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I want a continent of waterfalls: a place on the scale of South America where the land is broken terraces from mountain heights to sea level. And I want massive waterfalls to be ubiquitous, like entire seas spilling over the edge of plateaus.
For ease of discussion, let’s say the high plateaus are at north of the continent with sea level at south.
I’ve worked out to my satisfaction the plate tectonics to get the land mass. My problem is the water cycle. Evaporation and rain is not capable of moving as much water as I want to cycle. I have concluded that I need a water pump.
My idea is massive under-ocean caves at the north end of the continent. The caves allow ocean water to flow over geothermal heat source, which produces massive geysers up to the mountain heights.
My hope is that this geyser system could pump large seas worth of water up for hundreds of thousands of years.
Is this set up viable? If so, is it feasible albeit improbable to form naturally? How long could this setup last?
[Answer]
Unfortunately, this setup is not viable or feasible. It would not be possible for massive under-ocean caves to pump large seas worth of water to mountain heights through geysers for a sustained period of time. Additionally, the amount of energy required to pump such a large amount of water would likely far exceed the energy available from geothermal sources.
In terms of a natural occurrence, it is extremely unlikely for a water pump of this magnitude to form naturally. The forces required to create such a system are beyond what is typically seen in nature, and even if such a system were to form, it would likely not last for hundreds of thousands of years as it would be subject to various geological and climatic changes.
It is important to note that the water cycle in nature is a delicate balance and is dependent on many factors, including precipitation, evaporation, and transpiration. It is not possible to artificially pump large amounts of water in a sustainable manner, as it would likely disrupt the natural water cycle and have significant impacts on the surrounding environment.
[Answer]
**Short answer: Just use rainfall**
A cave/cavern system is not feasible, as @tech show already pointed out.
However, I am surprised that you ruled out evaporation and rainfall. The discharge of the Amazon river is more than ten times higher than the discharge of the Mississippi river. This is entirely created by rainfall. If you would lift up the entire basin, you would get waterfalls up to the horizon (horizontally, not vertically) close to the coast. A few tens of meters should be enough to create impressive waterfalls and avoid altering the climate of the basin. If you are messing with the geology a bit, the amount of water would be even higher. However, I would keep it at a east-west orientation so the whole basin can be in the tropical climate zone. The natural formation of such a system might not be extremely likely, but certainly not impossible.
Edit: Take a look at the [Iguazú falls](https://en.wikipedia.org/wiki/Iguazu_Falls), that visualizes the concept. At this point, the Iguazú river carries ~1% of the water that is carried by the Amazon river at its estuary.
[Answer]
**No**, it is not feasible to pump geothermal water at the scale of multiple Mississippi rivers.
The flow rate of a river is determined by many factors, including the amount of precipitation, the slope of the land, and the size of the watershed.
Geothermal water, on the other hand, is heated by the Earth's interior and its flow rate is limited by the heat exchange at the surface and the permeability of the rock formations. Pumping geothermal water at the scale of a river would require a significantly larger heat source and more permeable rock formations than currently exist, making it unfeasible with current technology.
[Answer]
Both geysers and waterfalls are short-lived on geological timescales. Geysers may not last for a thousand years, as the water deposits minerals in the spout, so they either block up or explode. Large waterfalls erode. The Zanclean flood where the Mediterranean sea filled would have looked like your scene, but that probably lasted a decade.
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**Closed.** This question is [off-topic](/help/closed-questions). It is not currently accepting answers.
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You are asking questions about a story set in a world instead of about building a world. For more information, see [Why is my question "Too Story Based" and how do I get it opened?](https://worldbuilding.meta.stackexchange.com/q/3300/49).
Closed 1 year ago.
[Improve this question](/posts/232559/edit)
There appears to be little credible evidence to support the plausibility of a human being raised by wolves. Even if such cases exist, there would be major issues in the development of said human such as [enculturation](https://en.wikipedia.org/wiki/Enculturation).
Leaving that aside, suppose our goal is merely to give the scenario its best chance at succeeding. I would be curious to learn if the preparations would take the form of trial and error or if there is anything in existing domestication of animals that has any overlap for this task.
## Question
If a group of scientists were given an unlimited timeframe to achieve the feral upbringing of a human, what process/resources would likely be required and why?
**Further clarifications:**
* Quality metric is **long-term** success: If the first few generations
of humans wind up being gobbled up by the wolves, this is acceptable
so long as the study make progress towards viability in later
iterations
* As such, the study is allowed to run for as long as it needs and is
allowed to span the tenure of multiple research teams.
* Success is simply determined by if the child can still be alive after a few years, say at least two. Mental / physical deficiencies can just be assumed out of scope.
* Ideally, the wolf would be at least somewhat feral. Outright domestication is not preferred.
**Configurables (these are the variables you can tweak if it helps you maximize success rate):**
* Species of wolf
* Geographic location
* Age of wolf/human at adoption
* Budget (unlimited budget)
[Answer]
It can't be done in the way of legends with babies being suckled by a wolf.
Wolves don't produce more milk than needed for their pups and they only lactate for about 3 months.
If the child was older it could survive on raw meat for a while assuming it had a supply of it which included plenty of fat. But raw meat has many dangers and it's unlikely that a raw meat diet is sustainable long term without other foods. If the child ate the organs it would give them a better chance for a while, but I doubt 2 years is possible.
Another problem is that raw meat isn't easy to eat. We don't have the dental apparatus for it.
So your best bet is a child who knows what fruit are and a habitat with lots of fruit and berries they can supplement their diet with.
[Answer]
The Wolf-U-Bator(tm) is a translational research spin-off from the Black Tower project. Scientists are developing procedures to 3D print every type of organ from stem cells with defined epigenetic regulatory cartridges added to a base embryonic stem cell line. The goal is to create a reliable replacement organ accurately reproducing a specific individual on demand. (i.e. Kim Jung Un, who was so honored after his attack on San Francisco. The Tower, standing 1.5 miles high over the ruins of the city and ever-growing, its research dedicated to the goal of prolonging his torture *"until the stars pass from the sky"*, is now regarded as the sole holy site of humanity)
The Wolf-U-Bator was one of the experimental prototypes (others targeted cows, pigs, and chimpanzees). The printed organs corresponding to a single wolf were connected via a complex network of blood and lymphatic circulators and electroneural interfaces, until the entire body of the wolf had been assembled and were available for ongoing study in a space the size of a high school gymnasium.
This was followed with further experimentation - swapping one species for another in the network, systematically replacing or concealing all serum proteins and blood antigens. This served secondary research goals, such as developing xenotransplantation protocols that work between arbitrary pairs of animals. Additionally, the decision was made to test human organs in the network, these being manufactured based on data from several Kim family members. Once nanopore antibody pickers had been invented, the availability of sessile bacterial expression systems capable of generating regulated amounts of biomimetic human proteins made this simpler than one would think - out with the old proteins, in with the new proteins.
The project occasionally assembled full models, such as the famous Wolftuar slave troop. Its technology helped inform the main human organ printing project, which generated many of the Kim clones presented for the spring execution festival. However, it remains sadly lacking in the most important aspect, which is replicating the original neural activity patterns. The project failed to fully replicate the complex connections between sectors of the brain, and the organisms on assembly were incapable of normal behavior except when the entire brain was grown *en bloc* in a very primitive fashion. For this reason what had been intended to be a "Ship of Theseus" program to sustain involuntary personal immortality has now degenerated in essentially sequential cloning regime. This creates public displays that are highly popular, but it is profoundly unsatisfactory at the philosophical level. It would disrupt the faith of many were its shortcomings to be widely discussed.
[Answer]
This should be easy enough feral children happened often enough in nature that it should be easy.
1. Get a large dog. Technically dogs and wolves are the same species, but a human raised dog is much more likely to see a human child as family and not food or a threat.
2. Age 6 months to 2 years. The child must be young enough to adapt to being in a pack. Yet old enough that it can provide for itself with a little help from the pack. The oldest feral child I know of was 2 years old when adopted so that's the latest. At the very least though it needs to get around on it's on so 6 months is the earliest.
3. Location a lab were you can control every aspect of the environment.
4. Budget: enough for food and medical bills for the child and dogs.
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Inspired by reading some recent questions about going to space and torchships and such, I've come to the sad conclusion that space is hard and rocket equations suck.
So what if we made advances in a different direction? Instead of getting more efficient fuels and engines, what about reducing mass instead?
This is definitely not a new idea; I remember that the starship [Andromeda Ascendant](https://andromeda.fandom.com/wiki/Andromeda_Ascendant) worked this way - by using anti-gravity fields it reduced the mass of itself and all of its contents to less than 1kg which then was easy to maneuver.
So how realistic is this? Ok, apart from the method itself. Let's imagine that we have invented a handwavium-powered device that produces an anti-Higgs-field-or-something which reduces the mass of all particles within 2m radius to about 0.1% of what it was originally. All other particle properties stay the same - charge, spin, polarization, whatever. Just the mass magically changes.
What would happen when the switch was thrown? Would everything around ir suddenly become featherweight? Or would everything around it disintegrate, because the kinetic energies of the particles would sudddenly be large enough to escape molecular bounds? Or something else?
If a human would be standing next to it, would they live to tell the tale?
I know that gravity at quantum scale is negligible, but mass also affects acceleration and maybe some other things, so I'm uncertain of the final (macroscopic) effect.
[Answer]
It would reduce the mass of the W- and Z-bosons in the atoms that make up your body by a factor of 1000. Which would - due to the uncertainty principle - automatically increase the range of the weak nuclear interaction by a comparable factor. The range would be long enough for the weak force to compete with the electromagnetic forces that hold your atoms together. I have no idea how you would die, if you would explode or desintagrate, but whatever would happen in your body it would have nothing to do anymore with any physical processes we rely on to exist.
[Answer]
A regular human has about 5 kg of blood, pumped to a pressure of about 120/80 mmHg.
Suddenly you have 1/1000th of the blood mass being pumped to the same pressure. That outta hurt. The air around you also has a very rapid drop in mass, and hence a linearly proportional drop in pressure. [Last I read about something similar was an incident in 1983, in which some divers went from 9 atm to 1 atm instantly due to someone disregarding safety measures.](https://en.wikipedia.org/wiki/Byford_Dolphin) This would still be more gentle than your method:
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> Medical investigations were carried out on the remains of the four divers and of one of the tenders. The most notable finding was the presence of large amounts of fat in large arteries and veins and in the cardiac chambers, as well as intravascular fat in organs, especially the liver. This fat was unlikely to be embolic, but must have precipitated from the blood in situ. The autopsy suggested that rapid bubble formation in the blood denatured the lipoprotein complexes, rendering the lipids insoluble. The blood of the three divers left intact inside the chambers likely boiled instantly, stopping their circulation. The fourth diver was dismembered and mutilated by the blast forcing him out through the partially blocked doorway and would have died instantly.
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> Coward, Lucas, and Bergersen were exposed to the effects of explosive decompression and died in the positions indicated by the diagram. Investigation by forensic pathologists determined that Hellevik, being exposed to the highest pressure gradient and in the process of moving to secure the inner door, was forced through the crescent-shaped opening measuring 60 centimetres (24 in) long created by the jammed interior trunk door. With the escaping air and pressure, it included bisection of his thoracoabdominal cavity, which resulted in fragmentation of his body, followed by expulsion of all of the internal organs of his chest and abdomen, except the trachea and a section of small intestine, and of the thoracic spine. These were projected some distance, one section being found 10 metres (30 ft) vertically above the exterior pressure door.
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If the drop in pressure does that to humans, it also does that to objects. There are plenty of videos in Youtube of people playing with vacuum chambers. Just imagine those things happening much faster.
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[Question]
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**THE DRAGONS**
When standing on all fours, a typical full-grown dragon is about 3 times as tall as a human. They are quadrupedal with opposable thumbs, with four legs and two or four wings, and can reasonably be expected to remain in the air for at least several hours at a time (and that's the low limit for sick or malnourished dragons). They are broken up into a slew of sub-species, all of which share the above traits.
Some dragon species can breathe fire, but no dragon sub-species has inherent fire resistance. There are a few other 'inherent' abilities like ice breath, a venomous tail stinger, breathing underwater, and silk-weaving. Also, some of them have 'superpowers' of sorts that are not normal for their sub-species, such as super-hot scales, mind-reading, future sight, or the ability to communicate with plants and accelerate their growth due to circumstances of birth or genetics.
They are social creatures, and their societal structures at the moment are largely made up of Medieval Monarchy-dominated kingdoms. By some fluke of convergent evolution, they ended up with emotions, thought patterns, and psychologies nearly identical to humans despite having started at the top of the food chain rather than the middle.
They do know that some humans exist on the planet with them, but in their minds, humans are prey creatures noteworthy for making little metal daggers and wood/stone dens for themselves. They are technologically and socially behind the dragons, and the dragons have absolutely no clue that other, crazy-advanced humans are hanging around up in orbit. The realization that there are humans up on a metal palace in the heavens who have unlocked the esoteric secrets of trapping and harnessing lightning, traversing sections of the sky where the air is thin enough to cause a dragon to suffocate, and giving traits from one creature to another is going to come as a big shock to the dragons.
**THE HUMANS**
The humans abandoned earth in favor of a space station in earth's orbit for a time due to an incoming extinction event, and the dragons evolved and took the humans' place in the grand scheme of things while they were gone. During this time, the general difficulties of space forced them to revert to an authoritarian government. They've begun to scout out the earth to see if it's habitable or not, and haven't revealed themselves to any dragons or humans on earth yet.
Human technology stagnated during their time in space due to resource-conservation measures, but still managed to reach near-futuristic levels. They have reliable spacecraft (that are sadly not capable of FTL travel), holographic projectors that can be paired with motion sensors for a 3D interface or used to cloak a ship from view, tiny chip-like implants that can monitor vitals and brain activity, several dozen 30-foot tall mecha similar in appearance to Fortnite's B.R.U.T.E.s that can outclass a typical dragon in raw strength, and experimental Directed Energy Weapons that are actually fairly practical as weapons if a tad unreliable. However, they still walk around, mainly use weapons that utilize bullets as ammo, and are reliant on hydroponic gardens for food and mining ice off the moon for water. They haven't changed much, aside from limited forays into genetic engineering; they have yet to figure out how to make entirely new DNA, but they can 'map' known DNA patterns from one organism onto another organism OF THE SAME SPECIES, which allows them to cure genetic disorders.
Note that the humans are capable of communicating with the dragons through a 'translation device', despite the fact that neither of them is capable of speaking the other's language, but as a general rule they don't bother communicating.
The humans have a pretty distinct technological advantage over the dragons, but the dragon's abilities might tip the power balance back in the dragon's favor, and the humans are aware of this. And this is added to by the fact that there is only a quarter as many humans up on the station as there are dragons down on the surface.
**THE SITUATION**
When the humans first sent down their scouts to assess Earth's status, they were pleasantly surprised to learn that their homeworld was habitable and some of their kind had survived, albeit in a primitive state. Unfortunately, the humans had been ousted from their top position in the game of life in favor of dragons, who have all the advantages of sentience and opposable thumbs paired with the fact that they are 20-foot, tall apex predators. In fact, the Dragons even hunted the humans who remained on earth for food or kept them as pets! So the humans decided not to descend back to earth en mass, thinking that a cautious approach was best.
The dragons quickly perked the human's interest. For one, they are, much like bees, able to fly despite the fact that conventional physics tells them that their wings wouldn't allow them to. Plus, they'd really like to figure out how to get some of the dragon's abilities (anyone in favor of getting Telepathy?).
Now, to get these abilities, they need to map dragon genes onto their own genome, and to figure out how to do that do that, they need to do some experimentation. And the human in charge concluded that the most efficient way of going about that is to abduct live dragons seemingly at random from the planet and subject them to horrifically inhumane medical experiments that often leave the dragons dismembered, traumatized, and/or dead. Some humans objected, but those who did were quickly and violently silenced.
But, naturally, the humans who objected weren't the only ones who didn't approve of this. The dragons, much to the shock of *NO ONE EVER*, wouldn't go quietly to this grisly fate. And that leaves my main question: **What physical restraints would these near-futuristic humans use to keep their dragon test subjects under control?** I'm asking for what materials they'd use, but also what shape they'd be and what features they might include in the restraints.
**CONSIDERATIONS**
The physical restraints in question need to fit a few criteria; please take these criteria into account in your answers.
1. **The restraints can't be slipped out of easily.** If there is a way to slip out of or break the restraints that doesn't entail significant self-harm, the dragons are going to try it, and some of them are going to be successful. And that means a scared, stressed-out dragon running amok in their labs, breaking all sorts of expensive equipment and causing harm to others and possibly itself in its frantic search for a way out.
2. **The restraints aren't prohibitively resource-intensive.** These humans aren't suffering from any completely crippling resource shortages, but they do not have infinite reserves of resources and are VERY aware of this. The restraints need to be able to do their job, but they also need to do so without requiring a ton of resources to produce and implement.
3. **The restraints need to not interfere too much with experimentation.** The humans want to be able to run experiments on the dragons, and that means that the humans must be able to preform surgical procedures/injections on them and transport them to different rooms for testing purposes without undoing the restraints too much. Metal cages and crates simply won't work for this.
4. **The restraints shouldn't cause harm to the dragons.** This is because they want to keep some degree of restraints on the dragons at all times, for identification/tracking purposes. The reasons stem more from practicality than from any concern for the dragon's safety; kind of hard to figure out how much of an effect a given drug is having on a dragon when it's bindings are tight enough to restrict blood flow, and you don't want your dragon test subjects choking to death because the collar is too tight. This does not mean the restraints have to be comfortable.
**EDITS:**
It's important to note that while humans have absolutely no compunctions about killing dragons during experimental procedures, they are a little bit more hesitant about killing them OUTSIDE of experimental procedures. Each dragon they abduct represents a risk of exposure, and they're not going to kill a dragon if they don't think they'll get some interesting info out of it beyond the autopsy.
By near-futuristic technology, I mean any technology that we could conceivably develop given 100 more years or so of technological progress.
[Answer]
**Type of restraints is dictated by what experiments you want to do**
You want cost-effective, dependable and harmless restraints, but they aren't really necessary from the beginning, you don't need state of the art technology for basic experimentation, so i will disregard a "harmless" part in a few places. But, i will also provide a pretty advanced set of restraints, meeting the requirements, later in this answer. But if you want to be cost-effective don't develop new technology if you don't need it at the moment, use what you have, if this doesn't bring results, think of something new. (Also, when i use words cost-effective, cheap, expensive, i refer to the 2nd consideration of "resouce-intensive")
**Start with severing the spinal cord**
It's easy and reliable, paralyze dragon from the neck down and use machines to keep it alive. You'll probably need a few tries to be able consistently do that, but there are more than enough dragons. Sure, they won't be able to control their urination and defecation, also body will eventually start to break down, but this method is meant for short-term experimentation aimed to develop general theories about dragons' biology, let's say it's a step-up from autopsy. It's also the safest one, dragon can't really pose a big threat in this situation.
**Screw with their bones**
Literally, use metal (or whatever sci-fi material is best for this use) to lock dragon's joints by screwing together neighbouring bones in wings, legs, tail, skull, etc. If done right it will immensely restrict dragon's mobility, preferably not 100% to allow dragon some movement for "health benefit" but you can also just immobilize them. It doesn't harm body in a short-term, eliminates need for machines to keep subject alive and allows you to experiment on basically unchanged body, assuming human surgeons are able to do that without causing infection. It is not perfect for long term experimentation, but better than severing spinal cord. Also makes it hard to escape, even if dragon would break free it would shatter it's bones.
[](https://i.stack.imgur.com/KjG4C.png)
something like that, but im not a specialist in implants
**State of the art restraints**
In this one im adhering to all your instructions and making full use of sci-fi setting. I came up with modular restraints created of metal and nanomaterials, using pressurized liquid or gas to conform to dragon's anatomy and using friction to make them unescapable. Nanomaterials, because this way you can stretch your resources, you can use cheaper base components, molecularly engineered to be much stronger.
[](https://i.stack.imgur.com/monh9.png)
1. Limb
2. Metal rings - Attached to the frame, their main role is not to restrict movement but to provide support to inflatable sleeve
3. Inflatable sleeve - Made of flexible and durable nanomaterial, pumped full of liquid when used, might possibly contain life function sensors inside.
4. Valve - Used to pump liquid/gas into a sleeve, could also serve as an access port to sensors inside sleeve
5. Metal frame - Providing stability and possibly allowing moving dragon's limbs into different positions by researchers.
6. Possible structure of inflatable sleeve's surface for maximizing contact with dragon's scales, sleeve's interior surface is similar to gecko's foot, it's role is to maximize friction to disallow any movement inside.
7. Hydraulically operated limb access port - most probably sleeve's interior would be divided in many sections, it could be used to create access ports operating similar to leaf's stoma.
There are many sizes and shapes of sleeves, which allows to completely restrict dragon's movement, by inflating them they can conform to wide range of shapes and sizes. Assuming dragon's are cold-blooded, you could cycle cold water trough sleeves to make them drowsy and more compliant.
**Extras**
How to recycle your dragon ? When dragon dies and you don't need it's corpse just throw it into meat grinder and feed next dragon with it. By doing this you can also research effects of cannibalism on dragons, them having their own Kuru disease could be important
How to store your dragon ? If you need to store living dragon on the space station, i would suggest external sensory deprivation tank. Cycle cold water of the similar density as dragon's body through the tank to slow down it's metabolism and make it docile then put it outside the station (if possible) mounted on some vibration cancelling supports, thermal insulation is not really that important in space, but tanks should be shielded from radiation. Also if something fails and dragon escapes it will just die in space. You will also have opportunity to research influence of isolation and sensory deprivation on dragon's brain activity, if you need it to be more awake just warm up the water. Dragon in this state would also need relatively little nutrition.
Also, dragons have no chance against humans. At least in my opinion, humans can just throw rocks at them from orbit, destroy their kingdoms with relatively minor damage to earth, then exterminate the rest either with brute force or biological warfare (pathogen custom tailored to kill dragons). But that's just my opinion.
Hope i helped.
[Answer]
**Twitch**
[](https://i.stack.imgur.com/zMA6j.jpg)
<http://www.tackntails.com/2013/11/twitching-more-than-just-rope-on-stick.html>
<https://en.wikipedia.org/wiki/Twitch_(device)>
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> The twitch is popularly believed to work by distracting the horse, but
> may act instead by triggering the release of endorphins from the
> horse's brain, producing a calming effect.[3] It is hypothesized that
> its effects are similar to acupuncture.[1](https://i.stack.imgur.com/zMA6j.jpg) The twitch is considered a
> humane method of restraint and is commonly used by horsemen and
> veterinarians to keep an animal still and quiet..
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Your dragons would be fitted with a twitch, which works on them like Larry Niven's tasp. They become mellow. They look silly and the humans giggle. The dragons don't care. They are humanely restrained and can receive veterinary care.
[Answer]
**Lovely Sedatives**
[](https://i.stack.imgur.com/Fhlztm.jpg)
Your spacemen have advanced biological engineering. They can map one animal's genome onto another, to give the new animal different legs and arms and wings and superpowers.
The spacemen are better at other biological things too. Like making futuristic sedatives.
The stuff in the blue syringe will put a dragon into hard suspension (a) without stopping its heart permanently; (b) so it can be woken up at a moment using the red syringe; and (c) so the stress of being repeatedly sedated and woken does not destroy the animal's brain.
When we need the dragon awake for experiments, we put on conventional physical restraints. Sometimes that means manacles and chains. Maybe a muzzle. Sometimes it means a dragon sized straitjacket. Sometimes it means a cloud of iron nails in the creature's hide and a big electromagnet.
Once the restraints are on, we use the red syringe to wake the dragon. When we're done we jab the dragon with the blue syringe, fold him up, and put him back in his storage drawer.
At least we USED to use the restraints. It turns out they are unnecessary. Blue induces euphoria in the dragon and is addictive enough that after a few jabs the dragon becomes compliant. He obeys all instructions. He wants to go back in the drawer you see. The faster the experiment is over the faster that happens.
[Answer]
## A Judas Dragon
One dragon with the ability to mind control / induce sleep / incapacitate other dragons has been bribed or otherwise induced to work with the advanced humans.
Combine with other powers like future sight and/or his own personal motivations (Greed? Factional rivalry? Hostage hatchlings? Researching the humans? Addiction? An unbreakable vow? A failed dragon romance? A romance with a human woman? Unbridled lust for silk weaving supremacy? A strategy to save the other dragons?) to generate plot arcs as needed.
The degree to which the Judas dragon's powers work on humans can also be customised.
[Answer]
## Low Temperatures
Maybe dragons go incredibly sluggish when cold? After all, why else was their ice breath such a useful weapon? A variant on this has them extremely resistant to cold but only until a certain threshold temperature (maybe an enzyme malfunctions), or resistant to low temperatures but not to sudden *changes* in temperature.
Dragon flies into a box full of dragon lollies and is snap frozen / thermally shocked with liquid nitrogen. Liquid N2 is not hard to make.
Electricity could be an alternative or complement.
## A sensitive organ
Lifting this one from the Tripods / White Mountains trilogy I read as a child. There was a species of alien that was generally superior to humans but that could easily be killed or knocked out by a bit of pressure on the right spot on their lower back. They foolishly hired humans as masseuses and one of them found the spot.
The humans just have a strong servant grip the dragons protruding nerve sac.
## Plain old steel manacles
Dragons are still ultimately made of meat. They aren't breaking 20mm steel manacles any time soon. Plain old mild steel. 1 on each foot, 1 on each wing, 1 on the neck, probe away. Handy when they thaw out from initial capture. You could be extra inventive and have someone with a sedative dart gun or dragon taser on standby.
Note that it is utterly impossible to slip out of neck manacles. Wing manacles and leg manacles ought to be no different. It worked on people for centuries.
Straightjackets are another option.
[Answer]
# Brain stimulation reward
In Larry Niven's Known Space universe, there is a simple electrical device called a droud that directly stimulates the pleasure center of the human brain. There's a pretty good short story where the bad guys basically do a "French Connection" on someone, who then willingly sits still and starves to death under the influence of the droud they forcibly placed on him.
Very importantly, this is *not* science fiction. In the real world, it's called "[brain stimulation reward](https://en.wikipedia.org/wiki/Brain_stimulation_reward)" (or "BSR"):
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> Scientists have successfully performed brain stimulation reward on rats (1950s) and humans (1960s). -- [Wikipedia](https://en.wikipedia.org/wiki/Wirehead_(science_fiction))
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The absolute best thing you could use to pacify a creature while you vivisect it would be a whole-perception replacement, something like the brain-jack used in *The Matrix*. But that is a really high technical hurdle. (It might not even be possible.)
By contrast, if your humans have spacecraft, they almost certainly have the tech they'd need to discover the location of the pleasure center in a dragon brain. (As noted above, real-world humans accomplished this in the 1960s.) Then they'd need to build an implantable device that applies an electric current to that location. And then they'd turn the device up to 11:
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> This stimulation does not appear to lead to tolerance or satiation in the way that sex1 or drugs2 do. -- [Wikipedia](https://en.wikipedia.org/wiki/Wirehead_(science_fiction))
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> 1 & 2: Speak for yourself, bub!
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### How would this be accomplished as a practical matter?
#### Phase 1 : Taming
You begin by taming a dragon. Lure it with foods it likes, and make no move to capture or harm it. Do this repeatedly.
Once it trusts you enough to hang out near you all the time, begin to deliberately spoil the dragon all day every day: provide it with its favorite foods and all the creature comforts you can devise. Spare no expense. Have people working in shifts to rub its tummy, scratch behind its ears, etc. Bring the dragon all its meals, more than it can possibly eat. Never let its cup sit empty.
#### Phase 2 : Brain study
Do this, with absolutely no dirty tricks, until you can get the dragon to sit for an MRI. It does not need to be conscious for this, it just needs to be stationary. Perhaps it's even possible to use classical conditioning to make it sit perfectly still.
While it's sitting for the MRI, give it some physical pleasure. This may be as crude as providing some kind of sexual stimulation. If it were cat, I'd just stroke its belly. Do whatever you can to cause pleasant sensations for the dragon. (BTW, identifying those things is something you have have *plenty* of opportunity to do during the taming phase.)
Now you know where a dragon's pleasure center is.
#### Phase 3 : Actual brain surgery
The droud is a pretty simple device: just an electrode that can be attached to the pleasure center, connected to a wire that runs from the electrode, out of the cranium, to a base electric device that controls the electrical current. You can build this while the other phases are underway.
The difficult part here is making the dragon sit for brain surgery. If you have any kind of drugs that work on dragons, use them. If you have poisons or chemicals that can incapacitate them, use that.
Physically restrain the dragon while it is doped-up or paralyzed. These restraints do not need to hold the dragon forever, just long enough for your surgeons to puncture the skull and insert the electrode. This may need to be done roughly, which is helped by the fact that you don't really care about the dragon's well-being.
The second you get that electrode in there, turn on the droud. If it's placed right, this will calm the dragon. If that happens, you're home.
#### Phase 4 : Do your evil Mengele stuff
Keep the dragon in this state for the duration of your horrible experiments. Feed it intravenously if possible; otherwise, keep it on a liquid diet that you can pour into its open, slack-jawed mouth.
The first thing I'd recommend is to locate the pain center, so you can disable that.
Every time you're going to mutilate the poor creature, turn up the droud enough to drown out any pain the dragon might experience. It may take some experimentation to figure out the right settings; until you get it right, you can always just turn the droud up to a setting just short of physically damaging the brain.
#### Phase 5 : Get those sigmas
At some point you'll want to repeat this with other dragons. I'd try to fashion some kind of helmet with a retractable electrified spike in it, located in just the right place to reach the pleasure center, the idea being that you can slip this helmet on a sleeping dragon without alarming it, and then immediately drive the spike into its pleasure center.
This probably requires a custom-made helmet for each dragon because of small physical differences. The necessary measurements are non-invasive, so you can take them during the tail-end of each new victim's taming phase: just have a couple of guys bring a big measuring tape along when they go to stuff more ambrosia into the unwitting dragon's mouth.
[Answer]
Formulate a special drug with anesthetic properties. Tranquilize the dragon and then inject it with the drug. The drug should keep the dragon in a state of semi-conscious, but unable to move about. When it is about to wear off, simply inject another dose of the drug.
This would only work for experiments that do not involve cognition of pain, mobility, or other such things. However, it would be very effective for keeping the dragon quiet and still for a short-term period.
You could also store the dragon in a cage of some form when not being used for experiments. During this time, the dragon would be able to eat and drink as normal. Then, when needed, all that would have to be done is to inject it and wheel it out of the cage.
[Answer]
## The dragon-burrito
Many animals can be successfully restrained and soothed by wrapping them in a blanket, thus immobilising their limbs:
This works well for winged animals, too:
Of course, you can't have them look so adorable or you'll never have the heart to experiment on them. What you'll use will be something between a straitjacket and a piping bag open at the front (warning: [actual experimental animal restraint devices](https://www.braintreesci.com/restraint-containment-handling/restraint/rat-restrainers/decapicones/), upsetting if you, like me, like rodents). You can make them out of high tensile strength cloth, or a net of sturdy material like metal chains, appropriately padded. You can inject directly through the cloth or into the gaps in the net, and for larger surgery sites you can cut a window and/or undo some links. You may need a muzzle for the fire-breathing thing, though.
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[Question]
[
I have a scene where a fleet of ships activates thier [Alcubierre Type Warp Drives](https://en.wikipedia.org/wiki/Alcubierre_drive) to flee from an enemy fleet, but unlike many sci-fi settings where a warp drive instantly pushes you up to superluminal speeds for a quick get-away, in this setting, you have to accelerate to superluminal speeds over time; so, there is a window where you can have an active warp drive, but until you break the light speed barrier, you can still be shot with conventional weapons. This means that as they flee, ships will be getting taken out by enemy lasers while technically moving at warp. So, what I want to know is how the presence of a warp bubble will effect what it looks like when these fleeing ships explode.
An Alcubierre Drive in this setting is defined as a [reactionless propulsion system](https://en.wikipedia.org/wiki/Reactionless_drive) that manipulates space-time such that the area in front of your ship resembles an extreme positive mass density, and the area behind it an extreme negative mass density. This causes the ship to "fall" perpetually in the direction of the positive mass density. For purposes of this question, we will assume the toroidal shaped warp field represented below.
[](https://i.stack.imgur.com/92UEt.png)
You can also assume that the Alcubierre Drive's mass density bubble is maintained by (*insert clarke tech here*) that if spontaneously shut off or destroyed would cause spacetime to snap back to its normally flat self at approximately the speed of light. This would presumably cause some intense [gravitational waves](https://www.ligo.caltech.edu/page/what-are-gw) to ripple out from the event. This does not necessarily mean that the warp drive of the ship will be the first component to fail; so debris from both before and after the warp drive fails should be considered, but the part of this event I am most interested in is the gravitational wave pattern formed by the collapse of the warp field, and what effect they would have on the debris field pattern of an exploding ship.
[Answer]
The Alcubierre metric consists of two causally isolated regions of space: the inside of the bubble, and the outside. Within each region, space behaves as you would expect for normal relativity, only moving at subluminal speeds, with well-understood relativistic mechanics. It is the bubble itself that moves superluminally and paradoxes are avoided because the two regions are causally isolated from one another meaning there is no path by which anything can enter or exit the bubble (which is why, contrary to pop-sci articles, the Alcubierre metric could never be used as a means of propulsion).
If a ship inside the bubble explodes, everyone inside the bubble sees exactly what they'd see if there was no bubble - an explosion in space, whilst people outside the bubble would see nothing, as they cannot see in. If something outside the bubble explodes, the situation is reversed, with everyone outside the bubble seeing a normal explosion, and people inside having no way to see out.
Given your final paragraph, if the ship's explosion destroys the bubble, you'll end up shrinking the bubble to 0-size, destroying all inside, and having to dissipate all the energy stored in the bubble, and the mass of its contents. Absent any net charge, this would through gravitational waves, albeit of a very unusual kind. As nothing outside the bubble can see into the bubble, I would expect this wavefront to be spherical, but you could make it whatever shape you choose by tweaking the way in which the bubble collapses when the ship explodes.
[Answer]
## No effect at all
You have defined an engine that is **"a reactionless propulsion system"** and then asked what the reaction of the propelled explosion particles will be. All the forces of general relativity will act on the particles, and no force at all will be imparted onto the particles from the deformation of spacetime. It's actually in your own definition.
Everything will follow the exact vector it was given by the combination of its relativistic momentum plus the explosive force.
I should add that properly, your ship’s relativistic momentum while using a reactionless drive (propulsion is a misnomer here) should be zero, by definition. This is why every sci-fi that used a consultant were told to “instantly go to light speed” in the trope you want to avoid. It begs the question, why use Newtonian forces at all?
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[Question]
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I have a canyon, with similar size and shape to the [Grand Canyon](https://en.wikipedia.org/wiki/Grand_Canyon). The canyon is carved by a large river, similar to the Colorado river.
I want this canyon to be filled with fog so thick that, if you are standing at the top, you can't see the bottom.
I would prefer the Canyon be
* Not too cold at the bottom
* Livable, if not nessecarily comfortable, for human life (ignoring growth of crops or anything like, just that someone wouldn't die if they went down there)
* Completely, or if this is not possible, very dark at the bottom of the canyon, even at noon
Is this possible? If so, what do I need to do to create it?
[Answer]
**Valleys can totally be full of fog.**
[](https://i.stack.imgur.com/GTfev.gif)
<http://www.personal.psu.edu/users/m/d/mdw5005/meteo481.html>
Grand canyon size is perfect. A river runs thru a desert. It comes a long way and it is shallow; the water is warm. As the river goes along, the valley gets deeper and deeper because the land is rising - the river has been there a long time and has cut a deep channel.
Farther along the course of the river, the highlands now on either side of the river have cold air. It rolls down into the valley and hits the humidity coming off the warm river. Fog is born.
If you want to fantastic it up, have a geothermal spring contribute its boiling water. That will make some steam. Such rivers exist!
[](https://i.stack.imgur.com/fIKCz.jpg)
<https://www.sciencefriday.com/articles/amazon-boiling-river-microbes/>
[Answer]
To get large amounts of fog/cloud you need large flow of warm moist air to be then be cooled in the target area. Easiest is with preexisting volcanism to supply the energy.
### Scenario one: Older yet still active volcano.
A large volcano near a large body of water, on the down wind side. This will ensure valleys will have rivers due to high rain fall. Then the volcano needs to be still active/have and there to be lava near surface. If molten rock is near surface close to one or more rivers near the base of the volcano then there would be a source of warm moist air, along with cooler air in the valley bottom.
This implies basaltic lava and newer igneous terrain which tend to not form large canyon systems. This would scenario would tend to have smaller steeper valleys. But more common then scenario two.
### Scenario two: Broad hotspot.
A hotspot such as Yellowstone or Hawaii. A river flows through the region which is heated up and provides warm moist air, upon mixing with the cooler surrounding air, clouds form. this is similar to scenario one but assumes a broader area and more flexible terrain. A hotspot can move under sedimentary rocks where grand canyon like valleys can be carved.
This could allow closest to requested features of terrain but would be least likely to have contentious broadly covering cloud. It would be less continuous due to more opportunities to have broad mixing of air. This would imply shifting locations of cloud/fog.
### Scenario Three: Mad scientist secret hideout.
To hide secrets, a nuclear power plant is installed in a valley. A system of piping is installed to release steam throughout the valley thus ensuring permanent thick clouds. The planned nature of this allows for much more consistent and thicker cloud cover.
This would have the highest consistent density of cloud by far thus providing the most shade. However this is an deliberately engineered outcome, which might not fit desired plot.
### Conclusion
There are other scenarios that are possible. But to get reliable thick cloud/fog a reliable energy source in close proximity to water is required.
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[Question]
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To give an example, I have this species of elk minotaur, they are mostly human looking but have a elk/deer head, ankles and hooves. (image source Raid Shadow Legend concept art + my low poly model)
[](https://i.stack.imgur.com/XUJZH.png)
If I wanted to know their eyesight and intelligence or other stuff I could just make it up since it's not something that is always obvious just from observation. But things like how though they are should be clear just from intuition by looking at the body structure and skin texture. So I could say that minotaurs have a toughness of 1.20 when compared to a human, the human being the default for the value of 1.00 , just throwing a random number.
**How does this question relate to world-building?**
Knowing how your creatures differ from humans makes it easier to create cultures as all you need to do is look at things that already exist on our planet and edit them a little bit based on clear variables.
**Is this question opinion based?**
I'm looking for anatomical information, I don't think this qualifies as opinion based unless anatomy is not a clear science.
**What is my actual question?**
Other than thoughness, what other things are obvious just from looking at the appearance, height and weight of a creature? like if hypotetically things like lifespan or ability to speak are usually obvious just by appearance or if maybe I'm wrong and almost nothing is obvious by appearance alone?
**What qualifies a good answer?**
A list of 2 or 3 factors which are obvious from appearance and have a strong influence in culture and the relationship between humans and other creatures, to make it less broad, focus the answer on my minotaur example.(This is just an example not another question) like, is it visibly obvious when a creature has a certain diet just by looking at their body or could something have the appearance of a predator and not be much of a meat eater?
**What qualifies as the best answer?**
The baseline for what qualifies a good answer, plus If there is any, a source on how to learn and study such things with ease on my free time. Not something that I need to dedicate my life to in order to study and understand it, or at least a brief explanation of this concept that I and other users who don't know much about external anatomy could easily understand and apply to their future creature designs.
[Answer]
Yes, you *can* tell a lot about a creature just by looking at it, if you've made a study of zoology as I have. Indeed, the best way I know to learn how to pick details from the image, corpse, bones or teeth of a creature is to study zoology at university level... or at least read the text books.
You can tell quite a bit about an animal's eyesight and even its habits just by looking at its head. For example, those minotaurs have a typically bovine-appearing head, with the eyes on the sides of the head. This is an adaptation to being prey, giving a wide field of view so as to better be able to spot predators sneaking up for the kill. It comes at the cost of a near-non-existent arc of binocular vision. This is at odds with the mythology surrounding minotaurs, that they are carnivorous and hunt their prey. However, some pictures of minotaurs *do* show that they have more binocular vision than a cow.
The size of the skull and brain case in comparison to the size of the body is an indicator as to the intelligence of the creature. Intelligence requires brain tissue, and while the actual volume of brain tissue may vary considerably for a given level of intelligence, intra-cranial volume is a strong indicator. In the case of these minotaurs, they are likely not particularly more intelligent than a cow, given their quite bovine-shaped skulls. However, as the processing ability of the mammalian brain is dependent upon the surface area of the cortex, there is the possibility that the cortex is highly convoluted, having a much higher surface area than a cow, and therefore higher intelligence. They still wouldn't likely be as smart as humans, though.
We don't see these creatures' teeth. They are very important to be able to tell what they eat and how they digest their food. Minotaurs are supposedly carnivorous, so we would expect carnivorous dentition: sharp incisors, long canines and shearing carnassials all adapted to eating meat. However, they *might* also be herbivores, however their body form suggests that they don't have a sufficient large digestive system to be herbivores. Perhaps they could also be omnivores similar to humans.
That these creatures have antlers like those of a deer is suggestive of their mating habits. Antlers such as these are evolved to interlock with those of another male during dominance contests as a prelude to mating during the breeding season. This helps prevent serious injury during the conflicts, making them more about strength than luck or skill. This is then suggestive that these beings don't actually want to kill each other when they fight each other, that such battles are more about dominance than eliminating a foe entirely.
The bodies of these creatures also bear out this supposition. They are humanoid, but have robust skeletons with a great deal of muscle mass. While they have cloven hooves, which originally evolved to lengthen the legs and increase stride length and speed, that their legs seem short and thick suggests that they are evolved to be able to exert great force at the expense of speed. They would be able to accelerate quickly, but wouldn't likely have a maximum speed much higher than that of a human.
Their broad, deep chests are covered in muscle, as are their arms, indicating that they likely use their arms for wrestling during these mating conflicts, but the size of the chest also shows that they have a large set of lungs and likely a large heart too, meaning that they are likely capable of prolonged exertion.
That these beings are furry suggests that, unlike humans, they do not have the ability to sweat, and therefore the main limitation on their ability to exert themselves for long periods of time is that of thermoregulation. Prolonged exertion would generate heat that they are just not as capable as humans at eliminating, and therefore they would likely overheat before they went into oxygen debt. They might be able to maintain a chase for some time, but as they would have to rely on panting for thermoregulation rather than sweating, they would not be able to keep up with - or outdistance - a trained human runner over any great distance. They're short and middle-distance sprinters, not long-distance runners.
Fur is suggestive of their preferred environment. If they lived in particularly cold areas, their less-than-human thermoregulatory abilities would be offset by the potential to rapidly lose body heat by flattening down the fur and flushing the skin with blood. By withdrawing blood from the skin and erecting the fur, greater insulation would be achieved.
Finally, carrying weapons suggests that these creatures are territorial, and reserve their violent tendencies for foes of other species.
However, as illustrated, these beings' physiologies don't appear to match their supposed capabilities or even their likely habits given their physiology alone. They seem poorly designed rather than naturally evolved, and it seems likely that they would not be a particularly successful species.
[Answer]
* You can see if the creature is armored or not: a pangolin, a turtle or a hedgehog are clear examples of creatures which one can unmistakably qualify as armored.
* Likewise, you can see if the creature has horns, fangs, claws, talons or anything else which can pose a threat. Think of a boar, a bull or a tiger. In the [picture](http://world-bird-sanctuary.blogspot.com/2012/04/really-weird-birds-part-2.html) you see the claw of a cassowary: it screams danger.
[](https://i.stack.imgur.com/r4CUW.jpg)
* Lastly, by their apparent size you can estimate their level threat: we usually think "bigger is more dangerous", until we stumble on a fire ant or the like. But normally a rabbit is less dangerous than an elephant, unless you are on the search for the Holy Grail.
The type of diet, even if ascertainable, is not so relevant for the danger level: elks, elephants, cows, hippos are examples of herbivores for which one should better take a safe distance.
[Answer]
**You recognize the creature is not natural because its parts are from unrelated animal groups.**
These minotaurs have recognizable bovid (or cervid) characteristics. The head, and the hooves. They have recognizable primate characteristics - the hands, muscle structure and bipedal stance. These are from different orders of mammals. Finding them together in a single creature means it is an artificial creature.
A natural creature should occur in nature with other similar
related creatures. The general appearance of an elk is not radically different from a white tailed deer or a moose. The general appearance of a human is similar to that of an orangutan or monkey.
In real life, animals occur in the context of their evolutionary cousins, and share features within their groups. In a single creature, features from two or more unrelated groups chimerically grafted into a single beast means the beast was not a product of nature, but a product of the imagination, or magic, or supernatural forces.
Or technology.
[](https://i.stack.imgur.com/nrary.jpg)
<https://www.cbsnews.com/news/living-breathing-glowing-rabbits-successfully-born/>
[Answer]
## Features
I think in general, certain features and attributes are used to signal things. If you depict an animal with a weapon, you suggest your animal is dangerous *and* intelligent, because it uses a tool (the weapon)
The larger the teeth are, the more dangerous.. *and* primitive.
**Ugly is evil**
A princess should be beautiful *unless* she is evil. Stepmother same thing. That's *why* they put stepmothers in evil roles, their uglyness is obvious and already present.
**Neotenous features**
The opposite. Have it look like a child. Let it wear pink, or light blue. This will effectively disarm your character. It is appropriate when the character has to be a victim, like ET, stranded on Earth. It has neotenous features: ET is small, with large eyes and it has a high pitch voice. It is an alien, but there would be few humans that would be scared of ET. Because it looks like a lost, innocent child.
**Opposite features may work**
Small creatures are not dangerous, large creatures are. But when your large creature looks like a fragile old man, it would become "the friendly giant". Similarly, you can make a small creature look dangerous. Gremlins are a nuisance and their heads look fierce, but Gremlins are not *really* dangerous.. The Gremlin is too small, it will only scratch you, it can't kill humans. Just scare them. Of course, the viewer/reader will be *amused.*
**.. or opposite features can weaken a character**
At this point, a critical remark about your [Minotaur](https://worldbuilding.stackexchange.com/questions/35499/what-does-the-minotaur-eat/35510). Opposite features will not always work.
King Minos of Knossos sacrificed people in his labyrinth, to be eaten by the Minotaur. This creature is based on mythology, to be *authentic* it should actually kill humans.
But your version of the Minotaur looks quite innocent. A mix of Santa Claus and one of his reindeer. I think it is because of the *antlers* you put, which are misplaced anyway, because the Minotaur was a bull (Taurus) and when you put a feature on its head, it should get *deadly* horns, not antlers. The antlers feature indicates deer, which is *not* a dangerous species for humans.
This one maintains most of your features and proportions, but it has horns and claws, no antlers,
[](https://i.stack.imgur.com/ckHdq.png)
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[Question]
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There is no world or setting attached to this question but it does have me curious and might be useful for those who do actually want to build a world with this as a feature. Imagine a luna-like moon that orbits an earth-like planet but the moon does not orbit around the center of the planet, instead it orbits around the planet like how a marble might roll around a tennis ball on a flat floor. Its orbital ring is offset to be flatter and nearer to the 'floor' of the solar system but still orbits the planet that has it as a satellite.
**What would cause a moon to orbit a planet like this?**
[Answer]
I found a few possible causes for decentered, and even non-elliptic paths for moons,
* the moon is very far away from the planet, in this case the orbit will not become elliptical, it could follow a horse-shoe shaped path,
<https://theconversation.com/earths-other-moon-and-its-crazy-orbit-could-reveal-mysteries-of-the-solar-system-38010>
* the moon was not formed from planet matter, like Earth's moon, rather it was kept in orbit after a collision event, to get a new orbit around the planet/moon system. At first, it could have a very decentric orbit.
<https://www.theguardian.com/science/2021/nov/11/near-earth-asteroid-is-a-fragment-from-the-moon-say-scientists>
Eventually, depending on the mass (see L. Dutch answer), the object will impact, or its orbit will stabilize as a centered ellipse, or a wobbling centered ellipse, when other moons are near,
<https://www.firstpost.com/tech/science/nasas-hubble-catches-a-pair-of-neptunes-moons-in-a-truly-bizarre-dance-of-avoidance-7669001.html>
* there is a regular disturbance of the moon's orbit, due to a nearby planet or another, heavier moon in the same system. The decentricity of the orbit would become periodic, when the disturbance of the orbit will also be periodic.
<https://solarsystem.nasa.gov/moons/saturn-moons/aegaeon/in-depth/>
In any case, a decentered orbit is temporary. All orbits around a single center of gravity become elliptical *and* centered in due time.
[Answer]
A planet is defined as a body under hydrostatic equilibrium. In that condition, its center of mass will overlap with its geometrical center.
The only way for what you are asking to happen is to have a body not massive enough to be a planet but rather a potatoid like [Ultima Thule](https://it.wikipedia.org/wiki/486958_Arrokoth)
[](https://i.stack.imgur.com/CRjET.jpg)
orbited by a body with an even lower mass.
In the configuration shown in the picture, if the biggest clump of the potatoid is also more massive, the center of mass will be located somewhere there, and the orbits would revolve around it, away from the geometrical center.
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[Question]
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I am busy working on a race of humanoids, to defend themselves against their planets large predators I gave them a pair of retractable keratin blades which are housed just below the Ulna in the forearm, they extend some 10cm beyond the elbow when extended. My problem is this:
How could the blade be extended and retracted but whilst still being rigid enough to stab an attacker without the blade simply retracting?
[Answer]
I'm a talker not an artist, so I'm not going to match the beauty of ProjectApex's very good answer. Words will have to suffice I'm afraid.
What you're looking for is a locking mechanism that engages the rear of the blade, holding it relatively motionless and padding any impact or shear forces. While this might be a little tough to justify through evolution alone, weirder things [do exist in nature](https://www.nature.com/articles/s41598-017-14312-0).
Stashing a blade between the radius and ulna sounds interesting, but you'll need to make some fairly radical changes to the structure of the elbow to allow the blade to pass. Rather than the human elbow structure with the ulna basically cupped around the elbow joint, rotate the radius and ulna such that they both cup the 'side' of the join while rotating. This gives us a clear channel along the back of the joint for the blade to pass through. Unfortunately this will restrict the rotation of the forearm a little, but we're getting a built-in weapon here.
Now on to the locking mechanism. If the faces of the elbow joint on the humerus are angled a little, the radius and ulna can be set to rotate around their long axis slightly when the elbow is fully bent. Each of the forearm bones can then have half of a locking mechnism that closes on the shaft of the blade, locking it in place. The interior end of the blade would have a shaped end that engages with the locking mechanism, with [fibrocartilaginous](https://en.wikipedia.org/wiki/Fibrocartilage) padding and [bursae](https://en.wikipedia.org/wiki/Synovial_bursa) to provide a little shock absorption. For bonus points a similar clamp structure at the wrist end of the arm could hold the blade in place when not deployed.
The blade itself needs to be housed in a [synovial sheathe](https://en.wikipedia.org/wiki/Synovial_membrane) to provide protection to the surrounding tissue and lubrication of the blade while moving. This might lead to a little leakage of synovial fluid - the stuff that lubricates your joints - around the blade's exit sphincter in the elbow. It might be a good idea to have a slow, steady flow of synovial fluid along the blade to help reduce the chance of infection, so maybe your humanoids have a constant slow emission from their elbows. Sounds a little gross, but I imagine bactieral infection of the blade sheathe is an unpleasant experience.
Putting it all together now... the blade is locked in place inside the arm by static arrangement of the bones of the forearm, backed up by dedicated musculature to prevent the blade from deploying accidentally. Bending the elbow past a certain point rotates the forearm bones apart enough to release the blade, allowing blade entender tendons to push the blade across the elbow joint. At full extension the elbow is rotated a little more, further rotating the forearm bones and clamping the locking flanges onto the end of the blade, locking it into place.
As awesome as a bone blade might seem though, these creatures will really come into their power once they hit the a technological level high enough to augment these blades. Ceramic blades with implanted enhancements. Powered blades able to slice through body armor like a craft knife through tissue paper.
(OK, now I'm just having fun. You can ignore that last bit.)
[Answer]
# If they have something like an exoskeleton? Literal Gear-like protrusions and locking mechanisms.
I'm not kidding. An exoskeleton opens the door to more mechanical-esque approaches. [Leafhoppers](https://www.smithsonianmag.com/science-nature/this-insect-has-the-only-mechanical-gears-ever-found-in-nature-6480908/) have a unique gear system in their hind legs. This is because their jumps are so powerful that if they don't make sure their legs are synchronized they could miss the desired spot they wanted to reach by a lot (these little things can jump faster than your eyes can process they're gone).
[](https://i.stack.imgur.com/8QC0f.jpg)
As for a locking mechanism, look no further than the mantis shrimp, whose powerful strikes are due to a spring mechanism. Their claws stay locked in place while their muscles contract, building up elastic energy that's released in one blow once the lock is released (kinda like a more extreme version of a flick)
With that in mind, it's not impossible that, having something like an exoskeleton in their forearms, your humanoids could rely on gear-like protrusions and locking mechanisms for their blades. Additionally, you could take a page from the [spearing mantis shrimp](https://www.iflscience.com/plants-and-animals/amazing-video-mantis-shrimp-spearing-fish-slow-motion-0/) and add in 2 locking mechanisms, one to keep the blade extended and one to allow you to build elastic energy.
With that done, add in some extra bits to make the thing able to extend longer and you could feasibly end up with something not too unlike an organic version of Cyberpunk's mantis blades. Here's a sketch for reference.
[](https://i.stack.imgur.com/BFyhL.jpg)
# without something like an exoskeleton? Probably a stay apparatus.
Now, if the thing doesn't have an exoskeleton or something similar, you could likely still pull it off, although you'd instead rely on special joint locking mechanisms (you know how your legs can "lock" in a straightened standing position? Something like that). It would most likely require something like the [stay apparatus](https://pubmed.ncbi.nlm.nih.gov/12739613/) found in horses so they can nap while standing, but I'm pretty sure you'd still require a joint system for this retraction.
[](https://i.stack.imgur.com/ZFKQp.jpg)
As for a wolverine style retraction and extension? I'm not sure if it's possible or reliable in the scale you want it to happen, as in organic life things like loose parts sliding around aren't common, if they are present at all. The easiest way to ensure that the muscles will be enough is to have the blade mounted on a joint system, as you'll have actual rigid components backing up the bladed portion rather than relying purely on muscle contractions/extensions, with the potential added benefit or granting some extra reach.
[Answer]
You are basically looking at an upscaled version of an insect stinger, stripped of any possible venom gland
>
> A stinger (or sting) is a sharp organ found in various animals (typically insects and other arthropods) capable of injecting venom, usually by piercing the epidermis of another animal.
>
>
> [](https://i.stack.imgur.com/WuCU2.jpg)
>
>
> An insect sting is complicated by its introduction of venom, although not all stings are venomous.
>
>
>
It's normally hidden, it is extracted on demand and it is rigid enough to allow piercing through the target skin.
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[Question]
[
A derelict space craft, 1MKg in mass is in a 100km (more or less) orbit above the surface of an asteroid out in the asteroid belt.
How big should the asteroid be to have the ship maintain this orbit for a long period of time (decades).
By stable I mean that the asteroid is large enough to thwart the efforts of the the Sun and Jupiter in the system (the two gorillas in the room) to disrupt the orbit, plus most any small object that happens to be flying by.
Wikipedia suggests "average" asteroid density is $2g/cm^3$, so that's good enough for this exercise. Asteroid is "more sphereish" than not. The barycenter should be deeper within the asteroid.
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The radius of the [Hill sphere](https://en.wikipedia.org/wiki/Hill_sphere) (the zone in which one body's gravity dominates over another) of a large body on a much smaller satellite (as will be the case for an asteroid and a mere 1 kiloton spacecraft) in a circular orbit is given by
$r\_H = a(\frac{m}{3M})^\frac{1}{3}$
where $a$ is the semi-major axis between the asteroid and the body *it* orbits (in this case, the Sun), $m$ is the asteroid's mass, and $M$ is the mass of its parent (the Sun). The main belt starts a little over 2AU away, so as the worst-case scenario, let's set $a = 2 \text{ AU}$, $M = 1M\_{sun}$, and then plug in $r\_{H} = 100 \text{ km}$, assuming the spacecraft is at the very edge of this stable sphere, and solve for $m$.
We get $m \approx 2.3\times10^{11} \text{ kg}$, which, using your density, requires a spherical asteroid of radius ~**300 m**.
Wikipedia helpfully lets us know that the actual orbital distance to ensure stability is usually closer to half or one-third the Hill radius. In the worst-case one-third threshold, we need to multiply $m$ by 27 to triple the Hill sphere's radius to 300 km, and thus triple the asteroid's radius to **900 m.**
As a quick double-check, the binary asteroid [2006 VW139](https://en.wikipedia.org/wiki/(300163)_2006_VW139) has a semi-major axis between the pair of ~100 km and is made of two asteroids on the order of 1-3 km in diameter, depending on the source (though it is a little further from the Sun). So our estimate seems very roughly right — objects of this size can indeed have satellites in (at least observationally) stable orbits.
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I plugged numbers in here.
<https://www.omnicalculator.com/physics/orbital-velocity>
I assumed the orbit was a circle 100 km in diameter and so the semimajor and semiminor axes were each 50 km.
[](https://i.stack.imgur.com/bZzVA.jpg)
1 billion or 1 x 10^9 if I counted the 0s right. That is pretty light as celestial bodies go; I checked Phobos and Ceres and they are much heavier.
The heavier the asteroid is the faster your ship will go around and around.
The cool thing about the calculator - as you add zeros to the weight of the "star" the orbital period is instantly calculated. At the weight of Phobos (1 x 10^15) the orbital period is 3.15 days.
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In my fantasy world based on late antiquity/the early medieval era orcs have a large, powerful empire and seek to expand its borders to invade more land. Since most of the world's population is human most of their conflicts are with humans.
What methods could orcs use to succesfully maintain an empire where the majority of the subject population is human? The goal is to prevent large-scale of just too many rebellions and make it so most humans would accept orcish rule. Real historical empires like the roman empire succeeded by assimilating people they've conquered into roman culture, and I'm not sure if it would be possible for orcs who look physically quite different from humans. Due to being a different species humans might have a harder time accepting orcs as legitimate rulers and be more likely to rebel. What could the orcs do to gain support from their human subjects?
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# Empire building will be much slower in the traditional way.
The normal way that an empire is conquered is you militarily defeat the main force of a region, and then your nobles intermarry with their nobles so you can be a legitimate leader.
This lets you call upon the resources of those you conquer, in taxes and levies of soldiers.
If you can't intermarry with conquered people because you can't breed with them, it's gonna be much harder forming bonds.
# They can form an empire like the Mongols did.
They had people of their own race form the core of governments, but a lot of their advances were based off making people pay protection money. They would go to cities, demand payment, and refused use horse archers, chinese siege weapon builders, and lanced charges to slay their foes.
They also built a sophisticated messaging system and trade system to communicate across their empire.
This lets you leave the governments of those under you mostly intact, while getting tribute and mercenaries from them as needed.
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**Mamluks?**
[](https://i.stack.imgur.com/7cJ4q.jpg)
Depicted: the Cairo citadel and mamluk stronghold. The mamluks were non-Arab warrior slaves in the medieval Islamic world. Despite technically being slaves, they were politically powerful in many Islamic countries. Mamluks took control and ruled Egypt for centuries.
<https://en.wikipedia.org/wiki/Mamluk#Organization>
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> Under the Mamluk Sultanate of Cairo, Mamluks were purchased while
> still young males. They were raised in the barracks of the Citadel of
> Cairo. Because of their isolated social status (no social ties or
> political affiliations) and their austere military training, they were
> trusted to be loyal to their rulers.[21] When their training was
> completed, they were discharged, but remained attached to the patron
> who had purchased them...
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> Mamluks lived within their garrisons and mainly spent their time with
> each other...
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> Sultans owned the largest number of mamluks, but lesser amirs also
> owned their own troops. Many Mamluks were appointed or promoted to
> high positions throughout the empire, including army command.[18] At
> first their status was non-hereditary. Sons of Mamluks were prevented
> from following their father's role in life. However, over time, in
> places such as Egypt, the Mamluk forces became linked to existing
> power structures and gained significant amounts of influence on those
> powers.[18]
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> In Egypt, studies have shown that mamluks from Georgia retained their
> native language, were aware of the politics of the Caucasus region,
> and received frequent visits from their parents or other relatives.
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So: ethnically distinct from the majority population, living with each other and not with the locals, children produced with the locals are not themselves mamluks. No inherited power. Only fresh-caught and trained persons can be mamluks. You could have your orcs be like the mamluks - ruling the humans but sticking to their citadel and consorting with their own kind.
I am hoping AlexP wades in on this one because the mamluks are super interesting.
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How many species of intelligent beings are there on Earth at the present time?
The usual answer is that there is one one species on Earth the present time, *Homo sapiens*, which is recognized as being an intelligent species. Since that recognizing is done by members of the species *Homo sapiens*, one might suspect that they might be biased in their favor.
I note that there are about 6,000 species of mammals on the planet Earth, and that hundreds of them have large enough bodies that they could support large and complex brains. And some of the species large enough to have large brains actually do have large brains.
Are humans the most intelligent beings out of all the beings intelligent enough to be considered people in all the universe? Ae humasn the least intelligent beings out of all the intelligent beings in the universe? Are humans sort of average among intelligent being in the universe?
So if some of the other large brained mammal species on Earth seem to have intelligence ranges which overlap with those of humans, does that mean that they count as intelligent beings and as people?
Or are humans at the absolute lowest possible intelligence range for a species to be just barely people, and would any beings with lower average intelligence, no matter how much their intelligence range may overlap with that *Homo sapiens*, be considered to be under the minimum intelligence level and thus not people.
So it is possible that members of at least four species of great apes, three species of elephants, and up to 80 or 90 species of cetaceans might be intelligent beings and people.
Thus it is possible that while humans formed thousands and thousnds of different states, some of which can be considered to be empires by various definitions of empire, other intelligent beings also lived on the Earth, and had greater or less degrees of interaction with human empires, and greater or lesser effects on the ability of humans to form and maintain empires.
And from those examples it looks like there might be only one species at a time with the ability to form empires. But what if two intelligent species on a planet are equal in the attributes which enable empire forming?
If there is a species on a fictional planet with similar intelligence and manual desterity to humans, they should be able to found states, including empires, about as well as humans can. In a world where humans are also found, sometimes those beings might rule empires which include humans as subjects, sometimes humans might rule empires that include those nonhumans as subjects, and sometimes there might be empire where the ruling class includes humans and nonhumans, and the commoners include humans and non humans.
Adn if the nonhuman species is superior in any important ways to humans they would have an advantage over humans in state building and should be able to form empires that include humans easier than humans can form empires that include the nonhumans.
The works of Tolkien contain several examples of superior species having rule over inferior species.
In Aman the Blessed the Ainur rule and the Elves rule themelves subordinate to the over all authority of the the leaders of the Ainur.
In Morgoth's realms of Utumno and Angband Morgoth's main servants, fellow ainur, were the uppermost class and members of biological species were lower cloasses, down to enslaved enemies who were the lowest classes.
And in the Years of the Sun in the later part of the First Age, Eleves ruled in Beleriand. There was a certain rivalry bebtween Thingal and Fingolfin as to who was the righful overlord of all Beleriand.
And after several hundred years of the Sun Men appeared in Beleriand. The Men settled in various lands and their lords became allies, clients, or vassals of the Elven kings.
So the Elves in Beleriand came to include lowly humans in their realm.
I am not certain how "superior" to humans any type of orcs might be. But I guess that your orcs could be equal to humans in ability to organize their societies and their armies, so they should have a fair degree of success in their wars and other relations with humans.
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Physical differences is not a barrier to rulership. There are countless examples in our own world of history of empires where the ruling classes of a different race or ethnicity then thier subjects.
Romans had Germans ( considered by them to be a different race) Asians and Africans in their Empire. The Spanish Empire Is had a ruling class of European or partly European ancestry, which ruled over a population of mainly natives and and African slaves.
If fact there difference might strength there rule. If there could prove that they were physically stronger than humans they might be able to present themselves as demigods with a divine right to rule.
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For contextualization, in my world a phenomenon caused anomalous "creatures" (for a lack of a better term) to appear. Among these, I planned to have "creatures" capable of running at ludicrous speeds when compared to anything based on earth biology. However when researching about how animal movement and speed works, including on this SE, the main conclusion I got to is that any machine or organism that relies on limbs to move around and accelerate will always be necessarily less efficient than something that makes use of wheels or treads due to how friction works as well as other details (as a wheel will normally always stay in contact with the ground, being able to apply a constant force, differently from the paw system that naturally requires the limbs to leave the ground and has a smaller overall surface area at any given moment during the run). To attempt to mitigate that problem, I planned to make my creatures similar in overall anatomy to a house centipede, aka it would have multiple legs, each leg longer than the last one to avoid collision, so that it would always have at least one limb (or pair of limbs) on the ground at all times, essentially trying to get closer to a wheel's nearly constant contact with the ground (originally I planned for a total of 10 legs).
However, what I found on the movement and bodyplan of house centipedes stopped being useful to me, since I wanted my creatures to be much larger (around 2.5 meters long and ~1.5 meters tall, with a max weight no higher than 200 kg), and I couldn't really find anything to help me at such sizes. The fact that [tiger beetles](http://corbettfoundation.org/articles/2015/11/09/the-splendid-tiger-beetles/) are proportionally much faster despite having only 6 limbs also made me doubt whether this approach would actually result in greater maximum speeds.
The ideal goal would be for the creatures to be able to maintain speeds of 150km/h for long periods, with max sprinting speeds closer to 500km/h (both assuming the creature is running on a straight line, unimpeded by obstacles). The creature's limbs end in 2 toes with claws and special rough skin used mostly to maximize traction. They predominantly live and run in terrain much like that of a flat Savanah.
Leaving worries such as the overheating problem and the resistance of the materials the creature is made of (these aren't my main concern, so as of now simply assume the creature is indestructible and fully capable of performing the necessary work without needing to worry about problems like overheating), **is such an approach of having more limbs an effective choice to make my creature a faster runner overall?** I couldn't really find whether the addition of limbs could provide any meaningful advantage or if a body plan of a centipede, with its hind(er?) limbs being longer than the previous pair, wouldn't cause drag-related problems given the creature's size and the speed it'd be running at, or at least not in the scale of approximately horse-sized (approximately 2 meters tall) animals.
If I've forgotten to add any important details, please let me know so I can add them.
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The speed of an animal is a function of stride length and frequency, the greater both are, the greater the speed of the animal.
The stride frequency is a function of strength vs weight, with the limb acting a bit like a pendulum, so animals with a higher stride frequency tend to have limbs that concentrate their muscle mass high in the limb... think ostrich-like legs rather than human-like legs.
To use a mechanical example, consider a mechanical metronome. The closer the weight is to the pivot point,the faster the metronome will tick.
However, being strong enough to run means that the limbs *must* have a certain weight so that they won't break under the load put on them. To make the limbs lighter, the entire creature must be lighter.
Next is the matter of gait. When walking, an animal always has at least one foot on the ground. However, when running, there are periods in which all feet are off the ground. However, aerodynamic drag tends to slow the creature during these unsupported portions of their gait cycle, so an aerodynamic shape is of some importance.
The specifics of the gait cycle for creatures with more than 2 limbs affects the creature's speed and maneuverability. The fastest gait cycle is one in which the feet touch the ground sequentially with a minimum of overlap.
When considering animals with more than 4 limbs, the advantage that they give to the animal's speed depends upon how many limbs are necessary to support the animal's weight while running. The higher the ratio between number of legs and the number of feet required to touch the ground, the more distance each gait cycle will cover. Most insects with 6 legs have a ratio of 6:3, which is actually no better than 2:1, with the added disadvantage that insects tend not to have unsupported periods in their gait cycle. Arachnids also tend to have a ratio no better than 8:3 with no unsupported periods.
So, if we could have a six-footed creature with a 6:1 ground contact ratio, with long, light limbs, and a long unsupported period, you'd likely have a particularly fast creature. Eight legs with 8:1 ground contact would be even faster, but given the weight of all the limbs, this ground contact ratio may be unachievable without making the limbs overly bulky and slow.
There are yet more factors at play. Take, for example, a cheetah, Earth's fastest living land animal. Even its spine plays a role in its great speed. By flexing and extending its spine while galloping, it gains about 5kph to its running speed due to the effect that has on the angles of its pelvis and shoulders relative to its spine. However, that is specific to a mammalian body plan. Other creatures may have other features that may allow greater speed.
So, just adding more limbs isn't necessarily going to make a creature faster. Centipedes are quite fast, but millipedes, with more legs, are actually slower. It all depends on the factors I have mentioned above.
There is just one circumstance which would allow a greater speed than any creature with limbs: rolling motion.
A creature capable of rolling - perhaps a serpentine creature which can roll itself into a hoop, or perhaps a roundish creature - could propel itself by distorting its shape so that gravity was pulling it down and leading it to roll forwards. The speed at which it could move would depend on its size and the speed at which it could change the shape of its body, as well as the local gravity and the local slope. The impact of centripetal forces on its body would also be important.
However, this would be a relatively niche means of locomotion, dependent upon having quite smooth, flat ground over which to roll. Obstacles could easily prove injurious or fatal at the speeds achievable.
The advantage of rolling locomotion is that there is (probably) no reciprocating limb motion consuming lots of energy, and the range of motion required is relatively small. The creature should be able to coast for considerable distances and achieve higher maximum speeds than creatures using multiple limbs.
This is probably the only reasonable way to achieve the speeds mentioned in the OP's question without requiring a ridiculously high energy input and having an unreasonably low endurance level.
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Centipedes are fast because they 's' their bodies like snakes not because they have so many legs.
More legs isn't any bonus to speed. It's not the amount of legs that matters as much as the length of the legs and other factors.
What you need is just a faster more durable horse or gazelle. Or a kangaroo built for speed with longer more powerful hind legs. Once a kangaroo gets going it can go pretty fast for a long time because most of the time it's in the air.
The [Red Kangaroo](https://www.nationalgeographic.com/animals/mammals/facts/red-kangaroo) can run at 70km/h and is the most efficient land animal we know of for covering distance quickly.
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More legs can work as a means of going faster, but only to a certain extent. The most efficient model would launch the animal forward with one pair of legs, then launch again when deceleration begins to take effect. Whether this is by another pair or the same, as long as it has the speed to achieve this the animal will get the most speed out of it's legs. Other factors with speed are dependent on shape or strength of the legs.
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There are two ways this could go -
The first is that these limbs contribute to speed, like extra legs or longer limbs so it could move faster. Many four legged animals move faster than two legged animals, because they can have longer stride distances. Humans top out in speed alot shorter than most quadrupedal animals, for example.
The second way this could go is bay making them slower. These extra limbs are extra weight, which could considerably slow them down. For example, even though an elephant is stronger than an antelope, the antelope will move faster because it has a lot less weight.
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Daemons are malevolent spirits that inhabit the astral plane. This religion views these spirits as divine beings and worship them as gods. They are heavily revered in the faith, and are considered higher life-forms that are superior to humanity. Daemonology is the study of these creatures in order to use them for their power. This craft exists in two forms of study: The path of the summoner, and the path of the host. Both of these disciplines have their strengths and weaknesses, and are a reflection of daemonic society: that of constant improvement over one's self through ruthless individualism and subjugation of the weak. The only law is power, which must be used to acquire resources at the expense of the innocent. This is the only way to run a proper society.
The path of the summoner involves the torture and enslavement of daemons in order to bind them to the will of the practitioner, the practitioner can wear the daemon like a glove or a second skin. At this point, the daemons powers and abilities can be exploited, with the user calling upon them as needed. The daemon can even be summoned entirely, separating itself from the host to use its true power at the behest of its master. This path is multi-faceted, with users gaining access to the abilities of numerous daemons. Several creatures can be bound at once, with the most powerful users able to enslave dozens of daemons in this fashion.
The path of the host involves the same process of subjugating a daemon, but involves binding it to a user's soul, turning the practitioner into a daemonhost. This daemon-human hybrid is a demigod representing the best parts of mortal and divine. This path focuses on specialization, with the individual gaining access to one set of powers. However, those abilities grow with time, making the user more powerful.
Obviously the best goal that can be realized would be the combination of both paths. This would lead to a daemonhost that can control other daemons. This would be the ultimate dream for any practitioner, as it would lead to UNLIMITED POWAH. Sadly, this would be too OP, as the resulting being would kill everything on the map. However, no respectable student of the paths would shy away from achieving more powah for themselves, as not doing so would betray everything they stand for. The only way to prevent this is to design some way to prevent this from happening. How can this be made possible?
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Freidrich Nietzsce's notoriously said
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> "And if you gaze long enough into an abyss, the abyss will gaze back into you."
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That's precisely the reason: when a demonologist trespass a certain threshold they become the very subjects they want to subjugate.
Turning from being a master to another master's tool is nowhere appealing.
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Daemon husbandry is a constant struggle.
The daemons aren't very fond of mere humans taming them. They try to resist domination. Daemonologists must keep deep concentration in order to subjugate the daemons and use their power.
Should a daemonologist get distracted, or lose focus for some reason, the daemon(s) would take over and do nasty things to them.
Having said that, it would be extremely dangerous for someone to try to follow both paths at once. But some overly greedy daemonologist might try... An interesting plot could rise from that.
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/This would be the ultimate dream for any practitioner, as it would lead to unlimited powah. Sadly, this would be too OP, as the resulting being would kill everything on the map./
**They leave the map.**
Daemonhosts that can control other daemons lose their foothold on this plane and wind up in the astral plane with all the other daemons. Some are powerful enough that they can just barely maintain a presence in the material plane, but at the expense of being unable to do much more than be present.
In the astral plane these things are powerful indeed. There are also other powerful things in the astral plane. Some resent these outsiders showing up.
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# They're not incompatible, daemons can use daemon summoning.
Unfortunately, this means that demons can also use daemon summoning. If you bond with a daemon and become a daemon, then other daemons can summon you and will summon you for use in disputes, wars, pleasure and whatever they will.
Daemons you summon can also summon you and bind you, which makes bonding daemons notably harder.
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# Daemons are [Sadomasochistic](https://cenobite.fandom.com/wiki/Cenobite):
No one LIKES being enslaved, but let's face it - the astral plane is a brutal, torturous place where daemons constantly vie to dominate and control each other. No daemon lasts long as an independent entity unless they are really good at fighting off domination by other daemons and having the ego to resist them.
Humans, on the other hand, are timid, innocuous creatures and our world is like a quiet day in the park. The very reason humans are successful is they AREN'T daemons. There is a lure to domination in our world which is shameful but pleasurable.
While daemons don't WANT to be merged with a human host, they know that after a relatively cushy time on this world, the daemon returns to it's native realm as a hybrid being with a new human soul fused to it. The battle in the daemon is both with the suffering of torture, but also the gain in power the daemon gets in the long-term. Pleasure and pain merge and the daemon is swept up in the metaphorical moment.
Conversely, daemons summoned and dominated by wizards aren't REALLY under control. They have the spiritual equivalent of a safe word. The daemon can ALWAYS resist, but the release from the constant struggle with other daemons is so great that the daemons gain strength over time resting in our world. The humiliation of being controlled is outweighed by the pleasure of release from constant struggle. Rather than continue resisting, the daemons take the chance to be bound in our world, knowing they always can resist if things are really bad.
But a daemon will ALWAYS resist binding to another daemon. It's the central fact of their existence. So a daemonhost IS a daemon to all other daemons. There's no upside to domination by another daemon - no gain, no release. Nothing humans can do to a daemon measures up to being controlled by another daemon. So a human who becomes a daemonhost will immediately lose control of all their daemons, as being controlled by other daemons is worse than any mortal suffering, and daemonhosts can't summon more because the daemons will never surrender to another daemon.
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We humans have the triad of Mind, Body, and Soul. It is the combination of all three of these things that make us the specific humans that we are.
It is well-known that daemons are stronger than us average humans, that is why we have to forcibly subjugate it to our will -- we have to prove our strength to them in ways that they will comprehend and grudgingly accept. Or not and we take their power -- either seems to work.
Binding a daemon to the body or the soul leaves the other two pieces untouched by the daemonic force. As such we retain a majority of what makes us human. Even the daemonhost, which becomes a demigod in power by taking a daemon into their soul directly, still has a mind and body that are human, that recall being human. In essence, those that bind daemons are human enough in the spiritual sense to continue down their chosen path.
Doing both leaves only the mind untouched by daemonic influence. That is two parts touched by and warped by the daemons and one that isn't. The instant one tries to follow the second path, the human has ceased being human enough to count for the first path. The three entities (two daemons and a human) cease being their individual selves and a new daemon is born from the fusion of all three beings. If the daemon bound to the body is lucky, they might get away severely injured and/or depleted when the reaction starts
Since it does not look like a daemon can be in the material world (easily?) without a host to hold it there, the new daemon is instantly yeeted from the mortal world and left to find its place in the daemonic hierarchy, to use or be used. If they recall their former life, they may actively look for a host to subvert, or viciously avoid becoming a pawn to the humans they once were.
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**They use the same resource.**
The Demonhost binds their soul to a single demon. Conversely the Summoner binds the demons to (part of) their soul. Since you only have one soul of course you cannot do both at once.
Specifically the Summoner chops off pieces of their own soul and grafts them onto demons to give them control. While the Host chops off the entire soul of the demon and grafts it onto their own soul.
So why not do both? Graft half of your soul onto some Summons and then use the other half to Host a demon? Unfortunately this will result in the demon's full soul taking over you instead of the other way around. . . .
. . . at least using any of the demons anyone is interested in hosting. It is possible to Host a Quasit or Millipede type demon using only half of a soul. But those guys are so small and puny, this makes you weaker than a baseline human. Anything worth Hosting required your entire soul.
The finite resource means you cannot be both a powerful Summoner and Host at the same time. You can only be a half-decent Summoner and half-decent Host.
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**The method of control allows them to disrupt each other**
Path of the Summoner relies on subjugation and is a method in which you hold absolute power over the subjugated. The daemons can scheme all they like to try and get a summoner to relinquish their power but, it is a one way transaction of power. That is why summoners can control many daemons.
Path of the Host relies on subjugation of a single demon and binding it to you so completely that it merges with your very soul providing proof of your dominance for the entirety of your existence.
However, the daemon of a host can still fight back. It is inevitable to lose to its host as it is weaker than the host. After all, it was subjugated and so most daemons don't fight back. The host cannot put other daemons on the leash of a Path of the Summoner because the disruption of a hosted daemon fighting back gives all the subjugated daemons time to act without fear of retribution as the host wages battle. This often ends in the summoned daemons killing the host to be set free.
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Assume we have a Dyson Sphere, ready to rumble.
Also Assume that knowledge bearing robots are plentiful as well (apart from energy) who can do any task (from 3d printing a laptop to creating a house to creating a car etc)
Now, can a person live off solely energy? (since elements can be converted to a metal of choice via energy).
You need iron, convert sand to iron. You need food, grow it via organic farming or create it in a lab. You need fuel, use solar powered car (also made via energy). You need fans/air conditioning/books you use energy to create them (along with the rudimentary materials).
For mental satisfaction, create virtual reality systems (as one of Molborg pointed out) or create androids (as romantic companions).
So, can excess energy essentially create a potential utopia? (assuming the individual greed/racism/communalism etc don't isolate a section of humanity from the benefits of the tech/energy)?
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Dyson Sphere, hm, no if your prerequisite is energy to matter conversion.
It may depend on how much matter they need to satisfy their needs, how many of them there are, and all that.
But using 100% of sun energy, in a 100% efficient way - they can make 4 million tons of matter per second. Or about 1.2e14 tons per year.
This is a significant number, as mass goes, and the important question is how much do they need for their happiness. If it is enough for them, like there is a trillion of them - maybe it is enough for them if they live a modest life, about 100t per year per person.
But using the same energy to redistribute the already existing mass of rocky planets and gas giants - seems like a more efficient way to use that energy.
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>
> Now, can a person live off solely energy? (since elements can be converted to a metal of choice via energy).
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Trivially, yes. You can synthesise all the materials you need, so ultimately you can support life as you see fit.
As MolbOrg pointed out though, the total amount of matter available from a sunlike star if you're merely converting its electromagnetic radiation to matter is actually kinda small, when you're talking about a civilization capable of constructing a dyson sphere.
(FWIW, their estimate of ~4MT/s doesn't account for the pesky conservation of baryon number, so it'll be more like 2MT/s, but the shortfall can be made up by the solar wind which would contribute another 1-2MT/s that you could catch in your dyson sphere)
A better approach might be [Star Lifting](https://en.wikipedia.org/wiki/Star_lifting), where you use various tricks to harness the energy produced by a star to pull matter up out of its gravity well to use as you see fit. The linked article suggests that using 10% of the sun's energy could let you lift up ~6 x 1018 tonnes of matter in a year... that's 10000 times more than you get from your mass conversion alone, and you still have that 90% of the solar output to play with as you see fit.
That huge amount of matter still only accounts for a miniscule portion of the sun's mass, so you could carry on doing it for millions of years before having lifted up a single percentage of the original mass.
>
> So, can excess energy essentially create a utopia?
>
>
>
Sure. But it'd make more sense to use all that excess mass, too. There's a lot of it in the universe, just lying around for the taking.
[Answer]
## Unlimited Energy Doesn't Necessarily Mean Utopia
From a theoretical standpoint, yes, you can take in sunlight and Hydrogen from the solar wind and combine the two into everything society needs.
From a practical standpoint...
Turning Hydrogen into Iron is going to require repeatedly fusing elements, then running the results through a separation process, since you will get some other, non-target elements out of each step.
The largest, most advanced fusion project humanity has ever attempted has cost tens of billions, takes up significant physical space, and resulted in approximately [zero fusion to date](https://en.wikipedia.org/wiki/ITER). So I think it's unlikely that we will ever build a society where everyone has their own personal fusion setup.
## Control Enables Corruption
If everyone needs to go to a "fusion provider" to transform their Hydrogen into whatever else they need, then the fusion provider is in a position of power. They can deny or delay access, which is a potential source of conflict. There are lots of potential solutions to this access process, ranging from near-utopia to tyrannical dictatorship.
Generally, having many different, independent, fusion providers is likely to produce a better society - each provider has less power, and therefore less ability to control others. If you want something more dystopic, consolidate the fusion providers.
## Secondary Avenues of Power
If people in the Dyson Cloud need to collect masses of Hydrogen, and physically move them to the fusion provider, then the people who do those activities also potentially have power over other people in society. There are bound to be choke points on the approach to the fusion providers, and to the best places to collect mass. The people who "own" (or can threaten) those approaches can charge tolls.
Likewise, people will need designs and recipes to build what they need. This will require knowledge, which could be shared freely or could be controlled with Intellectual Property restrictions.
**Human nature being what it is, I doubt Utopia is possible. It is certainly not inevitable just by providing unlimited energy.**
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No, not at all. About 20% of the economy of an advanced country is the kind of thing that you might make with unlimited energy — food and manufactured goods. The rest is services. Energy can’t write a novel or make a movie or cut your hair or give you nursing care or advise you on how to lay out your garden or get you front-row seats at a concert.
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Technically the name of this question is a bit of a misnomer, as I'm not talking about just *Velociraptor mongoliensis*, but any dromaeosaur (or dromaeosaur-shaped creature I suppose). How would, hypothetically, a sapient velociraptor wear clothes in order to blend in with human society? Would they just wear things like ponchos? Could they put on pants?
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It doesn't have to be much. A bow tie and maybe some cuffs with diamond links at each wrist.
Prey animals like humans are pretty smart. They know better than to admit that the predatory emperor that has no clothes.
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The thermal jackets they use for birds that are recuperating after surgery might give you somewhere to start since the dromaeosaurs and avians share the same basis body plan. They're basically puffer jacket vests, very Marty McFly in fact. As for pants I'd suggest suspenders that wrap over the back rather than the shoulders as probably a must the rest is a matter of tailoring.
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I think this is going to depend significantly on how long and/or flexible your raptors' arms are. Can they reach behind themselves, for instance? Can they touch the base of their tail? (In front? In back?)
I'm going to assume they can touch their shoulders and [vent](https://en.wikipedia.org/wiki/Cloaca), but have very limited ability to reach behind themselves. I'm going to assume also they have *some* ability to extend their arms outward, because if not, they're going to have a hard time dressing themselves, period. (If they're more flexible, it will give you more options for how to put on and take off clothing.)
As noted, they probably don't *need* clothing, aside from pockets, and they'll probably want pockets on their chest and at their flanks.
For uppers, they *might* just wear shirts and/or vests, like us. I *think* they'd be able to pull a vest (or shirt that opens in front) over their arms and head. Another, easier-to-manage option would be something which is split at the sides; this can be easily pulled over the head and then the sides fastened together. Note that the back will likely be wider than the front and will wrap around the front partway.
For "pants", you can get a bit more creative. One thing, though; because of their tail, they are *not* going to be able to have pants with no complete split the way humans can. One option is to have a cuff that goes around the tail with material in front and back. Like above, the bit that goes over the back will be wider and will wrap around in front of the legs to attach to the other piece. The lower piece might have a fly or flap for, ahem, "sanitary purposes". Another option, if they can reach behind themselves, is to have something more like human pants that they can pull up their legs, but is completely split in back, sort of like a shirt but backward.
I would definitely encourage doing some research on animal clothing. If you're looking to cover "naughty bits" in particular, I would look into animal *diapers* (yes, diapers), since — most animals not being trained to dress and undress themselves and use toilets[[citation needed]](https://xkcd.com/285/) — other clothes are usually *open* in the relevant places. I would also particularly look at *bird* diapers. Yeah, they're a thing. You'll also find them often called "flight suits". The drawback of many of these designs, however, is that they generally aren't designed to be put on by the critter wearing them, and thus the closures are generally not in locations that would be convenient for the wearer.
(That said, it would make for an interesting story if your raptors don't or can't dress themselves, and have sla^Wassistants for that purpose... and either have to be undressed to relieve themselves, or wear clothing that also serves to collect and contain wastes. Of course, it would *also* be interesting if they just didn't care, but that would seem contrary to the premise of your question.)
p.s. On that note, for certain tasks, they might indeed have "clothes" that have a built-in provision for waste collection. (This seems to be a fairly prevalent feature of futuristic space suits, in particular.)
[Answer]
People have put clothing on chickens.
A quick image search of 'chickens wearing cloths' showed mostly head coverings and vests. Pants would be more reasonable with people/animals that avoid pooping in their pants.
Why do people wear clothes:
* Status as a person: a creature wearing cloths is much more likely to be a person then a naked creature.
* Societal status: bling or just pure large number of hours of work.
* Warmth
* Physical protection: cloth armor is very effective, used for thousands of years, still used in the form of kevlar today.
* Information hiding. A poker face is useful. Clothing makes a poker body easier.
* Group identification AKA uniforms.
* Group acceptance.
These will apply to any people including people that look like velociraptors. So they will wear clothing for those reasons and more.
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I want an animal that gets harder to kill as it grows older, biologically immortal.
Every time the animal passes different stages of its potentially endless life, it can choose to "upgrade" its own DNA. Children born from older animals are already born upgraded but can choose more upgrades if they manage to survive. This mechanism makes the animal harder to kill as it grows older.
The upgrades can be anything from decorative displays, higher conscious and subconscious intelligence or various health and strength factors like thicker skin muscle tissue, looser skin to resist bites and scratches or more stiff tendons and cartilage to increase strength at the cost of flexibility or vice versa.
### Thought process
There's no doubt that the children you have in your youth will be different to the offspring produced in more mature ages, not only because of the degradatory process of aging but also because genes change and mutate as time passes.
Virus immunity is nothing but evolution of your body, often instantly.
So evolving in one lifetime is not impossible, after all evolution merely means change and growth, development.
In video games sometimes there are infinite randomly generated dungeons that get harder and harder as one explores more, and the playable character will find powerups to keep up with the difficulty. This is not done to make the game eventually be impossibly harder but to force the player to continuously adapt to new environments and ever changing challenges; it's made to kill boredom, not to kill the player.
Often the player finds more than one powerup and has to choose between them to make play styles variable. Maybe this round you choose 3 bonuses for speed, agility and intelligence but the next you want to try toughness, vitality and stamina. In this way, the dungeon feels unique every time.
I want this game's mechanism to be part of an animal's biology.
### Question
How would this be possible? By that I mean how would the mechanism work and what would enable it to function correctly?
[Answer]
**Unless it’s already programmed in the creatures DNA it won’t spontaneously “evolve”.**
There’s a fine line between adaptation and evolution, the latter mostly applies to the immune system. Everything about a living thing is preprogrammed in DNA with different responses to different stimuli; if A this response and if B other response. A creatures form doesn’t just change unless it’s already programmed to do so, like in metamorphosis. These programmed responses are how creatures adapt; muscles worn down = muscle growth, manual labor = thicker skin, bright sun = tanning and so on...
However the immune system can not only adapt but can also evolve. Normally immune cells have specific receptor proteins and create specific antibodies. But some immune cells can create new combinations at random to fight off potential unknown enemies. This is the closest thing to evolution you’ll find. But please note that this doesn’t create anything “new”, it just recombines existing features (a locksmith that makes different locks but can’t start making doors).
Other than that there’s natural selection, which you already know of so no point in repeating. You want your creature to change during its lifetime. What you need is a creature capable of as much variety as a dog if not more. You also need it to go through partial metamorphosis multiple times during its lifetime, with different forms depending on the environment. If you want the changes to be conscious choices then you’ll want to go the hormonal route. Changes in brain activity during stress causes a change in hormones, which in turn causes your creature to adapt. Simple.
**In short: your video game creature can pick multiple classes during its life that stack together but can’t create new classes. That would require actual evolution, natural selection and trials and errors with the offspring.”**
Sorry for the long answer, have a potato.
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I've decided that the reason my Orcs have green skin is because they have two pigments in their skin cells. The first is melanin, which works the same way as it does for Humans, with the amount of melanin affecting how light or dark their skin is. The second pigment needs to be something else, though I'm not sure what, exactly. **There are two primary things I want this pigment to accomplish:**
1. **It needs to produce colors other than green.** The pigment needs to be able to produce not only green skin but skin of other colors not found in humans, such as red, blue, and purple, potentially more. The idea is that colors other than green are a result of certain genes being more dominant, which usually correlates with certain advantageous attributes, namely greater Arcane or Psionic abilities. So, a red-skinned Orc is likely to be a powerful mage, a blue-skinned Orc is likely to be a powerful Psion, and a purple-skinned Orc is likely to be a Psionic Mage. Thus, these rare skin colors are generally viewed as positive traits, not negative.
2. **I would like for the green pigment to give Orcish skin somewhat more durability.** I'm not sure if skin pigment can do that, so if that isn't feasible, I can have their resilient skin be a result of something else, though I like the idea of the green pigment having an additional function, the same way that melanin helps to protect us from certain types of UV light. I figured in keeping with the "Orcs are durable" idea I'm using, the green pigment could primarily be for making their skin tougher and less likely to scar when it is damaged. This would be why Orcs actually prize their scars so much; if they have one, it means the injury that caused it was not small but they survived it.
I'm wondering if there is something that could accomplish both these things. I was considering having the pigment be copper based. This is because copper is pinkish-orange on its own (which could result in red-skinned Orcs) but is also present in malachite (which is green) and azurite (which is blue.) That just leaves purple, but I haven't been able to find out if copper produces a purple color when combined with something else. However, as it can get three of the four colors I'm primarily after (green, red, nd blue,) it seems the best option for the pigment that gives a majority of Orcs green skin.
**Am I on the right track or is there some other compound I should consider for these purposes?**
[Answer]
I think the copper minerals might work for the colours you've described, but you may need to tweak biology as copper tends to be poisonous. A copper mineral that is purple is Bornite.
An alternative chemical pigmentation is class of compounds, that do exist in nature as brightly coloured compounds, are porphyrins, there are the behind the colour of our blood and the colour of plants.
They can take a variety of colours, depending on what is attached to the ring and on what metal is in the centre of the ring. For red, the heme group in blood is a porphyrin with an iron core and additions to the ring, and if it is a basic porphyrin with iron in the centre it is green [](https://i.stack.imgur.com/cR6PN.jpg)
if instead of iron, it is a copper atom, then the compound is blue[](https://i.stack.imgur.com/d8Fnt.png)
and if its zinc, then you get purple
[](https://i.stack.imgur.com/nnFVz.jpg)
they are called iron, copper and zinc Phthalocyanine
An alternative to chemical colouration is [Structural coloration](https://en.wikipedia.org/wiki/Structural_coloration) would also work and it would be able to provide any colour you need, it is the method of coloration of peacocks feathers
[](https://i.stack.imgur.com/bdznq.jpg)
and macaws
[](https://i.stack.imgur.com/C9L2r.jpg)
and many more creatures, [almost no vertebrates have a blue pigment in them it is all from Structural coloration](https://northernwoodlands.org/outside_story/article/animals-blue#:%7E:text=To%20date%2C%20only%20two%20vertebrates,of%20cellular%20pigment%20called%20cyanophores.).
The color comes from microstructure in the skin that cause light to interact with itself, so that only the color you want is reflected.
Additionally the microstructure if they are made from harder materials (like calcium carbonate with [Nacre](https://en.wikipedia.org/wiki/Nacre)) then it may add an additional toughness to your orcs skin.
hopefully that helps
[Answer]
There are a number of small lizard species with green blood. Their hemoglobin is about the same color as ours, and there's no significant amount of copper in their blood (unlike the blue-green blood of horseshoe crabs): instead, their blood is colored by a biliverdin -- green bile.
When the liver breaks down red blood cells, the hemoglobin is split into two compounds, bilirubin (which produces red bile) and biliverdin (green bile); the former is an important aid in the digestion of fats, while the latter has little function in humans. In these families of skinks, however, the biliverdin is released into the blood plasma and colors the blood green, overriding the red that would normally come from the erythrocytes.
The evolutionary reason for this is uncertain, especially since some of the green-blooded skinks can interbreed with skink species that have red blood and produce viable, fertile offspring.
However: green blood alone would account for a greenish skin hue (just as red blood makes humans with low skin pigment pinkish). How the orcs get tougher skin is probably unrelated.
[Answer]
**Use tattoos.**
You want more than green - you want a lot of colors and you want them to have societocultural significance. It is easier for the orcs to choose that themselves. When they come of age (or occasionally later or even earlier - good for the story!) they get tats in the colors you want that signify who they are, where they belong and what they can do.
Just being colored a way because that is how you were born offers limited grist of the story mill. Choosing a color, or being colored offers more. If you become ashamed of your tattoo, what do you do?
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The Emperor (may he live for ever) feels that walking is too much trouble. He should be able to simply stand upright and his shoes take him where he wants them to. He also wants to impress his subjects by appearing to glide without moving his legs.
In medieval times there is no no obvious technology for this, so his Chief Advisor has suggested that insects be affixed to the soles of a special pair of slippers. When the emperor stands up, the extra weight will cause the insects to start to move in order to escape. The emperor simply has to point his feet in the right direction.
Motivation - Why not get people to carry him? The Emperor wishes to appear to glide everywhere as though by magic. If the soles of slippers are of insufficient area, then he can instead stand on a flat rigid plate and his voluminous robes can obscure its edges.
**Question**
As head of the design team, how do I go about achieving this? Is it even possible?
1. Should I employ a small number of large insects such as Goliath beetles or is it more efficient to employ many, many small insects such as ants?
2. What is the minimum area of the base plate such that the insects can carry the Emperor's weight (200lb 90kg) without being squashed?
---
**Conditions**
1. Insects are farmed for the purpose and replaced as necessary. There is always a spare base-plate/pair of slippers on hand.
2. The surface area of the soles of the slippers/base-plate should be as small as possible consistent with being able to support the Emperor's weight for a ten-minute journey from one throne to another.
3. The floors are smooth and flat. The emperor will be carried by courtiers up stairs or steep slopes.
4. The insects are any species of real-life Earth insect. They can be imported if necessary.
5. Please ask for other clarifications before answering.
[Answer]
Among ants, the record is a 500mg weight lift, 100x its body weight. 90kg mean would take 180,000 ants. Unsure what their endurance is under those conditions. Giving each ant 12mm x 4.16mm of space, you get an area of 9 square meters *minimum*.
Wood (2 x 4s) have a density of 881kg/m^3. A 9 square meter platform made of 1/4" thick material (which is too thin to work, I believe) weighs 100kg. You end up in a cycle where the weight due to increased platform area increases faster than the area required by the ants to support it.
This also ignores endurance issues under such weight.
In any case, you definitely want wheels or bearings of some kind if you attempt this.
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Rhino beetles are rumouredto be able to lift 850 times their own weight. However there is a lack of evidencefor that so let's stick to what can be proven.
<http://jeb.biologists.org/content/199/3/609.abstract>
Dung bettles can lift 100 times their weight. At 20mg and requiring 15cm by 7.5cm then at 1m square they can lift 176 kg. (88 beetles).
Wood (2 x 4s) have a density of 881kg/m^3. A 1 square meter platform made of 1/2" thick material weighs 22kg. Combined weight is 112kg.
Minimising the platform would give 0.8 meter square platform. This could accommodate 56 beetles and could support 112kg. Combined weight would now be 105kg. As this only requires 53 beetles then 3 can die enroute and not be a big problem.
HOWEVER 100 times their weight is not sustainable according to that reference. 30 times is. The tipping point will lie between those two numbers. If an element of selective breeding was introduced then you can push towards a higher value.
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I was thinking about humanoid designs, usually the most prolific version adds a digitigrade posture, looks cool and have some advantages for cursorial creatures providing speed but reducing stability and efficience when walk requiring mor energy than necesary for keep this humanoid creature walking or even just standing, my current conclusion of the causes of this is because the support area is notoriously reduced with just having the fingers contacting with the floor that made me wonder could these humanoids even walk? Won't they continually fall? Is the energy cost of keeping your legs this way worth it?.
Those are the reasons of why I thought a kangaroo-like tail could be very useful for improve the posture providing with third support point and helping with balance.
In fact currently was in develop a robotic tail to help with balance problems and almost sure is possible use this tail to stand, not for much time but maybe for rest short time periods is good.
[](https://i.stack.imgur.com/ZL7r5.png)
Even if my assumption about the use of the kangaroo like tail is wrong, the tail presence still being interesting and problematic, because I remember read that the presence of tail in a humanoid shape is harmful or contradictory to the correct posture, gluteus and other muscles used to stand, because the tail required other massive muscles to work.
But even I found some infomation which would indicate this is less problematic as could seems. With [sthenurine](https://en.wikipedia.org/wiki/Sthenurus) kangaroos which probably had a semihumanoid erected posture convergent in some aspects with hominidae features, obtaining a digitigrade (or even unguligrade) posture supported by the tail, coupled with the fact that this family of kangaroos would have put jumping aside in favor of walking, being able to move their legs independently. But this were just some visions and reconstructions of these species, as they are not conclusive and something truly functional still needs an analysis.
And as last complemente, kangaroos' tails are special, are very different to other species, these kind of tails have a great versatility, because even looking as rigid supports to stand, can turn flexible and be used with ondulatory moves to swim (as you can see in this [video](https://www.youtube.com/watch?v=Lj8kQycZvYw)) and other interesting feature is the nail tail from the [wallaby](https://en.wikipedia.org/wiki/Northern_nail-tail_wallaby), which practically have a little claw with unknown function but could be for defense or be used in [drepanosaurus](https://en.wikipedia.org/wiki/Drepanosaurus) like style.
So my questions are: how to get or develop and anatomically correct humanoid with a strong and versatile kangaroo like tail?, what kind of anatomical changes are necesary?
I emphasize that my problems are with the skeletal and muscular configuration of this fictitious species, since generally it would have to have a torso similar to a human but underneath with the aforementioned characteristics of digitigrade and a versatile and strong tail like a kangaroo.
A last addition, this question can be highly related with this
[How much I can change the humanoid body plan and still be able to perform the high speed throwing?](https://worldbuilding.stackexchange.com/questions/199712/how-much-i-can-change-the-humanoid-body-plan-and-still-be-able-to-perform-the-hi)
[Answer]
## Tails don't help you be digitigrade
First off: some humans ARE digitigrade. About 5% of healthy children undergo growth spurts where their calf muscles grow slower than their tibia and fibula causing them to walk on their toes. Because the calf mussels are pulled tighter than normal, they stand on their toes using the tension in the muscles rather than needing to exert any extra force to bring them up to a digitigrade posture. So, for these people, it is as comfortable to stand, walk, run, and jump up on the balls of their feet as it is for most people to do those things flat footed. This can cause temporary balance issues as they may transition back and forth between digitigrade and plantigrade, but these balance issue have nothing inherently to do with being digitigrade.
While more rare, some perfectly healthy adults are also permanently digitigrade. This is most common among people who are/were athletes who needed MORE balance (boxers, wrestlers, etc.) where they spend/spent so much time training in a digitigrade posture, that the muscles tightened and they assumed this as the default posture. A plantigrade posture is easier on your bones and muscles, but makes you slower, less well balanced (not more as the OP suggests), and only uses less energy if your muscles are not designed to be digitigrade. Despite the the smaller ground contact area, humans in a digitigrade stance have much better balance than plantigrade humans because they can react better to lateral forces without the risk of being rolled over their heels: thus the expression "[caught flat-footed](https://idioms.thefreedictionary.com/caught+flat-footed)".
The only reason most humans are plantigrade is because it causes less health problems as we get older. Because the bones in our feet are not fused together, extended use of the digitigrade posture can stretch out ligaments and cause foot pain. Humans are designed to be nomadic. We can walk for very long distances compared to other animals, but this is not a necessary feature of all humanoid or bipedal beings. Ostridges for example are bipedal and digitigrade and suffer no significant negative side effects from it... but they are built for sprinting, not distance, so they have evolved to be better suited to a digitigrade default stance.
## Why so many bipeds have minimal tails
The biggest problem with the bipedal body design is weight. Things that make you heavier are a bigger deal than when you are a quadruped; so, heavy things like tails actually slow you down making them counter-productive. Tails only help bipeds with balance when their body plan is leaned forward (like a kangaroo or t-rex), but when you make your weight distribution more vertical, like a human, you can drop the weight of the tail allowing you to become faster and still maintain good balance by centering your weight over your feet. If you are upright, a tail will just make you want to fall backwards.
Going upright, and loosing the tail frees up a lot of weight which means your bipeds can also support larger stronger arms which is important specifically for humanoid body designs. For a biped to have a forward leaning torso, adding the weight of large arms would have to be offset by an equally heavier tail (which is probably why kangaroos and t-rexes have such small arms)
In summary: if you want an upright biped to be digitigrade just make them digitigrade: it works well, and adding a tail only adds problems, not solutions. BUT if you want to add a tail for the sake of adding a tail, then you will need to make the body lean forward so that the body and tail can counterbalance each other.
[Answer]
Let us suppose that we have a normal human being without a tail. If we focus on the pelvic skeletal area, we can see the vestigial remnants of the tail which has devolved from our distant ancestors, in the form of the coccyx.
Now, the OP proposes that we add a substantial tail to this basic body plan, a tail that is as capable and useful to its owner as a kangaroo's is to its owner, capable of supporting the being's full weight and providing propulsion in both terrestrial and aquatic locomotion. The OP is correct in believing that adding such a tail would not be as simple as replacing the coccyx with the far more substantial appendage desired.
Why *wouldn't* we be able to just 'whack on' a big tail and call it a day? What would we have to do to make it work?
Consider the dimensions of this new tail. As any tail, it would consist of an extension of the vertebral column beyond the pelvis. In order to be able to support its owner's full weight and contribute to locomotion, it would have to have vertebrae that are robust enough to support the load, with muscle attachment processes big enough to anchor strong muscles. It would have to be *at least* as long as the leg plus the length of the foot - it would not support its owner's weight directly on its tip, but on at least twenty to forty centimeters of the end of the tail, almost like an extra foot, much as kangaroos use their tails.
With all this muscle and bone, we are looking at a substantial, massive appendage, with vertebrae roughly the same thickness as the lumbar vertebrae, surrounded by muscle that might make it as much as ten centimeters in diameter where it emerges from the pelvis. Unlike the picture of the artificial tail, it would emerge from the pelvis in line with the spine, not at right-angles to it.
This extra mass of muscle and bone would not come without consequences. The main consequence would be the alteration of the pelvic opening. Naively, this tail would 'bulk up' the coccyx on both sides, but this would result in it projecting into the pelvic girdle. For kangaroos, which give birth to offspring that weigh a few grams, this is not an issue, but for a human, which gives birth to offspring weighing five kilograms or more, with heads that have a diameter of ten centimeters, obstructing the pelvic opening could be fatal for both mother and child. This could be solved by moving the pelvic girdle ventrally so that its opening was unobstructed. This would result in the lower back appearing not almost flat from side to side as in modern humans, but with a rather more projecting bump on the lower back. At the very least, this would make lying supine more difficult, as the pelvis would tend to roll to one side or the other.
The next problem is that of locomotion. Unless the tail is even more bulky and muscular than I have described, it would not be used as a means of propulsion when walking or running. Fully tripodal locomotion involving the tail would be awkward enough that it is unlikely to evolve at this point. However, the presence of this weighty, bulky appendage would not be without its effects.
When walking and running, if the pelvic spine was vertical as it is in modern humans, a tail of this bulk would collide with the legs and the ground unless it was held up and to the rear. However, in that case, the weight of the tail behind its owner would shift the centre of mass backwards unless the torso was moved forward to compensate, resulting in a forward-leaning posture when walking or running. In fact, this would likely lead to the natural position of the legs being not directly in line with the torso, but being at a slight angle. This change would be reflected in the shape of the pelvis, with a slightly different shape to the pelvic bones to allow for the altered stance.
Having such a tail would mean that when stationary, the being could lean back on their tail, holding their torso fully erect in a tripodal stance, almost as if they were carrying a tall, narrow unipod seat around with them. As humans' upright stance likely evolved in order to see over tall grass in a plains environment, this tail would assist in such a posture, and allow a lookout to maintain a more comfortable stance while standing watch.
Given the strength of the tail, it would be capable of pushing its owner forward from a standing position, making the transition from standing to walking or running easier and more rapid, and would also allow a powerful braced two-footed kick as practised by modern kangaroos.
Given sufficient lateral musculature in the tail, it could contribute to aquatic locomotion to a small degree, given that in humans, the bulk of the power when swimming is provided by the upper body. This musculature would also enable the tail to be used as a weapon, to be swung about to bludgeon an enemy, as well as its use as a brace to strengthen a kick.
The tail is unlikely to be prehensile, given that African monkeys do not use their tails for grasping, while only South American monkeys use their tails in that fashion. Tailed Humans, probably being evolved from African monkeys and apes, would be unlikely to have prehensile tails due to that ancestry. However, the OP may be considering an alternative evolutionary path that allows for a prehensile, grasping tail.
Should this tail be prehensile, its strength would allow it to be used for crude grasping, and to help anchor an object being worked upon by the more dexterous hands.
The last significant difference in anatomy would be in the brain. In contrast to modern humans, these tailed humans would have a slightly different brain structure in order to provide the motor output from and sensory input to the tail. It wouldn't be a particularly major difference, but would likely be enough that an expert could tell the difference between a modern human and a tailed human from their gross brain anatomy, especially if the tail was prehensile.
The energy for this tail could easily be provided for by a modern human's digestive system, so there would be no need for any significant change in dentition, gastrointestinal or cardiopulmonary anatomy.
There would be other consequences to this change in anatomy, including likely alterations in the manner of copulation, preferred sleeping positions, furniture and transport design, and other sociological implications, but these go beyond the scope of the OP's question.
[Answer]
## Nature provides a model of an upright digitigrade biped.
Therizinosaurs are a group of dinosaurs that are basically upright digitigrade bipeds, they are not as upright as humans, but that is because they have a tail which means they need to sling the body slightly forward for balance, the bigger you make the tail the more forward the body needs to be. so your best bet is to estimate how much the tail of your creature weights, that will tell you how much you need to change the posture. Your problem is if you want a tail long enough, thick enough, and strong enough to support the weight of human well, it ends up weighing so much your person is closer to horizontal than upright.
[](https://i.stack.imgur.com/WMLlc.png)
Note the pelvis of this group has a very sharp bend in it to keep the tail pointed backwards. The tail supports the muscles that move the legs so it needs to remain roughly horizontal. Your tail does not need to be that horizontal.
there is already a question and answer about tails and balance so you can look for more info there. [Lizardfolk and the problem of balance and anatomically sound tails](https://worldbuilding.stackexchange.com/questions/171328/lizardfolk-and-the-problem-of-balance-and-anatomically-sound-tails/171345#171345)
**You are correct that putting a tail on a human frame causes all kinds of problem, but you don't have to worry about that**. Mammals evolved butt muscles to move the hind leg because they could not anchor them to the tail the way lizards and dinosaurs do, because they had greatly reduced the tail. If your creature evolved with a tail there is no reason to believe it would have this kind of musculature, Kangaroos do not. Note the kangaroo musculature is also different than the dinosaur system.
**Digitigrade** animals have much larger toes than humans have, so as long as you make the toes bigger you can put a biped on a digitigrade stance no problem. The energy cost if being digitigrade is not significant, you need muscle tension to stand no matter what you are, being digitigrade does not make it significantly worse. It is harder for humans to walk digitigrade but humans evolved plantigrade, it is harder for digitigrades wo walk plantigrade as well. Just like any posture it comes down to the arrangement and size of muscles. There is a saving to being plantigrade but it is so minimal that you can safely ignore it when designing a fictional organism unless you absolutely need them to be endurance walkers like humans.
As a side note at least two groups of dinosaurs use their tails for support while standing on their hind legs, diplodocid sauropods and stegosaurs, however they are not bipeds, only standing to feed. these tails are very thick and strong (just like kangaroo) also both groups use them as weapons, so you do have some comparisons to look at.
## So what changes do you need to make
You need **bigger toes** you also need to decide what kind of foot to give them, specifically how many toes and in what arrangement, kangaroo use four toes to get a pseudo-three-toed foot, [wallaby foot dissection](https://svpow.com/2009/11/06/things-to-make-and-do-part-3b-wallaby-feet/) but you could use a dog like foot, dinosaur like foot or a selection of other digitigrades.
[](https://i.stack.imgur.com/L0lxd.png)
You need a **bent pelvis**, your pelvis needs to have a bend in it just like therizinosaurs to get the tail pointed is a reasonable direction, although it does not need to be bent as much. You will likely want to reinforce the sacrum as well, since you want it to support lateral loading.
You will need to adjust the musculature, for one thing your creature will not have a butt shaped like a human one, the musculature from the tail will blend together with it.
you will need to **tilt the body forward**, your creature will not be as upright as a human, they will be leaned forward, likely close to 45 degrees maybe a little less, to balance the weight of the tail.
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[Question]
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I've been wondering for a while and have seen conflicting results, so I'm asking. "if an asteroid were to hit an extremely earth-like planet, would it cause the most damage when hitting the water, land, or coast? assume conditions of planet to be identical to earth" additionally, what makes this the most devastating?
Assume (an event) large enough to kill 75% of all life on earth within 50 years of collision.
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I've read that the worst place for a Chicxulub class impact (relative to land, sea, or coast) is in shallow water, i.e. continental shelf. Coastal waters, that is.
Why? Because there's water, and there's rock without too much water on top of it.
The rock will be blasted into partial orbits, with the "burning sky" effect (everything on earth will be under an oven broiler for an hour, producing a planet-wide firestorm), dust blasted into the stratosphere (which, combined with soot and ash from the fires, will result in an "asteroid winter" as well as the sulfuric rain mentioned in another answer), and sea water quenching the glowing rock at the actual impact site will cause global cloud cover almost instantly, resulting in flooding, rain to carry the sulfuric acid, massive erosion, and general mayhem.
Deep water shelters the rock below, unless the asteroid involved is much larger than a few kilometers, and land lacks the prompt cloud effects and planetary rains.
From comments, there's also [this paper](https://www.sciencedaily.com/releases/2020/05/200526111320.htm), which suggests that the angle of impact also contributed -- by way, once again, of maximizing the mass of material thrown into and above the atmosphere, as well as its dispersion.
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If we talk about damage in general (and not damage to a specific civilization settled in a specific area of the planet) in the short term, I would say that the most devastating location for an asteroid to hit would be an ocean, because of the huge waves and tsunamis that would hit all nearby continents.
However, if we're talking about the long-term consequences, maybe the location is not that important after all. According to recent studies regarding our own planet, the asteroid that killed the dinosaurs caused a rain of sulfuric acid, coming from the sulfur found in the rocks where the asteroid hit. Over time, this acid rain caused the acidification of the oceans and this would have also caused a mass extinction in the marine environment.
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I have seen some questions in this site regarding how to weaponise black holes. One very funny one was the **Black Hole Launcher**, which many to quick to point out how absurd that was. However, I had another idea which I think might be more viable, where instead of having the black hole be a "projectile", the black hole is formed "on impact".
More specifically, I referred to how high-energy particle collisions can temporarily create **Micro Black Holes**, such as in TeV Particle Colliders or when Cosmic Rays interact with the atmosphere. Of course, they only last for a while before they evaporate into Hawking Radiation.
To solve this, I searched for the energy requirements to make stable Micro Black Holes, and it seems that [100 TeV is enough to make Micro Black Holes that are stable](https://arxiv.org/abs/1611.04949). So, I thought, if we have strong enough particle accelerators that let particles be as energetic as that, and make the beams collide, it is likely that Micro Black Holes that last for a while can be made on the spot.
[It is something like this question, but rather than move a Black Hole, it makes them.](https://worldbuilding.stackexchange.com/questions/183279/is-a-particle-beam-the-best-method-to-fire-a-black-hole-at-a-target)
I am also aware that normal and current particle accelerators are HUGE and bulky and inefficient, so I decided to just have some unobtainium ([Q-Balls](https://cds.cern.ch/record/330517/files/9707423.pdf)), which allows particles to have such high energies while letting the weapon be handheld (*or at least artillery-sized*) at the same time.
So far, it seems more viable than the Black Hole Launcher by a mile. Also, as an upside for this weapon, the same accelerators can be used to feed the stable Micro Black Hole. However, I am still stumped by a single question: *Just what are the effects of such a weapon, both the high-energy particles and the Micro Black Hole? What harm can they do?*
PS: *As shown in my comments, these Black Holes can either be as light as a few micrograms, or as heavy as asteroids and mountains. Also, 100 TeV only seems to be a bare minimum. Lastly, when I mean stable, I mean "last forever" kinda stable. Extremal, if you will.*
[Answer]
### What can they do? Practically nothing.
You didn't include the [reality-check](/questions/tagged/reality-check "show questions tagged 'reality-check'") tag, so I'm going to assume that your source is right and stable black holes this size are possible.
Now, let's get into what they can do. As my main source, I used [an article by CERN about the safety of LHC](https://home.cern/science/accelerators/large-hadron-collider/safety-lhc):
>
> If stable microscopic black holes had no electric charge, their interactions with the Earth would be very weak. Those produced by cosmic rays would pass harmlessly through the Earth into space, whereas those produced by the LHC could remain on Earth. However, there are much larger and denser astronomical bodies than the Earth in the Universe. Black holes produced in cosmic-ray collisions with bodies such as neutron stars and white dwarf stars would be brought to rest. The continued existence of such dense bodies, as well as the Earth, rules out the possibility of the LHC producing any dangerous black holes.
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In other words, as long as there are big objects in the universe (like Earth), no black holes that tiny are going to have any measurable effect on anything. It doesn't say it explicitly (maybe it does and I just didn't see it), but here's my explanation (bear in mind it might be completely wrong): **It's just too little mass to have any gravitational pull.** From what I see on [Wikipedia](https://en.wikipedia.org/wiki/Micro_black_hole#Minimum_mass_of_a_black_hole), we're talking on the scale of micrograms. The earth, to get a 1g acceleration inward, has trillions of trillions of trillions of kilograms of mass. **These black holes are far more affected by other objects than other objects affected by them.**
There's my best guess, I hope it helps.
But while I'm at it, I might as well give you an idea for how you could massively scale up your particle accelerator. :)
This idea is from *Death's End* by Liu Cixin, the third book in the Three-Body Problem trilogy (if you haven't read it, I highly recommend it). In it, they construct a massive particle accelerator that rings the entire solar system. It's not enclosed, since one of the main reasons LHC and other accelerators are enclosed are to make a vacuum, which we already have in space, and each ring speeds up whatever it is and sends it shooting off to the next ring, which continues the process. Eventually, they let it go shooting away from the solar system at near lightspeed.
Don't know if that last bit is helpful, but I couldn't resist sharing what I think is one of the coolest gadgets I've seen in sci-fi.
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EDIT: Okay, so you've now told me that these can be up to trillions of kilograms. So I'm going to go with the figure of a trillion for this next bit (also please note these are guesses, we don't actually have data on this):
If fired at a person, the person would be torn apart by tidal forces well outside their Roche limit (somehow it feels a bit wrong to apply that term to people, but black holes will do that). Within a couple centimeters of the black hole, there are hundreds of m/s^2 of acceleration, but a meter away it's pretty much negligible. So if they fire for your heart, you'll pretty much have your heart ripped out as the rest of your body stays intact.
If at a planet, here's where it gets a bit interesting. I'd expect it to be like Randall Munroe's Neutron Star Bullet scenario (which I can't find online, so I guess you need the book *what-if* to check it out): It'll fall toward the center of the planet, ripping its way through the same way it rips through a human's body. Once it's there, it'll kinda just... stay there.
At that point I see a couple options. (1) It'll rip everything within reach and then just stay right there in the middle of the planet chilling. (2) Pressure's too much or something so that whatever's outside keeps getting pulled in. The black hole grows significantly (okay, it grew significantly in number 1 too, but not as much) and keeps growing. It might possibly get large enough to cause serious problems for us unsuspecting humans above.
Again, this is guesswork. I've never seen a trillion kg black hole and I haven't had the chance to fire them at someone (though the first test subject might be an unsuspecting little brother). If you do happen to get data, please let me know! I'd be fascinated to see real stuff on this. But I guess that's not likely.
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For starters, if you have a weapon that is capable of generating a black hole, you've already got a blockbuster on your hands. It is simply firing a lot of energy in a single point, so at a much lower setting you could easily destroy stuff.
If you can make a bullet-sized black hole, you can level a city. The black hole's gravity will be negligible - the amount of energy involved will not. I'd like to refer you to my answer on another question, [Finding out the mass of a black hole for it to last ten thousand years](https://worldbuilding.stackexchange.com/q/186425/21222):
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> (...) a black hole with a mass of 1.55 million metric tons and measuring 0.0000000046 nanometers across (~40 times wider than an atom). Any gas around it may reach a temperature over dozens of trillions of kelvin. At the distance characters and portals will be from the black hole, that means enough luminosity to probably cause a lot of destruction. As per the comments in this answer:
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>
>
> >
> > The black hole will emit 150 TW of blackbody radiation at 80 tera-Kelvin. You won't be as much sucked in as literally torn apart by gamma radiation. The black hole will "only" emit 16 grams of photons per second (yup, you read that right), but they'll be moving at the speed of light. For comparison, the Hoover dam produces measly 2GW, and it's much bigger than a 20-meter sphere.
> >
> >
> > -[John Dvorak](https://worldbuilding.stackexchange.com/users/807/john-dvorak)
> >
> >
> >
>
>
> 150 TW means that, [in a little over four hours, the black hole emits as much energy as all nukes ever detonated in history (until 2020), combined](https://en.wikipedia.org/wiki/TNT_equivalent#Examples).
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Supposing you shoot nanometric black holes and you can control them so that they disappear after just one second, it is still a bullet emitting ~10 GJ of radiation, which is about five Hoover dams all pouring out all their output into a small point for a second. You better be very far away from your target when you shoot.
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An innovative treatment for cancer and broken bones involves the precise removal and replacement of the affected tissue with artificially grown tissue. The tissue (or piece of bone) is "beamed" in and out by the Handwavac-70 machine. Rarely, due to handling errors - somewhat similar to the Therac-25 failures-, the new tissue is discarded instead and an equivalent volume of ambient air transferred into the original tumor site. Assume that the removal process itself is not faulty, we are not randomly beaming away pieces of the vena cava, for example, but we might operate on cancerous tissue right next to it. The volume is equal to that of the replacement tissue, which depends on the size of the tumor or broken bone segment. The replacement tissue would have contained agents to improve healing, think nanobots and the like, but the air unfortunately does not.
What are the effects of such a mistake? Where would the introduction of air (not oxygen, normal air) be benign/unnoticable, painful/dangerous or outright disastrous?
Edit: And how quickly would the effects become apparent, i.e. would the mistake be obvious to the operator?
[Answer]
**Probably death**
It depends if the air can escape the body. If it can't you'll probably get an air embolism.
The site will start to fill up with blood and other fluids. That much is clear. If the air can't escape the body, it'll probably get pushed into the veins towards the heart. From there some are likely to travel towards the brain, which can form a blockage. This will be akin to decompression sickness, but you can't reverse it. At the very least some part of the body will get the bubble blockade and die off.
I don't know how much air is needed to kill a person, but from what I can surmise from decompression sickness, it doesn't need to be much. The cancer in air volume is likely much higher, so probably a lot of the body will get affected by blockades. That something important will be blocked is likely as well, so my guess is that in practically all cases someone will die or receive severe permanent damage.
[Answer]
You are severing a piece of tissue without any further action.
That will result into a bleeding from all the blood vessels which were not sutured; therefore, the air cavity will not contain air for long time. Depending on the actual location blood and something else will fill in the cavity.
If it is in the intestine for example, part of the gut content will go into it, which doesn't sound like a good situation.
If is part of a bone you have actually interrupted the bone continuity or strongly reduced it, again not a particularly good situation.
If the patient is lucky enough to not get a septic shock or an embolus because of the wreckage happened in their body, they might grow some filling of the cavity. There are cases of patients having survived a gun shot in their head and have lived ever after with a open hole in their forehead.
[Answer]
**Air is ok. Uncontrolled bleeding not ok.**
Think about an open surgery on that tissue next to the vena cava. When they open the patient, there is air in the belly. When they close the patient minus the tumor, some air is left behind. It is resorbed.
Think about laparoscopic surgery. They pump the belly full of gas like a balloon to lift the front of the abdominal wall like a tent and give them space to move around in. Sometimes they use CO2 to fill the abdomen because it gets reabsorbed quicker because it is more soluble.
In either of these situations if the person has a scan shortly after surgery you can see bubbles still there.
The real issue with this transporter tech is bleeding. If I have a tumor, that tumor is being fed by arteries. If I beam the tumor out, somewhere there is an artery that now has a cut end. Blood is going to come out! Controlling bleeding is a major part of surgery. Often they address blood vessels first, tying them off before cutting the far end. For your fiction you can assert that the stuff you usually beam back in has factors to coagulate / cauterize or otherwise stop bleeding. If you just have air, the blood that would have gone to the tumor will pour into that void and your patient may go into shock.
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Additional reading
[Postoperative pneumoperitoneum on computed tomography: is the operation to blame?](https://pubmed.ncbi.nlm.nih.gov/25307607/)
>
> Abstract Background: Postoperative radiographs demonstrating
> pneumoperitoneum are a vexing problem for surgeons. This dilemma stems
> from uncertainty regarding the length of time for resolution of gas
> introduced operatively via either an open or a laparoscopic approach.
> We attempted to quantify the duration of pneumoperitoneum after both
> laparoscopic and open surgery in an animal model.
>
>
> Methods: A prospective study using 2 groups of 10 pigs (Sus scrofa)
> was performed. The animals were assigned to undergo either an
> exploratory laparoscopy or an open abdominal exploration.
> Postoperatively, sequential computed tomography (CT) scans were
> performed to assess for the presence of pneumoperitoneum.
>
>
> Results: Pneumoperitoneum resolution occurred sooner than average on
> CT scan in the laparoscopic group when compared to open group (1.79
> days vs 4.73 days respectively; P value of .02).
>
>
>
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Of course, there are a lot of different kinds of ITV's (Interstellar Transport Vehicles). Some only fly at 0.05c and some quiet a lot faster.
Today, I would like to ask what kind of Protection against Radiation and Debris would be in use if we had to protect an ITV flying at 0.8c. So around 239833 km/s.
I don't want to assume any flat out impossible ideas, it is suppose to be somewhat realistic.
A few of my own thoughts:
At 0.8c we travel such a long distance in a single second, that any sort of meaningful Point Defense System just doesn't work. A Laser is barely faster than the ITV itself (Which is kind of insane to think about). Not to mention that by the time a Computer sees, locks on and shoots at a Target this said target is probably behind you.
So my thought is that we need a passive protection. In other words, why avoid debris when you can fly through them ?
The first idea was to use a Normal Layered Shield. So you don't stop anything coming at you with the first layer, but like 20 maybe do the trick.
This has the problem though that your shield wears down. And if it is hit twice at the same spot, well that ain't too good.
So the next idea was some sort of Plasma shield. Which is great, in theory. This Plasma shield would have to be a few Million degrees hot at best, just to be able to Vaporize big chunks of debris. I could easily see such a shield being as hot as the core of the sun or a Fusion reactor, which sort of raises 3 problems.
1. Where is all the heat going ?
2. Where is all the matter coming from ?
3. Where is all the energy coming from ?
To the first, into space ? I would assume you need a stupid long ship to have this sun more or less be far enough away from the main body. And you could not run it at 100% all the time as your ship would just sort of melt.
I thought that maybe you could try to recycle most of the Shield´s Plasma and then fill the rest up with the debris your run over.
Since we need Fusion for such a shield anyways, I would guess Fusion would provide the Energy. Maybe the Shield itself is just some kind of Fusion reactor where the Fusion product is propelled outwards and shaped into a cone that protects the ship.
So yeah, this is how far I got. I would guess a Plasma shield is the only really option you have at this speed but I could very well be wrong.
Anyways, thank you for reading !
[Answer]
>
> I don't want to assume any flat out impossible ideas, it is supposed to
> be somewhat realistic.
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>
>
## The issue of inertia
Most Sci-fi either hand waves in some variation of inertia dampener or non-newtonian drive, neither of which have any scientific basis. When you accelerate a crew in the real world, they experience inertial forces similar to gravity; so, if you want to accelerate a person over a long period of time, you want to stay somewhere in the range of Earth's gravity (9.8m/s^2). At this acceleration it will take you about 283 Earth days to reach a speed of 239,833 km/sec.
## The issue of conservation of mass and energy
Another issue you will run into for realism is the conservation of mass and energy. For a ship to both speed up to and stop from 0.8c under its own power your ship will need a LOT of fuel. Anti-matter specifically since nuclear fuel can't get you going that fast. To reach that speed you need need 40% of your mass to be antimatter and 40% expendable normal matter assuming you have a 100% efficient engine which you generally don't get in real life. Then the remaining capsule will need to also be 80% matter/antimatter fuel. This means that your ship would have to be made of 96% fuel before you even start to consider powering a plasma shield or anything fancy like this.
Using ground-based-laser accelerated sails, you would not need nearly so much fuel, but you'll still need to slow yourself down meaning you are looking at 80% anti-matter.
To complicate this, anti-matter is REALLY hard to contain; so, keeping it contained for such a long trip with so little mass to expend on a containment systems will be nearly impossible as well.
## How to achieve those speeds
The most realistic solution IMO to this problem is the use of a **bussard collector**, a magnetic field device that scoops up all the hydrogen from space within several km of your ship to use as fuel. It's definitely not doable with today's technology, but at least the theoretical science for one already exists. So, you only need to accelerate your ship under its own power up to a small fraction of light speed until you can start gathering enough hydrogen to run a fusion reactor to keep yourself going. While a bussard collector will not protect you from an enemy torpedo, it will protect you from the thin atmosphere of space while simultaneously cheating the conservation of mass and energy dilemma.
## What about combat?
Just because you can get going at 0.8c does not mean you can fight at those speeds at all. It's not just a matter of seeing your enemy. Since any significant course correction would take months, there is no real way to intentionally put yourself in the path of an enemy ship you are trying to intercept at those speeds. This means you need to predict where an enemy ship will want to go by fortifying planets and other places of tactical and economic interest. So, while an enemy ship might travel between stars as 0.8C, it will begin slowing down hundreds of days before it arrives at you planet so that it can effectively stop at it. So when it arrives, it will be moving at the much more sane speeds of just a few km/s. At these speeds, ships will be able to maneuver enough to engage each other and traditional thoughts regarding detection, interception, etc. will all apply.
[Answer]
**Needle ship.**
1. The most relevant impactors are those encountered in the direction of travel, directly ahead of the ship. Mostly the ship will be ramming slower things in the way because it is so fast.
2. The smaller the forward profile of the ship, the less things it will ram. The ship is thus maximally long and thin, a flying needle.
3. The ship tapers to a molecularly sharp point in front, which can be regenerated. The idea is not to ram into things ahead, but divert them so that they change course with a minimum of kinetic energy exchanged. Hopefully this is mostly hydrogen molecules.
4. Lasers can fire forward from the shop. There are many and they illuminate what is ahead. With increased energy, the lasers themselves might be able to deal with smaller objects.
5. More massive objects detected in the path can be met with projectiles. A regular railgun projectile will suffice because at a speed of 0.8c it will convert whatever it hits to plasma. The needle tip can traverse hot plasma.
[Answer]
The ship needs a small fleet of small sensors flying ahead of it to detect any potentially problematic objects as they fly past and help deal with them. The main ship could be fed data concerning speed and direction at the speed of light so would get advanced warning of approaching objects at 0.8c and could have time to activate high powered lasers to destroy the approaching object.
The sensor fleet would be small, have redundancy and be capable of replacement from the mother ship to a limited extent. The sensors would fly ahead and in a ring around the main ship so that if any sensor was hit the debris would not hit the main ship.
[Answer]
Isaac Arthur's "Interstellar Challenges" video raises the same concerns, namely that, after a certain speed, point defenses are just not reliable. A laser-driven ship has the advantage that the laser can fire before the ship gets in the beam, which could somewhat clear the path, but you'll need something more , especially if you're going somewhere without a huge relay of lasers from both ends.
In addition to Wilk's needle-ship design, a couple other things are mentionned:
* Hydrogen fuel tanks could be put on a conveyer belt, since they also make decent shielding. If one gets damaged, convey it out of the way for repairs, while another takes its place.
* You don't have just one light sail; you have as many as you have room for materials. Throw some spares out in front of your ship, perhaps pushed farther ahead by your own lasers, and let those serve as shields. The farther ahead they are, the better, as any debris that penetrates them will be slightly deflected. The drag from small impacts will cause the sails to fall back toward the ship, where you can pick them up to be recycled and replaced.
[Answer]
Leaving all fancy yet-to-be-invented physics aside, one plausible method would be pushing large chunk of ice in front of the ship. The ice can be used as reaction mass for fusion engine, works as a shield and is useful resource anyway. The ship simply hides behind the iceberg in the acceleration and cruise phase.
When decelerating, the whole setup gets turned upside down, so the fusion torch of the ship blows obstacles away from its path. Collision with large asteroids remains a risk factor which makes the story more interesting. Nobody actually knows how many rocks there are flying between stars. There definitely are few, as astronomers have recently discovered.
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My completely unrealistic idea- have an atomic diverter, a device that takes objects in front and reconstructs them behind the ship in mostly the same way.
My more realistic idea- have a suicide ship in front, basically a big metal wall with rocket boosters(or whatever your propulsion system is) to block all the debris. Of course, you shouldn't fly through any huge asteroid fields, but it should help a lot with random space debris.
probably not much help, but that's my 2 cents.
Honestly surprised nobody downvoted this answer, so I guess I'll add a bit more.
The [Atomic Diverter](https://www.fanfiction.net/s/13471946/2/Last-Chance)(4th sentence of the 3rd paragraph) was something I made up to solve this problem, but with advanced technology and FTL travel. I do not go into how it works, so I have no idea if it is possible.
Your suicide ship would need to be at least as wide as your other ship, with a way to correct itself on at least 2 axis (X and Y, viewing from the front. Y isn't as important, but you might want it) either using engines or these [reaction wheels](https://en.wikipedia.org/wiki/Reaction_wheel) I've recently learned about. Please note I am not a physicist or anything, so they might not reset the ship fast enough or be too small for your suicide ship.
[Answer]
\*\*A detached shield or series of shields \*\* made of harvested matter traveling in front of the spacecraft. (Plus magnetic shielding for charged particles.)
Basically you would have to accelerate properly shaped impact shield/s to the same speed you wish to travel at and then travel in the 'shadow' of that shield all the way to your destination.
The shield/s don't decelerate at the end of the journey but the ship does.
One serious problem will be the 'flip' for the deceleration phase of the journey. Unless you install two drives (front and rear) your ship has to expose its longitudinal axis before it can start slowing down. So either you build an unrealistically huge (wide) shield or you make the turnover as fast as possible with fingers crossed.
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So, imagine you live in a very humid climate.
Much more than any tropical country. Fire doesn't appear in natural circumstances or, if it does, goes out extremely quickly. It's kind of a folk tale until by chance someone lights up some of it in a particularly dry building. In those circumstances, how would fire affect technology? I assume people would prioritize specific developments -weapons, certain things needed for survival in winter-, but I would like some input by more knowledgeable writers.
[Answer]
**Humidity is not enough**
Even when humidity is nearing 100% saturation, you can still start a fire. What does make fires hard to start is rain... lots and lots of rain. When it rains, would-be firewood becomes nearly impossible to light using primitive means for the next 1-5 days. Also, it has to be rain, not snow. The moisture from snow does not seep into the wood; so, if you have snow capped mountains, your people could just go up to the mountains to collect firewood. So for your world to act like you want, you need the whole planet to be constantly hammered by liquid rain. This is nearly impossible on a world that looks like Earth; so, your planet will need nearly all of its land mass isolated to the tropical zone with short mountains and a fairly small axial tilt to prevent your people from experiencing colder-drier seasons, rain shadows, or snow capped mountains where they could make fire.
**Without fire, you lose out on several really important early inventions**
1- Metallurgy: Without metal tools, you are stuck in the stone age. Without metal tools, agriculture becomes so labor intensive that you can not reliably sustain yourself off of farming in most regions. If you can not stop to farm, you can't build a very large or advanced civilization.
2- Ceramics: This is not just pots and cups, but bricks too. Your people will still be able to make wicker baskets for holding dry goods and use hollow gourds to store liquids, but lack of bricks makes creating permanent structures in tropical areas where exposed stone may be rare virtually impossible.
3- Mortar/Concrete: The active ingredient in early forms of mortar and cement is quicklime which you need to scorch limestone to get. Between this and lack of bricks, making large permanent structures becomes a lot harder. Add to this a lack of metal tools, and shaping stone into stable stack able bricks is nearly impossible anywhere. Stone with mud mortar or compressed earth construction will make mostly permanent buildings in dry areas, but since you don't have dry areas, you are basically stuck living in building made out of wood, leaves, and grasses.
4- Fire-hardened wood: fire is often used as a way of hardening wood for various purposes. Especially since you are in a humid environment, this means your spears, axes, and hammers will break more easily, and bows might not even be possible to make.
5- Hide-glue & tree resin glue: Not only were these early adhesives the only kinds of glues available throughout most of history, but they were also important water proofing agents. If you can't boil hide or tree sap, you can't make glue; so, this means you can't make leak proofed water skins, you can't make composite bows and even adding wooden handles or shafts to stone tool heads becomes harder since the bindings were often hardened and secured with a layer of glue.
6- Fire-boring: Another common way to fix a stone head to a wooden handle involves using fire to "drill out" the hole you need. Without fire boring or glue, the only way you have left to attach stone to wood is by tying it in place which is not particularly reliable.
7- Leather, raw hides, and furs: Animal pelts that are not fully dried (usually by sun baking or smoking) will begin to rot within a few days.
The end result here is that most people would remain nomadic. Nomadic civilizations are inherently size limited because they can only feed people based on the natural densities of available food sources. This size constraint also means you will never have enough minds in one place to really advance very far. The few places you could farm well enough using only wooden tools would be impossible to fortify well without shapeable stone or brick walls. When you look at the late stone age, early towns that did not have strong walls were routinely overrun by nomads; so, without the ability to make these stone walls, any attempts at early sedentary civilizations would tend to fail.
In short, not only are you stuck in the stone age, but the early stone age at that.
**Now let's look at the lucky civilization that can start a fire**
In our own history, various estimates indicate that it took somewhere between ~300,000 and ~2 million years to get from the discovery of fire to cook and stay warm to the use of fire as the foundation for all these other important technologies. Some of that time may have been evolution happening requiring our brains to be capable of becoming creative enough to make these leaps forwards. However, with so few humans in your setting being able to make fire, not only is accidentally finding better uses for fire harder, but you also take away most of the environmental pressure that made human creativity so selectively fit in the first place. In our own history, the hominids who could find the most uses for fire pushed out the other races, but on your world, the faster, stronger, healthier hominids will win out nearly every time; so, even those few places with enough pressure to push intelligence forward will likely see so much diffusion into the dumber surrounding populations that they will never get very far.
The only way I can see to solve for this is to isolate a population. Perhaps there is a large island away from the tropical zone which is mostly dryer than the rest of the world and cut off from moister areas. In this case fire using humans could evolve separately from the fire-less ones. Then when they go to expand to the rest of the world, they could bring things with them like metal tools and tinder kits. By bringing tender kits, and metal tools, they could craft stoves that would isolate the fire from moisture, and the tender kits would allow them to start fires on damp wood. Once they have the fires going, they could then make more tender kits, more tools, more bricks, and all the other stuff that our own ancestors were able to spread to the rest of the world.
**One last thought**
Even all these ideas to make your setting works may all be in vain if your humans are clever enough to simply prepare dry storage areas for their wood. Using only stone tools, one can make an elevated covered structure that would allow wood to dry out enough to use, even in a place that rains all the time.
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***Look to tropical civilizations:*** I'm being fairly general here, sorry. I'm not an expert on technology in the tropics, but you would need a very hot climate to support this level of humidity, so I'm guessing the tech would be much like what you find in the tropics. Cold climates would cause moisture to precipitate out as rain or snow, so these would be included in your "dry" areas (although if you've ever tried to light a fire in a bog, it's not easy). I picture a world like the Mesozoic, where there were tropical swamps at the poles. Over geological time, the environment and life forms would become (i think) similar to an age of dinosaurs.
* Large predators would promote either evasion or weapon tech. Building high in the trees gets you above such creatures. Poison helps you kill them, but be careful, you're not cooking to denature the toxins. Be careful what you eat.
* Food production would look somewhat different. There's no cooking food to partially break it down, and no cooking to kill parasites. Fire significantly increases the amount of nutrition humans can gather from the foods they eat. Try eating a raw potato. At least in a tropical environment there should be plenty of fruits to gather.
* Obviously metallurgy wouldn't exist like anything we know today, so any metalworking would be with naturally occurring ones like gold. The Aztecs were able to do a surprising amount without heavy metal use, even making flint swords. Stone and wood would be your primary materials.
* Fire might paradoxically become even more important due to it's rarity. Designing conditions to make it work would be the stuff of religion. Temples could come to resemble foundries, and if the educated elites held the secrets of fire, they might apply the knowledge to advancing related technology. The products of fire (cooked meat, metals, etc.) could be seen as gifts of the gods. If control of these secrets became too tight, the science could be lost as the only people who know it die (as has happened with many advances in human history). This gets into the story-telling part and is largely a matter of your preferences.
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**In the long run — there would be no difference**
Fire is one of those things that give individuals and groups enormous power. Fire on your world may not be easy to come by naturally, but the first person to figure out how to harness it would (at least for a moment) rule the world.
And there are always sources of natural fire (despite not lasting very long). Lightning and volcanoes will always burn things. It's unlikely a world can legitimately have constant rain over every square inch, mountains will cause areas where fire is more likely than others. But even if we assume a constant rainy world (a worst-case assumption), fire will start under bushes, in crevasses, and at the early edges of volcanic flows (you must have vulcanism or you'll have trouble justifying your magnetosphere).
Which all means it might take longer for those cave men to figure out how to get fire going in a cave — but they will figure it out.
And once they do, you're back on track. so in the end, there's no difference.
*Questions asking what would happen if a fundamental technology or resource is missing are frequently closed for being too broad — and for good reason. Those fundamental technologies are really, really, really hard to "not have." There are many ways to make things burn without fire; chemical being chief among them. Which means there are ways to achieve every technology despite losing one fundamental technology. The only consequence it it takes a little longer to get to where we are.*
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**What technology?**
You will not have humans much less technology. Fire is what allowed humans to exist in the first place. The invention of cooking and the massive increase in calories it creates is what allowed our ancestors to develop the large brains humans have, use of fire predates the Homo Sapiens for a reason.
Ignoring the problem of creating conditions in which fire is rare but humans can still live, you probably can't, those conditions would prevent humans from evolving in the first place.
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I'm looking for a reason to explain why a species of fictional creatures resembling vaguely a shark has evolved this form of sexual dimorphism where one sex has an hammerhead and the other doesn't.
[](https://i.stack.imgur.com/DtwF9.jpg)
[](https://i.stack.imgur.com/euDG4.jpg)
Image source: pictures originally created by Explicital, the original one was the hammerhead with a different tail and a large penis. They were poorly edited on a phone to censure the penis and because I didn't like the tail.
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**Sexual dimorphism for the purpose of intraspecific combat or mate quality recognition**
Sexually dimorphic headgear is extremely, extremely common in the animal kingdom, ranging from insects to fishes to iguanas to [*Shringasaurus*](https://en.wikipedia.org/wiki/Shringasaurus) to proto-mammals to ungulates. Many species of ungulates, in particular, have very elaborate head ornaments in the males but much less noticeable or absent ones in females. Antlers or horns are the commonly thought of examples but many ungulates will have bony growths of some kind. Brontotheres, protoceratids, and giraffes have skin-covered bony growths known as ossicones, entelodonts have bony flanges on their skull, and warthogs and some oreodonts have well-developed bony "warts". In all of these cases the growths of males are much larger and more extreme looking than in the females. Indeed, in some cases (the protoceratid *Protoceras* or the modern okapi, for example) males have ossicones and females don't. Hercules or rhinoceros beetles are another good example. The males have extremely elaborate head shapes they use for intraspecific combat, whereas the females lack headgear.
In a lot of these cases this headgear evolves for the purposes of male-male combat. Headbutting, locking antlers, etc. In your case I would expect head-butting to be the primary driving factor, especially as real hammerheads use their [heads to pin down stingrays on the sea floor so they can eat them](https://www.jstor.org/stable/1446449). Whacking each other and trying to pin a rival male with your head isn't too different from what real animals do (headbutting between males is pretty common in a variety of species), and it would result in positive sexual selection on the hammerhead (males with biggest heads are more likely to reproduce).
The other thing this kind of sexual dimorphism does is it advertises mate quality, since a large hammerhead takes a lot of nutrients to grow and thus cannot be easily faked. This has two purposes: it frightens off smaller rivals who don't want to pick a fight with a male with a huge hammer (and thus kind of ties into the whole intraspecific combat thing), and it shows to females that the male is healthy enough to afford to grow a gigantic hammerhead. This is what you see with things like deer antlers.
The condition you show here actually occurs to some degree in the [stalk-eyed flies](https://en.wikipedia.org/wiki/Stalk-eyed_fly#Sexual_selection). Both genders have hammerheads, but the males have much longer and wider stalks. The length of the eyestalk is thought to advertise mate quality because they are such a handicap to survival, like peacock tail feathers.
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**Gender dimorphism to facilitate finding a mate.**
If you are looking for a mate, you can waste a lot of time and resources if it turns out what you thought was a mate was actually your same gender. It might be fun for all involved, but thinking now of producing offspring - easier to do with a different gender mate.
In the images I see that your two genders are, except for the head, extremely similar looking. I can imagine embarrassing mixups might happen all the time.
I could imagine that under circumstances where one gender is looking for another, a distinguishing characteristic might help. If these creatures are living in dark water and popping their heads up to look around for mates, head shape according to gender is the obvious choice. Flattening and stretching one head type and squishing out the other head type is a good way to make heads different from a distance and in low light, and individuals with gender more obvious from a distance turned out to have better genetic fitness.
I could imagine there might be males with a female head phenotype, which tricked the other males into competing over it much like [certain male garter snakes](https://pubmed.ncbi.nlm.nih.gov/4010782/) do. This female appearing male then an edge over the other exhausted males. The females are apparently OK with a male that looks like a female; so too your people.
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Well first, hammerhead sharks use their head shapes to find prey. The wide set eyes give them a wider scope of vision. They also use their heads to pin down prey like rays on the bottom of the ocean, and then eats them when they are pinned.
Sexual dimorphism naturally occurs through natural selection that helps the species to survive. So to make it work, your shark creatures will need a reason why the females have hammerhead-like heads, and why the males are better off without them.
Often times odd head shapes evolve due to a specific way of feeding, so perhaps your females eat a different prey than your males. Another idea to consider is sexual cannibalism in which a female animal eats its mate or feeds its body to young. Snakes do it because mating requires a lot of energy and nutrition that they can gain back from eating their mate, and spiders like the black widow do it because their dead husband makes for a handy meal to kick-start their babies' growth.
Another idea to consider is that the females may use their heads in display during the mating process, though for that you would need a justifiable reason for why the female with the most hammerhead-like head is the best survivor, so the head needs to serve a functional purpose.
If you want a better answer than I can give, I would suggest looking into why hammerhead sharks adapted to look the way they are, and the purpose of sexual dimorphism in other animals.
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I know that part of the Sulfur cycle requires elemental Sulfur to be oxidized. Every example I've found uses Oxygen and becomes some combination such as Sulfur Trioxide or Disulfur Trioxide. If other oxidizers exist such as Chlorine and Bromine, could there be a sulfur cycle that includes Sulfur Tribromide or Disulfur Trichloride instead? The question breaks down into three related elements:
1. At that point would there be no need for Oxygen?
2. Is the Sulfur Cycle possible on a world without Oxygen?
3. Is life possible in a world without Oxygen?
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>
> I know that part of the Sulfur cycle requires elemental Sulfur to be oxidized. Every example I've found uses Oxygen and becomes some combination such as Sulfur Trioxide or Disulfur Trioxide.
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The sulfur cycle on modern Earth involve elemental sulfur being oxidized, but that doesn't imply that elemental sulfur must at some be oxidized to participate in a biogeochemical cycle on some other world. If you delete sulfate from the diagrams on [Wikipedia](https://en.wikipedia.org/wiki/Sulfur_cycle), a lot of links go along with it... but not all of them. Furthermore, elemental oxygen is not necessary for the production of sulfate. Sulfate is a useful ion biologically, and it's not obvious that halogenated sulfur compounds would be suitable replacements (maybe they *would* be, but it is not obvious, at least). But if life forms require sulfate, they can get the oxygen for it from other precursors; consider, for example, that sugars contain oxygen, but those oxygen atoms generally come from CO2, not from elemental oxygen.
It is convenient to have sulfur available in gaseous form sometimes, but SO2 and SO are certainly not required for that--H2S serves just fine.
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> If other oxidizers exist such as Chlorine and Bromine, could there be a sulfur cycle that includes Sulfur Tribromide or Disulfur Trichloride instead? At that point would there be no need for Oxygen?
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Sure. Or sulfur hexachloride, or sulfur hexabromide.
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> Is the Sulfur Cycle possible on a world without Oxygen?
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*The* sulfur cycle, no. *A* sulfur cycle, yes. And while something very much *like* the modern terrestrial sulfur cycle is not possible without any oxygen at all, it is certainly possible without gaseous atmospheric oxygen.
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> Is life possible in a world without Oxygen?
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Again, you have to distinguish between oxygen atoms in general and free atmospheric oxygen. Oxygen is a sufficiently useful atom that I expect life is not possible entirely without it. But life is most certainly possible without free atmospheric oxygen. Plenty of life finds free oxygen to be horrendously poisonous.
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**You can have a sulfur cycle where elemental sulfur is the most oxidized form.**
<https://en.wikipedia.org/wiki/Sulfur-reducing_bacteria>
Elemental sulfur is oxidized as compared to hydrogen sulfide. There are bacteria that reduce elemental sulfur to hydrogen sulfide and oxidize foodstuffs using sulfur as the oxidant. Sulfur plays the role of oxygen here: instead of O2 you have S and instead of H2O you have H2S.
No need for any oxygen molecules to participate in the chemistry, although oxygen will be around as H2O.
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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.
[](https://i.stack.imgur.com/fH31n.jpg)
I did some research recently for a story on the physical feasibility of some aspects of living in the Saturn cloud deck, and wanted to share it. Please, however, if you have alternate approaches, add them.
Under what conditions would it be possible to live inside the cloud decks of Saturn, assuming money wasn't a problem (within reasonable limits - assuming a solar system economy with settlements on many of the rocky planets, ice moons; this may be being done as some ambitious hext- or heptillionairre's pet project)?
Here are some of the parameters:
* Atmospheric makeup : H2 primarily, trace amounts of He and other elements (including nitrogen-bearing ammonia, sulfur-bearing hydrogen sulfide and carbon-bearing methane)
* Gravity at 1 Earth atmosphere of pressure : 10.44 m/s/s (1.06 Gs)
* Rocky bottom : none, but likely incredibly turbulent core of liquid or plasma hydrogen.
* Mass : 5.68 x $10^{23}$ kg
* Equatorial radius at 1 Earth atmosphere : 60,268 km
* Escape velocity : 35,468 m/s
* Low-altitude orbital velocity : 25,079 m/s
[Answer]
## Saturn Cloud Deck Topography
Where is worth living in this vertical real-estate column? Here is some data on how temperature and pressure vary with altitude, and some interesting landmarks along the way.
[](https://i.stack.imgur.com/iYss0.png)
**Interesting Places :**
* 5 atmospheres (5 bar) : inside the ammonia and hydrogen sulfide cloud decks, so that something useful might be harvested. 5 atmospheres is roughly the pressure of being in 80 feet of water. This is a pressure at which people can work without specialized equipment. The temperature at this altitude is approximately 200 degrees Kelvin (-75 C), [which is slightly better than the coldest temperature recorded on Earth](https://en.wikipedia.org/wiki/Lowest_temperature_recorded_on_Earth). Nevertheless, thermal protection and protection from poisonous gasses (ammonia and hydrogen sulfide) is essential.
* 0.3 atmosphere (228 torr) : is above most of the cloud layer, yet still at a pressure where [people can work without specialized pressure gear](https://www.ncbi.nlm.nih.gov/pubmed/6863078). The temperature has only dropped 50 degrees to 150 K. Very cold, but poisonous ammonia and hydrogen sulfide aren't as much of a concern (although explosive hydrogen creeping into an oxygen environment is a concern at any altitude).
## Feasibility of Cloud Cities in Ammonia Cloud Deck
The big problem here is that the atmosphere is hydrogen - the lightest element known to man. There's no possibility of getting a big lifting differential in a methane atmosphere (like Venus) and putting hydrogen in our envelopes.
So, since the lifting power available is so low, is it even possible to have a cloud city?
The lifting power of a balloon is related to the density of the displaced air, and the density of the air filling that gap. We can't use lighter material, so we're constrained to hydrogen gas (0.002 kg per mole) on the outside and hydrogen gas (0.002 kg per mole) on the inside as well. We'll also need to assume a limit on how much the inside gas can be warmed. For this, I'll say the air inside the lifting envelope is 125 degrees Celsius (400 deg K)
We need to figure out the density of these two gasses to determine the lifting power of a heated air envelope.
The equation is $PV = \rho R T$
where: P is pressure (in Pa), V is volume (in $m^3$), $\rho$ is density (in $kg \over {m^3}$), R is a gas constant, and for hydrogen is equal to 4157, and finally T is temperature (in degrees Kelvin).
For hydrogen gas at 5 atmospheres (5 bar) of pressure,
* The density of unheated (200 K) air is 0.61 kg per cubic meter
* The density of heated (400 K) air is 0.30 kg per cubic meter
How big an envelope is required to lift a facility of 100 tons mass? It's an envelope of 327,645 cubic meters. That sounds like a lot, but in more comprehensible units, it's a sphere of 94 meters diameter (47 meters radius). That's actually pretty reasonable, I think, for lifting a 100,000 kilogram (100 ton) facility.
**Hazard Avoidance**
The chief reason blimps never became a viable platform on Earth is how easily they are destroyed by foul weather.
Saturn's winds get up to 1,800 kilometers per hour strong. For comparsion, Earth-borne hurricanes top out at 396 km/hr. Flying against the wind is, obviously, not an option. Cloud cities will need to follow the prevailing winds.
High-accuracy, high-precision predictive weather, out to at least 30 days would be essential so that these cloud homesteads could reposition away from problems and also avoid collisions with one-another, and any other atmospheric traffic. And enough lead time that, in the event of an unavoidable calamity, there's time to abandon the structures.
## How Feasible is Working in the Ammonia Cloud Deck?
[](https://i.stack.imgur.com/u7OF1.jpg)
[](https://i.stack.imgur.com/IUYpW.jpg)
**How do humans work when there is no bottom?** My thinking is that, assisted or unassisted, a technology like the wing suit is required to get around "on foot" as a supplement to travel in vehicles.
## How Feasible is a Wing Suit in the Ammonia Cloud Deck?
Rather than trying to compute all the mechanics, I thought it might be best to imagine a buoyancy assistance device, like the BCDs that divers wear, and imagine how big a BCD would need to be to lift a human in the worst-case situation of stalled or broken wing suit.
This is a balloon equation problem, again. For the sake of the human being wearing this thing, however, I'm lowering the temperature inside the envelope to 25 degrees Celsius (300 K). This is about the standard temperature of Earth's atmosphere.
With that in mind, 491 cubic meters of volume are required for an "emergency bubble up" of the buoyancy compensation device to carry a 100 kg mass human being. This is a sphere almost 11 meters in diameter (or around 40 feet). It's big, but as a safety device doesn't seem unbearable.
## What About Getting Out of the Gravity Well?
Saturn seems nice. But, we really want to be able to move people and goods in-and-out.
I think this is where urban centers at 228 Torr (0.3 atmosphere) come into play, being the vertical "central" location for a community living in the more useful 5 bar cloud decks.
Again, some sophisticated software that accurately can predict the weather is essential for these much higher-altitude service-centers to keep their customers inside their service footprint.
## Feasibility of Cloud Cities at Haze Layer?
A similar 47 meter radius (94 meter diameter) lifting envelope that can carry 100 tons down at the ammonia cloud deck only has about 10 tons of lifting capacity at the haze layer.
This might be fine. These facilities could have bigger footprints, or just manage their weight more aggressively, making sure to get goods off the platform quickly. Or both.
## Moving Goods
A lifting envelope of only 26 meters diameter is required to load 4 tons of goods for a computer-controlled ascent up to the haze layer for pickup.
A similar system could be used for delivering goods down the gravity well. The computer control system must be pretty good, but I think current technology is up to the challenge.
## But Really Getting Out of the Gravity Well
Unfortunately, the haze layer is not orbit. It's not even the top-end region of atmospheric flight. Which makes you wonder. Could we use atmospheric vehicles instead of vertical launch+land heavy lifters?
## Feasibility of Atmospheric Orbital Flights from the Haze Layer
**Where is the edge of space on Saturn, anyway?**
[](https://i.stack.imgur.com/WTJb8.png)
According to Cassini, it looks like once you've hit about 1,000 kilometers altitude from the 1 atmosphere "surface" of Saturn, you've left most of the atmosphere behind you. However, it also looks like conditions aren't so bad for orbit at even half that altitude (500 kilometers).
## What's the Feasibility of Atmospheric Flight to 500 Kilometers?
**What's the density of the air at 500km?**
Reading from the chart, the pressure is about $1 \over {100,000^{th}}$ an atmosphere (1 x $10^{-5}$ bars). The temperature is still about 100 degrees Kelvin. R is still 4157. Therefore, the density is 0.00000244 kg per cubic meter.
Atmospheric (winged) craft get their lift from speed. This is resisted by the density of the atmosphere. In this thin atmosphere, a jet-rocket can get up to high speeds. This has to be balanced against frictional heating, from going too fast.
The equation for frictional heating is ${T2 \over T1} = {1 \over 2} \rho v^2$
Where T2 is the heated air temperature, T1 is the ambient air temperature, $\rho$ is density, and v is the aircraft velocity.
Orbital velocity for a close orbit to Saturn is 25,079 meters per second. That's way too fast, and would burn up.
But what if the rocket-jet was able to execute a small entry burn to slow down to some smaller speed before hitting the air? How slow would it have to go to generate lift (because the same low density allowing high speeds is stealing away capacity to lift)? Maybe some near-future fusion engine with a very high specific impulse and decent thrust.
After a LOT of trial-and-error, at about 2,000 meters per second gets a $T2 \over T1$ of 4.81. With the outside air temperature being 100 degrees Kelvin, this would make the vehicle's temperature about 481 degrees Kelvin (206 degrees Celsius), which seems like it could be withstood without too much trouble.
How big of a wing would be required to lift a 10 ton load at this service ceiling? The equation here is $L = {1 \over 2} \rho v^2 {C\_L} A$
Where L is the lift force required (100,000 Newtons), $\rho$ is the atmospheric density, v is the velocity (2,000 meters per second) and $C\_L$ is the lift coefficient (using 0.7 for this exercise) and A is the lifting area.
Or maybe, do this another way? How much load can an arbitrary lifting area carry at this altitude?
[](https://i.stack.imgur.com/u4M3X.jpg)
Envisioning a near-future Stratolaunch (the largest wing span aircraft in existence) to be about 4 times the Stratolaunch's impressive 117 meter wingspan and 4 meter average chord length, it's still only possible to carry about 500 kilograms at this altitude, at this speed, in this atmospheric mix. Very disappointing, it probably can't carry it's own weight.
There are a lot of options you could play with, but vertical takeoff and landing heavy launch vehicles are probably how you would get most loads from the haze layer into orbit.
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In the near future, humanity has spread out across the Solar System. A new planet is discovered, let's say 30 light years away, that shows it to be Earth-like and could harbor Earth life without too much issues. A research expedition with a variety of specialists is put together to go check it out. The plan is to observe and scout from orbit for a year or so and then send specialists down on the planet.
Let's also say that we now have an experimental drive that lets us accelerate to 0.4 times the speed of light, so we can get to this planet in 75 years. In that time, the researchers will be in cryostasis. A group of trillionaires and government organizations have put a lot of money together top fund this endeavor.
So does it make sense that they'd maybe want to send some "regular" humans colonists along for the ride? Since there is such a big chance that the planet can harbor human life without terraforming or hardcore protection from the elements, wouldn't it be a good idea to send some civilians along, so that after the initial recon and research is done, they can start building a civilization on the planet?
Is this something that those who put the expedition together would consider?
[Answer]
They might well *consider* it, but the right decision would depend on details you have not specified.
* How long would the colonists have to survive on that planet before more colonists could be delivered?
* How much will it cost to transport those colonists and their necessary equipment, to the planet, and back again if it turns out to be unsuitable?
* What is the *purpose* of colonisation: profit, a backup home for humanity, or some other reason?
* How good is the available medical technology, and how realistic is your setting? It's possible, for example, that humans might have severe allergies to proteins from an independently evolved ecosystem, which might make colonisation impossible.
The answers to these questions are your prerogative as author. They don't have standard and correct answers for all situations.
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**Yes it would make sense to bring support engineers in the form of colonists.**
It all depends on how large your expedition force is and how long surveying will take but... Assuming the expedition is very expensive and the amount of travel time involved, surveying will probably take several years to decades. Seeing that a round trip takes 150 years you don't want to rush the research once you are there. With an expensive research project of at least several years, you want top-notch researchers but also a complete support staff. You will need everything from cleaners, cooks to maintenance technicians.
It is these people that can perform a double function. While starting the research project a lot will need to be set up and you will people doing this. After everything is set up, suddenly you need fewer people and the scientist can do their work with only some help. This gives the would-be colonists time to begin colonizing while also keeping their normal day job.
In this way bringing colonists/support staff helps the mission get off the ground faster and let scientist focus on their main task. Since the ultimate goal is colonization, kick-starting it with a select group will certainly be worth the cost. Possibly even a science project of its own, seeing how colonists deal with foreign nature. And if the worst case happens and it is not colonizable at all the colonist can come back with the scientist while still having fulfilled a necessary role.
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**Not exactly**
You have access to cryostasis, so that gets one of the major hurdles out of the way, but there's another issue - energy. It takes a lot of energy and resources to launch space expeditions, so if you're sending a survey team, you don't want any dead weight with the survey team, and every additional system is an additional chance that something goes wrong. Not to mention that you'll need to be able to take the researchers back in case something goes wrong, and that's a lot more fuel.
However, there's nothing stopping you from sending a 'just-in-case' mission a year after the expedition team leaves, such that they'll arrive exactly when the expedition finished, replete with it's own resources.
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I'll elaborate more on this answer later, but I'd say **yes, it does make sense to send colonists along for the ride.** You see, your interstellar starship is an expensive build, even for the highly automated space factories churning out habitat components from target asteroids.
So expensive is the R&D of the starship's propulsion and other works that the company that built the starship did so with partial private backing. A nearby habitable world is an enticing venture for the rich voyagers of the solar system, and the extra living quarters, supplies, CO2 scrubbers and environment-sustaining machinery, etc. needed to maintain these people will cost far less than the price of the tickets to board this craft, saving the company money in the end.
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# It Depends...
There are a TON of variables that would go into the decision to send colonists, most of which have little to do with the actual planet. If we assume in your future scenario that Mars has been colonized, people are already accustomed to living in enclosed environments shut off from their world. Compared to Mars, an alien but Earth-like world where you can't interact with the native life because it's incompatible might seem pretty pleasant. Assuming oxygen, liquid water, Earth-like temps, Earth gravity, and not-entirely incompatible life (no aggressive sentients, or hyper-acidic bacteria, name your poison) even an incompatible world is worth colonizing - compared to Mars.
That being said, You can look at the various biosphere projects and see what a pain it can be to live in an isolated environment. Compares to Earth, it would be a sucky, isolated existence with little hope of relief from home. Now you are sentencing your children to that - FOREVER. Here are a few of the variables I can think of.
* **Panspermia** - If you assume all life in the universe is related to some primordial starter matrix (unlikely) then the biology may be compatible, in principle. This ideal situation gives you the best options. But you wouldn't know this until you got there. Potential colonists would have to be prepared to live their future lives out either in a sealed base or space station if the planet isn't an option.
* **Terran environmental failure** - If the Earth looks like it may be Dying, there's a HUGE motivation to send colonists ANYWHERE. Even if they take up residence in an asteroid belt, you still want to scatter your seeds everwhere and see what sticks.
* **Pure science** - While you can't be sure of the life your colonists might lead, ideological scientists might decide the planet needs to be studied permanently. They would want a permanent human presence to continue their work.
* **No return trip** - If your ship is essentially a one-way voyage, and the fuel is gone when you arrive, your voyage becomes cheaper in monetary cost, but more expensive in human cost. By planning a colony (even an orbital one) you provide a future for the people sent. And after all, an ideal round trip mission would imply society will have changed radically in the (150-175?) years of your trip. Think back 150 years in history; what do you have in common with those people?
* **Proto-Earth** - If your planet is like Earth near the beginning of life on Earth, there's Centuries to millennia before the planet will look like Earth even with terraforming. Given the "short" distance of the voyage, you would be better off assessing the needs of Terraforming (which industrial devices, bacteria, etc.) and sending new ships with the appropriate equipment to start the work. Meanwhile, your colonists have to sit around for a century waiting for the arrival of the needed equipment. The other mentioned points still apply, and people may still want to colonize. Just don't plan on sipping margaritas on the beach in anyone's lifetime.
* **Staking claim** - If your trillionaires are taking the long view, then establishing a colony means they may come to own the whole planet. Other people may take a dim view of this, and there would be lots of opportunities for good drama. If they have the money to finance the whole thing, they can get away with this, but most governments aren't going to be good at THIS level of mass-giveaway without some accountability (like nationalist sentiment). Rival governments may plan followup missions with the intent of challenging the claims, or sending smaller but faster ships to get there first. Small fast ships may not be good for colonists, and slower, larger missions may be better at staking a legitimate claim to the planet. In this scenario, I'd bring some military hardware and military-trained colonists. I'd also send the family members of the trillionaires, because the descendants of the colonists may not turn over the keys when the second wave arrives...
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So, Armchair Chem is an evil corporation that has access to technology some consider unnaturally ahead of its time (the correct term is anachronistic, but whatever).
One such is the Replica Forces. A battalion of highly-trained and heavily-armed supersoldiers. What makes them really efficient is the fact that they form a hivemind, that converges at a commander, and where information, like enemy position/status, can propagate really fast.
This also gives commanders first-hand knowledge of the battlefield without putting them in danger.
Now, the hivemind can only work, if it can't be used against the replicas. If the hivemind can be tapped and manipulated, then the enemy would have all the replicas' knowledge, including the position of their commander, or worse, they could turn the replicas against their commander. If the connection can be jammed, then replicas would become mere paperweight, thanks to the emergency shutdown protocol than puts replicas into suspended animation when not receiving signals from the commander.
**How could this hivemind be made resistant to jamming and tapping at the level of individual connections without hindering the speed at which intel propagates?**
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So there are two issues here:
1. Cryptography
2. Jamming Resistance
Both are related to messaging between a recipient and a sender, likely between your commander and individual soldiers, but both are fundamentally different.
**Cryptography**
[Cryptography](https://en.wikipedia.org/wiki/Cryptography) is ensuring that information of messages are kept only to their intended recipients and senders, and cannot be 'tapped' or read by a 3rd party. The common solution is to employ a 'key' to decrypt an encoded message. This key at its simplest could be a symmetric key (ie a commonly understood technique to scramble and then descramble a message).
Or you could use a 'public key'. This in fact is the use of two keys - where every member of your group has its own individual encryption key, but there also exists a 'public key'. This technique was discovered in 1976 at the dawn of the internet, and is referred to as [Diffie-Hellman](https://en.wikipedia.org/wiki/Diffie%E2%80%93Hellman_key_exchange) protocol. By encrypting both keys it is possible for messages to be very secure.
There are other methods here to utilise and this is an ongoing field of study, especially with today's online environment.
**Anti-Jamming**
The issue with Jamming however, which is the corruption of a signal, is very different. The interference between two points needs to be considered in two ways:
* Elementary Jamming (ie. a non-targeted approach to interference)
* Advanced Jamming (intentional and nuanced jamming)
[This article and the diagram below](https://krazytech.com/technical-papers/jamming-and-anti-jamming-techniques) indicates only some of the many different types of jamming possible:
[](https://i.stack.imgur.com/On44B.png)
Furthermore jamming could be physically difficult to detect, ie it could be at the sender source, the receiver end or at some point in-between (or generally everywhere). This, and the complexity of different types, lends itself to multiple approaches being employed to prevent jamming, including:
* Hopping from one frequency to another
* Having multiple ways to communicate
* Keeping elements in proximity to ensure physical connection is possible
* Constant consistency checks and techniques to detect jamming
* Artificial intelligence to detect and overcome interference signals
It is worth noting that a 'hive mind' may not necessarily have a constant 'commander' - nor even much communication. [Decentralised command](https://campusrecmag.com/decentralized-command/) is a technique where individual elements are operating and given authority independently, but with a common goal. In such a way, messages could be cut off but mission objectives are still achievable.
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In addition to what was said above, what you need to do is create some kind of decentralized trustless system. Technology similar to a [blockchain](https://www.investopedia.com/terms/b/blockchain.asp) (a type of decentralized database used in a decentralized way so that no single person or group has control and is immutable so data is saved as a permanent record) would make it harder for a hacker to mess with the hivemind and the data members of the hivemind are sending to each other. Plus, even if the commander or the central authority is taken out, the system is still able to function if other nodes (ie. soldiers) are still operational.
On top of that, anti-jamming can also work by having multiple ways to send information with one another (radio similar to Bluetooth technology, satellites, [Li-Fi](https://en.wikipedia.org/wiki/Li-Fi) light transmission). That way, if one method gets jammed, the hivemind members still have other ways to speak with one another.
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There is a planet called Galileo with life on it. The life is getting extremely complex, in fact, with some of the life on Galileo beginning to form tribes and clans and learning language. Humans want to study this planet, themselves in person (No drones or robots) but they want to keep this planet in as pristine conditions possible. As little contamination as possible, if any at all. My question is, how can they go about this?
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When you talk about contamination, are you speaking about biological contamination, or cultural contamination?
As far as biological contamination goes, it should be fairly simple for any human society advanced enough for space travel, just make sure that any exits out to the planet's surface (through buildings or out of ships) are kept behind airlocks with decontamination showers built in, and make it compulsory for people heading out to wear hazmat gear. This is especially simple if the planet doesn't have an atmosphere that's breathable to humans, since airlocks and space suits (effectively hazmat suits) are already necessary. Additionally when it comes to the ships themselves, the cold vacuum of space followed by the intense heat of reentry really ought to be enough to keep the outside of the ship sterile. This probably goes without saying, but they'd also need to restrict any unauthorized ships from landing on the surface, because they might not be fitted with the proper gear, generally the fewer people and groups are there, the lower the likelihood of a containment breach.
In terms of cultural contamination, this is much harder, seeing as any kind of contact with an outside force would be enough to drastically change the way any civilization forms, especially if the members are already intelligent enough to form language and tribes. If the humans or their sci-fi technology are ever seen, expect them to be worshipped as gods. If humans wanted to avoid cultural contamination, but also wanted to see the aliens in person, they would have to take extreme precautions, making sure any permanent or semi-permanent encampment they made was remote and far away from any kind of alien settlement, additionally, they would need some kind of cloaking technology, and I wouldn't expect them to ever get much closer than a few kilometers away from any settlement, always watching from afar.
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## Very difficult if you were there, possible if you weren't
Contamination can occur in many ways. Through our biology, through interaction, and through detection.
**Through Fungal Spores and Bacteria**
Probably the best known and most obvious one is biological contamination, being transmission of bacteria and fungal spores. The unfortunate thing is, it is almost impossible to currently eradicate bacteria from our spaceships.
The Mars Exploration Rovers [are the 'cleanest' available probes we currently have](https://www.nasa.gov/missions/solarsystem/mer_clean.html), with NASA having 'strict' sterilisation requirements of 300,000 spores, or 300 spores / square metre. This of course is not zero, and it is almost impossible to reduce it to zero unless your spacecraft is created wholly in space using material not from Earth, and for there to be no landing in any Earth environment (our [atmosphere is saturated with fungal spores and bacteria](https://www.sciencedirect.com/science/article/pii/S0166111608700700)) during its operation.
There is [already speculation](https://en.wikipedia.org/wiki/Interplanetary_contamination) that our current probes to Mars, even with these requirements, would have already contaminated that planet such that detection of life there must be viewed first as life from Earth, eliminating this possibility first, rather than assuming it is indigenous.
Even the smallest exposure of just one of these spores would possibly contaminate your planet if the conditions are right. The single spore could float in their atmosphere, and multiply when it reaches ideal environments. This, of course, may be catastrophic to your alien planet. You can also forget about spacesuits or airlocks - fungal and bacteria spores will get through these areas easily.
**Through Interaction**
The biological contamination risk being too high, *it is unlikely any physical contact is possible without advanced planning from both sides*.
This means 'communication' must occur through technology that does not require physical interaction.
The common sci-fi trope of clashing cultures makes good viewing, but unfortunately is very unlikely. Forget about getting aliens pregnant, an Oak tree is a closer relative to us than the aliens, so it simply isn't possible. Cultural contamination assumes we are communicating, and now if remote it really requires a common protocol and language/grammatical structure. Both would need to work really hard at it to achieve even just talking.
**Detection**
Of course it may be possible simply to observe this culture in ways that we could remain undetected, and remote. This would be preferable. *Stealthy ultra-accurate [spy satellites](https://www.fastcompany.com/40510108/new-low-cost-spy-satellites-are-getting-scarily-powerful) come to mind*, perhaps even ones that could detect movement, sound, distance and material, such that a virtual VR World can be generated for us to walk around in.
*Any satellite transmissions need to be focussed to prevent detection*, as simply being detected could also 'contaminate' (imagine if we found one in our orbit, and the biggest questions in our universe are suddenly answered).
Once ready, and interaction is (for whatever reason) desirable, perhaps sending robots to the planet (that are made in space) would be best, being installed with AI that already knows how to communicate. Or they are controlled through VR by humans remotely.
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So, I decided to up the ante with dragons and make them much more destructive by giving the aqua regia as the breath weapon.
The problem is that the dragon in this story is a sweet and cheeky kid, who prefers avoiding physical conflict. Even when it comes to trading blows, he'd rather avoid damaging the surrounding environment when using his breath weapon, partly because he lives in it.
Just like the rest of his kin, the dragon is roughly the size of a shire horse and can store several (2-3) liters of aqua regia at most.
The problem is that while aqua regia quickly loses its gold-dissolving property, it remains a potent acid for a while. On top of that, it also creates chlorine gas as a byproduct. The dragon was never a fan of trench warfare, especially when its smell is localized in his favorite clearing.
**So, how could a dragon minimize collateral damage and avoid turning their beloved forest into the No Man's Land after fending off a pack of monster hunters with their breath weapon?**
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**Water and Sodium Bicarbonate**
According to the [Illinois Division of Research Safety](https://drs.illinois.edu/Page/SafetyLibrary/AquaRegia) and the [University of Massachusettes](https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=12&cad=rja&uact=8&ved=2ahUKEwiLqLitmqfnAhVDc98KHQNtAe8QFjALegQIARAB&url=https%3A%2F%2Fehs.umass.edu%2Fsites%2Fdefault%2Ffiles%2FAqua%2520regia%2520Handling%2520and%2520Disposal%2520Procedures%25202014%252003%252007.docx&usg=AOvVaw2xwxARBX3a9cFFi09T99co), the proper ways to deal with aqua regia involve water and sodium bicarbonate.
[Sodium bicarbonate](https://en.wikipedia.org/wiki/Sodium_bicarbonate), also known as baking soda, is a common acid neutralizer. Slow application of small amounts is best. Further, mixing water and sodium bicarbonate can be used to produce an aerosol that will [neutralize chlorine gas](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2908650/) and improve the condition of those subjected to it.
Your dragons already have the ability store aqua regia (HNO₃+3 HCl), which has all the components of water and most of the components of sodium bicarbonate. It shouldn't be too much of a leap, then, to envision your dragons living near bodies of salt water who store that salt water as a heat regulation system that can also be deployed to counter the effects of their breath. If their scales shed often and easily, and readily break down into the counteragents needed, then your dragon's lair will be naturally resistant to its breath weapon.
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"... is a sweet and cheeky kid, who prefers avoiding physical conflict...", sounds like your dragon is a "spit in your eye" kind of dragon with a very expert method of delivering his acid to exactly where he wants it to go.
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The dragon may keep his breath pre-stored in glass flasks, since aqua regia does not dissolve glass. If they have access to technology, they may deliver the acid by using glass syringes (with glass needles). If not, make glass arrows or spearheads and coat them with the acid. These [require a relatively low level of technology to craft](https://en.wikipedia.org/wiki/Glass_knife#History).
Or, you know, the dragon might do as humans do and pollute its enemies habitat only. A kinda of *Pax Armada*. *"You humans don't ♥♥♥♥ with my home, and I don't puke in your water supply and granaries."*
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Urine contains ammonia, which would neutralise acid. So your dragon could simply urinate on the affected areas...
Human urine isn't very concentrated, but perhaps the dragon's urine is more basic (alkaline) than a human's, as a by-product of concentrating acid for his breath?
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**Closed.** This question is [off-topic](/help/closed-questions). It is not currently accepting answers.
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This question does not appear to be about **worldbuilding**, within the scope defined in the [help center](https://worldbuilding.stackexchange.com/help).
Closed 3 years ago.
[Improve this question](/posts/166651/edit)
Recently, I’ve grown curious other universes and dimensions, and while looking around and reading about said things, I’ve come across the terms inter/ extra dimensions and universes.
This got me thinking even more and I stumbled upon the terms inter/ extra dimensional and universal **beings**, I tried searching more about said beings just for the fun of it, but I couldn’t find much.
So I’ve come here to ask about what makes a inter dimensional being different from a extra dimensional being, same goes with the universal beings.
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The prefix *inter* means something belongs to or transits between more than one area. For example, international means involving multiple nations (international flights, international soccer championships). Interstate roads are roads that pass through multiple states. Interdimensional then is a term for things or beings that transit through different dimensions, one which have origins involving more than one dimension (using the comic book definition of dimension, not the mathematical one).
An extradimensional being would be a being that exists outside dimensions. Many works of fiction involve spaces between the dimensions, rifts or voids where terrible things exist.
For example (beware of spoilers):
* In the Discworld, dragons inhabit an extradimensional space.
* In the trilogy of His Dark Materials, people travel through dimensions by cutting windows between them. This opens holes to the spaces between dimensions, which is where spectres come from. Therefore the spectres are extradimensional.
* In Final Fantasy 5, the world was split in two different dimensions by the power of the crystals. In between the worlds there is a void where the villain is, so that is an extradimensional space.
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**Different flavor of shmeerp, essentially.**
In sci-fi writing circles, there's a term called a 'shmeerp', and it's something to avoid. The saying goes - "If it looks like a rabbit, and acts like a rabbit, don't call it a shmeerp!" Basically, there's a tendency among new sci-fi (and fantasy!) authors to make up new and fancy names for whatever it is they've made *when it doesn't actually matter*.
And then, of course, there's an arms race among shmeerp users, because while vanilla shmeerps aren't interesting, sometimes if you make your shmeerp un-rabbit-like enough, it's actually interesting so writers keep upping the ante of shmeerp names. So first you have inter-dimensional beings, then *extra*-dimensional, and now there's the glorious *fifth* dimensional species. There are real definitions for these terms, but they aren't particularly meaningful (that is, they aren't specific in the slightest - it's like calling a human 'something which exists in the universe') but the colloquial usage in sci-fi doesn't follow them - it's just calling a rabbit a shmeerp.
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In the 2002 documentary [the future is wild](https://en.wikipedia.org/wiki/The_Future_Is_Wild), numerous biologists and other scientists speculated about the future evolution of various species.
In the '100 million years in the future' segment, the "swampus" was introduced.
Swampuses are the evolution of modern octopuses, who adapted to shallow ponds and now live in swamps.
Octopuses are well known to be able to exist [out of water](https://www.businessinsider.com/curled-horned-octopus-coming-ashore-wales-2017-10?r=DE&IR=T), so an adaption to only sometimes submerged enviroments does not seem too unrealistic to me. Swampuses have a thicker, letherlike skin, protecting them from drying out too quickly. They have also have the ability to breath air, similar to [lungfish](https://en.wikipedia.org/wiki/Lungfish).
Are the scenarios presented in the documentary realistic, and could partly land dwelling octopuses really develop in the next 100 million years? What nieche would they likely fill?
Btw: The documentary is available on [youtube](https://www.youtube.com/watch?v=Rbi8Jgx1CNE), the swampus can be seen at 39:20.
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Yes. An awful lot of evolution is possible in 100 million years.
Consider your question in the context of it being asked slightly differently by an intelligent alien visiting Earth 100 million years ago. At that time there existed a family of small, unintelligent, timid pre-rodents called multituberculata, the last common ancestor of mice and humans. Your visiting alien finds one and asks, "could these develop into intelligent spacefaring bipeds who dominate the planet in 100 million years?"
The answer is obviously "yes" because that's what happened. But if you took a parallel universe machine and re-ran the history of the Earth over and over again from that starting point 100 million years ago, is it likely that that's where evolution would have gone by the present? Probably not. It could be really unlikely that's where evolution would go over those 100 million years. But the anthropomorphic principle applies: we're in the universe where it did happen, so we're here observing that it did happen, so of course it doesn't seem very unlikely to us.
Evolution isn't a nice linear process where we can look at an octopus and say that's where it's heading in 1, 10, 100 million years. It's mainly driven by extinctions: whatever favours the diversification of octopuses probably simultaneously made a lot of the competitors for niches they might fill extinct. Allow a good mass extinction or two in your 100 million years and if octopus-descendants survive who knows how their descendants would adapt. If they adapt to breathing oxygen there's a fairly immediate fit into a sort of predatory amphibian niche living in swamps but over that length of time you could see fundamental changes with entire limb functions changing like the development of wings in early birds, changes in skin type and so on. Octopuses today are very likely more intelligent than the primitive euarchontoglieres that were the last common ancestor of mice and humans 100 million years ago, so in another 100 million years who's to say they wouldn't evolve into land-dwelling, air-breathing sapients capable of similar feats to modern humans?
A version of the anthropomorphic principle applies to evolution in your world building: even if it's a very low probability evolutionary path, if you want it to have happened then it did, because the world where it did is the one where you as the author choose to set your story.
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I would say it is unrealistic: they are too good pray and too bad hunters on a land.
Everything thay would eat is faster then they are (on a land) and thay do need some defencive mechanism (poision, camuflage) against more agile animals. We have species with this properties now - snakes.
So octpuses would occupy snake niche, but here comes anothe trouble. Mollusc can protect themselfs from air (even from dry hot air), but they cannot protect themselfs against direct sunlight. They have no means to cool down and just cook alife in a minutes (I keep giant african snails at home - that is a problem).
So to be plausable this conditions should be met:
* wast cloudy, foggy but still warm region, preferably inside some crater at middle or high lattitudes or some cave system. There should be some places (even small ones) where sun never shine.
* no snakes (they would not give up their niche for some "khtulhu" invaders)
* octopuses should be highly toxic (like blue-ringed octopus) and continue to be ambush hunters
* shallow periodicaly driyng swamps/lakes or bays with *long* tide region (current record is about 20km)
And things should keep that way for hundreds of millions of years. It is very unlikely to happen, but still can.
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Set in the modern day, only a small portion of the population is aware of magic and some of them has unlocked their innate magic potential at a young age. There is a governing body that ensure fair usage and treatment of magic and a law enforcement unit to prosecute those who abuse magic, enough said there is only 1 magic currency system in this world and it is cap at a specific amount so that the combined currency is alway constant. The form of magic currency itself is ethereal, intangible, nign indestructible and can only be materialised by synchronisation of 2 or more willing parties so theft and robbery are rare. If a certain individual who is believed to show an affinity to magic will see the council elders to unlock their innate ability to command magic as well as opening a magic currency account during the session, the individual can then transact magic currency with others. Despite there are some gifted who can topple mountains and overturn the sea, why are they still limited by this currency cap?
E.g. A person opens a magic account with zero balance so everyone involves in the synchronisation can see each other body glowing in different colours but the outside observer would see a rich purple pulsating at very high frequency which tally with their combined net worth. To the elder the person is emitting a faint red glow indicating no balance in magic account.
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**Inflation**
How this currency cap is enforced is going to be a problem, though I suspect rigorous use of guidelines and trace magic would be helpful. But the reason to keep the production of magical money at a flat rate of zero and prevent any from being introduced is a very simple one - inflation. Allowing anyone to print fiat currency is a one-way trip to currency devaluation to the point where if rampant magical currency creation occurred, it would be completely derail the magical economy to a standstill and wizards would be unable to render services because you can't pay them. Wizards don't like not getting paid.
In addition, they printing new money at a constant rate would also marginally increase inflation, and the wizards didn't necessarily agree on how much new money should be made and who got to be in charge, because remember, the people in charge of making money possess an inordinate amount of power. So, honestly, the safest thing to do is declare all the money currently in the system 'legal' and then band together to stop any new money from coming into the system so the system could work.
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## The Currency is Time
Either literally or figuratively, the currency is time itself.
**Figuratively**
In this situation, the mages are exchanging favors. Basically, each unit of currency as an IOU, stating that it would be worth 1 hour of work at a later point in time. This IOU could be traded to others, who could come in to redeem it. The value of the currency would depend on the power of the one who coined it.
People would usually like to trade other's coins, rather than generate new ones, as even the most powerful arch-mage wouldn't want to spend every waking hour dealing with other people's problems. They would instead elect to pay for things with the coins of their apprentices, (who are probably paying with the coins of their own apprentices).
This would also create an interesting speculative market where people traded coins, based on if they thought a mage would become more powerful, would die soon, or if they thought the person wouldn't be able or willing to honor all the time commitments they traded favors for.
**Literally**
There are a few ways to do this, simplest is to have them trading the memories of the Earth, which gives a finite amount of currency which relatively speaking will not increase.
For a more crypto-currency type of scenario, the mages are trading the ethereal manifestations of the past. In 1 day, each mage would generate 1 day of past. The most powerful arch-mage or newest apprentice would generate this at the same rate, but with thousands of years of magic users, the total contributions from newly generated currency would be only a slight increase to the overall supply of past generated by long dead mages.
This gives you an intrinsically valueless resource, being slowly increased by all living mages, preventing inflation.
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**Time and labor is still limited**
Sure you can topple a mountain in a second, but making a magical frog the croak a unique poem based on your name and birthday before jumping into your mouth takes much longer, and is a specialized skill that most people don't have outside of the Anura chocolatier guild. So to make sure that people can still make things and get paid you have magic money. The money doesn't have real value, similar to a fiat currency, but it has value based off of what you can buy with it on the market. This can lead to John Wick like situations where the currency has vastly different exchange rates at times, but people will eventually agree on prices so long as the amount of money in the system is stable.
If there is no limit to the amount of money a person is willing to spend on items in the market, then there is no amount of money that it is worth selling items in the market for.Any amount of money would not guarantee that the seller could buy equivalent goods in the market, so it is better to hold on to the items of value or labor, than to sell them and get less back.
This money system has artificial scarcity to ensure that markets still work.
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Modern currency appears to be quite magical themselfs. Everyone accepts it and gives you basicly anything for enought of it. It hasn't been this way and it might change in the future. In theorie money is either a representative of e.g. gold or the promise of future work. This of course only work if enought people belive in the currency or the entity that backs it up.
An easy way to make your magic currency limited is linking it to an entity that is interested in the fact that the currency is limited. The easiest way is giving all magic some kind of signature unique to the caster. This way anyone can cast the Mcoin spell but only a small ammount of trusted mages issue Mcoins that are generally accepted. Again, everyone can "print" their own money but most people won't take just anyone's money since there is nothing to back it up. This way, there can be different currencies with different scopes backed up by individuals or groups of mages if the magical world is decentralised and one trusted magical bank that issues all money if your magic world is highly centralised. So basicly every mage can issue Mcoins but only the Mcoins that are issued by a (or the one) trusted authority are likely to be accepted.
But the real question is why anyone should take these coins for their labor or posession. Maybe there are mages that are known to rarely issue Mcoins that represent special favors they owe the owner. In this case, people would only value the Mcoins because they can exchange them for the work or knowledge of the mage that issued them and if you don't need the kind of magic this particular issuer practices, the Mcoin does not mean too much for you. This might also be the case for entire associations of mages with a larger scope and likely a more narrowly defined value of one Mcoin. On the other hand there might be an association of mages that promise to exchange physical currency for their Mcoins and vice versa. That would be your magic equivalent of a traditional bank that backs up the currency and there would be a pretty stable and concrete value.
There will be some instability at the start but after some decades, there will be a small set of accepted Mcoin-issuers. Their Mcoins have mostly stable values and are genrally accepted within their scope.
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The currency is actually the favor or attention of a magical entity. It can only remember or focus on so many things at once so there is a hard limit on the amount. The entity is from another plane of existence much different than ours and creating or finding more is impossible, it has been tried for eons with no success.
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**The Method of Currency Creation is lost**
The initial creation of the currency was made by the combined lost knowledge of the Magic Users of the ancient times. The unique and complex magical signature that comes off from the currency is not able to be replicated by today's means. No more can be created and it is impossible to fully replicate the complex signature.
**What does this mean for our new mage?**
It is time to become an apprentice. Learn the trade of the mage AND get paid for it. The mage gets some magical grunt work taken care of. The new mage starts amassing spending money. No different than not having money in the real world.
**What about Mages hoarding currency?**
Mages are in constant need of helpers, supplies, and other necessities. As they spend, so too shall others get spending money.
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The currency is limited simply because it, however ethereal, is still a finite resource not unlike everything else in the material world.
A magic user can only access so much of it before there is none left unpossessed, or more must be created.
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# Magical technology
Magical currency is a cryptocurrency. In another question I proposed a form of magic cryptocurrency called [Manacoin](https://worldbuilding.stackexchange.com/a/112321/21222), so all the fleshy details are there.
I based that on a very notorious cryptocurrency of real life, which as a feature has a limited amount of currency that cannot be increased. Inflation is controlled because new amounts are added to the ecossystem slowly via mining. The currency also supports enough decimal places that it might be useful for decades to come.
If magical currency is a cryptocurrency, then it may have a limited total amount built in as a feature too.
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Can a planet with a dense atmosphere composed mainly of sulfur dioxide have a blue sky like Earth's due to Rayleigh scattering? Or would the composition change the color of the sky? I mean, it's well known that methane is responsible for the bluish colors of the atmospheres of the icy giants of the solar system, Uranus and Neptune, so it's logical to think that a planet with a significant amount of methane in its atmosphere would have a blue-green sky, would the same thing happen in a planet with a dense atmosphere of sulfur dioxide?
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[](https://i.stack.imgur.com/HgOwr.png)
Rayleigh Scattering is a universal physical process so it will always be involved when light passes through gases. Which is not to say it will always be the dominant determinant of the color of the sky. But in the case of an atmosphere composed of $SO\_2$ that is doesn’t significantly absorb wavelengths shorter than 600 nm, Rayleigh scattering will dominate the color of the sky.
But the efficiency of scattering is proportional to the polarizability of the molecule. $N\_2$ and $O\_2$ have similar values ~1.6-1.7. $SO\_2$ is 3.8
This means that longer wavelengths like green and will scatter more efficiently in your atmosphere than they do in Earth’s atmosphere.
I expect that your sky will be green near the star and then blue green then blues then to violets as you look to the horizon.
Table of Polarization Values for some gases.
<https://cccbdb.nist.gov/pollistx.asp#1977Mil/Bed:1>
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So, at its core, magic is using a swarm of tiny (50-100 micrometers), naturally occuring robots to deliver substances to a given location and initiate chemical reactions that lead towards the desired result. It involves physics, chemistry, **programing and communication**.
So, how to prevent sieges from lasting until someone pulls out their fat man and obliterates the gatehouse, or the dragonborn from slaughtering 95% percent of the population with a magic sword?
Magic-denying fields that selectively nullify magic around a point of origin, of course. I think using the programing and communication aspects is the best for magic denial, as far as efficiency and universality is concerned.
However, micro machines receive their orders before they're fired and communicate between each other by holding hands (individual bots are spheres with several retractable arms with a gripper/hand at their end). A mage usually generates their own bots that recruit ambient ones, though one can rely solely on their own bots for a spell, if they're patient or strong enough.
Say, you summon me in the middle of the city, because you want to make a contract with me and become a magical girl. It's possible to fake the commands you direct at me after summoning, but if you summon me with the intention of walking up to the local jarl and banning him from life, that command is retained in the spell, that should be impenetrable to jamming attempts, thus no one on Earth could "talk me down" from slapping that jarl to death...
that is a problem!
Ideally, the communication of individual bots should be jammed, before they could form into my deadly, jarl-slapping avatar.
**So, how could communication between individual bots be jammed? Note that the barrier isn't visible and doesn't have side-effects.**
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Overriding or conflicting commands being sent by other nanobots, or through coded light or electromagnetic signals.
The nanobots would naturally have some sort of "reset" switch or "master" command, or they couldn't be recruited into a new spell. Some sort of command telling them that the deed is done. Given the size and power levels of a single bot, they're unlikely to be equipped with very strong crypto to defend against hijacking.
So, they float through a barrier that flashes them all with the nanobot equivalent of "Ctrl-Alt-Del".
But this is probably too much, because while doable, it would be ruinously expensive - think of all the low-level spells that should *not* be affected by the barrier, on pains of having to recast them all over again.
Probably, then, the "barrier" would need to disrupt specific spells. It would need to be a more complex meta-spell in its own right, whose nanobots would first interface with the incoming spell, then "recognize" its purpose, allegiance or permission level, and finally if not satisfied they would try and unravel it, or if the worse came to worst, trigger a local-area total spell reset.
This would give rise to a arms race between attacking spellmasters and defense spellmasters, the latter trying to devise faster and more cunning "antivirus" or "firewall" spells, the former trying to camouflage their spells or subvert the magewalls.
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Your nanobot thingamajics are basically a mechanical biological system akin to that of your body except it covers the world. It can converge and share energy, materials and information in order to cast magic. This also helps in keeping the swarm active and functioning.
The body doesnt want everything to be active at once, or wants to prevent certain actions from happening sometimes. To prevent this the body has ways to deactivate certain processes through various feedback loops. And this can be used for your nanobots.
Whoever designed it must have known that allowing all actions all the time is a bad thing, so sending it commands to specifically not do something like eat through the walls housing the fusion generator or the volatile chemical plant would be installed that cannot easily be overridden.
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In the anime, called *Attack on Titan*, the primary antagonists are these huge, humanoid creatures, called titans.
Titans have sizes between 15 and 4 meters. Larger titans aren't unknown, but they splatter, more precisely, they nuke when hitting the ground.
The reason why smaller titans don't nuke the place when falling from 50 meters high, nor sink into the ground, is explained with an all-around low density. So, the tissues of a titan have low density.
Hange Zoë, for instance, kicks one's head around like a football in Ilse's journal (OVA), though [she did the same with a heavy table](https://youtu.be/e4b6eo1nd7E), so keep that in mind.
[](https://i.stack.imgur.com/2u6Ry.png)
Now, all the weird \* beep \* aside that happens later in the show, **is it actually possible for a creature's various tissues to have very low densities (I see the most problem with muscle tissues and tendons) without impairing their function?**
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For water based life, average tissue density will be always around that of water, which is normal considering that water is from 70% to 90% of the total mass.
The only way to lower the density is to embed a lot of air, like it happens for lungs, which is not feasible for all the organs.
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I couldn't find much on this. [A question in biology.se](https://biology.stackexchange.com/questions/20072/mammal-body-density) focuses on mammals and concludes that there isn't much variation.
As [L.Dutch said](https://worldbuilding.stackexchange.com/a/164035/21222) for water based life, the only way to get less dense is to have air filled cavities. In that sense the least dense animals could potentially be insects (due to how their respiratory systems work) or, surprisingly, spiny pufferfish that inflate in air - I've seen it, they aren't able to sink until they deflate, but making them inflate in air is animal cruelty.
I'm trying to picture, in my mind, a titan-head-sized pufferfish inflated in air. Due to the law of square cubes, it would probably be too heavy to move like in the OP drawing. Notice that Attack on Titan follows the law of [Rule of Cool](https://tvtropes.org/pmwiki/pmwiki.php/Main/RuleOfCool), and does not adhere to realistic physics at all. In fact, according to such law:
>
> Of scientific laws that this trope circumvents, the third law of motion is probably the most frequently revoked, with the Square-Cube Law probably a close second.
>
>
>
In a question of my own, I learned that [the way the characters move](https://worldbuilding.stackexchange.com/q/127303/21222) would pulverize their bones fron inside out.
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If you are willing to accept life not-as-we-know-it-Jim, *very* low.
It is plausible-enough-for-sci-fi that alien organisms could be based on [cells filled with air](https://www.daviddarling.info/encyclopedia/B/bubble_life.html) rather than water, with the bulk of biochemistry remaining fundamentally similar to ours. Many enzymes, after all, only require a single layer of water molecules surrounding them to function, and could maintain that in a high-humidity gaseous intracellular environment while remaining attached to the outer cell membrane, or extended membrane structures inside the cell, like an endoplasmic reticulum. The major differences would be in macromolecular transport; only highly volatile molecules could transit the bulk of the cell, while stuff that would normally be dissolved in the bulk fluid of the cell's cytoplasm would be restricted to 2-dimensional diffusion along moist membrane surfaces.
A macroscale multicellular creature made out of those sorts of cells would have a bulk tissue density somewhere in between air and water, but plausibly closer to air than to water--and thus much less dense than our sort of water-filled flesh.
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**Carbon fiber prosthetics are much less dense than muscle.**
[](https://i.stack.imgur.com/p8PgD.png)
>
> The specific strength of the aforementioned carbon / epoxy composite
> is so high that it is possible to produce a prosthesis that has the
> same strength as a natural leg, but is 60% lighter at the same time.
> The first carbon fiber prosthetics produced were indeed very light.
> Thanks to this new material, a total leg prosthesis could weigh as few
> as 2 to 3 kilos. The leg of a man weighing 80 kilo, however, weighs
> around 13 to 14 kilos.
>
>
>
<https://www.reinforcer.com/en/category/detail/Carbon-Fiber-Epoxy-Composites-Ideal-Materials-for-Orthopedic-Prosthetics-/46/235/0>
Muscle is mostly water. A prosthetic limb fulfilling the same role as muscle and bone and occupying the same volume as a native limb can be 85% less dense. Prosthetic limbs are not biologic tissues but are used in the same role as an amputee's biologic tissues and specifically muscle and tendon. Modern prosthesis can be made very lifelike and fool a casual observer. It is not outlandish to posit a creature with a body largely composed of very lightweight synthetic materials. The titans would be something like articulated parade floats.
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This is related to [How would a race of humanoids with tails design [vehicle] seats?](https://worldbuilding.stackexchange.com/questions/158200); same universe, same humanoids.
I have a story involving a bunch of humanoids with tails (see prior question for specifics), with one scene where the POV character sees an "accessible" bathroom for the first time and is puzzled by the funny toilet. *What does it look like?*
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For context, we first need to ask, what do *ordinary* toilets look like? It seems obvious to me that they ought to look like, well, [these](https://en.wikipedia.org/wiki/Squat_toilet). Aside from the arguments that *humans* ought to be using these (modern westerners, specifically, as these are what historic people used, and many easterners still use), it seems that they wouldn't have the problems a modern western style toilet would have with tails.
The problem (and the reason why my POV character is surprised) with these is that they obviously won't work for some disabled people (those who are wheelchair-bound, especially, but even someone on crutches would have trouble), so there must be something different for such people. What is it?
Our goal is to design a toilet such that:
* It can be used by someone who has no use of their legs, preferably without needing complicated hoists.
* The user's tail (which needs to be able to hang limp; the user may not be able to move it either) is not in the way, or crushed, or...
* The user's waste doesn't get splashed all over, and particularly doesn't wind up on his/her tail.
* The user does not have to make contact with a surface which also makes contact with users' wastes.
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So far the best I've come up with is something like a huge pit with enough of a drop that the back of the seat can be open (to accommodate the tail) without this introducing a splash danger. However, while this might work for "pit toilets", the space requirements make it decidedly sub-optimal for e.g. a shopping center. Something that can fit on a second floor without disrupting the space below is strongly preferred.
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Edit: I'd sort of prefer a non-magical solution, but on further consideration, I *do* have "kinetic" magic and if there is a brilliant magic-based solution, it would be bad world-building to ignore it. See [How can I meaningfully define the energy cost of magical levitation?](https://worldbuilding.stackexchange.com/questions/160846) for an outline of the mechanics. Again, I think requiring magic to completely support the user's weight is sub-optimal, but magic could easily be used e.g. to hold the tail out of the way. (The tail still needs somewhere to *go*, however.)
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Honestly, having the squat toilet you described with moving bars on the side might be the way to go if your character is paralyzed only from the waist down. I hope I'm not describing this badly, but think about it like an adjustable bar - it is at first positioned at approximately a wheelchair user's height, and allows the user to relocate their weight onto their arms as their arms are holding this bar. But as the user stands and then 'squats' slowly, they relocate their body weight onto the bar, pushing the bar lower till the user is at a proper height, similar to squatting. This would arguably use less upper-body strength than bars on the sides on public disabled restrooms require. This would solve/minimize the usability + splash-back problem that the user could have.
Another thing to note as you correctly pointed out is the tail. For this the simplest 'fix' is to have a small tail-holder to make sure the tail is out of the way. In your previous post you already mentioned how long these tails are so that should give you information about where they should be placed and how high this holder should be. I would consider also having 'straps' to hold the tail in place, but this could be a sanitary issue and vector for disease.
Below are three diagrams - the overall look of this toilet from above, the diagram of how the bars sort of work, and of the tail holder. Hope this helps!
[](https://i.stack.imgur.com/yJEn4.png)
[](https://i.stack.imgur.com/VnDur.png)
[](https://i.stack.imgur.com/gthXe.png)
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First off, thank you cyber101 for a really neat and inspiring answer.
Here's what I think I'm going to use, inspired by [this video](https://www.youtube.com/watch?v=hxe-xxN0wi0) and cyber101 reminding me to think about the transfer bars. This is going to be on the overly-detailed side.
There are actually several relevant questions here:
## Q. How do we deal with the user's clothes?
I realized after asking the question that this is also a problem. For my needs, it probably won't matter, but it's important context that should be considered.
For humans, the consensus on the web seems to be "take them off first". For our people with tails, doing this while seated has the potential to be extremely awkward. For "healthy" people, I'm assuming that dressing is done standing up, such that dealing with the tail is rather like dealing with a third leg... not too bad. For someone sitting, this would only work if the tail is pulled between the legs, *or* if the clothes do not permanently wrap "over" the tail. We'll assume that our handicapped individuals either *do* sit on their tails (plausible) or else wear clothes that fasten above the tail, such that they can be removed without having to thread the tail through any holes. We'll also assume that they take their clothes (below the waist, anyway) *completely off* before getting on the toilet so that the legs are unrestricted. (This might imply that accessible restrooms will tend to have somewhere to set clothing aside.)
## Q. how does the user *get on* the toilet?
Here is where the aforementioned video really inspired me. Combining that idea with cyber101's reminder to stick close to the design of regular toilets is how I arrived at the final design.
Okay, so the user's pants and underwear are off. The user moves his/her wheelchair so that it is directly behind the toilet and locks the wheels. The user scooches forward and spreads their legs to help guide his/her knees around the "seat". Then, using a combination of the wheelchair and the grab bars, the user slides himself/herself forward onto the toilet. The rails (lower parts of the grab bars) help guide the user's legs onto the lower supports. In addition to the side grab bars, a front grab bar is available to assist in this process.
The user may lean forward to assist in positioning of the colon for improved evacuation.
## Q. So... what does this thing actually look like?
From the top, it looks a lot like a regular toilet. There is a similar splash guard, a gourd-shaped opening (wider at the back to maximize access to the user's bum, narrower in the middle for maximum leg support) and what looks a bit like feet supports. However, the support is actually based on a kneeling chair. The whole thing rises to chair height with a water basin. The back, however, has a dip for improved access.
Here is a picture with side, top and back views:
[](https://i.stack.imgur.com/lGHfr.png)
The front grab bar is shown only in the top view. The user's head/arms/feet are not shown. The tail is probably too short also, but only the base of the tail really matters, and tail lengths vary. Darker colors generally indicate greater distance from the camera plane. This isn't perfect, but should be good enough to get the idea across.
## Q. How does the user clean themselves?
Here is where we see some of the *why* of this design. The open back is inspired by human toilets and is specifically designed to provide an opening so that the user can reach behind and wipe his/her bottom. Additionally, because the user's legs are spread and not pressed against the front splash guard, there should also be room for the user to wipe his/her crotch.
## Q. What about the tail?
As shown, the tail *should* rest against the outside of the toilet and be more or less out of the way. However, my thinking is that either the user's tail will be partly supported by the wheelchair (which, recall, is directly behind the toilet), or else the user may elect to place his/her tail over the top of a leg. The latter is probably "optimal", and users can use their non-dominant hand to hold their tails.
## Q. Can this be refined?
Probably. I feel like there needs to be some tweaking to help users get their legs up and onto the "seat", but I can hand-wave that in narrative. This is close enough for my needs.
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I had an idea for a character that was stuck in a ghost-like state for a length of time after an accident. During this time, they would have very limited ability to interact with the rest of the world: no one could see or hear them, but they could observe everything happening around them.
They would occasionally be able to interact slightly with the physical world around them, but it would consume so much energy that they would need to rest and recover for an extended time before they could again interact in such a way. Even then, their ability to affect the world in a controlled manner would be limited. They may be able to knock a glass off a table but not write anything legible with a pencil, for example. They would also be limited in how far they could travel away from their starting location before they would be drawn back. However, since that location was in the middle of a college university, there will always be quite a bit to see, with different types of activities all in a fairly close area for them to observe. They will not suffer from hunger, thirst, aging, etc, during this period of time.
I'm wondering what would happen to a human psychologically if stuck in this state for a length of time. I know that a very brief length of time in solitary confinement can cause quickly drive a person insane. How different would it be if one could witness human interaction but not be a part of it? I assume being able to witness human interaction would lower the psychological harm caused by one's isolation to an extent, but how long can someone go without the ability to interact with others before they have reached a point where they would struggle to function in the mundane world even after they are brought back to a normal state?
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This is the effects of being *ignored*, *unseen*, and *unheard*. Psychologically speaking everyone has deep needs to be seen, heard, and validated. A person stuck in your proposed state is effectively discarded from any opportunity of this. Even a momentary interaction would not meet these deep emotional needs. Children who lack positive attention at young ages are significantly more likely to show difficulties re-integrating with society. Fortunately, your character has a history of participating in the real world so it is *possible* for re-integration to occur, but be warned: it's a VERY long and difficult road.
In more detail, the neural pathways take about three to seven weeks to take hold, and about three to six months to "cement" or form (ie to create a habit). The converse is also true - after about six months of being ignored your brain has entered a state of being "adapted" to no longer living with human contact and attention. To learn more about how this process works I recommend reading [The Mind and the Brain: Neuroplasticity and the Power of Mental Force](https://rads.stackoverflow.com/amzn/click/com/0060988479) *(NB: you can safely ignore some of the grandiose claims made by the author - Dr Jeffrey Schwartz - especially about proof of "the mind"; the book does a great job explaining the science and studies behind neural pathways and changes in brain chemistry, even if you disagree with his conclusions)*.
As your character goes reaches into the six month without any human attention or feedback, they will begin to show signs of isolation, lack of concern for the well-being of others (no longer being shocked or disturbed by violence, for example), and a general sense of emotional "numbness" and indifference. Emotions work a bit like a pipe - it's either on or off. You can't just shut off bad emotions (nor good emotions), when emotions shut down they *all* shut down.
When this happens, serotonin and dopamine levels in the brain restructure to place the character into their new perceived "role" in society - either at the top or the bottom of it. They would either develop a grandiose god complex, or become deeply depressed with a continual sense of being a shit-stain on the earth.
What would follow in the months and years afterwards would move from a sense of *isolation and numbness* to full on *detachment* and *dissociation*. Basically, your character would "drift away" from identifying as human, and turn into "an other" - a beast of some kind, a god figure of some kind, or a deranged rambling maniac.
Studies around this are nonexistent, as there is no pool of people who become adults and then disappear *entirely* from society without *any* interaction at all, especially not for years on end. Such studies would be unethical. But in the USA, if you've been imprisoned for 20 years or more, you qualify for some types of disability benefits because the government believes you're so dissociated from society that you'll never be able to re-integrate (or that doing so is too impractically burdensome). The point being if your character stays in this place for 20 years or more, their brain is likely mush and reintegration would be difficult if not impossible.
However, coming into this ghost-like state after maturity (approx. age 25) and returning to a life-state within 20 years, reintegration is *difficult but not impossible*. This would be akin to someone with severe brain trauma and amnesia after an accident learning to walk, talk, read, and write again. They would be able to remember these things, but it would seem "like another life" to them. They would have to learn social interactions again from scratch. From simple introductions, to making eye contact, to smiling and showing concern for others. As a general rule, I would expect every month in the ghost-like state (after the six month) to take 2-3 months for integration. Some could do so faster, some longer, but in general if your character was stuck for a year I would anticipate 2-3 years re-integration time on average.
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I imagine your character would become incredibly frustrated, if not go insane outright. I would try to imagine how you would feel if you were unable to speak and had your hands tied behind your back. Sure, you don't have the discomfort of being *actually* bound, or the frustrations of having to get other people to look after your needs (food, etc.), but still, you can't talk to anyone, can't manipulate your environment in any way...
There's a reason some cultures practice shunning as a form of punishment, or why in general ostracization is usually seen as "bad".
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Back home, Amphicyonidae (bear-dogs) predated Ursidae by only four million years. While the latter still lives in the form of eight species, the former had been extinct for two-and-a-half million years, which made me suspect that the ice ages were what drove the bear-dogs into extinction.
But in an alternate Earth, Ursidae never existed, and Amphicyonidae instead occupied that niche. In order to understand the bear niche, we need to recognize these key factors among bears:
1. Large, dexterous paws that can articulate to the extent of climbing and swiping, more like cats than dogs
2. A large brain necessary to learn new things (like the blacks, browns and polars becoming more and more accustomed to urban life)
3. Omnivory (Blacks and browns, for example, are hypocarnivorous, meaning that meat makes up a maximum of 30% of their caloric intakes)
In an alternate Earth with no ursids, would some species of amphicyonids evolve to look and behave more like them, maybe even survive the Pleistocene ice ages?
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**Yes - it is entirely possible**
Biological evolution often is influenced by both to fill an environmental niche (ie, evolve to expand into a less competitive environment) or evolve to cater for an existing one (to change to suit an alteration in the existing environment, such as less or more competition in an existing 'biological space').
The evolution from 'Bear Dog' to 'Bear' could be accomplished by both these factors.
It is worth noting the extinction of the Amphicyonidae family is unknown, but many think it is due to increased competition by other carnivores in the same 'space'. By removing this competition, it is conceivable the evolutionary pathway to more similar attributes to Ursidae is open.
The rest would then be via the same environmental factors that make attributes of Ursidae more desirable. In your question there are no alteration to environmental factors, so these traits could naturally evolve, and indeed are likely to, given the same environmental and competitive conditions.
Keep in mind there are other factors to consider - for instance the Ursidae often evolved from Racoon sized beginnings and slowly grew from there. Your Amphicyonidae would need to be similarly placed in their new environment, growing steadily in both size and ability to suit their new evolutionary pathway.
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If a dichromatic mammal had better night vision than a human, including tapetum lucidum, could they see large (red) and medium (green) light wavelengths but not small (blue)? Would something similar to tritanopia be possible, and if so, how likely? Most mammals that I could find couldn't distinguish red, is that because rods can't pick it up as easily because its wavelengths are large? The animal I'm trying to design can't see uv wavelengths.
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Yes.
Modern mammals lost two different color receptors (cone cell types) to make room for more rods in the eye, to get better night vision. you can easily have the same thing happen.
Mammals lost the UV and green receptor, most importantly without the UV receptor we can't see that end of the spectrum at all, if the blue receptor was lost as well we would lose the color blue entirely.
Just to be clear most mammals can see red, they just cannot distinguish red from orange, yellow and green because they all only activate the one type of cones, whereas we can distinguish them because they activate two different receptors at different levels.
[](https://i.stack.imgur.com/LRLdR.jpg)
[Answer]
### Yes
The non-TL;DR version: It all comes down to [photoreceptors](https://en.wikipedia.org/wiki/Photoreceptor_cell)
Better night vision can be a mix of several things: foveal acuity, tapetum lucidum, and available visual spectrum are the ones that easily come to mind. Foveal acuity could easily be selected for, whether naturally or through selective breeding. The tapetum lucidum assists night vision via retroreflection
The bottom line is that without light in the visual spectrum, you'll need to look elsewhere (pun intended). UV light largely gets [absorbed by the atmosphere](https://www.researchgate.net/publication/320660396/figure/fig17/AS:554166795894784@1509135068014/The-absorption-profile-of-Earths-atmosphere-from-UV-to-IR-The-graph-shows-the-regions.png), but more importantly there won't be nearly as much present at nighttime.
That leaves infrared, which [quite a few animals](https://sciencing.com/animals-can-see-infrared-light-6910261.html) can sense, so evolutionary pressures can select for IR photoreceptors. Since some animals [lose their eyes on evolutionary timescales](https://royalsocietypublishing.org/doi/full/10.1098/rstb.2015.0487), it's not unreasonable that others might lose a vestigial photoreceptor, causing species-wide tritanopia
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For quite some time I wondered how strong graphene is as armour. Don’t get me wrong, I understand what graphenes is and would no doubt make excellent armour.
I want to know how good it would be and what design of armour is the best with this wonder material.
Would a spaced design work better or just having multiple stacks of graphene layered onto each other? Let’s assume armour for a solider in the field. No concealed and armoured jackets for now.
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The tricky thing about graphene is that it is really, really, thin. It only takes a few sheets of graphene to out-perform a kevlar vest, but you could in theory make it a million or even a billion layers thick, and still make a quite comfortably thin and light weight armor material. In other words, you can make it as much stronger than modern armor as you want as long as you are willing to spend the time and money making it that thick.
The real limitation is how much force can be transferred through it. Once you get past a certain thickness, the graphene will hold up against almost anything, but the person inside will be turned into blood pudding from the impact force. This means that the best design will be to layer the graphene over whatever distributes the impact the best. Currently non-newtonian fluids offer the best impact distribution for their weight.
In short, you are looking at what modern body armor already looks like, just with a hundred or so layers of graphene to reinforce it.
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According to furturism.com, you would only need two layers of graphene to create an armor that was as hard as diamond (and can block bullets).
<https://futurism.com/two-layers-graphene-make-diamond-hard-armor-stop-bullet>
This article talks about some experimentation scientists have been doing on graphene layers. (They have also found out it is is a lot more effective than kevlar)
<https://www.extremetech.com/extreme/195089-graphene-body-armor-twice-the-stopping-power-of-kevlar-at-a-fraction-of-the-weight>
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If a race evolved in underground caverns, and had no eyes or vision whatsoever, how would they design buildings and cities for navigation via touch?
They have technology for tunneling through and working with stone much like we do. The buildings are both a mix of hollowed out tunnels, and regular building made of blocks, inside caverns (preferred).
I assume there would be some feature of adding guide rails with braille symbols which everyone would walk around with one hand on, but I'm very interested in practical details, or plausible alternatives, especially in relation to crowd movement and intersections.
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There are big limiting factors. Our buildings differ greatly by the materials property we can produce (technology), climate, ideology and purpose. For example, look up eastern vs western buildings throughout the history.
**Some points you may consider:**
They have to be able to navigate effectively without any external aids, otherwise they wouldn't have survived. Touch would be quite limiting, sounds is a better option. Gongs and bells and other, automatic and periodic sound producing "road signs".
Practicality above all, no need to look cool. Maybe Soviet block buildings.
Similar to their original environment. Narrow cave like tunnels, nicely echoing chambers. If you go with touch instead of hearing, than everything covered in soft, nice feeling (for them) material.
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* **Ropes and strings with various knots, bells**. They can **horizontally span intersections**; you can cross by moving them from your path once you ran into them,
but you'll have them in your way and won't be able to miss their
message. These can be used to create "**soft barrier avenues**" like police tape or velvet ropes that alert some people away from an area, but still allow other people through.
* **Changes in floor height**, for traffic control, or near walls and other obstacles to alert before collisions.
* **Fabrics with different textures** on the walls, maybe on the floors if the difference in textures is significant enough to note when walking on them. If your guys aren't always able to note when they're approaching a wall, you might like to use fabric to pad exterior walls. Some tapestries and embroideries can convey quite a message through touch.
* **Squeaking** floors, for all of the above.
* Elaborate **carvings** (why limit yourself to little braille
symbols)
What you might like to do is try and walk around your house or neighbourhood with a blindfold. That's one way to simulate how sight-impaired people get around.
[Answer]
**Since you specifically ask about touch:**
Tactile architecture could use texture of the surface they navigate in order to direct flows of traffic.
If they always walk, and are always barefoot, that's a pretty convenient way to constantly be "reading" where you are.
As far as avoiding other pedestrians, maybe they talk constantly, or hum while they walk to help others avoid them.
**Other thoughts to consider:**
Ultimately all organisms navigate their surroundings my absorbing energy from the environment, and interpreting those energy signals.
Sight is electromagnetic energy.
Sound and touch are mechanical energy.
Taste and scent are chemical energy.
Ultimately, these senses are for avoiding predators, or finding prey.
Others have gone into solid suggestions about Sight, Sound, Taste, Scent, and Touch.
One I would also offer is the sensation of heat or cold from the environment.
If that is sensitive enough, a hypothetical mole person might be able to sense the radiant energy of its environment with enough resolution to be as effective as sight.
Heat can also be reflected off of surfaces, meaning that a creature that can use radiant heat as its "light" could also effectively use it to see around corners in the same way that a bat can listen to echos to map its surroundings.
[Answer]
People have mentioned touch and sound, but smell / taste could be insteresting to explore as a signalisation method. Think of ant colony pheromones, tracing paths across large buildings like the coloured lines you can find in some large corporations or train stations / airports / etc
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If the polar cap of a tidally locked planet was all ocean, what weather patterns would emerge? The ocean couldn’t be half frozen/half boiling, right? I need a weather pattern so the planet isn’t just a sun blasted desert on the bright side and a frozen wasteland on the dark side. If one (or both) of the poles is an ocean that covers the light and dark sides, could the temperature differentials of the water create wind and other weather patterns?
[Answer]
The easiest way I can think of to explain a tidally-locked planet without extreme differences in temperature between the day and night sides would be through the structure and density of its atmosphere. Let me explain:
The atmosphere of a planet can have many different effects on a planet's temperature: highly dense atmospheres can have a [runaway greenhouse effect](https://en.wikipedia.org/wiki/Runaway_greenhouse_effect) that warms the planet considerably; the atmosphere also has the benefit of creating winds that can circulate temperatures between the hotter and colder halves of the planet.
But there is one bottom line: **The side facing the sun will be hot, and the side facing away from the sun will be cold.** You can't really avoid this fact, because one side is being constantly heated and the other side is getting barely any heat at all. You could have a dense atmosphere, but that will simply make it so that the near side is scorching and unlivable and the far side is simply "less cold."
"Strong constant heating of a planet on one side can change or even control how much weathering occurs on the planet, which can lead to significant and even unstable climate changes. These dramatic climate effects could make a planet that otherwise has the potential for life to instead be uninhabitable."
If you want to have a livable tidally-locked planet, you could:
- 1) have one with a thin Earth-like atmosphere, where there is a habitable zone on and near the border of the light and dark side. However, this would mean the sun is always very low in the sky and near the horizon in those locations, like a constant state of sunset. To these people, completely blue skies would be bizarre and foreign.
- 2) have people living underground on the hotter side or create complicated man-made systems that isolate people from extreme temperature (for example, a giant structured dome)
- 3) give the planet a certain degree of [libration](https://en.wikipedia.org/wiki/Libration). This means that although it is always facing the sun, it would "wobble" back and forth, giving a greater range of variation in temperature and potentially increasing the areas of livability.
You can also read [this paper](https://arxiv.org/ftp/arxiv/papers/1405/1405.1025.pdf) for more helpful information on a tidally-locked planet.
[Answer]
**Tidally locked planets can be habitable**
In actuality, having a tidally locked planet isn't such a big problem for habitability w.r.t. climate. [Take a look at what PlaSim](https://iopscience.iop.org/article/10.3847/1538-4357/aa80e1) generates for a tidally locked earth with solar constant of $1100\text{Wm}^{-2}$ (real earth value: $1360\text{Wm}^{-2}$). Notice how the climate on the day side ends up quite similar: the region around the pacific ocean is habitable.
The atlantic ocean ends up much like the north pole in winter: a few metres of ice covering liquid water below, and temperatures around $-30^{\circ}\text{C}$. Landmasses on the cold side can get quite cold, the model seems to indicate $-110^{\circ}\text{C}$ as the minimum average temperature. One interesting observation: a tidally locked earth can have liquid surface water down to $950\text{Wm}^{-2}$, while the real earth is a snowball below $1200\text{Wm}^{-2}$ and would need more CO2 to be habitable.
So what happens here? Two effects actually make tidal locking less of a problem than it seems. First, the weather patterns. On a tidally locked world, the atmosphere and oceans turn into efficient heat transport mechanisms from the light to the dark side. You can see it in the model results: Comparing the heat transport:
* Earth: $ H \approx 1.7 \text{Wm}^{-2}\text{K}^{-1}$
* Locked Earth: $H \approx 13.0 \text{Wm}^{-2}\text{K}^{-1}$
The temperature difference between the two sides is inversely proportional to the heat transport coefficient, and proportional to the diffrence in solar illumination, or: $\Delta T \propto H^{-1}\Delta G$. What this tells us about the climate on a tidal locked planet is some combination of:
* Average wind speeds are (much) higher.
* For tidal locked planets near the inner edge of the HZ: *Hurricanes* can be very strong and more common (even without the coriolis effect), as the 'pole of heat' on the day side forms a large area where storm systems can form. Similarly, dry, cold storms can form on the night side.
* Rain will be more common, especially around the transition zone.
* Weather tends to be more predictable.
The second effect is that of oceans. Oceans are great absorbers of heat, and take many years to heat up even from the sunlight on them. It takes one calorie to heat 1g of water up one degree (at standard pressure and temperature). Or:
$C\_{\text{aq}} = 4.186\text{Jg}^{-1}$
Given an ocean column of $d = 5\text{km}$ deep, and surface area $A=1\text{m}^2$, how long would it take the midday sun to heat it up a single degree?
$$t =\frac{ V\rho C}{G} \approx \frac{10^6dC}{G} \approx 1.53 \cdot 10^7s \approx 0.61 \textbf{ years} $$
Which means even with the slow ocean currents the deep ocean would have a uniform temperature. You might think that if you lived on a tropical island near a deep trench, the seawater down in the abyssal depths would be warm just like the seawater on the surface. In reality, the ocean has a steep [thermocline](https://en.wikipedia.org/wiki/Thermocline). The water deep down is surprisingly cold.
So nearby oceans will have a large moderating effect on local temperatures. Have a look at this [model of a tidally locked ocean planet](https://www.pnas.org/content/111/2/629). This model tells us that we don't need to have a deathly cold night side.
Increasing the ease at which oceans can transport heat by not having north-south continental shelves near the transition zone, or having more ocean and less land can make your exoplanet have a stabler climate with less variation.
You can see this on earth too. The most extreme climates (e.g. Siberia) are inland, with the dominant wind direction away from the sea. Milder climates (such as say southern Tasmania, or equatorial islands) are often maritime.
Notice how in this model also there are cold areas on the 'light' side (near the poles) and warmer areas on the dark side (near the equator).
The former are caused by the same mechanism as on earth (yes, there is constant sunlight, but it's of low intensity, equivalent to the light the North pole gets in April around noon).
The latter are caused by heat transport and a tidally locked planet's version of hadley cells. [This video](https://www.youtube.com/watch?v=n_E9UShtyY8) provides a nice overview of some of the basics.
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In [one of my previous questions](https://worldbuilding.stackexchange.com/questions/154298/how-powerful-a-starship-coilgun-can-we-make?noredirect=1#comment485840_154298), I asked about the viability of creating a coilgun for use on a sci-fi warship which would be capable of accelerating a 1000kg projectile to a velocity of 30 km/s or better, with a barrel length no greater than 100 meters. The answers I got indicated that the answer was 'possibly, but it's right on the edge of what is physically possible' and that actually building such a weapon might be beyond what could be practically achieved. However, in another thread on this site I saw someone mention [Operation Plumbbob](https://en.wikipedia.org/wiki/Operation_Plumbbob#Propulsion_of_steel_plate_cap), a nuclear test where a bomb was placed down a sealed shaft, and its detonation blew off the steel plate sealing the shaft at a velocity in excess of 60 km/s. This got the wheels in my head turning.
In a discussion I had with Starfish Prime, he recommended that I use antimatter-catalyzed fusion for my sci-fi spaceship designs, since you need a miniscule amount of antimatter to induce fusion in a pellet of deuterium and helium-3, surrounded by lead. It allows you to extremely efficiently create small fusion explosions which can be used to propel your spacecraft... but what about using this technology as a replacement for gunpowder in a large warship cannon? Can I use it to get my 100 meter-long cannon to expel a 1000 kg projectile at 30 km/s or better? Or would such a weapon be doomed to blow itself apart?
EDIT: To clarify, my precise question is: Assuming I have the capability to use this technology to create a scalable fusion explosion on the order of, say, equivalent to 100-1000 tons of TNT, can I build a cannon which can contain and direct this explosion, using it to get the performance figures I want, without wrecking the cannon and/or ship? The cannon isn't restricted to just conventional designs, it could use magnetic containment or any other known techniques, if they'll help, but it has to recognizably be a *cannon*; as in a fixed or mounted weapon attached to a larger ship.
[Answer]
It won't be a cannon at all, but a warhead.
This sort of device was actually investigated as far back as the 1980's under the Strategic Defense Initiative, and was part of a wider ranging investigation to harness the power of nuclear devices to drive weapons effects, so called "Third Generation Nuclear Weapons"
The basis of all these devices is to encase the nuclear "physics package" in a radiation case with one opening, so in the microseconds before the case is destroyed, the energy of the device is preferentially released through the hole. This can then be used to energize other materials, and create plasmas, shaped charges or explosively forged projectiles and even "shotguns". The performance of these devices was calculated to be amazing, the "shotgun" could fire pellets as fast as 100km/sec (at that speed, even a gram sized pellet would have the kinetic energy equivalent of a stick of dynamite), while the other proposals would have projectiles moving at small fractions of the speed of light.
[](https://i.stack.imgur.com/9ZR6a.jpg)
*Orion pulse unit. This is the basis of all third generation weapons*
There is no free lunch, however. While up to 85% of the energy of the device can be captured and used to drive weapons effects, attempting to "narrow" the cone of energy to increase the range will cause a falloff in the amount of energy being delivered to the target. There is discussion in many of the links below, but the overall conclusion is the best way to use this sort of device is to drive an Explosively Forged Projectile, which has the benefits of capturing a large fraction of the energy and having a long range (by virtue of simply being a large, unitary "cannonball", rather than a cloud of pellets or a stream of liquid metal moving at various speeds along the length of the stream). A spindle of star hot plasma will be energetically similar to a laser, at least until the plasma disperses
<https://atomic-skies.blogspot.com/2015/03/third-generation-nuclear-weapons.html>
<https://toughsf.blogspot.com/2016/06/the-nuclear-spear-casaba-howitzer.html>
<https://toughsf.blogspot.com/2017/05/nuclear-efp-and-heat.html>
Because the driver is a nuclear explosion, the radiation case will be consumed by the activation of the device. This means you will not have a "cannon", but rather the warhead which can be fired from a mass driver or mounted on a missile bus. Fourth generation devices may be smaller due the lack of a fission trigger, but will still have a massive energetic release when activated. If you reduce the amount of nuclear fuel to minimize the explosion, then the amount of overall energy being released will also be less. Remember, you can only harvest 85% of the energy, so a nuclear "hand grenade" is going to have far less effect than a device who's output is measured in kilotons or megatons. Given the great ranges and possibility of missing due to a minor aiming error or small movement by the target ship 300,000 km away, a cloud of pellets or a bunch of hypervelocity darts moving at .03 *c* are the sort of weapons that you will need.
[](https://i.stack.imgur.com/ULoqK.jpg)
*This is the real business end of a space warship*
[Answer]
I think I'm pretty much saying the same thing as Thucydides except in laymen's terms. The issue with using a nuke would be blow back and fouling.
Blowback being the amount of energy released back onto the, i guess you could say nuke cannon. That would be a very bad thing in zero-g.
It would act as a propellant against the ship.
And the fouling could be potentially be very nasty; coating the ship firing the weapon in fallout.
Have you explored the use of maybe an electromagnetic Railgun?
The recoil is apparently very low while still being able to accelerate the speed of a large solid metal projectile at incredible speeds.
[Answer]
TL;DR: No, don't do this.
Longer answer:
Inefficiency will kill you, because nukes generate a lot of energy, and you don't want all that energy going into your ship or your launcher. All nuclear reactions will generate a lot of radiation. You're trying to use this radiation to heat some form of propellant (which may simply be the bomb casing) which will then expand and push a projectile out of the barrel.
Absorbing *all* the x-rays, gamma-rays or neutrons from the reaction is going to be impractical unless you have a *colossal* propellant charge. All the radiation you fail to absorb will heat your gun and its surroundings, and you'll suffer from neutron embrittlement, neutron activation, photofission and photodisintegration and secondary bremmstrahlung radiation (oh my!) none of which you want to deal with. If you *do* absorb all (or most) of the energy, you may find that the average heat of your propellant is simply too low, and it won't expand fast enough and hard enough to give you the 30km/s+ muzzle velocity you need. You're then faced with a nasty tradeoff: if you want power, you have to put up with being cooked and irradiated. If you want safety and long weapon life, you have to put up with sedate muzzle velocities.
Secondly, efficiently propelling a projectile is an [awkward problem](https://en.wikipedia.org/wiki/Physics_of_firearms#Firearm_energy_efficiency). Not all the energy of your propellant reaction is going to go into the projectile. You might manage better than the 30% at the link (for a start, you probably won't be using rifling) but even small percentages of wastage are bad news. Your projectile needs at least 450GJ of kinetic energy. If the propulsion is an amazing 50% efficient, that means you need to put 900GJ in (and that's useful energy in the propellant, after all the losses mentioned above) and you'll dump the remaining 450GJ (108t of TNT equivalent) into barrel heating, barrel wear and escaping hot gasses which will act like a rocket engine on the firing ship.
Getting that muzzle energy may be even harder than you think. [The Effects of Nuclear Test ban Regimes on Third generation weapon Innovation](http://scienceandglobalsecurity.org/archive/sgs01fenstermacher.pdf), the author speaks of a mere 5% efficiency in coupling bomb output energy to projectile kinetic energy. To get 450GJ in the projectile, you need a 9TJ bomb yield (2kt TNT equivalent). The high muzzle velocities you want are achievable (the Chamita test, part of Operation Grenadier, apparently accelerated a 1kg plate to 70km/s) but keeping the plate intact and flying straight is another matter altogether. With yields over a kilotonne-equivalent, the thermal radiation from the blast appears to be sufficient to disrupt your projectile long before it reaches its target.
Matterbeam's *wildly* optimistic post on nuclear EFPs notwithstanding, this just doesn't seem like a particularly great way to shoot a bullet. Consider, perhaps, using your micronukes to drive mini-orion missiles instead?
---
You may be interested to know that one of the early design proposals for *Project Orion* involved a big combustion chamber in which the propulsion unit was detonated, with the resulting products exhausted out of a nozzle at the back. The design was dropped because it massively increased the engineering difficulties, without adding anything to thrust or Isp. This suggests your nuclear gunbarrel approach isn't likely to be any better than an Orion-style *external* propulsion system. Irritatingly, I don't have the details of this dead-end to hand... I think I came across it in *The Starflight Handbook*, and I don't have a copy of that conveniently available anymore. If I locate one any time soon, I'll update this.
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I have a planet similar to Venus(similar size and atmosphere) that has floating continents in the atmosphere due to strong magnetic fields. If it is possible, what would the continents need to be made of, and how big could they be?
[Answer]
**To lift a continent the size of Australia on Venus, you'd need 13,682C of charge between continent and planet.**
The only condition for a floating continent is that the force of the electromagnetic field is greater than the force of gravity. With this in mind,
$ F\_{gravitational} < F\_{electromagentic} $
and thus,
$ \frac{GMm}{r^2} < \frac{Q\_1Q\_2}{4\pi\epsilon\_0r^2} {\*} AreaOfSurface $
I've substituted in an electric field in place of a magnetic one (the effect is much the same- you get big amounts of repulsion). We assume the electrostatic force the planet exerts on the continent is the same in size from the continent to the planet. Now taking the mass of Venus to be $4.867x10^{24} kg$, the mass of Australia as $4.033x10^{16} kg$ and the area of Australia to be $7.692x10^{12} m^2$, we can rearrange the above equations to the following:
$6.67\*10^{-11} \* (4.867\*10^{24}-4.033\*10^{16})(4.033\*10^{16}) < Q^2 \* 7.692\*10^{12} $
$ Q^2\_{minimum} = \frac{1.440\*10^{21}}{7.692\*10^{12}} $
$ Q\_{minimum} = 13,682 Coulombs $
Numerically, 13,682 Coulombs sounds OK. However, once you learn that [a lightning strike is 15 Coulombs of charge](https://www.quora.com/How-big-is-1-coulomb-of-charge), maintaining this kind of energy over the area you'd need to quickly becomes a task too great for modern technology to handle. **Having this sort of energy as a planet-wide magnetic field would deep fry anything trying to live on the surface** (consider for a start the impact this would have on electronics- how would anyone be able to live on this floating continent?).
If a floating continent is truly what your heart desires, maybe look into an artificial gravity source that pulls the continent away from the planet? Could be cool having a continent that's upside down relative to the rest of your world. It may not be that much more efficient, but the lack of magnetic fields would mean modern technology could still very much be embraced.
Happy worldbuilding!
[Answer]
[Here](https://www.coolmagnetman.com/maglev.htm) you find some examples of magnetic levitation. The only one that might suit your needs may be:
5. Repulsion between a magnet and a superconductor.
You can not levitate magnets in stable fields:
>
> The stable levitation of magnets is forbidden by Earnshaw's theorem, which states
> that no stationary object made of magnets in a fixed configuration can be held in
> stable equilibrium by any combination of static magnetic or gravitational forces,.
> Earnshaw's theorem can be viewed as a consequence of the Maxwell equations, which
> do not allow the magnitude of a magnetic field in a free space to possess a maximum,
> as required for stable equilibrium.
>
>
>
Currently the only known way to do it is:
>
> Diamagnets (which respond to magnetic fields with
> mild repulsion) are known to flout the theorem, as their negative susceptibility results
> in the requirement of a minimum rather than a maximum in the field's magnitude,.
> Nevertheless, levitation of a magnet without using superconductors is widely thought
> to be impossible. We find that the stable levitation of a magnet can be achieved using
> the feeble diamagnetism of materials that are normally perceived as being
> non-magnetic, so that even human fingers can keep a magnet hovering in mid-air
> without touching it.
>
>
>
[Here](https://www.coolmagnetman.com/magsuper.htm) is the example. It has a problem though:
>
> One problem, though, is that if the magnetic field of the current flowing within the superconductor becomes large enough, the ceramic will drop out of superconductivity, even if it is cold. Large magnetic fields will destroy the superconducting state. So, there is always a balance between the temperature, the magnitude of the magnetic field due to the current, and the molecular structure in determining the suitability of the superconductor for a particular application.
>
>
>
[Answer]
This is not a complete answer because I haven't worked out how strong the magnetic field needs to be. One difficulty here is that a magnetic object cannot in general be stable in a static magnetic field. To keep this stable, you might want inside the continents giant superconducting sections. They could then use the [Meissner effect](https://en.wikipedia.org/wiki/Meissner_effect) or similar results which can result in stable positions. Edit see also this earlier question about this [Can the Meissner effect explain very large floating structures?](https://worldbuilding.stackexchange.com/questions/143152/can-the-meissner-effect-explain-very-large-floating-structures?rq=1)
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In an effort to gain inspiration for planetary formation and, at the same time, inspiration for governmental/territorial boundaries between residents of said formed planets, I've recently encountered a natural linear format (I won't say which, to avoid biasing answers) that is much longer than I ever expected for a natural formation. This got me wondering: **Just how long can a linear natural formation actually be?** or an alternative wording might be: **What is the longest naturally formed linear structure known to science?**
Some clarifications and definitions:
"Natural" just means not man-made. Plant-made or non-human-animal made is fair game, as are structures formed by natural/geological processes.
"Structure" There must be a solid component involved. The striped gasses of Jupiter, or the rings of Saturn, for example, are not valid, despite the likelihood that crystals of various ices are present, the gaps between said crystals break the "structure" in to smaller pieces, so it is not a complete single structure.
"Linear" is not meant to be taken in the literal mathematical sense, as this would imply something that has no width, depth, or even mass. Instead, it should be understood to mean that the structure follows a relatively straight line, from start the finish. Deviation to follow the curvature of the Earth or other planet or moon (if the structure is not on Earth), is allowed, when applicable. I'm hesitant to place a more strict definition on it, but something that came to mind is that it should not waiver more than its own width off of it's centerline, but this might be overly restrictive, for example if a river is 1 mile wide, and you draw a line from the start point to the end point, then neither bank of the river should be farther than 1.5 miles from that centerline in order for t to be considered linear. Again, that's just something that seems somewhat reasonable to me, but can be taken with a grain of salt and argued if a particularly promising structure deviates slightly more than that. It should be linear as viewed by the naked human eye, assuming proper perspective viewing angle (even if that means it must be seen from space to see that it's linear) **EDIT** I think this section needs a bit more clarification, though it might only make it more vague. I'll provide some examples of things that I would consider close enough to 'linear' for me to accept, given a convincing argument and/or description, etc: The Baja peninsula, the Gulf of California, the Red Sea, or the west coast of Chile. Of those examples, the Baja peninsula is probably the least linear because of that point about halfway that sticks out to the west.
"Structure" or "Formation". I can't imagine a comprehensive list is possible, but things that came to mind as examples of what I'm referring to are Rivers/Riverbanks, Coastlines, Mountain Ranges, Cliffs/ridgelines, Glaciers, Caves. Canyons (with or without the presences of surrounding mountains)
[Answer]
I would have to go with Saturn's moon, Iapetus. Iapetus has a mountain range all the way around its 1500 km equator:
[](https://i.stack.imgur.com/WlMJe.jpg)
The current theory is that it is a collapsed ring that once cirlced Iapetus.
[Answer]
I'll try.
Continents as a whole have a lot of variation in height, but tje ice on the poles is mostly flat. Almost every picture of anywhere on Antarctica looks like an endless plain until the horizon. So except for a big ridge it has off center, you could day a line from shore to shore is mostly linear.
Sputnik Planitia in Pluto is 1/15 the size of the South Pole, but is flatter.
[Answer]
I would probably say the Atlantic mid-ocean ridge. It's not perfectly linear, but it follows almost the exact midpoint of the Atlantic Ocean from the tip of South America all the way to the Arctic Circle. That's almost 16,000 kilometers.
[](https://i.stack.imgur.com/IZRVv.jpg)
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[Question]
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In my setting their exists the Kingdom of Tor a kingdom nestled nearby a small mountain range. The capital city, Tor, is built along a tributary of the river Goro one of the largest rivers in the setting and a river that connects many of the human kingdom's (think Mississippi style river). The kings of Tor are shrewd and after inheriting a toll castle along the river Goro saw the financial gain they could get from controlling this crucial river.
Instead of conquest the Kings of Tor used diplomacy. They slowly married off their own daughters and sons to various noble houses and over the centuries have gained many new territories and vassals with many having territories on strategic sections of the Goro or it's tributaries.
One slight issue. Most of these new territories would be considered exclaves with most being surrounded by other realms (but having access to the river)
How could a kingdom like Tor: one made up of mainly exclaves, survive and function? By function I mean politically how could the Crown of Tor assert its authority over its vassals when for all intents and purposes they're surrounded by another Kings land?
Note:
tech is the High Middle Ages if that matters
Almost all of these exclaves have some sort of access to the Goro river.
[Answer]
**SHORT ANSWER:**
The plan of the Kings of Tor could work, with some qualifications.
**LONG ANSWER:**
**INHERITANCE IS A ONE WAY STREET**
The plan of the Kings of Tor to acquire land by marrying off their sons and daughters to other noble houses wouldn't work. Or rather, the marrying off of the daughters to members of other royal or noble houses wouldn't work for the Kings of Tor.
For example, King William the Evil Usurper who conquered England in 1066 was related to the former King Edward the Confessor who died in 1066. William's grand aunt Emma was the wife of King Aethelred the Unready of England and the mother of King Edward the Confessor.
So, because King Edward the Confessor of England was descended from earlier Dukes of Normandy through his mother, King Edward the Confessor had a legal claim to the Duchy of Normandy. If Duke William of Normandy and all his children and close relatives died, King William the Confessor of England could have claimed Normandy and might have acquired it.
But, despite what some illogical people say, Duke William of Normandy had no claim to the Kingdom of England through that relationship. Duke William of Normandy was not descended from any previous King of England. He wasn't even descended from any English serfs or slaves.
When the daughter of a king or lord marries someone, she transmits a potential to inherit her father's lands or part of them to her husband and her descendants. But she doesn't transmit any potential claim to inherit her husband's lands from her husband to her father and brothers.
So if A, King of Tor, married his daughter B to Lord C of the fief D, and they had a son Lord E of the fief D, Lord E of the fief D would have a potential claim to inherit the Kingdom of Tor. If everyone ahead of him died, and if the inheritance rules of Tor permitted inheritance through females, Lord E of the fief D could inherit the entire Kingdom of Tor, or a part of it.
If F, King of Tor, married his son and heir G to lady H of the fief I, and they had a son and heir J, J would be in line to inherit the Kingdom of Tor from his father G and grandfather F. And if Lady H's brothers all died without children, and if the laws of fief I allowed inheritance through females, J could inherit part or all of fief I.
And in the European Middle Ages most lords, barons, viscounts, counts, landgraves, margraves, counts palatine, princes, dukes, kings, emperors, etc., considered the possibilities of inheritance when choosing who to marry their children to. They would guess which eligible females were mostly likely to become heiresses when choosing brides for their sons, and when choosing husbands for their daughters they would guess which families they would least mind having their lands inherited by in the future.
**THE MARRIAGE CHOICES OF EMPEROR MAXIMILIAN I (1459-1519)**
The workings of fate, or blind chance, or something, really favored the matrimonial choices of Maximilian I, Elected Emperor of the Romans and hereditary Archduke of Austria, Duke of Styria, etc.
First he married in 1477 Mary, Duchess of Burgundy, etc., etc. and after her death was often the regent for their son and heir Philip the Handsome.
Then he negotiated two marriage alliances with King Ferdinand II of Aragon, etc. and his wife Queen Isabella I of Castile, etc.
Maximilian's son and heir Philip the Handsome married Joanna La Loca, daughter of Ferdinand & Isabella, in 1496. Ferdinand and Isabella's son and heir John, Prince of Asturias, married Maximilian's daughter Margaret in 1797.
If everything went well for everybody, Philip, the ruler of Burgundy, etc., would have inherited Austria, etc, from his father, and John would have inherited Aragon, etc., and Castile, etc. from his parents.
But John, Prince of Austurias, died childless in 1497, and his widow gave birth to a stillborn child. John's oldest sister Isabella, Queen of King Manuel I of Portugal died in 1498, and her only child Miguel de Paz, eventual heir of Portugal, Aragon, etc., and Castile, etc., died in 1500.
That left John's next sister Joanna la Loca as the heiress of Ferdinand and Isabella. When Isabella died in 1504. Joanna became the Queen of Castile, etc., and Philip the Handsome became King of Castile, etc., as her husband. But Philip died in 1506, and King Ferdinand II took over ruling Castile, etc., in the name of his daughter Joanna.
Philip the Handsome and joanna's oldest son and heir Charles, eventually inherited all the lands of his four grandparents.
Charles inherited Austria, etc. from his paternal grandfather Maximilian I in 1519, Burgundy, etc., (which came from his paternal grandmother Mary) from his father Philip in 1506, Aragon, etc., from his maternal grandfather in 1516, and castile, etc. from his maternal grandmother Isabella in 1516. Technically Charles didn't inherit Castile, etc., from his mother Joanna la Loca until she died in 1555, but he became co King of Castile, etc. with his mother Joanna in 1516 and ruled in her name.
In 1515 Maximilian met with Sigismund I, King of Poland and Grand Duke of Lithuania, and his brother Vladislaus II, King of Hungary, etc., and King of Bohemia, and negotiated a mutual succession treaty and arranged another double marriage, between Vladisaus's son and heir Louis and Maximilian's granddaughter Mary, and between Maximilian's younger grandson Ferdinand and Vladisaus' daughter Anna.
Ferdinand married Anna in 1521 and Louis married Mary in 1515. King Louis was killed in the Battle of Mohacs against the Turks in 1526 without any legitimate Children, and Ferdinand became King of Bohemia and King of part of Hungary.
So by fate or chance or something Emperor Maximilian I's matrimonial decisions paid off really, really, really big time, thus inspiring the famous rhyme:
>
> Bella gerant aliī, tū fēlix Austria nūbe/ Nam quae Mars aliīs, dat tibi regna Venus, "Let others wage war, but thou, O happy Austria, marry; for those kingdoms which Mars gives to others, Venus gives to thee."
>
>
>
<https://en.wikipedia.org/wiki/Maximilian_I,_Holy_Roman_Emperor#Tu_felix_Austria_nube>[1](https://en.wikipedia.org/wiki/Maximilian_I,_Holy_Roman_Emperor#Tu_felix_Austria_nube)
And basically about 99 percent of the noble and royal marriages in western Europe for many centuries before and after the time of Maximilian I were arranged with at least a little thought and hope that something like this might happen to benefit one family or the other.
**ACQUIRE FIEFS IN OTHER KINGDOMS BY MARRIAGE - YES**
So it would be perfectly possible for the Kings of Tor to acquire small fiefs in other kingdoms by married women whose descendants would eventually inherit those fiefs.
In 1120, William, only legitimate son of Henry I, King of England and Duke of Normandy (son of William the Evil Usurper mentioned above), died in the White Ship disaster. Henry's only legitimate daughter, Empress Matilda (1102-1167), was married to Emperor Henry V. Emperor Henry V died childless in 1125 and Matilda returned to England and Normandy.
Henry I married Matilda to Geoffrey "Plantagenet" (1113-1151) in 1128. Geoffrey's father Fulk named him Count of Anjou and Maine in France in 1129 and went to become King of Jersusalem. King Henry I died in 1135, and civil war erupted in England and Normandy between Empress Matilda and Stephen Count of Blois.
Eleanor of Aquitaine (1122/24-1204) inherited the large and wealthy Duchy of Aquitaine, etc. in France in 1137, making her the most desirable heiress in Europe. Her overlord and thus guardian, King Louis VI of France, whose own royal domain was much smaller than Aquitaine, married her - surprise, surprise - to his son and heir King Louis VII of France in 1137.
In 1152 King Louis VII had his marriage with Eleanor, which had produced only girls, annulled. Eleanor promptly married another French vassal, Henry (1133-1189) Duke of Normandy, Count of Anjou and Maine, etc., the oldest son of Empress Matilda and already an over mighty vassal of the King. Now Henry and Eleanor ruled about as much land as all the other French lords - including the King - put together, and were vastly more powerful than the King.
Then, in 1154, King Stephen of England, Matilda's rival, died and Henry became King Henry I of England. And for three centuries the history of England and France was was dominated by the fact that the King of one country, England, owned various fiefs that totaled about half the area of France. The Kings of England were totally independent of France in England, but in France they were legally merely dukes and counts of various fiefs and thus vassals of of the King of France.
Since in this extreme historic case the Kings of France were unable to prevent foreign Kings from inheriting huge fiefs in France, half the entire Kingdom, you can expect that in most feudal kingdoms the Kings would be unable to prevent foreign kings of inheriting various small fiefs.
So it would be perfectly possible for Kings of Tor to inherit various disconnected fiefs in one or more kingdoms along the River Goro. Keeping everyone of them forever would be a different matter and would depend on various events in the history of those fiefs and there relations with other fiefs and with various overlords who might confiscate those fiefs if angry at the king of Tor. In short, how long those fiefs were retained would depend on the fictional history in your story.
Note that the typical relationship between the Kingdom of Tor and various fiefs obtained by the kings of Tor in one or more kingdoms along the River Goro would that of a personal union. In such a personal Union the fiefs would not have their governments united with each other or with the Kingdom of Tor. The only thing the various lands would have in common was that a single person would be King of Tor and also the lord, count, duke, etc. of the various fiefs.
<https://en.wikipedia.org/wiki/Personal_union>[2](https://en.wikipedia.org/wiki/Personal_union)
**ACQUIRE KINGDOMS BY MARRIAGE - YES**
It was obviously possible for someone to acquire other kingdoms by marriage and pass them on to their descendants.
The examples given in the section about the marriage arrangements of Emperor Maximilian I prove that, for example.
Note that King Ferdinand II of Aragon ruled several kingdoms that were separated by the sea from Aragon, Valencia, and Barcelona, including the Kingdom of Sicily, the other Kingdom of Sicily, and the Kingdom of Sardinia.
The Castilian group of Kingdoms included "The Kingdom of the Indias, the Islands and Mainland of the Ocean Sea" far across the Atlantic Ocean.
For a couple of centuries the Kings of the Spanish kingdoms also ruled the Burgundian lands, a group of fiefs in the Kingdom of Germany in the Holy Roman Empire, and some in the Kingdom of France, and all separated from Spain by hundreds of miles by land or by sea.
So it was certainly possible to acquire several separate kingdoms and fiefs that were physically sparated by water or bylands of other kingdoms and fiefs.
I note that in medieval Ireland there were allegedly about 90 or 150 kingdoms, according to different sources. The Island of Ireland has an area of about 84,421 square kilometers or 32,595 square miles.
If one assumes that there were about 50 to 200 kingdoms at any one time in medieval Ireland, the average size kingdom would have an area of about 422.105 to 1,688.42 square kilometers or 162.975 to 651.9 square miles. So if the average kingdom was a perfect square it would be about 20.545 to 41.09 kilometers, or 12.766 to 25.532 miles on each side. Someone could walk from one Kingdom across another whole kingdom and into a third during a single day.
At times when the population of medieval Ireland was amount 1,000,000 persons, the average Irish kingdom might have a population of about 5,000 to 20,000.
So if the Goro River was a very long river there could have been hundreds of such tiny kingdoms if it was several thousand kilometers or miles long, especially if those kingdoms had narrow water fronts and stretched a long way back inland from the River.
So if the Kings of Tor married princess from nearby and sometimes distant kingdoms along the Goro River, they might from time to time inherit various scattered kingdoms along the river. Some of those kingdoms might be separated from other kingdoms ruled by the King of Tor by only a few in between kingdoms, while others might be separated by tens of kingdoms.
Each and every single kingdom inherited by the Kings of Tor would normally remain a separate kingdom, independent from the Kingdom of Tor and from the other kingdoms along the river. That is called a personal union, when the only thing that two different kingdoms have in common is that the same person is the monarch of both of them. And in history that was the normal relationship between two different kingdoms that had the same monarch. It would usually take generations or centuries of having the same ruler for the two kingdoms to agree to unite into one larger kingdom.
<https://en.wikipedia.org/wiki/Personal_union>[2](https://en.wikipedia.org/wiki/Personal_union)
**ACQUIRE FIEFS IN OTHER KINGDOMS AND MAKE THEM PART OF YOUR OWN KINGDOM - NO, NO, NO!**
The main reason why the Kings of Tor would not make fiefs they inherited in other kingdoms part of the Kingdom of Tor is that would be obviously a crime. As lords of fiefs in another kingdom, they would be vassals of another king, the king of that kingdom, and so would be legally obligated to be loyal subjects. Stealing land from his kingdom would not be loyal to him. It would be an act of treason. Treason, if unsuccessful, was often punished by death and almost always by confiscation of the fief.
And taking land out of one kingdom and making it part of another kingdom would be an obvious act of aggression by the kingdom that acquired it. Medieval rulers rarely committed (obvious) acts of aggression, which after all, set bad examples for their neighbors in the future. Medieval rulers preferred to disguise their aggression with all sorts of silly excuses.
So the Kings of Tor would probably not try to make any fiefs they inherited in other kingdoms parts of the Kingdom of Tor, not while their society was anything like medieval Euorpean society.
[Answer]
**Option 1: The Hapsburg Plan**
As many comments have pointed out, this arrangement was not uncommon in Medieval Europe, where national identity as we know it did not exist and loyalty was based on feudal obligations and kinship ties. This option does have some limitations, though. It works best if the other lands between your kingdom’s holding are all part of a larger confederation, such as the Holy Roman Empire, or are at least the same religion as you with no competing sects. This is to avoid most justifications for war. If there is a regular structure for the various lands around your kingdom, you can try to dominate it, as the Hapsburgs did in the HRE. If not, just use manipulation, alliances, and maybe the occasional war to keep any competing central power weak, as the English did to the French crown (Medieval English kings were major landowners in France thanks to William the Conqueror and Eleanor of Aquitane), and as the Hapsburgs tried to do when the controlled both Germany and Spain.
**Option 2: The Dutch Plan**
Maybe you lack the necessary conditions for the Hapsburg plan, or you’re just more paranoid about your security. Well, as the early modern Dutch jealously guarded their naval superiority on the high seas, so must you with the Goro river. Invest in castles at any key points on the river, for instance where major tributaries join or any easy fords where an enemy may try to cut you off. The river is your life blood, and you must guard it jealously! At the same time, sell off any lands that are too far from the river, you can never hold them in warfare. Once you have the castles and a decent river fleet, you don’t even need a large standing army: it’s hard to muster a long siege in the Middle Ages, and you can resupply from your other holdings. Just be careful your enemies don’t maneuver a grand alliance to threaten all your castles at once. Finally, now that your control of the river is secure, milk that for all the profits you can to keep your number one spot. Set up tolls for river traffic passing your castles as well as at every major bridge. The Rhine in Germany is a good example of this too, and why there are so many castles there.
[Answer]
**Build a Trade-focused Nation**
There are several examples in the historical period you are targeting of nations which built themselves off of several small but wealthy cities on vital trade routes. Here are some examples:
* [The Hanseatic League](https://en.wikipedia.org/wiki/Hanseatic_League), which consisted of several north German and Baltic cities with close ties to merchant guilds, which also controlled several inland cities on vital river routes.
* [The Republic of Genoa](https://en.wikipedia.org/wiki/Republic_of_Genoa), which had their main cities in northern Italy but at their height controlled vital land in Corsica, Greece, and as far as Crimea.
* [The Republic of Venice](https://en.wikipedia.org/wiki/Republic_of_Venice), which also controlled several disconnected trading ports along the Adriatic, in Greece, and as far as Cyprus.
You might have seen the trend, but if your controlling land is not connected by land, it is pretty vital that they be connected by sea. If there is no way to travel between your major cities, you are going to have problems.
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I am not talking about anterior, posterior, etc... I am looking for words specifically relating to movement.
Long description...
In the mythos I am working on, mages learn to control objects in three dimensional space. They first learn to summon objects within six different spaces.
* Anterior = Front
* Posterior = Back
* Superior = Upper
* Inferior = Lower
* Dextral = Right hand side
* Sinistral = Left hand side
After learning to summon objects fluently in all six spaces, they learn to "throw" objects in different directions.
For example: a student would consistently summon a stone in the dextral, superior space (to their right side just above their head). An instructor would shout directions and the student would have to "throw" the stone in the correct direction. So, any object moving in an anterior direction according to the perspective of the mage, regardless of where it was summoned, would be moving "forward" or ???. Any object moving in a dextral direction according to the perspective of the mage, regardless of where it was summoned, would be moving "to the right" or ???, etc...
I have accepted that I may just have to use the words right, left, forward, back, up, and down. I just want to see if I'm missing some more specific/scientific terms.
To clarify: this isn't fur the reader's benefit, I am trying to find weird that would cost approximate what the instructors would be using in their teaching. The people that use magic are very scientific, dictionary, vocabulary oriented and using common terms like up, down, left, right would be to, well, common.
[Answer]
Anatomy has some useful words:
```
Superior -> Above
Inferior -> Below
Ventral -> Fore of the body
Dorsal -> Back of the body
Frontal -> Fore of the head
Occipital -> Back of the head
Distal -> Out, towards the tip of extremities
Proximal -> In, towards the body
Rostral -> Towards the face
Caudal -> Towards the tail
```
They say left and right in anatomy, as far as I can tell.
I found [usage](https://www.researchgate.net/figure/Three-reference-planes-and-six-fundamental-directions-of-the-body-movement_fig3_323160009) of `Lateral` for right and `Contra-lateral` for left.
We can import some words from heraldry for left and right:
```
Dexter -> Right (of the knight or shield, not the observer)
Sinister -> Left (of the knight or shield, not the observer)
```
I think you will prefer `Sinistral and Dextral`, by the way. Which are the words we use for chirality. They would work like `Port` and `Starboard` in that they always refer to direction relative to the observed, except you do not have to explain why mages talk about ports.
I also want to bring into attention these words from physics and chemistry:
```
Dextrorotation -> Clockwise rotation
Levorotation -> Counterclockwise rotation
```
Note: these are always respect the observer. *We do not say the hands of the clock are rotating counterclockwise when we are behind it.*
Speaking of rotation, anatomy has some:
```
Anteversion -> Rotate to the front
Retroversion -> Rotate to the back
```
Axes:
```
Longitudinal -> Head to tail
Horizontal -> Side to side
Sagittal -> Front to back
```
And planes:
```
Coronal -> Separates front and back
Transversal -> Separates top and bottom
Median -> Separates left and right
```
Oh, by the way, in astronomy they use `Zenith` and `Nadir` for up and down... not of the observer, not of the observed... but as absolute orientation. You can use them to complement the cardinal directions (`North, South, East/Orient, West/Occident`).
**Note**: It is worth mentioning that some language do not have relative positions. Instead people use cardinal directions always.
[Answer]
How about you use ship orientations?
`Front...Fore
Back.....Aft
Left.....Port
Right....Starboard
Up.......Zenith
Down.....Nadir`
Or perhaps orbital orientations? These are for counterclockwise orbits:
`Front...Prograde
Back.....Retrograde
Left.....Anti-radial
Right....Radial
Up.......Normal
Down.....Anti-normal`
[Answer]
Expanding upon user535733's comment a Roll Pitch Yaw and Fire system would be far simpler. You summon an object and then you orient it with the Roll Pitch and Yaw. You can then say the trigger word or Fire word, and this will cause the projectile to launch itself in a given direction with mathematical accuracy. If you would like to increase the mystic of such a system, simply use a made up number system.
If you instead use a 6 directional you start to over complicate your system. Take for example, the direction Forward. Is it forward from the Objects default orientation? Or forward from the Mages direction? Is this direction based on the head? or the body of the mage? Or maybe there is an absolute direction that is forward?
You also greatly increase the complexity to gain flexibility. Say I want to launch it at 45 degrees instead. Would that be Forward Left? what about 22.5 degrees? Forward Forward Left? What if it wasn't any easy to each number like 20 degrees instead? A 6 directional system lacks the ability to define the direction exactly as you want and will cause issues when you might want specific angles instead of moving things in a grid like manner.
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Why do they not think in [polar coordinate](https://en.wikipedia.org/wiki/Polar_coordinate_system) system? The one moving the objects could be in the middle and then you could define any number of directions based on the dominant number system in your world (e.g. octal, hexadecimal etc.)
[](https://i.stack.imgur.com/EJgIT.png)
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Volume efficiency is extremely important when it comes to minimising the targettable cross-section of a warship in space. Humans make pretty efficient use of spaces that are generally square or rectangular in vertical cross-section. I want a legitimate argument to have starships that are in the form of trapezoid or hexagonal prisms but those shapes don't make a lot of sense for human crews, too much wasted space, so I wondered if there are creatures on Earth that *can* take full advantage of such spaces and on which an alien species could be based?
As MorrisTheCat pointed out I need to specify that these are ships with artificial gravity creating a fixed up-down orientation, otherwise the question is kind of moot as three dimensional use of the space will render its shape less important.
I have thought about wasp and bee hives but their apparently hexagonal form is actually a solution to efficiently stacking circles in 2D sheets and doesn't, to my mind, (I'm happy to be convinced otherwise) make sense in longitudinal forms.
[Answer]
**Sextually Dimorphic Spiders**
*This will cause some additional oddities in your ship design that you may or may not want, but I think it talks more to the biological element of the question you are asking.*
Female spiders are often much larger than male spiders. This means for a gender equal society of sextually dimorphic spiders to work together, the ship will need to be made to accommodate both genders, but the spaces they use will need to be at two different scales. Since spider legs have a wide profile, the males could travel safely in the narrow lower part of the tunnel to avoid being stepped on while the females walk along the walls. Small rooms will branch off at floor level, and bigger rooms will be higher up.
Technically, it still makes more sense to just make two separate tunnels, but there may be cultural factors here as well. These mixed gender tunnels may be perceived as an expression of gender inclusion that has resulted from generations of equal rights movements and failed separate but equal initiatives.
[](https://i.stack.imgur.com/6a91H.png)
[Answer]
As for biology, this may be the wrong approach to think about it. We don't make rooms rectangular because we fit in them better, we make them that way because our stuff fits in them better. As long as you have 1-directional gravity, a flat floor and ceiling connected by vertical walls will be best for storage efficiency no matter what your organism looks like.
>
> "I have thought about wasp and bee hives but their apparently
> hexagonal form is actually a solution to efficiently stacking circles
> in 2D sheets and doesn't, to my mind, (I'm happy to be convinced
> otherwise) make sense in longitudinal forms."
>
>
>
However, here you are on the right track. If the ship is filled with honeycomb shaped rooms instead of square rooms, damage from enemy weapons is more easily contained and dispersed. Instead of just thinking about the stacking strength of a bee hive, consider that those hexagons will buckle without breaking much more so than square rooms. Vertically hexagonal spaces can be filled just as efficiently with hexagonal boxes as a square room is with squares; so, there is no major loss in efficiency if you use top-down hexagonal shapes.
Horizontal hexes or trapezoids will limit space efficiency under gravity no matter how you add it up, because they impede stackability (a key aspect of storage efficiency when gravity is a factor). However, there may be given parts of the ship where a hex makes more since for the purpose it serves. For example, if it is meant to be a minimally small crawlspace, a hexagonal form may be intended to allow a little extra shoulder room while maximizing the amount of serviceable wires and conduits you can fit around it. Or you might have angled parts of the ship's exterior that are just better to fit the room's shape to than trying fit the ship to the room.
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In a post-apocalyptic novel I'm writing, I plan to follow up with a sequel wherein the main characters are trapped in a hidden city in North America called Eden that has electricity, underground trains, organized society, etc. It exists entirely underground and has existed since the start of the apocalypse. My actual story occurs about 200 years after the apocalypse (a worldwide nuclear war).
Now, I know that a lot of novels with dystopian/post-apocalyptic themes have hidden cities that remain advanced despite the events of an apocalypse, like the outside world in Divergent and District 13 in Hunger Games.
But just because it's been *done* before doesn't make it *plausible*. I want to be able to explain Eden's existence; Suzanne Collins, for example, never really explains how District 13 was able to build an underground city without any resources from the Capitol.
Therefore, I'm asking, *is* it possible, and *how* is it possible? Or should I scrap the idea before I start writing it?
[Answer]
* **They can't.**
Modern industry is so strongly interconnected that it can't exist on much less than the global scale. Your settlement probably won't make airliners or microchips, but to be self-sustaining they need a *hinterland*.
* **They were prepared.**
They are not actually a self-sustaining technological society, but they were a military or civilian bunker equipped for long-term survival. They can't *make* the spares for their power plants and subways, but they have enough for several centuries.
There might be entire levels closed for lack of spare parts ("take all the ventilation fans from section 14 and distribute them among the rest") or visible signs of lack ("lightbulb wastage has been above average for the third quarter in a row, so don't replace burned-out lights in odd-numbered sockets").
[Answer]
**Mennonite village.**
[](https://i.stack.imgur.com/rXpRl.jpg)
The Mennonites are like the Amish, but not averse to tech. The apocryphal story I heard (or maybe it was about Hutterites) was about the John Deere salesman who was enthusiastic to get an order for a big generator from the village. About a month later they asked him to come pick it up because they did not need it. When he arrived he found his generator, with another one sitting next to it that they had built. They needed his generator to see how they were made.
You could have a group of these folks - make up your own along these lines so no-one gets salty. They see it coming. They do what they need to do to make sure their people survive. On the other side, they have tech and specifically tech they can maintain: wind and water, wood fired generators etc.
This community is insular but they are Christians. When the hammer comes down they do not turn away people seeking refuge and their numbers swell. They prepared for that too.
This will add energy to your stories. It is not somehow Indianapolis transported into the future. It is a village which has survived alone because the people there planned to survive alone. They had been planning to survive alone for hundreds of years before the apocalypse.
[Answer]
In Larry Niven's [*Lucifer's Hammer*](https://en.wikipedia.org/wiki/Lucifer%27s_Hammer), one of the main characters, a rocket scientist, who is aware that a civilization ending asteroid strike is imminent, spends the last few pre-apocalypse hours gathering science and engineering books which he carefully wraps in plastic and stores at the bottom of a well.
In the aftermath, those books and the knowledge within them are enough to purchase him safety among the war lords as a would-be Merlin.
I rarely admit to being a closet prepper, but I have a similar collection of technical books and a bunch of industrial garbage bags sitting in my closet, just in case.
All you need for your story is one supporting character who was a Niven fan.
[Answer]
The entire world is already supplied with underground shelters for the apocalypse of various sizes, from the basements of urban buildings prepared as civil defense shelters in the 1950's to underground command and control bunkers in the United States, Russia, China, the UK, France and in many other nations as well.
The vast build out of these shelters during the Cold War was in principle to shelter sufficient people and equipment to allow for rebuilding after a nuclear war. Some were fairly rudimentary, for shelter during the immediate attack, like civil defense shelters in the US and the Moscow subway system. Others were fully equipped long term systems such as the NORAD defense complexes in Colorado and North Bay. There are also alleged "secret" bunkers, such as the complex supposedly dug under the Denver airport.
There are several ways this could be handled in story terms. Fully equipped and functioning bunkers already exist, but are owned and manned by military of government personnel. These people are also the best organized and equipped to deal with long term existence underground and the ability to recolonize the surface afterwards.
Many cold war bunkers were decommissioned after the Cold War ended, but since they were built to withstand nuclear attack it is impractical to dismantle them. It may be possible for civilians to have access to them, such as the "Deifenbunker" near Ottawa, Ontario, Canada, which has been restored as a museum. If the inductions that war was coming were clear and with enough advanced notice, the museum staff could possibly stock the bunker and seal the doors. It would not work as well as the fully stocked and prepared bunker in the 1950's and 60's, but would be far better than anything else. There are also people who have purchased decommissioned nuclear missile silos who would have the same intrinsic level of protection.
It is very unlikely that even the NORAD bunker in Colorado Springs would be able to be viable if sealed for a century, but then again, even an all out nuclear war would not be as damaging as you seem to think. Nuclear weapons are much smaller in power than during the height of the Cold War (yields in kilotons rather than megatons), and nuclear stockpiles have been drawn down over the years from the tens of thousands in the Cold War era as well. The heightened accuracy of delivery systems means fewer and smaller weapons are needed today.
So long as the bunkers can be sealed prior to the attack, they can survive for periods ranging from days to years, but that is all they might need. So there is no requirement for an Elon Musk to build a secret underground city: there are already hundreds of bunkers around the world built for that purpose already.
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So, for my setting, I have an idea for domesticated hominids (previously orcs). They're intellectually comparable to gorillas, weigh around the same amount (350 lbs), and can carry 15-20% their body weight (50-70 lbs). They're largely herbivorous, but will eat meat when offered, and naturally collect in packs/herds of 30-40 individuals.
I'm thinking they're mostly used as pack mules and to pull carts and rickshaws. They can be trained and used to mine, log, plow and do basic building, but with their weight and bulk, they aren't used much indoors (that's reserved for goblins!).
Any ideas / suggestions on what they could be used to do, or how to handle them? I'm still just mostly toying with the idea so I'm open to input.
**EDIT**
Females and geldings are preferred to bulls as they are more manageable and easier of temperament. The ruling matriarch of a pack usually leads the mood. If she's upset or mad, the others grow agitated, whereas if she's calm, she keeps the others in line (no one wants someone else to ruin your day).
Bulls can be agitated and aggressive, so are mostly just kept for breeding or fighting (also maybe something like matadors exist). Young males who aren't neutered will be viciously driven off by the matriarch, and if they are kept in stables, the matriarch will become increasingly aggressive and try to break their way to the males. If she reaches them, she will proceed to drive them off or maul them.
Just had a thought; seafaring peoples would love these guys. Have enough of them rowing and you save up room for more soldiers and traders.
[Answer]
**Be careful - it might seem like they are slaves.**
Sentient humanoids used like animals for their labor is pretty much slaves. If that is the kind of fiction you are writing then OK. Having slaves can give a ton of energy to a fiction. But if that is not how you want it then make a conscious effort to steer clear. Or you might have it both ways in your worlds. Nothing says "we are bad guys" like mistreating your slaves.
I think you could have them treated like elephants and do the things elephants do which is pretty much what you have. If you are cruel to an elephant it might kill you. True also of other domesticated animals but they are not as dangerous as elephants. Have the orcs be tractable and willing, but their masters (the good ones) are careful to treat them well, give them swimming time and sweet fruit, etc. A mistreated orc will decide to leave and there is not a good way to stop it.
Orcs might make poor soldiers generally because if they figure out what is up they will leave before the fighting starts, and if they are on a loud scary battlefield they will not take commands.
Orcs fight other orcs but in the way gorillas fight - to establish dominance, generally not to the death. If it is a bloodsport sort of society people might like to watch orcs fight each other and other things.
They could be heavy duty servants, like Edward the troll in Hansel and Gretel. Shoutout to Edward, last of the animatronics!
<https://en.wikipedia.org/wiki/Extraterrestrial_skies>
[](https://i.stack.imgur.com/fcxk6.jpg)
[Answer]
Consider their mobility and ability to use tools.
If you want them to behave like most domesticated animals (horses, cows, etc..), you might end up with chaos. Consider a group of cows or horses: when they're not used for work, a fence is usually enough to keep them confined. Without a fence, they would wander around, possibly causing some damage (mostly involuntarily) or at least some troubles.
Now imagine if they could climb on buildings, throw objects and use tools. That makes it a lot more chaotic.
You would have to keep them confined in a closed room / cage when not working, which could be an issue depending on how many they are and the setting they're in.
Now consider their intelligence, and how they would react to specific events. Most animals are trained through punishment and pain. How would a group of orcs react to seeing one of them being whipped / shocked / beaten? Would they turn aggressive, or run in fear? Do they understand the consequences of something, if they don't have first hand proof of it? (a human slave would know it risks to be shot if he tries to run, even if he didn't do it before. A cow wouldn't.)
As for how to keep them in check, I guess shock collars are your best bet. It grants them mobility, and allows you to incapacitate them with the push of a button. It might also include GPS, so u can find them in case one escapes.
Their ability to use tools and move with greater agility than humans, makes them very dangerous if not controlled properly.
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[Question]
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I'm trying to build a super Earth that's capable of sustaining human life for space exploration in a way that's close to reality. So far I'm lacking some understanding of planetary science and human biology.
The premise is that the planet is a young world, around 2.7 billion years old, orbiting a K star within the shorter distance from the center of the habitable zone. It has shallow seas/lakes with a rusty green color, although the greenish hue of the color is slowly disappearing due higher concentrations of oxygen as time passes by. (This was inspired by reading research articles that suggest Earth's oceans were green with iron deposits before the great oxygenation event.)
Planet radius: 1.4
Planet mass: 2 Earths
Atmospheric composition: Nitrogen: 69%, Argon 0.82%, Oxygen 30%. Due to the higher concentration of oxygen, there are lots of negative consequences affecting the planet, such as more volcanic activity, massive forest burning, metal rusting faster, food spoiling quicker than Earth, constant rainfalls, and possible massive violent storms.
The temperature: It varies. The highest temperature I've recorded is 61°C (141°F) and the and the lowest ever measured was 10°C (50°F). The average temperature for the most part of the planet is 37°C (98°F).
Surface Gravity: I'm not sure what kind of gravity I should put. As far as I know, Earth's gravity is 9.8 m/s² (1g) but, since the planet has larger mass, the gravity characteristics differ from Earth, therefore, I'm clueless to calculate this.
Geology: Homogeneous mix of lands (smaller continents) and water that connects to different large or tiny landmasses. Instead of a large ocean, it has numerous water bodies with lots of inlets, bays, lagoons, and isthmuses. The topography is slightly flatter than on Earth.
Land coverage: 55% water and 45% land.
Orbital period and rotation: Another thing I'm at a loss for. I'm afraid I'm terrible at mathematical planetary motion but I wanted the planet to have 447 days (1.22 solar year).
Climate: Tropical.
Flora: Possibly a mega flora with wetlands, tall mangroves, and a rain forest.
My question would be, given everything that I listed, is possible human life could thrive on this planet? If so, what are the positive or negative side effects for humans to live there? Do humans suffer different gravity, atmosphere, weather effects? Would the inhabitants undergo disorder moods like seasonal affective disorder, since it has different lengths of days?
I figured since it has a higher concentration of oxygen, humans would perform better in endurance but I also read that with too much oxygen, long-term effects include oxygen toxicity and problems with metabolism and aging cells.
Correct me if I'm wrong in any those lists I've mentioned.
[Answer]
You really do have a lot going on in your question and splitting it into multiple threads is going to get you the best specific answers. That said taking your main question of "could human life thrive?". The short answer is yes.
The long answer is based on physics and the constraints you have listed you are going to end up with a world quite similar to earth in the grand scheme of things. All of the calculations that follow are rough estimates but in general should be close enough for use in a science based story.
Difference in gravity can be roughly calculated as mass of planet divided by radius of planet squared. Your listed mass is twice earth with a radius of 1.4 earth. 1.4 squared is 1.96. This lets us know that gravity on your planet will be about 102% of that on Earth.
The next thing to talk about is orbital period/distance. A quick and dirty calculation for this is that the square root of the orbital distance cubed gives you orbital period in comparison to earth. Obviously there is some flexibility to this, but it gets us close. Now you list the orbital period as 1.22 earth years so we can work this backwards. 1.22 squared is 1.488. the cubic root of that is 1.13 which means your planet orbits at roughly 1.13 AU, or about 13% further out than earth.
The habitable zone around a K type star ranges from 0.1 to 1.3 depending on the size of the star itself. So your planet checks out as being plausible. That said your temperature listings are a bit higher than earth so you are going to need a rather large K star or alternatively to shorten your orbital period so your planet can be closer to it's star, or assume a higher mix of heat trapping gases in the atmosphere.
You specifically call out the oxygen levels as being higher than earth currently, but they are not higher than what the earth has seen. Findings have show that between roughly 350 and 300 million years ago the oxygen level in the atmosphere was roughly 30-35%. So again your levels are reasonable on an earth like planet. Oxygen toxicity doesn't really become an issue until you start looking at high concentrations of oxygen at high atmospheric pressures. At a normal atmospheric pressure oxygen toxicity doesn't become an issue for humans until about 50% oxygen levels. On average even at 95% oxygen at 1 atmosphere a human averages 14 hours before showing signs of oxygen toxicity, which can be easily reversed by a low oxygen environment at this point. So clearly, you are a ways off from the atmosphere causing immediate harm. That said there could be some long term cell degradation at a 30% level but it isn't anything that is likely to keep a sustainable human population from being viable.
As far as rotational period of the planet that has far more to do with random chance, which direction did big objects impact the planet, than anything that is consistent across planets in general. So you can pretty much pick any rotational period, and thus day length you desire for your story.
Overall you have created an extremely earth like planet, with some room to play with the edges to make it a little more or less so. The way it appears now though the Flora and fauna, and it's aggressiveness/hostility towards humans is likely to have a far more meaningful impact on a colony surviving than the actual physical set up of the planet system.
[Answer]
As Crouse mentioned, the planetary diameter you listed means this world is not very dense at all. This would mean that it's severely lacking in heavier elements and will be very metal poor, significantly curtailing the speed with which a technological civilization can grow (unless they've moved on from steel to bulk carbon alotrope manufacture and can make large quantities of graphene, carbon nanotubes, synthetic diamondoids, etc.). This planet would have like that evolved under basically the same constraints as on Earth.
The problem is that volume grows with the cube of the radius. Assuming the same density as Earth, planet with two times the mass would have a radius of 6370 km (assuming a perfectly spherical planet, which won't be the case, by way of comparison, Earth radius ranges from 6378 km at the equator to 6357 at the poles, so this planet would be about the same size as Earth). This planet would however have a gravity that of 2G's: 19.62 m/s^2. (By comparison, a roller-coaster probably won't go much above 1.6 Gs, imagine living under that strain all the time)
I'm going to go forwards assuming that 2G surface gravity variant, and point out a few things about high gravity worlds:
1. Due to the dense atmosphere, your flying creatures can actually be bigger than on Earth. While the gravity is higher, meaning they need more force to keep them aloft, lift increases with atmospheric density faster than it drops off with the increase in gravity. So counter-intuitively, bigger bird analogues.
2. There seems to be a truism that flora and fauna on high G worlds is short and stocky, but people usually think this is for structural support reasons, which isn't the case. Stocky creatures have more mass that has to be held up, which means stronger support structures which means more mass, and thus a vicious cycle is born. You can keep lower to he ground, but you give up the advantages of a higher vantage point. It seems likelier that evolution would favor creatures that are lithe - with weight saving adaptations like hollow bones being common, and high density muscle that can apply a lot of leverage for minimal mass. That and creatures are likely to be smaller than the Earth average, to take advantage of the square cube law. Because objects fall faster, animals might also have faster reaction times. The bigger issue is fluids - an organism that is oriented flat to the ground has less of a pressure gradient that the heart has to struggle with, that's the read driver for shortness in high gravity environments.
3. High atmospheric pressures and oxygen content mean that simpler lung structures can be used, which means you can have giant insects and arthropods. Novel gas exchange mechanisms such as frog like skin breathing might also be more common.
4. Higher atmospheric density means that the planet will probably be warmer than Earth, with winds exerting more force for a given windspeed. There is also likely less temperature variation from the poles to the equator. As the strength of storms is driven by temperature difference, this means that to overcome the greater uniformity of the thick atmosphere and get large temperature differences, the planet will have to rotate slower, with longer day and night cycles creating hotter noons and colder midnights.
5. Flora will likely be more limited in height than on Earth both due to wind loading and the greater energy expenditure of transporting nutrients up the trunk. It will likely grow faster due to having an easier time absorbing CO2 and O2 from the denser atmosphere, much like how plants placed in high pressure environments seem to grow faster on Earth. Trunks might be surrounded by scaffold like branches that add rigidity while reducing wind loading.
How will this affect human colonists? Well, you talked about them being more disease prone due to higher O2 concentration, so that's a thing. The different day/night cycle will also have adverse health effects over the long run, reducing lifespan much like how night shift have been proven to be terrible for one's health.
Arthritis would likely be endemic due to the higher gravity if nothing was done, so people will likely use some sort of load bearing wearing exoskeleton - through not necessarily a powered one, that that would be very useful indeed. These conditions will also retard growth, as seen in experiments where mice were placed in a 4G environment, the extra energy demands means slower growth of all organs.
Heart issues will also be endemic even with technological aid, and people will likely be forced to wear compression suits similar to those worn by fighter pilots. Motorized scooters that let people lie back would likely be very common to help reduce the issue. Pregnancy would also be very risky, so exo-woumbs might be popular.
2Gs is really at the edge of what un-augmented humans can deal with.
[Answer]
There are already some good answers here, but I do want to pick up on one thing about your atmospheric composition; lack of density figures.
When it comes to things like oxygen deprivation (not enough) and oxygen toxicity (too much) the difference is not in the percentage of oxygen, but rather in the partial pressure. That means, that in order to know whether that percentage of oxygen is dangerous or not, we need to know what the pressure is in the first instance.
For example; the Apollo astronauts flew to the moon in a pure oxygen environment, because their capsule was only pressurised to below 0.3 ATM, meaning that the partial pressure of oxygen was still only 0.3 atmospheres (ATM), which is a bit more than the volume of oxygen in normal air at sea level. On the other hand, deep sea divers often dive with argon-thinned air mixes, so that at pressure when they breathe in more air, the *volume* of oxygen is the same as it would be at sea level.
It is also important to note that you can't just say that double the mass of the Earth will result in double the pressure of atmosphere; the difference between Venus and Earth is a prime example of this. The pressure is also impacted by heat, meaning that Venus and its runaway greenhouse effect creates a massively hot, high pressure environment.
Put simply, depending on what your starting atmospheric pressure is, your air mixture could already be too high for humans to breathe safely for any length of time.
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[Question]
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Is it possible to dye leather/cloth with blood without it fading, perhaps by using a sealant of some-kind?
Note: This would be in an apocalyptic world where advanced chemical compounds would have long expired.
[Answer]
Fresh blood has a bright red color, so if you would dip a cloth in fresh blood, it would get the same bright red color.
But then, as the enzymes and proteins present in the blood would start interacting with oxygen, it would turn to a brownish tint.
Anyway, this is what can be found [online](http://www.pburch.net/dyeing/dyeblog/C417788512/E20081020125227/index.html):
>
> What you want to do is basically the opposite of what one is supposed to do for blood stains that you want to wash out. You should cook the blood into the fabric, and then let it age for some time.
>
>
> Heat will denature protein. The denatured protein loses its shape and tangles around the other molecules of denatured protein. A good way to apply the heat would be to spread the fabric out, as much as possible, and bake it. Perhaps you could air-dry the blood on the fabric, then wrap the fabric around layers of crumpled unprinted newsprint paper, to allow air between the layers, and bake it in the oven, on a very low heat, for several hours.
>
>
> I would advise you to not wash the fabric any more than you have to. Blood cannot be used as a true dye, but it can stain the fabric very effectively. Repeated washing will cause it to fade and gradually wash out, however. Rinse no more than you need to to get the artwork to look the way you want it to.
>
>
> It is traditional in Japan to use freshly made soymilk as the binder for hand-painted earth oxides on fabric. The soymilk, of course, like blood, contains mostly protein. (Blood also contains some iron.) Treating your blood like the soymilk in the iron oxide painting recipes would probably be a good idea. Do NOT wash the fabric for several months, if possible. The longer the soymilk ages, the more permanent and washable the fabric designs become, though it should never be machine-washed or used for clothing that must be washed frequently; the same might be true of blood, as well.
>
>
>
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[Question]
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Does anyone know of any compound/substance one could have access to in a stone prison cell (From food? The rocks? The metal bars?) that could be processed through rudimentary means into a quick acting poison/venom?
Prerequisites:
* That it can quickly (within the hour) start showing effects (whether ingested or applied into a wound).
* Can't be made through means unavailable to an ordinary person inside a prison cell.
* It can be something that doesn't cause death but instead leaves the person heavily impaired (Paralysis, loss of consciousness, stroke-like symptoms...).
* Time is not a problem, production can take up to a month, and it only needs to be a single dose.
* It has to be a small dose.
* Can be extracted from food, but can't come from "specific herbs", the character is imprisoned and as such can't go out to look for specific plants/minerals.
In the story I'm writing, the protagonist finds themselves locked up and enslaved in a medieval prison/castle. Though there is magic in the setting it is not available to him.
My current idea was that he gathers apple/apricot seeds and crush them to make a cyanide-based poison, but by the looks of it there's no way to make it concentrated enough for it to be a relatively small dose.
[Answer]
### Ricin
Ricin is found naturally in castor beans, a common plant (in various parts of the world), and extremely fatal in tiny doses. In fact, [the CDC has a bioterrosim page dedicated to it](https://emergency.cdc.gov/agent/ricin/facts.asp)
Castor beans may be used in different types of foods and/or natural remedies. Depending on the timeline and location of your story, as well as other details (such as whether or not the prisoner is forced to work in the kitchen, where s/he may have access to raw castor beans) makes this a viable option.
Although onset is a few hours, ricin is extremely fatal, there is no known cure, and has been used by real-world assassins.
### Botulism
Improperly canned foods can cause [botulism](https://en.wikipedia.org/wiki/Botulism) - it would be rather easy for a prisoner with access to raw foods to prepare / hide the foods until they rot and the bacteria develops. Getting it on/in a guard without them noticing will be more difficult. Although possibly fatal, it's rare, but very debilitating.
[Answer]
**Fungus**
Being in a prison is quite possibly unsavory. Quite a few [fungi are poisonous](https://www.planetdeadly.com/nature/poisonous-mushrooms) and could be growing in moldering hay on the floor of the cell
There are also [lichens](http://blogs.discovermagazine.com/notrocketscience/2012/03/26/the-surprisingly-toxic-world-of-lichens/#.XJGGRCgzarw) that are poisonous which could be growing on the walls.
[Answer]
**Spider bite.**
I knew the [Australian funnel-web spiders](https://en.wikipedia.org/wiki/Australian_funnel-web_spider) were bad, but I did not know that their venom acted so fast!
>
> Envenomation symptoms observed following bites by these spiders are
> very similar. The bite is initially very painful, due to the size of
> the fangs penetrating the skin.
>
>
> Early symptoms of systemic envenomation include goose bumps, sweating,
> tingling around the mouth and tongue, twitching (initially facial and
> intercostal), salivation, watery eyes, elevated heart rate, and
> elevated blood pressure. As systemic envenomation progresses, symptoms
> include nausea, vomiting, shortness of breath (caused by airway
> obstruction), agitation, confusion, writhing, grimacing, muscle
> spasms, pulmonary oedema (of neurogenic or hypertensive origin),
> metabolic acidosis, and extreme hypertension. The final stages of
> severe envenomation include dilation of the pupils (often fixed),
> uncontrolled generalised muscle twitching, unconsciousness, elevated
> intracranial pressure, and death. Death generally is a result of
> progressive hypotension or possibly elevated intracranial pressure
> consequent on cerebral oedema
>
>
> The onset of severe envenomation can be rapid. In one prospective
> study, the median time to onset of envenomation was 28 minutes, with
> only two cases having onset after 2 hours (both had pressure
> immobilisation bandages applied).
>
>
>
Funnel web males apparently wander around certain times of the year, looking for mates. That is how they run afoul of humans. In your world there is a similar spider (or some other small invertebrate - scorpion might be good) and these things turn up in the prisoner's cell from time to time. Your prisoner knows what they are and after killing a couple, decides to keep one as a pet, feeding it lice from his own body. When the target shows up he surreptitiously flips the creature onto him. The spider seeks refuge in the target's clothes and bites him a minute or two later.
This seems to me more plausible than some ingested poison. If I am an occasional visitor I am not going to have a prisoner make me an omelette or give me a tattoo. I might come close enough to get a spider flicked on me.
If these things live in the prison the guards will probably know what is going on when the target starts gets sick. But an aristocratic target might not deign to tell lowly guards he is feeling poorly, and instead consult with his own entourage or wait to get help from a healer appropriate for his class and station. That would make good narrative, as one of the guards suspects the target has been bitten but then is ignored / dismissed.
[Answer]
# [St. Anthony's Fire](https://en.wikipedia.org/wiki/Ergot)
A fungus also known as ergot, found on rye grains and in rye bread containing a natural [LSD](https://en.wikipedia.org/wiki/Lysergic_acid_diethylamide) substance.
>
> The [convulsive symptoms](https://en.wikipedia.org/wiki/Ergotism) from ergot-tainted rye may have been the
> source of accusations of bewitchment that spurred the Salem witch
> trials.
>
>
>
Thought to have inspired the Triptych of the Temptation of St. Anthony, this is the detail of Saint Anthony being carried into the sky by demons:
[](https://i.stack.imgur.com/NzwUp.jpg)
*Hieronymus Bosch - Wikipedia 2019, CCASA [Licence](https://en.wikipedia.org/wiki/Wikipedia:Text_of_Creative_Commons_Attribution-ShareAlike_3.0_Unported_License).*
>
> characterized by muscle spasms, fever and hallucinations and the
> victims may appear dazed, be unable to speak, become manic, or have
> other forms of paralysis or tremors, and suffer from hallucinations
> and other distorted perceptions.... violent burning, peripheral
> pulses and shooting pain of the poorly vascularized distal organs,
> such as the fingers and toes...
>
>
>
If the poisoning continues long term then gangrene of the limbs and death will result.
[Answer]
Leave your food for a month alone. It will either rot or develop a fungus. You dry the fungus and mill it.
If it will rot you just save the "juice" and use as a poison.
In both cases you need to create concentrate for it to start acting quickly.
If your prisoner get feed apples he can create cyanide form apple seeds. Downside to this is that 80kg person need to consume 250 mg of cyanide to show symptoms as you described. That equal roughly to 6000 apple seeds. Apple can have max 20 seeds in one. So In the best scenario he would need 300 apples to create enough cyanide to poison certain person (with death as a possible outcome if he get the weight wrong).
There is not much to "get" from prison in your given time bracket. Botulism need at least 12 hours to develop. Regular food poisonings (salmonella, rare meat etc) need 24.
anything that is widely available is not poisonous because if it's occurrence in the world is common people have natural immune to them. As you build immunology to certain poisons by taking small doses of it.
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[Question]
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In a comment to a recent question, it was pointed out that [Biosphere II](http://biology.kenyon.edu/slonc/bio3/2000projects/carroll_d_walker_e/whatwentwrong.html) failed in part because too much CO2 was absorbed by the concrete, leaving insufficient oxygen in available CO2 to be released by plants in photosynthesis.
We know that one of the ways scientists and engineers are hypothesizing to reduce CO2 levels, in order to reduce the effects of global warming, is to investigate carbon capture systems, wherein CO2 is captured in, say, calcium carbonate and then buried.
This evoked in me an interesting story line and plot device.
It's about the Law of Unintended Consequences.
**Is it feasible to capture so much CO2 on earth and make it permanently unavailable to photosynthesis, that the levels of oxygen in our atmosphere fall to levels that can no longer sustain life on earth?**
This is NOT about HOW this capture is done, or even if it is doable. It's about, theoretically, given the current amount of CO2 that needs to be captured to reduce global warming, and the future ongoing rate of production and release of CO2 through the burning of fossil fuels, respiration, farting, and so on, if humans captured enough CO2 (and unintentionally made it unavailable to photosynthesis) to reverse global warming, would so much oxygen be captured that there is not enough left to sustain life?
In other words, is it feasible that we could unintentionally substitute one extinction event while trying to prevent another?
**EDIT**
Some useful data that I have researched is:
Oxygen levels today 20.9%
Minimum oxygen levels for proper human functioning without adverse effects 19.5%
Oxygen levels have been dropping as CO2 levels are increasing, hypothesized to be in part from oxygen used in combustion
Any oxygen removed by 'sinking' CO2 is no longer available to replenish this depleted oxygen through photosynthesis - a double whammy - oxygen used up in combustion and not replaced by photosynthesis.
Closest figure I have for projected oxygen depletion WITHOUT CO2 sinking is a drop to 20.8 by the end of the century.
I have not found any research that gives a figure that says how LOW CO2 levels have to fall to REVERSE global warming (i.e., is it below the C3 plant compensation point?).
But I have not found any research that ties it all together in a future projection. The closest is [this](https://www.sciencedirect.com/science/article/pii/S209592731830375X#f0025)
[Answer]
The photosynthesis would cease only as a secondary consequence.
CO2 plays an important part in the modern climate. [link](https://www.skepticalscience.com/co2-free-atmosphere.htm)
>
> 75% of the greenhouse effect is caused by water vapor and clouds, which rain out of the atmosphere if it cools. This makes water vapor a strong positive feedback to any change in non-condensing greenhouse gases. CO2 constitutes 80% of the non-condensing greenhouse gas forcing. Removing CO2 would remove most of the water, cancelling most of the greenhouse effect and cooling the Earth by 30 C.
>
>
>
This temperature drop would kill most of the flora and fauna first. Mostly because they are not used to this temperature, but also, because photosynthesis efficiency [drops](https://sciencing.com/effect-temperature-rate-photosynthesis-19595.html):
>
> At low temperatures, between 32 and 50 degrees Fahrenheit – 0 and 10 degrees Celsius – the enzymes that carry out photosynthesis do not work efficiently, and this decreases the photosynthetic rate.
>
>
>
Some would likely survive, as there are plants living on the [poles](https://beyondpenguins.ehe.osu.edu/issue/polar-plants/plants-of-the-arctic-and-antarctic), but i doubt they would be able to maintain the O2 level. But the O2 level would be highly unlikely to fall, as most of the life was killed by the temperature drop.
Also see this [xkcd graphic](https://xkcd.com/1732/), and this [NASA article](https://climate.nasa.gov/climate_resources/24/graphic-the-relentless-rise-of-carbon-dioxide/), showing that the CO2 concentration in the atmosphere never went under c.a. 180ppm.
Edit: I just found [this](https://biology.stackexchange.com/questions/29943/whats-the-or-some-of-the-minimums-amount-of-atmospheric-carbon-dioxide-need) on biology stackexchange:
>
> That being said, the answer depends on other concept: CO2 compensation point. For a C3 plant, carbon dioxide compensation point is around 50ppm (Tolbert, Benker and Beck, 1995).
>
>
> Thus, we can say that, as a rough estimate, the value you want lies between 50ppm and 170ppm (probably closer to 170ppm than to 50ppm).
>
>
>
(Extra: the plant cells have a [respiration](https://en.wikipedia.org/wiki/Compensation_point))
This would mean, if you instantly lowered the CO2 concentration under this point (and kept the temperature normal), the plants would slowly suffocate during the day. Probably they would produce some CO2 until they die, but probably this rate would not be enough to raise the CO2 level to the minimum for most of the plants.
Yes, this would lead to an extinction event (the species which have higher compensation points would be effected the most), also in the case if you do not consider the temperature drop.
[Answer]
This is a very good point to consider. The concrete absorbed CO2, which prevented the plants from using it in order to produce sugars and release oxygen back into the atmosphere. So, if CO2 is captured by some industrial process, and never released again, plant growth is stunted, and the animals will have to compete over a smaller share of plant food. First, the normal biomass will diminish as more carbont is sucked-out the system and less oxygen will find its way **back** into the atmosphere.
Humans [response to suffocation](https://en.m.wikipedia.org/wiki/Control_of_ventilation) is triggered by high CO2 and not low oxygen. This has caused the participants in the experiment to behave strangely, to our standards.
Even if the concrete was replaced with a more inert material, there is another problem: Volume of air. Our atmospheric mass is huge, so that biogenic factors, like breathing, raises CO2 very slowly. This allows plants to grow, absorb more CO2 and eventually catch-up with the pace of rising CO2. A few miles-high column of air above an earth-sized planet, is not the same as an aquarium loaded with plants and animals.
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[Question]
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I'm creating a new setting for a novel. I'd like to build a world where the interaction between the planet and its satellite/satellites can generate a normal tide excursion around 6/8 metres. Furthermore I need that once every 500 years there occurs a low tide ten/twenty times that of the normal ones.
Can anyone suggest to me how to set up this relationship to be at least credible?
I'm thinking of a system with a central planet with 2 satellites, where the nearest is smaller and orbits faster, and a second one is bigger and farther away with a really slow orbit with a very elliptical path, but I don't know if this solution can work.
P.S.: Obviously the number is merely indicative only for give you an idea of how this thing should work.
[Answer]
Tides are nothing but waves on the ocean, which are driven by the moon's and sun's gravitation. And, as with any wave, absolute hight depends *heavily* on resonances.
A commenter has already given the location on earth with the highest tides, which is a *bay* (<https://en.wikipedia.org/wiki/Bay_of_Fundy>). I.e. a half enclosed region of just the right size to produce such a strong resonance that you get 16m high tides. Most of the remaining water surfaces are not as highly resonant with the fixed frequency of gravity change, so you only get small tides that mostly don't exceed 1m.
So, you have two routes to go:
1. You heavily increase the tidal forces. I.e. bigger moon that's closer by.
2. You heavily increase the resonances. If you have a shoreline that's for some weird reason a sequence of bays like the Bay of Fundy, you get the high tides in each of those bays. You'll also get low tides at the coasts that are directly facing the open ocean.
If you go this route, you can use bays of virtually any size, as long as you adjust the length of the day accordingly. The larger the bays, the longer the day needs to be.
In either case, be aware though that those large tides won't last for long (= long in the geographical sense): The higher the tides, the faster the energy transfer from the earth's rotation to the moon's orbit and water heat content. So, the higher the tides, the faster the earth's rotation looses speed. And as your days get longer (very gradually, but I'm speaking about geological timespans here), the bays will get out of resonance and loose their high-tide property.
[Answer]
**This has probably already happened to the Earth.**
It is generally believed that the moon was formed from an impact event between a very young earth and a planet around the same size as Mars. In point of fact, it has been postulated that the young moon was responsible for the [creation of life](https://www.newscientist.com/article/dn4786-no-moon-no-life-on-earth-suggests-theory/) on earth, and that when it was newly formed from the debris ring around the earth, it was much closer to the earth, orbiting the earth every 6 hours or so and causing a massive tidal effect.
Ultimately, the closer you bring the moon to the Earth and the closer in relative size they are, the larger your tidal forces. The sun is also a factor though, so if you move the earth even slightly closer to the sun, and have a moon up close, you can end up with massive king tides as a result of alignment between sun and moon.
Mind you, the closer you put the Earth to the sun, the less time the earth will be in a habitable range (the sun is slowly heating up and in billions of years, Mars will actually be in the goldilocks zone, not earth) and having the moon closer, while potentially necessary for the *establishment* of life, may make the earth far less comfortable for the *sustainment* of life depending on what you're trying to achieve.
If the only thing you care about are tidal forces, then these configurations will help you. If you want this planet to harbour life to the point of intelligence, it may be a little more problematic. In any event, just move your moon closer to the earth and you get reasonable tidal variations quite quickly. You don't even have to move it much to have a great effect because of the squared effect of proximity on gravitational pull.
In other words, move it to half its current distance from the Earth, and your tidal forces quadruple. Move it to around a third of the current distance, and you have nearly 10 times the tidal forces in play. Of course, in both cases, your tides move much faster between high and low tides (unless you greatly slow down the rotation of the earth) so the impact on life is going to be greater than simple difference in tide height; you're generating a massive amount of momentum as well which brings its own problems that will have to be dealt with by life struggling to survive on the surface.
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**Horseshoe Orbits**
Yes, long term (geological timescales) stability will be an issue with this setup but it should be the setup that most closely matches your criteria.
Start with Earth's horseshoe orbit relationship with [Cruithne](https://en.wikipedia.org/wiki/3753_Cruithne), which is on about a 770 year cycle. This concept is easily modified to more closely match your 500 time requirement. From there, replace Cruithne with your tide "planet" and replace Earth with a large Gas Giant planet. When the Gas Giant approaches your tide planet, once every 500 years or so, the tides get huge for a significant time (probably several years, though I don't know how to do the math on it), before the tide planet and gas giant separate again for the next 500 years.
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In my world the resident humanoids evolve from beaver sized aquatic axolotls.The only land on the planet can be considered mountainous terrain. Imagine a volcanic crater where only the rim surfaces. Eventually after thousands of years of living in colonies of floating seaweed huts they begin moving onto land (while retaining the ability to live underwater essentially becoming amphibeans). For reference this is what an axolotl looks like-
[](https://i.stack.imgur.com/hNJTu.jpg)
Why would a creature like this evolve to walk bipedally on land after thousands of years of the species living solely aquatically?
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Axolotl are an interesting choice because they have a very *weird* evolutionary history. Axolotl are actually evolved from more land-living amphibious salamanders by [neotony](https://en.wikipedia.org/wiki/Axolotl#Neoteny), that is they evolved by the immature - and purely aquatic stage - of an amphibious organism becoming sexually mature. For an axolotl to become amphibious is therefore very easy, it's actually possible to artificially induce metamorphosis to a salamander like state and thus the pathways necessary still exist and just need the right conditions to favour them for evolution to do the rest.
The rest of it is not that dissimilar to real evolutionary history, which is far too long and complicated to do justice to in a single Stack Exchange answer, but in super-duper tldr; mode: first you need to evolve to be properly land-living: i.e. evolve proper lungs, skin that can cope with being dry, and eggs that can be laid on land. Then you need to evolve proper quadrupedal stance, so the legs are orientated under the body, rather than to the side as in most lizards and amphibians. Finally, you need a situation which favour bipedalism. It's not really clear what exactly this is: it's evolved in various dinosaurs (including birds), kangaroos, and humans.
Incidentally, beaver-sized Axolotl are likely not biologically plausible due to the requirements for respiration which since the surface area of their skin and gills increase with the square of their size, won't scale sufficiently to match their increase in volume.
Also, thousands of years is super-duper ultra-quick in evolutionary terms: whilst significant change can occur on these timescales during adaptive radiations, it's far more credible for the kind of changes you discuss to take place over tens, or hundreds, of *millions* of years.
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Let's review the long-standing and dominant theory on why some monkeys started walking to become what we are today.
Climate change was a key driver of the process. Several million years ago, Africa began to lose some of its forests as vast grasslands grew, so our ancestors gradually left their ancestral forests and moved out onto the savannahs.
Bipedalism made more sense in an environment where trees were rare.
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In your world you could say that climate change led to floating seaweed to disappear. Your axolotls were forced to move on the land. The majority of land in their region was savannah so they start walking upright and then from there on they follow the same pattern as monkeys -> human.
Standing upright frees the hands which can be used to manipulate tools. This increases the brain size and they become smarter, discover fire, agriculture etc... .
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Food
There wasn't enough food in the water for your Axolotl to survive off. The ones who managed to scavenge food off of the land had a higher chance of surviving and their adaptation to living in both land and water allowed them to get a small edge on the other Axolotl. However since they didn't have the usual defense mechanisms of land creatures, they would always retreat into the water for safety. So the ones that could go on both land and water had a higher chance of surviving and passing their genes on.
Seasons
There are dry and wet seasons. In the dry season, the water disappears (look at mud skippers for this) and he Axolotl had to migrate to a new and larger body of water. They have to move above ground and those best suited survived the journey. The better suited ones were able to claim new homes with plenty of food before the rest and so were able to pass on their genes as they had a higher survival rate.
Lack of Oxygen(?)
A stretch, but maybe they needed slightly more oxygen than other sea life and had to consume air and water to better survive. Those that became more suited at a mixture of both survived and as a result they can survive for extended periods of time outside of water but need to remain moist to help aid they breathing system.
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Suppose I take a group of alligators select the ones that emit the highest frequency of radiation (since all living creatures emit thermal radiation), and I breed those, and get rid of the rest and continue this for thousands of generations. Is it possible, that at one point the frequency of that radiation becomes high enough to enter the visible light spectrum?
My theory is that, since the criteria we have selected for the selective breeding is high frequency radiation, a point should come where the radiation becomes high enough for us to see, because after all, it is the body that is creating the energy, which depends on the genes of the alligators.
And if it is possible, could we exceed the visible light spectrum? Maybe reach a point where the alligators start emitting X-Rays or Gamma Rays? And do you think the alligators, as creatures, would completely change in order to keep up with the selective breeding system?
**EDIT:**
After seeing the answer's I've got, I remembered that alligators are cold-blooded, so would this work for warm blooded animals like monkeys, or any animal if possible?
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In order for a body to emit visible light as a result of black body radiation, that body has to be heated up to close to 620 degrees Celsius, or 1160 Fahrenheit. Think of light bulbs.
Your gators can only reach that temperature with human intervention involving fuel, and they won't be alive for most of the time they are that hot.
Fireflies emit visible light not through black body radiation, but as a result of luciferin reacting with luciferase in their bodies. It could take hundreds of millions of years for alligators to accumulate enough random mutations for that, but you could speed up the process with genetic engineering.
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No, it doesn't work that way.
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Black body radiation is emitted by anything above the temperature of 0 K. Alligators, being cold blooded animals, are just at the same temperature of their environment. There is no thing such a hotter or colder alligator, you would basically pick some based on the local environmental temperature (i.e. sunlight or shade).
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> Is it possible, that at one point the frequency of that radiation becomes high enough to enter the visible light spectrum? Could we exceed the visible light spectrum? Maybe reach a point where the alligators start emitting X-Rays or Gamma Rays?
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Different wavelengths are emitted as a consequence of different transitions.
Low frequency electromagnetic radiations are emitted by electron oscillations, while visible light up to X ray is emitted by electronic transitions within atoms. Gamma rays are emitted by transitions within the atomic nucleus.
Moreover, radiation with energy comparable to UV and above is dangerous for living being, as it usually damages the organic molecules.
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No. Not in the way you are suggesting, and not to the frequencies and power that you are dreaming of.
However... you could go around your problem and have a symbiotic relationship with some light emitting animal (e.g. a firefly), or bioluminescent fungus, or bacterium (as in the case of a [certain squid](https://en.wikipedia.org/wiki/Firefly_squid)).
You would "only" need to create a selective pressure for the two organisms to cooperate. In the case of the squid, the cephalopod needs to camouflage by imitating the brightness of the sea surface, and the bacteria are just happy to be carried around. In the case of your alligator, the light could attract some nocturnal preys, or camouflage the alligator during full-moons. The bioluminescent animals could benefit from cleaning the dirty teeth of the alligator, or cleanse its skin from parasites and ticks, or simply enjoy being carried around for the sake of it.
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An [astrophysical jet](https://en.wikipedia.org/wiki/Astrophysical_jet#Relativistic_jet) is a stream of particles emitted by matter falling into an supermassive star/black hole, travelling at up to 80% the speed of light.
A troll with a portal gun (which places portals instantly) wants to have his house floating above the ground (with his garden) just by using a small part of a jet.
Is this possible? (Probably not)
What issue would come up? Which other unreal technologies would be needed to solve the issues and make this possible?
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A big old beam that might be made up of equal amounts of electrons and positrons? Sounds like a job for Ludicrous Magnets inc.!
This answer makes a series of assumptions:
1: The beam is composed of electrons and positrons in equal proportions with no stray nuclei in there. This is Important.
2: You have some whopping great electromagnets and sturdy enough foundations/structures to mount them on.
3: You have a lot of vertical space to play with.
4: You’re in a vacuum. Seriously: who thinks firing a beam of relativistically fast matter into an atmosphere is sane??
5: Your control systems are insane.
So. If you have those 5 things you can begin.
First you have to build a magnetic field generator such that the portal fires the stream up through practically parallel field lines. As it does so the beam will diverge, as positrons and electrons are deflected exactly oppositely in a magnetic field. This magnetic field generator must be mounted to the main island in such a way that it does not intersect any part of the beam, or Fiery Death will ensue.
Second, way above the first magnetic array (exactly how high depends on how strong your magnets are and how powerful your jet is) you have your island. Attached to the island are two ‘intake ports’. One accepts a positron beam, the other an electron beam. If you position things right then the jets will seperate neatly into two beams that shoot directly into these ports. If you don’t then Fiery Death will ensue.
Thirdly: you have a series of very long, very complicated curves lined with electromagnets. As you have a beam of known magnetic properties and (hopefully) known velocity/energy you should be able to curve these beams round in some (admittedly huge) part circles, emitting beams at various locations in order to keep your island balanced and in place. If your control software isn’t capable of separating the beams appropriately Fiery Death will ensue.
Now, at this point you might be thinking ‘huh, that sounds an awful lot like CERN’. You would be correct. The size of the curves may well be obscene (unless you have some *truly* ludicrous magnets), but it is possible to bend the beams. In so doing you transfer momentum from the beams to the station.
If you can bend the beams around enough (and your station isn’t too heavy, which is again a big assumption) then you can hypothetically balance the force of gravity against the upward pressure of the beams, letting you balance your hermetically sealed house/garden atop the monstrous beam-deflecting complex you have created. If your station is too heavy then... you get the drift.
Now: there are a number of ways this can fail *spectacularly*
1: Control software failure. Your station drifts out of alignment and is bisected by the jet. Fiery Death.
2: Unexpected velocities of particles. Given the weird nature of these phenomena I’m imagining all the particles involved are moving at a set of velocities you know. If they don’t then parts of the beam will hit elsewhere on your station. Fiery Death.
3: Unexpected particle ratios. Much like above, but with an unexpected ratio of positrons to electrons. Fiery Death.
4: Unexpected nuclei. Your magnets, if calibrated for an electron stream, will not handle nuclei. They will impact your station like a stream of baseballs thrown by an angry god. Fiery Death.
5: Power Problems: I dread to think what kind of power requirements this will have. I’d say astronomical, but the pun might kill me. Anyway: any fluctuation in power supply: Fiery Death.
6: Anything else intersecting any of your beams. This includes the floor. The stream of plasma will interact Very Badly with matter, releasing bursts of awful radiation and debris that will hit your station. FIERY. DEATH.
7: Structural Failure. The forces you’ll be dealing with are ungodly. Any weakness in the structure will result in your magnets (and the beam of plasma. Don’t forget the beam of plasma) crushing your station. Crunchy, Fiery Death.
8: ADDENDUM DEATH: Overheating. You’d better have superconductors available, because any inefficient in power delivery or magnetic field design will translate to a lot of heat. AKA Fiery Death.
Anyway. If you avoid all that then you’ll have a free-floating station. The gravity of your station will slowly but surely move the planet you’re hovering over, potentially destabilising it’s orbit and plunging it into the nearest star.
In conclusion: Don’t do this. Fiery Death will ensue.
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A stream of particles traveling at relativistic speed has the inconvenience of generating a shower of gamma rays upon impacting other matter.
The higher the flow of particles, the more intense the gamma shower.
Gamma rays are pretty nasty on life form, trolls included I assume, though there are no scientific studies on the topic. Wearing a gamma ray blocking outfit in the garden is at least inconvenient.
Moreover, gamma rays would ablate the material they impinge upon. This means that the house would be literally eaten away in a rather short time.
Therefore a mandatory technology to make this feasible is a gamma shield that doesn't get significant ablation damage and can block induced radiation from reaching sensitive targets for months to years, which is the usual life expectancy for household equipments.
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I'm building a world with an interplanetary empire (with an emperor as head-of-state), but I wonder how realistic it is for one to even exist.
An empire, according to Google, is defined as:
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> an extensive group of states or countries under a single supreme authority, formerly especially an emperor or empress.
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But there does seem to be a limit as to how big an empire can functionally be before it implodes/fragments. For example, restrictions based on relativity make it incredibly difficult for an empire to function in an interstellar and especially intergalactic level (assuming no technology could circumvent the proverbial speed limit). But what about an interplanetary level? That is, could a solar system realistically be organized as an empire with an emperor?
Here a list of what arguments against the likelihood of an interplanetary empire ever existing:
* **Humanity's need for the illusion of self-governance**: while certain nations in existence today are obviously not free, they maintain the illusion of democracy and free elections to justify their right to rule. Emperors and empresses cannot conceivably exist in the future as it is so ingrained in the modern psyche that the individual/common citizen provides consent to rule.
* **Size matters**: this is a very logical argument. The bigger an empire becomes, both in size of land and population, the harder it becomes to manage. A single, solitary emperor cannot possibly rule tens of billions of his citizens in an interplanetary empire across potentially diverse habitats
* **Exorbitant administration costs/corruption**: this feeds into the prior point, although this can be a significant issue for any government save for a loose confederacy of interplanetary empires. Law enforcement, tax collection, bureaucracy, and basic public services are inherently difficult to implement at a grand scale for an interplanetary empire. It is nigh impossible to not have the government collapse or be abused to the point of ineffectiveness.
* **Communication and transportation time-limits**: let's say on a remote colony, that an uprising sprouts up and spreads to adjacent colonies. How long could it realistically take the emperor in his palace to be notified, formulate a response, and act upon his response? This hinges on the state of technology, of course, but is a factor nonetheless.
However, I've observed some tropes/characteristics in fantasy empires that justify the inception and maintenance of empires. And to some extent, this applies to sci-fi empires as well. They are the following:
* **Divine Right**: a trope not entirely outside the realm of possibility. In ancient times, emperors would proclaim that God or the Gods or Heaven has provided them the right/mandate to rule. If the candidate for emperor is charismatic, skilled in diplomacy and war, and has strong military/economic/religious backing, he could rightfully seize power and rightfully keep it. If the emperor manages to cultivate a cult of personality (whether by outright worship or extreme reverence), many citizens would be averse to plan revolting against him.
Note: this doesn't mean that people are necessarily irrational, but myths and legends still play a part in many people's belief systems and therefore their decision making.
* **The inevitable lapse into autocratic rule**: a democratic government comes with its own issues, and many artists/historians can attest to this. The fall of the Wiemar Republic and rise of Nazi Germany, Julius Caesar and the fall of Roman Republicanism, Babylon 5's President Clark, Star Wars' Emperor Palpatine... these are some of the examples where democracy dies and it is done legally and sometimes even by the consent of the ruled.
* **Control through fear and dependency**: a strong military that ruthlessly crushes opposition, a secret police that turns you against your neighbor, and economic slavery (e.g. dependent upon a welfare state that enables you to subsist) are sufficient de-motivators to keep people from rebelling. Note: while historically speaking, empires don't generally last long through fear and intimidation, it is a common trope.
* **Control through pleasure and prosperity**: Conversely, Aldous Huxley, in *Brave New World*, painted a dystopian future where the use of sex, drugs, and recreational activities placates the masses. This would be a more generalized version of "Bread and Circuses". Also, if the vast majority of an empire's citizens live comfortably under an emperor's rule, why would they feel the need to rebel? Indeed, it seems that the health of an economy sets the mood for its populace.
* **Control of information**: this one is a bit obvious. How could people be outraged at the emperor's brutal crackdown of such-and-such protest if they never hear about it? How could people reliably communicate and organize themselves to resist the emperor if the emperor's government controls all means of long-range communication?
* **Overdose of information**: Another salient point made by Aldous Huxley was the "overdose of information". Ancient and modern dictatorships rely on strict control of information in order to maintain control. But, if the populace is inundated with meaningless information non-stop, they would be too distracted and tune any important information out. For example, an article discussing corruption by the emperor, will be tuned out as they read about a certain celebrity's extra-marital affair, or watch amusing cat videos. People aren't necessarily apathetic to government abuse/corruption. But people could remain "unaware" or too distracted because any useful political article is among hundreds of articles that talk literally about nothing.
But based upon this reasoning, could an interplanetary empire realistically exist in the future? If you have anything to add in the for or against argument, please share!
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I think it's possible for such empire to exist within a solar system. I would say that having both **military might and control of information** is the key of creating such a huge empire.
Right now, we can say China's CCP could be a prime example of a modern empire. They have very strict control of information. No privacy is given, as they're required to have their actual ID to be able to access online. So if someone wanted to say something bad about the government, they know who it was. Not only that, propaganda is everywhere, as China's government also controls the TV networks and newspapers. They can always point their flaws to the enemy, and without any comparison with other media, will believe that it is true.
Undeniably, having a huge military force would be an essential factor to have control of the empire's citizens. The empire needs an organization to enforce the rules that it has, and the military would be the best for that. Coupled with controlling information, and the emperor can just bring down any of its citizens due to [insert false info here].
To be a living God may not fully work in a futuristic setting. With instant communication and surveillance, any emperor or it's family being treated as divine beings will be monitored continuously throughout their lives. Any flaws or mistakes will be pointed out by the masses, and at the end of the day, recognize them as any other human being. So unless an emperor lives for a huge lifespan that no other humans can achieve, I doubt it is possible.
Communication is definitely a factor, though with an interplanetary setting, it may not be a huge one. For example, it will take about 43 minutes for a radio transmission to be sent from Earth to let's say Jupiter (Europa is a possible moon to colonize). While not instantaneous, we've survived longer delays in communication back in the 90s (Cuban Missile Crisis, negotiations between US
& Soviet Union), so adjustments can definitely be made. Besides, with a huge military might, there will be stations in every major colony to "keep the peace".
Transportation on the other hand, is a bigger problem. Colonized planets could or must be self-sufficient that it produces it's own food and resources, rather than being depended on a "farming planet", unless technology has reached the point where it only takes days or weeks to arrive on another planet instead of years. At that point, very specialized planets would arise. Would be cool to see an industrial planet with a huge hole at the center, as it is being used to construct massive spaceships at the very center, and launch them once done. Or, a planet rich with heavy metals being surrounded by harvesters, eating the planet bit by bit and have a network of ships going back and forth, delivering said harvest to other planets.
Probably a big way for an interplanetary empire to form is to have a common goal.. or enemy. What if there's another empire or colony threatening the lives of the solar system? Humanity will likely band together to fight a common enemy and will voluntary join a part of an empire that will guarantee their safety.
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Using history as a guide, an empire could exist in the future as large as the solar system (Kardashev level 2). Time more than distance would be the limiting factor - how quickly (or slowly) can information be disseminated and reacted to. It could consist of hundreds if not thousands of independent and interdependent habitats, colonized asteroids, and terraformed worlds. How would the Emperor maintain control- through IA, brain washing and appealing to enlightened self interest of his governors and/or controlling corporations (think modern day royalty or an equivalent to medieval guilds (forget labor unions - too much of empire would be automated that they would not have a voice). The empire would employ a propaganda machine the likes of 1984 Orwellian could only dream of. Would there be decenters? Absolutely and would also be encouraged in limited ways to keep the civilization from becoming stagnant. I don't see it as being dystopian and the fringe would develop with unique customs and cultural identities.
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If you look at [British Empire](https://en.wikipedia.org/wiki/British_Empire), especially during 19th century, you would see that:
* It could manage different regions which were so far away that it took months while any help (army and/or goods) from metropoly would reach a colony. I agree with @Mice Wilco that time of travel is more important than just miles or parsecs.
* Some distant areas (Austalia, India etc) were managed by local Governor which had:
+ Local army which had local divisions along English
+ Local laws relevant to traditions of each region
+ Local taxes and local goverment system which also was relevant to culture of region
Distant colonies trasformed to independed states
So we could say that English Empire consist of different states under authourity of a Queen (King/Emperor)
* It suffers from corruption and inefficient Governors
* It existed for decades, even centuries.
So we could see that empire could exist on large scale when direct ruling fails. It could be not so dynamic and efficient as other form of goverment but it's possible.
By the way, some people say that Empire still alive in another form: [Commonwealth of Nations](https://en.wikipedia.org/wiki/Commonwealth_of_Nations) and less public but powerful [Five Eyes](https://en.wikipedia.org/wiki/Five_Eyes) and other semi-formal international organisations. It looks like conspirology but in scope of this question you may say that many countries *could* be secretely united by secret Emperor ;-)
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Long time ago I read from a sci-fi book sentention which I still like: `Emperor like democracy: He suggest that it's essential part of any empire`. Sadly, I can't remember nor author nor accurate citate.
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Imperial powers have existed in the past with many of the constraints analogous to the time/distance factors an interplanetary empire would have. The [Delian League](https://www.ancient.eu/Delian_League/) was essentially an empire of island city states held together by Athenian rule, an extended to the grain growing regions on the shores of the Black Sea. Transportation and communication was via ship, either "round ships" for trade and triremes for military control. This was a highly efficient and successful setup done in the classical era, lasting from 487-404 BC.
An Imperial system could easily be established in space through the simple control of vital trace elements which are difficult to find in bodies outside of the Earth. Control of phosphorus might be a critical factor, since this is a key element for life. Limit the amount of phosphorus available and you limit the maximum size of any polity outside of the Earth.
Other reasons to exert imperial control involve energy. Even a small cargo pod moving at interplanetary velocity will have the kinetic energy of a small nuclear weapon. The [Chelyabinsk meteor](https://www.space.com/19823-russia-meteor-explosion-complete-coverage.html) was estimated to be only 20m in diameter and a mass of 12000 tons, but had a yield of about 500 KT, similar to a strategic nuclear warhead on an ICBM. Spacecraft and other objects will need to be strictly controlled at all times, or they will become deadly hazards to planets, moons, space stations and other spacecraft.
Expanding on that idea, there are good reasons to believe that self propelled rockets will be a minority option in the future. [Beamed propulsion](https://space.nss.org/settlement/nasa/spaceresvol2/beamed.html) using lasers or high intensity masers or particle beams could be the norm, since you can bypass the [rocket equation][3 (<https://www.nasa.gov/mission_pages/station/expeditions/expedition30/tryanny.html>) and no longer have to fuss over every gram (and carry a lot more usable payload). The downside is there are now mega or gigawatt energy beams crossing the Solar System, and this must be carefully coordinated and controlled.
So there are historical reasons to believe that such a political system is possible, and several factors specific to the space environment which suggest that there are good reasons for such a system to be established.
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Only based on your arguments: the favorable characteristic you list are not enough to offset the three first obstacle you give ("Humanity's need for the illusion of self-governance", "Size matters" and "Exorbitant administration costs/corruption").
Although as mentioned by others history shows Empires are mantained through centuries, without better arguments to explain it, the Empire is not viable.
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It's **plausible** enough. To address some of your concerns:
**Humanity's need for the illusion of self-governance:** There's no reason to think the empress couldn't be elected; consider the Holy Roman Empire.
**A single, solitary emperor cannot possibly rule tens of billions of his citizens:** They're allowed to delegate. There's also no reason to assume that an interplanetary empress would be human.
**Exorbitant administration costs/corruption:** History would seem to support the notion that humanity's tolerance for corrupt governments is astonishingly-high.
**Communication and transportation time-limits:** The British managed to work around it 150 years ago in India; surely we've learned a few tricks since then.
In conclusion, there's nothing here that humanity hasn't overcome before.
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Yes, it can. It certanly can be worked to seem plausible, and it can be forged as a natural development from the right cirscunstances. And the strongest argument seems to be hidden whithin your "Control through [fear and] dependency" argument.
I believe that even the most advanced civilzation or the most expansive empire can be wrote as depending on "something" controled only by the emperor or his clan, family, aristrocracy. That special resource must be unique, possible to contain and indispensable to life for the people of the empire.
A good example of this implemented is the Dune series, where they have the substance know as the Spice or melange which can be produced in only one planet in the entire extension of the Empire:
In the series, the most essential and valuable commodity in the universe is melange, a drug that gives the user a longer life span, greater vitality, and heightened awareness; it can also unlock prescience in some humans, depending upon the dosage and the consumer's physiology. This prescience-enhancing property makes safe and accurate interstellar travel possible. Melange comes with a steep price, however: it is addictive, and withdrawal is fatal.
<https://en.wikipedia.org/wiki/God_Emperor_of_Dune>
Relevant info:
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> Leto II Atreides, the God Emperor, has ruled the universe as a tyrant for 3,500 years after becoming a hybrid of human and giant sandworm in Children of Dune. The death of all other sandworms, and his control of the remaining supply of the all-important drug melange, has allowed him to keep civilization under his complete command.
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A political union can take any form or many simultaneously. Not all agencies within any given polity act with the same fundamental rules or philosophy, rather what determines the fact of a political union is the subscription of those with power to that fact.
Observers with differing assessments and points of view will have different views as to the attribution of acts. That is to say, whether they are attributed to humanity itself, a given nation, an ethnic group
A Tujia British Muslim CFO of a US registered corporation acts. So inclined observers will alternately describe the act as the act of a Tujia, of a Briton, of a Muslim, of a Capitalist, of an American corporation. Some of those the observer will have no problem also including under umbrella categories 'Human,' 'Western,' 'Eastern,' 'Northern,' etc etc an. What matters to us is that those who oppose the view that x is part of y polity have insufficient power to make that an operational fact.
People still consider themselves 'Swedish' or 'Saxon' or 'Chinese' generations after another Swede or Saxon or Other might say any real connection was severed. Neither opinion defines any objective fact.
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What particular role and form any given political union might take is almost as boundless as human imagination, we might set arbitrary bounds for what amounts to a union or correspondency, but they are arbitrary.
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Life on Earth could be all but extinguished by one person with access to propulsion systems capable of carrying mass cargo interplanetary distances. One would imagine that should such a scenario as an interplanetary empire occur, survival of the species would, one imagines, be built upon a rather more deliberate and comprehensive approach to child-rearing than the lackadaisical approach currently accepted in the names of diversity, laziness and freedom. Unity of upbringing would inevitably (even if not a deliberate aim) be conducive to 'accepting the fact' of racial unity.
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An interplanetary empire built on any terrestrial model would probably end with the disappearance of humanity. Today we have a tendency to believe that MAD prevents major wars.. which if true, means that extensive colonisation of space will allow for major wars again if done under existing(or existed) cultural models, being as such a conflict can be fought and 'won' from space-borne vehicles that are not nearly so vulnerable as planetary populations.
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Rewriting the question to clarify:
The time and location is now in our current Earth. A wandering red dwarf flare star (like Wolf 359) is moving towards our Solar System.
The question: **How close could it be to Earth without disrupting our civilization?**.
[Answer]
# Considering luminosity
The absolute magnitude of Wolf-359 is 16.65. That is not very bright.
### Case 1: The dwarf adds to the planet no more light energy than 1% of the main sun
Lets say we define 1% of the sun as a mostly minimal source of extra heat and energy. If we added that much extra solar energy to Earth, global temps would rise, but probably stabilize near to where they are now due to higher blackbody emissions.
The apparent magnitude of the sun is -26.74. The brightness factor between to magnitude values (where $\Delta m$ is the difference in magnitude) is
$10^{0.4\Delta m}$. Set that equal to a factor of 100 (for 1% of the sun's apparent magnitude), and we get $\Delta m = 5$. Therefore, we need the flare star to have apparent magnitude of -21.74.
The formula for apparent magnitude ($m$) from absolute magnitude ($M$) based on distance in parsecs ($d$) is $M = m - 5\left(\log\_{10}d-1\right)$. This solves for 0.043 AU. This is actually very close, about 20 times farther than the moon, but closer than any other planet.
This suggests that the planet could actually orbit the flare red dwarf, as long as the flare red dwarf orbited the sun in the habitable zone.
### Case 2: The dwarf adds to the planet no more light energy than the moon
Let us say we want no appreciable effect on the planet's surface from the red dwarf's radiation. In that case, let us ensure the dwarf is never any brighter than a full moon.
We re-do the calculation, except we want the dwarf's apparent magnitude to be equal to that of a moon, $m = -12.74$.
Plug in the rest of the values for $M = m - 5\left(\log\_{10}d-1\right)$ and we solve for 2.73 AU. This is farther than Mars, but closer than Jupiter.
So if we replaced Jupiter with Wolf 359, Wolf 359 would not be any brighter than a full moon.
# Considering the flares
### Energy from the flares
From [Cwiok, et al, 2006](https://www.researchgate.net/publication/241379380_Search_for_Optical_Counterparts_of_Gamma_Ray_Burst), we see that the optical apparent luminosity of Wolf-359 increases to about magnitude 9 (from its normal 13.54). Peak luminosity is only a few seconds, and within about five minutes luminosity has returned to normal.
These flares would be visually noticable from Earth, but would not provide appreciable heating to disrupt the environment.
### X-rays and gammas
Wolf-359 does release X-ray and gamma energy. Both of these are strongly blocked by the Earth's atmosphere. I cannot find a source to determine the magnitude of the X-ray and gamma energy released, so see if either would be a radiation hazard on Earth. However, given that the Earth's atmosphere absorbs both, I strongly doubt Wolf 359 could put out enough energy to cause a problem.
I will keep looking into this, though.
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Many fictional characters,specially in the anime art have shoulders bigger than any other upper body muscle. Normally the obliques,chest and latissimus dorsi are the biggest muscles in the upper body but in anime the shoulders are actually bigger than the head.
[](https://i.stack.imgur.com/somj3.png)
These are the proportions I'm talking about,normally in humans the shoulders are merely assistance muscles which help the rest of the body on stabilizing the arms, but in anime the rest of the body is an assistance muscle to the shoulders.
Humans who somehow evolved shoulders this big would function differently than normal humans in basic activities or would they just be stronger and no other real difference would be noticed?
[Answer]
* Shoulder dislocation would be less common, although reducing the dislocation would be much harder.
* If women do not evolve with larger hips and broader vaginal canal, there will be more deaths during labor, affecting both mother and child. That could result in more caesareans.
* More strength on the upper body, although if other muscles do not evolve similarly, there won't be much difference since you need muscle synergy.
* Less mobility since you won't have much range of motion of the upper limbs.
* Larger seats so you could sit comfortably not rubbing shoulder to the person next to you.
* Scratcher would be a well paid profession, since you can't reach your back. Ok that one is a joke, but you get the idea.
[Answer]
**Nothing Interesting**
If it's happening through evolution, then the selection underlying this muscle growth would also select for the best support mechanisms for it, ie more muscular backs, bigger abs, bigger bones in the back and shoulders. Modern bodybuilders get close to anime proportions with minor negative effects on their bodies, like reduced flexibility. Assuming that that the evolved humans increase the size of their shoulders to gigantic proportions through training, we can look to body building to get an idea of what might happen.
Otherwise, the only noticable effect would be increased vertical lift strength when using the arms, since that's how the muscles in the shoulders are set up to work.
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So in this world I'm building there's a bunch of reasons to, at some point, stop being nice and make sure someone is really, really dead. For this purpose they decided to weaponize black holes. Nothing says "stay down" as ripping them to shreds, heating them up as they accelerate, crushing them into a tiny sphere of fused matter around a singularity in space-time and then even that matter they consisted of is erased from the universe due to Hawking radiation.
First to get this out of the way, black holes evaporate, and as this thread says: [Black hole launcher](https://worldbuilding.stackexchange.com/questions/11955/black-hole-launcher).
A one second black hole would already be thousands of tons. This handheld miniature black hole weapon wouldn't have anywhere near that mass so its ammo would evaporate almost instantly upon firing, where "evaporate" will be closer to "explode violently". To combat this the weapon would either need to use some kind of anti-quantum beam in the black hole's path to reduce the amount of Hawking radiation until it reaches the target, or the black hole would need to be fired really really fast. That last one doesn't seem very useful as it would still be evaporating violently while traveling to the target, unleashing most of its energy at the launch-point. So maybe there's a better idea out there?
How the (handheld) weapon works (as far as my knowledge on these subjects go):
Our Sun does not have the temperature and pressure to actually perform fusion in its core. As particles move they are subject to quantum effects, one of which means they have a chance to be somewhere else entirely. This allows these particles to "tunnel" into another particle they wouldn't be able to fuse with normally and start a fusion reaction. The temperature and pressure of the sun only make the chance of this happening more likely. The weapon has a carefully calibrated system that changes the chances and makes it almost 100% likely that a large amount of particles with a certain mass will converge simultaneously and form a black-hole, preferably with a tiny delay so that this happens a distance after the projectile has left the barrel.
So for my question: How effective would such a weapon be? Would it basically be close to an anti-matter bomb in that it just releases butt-loads of energy in a short period of time (to which there's protection in this universe, against such energy releases not antimatter which they sometimes use as an alternative to black-hole launchers), or would it really be able to be shot at a hostile say 100 m away and absorb something the size and weight of a cow without adding more techno-magic than the quantum-chance alteration at the end of the barrel of this weapon? Preferably without turning the owner of the weapon into part of the black hole.
[Answer]
A black hole gets its energy from its mass and the [minimum mass of a stable black hole](https://en.wikipedia.org/wiki/Micro_black_hole#Minimum_mass_of_a_black_hole) is 10¹⁶ Kg, so as a stellar killer mounted on a spaceship that could be made to work, but as a handgun you need to take into account the evaporation rate and [2 formulas exist:](https://en.wikipedia.org/wiki/Hawking_radiation#Black_hole_evaporation)
**For a mass much larger than 10¹⁷ grams:**
[](https://i.stack.imgur.com/o1jBi.png)
**For a mass much smaller than 10¹⁷ grams, but much larger than 5×10¹⁴ g:**
[](https://i.stack.imgur.com/E9nOF.png)
So *each bullet* is going to weigh *at least* 1,000,000,000,000 pounds: *a bit impractical*
Even if you would forget about a black hole handgun and go with [neutronium bullets](https://en.wikipedia.org/wiki/Neutronium), you would have a ton of technical problems as free neutrons have a half life of about 10 minutes, cannot be contained by electromagnetic forces, so would have to be made on the spot, so a [howitzer](https://en.wikipedia.org/wiki/Howitzer) could be located in a desert and use the surrounding sand to create its shells as needed but a handgun would run into severe technical problems as well.
On top of this, you would need to accelerate these heavyweights to hit anything, so I would say: *forget about kinetic black hole / neutronium handguns on a planetary scale*...
The only possibilities are:
* Drop de black hole or neutronium weapons from your storyline and concentrate on energy weapons
* Take the scenery into intergalactic space and have a massive shout-out there.
* Set your story in a hybrid Fantasy - Science Fiction universe and have it happen **magically.**
### ;-)
[Answer]
I was going to write a very long answer with physics and latex syntax and \*\*\*\*, \*\*\*\*\*ing about how this wouldn't work at all without [magic](/questions/tagged/magic "show questions tagged 'magic'"). However, the lack of the [hard-science](/questions/tagged/hard-science "show questions tagged 'hard-science'") tag coupled with my lazy pragmatical personality kept me from doing so.
You just want to know how effective such a weapon is. As a gun, you are always at the risk that you will shoot yourself on the foot, both literally and figuratively. There are a dozen ways you can miss a shot and the colateral damage will be more than the shooter could deal with. For example, should your aim from behind cover and hit the \*\*\*\*ing cover (happens more than I'd like to admit in paintball), you suddenly have a thousand tons of mass on your lap.
Even for a one second black hole, you would be facing a paradox much like the one from this previous question:
[What effects would propellant that expands at near light speed have on firearm technology?](https://worldbuilding.stackexchange.com/q/107898/21222)
In short, quantum and relativistic weapons may sound cool to the ears of light sci-fi fans, but they are only ever practical for suicide bombers.
[Answer]
The shortest answer of all is to forget about firing the micro black hole, but use it as a bomb or grenade. As it evaporates it releases ever increasing amounts of energy, mostly as hard radiation, so you have sphere hotter than a star in the final moments, blazing away at every frequency from gamma radiation to long radio waves. Shielding against that will be virtually impossible.
If you are not inclined to be a suicide bomber, the black hole and its containment unit is placed in a self driving vehicle and then sent to the address of the target. Precision isn't really much of an issue; several city blocks are going to be vapourized and large areas surrounding that will be irradiated, incinerated and blasted by high energy shock waves as the x-ray and higher radiation interacts with the atmosphere. Given even very small black holes have immense masses, you should be looking for a self driving truck to do the job.
Of course there is another issue to consider: the lifetime of quantum black holes is quite short, so you need to somehow prepare the entire package (including the black hole) within minutes of locating the target. Putting together a black hole is likely to take an enormous amount of energy and equipment, if I thought I'd be the target of a black hole bomb, I'd probably draw a circle around every high energy power plant and physics installation I knew of and clearly avoid this areas....
[Answer]
Any black hole you're going to be able to make with such a weapon (I'm looking at how much matter you would have in close proximity to use) is going to be pretty close to an instant bang.
It will not be quite as sharp a shock wave as a nuclear weapon would produce as the energy release is slower--and, yes, that matters. Think of a fuel-air bomb compared to a conventional bomb. The former makes a much bigger boom per pound but fares poorly at cracking hard targets due to the shock wave being more spread out.
An antimatter bomb is pretty clean. The blast itself is pure gamma radiation (which quickly gets absorbed and replaced with an expanding ball of plasma), the only radioactivity left behind is from atoms that lost bits of their nucleus to contact with the antimatter but where not completely destroyed. A black hole bomb, however, emits it's energy as energetic particles. Those will have a fair ability to induce radioactivity in whatever they hit. Far more atoms get hit than in the antimatter scenario, thus there will be more induced radioactivity.
If you want to survive it that means you're limited to pretty small bangs. (Since you have a line-of-sight weapon you're looking at the detonation.) At this point the blast differences aren't going to matter anymore but it's still dirtier than the antimatter.
(And before someone brings up the Davy Crockett--that was not a suicide weapon. Yes, if you stupidly stood there when you pulled the trigger you would die, but if you did it properly you dived into a foxhole while the weapon was in flight. Now you have a lot of dirt between you and the blast, the bomb won't hurt you. Better be upwind, though!)
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In the course of designing fictional species I often find myself wishing to use exotic senses which we humans lack. This poses a unique and interesting challenge as without possessing the sense myself I find it very difficult to understand what they can perceive. For the same reasons one can’t describe a color to a blind person or a sound to a deaf person I don’t expect an explanation of what this sense *feels* like, but rather what it is capable of.
Electrolocation is the ability to detect nearby electrical fields. It is observed primarily in fish as water is much more conductive than air. It comes in two different forms, passive and active.
Fish possessing passive electrolocation are capable of detecting the weak electrical fields that all animals produce by the action of their muscles and nerves.
In active electrolocation, however, fish produce their own electric field which allows them to detect differences in conductance and capacitance in their surroundings.
In order to make the question more answerable let’s focus on active electrolocation. **My question is what is an organism possessing this sense actually able to perceive?** I'll provide some example questions but don't feel the need to answer them all or limit your answers to them.
* Can they distinguish between size, distance, and magnitude of distortion?
* How precise is this directional sense and can it work
in all directions?
* Are there any blind spots to the sense such as the poles of the generated electrical field?
* What substances would block the sense?
* Can it penetrate insulating materials?
As further guidelines for what I’m asking for, I’ll give an example. If I were asked to describe the capabilities of our sense of hearing I could say that we can distinguish a wide range of frequencies from each other although frequencies too high or too low are imperceptible to us. We can roughly determine the distance and direction of the source of a sound as long as it isn’t straight in front of or behind us. We have difficulty hearing through insulating materials and we can hear sounds reflected off of other objects which may confuse our sense of direction. I’m asking for an equivalent description of the active electrolocation sense.
[Answer]
Don't think of trying to explain colour to a blind man but a colour to a totally colour-blind alien: a colour is like a black and white shade but more intense so you see the difference better and the same goes for electrolocation:
* Can they detect the distance of an object?
*Yes, and the closer it comes, the "clearer" the image gets, just like your eyes work.*
* Can they distinguish between, size, distance, and magnitude of distortion?
*Yes, eye analogy again*
* How precise is this directional sense and can it work in all directions?
*The closer, the preciser, all 3 spacial dimensions*
* Are there any blind spots to the sense such as the poles of the generated electrical field?
*Yup, just like the blind spot in one eye: you can have dual electrolocation fields (North-South and East-West) to compensate*
* What substances would block the sense?
*Anything blocking electricity: plastics, wood, ...*
* Can it penetrate insulating materials?
*Erm, no, otherwise they wouldn't be "insulating" but they can look around the tree a bit if it's not too thick as an electric field bends around obstacles.*
**And most important of all:** our senses are not separate but work together as a whole: You can *hear* a car coming closer, just like you can *see* it doing the same, *smell it* after it has passed, and touch it if it gets too close! **:-)**
So Electrolocation would work in tandem with the other senses the alien has: it would feel the stampeding herd through its foot soles first, hear the herd coming, "feel" the electrolocation changes, ... but don't forget its sense of electrolocation has to be pretty powerful under atmospheric conditions as air doesn't conduct electricity well, but at high enough levels, [it does](https://www.youtube.com/watch?v=WIXVZXGc610)... **;-)**
[Answer]
To take things in order:
* Can they distinguish between size, distance, and magnitude of distortion?
Not all three without some other data no, a large, low magnitude distortion will appear the same at a certain range as a much smaller but more intense distortion so without independent knowledge of the range to the probable source they can't really tell them apart.
* How precise is this directional sense and can it work in all directions?
It should be very directionally accurate and depending on the sensor distribution over the creatures bodies it should be accurate in all directions.
* Are there any blind spots to the sense such as the poles of the generated electrical field?
There is the potential for white-out zones, caused by sensory overload but I wouldn't think there would be dead spots large enough to cause a blanking effect in any natural electromagnetic distortion.
* What substances would block the sense?
Glass, wood, or an air gap for any but the largest distortions.
* Can it penetrate insulating materials?
Only when the distortion is large enough to penetrate them.
[Answer]
Electrolocation in fishes detects electric fields, normally generated by muscular activity (but also from metals, that's why apparently sharks are sometimes attracted by metallic objects).
My guess is that the fish would sense a stimulus which is as stronger as closer the target is or as intense is the muscular activity.
Depending on the configuration of the organ, it is possible to get a spatial orientation, and the signal would be shielded by any configuration stopping electric fields.
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I have not had much success finding out what the effects of bombarding a planet with comets or asteroids could have on the temperature of that planet.
I expect it would add some heat, and I understand it would be temporary. I understand that if it was a very large asteroid or a moon or something it could heat up the planet so much as to make it unlivable for millions of years. I guess I am more interested in the kinds of bombardments that could be done on a planet that already has inhabitants, at least living in enclosed habitats. I am sure there could be all sorts of effects depending on the composition of the object bombarding the planet, and the angle and location of bombardment. Maybe it could even kick up a bunch of dust or cause volcanic activity that would temporarily cool the planet?
I am mostly interested in the possibilities of adding heat to a planet via bombardment and I am wondering how much heat could be added compared to how devastating the impact would be and how long the heat would last. (Aside from the effects of whatever was in the comet being added to the atmosphere.)
[Answer]
As you've mentioned, you've out some very important pieces of information to give a definitive answer, but perhaps [this link](http://down2earth.eu/impact_calculator/) would be a good start. Select the attributes most closely representing your world and then click on "Data View" to see the amount of kinetic energy imparted. From this you can get a pretty good idea on the largest heat/energy component in your system.
This of course ignores parts of the equation such as the heating created by the body entering your planet's atmosphere/ejecta removing energy, but it's a pretty good start.
The nice thing about the impact calculator is it gives a good visual on crater impacts and the potential for fireballs.
The thermodynamics behind how 'long' the heat lasts would vary greatly depending on a great number of factors, but suffice it to say, with energy being added in the [Chicxulub crater event](https://en.wikipedia.org/wiki/Orders_of_magnitude_(energy)), it will be around for quite a while...
[Answer]
**Atmosphere Thickening Retain's Heat**
Instead of impacting the comets into the planet why not have them do aero-braking maneuvers through the upper reaches of its thin atmosphere? Comets are made from water, rock, and CO2 so if you did enough maneuvers with enough comets you could noticeably thicken the planets atmosphere. A thicker atmosphere retains more of the heat that the planet is already getting. Its basically using global warming and the greenhouse effect.
**Other Options To Consider**
If your planet is geologically active enough it will have geological out-gassing that raises the atmospheric pressure, but maybe your planet's magnetosphere isn't enough to retain the atmosphere so its being stripped away by the solar wind. This is what happened to mars. The thin Martian atmosphere is actually only held in limbo where it is at by geological out-gassing. If a large di-pole magnet were placed in an orbit between Mars and the sun it would only be about 20 to 50 years before mars had an atmosphere again. The temperature differentials between light and dark would stabilize, and liquid water would begin to pool. Within 100 years the icecaps would melt and we'd even begin to see small shallow oceans on mars again. Maybe your people could utilize a similar method to regulate their own atmospheric pressure. Even Earth has solar stripping of atmosphere, if we were to apply a shield similar to the theorized Mars one we would see atmospheric pressure rise with a subsequent increase in global average temperature.
We're talking a really, REALLY powerful electromagnet though. Minimally it would require a large fusion power source and would be using more energy per day than all of humanity puts out per year currently. But its scifi, stuff is supposed to be big. Plus, according to NASA it would actually work (we just have no idea how to power it yet or how to build and put an object that large into orbit.)
[](https://i.stack.imgur.com/8W7oW.jpg)
[Answer]
Bombardment can indeed cause heating, both directly and indirectly. The mare on the Moon are believed to be lava flows created when the Moon formed for instance. This heat quickly radiates away. At least quickly on geological timescales. More long-term heating is also possible though. The bombardment would also deposit large amounts of radioactive elements, which as they decay generate heat. It is believed that that is a significant reason why Earth still has a molten core.
But if there is already a significant atmosphere, the bombardment can cause long-term cooling. The soot and dust blasted into the upper atmosphere will block a large amount of sunlight.
Which effect wins out depends on a lot of factors. Dense asteroids that don't break up before they hit the ground will cause a lot more dust to be launched than asteroids which explode in the air. If the planet is far from its star or the star is dim, there isn't much light to be blocked anyways, so dust won't matter as much. How strong the weather on the planet is will also affect cooling. Stronger winds will mean dust will stay in the air longer, meaning the cooling effect will be stronger and last longer. Big enough asteroids will actually cause secondary impact events as debris is blasted in space and falls back down. It is believed that the asteroid that killed the dinosaurs did this, sparking forest fires all over the world.
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No planet in the center, just a large O shape made up of large chunks of rock that in and of itself itself orbits a sun, as if it were a planet (as distinct from a ringworld). I know most of the time, similar structures tend to coalesce into a planet, but is there any radius with any amount of mass where it would keep itself together with its gravity and yet not form a planet?
Not a solid torus, but a ring of planetoids. (Imagine Saturn but without the planet at the center).
It need not be habitable or earth-like in any extent, I just would like to know if it is possible, to sate my curiosity.
[Answer]
**~~This is unstable~~ See the Edit**
We know that [binary stars](https://en.wikipedia.org/wiki/Binary_star#Center_of_mass_animations) can orbit around one another similar to what you're doing with your ring-o-worlds. They orbit around a central "center of mass" point.
It has been suggested that anywhere [from half to nearly all star systems](https://history.nasa.gov/CP-2156/ch2.5.htm) are multiple-star systems, including systems of 3 or more stars. Therefore, it's possible for your ring-o-worlds to exist from the perspective of (and this is the important part) *no other interfering gravimetric source.*
The problem is when you put the ring-o-worlds in orbit around a star. That star imposes a difference in gravity between the planets given any moment in time. It doesn't matter how small it is. That it exists means a wobble exists in the ring-o-world self-orbit, a wobble that (over time) eventually leads to the planets falling out of their self-orbit.
Because of this issue, it isn't possible for the ring-o-worlds to develop in the first place. By the time habitability was attained, they would have long-since decayed into normal orbits.
**EDIT**
After some research, I'm not so sure the ring-o-worlds idea isn't possible.
>
> The third type which will consider for now is the Double Binary system which will have two sets of binary stars orbiting a centre in between them. In the outer binary system, they will orbit round a centre and then those two will orbit round a fix centre with another two. ([Source](https://www.universeguide.com/fact/multiplestarsystem))
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And perhaps more authoritatively...
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> In October of 2012, the first four-star planet was confirmed by the Planet Hunters program from Yale. The planet – called Planet Hunters 1 (PH1) – is a circumbinary planet meaning it is orbiting a pair of stars instead of just one. Furthermore, orbiting that pair of stars is another pair meaning this planet is in a system with four stars total. With so many large forces acting on this system, the stability is, of course, a question of concern. According to the paper announcing PH1’s discovery, though, “the system is indeed stable on gigayear timescales” (Schwamb 2013). This implies there are formation possibilities never considered and is inspiring further study of PH1. ...
>
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> With their calculation, Schwamb et al. found the quadruple star planetary system to be stable; although they mention it barely crossed the threshold of stability. ([Source](https://www.authorea.com/users/21937/articles/26136-the-stability-of-the-double-binary-system-ph1/_show_article))
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A double-binary star system suggests a ring-o-worlds could survive orbiting around its star. And from our sister site, [Astronomy.SE](https://astronomy.stackexchange.com/questions/12041/double-planet-orbiting-wide-binary-star):
>
> A double planet system is less likely. It's unlikely to form on it's own during planet formation as that requires too much planetary angular momentum during formation.
>
>
> It's possible, but also unlikely to form by giant impact, as that's more likely to leave 1 planet and 1 moon. I've read (but can't find an article right now) that there's a giant impact size ratio and it's in the planet-moon range, not planet planet. Much less than 1 to 1. Pluto-Charon is 9-1 and Earth-Moon 81-1. A giant impact is also unlikely to create an Iron rich core for both objects. It's not a good way to create planet-planet.
>
>
> That leaves a 3rd possibility, also unlikely, but perhaps the most likely of the bunch is planet capture. Planets can form in Trojan points in the same orbit (Theia). The difficulty with orbital capture is that the velocity needs to be just right and capture's are likely to be significantly elongated orbits, which, maybe, over time, perhaps with a 3rd asteroid, could even out to slightly more circular. This is very improbable, but it might be the most likely way to form a double planet.
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**At this time, as an amature, I must conclude that having a ring-o-worlds orbiting a star is, indeed, stable. But just barely. A rogue planet would likely throw this off. But it appears to work. Run with it.**
[Answer]
This would not naturally work the way that you describe.
Saturn has rings because the ice and rocks that make it orbit the mass of the planet.
Without that mass, say if Saturn were to fall into a plot hole, the rings would quickly stop being rings and just become a cloud, which would disperse as their momentum no longer had anything holding it in place.
If you were to replace Saturn with a black hole with the mass of Saturn, then the rings would carry on as if nothing had happened.
[Answer]
A Neutron star was enough for Larry Niven
— from Wikipedia -
The Integral Trees is a 1984 science fiction novel by Larry Niven (first published as a serial in Analog in 1983). Like much of Niven's work, the story is heavily influenced by the setting: a gas torus, a ring of air around a neutron star. A sequel, The Smoke Ring, was published in 1987.
—
If it worked for Niven ...
[Answer]
[**There's already a fictional torus world, created by a fictional post-singularity entity.**](https://orionsarm.com/eg-article/59b109574cb45)
[](https://i.stack.imgur.com/hlVzr.jpg)
*[Image source](https://orionsarm.com/eg-article/59b109574cb45)*
I recommend reading the **Planetology** section of the page. It discusses just how weird gravity, climate, and tectonics in such a world would be.
---
**Some weird traits of the world:**
* Shape is maintained by ultrafast rotation.
* Ultrafast rotation causes variable gravity, from 0.7 to 1.1 g depending on location.
* Rotation causes the planet to be very geologically active.
* Variable gravity and geological activity causes incredibly tall mountain ranges and varying cloud heights.
* Rotation causes fast winds and weak heat distrubution, which then causes dramatic temperature changes.
---
**[There's also another page from the same website, called a hoopworld.](https://orionsarm.com/eg-article/49142c044cba7)**
[](https://i.stack.imgur.com/KO1H2.jpg)
*[Image source](https://orionsarm.com/eg-article/49142c044cba7)*
While this is more likely the answer you're looking for, the hoopworld does not provide as detailed information as the torus world. The hoopworld has a much larger external radius at 70,000 km, being a fluid ring with a solid crust that does require further stabilization
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A habitable planet with multiple moons, only one of which is tidally locked to the planet: is this general scenario possible?
I understand that tidal locking takes a very long time to happen. So maybe this setup could be achieved by having one very old moon and some newer moons, where the older moon is tidally locked to the planet (and the newer moons haven't had the chance yet).
Presumably (?), if the new moons were created in an impact event like Earth's moon, this would destabilise the older moon causing it to unlock from the planet. But if the new moons were formed by e.g. asteroids being captured by the planet's gravity, this wouldn't be a problem.
[Answer]
[The time it takes a moon to become tidally locked](https://en.wikipedia.org/wiki/Tidal_locking#Timescale) to a planet depends on a number of factors. In particular,
$$t\_{\text{lock}}\propto\frac{\omega a^6}{m\_p^{2}}$$
where $\omega$ is the moon's initial angular speed, $a$ is its semi-major axis, and $m\_p$ is the mass of the planet. There's a very strong dependence on $a$ - double it, and we increase $t\_{\text{lock}}$ by a factor of *64*! So if it takes, say, 10 million years for a moon with semi-major axis $a\_1$ to become tidally locked with its planet, then a moon with semi-major axis $a\_2=2a\_1$ could take 640 million years to become tidally locked - even if they started with the same period of rotation.
Let's crunch some numbers. The initial conditions of the Moon after its formation are unknown, but there's been some modeling of them. [Cuk et al. (2016)](https://www.nature.com/articles/nature19846) did some simulations of the rotation of both Earth and the Moon. Using their modeling, I'm going to assume several things:
* The Moon's initial angular speed was $\sim10^{-5}$ radians/second.
* The initial semi-major axis was about 25 Earth radii, or $\sim1.6\times10^8$ meters.
* The time until tidal locking was about 20 million years, give or take.
Therefore, using the mass of the Earth, $M\_{\oplus}$, we find that
$$t\_{\text{lock}}\approx2\times10^7\left(\frac{\omega}{10^{-5}\text{ rad s}^{-1}}\right)\left(\frac{a}{1.5\times10^8\text{ m}}\right)^6\left(\frac{m\_p}{M\_{\oplus}}\right)^{-2}\text{ years}$$
This does assume that certain physical properties of the satellite, such as its radius, mass, and love number are all the same as the Moon's. However, it's simple to add more terms to the scaling relation to take this into account. Notice that if we take the ratio of the tidal locking timescales for two moons orbiting the same planet, the term involving $m\_p$ drops out.
Now, this kind of variation is possible. [The moons of Mars](https://en.wikipedia.org/wiki/Moons_of_Mars#Characteristics) have significantly different orbits; Deimos has a semi-major axis two and a half times as large as Phobos'! We see even greater variation in the moons of giant planets, such as [the moons of Saturn](https://en.wikipedia.org/wiki/Moons_of_Saturn#List), but I doubt there would be that sort of orbital difference around terrestrial planets, for the simple reasons that 1) it's hard for lower-mass bodies to form many moons, and 2) the [Hill sphere](https://en.wikipedia.org/wiki/Hill_sphere) - the region in which an object can have satellites - is smaller for low-mass planets.
It seems likely - possible, at the least - that [the moons around the giant planets formed at different times](http://burro.case.edu/Academics/Astr221/SolarSys/Formation/oddsends.html). Some of the ones with smaller orbits could have formed with the planet, out of the disk of dust and rock surrounding it. The outer moons might have been captured later on, from asteroids or bits of protoplanets. Additionally, some may have formed [in collisional families](https://en.wikipedia.org/wiki/Collisional_family), meaning that some groups of moons could have formed at different times. Each group would have formed from the fragmentation of an asteroid captured by the planet - [the Ananke and Carme families](http://iopscience.iop.org/article/10.1086/382099) of moons around Jupiter are prime examples. Of course, less-massive terrestrial planets are less likely to capture asteroids, but then again, the moons of Mars were likely once asteroids.
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The [Pluto system](https://en.m.wikipedia.org/wiki/Moons_of_Pluto) is almost exactly what you want, in the terms you are interested, with two caveats:
1. Pluto is mutually tidally locked to Charon, implying a long day (6 Earth days), which could affect habitability
2. Pluto has a small in mass and hence its gravity is small (6% that of Earth), which is bad for human habitability at least
It is not difficult to imagine this configuration with more Earth-like characteristics: closer to the primary, the two main objects with a bigger mass, a more life-friendly composition, etc.
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I apologise in advance for the graphic nature of this question. I guess it just had to be asked.
I am looking for a way to make the feces of my alien vertebrates some color other than brown or green. In our Terran vertabrates, bile that is broken down in the gut along with items in the diet affect the color of fecal matter. We usually see green, rust, or the 'classic' brown unless something unusual such as a beet was eaten. My first thought when finding an answer to this question was to find an alternative to bile for breaking down fats into fatty acids. I am looking for something that would change the color almost regardless of what was eaten, as bile does. Anything that would change the color in carnivores, herbivores and everything in between would work. As long as the feces will be distinguishable from Terran feces, it should work.
Thanks for bearing with this one.
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**Bone = white dung.**
If an animal eats a lot of bones, much of the bone minerals is not digested. It passes through into the feces and turns them white. I have seen this with dog droppings. Hyaenas routinely eat bones; depicted are hyaena droppings.
[](https://i.stack.imgur.com/S5a9k.jpg)
<https://thomsonsafaris.com/blog/identify-animal-scat-walking-safari/>
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Another way to get white feces is how reptiles do it: concentrate the nitrogenous wastes that mammals pass as urine, and pass that concentrate as feces. The nitrogenous waste (mostly urea) is a white substance with the regular poop brown. Reptile feces is bicolor for this reason.
[](https://i.stack.imgur.com/EUH90.jpg)
<http://www.feedpecker.com/snake-poop-look-like/>
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**Blue dung (or purple or red)**
If you can design the metabolism of your aliens to excrete *anthocyanin* (an organic pigment) you could have a reason for their poop to be blue, purple or red (depending on the PH of the remaining components of the dung). So, the same way we humans have a variety of standard colors, they could have their own pantone (depending on what they have eaten).
More info about the anthocyanin in this Wikipedia link:
<https://en.wikipedia.org/wiki/Anthocyanin>
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Their normal gut flora includes something that releases a chemical that is whatever color you want.
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Note: an edit has been made to the main question at the bottom
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A couple of years ago, I had a worldbuilding project which I have recently revived.
I was relatively new to worldbuilding back then, and I made the terrible mistake of drawing a map of my planet before deciding axial tilt.
Now that it has been reborn, I am applying my much better worldbuilding skills to the project to give it a new and more plausible feel.
Since I already had a map of biomes, I divided the width of the page the map was on by 18 to determine lines of latitude (One for every 10 degrees).
Using the biome map, I denoted that the absolute minimum figure for the latitudes of the **tropics** must be **40 degrees north and south.**, meaning the axial tilt of the planet is 40 degrees.
Therefore, the latitudes of the **polar circles** would be **50 degrees north and south**.
But that figure conflicts with my map. The environment only starts to change to tundra at around **20 degrees north and south**, which is already halfway inside the polar circles.
So, my question is: **Is it possible for the climate in the warmer half of each polar circle to be temperate, and if so, how would I do it?**
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Yes.
In Earth history there was a time when tropical plants grew at the poles. So, give the right combination of atmosphere composition, condition and solar irradiation, and it can happen.
Useful [Triassic Period](http://www.ucmp.berkeley.edu/mesozoic/triassic/triassic.php) citation:
>
> "There were no polar ice caps, and the temperature gradient in the
> north-south direction is assumed to have been more gradual than
> present day. "
>
>
>
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The **[Gulf Stream](https://en.wikipedia.org/wiki/Gulf_Stream)** is a very important aspect of the global climate that helps maintain the climate of locations like the British Isles and Scandinavia via the [North Atlantic Current](https://en.wikipedia.org/wiki/North_Atlantic_Current).
>
> A noticeable effect of the Gulf Stream and the strong westerly winds (driven by the warm water of the Gulf Stream) on Europe occurs along the Norwegian coast. Northern parts of Norway lie close to the Arctic zone, most of which is covered with ice and snow in winter. However, almost all of Norway's coast remains free of ice and snow throughout the year. Weather systems warmed by the Gulf Stream drift into Northern Europe, also warming the climate behind the Scandinavian mountains.
>
>
>
Your planet could have a series of ocean streams that move warm water (and thus air) from the part of the planet closest to the sun to the poles. It might take some finagling to make a plausible continent/ocean shape, if you care to, but I think this is a realistic way to say that part of the poles would be temperate. The other half of the pole could be blocked off from the effects of the warm weather by particularly high mountains. Look at how desolate the east side of the Rocky mountains is compared to the west.
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In addition to other answers that discuss the Gulf Stream and cyclic climate change, there is a specific casethat come to mind.
## Axial Tilt
If Earth were tipped on it's side, like [Uranus](https://en.wikipedia.org/wiki/Uranus#Axial_tilt), then the poles would likely never have ice on them, even if the points furthest from the solar plane did.
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I have a creature in which its main feature are its alligator-like jaws. It's carnivorous, incredibly aggressive, and is a reptile. Let's call them **boom-agators**.
Now reading through many different alligator and [crocodile bite forces](https://news.nationalgeographic.com/news/2012/03/120315-crocodiles-bite-force-erickson-science-plos-one-strongest/), they have a bite force of 3,700 pounds per square inch, or 16,460 newtons (saltwater crocodile).
I'm looking to get much more explosive with my reptilian bites the only way I know how...**adding explosives to the mix**. The idea is that in the jaw of my reptile, a small chemical explosive (think airbags) would combine and react in a small piston-like cavity in the jaw, propelling the jaw closed with the force of the reaction.
Now obviously, having explosives in your mouth seems like a *Bad Idea*TM, however for my story to be plausible1, I need for these to be explosive based. There's a few problems that I think I've addressed, but have I missed anything that might cause issues for this animal.
* Their primary diet consists of rapidly swimming fish, and requires them to essentially open their mouths and clamp down as a fish is swimming (35 km/h) by them. They're a river dwelling species in which fish are constantly in migration, so food availability isn't an issue.
* They live in the water, so any fire based reactions (gunpowder, etc) should be contained within the animal.
* The animal has a chitinous jaw-stopper that looks like the [rubber pieces that keep doors from opening too hard into walls](https://www.lowes.com/pd/Gatehouse-0-7-in-x-2-6-in-Universal-Hinge-Pin-Stop/3353164). It can take as much force as you put into it to prevent the teeth from entering its own skull. Their bones are made from adamantium.
* If used in combination with actual muscles, assume that there is no limitation on its reactions, and its evolution has taught it how to use this ability with its muscles involved.
* If the required chemicals are not natural, please assume the creature can make them by eating a magical weed that its species knows is beneficial.
* The explosive must not be so large as to be unable to be contained by the animal (please don't make a tiny black hole in its mouth to do this...)
I also just saw [this question](https://worldbuilding.stackexchange.com/questions/112460/armor-for-giant-crabs-to-defeat-explosive-bites-from-predators) about a crab that needs to escape my predator, however I'm looking for the other side of the equation.
So with that out of the way **How can my creature use explosives to get the maximum bite force/speed?**
1 Guy gets stranded in a Bayou environment in which these live, and must harvest these chemicals and glands to get revenge on those who wronged him.
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You basically gave the answer yourself: **airbags in the jaws**. Your animal's teeth rest on a semi-flexible bag containing the explosive chemical. Two layers of bone in the jaw: a larger one, the regular jaw, attached to the skull, plus another extra adamantium-bone layer attached to the teeth, and the membranous airbag conecting them.
In normal conditions, the animal is able to open and close its full mouth at regular speed. The airbag is shut down, thanks to the sticky explosive liquid. But when it is *Bite'o Clock$^{TM}$*, a nerve signal triggers the explosion and the bag immediately inflates, sending the bone-with-teeth upwards and away from the regular jaw. The connexion with the upper set of teeth is almost instant and catastrophic to anything that is in the middle. After the event, the gas deflates relatively slowly through the small pores in the bag, while a new batch of sticky explosive liquid is secreted by specialized glands, much like if it were saliva.
As for the explosive chemical, we could work with a something chemically related to [nitroguanidine](https://en.wikipedia.org/wiki/Nitroguanidine), which presents a molecular structure close enough to what is easily biologically available and a good explosive, see [Explosive behavior of nitroguanidine](https://www.sciencedirect.com/science/article/pii/S0082078469804571). And it is used, with other stuff, on actual airbags, so one could work some force numbers from there...
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Basically what you will want is a [concrete nailgun](https://www.youtube.com/watch?v=gnaN8cEUKWM).
[](https://i.stack.imgur.com/ALJ06.jpg)
Concrete nailguns like these use a small firearm charge (such as a .22 blank) to generate pressure to drive a nail into difficult materials like concrete. It's designed to move the nail fast enough to limit the concrete's ability to distribute the shock outward (which would lead to chipping). This is perfect for you because it lets you avoid one of the banes of any firearm setting: momentum. If you tried to drive a giant object forward, like, say, a 20mm bullet, it drives back with [comparable force](https://youtu.be/E92CLD5VXKg?t=1m36s). This is less than ideal in the middle of your skull. Even with adamantium bones, you still have to carefully construct the bones to transfer that momentum into the adamantium joints properly. This will likely limit the mobility of the jaws. Also, as a general principle, momentum is bad in the head. If mismanaged, it tends to lead to concussions as the squishy brain impacts the hard bones. If you fire small nail like objects into the prey, they have less momentum and focus all of their penetrating energy on very small points.
You obviously wouldn't want to leave a nail in the body of the enemy. That's inefficient. So you probably want it to be more like a [captive bolt pistol](https://en.wikipedia.org/wiki/Captive_bolt_pistol) used in the slaughter of cattle. The nail would fire forward and then be retracted.
Retracting could also be an issue. After all, this technology is designed to fire nails into concrete so that they stick there well enough to hold up the frames of houses. Obviously you'd want muscles with a lot of mechanical advantage, like the muscles which pull back on the [mantis shrimp's hammers](https://www.youtube.com/watch?v=LXrxCT0NpHo). However, to play it safe, I'd also have a second explosive charge ready to explosively retract the nail if it does indeed get stuck in something horrible like concrete. One would not have to worry about it getting stuck in reverse because, unlike the attacking case, we get to craft precisely how the nail will impact at the point of maximum retraction.
If you're doing all of this, you probably also want to maximize lethality. You might as well also make the nail slightly hollow, and have an explosively generated gas charge ready to inject like t[he Wasp Knife](https://www.youtube.com/watch?v=XjPIS68DO4Q) does.
Thus, the full process would be:
* Jaws clamp down like normal on prey
* Explosives are triggered to drive several nail like adamantium teeth into the enemy.
* Once there, secondary charges are fired to generate gas to drive down the hollow teeth into the prey.
* Muscles try to retract the teeth, using maximum mechanical advantage to do so.
+ If the muscles cannot retract the teeth, a secondary charge can be used to effectively fire the teeth back up into the skull. Thank goodness for adamantium skulls!
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I think I could believe a story with this set up, since mother nature pulls some bullcrap similar to your creatures. [Bombardier beetles](https://en.wikipedia.org/wiki/Bombardier_beetle) utilize chemical explosives as a defense mechanism and woodpeckers deal with freakish amount of force being self applied to their bodies, so truth might be as strange as your fiction. Heck, [mantis shrimp](https://video.nationalgeographic.com/video/worlds-deadliest/deadliest-mantis-shrimp) punches have a snap that can probably rival the most overpowered mousetraps on the market.
Keep in mind that the fish that make up their diet might have to be durable, as well as fast, to justify this evolved specialization. Otherwise it would be smarter to evolve something to spear the fish, like a crane's beak or a preying mantis' claw-things.
A magic weed that produces explosive chemicals would probably be a good addition to this story as a way to make your boom-agators seem more plausible. Not only that, but you could have your character try and make weapons out of the weeds, only to realize he can't get the purity he needs. "I'll have to take it from the gators. \*\*\*\* me."
Oh, and [peat moss](http://www.abc.net.au/science/articles/2010/07/23/2962175.htm) is a plant that utilizes explosive force to launch its seeds, so your magic weed can be justified as well.
(Huh. That is the first time I have used the term magic weed and actually ment a weed that has supernatural properties.)
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I'm building a world where all continents are Islands.
Since I was interested in giving a little bit of science backup on this particular thing, I decided that the weather was mostly windy and stormy as pointed out in here: [Would an island-covered planet be possible?](https://worldbuilding.stackexchange.com/questions/25918/would-an-island-covered-planet-be-possible) This in turn caused the main means of transportation to be completely aquatic.
If I wanted to create an airship that would be fit for an environment full of wind and storm, which would be the best shape to create it?
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## Avoid helicopters and airships. Try the WC-130 or WP-3D.
First, airships are not fantastic choices for maneuvering in high winds. Helicopters are bad enough, but [airships are large and slow](https://aviation.stackexchange.com/a/3850/7810), meaning that there's even more drag on them from high winds. Adding stabilizers can help, but if wind direction changes quickly, steering the ship could be difficult, and flying could be dangerous. That's one reason why airships with very high passenger/cargo capacity have so far been unsuccessful.
Instead, use something more stable: An airplane. The two main airplanes used for [hurricane hunting](https://en.wikipedia.org/wiki/Hurricane_hunters) are the [**Lockheed WC-130**](https://en.wikipedia.org/wiki/Lockheed_WC-130) and the [**Lockheed WP-3D Orion**](https://en.wikipedia.org/wiki/Lockheed_WP-3D_Orion). Both - although especially the WC-130, which is a fairly hefty aircraft - are equipped to fly straight through a hurricane, not just over it. The WC-130 has [a fairly long range](https://www.lockheedmartin.com/en-us/products/c130/wc-130j-weatherbird.html), of over 1,800 miles, and can reach top speeds of over 400 miles per hour. There's [little to no structural modification](http://www.hurricanehunters.com/faq.htm); the planes are already capable of enduring high winds and other dangerous conditions.
The one issue you might want to keep in mind is runway length. The WC-130 and WP-3D Orion are big planes, with lengths and wingspans in the area of 100 feet. They're also heavy, and so they require longer takeoff/landing strips than, say, a light Cessna. It might be difficult to find such runways on a world of islands - although it's worth noting that [the C-130 can take off on short distances](https://aviation.stackexchange.com/q/3899/7810) and on a number of different types of terrain (including sand), and [jet-assisted take off (JATO)](https://en.wikipedia.org/wiki/JATO) could be applied, as in [Operation Credible Sport](https://en.wikipedia.org/wiki/Operation_Credible_Sport). Nonetheless, you'll probably need takeoff/landing areas of 1,000 to 3,000 feet, depending on the weight of the aircraft, especially if you're not using JATO. That, I suppose, is the one advantage of helicopters and airships.
[](https://i.stack.imgur.com/T6Tlw.jpg)
The WC-130 in flight. Image courtesy of the US Air Force and in the public domain.
[](https://i.stack.imgur.com/LsMIl.jpg)
Two WP-3D Orions in flight. Image courtesy of the NOAA and in the public domain.
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I have this character in my story who controls insects and I wanna have him travel in swarms of house flies. *why house flies?* you ask? Well, two reasons:
* When I was younger they were my favorite animal (seriously, I would make jar habitats for them and breed them).
* The more practical reason: it's more believable that if there would be enough to fly a human around town.
But there is one problem: the average person doesn't have enough surface area on their body to let 11,818,181 flies to grip him and fly.
My question is: what structure would increase his surface area to 2,954,545.25 square inches to let that many house flies grip and fly without adding any more than 30 lbs to a 230 lbs person?
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**A Peculiar Sort of Cape**
The character wears a sort of rigger's harness under his clothing with a large billowing cape-like garment attached to it. Instead of fabric the cape is thousands of sturdy threads. While thread seems weak, if enough of them are spreading out his body weight over a large enough area no single thread would need to be bearing much more than a few ounces of weight. It would also look mad-creepy. If his abilities are focused and fine-tuned enough (its magic so he can be as in control as you want him to be) he could even have them arrayed behind him in such way that they look like a massive blurred and droning set of flies wings.
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**Could an ancient civilisation create plastics on Saturn's moon - Titan?**
Much like how we forged metals and glass here on Earth... To prevent it from being impossible from the start fire can be produced using a special type of plant that can burn in Titan's native atmosphere.
The hydrocarbons are native to Titan so for example Titan has lakes of liquid methane/ethane and has huge sand dunes made of organic material in other words plastic so no need for oil.
<https://www.wired.com/2013/09/cassini-titan-propylene/>
<https://www.scientificamerican.com/article/electric-sand-how-titans-dunes-got-their-weird-shapes/>
My question is could one create useable plastics from it using the sort of technologies that a civilisation which is a sort of hybrid between civilisations like the Ancient Greeks and Aztecs all the way to the Renaissance era. But the wouldn't be able to use metals or glass. Since Titan is mainly made of water ice and organic materials so one would be limited to Native American/Stone Age-like tech.
I only have an A-level knowledge of Chemistry since I decided to study Physics at University but to my understanding most plastic require great temperature which is feasible with fire but without metal - the great pressure that most of these processes require isn't so feasible.
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Bacteria make plastics from methane without any equipment at all. [Here's one recent example.](https://www.fastcompany.com/40476430/the-shirt-of-the-future-is-made-from-polyester-thats-been-created-by-methane-eating-bacteria) Specifically, methanotrophic bacteria in Alpha-proteobacteria become rapidly filled with bioplastic in the presence of methane. I believe 60% of their biomass is plastic. It is their version of fat.
One would not need great temperatures. (a fire would be helpful but they'll have that.) One would instead need a way to harvest the bacteria and purify the plastic. It may be that some are more than 90% plastic, I don't recall, but they do fill up with the stuff.
We use these bacteria in biotech and it is the purification that is the main problem. But I suspect the answer is yes, if the people had the knowledge of these bacteria, it could be done with that level of tech.
Harder would be surviving without any oxygen! As multicellular creatures, your people will need a good electron acceptor like oxygen for their biochemistry. Nitrates (etc) aren't strong enough e- acceptors to give us (multicellular organisms) the energy we need.
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For simple plastics like polyethylene (PE) it's perfectly possible. PE is just a long chain of $CH\_2$ groups.
[](https://i.stack.imgur.com/HFTYm.png)
For some other plastics, like PVC, it might be impossible or really hard, depending on the availability of suitable chemicals, like Chlorine for Polyvinyl Chloride (PVC).
[](https://i.stack.imgur.com/Q6Hps.gif)
High temperatures and pressure make the conversion faster, it doesn't mean it is impossible without them. UV light (a.k.a let them exposed to sun light) can open the bonds and allow for polymerization, too.
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Let’s say that the tech level is that of antiquity to early medieval times and the entirety of the planet’s landmass exists as a single supercontinent. Could the local equivalent of the Roman/Persian/Mongol Empire conceivably conquer and rule over the entire thing? Or would logistics inevitably become a problem even without oceans separating the seat of the empire from its territories? Let’s assume internal politics don’t have any say in whether or not this empire collapses and that the regime is backed by some sort of theocracy or divine mandate.
tl;dr can I have a single empire believably ruling the entire world under certain conditions?
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Trivially, yes. If the [landmass is small enough](https://en.wikipedia.org/wiki/Island_country), it can easily be [controlled by a single empire](https://en.wikipedia.org/wiki/Malta).
However, that's not a very interesting answer, so **a better question is how big the landmass could be.** We can use real-life examples to see how large this hypothetical controllable landmass is:
**0-1,000,000 sq. km of land: Easily.** According to the [sizes listed here](https://data.mongabay.com/igapo/world_statistics_by_area.htm), countries today range in size from <1 square kilometer (Vatican City) to more than 1,000,000 sq. km(Russia). The average country in the world takes up about 750,000 sq. km, which is about the size of Chile and Turkey. The [Byzantine Empire](https://en.wikipedia.org/wiki/Byzantine_Empire_under_the_Macedonian_dynasty) roughly covered Turkey back in the 9th century, so these sizes are definitely possible.
**1,000,000-15,000,000 sq. km of land: Probably.** According to [this list](https://en.wikipedia.org/wiki/List_of_largest_empires), there are plenty of large empires in history. Rome, Alexander's Macedon, and the Ottomans all claimed about 5 million sq. km of contiguous land at their peak, the [Umayyad Caliphate](https://en.wikipedia.org/wiki/Umayyad_Caliphate) got to about 11 million sq. km, and the [Qing dynasty](https://en.wikipedia.org/wiki/Qing_dynasty) of China reached about 15 million sq. kilometers, [which is about a third of Asia](https://en.wikipedia.org/wiki/Geography_of_Asia#Overall_dimensions). These empires are certainly at the technological level you described, and there are plenty of examples so this size is pretty doable.
**15,000,000-25,000,000 sq. km of land: Possibly.** There are two historical land empires in this category: the Russian Empire and the Mongol Empire. The Russian Empire formed in the early 1700's so it might be a bit too advanced compared to the examples you gave, however the Mongols are the interesting one here anyway. At it's peak in the late 13th/early 14th century, the Mongol Empire covered 24 million square kilometers of land. This is [about the size of North America](https://en.wikipedia.org/wiki/North_America). Since this is the largest land empire in history, it may be around the upper limit for the size of empire at the technological level of your examples.
**25,000,000+ sq. km: Probably not.** The largest empire in history, the [British Empire](https://en.wikipedia.org/wiki/British_Empire), controlled about 35 million sq. km at it's peak. However, they cheated and used boats, which significantly sped up their empire-wide communication and logistics. Since no other empire *has* come close to this size, it is unlikely that an empire *could* come to this size without significant use of the ocean around the supercontinent. This would also require the continent to be thin or [fjord-y](https://en.wikipedia.org/wiki/Fjord) in order to let ships cover most of the travel distance.
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So, an empire easily can control an entire landmass: it's the *size* of the landmass that determines if some single empire can control it. **According to real-life examples, a landmass the size of North America seems to be the upper limit for an empire with an ancient or medieval level of logistics ability**, since nothing has gotten larger than that on Earth even though larger landmasses exist.
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While gunpowder has been rightly characterized as one of the greatest leaps forward in the lethality of weapons, guns required some companion inventions to become the dominant small arms weapon system of the current age. Since I'd rather not have guns be the dominant weapon system in the world I'm building, I'm looking to block at least some of these ancillary inventions so that guns remain messy, relatively unreliable, and decision-demanding, leaving room open still for closing to melee combat as a practical matter of course.
In particular, one of the companion inventions I consider key is the *percussion cap*: a small metal piece that holds a small quantity of primary explosive, or *primer*, that explodes when the cap is struck, initiating a propellant charge or other firing train. While stopping people from shaping metal into a certain form is certainly not a practical way to worldbuild, making it so priming explosives are a chemical impossibility seems to be like a decent approach to this problem. Furthermore, blocking the percussion cap from being invented has the desired effect -- without percussion caps, you can't have weatherproof, high-reliability cartridges, nor can you have easily operated breechloading firearms (never mind not being able to develop autoloaders).
Therefore, I ask one question: what changes can I make to my world so that priming explosives are not discovered/invented while causing the least amount of collateral damage to other parts of the world? (In particular, biochemistry in the world still needs to be Earth-like, as far as is possible.)
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Percussion caps can be delayed but can’t realistically be prevented without serious rearrangement of history or the use of magic. The longer the time period of the delay the harder it will become to prevent the invention and the greater the distortion of reality.
The problems being the shear multiplicity of chemical compounds, other technological solutions and human ingenuity. If one compound used in percussion caps is prevented (perhaps by making Mercury very very rare so no Mercury fulminate) Silver fulminate would be discovered and used a little later. If fulminates are hand waved away somehow percussion caps could still be made with lead or Silver azides and if those were excluded there are many more Lead styphnate for instance.
Ultimately in the modern age a range of different technologies could be adapted for use as detonators involving pressurised gases, electrical ignition or the mixing of hypergolic (spontaneously flammable) materials in confined space
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Trying to prevent a technology from being created is very difficult. In general it's best to just handwave it and leave it at that.
If you need to actually stop a technology from taking root, I find the easiest way to do it is to turn to the most powerful handwavium you can get: religion. If the world's major religions all have clauses which make explosives frowned upon, its effect will delay primers *substantially*.
For an excellent example of this working in a science fiction world, take a look at Frank Herbert's Dune. Frank wanted a world that wasn't dominated by computers, so he staged a great war against the "thinking machines," known as the Butlerian Jihad. One of the outcomes from this was that every civilized planet in the galaxy was seeded with the commandment: "Thou shalt not make a machine in the likeness of a human mind." Herbert's world is rich with all of the solutions people came up with to get around this limitation, like the Mentats, but actual computers never showed up in his work.
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A civilization is very good at bio-engineering, and I was wondering if there was any kind of chemical an organism could produce which would produce viable rocket fuel. It has to do a of couple of things:
1. Work at least half as well as modern rocket fuel. Too much less, and I worry the rocket will not be able to get off the ground. As well as, is there any way to theoretically improve the efficiency?
2. The organism needs to go with the rocket. It's neat if you could create fuel, but if you can't bring it with you, your missions are going to be much shorter.
3. I would prefer that the organism would be able to convert plant matter into rocket fuel, but this is not necessary. The rocket will most likely have a hydroponic farm to feed the crew, and it would be great if the fuel-creators could eat that too. A close second would be some sort of animal matter.
4. The fuel is somewhat easy to replace while in flight. Once you get the fuel-producer up in space, it would be a bummer if you can't use that fuel.
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Living organisms can produce hydrogen peroxide, therefore one good choice seems to be high-test peroxide, or [HTP](https://en.wikipedia.org/wiki/High-test_peroxide)
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> High-test peroxide or HTP is a high (85 to 98 percent)-concentration solution of hydrogen peroxide, with the remainder predominantly made up of water. When used with a suitable catalyst, HTP can be used as a monopropellant, or with a separate fuel as a bipropellant. [...] Some significant United States programs include the reaction control thrusters on the X-15 program, and the Bell Rocket Belt. The NASA Lunar Lander Research Vehicle used it for rocket thrust to simulate a lunar lander.
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In the monopropellant usage your organism just need a suitable enzyme to decompose HTP into steam and oxygen.
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See Stage Rockets in Larry Niven's Known Space series. They are remnants of the Thrintum/Tnuctipun empire. See "A relic of empire" and a brief mention in "World of Ptavvs"
These were the equivalent of the booster rockets on the shuttle.
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Half as well isn't very good. A decrease of 50% of specific impulse takes effect in the exponent of the [Rocket Equation](https://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation) (It looks innocuous until you solve for Mo)
There are reasons that 60 years after Sputnik we still don't have reusable single stage to orbit rockets.
To create fuel in space, you *still* need a source of chemicals. E.g. to make a hydrogen/oxygen fuel you need a source of water. Mass is the problem.
In low g environments it starts to make more sense to spend a lot more energy and far less mass. If you can use solar energy concentrators to boil asteroid rock, then use a linear accelerator to accelerate ionized rock vapour to appreciable fractions of the speed of light, you have a ship that can cruise the solar system. You also have a good weapon with that exhaust.
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You might want your animal to somehow secrete a combustion chamber of erbium crystals (extremely rare element - so you might have to explain where the food comes from), and generate very high frequency bioluminescence in the range of gamma radiation. Then your animal could generate fusion from heavy water (which also should be on the diet) (<http://www.neofuel.com/neutralize/Steinetz%20mse%20catalyzed%20beta%20and%20neutron%20autocatalysis%202017%2006%2026-1551.pdf>)
Another alternative is that the animal eats antimatter. It is produced in extremely tiny quantities naturally around planets where incoming cosmic rays first begin to interact with matter. The antimatter could potentially be packaged safely in buckyballs (graphene nanoballs). Assuming your animals were farm-fed from some industrial facility that produces antimatter on a larger scale, they could react the fuel with almost anything.
In terms of weighing alternatives, I think specific impulse is less important than mass energy efficiency. With chemical, it tops out at almost zero; with fusion, the top end is not quite, but close to 1%; with antimatter this could approach 100%
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Many common rocket fuels can be created by biological processes. In the case of fossil fuels, they actually were.
**Bipropellant fuel**
Hydrogen is the most efficient rocket fuel by mass, which is often the most important factor for a spacecraft. It has several major drawbacks, though: it needs to be cooled down to ridiculously low temperatures, has an abysmal density meaning giant tanks, and has a tendency to boil off as well as to escape pretty much any container with time (H2 molecules are so small they slip between the tank's atoms). It can be produced by bacteria, or the civ could use biotech to reproduce today's industrial processes, which for many are relatively straightforward.
Kerosene (specifically highly purified RP1), on the other hand, is compact and doesn't need to be cooled down. It is quite a bit less efficient per mass than hydrogen, but those make up for it enough that it is a rather common rocket fuel. It comes from oil, which has naturally formed from dead organisms, and it is possible to recreate this process artificially from, say, algae. We don't do it today because it would be too expensive, but it may start to appear once we run out of fossil oil - nothing a biotech civ should have any problem with.
Between those, there is methane. Not as compact as kerosene, but not too bad either. Needs to be cooled down, but far from the extremes of hydrogen. Performances are also between those, as its hydrogen ratio in the molecule is higher than kerosene. Methane is a well-known organic byproduct.
Note that gaseous fuel is almost always cryogenically liquefied instead of compressed, as this allows greater density and doesn't require impractically heavy tanks.
For early rockets, ethanol can be used, and such a civ should have ample alcohol-producing capabilities. It is very easy to use as fuel compared to the others, but its poor performances mean that it will be only used for initial experimental rockets (think V2).
**Bipropellant oxidiser**
As oxidiser, liquid oxygen is the obvious choice. It is cryogenic (though not as extremely cold as hydrogen), but is the most efficient practical oxidiser.
If you hate the world and everything in it, you can use fluorine (aka burning cancer). The stuff is such a nightmare to handle even the Nazis thought it was too dangerous. It will burn anything it touches, produce highly toxic fumes and durably contaminate the zone. There are probably bacteria out there that can produce the stuff, but frankly the world is a scary enough place as it is.
Hydrogen peroxide is not as efficient and will try to explode when given the opportunity, but it is liquid at room temperature, compact and can be useful if you want a simpler, non-cryogenic rocket. Again, there are some organisms that produce it, so it shouldn't be a stretch for a biotech civ to produce it.
Nitrous oxide can also be produced biologically, and fills somewhat the same niche as hydrogen peroxide. You need to cool it somewhat, but not as much as other cryogenic fuels. It is a bit less compact as hydrogen peroxide, but is very stable.
**Monopropellant**
For things like satellites or small manoeuvring stages, they will want monopropellants, that is rocket fuel that doesn't need oxidisers. You only heat it and/or flow it against a catalyst and it will burn by itself.
Hydrogen peroxide and nitrous oxide can be used as monopropellants. Performances are mediocre compared to bipropellants, but small crafts will need small, simple engines and monopropellant engines are much simpler, and easier to be made tiny.
If you think Nazis were tree-hugging sissies, you can also explore chlorine trifluoride, which is the evil version of fluoride. It will burn water. It will burn sand. It will burn glass. It will burn spontaneously given the slightest provocation (for example, looking at it sideways). And of course its fumes will cancerously burn nearby lungs and contaminate the zone forever. But hey, at least it is efficient at it.
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I am currently worldbuilding a setting on a [hot eyeball](https://planetplanet.net/2014/10/07/real-life-sci-fi-world-2-the-hot-eyeball-planet/) world with the habitable zone located around the terminator rim between desert and ice sides.
* The world is terraformed with terran-descended flora/fauna.
* Technology is late-Roman period (A.D. 200-350).
Research about tidally locked worlds suggests the main problem for life and civilization would be the hurricane force winds constantly blowing across the planet. I am trying to come up with a way to reduce the winds. I might end up using a handwave (magical nodes that stabilize the weather). But before that, I would like to see if there is a mundane workaround.
One idea I have is a wind-break mountain range ringing large parts of the habitable area (though not all) of the terminator.
**What would be the best option for protecting the inhabitants of a tidally-locked world from the weather?**
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First, what's the problem with a tidally-locked world? Basically, one side of the planet will always face the system's star. That side would get very hot. The opposite side, being locked in a position of permanent night, is very cold.
Let's not worry about how hot or how cold it is on the respective sides for the moment. The important point is that one of the basic laws of thermodynamics says, I'm paraphrasing here, that heat travels from hot zones to cooler zones. This will happen by whatever conductor(s) is(are) on hand. In this case, the atmosphere will do a great deal of work here. That makes wind. Generally speaking, the hotter the light side is in relation to the dark side, the stronger the wind will be.
So, if you want to kill off those winds or at least slow them down on a planetary level, you have to do something about that temperature differential. If you have technology to terraform the planet then you could also, while you're at it, add a Solar Shield and a Solar Mirror to the mix. I would argue that it may even be easier to do that than try to build reliable protection from the winds on a settlement by settlement basis.
In this case, the Solar Shield I envision is a circular mesh deployed at the [L1 point](https://en.wikipedia.org/wiki/Lagrangian_point). It would not stop all the light but it would block a percentage of it. The shade lowers the temperature on the light side. Also, a mirror deployed at the [L2 point](https://en.wikipedia.org/wiki/Lagrangian_point) could reflect some light to the dark side. If the makers are smart about it, they would make these two objects complement each other. In other words, the heat energy blocked by the shield on the light side would equal the amount of heat delivered using the mirror on the dark side. Indeed, a step more along that line of reasoning would allow the devices a limited amount of "intelligence" and the ability to give the tidally-locked world real day/night cycles.
So, the version 2 shield is not a mesh but a material that has two states, fully opaque or partly opaque. The control mechanism being how much of an electric current is running through it. [This is similar to composite materials used today in high-tech windows of tomorrow.](https://atelier.bnpparibas/en/smart-city/article/smart-buildings-photosensitive-windows-set-reduce-energy-costs) Version 2 of the mirror would likewise be covered with the same material but with a range of fully opaque to clear. That would allow the mirror to go dark as needed. With both devices in place, the light side could experience night while the dark side got day.
Regardless of which versions you use, the end result is to bring the world's areas of extreme down to a more moderate level. That would help with the wind problem. With these great extremes the heat exchange, which is the source of the massive winds, becomes more moderate. That makes the winds more moderate.
Now, I'd like to point out that success here may not cause the wind to cease completely. It is more likely to bring the winds down to a more manageable level. A level that would allow the individual settlements, at a much lower tech level, to build things that could survive the wind.
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I've heard that the city of New York has it's own micro-climate which has come about due to the many tall buildings, polution and other factors.
A little digging led me to [this](https://www.britannica.com/science/microclimate) article with a quick skim suggesting that many factors can influence micro-climates. Your colonists might have had more success by creating one or two areas with moderate climates through the placement of artificial mountains or hills, tree-breaks, bodies of water and so on before branching out little by little to create new areas as their population grew.
Areas closer to the desert side of things might benefit from a mountain (and some other things - no one solution would be simple), while an area closer to the cold side might have a large forest tract.
Even in a culture similar to the late-Roman era, sophisticated knowledge on this could be easily known/available, as handed down by ancestors and refined over generations, because face it humans adapt their surroundings much better than they adapt to their environment.
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Much depends on how much air you have. One of the stable solutions is that all the air freezes out on the dark side, leaving only what is the vapour pressure at the darkside temp. Not much.
With enough air it rises at the sub solar point rushes around, sinks at the dark side, and returns. Depending on how fast this cycle runs you can get anything from constant icy wind to something bearable.
I suspect that the amount of water in the air will also make a huge difference. Water has large latent heat. If you have rivers that flow all the way to the subsolar point, then much of the heat can be transported by water vapour instead of by wind. Since the habitable band is substantially cooler than the sub-solar point I would expect nearly constant rain there, with attendant erosion. If you can even transport half the heat by water vapour it cuts the volume of air moved by a factor of 2, turn hurricanes into mere gales.
A constant cloud layer also moderates the temperatures, reducing the amount of heat that has to be moved.
Another solution would be a pair of planets or a planet and moon tidally locked in orbit around the star.
Or have the planet tidally locked around a brown dwarf or other minimally hot object, and that pair orbits around a more conventional star. The conventional start provides most of the energy. This has a problem of making for longish days
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First of all, I have not seen the show, only read the comics.
In that scenario, there are four very important things to know about the zombie apocalypse.
1. No matter where it originated, the virus travels by air, and faster
than people. It will infect the entire landmass, maybe the entire
world, within a very short delay.
2. Being infected makes no difference whatsoever before you die, but
when you die no matter the cause you will turn into a zombie within
24 hours, sometimes much faster.
3. Any zombie bite will kill you within hours.
4. There is no known cure to either being alive and infected, or full
blown zombie.
Let's assume that the people responsible for the original outbreak were both prepared and responsible. They reacted fast enough, either by alerting or being the autorities, so that everyone got the information quickly enough to avoid a complete disaster like in TWD.
They couldn't prevent the infection, but zombies didn't take control of the country or world, not even a city.
After that, since everyone turns into zombies on death, but it won't take you by surprise, I guess zombies will become a notable risk in society.
How would society adapt to this new zombie element added to regular deaths?
I assume funerals would be very different, considering that even by killing the zombie, you'd still have a much more disgusting corpse, therefore open caskets would probably disapear.
I am asking specifically what measures could a country take, whether it is by law or by religion, to avoid mass murders every time someone dies? What habits would people adopt to react to this important change from a safety point of view? Is it even possible to avoid complete anihilation, assuming we know what we're dealing with from the start?
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* Predictable death locations (nursing homes, hospitals) seem likely to be prepared with on-site armored crematoriums, security doors, and plenty of well-equipped (armed) orderlies. Ambulances and hearses will look quite different!
* Since sudden or surprise death is the big threat, look to pay higher taxes for more police and containment teams.
* Manslaughter, negligence, or suicide resulting in further zombie-caused havoc will be treated much more seriously. Drunk driving or drug abuse, for example, present a much higher risk to others if a simple crash or overdose explodes from a one-person tragedy to a chain overwhelming a neighborhood.
* Rise of surveillance states: People and their vehicles with monitors so nobody dies unnoticed or unlocated. Well, we know the Census will be accurate! Also, universal (perhaps compulsory) health care and behavioral health monitoring...now that one severe depression is a risk to an entire community. You can live without a monitor...on the Reservation.
* One imagines various kinds of swords will come back into fashion, and various anti-zombie techniques will be added to school gym classes.
* Look for in-person funerals to be replaced by post-cremation memorials and wakes.
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Building codes would be upgraded, doors and structures would be rated to resist a single zombie assault for a set time period, so that if someone dies in their sleep or is otherwise turned, they are easily contained and don't break out and kill the entire household.
Along similar lines I imagine people wouldn't want to share sleeping spaces as much, whether married couples or otherwise; expect solitary sleeping accommodations to be preferred, barracks or high occupancy dorms would be the worst possible environments.
Expect bullet proof helmets or other head wear that would prevent easily subduing a zombie to be outlawed, or outfitted with required weak spots.
Smart phone heart monitors with alarms would likely be extremely popular, the extreme end of this type of device would be an automated head mounted (or implanted) small explosive device to destroy the brain after death is detected.
I wouldn't expect everyone to be trained or equipped to eliminate zombies, some would (I would expect general population rates similar to first aid or CPR training), but many people would be psychologically or physically unable to perform the task. I would expect the standard method employed and trained for the masses would be containment; isolate and avoid the infected and call for help.
Expect weapons designed specifically to kill zombies to be developed, marketed, and in common distribution and usage.
* Zombie specific ammo designed to penetrate the skull, but minimize collateral damages.
* Knives or other piercing tools.
* Bite and scratch resistant clothing.
* I would expect something like a [shark bangstick](https://en.wikipedia.org/wiki/Powerhead) to be the preferred tool, basically a stick with a shotgun shell on the end that fires on contact: apply this end to zombie head to destroy brain.
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Fitbit would come out with a new model of health monitoring wrist bands called the GoneGong which would monitor its wearers heartbeat and sound a klaxon when the wearer dies.
The deluxe model would come with a length of razor wire in the strap which can be used to garrote/decapitate the wearer should less sanitary reanimation prevention techniques are not available.
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I've been spending a lot of time developing aliens for a comic I'm working on, in the skeletal structure department I've run into a bit of a roadblock, how to design a spine for a species that is kind of humanoid, but weighs several hundred pounds more. The spine also needs to be transferable to members of the same species that are over 30 feet tall, living in a somewhat reduced gravity.
My current ideas are; making the spine segments wider, thus providing more support, and adding muscles to reduce stress; adding a secondary spine, so instead of having a single spine in the middle of their back, they have two spines running in sideways arcs up their back (this wouldn't be much of a problem as far as making the torso wide, they already have very broad shoulders and such); lastly, I am thinking of removing the spine and replacing it with something that would resemble an oobleck spine, so it is soft and malleable (which would negate the problem of destroying the back over time as it would be a flexible tube-like organ), but then during times of combat there is a system of muscles that squeezes the spine and causes it to harden.
Are any of these feasible or useful in any way?
edit: Giraffe spines have the same number of vertebrae as a human neck, but they are far larger, and seem to lock together like puzzle pieces. could using less, larger vertebrae be helpful in this situation? I imagine it would make the spine stronger, but less flexible.
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**Vacuoles and turgor pressure!** ([what's turgor pressure?](https://en.wikipedia.org/wiki/Turgor_pressure))
A firm, fresh cucumber is firm because it is full of water. As it dries out (wilts), it loses water content and becomes weak and rubbery.
A functional spine could be made from a tube composed of a network of vacuole-rich cells which, when properly hydrated, could remain firm and erect indefinitely. However, to do that these cells would need to possess a structure analogous to a plant's cell walls, because the amount of turgor pressure a plant cell's full vacuoles exert on the plant cell (to provide firmness and structure) would cause an animal cell's membrane to lysis (burst) and the cell would die.
One problem with this suggestion is that we observe changes in turgor pressure in plants and fungi that just go much slower than we'd want our new spines to be able to adjust themselves for motility purposes: a solid tube of these cells won't do the trick. So, you could build a network of vertebrae out of these vacuole-rich cells instead of from bone that basically functions the same way, but is much more "plastic" and faster to heal/self-adjust than we are accustomed to. (Imagine a slipped disc working itself out in 30 minutes!)
I assume by "transferable" you mean scalable, i.e. the same design will work for 30 foot tall humanoids in reduced gravity. I guess a 30 foot humanoid would have a ~10 foot spine, and while that would certainly be pushing it for a continuous structure (plants that grow to 30 feet tall do so with woody cellulose, i.e. a very thick cell wall offering no medium-term motility, in the way a vine might curl around a branch in an afternoon), I see no reason the vacuole-vertebrae would not work in this case.
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Why do you need a spine as we have it?
The spine provides a flexible torso, and an earth life, this developed because locomotion in earlier forms required the undulation of the entire organism. Look how a snake moves, or a fish swims. In terrestrial mammals, the spine and back are an important part of locomotion as well, as they add power to the stride.
If you are willing to forgo having a flexible torso, and have a rigid torso, you can have a single support column, that runs from the pelvis to the neck. Alternately, the bone column could be wide and hollow, with all the venerable bits inside, like an exo skeleton, but not necessarily a shell, it could still be covered with skin and hair/fur/feathers...
Look how robot torso's are envisioned, they seldom have a flexible spine. Think "Bender" from futurama.
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Human spine isn't what you want to take your inspiration from.
In addition to have evolved to allow and ease locomotion for fish-like creatures, all our land dwelling ancestors were quadruped. To sum it up, our spine is optimized for horizontal support and lateral movement of any part of our body, which is definitely not how you would define humanoid standing.
In short, our spine is a suspended bridge and what you are looking for is an architectural column. The first allows lateral freedom and is strong and supportive as long as it's horizontal while the later offers support as long as it's vertical.
If you want to be rigorous, concentrate on the environment and lifeforms of your planet :
* What are the environment characteristics ?
* Where did the first complex lifeforms appeared ? Therefore, what did they look like ?
* What these lifeforms eveolved into ? Which subsequent steps and forks did their evolution took ?
* And finally, what does your creature look like, given the evolutive path its ancestors endured ?
That way, you'll get something that is supported by their environment and they will look like the other creatures on the planet. Our spines grew in fishes that were the first vertebrates and every vertebrates have similar spines now. It's so old and basic in our evolution that it mostly didn't change, whether it was reptiles, dinosaurs, birds, mammals or whatever. That's why our way of standing and moving is so shitty compared to how our spine works - and why so many humans have back issues.
I hope it gave you some food for thought and a begining of solution.
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Our current spinal architecture is pretty scaleable, easily capable of handling larger humanoid body masses. After all, toddlers of 30 pounds are skeletally very similar to adults of 250 pounds with no significant issues. Many modern back issues are not due to an inherent structural flaw in the spine but rather the poor ergonomic situations (a dozen hours a day sitting slouched over in an office chair/car seat) combined with poor physical fitness. It is the consequence of maximal adpative flexibility when it is subjected to prolonged repetitive stress. There are also other biological reasons why humans at the upper end of the size spectrum have issues, not really due to spinal problems other than folks with global bone growth issues. So when scaling humans to 30 feet, even in reduced gravity, you have other problems to consider, not the spinal structure.
The spine provides not only structural stability to the upper body, but also shock absorption, flexibility to the torso/head, and protection for the spinal cord. Simply making a solid or rigid spine would transfer a LOT of impact stress to our hips or skull. The spine is also the attachment site for many major muscle groups, so you can't just do away with it or duplicate it without also redesigning the entire musculature system.
Nerves really don't like to be pinched so you also can't have a fluid spine that goes rigid because you could easily compress nerves (the nerve outlets wouldn't be as static and protected as they are with a segmented spine). In a surprise stress situation you might even lose control of limbs if you were in an awkward position when your spine suddenly tightens up under muscle contraction and pinches off the motor nerves to your arms or legs.
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I'm imagining that a group of humans was transported to a different planet almost 100 thousand years ago.
The planet is similar enough to Earth that they can survive, and already had other earth-based life forms living on it which had arrived there many millions of years ago, but nothing comparable to the level of human intelligence.
Any traits you associate with vampires are cool as long as you can explain them.
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**Vampires are vulnerable to light and are pale skinned**
This planet (or the area the vampires live in) could be hot. Maybe it is slightly closer to the sun or it has greater concentrations of carbon dioxide or other greenhouse gases. This makes daytime too hot for most creatures to be active so they are primarily nocturnal. This forces vampires to become nocturnal for hunting etc. other time they begin to produce less and less melanin. Couple this with a low vitamin D diet and vampires will become very pale skinned in order to get the maximum vitamin D at dawn/dusk to make up for the lack during the day. This would give them no tanning ability so they would burn instantly on direct sunlight.
**Vampires are stronger/faster than humans**
If the vampires maintain a tribal hunter/gatherer society then they will be more athletic than most humans. This advantage could be increased to supernatural levels by giving their planet slightly higher gravity. This would mean the vampires are used to jumping and running being harder than it is on Earth so they would find jumping on Earth, lifting in our gravity and (possibly) running easy.
**Vampires can see at night**
Earlier we made vampires nocturnal. If we increase the number of rod cells in vampires. Some humans do have increased rod cells and in nocturnal humans more rods would be an advantage. This would let them see in lower light conditions, probably by moonlight. It would also leave them blinded by too high light levels.
**Vampires drink blood**
If the world they live on is a hot, fairly dry place then prey will be scarce. The vampires need to maximise what benefits they get from prey so will drink the blood to avoid wasting it. Furthermore if the diet is low in iron then drinking the blood of an animal/other vampire/human could be how they counter that.
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One of the peculiar traits of vampires is that they are photophobic.
The group of deported humans carried the genes for [Porphyria](https://en.wikipedia.org/wiki/Porphyria).
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Due to the [founder effect](https://en.wikipedia.org/wiki/Founder_effect), the resulting population will carry the same genes and will have to live secluded from daylight, resulting in them being *nicely* similar to vampires.
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If I were attempting to explain it, I would start with how humans got to the planet in the first place. Given that most habitable planets are very far away, the humans travelling from one place to another would either need to have children in space, learn to travel very quickly or find a way to live much longer. The latter is where you can derive long life from by mentioning the science behind telomeres (which degrade as we age to the point of death), telomeres are sections of your DNA that protect all the important stuff, scientists have suggested that finding a way to halt or reverse the degradation of telomeres may hold the key to aging (at least in part).
Related reading: <https://www.tasciences.com/what-is-a-telomere/>
Once you have the long life as a result of youth you can then go further into the concept of DNA manipulation for space travel, talking about how muscles degrade in space, a solution to this could be to alter the DNA so that the muscle cells are more resistant to low gravity or even completely gravity independent. This would in turn mean that any landing space travellers would have a greater level of strength in comparison to the average human since most of your muscle mass comes from earths gravity and your need to resist it.
Related reading: <https://www.nasa.gov/mission_pages/station/research/experiments/245.html>
Now that we have established long life and great strength, you need a reason for the vampire population to require extra sustenance, you could justify this by creating a reason why the DNA treatment your humans received for space travel leaves their cells unstable, for example the muscle cells could require hormones or some other chemical to keep them afloat. If we go with hormones for the sake of an example, you could have one of the initial settlers developing a
hormone deficiency, requiring that they take the hormones from another by drinking blood etc, but once they drink the other settlers blood, the disease causing the hormone deficiency leads to the bitten settler developing the same deficiency.
The latter is quite sci-fi and will need some imaginative explanation but it's doable, in this example the long life could prevent dying completely (see: <http://news.nationalgeographic.com/news/2009/01/090130-immortal-jellyfish-swarm.html>), the muscular degradation due to a chemical deficiency would mean that drinking blood heightens strenght and not drinking it reduces strength to little more than an infant (see: <http://www.nhs.uk/Conditions/Muscular-dystrophy/Pages/symptoms.aspx>) and you could throw in explanations for multiple other abilities.
Other ability explanations include:
* Psychic - Cybernetic spinal chip implants, review the work of Professor Kevin Warwick for plausible explanations (see: <http://www.kevinwarwick.com/project-cyborg-2-0/>), although the professors work is still in its infancy in comparison to our examples, a neural implant and computer security could be used to explain breaking into someone's thoughts.
* Flying - Could be related to the muscular resistance to gravity, you could even have the cells generating gravity if you like (see: <https://home.cern/topics/higgs-boson>) using the higgs boson could give you a plausible excuse.
* Aversion to sunlight - Related to space travel again, chloroplast genetically inserted into cells to produce solar food for space travellers travelling vast distances, the muscle cells could produce excess carbon dioxide when not receiving enough of the chemicals that the vampires need to survive. (See: <https://www.nature.com/scitable/topicpage/plant-cells-chloroplasts-and-cell-walls-14053956>)
All of your vampires could have no idea why they are what they are, a hundred generations down the line from their space exploring ancestors they may have no concept of DNA modification etc. All of these traits could be developed naturally too, in the same way that the Turritopsis dohrnii developed its own immortality in nature, and the same way that plants developed their ability to digest sunlight.
I hope this helps!
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Ok, so this is an very odd little question.
I've been working out the economy of an industrial age world; figuring the major industries, trade routes, etc. I have a tropical region I was considering putting a lot of guano mines in. In the real world, South American guano was prized as a valuable fertilizer. As supplies ran short, we turned to artificially synthesized ammonia instead.
It's not totally clear to me whether this was to satisfy demand, or because ammonia synthesis is in some way just that much more competitive; whether it results in a superior product, can be made faster and in larger bulk, costs much less to produce, etc. etc.
So, in a world where ammonia synthesis has recently become possible (in the last couple of decades), how likely would it be to seriously cut into an otherwise thriving guano mining industry?
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Ammonia can be synthesized from atmospheric nitrogen by the [Haber process](http://www.chemguide.co.uk/physical/equilibria/haber.html). But nearly as important as nitrogen is phosphorus (as phosphate) and you cannot make that out of air. You need a mineral source or guano, which contains nitrogen and phosphorus.
The phosphorus content is what kept guano competitive with synthetic fertilizers into the mid 1900s.
Other reasons guano might stay competitive
1. Nationalist protectionism. If a competitor state houses the industry with a secret method for NH3 production, I might tax imported NH3 to reduce profits for that industry and its parent state. This will make my domestic guano industry more competitive.
2. Abundant local supply of guano and well established supply routes. People like to do things the way they are used to doing them.
3. Synthetic ammonium nitrate fertilizer can be dangerous to transport.
from <http://highschoolenergy.acs.org/content/hsef/en/how-do-we-use-energy/history-of-nitrogen.html>
[](https://i.stack.imgur.com/WyYuu.jpg)
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This is for a story line that I would prefer to be based on known science as much as possible.
Is there a known compound that can phase shift from gas to solid or liquid, or the other way around, in room temperature, when a relatively small amount of electricity is applied?
With "a relatively small amount" I am thinking of something like what can easily be obtained e.g. from an automobile battery.
Alternatively is there any thoughts on what such a compound could be based on? (In this case, instead of naming a compound I could use some description of how it was created.)
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You can boil water with adequate voltage. The water offers resistance to the current. As with anything that offers resistance, the current will heat it up and eventually it will boil.
Here is a video of a person boiling water after making homemade electrodes out of razors.
<https://www.youtube.com/watch?v=q2r0GMVAWyI>
Getting a gas to condense back to a liquid by adding energy is a tall order.
Another option is technically not a phase change of a single substance, but a change of a liquid to a different gas and back again: electrolysis of water to constituent hydrogen and oxygen, then electrically catalyzed combustion of hydrogen and oxygen back to water.
You can electrolyze water (H2O) into hydrogen and oxygen gas by passing a current through it.
[](https://i.stack.imgur.com/NG8DN.gif)
<http://www.instructables.com/id/Separate-Hydrogen-and-Oxygen-from-Water-Through-El/>
You can turn the hydrogen and oxygen gas back into liquid water, again by passing a current through it. The voltage at sufficient energy will ionize the gas into plasma forming a spark. The heat from the spark will catalyze the combination of hydrogen and oxygen back into H2O.
You can accidentally boil water with your electrolysis apparatus if you do not pay attention and you deplete the electrolyte. As you deplete electrolyte, resistance of the water increases and it heats up.
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Without knowing *why* you want this, it's hard to give a proper answer. As Will mentioned, direct electric boiling is possible, and indirect condensation is also possible. It's incredibly inefficient and very slow.
Playing with the laws of physics gives you a much more rapid option, but with significantly more equipment needed.
Water turns to vapor when it boils, but ALSO at lower pressures. (Technically, it just boils at lower temperatures at lower pressures). So, you build a container that can change its interior volume. Put the water in when its "compressed" and then have it decompress. With enough of a pressure difference, the water will boil into vapor. Recompress, and it'll condense back into a liquid.
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I've seen references a handful of times to the fact that a toroidal world is *theoretically* possible but realistically won't form naturally. That gives me some thought: What objects are possible, but wouldn't naturally exist? Something that, if we came across it, we'd be able to immediately go "Someone built that."
To be complete, I am **excluding** megastructures such as Dyson Spheres, Ringworlds, and the like. I want weird things, like a planet set up in an orbit that's too "Perfect" or the above torodial world. To be more complete, the objects in question should be easily identifiable as artificial by simply existing, not by what's on them
**Additionally** I am similarly excluding the ***how*** of the object. Putting the planet together, or moving stars to a specific orbit, is not in the scope of this question. Presume that whoever built it had an unlimited budget of time, energy, and resources.
**Further Clarification:** Said object must be easily visible from the edge of the system. Assume that the object is being detected by a ship just entering the system via a hyperlane or grav point or some similar specific-natural-point to specific-natural-point FTL system.
I am looking for the most unquestionably artificial object that can scientifically exist. Something that one look from a star system's width away makes you go "Someone made that." The object shouldn't be larger than a planet and should be made of "natural" objects - No refined metals or other things. There also shouldn't be any scanning or exploration required to determine its nature.
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Terry Pratchett's *dark side of the sun* has several, they are called joker artifacts and are the leftover signatures of a precursor races. examples include, a stable ring of mutually orbiting stars, a protostar with inside out planet inside it, a neutron star core that has had tunnels cut through it creating a gravity maze, and the planet Band described thusly.
"Band spins on its axis so fast that the equator has a noticeable bulge to it. It looks like a solid gas giant with a twenty-five thousand mile wide band of mountains at the equator, edged by two strips of of grassland which are edged by two strips of sea which end at the circles of ice on the poles."
It appears to be a planet sized wildlife preserve.
It also contains the First Sirian Bank a 7000 mile tidally locked asteroid composed of a combination metal impurities and fault lines to create a sentient supercomputer powered by the thermal gradient between the light and dark side.
The trick is to think of something that is technically possible but just so extremely unlikely it could never happen naturally. Like planet surrounded by moons make of regular geometric solids or a planetary system where each planet is identical.
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/I am looking for the most unquestionably artificial object that can scientifically exist. /
An artifact from an unfamiliar civilization might be mistaken for a natural phenomenon. The most unquestionable artificial object will be one which echoes the viewer's own civilization. **The unmistakable thing viewed should be a reproduction of a familiar artificial thing: an artifact from the viewer's own civilization.** For example, Michaelangelo's David. Or the Statue of Liberty. The viewer will immediately recognize the object and understand that such a thing would not come into existence naturally. What is viewed is a copy of the thing, which must have been made by an intelligence copying it on purpose.
This is the method used by the aliens in the Jodie Foster movie Contact.
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A solar system showing an "ordered complexity" in the arrangement of orbiting bodies would be a good candidate in my opinion. For instance one that exhibit a highly peculiar gravitational landscape such as structured distribution of Lagrange points, or patterns in asteroid belts.
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So, as a project for an idea, I'm trying to blend sci-fi elements with a Tolkien-ish world to try something new. One of the key features of this world is a type of universal energy which has the following qualities:
* exists as all states of discovered energy, and a few exotic ones.
* can be physically harnessed into a type of matter, or more specifically crystal
* with the simple input of electrical neuron firings in the brain, can be manipulated into a desired force
* Can be exhausted to create any energy form, like heat, electricity, or electromagnetic
...This is starting to sound like Mana.
All I want to know is if there is ANY way that this isn't deniable, and if it could potentially exist.
I would like serious answers. But any helpful response is appreciated.
[Answer]
It's possible, though improbable. Let's go through the list, shall we?
* *"exists as all states of discovered energy, and a few exotic ones."* - This phrase doesn't really have any strong meaning in the physics world. You're free to make this claim if you want. Claim something about some superposition of quantum states or something like that.
* *"can be physically harnessed into a type of matter, or more specifically crystal"* Most forms of energy can be converted into a "potential energy" which in some cases is very stable. The chemical potential energy holding together then bonds of a diamond can last for millennia without breaking down.
* *"with the simple input of electrical neuron firings in the brain, can be manipulated into a desired force"* **This is the tough one. We'll get back to it.**
* *"Can be exhausted to create any energy form, like heat, electricity, or electromagnetic"* This is actually part of the nature of energy. Energy can change forms from one to another.
So, with all of this, what you are trying to create is really garden variety "energy," except for one detail: the ability for a neuron to manipulate it. That's really the only unique trait you have to worry about explaining. And maybe we can do something about it.
When building systems like this, one of my favorite tools to use is called metastability. I love using it not only because it has the prefix "meta-" in it, but because it's something that happens in real life *and* has all sorts of odd properties which border on magic.
The idea of metastability is this. Consider a cannon ball placed on a hill.
[](https://i.stack.imgur.com/Mfnh7.gif)
The cannon balls in positions 1 and 2 are stable. You can leave them there for as long as you like, and they wont move. If you perturb them a bit, pushing them a little one way or the other, they settle back down into their stable position. At all other positions on this hill, the ball will roll down into position 1 or position 2. Which way it goes depends on where on the hill the ball gets placed.
At the top is the curious point. This is the metastable point. If you do the physics, you find that a ball placed *perfectly* at the top of this hill will not fall to position 1 or 2. It will instead just remain at the top of the hill, forever. However, if the ball or hill is imperfect, or if you give the ball the tiniest of taps, it will move into position 1 or 2. This is metastability. It's not stable, but it also wont move if it's perfectly placed.
This creates all sorts of odd things. For example, you've been told that absolute 0 is the lowest temperature something can attain. Well, that's only part of the story. It's the lowest temperature a *stable* thing can attain. Metastable things can achieve negative temperatures. We've indeed created bundles of atoms hovering at one of these metastable points which, by the mathematics that defines temperature, are actually at a negative temperature. Temperatures below absolute zero are strange. Usually heat flows from the hotter object to the colder object. However, if one object has a negative temperature, heat flows from the colder object to the hotter object! Why? It's the mathematics we use to define temperature, and its just one example of many where metastable objects behave in ways which are "out of this world" for most of us!
If your "meta-energy" was stored up in such a metastable state, it could be converted to any normal energy at any point in time, simply by nudging the energy to move towards a stable form of energy. It could also be harnessed in something like a crystal, because as long as the energy is perfectly metastable, it stays that way. Of course, in practice all known metastable systems fall back down to one of the stable states, but it can take a long time. Hydrogen peroxide, for example, can take 20 days to fall from its metastable state to a ground state (water and oxygen), longer if stored properly. However, if there was something about this energy which was borderline self-aware, it might stabilize itself on this metastable state. It might appear as though this energy is "searching" for something to turn into, and waiting for something worthwhile. (I find anthropomorphizing is effective for trying to convey a magic-like thing which has physical properties). Think of balancing a broomstick on the palm of your hand. Now imagine the broomstick balancing itself in that upright position, and you've got a pretty good metaphor for this "metaenergy."
Human neurons contain a metastable pattern of their own. Its the force behind why they fire. They can go for very long periods in this metastable state before a stimulus nudges them and causes them to fire (really all I'm doing here is taking real physics and applying the term "metastable" to them when describing these states that survive for a long time and then suddenly decay). Well, what if the human neurons adapted to have a pattern which your "meta-energy" resonates with, permitting the human neurons to unleash that energy in a way which might take millions of years to unleash via random particle interactions. It's like your neuron can fire in just the right way to "convince" the self-balancing broomstick that it wants to fall to the left, or to the right.
Suddenly now your "meta-energy" is just garden variety physics-class energy, just a really peculiar variant of it. This is good because it means you're likely not to run into huge trouble with physics -- you're just using physics like normal. However, due to the metastability of this energy, it behaves in ways which most of us wouldn't think about it behaving. Toss in a little evolution of the human neuron, and you've got a complete system. The only thing that's missing is an explanation of why your world has so much energy pent up in this particular form. While our real laws of physics don't prohibit "meta-energy" of this form, they certainly suggest it should be *incredibly* unlikely. Fill in this detail in your universe if you want, or just have it be an unexplained detail. Have it be a part of your world that *infuriates* scientists by being incredibly hard to study, thus virtually impossible to explain.
You also might draw from Aristotle's theory of motion. In it, he defined two types of energy. The first is energia, which is pretty close to what most of us think of for physics-classs energy. The second is *entelechia*, which is energy spent to keep something as itself. One classic example from his works is that a fish expends energy in the form of *entelechia* to remain a fish. If a fish stops expending this energy, it quickly ceases to be a fish and becomes dead meat. It's not an easy topic to digest, so it may take some time, but it's a powerful theory for building sci-fi worlds. There's a lot of corollaries that can be drawn between his *entelechia* and such self-stabilizing metastable patterns, so if you ever wanted to drop the high-tech physics speak and go old-school philosophic with your theory, he's a good source to draw from!
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Is this an energy field created by all living things? That surrounds us and penetrates us? It binds the galaxy together? Must you feel the Meta-energy around you; here, between you, me, the tree, the rock, everywhere, yes. Even between the land and the ship.
I definitely think it is a workable concept.
[](https://i.stack.imgur.com/gfD5T.jpg)
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>
> One of the key features of this world is a type of universal energy which has the following qualities:
>
>
>
We've got a form of universal energy already and it works fine. It's called "energy". Everything (photons, neutrons, pizza) is a form of energy - we've got different "wrappers" for energy, but it's all just energy.
What you're essentially proposing is that in your universe is either :
* a second type of energy-like quantity that can change into boring-old-energy in some way
* a different kind of "wrapper" for the energy, which means it would be relatively easy to thing of pseudo-scientific ways it can interact with everything else.
In the case of the second of these (which I prefer), you're basically creating a new quantum field type - some field mediated by a particle type we don't have (or don't know about). It would interact with matter in different ways from the fields we have in our universe.
>
> exists as all states of discovered energy, and a few exotic ones.
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That's kinda meaningless. The advantage of the new wrapper type is that it's just energy and we can in principle exchange energy between it and every other type of wrapper.
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> can be physically harnessed into a type of matter, or more specifically crystal
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>
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Energy in one form converted to and from another form. No problem with the new wrapper approach (as long as you don't need the mathematics :-)).
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> with the simple input of electrical neuron firings in the brain, can be manipulated into a desired force
>
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>
Well that's tricky unless the neurons in your universe can be made in a way that gives them some way to interact with the new field (the new wrapper).
Now that's not beyond all possibility, as the new wrapper probably will have ways to interact with ordinary wrapper, like matter, but it's non-trivial, from a physics point of view, to imagine any way that *just* neurons would do this. You'd probably need to contrive some special construct in the brain, e.g. crystals with special properties, that can do this, otherwise everything would be doing it.
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> Can be exhausted to create any energy form, like heat, electricity, or electromagnetic
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>
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Well that's again a bit meaningless in physics, but we can happily (in principle) convert our new wrapper to one of the old ones with some contrived interactions.
This is more making it sound vaguely plausible, than realistic. We're in hand-waving territory and not going to get out that.
Now I did mention the alternative - a type of energy-like something that can be exchanged or mimic ordinary energy. This one has problems, not least of which is that I have no idea to even imagine this in physics terms - practically the entire basis of modern physics is underpinned by the notion that energy comes in different forms but can be converted between them (different wrappers), but not that these things are different.
However it might be possible to imagine (again plausible sounding, but possibly not realistic) some alternative energy field which can co-exist with the "real" energy field and interact with it (it has to interact to be able to do anything to the rest of the universe). It might be able to affect space-time in ways that mimic the behavior of real energy and (hand waving like blazes) somehow still remain apart.
That all sounds messy to me, and compared to the additional field (an additional new wrapper for energy) it's just hard to imagine. @cort-ammon has a good discussion of this, but I can't quite get there myself.
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Situation: A terrestrial environment on a megaworld (artificial construct). I'm thinking of how invasive species tend to dominate the ecosystems they move into--how about the ultimate invasive species?
The westbird really likes to go west. It has no territory, it is a parasitic egglayer so it doesn't need to nest. It is a soaring hunter by preference but it can live on vegetation if it has to. It keeps moving west so it's always moving into new territory whose local life isn't adapted to competing with that variety of westbird.
Given the size of the world pretty substantial evolution will occur before a given westbird's descendants complete a trip around the planet so they never actually return to an environment. Of course there are more westbirds but westbirds at a location at different times have no more genetic access than populations in different places normally do--thus they will be somewhat different, providing an ever-changing enemy for the local flora and fauna.
The weakness of the westbird is that it must be viable in all substantial environments because it will pass through them in it's eternal migration. Harsh environments will no doubt kill most of the westbirds that cross but the survivors reproduce rapidly when they reach a more hospitable place.
The big concerns I have are massive deserts (think what happens to a westbird that encounters a mega-Sahara) and large oceans (although I think this can be covered by making the birds not age so they don't die out when they hit water they can't cross in a lifetime.)
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My concern with the concept, if I've properly understood it, isn't the success of the bird itself, but more that no part of the planet would remain unaccustomed to them for long no matter what. Sure, a mega planet would take far longer to circumnavigate than Earth, especially for a small animal doing so via muscle power. Even so, it's still a round object, where moving west indefinitely will mean you come from the eastern horizon once more eventually. So no part of the planet, at least along the latitudes where this bird lives, would remain untouched by this bird for long.
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If it keeps moving then it will impact perhaps harshly on local species but not for long. Local species will adapt unless your bird has some special abilities. It can't kill off the natives it needs them to look after it's eggs. It's continually moving into places it's not used to so locals will have an advantage. It doesn't take over nesting sites or physically endanger other birds, so it's impact won't be too bad.
Invasive species take quite a few generations to make an impact, normally they're in smallish numbers and take a few generations even on small islands. The reason they have an impact is THEY DON'T GO AWAY. They eat resources and take nesting sites.
But if you must then have the birds originate in a harsh arid landscape, because then they will evolve into very tolerant of environment birds with a high birth/survival rate in good times who will eat anything other birds will. They then have a good chance of surviving as a successful species, but I don't think they'll have the impact you are thinking of.
Some butterlies like the ones in this [link](https://blogs.scientificamerican.com/lab-rat/butterfly-watch-multi-generational-migrations/) migrate for generations before returning to their place of origin, they don't really make an impact that much except briefly.
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Yes, it is possible.
You state your world is an artificial construct. A little background first: For reference, Jupiter has an equatorial circumference of about 273,000 miles; [migratory birds will typically fly 160 miles a day](https://superbeefy.com/how-far-can-a-bird-fly-in-a-day/); which means they would take about 1706 days to circumvent Jupiter; about 5 Earth years. A 2 million year circumvention would require a circumference of 116,800,000,000 (117 billion) miles; implying a radius of 37,178,594,706 (37 billion) miles. So 10 times the distance of Pluto. About 55 light hours.
Just to be clear from an engineering perspective, you are talking about a large object; even in just a Dyson ring form likely requiring more mass than we have in our solar system, and so far from its parent sun I question its utility. Either that, or your westbirds cannot manage more than a few miles a day; which makes *them* implausible, even a migrating Monarch butterfly can cover 25 miles in a day, without wind assistance.
Given your figures I infer an advanced level of technology, and given that, absolutely no reason for your construct to have deserts, oceans, volcanoes or anything else your westbirds cannot cross.
Even if this construct has been abandoned by the original engineers for millions of years (to allow for evolution), migratory patterns are themselves subject to evolutionary pressures, which can include avoiding flying over landscape that can kill the migrants: Landscape without food or fresh water, or landscape with no place to rest.
But [birds can stay aloft for six months;](http://www.smithsonianmag.com/science-nature/this-bird-can-stay-in-flight-for-six-months-straight-903069/) it is certainly plausible for your westbirds to double something we actually know exists IRL.
Another adaptation you could implement is live birth, instead of eggs. I don't think that makes it a non-bird; it is still a flying creatures with wings, beak, etc. Live birth would allow the westbird to skip egg incubation; just land and give birth. On Earth, many animals are on their feet within minutes of being born. Westbirds, instead of being born featherless and naked, could be retained longer by the mother and born ready to fly within a day; just dry out the feathers, experiment a little and off they go. Like some animals, you can have the Westbirds able to delay birth by a week or two, in order to find a suitably safe place to do it.
I think live birth would make them more independent and self-sufficient, a big problem when they are constantly entering new territory with new challenges, landscape, food, defending species and predators.
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This scheme of the moving wave would work well initially for the westward. A successful invasive predator which is not super mobile tends to wipe out all local prey and then itself suffer a population crash (e.g. cats, mongooses). The continual movement of the westbird would hit the locals hard but then the westward moves on, allowing the survivors to repopulate. Oceanic predators do this - like tuna or dolphins. The idea of a wave of predators with a huge front is a good one too: the local prey cannot escape by moving laterally because the wave is so broad.
I think that the original westbird nest parasite scheme makes it a little trickier because you would wind up with multiple waves. Having mobile young who travel with the wave and are supported by parents/siblings is more workable.
Consider if the westbird were not just predators but omnivores. They eat everything. It could be like a perpetual world-circumnavigating plague of omnivorous locusts.
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In laying out the groundwork for a series of stories I'd like to write, I'm positing a somewhat modernly-realistic take on the "well-aged human empire in the stars" type of setting the classic authors used to portray so elegantly.
I want to avoid as much suspension of disbelief by way of what advanced technology can actually do. So, I'm mostly not using mysterious MacGuffin technologies for artificial gravity, FTL and the sort.
The main suspensions of disbelief are:
A.) Fusion power has been mastered to its fullest extent, and thus energy isn't an issue for this society. This is actually pretty likely if we as a technological civilization refrain from collapse or doing ourselves in.
B.) Stable wormholes large enough for massive vessels to traverse can be created and maintained indefinitely. This isn't out of the realm of possibility, but is the most optimistic interpretation of wormhole theory of course.
These wormholes are created with no way of knowing where they'll open to on the other end. So, most, if not all, of the colonized systems, they have no way of knowing the relative location of in space. They might be in galaxies we can't even see with telescopes.
My question therefore is, would they be safe from violation of causality if they simply open up to locations too far for light to ever reach from Earth and vice versa? (Or at least with very significant light speed delay?)
Or, would they need to open to other universes altogether, that happen to have the same cosmological constant and other properties as our own universe?
EDIT:
It's been brought to my attention that this question, probably due to my own wording, is kind of hard to answer, so I'm appending some clarifications here.
1.) Travel through such a wormhole is essentially instantaneous. Any matter crossing the wormhole's event horizon arrives at the destination instantly. Obviously, something a mile long traveling a mile a minute, would take a minute for its entire length to arrive. If it helps, imagine them as three-dimensional bubbles that behave like the portals in the game "Portal".
2.) My concerns about violating causality are, as a commenter said, the pole and barn paradox. Many physicists believe that anything that could cause such paradoxes simply won't happen because it's an unbreakable rule in this (or indeed any) universe. So it seems to me that wormholes of an instantaneous nature like I'm proposing, would have to lead to destinations far enough away to avoid this violation, and avoid the time travel issue as well.
EDIT #2:
This question has more or less been answered in a comment, because I asked it without considering something they graciously pointed out about the paradox being an issue even in normal space. If they can repost their comment as an answer, I will accept it and mark this question answered.
Naturally I pick as my first question to ask on here, something so obtuse and abstract nobody wants to touch it ha ha.
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The Pole and Barn paradox exists even at sublight speed.
<http://hyperphysics.phy-astr.gsu.edu/hbase/Relativ/polebarn.html>
That is not an issue of causality; it is just a disagreement about when things occur. It says that in one point-of-view (an observer in the barn) the pole fits in the barn with both doors closed at the same time; while in the other POV (an observer on the pole) both doors are never closed at the same time. The link I gave shows that is the case even at 0.9c, which is within the laws of physics. This is a paradox even without FTL.
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An alternative writing approach: If two observers are **NOT** traveling toward or away from each other at relativistic speed, then there is no problem.
Make that a feature of your wormhole: It is impossible for it to open on anything but empty space in microgravity conditions. I'm not sure if space itself can be traveling (I don't think so...) but just in case, say the wormhole will not open unless time is passing at the same rate on both ends; it cannot be stable, and you wouldn't want it anyway: Your scientists calculate that an instantaneous change in Lorentz contraction that is greater than half the width of proton will cause atoms to disintegrate in a nuclear reaction; e.g. an explosion.
So you have no problem, neither side is traveling at relativistic speed away from the other. And as you said, no telling where they are, somewhere in the infinite universe; but all relatively at rest with respect to each other.
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I know it's an old post, and it's marked as answered. But hey, it came to the top of my feed for some reason.
You can't save causality if you allow wormholes.
If you have a wormhole connecting two events at a space-like separation, then you must make a choice as to the relative time that the join is made. If you can connect two events that are space-like separated (separated by more space than light can travel in the time difference) then there is no reason you can't connect different times at the other end. Anything that did prevent you doing so would violate special relativity.
Example: Suppose you build a wormhole that connects two points 30 light years apart, doing so in a manner that you believe puts them at the same value of time. And your buddy is moving at 0.001 times the speed of light relative to you. And he does the same. Then his wormhole and yours will be different at the ends by about 8 minutes. So you can travel back in time as far as you like by going through one, and back through the other, as many times as you like.
[](https://i.stack.imgur.com/XLoaj.png)
The only limit is, you can only come out as far back as the wormholes both existed.
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If you are willing to start with a premise that fusion is developed and wormholes provide galactic or inter-galactic travel; then you are starting from a premise that makes a lot of the quantum mechanical cookbook possible.
And that opens the door to a lot of possibilities that only appear to be a causality violation from a newtonian physics worldview.
Imagine making switches from quantum spin paired devices. Now enable your communications devices with them. Drag them through the wormhole.
You can send pictures instantaneously that the light will take years or hundreds of years to travel back home. Did you just change someones future by sending them a warning of a navigational hazard in space? Perhaps from a narrow worldview.
Mathematicians tend to create tools to solve problems long in advance of actually having a real problem to solve. Cauchy bubble descriptions of causality are an example.
"If quantum mechanics hasn't profoundly shocked you, you haven't understood it yet." - Niels Bohr
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Strange question, but then again I think this forum positively welcomes those! I'm aiming to create a campaign centred around a fictional 13th century Byzantine successor state based in the Crimea.
My main question is where, logically, it would make better sense to base this city, there are two options I can think of centred around the Kerch straits (pictured).
On the West side of the straits you have Kerch itself, the area is well elevated, the straits give it excellent defences though it is somewhat dry and water is more limited.
On the East side of the straits you have plentiful water, good farming land, however you are also bordering the steppes; any steppe hordes can sweep down and attack your city, however they would have to get through some fairly nasty swamps and rivers to reach the city.
Where should I locate it? I'm slanted towards the West side but i'm not sure if the water problem would be solvable.
[](https://i.stack.imgur.com/DNwRk.jpg)
[Answer]
If the west side's water situation is unsolvable then they might put defenses on the west side and use it for control of the strait and as a bolt hole in response to an attack from the steppes. The swampy lands might be enough to slow attackers enough to evacuate across the strait. There would also have to be enough defense in depth to allow evacuation.
So, people would live and farm on the east side. The military and, likely, rulers would live on the West side. If the granaries are on the west side, the drier climate would be better for storage. I would also put the religious institutions on the west side to reinforce the fact that the townsfolk need the west side.
If the people can evacuate across the water, steppes attackers would go through all that effort for nothing. Also, if the military gets good at water navigation, they can probably put harassing troops behind the attackers for hit and run attacks. All this is an effort to discourage further attacks. The combination of being a pain in the rear to attack and having food for trade might be enough to work out a peaceful arrangement with the nearest steppes tribe.
If the steppes tribes are too much of a threat, then most of the population can be on the west side. Then water may have to be transported up to the city. In this scenario, you only have farmers on the east side. The evacuation would be quicker that way but more effort needs to be put into water and food transport.
**[Edit]**
I just looked at the map on Google. It shows water sources and farming on the west side. It might not be as good as on the east side but, combined with farming on the east side, I think the west side can support a decent sized city. I don't get a good feel for relative elevations so I don't know how difficult it would be to get water to the city from the small lakes up there. So, city on the West and farming villages on the east sounds like a good solution if you want grain for trade.
[Answer]
You are spot on with Kerch. Why not playing along with real history and use the actual Byzantine successor state in Crimea, the [Empire of Trebizond](https://en.wikipedia.org/wiki/Empire_of_Trebizond)?
This region was called [Perateia](https://en.wikipedia.org/wiki/Perateia) and recounting its story (and how it seceded and eventually became the [Principality of Theodoro](https://en.wikipedia.org/wiki/Principality_of_Theodoro) further west) would make a great historical novel.
It's possible that reality was even wilder than whatever fiction we could come up with. So perhaps if you contacted a Byzantinologist and got acquainted with the literature about it (or even translated primary sources) you could strike gold!
Let me know, because I would look forward to read it.
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No magic exists in this setting beyond what is explicitly described in this quesiton. The setting is vaguely European medieval. The question centers around a town large enough to support a nobleman complete with his keep. The town and the immediate surrounding area have a variety of industries, most notably farming, logging, mining (iron ores), and a variety of local craftsmen.
A carpenter one day discovered that if he built a water wheel and mounted it horizontal it would turn, building up speed. Eventually it would reach somewhat more momentum than an aggressive stream would produce. A smaller water wheel with smaller paddles produces less force, and poorly constructed water wheels will eventually break as though actually being pressed on by a force of water. In fact, for nearly all intents and purposes, the wheels act like they are being pushed by an invisible stream of water.
What exactly constitutes a "water wheel" isn't clear, but if through experimentation the townsfolk determine that any wheel that looks like a water wheel and was intentionally crafted in the style of one seems to possess this effect. The less horizontal the wheel is, the less the effect is present. The further the wheel is away from the town, the less the effect is (at about 50 miles out from town the effect is entirely gone).
Effectively this creates a means of getting mechanical power like water generated power of that time, but be largely unburdened where one is getting the power (no need to be near a stream).
What effects would this new energy source have on local industry in the relative short term (<30 years)?
[Answer]
Water wheels were one of the major turning points fro humanity in moving towards machine rather than animal labour. They were used in corn/grain mills primarily but were also available for sawmills, fulling mills (cleaning and preparing cloth) and many others.
The first big advance I can think of for your town is breadth of industry. At the minute labour intensive industries such as milling corn have to be done by hand or on the (presumably limited) river bank. With the area these activities can be done in increased dramatically there will be room for more mills widening the industrial scope to include all major watermills of the period. In your area sawmills and iron trip hammers will probably be particularly popular due to the logging and mining industries.
People are inventive (evidence [here](https://worldbuilding.stackexchange.com/)) so it won't be long before waterwheels become more used in your town. One new technologies I can thing of are cranes. In your time period most heavy lifting was done by humans walking inside a giant wheel which wound a rope. Using waterwheels to turn the ropes will greatly expand your lifting capacity. Some Islamic water wheels could lift 2550 litres of water a minute so that suggests some pretty hefty lifting strength. I don't know exactly how much these water wheels can lift which should make lifting iron ore from mines easier as well potentially providing winches for tree extraction. The only issue might be getting the stuff off the waterwheel at the top if you can't stop it turning but that issue should be resolvable with some sort of brake or coupling/uncoupling axle. The crane would also obviously be useful for building stuff. See Guedalon castle, France for an example of the classic medieval hamster wheel cranes in action.
A slightly less likely technology would be the first cars. If a waterwheel were attached to a (larger) normal wheel then you would have a self propelling car. Whether these would replace carts I don't know as I suspect their would be a lot of issues with building them but it is definitely a possible technology.
I suspect I have missed a lot of potential applications such as military applications (not really useful in a small town) and other civil ones.
[Answer]
# It quickly becomes a large city
This sort of concentrated mechanical power happened in Roman times. There are at least two known concentrations of water-powered mills at [Barbegal](https://en.wikipedia.org/wiki/Barbegal_aqueduct_and_mill) in southern France, and [Janiculum](https://en.wikipedia.org/wiki/Janiculum#The_water_mills) outside of Rome. Another may have been at Amida (modern Diyarbakir) in Turkey.
Barbegal was likely the more powerful of the two installations. The Romans built a long aqueduct from the Alpilles hills to Arles, a city of maybe 50,000 at the time. The aqueduct was designed with a steep drop down a hillside; at this drop a complex of 16 overshot mill wheels was installed. The mill complex could produce something like 4.5 tons of ground flour per day.
Janiculum, was the same thing, except for Rome. During the time of Aurelian, (at least) one of the aqueducts was redirected to run staight down the side of Janiculum hill, previously on the outskirts of town. The Aurelian walls of Rome were then extended out to protect the mills and the town's bread supply. The mills were still in use as late as the time of Pope Gregory IV (-844).
The fact that both these large industrial industrial installations were used exclusively for grain milling shows the scale of grain milling in the ancient (and medieval) world. If a person needs a [1-2 lb of flour a day](https://en.wikipedia.org/wiki/Medieval_cuisine#Caloric_structure), then a city of 1 million like Rome needs 500 to 1000 tons of grain milled per day. Obviously, this analysis only applies if your people's staple food is wheat or corn or cassava or something that needs milling. If their staples are rice or potatoes, this argument isn't valid.
The biggest relative advantage for a city with free magic power is in milling grain. Logs and stone and other things are heavy and expensive to move; even if you can make them cheaper with mills in this town, most of the cost of getting these items to customers are transportation costs, with medieval technology. Grain, however, has to come to a city in grain form anyways (flour spoils faster and can't get wet). So for any given city size, you get mostly free grain milling with no extra transportation costs with these magic mills.
Therefore, I conclude that the biggest advantage of this city will be cheap food, which will make craftsmen and people of all sorts want to move there. Many of these crafts can't be aided by mills anyways (leather, goldsmithing, dyeing).
[Answer]
As other answers have mentioned, you'd get an accumulation of lots of industry that would otherwise be found only on large rivers. I think the biggest gamechanger, though, is that the magic wheels are *portable*; you can set them up anywhere, move them from place to place, even have them power their own transport! Automobiles might be too big a bar to clear, but other means of transport would certainly be enabled, from trains on railways to paddlewheelers on canals. If the effect goes out dozens of miles, that binds the entire region (and its various manufactories) together into a medieval metropolitan region.
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Suppose they have non-flexible beaks, but they still posses vocal cords and a tongue capable of producing the same sounds as humans. Variation of these bird-people are as follows:
[](https://i.stack.imgur.com/SEjgk.jpg)
What types of sound should not be assumed to be part of their language?
[Answer]
Birds don't have vocal cords, what they do have is a [syrinx](https://web.stanford.edu/group/stanfordbirds/text/essays/Bird_Voices.html), which is more drum-like to the human vibrating strings.
So when a bird mimics human speech, it's less repeating the words it hears, so much as **replicating** the noises in a human "song". The syrinx is the main reason birds have such a wide vocal range (I'd like to hear you perfectly replicate the sound of plastic clattering inside a vacuum).
Humans rely on our lips, tongues, and mouths to provide the diversity of sound required for our complex verbal languages (birds rely on the "drum" in their neck). However for a group of the stiff-beaked races above, any sounds requiring motion beyond opening/closing your mouth should be discounted if relying on human vocal cords. Pull back your lips(with the attached muscles, not your fingers) and try to pronounce the sound. For instance, "Oh" requires lip movement, while "Ah" and "A" do not.
* There are [44](http://www.dyslexia-reading-well.com/support-files/the-44-phonemes-of-english.pdf) "sounds" in the English language.
* [here](https://www.internationalphoneticassociation.org/content/full-ipa-chart) you can find a downloadable chart for a more international scale.
*But* you can bypass this entire problem by giving the bird-people syrinxes.
[edit] thank you to @John for allowing me to realize my assumption of preferred language, it was narrow-minded of me and I apologize.
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I plan on writing a story about a human born in the wild and raised by wild animals. I have heard of stories of real humans being raised by wild animals, mostly in Africa. I have also done some research on wild animals and figured out that, at least in Africa and Asia, elephants are the best wild animals for raising humans.
They have lots of pros and very few cons.
**Pros:**
* Protection from predators, most lion prides won't even bother with elephants
* Cross nursing, one of the elephant documentaries I watched was about an orphaned baby elephant being raised by a herd other than the one that had its mom
* Prehensile trunks
* Rich milk
* Very little risk of illness (at least compared to being raised by carnivores)
* Injury risk is low
* Can sense vibrations through the ground as well as hear
This is what I think would happen in the best and worst case scenarios of a human being raised in the wilderness:
Best case scenario (raised by elephants if humans aren't nearby):
The baby easily survives and grows up playing with baby elephants. The human ends up easily being able to call to elephants.
Worst case scenario (raised by lions):
The baby has to be super tough to survive. The lion's diet is dangerous to humans. I'm not saying meat itself is dangerous but lions eat raw meat and rotten meat. Both are dangerous, especially rotten meat, but even fresh meat could make a human ill if eaten raw. The baby not only has to survive very bad illnesses and vitamin deficiencies (especially vitamin C deficiency which makes the blood vessels not hold as well and thus bleeding occurs more easily) but also a lot of bites and clawing wounds from not only lionesses but also cubs that want to play and occasionally the male or males. There is no way the baby could survive in a lion pride, even if the lions did not hunt down the baby.
**Is it plausible that a human baby would be raised in and survive in an elephant herd?**
[Answer]
Unlikely, a very strange happening, but not impossible.
First thing, let's determine how old your baby is, and the differences between an elephant baby and a human.
Baby elephants walk pretty quickly, and human babies don't. It can take anytime between 6 months and two years for a baby to walk (with the average being between 9 months and 1 year). What this means is that your human baby doesn't have the stamina to keep up, and herds move quite a bit. They won't likely have it even when they can walk, so baby would have to be carried a lot--and that would not be hard because elephants can lift [a lot with the trunk...](http://www.elephantsforever.co.za/elephants-faq.html)
Most cross-species adoptions involve animals with more base similarities, than is true here, especially when it comes to how their young develop--and baby elephants aren't nearly as helpless as humans are by any measure, for any real amount of time. At least with wolves or lions, the pups/kittens are helpless for more than a couple of hours, so they have the instinct to deal with it--if not the milk supply.
And the biggest hurdle is size, which is why I think a toddler would be better than a newborn or a baby, preferably a TALL toddler. I'd say you might want to age your kid up--4 years old, 5 years old, at least.
A newborn elephant is [3 ft tall at birth](http://www.nationalgeographic.com/animals/mammals/a/african-elephant/) and while a mother might try to help her baby stand and nurse, they won't necessarily know how to deal with a 6 month old human baby, which will be considerably shorter and who can't walk with the herd.
>
> In Africa, elephants can cover over 50 miles (80 kilometers) in a day, if food is scarce, but rarely walk that far. More often they cover a few miles during the day, and sometimes spend most of their time near a water source. The distance that elephant herds travel seems to change during the year.
>
>
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That is something you want to consider.
Now there's this lion thing you've thrown in--I actually find that a trifle more likely, TO BEGIN WITH, on the kid being baby age. Lionesses have been known to protect babies not of their species just by instinct, from male lions--she'd have to be tough, wary, and ever-watchful, and it would help if the human had some sibs growing up with her/him. The vitamin C deficiency may never be a problem, actually. There's some argument that that raw meat actually [contains vitamin C](https://www.thenakedscientists.com/articles/questions/how-do-inuit-cope-without-fresh-vegetables-and-vitamin-c) and some of the organs in the body are surprisingly a good source of it.
The true hurdle is how long a baby is helpless, compared to animals, both with the lions and the elephants. It takes us forever to even walk. The upside to your elephants is the long weaning period (up to 10 years sometimes), whereas your lions don't nurse that long--and they start teaching cubs to hunt at 3 months--which, good luck to the baby...and they wean between 6 and 10 months. Humans do the same but...we don't have teeth for a while, and even once we do, we don't have very many for a long time and they aren't up to the task of raw meat. Neither is the digestive system, so again, I'd age up your kid to like 5 years old or something instead of baby aged.
Let's go through the point-by-point on your elephant advantages:
* Protection from predators, most lion prides won't even bother with
elephants Cross nursing, one of the elephant documentaries I watched
was about an orphaned baby elephant being raised by a herd other than
the one that had its mom. *Weak baby elephants still sometimes get picked off by predators who bide their time.*
* Prehensile trunks *The advantage here is that your elephants could carry baby without harming them, whereas, a lioness would try to carry by mouth.*
* Rich milk *Good point, but your baby has to be tall enough to reach it. Maybe mom can use her trunk to shove baby up there so it can reach? That'll be awkward but not totally impossible, I guess?*
* Very little risk of illness(at least compared to being raised by
carnivores)*I respectfully disagree. There will be plants that baby
or toddler is not equipped to digest or might be poison to humans but
fine for elephants. This is a human in the elements, the risk of illness from something eaten is higher than you might think.*
* Injury risk is low *Now, you talk about clawing wounds from lions--but--elephants play as well (and stampede--no idea what a crawling baby could do in a dust storm of stampeding elephants, who have the instincts not to run over their several hundred pound babies). Cats have signals used when play gets too rough, as do elephants, but a baby elephant is actually more likely to accidently kill a tiny human than a lion kit would, simply because of the difference in size. Adult elephants can be very gentle, but it is something that they have to learn. Imagine rough and tumble play with a group of 3-4 or 200-lbs babies and who are playing together and a 30lb child comes in between it. Accidents, broken bones, maybe even death can result.*
* Can sense vibrations through the ground as well as hear *I am not certain how this would benefit the baby*
You list your pros, but NO cons, so--
* Stampedes
* getting the runs and dying from it from bad hygiene, eating something your species can't tolerate
* parasites (just by dint of being in the wild)
* 200 lbs playmates who might accidentally squash you like an insect when you are barely able to walk.
[Answer]
I think one of the biggest barriers to being raised by elephants, unless you imbue your elephants with some kind of greater intelligence, is the diet. Humans can't survive on grasses, small plants, bushes, twigs, tree bark, and roots. Fruit, maybe, but the likelihood is that the baby would die before the elephants figure out to only offer it fruit. If the elephant could manage to hold the baby up to nurse until it was old enough to feed itself there might be a chance of survival, and if the elephant continued to nurse the child until it was able to find its own protein, it might escape most of the crippling effects of various nutritional deficiencies. Still, not at all likely.
Especially when you consider the fact that so many children die of malnutrition even when being cared for by members of their own species. Add in the fact that no medical care would be available, and no shelter from the elements.
If the child were basically old enough to feed itself, but just needed protection, you might have one or more of the elephants be escapees from a village, and therefore trained, at one time, to follow a human's commands. If the child (who had been raised in that culture) were to command the elephant to carry and/or protect it, that might work. And a child raised in such a way might learn to eat bugs and to forage for whatever food is available, retreating to "mama" elephant's back when there is danger.
[Answer]
Only after it's been weaned. But by then it would be considered a toddler, so, no.
Simple geometry, a baby can't stand upright. When crawling, its maximum vertical reach is about 40-45 cm. A newborn elephant calf, stands around 85 cm. Herbivores suckle standing.
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What I mean is: instead of a "rat" evolving into primates and those tree hugging primate becoming bipedal great apes, imagine a "rat" evolving into a dog-like or cat-like animal, then that animal becoming a tree hugger, which then turns into a great upright-standing "canis homo sapiens."
In short, if tree climbing canine-like animals got the same environmental pressures that lead to human intelligence, what whould it look like? And could this have happened?
[Answer]
You need several things to converge for intelligence to build and eventually lead to what we think of sentience.
1. pressure to go bipedal, which provides advantages in distance vision vs. quadruped animals.
2. increased brain size to develop higher intelligence
3. sustained increased calorie intake to fuel the larger brains
4. tools -- the ability to make and use them
5. empathy to encourage social interaction
6. language
This article on [evolution of human intelligence](https://en.wikipedia.org/wiki/Evolution_of_human_intelligence) might give you a useful framework.
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Primates developed versatile hands and feet due to living in an arboreal environment for tens of millions of years. Cats have claws which are sufficient for clambering about a tree and there would be no advantage to a cat evolving hands. Developing tools would be difficult without hands.
[Answer]
As answer by CWallach tells, first of all you need hands.
Primates are very evolutionary close to Rodentia, who also have quite developed hands
[](https://i.stack.imgur.com/pXdRd.jpg)
On the other hand, all canines have lost their hands in favor of claws. It is inevident how they could develop hands again.
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In my world, clans and factions fight wars with what is effectively magic, and have different types of soldiers. Most of these seem pretty practical, but I am not sure about the "ninja" class.
**World setting:**
North America, post-apocalyptic, no internet, very little electricity and internal combustion engines. Less population due to disease, lack of food, wars and magical monsters.
Major tribes and clans have population of a few thousands to tens of thousands.
**Magic system:**
Each human being can be trained in "magic", except this magic conserves momentum and energy, and is not "magical" in the way that Harry Potter series's magic is.
Benefit of magic includes:
* Increase muscular power with magic (requires energy)
* Shoot magic laser beam and fireballs (requires energy and intense training)
* Telekinesis (requires intense training and does not break physics)
* Craft magic items (i.e. magic equivalent of firearms, ammunition and steroid)
* Healing (very rare and requires intense training)
**Existing classes of soldiers:**
These are types of soldiers that I feel are pretty reasonable to have:
* **Knight:** Heavy armours, heavy melee weapons (sword, mace etc.) Specialized in using muscular power intensification. Act as front-liners.
* **Mage:** Light arms, specialized in casting magic fireballs and laser beams, act as long-range crowd-control and artillery (also counteracts enemy mages)
* **Gunners:** Similar to mage, but use magic firearms instead of casting attacks themselves, very long range, expensive to deploy.
**The class in question**
I know historically accurate ninjas are more like spies than soldiers, but they seem really cool to have. My current setting of this class is this:
* Lightly armed, use short, bladed weapons like daggers.
* Use physical projectiles like darts and arrows.
* Not specialized in strength but in speed.
* Does not cast magic projectile very often (need to reserve energy for movement), but will do so in emergency.
Based on the descriptions I gave, is there a practical role that these ninjas can fit in?
[Answer]
So your army is going to need scouts, spies, snipers, search and rescue guys, messengers and assassins. You may also need specialist urban combat units. Your ninja class will suit all of these.
[Answer]
Your ninja's are the disruption units of the army. Think an Assassin class. Or the medieval equivalent of a tactical missile strike. They can be deadly and quickly get to important targets to take them out, such as the enemy general.
Alternatively, you can send them in to take out the enemy mages and gunners so that your arty can get through.
The speed helps them close distances and escape chases from knights - since their armaments are also light weapons, they have to pick their targets (low armor ranged units), or they will die quickly against an armored knight.
[Answer]
What about giving a plus to your ninjas trought disguise and camoufalge?
Let's say they are fast and deadly in close combat but this is no useful against fireballs, guns and armors, and by those means are easy to kill, so, they require training in matter of psychic powers to become some kind of shadows and/or mist, some instant disguise and illusions to avoid direct attacks and get close to enemies, that puts a lot of possible tricky and traitorious scenarios at hand.
You can divide them in levels to define how much of them are like martial artists with no super powers and a few high level like the very same reincartion of Hattori Hanzou!
[Answer]
Your **Ninjas** can act as an *offensive* close-quarters class while your **Knights** focus on *defensive* close-quarters.
From how you have described your Knight class as *front-liners*, I'm under the impression that they not only have to attack the enemy, but *defend* your Mages and Gunners. The Knights are also the only class that fights in close-quarters and not from long-range. So if the Ninjas can pick up the slack of the Knight's attack duties so the Knights can focus more on defense, then they will both still be essential to an army without overlapping roles.
[Answer]
Ninja is perfect for low density post-apocalyptic urban warfare. Scouts are essential. Stealth and speed allow you to bring something unexpected to every encounter and defending against stealth adds an interesting dimension.
I might not call them ninjas though, ninjas were invisible because they were just like everyone else. They blended in with the normal people. Nobody is normal in your new world.
[Answer]
Depending on the skills you choose to choose to emphasize, I can see several use for your ninjas. Of course, they can develop all of it or specialize in a branch :
* Precise strike - Extreme stealth.
By sending a few assassins inside the enemy's camp or city, you can take out the leaders, sabotage the mount's saddles or the vehicules, set fire to food or ammunition supplies, unlock the gates, etc. This would require your soldiers to be equiped with only "stealthy items" as they will be killed or captured as soon as they are found. It would also require a way for them to kill themselves quickly and easily as the risk of torture in case of capture would be great.
* Disruption - Explosive weapons.
With their great stealth and mobility, your soldiers could also cause unexpected and violent blows to an ennemy's army. For that, they would need to get close to the ennemy, by approaching or setting an ambush, and suddenly cause panic with the more spectacular weapons your people have at their disposal. It doesn't need to be deadly, it needs to be scary, and it needs to be timed just right so that the rest of your army can take advantage of it. Then they could either enter the fight or choose to vanish again for another strike.
* Scouting and harassing - High mobility.
If they are very fast, your ninjas may also be your scouts. If you're in a society that doesn't have access to modern technology, remember that a battlefield is mostly a vast piece of land with nothing such as "rules" or "official limits". Soldiers could be hiding behind this crest. Are there reinforcement coming from the north ? Scouts roaming everywhere act as human radars and spare you the need to move your whole army for every little change of the plans. If you have inactive scouts, they also can harass the ennemy forces, by striking from a safe distance, and then getting away before he can retaliate.
[Answer]
I think without really knowing a lot about the context in which the soldiers have to fight nobody will really be able to tell you how good they would be in combat. And the significant context here might have to include almost everything in your world depending on how "realistic" you would want to make your soldiers.
First of all in which context is your setting being used? Is this for a game? maybe an RPG campaign?
Then you would have to think about how much fun each class is to actually play. Maybe the knights never really have a lot of options in a fight except for buffing themselves with a spell and hitting somebody with a weapon. This could be very boring. Or you always fight in close quarters as a group and your gunners never get a clear shot. That would be very frustrating.
If this world just stands on its own and you do not have to think about things like that then there are still lots of things to consider. For example chemical weapons can be quite effective in combat but are not allowed to be used because of ethical considerations. So how does the culture and political climate in your world look like? If your world is in perpetual war maybe nobody has a big problem from an ethical standpoint but ninjas might be looked at as a cowardly class of soldier by something like your Knights if they have a kind of codex. If not maybe everyone tries to assassinate the other factions leaders all the time with ninjas.
Taking those considerations aside, let us say that you put me into your world as a general of these kinds of soldiers. Still I have to know the full context of how combat plays out to know which of my units are actually worth something in the field. Is there perpetual war? A Unit that needs a lot of equipment might be too expensive to supply in a world were the resources of an army are depleted by a prolonged war. Are all these clans and factions living in a desert, the mountains the forest? In what climate are we fighting? Do I need to conquer something far away in a different climate? This has made a lot of military units almost useless and caused a lot of attrition in real-world wars (like napoleons army in Russia or the german army in Russia during the second world war). Even today some of the most advanced military equipment just has problems in desert sand or arctic winter.
You should probably think up all of the scenarios in which these armies might clash against and then evaluate them again. Maybe read something about warfare in a scenario that describes your world best. Maybe look at the battles were people had to fight without enough supplies if your world is starved of them. Keep in mind that you can change your world in order to make one class of soldier viable. In fact if you think enough about it, you probably have to really think hard about how exactly your magic works and what kind of defenses you have against it because most classes of weaponry become useless with everybody wielding magic.
To get to some scenarios were your ninjas would maybe excel:
I do not know a lot about the historical ninjas but most spies even in modern times had to be very creative with their equipment to be the most effective. You talk about the power to craft magic items. Depending on how those items work they could be very important in infiltrating the hostile army and sabotaging their plans. Of cause if magic grants you an advantage in detecting enemy spies that is less of an option. In open combat a faster unit might be able to outmaneuver slower knights to get at the more important units or to get knights in heavy armor tired so that they are less effective in battle. But in some situation you do not have a lot of terrain to work with.
So to wrap up there are lots of ways pretty much any unit you think up can be effective. It all depends on the situations they have to fight in or use there abilities.
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Like the title says, could a creature use metals absorbed through consumption to harden its natural armor? Metals and minerals that would be available would be similar to those on Earth (iron, aluminum, titanium, etc.) The creature's natural armor would be similar to that of armadillos.
By harden, I mean enough to resist small to medium size arms (.308 to 7.62x51) fire.
[Answer]
There's an animal that does something similar to this: the Scaly-foot gastropod <https://en.wikipedia.org/wiki/Scaly-foot_gastropod>. Its a mollusc that lives in deep-sea vents which incorporates Iron Sulphates into its shell & skeleton.
I'm not sure how tough it makes then, but it shows that what you're asking is possible in some shape or form.
[Answer]
I don't see any reason creatures like that couldn't exist. But practically speaking, there's a cost to running around in a heavy suit of natural armor, and for creatures like this to develop there would need to be commensurate selective pressure.
If there were lots of predators hunting with small arms (or better get, hunting with BB guns, slowly increasing over a long time to larger force and caliber) then no doubt creatures would gain son sort of defense, possibly metal-based armor. Actually I think other kinds of defenses would develop more rapidly -- fast movement, high reproductive rate, etc. -- but if the selective pressure was appropriate it seems highly likely.
[Answer]
You could certainly posit an evolutionary branch that developed the ability to deposit metal in some form of natural armor. You would need to propose a mechanism for the metal to be refined into a useful format by the biological process. This could perhaps be some form of rite of passage? Perhaps the armor could be "grown" then the creature could as part of it's lifecycle go through some radical action to "temper" the armor. Or perhaps the armor could be tempered by chemicals secreted or applied.
Interestingly there are some creatures on earth that make use of metals eg: <https://biology.stackexchange.com/a/9442>
In that same question/ answer sequence there are several other creatures that use metal to some degree in their biological functions - this would give you quite a few ideas for how to present a believable method of obtaining metal in a creatures armor.
[Answer]
To be an advantage on a living being, a shield has to offer protection but not give a burden to movements: this rules out too heavy shields made of metal.
The living being may develop the ability to generate carbon based fibers offering protection to its body.
FYI cobweb fiber is already much better than steel at absorbing energy, and weight much less.
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[Question]
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Basically, I am looking for variables in travel for the same ocean or sea journey, along the coast, but in the opposite direction. No motors, just standard 15th century ships. I am building a world with ocean currents and wind variations, so I'd like to get an idea of the impact on travel time.
**If both the wind and the current help get them there in one direction (say it's a three day journey) how badly can it hurt them coming from the opposite direction, where they will be against the wind and current? How can I build the ocean currents/wind in my world near the coast to get this effect, if it is even realistic at all? Please see the clarifications/details below**
I know that a great many things factor into this, and I don't have a good knowledge base as far as sailing is concerned, so just a basic math thing given a 10mph boost for wind and another 10mph boost for for a gulf stream and then make a -20 mph to the other direction is far too simplified, I'm sure. I can build in "dead zones" which can be traversed by the momentum gathered by the wind and current, which can't be travelled in the same way from the other direction, right? If there are analogous travel zones in our own ocean (where one direction is super quick and the other is very very slow), please let me know--my google fu is apparently weak today!
[Answer]
# Routes
As a standard example of sailing routes in UK waters, below is a map of the route taken by the Spanish Armada in 1588. [Source](http://www.emersonkent.com/map_archive/spanish_armada.htm)
[](https://i.stack.imgur.com/advXr.gif)
Once they'd gone up the Channel the only way back was round the North of Scotland and down the West coast of Ireland. The winds and currents around the British Isles say that this is the only way to do this. Effectively you can't sail the other way round as there are strong currents round Dover, and you need a ship capable of a certain minimum speed to actually make it round the point and into the Channel even if the wind is with you.
You can also look at the historic transatlantic routes which follow much the same sort of pattern as this follows the prevailing winds and currents as shown in the maps below. [Source](http://www.seos-project.eu/modules/oceancurrents/oceancurrents-c02-p03.html)
### Currents
[](https://i.stack.imgur.com/nds5L.png)
### Winds
[](https://i.stack.imgur.com/dSbR6.png)
What these maps also show if you look at the Southern Ocean is that there's a clear correct direction for sailing round the world giving you a significant concept of [sailing the wrong way round the world](https://www.theguardian.com/sport/2010/jul/25/sailing-round-the-world).
Related to the concept of sailing the wrong way, you can also see that on the return trip to Europe from India/China/Spice Islands, you need to sail close to the Cape of Good Hope so as to not have wind **and** current against you. Meaning that tales of bad trips round the Cape still hold today for those sailing the wrong way.
# Deadzones
The best known deadzone is called [the doldrums](http://oceanservice.noaa.gov/facts/doldrums.html), officially called the Intertropical Convergence Zone, it's an area with no wind around the equator. It's possible for a sailing ship to get stuck for days or even weeks in glassy seas.
>
> Known to sailors around the world as the doldrums, the Inter-Tropical Convergence Zone, (ITCZ, pronounced and sometimes referred to as the “itch”), is a belt around the Earth extending approximately five degrees north and south of the equator. Here, the prevailing trade winds of the northern hemisphere blow to the southwest and collide with the southern hemisphere’s driving northeast trade winds.
>
>
>
Big sailing ships don't carry a lot of momentum and we're talking an area that's a full 10 degrees North-South and runs all the way round the world. Once you're stuck there you're stuck until the wind comes back.
[Answer]
Modern ships are powerful enough that wind and currents are just one factor among many. Historically, that was different.
* Consider how HMS Calliope escaped a [cyclone in 1889](https://en.wikipedia.org/wiki/1889_Apia_cyclone#The_cyclone). That was extreme weather, but a ship that could make 14 knots under good conditions was reduced to 1 knot or so by winds and currents.
* Ships would often wait in a [roadstead](https://en.wikipedia.org/wiki/Roadstead). Quoting from Wikipedia, summarizing the [US Army Tech Manual TM 5-360](https://books.google.com/books?id=K6YXAAAAYAAJ&pg=PA22&dq=a%20roadstead%20is&hl=en&sa=X&ei=ABx8U-SVN4zLsASNtYHIDg&ved=0CDAQ6AEwBDgK#v=onepage&q=a%20roadstead%20is&f=false): "A roadstead is a body of water sheltered from rip currents, spring tides or ocean swell outside a harbor where ships can lie reasonably safely at anchor without dragging or snatching while waiting for their turn to enter a port of call."
[Answer]
Some of the other answers cover the winds on the open ocean. Those winds are more or less constant; the same winds go in the same direction the same time of the year. Prominent (historically) among winds are the Atlantic North Equatorial current and corresponding winds, which runs straight across the Atlantic from the Canaries to the Caribbean and took the initial explorers and conquistadors to the New World, and the season spring-fall monsoon winds of the Western Indian Ocean which moved ship commerce between India and Arabia and East Africa.
However, the biggest cause of delays were port conditions. There are three factors to consider.
# Rigging
There were generally two types of rigging, square and lateen. Lateen rigging allows a ship to tack 'into' the wind, allowing it to make slow progress directly against an oncoming wind. It also improves maneuverability. However, it provides poorer performance 'running', that is going with the wind 80 degrees or more abaft the beam. A running lateen sail's yard will be extended outwards over one side of the ship, to orient the sail perpendicular to the wind. However, if the wind shifts direction by a few degrees, the forces can attempt to switch the side that the yard wants to project on. A rapid shift of the yard will cause the ship to 'back' removing forward momentum; the swinging yard can kill passengers, destroy rigging, and even flip the boat.
A square rig is much safer, and better at catching the wind too, when running. All the big ocean-going tall-ships of the Age of Exploration depend on the square-rigged sail to cross oceans; it provides more thrust per sail area, less rigging to handle, and is stable in conditions of steady following winds.
Lateen rigging is preferred in more geographically compacted seas with more variable winds, such as the Mediterranean. In the Indian ocean, the Arab dhows with their lateen sails were quickly driven out when the Europeans showed up with their larger square-rigged sails.
# Port traversal
The big advantage of a lateen rigged ship is that you can get into an out of a port under many conditions. Since a port is designed to be protected from ocean swells, it is almost always in some sheltered location with limited access to the open ocean. If there is only one direction you can go to get to the open ocean, then it is entirely possible that there is just not enough wind to get there.
Lateen rigged ships are much more likely to be able to move in the direction they need to go to get out of port. Lateen rigged ships can often start from anchorage in a 180 degree arc along the direction of the wind. A square rigged ship's ability to start is more like 90 degrees. Further complicating matters, is that it is important which way you are facing when you try to start sailing. If a square rigged ship is facing into the wind because of the direction of the current where it is anchored, then it cannot raise its sails at all, or it will start drifting immediately. I won't get into too much detail, but a lateen rigged ship has a lot more options.
# Tides
This brings us to the last point, tides. Under certain tidal conditions, you would not want to get underway. Certain tidal estuaries can have very high currents at different points in the tidal cycle. Examples that I have seen personally include Lisbon (5 knot currents in the estuary) and Lagos, Nigeria (where I had to order an ahead bell while mooring due to extremely high currents in the lagoon). Despite that fact that I sailed a ship under power, with tug assistance, these operations were both dangerous and would have been better avoided.
I don't see how a sailing ship could attempt to get underway in such conditions. Thus, in certain ports, only at high or low tide, when the current is slack, can a ship expect to get underway safely. Other ports, especially those with man-made barriers such as the ancient ports at Carthage or Alexandria, have shallow bars that develop at their entrances. These bars mean that a ship can only expect to get underway at high tide. Thus, depending on the situation, a ship may only be able to leave port at high tide.
The real problem is the combination of tide and winds. If you can only leave port at high tide, then you would get your crew aboard every day at high tide and see if the wind was right. If it wasn't, you weren't leaving that day (its not like you'd get underway at night). Send the crew ashore for some drinking and wenching, try again tomorrow. This could go on for weeks.
# Conclusion
Coastal sailing is not done at night in the ancient world. Perhaps if the moon is full, but generally there is too much risk in running aground. If you want to keep going at night, you have to get out into open sea. That means coast-huggers use lots of temporary anchorages (or haul-outs where they beach the ship, if it is a galley, see *The Odyssey*) while hugging the coast from point A to point B. A wise captain will know the winds and tides and predict good places to hang out overnight so he can start right away in the morning. A foolish, inexperienced, or unlucky captain will not.
Roman records in particular are filled with travelogues of the varying calamities that can cause delays. Most prominent among them are delays leaving port, and delays caused by being trapped in a temporary anchorage.
[Answer]
A very important thing to consider is this: In sailing (especially 15th century sailing) travel speed is, very roughly, wind speed minus drag.
Wind speed is directed. So you cannot simply sail against the wind, you would just end up sailing backwards with the wind.
With some smart usage of angles, the keel and whatnot, you can sail in a direction something like 45° into the wind (with 0° being the wind from the front and 180° being the wind from the back). This means the total length of your journey just increased by sqrt(2). Still, roughly speaking, but the principle holds.
Also, you can only make use of a part of the power of the wind. a lot of how much you can use depends on the geometry of your rigging, but at that time you can guesstimate that it won't be more than half.
you are now at something like 2\*sqrt(2)\*original travel time.
Now d the same for currents, and you have a ballpark guess at what your travel times will be.
One note, though: wind has a tendency to blow towards a shore, or off a shore. This is because when the sun shines on land, air above it will be heated up, expanding and rising, and at night the ocean, warming slower, is warmer than the land, so now you have warmer air above the ocean.
That said: your setting where the main wind blows along the shoreline is not very plausible. The current, though, is quite feasible.
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To be very-very simple:
The very main setting of my world is a very special and very small galaxy, the galactic core of which is a quasar - with the "iconic" light beam in the middle, serving a special and iconic object for the cultures living within the galaxy.
[According to a Redditor](https://www.reddit.com/r/worldbuilding/comments/5mh02k/how_can_i_realistically_justify_a_gigantic_pillar/dc3jsgw/), these are extremely bright objects, with the possibility of providing enough brightness to eliminate night, even from tens of thousands of light years.
However, I decided to choose a very small "population": less than 1 million stars. If a quasar is so strong, then it would be an extremely sparse galaxy and I need to do something about it.
**What is the estimated distance from a small quasar** (if it's a thing at all) **where brightness would not interfere normal day-night cycles?**
[Answer]
The size and luminosity of quasars varies by a rather large degree, since you did not bother to include specifications, I'll supply my own based on the average:
Quasars emit a light as bright as that of **one trillion stars** and they have a radius of about 90 AU (0.00142313 light-years).
Light travelling through the vacuum is subject to the inverse-square law which means that the perceived intensity of the light is inversely proportional to the square of the distance from the light source: $I = 1/r^2$
I have no idea how dark you want nights on your planet, all you say is you want there to be a clear day-night cycle, so I'm going to say you don't want the perceived brightness of your quasar to be anymore then a tenth of that of a average star. That way, you will still indeed have day-night cycles but the quasar will still be a very impressive sight in the night sky (certainly sufficient to be an iconic object). In other words you want the perceived intensity to be only 1/10 trillionth of what it is at the source (which is the surface of the quasar at a radius of 90 AU from its center).
So let's plug in the numbers.
1/r^2 = 1/10,000,000,000,000
Now if we solve for $r$ we get about 3,162,277. The unit as I've previously mentioned is 90 AU. When we convert to whole light-years we get **4500 light-years**.
Now considering that 1/10th the brightness of an average star is still very large and that the Milky Way galaxy which happens to contain anywhere from 100-400 billion stars, only has an estimated radius of 100,000 light-years than we can see that 4500 light-years is rather big for a galaxy only containing a million stars. If you were to increase the number of stars then this would become feasible.
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**Note:** *Thank you to Adrian Colomitchi for pointing out the mistake I had previously made.*
[Answer]
Something that looks in disagreement with [@AngelPray's answer](https://worldbuilding.stackexchange.com/a/67124/26061) - the **[3C 273](https://en.wikipedia.org/wiki/3C_273)**
>
> if it were only as distant as Pollux (~10 parsecs) it would appear nearly as bright in the sky as the Sun.
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>
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10psc is roughly 33 ly. Inverse square law says if it would be 10x farther - i.e. 330 ly - the brightness will be 1/100 of Sun's brightness.
At 3300 ly (that's 1/10 the diameter of the Milky Way's size, 1/5 of its radius), the brightness would be 0.1% that of the Sun. This is in the same ballpark as the difference in brightness between the [Sun and the Moon](https://en.wikipedia.org/wiki/Apparent_magnitude#Example:_Sun_and_Moon).
[Answer]
Two huge problems:
1) Quasars existed in **early universe**, when there was very little elements outside hydrogen and helium - thus forming a rocky planet was rather hard (@JDługosz already pointed that out)
2) Quasars are **terribly variable** "stars" - a black hole devouring nearby gas in wholesale quantities. So do not expect any orbit to be in Goldilocks zone for long.
[Answer]
# AGN structure and emission
Let's talk about the structure of an active galactic nucleus like a quasar, and the types of emission we see from it. The classic [*unified model* of an AGN](http://astronomy.swin.edu.au/cosmos/A/Active+Galactic+Nuclei) consists of a supermassive black hole (of perhaps $\sim10^8\text{-}10^9M\_{\odot}$) surrounded by an accretion disk about $\sim10^{13}\text{-}10^{14}$ meters in radius. The disk has a radial temperature distribution of
$$T(r)\approx3\times10^5\dot{m}\left(\frac{M}{10^8M\_{\odot}}\right)^{1/4}\left(\frac{r}{r\_{\text{Sch}}}\right)^{-3/4}\text{ K}$$
where $r\_{\text{Sch}}$ is the Schwarzschild radius and $\dot{m}$ is the ratio of the accretion rate to the maximum accretion rate specified by the Eddington limit. If we assume that $\dot{m}\approx1$ and $M\sim10^8M\_{\odot}$, the luminosity should be about $L\sim10^{39}\text{ W}$. The disk itself should emit most strongly in the x-ray and ultraviolet portion of the spectrum, with UV emission beginning at $\sim10^{13}\text{ m}$.
Beyond the disk lies the *broad-line region*, where high-velocity gas clouds produce secondary emission. This area should have an outer radius of maybe $\sim10^{14}\text{-}10^{15}$ meters. Beyond the broad-line region lies the narrow-line region, (radius $\sim1000$ light-years) which includes the *obscuring torus* (radius $\sim100$ light-years), the latter being a structure of gas and dust that may be fed by a wind from the accretion disk. The narrow-line region contains slower-moving gas clouds; the low speeds produces less Doppler broadening - hence the name.
I think that what you've been considering is only the jets that arise from the accretion disk. Matter from the disk travels along magnetic field lines; electrons are accelerated, producing the synchotron emission observed from many AGN. This is indeed strong, but keep in mind that the jets are narrow and usually perpendicular to the plane of the galaxy, meaning that most objects in the galaxy are far away from the jet. If your planet exists in the equatorial plane of the quasar, it won't be hit by the jets, although it could experience radiation from the accretion disk.
# Different radii
We could attempt to compute the flux the planet would receive from the disk via the inverse square law if the disk was a point source and emitting isotropically. This is decidedly not the case. If we want to look at the best-case scenario, where the black hole is accreting below the Eddington limit, we could attempt to model the disk as a thin disk and use the [Shakura-Sunyaev model](http://www.scholarpedia.org/article/Accretion_discs#The_.22standard.22_model:_Shakura-Sunyaev), where the flux is given by
$$F(r)=\frac{3GM\dot{M}}{8\pi r^3}\left(1-\sqrt{\frac{r\_0}{r}}\right)$$
where $r\_0$ is the inner radius of the disk. If we assume the accretion disk somehow extends to the black hole's surface, we get that at a distance of $1.17\times10^{16}$ meters (1.24 light-years), the flux from the disk is about 10% of that from the Sun.
There's another radius we may want to consider, which is $r\_{\text{blr}}$, the outer radius of the broad-line region. It's calculated by
$$r\_{\text{blr}}\approx0.26\times10^{15}\left(\frac{L}{10^{37}\text{ W}}\right)^{1/2}\text{ m}\approx0.27\text{ light-years}$$
This radius is quite similar to the dust sublimation radius, inside which dust will be vaporized. This occurs when $T\approx1500\text{ K}$. I then calculate that for our supermassive black hole, $r\_{\text{sub}}\approx0.037$ light-years. The order-of-magnitude difference is because of my assumption that the black hole is accreting as fast as it can - a sort of worst-case scenario for our quasar. Finally, consider that the largest accretion disks may be around $0.01$ light-years in radius.
Here's a summary of the various length scales:
* $2\text{ AU}$: the Schwarzschild radius of the black hole
* $0.001\text{ ly}$ ($64\text{ AU}$): the outermost point of UV emission
* $0.01\text{ ly}$: the outer radius of the accretion disk
* $0.037\text{ ly}$: the dust sublimation radius
* $0.27\text{ ly}$: the outer radius of the broad-line region
* $1.24\text{ ly}$: the distance at which the jet's flux becomes 10% of that from the Sun
* $\sim100\text{ ly}$: the outer edge of the obscuring torus
* $\sim1000\text{ ly}$: the outer edge of the narrow-line region
The answer to your question, then, depends on the innermost zone you're comfortable with having your planets in, assuming you're good with the systems being in the plane. If not, you can be around 80 light-years away, for a direct hit from the jet.
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Set in the medieval period, preferably around 15th century, there is a habitable island the size of New York surrounded by boiling water inside the mouth of a volcano. How could you explain that there is a small human settlement on that island? Whether the volcano will one day blow itself or not is a topic for another day ;p
[Answer]
I can imagine such a refuge being very nice in winter. The discoverers were trapped out in the cold with no firewood and so made for the volcano in hopes of not freezing. They could rappel down from a height on a rope tied to a big rock which they threw down onto the island. They dug little channels in from the boiling water and made hot tubs where they soaked the winter away like Japanese snow monkeys. Scurvygrass, dodo birds and the aforementioned excellent weed is all you need for paradise.
[Answer]
Your island sounds a lot like [this](http://avatar.wikia.com/wiki/Boiling_Rock) prison that is used in the TV show Avatar: The Last Airbender. In the show, they accessed the prison using a pulley and gondola system, but the methods mentioned in other answers could have worked as well.
Perhaps in your world, there was a former civilization who used the island as a prison, but abandoned it at some point. The settlement could be made up of the former prisoners who either couldn't or didn't want to leave.
[Answer]
If they do not leave or enter the island all the time, it could be that an earthquake activated the volcano. Each earthquake may change the situation.
The boiling is not too much of a problem for a big wooden ship. Inside the ship it remains fairly comfortable, for a while. A storm or an extremely urgent need to get on shore could be a motivation to do it.
[Answer]
The most straightforward solution would be essentially a single-use drawbridge. On the outer edge of the water, build the bridge and two towers. Anchor the bridge at one end, and use pulleys in the towers to first pull the bridge upright, then lower it across the water. Once the bridge is in place, the other end can be secured and (optionally) the towers and pulleys can be disassembled. Counterweights could be used for a particularly large bridge. If the water is too wide, a series of bridges between conveniently-placed smaller islands could be used.
Since this is the same principles behind a castle drawbridge, which was a common defensive structure in the medieval period, the technology would be no problem. In fact the technology for lifting much larger and heavier objects vertically and lowering them back down was pretty common long before medieval technology was available, at the very least the Ancient Egyptians, the makers of Stonehenge, and the Easter Islanders could all do it.
There are other similar solutions. They could rotate the bridge horizontally while supporting it with ropes. They could also just place two long tree trunks, either by lowering them with a simpler pulley system, rotating them, or if they are much longer than the water is wide just pushing them across. The planks could then be installed one after another, having the workers stand on the previous plank as they secure the next one. These sorts of solutions might be a bit simpler if the bridge doesn't need to be raised and lowered.
A better question is *why* they would want to live there. You could argue that this is a mining town, harvesting some rich mineral or gemstone resources released by previous eruptions. You could say someone spotted the glint from exposed gold or gemstones, and that is why the bridge was constructed.
[Answer]
Once every X amount of days/months/years, the volcano calms down, the boiling stops, and the island becomes accessible for a short time. A bit like the Old Faithful geyser, but backwards. Instead of erupting periodically, it stops erupting periodically.
You could require that both the volcano timing and the tides need to be correct, making it harder to predict and with possibly much longer and seemingly irregular intervals. Perhaps the weather also plays a role. The original explorers came across the island by chance in a calm period, and wandered in, and got trapped there. Or that the steam provides excellent defense, and they are happy to live in there for X months/days at a time since they'd be raped and pillaged by bandits otherwise. No one else has figured out the timing pattern, so it seems like its always inaccessible. Perhaps there's excellent weed growing naturally there. I think the problem is not to explain the steam and boiling (its the mouth of a volcano after all) but why the inhabitants are actually there in the first place.
[Answer]
I cannot comment yet, so expanding on the castle bridge answer with the "Why somebody would want to live there"?
People that were persecuted found it to be a very safe location.
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[Question]
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**Toxic Spiders and Experiments Gone Wrong:**
## Let's Talk About Comic Book Mutations
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Numerous superheroes get their powers after something mutates their cells.
Perhaps it's a [gamma ray](http://marvel.com/universe/Hulk_(Bruce_Banner)), and results in a morphological change every time the hero is stressed; or maybe an [irradiated spider](http://marvel.com/universe/Spider-Man_(Peter_Parker)), that gives the hero enhanced speed and agility.
*Let's talk about why that shouldn't work*.
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> In real life, we observe two types of mutations:
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> **Germline / Germinal / Heritable** These are passed on from parents to offspring. They occur when a gamete (sperm or egg) mutates, and
> result in the mutation being spread through the entire body of the
> offspring.
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> **Somatic** These are not passed on from parents to offspring. They occur when environmental factors (radiation, DNA copying errors) are
> present, and only effect areas of tissue created when the mutated cell
> replicates.
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>
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The problem with explaining the powers of superheroes with mutations, aside from the improbability of mutations that cause the powers described in comics, is that the mutations described in comics seem to be a **combination of both germline and somatic mutations**.
Comic books describe **environmental factors**, that, in real life, would cause **somatic mutations**. They would
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> 1. Only mutate clumps of cells nearby (think tumor instead of whole body)
> 2. Only mutate the same types of cells (a toxic spider that bites the skin won't change the bones)
> 3. Not be passed on to offspring
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But yet these mutations effect the entire body, and can be passed on to offspring: they are also **heritable**.
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**Is there a way to justify a mutation from an environmental cause that affects all cells, and can be passed to offspring?**
**EDIT:** To clarify, I am not asking if mutations can give you superpowers - of course they can't. I'm asking if the genes required to do so can end up in the places the comics say they are - and if so, how.
[Answer]
The big issue with this sort of thing is that, somehow, all different parts of the superhero's body need to be affected at once, and with synergy. If half of the hero's muscle fibers are made stronger, and half are made weaker, they gained nothing. And then there's the whole issue of all the unlucky mutations that kill the cells outright (and there's *far* more of those than there are mutations for telepathy!). There's no way a simple radiation accident (or similar) could do what we want on its own. However, what if the seeds for this ability are millions of years old? Perhaps instead of having the radiation cause the mutation, maybe all it does is trigger it, and some complex internal system does the rest.
The current favored hypothesis for the evolution of species is called punctuated equilibrium. In this system, species spend most of their time in a sort of equilibrium where few changes occur. However, every now and then, they undergo a period of rapid change. This rapidity is used to explain the lack of transition species that we can find in the fossil record. Now the real scientific theory this occurs over hundreds of generations, but what if it actually occurred in just one?
What if our bodies ran in two modes, which I will label "user mode" and "kernel mode" because there's enough similarity between this idea and the way modern computers handle privileges. The key difference between the modes is that "user mode" is not allowed to alter the DNA itself, except through well understood channels such as mitosis and meosis.
Kernel mode would be invoked via a quorum. If enough cells signal that we need to unlock "the hidden potential" of the individual, they'd vote for it with hormones. If enough hormones are emitted, it's like the bat signal flashing over the sky, and the kernel mode capacities of our genome are woken up. They call one final vote (which is easier now, because they have an "elected official"), and if the vote is sufficient, kernel mode is activated.
In kernel mode, the DNA of the individual is open for reading and writing. This would be very powerful in radiation environments because it would act like a massive RAID of harddrives. Every bit of damage that gets caused has a few million replicas elsewhere in the body. This could counteract the otherwise certainly-fatal doses of radiation poisoning.
Of course, if you were going to have this sort of power hidden in your genome, you'd not only want to be able to counteract the radiation, you'd want to rise above it. You'd want to write new genes to rise above the environment. These genes, of course, could be passed on if you chose to rewrite your germline DNA. Your brain, on its own, would be insufficient to do this but what if it had help? What if, in some of the parts of our genome which appear to be unused likes a sort of grimoire of abilities the genome knows how to do. This sort of knowledge could then be used by the lower brain to try to identify mutations to fix their environment.
I say lower brain for three reasons. The first is that it's older... this sort of crazy pseudo-science would have to be born quite early if it were responsible for punctuated equilibrium. Perhaps the kernel mode of our bodies doesn't yet trust this new fangled cerebral cortex. The second reason is that, in the stories, people tend not to have full control over what mutations occur. If the cerebral cortex was involved, they would. Finally, I'd like to point out that most individuals going through this process are... well.. screaming in agony and in no condition to make life decisions.
I can't make any claim that this is how it works in real life, because I'd almost certainly be wrong. However, this seems like a reasonable way to bundle up just that much otherwise unbelievable power into a momentary dose of radiation. The radiation isn't doing the mutation, it's merely stressing the body enough to break a seal and unleash the next higher level of power the body has.
[Answer]
There isn't really a way for a genetic mutation in one cell to spread to another without outside help (which includes "the cell is made in some way different to the ones of normal, real-life humans).
The most likely answer will vary from comic to comic.
In hulk's case his whole body was irradiated, so we don't have any problem there (except explaining why the mutations were all consistent. That's not the question though).
In the case of spiderman and anybody else who gets bitten or otherwise infected we can attribute it to a virus. Such a virus would have no reason to evolve, but assuming it exists and is in the right place (i.e. in the spider's spit), it could infect a cell and modify its genes so that it creates more of the virus, besides making any changes required for the desired superpower. The virus would then spread through the whole body, modify the immune system to ignore it, change all genes as desired and eventually commit suicide. The cells could have a timer, after which they create another virus which modifies their dna to **stop** producing both viruses.
All of this is assuming genetic mutations could somehow cause all the superpowers we're talking about, but that seems to be the assumption in your question already.
EDIT: You **could** justify all mutations with a virus if you say that the first mutation (the single cell that was hit by the cosmic handwavium particle) was such as to cause the cell to produce the above-explained virus, but that would be even crazier than the superpowered mutation.
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I write Fantasy novels, and I always have the same problem: Whenever I want to create a map or outline of any village/city/farm/what have you, I don't know what goes in it. Nowhere can I find a definitive source for 'this is what every village needs for \_\_ time period.' All I'm looking for is the basics - the buildings that every settlement has to have on some level (additional details would, of course, be nice).
I can figure out a lot of the buildings. Humans need three basic things: food, shelter, and clothing. But the more advanced I make the humans, the more things they require, and I can never tell if my city contains them all.
**Is there somewhere I can find this information? (physical or virtual)**
EDIT: Something else that would work would be a formula which would allow me to determine what buildings my settlement requires based off of what they need. I would imagine a simple map would be easier though.
---
For example, in my current work, I have a group of humans from around 1300. They are living in the vicinity of New Zealand. I say the vicinity, because this is a fantasy novel and there is, in fact, no such place as New Zealand. They do not have access to metal, and wouldn't know what to do with it if they did. There are approximately 1000 of them living in one village.
I don't know what their village would contain. The first thing I would do is try to find a blueprint for a Native American village, as I would imagine the buildings needed would be fairly similar. Apparently, no such document exists. I've done extensive searches, and I've found nothing.
How can I find the information that I need?
[Answer]
The reason you are having trouble is how basic needs are fulfilled vary wildly not just by time period but also by culture and landscape. the simpliest human settlement is a a few huts to sleep in, a communal fire pit, and a garbage pile, and that's it. even simple things like how food is obtained or what resources are abundant changes community structure dramatically. Hunter/gather, fishing, herding, or plant crops all have different living conditions.
Your best bet is to use realworld examples. Pick your time period, climate, and culture then search from there. But you will still have to consider things like whether it is a market town or farming village, are the people nomadic pastoralists or or a fishing village.
[Answer]
# Archaeological Journals
The information you want is published reports of digs in Archaeological journals. Unfortunately, getting your hands on that information can be tough. Searching through published articles is a good way to get what you want. Unfortunately, Journals aren't really free. If you are a college student, you can usually use JSTOR through your college library to search a lot of available journals. If JSTOR is available to you, that is BY FAR your best option and you should spend the time learning how to use it.
You have a few options, pay for a subscription, or see what you can get for free. [Google Scholar](https://scholar.google.com/) is in general a good resource of a lot of topics, but archaeology really isn't one. I haven't had much success with it in that field; most of the good stuff is behind paywalls and most of the free stuff is crap. The [Royal Archaeology Institute](https://www.royalarchinst.org/) offers for free all their issues from 1844 to 1963. This is good, because back then people were more interested in digging that in social theories and other nonsense. Unfortunately, their search tool is godawful and it is hard to find anything.
The last option is paying for subscriptions, or pay-per-view on papers you know are interesting. Google Scholar can help here, since it links to many non-free papers in addition to the free ones. I have never done this so I can't really advise you on a good strategy for spending money effectively.
# Books
Have you been to your local library? No one goes to the library any more. But especially in older towns there can be some impressive things in public libraries. If you live near a city that boomed before 1900 or so, Public libraries often have very impressive endowments from people like Carnegie and Rockefeller and such. Check out the library. You never know what is in there until you look.
Amazon is the next best thing. The problem with amazon is that it can be hard to determine what is useful and what is garbage before you buy. read reviews and look for adjectives like 'dense' and 'hard to read.' Then you are probably on the right track.
# Search terms
The term you are searching for is 'material culture'. Combine that with village and you can search on, for example, [Amazon](https://www.amazon.com/s/ref=nb_sb_noss?url=node%3D11242&field-keywords=material%20culture%20village&rh=n%3A283155%2Cn%3A3377866011%2Cn%3A11242%2Ck%3Amaterial%20culture%20village) and see what you can find. Here is book on material culture of an [Early Mediterranean Village](http://rads.stackoverflow.com/amzn/click/1107661102) (note: uses the word 'agency' in the title which is code for 'bullshit'), one on an [Alaskan native village](http://rads.stackoverflow.com/amzn/click/160223244X), a [late Moari village](http://rads.stackoverflow.com/amzn/click/1869403150) (Did somebody say New Zealand!!!), an a [Kickapoo village](http://rads.stackoverflow.com/amzn/click/B007QXY3JI) from Illinois (Native American anyone ?!?!).
So there you have it. You should probably look for journal articles or see whats in the library, but at least on Amazon there are two books that seem to cover exactly what you want. Are they good books? No idea, you and your $70 are going to have to find out. But its a start.
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## Stone age
"They do not have access to metal" means that they live in the stone age, by definition. There are zillions of articles on the internet about stone age settlements, and there are [quite a few](https://www.google.com/search?&q=stone+age+settlements+site%3Aarchive.org) full books on the Internet Archive; for example, [*The New Stone Age in Northern Europe*](https://archive.org/details/newstoneageinnor00tyleuoft) by John M. Tyler (1922); has pictures. For an archeologist it would be too old to be useful, but I think that for fiction it should be quite serviceable. The climate of northern Europe is not substantially different from New Zealand.
[Answer]
## You can find what you need through more research; there is no "go-to place" of which you speak.
Given a date, a source cannot simply say "this is what there would be" because the date says nothing in an [alternate-reality](/questions/tagged/alternate-reality "show questions tagged 'alternate-reality'") setting. In a fantasy world, there may be magic in development at 500 A.D., and the Great Elf Wars might happen, ridding the world of all it's titanium alloy in 1700 A.D. - **it depends on the world *completely***.
You would have to provide the location, how long the society has been developing, the neighboring civilizations, their stats, the nearby resources etc. - and at that point, "what their village would contain" is still opinion-based. No source but research and reasoning will do the math for you.
[Answer]
One of the most important historical documents on demographics is the [Domesday Book](https://en.wikipedia.org/wiki/Domesday_Book) from 1086 that holds a very thourough land survey of the territory held by William the Conqueror in England.
Data from this document has been used by RPG fans to create a number of tools to quickly get an estimate for populations and economics of medieval settlements of a given size.
I recommend taking a look at the following links:
[Medieval Demographics made easy](http://www222.pair.com/sjohn/blueroom/demog.htm)
[The Domesday Book (tool)](https://www.rpglibrary.org/utils/meddemog/)
[Low-Fantasy Populations](http://www.welshpiper.com/populations-for-low-fantasy-settings/)
[Medieval Demographics Online](http://www.welshpiper.com/medieval-demographics-online/)
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I wish to build a sort of [Dyson swarm](https://en.wikipedia.org/wiki/Dyson_sphere#Dyson_swarm) around the sun. Not to transmit energy, but to put supercomputers in each satellite so they can calculate spatial trajectories.
The main idea of the project is to provide easy travel in the star system. I was thinking of including a patched [KSP](https://en.wikipedia.org/wiki/Kerbal_Space_Program) simulator into every spaceship, but a physicist friend of mine told me that "lol no".
Now, the building construction being incremental and heavily pushed by diverse big companies (aka deluded trillionaires), my main focus is on the feasibility of it.
I think the main problems may be cooling the processors, solar wind damaging the electronics and the overall maintenance cost once the calculators are in place.
So my main question would be: Is it possible to build low-heating radiation-resistant processors with a decade-long lifespan?
[Answer]
Ok, as comments already helped OP to find Matrioshka brain concept, I let me focus on other aspects of the question.
First of all, the scale of the system, let say 500 W per node consists of 100W processor(s), 300W of graphic card(s) (kinda), 100W for other needs.
the power of the sun is 3.82e26W, with efficiency 40% we will have 3.056e+23 nodes in that super-cluster.
So far(in this and previous century) we have produced less than 1e14 processors. (kinda my wild guess, embedded processors included and they are 99% of things we usually call a processor, Quora question [How many microprocessors does Intel sell per year?](https://www.quora.com/How-many-microprocessors-does-Intel-sell-per-year) contains an interesting link).
The Point is that even if you have dedicated 1e9 factories to produce nodes for MB and for spare parts of MB, it makes sense to replicate all technologies which are needed in production(just replicate earth manufacturing capacities, and scale it a bit) in one production node, because scale of operation way above of anything we have done on earth at the moment. This way each production node will be self-sufficient.
On earth orbit, at distance 1 a.u. from the Sun, 1e9 factories with the size of the earth will cover half(0.47) of the surface of the 1 a.u. sphere around the Sun. (I just find that funny illustration, they do not have to be so big, but collectors have to be 2 times bigger)
### The Problems which OP have mentioned.
One of the main problems, in terms of feasibility, will be developing(not building) those (1e9) production units, they have to be fully automatic in production installation and replacement of broken units, recycling.
This way fundamental cost will be in developing such automatic system, partially by copying existing earth/moon/mars/venus/mercury/whatever technologies with complementing them with automation into a fully automated system.
Second fundamental cost is developing a fully automated system of extraction and resources supply at initial stages for the growth of the supercluster.
Maintenance cost will be overseeing that supercluster, monitoring it, just in case. No other maintenance costs are needed, this system will work until the sun is burning.
In general producing low heating processor is not needed, because energy flux is limited by energy flux at that distance from the star, this way maximum temperature for this system will be limited by how high temperature of a black body may be, at that distance from the sun. (see notes)
Depending on configuration, how are those calculation units arranged - - as thin layer or more globular structure - radiation resistant processor may not be needed, because construction may have a pretty thick layer of protection(km's thick)
But radiation resistant processors are produced today for aerospace needs, and replacing those which are damaged by flares will be a small percentage of manufacturing capabilities which the entire system have, and may be done just as an upgrade of the system rolls. For the same reason no need in decade long life span. But as an example, some processors produced for Voyager are still working even today, so they are perfectly capable for decade-long lifespan, but really it is not what you may wish, as replacing them with more efficient units as soon as possible(as it makes sense) is a good thing.
Radiation resistant processors may be produced by other no silicon-based technologies, based on nano vacuum tubes principle - different variation are tested in labs:
* [The vacuum tube strikes back: NASA’s tiny 460GHz vacuum transistor that could one day replace silicon FETs](http://www.extremetech.com/extreme/185027-the-vacuum-tube-strikes-back-nasas-tiny-460ghz-vacuum-transistor-that-could-one-day-replace-silicon-fets)
[Could modern, nanoscale vacuum tubes replace transistors?](https://www.extremetech.com/computing/229680-could-modern-nanoscale-vacuum-tubes-replace-transistors)
[Return of the Vacuum Tube](http://www.sciencemag.org/news/2012/05/return-vacuum-tube)
[Nanoscale vacuum transistors – way cool, but still not as pretty as a glowing 12AU6](https://wattsupwiththat.com/2012/05/24/nanoscale-vacuum-transistors-way-cool-but-still-not-as-pretty-as-a-glowing-12au6/)
## Navigation problem
Such a system as a solution for navigation problem is overkill.
For navigation system, it is enough to place beacons each 5'000'000 km, and example of such system and some consequences and some use case are described in this answer of my, [here](https://worldbuilding.stackexchange.com/a/41407/20315)
The entire solar system may be covered up 10 a.u. by about 100 million of such nodes, with a modern notebook of calculation power, and forming a network of those units it will be way much than enough to solve any navigation problems, one may face in the solar system.
5'000'000km are based on [LISA](https://en.wikipedia.org/wiki/Evolved_Laser_Interferometer_Space_Antenna) project, where 5 million km is planned distance between probes, for detecting gravitational waves. I do not know which precision they should keep the distance between them, but I guess if it is good for detecting gravitational waves then it is good enough for navigation purposes. (See *Note, LISA precision*)
## Notes
Mass of the computer system may be about the mass of a planet like earth if the average mass is 10kg per calculation node.
Distance from the Sun is about 1 a.u. because it is about temperature which current system still may work, even without active cooling. The temperature of a black body is about 130 °C at that distance.
Considering one unit is about let say 1 cubic meter of volume per calculation node (average) and 1e9 of such clusters, size of one cluster is about sphere with about 90 km of its diameter, so biggest thing there(in size) is energy collector, and cooling system, with tiny specks of actual processing and production units attached to it. (or those calculation units are tiny layer on collection system about 0.01m tick)
* example of that system is in this [answer](https://worldbuilding.stackexchange.com/a/58790/20315) provided by Thucydides and it is called "[Server Sky](http://server-sky.com/)". The question itself is very similar to this question.
Speed and time to build that system are highly dependent on the energy efficiency of processes used and that is only limiting factor of the project in terms of actual building. (it may take less than 25 years to build such system)
## Note, tracking all small size objects in the star system
I'm actually a big fan of tracking each object in solar system up to 3 liters in volume, including and specially including Oort cloud, as I think it is very precious database which will allow us to take a look in great details in the past of our star system, and history of events which took place around our star system in the past, millions maybe hundred million years in the past. Which stars were passing by, spectrum and intensity of their light, distance, trajectory relatively to our system, their composition. Records about our planets in our system(trajectories, evolution of our system, stability of our system, atmosphere composition of our planets, do we had some planets we do not have at the moment) , maybe about planets in other systems(which have fly near our system) and maybe even more - all that as hologram may be recorded in Oort cloud, in composition of big small and tiny asteroids there, layer by layer.
Not sure trough if such a task, like see in the past of our system, need an MB system, it will definitely help, but considering how energy inefficient are current systems compared to biological brains and that problem is suitable for parallel processing(which is excellent case for quantum computing) I would not dedicate all available energy for the task 1% is way as enough, there are more important tasks, and better equipment will probably exceed the needs for this task even on 1% of the sun energy.
But just tracking objects for navigation purposes, this task is much simpler.
But it needs more sophisticated equipment then one we have at the moment, and slightly different approach than just building super cluster.
The main problem which has to be solved is to track relative positions and speeds of those bodies. In fact, this base may be very huge, but what is nice about it, for navigational purposes we do not have to have this data base in a data center. Optimization is exactly same as for simulating matter interaction on a molecular level - each piece of information is grouped by the position of those objects. Also, it helps further that in some places they naturally form groups like groups of asteroids in Lagrange points.
It is enough 2 or 3 times to observe the object to predict it position for a long time, with good accuracy. Sometimes we loose previously observed objects, but most of the times it works. Those objects between Earth and Jupiter as an example have orbital periods about 1-11 years. Considering all that if an object will report his position once in 3 months we will easyly be able to predict its positions in the future, between those updates.
Further is the body, longer it takes for it to make a full circle in the orbit. Saturn orbital period is about 29.5 years and it is enough for objects at 10+ a.u. to report their position once in 10 years(maybe) to allow us to predict their position with high accuracy.
Thus if we label all those bodies which we like to keep track of, with some kind of markers and give them the ability to determine their position and ability to keep a connection on demand and to report their positions on schedule we will have position-velocity database in distributed form across solar system, and data will be there where it is needed for navigation, where we find use for it.
Each label should keep track about nearest objects, 10-100 objects nearby, the same way as cellular network works, based on relative proximity. Each individual label will operate with a small amount of information and because of that do not have to be something exciting in terms of calculation power, and most of the time it will be in sleep mode, accumulating available energy for next connection session.
And those labels have to be small, energy efficient, robust, be able to upgrade them self, be able visually or by other means track smaller bodies around them if such task is given. And most important they have to repair themselves, it is not acceptable to send something each time it needs a repair. Also, they should be able to mark and discover objects needed to be labeled, and actually label them - von Neumann probe approach.
The main point for navigation, those labels will be activated when they need to be activated. Some ship plans some trajectory and it requests information about trajectory and corrections from this global solar network, the system asks base stations on that route, they check information about know-marked objects on the route.
Depends on travel speed of the ship, but it is enough to know situation 100'000 km ahead and around, this will give hours to react and make corrections if it is needed. And information which should be accounted is greatly reduced for the ship and for the system as a whole.
It is hard to tell how much bodies should be labeled because the distribution of them is not even across the system. My notebook relatively easy can calculate interaction between planets (8 bodies) with 10 second steps it takes about 17 seconds per year, just on processor in one thread, it is about 40 million calculation per second, may be a bit off with numbers, can't check at the moment, especially about time, so to be save, probably you may check intersection with 1 million objects on pretty typical PC, per second. (you do not have to check their collisions between themselves because it is known already and most time they probably not collide).
So with 100 km/s speed of the ship, and typical for the objects speed of 10-30 km/s it is easy to navigate between 1 million of objects in about 300'000 km3, which is about 3 objects per km3. Probably even dust do not have such density in inner parts of the solar system. And you still do not need supercomputers.
### MB rough power vs solar system small bodies
Using MB power to calculate interaction between all bodies in the system and by that be able to predict positions of the bodies with high accuracy - that is great, but there are some problems.
First of all to find out all those bodies, and determine their positions and velocities. From the distance we can do it with limited precision, farther a body is from our detectors, less is the precision.
Second is - at the moment we have a hard time to determine the mass of the objects, there are different ways to make a good guess, but be sure, we can't be sure at the moment, and probably in the near future.
Both of that make calculation not precise, not useless but imperfect. (there are also other nongravity related factors, lot of them, as an example [Yarkovsky effect](https://en.wikipedia.org/wiki/Yarkovsky_effect) or just industrial actions in solar system)
But the system itself, all those bodies with our beacon attachments, it calculates those interactions very well and very precise and at 0 Energy expenses from our side, for free - I like for free.
Also we have to explore our system, it is not enough to know just positions, we should know where and what we can take, by composition, by the amount; Also we have to make a science from that knowledge. For all that we should be there where those objects are. We should be able to test them, to taste them.
### Small bodies the problem
The real problems are those markers or labels.
At different technological levels, it makes sense mark different in size objects. At our current level, or better to say which we will have after SpaceX will make BFR - it will be perfectly fine to mark 1km size bodies and keep an eye on less significant objects by using 1km size bodies as observation stations and base stations for the system. It will make sense for the inner solar system.
Better technologies are, farther we can mark, smaller objects we can mark. It makes no sense to mark an object if a marker is bigger then the object itself.
[Starshot nanocrafts](http://breakthroughinitiatives.org/Initiative/3) they probably can be used as labels for small bodies, with a bigger base in the region, which produces them, and sends them to bodies we like to keep track on.
But those starshot markers are very limited in capabilities, but still, they can be useful.
The real breakthrough is possible with nanosystems with self-repair capabilities, and with capabilities to reconfigure them self in systems we like to build from them. Gray goo is actually used to depict such smart matter and such capabilities, but I didn't saw a blueprint for them, and as they are imagined by many they have huge holes in the plan and have significant limitations.
Technology from the [answer](https://worldbuilding.stackexchange.com/a/41407/20315) which I have already mentioned above, they are perfectly capable of doing the job, in safe and predictable manner, they are something in-between of marco-machines and nano-machines - best of two worlds.
With them, we are perfectly capable of marking all our solar system.
### Problem with "huge fleets of vessels to roam the system"
Problem is, reactive propulsion is inefficient, [Tsiolkovsky rocket equation](https://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation), and there is a limited number of places to visit on regular basis (maybe 1e9 places), and a limited amount of mass in our system so limited amounts of ships is possible. My personal recommendation travel with 30km diameter ships, safe and comfortable way of traveling, high military yield in case of demand, and if to extract all building matter(everything excluding Hydrogen and Helium) from the sun to build them it will be enough for about 736'481'481'481 such ships. If ships are smaller let's say 1km sizes then the number will be about four orders of magnitude bigger, and so on, cube square law.
The point is that huge fleet is not so huge for the star system, because star system is pretty big in size, and number themselves aren't that huge for even modern computers.
P.S. Short speaking, I wish to say, yes, MB is overkill for navigation.
### Note, LISA precision
From their page
<https://www.elisascience.org/articles/elisa-mission/elisa-technology>
>
> The expected distance changes are tiny, a few parts in 1021 or 1022 of the separation of the spacecraft.
>
>
>
[Answer]
We have satellites currently operating in orbit that are well over ten years old, so, yes, it's possible to build low-heating, radiation-resistant processors with a decade-long lifespan. ;-)
Cooling isn't an issue. Space is really cold when you're not in direct sunlight, so put some radiators on the shady side of the satellites and they can dump as much heat as you need into the cold black depths of space. Consider that space probes regularly use radioisotope thermal generators that are only about 5-7% efficient. As a result, a probe that requires a few hundred watts of power for their systems has to dispose of a few kilowatts of waste heat. So add some [black radiator](https://en.wikipedia.org/wiki/File:RTG_radiation_measurement.jpg) fins or some [folding radiator panels](https://en.wikipedia.org/wiki/File:International_Space_Station_after_undocking_of_STS-132.jpg "the white wavy ones perpendicular to the solar panels") and you're good to go.
As for the chip design, the short answer is yes, we can build radiation-hardened processors without too much trouble. The caveat is that space-hardened designs are usually not bleeding-edge chips, but rather trade off performance for as much durability and reliability as possible. So you're probably going to be looking more at a massively-parallel supercomputer design as opposed to a single ultra-high-power processor. Of course, if your super-computing satellites are using some sort of exotic processor and not modern-day silicon (e.g. quantum computing), then there might be additional considerations required. But at that point, you can really declare whatever you'd like as far as shielding requirements go.
Regarding maintenance, if a civilization is building a swarm of satellites large enough to surround their sun in Dyson-sphere-like fashion, I would assume that they also have the capability to maintain it in some useful way. Just as an idea, there could be "depot" stations scattered throughout the sphere. Damaged or malfunctioning satellites could either return to a depot under their own power or be brought to one by tender craft, and then be refurbished or recycled as needed. Of course, for a project of this scale, you're at the higher-end of [this xkcd strip](http://www.xkcd.com/1737/), so it may just be easier to shove a broken satellite into a graveyard orbit and deploy a replacement one. That could get messy, though, so they'd probably want to have at least some sort of garbage-collection method sweeping up old satellites.
So, in summary, the design of the satellites themselves are not the limiting factor. As far as the satellites are concerned, we could start building your Dyson-computer today, if we suddenly decided to do so.
The main bottleneck as I see it would be the development of manufacturing infrastructure able to output satellites on the scale you are describing. In-orbit manufacture and maintenance facilities would absolutely be required, and you'd want to mine as much of your raw material as possible from asteroids or other low-gravity sources, so that you can minimize the amount of material that needs to be hauled up from Earth (or whatever your home-base planet is). But if your civilization already has that manufacturing capability in place, then they should be more than able to do it.
[Answer]
If you want the best possible space travel you should use space corridors.
Basically, you want to have set points in space to travel to and use them as a highly monitored highway.Ships could jump into FTL there without a problem.
The rest of space would not need monitoring except for a couple million km around the corridors.
Just put satellites/monitoring stations with quantum entangled particles around it and if something was going to happen everyone would immediately know because quantum tunneling is instant.
Change particle A here and particle B changes in andromeda for example.
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