v=1IAc2hDCHlQ) excellent tutorial - if you ignore the fact he's using a plastic base) This, when finished and dry would be coated with a *very thin layer of beeswax* or equivalent and then a fine spray of thin oil to act as a release agent.
A "negative" can then be made with [alginate](https://en.wikipedia.org/wiki/Alginic_acid) (seaweed extract - should have strips of fabric added to give it structural strength when it's peeled off) - when set, this is *carefully* peeled off and set to rest in a suitable pile of cloth downside-up, it can then be painted with latex. When dry this can be peeled apart, discarding the alginate, leaving perfectly textured skin-substitute ready for sticking on, and blending-in with make-up.
[Answer]
# Pig skin
Pig skin is already used on humans as part of [skin grafting](https://www.woundcarecenters.org/article/wound-therapies/skin-substitutes).
It is generally only used as a temporary graft until a more permanent one is ready.
From a [1964 article](https://jamanetwork.com/journals/jama/article-abstract/1161692), as the process was very new:
>
> Pigskin dressings and immediate excision were both advocated for the
> treatment of burns at the 49th Clinical Congress of the American
> College of Surgeons in San Francisco in October.
>
>
> Pigskin grafted onto patients with extensive third degree burns was
> retained for more than two weeks...
>
>
> In earlier experiments these investigators had used fresh
> split-thickness pigskin on third degree burns in 200 mice. They found
> that the grafts, irradiated or not, appeared soft and viable for
> nearly three weeks. During the next two weeks the grafts slowly dried
> and sloughed.
>
>
>
In 2012, [Doctors graft pig's skin onto burned child](http://www.gochengdoo.com/en/blog/item/2588/doctors_graft_pigs_skin_onto_burned_child_in_zigong). In this case it was done pretty quickly without a lot of processing. The skin was grafted and expected to take about 2 weeks to fall off as the child's own skin regenerated.
Here's a picture from a [different article](https://link.springer.com/article/10.1007/s40204-014-0030-y). It looks pretty decent (the last picture is a human leg with porcine skin). Maybe could use some makeup...
[](https://i.stack.imgur.com/URU1M.png)
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The closest you might be able to get would be prepared animal skin (cut, formed and dyed to the right specifications), but I sincerely doubt there is anything that will stand up to close inspection. If it only needs to fool from a distance, then that would probably suffice.
[Answer]
[Gutta-percha](https://en.wikipedia.org/wiki/Gutta-percha) was used in the times before plastics were invented, for pretty much similar purposes.
It became uncommon only after the mid-20th century, because plastics became easier to manufacture in larger quantities. Gutta-percha is made from the sap of trees, so it cannot compete in modern times with plastics due to economies of scale. However, it could theoretically be manufactured with medieval levels of technology.
Searching it among google images, there are many results in the colors you wanted.
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[Question]
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When developing a medival fantasy realm, especially one with no known healing and restoration magic, one may need to develop the people's understanding of science and medicine. A unique example of this is in Patrick Rothufuss's "A Wise Man's fear", where someone from an altruistic organization called the Amyr performed human experiments for the purpose of collecting data that aided in saving many human lives in the future, despite the hundreds of tortured human lives that were sacrificed to produced such data.
My question is how can I develop a people's understanding of the germ theory as early as the middle ages, even if only the rich and educated get exposed to such knowledge?
[Answer]
The Middle Ages is normally said to be between the 5th and 15th centuries (so 400-1400 AD).
[Germ Theory](https://en.wikipedia.org/wiki/Germ_theory_of_disease) was first proposed in 1546 (!), close to the Middle Ages. It's not clear if [Girolamo Fracastoro](https://en.wikipedia.org/wiki/Girolamo_Fracastoro) meant cells and bacteria as we know it today, but the core idea is there.
So you really have little to do beyond making influential figures of the period (e.g. A King or two) become convinced it's the right theory and back it. Perhaps another person or your character who proposes the idea is fortunate to have a powerful patron who lets them, e.g. try out improvements in basic hygiene and something as simple as masks and gloves when dealing with blood injuries or similar systematic approaches to dealing with illness. Perhaps the results impress the powerful patron and leads to wider publication and more widespread use. And in time to an early development of the theory and it's applications.
The [compound microscope](https://en.wikipedia.org/wiki/Optical_microscope#Invention) was invented sometime around 1590. Again just outside the Middle Ages. The combination of these two inventions in the right hands and with the right patron would be enough to get things going well. Probably this can be reasonably be made to happen a little earlier (say 1400). The microscope is important as it lets you see something to attach a theory to. "Have a look at this, Oh Wealthy Patron" works a lot better than "I have this wild idea, Oh Great One". It won't prove germ theory, but it will help advance the idea.
A King or Emperor who has a great interest and belief in sciences would be *very* useful. A King whose heir also has that interest would be better. Science needs money, lots and lots of money. :-)
As an aside you need to explore how science was done in the Middle Ages to get a feel for the way it would happen.
[Answer]
**We already had it and ignored it**
There was a Greek general [Thucydides](https://en.wikipedia.org/wiki/Thucydides) from the 5th Century BC (no relation to our fellow resident answerer as I understand it) who first postulated the theory of contamination being spread by 'Seeds', or small objects invisible to the eye.
We ignored this in any serious scientific way, preferring the idea that deities and potentially their familiars (think cats during the Black Death) were responsible. It wasn't until Louis Pasteur that we really started to resurrect this idea as a serious scientific line of enquiry.
In many ways, this is similar to the [Ionians](https://en.wikipedia.org/wiki/Ionians) who in the 13th century BC (or thereabouts) first articulated that the earth orbited the sun as part of a solar system before that idea disappearing for over 3 millennia.
The best possible way to enable the idea of germs during medieval times is to have taken Thucydides' observation and handed it to real Greek scientists to explore and develop as part of their research pursuits. If we didn't lose it in the first place, perhaps the dark ages wouldn't have been so... well, dark.
Just saying.
[Answer]
In a rudimentary way, people already knew. More precisely, they observed that many illnesses would transfer to another person when they got in contact with an ill person, but they didn't understand why.
This led to very different ideas like
* An illness is a punishment from God. Those who conspire with afflicted people deserve to be punished (infected) as well.
* An illness is caused by bad smells (Malaria literally means "bad air"). This led to people avoiding the manure in their cities and using good-smelling herbs as medicine. They got the cause wrong, but the result was right in most cases.
* People observed that most illnesses spread through close contact between ill and healthy people. In times of highly infectious epidemics they build quarantaines to seperate ill people from the general public.
* They had a twisted understanding of cleanliness. It was thought that changing your underwear (a long garment like a night gown) at least once a day (twice a day for infants) was the definition of "clean". They neglected personal hygiene like washing their hands and faces with soap, which evidently lowers the risk of contagion.
[Answer]
wouldn't have to necessarily develop a germ theory, so much as pragmatically adopt the hallmarks of infectious disease control, some of which were known in the late-roman/byzantine/arab world:
* quarantine
* frequent bathing, changing of dressings/clothing/bedding
* clean clothing & bedding by boiling
* clean fresh water supply
* well-functioning sewage system
this could all be rolled into a hygienic aesthetic, perhaps a cult
[Answer]
Please refer to the novel "On the Oceans of Eternity" by SM Stirling for a very interesting take on that question. A group of Americans who were transported back to the 2nd millenium BC, try to teach the Sumerians how to protect themselves from germs. They have to integrate this into religious beliefs and daily rituals.
If I recall well, they use the Inanna and Enki myths to justify the hand washing rituals, boiling drinkable water, etc.
[Answer]
As a very specific example, there's nothing about [Louis Pasteur's swan neck flasks](https://en.wikipedia.org/wiki/Swan_neck_flask) that preclude them from being demonstrated much earlier than the 1860s.
Possibly not enough on its own to get you all the way to a full germ theory, but it could be a pretty useful step along the way.
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[Question]
[
Would it be possible to make a crude scale mail out of oyster or some other mussel shells. If so how effective would it be? Do I need to invent some kind of super tough oyster for it to work?
[Answer]
Real shell armor does exist. How practical it was is unknown however.
The breastplate of tula was made by drilling and sewing hundreds of shell fragments to a leather base. Helmets of cowry shells also exist. The big issue is it would not survive many hits, shells are brittle and the bigger the individual pieces of shell the weaker that will make the armor because the more that will end up broken after each hit.
I apologize the museum website may require some scrolling to see the close up [image](https://www.uweduerr.com/museo-nacional-de-antropologia-gallery-toltecas/m7vizlae2uqy8fvkybf90p0slb5qdw).
[](https://i.stack.imgur.com/McVuF.jpg)
[Answer]
Could you do it? Absolutely yes. Would it be WORTH doing? Well, that's trickier.
Oyster shells are [very, VERY tough](https://physicsworld.com/a/scientists-crack-oysters-secret-of-strength/). Tough enough that the DoD is currently trying to replicate its qualities [in modern armor](https://www.nbcnews.com/science/science-news/how-oyster-shells-could-help-protect-troops-battlefield-n68136). So toughness isn't an issue at all, and if you could actually MAKE some, it would make very effective protection.
That's where this gets tricky though: How you do you attach the shells to an underlayer or to each other in a way where they won't just constantly be coming off when struck. When you're crafting the scales yourself out of metal or whatnot, you can control the shape to have proper attachment points. Oysters don't NORMALLY have any convenient way to firmly attach them to anything else. If we were trying to do this in our world with our oysters, the way you'd probably have to do it would be by drilling holes in the oyster shells so you could use laces to attach them. This is how traditional scale armor was constructed back in the day.
Of course, the very qualities that make you want to use oyster shells make them VERY difficult to drill, so the time and effort you'd spent making a set of armor like this would be all out of proportion to any reasonable benefit.
I see two possible solutions: You either introduce a tool or technique that's particularly effective at easily putting holes in oyster shells, but impractical as a weapon (some kind of acid might do nicely), OR you find or create a species of oyster that has particularly pronounced protrusions that can easily be used to secure it to armor.
[Answer]
A couple layers of shells should provide a good set of armor if you have nothing else, though they will certainly start cracking with every good hit so don't expect it to last long.
---
For every question, there's an oddly specific research paper that gives the answer: [Shell Hardness and Compressive Strength of the
Eastern Oyster, Crassostrea virginica, and the Asian
Oyster, Crassostrea ariakensis](https://pdfs.semanticscholar.org/cd2d/639cc212b857ab62377b44dcae4472f7ea63.pdf).
According to the above paper, the [compression strength](https://en.wikipedia.org/wiki/Compressive_strength)(ability to not crack) of oyster shells varies based on thickness. About 1000 Newtons are needed to crack a 1mm shell, 2000N to crack a 3mm shell, and 4000N to crack a 5.5mm shell. According to [this site](https://hypertextbook.com/facts/2000/AlbertKlyachko.shtml), a good swing of a baseball bat hits a baseball with 3400N of force, so if the oyster shells in the armor are 5mm or more it would provide decent protection.
However, [this Physics StackExchange answer](https://physics.stackexchange.com/a/13605) goes into how much force a hammer hits a nail with: more than 9000N, which is likely closer to what armor would need to withstand in a fight. Thankfully, the original paper shows that compression strength increases non-linearly as shell thickness increases, meaning increasing thickness leads to greater and greater resistance to cracking.
Although it wasn't measured, a 7mm thickness would resist up to 7000N of force, and 10mm should resist at least 10000N if the increase continues at the same rate. Though there's probably diminishing returns, a couple layers of shells should give the strength needed to resist glancing blows, and maybe even a few direct hits before shattering.
[Answer]
Two things:
Firstly, in the absence of metal, it might be a very worthwhile endeavor, comparable to chain mail.
Secondly, not everything had a practical element, generals wore leather muscle cuirass long after better things came along because it was prestigious and looked cool, likewise a labor intensive armor made of beautiful, shiny shells might be used both because it was practical and BECAUSE the labor intensive nature of making and replacing broken shells showcase the status of the warrior or chieftain, and thicker shells on leather could be items of high status, while thinner shells strung over straw padding might be a more affordable, but less effective and impressive armor.
Finally, on a slightly unrelated note: Giant clams baby, you would have the most expensive and prestigious suits, reserved for high priests and kings, be literally carved out of the shells of MASSIVE shells, from killer clams, with the rough outer layer sanded off, leaving a breastplate of unparalelled protection, and BEAUTIFUL mother of pearl finish!
[Answer]
## Not actual shells, but artificial shell analogue materials
Can you make a dress out of silkworm cocoons? Not really. But out of silk? Definitely.
The same is true for oyster shells. Such shells are layered calcium carbonate and biopolymer composites, and they're very, very tough, which is one of the prime requisites of an anti gun armour.
More importantly, if engineered right, they'll crack sacrificially in a way that stops bullets better than steel, weight for weight. It won't survive many shots, but no other armour does either. This is called fracture energy. Its upper limit often correlates with toughness.
This is how military grade sintered alumina armour (which weighs about 10-15 kg) works. I've got personal connection to this. I got to work on sialon in a lab as a ceramics chemistry intern; they were making body armour and the ballistics results were nothing short of incredible.
Artificial shell could be incredible in this regard.
The real questions involve aesthetics. You won't be growing body armour out of actual shells in real life; they'd be boring looking shiny flat plates. But...artificial worlds aren't real life. If you want an anime style shell armour, go for it.
PS If its for swords rather than guns, stick to steel.
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My world is covered in a black stonelike material which is similar in structure to coral, being that it's highly-porous but not formed in the same way. The (non)water on my world, which is (currently) trisilane, can flow through the material with ease, and I have the idea that it flows underneath the surface to a point in which there is a different material that is not as porous, and therefore creates the true "bottom" of the ocean. This idea is not fully-formed.
You could also compare it to volcanic rock.
Islands are low-lying raised instances of this material in which these plants and their fellow living creatures would survive.
The way I define plants in this question would be "living organisms which form roots in the ground and sprout upward". They are intelligent and feeling, and can move flexibly (though slowly) to avoid predation or unnecessary touching. That is, if they can even survive in this environment.
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On earth, **Lichens can grow on bare rock — and in the process slowly create soil from the (slowly dissolved) rock and themselves.** Lichens are actually two organisms in a symbiotic relationship, an alga and a fungus. See:
<https://en.wikipedia.org/wiki/Lichen>
If your world has (functional analogs of) algae and fungi, **I posit that eventually they'd end up forming the functional equivalent of lichens**, and would slowly dissolve the surface rock into soil usable by conventional plants.
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Stone itself is not a barrier to plant life, plants can get their nutrients from what is in the water. You get shrubs that will grow on lava fields wherever they can get a grip.
But water is the key problem, water is essential for life, not just because it's water, but because all sorts of essential ingredients are soluble and can be carried in it and later retrieved. If our oceans were pure water no life would have evolved at all.
So having oceans of trisilane is your biggest problem, not the rock.
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With great difficulty, there's a reason they call land like this [Hell](https://en.m.wikipedia.org/wiki/Hell,_Grand_Cayman)
You can't walk on it without heavy shoes, each edge is razor sharp. You can't build on it without modern tech so no infrastructure early on.
Land based life would initially be limited as each Individual area would be cut off from the whole - this could lead to a bigger variety of animal kingdoms.
I can see any large creatures evolving, as they would have the transport issues and as soon as they were bigger than the holes in the land they would be perpetually exposed..
Without breaking the stone down, trees will be limited by what they can access in terms of water.. stunting growth as well.
All in all, sounds like a horrible place! I will not be booking a ticket
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### The kingdom itself
We are talking about medieval era.
We have a kingdom that is established on a [large desert](https://worldbuilding.stackexchange.com/questions/55052/constructing-a-desert-area?noredirect=1&lq=1).
Desert tend have low precipitation and high temperatures, this makes it an inhospitable place to be, but differents civilizations have managed to live in.
They have access to regular metals used in weapon development(iron, steel).
### My questions
* What types of armor and weapons could they develop?
* Would they ride horses or other animals to battle?
* How would they fight outside of the desert?
I mean, they are used to fight inside the desert, so when it comes to invading a place which is a grassland, how would they develop their regular tactics?
And last
* Defending cities from other kingdoms sieges, is just as other cities would do?
[Answer]
Most major desert civilizations were historically built up in large, flat flood plains surrounding major rivers, such as the Tigris and Euphrates in Mesopotamia or the Nile River in Egypt. These areas have concentrated regions of high quality farmlands. They have rich, silty soil from regular flooding and can generally be irrigated fairly easily by digging canals. The civilizations themselves tend to be agrarian with dense population centers compared to nomadic cultures or cultures living in areas with lower quality farmlands. While small armies may exist in the hands of nomads in the drier wastelands, big civilizations, and therefore big armies, will be suited for combat in these floodplains.
The floodplains, while differing in character to some extend based on the temperature of the desert, will follow these general characteristics:
* Good visibility
* Flat terrain
* Few obstacles
Desert armies are going to be set up to take advantage of these features. The Egyptians, the Persians, and the Ottomans all relied heavily on chariot or cavalry formations supported by large blocks of infantry. Large, but generally poor, civilian populations will form the infantry, while the wealthier classes in society will be able to afford horses, and will make up the cavalry. Alternately, the cavalry may be comprised of professional soldiers, such as the Mamluks.
Armament of soldiers will be varied, based on the technological level and individual culture of the civilizations themselves. Generally, though, they won't be significantly different from armies in other environments, aside from the fact that desert soldiers will probably wear some form of head and neck covering for protection from the sun. Different groups of soldiers varied from very light clothing, as was found in the armies of ancient Egypt, to the full body plate army worn by the Mamluks millennia later.
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People from deserts did plenty of conquering in history. Infact in the actual middle ages, most of the big conquering took place at the hands of desert or semi-desert dwelling [Arabs](https://en.wikipedia.org/wiki/Early_Muslim_conquests), [Turks](http://www.fsmitha.com/h3/casia01a.htm), and [Mongols](https://en.wikipedia.org/wiki/Mongol_invasions_and_conquests).
**Armor**
[Examples](http://www.umich.edu/~marcons/Crusades/topics/war/Islamic_Armour.html) [here](http://www.metmuseum.org/toah/hd/isaa/hd_isaa.htm). Turbaned helmets provide head-protection against sun and sand as well as arrows and blows. Metal armors are heavy and get hot in the sun, many nomad armies wore quilted, leather, or silk armors.
**Weapons**
The bow is the weapon of the nomadic [horse-archer](https://en.wikipedia.org/wiki/Mounted_archery). Living in near-desert conditions means living with livestock, not farming. Living with livestock means finding some livestock to ride. When your whole army is riding, you can use mobility to your advantage. Move, shoot, move, don't close with the enemy unless their morale has already been shattered.
**Mounts**
[Camels](https://en.wikipedia.org/wiki/Camel_cavalry), obviously, are great in deserts. But the horse family is actually pretty well desert adapted as well. One of the most famous horse breed is the [Arabian](https://en.wikipedia.org/wiki/Arabian_horse), and its quite a stretch to call Arabia a grassland. The Arabian horse is ideally situated for the nomad warrior, having great stamina and not being too big (i.e. not needing to eat and drink alot like the destriers of the West). Plenty of horse-like animals live primarily in the desert like the [Khulan](https://en.wikipedia.org/wiki/Mongolian_wild_ass) or [Imperial Zebra](https://en.wikipedia.org/wiki/Gr%C3%A9vy's_zebra).
Going more fantastically, creatures often imagined to live in deserts would include giant lizards, griffins, hippogriffs, giant scarabs, and the phoenix.
**Outside the Desert**
They would fight...the same! As long as there are open plains, the horse-arching tactics of the nomads will work. The Huns, Avars, and Magyars penetrated as far east as Hungary while raiding into France, the Arabs and Berbers conquered Spain while raiding into..France. The Mughals (Mostly Afghans and Turks) conquered North India and raided into Southern India. The Mongols conquered northern China while still primarily nomadic (by Kublai Khan's day their armies were Sinified), and raided Korea and southern China. While dense forest regions like South India, South China, and European Russia remained unconquered, they were all certainly subjected to slave raiding and tribute. Forest wasn't much of a barrier to well organized nomad armies.
**Cities**
Why would your desert people have them? They live off livestock and livestock gots to move. No time to settle down for cities. A few walled trading posts of a few thousand on strategic trade routes is all that the desert kingdom will get.
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In strategic terms, control of the desert means control of water and viable transportation routes. Attackers will need to be highly mobile and capable of moving from oasis to oasis (which, as noted favours cavalry formations mounted on appropriate horses, camels etc.) and generally lightly armed and armoured to achieve speed and mobility.
Defenders will need to be able to fortify and hold oasis and passes through the desert, as well as having the knowledge of the local terrain to prevent being outflanked.
Fighting for control of caravan routes, salt pans (a valuable resource which can be easily mined), watering points and other strategic areas will be the goal of desert warfare. (This was true even in the 20th century. The Arab Israeli wars were decided around key points like the militia pass or the canal running through the "Chinese Farm" in the Sinai Desert, for example).
Logistics will also be difficult. Forces will be spread over a wide area, and concentrating large forces will be both difficult to organize due to poor communications, as well as the sheer difficulty of feeding and watering large forces in the desert. Defenders will be in isolated forts, with limited supplies and perhaps long time lines for any reinforcements to arrive. The classic French foreign legion films are set in a different era, but illustrate the point perfectly.
[](https://i.stack.imgur.com/9irgC.jpg)
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**Amour**
Seems appropriate to use leather - it'll dry and harden nicely in the desert conditions and it's fairly light. Laminate with soft leather so that impacts aren't likely to break the hard leather too much.
**Ridden Animals**
Camels seem the obvious choice here, or oversized Monitor Lizards - really depends on what species you've chosen to populate your world with....
**Outside the Desert**
Might make sense to make use of guerrilla tactics and go silently on foot, ideally at night.
Defending cities shouldn't be a big issue since your cities will be built around any oases. Anything areas outside the cities wouldn't have any water sources to speak of, which makes things rather difficult for the opposing army.
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**How big could an empire using World-War II equivalent technology become on a very large world?**
**Setting:** Handwavium-based-artifact by a Kardashev III+ civilization, or perhaps a simworld created by AI researchers in the (not-so?) distant future. We're talking about a [1-AU-radius world](https://worldbuilding.stackexchange.com/a/41870/3510) (except people live on the outer not inner side of the hollow sphere), so for all intents and practical purposes (at least with WWII transport tech), a humongous and near-flat world (it would take hundreds of years to drive around at 130km/h). Let's assume that:
* **It's Earthlike** in effect. The exterior surface (I'm assuming it is a hollow Dyson-like sphere, outside populated, with 20-40 km of earth and oil and rock on top of the thin handwavium layer keeping it together) is somehow kept Earth-like (1g, 1001 KPa air, habitable throughout, with each area subjected to a myriad local (small) sun-like sources orbiting in such a pattern that most areas see something like a 24 hour day-night cycle and temperate-climate-like seasons). There are geological process emulators, so there are volcanoes and tectonic plates and earthquakes, ensuring that chemical elements get cycled through properly and all Earth-like. The world has ample coal, oil, metals and other resources. Fake fossils everywhere, cunningly planted.
* **Feature granularity is Earth-like**. I mean earth-sized seas and continents, very few if any size-driven impassable oceans, mountains or deserts. (i.e. the ocean or desert does not stretch in that direction for 10,000,000 km)
* **Primitive humans were seeded throughout**, 20,000 years prior. Uniform distribution with several small (but genetically sustainable) bands placed in habitable areas.
* It's big. **Very big**. If I did my calculations right, the total area is about 281,229,865,303,000,000 square km, that's about 500 million Earths' worth.
* Some rare areas would be thousands of years ahead of the pack due to sheer geniuses or dramatically good conditions, so I expect some areas to reach industrial tech while others are still hunter-gatherers. I'm not sure what I want to define as areas in terms of size, but I expect them to be pretty large, since technology does tend to diffuse outwards.
Let's skip ahead to a point where there are now industrial-level civilizations on the planet, with WWII-era technology. **How big could a World-War II equivalent technology empire become in such a world?**
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Potentially very large.
The limits would be speed of transport and communication.
For comparison the Roman Empire was about 4,000 km across with maximum communication and transport speed of ~10 km/hr (horse or boat)
By the time of the British Empire you have spread to effectively be world wide or about 40,000 km (Earth's circumference) with speeds of travel and communication around ~40 km/hr (steam train and fast sailing ships)
WWII tech would push the land speeds up to around 100-150 km/hr, ocean speeds of ~50-60 km/hr, and the addition of air travel at speeds of ~500-1000 km/hr.
The big change was the introduction of radio communications allowing messages to travel at near the speed of light.
Assuming the transport speeds are the limiters (which would all require infrastructure to support), your empire could easily be multiple earths in size ~1,000,000+ km.
For an upper maximum size example: an ocean vessel or train line running for a lifetime (~50 years) would only go 20-40 million km so I think an empire larger than that would be very unlikely.
With radio there could be communication around the entire object (with repeater stations for line of sight issues) but I think it would be unlikely to care about a place that is so far away it would require generation ship timelines to get there.
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@JoshKing's answer addresses the main issue very well, but I want to toss in an alternative. Considering that communication around the sphere could still be achieved by radio at near-light-speed, it's theoretically possible to organize a government that spans the entire sphere.
Governments only work because of two things: (1) People generally agree what rules there should be, and to a much greater extent, (2) the government has the ability to enforce those rules. If global (spherical?) consensus could be reached on a set of laws/rules, enforcement agencies (police/military/etc) could be organized at intervals around the sphere to enforce them locally. If any one group decided to stop obeying, it would be the responsibility of the agencies adjacent to them to quell the disturbance and return the region to status-quo.
There's just a *teeny-tiny* `sarcasm engine revving` problem with this whole idea, though. Even on tiny little planet Earth we haven't managed to achieve any level of cooperation remotely close to what would be required in this scenario, so chances are it's nearly impossible for *humans as we know them* to accomplish. But it's at least food for thought.
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I like all answers so far, all have valuable points.
Also I may confirm OP calculations, it's 554,502,685 times larger surface.
## How big it is
Larger surface means also larger possible population, 3.88151879518e+18 peoples, if we take current density, and it may be 10-100 times bigger, even ww2 tech. But let's stick with first number.
[Six degrees of separation](https://en.wikipedia.org/wiki/Six_degrees_of_separation)
* Six degrees of separation is the theory that everyone and everything is six or fewer steps away, by way of introduction, from any other person in the world, so that a chain of "a friend of a friend" statements can be made to connect any two people in a maximum of six steps. It was originally set out by Frigyes Karinthy in 1929 and popularized in an eponymous 1990 play written by John Guare.
What will it mean for such large population?
It will be not Six degrees of separation but **12** degrees of separation.
* It is result of following equation 6 \* X, where X is from: Max\_sphere\_population=6dos\_theory\_populationX=average\_person\_connections6\*X
X=ln(Max\_sphere\_population)/ln(6dos\_theory\_population)~=ln(3.9e+18)/ln(2.5e9)
It means any chain of command will be 2 times longer then nowadays. Without internet, without computers, without databases, without terabit/sec of data channels etc. And with radio stations, and typewriters - it will be even worse to manage that population.
It have not to stay long in that state - so I assume they developed proper stuff.
## Population
Just a side note, how long it will take to reach such number by population. [Population growth](https://en.wikipedia.org/wiki/Population_growth)
* Global human population growth amounts to around 75 million annually, or 1.1% per year or 1.011 times per year or 1.011^100~= 3 times per 100 years.
It depends from start number, but let say million at the begin. *It will take 2600 years*
So not million years, not even 10-100 thousands. If we keep health care and food production on ww2 level - we can expect even faster grow, because of fewer limiting factors like price of surface to live, wood, water etc etc - just go far enough where no body cares and all is ours - like wild west.
How far is that? I guarantee you 20000 km is far enough, more then enough not to care, even in our time with satellites and gps. Actually 1000-2000 is enough. Even less is enough, but it depends on density of population in that place.
So you may travel on your personal [wood gas](https://en.wikipedia.org/wiki/Wood_gas) powered auto, wild west style but with autos.
## Government efficiency
* What actually means 12 degrees of separation instead of 6 degrees of separation.
It means command chains are 2 times longer, it means not only 2 times slower reaction, but if there is 10% chances to do something wrong, and 90% to do it right - it means with 3 times longer chain it will be 19% and 81% for fail and success, for single chain. So any imperfection of systems will grow. higher is that imperfection more impact it will have.
Or it may be depicted another way - each human from our current world is president of another world of same size. Not sure that I like to think about that.
As radio will be main source of transferring data (for OP tech level) - easier to fake transfers, to falsify data, etc. More possibility's for corruption, more possibility's to exploit.
Even with today technologies it will be a big big problem, not because of tech, but because of social factors and concept of central government as pyramid of influence.
But there is and was different approaches, sort of p2p approach, as not perfect example but some of it's kind [Decentralized autonomous organization](https://en.wikipedia.org/wiki/Decentralized_autonomous_organization).
Our current systems capable for cases 4-5 degrees of magnitude management, which are actually power of some undefined number of peoples, in theory above I estimate it is something like 40.
This number have actually more deeper sense, connected to our biological limitations, I mean mostly with our brains. As usual with humans it is't something strict, but it makes sense.
There is so called [Dunbar's number](https://en.wikipedia.org/wiki/Dunbar%27s_number)
* Dunbar's number is a suggested cognitive limit to the number of people with whom one can maintain stable social relationships. These are relationships in which an individual knows who each person is and how each person relates to every other person. This number was first proposed in the 1990s by British anthropologist Robin Dunbar, who found a correlation between primate brain size and average social group size. By using the average human brain size and extrapolating from the results of primates, he proposed that humans can only comfortably maintain 150 stable relationships. Proponents assert that numbers larger than this generally require more restrictive rules, laws, and enforced norms to maintain a stable, cohesive group. It has been proposed to lie between 100 and 250, with a commonly used value of 150. Dunbar's number states the number of people one knows and keeps social contact with, and it does not include the number of people known personally with a ceased social relationship, nor people just generally known with a lack of persistent social relationship, a number which might be much higher and likely depends on long-term memory size.
This number may be in base of that 6 degree power, 150 makes big number 1.1390625e+13 which is still less then number of that may be achieved in that world, 340,000 times lesser, it may mean probably 340000 countries or and probably yes a bigger number of them.
Let say ambassador will have printed book, or 10 books just with names of counties. 340000 countries = 3400002 ambassadors, as example.
Depending on how well these 150 people groups overlap with other 150ppl groups - depends how strong is county identity
Everything above, are not just a big numbers, it is not linear grow complexity of all tasks, every single task that is connected to people managment's. It is at least O(n2).
It's reasonable to take current sizes of counties, in therm of peoples. Our governments systems also developing with people grow, but at any given time they are on the edge of their capabilities.
Even with perfect, state of art tech and system, human brains are limiting factor, and in given time as 300 years, it will to stay a significant limiting factor. Even with tech developing, which may substitute and extend some capabilities - it will stay major limiting factor. And that's good actually.
## Notes
As note I have to say that 6dos theory is't confirmed yet, as far as I know. Because of different obstructions, complexity of task, not well defined metrics etc etc.
But interesting numbers from FB [this](https://en.wikipedia.org/wiki/Six_degrees_of_separation#Facebook) and [this](https://research.facebook.com/blog/three-and-a-half-degrees-of-separation/)
* It had over 5.8 million users, as seen from the group's page. The average separation for all users of the application is 5.73 degrees, whereas the maximum degree of separation is 12.
* The average distance we observe is 4.57, corresponding to 3.57 intermediaries or "degrees of separation."
* Within the US, people are connected to each other by an average of 3.46 degrees.
So many may personally to feel difference between 6 and 3.57 degrees of separation. And 10 and 2000 friends)).
## Country size estimation
* As reasonable number of people who identify them self with particular country, and territory, I would take something between 100 and 2000 millions of peoples.
* As territory 10 km2 average per person. Way too much, but why not if it is plenty of land there.
As result 18000-80000 km radius from metropolis with 10km per person
Or 5600-25000 km radius if 1 km2 per person. (My personal favorite)
Or 1488-6666 km radius with current 0.0695604 km2 per person.
## Naval transportation
People do not forget about dirigibles it will be very useful even with, and probably with, our tech, when it comes about distant land transportation covering. Specially if there will be consistent air flows like on earth, add solar panels and with air bearings it will be sweet - never breaks never have to to refuel. It will be like dream, not fast dream but comfortable, large, which may transport you to any point on land and on sea, cheap, efficient.
As personal recommendation for OP and important moment allowing to investigate large swarms of peoples I recommend, also for any who is attracted by this question, to think about [O'Neill cylinder](https://en.wikipedia.org/wiki/O%27Neill_cylinder) aka space habitat. It is actually the same situation, from social point of view, with same huge amount of peoples, huge amount of surface, huge amount of space habitats, but without handwavium. And actually is possible 30 years later after stated by OP tech.
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To add a little to Josh King's answer, it's not just the speed of travel and the speed of communication, it's the speed of culture that really limits an empire.
If the group is united, then it could spread unchecked to surround the entire sphere.
But if there is any differences between them then different cultures will start to form, and then those will split off as they get to far from the center of culture and become something "other".
You'll see this in a small way if you look at very large cities:
[](https://i.stack.imgur.com/oTGSz.png)
In some ways New York is the center of culture for the U.S., and is very ethnically diverse thanks to it being one of the main points of immigration in the past.
If New York grew to consume the Earth, those neighborhoods would by and large remain, and if the Empire of New York was weak, its culture tenuous and fragmented, and it was unable to maintain control, it's likely that those neighborhoods would leave the empire to do their own thing.
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Only real way to keep distant areas under central rule is to be able to project power, in other words be able to go and remove anybody who tries to rule without approval of the central government. Another critical need for power projection is to be able to defend the edges from external threats.
Only reasonable way to project power with WW2 technology (or even today's technology) over ranges longer than range of airplanes is by naval fleets. To be able to actually keep projecting power, you need supply lines. I would estimate maximum reasonable supply line length to be... say, 100 days. Assuming cargo ship speed of 1000 km/day, that's naval distance of 100 000 km, two and half circumferences of the Earth. So depending on geography, maybe half of that as bird flies.
Any larger than that, and fringe parts of the empire will start to secede and claim independence. This happens as soon as population at edges is large enough to sustain their own army. If the central government tries to support their power projection from too far of their seat of power, well, they just gave someone means to turn that power against them and secede even more easily.
Only way to be larger than this would be by being truly good government, but I doubt that is possible. There's always corruption, inability to really care about people 100 000 000 km away etc. Central government won't be able to stay good government for the edges of the empire. So they will want independence, and they're too far away to be stopped at this distance I estimated above.
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Josh King is quite right about transport and communications being the bottleneck on any civilisation, and given Earth-like political conditions that match the tech to the time as it were transport is more important and his math is probably about right.
BUT, if we pick a different political model; say ancient China or Rome after they split the empire, and scale up what you get is a civilisation that is centrally organised but realises it cannot make realtime decisions throughout it's territory. Central government makes policy but leaves the actual governance of the people in any given province to the locals. I don't know about establishing an empire using this model but once in place it could cover the whole world as round-trip communications are going to take on the order of an hour and a half to two hours. Transferring people and equipment around to respond to crises is only necessary within or at most across to a neighbouring province so transport speeds stop being a handicap.
[Answer]
The real issue is how do you keep them at WW 2 level of tech for longer than a few years. As soon as you have hundreds of millions of Earths linked by telegraph lines the pace of technological change will become unbelievable.
As for the max size of the empire, ancient empires seemed to max out at a few months of travel time (3 to 6? Something like that. Mesopotamia was too far to be ruled from Rome. Scale that to the speed of travel in WW 2 and you have half of an answer).
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Here be the dragons, here be the elves, here be the humans, here be the trolls. I get the basic, but I am torn apart:
**How realistic does the fairy tale world have to be for average 12 year old reader?**
Recently I did read a really great book "Dark Lord: The Teenage Years/ The Early Years" from Jamie Thomson and even when I am 34 years old, I totally enjoyed it.
But, the fairy tale world seemed to me totally unrealistic. The economy of such world seemed to me as not working ... and therefore lets rephrase the question:
What should I take in account when creating a world for a fairy tale story where intended reader is 12 year old (boy)?
And, what can I skip, knowing that only 30-something old people will nit-pick me about it?
[Answer]
When I was 12, I ignored the following (and I loved to read about the details of a world!):
* The overall geography, beyond the parts that characters roamed.
* Anything not on the planet, if the story take place on a planet (I wasn't too astronomically-minded then!).
* Most of the science of the world - I didn't quite care about whether or not the biomes were in the right places, nor about the reproductive cycles of specific animals.
* The languages spoken, beyond the language that the books was written in and the characters spoke (English, for me). A love of Tolkien came later.
I cared about:
* The history of the various groups involved.
* The trading of goods, although not the economy.
* The culture of all the groups involved.
* What the characters looked like, and their characteristics (e.g. What do the elves look like and behave?).
* Maps of the places where the characters went.
Basically, I looked for the cultural things and the interactions between various people and groups, while I didn't pay attention to the science of the world. The progression of the story was more important to me than the justification for things working the way they did.
[Answer]
# I think you're asking the wrong question
While I like @HDE226868's answer, I think you aren't approaching the problem from the right angle.
This problem isn't specific as you think it is, **it's a much general problem**: which parts of your story and of your world should be well-crafted, and which ones can you skip?
This problem happens in **any** work, for any target.
# The richer, the better… but!
The richer is your setting, the better it will be perceived by everyone. **This doesn't mean you must write about everything**, this means **YOU** must know how everything works and why.
If you can, ***hint* at everything**, so that every reader of every age will realise you are not just throwing random numbers and stuff, and this will broaden your audience, and gather respect of anyone who notices (and they will be your most vocal supporters!).
What you have to decide, then, isn't if your world has to make sense in every aspect: it does have to. What you have to decide is which areas you should write about most.
## A general outline
In case it wasn't clear, I didn't mean you must know everything *in detail*.
I mean that you must have ***a general outline* about everything**. You'll then add details were needed, of course.
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**Fairy-tale worlds don't need very detailed as long as you address the kinds of things a 12 year old can comprehend**. Priming yourself with research about development at age 12 will go a long way towards determining what to include or exclude from your story. That said, [Making Money](https://en.wikipedia.org/wiki/Making_Money) by Terry Pratchett is a completely whimsical book that taught me more about how money actually works than any economics book I've ever read.
**Things 12 year olds understand**
[Children around age 12](http://childdevelopmentinfo.com/child-development/piaget/) can comprehend abstraction and formal systems. They are just on the cusp of becoming more independent. Friendships and social situations are [really important to them](http://www.stanfordchildrens.org/en/topic/default?id=the-growing-child-school-age-6-to-12-years-90-P02278). They won't understand complex systems
You can get away with a low fidelity world (because a 12 year old is unlikely to know enough to know better) but you may engage your readers more if you provide them with a high-fidelity (but low resolution) world. Emphasizing the aspects they understand while including aspects they may not get yet increases readability and may expand your readership to older readers who *will* understand more complex systems.
[Answer]
What I find important for creating lands like this is making it easy to understand the parts of the world that matter, and letting that slowly expand to a larger world.
As an adult, we know that things are tremendously interconnected in delicate balances. If we read a fairy tale book at an adult age, we can suspend our sense of disbelief if those balances "feel right." At 12, we already understand that delicate balances exist, but a larger portion of the world appears unbalanced because we simply do not have the experience to see where the balance is being made.
Accordingly, a good book for a 12 year old will get the *kind* of balances that 12 year olds deal with right. If there is sibling rivalry in the book, that has to be done "right." They don't mind so much if the international politics aren't quite right. A good fairy tale for a 12 year old should not depend upon the subtle details of such politics (unless that's your target demographic of reader, in which case, *full steam ahead!*)
A great book, for 12 or 34, is one which can portray its essential meaning to a 12 year old's mind, but hide just enough details in the wording that a 34 year old can reach out and piece together the world surrounding it. If done right, the 12 year old can learn from the book, while a 34 year old that read the book many times when they were 12 can still learn something about how society functions and how people function, even if the "core" message was learned years ago.
One visual metaphor I find successful: if I were to think of my story as a picture, the main points should be big color blocks. I don't want them to be missed. However, I want to make sure that, at all times, there are subtle nuances to the colors to suggest that, if one looks a little bit further, there's another layer to be explored, done with smaller and more subtle blocks. **If, at any layer, I always feel like I have a complete message and simultaneously feel like there's more to be had if I were to dig at it, I find the book to be very successful.**
[Answer]
Well considering that most 12 yo don't understand economics more than you need green to get what you want and "my parents can/won't let me get it!"
Generally if you have money you can buy what you want. Often it doesn't even need to make sense as to why one person has something for sale. Often for anything in a good YA story you only add the details you need to make the core story work. Often people don't even need to worry much about money, things just work, or someone has enough etc. It depends and what is important to the story for who much detail you need to put into it.
It's kind of like using the toilet, unless it's an important scene, there is a lot that is just assumed, with no details needed.
[Answer]
I think readers are very forgiving as long as what you do include is justifiable and makes sense in your story. So if you are just at the planning stage then get your story together and let that help you decide what needs to be in or not.
Sorry if I sound bit simplistic but it seems to me that you're over-thinking this. Artemis Fowl/ Eoin Colfer deals with fairies in a very tech savvy way and while it isn't what I would chose to do it all makes sense in his world.
Don't underestimate your readers either. Likely they play on PS and PC and have wide-ranging interests. I know kids reading Terry Pratchett, Frank Cottrell Boyce, Narnia, Harry Potter. These are all successful because they don't talk down or dumb it down. Good luck!
[Answer]
I think this can be answered with reference to the canonical, best selling young adult fantasy novel series, Harry Potter, loved by 12 year old boys all over the world. In fact my son who is 9, has read the whole series twice, I had to put them away so he would read something else.
There is almost no aspect of the Harry Potter setting related in the books that is not immediately engaging to the young mind, both female and male and is instead superfluous. While some details included may not be entirely essential to the plot, I think this series demonstrates that a lovingly crafted, detailed world that is well aimed at its audience will, all else equal, beat a less detailed equivalent. This is not to say you cannot write a good fantasy story a 12 year old boy will appreciate in low-fi, but it probably won't be as good.
I believe that a key part of Harry Potters appeal to the young reader is the carefully developed relationship between the world of Muggles and Wizards. Every young body reading it is accordingly transported out of that actual muggle world he inhabits and the Wizarding world. The fact that Harry starts his journey in the Muggle world and regularly returns to it serves to anchor what is a highly fantastical setting to more mundane events which the 12 year old reader instinctively understands.
Another key element designed to draw in the young male reader is Harry's sporting activities in the highly dangerous sport of Quidditch.
Finally and most importantly the books carefully develop a series of antagonists which at the beginning of the series are basically schoolyard enemies/bullies and unpopular teachers, immediately recognisable figures of menace to any pre-pubescent child. The way these initially slightly menacing individuals grow into much more real threats throughout the series is very well accomplished.
So with reference to your setting, is there any reason a Fairy cannot use a mobile phone (at least when he or she is present in the mortal plane)? How has interaction with modern man changed the fairy world and economy. I suggest that if you develop a background for the fairy world as it was in the 15th century and then work out how it has co-evolved with the modern world, you can derive an interesting setting.
This is not to say your fairies need to employ technology, but they may have evolved to display certain similarities of culture or economic organisation to that which is familiar in the normal world today (could fairies develop a non technological version of social meida?).
However you do need to find some method of grounding your world on concepts and characters which have traits which are very familiar symbols to your target audience. The schoolyard enemies and friends, the mobile device/tablet and social media, parents and siblings, video games, school/lessons, holidays, figures of authority etc.
These symbols will become more effective where they are integrated carefully into the world building of your setting such that the more potent and recognisable or crucial to the plot the symbol/archetype employed is, the more you invest in the world building behind that aspect.
] |
[Question]
[
I showed a draft of a short story I wrote to some friends and got a very derisive comment from the chemist in the group.
According to him the chemistry just isn't possible.
I'd like a second opinion.
The short of it:
It's the year 2970 and humanity has finally cracked the FTL drive and starts to colonize worlds far away.
They find a world with perfectly Earth-like conditions. It even has complex live (non-sentient) similar to Earth. The alien life is even carbon-oxygen based with a bio-chemistry that is very similar to our own. There are thr equivalent of plants, herbivores that eat those plants and carnivores that eat the herbivores.
Unfortunately for the colonists the bio-chemistry of the alien life-forms isn't compatible with Earth lifeforms. Earth live-stock can't eat the local plant-life. Meat from alien animals/alien plant-material is at best indigestible to Earth life-forms (including humans), at worst poisonous.
Luckily Earth plants can deal with the alien soil, so the colonists can setup an Earth food-chain starting with plants.
The opposite isn't true: The alien life-forms can and will eat Earth bio-mass. Alien herbivores find Earth plants tasty. The alien carnivores consider Earth live-stock (and especially humans) a nice snack.
My story revolves about the fight for survival of the colonists against the alien biosphere.
Now the chemist (an-organic chemistry, he is not a bio-chemistry expert) claims that this won't work.
According to him, if the alien bio-mass is indigestible (or worse) to Earth life-forms, the opposite has to be true as well. It works both ways.
Obviously that would kill my story altogether.
I'm not so sure he is right. I would presume that it heavily depends on the exact mechanics of the digestive system of the alien life-forms. If that first breaks down the Earth-chemistry bio-mass into small chemically simple compounds that are easily digestible this could possible work in my opinion.
Who has the right of the matter. Can this work or made to work?
[Answer]
**Arsenic $\times$ Phosphorous**
Make your alien lifeforms able to use arsenic while our earth lifeforms can only use phosphorous.
Voilá. If your alien lifeforms eats earth lifeforms the arsenic in their blood outcompete the phosphorous on the food (preventing phosphorous from being toxic), while if earth lifeforms eat arsenic based lifeforms the arsenic displaces phosphorous and kills earth's lifeforms.
Its possible if someone finds a way for arsenic to work on a cell and do the same things that phosphorous does for our cells.
>
> Arsenic, which is chemically similar to phosphorus, while poisonous for most life forms on Earth, is incorporated into the biochemistry of some organisms.[19] Some marine algae incorporate arsenic into complex organic molecules such as arsenosugars and arsenobetaines. Fungi and bacteria can produce volatile methylated arsenic compounds. Arsenate reduction and arsenite oxidation have been observed in microbes (Chrysiogenes arsenatis).[20] Additionally, some prokaryotes can use arsenate as a terminal electron acceptor during anaerobic growth and some can utilize arsenite as an electron donor to generate energy. ¹
>
>
>
¹ [Hypothetical types of biochemistry](http://en.wikipedia.org/wiki/Hypothetical_types_of_biochemistry#Other_exotic_element-based_biochemistries)
[Answer]
# [Chirality](http://en.wikipedia.org/wiki/Chirality_(chemistry))
We may remember this from basic chemistry! There are molecules, especially biological ones, who can have the same formula but be different arrangement of atoms. In a biological context, if you eat something with the correct formula but wrong chirality, it may be [poisonous or ineffective](http://toxsci.oxfordjournals.org/content/110/1/4.full) for you.
If their biology is similar, but of opposite chirality, the two groups are poisonous to each other but can still use the basic environmental factors to produce an food chain. In earth biology, shape matters, and chirality is important in determining if a protein is the right shape, is ineffective, or is deadly.
Sorry, but it seems your chemist friend has a very valid point.
[Answer]
[Chirality](http://www.vanderbilt.edu/AnS/physics/astrocourses/ast201/aastruct.html)
Earth-life almost exclusively uses what are known as left-handed amino-acids. What that means is that most amino-acids can be "mirrored" - you can reverse them - but our life is only set up to handle the "left-handed" version. You can create the right-handed versions, but our biochemistry can't process them. You will want to check with a biologist to be sure, but my understanding is that this is just a quirk of our evolution - it's just as likely that we could have ended up using right-handed instead.
However, what if your alien life, for some reason, evolved to use both left-handed **and** right-handed amino-acids?
Then they can consume earth life, although probably not exclusively, because they can handle both types. But if we try to consume them, our chemistry can't do anything with the right-handed amino acids, rendering them indigestible (or at the very best, extremely un-nutritious).
Edit: looks like I got scooped by the other answer + comments.
[Answer]
Actually I can offer a completely different answer to the others - what you describe is entirely possible.
Have the earth and the native species both basically compatible in terms of both being able to eat each other. However the native species would use some chemical which is poisonous to earth species within their bodies.
This can either be a deliberate defensive evolution that local predators have adapted to overcome or it could be a coincidence that a chemical they all use is toxic for earth lifeforms.
[Answer]
Let's talk about some of the common chemical types used in life:
1. Sugars
2. Amino acids
3. Nucleotides
4. Other factors
5. Putting it together
**Sugars**
As mentioned above, both Sugars (the chemicals used for energy transport and storage) and amino acids (the chemicals used for cellular structures) are chiral (meaning they have left & right handed types). Use the above answers to see what handedness matters.
At the worst, the odds of using the same sugar chirality is 50% (some experiments have shown a preference for one handedness over the other in some reactions).
If non-terrestrial biology uses sugar in its energy storage and transport mechanisms and we share chirality, then we should be able to absorb and utilize the sugar from non-terrestrial organisms.
**Amino Acids**
Another aspect of amino acids is that I read somewhere (but can't recall where - so no reference) that terrestrial biology uses 47 of the 50 amino acids most commonly found in nature. Meaning it isn't a stretch to suppose that other biospheres using amino acids in its biology will likely use most of the same amino acids.
As above at the worst, the odds of using the same sugar chirality is 50%.
If they also share chirality, then we should be able to break down and absorb at least some of those amino acids.
**Nucleotides**
Terrestrial biology uses DNA and RNA to store and transmit genetic information. In terrestrial life, DNA uses 4 nucleotides and RNA also uses 4 nucleotides. However, RNA uses Uracil in place of Thymine in DNA. That means terrestrial biology uses a total of 5 different nucleotides.
I'm not a biologist but I assume that other nucleic acids would serve the same purpose, however, those used in terrestrial biology out-competed all other methods of storing and transmitting information over the last 4.3 billion years.
I assume this is both due to it's ability to preserve that information as wells as providing an extremely small probability of mutation (which gives the species a chance to adapt to other environments).
**Other Stuff**
Let's assume chirality isn't a factor and the non-terrestrial biologic uses at least some of the same sugars and amino acids. There are some other interesting things to explore.
One that I found fascinated was the fact that much terrestrial animal life uses a protein analogous to hemoglobin to transport oxygen.
In octopi and horseshoe crabs, this protein is called hemocyanin and uses *copper* instead of iron as the critical metal ion.
Other metals used in hemoglobin analogs are *vanadium* and *manganese*. However, all three of these analogs are much less efficient than hemoglobin (<1/4 for the best).
Another thing to consider is that terrestrial life develops to survive in a specific environment. Freshwater fish can't live in sea water (it's too salty). Salt water fish can't live in fresh water (not enough salt).
Organisms which consume plenty of a vitamin through its diet, lose the ability to produce that vitamin (e.g. human bodies can't make vitamin C).
Elements become toxic to organisms which are unused to exposure to that element (e.g. the arsenic comment above).
**Putting it together**
No one knows what alien life will be, how it will function, what chemical processes it will use, and whether that chemistry could digest ours. However, if the non-terrestrial life uses process similar to that of terrestrial life (which isn't entirely improbable) then we can make some guesses.
If we both use sugars and share chirality, then terrestrial and non-terrestrial organisms can digest each other's sugars. Otherwise we can't.
If we both use amino acids and share chirality, then terrestrial and non-terrestrial organism can digest each other's amino acids. Otherwise we can't.
Organisms from one biology are unlikely to be able to co-opt, infect, or otherwise bother the cellular operation of each other directly (no viral cross infections).
However, organisms from one biology may happily set up shop in the body of organisms of the other biology (e.g. alien bacteria living in our mouths). It may take a long time for our own immune system to adapt a response to shutdown those opportunistic colonies.
For planets with different elemental abundances, we may find that common composition of the organisms contains enough of certain elements to be toxic to the other. I would expect that in most but not all cases, this would mean the toxicity goes both ways. However, in certain special cases this might not be true.
So if you're writing a story of the type you outlined, then you could sprinkle in some of these factoids and then make comments that it is highly unusual for two biologies to have an asymmetry in toxicity like the one you describe.
Even if it turns out to be unlikely it's certainly possible and know one knows whether it is truly plausible or farfetched.
[Answer]
Well, I'm not a biologist or biochemist, but I think your scenario could be made to work (although still very unlikely) as follows:
Our genetic code is based on four nucleotides which make up two pairs of complementary bases. Now there's no reason to assume that the genetic code of the aliens is the same; indeed, there's no reason it should be restricted tot he same base set. However, in principle, it could be that it uses those four nucleotides we also use *and then two more*, so it is based on three different base pairs. Since the genetic code is that fundamental, every single of those alien life forms would have those extra nucleotides. Now if those extra nucleotides are poisonous for us, we cannot eat anything from their life. However we don't contain anything that's poisonous to them (all our DNA bases are used by them, too), so they can eat earth food quite fine.
Alternatively, their DNA could be made up of the same bases, but they could use a superset of the amino acids used by earth life forms to build proteins. Again, if one of those extra amino acids is poisonous for earth life, then you get what you want.
Now there's one open question: How can it be that it is poisonous for *all* life forms on earth? I think that would be easiest explained for the extra nucleotides: Since our genetic machinery (like the ribosomes to interpret the genetic code, or the DNA duplication/repair mechanism) is not prepared to those extra nucleotides, their presence might cause those processes, which are at the very base of *everything* going on in our cells, to fail. On the other hand, those alien life forms would have no problems with earth material since the nucleotides are the same.
A similar mechanism could be at work with the amino acid suggestion; our ribosomes may erroneously build those alien amino acids into our proteins instead of the correct ones, because they are not prepared to distinguish them; this leads to dysfunctional enzymes and proteins, and thus to death.
Note however that while this would be a *possible* solution to the problem, it would still be a highly *unlikely* one: It is far more likely that the alien life forms would have evolved to have a completely different biochemistry, which means we would be as useless as food for them as they would be as food for us.
Well, unless one assumes that evolution on at least one of the planets (earth or that alien planet) didn't start naturally, but as experiment by some intelligent species; then that intelligent species could have intentionally made that similarity plus specific difference, probably in order to study what effect that difference has on evolution.
[Answer]
Changing the alien digestive system to break everything down to a level where chirality is not an issue may be possible, though is going to be quite complex compared to our approach of just dissolving the food and using whatever we find in it fairly directly.
The main thing you will need is a way to synthesize all those complex proteins more or less from raw materials. Using bacteria is probably the easiest approach, rather than adding a bunch of new organs. The conditions for forming new proteins would be quite different to what you need to break down the old, possibly incompatible ones, so the aliens will need multiple stomachs.
Ideally the usable proteins would get filtered out at some point so they don't have to be recreated, but I don't see a way that could have evolved - breaking down everything could be useful since absolutely anything they can find will be a balanced diet, but they have no reason to expect minor variations that only exist on another planet.
I don't have the math to confirm it, but I suspect this approach is going to have some energy efficiency problems - there is a reason we let plants produce most of what we need. At least some of the food will need to be usable as is to power the complex digestive system.
It seems a little unlikely that something this inefficient would end up dominating the planet, but it's not completely implausible, and it gets you a creature that can eat absolutely anything as long as it eats massive amounts of it.
For a simpler approach, make the basics completely compatible, and add some poison. There are plenty of examples of plants evolving poison and the animals that eat them evolving a resistance to that poison. No reason it couldn't end up happening with pretty much every life form on the planet.
Even if the animals are not affected by the poison, it may make the alien plants taste awful - given a choice, they will always eat something from earth.
[Answer]
**Use biology**
You can actually displace this phenomenon to **biology** instead of biochemistry. Consider the mitochondria, which is believed to be a the result of an ancestral symbiotic relationship between eukaryotes and prokaryotes.
Now, what if a similar symbiotic relationship exists with these alien organisms which makes them indigestible to earth organisms? That is, earth creatures have no problem eating these alien organisms, only with these symbionts (which are poisonous, let's say). The alien organisms would naturally have no problem eating each other (since they evolved together) and **may or may not** have problems eating earth organisms (if the chemistry is as similar as you claim, I would say the latter).
This is really the only way to have "similar chemistry" and still have the phenomenon you want. The above posters give ideas which create huge differences between alien-earth biochemistry (chirality, biochemically speaking, can be as different as an apple and a suspension bridge; its like the idea of tones in Chinese languages, a different tone makes the word have a completely different meaning).
EDIT: Found a **much** better solution:
**Use L-Glucose**
D-Glucose is used by almost all higher organisms (multi-cellular) because one of the first enzyme in the glycolysis pathway, `hexokinase` cannot phosphorylate L-Glucose. Hence, L-Glucose cannot be used as energy by most organisms (though it tastes just the same as D-Glucose).
However! L-Glucose *can* be oxidized by the enzyme: `D-threo-aldose 1-dehydrogenase` which found in certain organisms such as Burkholderia caryophlli (a plant pathogenic bacterium, according to wikipedia. Thus the solution is simple, just make all the organisms on the alien planet utilize L-Glucose as their primary energy source.
To allow them to also metabolize earth organisms, give them non-stereo-specific enzymes for metabolizing D-Glucose
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[Question]
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## Background
For my own entertainment, I have been designing how I would hypothetically make a spiritual sequel to **Arcanum: of Steamworks and Magic Obscura**. It is hypothetical as the work needed to do it right is beyond my abilities and resources but not my imagination. THE major interesting feature of this game was the interplay between magic and technology which are largely mutually exclusive/antagonistic in this world. The flexibility of a mage compared to the difficulty to achieve mastery in any area for a scientist meant that the game was a lot easier for the first group but boring to play multiple times as a mage. I usually write Sci-Fi stories (and do nothing with them) which means I automatically wanted to find a systematic way to handle magic which is significantly different from the original but would solve these issues.
## Basic Plan
All magic in this world by my current plan **has a color** and difficultly. Whether a mage can cast the spell is dependent on his color (no not race) and power. I wanted color to be described by 6 cardinal directions which in the simplest case is an octahedron.
One of my main hopes was that the appearance and interface would change depending on the character's expertise in a given area. It would start and octahedron far any user. As magic developed would become a triakis octahedron. By end game, it would be a constellation, geometric design, flame like fractal, crystal, lightning branching structure, etc. depending on the mage's particular aptitude. This means for a powerful mage, the auras would become the major aesthetic difference from the increasingly detailed gritty, steampunk appearance of the world from the eyes of a scientist.
For magic, the most obvious directions would be fire, earth, water, air, light, and darkness. The point is that a mage could cast pure fire or pure light spells but not pure light and dark spells. Any electric, lava, astral projection, life, or healing spells would be combinations of these. The issue is, I need have appropriate real colors which correlate with each of these. Unfortunately, the colors that first spring to mind are red, brown, blue, light blue, white, and black. These will not work well.
## What am I asking for?
I want a (preferably) continuous map of magical abilities that has a superimposable color map. The idea is that from the level/size of the aura and the color of the aura, an experienced oberserver can know which spells (that the observer knows about) the mage can cast. It must be inherently designed such that no mage (no matter how powerful) can become a master of all areas of magic. Spells analogous to those from the original game's colleges (listed below) must have an intuitive place of the map. The map should attempt to distribute these over the map as uniformly as possible so one particular build is not overpowered. The designer is free to add additional (but logical) spells or colleges, break up colleges, or revise them to make this work out better/easier. Ideally colors should aethetically mesh with the type of spell in that area.
* Air
* Conveyance (telekinesis, space warping, and teleportation)
* Divination (detect magic, see contents, identify magic properties)
* Earth
* Fire
* Force (electric, force push, disintegrate opponent)
* Mental (charm, control will, stun)
* Meta (magic about magic such as silence or reflect spells)
* Morph (turning things into other things such as opponents into sheep)
* Nature
* Black Necromancy (talk to dead/trap in rotting corpse, raise undead, extract soul to kill)
* White Necromancy (heal, resurrect, essentially nice versions of necromancy)
* Phantasm (light based spells such as blinding flashes and illusion casting)
* Summoning
* Temporal (time based magic such as slowing enemies while speeding allies up)
* Water
I have included my best answer thus far but am not satisfied with how certain etherial magics (meta, mental, temporal, conveyance) fit into it. I am also uncomfortable with what type of magic should be purple (or how else to jump between the red and blue without going green). While that answer attempts to address it, I believe that one side of the map is very unbalenced.
[Answer]
This may be a little unconventional, but I propose the following candidates for axes:
* **Normal-Strange** How close to natural occurrences is the spell? A flame or a gust of wind are rather ordinary. A floating object, not so much, but still not extreme when knowing magnetism. A walking corpse or a local disturbance in space topology, however... you get the point.
* **Blunt-Intricate** How much structure is in the spell, how many constraints on it being correct? Hail, an explosion, or a nova don't call for too much precision. A defensive wall already needs a little more. But resurrection or mind control won't work unless executed with precision.
* **Rash-Calm** Is the spell the kind someone would cast in a rage, or after careful consideration? Creative spells tend to go in the "calm" direction, while a curse or a direct attack counts as rash.
I came up with these by brainstorming 16 potential axes and filtering them for applicability to sample spells and correlation. *Though I wouldn't claim to have been very thorough with picking candidates.* Here's a table with example classifications, in which I split each axis only into the two extremes and a neutral slot. The Rash-Calm axis is the innermost distinction, with rash at the top, neutral in the middle and calm at the bottom.
```
Normal Unusual Strange
======================================================================
Blunt Fire, Hail Corrode, Swarm Devouring Darkness
Wind, Fog Push, Bend Alter Gravity
Rain, Sunshine Beacon, Eclipse Aura of Magic
======================================================================
Structured Lightning Mind Stun Infest/Possess
Poison Frighten Distort Space/Time
Stone Wall Thornbush Wall Skeleton Minion
======================================================================
Intricate Disease Curse Netherworld Banish
Identify Barrier, Enchant Transform
Create Item Hear the Dead Portal
```
*Swarm would be an insect swarm or such, Aura of Magic an undirected magic buff.*
I can't imagine the setting or planned content too well, so the examples might be off. But it seems easier to me to map a new spell to these axes than to axes like "Earth" or "Light".
How to map these to colors would probably depend on the distribution of actual spells. I hope they are fairly close to orthogonal, but that of course depends on the actual spells.
## RGB mapping
If those are orthogonal, one could simply map them to RGB. Players will have to decompose colors in any case, so why not make it easy for them? Say, red is rash, green intricate, and blue normal?
Then, black would be calm-blunt-strange, white would be rash-intricate-normal, violet would be blunt-normal, teal would be calm-unusual, yellow would be rash-intricate-strange.
## Dynamic visualization
If you are making a game, you're not technically limited to a static color. Instead of trying to get the most out of color space, you could use the fact that the image is not static. How about those axes:
* **Hue** Red is blunt, then it goes up the spectrum until violet is maximally intricate
* **Brightness** Black is calm and white is the total berserker
* **Noise** A uniform color is normal, and flickering spots or color noise indicate strangeness
The noise could be implemented such that, for very bright or dark characters, the noise peaks out in such a way that the hue can still be determined from remaining flickers, even though the color is technically black or white. This would mean that for perfectly "normal" characters that are either perfectly calm or rash types, the intricacy cannot be told.
In a strange way, that's kind of logical. *Though, if you don't like this, just limit the brightness range.*
[Answer]
If I understand you correctly, each spell sits at a certain point, and the geometric shape represents the set of spells the mage can spell. And each point should have a different colour, representing that point, with inner colours being the mixture of the outer colours. Moreover I'm assuming the following opposite pairs (you only explicitly stated one):
* light — darkness
* fire — water
* earth — air
As you already noticed, black and white are the natural choices for light and darkness. The middle point ("neutral") would be a 50% grey (which actually fits quite well with your suggestion of silver, since silver is nothing but a shining grey).
For the other colours, I'd look at the [HSV colour wheel](https://en.wikipedia.org/wiki/Color_wheel) and choose four colours on a square. For example, looking at [this image,](https://en.wikipedia.org/wiki/Color_wheel#mediaviewer/File:RBG_color_wheel.svg) assuming you choose red for fire, and want fire and water to be antagonists, you'd get cyan for water (which isn't too far from blue), and then have violet and chartreuse green for air and earth, where you still have freedom of which is which.
Actually looking at [this colour wheel with HTML names](https://en.wikipedia.org/wiki/Color_wheel#mediaviewer/File:Hsv_color_circle.svg) shows that the HTML name for cyan (opposite of red) is "aqua", which actually is what this would result in.
Another starting point could be yellow for earth, which would give blue for air, and leaves rose and spring green for fire and water.
Note that there's relatively little freedom of choice if you want mixed colours to work nicely. As soon as you chose black and white as light and darkness, all other opposite pairs *must* be opposites on the colour wheel. You might be able to choose two non-orthogonal directions for your colours in the wheel, though.
[Answer]
An interesting fact based source for these colors would be the [psychological primary colors](http://en.wikipedia.org/wiki/Opponent_process)
```
Black -- White
Blue -- Yellow
Red -- Green
```
What is neat about them is that it is theorized that humans cannot see "RedGreen" or "BlueYellow." This is why its so utterly painful to see badly designed Christmas cards with poorly chosen Red-on-Green color schemes.
I would also highly recommend such a system be dynamic in time, because that's another axis you can use to make powerful magicians create dancing auras. It could also show interesting structures which challenge the "you cannot see both colors" attitude: a highly blue individual who has specks of yellow that dance and sparkle around him, but his body is a deep unmoving unwaivering blue.
[Answer]
My current best direction/color combinations are:
* earth: yellow (color of sandstone)
* fire: red (hue 0)
* ice: blue (color of a deep crack in a glacier)
* light: white
* dark: black
* air: purple
* balance: silver
The issue is that air would have to be purple. I would try to legitimize this by having pure air also involve pure spiritual or mental spells (like divination) and have those involve the appearance of dark purple runes.
This feels, however, contrived for earth and air. I am worried that having a balanced magic user's aura look silver may be difficult to pull off but if done right could be awesome. Air with a spiritual component may also make the white necromancy/black necromancy dynamic from the original into an awkward position.
Important or worrying combination observations:
* Lightning which I always thought should be yellow, would be a light
magenta.
* Energy/Force in general is a combination of air and fire
* Lava is orange
* Apparently water is a purple blue. This may be the best way to separate it from ice.
* For Nature to be green, it would be earth and ice.
* Light/Dark would no longer be as tightly linked with Life and Death as I originally wanted.
* I don't know what earth spells would work with light and dark off hand to offset the now super magical air. I think I would have to overpower lava and nature.
* Steam spells don't exist for good reason (steam should be considered tech)
* Teleportation (Conveyance), unlock can trap, time magic (temporal), meta magic, and some other important spells from the original game are difficult to place without overpowering the air side or defaulting it them all to "balanced but hard".
[Answer]
This is putting me in mind of the color scheme of Magic: the Gathering, so I can use that as a start point.
In my mind your magical spectrum is a sphere withing a cube. All three axes pass through the center of the sphere and you mages abilities can be mapped on the surface of the sphere. The strong mage will cover a large portion of the surface while weaker ones will only cover a smaller portion. These portions are represented by a circle drawn on the surface of the sphere with the center point being the core of their ability and getting progressively weaker the farther away from the center-point that you get. No one can cover more than 120 degrees of arc in any direction from their center. This will leave the diametrically opposed magic unavailable to them.
The color continuum would work like so:
Up and down are Good and Evil so White and Black
North and South are Earth and Air so Green and Yellow
East and West are Fire and Water, which is Red and Blue.
Every point on the sphere is affected by the combination of colors. Up oriented mages are going to have a lot of pastels, where down are going to be muddy. North is going to be very green with pastels and muddy colors both. A Westerly mage will be good with water, but not really be able to do anything with fire. A powerful westrly mage will be able to do some up and some down, as well as a little north and a little south. the *rule of cool* side effect color would be a combination of how much north or how much south or whatever.
I think this kind of thing should make a big portion of you magical system intuitive and consistent to anyone familiar with "Alchemy" and other things.
Where i get the inspiration from M:tG is with the "philosophies" in the colors. Death and Decay and what is associated are black. White is civilization and Order. Green is life, which is chaotic and not always nice. Water is flexible and fluid, like thought. Your various spells would fall along those lines. A conveyance spell to a green mage might mean being slid along the surface of the earth at tremendous speed while a yellow mage would fly. A Black Mage would ride on the back of a nightmare and so on.
You can get creative with this too. Light spells could come from anywhere on the sphere. a Red mage would use fire, a black mage would use a glowing fungus. Water and air mages would both be good at seeming or illusions.
One last note about the cube that is around the sphere. The space around the sphere is the Aether and as such is the purview of deities only. they could posses powers of the spirit that may correspond to the sphere, but are above it.
This sounds like fUn!
[Answer]
Building off @celtschk's answer, you could use something like this:
and have red be fire, yellow be earth (the color of sand), cyan be water or ice, and blue be air (the color of the sky). Likewise, the colors would be lighter for light magic and darker for dark magic.
] |
[Question]
[
The scenario: in September 1985, almost everyone abruptly disappears. Humans, domestic animals, carried/worn possessions, and vehicles currently in motion, vanish, while everything else stays as it was. (I don't know whether there is an accepted term for this kind of setting; if not, I'll use the one I just came up with, 'abruptly abandoned world'.)
A small group of protagonists have effectively become colonists, trying to reboot civilization. In the short term, they will be fine; they have access to all the infrastructure, equipment and supplies left over by the existing civilization. In the long term, they have a tough challenge of figuring out how to reproduce everything they need, before the existing inventory decays to uselessness.
One of the harder problems seems to be fuel for vehicles and equipment. Apparently both gasoline and diesel have limited shelf life, the exact figure depending on conditions and who you ask, but the consensus seems to be that even if you store them in full airtight containers with added stabilizer and away from heat, in a couple of years they will have decayed to the point where engines may fail to start.
I'm given to understand that a diesel engine can run on vegetable oil in a pinch, but vegetable oil has the same limited shelf life for the same reasons. You could produce more, but the quantity of food production that would have to be diverted to this is staggering.
Getting an oil refinery working again would be a huge challenge; those are incredibly complex machines.
It seems to me that 'make fuel from decayed fuel' should be intrinsically easier than 'make fuel from raw petroleum', and we know the latter is possible. Just how difficult would the former be? To take gasoline or diesel whose shelf life has expired, and turn it into (a smaller quantity of) usable fuel again, perhaps by somehow removing impurities? Is that possible? How difficult would it be? What, at a chemical level, is the difference between expired versus fresh fuel anyway?
[Answer]
The book [The Knowledge: How to Rebuild Our World from Scratch by Lewis Dartnell](https://en.wikipedia.org/wiki/The_Knowledge:_How_to_Rebuild_Our_World_from_Scratch) should be a very informative read for you. It covers what one should do in your setting in great detail.
At least, in the long run, the answer to your question is to ignore fossil hydrocarbons altogether. They depend on an industry that was built up from very efficient oil sources. Those sources don't exist anymore. The same goes for coal. You'll need to go for a green reboot. Thus I present to you:
## [Wood/Producer Gas Car](https://www.lowtechmagazine.com/2010/01/wood-gas-cars.html)
## [enter image description here](https://i.stack.imgur.com/aIEgO.jpg)
>
> Despite its industrial appearance, a wood gas car scores rather well from an ecological viewpoint when compared to other alternative fuels. Wood gasification is slightly more effiicient than wood burning, as only 25 percent of the energy content of the fuel is lost. The energy consumption of a woodmobile is around 1.5 times higher than the energy consumption of a similar car powered by gasoline (including the energy lost during the pre-heating of the system and the extra weight of the machinery). If the energy required to mine, transport and refine oil is also taken into account, however, then wood gas is at least as efficient as gasoline. And, of course, wood is a renewable fuel. Gasoline is not.
>
>
>
Those cards were common during the second world war. The Germans even had some woodgas tanks. Nearly a million wood-gas vehicles existed by the war's end, making this a proven technology. The image above is an amateur conversion, but this is probably what you would expect in the post-apocalypse. Professionally built woodgas cars will look like normal ones.
There are several videos on Youtube where people convert gasoline cars into woodgas cars. The process is probably not too complicated.
The big advantage is that these make you pretty independent of local infrastructure. And they look like something straight out of Mad Max. If you reboot civilization in the long run, keep in mind to plant fast-growing wood (willow or bamboo would do) for larger wood consumption.
[Answer]
**Ethanol.**
This was one of my favorite Mythbusters episodes. An unmodified late model car ran very well on ethanol.
<https://mythresults.com/moonshiner-myths>
>
> A car can run properly on moonshine instead of gasoline, without
> modification. CONFIRMED
>
>
> The Build Team decided to test the operability, performance, and
> longevity of cars running on moonshine. For operability testing, they
> obtained three cars of the same make and model, but from different
> decades: 1970s (carbureted), 1990s (fuel injected), 2010s (fuel
> injected, modern). With 192 proof moonshine in the fuel tanks, each
> car was driven on a course designed to test acceleration and
> maneuvering. In the 1970s car, Tory struggled with the engine stalling
> and was unable to complete a full lap. Grant completed one lap in the
> 1990s car, but stopped on the second lap after his engine began to
> stutter and lose power. Kari, driving the 2010s car, was able to
> finish three laps even though she noted slower-than-normal
> acceleration. The 2010s car was used for the remainder of the
> experiments.
>
>
> For the performance testing, the team tested three different strengths
> of moonshine: 151 proof, 170 proof, and 192 proof in a 0 to 60 mph (97
> km/h) acceleration test. The car would not start on 151 proof, it
> averaged 19.4 seconds on 170 proof, and averaged 9.0 seconds on 192
> proof (96% ethanol). Next, at Petaluma Speedway, Tory drove 3 laps
> running gasoline and 3 laps running 192 proof moonshine. The lap times
> in the moonshine-powered car were marginally better. Tory noted that
> even though the acceleration was slower on moonshine, the effect gave
> him better control on the dirt surface of the track.
>
>
> For the longevity test, they went to Thunderhill Raceway Park. Grant,
> in a moonshine-fueled car, attempted to outrun Kari and Tori in an
> identical but gasoline-fueled car. Grant was able to stay ahead of
> them after 3 laps totaling almost 10 miles (16 km).
>
>
>
Pretty sweet. Any liquor store will have plenty of 195 proof grain alcohol which would be enough to fuel a car until you found a big stash of denatured alcohol. Ethanol will keep forever.
I have been trying to get brave enough to pour Everclear into the old Subaru. Maybe I will need a little for myself first.
[Answer]
The problem with storing hydrocarbons is that over time the atomic chains making the fuel will start interacting with each other, moving away from the rather precise composition it had initially and becoming a soup of hydrocarbon with various lengths.
The challenge is that those chains react in different ways with oxygen and do not give a clean and clear combustion, which in an internal combustion engine is bound to happen in a blimp.
Instead of making fuel out of decayed fuel, I think you can better engineer the engine. I remember that when he was explaining internal combustion engines, my professor mentioned that there were certain naval engines (2 strokes if I remember correctly) which by just changing the injection time could burn anything ("even dead sailors or engineering students", as he jokingly put it), and this was an appreciated feature in ships which could not be too picky with which fuel they could get in any harbor around the world. Additionally, such an engine that at full power runs at 60-70 rpm has more time to spare in letting the fuel burn at each cycle (and it can give some odd resonance with the heartbeat of those around it...)
If you can lay hands on such an engine, or make one which work along the same philosophy, you will much easily get a working engine.
[Answer]
**Let's start with a quick [Frame Challenge](https://worldbuilding.meta.stackexchange.com/q/7097/40609)**
It's certainly true that people will take advantage of all the benefits of their former civilization for as long as they can. But unless the disappearances are intentional, you'll be left with far too few people to run refineries... and electrical plants... and basic water systems.... You're focusing on transportation at a time when most people will be trying to figure out how to expand home gardening to produce sufficient food. Most apocalyptic stories have one basic problem: human nature. It's nice to think that we'd work together to reboot civilization, but thousands of years of history prove we simply won't do that. People who don't know how to plant gardens, purify water, and store food will act to horde and control everything they possibly can.
And whomever can control gasoline would be Tyrant #1.
Honestly, your biggest problem will be bullets. But let's get back to your question.
**How do we power transportation in an abruptly abandoned world?**
* Steam
* Horses
And you can bet that people would shift to horses very quickly. That shelf life of only a few years means people are IMO deep into survival mode. They don't have the time to fididdle around with chemistry to lengthen the time an already very limited resource can be used. You suggest "make fuel from decayed fuel," but unless your people are willing to become completely nomadic, there simply won't be enough decayed fuel around to matter. If some genius worked out how to do it without resorting to the complex refining process you've already realized can't be sustained, unless your protagonists happened to be near something like the [U.S. Strategic Fuel Reserve](https://www.pbs.org/newshour/politics/what-is-the-strategic-petroleum-reserve), what was available would only last for a handful of years anyway without strict rationing.
**Rats, I'm back to my Frame Challenge**
Maybe you should change from the [science-based](/questions/tagged/science-based "show questions tagged 'science-based'") tag to [science-fiction](/questions/tagged/science-fiction "show questions tagged 'science-fiction'"). Cars decay, too. Parts for any one car become increasingly hard to find, especially if you're jury-rigging an alternative fuel source to it. Your access to anything other than steam (is there coal around? Can't depend on propane/NG, another limited resource) and horses will disappear pretty quickly without increasingly more difficult forays to secure more quantity. But, as I said, that's just a delaying action. Your people are on a ruthless clock to get a lot of manufacturing back online. With only a random 10% of the population to work with, I'm having trouble believing that.
---
*It's really unfortunate this post is tagged [science-based](/questions/tagged/science-based "show questions tagged 'science-based'").*
@PaŭloEbermann points out that almost all of the horses are gone, too. I'd overlooked that aspect. It doesn't change my answer a lot — people will be using what they can as quickly as they are forced to — but it does seriously underscore how screwed the population is.
That a group of people in any one local area are left behind such that the chemistry of reclaiming decayed fuel can be worked out (chemistry/scientist), the process of reclaiming the fuel can be worked out (chemistry/engineer), the necessary facility (assuming it's not completely trivial, which it isn't or the world would have it today off-the-shelf) can be designed (structural & civil engineering), and then actually built (engineering & construction) feels mighty un-[science-based](/questions/tagged/science-based "show questions tagged 'science-based'") to me. And that assumes everyone is working together and playing nice rather than fighting to survive. The luxury of science is that *someone else* is providing the food (and everything else).
And just to add insult to injury, *domestic animals* are decimated, but not wild animals? So wild horses remain untouched (yay if you're in the southwestern U.S.!) but almost no domesticated horses remain — assuming horses are included in the phrase "domestic animals" (they're usually not) and not cats, dogs, and pet iguanas (what's the point of decimating cats, dogs, and pet iguanas?).
I suspect this is ending up as one of those, "give me a cool idea for my story!" brainstorming questions that won't have an actual worldbuilding foundation because rules, which must be independent of all stories, would be something like, "all the horses survive the apocalypse."
Remember, [science-based](/questions/tagged/science-based "show questions tagged 'science-based'")... The vast, vast majority of apocalypse survivors are out of fuel in one month or less because most if not all of the gas stations will either (a) run out of fuel, (b) run short of electricity to drive the pumps, or (c) run short of maintenance, shutting down the software-driven pumps. If memory serves, people can't simply pop the top of the gas station tank source pipes and siphon fuel out. Folks could start siphoning the many parked cars (that didn't get decimated, like the wild horses...) but that's a time-consuming process in a (for many of the survivors) winter-is-three-months-away world.
And the number of people who have the expertise to modify vehicles to use an alternative fuel is very small, the number who can (once told how) modify the vehicles once instructed is only slightly higher.
Yeah, we're in "declare it to be so" and move on territory.
To be completely honest, I don't think there's a [science-based](/questions/tagged/science-based "show questions tagged 'science-based'") set of conditions that would provide the solution the OP is working for within the constraints the OP has provided.
[Answer]
When gasoline or diesel fuel is stored for a long time, chemical reactions can occur that change the makeup of the fuel. These changes can make the fuel less effective at running engines and can even cause damage over time. It's not easy to reverse these changes and make the fuel usable again, especially if it has become contaminated with water or other impurities. In a situation like the one you described, where almost everyone has disappeared and you're trying to rebuild civilization, it would be difficult to find a way to "refresh" or restore the quality of the stored fuel. Instead, it might be better to try to find a source of fresh fuel or to explore other methods of powering vehicles and equipment, such as electricity or hydrogen fuel cells.
] |
[Question]
[
There is an Earthlike planet inhabited by Earthlike lifeforms including beings that are human for all practical purposes. The primary visible human civilisation is roughly equivalent in technology to Ancient Greece in the period 200 BC - 100 BC. However, the god-emperor-like semi-secret rulers of the world possess technology equivalent or greater than what we have today (2022 CE).
The secret rulers are aware that there are pesky human offworlders with comparable technology visiting their world and they wish to detect these intruders and restrict their intelligence gathering activities. While there are many measures being undertaken to achieve this detection / restriction strategy, this question is *only* concerned with detecting camera usage within population centres by offworlder spies. (Detecting the offworlders as they arrive, fumble their way through the language or exchange diseases with the locals are all out of scope.)
Conditions:
1. Camera detection equipment is built into statues placed such that any person within a town will always be within 100 m of a statue.
2. There is no cultural restriction on the materials that the statue can be made of - the populace know that their rulers have powers available, they just consider them magic rather than technology.
3. Detection station technology is limited to that available in 2022.
4. Power supply and maintenance for the detection stations are non issues, provided maintenance is not required more frequently than daily.
5. Active scanning, if any, must not have adverse effects on the citizens or be detectable by the citizens (eg a solution that scans the area constantly with a multi-kilowatt laser/reflection detector combination that will send everyone blind within a few years is unacceptable, as is even a visible spectrum low-powered laser.
6. Offworlder cameras may be concealable digital cameras or film cameras. However, they are equivalent to off-the-shelf consumer items that have been available in the period 1992-2022 on Earth, not custom creations of a spy agency.
7. Offworlder cameras' electronics (if any) are shielded so RF detection is not an option. The offworlders are also smart enough to physically disable the flash (if any), to avoid any possibility of accidental activation.
8. Offworlders will always deploy a camera from within their robes / under the fold of a cloak etc. They will not hold it up in the open to take pictures nor will they leave it unattended.
9. Budget: Assume that each detection station may contain up to USD 100,000 worth of hardware with a separate and effectively unlimited software budget. Offworlder cameras are price limited to USD 1,000 each.
10. Detection stations are only expected to be able to detect cameras that are pointing at them.
11. Detection stations must recognise that eyes (human or other animals) are not cameras for this purpose and must not return a false positive every time a human, sparrow, moth or goat (or equivalent) looks in that direction.
**Question:** Given the above conditions, how long would the lens of a covertly employed camera 100 m away from a detection station need to be exposed in order for there to be a 50% (or greater) chance of the station detecting it?
Note 1: Every search along the lines of "detecting cameras" provided "how to find a hidden camera in my hotel room", which is how to slowly scan a single room for a camera rather than constantly monitoring a large area for the presence of every camera.
Note 2: While the rulers and the offworlders both have access to particular technologies that are more advanced than current real-world Earth technology, these do not impact this surveillance / counter-surveillance issue.
[Answer]
Active digital cameras are easy to detect. CCD and CMOS cells are effectively retroreflectors, so a bright modulated infrared light source will be visible in them and detectable as long as there is line of sight. 100 meters might be probably optimistic, but many tens of meters would be possible. This is technology that is used in real life and is non-harmful to people.
This will detect close to 100% of cameras with open shutters pointed in direction of the detector that are close enough. Given level of society there should be no other retroreflective things in the open other than cats' eyes, so very few false positives. Use below to sort out the cats.
Film cameras are another matter, because filmstock is not reflective and lenses are usually coated in anti-reflection coatings, thus they are impossible to detect via reflected emissions. (In general case, they are basically impossible to remotely detect, since any box with a pinprick can be a camera obscura. Even CT-scan wouldn't be enough, you'd have to do chemical sample to detect if there is light sensitive chemicals present.)
If you can be sure that a film camera always looks like a camera, then best bet for "today's tech" would probably be to use AI image recognition to pick up lenses and camera looking things in surveillance feeds. This will also allow you to sort out any false positives from the CCD/CMOS sensor detector. Because of variability of AI tech, it is impossible to say how reliable this would be, but it could be anything from 50% to 95% for positives ("camera") with something around 80% likely, and high 90s for negatives ("not a camera").
[Answer]
"Cameras". You leave open the type, the power source, the size, the connection. There is nothing specified about these hidden cameras except they are placed by the offworlders. These cameras might have nothing in common with each other except they stink of offworlders.
**Sniff them out.**
**Magawa dies at 8: Heroic rat sniffed out land mines and helped save lives**
[](https://i.stack.imgur.com/Iqdslm.png)
<https://www.cnet.com/culture/internet/magawa-dies-at-8-heroic-rat-sniffed-out-land-mines-and-helped-save-lives/>
Animals can be trained to find devices based on the smell of those devices. Magawa here found 100+ land mines in his career as a bomb sniffing rat. It will be easier to find offworlder tech because offworld stuff has several different funky smells that are not present on this alien world. To a creature that perceives the world through smell these cameras are super obvious.
--
One could use teams of sniffer animals and search, like they do for mines. I assert though your secret rulers are not that obvious. They do not want the offworlders to know that anyone is searching for their tech. The animals could be trained to work solo and try to get into the cameras and open them up for a treat. Perhaps pest control civilians laconically patrol the city, looking for evidence of rat nests and rat damage and collect the cameras in a disinterested way along with rat nests and other trash, in the interest of civil cleanliness.
Or even stealthier - one could make mutant animals that are especially attracted to the offworld smell.
[Mutant mice become "super sniffers"](https://www.bbc.com/news/science-environment-36745483). We have this tech and so too your hidden rulers.
I like wasps or bees for this. They choose sites that smell like offworlders to place their nests. The nests mess up the cameras. The wasps don't care if the cameras are high or low or hidden in a crack, or how they work: they smell like a good nest site. Even before the cameras are discovered the wasps mess them up.
Insect control persons eventually remove the nests as a public hazard and the cameras too.
Added benefit - the wasps like other offworlder things for their nests. Nests are not just on cameras! The hidden rulers chuckle.
[Answer]
Maybe you could rephrase your problem statement and move detection to an earlier stage. For example, detect the intruders before they land on your planet. Camera is not the only spy tool. So yeah, think of a planet wide intruder detection system. If you can afford, send several satellites into orbit.
When you say world, you seem to assume a city. That's a fallacy I see in many Sci-Fi movies - when they say a planet they mean a city. Imagine having to monitor for camera use in thousands of cities around your world!
So better move it one level up.
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[Question]
[
How could the effectiveness of radar, heat seeking, or laser guided weapons be reduced during a battle between a monster the size of a 7 story building and the military of a small country.
The monster is purely biological, and has no paranormal powers or abilities, and would die quickly if hit with modern anti tank weapons because its armor is "realistic" and couldn't stand up to something designed to kill a tank for long.
Something that would force the military to use unguided weapons, wire guided anti-tank weapons with a human operator (The TOW, for example).
Maybe an environmental factor that could artificially constrain battles to being within visual range?
[Answer]
A lot of systems are looking for an infrared signature, or perhaps doing some image processing to identify the manmade object in a natural background. Since your monster is biological it has low thermal contrast and since it doesn't look like tanks or other objects that the automated systems were designed for, they need to be manually pointed or controlled.
Some systems use laser designators where an operator shines a laser on an object and the guided bomb is designed to hit the spot being illuminated.
For your creature, its skin/fur/coating is black because it evolved for stealth, and the structure of the skin/fur/coating traps the light very efficiently so the laser designators don't work.
For radar, you could also go the absorption route to minimize signal return, or you could have angular surfaces that reflect the energy up and away from the platform trying to shine its radar on the creature. Or if it is in a urban environment there could be a lot of radar clutter.
Environmental factors include smoke and fog, both can limit the effectiveness of modern weapon systems.
[Answer]
**Counterfire.**
The monster has acute senses. And even though it is big, it is fast. It can hear a tank missile taking off. It throws something to meet the missile - maybe a scoop of earth, or flying spikes, or projectile vomit or whatever works.
To hit the monster with something like a missile you need to get very close so it does not have time to react. Many of the antitank munitions do not arm themselves if they have not flown a certain distance, and then they bounce off.
Perhaps your humans set up a remote controlled missile launch station in the monster's predicted path. They neglect to set it up downwind from the monster. The monster has acute senses.
---
**Advanced armaments used up.**
[Has America almost depleted its supply of essential weapons for Ukraine?](https://www.washingtontimes.com/news/2022/may/3/has-america-almost-depleted-its-supply-of-essentia/)
>
> Albert Einstein famously said, “I know not with what weapons World War
> III will be fought, but World War IV will be fought with sticks and
> stones”...
>
>
>
In the world where this monster shows up, there has been a war. Or maybe the war is still going on. Sophisticated antitank weapons were largely used up early in the war; few remain. The industry to make more is also either gone or is devoting efforts to munitions that are cheaper and quicker to make.
[Answer]
**Aluminum!**
Okay, let me explain. All three of these guiding techniques you mention use a scanning method to track their target. And all of them can be countered with (relatively) simple approaches.
**Laser Guidance:** This uses a method called laser painting where you fire a laser at the target and then the missile (or what have you) tracks the target based on how the laser scatters off of it. If the target does *not* scatter the laser and instead absorbs it, then the laser guidance is mostly useless. Laser scattering materials include black aluminum.
**Heat-seeking:** Heat seekers, despite their name, do not actually seek out heat. They seek out infrared light, which is generated by heat. This distinction is important, because it is possible to block infrared light with a conductive metal, like say, aluminum.
**Radar**: Radar is surprisingly effective to use to guide weapons, but there is a caveat - radar sucks at distinguishing objects. In an isolated environment, (i.e. open sky) then yes, it is useful. If you're fighting a kaiju in a building-dotted landscape ... not so much.
Also, radar can be tricked by scattering ions and ion deflectors all over the atmosphere. like say, aluminum. So the monster can belch clouds of aluminum all around it and the radar will be tricked.
Tl;dr - aluminum OP against detection methods, plz nerf.
[Answer]
## Speedy flock of monsters
I live in a small country. Ok, let's suppose this thing is 7 stories high and it eats humans.
And it is not the only one. He brought his herd along, which was 300 individuals at first. Some 15-20 meters each, a herd of predators the size of a brontosaurus approaches my small country.
**Fast and unpredictable**
The Germans tried to use cruise missiles against them last night and failed. These beasts are agile, they are not moving in straight lines, like military vehicles and ships do. The herd behaves like a flock of birds, roaming around for food. These monsters need about 1600kg meat per day.
The herd now moves toward us. They appeared to have crossed the Polish border yesterday evening and then they did Northern Germany overnight. Alarms were set off, NATO fighter jets were deployed, some monsters were killed but it required low altitude flight and agility to keep up with them. No actual practice was ever done by the military, chasing monsters 7 stories high, running at about 200km/h.
**Danger of collateral damage in a small country**
In Poland and Germany, the damage done by the military far exceeded the damage resulting from the flock's presence.
In our overpopulated small country, the collateral damage problem will be worse and that prevented a quick response with our guided artillery. About 280 monsters reached our small country at noon today. The herd passed the German border near Klazienaveen and the population was not prepared for that. These monsters don't walk straight, they roam around and steal cattle, ravage houses, eat people. Multiple Dutch villages got rampaged by them, 60 folks died and about 200 people were wounded. Some are still missing. Their break for dinner was 2 hours later where I live. I managed to escape one.
When drinking or eating, they would be sitting duck for heavy weaponry. But.. how to attack these monsters when they are having dinner where the meat is, that is in populated areas?
**They passed**
Some experts in herd behaviour were consulted by our government and a military strategy was devised. But late in the afternoon today, the herd had already passed the Belgium border in the south. The government decided to cancel the whole plan and let Belgium solve their issue.
[Answer]
## The creature lives underwater
Not only would this sidestep the square-cube size limitations that land-bound creatures have and enable the hypothetical construction of truly massive yet still biological creatures, it would also render most conventional weapons useless as they can't attack underwater.
No modern AT or AA weaponry is effective against targets under basically any depth of water and this includes everything from missiles to mortars to artillery. So long as the creature can withstand the shockwaves that heavy explosives can cause and dive more than 10 meters or so, it is basically insulated from everything a modern army can throw at it excepting:
* Truly big explosives up to and including nuclear ones (the creature would likely need to dive more than 10 meters to avoid these but still easily possible)
* Specifically designed underwater weaponry like mines, depth charges, or torpedoes.
Interestingly, such a creature could possibly even "defeat" the small country in the sense that it acts as a complete naval blockade, sinking all ships that approach its shores. Provided it alpha-strikes the likely small force of submarines and realizes that torpedoes are things it needs to dodge, there is very little that could reach a creature 100 meters down. It just occasionally reaches it's tentacles or whatever up to sink ships, and otherwise stays in the untouchable depths.
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[Question]
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This Fantasy World has very large monsters, intelligent humanoids, expansive unique biomes, ect. While I was making my fantasy world I realised how hard it would be to hide all of this from humans. I was thinking of a few ways this could work out, maybe the world is on another planet, maybe during this time humans are in a more early stage of development (think the middle ages). But I feel like these reasons wouldn't really suite my story, but I wouldn't be too opposed if they made sense. I was thinking of magic, but in my story magic is quite minor and not a very dependable art.
[Answer]
## Earth until 1500 AD
**You can hide for Europeans.. but don't forget other peoples**
You added a magic tag, plausibility may be less important, you could cloak the island with a magic spell.. but I can note on Earth, in Europe around 1350, most islands far away were *myth*. Any remote island would do. Out of reach for Europeans. However, for *other* people.. elsewhere.. that was not the case. Let's do a few candidates,
**Pacific**
Obvious, but better skip the pacific.. in medieval times, the Chinese had ships, [peoples in the pacific colonized islands](https://en.wikipedia.org/wiki/Exploration_of_the_Pacific) everywhere (1200), people able to read and write would find you and spread the news. Maybe Easter Island would be a candidate, near the Chilean coast but I'm not sure.
**Caribbean**
The Caribbean would be out of reach for you, if you don't want to be discovered: islands and areas up north were inhabited, they even received [Maya and Inca colonists](https://en.wikipedia.org/wiki/History_of_Belize) and there was [Maya trade in the Caribbean](https://www.cambridge.org/core/books/abs/sea-in-history-the-medieval-world/maya-caribbean-fishing-navigation-and-trade/2D69638DA2B29BA8D4D011A96D903DF9).
**Southwestern Atlantic Ocean, before 1500**
Most of the Atlantic Ocean was unknown territory for Europeans. Thousands of years, [Atlantis](https://en.wikipedia.org/wiki/Location_hypotheses_of_Atlantis) presumably existed as a large island west of Gibraltar. Beyond Atlantis.. the world was supposed to end.
Don't go *too near* the European continent, they would find you,even in Medieval times. Madeira was a known place, Vikings had explored the north.
So.. find something southwest in the Atlantic..
**Malvinas / Falkland Islands would be a candidate ?**
In medieval times, the Falklands would do fine. [Kelpers](https://en.wikipedia.org/wiki/Falkland_Islanders) claim they are native population, but it is not clear how many lived there in medieval times. The [local population of Patagonia](https://www.britannica.com/place/Patagonia-region-Argentina/Plant-life#ref41681) were nomadic hunters without ships, and European discovery expeditions had not reached that far. The Falklands were discovered in 1504.
[](https://i.stack.imgur.com/2kz6P.png)
## Antarctica until 1800 AD
If you put your story before 1800 AD, *and* your wizards can create some artificial heat, you'd be safe anywhere on Antarctica. It was unpopulated. With magic tricks at your disposal, there's a lot of options to build your world. You could e.g. melt all snow 200km around a lake inland, you'd have water, agriculture, fishery, domestication of penguins for their meat.. you could built cities there.. chance is, nothing would be discovered, until satellite images of Antarctica were published. Candidate..
**Lake Vostok until 1960**
The location of [Lake Vostok](https://en.wikipedia.org/wiki/Lake_Vostok) was not discovered until 1959-1964
[](https://i.stack.imgur.com/jfPxE.png)
[Answer]
## Underground
Maybe it's underground, deep within Earth. It could be unearthed in a ton of ways (Sinkhole, volcano, oil dig, etc.).
Pros:
* We in reality have never gone really deep into the Earth's crust, except for in specific deep dig sites.
* The world would have no contact with surface humans, although it could have had attempts before.
Cons:
* The magical/fantasy world would then logically not have access to the sun.
* It would also be very difficult to get out of, although I'm sure you could figure out a way.
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## PORTALS
Portals, discovered either by accident or through scientific research.
Pros:
* It adds heavily to the fantasy vibe.
* The fantasy world on the other side could have anything you want in it, even custom physics, without need to find how they got there and why it works.
Cons:
* Portals are probably very energy consuming to use.
* This may be difficult to explain as to how it was discovered.
[Answer]
**Awful Island**
[](https://i.stack.imgur.com/Y0z4t.jpg)
The Fantasy world is on an island surrounded by horrible mangrove forests.
[](https://i.stack.imgur.com/AwKIZ.jpg)
The people are on a different island. They don't want to go to the awful island.
[Answer]
**Humans do not notice the fantastic.**
As far as I can tell in Percy Jackson, people confronted with something that does not make sense perceive at as something that does make sense.
I think a better way is to have an escort - a guide who can step between worlds and who can show you the fantastic world adjacent to and intertwined with ours. Eventually you can make the trip yourself.
I wish I could find my copy of [Grimbold's Other World](https://www.worldcat.org/title/grimbolds-other-world/oclc/24788768) - Grimbold the cat can (like all cats) walk between the worlds and he brings the boy Muffler to the Night World. It is an echo of the day world but cats are huge and dogs are tiny; forests still have their ancient grandeur. A old mans shack on the mountain is revealed to be a castle. The fantastic coexisting unperceived with the real is more or less the premise for Mary Poppins, and Harry Potter, and the world of Spirited Away - the magical coexists with the real and the protagonist can move between worlds, somehow.
It is done so often you can assert it to be.
---
I am reminded of the story of the Fairy Ointment. As it turns out this type of fairy tale has its own category in the [Aarne-Thompson-Uther](https://en.wikipedia.org/wiki/Aarne%E2%80%93Thompson%E2%80%93Uther_Index) fairy tale categorization system. Check them out! [https://sites.pitt.edu/~dash/midwife.html#bray](https://sites.pitt.edu/%7Edash/midwife.html#bray) The human lady in the story is usually a midwife and she is given some ointment to put in the eyes of the baby. She gets some in her own eye and then can see Faerie from that eye. Note to anyone who finds herself able to see Faerie: keep that fact to yourself.
[Answer]
**Metaphysics**
1. **Extra-dimensional**
Draw a 2-dimensional character on a piece of paper. Now pick up that piece of paper, move it to another room. Note that it remains a 2-dimensional character, but it has in fact physically traveled through a 3-dimensional world.
Likewise, while us 3-dimensional beings may not be able to perceive or understand the 4th-dimension, the existence of, and ability to travel through the 4th dimensional axis can be part of the nature of your world. Magic need not be used, it is part of the metaphysical reality of the world, and the fantasy world occupies a 3-dimensional world on a parallel 4th-dimensional axis. Only those who understand this principal may be able to open a portal to traverse between worlds. So this is ultimately a "Portal" method to separate the real world from fantasy, but may have different implications for your story to build upon.
2. **Intersecting Planes of Existence**
One of the most common fantasy trope. Fantastical things are happening on another plane of existence, sometimes it influences the real world but we can't interact back with it, which might explain paranormal phenomena.
Harry Potter, Wynx Saga are arguably one of the above two.
**Mundane, Physical**
1. Physical isolation, or shielded/masked isolation.
I'm sure this needs very little explanation. This is like Atlantis, Camelot, Wakanda, etc.
2. Political isolation
Think North Korea.
**Social**
The fantasy population is limited, but held together by an organized structure and everyone mutually agrees to avoid letting regular humans learn of their existence due to the inconvenience or threat of a unified human response. This is employed in Vampire Diaries universe and many isekai Anime series.
A personal favorite Mahou Sensei Negima blends all of the above; The magic world is actually a literal underground world within the Martian core, connected through a massive gateway generated by the stonehenge. There's a whole explanation why that is the case and how it was necessary to sustain all the fantasy world people and the impending issues due to it.
[Answer]
# Magic is weakened if too many people tap into it.
There's an extremely limited and restricted supply of magic, from books, to monsters, to biomes, everything. There are locations where it's more common, but they're rare.
As such, most leaders made agreements to hide magic and so only the mega rich elites know of it or have access to it.
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Nothing with mass can reach the speed of light because the closer to the speed of light it gets the more mass it has tending toward infinite mass as it approaches light speed & the more mass it has the more energy needed to accelerate it any further tending toward infinite energy as it approaches light speed.
I'm assuming this mass is relative in the same way as time dilation from near light travel so that it's not felt by anything or anyone who might be traveling at these speeds.
Howsoever I also assume the gravity effects of this mass is felt by external objects that are passed by the items traveling at these speeds.
So (assuming I have all that sufficiently correct?) this seems to mean that passing through (or near enough to) a solar system with sufficient speed to replicate the gravity effects of a large black hole could be catastrophic (to say the least) with the potential to drag planets & even the systems star itself to the fast moving object & compact them around it into a new black hole.
I have so many thoughts, ideas & questions stemming from this ;) but I'm by no means sure I've got it entirely right at this stage, so it's probably prudent to limit myself to "have I got this right so far?"
[Answer]
# No
Relativistic mass is not "real" mass. The gravity of an object travelling at relativistic speeds does not increase, because its mass does not increase. The "mass" added in the Lorentz equations is an expression of the asymptotic energy required to actually reach lightspeed when you have mass.
[No amount of acceleration would make an object into a black hole](https://www.wtamu.edu/%7Ecbaird/sq/2013/06/18/can-you-go-fast-enough-to-get-enough-mass-to-become-a-black-hole/).
Edit: [Forbes explains this at greater length](https://www.forbes.com/sites/startswithabang/2021/02/09/do-objects-get-more-massive-when-they-move-close-to-the-speed-of-light/?sh=3e274b07dad9), but the pertinent bit:
>
> Understanding the answer is the key to understanding relativity: it’s because the “classical” formula for momentum — that momentum equals mass multiplied by velocity — is only a non-relativistic approximation. In reality, you have to use the formula for relativistic momentum, which is a little bit different, and involves a factor that physicists call gamma (γ): the Lorentz factor, which increases the closer you move to the speed of light. For a fast-moving particle, momentum isn’t just mass multiplied by velocity, but mass multiplied by velocity multiplied by gamma.
>
>
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In high school physics, we use the Lorentz formulae and are told that the apparent mass/length/clockspeed of the object changes, but gravity warps spacetime, and so if the mass of the object changed, photons would *behave differently* around it for all observers, which is impossible. From the frame of reference of an observer on the accelerated object, the object cannot appear to gain mass. Which means that spacetime cannot be distorted... and therefore it cannot be distorted from the perspective of a stationary observer.
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No. Gravity in General Relativity is not just about the mass. Einstein's equation sets the curvature of spacetime equal to the *Energy-Momentum-Stress* tensor, which contains one term for each pair of coordinates from x, y, z, t.
The tt term is the energy, and because of the rest mass energy usually pointing in this direction when things are going slowly, this is usually by far the biggest term. That's why it is usually valid to ignore all the other terms and treat gravity as if it was purely sourced by accumulations of mass.
The xt, yt, and zt terms are the linear momentum. When things are moving very fast, these terms get big. However, because of the peculiar geometry of spacetime, it tends to cancel out the effect of the mass. More on that in a moment.
The xx, yy, and zz terms are the *pressure*. This is one of the main reasons why stars collapse into black holes - as the star gets bigger, the pressure in the centre grows, which makes the gravity even stronger, raising the pressure even further. There's a positive feedback loop that means beyond a certain point infinite pressure is needed to balance the forces. Since nothing can supply infinite pressure, nothing can stop the collapse.
The xy, xz, yz terms are the shear stresses. Those are usually small, because no matter is strong enough to resist such forces. With compression, there's nowhere for the matter to go, but with shear the matter flows like taffy.
If you rotate your coordinate system, the numbers change. But it's still the same underlying geometry - just described differently. Rotating about planes involving only x, y, z axes behaves like you would expect, but rotating in any plane involving time works a bit differently. In Euclidean geometry Pythagoras says the squared length of a vector is $x^2+y^2+z^2$, which rotations don't change. In Minkowski geometry, the t coordinate has the opposite sign. So we can define the squared length of a vector using a modified Pythagoras theorem as $t^2-x^2-y^2-z^2$, which doesn't change under 4D rotations. This leads to a relationship between energy and momentum: $E\_0=E^2-p\_x^2-p\_y^2-p\_z^2$, where $E\_0$ is the rest energy (or mass), the length of the energy-momentum vector and a fixed constant in any reference frame, $E$ is the relativistic energy (or mass, the thing that increases with speed), and $p\_x$ etc. are the components of the momentum.
When you shift to a reference frame where the object is moving, the momentum terms obviously get bigger, and so the energy term gets bigger too. This is the kinetic energy. The increase in size of one is counterbalanced by the other, to yield exactly the same rest energy. The energy-momentum vector is not any longer - it's just viewed from a coordinate system where the components in each direction are bigger numbers. And so the 'size' of the whole energy-momentum-stress tensor, and hence the gravitational space-time curvature, is no different.
This does *not* mean that kinetic energy is irrelevant for gravitational purposes. If you have a fast moving particle *confined in a box*, then it bounces backwards and forwards, resulting in momentum currents in opposite directions that *cancel out*. But the kinetic energy term doesn't cancel. If particles are bound together, then the kinetic energy of their confined motion *contributes to their mass*, because the momentum terms cancel out. It turns out that much of the mass of ordinary matter is not the bare mass of the constituent particles themselves, but comes from the *binding energy* that is the result of their confinement, being stuck to one another.
[Answer]
# Frame shift: how about *two* objects...?
Lead answer is right that *one* object can't make a black hole with relativistic mass. But it is wrong in another way: relativistic mass **IS** real mass! Most of the "mass" in the protons and neutrons of every everyday object is the "relativistic mass" of quarks moving around.
If you need any extra convincing, consider what happens if two of your particles crash together. Suddenly all that relativistic energy is spewing out as vast numbers of particles and antiparticles and photons and so forth. So it is certainly conceivable that these two objects could make a black hole with all that mass. (Note the "rest mass" is determined by the velocities of these objects *relative to each other*, because that cannot be reduced to zero by simply picking another frame of reference)
The caveat being that of all the ways to round up the mass to make a black hole, delivering it as free energy has got to be the most *painful* way to do it.
[Answer]
If we take our solar system as reference, an object like the one you describe would cross it from one end to the other of Pluto's orbit in about half a day.
Gravity is a small force and, especially at large distances, would need time to produce significant effects. Time that is not given by the quick dashing through the system.
Considering that the probability of an impact is minuscule, the most likely effect is a small perturbation of some orbit, negligible in the short term, maybe less in the long term.
That apart, consider that to double the mass the object would need to travel at 0.8c, to decuplicate it it would need to move at 0.99 c, an it would still be far from being anything close to a black hole. However, as jdunlop noted in the comment, that relativistic mass does not increase the gravitational pull of the object under acceleration.
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# Yes, as you're travelling through the solar system.
If you travelled fast enough, which is probably going to be a very weird number like 99.99999999% of the speed of light, collisions with protons and other particles will cause micro black holes to form.
This was a fear for the LHC, that it would form micro black holes. You could use much more energy.
The gravity would of course be negligible, since relativistic mass isn't real mass and doesn't change the underlying space time geometry. But, the explosions of energy could certainly do some damage to the solar system, if there was enough speed.
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# Yes.
Consider: <https://physics.stackexchange.com/questions/479299/does-kinetic-energy-warp-spacetime>
A black hole does not form because you reach a certain rest mass energy. A black hole forms because a region of space reaches a certain energy density. Accelerating a mass to a sufficiently high velocity that the region of space it occupies achieves this energy density would form a black hole.
Note that black holes form because of energy density, not total amount of energy. As a result, you can have very low-mass black holes--space is highly curved, but only very close to the singularity. Accelerating things to very high speeds will produce these type of black holes unless the total energies involved (rest mass + kinetic energy) are on the order of solar masses. Such small black holes will rapidly cease to exist thanks to hawking radiation; their energy will be released as a flash of other particles.
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>
> The storyteller sits down. He has a tale to tell, a tale of a village
> that was suffering a drought. A tale of the desperation of the
> villagers. The desperation that led them to seek the help of one of
> the cruellest of tricksters, a Narrator. A tale, of how the narrator
> was one which was surprisingly docile, and didn't cause a flood, or an
> invasion, or a monster to arrive. In fact, the tale goes, no more
> people lost their lives from a cause that was linked to the initial
> drought.
>
>
> The people are pensive. The story, they hear. And they say to their
> neighbours, "please lend me your ear. I have here a tale, important to
> tell, and I beg you to listen, and remember as well."
>
>
>
This is roughly how my magic system would work: someone tells a story, and the story is passed on, until it literally gains a life of its own. This life is a Narrator, who then bends reality to conform with the story that spawned him. Now narrators are not mindless forces, they are sentient, incorporeal, invisible beings. Their most dangerous characteristic is that they can get bored. This is why most people don't deliberately spawn them.
However, some people are such good storytellers, that they can just tell the tale once, and the narrator is spawned. True, not as strong as the older ones, whose story has been told hundred or thousands of times, but it can still make simple things happen, like tiles falling of roofs, or lightning striking a tree's equally tall neighbour instead of the first one.
I would like "wild" Narrators to be a force to be reckoned with, but I would also prefer it if one person couldn't just tell himself a story about a city being destroyed, and it happening.
# Tl;dr: how do I nerf people who are exploiting the fourth wall?
Edit: "Wild" narrators are spawned by wild narratives: in the case of the example, the entire community is deliberately repeating as close to the exact same story as they can get. However, a lot of stories are told and retold so many times that the original is hardly recognisable. These are wild narratives.
[Answer]
**Number of people who've heard it and believe in it**
The most common restriction I've seen for a magic system of this type is that it's powered by the number of people who believe in the story, and for stronger stories, you need stronger beliefs. For instance, let's say there's a story in a small village about a boy finding a well. That could very well meet the requirement. But let's say there's a [story](https://en.wikipedia.org/wiki/The_Mouse_That_Roared) in the same small village about how their small country somehow defeated a much larger and more technologically advanced country. If just the village believe that - no dice, the narrative can't be formed. But if the *country* believes that, then the narrative *can* be formed.
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What if the power of a story depends on either the momentarily total or the accumulated amount of belief or imagination it causes, in the teller as well as in the listeners?
A good story captures your imagination, and makes you see the events told with your inner eye. It might even send chills down your spine! Even if you know that "it's just a story", there is no denying this perception, in itself, is real. The stronger this alternate reality is perceived the more impact it has on reality, but there is only so much imagination in a single person. If you can capture a dozen people's imagination this is clearly more powerful, and capturing a nation might make truly non-trivial things happen.
This way there could be individuals with the power of three or even a hundred average people, who are either born with talent or train their minds at institutions since childhood. These individuals, for whom reality and imagination so-to-speak blend together, could do things on their own which are impossible to most people, but without an audience who vividly listens their powers are limited.
The effect could be linear, with a story seen by the inner eye of six people having six times the power of one told by a person to itself, but more likely not. I like to think that an audience of one is quite a bit more powerful than a story told to oneself and increases rapidly for small numbers, but soon starts to flatten off.
Like mentioned on the top, Narrators could either be fed by spikes of belief which quickly wear off, they could accumulate power to be still sustained by the imagination of people long dead, or some combination.
With this system, you CAN exploit the masses by using them as an audience to something they don't really agree to, while you retain the possibility of people (wise by experience) protecting themselves by either physically preventing themselves from hearing or by suppressing their imagination. Also, at least in a pre-industrial society, finding a large audience is difficult, especially if you are a suspicious Taleteller (What good can come of listening to those?)
This gets a little meta, but I just realize that for people to be suspicious of Taletellers, they must, in some way tell stories about them to warn eachother and their children. Does this somehow feed the system? Or do the True, very old and often retold, tales of history feed more stable and "boring" Narrators, like a sort of relatively passive gods?
Do Narrators care about how their stories are told? Does altering a story weaken the power of a Narrator or cause it discomfort? If so, this might be strong incentive for people telling about History to get it right, not to provoke the gods.
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A Narrator depends on three main things for life:
* The reality of the Story to set a personality
* The Story being told to call it into being
* The Story being spread to give it power
Each of these three, along with whatever limitations on the magic itself that restrict their creation, is a choke point for creating a Narrator force in the world. The stories literally develop a life of their own, but until called forth they cannot influence the world directly.
The core tenet is that every story can have its own spirit, and we invoke those spirits at our risk.
### Premise 1: A Wild Narrator is a Minor Trickster Spirit
TL;DR: They can't have enough power to do much by their nature
The first idea is that a Wild Narrator does not have a lot of power because their stories do not have a lot of lasting power and are not grounded in a single precise moment of reality. They are the nebulous tales of minor events, sometimes exciting, that pepper lives that we remember and repeat endlessly through random chance.
Because these spirits are based on minor events that happen in a myriad of ways, they have been passed down through the ages like the larger tales. However they have not been passed down in a definitive line of succession, nor in any coherent way like a myth or legend would. This gives the Narrator lattitude in fulfilling its narrative and allowing it more freedom in its interpretation, but narrowing its scope to a single event.
Example: The story of a person getting injured when a small part of their ceiling fell on them has happened many times in history. However, it's a minor event -- a story that gets spread for a few days when it happens and then life goes on. Its spirit is not necessarily that strong as it is not about one single momentous event, but due to the many times and ways the story has spread, it can create the event in a myriad of ways.
Note: Not all tricksters are good -- I am almost sure enough people have fallen through ice and drowned that there is a Narrator Spirit for that too should somebody want to curse their enemies in winter.
### Premise 2: Wild Narrators are Distilled Tropes and Genres
TL;DR: The greater Wild Narrators spririts are rarely invoked due to their nature
In contrast to the minor spirits of events, these Wild Narrators are the greater spirits that hold sway over tropes in general. They are the ones that are potentially invoked when a Storyteller spins a tale without it being a specific one.
In a sense, they have ascended beyond being the Spirit of the Story because they have been told and retold -- stories passed down through time until many mesh together into a sort of ur-tale. The Hero's Journey, being one of the archetypical ones, would fall under this category. Character Archetypes fall under here too -- religious mythologies tend to spawn them given the many changes and variations in myth and legend.
They hold an immense power within their sphere, but are incredibly hard to rouse because of it. It would require a story either so mind-numbingly generic that only the Overtrope could hold it effectively, or one would need to be able to invoke the ur-examples of the trope. Only the First Stories can reliable call the Wild Narrators of the Tropes and those are either incredibly secret or lost to the ages.
They are wild and capricious because these Spirits are so wide reaching and we can't control them by their nature. The tropes that they embody are much more vast than a single event and once set into motion, the Storyteller can influence the Story but not control it. However, a story usually resonaltes more with a spirit that is more specific to the story and these greate spirits rarely awaken
### Premise 3: Getting Meta
TL;DR: Your Story is different, netting a different Narrator Spirit
By their nature, invoking a Narrator is exploiting the Fourth Wall -- this person is forcing a narrative onto something and they are holding the script that the spirit needs to follow. When invoked as a story proper, there is only a small level of risk. Namely that the spirit gets bored and/or creative when imprinting its tale on reality. But intentionally invoking a Narrator is also a Story and invoking this kind of metatale Does Not End Well.
For a start, the Story changes. It is no longer the tale of a town suffering from a drought that prayed for rain and got it. It is the tale of a person that wants to call the spirit of the rain maker stories and ask for them to being rains through the power of their Story. That is an entirely different Story, and they ways it can go wrong are immense. Not the least is that the Storyteller does not have the power here -- the Narrator does.
The biggest risk is a Narrator Spirit developing from those stories of people that invoke Narrators directly and knowingly. This spirit would have a similiar Fourth Wall Awareness as per the protagonist of the tale, only their awareness equate to the awareness of our world, and have the sentience to know that if people don't tell these stories they will fade into obscurity. Maybe it already has and the biggest lesson is Do Not Invoke -- Yes, the capital letters are mandatory.
Comparison: It would be like Deadpool being able to directly influence media people to produce more Deadpool stories so that Deadpool can always be on the shelf in some form. This world's version is probably saner than him, though no less aware of their own situation.
[Answer]
**Introduce a concept similar to mana or to chanting.**
Your magic concept is a really interesting one, and sounds almost poetic and a nice thing to exist...until some jerk tells a terrifying story about a man-eating monster to most of the village's children.
To avoid both these misuses as well as strong narrators, we need to make the act of telling stories something special, even if the story must be passed on to become real.
Solution 1-"mana".
Telling a story isn't just a matter of breath and spit, there's something else, an energy from within that's invoked and used when one's telling a tale. The better and greater the story, the more it takes from the teller. Of course, tales that are shared by many won't require so much, as the "cost" of the story is shared by the many who tell it, but for one to make a story happen alone, he must pay the price fully, that way telling a good story is literally an exhausting activity.
Solution 2-there are stories and there are Stories.
Anyone can tell a story, be it a simple tale of something that happened or a myth about a hero who slayed a dragon. But Stories? Those are different. While the great narrators do understand our language, they won't listen to any story unless they're bored to the point of insanity. It takes a special way, of saying, a way of almost chanting the Story, which captivates the narrators and allow it to be remembered through the ages. The stories are told but the Stories must be sung and fit a certain format. Singing a Story according to a special metric not only makes it easier to remember (in Palestine as well as in the medieval times, many stories were sung in order to make memorization easier and ensure they lasted longer without alterations), thus ensuring it won't be distorted by the next teller. It helps differentiate them from something you normally wouldn't want the narrators to pay attention to (let's hope none was bored when you decided to tell your tale).
But there's another important difference: anyone can tell himself a story, but no one can't just sing himself a Story. The narrators may get bored, but they won't take anything unless they're in absolute desperation for some stimuli. If you can't even find a mortal who might want to hear your Story, you really think they will want to hear it? A Story is more than a well sung tale, it takes another, a listener, to hear the Story and spread it through the winds, tho whoever shall listen. A good Story has many listeners, but a Story told to oneself or forced onto another shall be ignored and forgotten, and so shall be its teller.
[Answer]
**Make them pay**
Yes you may case a hurricane with "The Wizzard of OZ", but your soul would be consumed to create this "Narrator". And you would need to complete an untrivial quest to get it back.
Or you may slowly and gradualy become a tale of yourself with each new story. At the end you cease to exist and only story of you is spoken around. For a while.
UPD: to nerf the power of magic you can also make listeners an retellers to pay. For one single rain one single soul is enough. But for city destruction you need thousands of eager listneres (cult?) who whould sucrifice their souls (or existance) to make it happen.
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I understand that some non human animals build structures that they innately know how to build, such as how birds innately know how to build nests, and spiders innately know how to make webs, and beavers innately know how to build lodges.
Could a land animal evolve to innately know how to build a boat? If so could a land animal evolve to innately know how to make and use a sail, or a paddle to help with steering the boat?
[Answer]
There are quite a few birds which build floating nests. Those nests are more in the nature of rafts than boats, but maybe that's enough.
* [Australasian grebes](https://en.wikipedia.org/wiki/Australasian_grebe), *Tachybaptus novaehollandiae*.
[](https://en.wikipedia.org/wiki/File:Australasian_Grebe_nest_building.jpg)
(source: [wikimedia.org](https://upload.wikimedia.org/wikipedia/en/thumb/4/48/Australasian_Grebe_nest_building.jpg/640px-Australasian_Grebe_nest_building.jpg))
*A pair of Australasian grebes building a floating nest. Photograph by user [Grahame](https://en.wikipedia.org/wiki/User:Grahame), available on Wikimedia under the Creative Commons Attribution-ShareAlike 3.0 license.*
[](https://commons.wikimedia.org/wiki/File:Grebecoveringeggs4502.jpg)
*Australasian grebe adult over its egss on a floating nest. Photograph by Keith Lightbody, available on Wikimedia under the GNU Free Documentation License, Version 1.2 or later.*
* The [common tern](https://en.wikipedia.org/wiki/Common_tern) *Sterna hirundo*.
[](https://commons.wikimedia.org/wiki/File:Batalla_de_golondrinas_de_mar_(Sterna_hirundo).jpg)
*Argument between a group of common terns. Photograph by Xavier Grané Feliu, available on Wikimedia under the Creative Commons Attribution-Share Alike 3.0 Spain license.*
* [Allen's gallinule](https://en.wikipedia.org/wiki/Allen%27s_gallinule), *Porphyrio alleni*, formerly known as the lesser gallinule.
* [Least grebe](https://en.wikipedia.org/wiki/Least_grebe), *Tachybaptus dominicus*.
* [African jacana](https://en.wikipedia.org/wiki/African_jacana), *Actophilornis africanus*.
* [Ferruginous duck](https://en.wikipedia.org/wiki/Ferruginous_duck), *Aythya nyroca*.
* And quite a few others, such as the [American coot](https://en.wikipedia.org/wiki/American_coot), etc.
In addition, Wikipedia says that the [New Guinea crocodile](https://en.wikipedia.org/wiki/New_Guinea_crocodile), *Crocodylus novaeguineae*, makes floating nests to lay its eggs.
In a second addition, floating nests made of foam are not uncommon among fishes and amphibians.
[Answer]
**Yes. Fire ants make rafts.**
[](https://i.stack.imgur.com/b7SrK.jpg)
<http://theconversation.com/how-do-fire-ants-form-giant-rafts-to-survive-floods-80717>
Fire ants instinctively build a raft of their own bodies to survive flood. They also instinctively make towers. The linked articles describes researchers who derived rules of behavior describing how ants, which know nothing, can instinctively behave in response to a stimulus so that these impressive emergent mass behaviors can occur. Such behaviors evolve because the emergent mass behavior is adaptive for the colony as a whole - the social insect innovation that has allowed ants to conquer the world.
>
> Perhaps the most remarkable implication of this research is that the
> ants don’t have to “know” whether they are all behaving the same way.
> Apparently they follow the same simple rules of movement: If ants are
> moving above you, remain in place. If not, move randomly, and stop
> only if you reach an unoccupied space adjacent to at least one
> stationary ant.
>
>
> Once the tower is built, the ants circulate through it while
> preserving its shape. We were surprised; we thought the ants would
> stop building their tower once its height was maximal. Previously,
> when we studied the ant raft, we were surprised in the opposite way.
> We thought the ants would circulate through the raft so as to take
> turns being underwater on the bottom. Instead, ants on the bottom can
> stay in place for weeks.
>
>
>
I do not know if the ants can pilot their rafts, but it would not surprise me. It would be the same sort of emergent behavior.
For example:
IF ant is on top of raft AND ant sees dry land, THEN ant moves towards edge of the raft nearest to dry land. The result is the whole raft generally moving towards the sighted land.
[Answer]
# NO
I'd argue that beavers, e.g., do not innately how *"how to build a lodge"*. Rather, they innately know how to cut down trees, move them and shape them into dams, lodges, etc. I do not believe they are sentient creatures ([in the usual sense of def. 2](https://en.wiktionary.org/wiki/sentient)) and thus have no concept of structures and no means of communicating plans, designs, skills or novel adjustments to technique. In other words, they don't know what they're doing; they just know to do what they're doing.
I'd argue that a land animal *could* evolve to craft a crude boat-like-object. Something like dugout canoe could easily be made by a creature not at all unlike our happy dam building beavers. It's just a matter of applying their teeth to the job.
In order for your critters to make and use a *sailboat*, they'd have to innately know how to make not only a boat-like-object, but also how to make sails. This would involve innately knowing how to weave sailcloth, how to trim and stitch pieces of cloth together. It would involve innately knowing how to obtain fibres and twist rope. It would involve innately knowing how to make a mast, a boom, a keel, a rudder and various doohickies for making fast said sail. This would involve innately knowing how to make dozens of complex pieces, joining them up and using them to advantageous sailing. It would involve innately knowing at least three basic lower-level technologies that are agriculture based (jute, hemp & flax growing) plus basic higher level technologies like weaving that require other technologies (preparation of fibres, spinning threads, making looms, making sewing needles).
Most importantly of all, most of these things would require them to innately know how to make and use a language through which they can communicate all these high level technologies and coordinated actions.
[Answer]
In addition to what @elemtilas has said, the development of animal skills such as nest building through evolution has to serve a purpose in the species' survival that cannot be reached more easily otherwise. For example, the nest in a tree keeps the eggs warm and safe in a way that no other behavior can in a similarly efficient manner.
So what evolutionary purpose might building a sailing boat accomplish?
It could get the animal to a place with more food or to a safe habitation accross the water.
But is developing the skill to build a sailing boat the easiest way to get accross the water to more food or a safe nest?
Certainly not. Animals that needed to cross the water evolutionarily have developed the skill to either swim or fly. In fact, [almost all mammals already know how to swim](http://www.bbc.com/earth/story/20170320-the-cruel-experiments-that-revealed-most-mammals-can-swim) (apes being the only exception). Apparently developing these abilities was easier or quicker for nature to accomplish, or we would have sailboat building non-sapient animals on Earth.
[Answer]
Starting with the conceit that you meant sapient instead of sentient - here's my idea.
First, it depends on the physical properties of your world. This will probably only work on a planet of many small islands, separated by a greater distance than can be easily flown by most birds/flying reptiles/squirrels what-have-you.
This all starts with a small herbivore who builds nests out of small branches/logs and mud or self expressed resin. Could be beavers or bugs, doesn't particularly matter. But because of the makeup of the world - there aren't many large lakes for them to make their nests in, so they evolve to anchor their nests to rocks exposed by low tides, slightly off the coast of the islands. Maybe they build conically up from the rocks, maybe they use a biological mechanism to secure the nests so they are anchored, maybe they just build them up big enough that they stick up out of the water.
Regardless, these nests happen. I personally like to envision them as conical beaver lodges, because I like beavers.
So, these nests are built up around the islands that the creatures are native to. There are birds that can fly between islands, spreading flora and whatnot in their droppings. But not all the birds can do so. So the birds only capable of shorter flights begin to colonize the larger nests, building their nests on top of the beaver nests. This keeps them safe from carnivores, and is a benevolent sort of parasitism. Well, these birds are seed eaters. They feed from various plants and in the fullness of time, a particularly broad leafed tree gets it's seeds mixed in. The birds deposit some of those seeds while nest building on one of the island nests, and what do you know, the tree takes root. As it grows, the prevailing winds break it's bonds to the rocks - sending nest and tree off into the unknown.
The colony of beavers is stuck, the birds are stuck, and the tree is pretty obviously stuck. So the winds take this makeshift boat over time onto virgin shores, where the beavers are wildly successful, the birds are wildly successful, and the trees... well they do okay too. Eventually through self selection we develop a subrace of beavers who build weaker bonds, then eventually no bonds, because these birds are now widespread enough that their floating nests will be colonized and en-sailed. This allows new colonies to constantly form and drift around until they hit land, feast, and rebuild.
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You've been transported into a world with a medieval tech level. This world has coal deposits, but no petroleum deposits. You have no chemistry equipment with you, but you can use glassblowing or blacksmithing to make any vessels you need. You have also memorized a few college-level chemistry textbooks before you came here.
With magic, you are able to:
* telekinetically move or float anything light enough to hold in your hand
* create high-voltage electrical arcs
* heat or cool anything. Takes a long time, but with sufficient insulation you can theoretically indefinitely heat or cool any material you want, so liquid hydrogen and molten tungsten are not out of the question.
Ignoring cost and time, what kinds of chemicals would you be able to make? Specifically, would you be able to synthesize:
* Plastic (any sort of it, including bakelite or polylactic acid)
* Explosives: TNT, guncotton, nitroglycerin, smokeless powder
* Medicines
* Rocket fuel of any sort (other than liquid oxygen and hydrogen)
I have ideas for ways to make some chemicals:
* Gathering hydrogen peroxide from special bacteria
* Making ethanol from plants like grains or sugars
* Creating nitric acid from electric arcs
EDIT: Maybe I should have clarified that automating many tasks, including magic-based tasks, are not particularly difficult, and the organic matter that *should* have been made into petroleum was turned into non-hydrocarbon, non-combustible magical fuel instead. With enough magical fuel, you can use the forbidden arts to build an magical toaster or electric arc machine or air compressor, the workers at the chemical factories could be necromantic zombies, etc.
In other words, *carrying out* the industrial processes wouldn't be so much of an issue as the *number of processes to remember*, or the ability to gather the necessary materials.
[Answer]
*Technically* the answer is yes. If you have coal, you can make [coal tar](https://en.wikipedia.org/wiki/Coal_tar) and [coal gas](https://en.wikipedia.org/wiki/Coal_gas). They aren't as good as actual oil, but they're still a splendid source of hydrocarbons for industrial and medicinal use. I'm sure with sufficient chemical cunning, a big fossil hydrocarbon-based chemical industry could arise.
With your modern knowledge you could probably kickstart an industrial, chemical and pharmaceutical revolution... but there's a good chance that you won't live long enough to see it pan out. Building an industry from nothing will be very hard, especially when there's no mass production, electricity or even much education around!
Note that none of the suggestions (with the exception of liquid oxygen) I've made below require or make use of your magic. If something is easy enough to be achievable, you can probably get the raw materials even back in medieval times. All the telekinetically lifted molten tungsten in the world won't make you any anthraquinones.
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>
> Ignoring cost and time, what kinds of chemicals would you be able to make?
>
>
>
Obvious things you've missed out in your list include fuels such as [biodiesel](https://en.wikipedia.org/wiki/Biodiesel) (skip the steam age! you are adding steam engines to your list of inventions too, right?) and useful chemicals such as chlorine-based [bleach](https://en.wikipedia.org/wiki/Bleach) or nitrate- and phosphate-based fertilisers all of which should be in your capabilities to produce.
More importantly, why not introduce electricity and electric motors? Not chemistry or magic, but incredibly useful nonetheless. Not to mention hot air balloons and gliders...
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> Plastic (any sort of it, including bakelite or polylactic acid)
>
>
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For bakelite you'll be needing formaldehyde and phenol. These *might* be within your ability to make. The former can be made from methanol (also called wood alcohol, cos you can make it from wood) and the latter from coal or coal tar.
I suspect that most other plastics will fall into the category of "*Things that will be made as a result of the revolution you started*" rather than "*Things you'll make whilst still alive*". The raw materials for PLA are potentially available to you, and it is possible to make other polymer feedstocks from coal-derived chemicals(see [methanol to olefins](https://www.honeywell.com/newsroom/news/2016/07/china-turns-coal-into-plastic-with-honeywell-technology) for a modern example) but the synthesis is likely to be far too hard for your medieval wizard. Making the catalysts needed for polymerisation is probably all but impractical. Maybe some future wizard will discover them and name them after you.
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> Explosives: TNT, guncotton, nitroglycerin, smokeless powder
>
>
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Obvious answer: gunpowder. It might already be popular, depending on your time period. Given potassium nitrate (the oxidiser in gunpowder) you can make nitric acid. Potassium nitrate, also known as saltpetre, is a naturally occuring mineral and you can make it from manure or even urine. Sulphuric acid can be made from sulphur (also a naturally occurring mineral, and an ingredient for gunpowder) with a little effort, and with those two acids you can make all sorts of fun things, including guncotton and nitroglycerine.
TNT is Quite Hard to make, even these days. Composition C might well be possible though... you'll need some sulphuric and nitric acids and hexamine, and to make that you'll need formaldehyde, so there's nothing there that's obviously insurmountable.
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> Medicines
>
>
>
Oh, all sorts. This might be the easiest place to start building your empire. Introducing anaesthetics might be as simple as making some ether or chloroform. You'll need some ethanol and some sulphuric acid for the former, which should be straightforward to procure. Extracting exciting alkaloids from plants (eg. morphine) isn't rocket science!
The big improvements in medicine would be things like germ theory, hygiene and antibiotics, and these aren't necessarily in the domain of the chemist (but you could introduce them anyway, I'm sure).
>
> Rocket fuel of any sort (other than liquid oxygen and hydrogen)
>
>
>
Gunpowder again? Hydrogen peroxide is also possible, though neither will get you in to space. You'll mostly be wanting better metallurgy, I suspect, to make good use of your new propellants. Liquid hydrogen would probably be too hard to work with, but LOX would work with all sorts of other fuels that you could probably get your hands on. [Alcohol/LOX](http://www.astronautix.com/l/loxalcohol.html), anyone?
[Answer]
**The short answer is "no"**
Access to the equivalent of a stove, a 'fridge, and a lightening bolt doesn't give you the ability to access any chemicals not already accessible during that time period. Specifically:
* Gunpowder pre-existed Medieval Europe.
The rest of it requires everywhere from small to *massive* processing. My college-level Organic Chemistry text (which I still have) doesn't tell me how to manufacture rocket fuel or pharmaceuticals of any kind. It also doesn't explain how to manufacture microscopes, flasks, clean rooms, safety equipment, or any such else.
1. Your traveler would need to memorize and/or have access to the better part of 50-100 textbooks on chemistry, physics, manufacturing, electricity, and more.
2. Your traveler would need time to create power distribution systems, and hundreds of electrical or mechanical instruments.
3. Your traveler would need time to create manufacturing facilities (most chemistry requires *processes,* not just the combination of a couple of chemicals).
4. Your traveler would need to hire hundreds of people and train them in everything from construction to factory work to advanced processing, raising their knowledge so far above that of their peers you'd risk starting civil wars.
5. Pharmaceuticals are *absolutely out of the question* with the exception of some basics (aspirin comes to mind) that can already be derived in part or in full via the pharmacology of the time.
We are occasionally asked, "how can I get advanced tech X in the medieval age?" questions. Pretty much all of them suffer from the same problem. Quoting from [an answer of mine in Meta](https://worldbuilding.meta.stackexchange.com/a/5764/40609):
>
> Technology is a massive mountain. Today, right now, we're standing on the top of that mountain. What's below us is a nearly unfathomable amount of knowledge and experience. Choosing *[insert conditions of your question here]* is like picking up three rocks on the mountain (presumably one at the bottom, one in the middle, one at the top) — and then expecting those three rocks to lift you high enough that you can rebuild the mountain in less time than it took to build it in the first place.
>
>
>
It would take a lifetime to scratch the surface of what you're trying to do. You need to declare it to be so and move on with your story. There isn't a believable path that represents a reality-based or science-based answer.
[Answer]
[Pyrolysis](https://en.wikipedia.org/wiki/Pyrolysis) of wood can be the basis of your chemical industry.
In pyrolysis process, wood (or virtually any other organic matter) is heated in the absence of air. If properly done, it results in charcoal and [pyrolysis\_oil](https://en.wikipedia.org/wiki/Pyrolysis_oil) vapors. Those vapors need to be captured and separated into individual substances. Pyrolisis oil is still quite different from oil's [naphtha](https://en.wikipedia.org/wiki/Naphtha), but the pathway to most organic components that you want is much shorter now.
Another way that you already mentioned is fermentation, which results in ethanol and or other alcohols.
Electric arc that you also mentioned is indeed a good way to produce nitric acid, which should give you a pathway to other strong acids, which, in turn, can be used for dehydration and substitution, eventually giving you hydrocarbons and plastics.
P.S. All those things above would be doable in small quantities in an "alchemist's lab" environment. Building a whole industry producing all the substances (XIX or XX tech level) is a much bigger task.
[Answer]
Certainly you can do much practical chemistry without petroleum. The modern organic chemical industry was founded on chemicals produced from coal tar, starting with Perkin's discovery of mauveine <http://www.victorianweb.org/science/perkin.html> Many other chemicals were produced from it, including phamecuticals (<https://en.wikipedia.org/wiki/History_of_aspirin#18th_and_19th_centuries> ), explosives (picric acid), and precursor chemicals such as phenol.
[Answer]
If you can heat/cool things and create electric arcs and have modern chemistry knowledge you can jumpstart large scale manufacturing of modern explosives, that are way better then medieval black powder. You won't be able to build artillery tubes because the metalworking isn't advanced enough but you can manufacture hand granades, like the german potato masher, and high explosives for the sappers. Your king will be most pleased and will set up a royal arsenal to manufacture a lot of these granades and charges. So, there will be demand and, with demand, you can create a manufacturing complex (aka industry).
If you can create electric arcs/know high school chemistry you can create batteries. With enough batteries and some way to recharge them (maybe a mill on a river generating current), you can create aluminium metal. Aluminium would be a godsend to the medieval people. A metal that is very light and strong enough to be useful, that withstand corrosion in normal conditions, has many uses. And if you have uses, you have demand and if you have demand you have an industrial complex.
But i would advise against appearing in medieval europe - too few people, too poor. Appear in India or in Syria or even better, in Tang/Sung China.
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So, a council of wizards decided that all should bow to their rule. That, it turns out, is a thing wizard councils did a lot. This lead into a certain degree of disagreement, which in turn resulted in the exchange of increasingly large fireballs and generally propelling matter into the stratosphere.
So, now most of the larger objects in the stratosphere have fallen down, leaving only sooty smoke and dust darkening the skies, resulting in a nuclear winter. And, given the aforementioned fireballs, a lot of the wizards are gone, and anyone pursuing the craft tends to end up under considerable time-pressure to learn how to stand on thin air.
So, my question is: How, if at all, can a medieval fantasy population, with a bare minimum of magic, weather the nuclear winter?
[Answer]
# Survive? Sure!
There were farmers in Sicily just as there were farmers in Norway. The difference in temperature is easily more than the effects of a nuclear winter.
Some problems with that glib answer:
* Farmers in Norway and in Sicily have animals and crops adapted to their respective climate. They know what to expect and how to cope. That's not the case in a surprise *magical winter*. There may well be near 100% losses of the planted crops and herds.
* Buildings will not be adapted to the temperature. Will orchards be cut down to heat thin-walled huts? Will roofs collapse under the loads of snow?
* If half the necessary food is missing, it won't be that half the people will simply lie down and starve. There will be a collapse of law and order.
Still, exterminating an entire population is *extremely* difficult. The question is how many will survive, and who. One percent? Ten percent?
* Who has stockpiles of food, and can they defend them? Will people die before they can consume their hidden stockpiles, and will subsequent scavengers find them?
* Are the barons ruthless enough to let their serfs starve and to feed their knights? Are they ruthless enough to let *some* of their knights starve to feed *some* of their serfs?
* Will groups like hunters and fishermen continue to feed their communities as long as possible, or will they hide out in the forest with their meager catch?
I can think of a couple of spells that a low-end "hedge wizard" or "wise woman" might know.
*Lure fish into creel.*
*Detect wild fruit and vegetables.* (Might also work on hidden root cellars.)
*Preserve meat.* (If fodder runs out and animals must be slaughtered.)
*Ignite fire with wet wood and no tinder.* (After the rains.)
[Answer]
For a medieval world an harsher climate would easily mean famine: look at the impact of the year without summer following the Krakatoa eruption on some communities, though they were well off of middle age.
A nuclear winter would mean sure death for a large part of the population. The only way for magic to help would be to increase food production before the blow, and to preserve the food during the nuclear winter.
[Answer]
Did you know that temperatures dipped in Medieval times in something close to Nuclear Winter? It was called the Little Ice Age. NW takes temps down by 1.8 degrees F. The LIA took it down by 1.5 degrees Fahrenheit. Unless you are looking to add NW ON TOP of that--gotta say, historically, you ALREADY HAVE the effects, or at least pretty close.
So Famine. And yet the population still grew as people adjusted. There's a .3 difference. That's a lot.
NW, or at least the 1.8 takes 100 Hiroshimas. That's just...a lot. And difficult to achieve for a population so low. It means that there have to be whole areas that are just burned to ash.
Considering the population of Medieval times, this means a LOT of wizards. In fact, to achieve 100 Hiroshimas, I wonder that there would be all that many people to oppress considering all the wizards needed to do this. Further, it would NOT happen all at once--Hiroshima was a one time event, as are most nuke drops. What you're talking about (massive fires and ash in the atmosphere) will likely NOT happen all at once. Medieval times were fractured as far as communication and travel is concerned--so it's not like it is now. Concerns are local. The wizards would be warring over time, not all at once. Which means that the drop is going to be more gradual than it would be if you did 100 Hiroshimas.
The amount needed to be burned is on a scale that is far over what Medieval times could achieve. Total destruction of a city is definitely not the way war was waged most of the time. Because you wanted to take territory and resources. War waged as it has been in modern times is very, very different.
The destruction of Hiroshima was about 5 square miles. With a lot of material to burn. The largest city in England, London, was maybe 1.12 square miles. And this was a mega city of the time. That's the main problem with the premise
The answer to how they can weather it--hie thee to yon google and ask about the effects of the Little Ice Age. Folks died, famine happened and so on. That can give you a detailed account.
I will add to this when I have time regarding the Great Famine and effects.
Thing one that happened was a shift in weather patterns--specifically far more rain than was good for crops. Lots of things died.
If the temperature continued to drop, this would worsen (less rain eventually, some more extreme weather).
People would die, but people would also adjust. No matter how much the technology lacked. I posit that wizards might not be blamed for this directly (cause and effect wasn't a strong suit of the Medieval mind) and that magic would be used like technology is to help US survive.
See, even if 100 Hiroshimas happened, though there would be groups that "blamed science" most humans would grasp at ANY advantage to help them survive, even the very science and tech that destroyed them. That's how they survive. A few folks with hedge magic helping their town survive and making things grow...
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[
Thinking about the shape gets pretty weird.
So my species has a more or less horizontal posture, pretty much a small sentient raptor. They can assume an 'upright' position, but only in the sense of a parrot.
They would of course have some kind of personal furniture for sitting elevated above the ground, and need some kind of seating shape for safely operating vehicles. They'd also need to harness themselves for anything faster than a buggy (cars, airplanes, spacecraft).
Human-shaped chairs and seat belts would thus be useless to them; their tail gets in the way, they can't rest their back against them, and they're very unsafe.
What kind of furniture would adequately rest a theropod, and also serve as a good model for safety seats?
Optionally, but ideally, it could also free up their legs to use for operating machinery or using tools.
[Answer]
I am not sure a theropod would have the need to sit.
If you want to go for it anyway, I would go for something where they can rest their lower abdomen/belly upon, similar to the harness of a deltaplane (I have found a beautiful drawing of a raptor resting on a tree which could illustrate this very nicely, but I have not the permission to share the image).
Basically you want to assure a third point of contact to release any balancing effort. Something going in the red area in the picture below should do.
[](https://i.stack.imgur.com/rYxpJ.jpg)
[Answer]
**therapod sitting has actually been studied.**
It actually varies quite a bit depending on what therapod you are talking about, some theropods are nearly horizontal others nearly vertical. Raptors have a rear facing pubuc boot (an enlarged section of the pubis that the body weight can sit on) meaning they actually end up with an upright sitting position. Early theropods are nearly horizontal while a t-rex on the other hand ends up sitting more in between. Birds actually vary wildly depending on the type of bird perching birds in particular do not sit.
For non-avian theropods in the sitting position they actually have 3-4 point contact, the pelvis (pubic boot) and both feet rest at the same level as the boot, with the tail on the ground or not depending on the species (most are a yes). You can look at the first image for the sitting position and the other two for the anatomy supporting that posture.
Because of this position a raptor chair is likely nothing more than a cushion on floor. Think along the lines of traditional Japanese furniture. By raptor I am assuming you means something like velociraptor or deinonychus and not an eagle. Note: however they need a lot of clearance behind them for the tail, in many species it is rigid for most of its length, in others especially the oviraptors it is shorter and more flexible. so unlike a bird they need need a lot of space behind them. For a vehicle there could be a lowered section of floor for feet forward and down from the seat, yielding something more like a motorcycle seat for the pubic boot to sit on.
A safety seat will likely have a flattened bar of metal running up along the stomach to anchor the torso against tilting forward, they can be strapped into that safely. Building true safety seats will be much harder than for humans. protecting the head in particular will be problematic since it is at the end of a long neck, whiplash will be a big problem. I can't think of a way to protect the head that does not prevent them from looking from side to side, the best I can think of is some kind of safety cable attached to the ceiling that prevents over extension. Really it depends on what you mean by safety seat, the seat for a car vs a rocket will be very different.
As a side note the sitting position is likely also the sleeping position, many birds tuck the head into the armpit to sleep and raptors definitely have the neck for it. the position and flexibility of the arms makes resting on the stomach unlikely. I can imagine tool using raptors inventing elevated wooden stands with a pillow on it for resting the head.
[](https://i.stack.imgur.com/AIrKG.gif)
[](https://i.stack.imgur.com/28bwi.jpg)
[](https://i.stack.imgur.com/D9Dp7.jpg)
[Source 1](https://s3.amazonaws.com/academia.edu.documents/42951043/Guaibasaurus_candelariensis_Dinosauria_20160222-3613-8z5vjr.pdf?AWSAccessKeyId=AKIAIWOWYYGZ2Y53UL3A&Expires=1550679367&Signature=IFr9gVQlTBtXWrGbbjOtf%2B6X%2Foc%3D&response-content-disposition=inline%3B%20filename%3DGuaibasaurus_candelariensis_Dinosauria_S.pdf)
[source 2](https://www.nature.com/articles/nature02898)
PS I know thistle's wrists are broken, but that is irrelevant for the discussion.
[Answer]
Big birds sit on their heels, not on their butts. They also have no nads.
So what you need is some sort of platform where they can fit their legs heel to toes, and which is comfortable to get onto and off. A regular human bench would do the trick, specially if you elongate the bench a little.
Some benches used by humans would serve nicely as well. This could site a few of them around a table:
What you don't is a rest for the back. That would be useless at best, and a nuisance at worst.
Also take a look at this other question. It is only tangentially related, but could give you some inspiration:
[Could winged humanoids perch on public transit?](https://worldbuilding.stackexchange.com/q/112002/21222)
[Answer]
**A Bowl** (modified appropriately)
What first came to my mind while reading this question's title was a nest many are bowl shaped). After reading the full details of the question, I realized that a nest doesn't quite fit, so I started thinking "which birds seem to have the most "comfortable" (by human stndards) places to rest their body weight while taking weight off of their legs?" And the answer to that question is Ducks floating in the water.
How is this applicable to the question? By taking the shape of the indentation the Duck makes in the water (basically an elongated bowl), and making it solid, then poke holes for their legs.
This concept can be modified (lengthened, widened, deepened, inclined), as needed, depending on the exact body structure of the actual species, to be almost universally applicable to any animal with this general type of body structure.
Also, just like human sitting options, they can range from very generic to very specific. For example, an actual bowl with no holes at all, and with a main shape only loosely specific to the general body form of the species, would be comparable to something like a human bench or stool, while on the other end of the spectrum a bowl could be specifically contoured, flexible, with holes of variable size and or position, adjustible inclination, etc., could be similar to a high quality office chair.
BONUS 1: it's very simple to run a strap (or 2) from one side of the bowl, over the back of the theropod, to the other side, as a safety harness
BONUS 2: Holes for the legs frees up appendages for manipulating tools, as requseted
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[Question]
[
My idea for a creature within my fantasy story is that of a creature which floats through the air like a living hot air balloon.
It would do this through the intake, storage and regulation of gases within its body alongside its body temperature.
Its appearance is that of a large blob varying in size from a backpack to a small car with a head in front. There would be several long appendages hanging below it to act as limbs, grabbing food to bring up to its head to eat. There are wings but they function more like a parachute to keep it in the air and for balance and directing its body. Its main body would consist of all your standard organs alongside several large sacs for storing gasses and an advanced respiratory system to manage its own breathing and the regulation of its gases.
It is an opportunistic omnivore with its main diet consisting of vegetation and carrion it finds. It doesn't hunt since it's not that hard for anything to get away from it(through running or hiding under cover).
It doesn't need to worry about predators as there is nothing capable of catching it in the air except birds of which there are no varieties capable of taking it down at full size, and even if they hunted the backpack size ones, they taste terrible.
I am undecided on which gas/es it will use to do this, any suggestions are welcome, whatever it is, it will have to be sourced through breathing from a standard earth atmosphere and/or producing it from food sources within its body. The gases will need to be able to produce enough lift for it to float in the air just above treetop level or higher. It can use its own body temperature to increase the lift provided by these gases but that is limited by how high its body temperature can get.
My question is how viable is this creature? could it actually float and survive in an earth-like world?
[Answer]
As others have stated, the best lifting gas for this purpose is Hydrogen gas, as it can be produced biologically and offers the highest amount of buoyancy.
But your life form would be a very fragile thing, the skin sack holding the gas would realistically be millimeter thick at best (see following math) and could be ruptured by most anything.
I disagree with Dubukays assertion that an animal like this would have to be kilometers long though. Let's look at the math with skin 1mm thick and 1g/cm^3 dense
Volume for a spherical air sack that is **1 meter** in diameter: $V = (0.5 \ m)^3 \times\pi \times 4/3 = 0.52 \ m^3 $. Fully filled with Hydrogen gas this can lift **half a kilogram** (rounding for convenience we say that Hydrogen provides **$1 \ kg/m^3 $ lift**). This is where we run into troubles. The weight of the skin is about $(0.5 \ m)^2 \times \pi \times 4 \times 1 \ mm \times 1 \ g/cm^3 = 3.14 \ kg $ ! No dice.
Volume for an air sack that is **5 meters** in diameter. A lift of $(2.5 \ m)^3\times\pi\times4/3\times1 \ kg/m^3 = 65 \ kg$, while the skin masses in at $(2.5 \ m)^2 \times\pi\times 4 \times 1 \ mm \times 1 \ g/cm^3 = 79 \ kg$. We're getting closer and the square cube law is clearly working in our favor.
A **10 meter** diameter air sack will give us over **550kg of lift**, while the skin (still 1 millimeter thick) uses up about **320kg**. This leaves a respectable **220kg** or **480 pounds** of usable mass.
So yes, the animal will be large, but not infeasibly so. There's still a few problems left, but nothing that can't be solved. For one, the animal can't become airborne from birth, because it will need a few hundred kilograms of loose skin for its balloon. Supporting this excess weight is very problematic for a terrestrial animal.
I propose a life cycle split into two parts: The creature is born in lakes, rivers or oceans and grows until it can sustain enough skin for an air sack that will let it fly. It rises to the surface and begins filling the air sacks with hydrogen derived from the surrounding sea water. It is obviously very vulnerable during this period, though this can be alleviated by living in bodies of water without large predators or blowing up in large colonies.
It gently rises from the water once it has accumulated enough hydrogen gas and floats away. It will likely stay above water for its entire life - should its air sack get popped it will gently fall into the water below and heal the damaged skin - but may forage inland above rivers. Mating happens in the air and females drop a large number of eggs above promising bodies of water. Food can be captured with tentacles, as other users have suggested. Hydrogen gas will leak quickly through the thin skin, so it constantly replenishes it.
It's probably unlikely for an animal like this to evolve naturally, but I don't think it's physically impossible.
[Answer]
Sounds very much like the oafan people from [Schlock Mercenary](https://www.schlockmercenary.com/2018-05-27)'s current storyline
They use hydrogen because it can be generated from water by using a simple electrical current which can be generated biologically. Altitude is adjusted compressing the body slightly to decrease volume but not mass and vice versa
Of course it makes them very scared of fire....
Body temp isn't a good method of controlling altitude as it's slow to respond and requires a continuous fuel source to maintain the heat.
If you treat your creatures like a man-o-war jellyfish, they would be the predators and the birds, the prey. They could drift down to above tree height and catch birds or at night birds and bats fly into their tenticles.
Eating carrion isn't very likely. Carrion will be on the ground and unless open plains, wind would be very dangerous to a living balloon.
The biggest risk is storms and strong winds. Your creatures would need to rise above the storms or completely deflate and ride it out on the ground. You don't want to be a hydrogen balloon in a thunder storm.
[Answer]
Your animal can use body cavities filled with hydrogen to provide buoyancy.
Hydrogen can be obtained by catalytic breaking of methane. Methane on the other side is produced in large quantities in the bowels of vegetation eating creatures (ask cows for info) like yours.
By venting/contracting/relaxing the bags the creature can control the buoyancy and therefore the flight level.
Let's assume your creature is the size of a peregrine falcon, weighing 1600 grams.
The buoyancy force can be calculated as $F\_b = g(d\_a - d\_h)$. Placing the correct numbers in the formula you get that with 1.5 cubic meter of hydrogen you can lift 1600 gram.
That would mean a bubble about 5 meters diameter. Not exactly a nice looking animal, but fitting in your description:
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> Its appearance is that of a large blob
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Only caveat: stay away from lighting and electric eels.
[Answer]
**Sadly, no.** Tl;dr: the minimum size of such a creature is on the scale of kilometers and thus pretty infeasible. Instead, try making the creature some kind of colonial organism and boosting your planet.
**Let's assume a spherical creature.**
What we're trying to figure out here is the minimum size of a biological gasbag. We model that as a sphere of $H\_2$ gas surrounded by a thin shell of skin.
*Beware, physics below*
Our initial equation starts out pretty simply:
$V\_{hyd}\*F\_{buoy} = M\_{skin\ shell} = V\_{shell}\*\rho\_{shell}$
where $\rho$ is the density of our shell.
This is then expanded to give us some actual formulas. We're trying to solve for the radius of this biological gasbag, so we're hoping to end up with $r$ alone on one side set equal to a bunch of numbers.
$\frac{4}{3}\pi r^3\*F\_{buoy} = 4\pi r^2t\*\rho\_{shell}$
Where $t$ is the thickness of the shell- I'm going to assume it ends up being 1 meter thick. Sounds approximately right to me. We can simplify a bit with that information and some quick algebra:
$r^3 \* F\_{buoy} = 3r^2\*\rho\_{shell}$
Which immediately simplifies to exactly what we were hoping for!
$r \* F\_{buoy} = 3\*\rho\_{shell}$
Let's deal with those other two variables. The $F\_{buoy}$ is the force of buoyancy due to our lifting gas, in this case hydrogen. There's a lot to it, but Wikipedia has [a shortcut](https://en.wikipedia.org/wiki/Lifting_gas#Hydrogen_versus_helium): $1\ m^3$ of hydrogen can lift $\approx 1.1kg$. Cool! We can also deal with the other variable, $\rho\_{shell}$. Here, a quick google search tells us that the density of skin is about $800\frac{kg}{m^3}$ (ew). Let's plug those numbers in.
$r\*1.1 = 800\*3 = 2400$
*Note: I fudge my units for simplicity's sake here. The $F\_{buoy}$ term is a good bit more complex.*
So our minimal radius for our idealized gasbag is $\approx 2200m$, or 2 kilometers.
We can also reality-check our skin thickness estimate of ~1m. We’re about 2 meters tall and our skin is about 2mm thick, so I’m pretty happy with it. (Actually, there were a lot of bad guesses before I zoned in on 1m but you don’t need to know about all those)
[](https://i.stack.imgur.com/NsoVQ.jpg)
## Biological assessment:
Totally infeasible. A creature 4 kilometers long is nowhere near plausible, and that's the absolute minimum. You'd have to add things beside skin, and that all adds weight, and every time you add something you increase the radius that much further. With some back of the envelope calculations, I get a minimum size of 8 kilometers; including water and muscle mass as well as a tubular body. What really sunk this, however, was the circulation system. Even though the volume scales as the cube of the radius, the amount of liquid needed to provide circulation throughout the body scales even faster. Sad.
### Possible solution: modify the environment
I fudged the buoyancy term in my derivation above, but it's based on essentially two things- the force of gravity and the density of the atmosphere. Here in Worldbuilding, we're free to modify both of those! What we want is a small planet (low gravity) and a dense atmosphere. If we have a atmosphere like Venus, which is some 60 times denser than Earth's, and a planet about the size of Titan, which has a gravity about 1/8th of ours, we can get a much larger buoyancy force. On this planet, every cubic meter of hydrogen is going to be able to lift around 250 kg- a massive increase from the 1.1 we used on Earth. This cuts our minimum radius down to just **10 meters**! That's much more reasonable for an organism, and quite manageable in any fiction novel.
[Answer]
The problem with hot air balloons is they require a lot of energy to become buoyant, and this would require an improbable metabolism. A typical hot air balloon uses a powerful set of [propane burners](https://infogalactic.com/info/Hot_air_balloon#Burner) or equivalents, meaning a creature would have to produce a similar amount of heat (and likely using far lower energy density fuels, unless you want to postulate something really crazy like it eats coal...)
The alternative is even more bizarre. [Buckminister Fuller](https://infogalactic.com/info/Buckminster_Fuller) speculated that geodesic domes, expanded to extreme sizes, could eventually take off like hot air balloons since the entrained air inside would outmass the structure by an enormous amount. The mass of the structure grows with the square of the volume, while the mass of the air inside grows with the cube.
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> The following extract from a paper posted to GEODESIC by Robert T. Bowers explains the idea.] ``When considering a geodesic sphere, the weight of the sphere is a function of the surface of the sphere. The amount the sphere is lifted by warm air is a function of the volume of the sphere. In mathematical terms, weight is a function of the radius squared, while volume is a function of the radius cubed. This is very significant. Even as the radius of a sphere increases, thus increasing the sphere's weight, the lift of the sphere increases more. If you image a sphere that could grow larger, as the sphere gained a little weight, it would gain much lift.
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> ``Buckminster Fuller proposed that as spheres of great size are considered, the amount of air enclosed grows huge compared to the weight of the sphere. Of a sphere with a radius of 1320 feet, the weight of the enclosed air is 1000 times greater than the weight of the sphere's structure. If that volume of air was heated only one degree, the sphere would begin to float!
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<http://www.geniusstuff.com/blog/flying-cities-buckminster-fuller/>
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> I know it sounds like science-fiction, but here’s how Bucky proposed a Cloud Nine would work. A half mile (0.8 kilometer) diameter geodesic sphere would weigh only one-thousandth of the weight of the air inside of it. If the internal air were heated by either solar energy or even just the average human activity inside, it would only take a 1 degree shift in Fahrenheit over the external temperature to make the sphere float. Since the internal air would get denser when it cooled, Bucky imagined using polyethylene curtains to slow the rate that air entered the sphere.
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So a creature which was essentially a hollow sphere over a kilometre in diameter could theoretically become a hot air ballon with a combination of solar heat and metabolic process, but imagining what sort of life cycle that would be required to *reach* a kilometre diameter size before taking to the skies is a bit mind bending.
[Answer]
This sounds similar to the [Affront](https://theculture.fandom.com/wiki/Affront) in Ian Banks' *Excession*. They are described as being:
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> A bulbous mass about two metres in diameter, which hangs from a frilled gas sac one to five metres in diameter. Six to eleven tentacles of varying length and thickness grow from the central mass, of which at least four end in leaf shaped paddles.
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However they cannot survive in an Earth-like atmosphere.
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> Affronters require a high pressure, low temperature environment, and breathe an atmosphere composed mostly of nitrogen and methane, plus other trace hydrocarbons.
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These creatures either 'walk' on their lower limbs most of the time, but with most of their mass supported by their own bouyancy, or they lazily paddle through the air at a low altitude. When they are in a hurry they have a gas vent (anus) on the bottom of their bodies for propulsion.
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[Question]
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In a fictional world a young civilization is struggling for survival.
Round about a century ago, it broke up with the core-society that was just beginning to establish itself on an inhospitable planet. The hiving off was accompanied by a war, involving heavy losses. Meanwhile the war is over, but there are still occasional raids going on. In fact there are more than these two groups loitering around, but let´s keep things simple.
Our young civilization is surrounded by a voluptuous vegetation and dangerous animals living in it. As a result of the fight for survival and due to the penchant of some of the early leaders, people began to calculate their own possibility of survival called “ProProg” (Prognosis of Progression). Absolutely everything is tagged with a number that ranks its contribution to the ubiquitous ProProg. For e.g. a method to control the birth-rate gets a high positive ranking. The birth-rate itself , depending on the actual situation, is ranked too. Production of goods is ranked. Technical innovations are ranked. The quality of ore recently has become worse, so it has been down ranked. But at the same time, a gas pipeline-worker made a proposal how to only defecate every three days without getting digestive problems and thus saving precious time. So there’s an up valuation of the ProProg here. The way people (and even children) contribute to the ProProg in their spare time is ranked. And the ranking can be negative too, so people get aware of favourable and unfavourable behaviour every minute of the day. How many and how severe raids have there been ultimately? Being it wild beasts or the other “tribe”. How probable is the eruption of a near volcano?
All these tiny to big rankings are pooled in one big number, the actual ProProg. A ProProg of 100 would mean: survival granted for the next 500 years, no threats at all. Birth-rate is going up, production growth stable and political stability granted. Right now the ProProg is around 38, meaning that there is a good chance to survive the next 190 years, but a lot of problems still are unsolved.
Besides the psychological effect, in a positive as well as in a negative way, does this make any sense? Which sectors in such a civilization are essential to be ranked? **Is it somehow feasible to gather this huge amount of data and make one sustainable number out of it? Can there be one formula to rule them all?** Would it really help a young civilization to blossom?
A lot of questions, but I think they all stay in the frame of the main topic.
Some more specific indications (Meant to help frame the answer and not to be taken too literally. Also referring to the above mentioned examples):
* The society has a stage of development comparable to middle Europe +/- 1880.
* It´s political and social framework is mostly technocratic.
* No electricity. Main energy source is natural gas in diverse refined conditions. Gas sources are everywhere. Here our society is far beyond the technical status of earth´s 1880.
* The whole administration and calculation is based on paperwork.
* All devices used to help calculating should be similar to the ones used on earth until 1880, unless the availability of different types of gas allows other.
* Steel is produced.
* Lots of construction wood in the surroundings.
* Just one other humanoid group.
* Formerly a few 100, nowadays round about 100.000 inhabitants.
* A very solid and gigantic “town hall”, allowing shelter to most citizens and main production facilities.
[Answer]
TLDR; *"It’s difficult to make predictions, especially about the future"*. ([Attributed to many famous people](https://quoteinvestigator.com/2013/10/20/no-predict/); the Quote Investigator attributes it to [Karl Kristian Steincke](https://en.wikipedia.org/wiki/Karl_Kristian_Steincke))
## Garbage In, Garbage Out
So we have this cilization which aims to *"establish itself on an inhospitable planet"* and has a *"stage of development comparable to middle Europe [around] 1880"*. I won't be snarky and point out that the stage of development of, for example, (little) Romania (oh my country!) around 1880 and the stage of development of, for example, the United Kingdom around 1880 were profoundly different. (To illustrate, Romania experienced massive peasant uprisings in 1888 and 1907; in 1880 Romania had about 1400 km of railroads while Britain had about 29000 km.) So let's assume the best of the best, and consider that this society has a stage of development similar to Britain around 1880.
* The first strange thing is how could a society similar to Britain in 1880 get to aim to establish itself on another world. This does not compute. To be in a position to aim to establish themselves on another world they must have started from a very advanced society, several centuries more advanced than ours. How did they forget how to make electric generators, electric motors, light bulbs, electronic valves (they can be made at home), how did they forget radio and television? This is crucial; societies cannot forget *selectively*. Either they went through a long phase of complete illiteracy, in which case, sorry, but a hundred thousand people society *will not* reach a level of development similar to 1880 Britain (maybe, just maybe, they could reach a level of development similar to 5th century BCE Athens), or this is simply inconceivable.
* The second strange thing is how did this society similar to 1880 Britain get this obsession with planning? Are they by any chance Marxist-Leninists enthralled by five year plans and the dream of building a perfect society? (Note that not even the Soviet Union tried to aim for global optimization of progress; they simply established that some things were "good", such as producing many tons of steel per head, introducing many hectares into cultivation, opening many miles of railroads and canals, etc. and went for it.)
But anyway, let's take the premise as given. We have a society similar to Britain in 1880 which is curiously fascinated by a numbers, specifically by computing a prognosis of progression, which, by the way, is specified only as a "prossibility of survival". *"Right now the ProProg is around 38, meaning that there is a good chance to survive the next 190 years, but a lot of problems still are unsolved"*. All right, but *what are the threats*?
That is to say, why *wouldn't* their society survive five hundred years? Will the bears eat them? Is the climate changing? Are the gas reserves running out? The question does not specify.
So we have "everybody" providing a daily ranking of their contribution to the probabilty of survival of the society. Now, here come the first problems:
* Both Lenin and [Kerensky](https://en.wikipedia.org/wiki/Alexander_Kerensky) will estimate their contributions to 100. One of them is wrong, but which one? How can the Central Institute of Totally Democratic and Objective and Definitely Not Totalitarian Statistics decide whether Lenin is right or Kerensky is right without having to fight a civil war to find out?
* How do they solve the problem of the *shortage of clairvoyants*? The invention of the internal combustion engine was considered a great achievment in the late 1800s, and it took a hundred years for society to realize that burning a lot of hydrocarbons poses a clear and present threat to the survival of the human civilization. Birth rates? Should they be high or low? Would the invention of television be rated 100 or 0? How to decide?
In short:
* The input numbers are completely untrustworthy. Individual rankings are purely subjective. "Societal" estimations are, to use a term from dialectical materialism, *historically determined*, that is, they are constrained by the level of development of the society. Burning gas was seen a a good thing in 1880, not so much in 2017.
Ah, but we'll have an army of trusted estimators (a.k.a. the KGB) providing estimations of each individual's contribution, and we'll have Central Planning Committee providing estimations for inventions and innovations. True, it didn't work on Earth, but *our* society is different! We'll develop a perfect method of divining the future impact of any invention or innovation! We'll grow a generation of perfect snitches, intelligent, benevolent and with the capacity to see the future!
Basically, **garbage in**.
* The thing with history is that it's long and unpredictable. Children's activity in school and out of school is ranked... by fortune tellers, presumably; because how can one provide a trustworthy evaluation of a child's *future* contributions to society? Maybe the child will develop into a Faraday (born in a poor family), or a Tesla (born in a faraway and backwards country)? As children neither of them had any readily apparent prospects to do anything important in life, and yet they proved essential to the development of human civilization.
How can the Totally Democratic and Transparent Planning Committee of Clairvoyants decide how to *weigh* the individual numbers? They are submerged in a deluge of numbers: the boy Joseph Vissarionovich did great in school, the girl Marie Sklodowska no so well, a scientist named William Thomson discovered a method to compute the maximum signalling rate on a long cable, an economist named Karl Marx published an analysis of the capitalist mode of production... How can the committee judge how important is any of this events relative to the others? How can they tell which is positive and which is negative?
In the question, it is said that *"the quality of ore recently has become worse"*. This is bad, undoubtely. But what if this deterioration of the quality of ore spurs the mining company to explore new deposits, thus finding a much better source of ore?
Basically, **garbage out**.
[Answer]
This looks a lot like Asimov's [psychohistory](https://en.wikipedia.org/wiki/Psychohistory_(fictional)) but using only the current situation not projecting against changes to the situation. Your numbers are far too small for his purposes but the principle is the same at heart. It is hence a concept that a SciFi audience will accept.
**There can be one formula to rule them all**
# Problems exist
Many of these problems are solved by the much larger population numbers Asimov insisted on.
* Their technology isn't good enough to gather the data required for the number to be correct.
* 100 people surrounded by tigers are more bothered about whether they're going to survive into next week, never mind next century.
* The more factors you introduce, the more complex the formula, the less meaning it has to the ordinary person, and the closer it gets to 0.
* The mere presence of a volcano above their only town should reset the number to a permanent 0.
* On any day someone could go out into the jungle and catch the fever that will wipe them all out, the mere existence of something like ebola would give a permanent 0.
* You have to know *what* it is that's going to kill you to be able to do something about it.
* There can be one formula to rule them all but taken alone it has no meaning.
The granularity of data is there in the calculations, but the grand formula takes away any use it has in projecting the future. It becomes a toy for morale and nothing more, you need to hope it keeps rising.
To do anything with this number, to improve their survival, it has to be looked at as a series of values, one for each threat against the factors that mitigate that particular threat.
That sounds a lot like an insurance risk calculation though, which begs the question, when did insurance first come about? Lloyd's Coffee House was the place to go to get your insurance in the early days. Now known as Lloyds of London it was founded in [1688](https://www.lloyds.com/lloyds/about-us/history), so it's perfectly reasonable to be making risk calculations against a basis of 1880 technology.
[Answer]
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> Our young civilization is surrounded by a voluptuous vegetation and dangerous animals living in it. As a result of the fight for survival and due to the penchant of some of the early leaders, people began to calculate their own possibility of survival called “ProProg” (Prognosis of Progression).
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There are two kinds of society :
1. Survival problem ? Focus energies on solving the problem. This type survives.
2. Survival problem ? Focus energies on calculating the odds of surviving. This type becomes extinct.
The number you are describing would not, ever, be done by detailed calculation, but by some sort of empirical rule of thumb guess-work formula. It's the sort of number politicians like and technocrats actually have utter disdain for, because the number is useless in and off itself. The number provides no information on the nature of the problem and no idea at all how to solve it. It distracts from the problem itself and it uses resources to make it which could be better spent elsewhere.
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> The society has a stage of development comparable to middle Europe +/- 1880.
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We're almost 150 years in advance of that and *we* can't make such an estimate.
And we'd never agree on one estimate anyway.
Your society could *never* produce a useful estimate. All it could produce is a useless one done for dogmatic purpose ( "we must have a number, even if it's pointless" ).
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> It´s political and social framework is mostly technocratic.
> No electricity.
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We had electricity in the 1880's, if they had comparable technology to ours in 1880 and were technocrats then they would inevitably focus research on producing an electrical power production and distribution system over the less efficient gas. Electrical power is essential for forward development of technology - you can't match it with gas, and they would know that.
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> Main energy source is natural gas in diverse refined conditions. Gas sources are everywhere. Here our society is far beyond the technical status of earth´s 1880.
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This technology is limited. Electric lighting is far superior to gas - you can generate much brighter lighting even with early versions of light bulbs. High speed devices for machining need electric motor technologies - gas won't ever do it. Switching systems (like phones and primitive computing devices) require electricity.
As technocrats they would know this. Gas is a dead end technology for their society.
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> The whole administration and calculation is based on paperwork.
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So they're not a technocracy, but a bureaucracy. :-)
Once you start down the road of organizing everything around a dogmatic principle with no value (calculating the odds of survival) your entire organizational system will become warped to that purpose and everything else will become secondary. The bureaucrats and administrators will become the controllers and the technocrats will loose out.
That's inevitable.
The only way to have a technocracy is to make developing the technology for society's benefit a primary purpose - you need "social technocrats". And you need to ditch the daft calculation to make this work.
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> All devices used to help calculating should be similar to the ones used on earth until 1880, unless the availability of different types of gas allows other.
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Different gas won't fix the fundamental fact that electrical devices allow faster and smaller and easier to maintain calculating machines than gas ever could. This is simple physics and would be plain as day to your technocrats.
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> Steel is produced.
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In what quantities ? You have a tiny population to try and sustain even basic levels of steel production. I do not believe this is economically viable.
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> Lots of construction wood in the surroundings.
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Oh joy. :-)
Note also implies a lot of woodland that's soaks up resources to clear for agricultural production and housing needs.
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> Just one other humanoid group.
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That's so vague as to be useless. Are they enemies ? Are they friends ? Are they neutral ? Are they more advanced, less advanced, about the same ? Are they integrated into your society or completely apart ? Are you able to communicate with them on any level ? If you can't answer detailed questions like this then leave this other race out of your story altogether.
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> Formerly a few 100, nowadays round about 100.000 inhabitants.
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In a single century ???
Even if a quarter of the population are of child-bearing age in any five year period and they produce four children per couple in that period that survive to adulthood, they will barely be able to make the 100,000 mark in a 100 years.
But just sex alone won't keep a population alive !
They need food and shelter. And in your society they also need education and light and heat and protection and health care.
And that takes time to build and resources to make. Humans take time to grown and are not productive for the early part of their lives and cannot be as physically productive in their later years.
Factoring in all these things means your society will expend most of it's resources in simply expanding it's numbers and being able to keep them.
Rather than being able to focus on technology, they'll have to focus on agriculture and basic building and basic infrastructure - try designing and maintaining a sewage and water system for just 100,000 people !
So this is not realistic in any way. They'd have a hard time just maintaining the technological level they started with, let alone improving it.
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> A very solid and gigantic “town hall”, allowing shelter to most citizens and main production facilities
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A town hall large enough to house and shelter, say, 70,000 people in even the most basic conditions would be vast - an engineering feet beyond the ability of their technology and one that would be a massive undertaking for us now. Without the development of 20th century levels of water production, sewage management, cleaning systems and agriculture you would have nothing more that a miserable disease ridden slum.
The availability of wood makes the building of normal small dwellings more likely, simpler and more cost effective. This won't reduce or remove the requirement for a sophisticated system as described, but it's not as difficult to build and maintain as your giant hall.
The giant hall would be a serious problem in that it is difficult to expand it as the population grows. A modular town hall would be little more than a lot of connected sheds - useless for housing a population and it's social needs as well as production facilities.
So the giant hall is a non-starter.
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Beware [tautology](https://en.wikipedia.org/wiki/Tautology_(logic)), predictions of any kind tend to be self-reinforcing, any data that comes out of ProProg will be problematic. Actually it's worse than that, ProProg is going to be prone to turning [recursive](https://en.wikipedia.org/wiki/Recursion) since it has to take the manifold effects of ProProg into account in it's calculations (if the ProProg output data are made public, which they have to be if you want to act on them), that will alter said calculations which will also alter those calculations and so on. You will have extreme difficulty, as in it will be next to impossible, in getting anything usable out of a system that's sensitive enough to provide accurate predictions and then anything you get will start a fresh recursion loop.
The concept isn't exactly a non-starter but you have to be very careful to put some solid limits around what it monitors and how the data are presented to the public, if at all. A dip is of course worse than a lift, humans tend to panic during downturns, (see every market crash in history), but even a sustained high number can be tricky if people stop paying attention.
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The number in itself has no meaning and even less value.
The *process* to derive it, if rigorous enough, could be very helpful indeed.
What you really need is a way to move resources from one sector to another in order to maximize the number.
This is done very badly "on paper" and this is the real reason of (initial) Apple success: the first program readily enabling to do this kind of calculations (the first spreadsheet) "[VisiCalc](https://en.wikipedia.org/wiki/VisiCalc)", but I'm digressing.
For sure you need to, in some way, approximate this computation in order to manage the colony development. It is one of the "modern" discoveries that many interactions in complex systems are highly counter-intuitive and thus the development of a series of tools (from the above cited VisiCalc down) to help managers, at all levels, to take their decisions.
If useful to your plot you can devise a specific "plan office" where some skilled humans will emulate this "optimization" process "by hand".
Bear in mind the whole process will start as a very rough model and will be refined over the time, along with techniques for multi-variate maximization.
You need something similar to what has been done in early '70s by "Club of Rome" to give a rough estimate to [The\_Limits to Growth](https://en.wikipedia.org/wiki/The_Limits_to_Growth) (it has been heavily ridiculed at the time, but many of graphs proved somewhat true, unfortunately).
Reliability of computations in a small and culturally compact colony would be much more reliable than what possible in a 7billion+ inhabitants world with many conflicting entities.
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Have a look at [Maslow's hierarchy of needs](https://en.wikipedia.org/wiki/Maslow%27s_hierarchy_of_needs).
[](https://i.stack.imgur.com/IuWjl.jpg)
Based on your original premise, this is a splinter group from a colony that I would assume was seeded by an advanced civilization. So at least initially, the possibility that the know-how to prevent or minimize the risks of in-breeding would have been available, and I am sure that the means to grow the population in that regards safely would have been passed down to later generations, even if the **why** wasn't.
Similarly, the original colonists would have been aware of the above-mentioned hierarchy, or something similar, and so have based their rating scale on that. Initially physiological and safety needs would have been the primary focus, but they would have recognized that for their civilization to not only survive, but **endure**, the other needs would also need to be addressed at some point - and not in the too distant future either - "all work and no play" would have serious repercussions early on in the game.
Another important aspect to rating an improvement would be how many people will benefit and/ or suffer from an event/ implementation.
So one method would for the colony's founders to have broadly ranked ideas according to Maslow's hierarchy. If someone came up with an idea which might benefit a large number of the colony's population, the value of the benefit might either be put before a committee for ranking, or even put to a popular vote (as this might supply a benefit both the Love/ belonging and Esteem steps).
If the benefit was deemed to be good for a smaller number of people, it would rather be decided on by the people potentially affected.
But ultimately, the score could be worked out along the lines of *rank on the hierarchy* **x** **(** *percentage of population benefited* **-** *percentage of population harmed* **)**.
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Very good answers so far. From me just some afterthoughts:
Sounds like a steampunk and [Difference engine](https://en.wikipedia.org/wiki/Difference_engine) setting. No problem there in 1880.
Electricity just seems to be forgotten or impossible on this planet, perhaps too few or the wrong metalls, metall eating bugs / coroding plant sap ... and very good hard wood for your gas and difference engines?
I would expect your number 38 to be determined empirical, but then you would need experience with a lot of such colonies in the past (some big amounts of historical data from other planets or the last 10.000 years in books?) or very good models (calculated with your difference engine or by hand on paper).
To get more experience I would split (at least virtual) the colony in several self-governed parts. After some time the fitness of all the parts would be compared and correlated to their decisions. The fitness would be your number, e.g. calculated with number of children, combined weight of people, calories in stock, time with digestive problems and such. The more successfull parts would get resources (like people just voting with their feet) from the less successfull parts, splitting and diversifying again after a certain size is reached.
A hundred thousand (and fast growing) people just doesn't sound very "inhospitable" ;-)
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The **Lindy Effect** may make fools of your prognosticators.
The theory called the [Lindy Effect](https://en.wikipedia.org/wiki/Lindy_effect) basically says that the life expectancy of a particular thing (such as a civilization) can be expected to be about its current age. Your civilization ultimately will come to an end (unless the apocalypse comes first), so the question is not whether, but when. If it has survived for a century so far, the best bet is that it has another century left in it. But if it survives a second century, it can then be expected to survive *two more*.
The logic here is that the future is fundamentally unpredictable, but some societies are more robust to changing conditions than others, and this can only be observed over time. The longer they survive, for whatever reason, the longer you can expect that they will continue surviving. This applies even if the reasons they survive are entirely different from the reasons they *think* they will survive.
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My question is as stated above: if a planet is tidally locked to its sun, how would the people on the surface, assuming it's habitable, be able to tell time? What devices would they be able to use? Obviously a sun dial is out of the question.
I am also curious as to how they would develop a concept of time because they wouldn't be able to note the passage of time nearly as easily. I understand things would still grow and change, but this would take much longer.
So, assuming they evolved on this planet, what would a device look like to measure time on this planet, and how would this device have come about to begin with?
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* [Pendulum clock](https://en.wikipedia.org/wiki/Pendulum_clock)
* [Water clock](https://en.wikipedia.org/wiki/Water_clock)
* And from [here](https://en.wikipedia.org/wiki/Clock), candle clocks, incense clocks, hour glasses, etc.
Please remember that time is a somewhat arbitrary concept that has only been refined through mathematical expression (and the fact that so many "constants" are wacko numbers to the nth decimal place might mean that our "second" is still fairly arbitrary). Therefore, your people really only need to pick a quantity of divisions and use a divisible resource (see above) to mark those divisions and *voilà,* you can tell time.
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If the planet is habitable it is probably only habitable within a ring around the terminator where it's neither too cold nor too hot.
From there it should not be difficult to see stars and other planets and be able to tell years and months from their movement.
If the planet has one or more moons they can be used as well to measure timespans from months to days.
If the planet's orbit around the star is excentric enough there might be stronger variations in solar irradiation leading to periodically changing weather patterns, e.g. in the winds crossing the terminator and the overall temperatures, leading to some sort of seasons.
EDIT: About devices used, for the first two points that would just be astronomical devices or simply their own eyes, and in general they could just simply count e.g. the rise of a certain star or planet or moon, or the arrival of a certain warm wind or cold wind. All this could then be the basis for more artificial means of counting, e.g. by taking a moon period and cutting it into shorter timespans of equal lengths by using e.g. sand clocks or water clocks. Once certain shorter timespans are defined, they can again be shortened and with rising technology I can easily imagine mechanical clocks appearing, just like humans did on Earth. Once a basis for measuring timespans is established I don't see why they wouldn't invent the same kinds of devices as humans on Earth did. The main differences just lies in establishing the initial cycles everything else is based upon and those depend on the planetary circumstances.
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They might think about time entirely differently from us--as something that comes from people.
With no non-living examples of predictable change (assuming there are no cyclical weather patterns or seasons as well as no day/night cycle), these people might talk about time the way they talk about feelings e.g. "Gathering nuts takes a long time because it's boring."
Standard time might be first tied to growing trees, which get obviously and predictably taller. Maybe every tribe has a "clock tree" it uses to make sure everyone has the same referent.
If you want time cut into pieces smaller than "growing a tree," perhaps they could measure time by heart beats or eye blinks (depending on their anatomy) how long it takes to get hungry after eating again, and how long it takes to gestate a child (or incubate one or whatever).
More accurate and precise water clocks or candle clocks (or indeed clockwork clocks) won't be technically any harder for them to produce than they were for us, but I bet the inhabitants of this world will take longer to develop accurate and precise timekeeping, since they'll start from the assumption that time governs only earthly things, rather than heavenly.
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> **TL;DR**
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> The US measures distance in feet. However, even if humans had not grown feet, the general concept of distance would still exist.
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> Similarly, if there are no solar days on this planet, they wouldn't be using a *unit* of time based on a solar day; but that doesn't mean that the locals are oblivious to the general concept of time progression.
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How are people able to keep track of which day of the week it is, since a week is an artifical construct that does not occurr naturally?
The answer is that it is inherent to **tracking time**. When you track time, you are inherently aware of what time it is at a given point.
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> if a planet is tidally locked to its sun, how would the people on the surface, assuming its habitable, be able to tell time?
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Even though our planet experiences sunrises and sunsets (and your tidally locked planet does not), our method of keeping time is *no longer* connected to the sun rising and setting.
We've created completely independent time tracking systems (atomic clock, quartz crystal, expressing time as a function of lightspeed, ...), and we've simply decided to **retain the traditional time units** that used to be relevant when we tracked time based on the position of the sun.
There is nothing that stops humans from changing the time units to something completely artificial and unrelated to our planet's movement relative to the sun. We could e.g. decide that a year is now 400 days long for the sake of mathematical simplicity (i.e. the length of a day is unchanged, but there are now more days in a year). Although a year (400 solar days) would then no longer accurately reflect Earth's orbit around the sun, there is no problem with this change from a **time tracking** perspective.
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> What devices would they be able to use? Obviously a sun dial is out of the question.
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Sundials are passive clocks that do not need to be set (other than physically placing them). Which is nice, but much too inaccurate for our modern day standards anyway.
Your civilization can use any other clock that we use. Since they have no natural frame of reference (e.g. sunrise/sunset), they are free to choose **whatever method they want**. The only thing that's important is that the used time tracking method must independently yield consistent results. If you and me synchronize our watches, split up and meet again in the future, our watches should still be in sync (I'm omitting relativistic time dilation for the sake of simplicity).
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> So, assuming they evolved on this planet, what would a device look like to measure time on this planet, and how would this device have come about to begin with?
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As I said, most human clocks nowadays do not observe the movement of the sun. They simply *happen to be* using a unit of time that coicides with the duration of a solar day.
Therefore, you can use any timekeeping system which does not rely on solar positioning:
* Quartz crystals (the crystal's resonance defines the passage of time)
* Atomic clocks (the atoms' resonance defines the passage of time)
* Pendulum clocks (as long as gravity is constant everywhere on the planet at a given altitude, a pendulum can define the passage of time)
* Hourglasses (as long as the material consistently takes the same amount of time to go through the hour glass)
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> I am also curious as to how they would develop a concept of time because they wouldn't be able to not the passage of time nearly as easily.
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I don't quite agree with you. Even if our sun would not have moved, or would have moved erratically, animals would still have needed to rest from time to time.
*Because* we have a consistent sunrise/sunset, animals have historically adapted to setting their biological clocks to this rhythm, for the sake of simplicity (so that e.g. our eyes only really need to work in daylight, and less so in darker conditions). If we had evolved a sleeping pattern that was unrelated to the sun's position in the sky (e.g. awake for 30 hours, sleeping for 10 hours), then our bodies would simply have evolved to deal with life both at night and during the day.
**Time is not inherently tied to planetary movement.** Time is nothing more than a linear progression of events. It just so happens that we decided to use our planetary movement as a unit of time.
**Analogously**, the US measures distance in feet. However, even if humans had not grown feet, the general concept of distance would still exist! We would simply have used a different unit of distance, possibly either related to a different body part ("This wall is ten heads long and fifty heads wide") or using an artificially decided unit of distance.
Interestingly, [the **meter** is such an artifically constructed unit of distance](https://en.wikipedia.org/wiki/Metre):
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> In 1799, [the meter] was redefined in terms of a prototype metre bar (the actual bar used was changed in 1889).
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People literally just made a metal bar, and then said "the length of this bar is now called a meter."
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> *Edit:*
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> *A definition for a meter was then drafted, which may have tweaked the actual distance of a meter, since they used a rounded definition: one ten-millionth of the distance between the equator and the pole. However, before they decided to define a meter as such, they were already aware of **roughly** the unit of measurement they were looking for. If the outcome of this definition would have been 1mm or 1km, then they would have used a different definition for a meter, rather than define the meter as whatever the outcome of the definition is. Therefore, the **decision** came before the **definition**.*
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Why was this bar exactly that length? **No reason**. They just had to pick *anything*, really, so they picked this particular distance.
The only real consideration that was made is that the chosen distance was sensical to humans, e.g. it's impractical to define a unit of distance based on something a human cannot perceive, whether it's the width of an electron or the diameter of the sun. These are not intuitive because we have no way to easily see this distance or use it for comparative purposes.
As it is defines, the meter makes sense. It's roughly as long as a human leg, which means that we have a somewhat accurate representation of the meter on our body (just like the US foot).
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What I am imagining is some sort of gargantuan beast that encloses a star with its monstrous jaws and then feeds off the rays released by the sun to power itself.
I am curious what kind of creature would be able to 'devour' an entire star (typically the size of ours)
What adaptations would it need in order to survive in space and its star-eating lifestyle, and how would it travel?
I am aware though that such a large creature poses equally large problems regarding its function and its survival, but it's nothing a light sprinkling of handwavium and help from world building users can't fix.
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I propose a being that needs gravitational waves to survive. The being is a star (black hole, whatever) that has millions of wormholes terminated above its surface. The other ends of the wormholes travel light years to space until they find a proper source of gravity such as another star. The wormholes are such that the other star gets sucked in. As long as feeding takes place, gravitational waves are produced and your being is happy.
Sometimes, a larger celestial body gets your being turned inside out through its own wormholes, which is terribly painful, and causes serious psychotic breaks. These end with other stars being devoured.
**Edit:** some thoughts about how such being would exist. To make a wormhole, you need a dense kind of matter with negative energy relative to the vacuum. It is not known if such thing could exist. The being in question could be made of this type of negative matter, plus normal matter.
Normal matter is made of electrons and nuclei held together by electrostatic forces. Since the negative matter and normal matter would repel each other, it is hard to make a mixed atom. But, you could make a mixed system similar to a ionic crystal, in which the positive ions are particles of normal matter, while the negative ions are particles of negative matter. That mixed part of your being would have a zero gravitational footprint as its density is close to that of the vacuum.
Although your being might have zero mass, it can still get attached to celestial bodies, if its mass has a total dipole. Dipole means that overall, your being can be imagined as two centers of positive and negative mass slightly separated from each other. This is similar to what ferroelectric materials are: crystals with long range order in which positive charge centers are slightly displaced from the negative charge centers.
The interaction between a mass dipole and a another mass could be strong, but it will decrease with the distance much faster than the interaction between two masses of the same sign.
Your being would be a huge structure made of negative and positive mass, exhibiting a large mass dipole. On the positive end of the dipole, it should have a normal star or even a black hole, while on the negative end it should have the wormholes. The wormholes are structures with walls of negative matter, so they would only get attracted to other negative matter.
The positive mass attached to your being should have a larger mass than the wormhole, so there would still be attraction between it and the stars to be consumed.
When a star falls through the wormhole and tries to circle your being in order to fall on your being's celestial body companion, is should generate gravitational waves. If this process is violent enough, the gravitons could generate pairs of negative and positive particles. These pairs could be adsorbed to the surface of your being, effectively helping it to grow itself, similarly to the way you grow crystals by [beam epitaxy](https://en.wikipedia.org/wiki/Molecular_beam_epitaxy). You could also split the vacuum to generate negative matter for the wormholes.
If the celestial body to be devoured at the other end is too big, I can't see why your being plus star companion couldn't be forced through its own wormhole. In fact, I think you would also have wormholes going through that wormhole, but I don't want to think how that would work out.
As far as intelligence goes, you can assign your creature any intelligence level, but probably it wouldn't need to be too smart if it doesn't seem to have competitors. So, the psychotic breaks would be a personal touch. Otherwise, your creature would only "think" when there gravitational waves are strong enough to disturb its structure, as it happens during feeding.
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Do not, I repeat DO NOT freak out about this, but there are creatures known by Mankind that feed off the rays from stars. Governments around the world try to surpress this knowledge in the wider population, but I have seen some *speculation* online claiming these Things are called **"Plants"**.
OK, jokes aside, this is an interesting Question. I assume that something this big, if it is not collapsing under is own gravity, would most likely function like a Jellyfish. Also a collective of highly specialised specimens, that are working together. A tough, partial mineral or metalic skin for protection, and some sort of thrusters at one end, so it can move forward.
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A creature *more or less* like the one you describe is the co-protagonist of Fred Hoyle's *The Black Cloud*.
It is a denizen of deep space, that periodically manoeuvers around a star (the propulsion is a composition of lightsail and railgun jet) and forms a stable Dyson disk structure inside the Goldilocks zone, in the process light-starving any habitable planets already there, such as our Earth. The Cloud is composed of trillions of ice rocks covered with organic structures that electromagnetically interact one with another, and form a sort of distributed sentience.
Hoyle's Cloud does not shorten the chosen star's lifespan in any way, and simply lives off its light. But a sufficiently advanced Cloud might try and increase feeding efficiency by brightening the star, enlarging and pushing farther its Goldilocks zone. It could maybe do so with beams of *really* energetic [muons to increase hydrogen-hydrogen fusion](https://en.wikipedia.org/wiki/Muon-catalyzed_fusion) in the star and move it closer to the surface (of course it would need more efficient technologies than Earth's, or the process would be antieconomic).
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If your creature exists in higher dimensions, it might be able to just pluck the star out of our own dimension, like a 3-D being can lift a 2-D being off a sheet of paper. This avoids the problems you would have with conventional physics if such an enormous creature tried to eat a star in our regular three dimensions. It would also be extremely disruptive to anything that was previously in its gravity well, like inhabited planets, which may or may not work for your story's plot.
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A creature that behaves like an organic Dyson Sphere would of course be enormously titanic. It would probably resemble a vast Jellyfish and if it exists as a photosynthetic autotroph of some kind then it would not need to literally devour the star it feeds from, instead it would perhaps envelop the star with its entire physical form, absorbing a high percentage of the Star's output. Such a creature would have to be able to resist extreme temperature gradients and intense radiation. It would also presumably require a source of water, which does not exist in main sequence stars. It would also have to be extremely endurable in order to resist being inflated to bursting point by the solar wind produced by stars as it feeds.
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Now, I know you said that it is unfeasible but if we combine two theoretical pieces of technology we can create a much more realistic being-
## A self replicating Dyson swarm
Now first, what is a Dyson swarm? Well a Dyson swarm is a swarm of satellites that surround a star and collect it's energy output. Here is some concept art:
[](https://i.stack.imgur.com/XHpeL.png)
This could then be built to have control robots that mine the planets and other celestial bodies in that solar system. Whilst the robots do that it could be collecting energy from the star and charging it's batteries. The robots would also be building another copy with the material they mine. It then gives the energy it collected to it's offspring. Once fully charged The daughter swarm goes to another star and does the same thing. The parent swarm will then stay around that star until it is about to die, collecting energy, charging it's batteries and collecting deuterium (An isotope of hydrogen that has a neutron as well as a proton. if two of these atoms were merged helium would be produced. That is the concept of fusion power.) . Once the star is about to die the swarm then moves to another star. Movement is simple as each satellite would have a fusion drive.
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I'll go full Lovecraft on this one.
**A giant self replicating fungal organism**
It could be as old as the Universe itself. Plus, in some mythologies, it could be *the* center of the Universe, much like Azathoth. Being such an old and awesome living being, it's constantly puffing spores to every direction.
The Universe is very, very vast, but it's pretty much empty, so the probability of a spore being ejected in a direction that will make it close enough to any star is low. These spores could be ejected at low speed, so they wouldn't had time to get close to stars much further than were this being resides. On the other hand, a mysterious void in the Universe could pinpoint the location of the mother-organism.
When one of these spores get close to a star, it begins receiving energy from it in a process similar to photosynthesis. This make the spore grow in a polyp, which in turn produces more and more spores, until the star is completed surrounded. Then, the polyps mature and begin to enclose the star, closing the gaps between them until absolutely no light escapes from the star.
From an observer, outside this, it would look like the star died, because it vanished. Instead the star would be still fully operational, but 100% of its radiated energy would be absorbed by the fungal structure.
After a star is fully enclosed in this deadly embrace, it would start producing and puffing spores by itself.
This could pose a danger for the Universe, since in a few trillion years the spores could have reached a good part of the stars.
EDIT after andrey's comment. I thought about his very valid critic, and I'll enhance my suggestion.
What we perceive as dark matter and dark energy are indirect evidences of an orthogonal universe. I'm not using the work parallel here, because if another universe is totally orthogonal to ours, the mathematical projections of their dimensions onto ours would be zilch, hence we wouldn't perceive it. However, its mass and energy would affect our cosmos, hence the dark matter and dark energy.
These fungal organisms could be pandimensional beings, which exist in several different ortoghonal universes. I do understand the problem of the blackbody radiation and the source of matter for the spore-to-polyp evolution, and I propose the creature to funnel matter and energy between universes. Then, from an outside observer, the star would seem to be devoured, and there would be no blackbody radiation, since all of the absorbed energy would be funneled to another universe, in exchange for matter to grow more spores.
This way this pandimensional fungus would still conserve matter and energy, but not on a local single-cosmos-wise system. It could act as, for example, an organic Dyson sphere from an even higher civilization that learned how to control this organism. They would seed these fungus on several universes and let them evolve, so whenever the spores find a star and began their transformation into an organic Dyson sphere, they harness this energy.
I guess I went a bit too wild on this one, but I got truly excited on this idea!
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I have a world with 9 year days. That is, the day-night cycle here lasts 9 years, where ours lasts a mere 24 hours.
Very similar to a tidally locked planet, except the habitable belt moves. The species that have come to live on this planet have evolved to instinctively migrate west to avoid the night. The terrain consists of very few mountains and oceans, with lakes and vast expanses of plains being more common. Towards the poles, the night side temperatures become so cold that massive glaciers carve the land and provide water to fuel non-mountainous rivers. While the day side gets less water, the land itself is more hospitable.
The astronomical features of this world include a small ring system and multiple smaller moons.
As I was designing the cultures living in this world, a question began to arise. If these people are circumnavigating the globe since before they were even self aware, would the idea of a flat earth even start in the first place? If this world's inhabitants did once believe in a flat Earth, would their migratory nature allow them to discard this idea sooner?
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If species evolved on this planet they would have also developed built-in biological mechanisms to enable them to navigate across their world. There is quite a repertoire of such mechanisms. Observing the polarization of the sky, sensing magnetic fields, and celestial navigation turn up in a wide variety of organisms.
It is possible creatures on this planet will invariably be equipped with one or more biological navigation mechanisms. This will be essential for their survival.
One consequence may be for a sapient species on this planet that they may aware instinctively their world is round, but may lack a conscious cognitive awareness of the fact. They will understand, without having to explain it, that their lives are spent moving in great spatial circles. Each one of which takes nine years to complete. In the same way, we know each season follows, one after another, until the annual cycle of the seasons is complete and continues ever onwards.
This would make it virtually impossible for them to conceive that their world was flat. To them this might be an absolute fantasy. However, it could be an interesting moment in their intellectual history when they go from a purely instinctive understanding of being on a round planet and knowing this to be a fact.
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If we put aside the "mythology" on the flat earth believer of ancient times, we can see that the awareness of the planet being round was well spread even before circumnavigation was possible: Eratosthenes calculated the globe's diameter when just crossing the Mediterranean was a challenge, and did this based on purely astronomical evidence (the shadow in the well).
Other evidence also leads a scientific mind to conclude the planet is round and not flat, like the different duration of day and night when traveling along the meridians.
All of these phenomena would hardly be noticeable in the world you describe, as there would be no stationary populations. Indeed, the fact that after nine years a migratory population comes back to the same location is more evidence they cannot deny.
Assuming that they have the possibility to develop some sort of scientific mind, on the level of ancient Greece, I see the same chances as in our history.
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It's obvious that for people that return to the same point every 9 years just by sailing westward, realising that the world is round will be a lot easier than it were for ancient humans here in Earth. If we take in account that ancient Greeks knew that the Earth was round and they even managed to measure it, it's clear that early scientists in the OP's world will soon be rather sure that their world is round.
However, is it still possible than common people or pre-scientific (pre-geometric) cultures believe that they live in a flat world in spite of circling it every 9 years?
It is harder than in Earth but it is possible.
* Thermal an ecological conditions are like to vary a lot in the sunlit face. Some species and cultures may be restricted to just certain latitudes and/or small patches near the trailing or leading terminator. The path followed by people living higher latitudes is not very different from a circle in a flat world, so they might fail to notice that they are circling a sphere near its pole.
* Although at most latitudes circling the Earth in 9 years would mean moving tens of kilometres westward every month, depending on how big is the planet, what latitude the people live and how fast they travel, they could manage to do so without navigating. If you are fast enough, you could just wander randomly moving to the sun when it's too cold and away from the sun when it gets too hot. This way you could circumnavigate the globe without doing any navigation nor realizing it's spherical.
* To realize that you return to the same spot every 9 years you need to recognize some features. The world can just be featureless, like an ocean world of insondable depth, or a flat world (no plate tectonics, no vulcanism, no mountains, no seas...) where any new feature is wiped away by 4 years of scorching sun followed by 4 years of glacial age.
* If the orbit of the planet is somehow eccentric, climate distribution can be different from one "day" to next one. Therefore migrating paths can me more complicated than just returning to the same spot every 9 years. If their path is complicated enough, most creatures won't return to the same place in their whole lifetimes and therefore they won't notice that they follow a closed path (although I must admit that they need to cross their own path at some point, but this factor could be combined with any other above to keep this crossing unnoticed or explained by a reason not involving a round world).
In summary, roundness of world it easier to notice than Earth's one, but it still doesn't need to be self-evident.
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They would very quickly discover that the world is round, they would have discovered this before they even had a written language. Off topic here, but what are the conditions on the night side for 4.5 years? Because a civilisation might just build a settlement every 20 lines of longitude and remember where it is so they can use it again, unless the conditions on the night side ruin every settlement.
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**Setting:**
We have alien-constructed stargates connecting different solar systems to each other, but otherwise it is a hard sci-fi universe with only known-possible technologies. We have fusion drives. But no warp drives, artificial gravity, or powerful shields.
Our protagonist is suspicious that one of the spacecraft in the system is not what it seems. He already has plenty of passively collected data from his long-distance probes. He would love to take a closer look at the spacecraft's characteristics and confirm or deny his suspicions. But wait a second, is there any way to do that?
**The Question**
Would it ever make sense for someone to use active sensors to look "more closely" at someone's spacecraft to determine its characteristics?
Thank you for the help in advance. You guys are super smart, and it's been fascinating lurking here.
**Edit:**
To clarify, we are watching a suspicious vessel - it may truly be civilian, or it may be a military vessel cleverly disguised as a civilian one. For instance, maybe it has a coilgun and additional radiators hidden in its hull. Is it likely that active sensors could give us a decisive answer to this question, where passive sensors could not?
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Yes, to some extent.
First, there is the [doppler radar](https://en.wikipedia.org/wiki/Doppler_effect) that lets you know the target's relative velocity instantly, without waiting. This can be a game changer, measuring velocities using passive ways requires you to wait and allow him to fly away and get a head start.
Now for the shielding - it is cheap, but still costs money. Commercial vessels will only shield against things that are both dangerous and expected. And they will only shield as much as is needed, not more. The fact your target is *more opaque than it should* will tell you quite a lot - it will confirm he is hiding something. Still, in real life most of the time it is quite sufficient for us to just know the shape of our target. So if it is less *reflective* than it should be, be suspicious. There is literally no reason to prevent reflections for commercial crafts.
Now the main reason for using active sensors in modern military: *precision*. We can detect planes using passive means all right. Visible light, thermal etc. Still, when we need precise information about its location we use radar. If you will have a chance, compare a night vision goggles image with just using a flashlight. I think you can imagine the difference - image quality is much, much better with generous amounts of light. The idea that there is a need for active sensors to get details is believable all right, because that's pretty much what we are using in the real world, too. The flashlight analogy is also pretty good at illustrating side effects:
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> Be wary though: using an active sensor (like a radar) means the ship can see you observing it. The flashlight comparison is accurate on this issue: sure, you see better, but if you search someone, he'll know and be able to precisely locate you. – [Keelhaul](https://worldbuilding.stackexchange.com/users/38047/keelhaul)
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Even if you [use external illumination](https://worldbuilding.stackexchange.com/questions/85263/does-it-make-sense-to-use-active-sensors-to-learn-more-about-an-enemy-spacecraft/85266#comment250652_85266), your target will know someone is looking.
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It really depends on the kind of details you want. Since you specifically asked for technologies we know its at least theoretically working, I want to focus on what we know from experience that works, followed by a wild speculation.
If you know the position of the suspicious vessel, you can use either radar or some kind of lidar (basically a laser-radar, using laser-frequency photons instead of radio photons). Both will be able to determine the current vector relative to your vessel.
Current velocity however isn't very indicative of what you want to know. But fortunately, both radar and lidar should be able to determine the spacial form of your target, specifically what kind of propulsion is used and how large it is. You might calculate an approximate maximum accelleration based on this.
What I think might be even more indicative than the exact dimensions of the drive itself would be the means of heat dissipation. Power systems produce a lot of emissions, especially with fusion-powered systems. You need to get rid of that stuff, so look for heat sinks.
The vessel will need as much heat sinks as it has power available, otherwise it will fry itself when going full power.
You could use the reflection behaviour of the material you're looking at to determine it's type and guess it's use, not every surface needs to be a heat sink (see: story weakpoint)
But there is a caveat: unless you have drones in the proximity of your target, you'll probably not be able to see every heatsink, as you won't get any reflection from the sides not facing your own vessel.
Also, the range might be limited, because after bouncing from your target, the radiation will scatter much more, and radiation will, unless it is lased, diminish proportional to the second power of the distance (see: inverse-square-law).
Thus, you will probably close in distance much more to have sufficient sensor resolution.
**Story weakpoint**
Now this is a weak point of your technology stack: Technically, it isn't too feasable to use fusion power, as the only ways to get rid of the heat in space are either dropping coolant or blackbody radiation. You could estimate needed radiator area by using [Getting rid of heat SE](https://worldbuilding.stackexchange.com/questions/59402/how-to-get-rid-of-all-the-heat-in-my-spaceship) Unless you want to overlook this scientific fact in your story (it is science-fiction after all). You could always invent some way to address this.
**Other things to consider:**
You probably wont find anything that is penetrating the hull of the suspicious vessel, as it will be heavily shielded against everything freely floating in space, like microwaves, gamma rays etc., since they will be facing the sun at some point (probably most of the time). Even if you could, you'll be killing the crew anyway.
**However:**
It seems to me, that in many cases, it doesn't necessarily depend on whether you use active or passive sensors as much as your distance and the targets emissions. These, in many cases, have a much higher factor in determining detail than the type of sensor you use.
[Answer]
For many purposes you can use passive sensors, since everything is being done against the 3K background of space. Ships will be radiating heat like a lighthouse against the thermal background, and the use of energy to manoeuvre, use weapons etc. will make you stand out even more.
However, very small weapons like "Soda Cans of Death" (SCoDs) will be more difficult to detect due to their small size and low thermal mass once free of a missile bus or ejected from a rail or coil gun. Devices like that will need to be tracked with a high degree of accuracy either to avoid them by jinking your spacecraft or using a Ravening Beam of Death (RBoD) laser to destroy them from as far away as possible (theoretically, up to a light second away). (For the provenance of these terms see: [Rocketpunk Manifesto](http://www.rocketpunk-manifesto.com)
Of course, the laser itself could be used on a "wide" setting or farther than a light second way. The intense thermal energy will heat up things like SCoDs, making them stand out even more against the background of space and allowing active defences to be mounted from a much greater distance.
[Answer]
I say yes but for a different reason than those already given. Would it ever make sense for a cop to pull over a car that was not doing anything wrong? Sure. Why? **Because the interaction that ensues can give away what the driver is really up to.** An active sensor uses energy to send a signal, and derives information by how that signal interacts with the object sensed. By that definition, a radio hail from a human is a sensor too.
A good cop can sniff out when something is not right. Non-communication active sensing may provoke action that tells you more about the ship than your scans could. Suppose the incoming ship does not respond to an active scan. That is useful information. It either did not detect the scan, cannot respond, is playing dumb or does not deign to respond. Follow the scan with a courteous hail appropriate for the relative status of the two ships. The human components of that incoming ship may not be as good at concealing their true nature as the ships engineers were. If they are nervous, or do not know the mode of interaction appropriate for their cover (e.g. Navy SEALS masquerading as truck drivers) they may give themselves away. Suppose you receive back "What the !@'s $#!@ are you scanning my ^&~\*@! for, you \*&!?" That might be reassuring.
I hope this is a story because I like this as a narrative device: the engineer and science officers argue (as in prior answers) over how to use deflected particles to gauge mass, use radar / lidar. Then the captain opens a channel.
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In most cases, you would not need active sensors at all. All bodies radiate heat, and the amount and temperature of such radiation give a lot of information. By comparing an object's increase in radiation to its delta v, you now know it's mass and likely composition. By comparing its temperature to its brightness you know its size. There are very few things an object's own radiation won't tell you that you can determine by bouncing other radiation off of it. In addition, its very hard to mask radiation, as the only way to do so would be in a heat sink which would have to be emptied quite quickly, or to radiate in only one direction which would limit changes in velocity.
[Answer]
It depends (as always) on specific circumstances but if question only is: "may active probe be more efficient to discriminate a heavily armed vessel from a civilian one?" the answer is **YES!**
The ultimate probe is a *real* (looking) nuclear attack missile. This "probe" will look like a real threat and elicit the highest counter-measures available.
In case these counter-measures prove insufficient (i.e.: we are dealing with a civilian ship) the "probe" can be stopped short of its destination, otherwise we already have a good assessment of military ship capabilities.
This can be a bit "over the board", but is a viable example of an effective "active probe" ;)
[Answer]
I'm not really a hard-science guy, but I think I have a clever idea to do all of this legally in this world, it may only take the simple process of figuring out of it is plausible by our own rules of physics.
In this world, there must a ray/beam (radar) of some sort used by the authorities to automatically scan a ship anyway, consider this process/system similar to scanning someone's public records or internet history.
By using some kind of electro-magnetic wave, used to scan all sorts of electronic devices for their data and basic information. The reason this legal to used by the police (space patrol) is because anything that the ship's owner/pilot wants to stay safe and hidden from the public is automatically blocked from the scan's point of view. What exactly is going in space for the authorities to check any type of ship in the first place you might ask?
By using this basic Scan Beam, the user can see everything the ship is made out of (physical prompter) and everything that isn't blocked inside the owner's public data record (electro-magnetic prompter). Think of this as a 3-D mapping of the ship owner's place of hold, without the use of x-rays of course to keep the privacy to the owner. However, the police can still see every corner of the ship's exterior to check if it is indeed, an exact copy of the normal ship model.
And by using the "data prompter," you can see into the pilot's skill records to compare them to whoever's actually driving the civilian ship, or maybe there's very slightly wrong with the data record when someone else is driving it. Because of this system of public data, the police officer might see who's piloting the ship compared to who's actually supposed to be piloting it.
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In the Cold War the adversaries had huge amounts of nukes, a readiness to deploy these nukes and a second strike capability that assured that in a nuclear war both sides would be destroyed (mutually assured destruction, a.k.a. MAD). The question is to come up with a different system that doesn't involve this huge amount of proliferation-prone dangerous weapons.
E.g. the US could change the course of a few large ten km diameter asteroids so that these are guaranteed to hit Earth in a few years time. The US would change the course of these asteroids periodically, so that doomsday is always a few years into the future. The existence of such a system will be made public.
So, after a nuclear war in which the US is destroyed, the enemy must then also be be to change the orbits of the doomsday asteroids within a short amount of time. The requirements of winning are thus made a lot tougher than just having escaped the worst consequences and having survived as a nation state.
But this is just one example of a probably not so perfect solution to the problem of having a MAD system that doesn't involve a huge investment in dangerous weapon systems.
**What is a system that would allow MAD but that the enemy cannot easily combat or reproduce?**
[Answer]
MAD existed because of a combination of two factors:
1. The weapons of annihilation can be deployed with little chance for your enemy to stop you once you have committed your weapons.
2. There is a delay between the time you commit your weapons and the time when those weapons have actually taken effect. And this delay is long enough for the enemy to commit to their own capabilities against you.
The example you suggest doesn't qualify, since there are many ways to neutralize the system you propose. Sending missiles to destroy the machinery on the asteroids, sending robots there to just directly take control of that machinery, figuring out how to fake the signal used to control them, etc. Note that this would be done preemptively, before you engage in a nuclear war (and likely with the backing of literally the entire rest of the world).
Stopping a thousand ICBMs is much harder. As is stopping sub-launched nukes.
You want something which has property #1, but without something that could proliferate. That is, it can't win through force of numbers, but through force of force.
That's difficult. The smaller the number of anything is, the easier it is to attack them. Your asteroid example falls prey to precisely this: there are only a few of them, so they can be attacked and defeated. Or the signal can be hacked. Etc. Indeed, if so much as one person leaks the secret of the signal, your weapon is rendered impotent.
The most effective way to guarantee #1 is having a lot of something. But they don't all have to be the *real* something.
Let's say you engineer a super-virus, which will be deployed by ICBMs. Instead of having thousands of viral warheads you have thousands of *potential* viral warheads. Only 5 of them will have the actual virus. And you can make sure that *nobody* knows which 5 are the real virus. You can even make the fact that only 5 are the virus a closely guarded secret.
That keeps proliferation under control, but still ensures that you have second strike capability.
[Answer]
Build a good old-fashioned doomsday machine. Admittedly this means accumulating more nuclear explosive devices in one place. The detonation of the doomsday machine is designed to exterminate all life on planet Earth. Therefore, no nuclear adversary will launch an attack against your nation for fear of mutual annihilation.
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> A doomsday device is a hypothetical construction—usually a weapon, or collection of weapons—which could destroy all life on a planet, particularly Earth, or destroy the planet itself, bringing "doomsday", a term used for the end of planet Earth. Most hypothetical constructions rely on the fact that hydrogen bombs can be made arbitrarily large assuming there are no concerns about delivering them to a target (see Teller–Ulam design) or that they can be "salted" with materials designed to create long-lasting and hazardous fallout (e.g., a cobalt bomb).
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Source: Wikipedia entry on [Doomsday device](https://en.wikipedia.org/wiki/Doomsday_device)
The only the major super-powers will capable of constructing such megadeath machines, on second thoughts, that should be gigadeath gizmos, so the building of doomsday machines will be effectively confined to the USA and the USSR during the Cold War era. This will effectively inhibit the proliferation of other nations building their doomsday machines. This is one arms race nobody wins.
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> Since the 1954 Castle Bravo thermonuclear weapon test demonstrated the feasibility of making arbitrarily large nuclear devices which could cover vast areas with radioactive fallout by rendering anything around them intensely radioactive, nuclear weapons theorists such as Leo Szilard conceived of a doomsday machine, a massive thermonuclear device surrounded by hundreds of tons of cobalt which, when detonated, would create massive amounts of Cobalt-60, rendering most of the Earth too radioactive to support life. RAND strategist Herman Kahn postulated that Soviet or US nuclear decision makers might choose to build a doomsday machine that would consist of a computer linked to a stockpile of hydrogen bombs, programmed to detonate them all and bathe the planet in nuclear fallout at the signal of an impending nuclear attack from another nation.
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Doomsday machines are not perfect deterrents. They represent MAD on steroids. Waging nuclear war with doomsday devices would be war by suicide.
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This was a strategic road the Cold War super-powers didn't go down. But if planners were attracted to its possibility, then it would be reasonably easy to maintain a massive array of nuclear weapons, that constitute a doomsday machine, in a single location. There would be no concerns about launch readiness. It could be deployed immediately once the go-codes were properly authorized.
[Answer]
We actually have such a system these days: **Distributed Denial of Service**
As more and more of our world becomes dependent on the Internet functioning at high speeds, the ability to disrupt this communication can be catastrophic. Imagine a world shortly in the future where cars are navigating and talking with each other over the Internet; where airplanes fly pilotless remote controlled by command and control systems over the Internet. Bitcoin is the main currency of the world.
The reason DDOS can act as a MAD device is because there are MILLIONS of machines just waiting to fire their payloads, on every network, in every ISP. Most houses in America probably have at least one compromised device on their network. Antivirus and firewalls don't help, because any machine can become a cannon spewing forth network noise.
You don't know which machines will cause trouble until the "fire" command is sent, at which point your entire Internet is being flooded with nonsense garbage.
I had a rack of web servers on a 10GB link go down because it was receiving 10GB of packets containing nothing but the string "SO I HERD U LEIK MUDKIPZ". **Seriously.** We did what we could, but basically we just had to weather the storm.
What are you going to do? Filter the packets out? You'll spend more CPU power trying to filter the packets than you possibly could have. Firewalls are useless, because they have to know who to block, and you're getting traffic from a million addresses. You can't blackhole blocks of addresses, because they're randomly distributed over the entire address space. You can't whack specific addresses because new addresses will just pop up to take their place (and now you're spending MORE CPU trying to filter out addresses). Literally the only thing you can do is SHUT DOWN THE NETWORK and wait for the DDOS to stop.
The attacker, on the other hand, has no such problems. They have command and control over the botnet, so they can instruct the botnet to avoid their specific address space. Routers will handle intra-country traffic, and just ignore the rest of the world. It's a MAD situation, so I'm not talking firewalls, I'm talking literally unplugging the country's network from the rest of the world. Even if the rest of the world retaliates, there's no route back to your country.
Won't the enemy just cut off their network? Sure, but it's too late: you've sent the command to DDOS and infect. They'll have to play whack-a-mole, tracking down individual machines and disconnecting them from the source. Every IP camera, every cell phone, every car WIFI access point can be an potential DDOS transmitter. The Internet is dead, everywhere, except the specific places you took offline beforehand. Self-replicating self-healing botnets reinforce themselves, scramble addresses, go dormant when anyone gets too close to finding them.
**This is mutually assured because either side can pull the trigger.** The Capitalists and the Commies probably both have botnets in each other's country. The first strike involves activating the enemy network, then pulling your network cables before they can send a retalitory command to THEIR network. Or at least that's the theory. There's probably backup command servers, canary heartbeat servers which would discover that they're disconnected from NORAD and start firing... but that's the Mutually Assured part. It's each country's job to keep their botnets from unintentionally destroying the other country's Internet, while technically allowing a non-nuclear option.
**EDIT: What about 'Mutually'?**
There's a point to be made that script kiddies can do DDOSes. I've been DDOS'd by 4chan, and it's not cool. But modern infrastructure has terrabit pipes, you'd need to be a state-actor level in hacking and network building. 4chan machines generally come from a pool of machines used for criminal activities using command and control software based on DNS records or IRC chat rooms. This is fine if you want to swindle a few credit cards or knock a colo server off the grid. MAD level DDOSes will depend on almost-sterile computers with just the enemy state's code on it. It'd probably actively immunize the OS against other virus type activity. It must be undetectable except under the highest scrutiny.
Ironically, a MAD DDOS system would likely increase the security and stability of the enemy state's computers up until the moment the button is pressed.
**EDIT: What about the "Assured"?**
Neither side actually expects a nuclear strike to be the end of the war. Maybe, at the very beginning, the idea of a 10 minute war was viable, but both sides have so much redundancy and readiness built in to the Nuclear MAD that we focus now on a First Strike; the hope being to hit so hard right away we can stop a retaliation and force a surrender before the other side gets reorganized.
"We've got enough nukes to destroy the entire earth 12 times" (or whatever) isn't realistic, because we expect most of those missiles to miss, or burn out, or fail to launch, or refuse arming commands, or be jammed, or intercepted... that part of the "Assurance" for Nuclear MAD; so many missiles you can't stop them all.
The reality is, a Nuclear War would involve a first strike followed by the remnants of each country fighting for survival and victory, with hopes that enough of the other side's infrastructure is destroyed that they can't fight longer than we ca.
This is why a State Actor DDOS can be MAD. It's "Assured" that the first strike on the enemy WILL scramble their communications, crash their infrastructure, cause power outages and civilian panic, disrupt transportation channels. You hope you can scramble the enemy long enough to get conventional bombers or marines or whatever to destroy or capture the command and control of the enemy while they're disorganized and force them into defeat.
**EDIT: But what about the "Destruction"?**
My intention was that this shortly future future is way more reliant on Internet than we are. I'm not talking "you get to work and can't log in to email," I'm going for "nobody's cars will leave their driveways because they can't establish a link to the traffic router" and "an undetected flaw in the control systems for that nuclear power plant allowed an attack in, but nobody can log into the computer because it's too busy throwing away packets."
I agree, this disaster isn't as obvious as nuclear weapons, but if you've ever worked in a datacenter, you've seen how the phones will light up and alarms will go off when 4chan's Orbital Laser Canon turns on them. And that's for people's cat websites. Servers don't just get their network card jammed; they shut down, overheat, cause rolling failures as the stress backs up into further systems.
I'm not talking Netflix going down; I'm talking planes falling out of the sky because they ran out of fuel waiting for clearance to land because the control tower computers crashed. I'm talking hospitals backing up because none of their high-falutin' test equipment is responding to commands, MRI machines have exhausted their supplies due to crashing, and the entire medical records system is locked up nation-wide, so everyone's medical histories, allergies, everything is essentially gone. The central communication systems of the government probably still work, but they've just been thrown back to Early World War II as every computer around them is either spewing crap or being buried by crap.
If nothing else, it'll cause panic, confusion, and fear in the enemy state, as everyone suddenly finds themselves trapped in the 50s. Many in this generation have never used a rotary telephone or been without an internet connection for more than a day or two. The initial panic, confusion, and fear could be enough to destabilize the other side.
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Maybe using biological weapons. Rockets contain airborne viruses set to release in the case of an attack. The Rockets release the virus into the atmosphere while the wind currents spread this man-made plague worldwide.
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A collection of doomsday devices. Any one doomsday device would be subject to being taken out. At several sites in the US very large cobalt bombs are build underground. Each bomb is connected to as many other bombs as practical via independent fiber-optic links, each bomb uses this link to keep repeating a status report. Each bomb reports "It's o'clock and I'm fine", signed with it's own private key and also a copy of the most recent report from every other bomb. It also has sensors of some kind to report that the nation is ok. (For example, it has a list of several nearby radio stations and it makes sure they're on the air. It has a tap into nearby internet cables and records the amount of traffic etc.) If this traffic drops too much it's report says "It's o'clock and the world is awfully quiet." It could also report "It's o'clock and the world is awfully radioactive."
Each bomb pays attention to the reports it hears (or fails to hear) from the other bombs. If it gets too much bad news it figures the nation has been destroyed and it's report changes to "It's o'clock and I think we have lost. Detonation in 48 hours..." If it's a mistake a human reading that can know what bomb and where it is and go fix the problem. If it's an enemy agent he doesn't have the codes, all he knows is that there's a bomb **somewhere** counting down to detonation.
Unfortunately, any such approach will cause the destruction of the world if the nation that builds it falls to something other than enemy action.
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Make them economically dependent on you.
Pick some intermediary product which is needed by a lot of different industries and which requires raw materials you have easy access to. Basic electronic or mechanical components are a good bet.
Heavily subsidize the production of this product and export it very cheap to your "enemy". Make sure you vastly undercut the competition in the enemy's country to get them off the market. Don't worry, your enemy won't mind, because those unemployed workers will find new jobs in all the companies which benefit from being able to acquire your product for cheap.
Your goal is to obtain a monopoly trough price dumping. But even after you have achieved that goal, do not start to become greedy. Keep selling cheap, even if you are selling at a slight loss. Think of it as part of your defense spending.
After a while the enemy country will no longer have any of the infrastructure or know-how to produce that product, even though large parts of their economy depend on you as a supplier.
They can now no longer attack you, because crippling your economy means to cripple theirs as well.
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It is a fairly reasonable argument that MAD *doesn't* require large numbers of nuclear devices - or at least large numbers of launch platforms. Outside of the US and Russia, most nations' nuclear deterrents consist primarily of a couple of submarines, with one or two on patrol at any time. A single *Vanguard*-class submarine for example can carry up to 192 warheads, with a combined energy of over 90 megatons - 6,000 Hiroshimas.
So a small fleet of submarines is easily capable of providing a deterrent effect for most purposes.
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Society might eliminate the expensive and vulnerable delivery systems. There would be a large nuke installed in a bunker under a Russian "embassy" in a dozen major US cities and vice versa. Activation would be much the same as already exists on submarines, but the staff would be in much better communication with their home country and the world, so less easily deceived. Also they could not fool themselves that there was any chance of personal survival after they "launch".
So much the same deterrence we have with missile submarines but far less expensive and far less risk of error. Also less warheads needed, no overkill. If the superpowers ever go MAD at least they won't take all of the human race down with them! Also no risk of a destabilising arms race.
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A society should marry all their women to the enemy, ensuring total annihilation by said wives should the enemy be foolish enough to attack.
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In my world (that takes place on an infinite plane), there exists an empire (let's call it Usotuhr) that is hell-bent on establishing human hegemony, or at the very least a human foothold, in the world. Due to this, they have launched a series of colonization programs that they call "The Manifest destiny". The only problem is... They don't have enough people. The rapid sending of humans overseas eats away at the domestic population, those who are comfortable in their environment won't go, and those that do go don't reproduce quickly enough to establish any significant population in the region.
My question is: Is there any way to cause rapid overpopulation?
(Edit : Growth )
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I think the obvious answer is: Make it socially and economically desirable for people to have many children.
Are we assuming a modern, 20th century or later society? Or a more primitive society? I'm assuming modern.
The average woman is fertile for about 25 years of her life. Presumably most women could manage to have a child every 2 years. So why does the average American or European woman not have 10 or 12 children in her life? Presumably because having and raising children is, (a) a lot of work, (b) expensive, and (c) interferes with other things a person might want to do in life.
So simple idea #1: Direct pay-offs. Promise \$X for each child someone has, either a flat fee or a monthly stipend. Of course the amount has to be enough to make it worth people's while. I wouldn't have another child just because you offered me \$10, but I surely would if you offered me \$100,000.
In the past, having children was often economically beneficial. More children meant more help with the family's work: more hands to work on the farm or make the pottery or whatever. But in modern society, most people don't own a business and so they work for someone else, and child labor is illegal so they can't send their kids to work to bring in income. So children are an economic burden rather than a benefit.
Idea #2: Encourage entrepreneurship, and make sure the law allows people to use their children to help with the business with few restrictions. If people have home businesses where children bring in money, they have an incentive to have more children. Loosen child labor laws and eliminate barriers to children earning money. Presumably you don't want to produce more children only to have them all die in factory accidents, but make it easy for young teens to get paying jobs. Abolish the minimum wage. Bring back apprenticeships.
For a time children had a lingering economic benefit that you expected your children to take care of you in your old age. But now we expect the government to do that.
Idea #3: Abolish government-funded retirement plans. Re-establish the idea that when you are to old to work, you should move in with your children and have them take care of you. Then people have an incentive to have more children in the hope that at least one will be willing and able to care for them in their old age.
Idea #4: Make it easier to have children and harder not to. Make contraceptives illegal or expensive, while making maternity care cheap and easy to obtain.
Of course people respond to incentives other than money. You need to work to make people think of having children as something positive of itself.
Idea #5: Produce books or movies or holodeck programs or whatever entertainment your society has that builds up the joys of family. Some can be overt: like make dramas about young couples who have fertility problems and they are heartbroken that they cannot have a child and then finally the doctors find a cure for their problem and they have a baby and they are overjoyed and live happily ever after. Have stories where a woman struggles whether to get a career or have children and stay home to raise them, and in the end she decides to have children and this is clearly portrayed as the best choice and a happy ending. But be sure to include plenty of more subtle pro-children messages. Like the action hero fights the villains and saves the day, and then at the end he goes home and hugs his children and he tells his wife that winning these great battles is exciting and important but his real joy is the family. Have quick, throw-away scenes where characters praise a woman for having a lot of children or express jealousy that she has more children than they do, and then get back to the main plot. Or have characters express surprise that someone doesn't have children. Have a character sneer, "Bob doesn't have any children -- I guess he's just not man enough to get a girl pregnant." Instead of comics telling jokes about race or politicians or whatever, have a major subject of ridicule be people with no children. Etc. Use fiction and literature and entertainment to create an assumption in society that more children is good. Get people thinking that EVERYONE wants to have children, and if you don't, there's just something odd about you.
I guess a lot of this depends on what the people with this agenda control.
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Earth has been in the middle of a population boom since about the 1960s. It took until about 1800 for the first billion people and now we add a billion about every 12-14 years. We're so good at making more humans we're fighting to slow down population growth, but this is a very recent thing in human history. How did that happen?
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Years
Passed Year Billions
- 1800 1
127 1927 2
33 1960 3
14 1974 4
13 1987 5
12 1999 6
12 2011 7
14 2025* 8
18 2043* 9
40 2083* 10
```
The basic equation is deceptively simple: increase birth rates, decrease death rates. But it's not quite that simple. And it's more important to decrease death rates, *and when they die*. This is all about increasing the fertility of the population. You do that by...
## Decreasing child mortality.
It doesn't matter how many people are born if they die before they become adults and have kids of their own. In the Middle Ages this was anywhere from 30 to 50%. In 1915 in the US infant mortality was at 10%. Now the worldwide average is more like 5%.
[](https://i.stack.imgur.com/oXgCO.gif)
# Decreasing maternal mortality.
Historically, childbirth is one of the most dangerous things a woman can do. In the Middle Ages the cause of death for a woman would be child birth, or associated complications and infections, about 20% of the time. In the US in 1900 this was still high at 1%. In some parts of the world today it's still at 15%. Since the number of women is the limiting factor, it decreases your breeding population if they're dying during birth. Now, in the US, it's practically 0.
[](https://i.stack.imgur.com/I9fSd.gif)
# Decreasing poverty.
>
> The risk of a woman dying as a result of pregnancy or childbirth during her lifetime is about one in six in the poorest parts of the world compared with about one in 30 000 in Northern Europe.
>
>
>
*Source*: ["Maternal mortality: who, when, where, and why"](http://www.sciencedirect.com/science/article/pii/S014067360669380X)
The single biggest cause of death is being poor. It decreases your access to medical care. It reduces the amount and quality of food you have. It increases stresses on your body, the amount of toxins you're taking in, and so on. Child mortality rates are 2 to 3 times higher in the developing world than the developed world.
# Increasing the food supply everywhere.
Can't have kids if you can't feed them. Gotta feed all those people. More food means cheaper food means more calories for everyone. More calories means healthier people having healthier babies who will live to have healthy babies.
Part of our current population boom, and abundance of food, is due to the [Green Revolution](https://en.wikipedia.org/wiki/Green_Revolution). The development of cheap, industrially produced fertilizers and pesticides, plus changes to how we manage our crops and what crops we were growing, in the early 20th century saw a huge increase in farm productivity in rich nations who had the money and industrial capacity to support it. Later in the 1930s to 1960s a concerted effort was made to make the same technology available world wide. The result was a huge boom in the global food supply.
# Discouraging industrialization.
When everything had to be done by hand, people traditionally had big families with lots of children because they needed a lot of people to work the farm. Someone has to feed animals, milk the cows, plant the crops, til the soil, mend the fences, go to town, shoe the horses, etc... etc... etc... The more children you had the more land you could work. The more land you could work the more crops and animals you could grow and sell. People will naturally want bigger families.
Once you industrialize you have machines for all that. You need less people. You have smaller families. The birth rate drops.
# Having a Prolonged Period of Peace.
The unprecedented era of world peace (nothing on the scale of the world wars), global cooperation, and trade we've enjoyed since 1945 added to the population boom.
Modern war means sending your young generation are soldiering, not working or having children. It means diverting your food and industrial output towards warfare. It means wrecking your infrastructure. This all leads to a lowered standard of living for the civil population. Less food, less prosperity, less young people of breeding age, this all means lowered birth rates, and higher child mortality rates.
# Sources
* [Life Expectancy In The Middle Ages](http://www.sarahwoodbury.com/life-expectancy-in-the-middle-ages/)
* CDC, [Achievements in Public Health, 1900-1999: Healthier Mothers and Babies](https://www.cdc.gov/mmwr/preview/mmwrhtml/mm4838a2.htm)
* [The Medieval Child, Part 3: Surviving Infancy, Page Two](http://historymedren.about.com/od/medievalchildren/a/child_survival_2.htm)
* The Lancet, [Maternal mortality: who, when, where, and why](http://www.sciencedirect.com/science/article/pii/S014067360669380X)
* [Causes of death to women of reproductive age in two developing countries](https://www.researchgate.net/publication/226508104_Causes_of_death_to_women_of_reproductive_age_in_two_developing_countries)
[Answer]
Methods:
* tax incentives (bonuses for high number of kids, punitive taxes for not having kids or not being married)
* generous childcare services and safety net (actually judging from EU experiences it seems more cost effective than just money incentives)
* poor access to abortion or contraception (it may sinful, immoral or just hard to buy)
* high status of women who give birth to new citizens (actually simpleton Sparta kept them in higher esteem than seeming enlightened Athens)
* subliminally propagated cultural norms (like showing on TV mostly big families)
* give your soldiers a holiday to have a time to impregnate their wife (I would not say which country tried this, I would just say that their project to have a thousand years empire failed pretty quickly...)
* policies directed at having multiple kids, who not necessary would be raised by their mother (like Lebensborn, but in more modern setting it may involve in vitro and surrogate mother-ship)
[Answer]
Please, respect women, don't view them as just child-producing factories, and don't expect them give birth to >10 children (it's unhealthy, after all). But 4-5 children per woman is realistic, under right circumstances.
1. Group marriages. It's easier for 6 parents to raise 15 children than for 2 to take care of 5.
2. Make the culture more child-oriented. Let it picture children as the most perfect/beautiful/etc. of everything that exists in this universe.
3. Religion. Let them worship a deity that looks like a human child. Also, some cultures in our world have a cult of ancestors, but your people can have the opposite -- veneration of descendants.
4. All that has already been said about the social benefits, better healthcare for pregnant women, etc.
5. The last, but not the least: all those prohibitions (on contraceptives, abortions, etc.) don't work. They have quite the opposite effect: if you are trying to force people do what you want, they will try to escape by whatever way they can.
[Answer]
You've got something mistaken...
Empires would just conscript soldiers and generally war causes babybooms to happen so all you have to do is conscript soldiers and send them out to fight then if they're likely go home to a wife with a child and have plenty more because thats what we humans do.
As for getting people to move you can give people bits of the land they've fought for and you could say that families that move out to the new lands won't be subject to conscription for a decade or so.
[Answer]
For a simple increase to ten children per woman, that's just social manipulation. Just increase infant mortality by taking about two thirds of children at random and shipping them to some other planet. Parents will have more children to be sure two are likely to 'make it'. The Nazi party got about six children per women just through pressure and money.
For higher rates, it gets dicey. Having litters instead of individual children requires many resources and tends destroy the mother's health. Mechanical aids, such as forcing premature births only add a little, as does forcing all women to be pregnant from sixteen to forty. Once you assume in-vitro gestation, the sky is the limit and factories could turn out kids.
Instead of increasing the rate past ten per woman, you could use alien tech to just increase the density. Free energy, food, and building materials could go a long way towards making mile high megacities with a planetary population pushing eighty billion.
I'm a bit unclear why Earth is the only place for reproduction. It does make an odd society if the *all* human babies must be born on earth. Adoption as the norm becomes a thing.
] |
[Question]
[
I have a country, inspired by Edo era where for 2000 years the people lived in a hierarchical society arranged in below classes:
1 Aristocracy - Ruling class, negligible part of population
2 Warrior class - ~8% of the population, they either
* Work in military / law enforcement
* Work privately as guards, cowboys or merchants, but serve as reserve they must train and be ready to join the standing army
if there's war with the neighbors or rebellion.
3 Artisan - ~8% of the population. They live in the cities, not allowed to travel outside of it without permission of the local lord.
Make and sell their wares in their shops and local market. Licensed entertainers and skilled professionals are also in this class.
4 Farmers - Bulk of the population. Must stay in the villages to work the land, not allowed to travel outside of their lord's land.
Sometimes forcibly conscripted into army if aristocracy needs a lot of manpower quickly.
5 Outcasts - ~2% People doing tainted job. Sanitation workers, undertakers, prostitutes, vagrants, criminals.
Most of the time children inherit the class from their parents, but classes are ready to get rid of their worst members,
and are grudgingly ready to accept from other classes if the newcomers are extremely talented.
Marriages between classes are not banned though spouses with equal class and equal profession are preferred.
In short some social mobility exists, both downward: incompetent aristocrat, coward warrior, untalented artisan, lazy farmer,
and upward: lords needs farmers so outcasts are granted land, rich farmer pays for apprenticeship for their talented kid, ...
Is this enough selective pressure to make classes & professions to look different between each other after 100 generations (2000 / 20), similarly to differences between different breeds of dogs or horses?
[Answer]
I also agree with John Dallman that **your conditions are not enough to get the kind of selection you are looking for**. However let me suggest some changes that might achieve what you want.
1. **Reproduction between castes is vanishingly unlikely.** (It's not enough that marriage is unlikely if you race's behaviour is anything like humans.) This means that any genetic traits that arise in one class don't transmit to another. Effective and easy birth control that was usable by either gender might help with this.
2. **A few highly valued traits in each caste.** So valued that anyone exhibiting these traits from a different caste would be instantly snapped up as a mate in the caste that desired them. Or maybe anyone with that trait is adopted into the caste.
3. **The castes are originally different races.** So instead of the Normans invading and conquering Britain, it was the Moors, or North American Indians.
4. **Any child showing characteristics of the wrong caste is immediately killed as an abomination.**
[Answer]
No, it isn't. You will get a tendency for people in the upper classes to be taller and stronger, but that's simply a matter of better nutrition and exercise as children, and isn't genetic.
None of these groups seem to be selecting for a particular appearance, and that kind of active selection is what makes different breeds of dog or horse look different. If your classes were formed from different ethnic groups, from different parts of your world, then the classes could have distinctive appearances, but that isn't the situation you have here.
The need to distinguish people by class is one of the reasons why many societies have had [Sumptuary Laws](https://en.wikipedia.org/wiki/Sumptuary_law). Something like that may provide what you need.
[Answer]
Both John Dallman and DJClayworht make good points, but it's incomplete. As they point out, 2000 years is not enough time for natural selection to change appearance much at all. Artificial selection or selective breeding could do so. If there were strong expectations or prejudices for each group, then social mobility would facilitate the change.
Some prejudices re-occur across cultures: rulers should be good-looking and charismatic, warriors should be big and athletic, artisans nimble, farmers should not be remarkable, and outcasts are often deformed, diseased, disabled, deranged, or just really ugly.
Suppose the ur-ruler in their mythos had curly hair. Who would want to take orders from someone with straight hair or bald? You can go wild with what physical characteristic is associated with which class. History is full of wackyness taken seriously.
On the other hand, 2000 years is plenty of time for the classes to have developed completely different cultures, religions, and languages. That, plus diet, amount of exercise, grooming, and behaviour should make the classes distinguishable in most cases.
[Answer]
Nutrition does this within a single generation, or at most a few. The first two will be tall/muscular in comparison to the others. The outcasts will be diseased (both pathogens and nutritional diseases) and quite possibly disfigured and disabled. Farmers will be shorter (even if they do animal husbandry instead of row crops) compared to those above or to their hunter-gatherer ancestors 5000 years ago.
It's still happening in our own real world even today, though to a lesser extent than in centuries past. Depending on the details of your world, an even starker contrast isn't wholly implausible.
] |
[Question]
[
In the (relatively new) *Star Trek* movie *Into Darkness*, we see Dr. Bones and Captain Kirk in a world composed mainly of red plants. Obviously these are just eye candy with no real basis behind it, but I would like to go further.
***What conditions would be necessary to have plants red in color? Blue?***
---
Some factors I would imagine would be very important in deciding the color of my plants:
1. Sunlight — There a reason our plants here on Earth take most of the warm colors in more efficiently than green light. The color of our sun is yellow. *Would having a green or blue sun impact the color the plants absorb?*
2. Soil content — a shifted soil content might affect a plants color. A common example here on Earth is flamingos. *Obviously* not plants, but the way they change color upon eating large quantities of shrimp is a good example.
Any other ideas welcome to be addressed!
[Answer]
The colour of plants — or any other solar-powered autotrophic lifeform that may or may not be capable of description by the term "plant" — is a function of chemistry and evolution.
Put quite simply, there are only so many viable compounds that allow photosynthesis to take place in a given environment, and they vary in efficiency. Some may be faster than others, some may be more efficient than others, and some may be able to absorb and utilise a greater percentage of the incoming light than others. The latter is defined by colour.
On earth, leaves are green because chlorophyll reflects green light. Green light is a major component of sunlight, and since it is reflected not absorbed, it cannot contribute to photosynthesis. However, it is used by terrestrial plants just *because*. Because chlorophyll was a compound that worked, and it worked well enough, and nothing better came along.
An ideal, theoretical photosynthetic compound would be black, absorbing all of the incoming energy, however this would only realistically be achievable with a suitable mixture of different photosynthetic compounds. A better colour for a photosynthetic pigment on Earth would be red or purple, since the light output from the sun is less intense in these frequencies, but while red pigments such as [phycoerythrin](https://en.wikipedia.org/wiki/Phycoerythrin) might be better, plants simply never used them.
So, you may have almost any colour, as long as its chemistry is feasible and nothing significantly better has appeared in the particular niche of the biome. "It just evolved that way."
[Answer]
The way I am reading your question, you are asking about the mechanism of photosynthesis in alien plants, which would affect the colour of the leaves (or whatever sunlight collecting mechanism these plants use).
On Earth, the primary pigment for photosynthesis is chlorophyll, and green chlorophyll pigments evolved to take advantage of the major component of solar radiation entering the Earth's atmosphere. Around different stars, the plants would preferentially absorb different wavelengths of light. Around a hotter star, plants may look yellow or orange (or possibly blue; reflecting away the more dangerous energetic radiation), while around redder stars, plants might become black. (see: <http://www.solstation.com/life/a-plants.htm>)
Other parts of the plants may still be colourful, in order to serve other purposes. Flowers and fruit are brightly coloured in order to attract pollenating insects, or animals to eat ripened fruit and spread the seeds, so if there are analogues to pollenating insects or mobile animals to spread seeds, then we might expect similar adaptations from the plants. Other colour codes include warnings that certain parts of the plant are poisoned. Other adaptations may be possible depending on the environment and how plants evolve to adapt to them.
Larry Niven popularized the "Sunflower"; a plant with a reflective coating to focus sunlight on a photosynthetic nodule. This might evolve in places where sunlight was very weak. Of course Niven's sunflower also could refocus the sunlight to burn competing plants and even herbivores who might eat the sunflowers. (the scorched plants and animals would die and fertilize the soil the sunflowers would soon occupy...).
Another possible "plant" analogue might exist around a planet similar to Jupiter, with leaves that are metallized and pass through the magnetic field of the primary, generating electrical energy. You might also imagine a "plant" which uses chemosynthesis living near a hot vent under the ocean as well.
Nature will always find a way.
[Answer]
We have red and blue plants right here on earth. China’s Red Sea Beach, Panjin comes to mind: <http://www.grindtv.com/random/chinese-wetland-has-beachgoers-seeing-red/#gEPwaeBVU5cACojl.97>
This red grass, known as sueda (seepweed) remains highly tolerant of the area’s **alkaline soil.** In April at the start of sueda's growth cycle, it exhibits a light red color, then turns green during summer, before maturing to the deep crimson color in September. This might suggest that green plants are better suited for the intense sunlight of summer, but that other colors may thrive in an environment with certain soil compositions and a weaker and more defuse sunlight.
But basically, it all comes down to chlorophyll. Chlorophyll absorbs red and blue light and reflects green frequencies. On early earth, microbes used another molecule called retinal, which reflects red and blue light and absorbs green. (Bacteriorhodopsin is another such molecule.) Some scientists theorize that chlorophyll evolved in latecomer lifeforms that couldn't compete with the retinal using lifeforms, and so evolved to take advantage of the frequencies of light that retinal based life ignored: <http://www.livescience.com/1398-early-earth-purple-study-suggests.html>
Dominant life on early Earth might have been purple with chlorophyll- and retinal-based organisms living side-by-side. Chlorophyll based life won out due to the greater efficiency of chlorophyll over retinal at utilizing its preferred wavelengths of light. One can easily imagine on some distant alien world that its flora evolved another hued molecule, due to local light wavelengths and soil conditions, which sports an even greater efficiency than chlorophyll. Black earth anybody?!?
[Answer]
**Zoochory.**
You have to consider the rest of the life on the planet.
If you can imagine a situation that can cause your animals to ingest and disperse seeds based on colour, then plants red in colour will continue to be distributed.
Perhaps the planet has some really odd limitations around its position to its star, its chemical composition, or its geographical features. It could be such that the water and soil content (which is very red in colour) is healthy for the plant species on the planet.
This could be an initial startup for the phenotype, and it might be sufficient if the soil is such that simply everything that grows there is red in colour.
Once other organisms come along and start dispersing the plants by ingesting them and spreading their seeds, they learn that non-red plants don't have the health benefits. Maybe non-red plants are really toxic because they typically grow in hostile environments but still manage to survive.
So plants that are red in colour are spread more than those non-red plants, leading to a primary plant colour of red on the planet, where non-red is in sparse locations.
[Answer]
re: sunlight — Atmosphere could affect which frequencies of light are more abundant.
re: soil — Oxidized iron is reddish (think of mars) and Bromine is reddish-brown (but is very toxic and doesn't occur much on Earth). An abundance of other elements or compounds might cause a different color.
Other factors that might influence plant color...
* The dumb luck of evolution. (example: A pink bacteria got the first foothold on life and everything else is either bootstrapped from it, and.or it is at the bottom of the food chain.)
* Being silicon-based instead of carbon based. (Not sure what effect this would have exactly. Everything is gray or clearish?)
* World actually created by a mad scientist/wizard.
] |
[Question]
[
The imagined scenario is of a small city built inside of a chasm that draws most of its water from an aquifer or underground river. The place and time in which the scenario takes place is Earth and roughly around the year 2100 A.D. While surface cities enjoy the advanced technology that one would imagine populates the world, this particular semi-subterranean city is an unofficial haven for society's rejects and the disillusioned and therefore lags behind technologically speaking and frequently must rely on primitive forms of tech to survive. That brings me to this question of water wheels. Could waterwheels generate enough electricity to accommodate, or at least fortify as a secondary source, the energy needs of a city of say 50,000? How large and/or how many would be required? Keep in mind the energy would mostly be diverted to growing and maintaining sources of food and vital industry such as medicine and communication. Thank you.
[Answer]
Probably not Roman or post-Roman overshot, breast, or undershot (i.e. classic) water wheels, but what about reasonably modern hydro power installations?
First, you would need to define the energy consumption standard of living of your societal outcasts. If they can live on, say, 20% of the power draw that most of us do (with our computers, lights, electric hot water and heat pumps, appliances, and so forth), you would need something around 200 W per person average generating capacity. Multiply by 50,000 people, and allow for some reserve for peak draws, and you'd need between 10 and 20 megawatts capacity.
This is a pretty small hydro installation by 20th century standards -- one I used to see fairly regularly, [The Dalles Dam](https://www.nwd.usace.army.mil/CRSO/Project-Locations/The-Dalles/) (on the Columbia River that forms the border between Washington state and Oregon for a couple hundred miles) has a bit more than 2 gigawatts generation capacity (about ten times what your chasm city needs if they live in energy poverty, probably more than required to live like Americans do in the 2020s), while [Hoover Dam](https://www.usbr.gov/lc/hooverdam/faqs/powerfaq.html) (one of the largest hydro and water impoundment facilities in the Western Hemisphere) has barely more (a few tens of megawatts) and [Grand Coulee](https://www.nwd.usace.army.mil/CRSO/Project-Locations/Grand-Coulee/) dam (eastern Washington state), one of the biggest hydro generation facilities on Earth, produces about 6.8 gigawatts.
Cave streams exist with plenty of flow and head to produce the needed 10-20 megawatts -- though I doubt you could pull water out of a true aquifer rapidly enough to feed this need. You need to understand the distinction: an aquifer is water "flowing" by seepage through pores and cracks in deep rock or soil, while a cave stream (a true "underground river") is a free-flowing stream inside a naturally formed (or, rarely, artificial) cavern or tunnel; some form as streams above ground and flow into a cave, others form from drip water or springs inside a cave and flow out, and a few flow through natural tunnels -- going from above ground to underground and back to above ground.
Then again, maybe Roman technology (driving modern electrical generators) *could* have done this. There were a lot of water wheels driving various industries -- stone saws, wood sawing mills, grain mills, and textile related machinery -- from at least the Third Century CE. One of these, the Barbegal complex, had [*sixteen* overshot wheels](https://en.wikipedia.org/wiki/Barbegal_aqueduct_and_mills) as well as the machines and shops they powered. Each of those wheels would need to produce about 1.25 megawatts -- or roughly 1500 horsepower -- to give the required generation capacity. One megawatt from water (ignoring the relatively large losses inherent in this kind of water wheel) would require a hundred cubic meters of water per second down a ten meter drop -- or the same product of flow and head. Even a fairly modest stream can do this *if you have enough drop*.
[Answer]
**This is a [Frame Challenge](https://worldbuilding.meta.stackexchange.com/q/7097/40609)**
*The water source isn't the problem, it's channeling that source to a useful location.*
Whether your source is an underground river or an aquifer, it doesn't matter. Frankly, an aquifer is a *much better solution* due to the increase in pressure from its enormous weight and the ability to draw substantially more water from the aquifer than from any underground river.
Some will disagree with this. But I ask you to consider the [Ogallala Aquifer](https://en.wikipedia.org/wiki/Ogallala_Aquifer). With a maximum thickness of [800 feet](https://www.twdb.texas.gov/groundwater/aquifer/majors/ogallala.asp) the anticipated *below ground* pressure of the water *at the aquifer's minimum level at that maximum thickness* is [800 ÷ 2.31](https://www.absolutewaterpumps.com/blog/convert-feet-to-psi/) = 346 psi. For ccomparison, the water pressure at the base of the [Hoover Dam](https://www.usbr.gov/lc/region/pao/faq.html) is only 312 psi. Add to that the reality that one could tunnel and extract hundreds of millions of gallons of water a day from a large aquifer like the Ogallala1 — but a river can only disgorge as much as flows.
What does this mean? The Hoover Dam supplies enough electricity for [1.3 million people](https://www.ktnv.com/news/drought-crisis/lower-water-levels-at-lake-mead-mean-less-electricity-from-hoover-dam). The Ogallala Aquifer, *if you're tunneling below it,* can supply that much *just from one section of the aquifer.* It can supply everything you need.
**But where does all that water go?**
*That's your problem.*
It's not the existence of water that generates electricity, but the flow of water. And that means *the water must go somewhere.* There are high altitude aquifers in the world (e.g., the Lhasa River Basin) that could be used as examples of an underground city drawing power from an aquifer or river and then disposing of it into the sea. As I said, a river already has an exit. But if you're using an aquifer, you're tunneling... somewhere....
So...
* Use an aquifer, which could provide every joule of energy your underground city could possibly need, but you'll need to invent/create/explain/ignore where the water goes.
* Use a river, which disposes of the water for you, but could limit the amount of energy you need for your city.
**Conclusion, and to answer your question**
YES! You can use either an underground river or an aquifer to power your city. Heck, all you really need to do is tunnel 500-1000 feet below the water source then dig a big old hole from your power plant up to the source. Instant power and a lot of it. You already have the ability to dig out the city, so digging out the vertical source shaft shouldn't be too hard.
But unless you want to ignore the issue (which you can, stories aren't required to explain everything and, frankly, not that many people would think to themselves, "Huh, I wonder what they're doing with all that water?"), you need to care about how you dispose of the water. That's a bigger problem than generating power from it.
---
1 *Which is what we're already doing with the millions of wells we've dug to the Ogallala. In fact, we're draining it quite a bit faster than it can recharge. Getting water out of an aquifer isn't the problem if you dig enough wells. Getting the water back in.... that's the problem. But we'll ignore that today.*
[Answer]
Aquifer has no usable potential energy. Underground river unlikely to have much of a flow but if you have it, water has the way out without filling up your big cave, so you can just drop any water on the surface above you city (e.g. usual river) into a hole, use the energy, let it flow to underground river. Amount of energy depends on how deep you are and how much water your underground river can carry outside.
50k is not a small city. You would need at the very least half an acre of land per person for agriculture, 25k acres, 10x10km, (6.3x6.3 miles). All this land needs rather intensive work and light, at the levels the Sun provides. It would require huge amount of energy. Technologically making a cave of such size, watering and lighting it would be a rather daunting task. If they pull this off, they likely have better tech than 95% of the people who has it easy on the surface.
They could use geothermal energy though. Or a "primitive" nuclear reactor.
] |
[Question]
[
We all know that the key to worldbuilding is designing the right kind of the toothpaste tube. Terra is enthusiastic about fossil fuels, plastic, single-use wastemaking packaging, but this world I am building is not.
Fossil fuel/plastic isn't hardly a thing here. Canvas carrier bags. Wood furniture. Woollen coats instead of polyesters. Wood-and-stone houses instead of concrete. Instead of plastic bottles, you fill [this](https://i.etsystatic.com/27603878/r/il/ed6175/2891551411/il_fullxfull.2891551411_q6yw.jpg) up at the well or fountain. What I'm saying is that sundries are built of natural materials, mostly built by craftspeople rather than factories.
So what's a toothpaste tube made out of that avoids waste (is *reusable*) and is manufactured without industrial chemistry?
One thing I found was the syringes in the picture below, which your village glassblower could make for you, and you could top up with toothpaste every time you run out –
[Answer]
**Let's start with a definition of Solarpunk**
>
> Solarpunk is a literary and artistic movement that envisions and works toward actualizing a sustainable future interconnected with nature and community. ... As a science fiction literary subgenre and art movement, solarpunk works address how the future might look if humanity succeeded in solving major contemporary challenges with an emphasis on sustainability, human impact on the environment, and addressing climate change and pollution. Especially as a subgenre, it is aligned with cyberpunk derivatives, and may borrow elements from utopian and fantasy genres. Solarpunk can risk being greenwashed through aesthetics that give the appearance of sustainability without addressing the root causes of actual environmental issues. ([Source](https://en.wikipedia.org/wiki/Solarpunk))
>
>
>
What do I learn from this?
1. We're looking for something sustainable.
2. We're looking for something that binds the user to nature and/or community.
3. The solution reflects solving today's problems, notably human impact on the environment.
4. We're specifically trying to avoid looking sustainable without addressing a root cause of environmental impact.
**Let's ask ourselves what the environmental impacts of toothpaste tubes**
>
> Toothpaste tubes cannot be recycled in a single stream, or mixed recycling bin that is typical for most recycling services. The reason is that toothpaste tubes are made from layers of plastic and aluminum, and items like that with more than one component are difficult to recycle. ...
>
>
> My basic question was, what is the environmental footprint of toothpaste? I wasn't able to find all the information I was looking for, but, being a former lab-rat, I love breaking things down and analyzing them, so I filled in the gaps for myself. I'm sure it's not perfect, but it will give you an idea, and hopefully inspire you to switch to tooth powder. ...
>
>
> Toothpaste Tubes Increase Our Carbon Footprint by 3.5 billions tonnes of CO2 annually. ...
>
>
> Toothpaste tubes also waste toothpaste. You literally can't squeeze it all out of there. On the internet, the average waste cited is about 5% of the toothpaste. ...
>
>
> Tooth powder has no water in it, while toothpaste contains 20 - 40% water. This increases the carbon footprint of transportation by about 30%, just to transport it from the factory to the store. ([Source](https://www.aspirecolo.com/post/carbon-footprint-of-toothpaste-tubes))
>
>
>
*Full disclaimer, that site is kinda self-serving as they're selling tooth powder in what they claim are reusable containers — [some of which are plastic](https://www.aspirecolo.com/online-store/Tooth-Powder-c72290165). Still, when you read through it, the author of the article was thorough if not perfectly scientific.*
**OK, what can we do to believably use toothpaste in a solarpunk world?**
* We're using a powder. The argument about reducing weight in transport by removing the water at the manufacturing plant and adding it at the point of use is compelling.
* From that same point of view, we're looking for a light shipping container. Plastic is definitely light, but plastic has a high cost for pollution and disposal. We're looking for a light reusable container that can hold powder, and when it does need to be replaced, it's disposal footprint is really small. I'm thinking [Xiangxi bamboo weaving](https://news.cgtn.com/news/3d3d414d3045444d30457a6333566d54/index.html), which is good enough to hold water. So long as the powder itself doesn't have a consequence ([most toothpastes do](https://www.sierraclub.org/sierra/2020-2-march-april/ask-ms-green/there-eco-way-brush-my-teeth), so powder can, too, but we'll ignore that for this question), bamboo is about as environmentally cheap as it gets.
I believe the use of woven bamboo to hold tooth powder meets all the identified requirements for Solarpunk. Wholly natural to grow, no heat required to gather, process, or manufacture, and when disposed of it's 100% biodegradable in a short period of time.
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[Collapsible tube containers](https://en.wikipedia.org/wiki/Tube_(container)) were invented in 1841, by [John Rand](https://en.wikipedia.org/wiki/John_G._Rand), an American painter; the point being that they don't need modern plastics. They were made of zinc, or tin, or lead, sometimes with an internal coating of beeswax. Toothpaste sold in such collapsibe tin tubes was introduced in the 1880s.
Before that toothpaste came, sometimes, not often, in something like a syringe made of tin. Never glass.
But the most common containers for toothpaste before the invention of the collapsible metal tube container were [small metal boxes](https://commons.wikimedia.org/wiki/File:Nivea_1924-2010.jpg) or tin cans. (Similar to those in which Nivea cream is sold to this day.)
Before that, toothpaste was not really a thing and people used [toothpowder](https://en.wikipedia.org/wiki/Dentifrice) which came in any random kind of container.
Good luck with making glass or smelting metals without using fossil fuels or burning all your forests. Glass making and metal smelting are very energy intensive.
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**Instead of toothpaste, use toothsoap.**
Rather than a paste or powder that needs a container, formulate your tooth-cleaning material such that it's solid before being used. Slice it into rectangles and wrap it in paper or whatever else is convenient. When you need to use some, use the toothbrush (possibly with water) to scrub a bit off.
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Any item that people use for a long time, is very likely to be ornately decorated and embellished. Whether by holder themselves according to their taste, or they received it from someone special and it serves as a reminder to them, or memory of some achievement, or any kind of meaning. So I believe the answer to "what would X look like in solarpunk society" must include this. Not have the same bland throwaway design we are used to in our consumer society, except with sustainable materials.
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I am looking to write a story where part of the [Atlantropa](https://en.wikipedia.org/wiki/Atlantropa) project goes through. Now I know about all the issues with it: the soil is covered in salt and unusable, it raises sea level in other places, makes existing coastal cities landlocked…
But my question is different. I am wondering if it would be possible to achieve some of the effects of the planned project (i.e. lower the Mediterranean by several meters) by placing a dam between the Mediterranean and the Black Sea, but not at Gibraltar (on account that it is too big of a dam to build — in my scenario they begin building it but never manage to finish it).
I guess it's a difficult question to answer, but some people might know more about the hydrology of the Mediterranean than I do.
Thanks a lot for the help!
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According to the [information](https://en.wikipedia.org/wiki/Black_Sea#Hydrology) I can find, the net contribution of the Black Sea to the Mediterranean sea is about 5000 cubic meter per second
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> The Black Sea experiences water transfer only with the Mediterranean Sea, so all inflow and outflow occurs in the Bosporus and Dardanelles. Inflow from the Mediterranean has a higher salinity and density than the outflow, creating the classic estuarine circulation. This means that the inflow of dense water from the Mediterranean occurs at the bottom of the basin while the outflow of fresher Black Sea surface-water into the Marmara Sea occurs near the surface. The outflow is 16,000 m3/s (570,000 cu ft/s) (around 500 km3/a or 120 cubic miles per year) and the inflow is 11,000 m3/s (390,000 cu ft/s) (around 350 km3/a or 84 cubic miles per year), according to Gregg (2002).
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On the other hand, the net flow through [Gibraltar strait](https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2010JC006302) amount to 0.038 Sv, with [1 Sv being 1 million cubic meter](https://www.traditionaloven.com/tutorials/flow-rate/convert-sverdrup-sv-oceanic-currents-to-m3-cubic-meter-per-second.html#:%7E:text=The%20cubic%20meters%20per%20second,second%20flow%20rate%20unit%20alternative.&text=Sv.,-%3D) per second, thus 38000 m3/s.
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> The net flow through the strait, estimated from the Mediterranean water budget, and the Mediterranean outflow, estimated from currentmeter observations in Espartel sill (western Strait of Gibraltar) from October 2004 to January 2009, made it possible to estimate the Atlantic inflow as the sum of both of them. The obtained mean net flow is 0.038 ± 0.007 Sv, with a seasonal cycle of 0.042 ± 0.018 Sv annual amplitude and maximum in September. The Mediterranean outflow shows a seasonal signal with annual amplitude of 0.027 ± 0.015 Sv peaking in April (in absolute value), and a mean value of −0.78 ± 0.05 Sv. The resulting Atlantic inflow has a mean value of 0.81 ± 0.06 Sv and a seasonal cycle with annual amplitude of 0.034 ± 0.011 Sv, peaking in September, and high interannual variability.
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I don't think that damming the Black sea alone will make a dent in the Mediterranean sea level: the same paper I cited above mentions that the average Atlantic inflow is 0.81 Sv, and that means that the flow through Gibraltar can easily accommodate the missing inflow from the Black Sea, simply by reducing or nullifying the Mediterranean outflow.
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[North Anatolian Fault](https://en.wikipedia.org/wiki/North_Anatolian_Fault) passes straight under the ... umm... strait of Bosphorus.
And the fault is quite active based on the list of earthquakes listed by Wikipedia for the last 81 years. And it looks like [the Anatolian plate is drifting relative to the Eurasian plate at a rate of about 30 mm/year](https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/96JB03736)
Now, a dam over Bosphorus will slowly raise the level of the Black Sea and cause just a wee more water to infiltrate and lubricate the fault. Me thinks that is bound to accelerate a bit the fault movement.
50 years at, say, 50mm/y spells real trouble for that dam.
I wouldn't want to be around when a reverse [Black Sea deluge](https://en.wikipedia.org/wiki/Black_Sea_deluge_hypothesis) happens. because Bosphorus will get deeper and the [outburst flood](https://en.wikipedia.org/wiki/Outburst_flood) will get to take some of the [choked full of hydrogen sulfide mud](https://www.sciencedaily.com/releases/2016/09/160901093155.htm) in the Black Sea.
(image from Wikipedia, [By Mikenorton - Own work, CC BY-SA 3.0](https://commons.wikimedia.org/w/index.php?curid=12769153))
[](https://i.stack.imgur.com/Nfu8C.jpg)
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It is very obviously impossible to lower the Mediterranean to any significant degree as long as it is connected to the ocean. [Communicating vessels](https://en.wikipedia.org/wiki/Communicating_vessels) etc.
Yes, stopping the inflow of water from the Black Sea will lower the eastern Mediterranean a little. (The Mediterranean has a water deficit, and average level of the sea decreases from west to east.) As it is, the eastern Med is about 20 cm lower than the Red Sea on the average; stopping the flow from the Black Sea will make it maybe 25 cm lower than the Red Sea on the average.
Fun fact: one century ago the eastern Med was about 50 cm below the Red Sea on the average, and two centuries ago it was 70 cm below the Red Sea. Nowadays, from July to December the eastern Mediterranean is actually some [10 cm *above* the Red Sea](https://www.sciencedirect.com/science/article/abs/pii/S0272771496901602)! (Warning! The link goes to ScienceDirect. Better open it in a private browsing window.)
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Scenario: in the not-so-distant future, someone(s) crack the code to the human mind. Essentially, humanity now has the power to treat the human mind as computer files - copy, delete, modify - all in the hands of a skilled professional, of course.
I'm thinking less like [Altered Carbon](https://en.wikipedia.org/wiki/Altered_Carbon) and more like [Dollhouse](https://en.wikipedia.org/wiki/Dollhouse_(TV_series)) (spoiler warning for the Wikipedia article if you didn't watch the series) but instead of the technology being secret, monopolized by a megacorp and stretched to all possible limits, discovery was publicly announced and it led to organization and regulation, possibly after a few... unfortunate incidents like all technological advances in history.
A few possibilities of the technology:
* Medical applications: the technology can be used to cure mental health issues like PTSD, extreme grief, schizophrenia - or also *give* people mental issues
* Logistic applications: instead of travelling physically, someone's mind can be sent to the desired location and use another body, or the same person can have their mind copied and be in multiple places at the same time - while useful for busy businessmen, can also be used to commit a series of other less savory acts like espionage, sabotage, even identity theft
* Instant skill mastery: learn anything you want in seconds... for the right price - and this would affect regulated professions such as most health professions (medicine, pharmacy, nursing...), law, engineering
* Memory alterations: want to forget that horrible day / period in your life? Sure. Get new memories of a holiday you didn't go? - that would surely have an impact into law enforcement: how to make sure that an eye-witness' account is legit and not implanted?
* Personality manipulation: someone can be made to be more ambitious, or persistent, or polite, or aggressive, or even a psychopath
* Body hopping / functional immportality: someone short on money can rent their body for someone else to take it for a spin - short (a few hours) or long term (surrogacy will be a whole new process...) or maybe even... indefinitely - which without consent would be essentially kidnapping or murder
How would this technology will be regulated? More specifically, what kind of safeguards would governing bodies put in place? For example, proof of identity - biometrics in this world (thumb, retina, even DNA) wouldn't mean much
Of course there will be people performing illegal activities but that's not the topic for this question
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# What is the *story* you want to tell?
As an author, your first and foremost question must always be: "what is the *story* I want to tell?"
Altered Carbon is not about alien "stack" technology, it is a story about Social Class; what happens when eternal life can be bought by some, but not all; what happens when death becomes a commodity. The "stack" tech in Altered Carbon is not there for its own sake, it is there to enable the *story*.
So, my question back to you is: what is the *story* you want to tell?
Once you have figured out the story, you take this concept of yours, and then you create "problems" with it. In Altered Carbon, the "problem" is that it is prohibitively expensive to re-sleeve. This creates inequity and tension, and in that inequity and tension, the story is enabled.
So now we arrive at your question: what *regulation* will there be?
For that we need to examine the following question: What is regulation, why does regulation exist?
The answer: regulation is — always — a way to *try to solve "problems"*. No-one wants to regulate just for funsies, because regulation means bureaucracy and cost. A cynic might say "well, there you go", but in reality, "no-one" wants to regulate anything unless they have to. And you only have to, if there is a "problem" that needs solving.
* Nuclear power, produces enormous amounts of exergy. Problem: accidents and waste might cause environmental and economical disasters. Solution: regulate safety and waste handling.
* Capitalism, allows persons to forge their own destiny and accumulate wealth. Problem: it can create inequity where the wealthy can use their fortune to exploit the weak. Solution: regulate what you may and may not do with your wealth.
* Non-tangible creations, that can be easily replicated, such as data, music, images, innovations. Problem: as the original creator I cannot monopolize the creation for my own benefit and profit. Solution: immaterial rights regulation, i.e. *copyright*.
...and so on.
So, what regulation will there be? Well, that all depends on what *"problems"* you have with this technology. The regulation will only exist to solve the "problem". And the "problem" — as it stands right now — can only be known by you, since only you know what story you want to tell.
A tip: do not make the regulation too effective, because then the "problem" does indeed get solved, and then you have negated the impact of the "problem".
Also note that "problem" in is written quotes, because one person's problem can be another person's solution; you can have *competing interrests*. For example, copyright is a regulation to regulate an issue that is a problem to some — Intellectual Property piracy — but a boon — free access to culture and innovation — to others.
...and this then harkens back to what I said before: if the regulation is effective, it solves the "problem". For the sake of your story, you might have people that do not want this "problem" to be solved, but instead wants this "problem" to go into full and *unregulated* effect.
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To summarize...
1. Figure out the *story* you want to tell, the obstacles you want your protagonist to overcome
2. Figure out how you need to make this concept of yours *imperfect*, problems with the technology, that enables the story
3. Regulation will be the government trying (and preferably failing to some degree) to *overcome the problem* that you specified in 2.
Good luck. :)
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When I was in college I had a class on computer crime. The professor, a lawyer, explained that in theory we might never need some computer crime related laws. Stealing money is stealing money whether you do it at gunpoint or behind a keyboard. Defamation is defamation whether you do it online or offline. Violating someone's privacy is a crime no matter how you do it. But people created computer crime laws in many countries anyway, because new technologies give new forms to the way people break the law and the impact they can have.
Same thing here. The technology you describe can lead to new forms of torture, data theft, privacy violations and impersonation in the very least. So first things first, legislation would be drafted and passed regarding punishment for people using this technology with malicious intent.
After criminal laws, societies will discuss fair use. Is it fair for someone to use this technology to pass an exam? Can a company force its employees to undergo training by downloading stuff into their heads? If so, how much of that info belongs to the company, and does the company have the right to delete that info if the employee is fired or quits?
These kinds of questions get political really fast, so I am not going to discuss those. Just consider that different places will have different views about those, and within modern democracies instances (and therefore laws) on each topic may alternate fast and drastically.
Finally, once fair usage laws are in place, last thing to do is regulate access to the technology. If it takes a lot of skill to fiddle with a mind without killing or permanently harming the patient, a professional should need a license in most countries. Government backed associations may form around this, which will regulate what training is needed and how certifications are handled and maintained.
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**If the tech is perfected nothing can escape the mind-scan. If someone is lying, pretending to be someone else it won’t work.**
Recently played Subnautica below zero, the architect aliens also had similar technology, very cool. Anyway... how do you stop criminals from misusing mind tampering tech? Well as I said if the mind-scan even works on subconscious and repressed memories, there’s nothing you can hide if caught and interrogated. It may become common practice to scan people’s memories at airports or before and after important meetings. The platform may even be so developed that mind-archives might be created to keep track of the individuals and their memories, as insurance against memory loss or to compare their memories to check for inconsistencies.
The movie version of Ghost In The Shell (mediocre adaptation) had concepts like what you proposed in your OP. Hacking into someone’s memories to steal sensitive information can definitely become a problem. I doubt corporations would let their employees walk around with such information. Instead they would probably separate their memories from work from their personal life. That way the boss of a corporation can go to his family while his memories are stored in servers at the company.
There’s the obvious risk of someone breaking in through security and stealing the info, but at least those areas will be the most heavily guarded. There’s also the risk of a Trojan Horse where a person is unaware they’re carrying a device that monitors their memories while they go to work. In that case either a more thorough search is in order or a means to block communication with the outside of a building.
With that in mind regulations should be made with current morality in mind, the technology doesn’t change that it just needs to be taken into account. Medical mis practice will obviously be banned, this includes stealing bodies or memories or giving false treatments. For travelling by body swapping there will most likely be new border crossing fees and taxes depending on how many bodies you have (they love finding new ways to steal our money). Transferring skills that allow to kill will be banned, instead the only authorized non military fighting skills will be those of self defense. Memory alteration will be difficult to regulate because of moral dilemmas, but giving someone a completely fake life might be discouraged, while small details would be acceptable. Body hopping would be treated the same way as inheritance but in reverse.
And yes they will always be crime or exceptional situations that require intense debate and discussion. But as a general rule of though anything that goes against individual freedom and wellbeing will be discouraged.
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You missed another option- multiplicity; where one of “you” can exist in multiple instances, each engaging in productive work at the same time (and maybe some going on vacation), synced back to a “root” mind.
**Legality of Body Hopping**
This technology can be implemented in four ways. One has much fewer ethical hurdles than the other.
* You can body hop and at stay digital, doing whatever you need to do in fused-reality environments that are sourced from camera and sound feeds that are ubiquitously spaced in the real world. Real people with fused-reality equipment in your same physical location can see/hear/speak with you (and perhaps more if synaptic and olfactory senses are part of the experience). There no obvious ethical concerns to this approach, except right-of-way and trespassing.
* You can body hop and stay digital in completely virtual environments, made from the imagination. Legal concerns might be : are virtual-only people “people”, “property”, or “data”. For examples of this: can I delete a whole “city” of these beings? Or power a “person” off without consent, or force a “city” or people through countless disaster simulations, which might be thought of as a human rights problem, if done to people.
* You can body hop into a robotic chassis. The copy of you may be running in a computer physically located on the robot. With a good radioisotope thermoelectric generator (RTG), you could transmit yourself from Earth "rent" a body on Mars, take it out to the wilderness for a weekend excursion. Legal concerns: you might want to make sure whoever owns the robotic unit deletes copies of you after your done, and doesn't do any snooping through your thoughts for passwords, credit card numbers, or other personal info; or misuse your identity in any other fashion.
* You can body hop into a prepared biological body. This is the most fraught with ethical complications. The root of the problem is that any such body is capable of existing as a person. Nevertheless, it may be legal in some jurisdictions to body hop -- it will nevertheless be a very divisive political point. Some people will see the act as ethically equivalent to murder, and the only thing that will neutralize that sentiment is a body that is outside of the uncanny valley -- absolutely, unambiguously not a thinking thing (a robotic body).
**Social Impact of Portable, Editable Human Minds**
Let's say you can download skills. You'll be able to do it in one of three ways : (1) "write" the skill to your own unique synaptic wetware, (2) write the skill to a brain/machine bridge (think of it as phone local storage), or (3) pull the skill on demand from the local planetary network (like using an online service).
Schooling will change radically. They may become mere sellers of skill libraries or subscriptions to curated plates of skills.
Schools still might offer in-person services where a teacher shows you how to use your skills, and gives you some in-person opportunity to try it out. For example: you might download anthropology and a few dozen dead languages -- the school may still offer a semester of going out into the field under the supervision of a teacher to put these downloaded skills to work.
**Post Literacy**
Another interesting wrinkle is post-literacy. If we can download skills directly to the brain, or share experiences in video, audio, or direct-to-brain formats, there's a massive decrease in the value of writing and reading.
It's very interesting from a worldbuilding perspective to think of a high-tech society where everyone is, practically speaking, illiterate.
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Why would you think this needs to be regulated and if so, what makes you think it is possible to be regulated?
Some ministers or a president wants to regulate this technology? Just bodyswap them and make them commit suicide.
A lot of governments today have continuos "incidents" were political figures die or dissapear misteriously after saying or doing something they should have not.
Police wants to catch you? Just run away into someones body, what are they gonna do? Kill both of you, even if you are inside the mind of someone innocent? What if they can't even find you?
In my country using drugs is illicit and will get you fined when the law enforcement feels like it , smuggling drugs is illegal and will get you up to 30 years in prison.
Yet I see literal children aged 8 selling drugs.
All regulations can be exploited, all laws can be broken and it's hard already to enforce normal laws today...let alone enforce laws about body swapping and mind controlling superpowers.
For real, if the police can't do anything in my country about children smuggling drugs, what makes you think they can handle superpowers?
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**Legal complications reading and writing brains**
One purpose of law in many modern countries is preserving the citizen's right to body integrity and privacy. No physician is allowed to perform invasive procedures on your body, or connect electrodes and tap your brain for any purpose, without urgent medical reason. Involuntarily being subject to brain reading should be prevented and protected against by law. Devices that do brain reading are to be registered and there should be continuous logging and monitoring.
On the other end of the spectrum, you'll suddenly have means to write brain information as well. Same counts for that: involuntarily being subject to brain writing should be prevented and protected against by law. Misuse must be severely punished. For active brain access, many current inhibitive laws would be applicable as as well: deception, fraude, indoctrination.. and doing psychological damage to the victim (assault). I don't expect brain writing would be legalized any time soon, except for strictly medical reasons.
**Medical applications** - **Memory alterations** - **Personality manipulation**
*the technology can be used to cure mental health issues like PTSD, extreme grief, schizophrenia - or also give people mental issues (..) want to forget that horrible day (..) someone can be made to be more polite (etc)*
An important consideration is ethics. Doctors want to help real patients. But that does not mean they should help to *remove* e.g. gender change wishes, or sexual preference. I think the use of this technology should be allowed only for adult subjects, not for children. The subject whose brain is changed should be made 100% responsable - black on white legal document preferably - to allow for such treatment.
**Body hopping** - **Logistic applications:** *instead of travelling physically, someone's mind can be sent to the desired location and use another body, or the same person can have their mind copied and be in multiple places at the same time - while useful for busy businessmen, can also be used to commit a series of other less savory acts like espionage, sabotage, even identity theft*
See initial remark. Doctors need formal approval from *both* subjects, before the procedure is done. Also, both subjects must agree, in writing, on a fixed date, where the body swap will be *undone*. It can't be done quickly, for commercial reasons as you seem to suggest. There is no time for the neccesary legal paper work involved in this.
**Instant skill mastery**
*Learn anything you want in seconds... for the right price - and this would affect regulated professions such as most health professions (medicine, pharmacy, nursing...), law, engineering*
Dream on. Nice *to be able* to do that, but again it involves a brain writer device, which has to be certified under law and is subject to restricted purposes. Any commercial application of brain writers, rather than a medical purpose, should be prohibited under law, to prevent misuse by employers !
**Functional immortality**
*someone short on money can rent their body for someone else to take it for a spin*
You could end up with laboratories filled with spare brains of their customers. Once these brains are read and copied, they serve no purpose anymore. Eventually, these brains would pose a serious legal challenge. Where are the subjects gone ? When there has been a swap, the poor person's brain needs to be stored, else the donor would die. Do these donor brains have any legal responsabilities left ? Suppose the buyer is a weak old man, he buys the body of a strong man and kills someone.. would the donor be partially responsible ? his fingerprints are on the baseball bat.. and without his new body, the murder would not have happened. And on the other side, how would civil rights be applied to all these spare brains.. is a person only existing in a bottle in a fridge entitled to legal protection.. or could the laboratory simply decide to clear out their spare brains, on a regular basis ?
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For an alternate Earth I am trying to develop a type of flying creature which poses an unusual threat model for the unaware explorers wandering in their habitat: when the creature is flying above 10 meters of height and does its business, its droppings can knockout a human who happens to be with their unprotected head on the path of the thing's free fall.
I know that blows to the head can rather easily send someone unconscious, but I am not sure that a creature which can achieve it with its droppings can also be able to fly.
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The ‘knockout’ is really caused by a skin-contact neurotoxin.
This bird has quite an effective self defence strategy. When startled it flies away while simultaneously doing it’s business (as many bird species do). It’s faeces, however, contains a neurotoxin which can cause a range of effects from sudden death (in small predators) up to mere unconsciousness or partial paralysis (in humans and the like). The bird’s cloaca is designed such that a panicked flight will spray this paralytic agent behind the bird as they flee.
The effects are generally temporary, but an unwary explorer that wipes away a blob of bird droppings will find themselves waking up sometime later with a numb hand and a powerful headache.
Explorers unlucky enough to startle a flock of these birds usually die when their diaphragm stops moving.
I’d expect these birds (certainly the males) to exhibit [aposematism](https://www.wikipedia.org/wiki/Aposematism) and have highly specialised predators.
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Aeschylus (c. 525/524 BC-456/455 BC) was a famous Greek playwright with an allegedly bizzare death.
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> In 458 BC, he returned to Sicily for the last time, visiting the city of Gela, where he died in 456 or 455 BC. Valerius Maximus wrote that he was killed outside the city by a tortoise dropped by an eagle (possibly a lammergeier or Cinereous vulture, which do open tortoises for eating by dropping them on hard objects[24]) which had mistaken his head for a rock suitable for shattering the shell.[25] Pliny, in his Naturalis Historiæ, adds that Aeschylus had been staying outdoors to avoid a prophecy that he would be killed by a falling object.[25] But this story may be legendary and due to a misunderstanding of the iconography on Aeschylus's tomb.[26]
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[https://en.wikipedia.org/wiki/Aeschylus#Death[1]](https://en.wikipedia.org/wiki/Aeschylus#Death%5B1%5D)
So if the fictional birds fly high, especially a lot higher than 10 meters, anything heavy and hard it drops could kill someone. I note there is not much difference between the force necessary to knock someone out and the forece necessary to kill someone.
I remember a grove of black walnut trees over 100 feet tall. I imagine that any walnuts which fell from the top during walnut season, or any branches which broke off from the top when it was windy, would hurt a lot if they hit anyone.
So manybe these birds eat some sort of large fruits which have large, indigestable seeds the size of black walnuts, and don't digest the seeds but pass them out in their poop. And maybe the birds have a way to aim and expell the seeds with great force.
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**Unconsciousness process**
Unfortunately this is too long to be a comment on the answer of M. A. Golding.
**Impacts to the head, concussion and unconsciousness:** As Trioxidane noted in a comment on the question, Hollywood gives a very misleading view of how blows to the head turn out. The first concept to look at is how a concussion is caused. In non-technical terms, it is the brain getting bounced around inside the skull. Due to the spine not compressing very well, this does not happen much as a result of blows from above that strike the top of the head, as PcMan related anecdotally. Impacts from this angle are most likely to have either minimal effect or fracture the skull and cause a serious and possibly fatal brain injury (but not necessarily immediate unconsciousness). (Fortunately PcMan suffered the former and not the latter.)
In order to maximise the chance of bouncing the brain around (ie causing a concussion), the head needs to be accelerated forwards, backwards or to the left or right. [This article](https://news.stanford.edu/2015/01/06/measure-concussion-forces-010615/) suggests that impacts from the side are more likely to cause a concussion than impacts from the front or back, although the data at the time was suggestive rather than conclusive. What this means is that if a bird's biowaste projectile is going to concuss rather than either annoy or kill someone, the bird needs to be flying very low and very quickly so that sideways rather than downwards force is delivered to the head.
(Note that even with ideal concussion-producing conditions, only 1 in 10 concussions results in noticeable loss of consciousness.)
The next part is looking at how much force is required and how it is delivered. Googling "speed of MMA punch" throws up a few results - I'm going to cherry pick a conversation in which an unnamed study apparently found 9.14 m/s and round up to 10 m/s. Let's say that the arm throwing the punch masses 4 kg (ignoring the body behind it), so we're looking at kinetic energy of 200 J.
10 m/s is a pretty puny airspeed but 4 kg is a massive amount of bird doo doo. Let's double the speed - giving 4x the kinetic energy, which brings the payload mass down to 1 kg. For a really big bird this is vaguely believable - the ostrich loses only 2.3 L/day of water through evaporation, urine and feces under harsh conditions, but that is enough for 1 kg fecal bombs. Assuming that the fecal matter has the same density of water and is spherical in shape it is roughly the same size as a fist, so there are no concerns about overpenetration.
There it is - an at-least-ostrich-sized bird with a decent horizontal airspeed (72 km/hr) that flies across rather than along paths (if any) to release big droppings. Without vast numbers of really big birds the risk of being struck would be very low, so presumably this is deliberate behaviour used to hunt or drive off intruders in their territory. There would need to be a reason for evolution to favour horizontal bombing runs over the more easily aimed dive bombing technique. Perhaps it is used to strike intruders who have taken cover under trees or rock overhangs.
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Your bird is simply huge.
The upper estimates for the [Quetzalcoatlus's](https://en.wikipedia.org/wiki/Quetzalcoatlus) weight are around 250 kg. A beast that big might feasibly drop a pound of dropping at you from above. At terminal speed, and depending on what the beast ate, that would be like taking a coconut to the noggin'.
Mythical fauna has larger birds yet, such as the [roc](https://en.wikipedia.org/wiki/Roc_(mythology)). The opening image in the wiki shows a roc, which looks like an eagle, carrying an elephant in flight. If such a bird decided to drop on your head, you'd be dead.
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Perhaps the bird eats minerals from cliff faces to aid in digestion(or maybe to get salt). The small rocks it eats get lumped in with the rest of its waste, and when it defecates it drops a part-rock part-waste bomb. Additionally, maybe the bird values water, so in its digestion it removes most of the water from its waste, further hardening and turning it into a rocky mortar perfect for breaking necks.
Finally, the bird wouldn’t have to be that large to have deadly poops. A bird a hundred pounds in weight, well under the historical record, could produce 2-3 pound poops. From 100 feet up, a rock-sludge ball of that weight could easily kill or maim.
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My story, set in 1990, has secret societies of immortal beings (vampires, werewolves, elves, leprechauns, etc.) living amongst the human race and trying to survive while remaining a secret. One idea about this world that I've had for ages is the concept of "grades" of magical blood, both in the immortal beings and in the human stock they mutated from. There are four grades, in increasing order of power and rarity: gamma (60% of the human population), beta (30%), alpha (9%) and cambion (1%). The higher your grade of magical blood, the more of your race's powers and the fewer of your race's weaknesses that you have. If you're a human, your blood grade is randomized at birth, basically completely irrespective of what grades your parents were. However, if you're an immortal, the grades of your parents *are* taken into account, and due to how it works, it'll most likely be the lower grade between the two. For example, a cambion immortal with an alpha partner has a 1 in 10 chance of having a cambion child, with a beta partner it's 1 in 31, and with a gamma partner it's 1 in 61. In addition, in cases where it's an immortal and a human, if the human is the one with the higher blood grade, it will automatically default to the immortal's lower grade.
This means that the cambion immortals are rare and, crucially, impossible to replace should all of them be destroyed. This has caused immortal species whose cultures emphasize protecting the cambions among their ranks to have a survival advantage, meaning most immortal societies regard cambion life as far more valuable than the lives of lesser blood grades. The way I envision it currently, the culture many immortals are brought up in drives most lower-grade immortals to be prepared to die to protect the cambions among them. A "lowblood" who allowed a cambion to die to save their own skin is regarded in nearly all immortal circles with the same visceral contempt with which a human would regard someone using an infant as a human shield.
Now, obviously, I know enough about history to know that it's *far* from impossible to make people prepared to die in the name of something they perceive as greater than themselves. The issue comes with species like vampires.
See, vampires, like in nearly all popular culture, have the ability to "turn" humans into more vampires. A vampire can't turn a human of an equal or higher magic grade than themselves, so this isn't a way to make more cambions, but it allows them to replenish their ranks extremely quickly as long as the cambions stay alive, and it's a major survival advantage that has caused vampires, along with other races with the ability to "turn", to become the dominant immortal species.
But this means that vampires will regularly be replenishing their ranks with ex-humans who grew to adulthood in a completely different culture that didn't drill into their heads how important it is to keep the species alive at any cost. The entire survival advantage of these turned vampires is the ease with which they can be replaced, but with this ability to turn, most of the "cannon fodder" will be coming from a background that hasn't actually *taught* them to view themselves as cannon fodder.
For vampire clans where this bigotry is overt, on-the-books marginalization of the non-cambions, where failure to do what the cambions say is punishable by death (and the incentive to become a vampire in spite of all this is the general license to abuse your power that these more villainous clans grant), this doesn't matter as much. But if I want to explore this bigotry in a *less* overt fashion, more in the form of cultural values and social enforcement, I'm having trouble imagining how this sort of culture could survive when it keeps getting new members who are naturally inclined to see it as nonsense, and nonsense that comes directly at their expense.
**How can I stop the regular influx of people who weren't raised as vampires from inherently undermining the culture of "species patriotism" among the lower class that these immortal clans rely on to flourish?**
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**Only use Renfields to make vampires**
Vampires in fiction often have mortal hangers-on who are fanatically loyal to the vampire, either out of hypnosis or because they hope to eventually be bitten and turned into one. Renfield from *Dracula* is one of the earliest exampled but there are lots of more recent examples in urban fantasy. The way this usually works in modern urban fantasy is the people serving the vampires do so because they believe they will eventually be rewarded with vampirism and immortality.
The problem with converting random people is not just that they have no reason to abandon their social structure and conform to a foreign group (not just that, but conform to a foreign group where they are at best second-class citizens and at worst slaves and cannon fodder due to the fact that they cannot rise in rank due to blood purity) is that it creates a large, disgruntled underclass who would just love to take the first chance to rebel against their vampire masters. People will often support a corrupt system if they believe that they have some chance to achieve social status within it. It's the "Path to Glory" fallacy. This is why most of the soldiers that fought for the American Confederacy never owned slaves. Or, to use a vampire example, a lot of vampires in setting like *Vampire: The Masquerade* follow the rules because they believe that eventually they can become top vampire.
However, in the case of vampires, there is a big issue in that the disgruntled underclass has a very easy way to screw over the vampire nobility. All they have to do is publicly reveal the masquerade by demonstrating vampire abilities in public to a large audience, like a late-night talk show. They may want revenge on how vampire society treated them, and they will probably be spiteful enough that they won't care that exposing secrecy hurts them as much as it does the other vampires. Notably, in this case threats of violence and killing them won't work because the vampire underclass have nothing to lose, and they are likely to just hide their motivations until it is too late.
The best way to minimize this is by having strict criteria of who gets to be a vampire, specifically valuing loyalty and desire to conform to vampire culture as prime values for a candidate. If only those who are loyal fanatics and complete vampiraboos get bitten, then it dramatically reduces the risk of creating disgruntled underlings.
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It's actually pretty common for newcomers into a culture/religion/organization to be somehow more zealous/radical in their observance of the related norms than those who are born and grown up into it.
Since it has been learned over a shorter time, it's easy to miss some of the nuances of the adherence to a certain set of norms which one develops while growing into it.
The Japanese have a term which translates roughly to "turning into a tatami", to indicate when foreigners living for some time in Japan start taking habits of the Japanese culture which they think are "too Japanese" for a foreigner to embrace, like enjoying eating [natto](https://en.wikipedia.org/wiki/Natt%C5%8D) stirred to make sticky strings.
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Going off of user2352714's answer, what if vampires are capable of blood *up*grading?
In my mind, if a vampire bites you, no big deal. If a vampire drains you of all your blood, *very* big deal, you'll wake up the following night feeling drained and thirsty....thirsty for blood.
Now, perhaps the newly-born vampire is *vulnerable*; perhaps they need to drink enough blood to "refill," so to speak, and they naturally become fanatically loyal to whoever gave them the blood they needed to remain alive and become a true vampire. (They're not a vampire until then; just a 'blood husk.')
If a *cambion* is the one who gives the blood husk the blood they need (the cambion should have extra, having just Husked some poor sap) the result will be a totally devoted thrall. Come on, how can you betray the one who *literally gave you life?*
Additionally, what if the blood grade of the vampire is added to the husks? If cambions are the most powerful of their kind (which I believe is implied in the OP), the end result could very well be an army of thralls far superior to every lesser vampire's thralls.
If it goes vice versa (the husk's blood grade is added to the vampire's,) vampires should soon rise into the ranks of the most powerful magical beings, like dragons.
Even better, this makes it so vampires will A) have incentive to vampirise (or Husk) other people, which will conflict with their need for secrecy and eventually humanity itself, which won't want vampires to take over and B) a simple thrall could eventually become the head vampire!
Anyway, I hope this helps.
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Chivalry. Human societies evolved with a fairly similar issue: men and women could both fight, but only women could replace the casualties of battle. Many societies reacted by protecting (which is to say marginalizing) women from battle and often other roles, and focused on keeping them reproducing. The overall effect was not particularly pleasant for women, and by extension, I would expect that the life of your cambions might similarly be dominated by an imperative to reproduce.
Where things diverge from humanity is that these cambions would be able to reproduce in the absence of all other castes, and the way you describe them, have considerable physical superiority. Given the opportunity, they could completely supplant all the other grades. They might have some sort of Nuremberg laws to keep from "wasting" their reproductive potential with lower castes. They might seek to sterilize the lowest caste and remove it from play entirely, to be followed by the next lowest. On the other hand, physical superiority does not guarantee higher social status! In the early United States, planters in the South would pay a premium for "seasoned" slaves from Africa, who had proved resistant to malaria and were capable of surviving the horrible conditions of labor ... that did not translate, of course, to political power.
Politics is not always tremendously rational, and it is possible that different countries of vampires would have radically different social structures. War between them might be almost inevitable.
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Might be a bit of a cop out, but have you considered magic?
A common vampire trope is that vampires are subservient to the one who turned them, often whether they like it or not. You’ve stated that you don’t want this in your setting (in the comments but not the body of the question), but that doesn’t mean lower-level instincts can’t be imbued.
lIf you frame this power as ‘other vampires want to protect/serve me’ (like ants in a colony don’t directly follow the Queens orders but will die to protect her), then protecting the Cambions is an inevitable consequence
If blood purity gives greater power then Cambion vampires will have the most overwhelming protect/serve aura. Vampires of the same grade as them will resist and act under their own initiative, and alpha vampires will act like loyal retainers/ subjects but those below will become increasingly overwhelmed to the point that low-level vampires in the presence of a Cambion will become fanatically devoted.
Furthermore if you tie this ability to bloodline (so a subservient vampire feels more loyal to their progenitor than another high level vampire) you get the ‘vampire clan’ scenario. Expect lots of backstabbing/political manoeuvring in the alpha ranks to become the Favourite of their Cambion overlord (who they literally *cant* think about deposing).
Of course: if someone didn’t want to be turned there is every chance this mental whammy will just break them, especially if they are low level. At that point they become a mindless thrall, useful only as cannon fodder or playthings for their superiors who have embraced the dark. At that point you get two kinds of vampire: broken thralls and willing converts, either of whom will protect their superiors (and especially the cambions).
Thralls would be the lowest of the low amongst their own rank but could still inspire protective instincts in those below them, and since you want your low level mobs to be focussed on the tasks you’ve given them rather than protecting a broken alpha it makes sense to keep high level thralls in reserve as ‘sub bosses’ or dumb bodyguards to use after the low level cannon fodder is all dead.
After all: your clan-leader can always make more.
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An odd question, yes, but a question I am asking anyway. I have a group of feral cats that lives in a cave system. They've lived down here for generations, and survival of the fittest weeded out the builds that were unlikely to survive. Question is, could cats sustain their basic needs, off of only what is in the caves? These cats are of human intelligence, have extremely primitive technology. As a bonus, you can also add what mutations and genetics would aid a cat in cave survival (Real life mutations and genes).
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With no humans to domesticate, they'll have to hunt their own bats.
Which proliferate by the thousands in caves in many parts of the world.
And fish, which are [common even in deep caves](http://en.wikipedia.org/wiki/Cavefish) with good water systems. There are even underground catfish, and [fish that can climb the walls](https://en.wikipedia.org/wiki/Waterfall_climbing_cave_fish), though these are rather too small to make a good meal.
Some species are blind, living in deep caves without light, so these cats may have unusually large ears, and hunt by the splashes and plops they make breaking the surface.
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I think your cats may can survive by hunting bats, besides I think @L.Dutch may be thinking about deep underground ones rather than caves, beside you say your cave is not blocked, which doesn't mean other animals beside your cat don't go outside to hunt, unless I'm mistaken and it includes other animals too?
Also I have seen feral cats hunt bats many times, even inside caves or usually near the cave's mouth.
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*Human Intelligence* is the most overpowered skill you can give to any animal and it's arguably the most powerful skill ever--it's what's enabled humans to dominate the world. This is why I'd say: As long as it's thermodynamically possible, yes, your cats can survive.
To elaborate: living creatures consume energy, measured (for example) in Calories. If a creature eats more Calories than they burn, they survive. If a creature eats less Calories than they burn, they will eventually die, probably before procreation. This means for your cats to survive multiple generations, you need to introduce energy into the cave system somehow. Some ways this could be done:
* Hunting non-cave creatures: mice or other small prey animals consume food outside, wander into the cave, and get killed and eaten. Requires reliable and high "wandering in" rate
* Farming: certain cave sections have skylights where sunlight pours in. These patches of light are used to grow plants (although I'm not sure if cats would be ok with a strictly vegetarian diet). These plants could also be used as food for domesticated animals, which are eventually eaten by the cats
* Fishing: a surface river goes underground and passes through the cave. The cats can use nets or other fishing strategies to catch aquatic life and then eat it
* Fungal farming: provided the cats have some sort of abundant biomass source, mushrooms and other fungi can be farmed and consumed directly or used to feed livestock. This has advantages because the fungi do not require sunlight.
* Pre-supply: some food preservation methods can keep food edible for a very long, if not indefinite, time. For example, maybe someone stored tens or hundreds of tons of pemmican in the cave before sealing it. This could feed many generations along with possible livestock or fungal farms as desired.
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The food chain inside caves is fed through the few organic matter which drips inside the environment. Therefore it cannot sustain large organisms.
The largest cave organism I recall is a sort of newt, way smaller than a cat. If your cats have to sustain themselves only with what they can forage in the caves they will be forced to scale down to a similar size.
Anything bigger would probably starve.
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The telekinetic in question seems to have fantastic line of sight telekinesis and even great out of sight telekinesis being able to even manage "having a sense of feeling" to said things using his powerful imagination (he's quite the maladaptive daydreamer) however he can't move or manipulate things he doesn't know exist and telekinesis at its best is manipulation of matter that does exist with the mind. For him to know this he needs to have previous experience with said object/area. Bare minimum muscle memory or visually with that object being in his line of sight beforehand to create a "link" to said area or object. It is possible for his memory to be foggy and if he can't remember a area/object well enough he could possibly lose all telekinetic link with this area/object. Meaning if he doesn't at least have a idea visually of your house he can't just levitate your Xbox 3 miles back to his place. So assuming he was familiar with how generally automobiles work and he was insanely familiar with the inner workings of a 1957 Cadillac Eldorado Biarritz how would he go about mentally starting this vehicle without keys and driving off?
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Yes he can start an *old car*. All he needs is to
1. Apply momentum to the keylock
2. Start to vibrate that keylock
That is exactly like how a modern vibro-lockpicks works.
Additionally, if he can work using his muscle memory, he can touch the pins of a lock with a piece of paper or clip and then just push them and turn the lock.
All this needs is that he have at least watched some video on youtube about locks and lockpicking. Better if he has some real experience with it.
But this method has a lot of limitations:
* "secure locks" have protection from this method (so he would have trouble opening safes or secure doors)
* most *modern cars* have additional digital security measures - like the key also being a digital token, and many other more complex systems. So - no luck with cars with a start/stop button!
P.S. (inspired by comments) Or, if you are strong enough, you can just switch the gearbox to neutral and push the car with your own force! :)
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**Use water to feel the inside of the lock**
I presume your telekinetic gets some sensory feedback from the items he moves. For example if he picked up a bed and pushed it towards the wall he would feel he bed stopping against the wall, even with his eyes closed.
So do the same for the inside of the lock. Take a small amount of water and manipulate it inside the lock. Then he can generate a mental picture of the inside of the lock. From there is should be easy to locate the relevant tumblers, pins et cetera and open the lock.
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# No
`however he can't move or manipulate things he doesn't know exist`
The car in question would have to have been manufactured before the implementation of ignition keys. By the rule stated above, the telekenetic can't actuate tumblers he/she can't see (doesn't know where they are, what their settings are, etc.). If the telekenetic is powerful enough to break the lock, he/she's powerful enough to do a lot of things that make the question moot.
Bear in mind that telekenisis is just a form of sci-fi magic. You can do anything you want with it — but by the rules you've established, no, the telekenetic can't start cars.
*A better answer would require you to provide more details about the rules of telekenisis in your world, like a chart of force-vs-distance, rules about precision and dexterity, etc. Most telekenetics in, for example, the Marvel universe are godlike in their ability to perceive their surroundings and therefore utilize their gift. A practical telekenisis would be no more useful than your own hands. If you can't do it with your hands, you can't do it with your mind, because that's as complex as the human creature can be without additional tools.*
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Answer based on an edit.
He would need to watch a few episodes of "[Lockpicking Lawyer](https://www.youtube.com/channel/UCm9K6rby98W8JigLoZOh6FQ)". A 1957 car wouldn't have any additional power security (in the vanilla factory model, at least). If they had, bad luck those things are PITA. First to find, second to operate.
If he has seen the key it would be even easier. He could imagine where the pins should be, and then use telekinesis to hold them all at once.
However, there is a different method at his disposal. Provided that he is familiar with the internal workings of the car, he could just give power to the cable that activates the solenoid that starts the start and give power to the ignition coil (etc. ad nauseam). To simplify, just imagine the red wire touching the pink cable.
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Someone
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> familiar with how generally automobiles work and ... insanely familiar with the inner workings of some pre-1980 model
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... can run this car without the keys AND without any telekinetic abilities. In a few minutes or maybe less. That's how advanced car thieves did work back then.
Telekinesis can shorten this time down to few seconds - in practice, just as fast as with keys.
It boils down to opening the doors (pretty much possible from inside when you see where the handles are from the opposite window and this Cadillac is cabrio anyway) and shorting 2 (and temporarily 3rd) wires that everyone knows where they are.
Steering wheel locks AFAIR were introduced later and they are rather easy to bypass, especially if you can simply undo bolts that you can look at.
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Part of the ignition system of the vehicle is a [relay](https://en.wikipedia.org/wiki/Relay), which is an electronic device that enables a low-voltage circuit (the key switch) to switch a high-voltage circuit (the starter) on and off while keeping them electrically isolated from one another. Relays generally work by sending the low-voltage signal through a coil that acts like an electromagnet. When energized, the magnetic field from the coil will push or pull a switch open or closed, which opens and closes the circuit on the high-voltage side.
To start the car, your character would simply need to use telekinesis to close the ignition relay. It doesn't take much physical force to do this, but the relay's components are sealed inside a plastic shell. Your character would need to swap the relay in his car with [one that had a transparent shell](https://www.aliexpress.com/item/32845450396.html). Once he could see the insides, activating it should be trivial. After some practice, he will likely learn to do it while sitting in the driver's seat and not having a direct line of sight.
If he wanted to make his car really hard to steal, disconnect the key switch entirely and replace it with a pushbutton hidden somewhere inaccessible. The only way to start it would be to press the button telekinetically.
This would be a lot harder for modern cars, though. Their ignition systems are more complex.
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Depends on the vehicle. Modern cars, built since maybe late '90s, have electronic security systems (RFID) built into the key. If the car's ECU (electronic control unit) doesn't read the correct code from the key, it won't let the engine run. If you go to your local hardware store and cut a duplicate key (that is, with the same teeth & notches, but without the code), it'll just unlock the steering column, but not start the engine.
With older cars - for instance, my '88 pickup - you could start the engine by telekinetically picking the lock, just as you can cut a simple replacement key.
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You don't need to engage the ignition system to start a car (at least, a car with a carburetor - I'm not sure how true it is of a fuel injection engine, but 1957 is definitely going to have a carburetor). All you have to do is get the crankshaft turning with enough momentum to cycle a few times. The ignition system just engages the starter, which is an electric motor that turns the crankshaft until the motor gets going.
Cars can be started by "push starting" instead - get the car rolling by pushing it by hand or another vehicle, or just rolling down a hill, then "popping the clutch" to engage the gears. The momentum of the car will start the crankshaft turning, causing the engine to start up.
Your guy does not need to start it in exactly that way. He just needs to turn the crankshaft with his mind. In fact, since you seem to be interested in a particular vehicle, all he has to do is look under the hood long enough to "picture" that big fly wheel in front driving the belts. It is connected to the crankshaft. So all he needs to do is start turning the wheel, and the car will start.
If the car is in park or neutral, then it should start easily. If the car is not, then he will have to start moving the entire vehicle to get it going.
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Star Wars Rebels had Jedi able to do basically the same thing to a door lock by visualizing the mechanism. Is that close enough to what you mean?
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I want to help people to verify they're from future (if they are, of course). For this I publish some facts/numbers on my website, dayly or weekly or whatever, so that a time traveller can remember numbers for the next week and say them to whoever wants proof.
The requirements for such numbers are the following:
1. They should be unified: I don't want to mix it up, so better stay consistent.
2. They should not be about one-time or unique events: while being told that a big robbery is to be commenced next week is an important thing by itself, there might not be any noticed robberies on a given week.
3. They should have a lot of possible values: while "yes or no" answer is as simple as it gets, it's still a 50% chance to guess right. And many such questions are harder to check and easier to mix up. Ideally it's a big number with lots of equiprobable values.
4. It should be unequivocal and easy to check for me: time travel possibility is pretty low, so I can't spend too much time and money if there really is nobody to help to.
5. It should be near impossible to be influenced or changed deliberately: stock prices are varied and are easy to check, but can be controlled.
6. It should be resistant to butterfly effect: true random number generator values and such things are out of questions, because future traveller's arrival might cause them to roll differently.
7. It is a good idea for the number to be easily checkable by others: this means my numbers can be checked and nor me nor anybody else can fudge them.
8. And lastly, it should be impossible to find out or predict or calculate before checking date: obviously, if it is known before check date, we're not checking future knowledge anymore.
Any ideas for something that fits all of these? Preferably not something restricted to our time or our world.
Of course, if you have other ideas on verifying time travellers without numbers or find a flaw in my reasoning, you're welcome as well.
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Stellar, specifically solar radiation.
Get a big telescope and measure solar activity like flares, sunspots, and more. Use some sort of pre-determimed formula to convert your observations into a memorizable string of numbers and publish them to your blog. Now you've got numbers which are essentially impossible to predict (as the sun is such a ridiculously chaotic system) and which are unlikely to be changed by any butterfly/causality effects. If someone is able to predict them or alter the sun significantly enough, you've got bigger problems than time-traveler verification.
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Use a [Cryptographically Secure Pseudorandom Number Generator](https://en.wikipedia.org/wiki/Cryptographically_secure_pseudorandom_number_generator), with a randomly-generated initial seed that you keep secret.
A pseudorandom number generator will allow you to produce a completely predictable sequence of numbers based on its initial seed, so as long as the time traveller's actions don't butterfly the initial seed, the remaining numbers produced are both completely deterministic,and (ideally) not determinable from knowledge of the previous numbers.
Generate one a week, publish it, go about your day.
When someone shows up with a number, if their claims appear to be credible, they can give you a number, and you can generate pseudorandom numbers until the number the one scheduled for the week they came from appears, and see if it matches.
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**Bomb pulse radiation**
Anything born post August 6, 1945, the carbon-14 in the DNA can tell you exactly when they were born, until about 2050. Have them bring you a lab rat from 30 years from today and test its carbon-14 levels. This isn't something that can be faked. In the event that another nuclear event caused levels to change, have the time traveler grab a rat the day before this event then. Realistically, anything greater than a few years in the future will be impossible to recreate.
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I would suggest looking for some inherent "clocks" related to evolution:
1. Their digestive bacteria will likely be insensitive to modern-day antibiotics.
2. Their blood will likely contain [Ig G](https://en.wikipedia.org/wiki/Immunoglobulin_G) to new era diseases (AIDS / MERS / SARS, etc).
3. If we're talking about a *distant* future, then perhaps [mitochondrial mutations](https://en.wikipedia.org/wiki/Human_mitochondrial_molecular_clock) could be detected.
4. If we're talking about a *really distant* future, then would it be possible to detect some [Y chromosome](https://en.wikipedia.org/wiki/Y_chromosome) degeneration?
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Assuming we have a way to generate the numbers, like Dragongeek's answer (solar radiation), the problem is to make sure no-one stole those information, like pointed out by mjt and SRM. This would violate #8 as a fake traveler could find out by forcing a real traveler to reveal information.
# Additional random questions
First I want to address mjt proposal as I don't think it to be viable:
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> The only way around this I can think of would be asking the time traveler questions so arbitrary that nobody would have thought to brief their fake about.
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The problem is that if nobody would have thought about them, then the same can be said for someone that came from a 100 years from the future and didn't thought of researching those things. Anything he could know from his life experience would be too far in the future to be verified, leading to plausible deniability for any fake.
# Characteristic of the body
For this reason I think SRM is right to say that we need to focus on some characteristics of the person to check that it's actually them to have came back from the future. The problem is that it's not possible either.
Many of the following require state-like organizations with a lot of funds. This seems to be within what described by #5. It may be implausible for many scenarios, but it is still be a valid threat according to the question.
## Radiocarbon dating
If you want to fake the concentration of C14 (for [bomb pulse dating](https://en.wikipedia.org/wiki/Bomb_pulse) too as it's always about the concentration of C14) you just need a [closed ecological system](https://en.wikipedia.org/wiki/Closed_ecological_system) able to sustain a human and built with the required initial concentration of C14. It may require some time initially to bootstrap the process, but everything you need it a source of carbon with a the ratio of C14/C12 you want. This can be obtained in at least three ways:
* The first is to use the same [centrifugal method](https://en.wikipedia.org/wiki/Isotope_separation#Centrifugal) used to separate uranium-235 from uranium-238 as their mass ratio is 0.987, while the one of C12/C14 is 0.857. As lower ratio implies a greater difference in mass (more far from 1), this method is viable.
* Using the C14 produced by [nuclear power plants](https://en.wikipedia.org/wiki/Carbon-14#Emissions_from_nuclear_power_plants) as they have a higher C14 concentration. If mixed it can lead to the required ratio.
* Using the carbon from [fossil fuels](https://en.wikipedia.org/wiki/Suess_effect) as they have no C14. This can be mixed too in case you need to lower the amount of C14 present.
What you need for the fake is someone building this thing before the time traveler arrives (you wouldn't have a fake always ready if you build it afterwards). You can use the plants grown within it to feed someone using a vegan diet and the result is that the person in question will have the required amounts of C14. From <https://en.wikipedia.org/wiki/Carbon-14#In_the_human_body> :
>
> Since many sources of human food are ultimately derived from terrestrial plants, the relative concentration of carbon-14 in our bodies is nearly identical to the relative concentration in the atmosphere.
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Which obviously means that if we fake the concentration of C14 in the atmosphere used by the plants we eat, then our concentration of C14 will follow the one of that atmosphere. You just need to eat from that closed ecological system from birth, after all the intake of carbon of humans comes from their food. If the 2° or 3° way to modify the C14 ratio are used then this is not even that expensive, you just have to use waste products.
Using C14 to date things is usually considered reliable because no one has a closed ecological system (even if they exist) with altered C14 (even if it's easy to do) from which they eat since birth. But it can be done in the same way it's possible to control stock prices. If you are the USA, EU or Russia of the past, you would just had to convince the ones who actually build the closed ecological system in existence to use the materials and CO2 you provide them. If they were at war and that could make them win it, it wouldn't be that far fetched of a scenario.
## Identity based
One method could be to exploit the case in which the person who came back from the future was already alive (by comparing with the person already alive). The problem is that it can't be used to roll out fake travelers as the fake one could just say to be from a more remote future (like 30 years for a 20 yo.).
For the fake you just need someone that is either from a state with a loose identification or that was kept hidden by a state for military purposes (you can't control what your enemy state is up to). In this way you can't verify that they were already alive in our time and you need to apply other techniques, bypassing any control and assurance that those techniques may have.
## DNA coding
DNA coding can be replicated too. Overall it's called [gene therapy](https://en.wikipedia.org/wiki/Gene_therapy) and there are already [treatments](https://en.wikipedia.org/wiki/Voretigene_neparvovec) able to change the DNA of a part of the body, with the change taking place within the body.
Overall if a state wanted to create a fake time traveler using the information of a valid one they could just apply to many people the best treatment known, possibly multiple times to make sure all cells are affected and use the best fake. But even if not fully possible, this would heavily restrict this idea to the present day. Considering the current developments rates, in just 10 years this technique would become rather unreliable.
## Numbers for 20 years
If the time traveler wanted to makes sure to be identified even if he get arrested and released after a while, he may want to remember a set of numbers for some of the following years. Maybe he thinks that he will be asked to be identified multiple times or just to be sure in case something happens. The problem is that we can't control or check that they didn't remember additional numbers, so this scenario applies to any method used to prove that a certain person is a time traveler.
The problem is that this would tremendously ease whoever wants to create a fake as it'd be possible to engineer a fetus and his growth environment to reach the required characteristic. This may have severe ethical problems, but if we are talking about states under war that think they can use the fake information to win the war, then it wouldn't be such a far fetched possibility and needs to be considered and you can't make sure that your enemy state didn't use it.
## Any not-currently-known technique or scientific knowledge
Lastly even if we find something different from DNA and C14 that we can't currently do (but we have reasonable certainty that it can be used to identify the body of a time traveler), it would still be not viable, as pointed out by Максим Корчагин under an other answer:
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> Scientific discoveries definitely fall under #2 and #8(because the time between actual findings and theory being published might be quite big).
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And in this case we would be using a scientific or technological discoveries to satisfy #8, which wouldn't comply with OP.
# TL;DR
To conclude neither information, objects (can be stolen) or characteristics of the body can be used to guarantee that a certain person is from the future as required by OP, unless we ignore stealing information from an actual time-traveler.
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To answer your question we have to assume some rigid variables in the test.
1) We are only verifying a short trip to the future. Anything longer will leave too many options for fraud.
2) All players are known and will be available for the duration of the test from start to finish.
3) The exact conditions of the test will not be revealed to the participants until the test is underway.
The test will require two time delay safes that cannot be opened under any conditions except by allowing the time delay to expire.
The test.
1) The testers gather before the time traveler is notified the test is underway. The testers will each record a private message that go into sealed envelopes. All are sworn to keep what their specific message is secret. The assumption is the primary tester will not ever reveal what their message was, if the others share, they will not have the primary tester's message.
2) All the sealed messages go into the time safe. It is set to open in 3-days, closed and locked.
3) The time traveler is notified the test is engaged. The time traveler must complete their jump forward and back before the 1st time safe expires. On their arrival, they must record all the messages that were created in step 1 on their own and without talking to anyone who has recorded one of those messages. These messages are placed in a sealed envelope and this sealed envelope is locked in the second safe timed to open at least 1 day beyond the expiration time of the first safe.
4) Once the second safe is locked, the first safe can run to its timer end at which point it is opened and the messages are retrieved. These can be posted or published in an easily accessed place for the time traveler to read and remember to create their message.
5) Assuming the time traveler really went forward in time and did this, the second safe should at this point contain the same messages from the first safe and all the testers need do is wait for that timer to expire and open it to verify that time travel occurred.
If all the testers are intent on proving the time traveler really has gone forward in time, all of their messages when kept secret will verify to their satisfaction that this occurred. If any collusion occurs among the non-time travelers, the test fails for those, but the ones who do not collude to foil the test still have the integrity of their message safe from revelation and proved once the second safe is opened.
The short duration is intended to preclude any circumvention of the safe timers by any participant and allows them to all be together for the duration of the test so that they cannot bring in tools or expertise to circumvent the safes.
The dual message system ensures that the time traveler is not present when the original messages are created and locked. They must successfully move forward in time to retrieve the messages when they are out of their safe, and return to lock those messages in the second safe before the first safe opens. The testers are more than one to watch each other and to watch the safes to ensure no safe is breached for the duration of the test.
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**A one-way hash of the lottery numbers.**
The time traveller tells people the results of the Powerball draw on Jan 22 2020 will sum to 222. For Jan 25, 2020 will sum to 149, and for Jan 29, 2020 will sum to 129.
Three draws later, you're convinced - but even if you force the time traveller to give up all his future predictions, you can't win millions and change the world because he only knows the sum of the numbers, not the individual results.
The nice thing about using lottery numbers this way is it's widely accepted they can't be predicted in advance or changed in the past; they're widely reported, and there's a new lottery result along every few days.
**Scientific discoveries, in unhelpfully vague form**
A time-traveller sent to 1870 could reveal that "power equals mass times the speed of light squared" and by 1920 it would be clear he had knowledge of the future - but the statement is also imprecise enough the time traveller is less likely to inadvertently speed up science on this timeline. For example, if your proof phrase was "uranium will prove militarily important" that might change the timeline a great deal!
The advantage of this is no matter how much the timelines diverge, fundamental physical laws will be the same in both timelines. On the other hand, you have to predict things well in advance - the same revelation in 1903 only proves you're at the cutting edge of physics, not from the future.
**Time-lock encryption**
There are [proposals for ways](https://www.gwern.net/Self-decrypting-files) to create cryptographic time locks - puzzles that can only be solved in a fixed(-ish) period of time.
In short, they rely on a calculation that can't be 'parallelised' - i.e. that you can't calculate any faster by having twice as many computers, only by having a faster clock speed. If your website does a calculation as fast as possible on a 4GHz processor after 10 years you'll have used 40 GHz-years. If someone turns up with a result proving they've used 400 GHz-years, you know they've either come from 390 years in the future, or they've got a 40 GHz processor, or somewhere in between.
This converts the problem into always having the fastest processor in the world. Expensive, but not impossible.
**Caveat: Capture a time traveller, become a fake time traveller**
If cold war USA captured a time traveller who had a list of numbers that proved he was from the future, they could take his list and send a fake time traveller to the USSR to give them a bunch of bad advice. And no list of numbers will prove to the Americans that the same hasn't already happened in reverse.
The only way around this I can think of would be asking the time traveller questions so arbitrary that nobody would have thought to brief their fake about.
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**March Madness Bracket**
Make them produce a perfect bracket for March Madness for the next calendar year. This may take 1 year to verify but the feat has never been achieved. If anyone is able to create a perfect bracket they would probably be from the future. You could also enter their bracket and win tons of money, so bonus!
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"Who are your parents/grandparents currently living?"
Get DNA from them and prove lineage.
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Combine @Dragongeek's answer with at least one of the following biological tests:
* Urine/stool samples to test for future food ingredients (ex: acesulfame potassium would not be present in the urine of a person before 1988)
* Titer tests for antibodies to diseases that do not yet exist (note: this does not necessarily mean that the person contracted the disease, it could just mean that he/she received a vaccine for a currently unknown disease)
* Traces of currently undiscovered medications in his/her bloodstream (this could be helpful, as the medicine could become introduced to 2020 civilization)
* Evidence of the person being cured of a currently incurable chronic disease (ex: HIV antibodies/antigens without the person being detected positive for the HIV virus)
* CT or MRI scans for currently uninvented implants/artificial organs (similarly beneficial to us)
* Test for Y-chromosome (if the time traveller is male) or mitochondrial DNA haplogroups that do not yet exist (these could potentially arise through exoplanetary colonization when a small group is sent (possibly to avoid religious persecution like with the Pilgrim settlers of North America) to colonize an exoplanet or exomoon and these settlers do not have children with outsiders for a long time)
* If the person is from the far future, test their DNA or their anatomy for currently unknown genetic mutations that would have an advantage in a radically different environment from any that exists on Earth today (ex: atmospheric filtering mutations and increased heat/cold tolerance from a post-Apocalyptic Earth or from an exoplanetary/exolunar colony)
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Many [transient astronomical events](https://en.wikipedia.org/wiki/Transient_astronomical_event) are effectively uncomputable and unprevisible. Those include [gamma ray bursts](https://en.wikipedia.org/wiki/Gamma-ray_burst) (GRB), [microlensing events](https://en.wikipedia.org/wiki/Gravitational_microlensing), [gravitational wave detections](https://en.wikipedia.org/wiki/List_of_gravitational_wave_observations) and [supernovas](https://en.wikipedia.org/wiki/Supernova).
Let's pick GRBs. There is no two GRBs with the same light curve. Altough each GRB is an unique event, they are frequently enough that the next one to be observed is no more than a few days in the future, as some sort of lottery.
Now, if our time traveler knows the precise time of future GRBs down to the nanosecond scale with all the detailed light curve data and precise source in the sky with milliarcsecond precision, he would surely be a time traveler.
Let's see if this fits the bill:
* The data is unified, so passes criteria #1.
* It is not a single unique event, but a series of recurrent events. However, each one of those is unique in its own way. So, it passes criteria #2.
* It is not a simple "yes or no" answer or a very simple number that someone lucky enough could be just guessing, so it passes #3.
* As long as there are satellites out there detecting and measuring the GRBs and honest people publishing the observed data somewhere in the internet, anybody with a web browser and the proper links can check that. So, it passes #4 and #7.
* Since a GRB arrives at lightspeed and as long as there is no FTL travel, there is no way to see that a GRB is coming in order to be able to use that information before it arrives. This further strengths #4.
* There is no way to control or influence the time in which a GRB happens, where it will happen or what would be its light curve. #5 passed.
* There is no way for some sort of butterfly effect or self-fulfilling profecy be operating here. #6 passed.
* Except perhaps for a [type III civilization](https://en.wikipedia.org/wiki/Kardashev_scale), it is impossible to predict in advance the time of a GRB or its lightcurve. #8 passed.
The weakness is that you must rely on having satellites observing GRBs and honest people publishing the observed data somewhere in the internet, which means that very few people would be able to measure it independently. Depending on how the story unravel, conspiracy theories would be created stating that either the scientists publishing the GRB data would be simply faking it and just publishing whatever that fancy guy that says he came from the future is telling them to do or perhaps that the guy hacked in the satellite systems that are now just falsely reporting whatever the guy wants they to do. Or perhaps due to the turmoil, the scientists choose to don't publish the data anymore or perhaps they're now just publishing fake data with the very purpose of making them disagree with the predicted data and then make the future-guy fall in disbelief.
But if the time traveler uses his knowledge from the future only a few times or maybe disclose what he knows only secretly for people who trust the scientists measuring GRBs out there (likely from governamental agencies), he surely would have a strong proof that he came from the future.
Also, as long as there are satellites or starships detecting and measuring the GRBs, this is not something restricted to our time or our world.
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1. **Lottery numbers.** Lottery numbers is something that readily available and ostensibly not known before the lottery draw. Popular US lotteries like Mega Millions and Powerball have drawings two times every week. Although a lottery can be rigged, doing so with a large national lottery would be very difficult, and also rise a question about a purpose of doing so. With jackpots normally exceeding $100,000,000, it should be worth more for the perpetrator to fool the time traveler verification system than to just walk away with the money. An obvious drawback of lottery numbers is a random nature of the drawing process. Depending on how the universe and time travel is organized, the same numbers may, or may not be drawn on the "second pass" of a timeline.
2. **Celestial events.** Knowing some number related to events outside of Earth (and even Solar system) would naturally eliminate the possibility of rigging the system (however, astronomers registering those events can be compromised). It also fixes the possible (non-)deterministic factor, because those events would have originated years and years before they are registered on Earth. No matter what kind of "butterfly effect" has unfolded on Earth, it would not affect what has already happened elsewhere. The drawback here is that there is no widely available number which we can use. Whatever is the number that we choose (like luminosity of an irregular variable star or number of supernovas in a galaxy cluster), there has to be an deliberate procedure for obtaining this number.
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You create a secure random number generator with a radiological seed. This device is hooked up to the internet, and it publishes some 50 digit numbers to the internet, one each day.
These numbers are easy enough (challenging, but nothing truly difficult) to memorize just in case it's Kyle Reese and he has to come naked.
They're impossible to predict. Impossible to misuse (except for cases of trivial fraud... "hey kid, I predicted the numbers now invest in my pump-and-dump stock scheme!"). And the time traveler can give you numbers indefinitely into the future, just in case he doesn't want to immediately be proven (for whatever reason).
Assuming your funding is secure (say, the backing of a nation-state government), then even if the machine goes down he can likely convince people ("there were no numbers on November 17th 2021, I'm not at liberty to explain why" then you learn a squirrel chewed through a powerline in Pennsylvania and there was an 11 hour blackout).
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There might be a metabolic check for time travelers, providing they haven't been in the now for too long.
Carbon-14, an unstable isotope, is generated in our environment in the upper atmosphere of our planet by incident solar radiation. The concentration of $C\_{14}$ is relatively constant since the output of the Sun is relatively constant.
Since time travelers are coming from a far future where they've solved many of society's problems, I think they'd have a different $C\_{14}$ concentration compared to someone living today. One thing their society would have solved was starvation. There are many different solutions, but they'd all effectively involve closed-systems like orbital farms or vat-grown food. All these kinds of solutions would result in the reduction of atmospheric $C\_{14}$ getting integrated into the food supply. So, people from the future would have lower to non-existent $C\_{14}$ levels. This would persist while they were back in the here and now, but would fade as they ate our local foodstuffs, but might take years to equilibrate with our 1 part in 1 trillion concentration.
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I think we can start with "astronomical method" for the numbers. Convert astronomical observations of something massive enough with high variability to numbers in a reliable manner that filters observational errors. I personally prefer variable stars to observing the Sun but it does not really matter. Other answers have good enough suggestions.
Then have the person in the future tattoo those numbers into their arm, wait a month and come back two months in time and come see you without delay. Then inspect the tattoo for the numbers and the amount of healing that has happened since the tattoo was taken. You can specify the type of tattoo to be something you can date to tell the difference between one month old and few days old max. Now wait that month to verify the numbers.
Obviously the future person can still travel back in time two months, have an accomplice tattoo the numbers into to their arm and come see you after a month of healing. But I am not sure if there is much you can do if a person who can actually time travel wants to fool you into believing in time travel? Or point really. If a time traveller wants to hide their identity they probably have a good reason.
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You are the control. You determine the message that will be sent out. It can be as complex or as simple as you wish. This message does not need to be locked up or revealed to anyone. It is kept safe in your head.
If someone comes from the future and tells you what your message is, you then publish that information to make it available. Until someone comes from the future and tells you what that message is, you have no reason to reveal it to anyone.
If you die and no one has shown up, someone else will need to become the control, create their own message and wait for the future time traveler to contact them.
If you need others to verify, they are also controls with their own messages, the future traveler must confirm all the messages.
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Assuming the information provided by the putative time traveler will be kept private (and hence not very prone to butterfly the predictions), it should be possible for a well prepared chrononaut to provide the names of officials elected or results of issues at election well in advance -- for instance, someone predicting the results of the 2016 US Presidential election prior to, say, late 2014 could reasonably be presumed to be either a time traveler or part of a conspiracy.
The problem with this method is that it takes so much time to verify.
A similar method that's a little harder (for both the traveler and the verifier) is calling vote counts for any Senate or House (or Parliament) vote on a particular issue, especially an emergency measure, days or weeks ahead. Something like "House Bill such-and-such will fail in committee, but nearly identical Senate Resolution something-or-other will pass the Senate and be confirmed in the House, then vetoed."
This would require the traveler to have brought records -- and the fact that they have a device that serves the purpose of a PC/tablet/smart phone, that is incompatible with known designs, uses incompatible storage media, charging hardware, and communications (even if the latter includes backward compatibility that lets it function on current networks if activated) would serve as very strong evidence. Making a "Samsung", for instance, that isn't any known Samsung, has a processor ten times faster, and stores, say, 32 times as much data, is beyond what even CIA, NSA, or other alphabet agencies could manage.
For instance, a modern pocket device that can store multiple HD full length movies internally would be very strong evidence, to someone in 2000, that the owner was from *some* future -- especially since neither smart phones (nor even the earliest versions of their operating systems), HD television, nor high density (multi-gigabyte) flash storage existed yet in that time. In fact, in the end, the technology brought back seems more likely than any record or memory of "future" events to prove that someone comes from a (though not necessarily "the") future.
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Depends how far in the future I guess. There would be a huge difference between 10 years and 100 years. For 100 years, the type of clothes, technology and language would be a lot different.
Photographic evidence would help, say from a phone or laptop whatever.
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Inspired by [this](https://worldbuilding.stackexchange.com/questions/165692/consequences-of-an-earth-size-object-hitting-the-sun) interesting question-- let's say that the universe was just really, really out to get a particular star, such as our sun. Is there a perfect cocktail where a mass significantly smaller than a star could cause the star to behave strangely after impact?
I'm not just referring to a massive pile of salts crashing into the sun and making a pretty multi-colored burst around the impact, but something that would disrupt the underlying nuclear processes of the star in a way that would be observable from Earth.
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One possibility is called a "[Q-ball](https://en.wikipedia.org/wiki/Q-ball)". A Q-ball is a finite-volume mass of bosons (net-zero-spin particles) theorized to exist by many flavors of string and quantum field theory. The bosons are not bonded to each other by traditional observations of the four fundamental forces, like gravity or electromagnetism, but instead due to a local attractive force within that mass which makes the Q-ball the most stable, lowest-energy arrangement of the particles within it. One additional theory is that this attractive force can cause the Q-ball to grow in size by capturing more bosons.
Now, the nucleus of a Helium-4 atom is a boson; the net spin of its 4 fermions is zero. Helium-4 nuclei could therefore be attracted to and captured by a Q-ball that wandered into the mass of a star. Bosons within the Q-ball would not undergo interactions like nuclear fusion, thus robbing the star of a key late-stage fuel and fusion source. This would affect the star's density and thus its temperature, disrupting the stable dynamic equilibrium of the star's interior environment, potentially slowing hydrogen fusion and creating a vicious cycle that, in theory, could eventually "kill" the star.
This was one theory proposed by the writer of the movie *Sunshine*, as a scientific basis for why the Sun's fusion was prematurely slowing (causing a reduction in solar radiation, and catastrophic global cooling of Earth, prompting two separate expeditions to deliver a vaguely-described device to "restart" the Sun). However, the Sun's mass is insufficient to trap a Q-ball, and our best estimates of the Sun's age indicate only 25% of its mass would be helium, with minimal helium fusion occurring, so even if a Q-ball were in the Sun, there's nothing significant it could inhibit for billions of years. And, should our Sun ever start to behave abnormally, there's nothing at all the human race could do with current or near-future technology to influence it; the entire mass of Earth is 1/333,000 the mass of the Sun, so anything we had available to use to build any such device would be a grain of sand on a beach relative to the raw energy of a star or anything that could possibly actually influence it.
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Assuming neutronium is stable in sub-stellar masses (impossible to verify at this time), a chunk of that material, introduced with enough velocity to promptly penetrate to near the core of the star, then capture into an orbit (via gas drag), would have some significant effects on its hydrogen fusion process and the convection that delivers that energy to the outer layers where it can be radiated.
The mass involved might be as "small" as that of Jupiter -- less than 1% of the star's mass -- but the surface gravity of a neutronium sphere of that mass would be thousands of G, allowing it to create its own "atmosphere" even inside the star. Such an object is dense enough it could *orbit* inside the star (bypassing its core) for at least centuries, possibly as long as a million years. While doing so, it would be constantly accreting the stellar material (mostly hydrogen, of course) onto its surface, shrinking the star slowly even as it disrupts the star's circulation.
Then, at some point, the accreted material (which would include an ever-thickening layer of degenerate hydrogen) would initiate a runway fusion reaction, equivalent to (IIRC) a type Ia supernova event, potentially capable of completely disrupting both the neutron sphere and the host star.
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# Strange matter
One single [strangelet](https://en.wikipedia.org/wiki/Strangelet#Natural_or_artificial_occurrence) will do. It could weight as little as a light nucleus (such as that of an carbon or oxygen atom).
The thing about strangelets is that everything they interact with also becomes strangelets. This means the sun would be completely converted into strangelets in finite time.
For more information, see this video by Kurzgesagt, [starting at 3:52](https://youtu.be/p_8yK2kmxoo?t=232) (or watch the whole thing to learn even more about this bizarre thing). The sun would still have the same mass, but it would become denser and dimmer.
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**Gamma ray burst**: a typical GRB lasts less than a second - a 'long' one lasts several seconds. You can learn more about it [here](https://starchild.gsfc.nasa.gov/docs/StarChild/questions/question47.html). They're caused by exploding stars, so given that two stars are travelling in exactly the same trajectory to one another - effectively in parallel in 3 dimensional space - a long lasting, focused GRB on your star could kill it - the star might supernova! The only thing that can cause one star to supernova is another - fight fire with fire!
**Antimatter**: Dropping enough anti-matter can probably take out the entire star through its annihilation process. I don't like this idea because if you're planning to annihilate the entire star, that would require a proportional amount of antimatter, and that's not very interesting, and where would you even get so much of it in one place? Might be too unlikely. But your choice. Here's a [post](https://www.quora.com/How-much-antimatter-would-it-take-to-destroy-the-sun-Is-it-possible) with some numbers about it.
**Black hole**: nuff said
**2 Other Stars**: These other stars pass by your main star in a trajectory that is perpendicular to both your main star its co-star. The resulting forces would likely result in your main star being torn apart.
I'll add more ideas if I come up with any - I know that you asked for masses to slam into your target star, but I think this could also inspire some cool ideas. The other answers are also pretty good. I hope this helps!
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**Drop anti-uranium into it.** Assuming that:
1. Antimatter can occur naturally,
2. Matter-antimatter reactions actually *do* result in complete mass-to-energy conversion (to my knowledge nobody has ever proved this), and
3. The antimatter can get from point A (somewhere outside the solar system) to point B (the sun) without being completely annihilated,
then the result would be
4. A complete mass-to-energy conversion of the anti-uranium and the solar corona in its area. Provided that a sufficient amount reaches the sun, this would cause a massive solar flare. If you want to be *really* extreme, you could drop a mass the size of Jupiter into the sun, causing the sun to go supernova. A supernova would definitely be noticed, but this notice would only last about .00001 seconds.
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I would swear that I saw a documentary saying that as soon as a start begins to produce iron, in that cascade of fusing heavier and heavier elements beginning with hydrogen to helium, it immediately goes nova. It also said that authors in Science Fiction have gone through so much trouble to explain killing a star with invented exotic devices, when all they really needed was a frying pan. Try googling that.
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I'm devising a political system for a novel I'm working on, but I'm not sure how to name its parts. I'll give some context first and then get to my question.
* The story is in a middle age context
* The continent contains 6 roughly equivalent "kingdoms", where "kingship" is hereditary
* Kind of like Malaysia's political system, there is a rotation among the 6 "kings" or "queens", where they alternate to become the "high king" for a 5-ish years term. There is a central kind of state, where they sit for the duration of the term.
* Balance between the 6 "kingdoms" is a big theme in the story, and the meta-governing body is necessary for the plot.
My question is this: Is there a name for this kind of system? I don't want to call it a kingdom, or an empire, or whatever, if this is not the right term. Basically, I'd like to know how I should name
* The whole "meta-kingdom"
* The six "kingdoms"
* The six rulers
* The ultimate ruler
Thanks a lot.
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So the term for this system is "Federal Monarchy". Likely a "Federal Constitutional Monarchy" in that the big king has to have some areas of power where he is not absolute in his authority within each separate Kingdom.
There are lots of terms you can use for the whole Kingdom, though "Federation" should be avoided as the term did not exist back then (Instead, what we call Federation today was a Confederation then... which now denotes a very loose federation. The EU is probably a Confederation). Union or League are probably good common names, given the setting, though if you want a fancier term, I suggest "Polity" or "Grand Kingdom". The actual name of the super-kingdom is yours and yours alone to consider and should probably be a Regional term (I.E. The United States of America is literally a federal nation of republics on the American Continent. As compared to the United States of Mexico, which is a federal nation of republics in the Mexico region of the world). While now only refering to one nation, United Kingdom was used in history for any nation where the King and his men were in control of multiple Kingdoms to one degree or another. The modern UK is four nations (England, Wales, Scotland, and (Norther) Ireland). The historical United Kingdom of Portugal was a period where Portagul was one component of equal monarchies representing their colonial holdings (Including Brazil and Algarves at it's height.) In both cases, all componant nations were part of the former title, but in more common use, the principal kingdom or region will be the first nation mentioned (United Kingdom of Portugal or United Kingdom of Great Britain.). Grand Kingdoms aren't a real thing, but several real life Grand Duchys exist, where the Monarch is a Duke who holds multiple Duchies, often because the Duke/Duchess was the heir apparent to multiple Duchies.
The six Kingdoms can be Kingdoms or Vice-royalties or Captaincies or Duchies. Obviously this denotes different things, where the Kingdom will be a hereditary King (closes in line will be King, usually going down the eldest son's family tree), Viceroys and Captains (as well as Governor and Governor-Generals) typically denote people who act for the king in day to day management (I like to say, the Keep the Local Throne warm). Typically they're not lineage driven, but you could have a system like the Papal Conclave where the Big King may designate from the persons family line (but not necessarily direct line) when a vacancy needs filling and then those people sit on a rotational basis of five years, with the big king leaving after five. Alternitively, it could be the guy in charge of the Big King's Kingdom while he is managing the Big Kingdom so it's five kingdoms and one Vice-royalty. Could also be that the collective actions are made by all six kingdoms with the Viceroy's vote going to his king (giving big King a second vote, that may only be used in a tie breaker vote.). Alternitvely they could be Princes of Principalities or Princely States (India used this. A raj was a prince, a raja was a King, and a maharaja was a High King, ususally having more than one Raja or Raj answering to him. An Emperor was called something else).
The Big Guy would probably a High King or an emperor. Depending on the flavor of the six constituent kingdoms, you could find a similar term for them. Empreror usually denotes that the Emperor is a king of multiple kingdoms at once (similar to a Grand Duke is a Duke of many Duchies) while High King is usually a King of Kings, meaning that his power is absolute in his personal kingdom, but he does have some authority over kings of other kingdoms, but not absolute. For example, in the United States, the President speaks for all states in foreign negotiations, but does not speak of a state in matters of zoning laws... a governor does that.).
The government is probably an oligarchy in nature (which means leadership is not inherited but is limited in who can be eligible). It's probably Constitutional as well (though a Constitutional nation didn't become a thing until the United States did it and everyone wanted to be cool. Middle ages would not have it and the closest thing, the Magna Carta, was a list of Rights of Nobles (and later all men) that formed only part of the Constitution. To this day, the UK is one of only two nations without a codified constitution (the other being New Zealand. Ain't no rule that you have to actually follow the Constitution or that it has to have a bill of rights... It's just a list of hard rules of government operation. Saudi Arabia is an Absolute Constitutional Monarchy (there Constitution is the Koran). Vatican City is an Absolute (infallibility, though rarely invoked) Constitutional (the Bible) Elective (Conclave) Monarchy (The papal title is a linage to a certain person, though not blood lineage as is traditional to monarchies, but a spiritual one and the ruler is picked from Cardinals named by him or his predecessor).
There are a lot of fun options, but you should probably focus on why a rotating king as opposed to a unified empire was desirable (descendants from one Mythic King of the Realm who couldn't choose a favorite child from his six? Six weak kingdoms that only survive in their unity, but are too proud to become fully unified on all fronts? A military alliance of six kingdoms that allowed a rotating leader an extra vote when ties occurred and the military needed some decision. This was carried over in peace. A group of enlighten monarchs that believe no one man should have all the power (The Liberal Movement that Sparked the United States never actually favored Republics over Monarchs. Rather it believed government should protect the people's rights. The anti-Monarchy angle came from the fact that George III was using royal ascent to grant parliament the ability to abuse citizens of their rights and the King couldn't be ousted reliably by anyone led to a marriage of Liberalism to Republicanism, though the two are not mutually required.).
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Yes, there is *an existing name for this kind of political system*. It is called...
## The European Union
This is exactly precisely how the European Union works. There are 28 (as of 6-Nov-2019) member states. Every six months, one of the heads of government of the member states becomes [President of the Council of the European Union](https://en.wikipedia.org/wiki/Presidency_of_the_Council_of_the_European_Union). The order is fixed and known in advance. As of now, in November 2019, the President of the Council of the E.U. is Antti Rinne, Prime Minister of Finland. In January 2020, whoever will be Prime Minister of Croatia at that time will become President of the Council of the E.U., to be followed by the Chancellor of Germany in June 2020 and so on.
In the E.U. we usually call this the "rotating presidency", but this is not an official term in any way.
Fun observation: The President of the Council of the European is a non-executive position, yet it is always held by an executive head of government, never by a non-executive head of state. Go figure.
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## Confederacy
As others point out, what you're wanting really is a confederacy. I'd like to focus on one historical example: the [Iroquois Confederacy](https://en.wikipedia.org/wiki/Iroquois#Iroquois_Confederacy). They're a [fascinating read](https://www.jstor.org/stable/1464101?seq=1#page_scan_tab_contents), or if you're short on time, I think the youtube channel Historia Civilis [has a pretty good video overview](https://www.youtube.com/watch?v=S4gU2Tsv6hY) of them. There were "sachems" who became the "council" of the actual confederacy. Everything was deeply symbolic of the family structure.
There wasn't exactly a high king; it was more democratic among the council (like a parliament or congress). There's no way I can do it justice here, but really, the Iroquois are worth some study. But instead of doing them justice, if we raid their language in the name of creative fun, we can come up with:
* **Confederacy** = The whole "meta-kingdom"
* **Nation** = The six "kingdoms"
* **Sachem** = The six rulers (elected from among the "chiefs" of the "council" - again, playing around with names here)
* **Great Clan Mother**, or **Great Mother** (or "Great Father" / "Great Clan Father") = The ultimate ruler.... This wasn't a thing for the Iroquois, but we can make this up for fun.
Personally, I like the symbolism of "one great family", and this example of a confederacy was quite remarkable.
## Hegemony
Wikipedia has a decent [list of historical hegemonies](https://en.wikipedia.org/wiki/Hegemony#Historical_examples). A noticeable example was the [League of Corinth](https://en.wikipedia.org/wiki/League_of_Corinth) where Philip the Second "unified" (basically by threat of force) the Greek city-states into the Macedonian empire. The league elected a [Hegemon](https://en.wikipedia.org/wiki/Hegemony) to rule over the league. Each Greek city-state participated in the alliance and they appointed Philip and his descendants as the Hegemon over the League. This was more or less a military alliance, with Macedon "allowing" the city states to do their own thing so long as they (a) never interfered with Macedon, and (b) participated with Macedon (under Philip's rule) to wage war against Persia.
Broadly speaking, a Hegemony is a form of *confederation*, as other answers point out that's really what you want. And historically there isn't a hegemony exactly like what you're describing. But the word "confederation" wasn't used as much historically, and hand-waiving here is probably okay for creativity's sake. In this context you could steal from the language to make:
* **League** = The whole "meta-kingdom"
* **State** = The six "kingdoms"
* **King** = The six rulers
* **Hegemon** = The ultimate ruler
Although the Hegemon wasn't rotated in or among the
## Satraps and King of Kings
A more top-down approach would be something like the [Achaemenid Empire](https://en.wikipedia.org/wiki/Achaemenid_Empire), which is a where Cyrus the Great established *satraps* (basically governors) over a *satrapy* (state), where they had (mostly) full autonomy, outside of some tax laws and allegiance to Cyrus (the "King of Kings"). This worked really well, especially in a multi-ethnic area. Granted there is no rotating in or out of the king of kings, but again, stealing some of the language for the sake of creative fun:
* **Empire** = The whole "meta-kingdom"
* **Satrapy** or **State** = The six "kingdoms"
* **Satrap** or **Governor** = The six rulers
* **King of Kings** or **Emperor** = The ultimate ruler
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I have to type fast before this is closed as opinion-based or whatever.
Basically what you're asking cannot really be answered, we can only give an opinion on what would sound good, and again depending on what kind of "feeling" you want your setting to evoke you have to choose different names. So I won't make any suggestions, but I will try to give you some guidelines:
1) Start with the word for the six "kingdoms" OR one of the six "kings". Depending on your setting this could be a lot of things, totally different for medieval high fantasy and space opera where the kingdoms are planets or star systems. One way to approach this is to find a familiar language (depends on your audience, but generally something like English, German or French is suitable for Europeans, or Greek/Latin if are a man of culture) and try to combine two words that reflect "authority" and "place" (if you start with the "kingdom") or "authority" and "man/woman/human" (if you start with the "king")
2) Once you have the word for one of "kingdom" or "king", you have to devise the word for the other, this will usually be done by either appending something or cutting something from the first word. Do as you see fit, but try to keep both words at or under three syllables maximum.
3) From there on, you have two options. Either append something that reflects the meaning of "over"/"superior"/"greater"/"bigger"/whatever to these words to name your "meta-kingdom" and the "ultimate ruler". Or follow the same process as before, but with words that sound "grander".
Alternatively: you don't have to restrict yourself to one name. Each kingdom and its king may have a different title, and the combination of such may be named something else entirely. This works because it gives you more of an individual feeling, for example if I read about a "Confederation" I'd get a different head-image than if I read about an "Empire" or "Caliphate". Additionally, for important things like the "super-kingdom", you can have multiple titles, one "formal" and one "informal" (which may even be derogatory) used among the general populace.
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You might want to read my post in the thread: [Imperial Kingdoms?](https://worldbuilding.stackexchange.com/questions/110223/imperial-kingdoms/110329#110329)[1](https://worldbuilding.stackexchange.com/questions/110223/imperial-kingdoms/110329#110329)
Some of the historical examples it gives from Earth history may be informative for your purposes.
To decide the title of the ruler of 6 kingdoms consider the organization of a feudal kingdom in Europe, which is more or less a rough model for your society.
Most of the land in the kingdom would be divided into hundreds, or thousands, or tens of thousands of manors, each with tens or hundreds of peasants, both serf and free. Each manor would have a lord who held it as a fief from a higher lord and had to give feudal service to the higher lord.
A larger region of the kingdom would be a county, and the count of the county was usually the overlord of most or all of the manor lords in the county. The lords were the vassals of the count. Thus the count could be considered to be a lord of lords but used the separate title of count instead.
The kingdom would be divided into some large regions called duchies, each containing a number of counties. The duke of the duchy would be the overlord of most or all of the counts in the duchy.
A duke could be considered a lord of lords of lords, or a count of counts, but used the separate title of duke instead.
All of the kingdom would be under the king, and all of the dukes would be vassals of the king.
So a count could be considered a lord of lords or lord to the second power, a duke could be considered a lord of lords of lords, or lord to the third power, and the king could be considered a lord of lords of lords of lords, or lord to the fourth power.
A duke could be considered a count of counts, or a count to the second power, and a king could be considered a count of counts of counts, or a count to the third power.
And a king could be considered a duke of dukes, or a duke to the second power.
In real life the feudal system, or lack of system, could b get a lot more complicated. Many persons accumulated a number of different lordships, counties, duchies, and even kingdoms and thus had several different overlords and many different vassals. Few persons ever turned down a chance to acquire another manor, fief, or principality merely because it would make their feudal relationships more complicated.
It was perfectly possible for Lord A to hold fief B from Lord C while Lord C held fief D from Lord A, making them both each other's overlords and vassals.
A baron was a lord who was a direct vassal of the king and wasn't a vassal of any count or duke.
In the Holy Roman Empire the class of princes were rulers who were immediate and direct vassals of the Emperor and king, but they had a number of different titles. From lowest to highest the titles of the princes were princely count, landgrave, margrave, count palatine, prince, duke, grand duke, and archduke.
In some kingdoms, abbots of monasteries, bishops, and archbishops were also feudal vassals.
Anyway, in a feudal kingdom, each higher level could have been described as the overlord of the next lower rank but instead had a totally separate title.
So that would make it logical for you to invent a totally new title for the overlord of kings, since counts, dukes, and kings had titles which didn't specify who they were the overlords of.
As most people should know, there was a country in Europe which had many rulers who were overlords of kings - Ireland.
Medieval Ireland had tens of states or kingdoms called *Tuatha* - I have seen numbers like 90 or 150 but don't know how many there actually were, so I assume that there were about 50 to 200.
The island of Ireland has an area of 84,421 square kilometers or 32,595 square miles. So if at any one time there were 50 to 200 *Tuatha* in Ireland, the average *Tuath* would have an area of 422.105 to 1,688.42 square kilometers, or 162.975 to 651.9 square miles. If each was perfectly square it would be 20.545 to 41.090 kilometers on a side or 12.766 to 25.532 miles on a side.
If medieval Ireland had a population of 1,000,00 persons at any specific time the average *Tuath* would have a population of 5,000 to 20,000 persons at that time. Of course *Tuatha* varied a lot in size and population.
But if the kingdoms in your story are no larger than Irish *Tuatha* the six kingdoms would occupy only a rather small island instead of an entire continent.
The monarch of each *tuath* was a *ri*, or king. The ruler of a group of *tuatha* was often called an overking. The ruler of all the *tuatha* within a province of Ireland was often called a king of overkings.
"Province" is an English word. The Irish word means "fifth", and the "provinces" were originally fifths of Ireland. But ambition was more important than math or logic for Irish kings, so the number of "fifths" at any one time varied with political and military events, and today people usually talk about the four provinces or "fifths" of Ireland, forgetting there were once five and sometimes six.
And for centuries there was a king claiming the over lordship of all Ireland, who was called the High King of Ireland, or often called the King of Tara from the ancient ceremonial center at Tara.
As I said before, you are free to make up any name you wish for the supreme ruler above the six kings. If the name of your island or continent is, for example, Ecalpemos, you could call the supreme ruler the Ecalpemcrat, "ruler of Ecalpemos". Or maybe Contincrat, "continent ruler".
However, I kind of prefer that you call the supreme ruler of the continent the king of kings of that continent.
And that is because a number of religious persons claim that the title of King of Kings is reserved for God almighty, and I think that silly opinion should be disregarded as often as possible.
In the Bible, God is often called the Lord, and King, so if using titles that have been used for God is bad, all the lords and kings in medieval and modern Europe would have also been using titles reserved for God.
Furthermore, when the Bible was written including sections describing God as King of Kings and Lord of Lords, human rulers had already been using the title of king of kings for centuries or millennia. Clearly the writers who described God as king of kings couldn't hope to persuade human kings of kings to give up that title, or convince the more educated Jews that king of kings was a title used only by God, so those could not have been their intentions.
And of course many Christian countries have been ruled by kings of Kings.
But claims that mere mortals shouldn't use the title of king of kings may have discouraged its use in many medieval lands. In Ireland, for example, it would have been logical for an overking to use the title of king of kings, a king of overkings to use the title of king of kings of kings, and the High King of Ireland to use the title of King of Kings of Kings of Kings of Ireland.
European culture lacks any title higher than king and lower than emperor, and so many rulers who wanted use higher titles than king took the title of emperor. Thus there were a bunch of so called "empires" such as the Russian Empire, the First and Second French Empires, the Austrian Empire, the First and Second Haitian Empires, the First and Second Mexican Empires, the Brazilian Empire, the German Empire, the Empire of India (the British Raj), the (Italian) Empire of Ethiopia, and the Central African Empire.
But none of those "empires" were true empires in the sense of being Roman Empires or claiming to be the rightful governments of the whole world. If European culture had a tradition of titles ranking between king and emperor, such as great king, high king, king of kings, etc., etc., those titles could have been used by European rulers higher than ordinary kings but lower than emperors.
And I hope that fantasy writers do their part to show what an error that was by creating titles higher than king for their fantasy world while restricting the title of Emperor to those rulers who claim to be the rightful rulers of all the world or all the universe.
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It's the perfect locked-room mystery: the police find the victim murdered, but the room is locked from the inside. How did the killer escape? *He didn't.* After committing the murder, the killer committed suicide and then destroyed his body, leaving no traces.
**How can a person destroy their body so that no traces of it are visible?**
To clarify, the traces of the person's body do not have to be completely undetectable, but a non-expert should not be able to find anything suggesting a corpse (i.e. Sherlock Holmes could deduce that the killer had destroyed himself, but Inspector Lestrade wouldn't be able to work it out).
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If the locked room is a morgue, then the murderer poisons his own twin brother and makes sure the body is checked into the morgue. Before the autopsy, he lures the victim there, murders him, burns his twin brother's body in the medical incinerator, burns all of his own clothes, rearranges all the bodies in the morgue (just to mess with investigators), and then lying in a morgue refrigerator crisper bin or whatever they are called, swallows the poison he used to poison his twin brother.
Oh, and he hasn't eaten anything for 48 hours, and gave himself an enema, and peed before laying in the cold metal thingy they keep bodies in so he doesn't crap and piss himself when he dies.
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How much time is allowed before discovery?
The room has a sink made of a material that can take a good amount of heat. Stainless steel comes to mind but there very well might be other materials that aren't coming to mind at the moment.
After doing his dirty deed the killer climbs onto a contraption sitting in the sink. (This will be a bit precarious due to the narrow base it must have. There could be additional supports while he was getting in that are then removed.) He's lying on a membrane separating himself from a mixture of sulfuric acid and hydrogen peroxide. After he's dead a timer triggers, making a hole. In time the chemicals dissolve the body. (Yes, this is basically a scene from *Breaking Bad*. The show didn't give the details and it wouldn't have worked exactly as shown anyway.)
After enough time has elapsed a second timer opens a drain line which is run down the drain past the metal parts. Away goes your chemicals and all obvious traces of the body. Removing all that weight causes the device to fold up (and pulls up the drain line) and triggers the next stage--the release of a solvent for the plastic of the main part of the machine. The last piece to melt through is another drain--that part is now gone.
Yet more time, a container of water ruptures, washing the gunk out of the trap. At this point you have some scaffolding, the bowl that held the melting plastic and whatever held the water. (The timers are chemical in nature, no electronics are involved.) These are all built out of something that will burn slowly and cleanly, the last stage is to burn it. (This timer might be as simple as something that will spontaneously ignite once dry--but it was in the water holder.)
There's no such thing as truly zero residue from burning a solid, there will be traces left but not much. A disguise of a controlled kitchen fire earlier would make it even harder to find. (Something on the stove burnt in a situation that kept the size of the fire down. Lots of smoke but no fire damage. Leave the burnt stuff as evidence of the nature of the fire.)
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**Thermite**
The murderer could use thermite to dispose of their own body (could be a timer-based device that ignites it) or simply to commit suicide (but that would probably be rather painful).
The only problem is that it burns *slightly* hot and could potentially just incinerate the whole room so a lot would depend on the environment - ceramic tiles in morgue would probably be fine, some old wooden shack would probably burn down.
Since there will be a lot of ash, the murderer could make it look like hiding the evidence even further - throw some clothes, computers and other stuff to the burning pile and the body might not be detected so easily.
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# Human Candle/Wick Effect
<https://en.wikipedia.org/wiki/Wick_effect>
If a sufficiently rotund body is wrapped in wicking material, and then set alight. The body can be almost completely destroyed/cremated owing to the makeshift reverse candle that is created.
The body slowly imparts oil to the wick/clothing. This slow burns creating intense temperatures, which destroys the body.
Typically in this process, the legs are usually left intact.
To counter this, our "hero" could cover his feet in lard before rolling himself up in a carpet, and setting himself alight.
As a bonus, this process in the wild, typically does much less damage around the body than would be expected.
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Acid in a barrel, connected to a drain pipe, with a timer to open a drain valve (and some neutralizing alkalic solution). But watch the mythbusters episode about Breaking Bad.
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Another and less usual way to destroy a body is by decompression. If you've got a good stomach for gore, google for some decompression accidents.
I believe it's possible to more or less liquify a body, so it could be drained away.
I can't find a citation for that right now (thought it was the Byford Dolphin, but not sure), and don't feel like reading reports on it again... someone else can, ah, flesh out this answer...
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I have a character who is, for lack of a better term, a Monster Hunter. She's physically fit, has a pretty high pain tolerance/is generally pretty durable, and is skilled in various forms of hand-to-hand combat. The problem is that she's also Not Very Big- 4'11, *maybe* 135 lbs soaking wet- and while she's proportionally fairly strong due to her Ridiculous Personal Training Regimen, there's still only so much force she can exert with that much mass, and sometimes the Baddies are just Too Big/A Ridiculous Temperature/otherwise Unwise To Touch and likely to Kill Her Very Badly if she gets too close.
The obvious solution is, of course, a ranged weapon; something to Shoot Some Zelda-Boss Looking Beastie Right Between The Eyes before it can Raze The Village or whatever. Except that there's another problem: our heroine, in addition to being a frankly *hilarious* size given her line of work, is also *[severely myopic](https://en.wikipedia.org/wiki/Near-sightedness)*, to the point where she might be bordering on "Legally Blind/Not Allowed To Drive Without Corrective Lenses" territory nowadays. She is... Really probably not the best person for this job, but my question is more about workarounds than it is about her questionable career choices. XD
She does have access to Corrective Lenses for this problem, and wears them on the job; however, while they dramatically improve her general vision, they're roughly equivalent to the sorts of lens technology used for spectacles in the late 1800's-maybe early 1900's, and as a result are more General Magnifiers than Specific Prescription Lenses (they're big heavy suckers too, an inch thick and taking up Most of Her Face XD), so I'm not sure if that would affect things like accuracy and depth perception at all. As someone who uses Modern, Specialized Corrective Lenses myself and still can't hit the broad side of a barn with *anything*, trying to imagine what kind of ranged weapon this Unusual Monster Hunter might use, and how she might compensate, is difficult.
I do have one idea that fits a few of the themes of her story: a sling, like in the biblical example of David and Goliath. Hits hard, ammo is literally All Over The Ground (can be knapped into a better shape for throwing if you have time), concussive force kills plenty of things outright and probably at least stuns larger foes if you can get them in the head, you don't have to be very big to generate a lot of momentum/energy with it... The only problem is, I've never used one myself and have no idea how accurate you have to be in order to do any damage with it. As long as she can focus her vision enough to discern Roughly Where The Head/Other Vulnerable Spot is, is that going to be enough to allow her to hit the mark? And how much damage could she reasonably do this way, assuming the enemy in question isn't Plated All Over Like An Armored Truck?
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One key note is that you should never underestimate what the seeing impaired can infer with proper training. My mom for example is legally blind from toxoplasmosis; so, I'd imagine her vision is as bad if not worse than you are describing. Yet, she can beat most normally seeing people in a game of ping-pong despite not seeing the ball. People who only see form tend to get very good at paying attention to body language and posturing which could not only help her guess where the bad guy is, but where his soft spot will be 3-seconds from now for a dead-on hit.
As for the sling, it is important not to confuse these for a slingshot. Slingshots are not good for killing anything bigger than a squirrel, but with practice a sling can deliver a similar force to a mid-high calibre handgun.
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> Recent experiments conducted in Germany showed that a 50-gram Roman bullet hurled by a trained slinger has only slightly less stopping power than a .44 magnum cartridge fired from a handgun. Other tests revealed that a trained slinger could hit a target smaller than a human being from 130 yards away. <https://news.nationalgeographic.com/2017/05/ancient-slingshot-lethal-44-magnum-scotland/>
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As for what size monster a sling could be used against, we know from ancient accounts that slings could kill lions and armored soldiers without problem, and if it's stopping power is in fact similar to a .44 magnum, then even killing an elephant sized foe in the right hands is not out of the question.
The only real downside of a sling compared to other ancient ranged weapons (for a well trained user), is that you do need to be in a more open position to use it so it does not snag on anything.
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Since you say she is a type that makes a Ridiculous Personal Training Regimen.
A sling is a viable weapon. They are popular in the Middle-East even today.
You can make a sling that will throw a fist sized rock a quarter mile (400m) and with practice hit accurately. They are cheap and easy to make.
Even if she is myopic she should be able to practice enough to hit man sized targets or larger.
One serious advantage that may be an idea depending on your setting, alternative ammo: a few smaller rocks for a shotgun effect, a bola round to tangle them up, or throw some kind of potion bottle that does tear gas, an expanding sticky compound, sleep gas, or something like that.
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As you said, a sling deals damage by impact.
Having, as a kid, played quite often with throwing stones (either by hand or with some slingshot) to hunt lizards and other small animals, I have also received my fair amount of "friendly fire".
Though a kid doesn't have that much force, I cannot state that there was a part of my body I would choose as target to be hit since it causes less pain.
Now I imagine that a trained person will be able to put quite some kinetic energy in that projectile, that would either deeply concuss a body, should it hit a limb, or even case more severe damage, should it hit the body or the head.
Being able to see at least the location of the target should suffice to address some shots, without needing the perception of fine details. The only problem could be to discriminate between a still target and an inanimate object close by, like a bush or a tree.
To have an insight of the damaging power of the slingshot, this is what the Roman [Vegetius](https://en.wikipedia.org/wiki/Sling_(weapon)) wrote
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> Soldiers, notwithstanding their defensive armour, are often more annoyed by the round stones from the sling than by all the arrows of the enemy. Stones kill without mangling the body, and the contusion is mortal without loss of blood
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**Probably not a good choice**
Slings (including staff slings) have several advantages when compared to bows, crossbows and firearms:
* Slings are very cheap and quick to manufacture with materials that are likely to be easily sourced.
* A sling is very light and easily concealable.
* A sling can be used to launch unusual ammunition types, even including grenades (for those willing to live very dangerously).
With all of these advantages, why do people use anything else for hunting and warfare? Well, the disadvantages are:
* the sling must be used from a standing position (unlike crossbows and firearms, which can be fired from a prone and/or covered position with minimal exposure)
* the slinger needs a considerable amount of clear space around and above themselves to swing the sling, depending on the length of the sling and technique (overhand or sideways) being used. Even clipping relatively light branches or shrubbery in the path of the swing will eliminate accuracy, while use is completely impossible in tunnels, doorways or cramped indoor quarters.
* rate of fire is very slow compared to both bows and most firearms - this is literally the killing weakness for the monster hunter, as if the one shot does not eliminate the monster there will not be time for a second.
* vast amounts of training and practice are required to employ the sling effectively and accurately. This is the main reason that crossbows and subsequently firearms were adopted by armies worldwide - a soldier can be trained to reliably hit a man-sized target at battlefield ranges within a few weeks using a crossbow or firearm. Achieving equivalent effectiveness with a bow or sling takes months or years of training and constant practice. This may not be a problem for a dedicated monster hunter, but the time taken training with the sling is time not spent on other activities.
Looking at the situations described where a ranged option is desirable:
* Ridiculous temperature / unwise to touch (poison skin?) - in these situations firearms are best but a long spear made of an appropriate material would still be preferable to a sling unless any target bigger than a squirrel.
* Too big - this is the reason elephant guns were invented. A sling can be effective against humans, but if the monster is much bigger and tougher than a human then sling ammunition will just be an annoyance as it closes. Use a firearm with lots of punch.
[Answer]
**Crossbow**
Crossbow is a better option as it could be fitted with a telescopic sight to compensate for the vision problems. Even fitted with a single lense would assist.
The first [telescopic rifle sight](https://en.wikipedia.org/wiki/Telescopic_sight) was invented in 1835 and the first [telescope](https://en.wikipedia.org/wiki/History_of_the_telescope) was 1608.
A sling is hard to use and not the sort of thing a person with poor eyesight would want to rely on for a sure kill as any kill would be mostly pure luck.
A crossbow can be loaded ahead of time and fired from cover in an ambush. The bolt can be barbed and poisoned helping take the monster down and different bolts can be made for a monster's weakness such as silver bolts for werewolves and wooden bolts for vampires. Barbed harpoon bolts could tether the monster to a spot to stop it from fleeing.
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[Question]
[
How would one go about repurposing a small cargo ship, no more than 50,000 tons, to run on an alternative fuel source/propulsion other than oil? And what alternative source would work best for propelling a ship that size while meeting the following requirements?
* The ship must be convertible to alternative fuel/propulsion with fairly basic technology: steel, welding, and simple machinery
* Fuel source/propulsion mustn't rely on heavy infrastructure or complex methods of extraction, no nuclear power or what have you
* Should be easily repairable with basic technology
The world the freighter would exist in is a not quite post-apocalyptic earth in which very complex or infrastructure-heavy technologies (like the internet or oil industry) are no longer capable of being manufactured, but for the most part, civilizations are still around. Simple technologies that can be locally manufactured still exist and there are bright spots where the technology is much more advanced.
[Answer]
One option is to install masts and use wind, the Thomas W. Lawson was a ship 7 masted steel schooner that could carry 58,000 barrels of paraffin oil. Your cargo ship is bigger, but could probably just have more masts. It could make for a very interesting looking artist rendering.
[Answer]
Cargo ships are designed to run on [bunker fuel](https://en.wikipedia.org/wiki/Fuel_oil#Bunker_fuel). Bunker fuel is basically what's left over after you're done refining all the interesting bits out of crude oil, and is highly variable in quality. Because of this, marine diesels are quite versatile in what they can run on.
In a not-quite-post-apocalyptic Earth that has a use for something as large as a small cargo ship, there's not really any conversion needed. Just dump whatever flammable liquids you can find in the tanks and go on your way.
(The fuel doesn't even need to be liquid at room temperatures. Bunker fuel is so viscous that the tanker's fuel system will include provisions to heat the tanks and fuel lines.)
[Answer]
**Whale oil.**
If civilizations have fallen the whales might be doing alright. Round them up and render the oil in the old school way.
Or if that seems too mean, the first steam ships used to run on coal. Digging that up is not especially high tech and you could switch up your ship to use a coal-fired boiler.
[Answer]
## Multi-factorial approach:
* sails: you'd just need a lot of them
* paddle wheel: rig up some big paddle wheels to be turned by...
* coal powered engine: there's still loads of coal and in the Post-Pockyclypse
* ox turned engines: just like old fashioned mill stones
* oars: yep --- *power to the people!*
I think we need to be cognizant of several things for this scenario:
1. You've already ruled out petroleum and nuclear as viable energy sources
2. In ruling out petroleum, you're basically ruling out nearly everything else *in the entire world*: no petrol means no cranes to build or fix wind turbines; no plastics to make or repair solar panels; no fuels to transport goods or people; also no fuel for heating, cooking, petroleum based power plants, etc.
3. This means your big ship and her crew will need to be much craftier and much less reliant on a single fuel power plant.
That said, the largest sailing ship ever, as every true sailor knows is the *Irish Rover*:
With 23 masts, she could outrun the wind and outmanoeuvre the White Whale; and her carrying capacity was every bit as incredible. She hauled all the bricks needed to build the city hall of New York, and in addition, could easily handle a million bales of old billy goats' tails, two million buckets of stones, three million sides of old blind horses hides, four million packets of bones, five million hogs, six million dogs, seven million barrels of porter and eight million bags of the best Sligo rags. She could remain at sea for seven years and pilot herself through any fog. Rocks and shoals were no problem for the *Rover*: she was designed to pull off a *Poseidon* manoeuvre and roll nine times around before she would sink to the bottom of the wine dark.
[](https://i.stack.imgur.com/Z9WGO.jpg)
Since sailing ships of this class are narrower than a modern cargo ship, I'd suggest running three rows of masts: along the center and also along either side.
Your cargo vessel is tall enough above the water line to handle two galleries of gigantic beast and slave driven oars. She'd be a bireme, with eighty oars in each gallery, for a total of 320 oars.
So no worries! Let the winds drive her while they're blowing; and when they're down, put the men to work! In a pinch, fire up the (already firing) boilers to drive her through anything the other means can't!
[Answer]
In a post apocalyptic world there is no reliable supply chain.
Ergo hedge your bets.
* Sail
* Wind Turbine
* Solar
* Steam
* Human
Sail is pretty obvious, install some masts and use the wind to directly impart some motion.
Wind Turbine and Solar provide electricity which can be stored in batteries. The battery could be a water tank which releases hydro power, or something more advanced such as chemical or open air. Either way this energy source has a reliable supply chain, and regenerates even when at sea. Electric engines are also relatively low maintenance.
Steam. Unfortunately a very large vessel requires very large amounts of energy to make it move. As the supply chains are chaotic you won't know in advance what fuels would be available in port, and even how much could be obtained. In short this ship needs to run on everything: coal, oil, diesel, wood, charcoal, plant material, fat, etc... The simplest way to work with such a range of fuel sources is to burn it to boil water to make steam to drive a steam engine. The steam engine could directly propel, or indirectly propel via an electric system/electric motor.
Lastly, no one likes the idea of being stuck in a large ship at the mercy of wind, sun, and no fuel. The final modification would be to introduce a generator that runs on human labour. It will take a lot of effort, it won't be nice, but its better than drifting. Couple that with some sort of energy storage system to build up the energy needed to operate the engines at capacity for a reasonable amount of time. Perhaps that could be coupled with the energy storage system, like a water tank + hydro generator. The human element then would be a manual pump.
Finally the unspoken problem is that a 28000 ton ship needs lots of energy to make it move. A 27000 ton ship needs lots of energy to make it move. A 27000 ton ship needs lots less than a 28000 ton ship. So what can go? As a side-effect what you remove can be sold to help pay for the ships modifications, or be used as the raw materials to remake the ship (so as to not increase the weight after modification).
I imagine a savvy Captain would:
* invest in an Electric/Steam engine plant
* a few masts with a mix of sails and/or vertical wind-turbines on each mast.
* line the sails, and parts of the deck with solar cells
* invest in an electric energy storage system, even something as simple as a water tank/pump/hydro generator to provide some engine power/general habitation power.
* install a human powered electric generator/engine, perhaps a hand pump to move water into the water tower/hydro generator, or some other human powered motor system.
* reduce the ships weight as much as possible
[Answer]
Many answers either don't give you enough energy (oars), require advanced manufacturing (big electric engines) or both (solar).
You could go for biofuel or coal-based fuels, given that those engines run on nasty bunker fuel to start with, but this would require massive quantities of fuel, which is unlikely to be available. Keep it around as secondary propulsion, but don't rely too much on it.
Solar isn't an option (not enough energy in the first place), but wind is. Using sails on such a behemoth is going to be a challenge. And you are going to be limited in your travel direction. Still, it may be a good idea when conditions are favorable.
If you want more flexibility with wind (and go more greenpunk), use wind generators as well, especially [airborne ones](https://en.wikipedia.org/wiki/Airborne_wind_turbine) (assuming the tech matured enough before the apocalypse): they are lighter, can potentially reach higher-altitude winds and are easier to retract in case of storm. You can go against the wind with those, in particular.
But wait, didn't I say that big electric engines were a problem? Well, if you managed to salvage some of those pre-apocalypse ones, you could still be good. However, let's assume you couldn't. Then, go for direct mechanical transmission. Your flying wind generators don't carry big turbines. Instead, they are kites that go up and down, periodically pulling on their line, which then directly (through a gearbox) make the propeller(s) move. Don't get me wrong, that's going to be a complex, maintenance-heavy, potentially breakage-prone (plot! drama!) piece of hardware.
Note that when conditions are favorable and you don't want to wear your hardware, you can put flying sails on your kites instead.
The kites may still have small turbines for onboard electricity, and for powering the kite control surfaces (or even reversing the turbines as propellers to gain altitude). You may also want some batteries for that. If you need only electricity - say, you're at port and want to sell on the energy grid - plug them on generators (or mount turbines on them) instead: many small, fast-rotating generators are easier to make than few giant, slow-rotating ones. Which is, in fact, why you'll see small flying windgens, an possibly solar-thermal, instead of traditional giant windgens on land.
You may want to store energy for dead wind days. If you can, cram a small [power-to-gas](https://en.wikipedia.org/wiki/Power-to-gas) station on the ship using, say, electrolysis and [Sabatier reaction](https://en.wikipedia.org/wiki/Sabatier_reaction) to produce methane on windy days. Note that you'll have to find a way to use methane on your engines.
Now, you tell me, why not have bigger, more efficient power-to-gas stations on land and simply use them to refuel your ship as before? Because it's cool. And because you may not want to count on external infrastructure, but mostly because it's cool.
[Answer]
Swap out the engines for electric motors, wire solar panels / windmills to batteries. Should be doable by an electrician and a mechanic, I just don't know what kind of capacity it will be needed.
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[Question]
[
If an expert of some kind travels back in time to the 14th or 15th century with modern tools and machines that don't require power to work and if he were to past on the knowledge of modern technology to a group of experts from that timeline, could they build an inline engine for use in vehicles and aircrafts? Also, with the knowledge they obtained and the tools and machinery, could they build a helicopter instead if the plane doesn't work?
[Answer]
# There are too many missing technologies
There are several technologies critical to an inline engine that would not have been easily replicated in the 14th century of thereabouts
* **High quality metal**. The block (and cylinders and cylinder heads and bolts, etc) are under high temperature and pressure stress during operation. Metals at the time might not have been able to handle the stress; at least, given the uneven quality of production, not all engines would work. You'd need to wait at least until the development of mass produced iron cannons in the 17th century, possibly until the steel-making changes of the First Industrial Revolution around 1800.
* **Fuel**. The technology to refine crude oil into a useful gasoline by product didn't really exist. Neither does a suitable lubrication oil You would have to get an entire petrochemical industry off the ground by yourself.
* **You can't make the parts**. The crankshaft (along with a cam) is necessary to control the timing of the pistons. That wasn't used widespread in Europe until the 15thc century. Valves and valve springs haven't been invented either. Pistons for compression weren't invented until 1838. Neither have the machine tools to make such finely tuned internal parts. Topping this all off, there does not exist a standard set of measurements which you could use to have craftsmen build parts of standardized sizes.
* **You need a spark plug**. Which means you need to develop the technologies for integrating ceramic and metal into what is basically a capacitor. Also, you need a battery or at least an alternator to run the spark plug. Alternately, you can use compression ignition, but that just makes your metals problems in bullet point 1 that much worse.
You basically need...like....an Industrial Revolution to build an internal combustion engine. So, you can do it in the 14th century, as long as you have a ~1900 industrial base....but then you aren't really in the 14th century any more.
[Answer]
**Yes... and No**
Could you import enough educated people via time travel into the 14th century to build an inline engine? Of course. The metal existed then. The oil and rubber existed then. In other words, there's nothing about the planet, itself, in the 14th century that wasn't also true in the 19th and 20th centuries. So, yes, if you bring enough expertise with you, you can do it.
But what would be the point?
Technology (aka, knowledge) is a pyramid of knowledge and experience, innovation and insight, and at every moment the pinnacle of that pyramid is based on the accumulation of everything beneath it. The amount of knowledge and experience that pinnacle represents is *staggering.*
The smaller the group of people you can import into the 14th century, the more likely the answer is "no." The dependencies involved with technology are deep and unforgiving. Henry Ford (et al) had access to trains, "modern" mining, factories and cities full of people who were competent to work in those factories, universities (the educational pyramid alone is massive), chemical plants, tool manufacturers, etc., etc....
So, unless you can import each and every person you need (potentially thousands), no, you can't build an inline motor in the 14th century.
*Besides, if if you import everyone you need, you wouldn't have the medieval period anymore. It would instantly (within 5 years) be changed to the industrial age. If history has proven anything, it's that keeping knowledge a secret is basically impossible.*
P.S., if what you're trying to do is reinvent Twain's *A Connecticut Yankee in King Aurther's Court,* you should be aware that as you add detail, the story will become less believable. The story is only plausible when you force the tech to exist within the context of the culture, which means you can't have your engine and a believable story. I could be wrong guessing about your motivations, though.
---
**Edit:** A response to a comment made by @Graham brought this succinct point: Assuming you have no limitations to your time travel, you can always import enough people in the right order to guarantee construction of the engine — but that makes the timeline and the culture associated with the timeline irrelevant. The more relevant the timeline, the less possible that engine becomes (likely at an exponentially decreasing rate).
[Answer]
I think a [hot-bulb two-stroke engine](https://en.wikipedia.org/wiki/Hot-bulb_engine) might just be possible. It has no valves, so no need for springs. Instead, it uses the reciprocation of the piston, quote Wikipedia *"by the piston covering and uncovering ports in the cylinder wall"*. Since you still need somewhat high precision, you probably need to produce a working mechanical workshop. Set up shop by a river where you can use flowing water to power your lathe, which you will build from scratch and use to build a better lathe, which you will use to produce your engine.
Since you do not have access to much steel, if any, you need to work with cast iron. So this engine will be heavy and not suitable for airplanes, but for carriages, boats or a (possibly portable) power plant it would be fine.
Since hot-bulb engines run on crude oil, you don't need a petrochemical industry. Hot-bulb engines were usually started with lighter oils or gasoline/petrol, but you could likely distill smaller amounts of "starter fluid" from crude oil or maybe use ethanol. Or just heat the bulb with an external fire until the bulb is hot enough. Once the engine is hot, you can pour in olive oil, bees wax, crude oil, whatever flows and burns, tar oil. These engines are not picky, if it flows and burns it will run on it.
A hot-bulb engine also avoids spark plugs while avoiding the high compression ratio of the Diesel engine, avoiding the need for the high tolerance necessary for Diesel engines.
Regarding measuring, just produce your own reference measuring bits. They don't have to conform to anything in particular, the important thing is that they are internally consistent and that you store your reference bits safely, and only work with copies made from those. Choose metric, imperial, or invent your own system. :)
Since using bolts is another technology which is actually very advanced, use [riveting](https://hackaday.com/2018/08/20/the-forgotten-art-of-riveted-structures/) whenever at all possible.
Edit:
In fact, you may want to bootstrap your engine factory by first producing engines for stationary power plants, so you can build more robust, lower precision engines first. Now, mills and pumps for wells etc can be powered by your invention where there was no power source before.
[These engines also run on wood gas](https://www.youtube.com/watch?v=ST7eDSIdwWU), and wood you should be able to find without a petrochemical industry. :-)
[Answer]
[Valveless pulsejet](https://en.wikipedia.org/wiki/Valveless_pulsejet) is definitely fit for aircraft and you could call it internal combustion one(fuel combusts inside after all).
You do not need high quality metal - ordinary construction steel was used for those and I am pretty sure bronze would work too.
Any plant oil would go as fuel - it was even fed coal dust!
Basically no precision is required - enthusiast just cut steel by hand when make one.
No need for spark plug - fire from previous cycle ignites fuel.
No need for fuel pump - you can use valve to pressurize fuel tank with exhaust from engine.
[Answer]
They could if you teach them how to make materials and all needed tools and parts of said engines and vehicles. And have funds and influence to get it going.
But that would take years to get there.
Tools that do not need energy??? Maybe they have internal power supply? Tools that use your muscles for energy source?
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[Question]
[
Below is a diagram showing transverse cross sections of skulls representative of the two subspecies (A and B) of the Trilateral\* species. **Is it plausible that such obvious differences – noting the rest of their morphology and physiology is essentially identical – could be found within the same species?**
[](https://i.stack.imgur.com/Hn0Rx.png)
\* A placeholder name.
### Background
Trilaterals are quadrupedal [sophonts](https://en.wiktionary.org/wiki/sophont) a little smaller than chimpanzees, and have triple hemispheric (left, right, and posterior, as shown) brains consistent with a body plan evolved from radially symmetrical ancestors. Their 'head' sits atop a narrower, flexible thorax without a discernable neck; a hip-like structure at the base of the trunk supports four legs and two arms.
Trilateral A is the dominant subspecies; B evolved in parallel in geographic isolation. They are capable of interbreeding and producing fertile offspring. There is no statistically significant difference in skull volume or intelligence among mature samples from either population.
[Answer]
# Very Plausible
Creatures of the same species can be pretty widely divergent. An extreme example comes from domestication:
[](https://i.stack.imgur.com/e1rNC.jpg)
[](https://www.chichisandme.com/wp-content/uploads/2016/05/brown-chihuahua-in-grass-holding-a-ball-and-a-womans-finger-with-a-clicker-around-her-wrist-pointing-to-the-ground-shutterstock_545684785.jpg)
[](https://medcitynews.com/wp-content/uploads/2017/04/GettyImages-80602579.jpg)
Yep, those are all the same species. So I think your minor alterations in skull structures will be just fine.
# Evidence for brain changes
To address the issue of brain casings, dogs and wolves have various significant differences in brain structure (reference: [Shoenenbeck and Ostrander, 2013](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3567726/)) Specifically, the limbic system of the wolf is decreased by 30% or more in domesticated dogs. Since this system is associated with 'fight or flight' responses, this may account for the 'how' a wild competitor with humans was able to be domesticated.
Additionally, the recent domestication of silver foxes has been shown to have significant neurological and endocrine effects (reference: [Trut et al, 2009](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2763232/)), such as reduced cortisol levels by a factor of two in the domesticated animal.
Finally, from the same Trut paper, the expressed genetics of the hypothalamus in wolves and dogs are more divergent after a few tens of thousands of years of separation than are the brains of wolves and coyotes (*Canis latrans*) which diverged some two million years ago. So there is evidence that genetic differences in brain structures within a single species (considering dogs and wolves to be single species) can be more variable than differences between two species within the same genus.
[Answer]
Essentially the question is whether the desired morphological changes in the skull could occur before other unrelated changes would accrue that made interbreeding impossible and resulted in speciation. The simple answer is that since genetic drift produces random changes in finite populations there’s no guarantee that some barrier to interbreeding will ever necessarily arise and thus extreme divergences are possible. That said, it might be useful to discuss the factors that will affect the rate of change.
First and foremost the most potent force for evolutionary change is selection. If the two populations have different environments that impose different selection pressures then they will rapidly diverge. An extreme case of this is the domesticated dog which has been intentionally bred into many morphologically distinct breeds at a breakneck pace which would not be found in nature. If the Trilateral B subspecies was subjected to an environment where enlarged posterior lobes were advantageous then the desired changes could occur rapidly on an evolutionary time scale. Perhaps the posterior lobe is involved in olfaction which is more important in the B’s environment. Perhaps B females began to favor males with elongated posterior skulls. Perhaps B’s spend more time in water and the elongated skull proves more hydrodynamic. If you are able to work in a selection pressure (no matter how small) to drive your desired change than there is no reason the subspecies can not differ in this way.
If you want the skull shape change to be unadaptive and therefore random and purely a result of genetic drift things become more questionable. While the main factor regulating the speed of genetic drift will be population size both the desired skull morphology changes and the undesired reproductive barrier changes will be affected equally. A small, isolated population would diverge more rapidly in both areas. Ultimately, which change would be more likely to happen first is a subjective evaluation of which is the “larger” change. By larger here I’m referring to some measure of the number of mutational steps that need to accumulate to produce the change. In my opinion the proposed skull morphology changes are not large enough that they could not occur due to genetic drift before an interbreeding barrier arose.
[Answer]
The interesting thing is I wrote about something similar to this on biology stack Exchange [about ring species](https://biology.stackexchange.com/a/94800/59577) Basically, they are species that are able to interbreed with closely related populations, but there are least two "end" populations in the series. If the trilaterals are a ring species, they can form into two different subspecies that can coexist and live in the same general area, while still being their own distinct subspecies. Like the real-life ring species I mentioned in the link, they may have the ability to interbreed but rarely do for whatever reason. There can still be some geographical isolation, but the isolation could be something either subspecies can overcome, but each one prefers to remain in its own environment and breed among its own kind.
[Answer]
**Yes this is plausible**
There is tremendous variety in nature even within species. Think of the sexual dimorphism in elephant seals and the massive changes that some insects undergo during metamorphosis into butterflies.
Isolated groups of the same species would eventually become different species especially if there were strong evolutionary pressures, but this would probably take a great deal of time. In the meantime your Trilateral A could morph into Trilateral B.
Although it is entirely plausible, it is not always the case. It is also possible for animals to be fairly similar but not be able to interbreed to produce viable offspring such as donkeys and dwarf horses.
] |
[Question]
[
A group of ships I've made are supposed to be modular in design with each modular hull segment being self sustainable both in terms of power needs and crew upkeep (oxygen, food, water, etc.)
I've been split between having the ships house massive reactors, with one or two (for redundancy) in each segment, or having that exact same space filled with hundreds or potentially thousands of smaller reactors.
Assuming the technology level is one that has been able to create fusion reactors that have far surpassed fission reactors, what are the benefits between having a smaller number of larger fusion reactors vs. larger numbers of smaller ones?
I'm looking for answers in terms of total power output per cubic meter of hull space used and manpower needed to maintain them.
Can fusion reactors be scaled up and down like this? Or are there other factors that make fusion reactors lean towards a specific size range?
[Answer]
>
> what are the benefits between having a smaller number of larger fusion reactors vs. larger numbers of smaller ones?
>
>
>
If you have lots of small reactors then, for the same total volume of fuel used between them all, you have a much larger surface area than you do for one large reactor. This means you put more energy into heating up and maintaining your fuel at the ion density needed for fusion. **(So larger>small)**
>
> I'm looking for answers in terms of total power output per cubic meter of hull space used and manpower needed to maintain them.
>
>
>
In terms of power output you will need to redirect more of that power back in to keep the reactors going if you use lots of small ones so the output will be lower. Manpower would be higher for lots of smaller ones too.
>
> Can fusion reactors be scaled up and down like this? Or are there other factors that make fusion reactors lean towards a specific size range?
>
>
>
In principle there is no limit on size up or down (though you would probably need a few technological advancements if you want to start making something the size of the sun). The **larger the plasma** (more ions) the better since you've got a much **higher chance they will hit another ion** before attempting to leave the plasma (though magnets do direct them back in you will get some loss).
[Answer]
As noted in the other answers, there are various trade offs to be made in terms of efficiency and manpower. I'd say the underlying calculus has to be in terms of overhead i.e. how much structure is needed to house the reactors, how many crew members are needed to attend to them and how much space is being used not just for the reactors, but associated plumbing, cabling, control wires etc. How much are you sacrificing for this compared to weapons, sensors, life support systems and so on?
This has to be balanced off by the various threats to the system. Is it very likely that reactors will be hit during a mission? If the supporting structures or infrastructures like radiators, fuel pipes etc. are hit, will this cause a cascade failure? If it is likely that rectors will be hit during a mission, then up to a certain point, having more is better. If the associated plumbing and structures are more likely to be hit, putting the reactors out of commission, then maybe having fewer, larger reactors will make more sense.
One other issue is what is the minimum amount of energy needed to run the ship or a module? If the individual reactors are too small, you may end up in a situation where the remaining ones are funning at full power but there isn't enough energy being produced to actually run the ship or its systems. Larger, redundant reactors which can shoulder the load may be a better choice (just run them at a fraction of their output under normal circumstances).
So a lot of this may depend on the circumstances you wish to introduce for your story, but in general terms, you want the lowest overhead and the ability to run the entire system even if one or more reactors need to be shut down or are destroyed. This would speak to the idea of using few, large reactors.
[Answer]
Consider that a fusion plasma loses energy through its surface, but most of that energy has to be kept and used to fuse the atoms.
Therefore small reactors tend to be less efficient or even not operating at all, in the sense that they won't produce energy but rather absorb it to maintain the fusion.
Also, the more component you have, the more likely is a failure.
So, if you can build it, go single, go big.
[Answer]
Others have contributed good thoughts about the efficiency benefits of a small number of large reactors. Those points are valid and I think you should take heed of them.
I'd just like to contribute a point which heads the other way, as much as anything because I think it might make for some interesting plot devices for your story.
I have no direct knowledge of fusion reactors, but I did work for a while with the largest (by physical dimensions, not power output) nuclear Fission reactors ever made.
An interesting property of physically large reactors is that controlling the reaction becomes harder compared to smaller units. Neutron propagation time across the core becomes significant, so they don't respond to control inputs as quickly as small reactors do. Now I'm not even sure if this transfers to fusion reactors as they are quite different beasts, but if we suppose for a moment that it does, it seems to me that the following might be true
1. your big reactors take time to change power level, so you have a delay before your ship can, say, fully charge it's weapons or employ full acceleration, or jump to light speed if your universe includes ftl travel
2. Maybe you need a mix of large and small units to mitigate 1
3. Large units might be more susceptible to control system damage or breakdown making them unstable and either causing a catastrophic explosion or requiring a shutdown for repairs.
Just some ideas to play with
[Answer]
More reactors throughout the ship would require more in terms of maintenance and crew. Even small reactors would need attention, and if your ships are likely to engage enemies or take damage, you would need far more engineering crews to be able to support the reactors.
A single point of failure (one big reactor) can be dangerous too, since it will likely become the main target of enemies. On the other hand, too many small reactors could be less efficient to shield or protect, potentially meaning an enemy just has to target a few of them to really cause problems aboard(maybe your hypothetical reactors aren't dangerous, or maybe they are -I'm picturing small nuclear explosions all over a ship). Multiple redundant reactors would be a good in between. Not so many that every single person on board needs to be a reactor technician, but not so few that the failure of the reactor is complete power loss. Also, it could provide for a more optimum shielding solution. Yeah, you have to heavily shield a few more things, but at least you won't need that armor all over every little reactor spread through the ship.
With that, the redundant reactors could still be in your modular sections, as needed.
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