text stringlengths 22 2.11M |
|---|
[Question]
[
A classical trope of fantasy is lizardfolk, or a similar species by another name (see for instance the Argonians of Elder Scrolls fame). In general, though, we're dealing with:
* Bipedal, often plantigrade but sometimes digitigrade
* Tool/weapon-using (albeit not particularly sophisticated), with opposable thumbs
* Human-sized (roughly) with often somewhat crocodilian or monitor-lizard-esque features
* Sentient, with a spoken language to their credit
* Oviparous i.e. egg-laying (although this topic is not often addressed) reptiles.
What would be the most logical/plausible evolutionary ancestor for such a species, given the wildlife available on Earth, past and present, to choose from? What sort of evolutionary path would lead to such a species? What sorts of environs would favor such an evolutionary path?
[Answer]
Modern reptiles are too specialized in their reptilian roles, and their metabolism is [too slow](https://en.wikipedia.org/wiki/Poikilotherm) to make them serious contenders for the role of a civilized species.
A serviceable solution would be to make those lizard-folk descendants of a basal [theropod](https://en.wikipedia.org/wiki/Theropoda) dinosaur, such as *[Eoraptor](https://en.wikipedia.org/wiki/Eoraptor)*, which would make them distant cousins of birds.
In our world there is only one lineage of dinosaurs still extant: the birds. They are bipedal, some of them are quite [intelligent](https://en.wikipedia.org/wiki/Bird_intelligence) and some of them [use tools](https://en.wikipedia.org/wiki/Tool_use_by_animals#In_birds). The only problem is that birds don't have functional hands, because a long time ago they adapted to flight. Their immediate ancestors had stiff hands with only three fingers, so we must go back to the beginning of the theropods to find a suitable ancestor with flexible hands which could evolve sufficient manual dexterity.
With this hypothesis there would be two lineages of dinosaurs which survived the [KT extinction event](https://en.wikipedia.org/wiki/Cretaceous%E2%80%93Paleogene_extinction_event), with both lineages belonging to the theropod clade; one lineage went trough the tetanurans, the coelurosaurs, the maniraptorans and produced the birds, while the other went in a different direction and produced bipedal, tool-using, tool-making, intelligent, speaking lizard-folk.
It did not happen, but it *could* have happened. Evolution is driven not only by selection and adaption: luck and chance are equally important. The only big problem is that with Earth dominated by an intelligent species many millions of years before the rise of the higher primates there would be little chance for ape-folk like us to evolve.
[Answer]
**[Troodons or Hypsilophodon](http://www.dinosaur-world.com/feathered_dinosaurs/species/troodon_formosus.gif)**
Troodon are already bipedal, warm-blooded, partially scaled, have grasping forearms, and there are plenty in the right size range. They were the most intelligent dinosaurs (not including birds), and large brains and large forward facing eyes. You will probably need an excuse for them to not be covered in feathers (or at least protofeathers) but it's not too difficult, modern birds still have scales after all, so so would they. All you need is a evolutionary pressure to revert. As a bonus you can have proto-feathers retained on the head or other places for a hair like effect. Ornithopods only have the most primitive from of feathers and are mostly covered in scales.
[](https://i.stack.imgur.com/14K23.jpg)
An alternative is any of the small ornithopods like Hypsilophodon they are not theropods and did not have feathers, although they may have had very primitive proto feathers. They are herbivores. You have a bipedal scaly dinosaur with a five-four fingered grasping hand. They have teeth and beaks at the same time as well as cheeks. basically dinosaurs give you a huge range of bipeds to pick from. I'll put an asterisk in front of the things that would not be true of ornithopods.
[](https://i.stack.imgur.com/uq69Q.jpg)
Now if you want upright bipedalism it's a bit tougher just becasue that has not evolved very often, and there would not be much benefit. But you could swing the body upright as seen in [Therizinosaurs](https://s-media-cache-ak0.pinimg.com/736x/0b/5b/28/0b5b28c684205e28eeca319ece211452.jpg).
**What might you see in the finished intelligent descendant**:
\*They will only have three fingers (two and thumb) dinosaurs lost them pretty early. Their wrists fold sideways, how noticeable this is would be up to you. Ornithopods have 4-5 fingers and the wrist works more like ours.
Their hips will be wider than a human of the same size, and the legs should point a little forward. The dinosaur pelvis is very different than a mammalian one. The more upright their posture the more it will look like a therizinosaurus pelvis, although narrower.
They will be digitigrade, with either three or four toes, basically pick the bird foot you want and use that. You could even have the same foot pattern as velociraptors just as troodons have.
How much of a snout they have is up to you, you could even include a beak if you want it certainly evolved often enough. The head should be bigger than a human the shape of the skull puts more bony support around the jaw muscles, although if birds are any indication they may get more intelligence out of a smaller brain.
the neck should be longer than a human and that means I expect the skull should be attached to the neck at the back of the skull not right underneath it at 90 degrees as in humans.
Dinosaurs and birds have very rigid torsos no flexing at the stomach for them. That's why the have more flexible necks.
Dinosaurs have worse hearing than humans but better vision, especially color vision, how that affects them I leave up to you.
Just don't look at the attempts at a "humanized troodon" it's awful and wasn't made with evolution or anatomy in mind. you'll get something more like D&D lizardfolk in rough body shape than an argonian. But you can decide how upright you want them to be, just keep in mind only mammals have buttocks.
\*Oh one more thing, your animals will not chew, not really, they would have a crop and they would swallow stones (gastroliths) which will do the chewing for them. I could even see a market for hand cut angular stones for this purpose, you might even see wealthy individuals buying hard semi-precious gems like jade or corundum for this. I imagine regurgitating worn out (round and smooth) stones would like seen like any bodily function. Ornithopods on the other hand do chew and even have cheeks to facilitate it and they would not have the stones.
As AlexP pointed out any basal theropod or coelurosaur will work, if you go early enough you can get more than three fingers as well, any you won't have to worry about proto-feathers.
[Answer]
[Crocodile](https://en.wikipedia.org/wiki/Crocodilia).
It's more advanced than other reptiles, specifically including a four-chambered heart.
In fact, it *is* the ancestor of birds. (More rigorously, the [common ancestor](https://en.wikipedia.org/wiki/Crocodilia#Evolution) of modern crocodiles and dinosaurs is very much like a modern crocodile.)
So they evolved into many diverse forms *and* also stuck around unchanged: Most reptiles that were around back then are extinct and are largely unknown by the general population. If you look at when mammals split off, for example, it’s hard to point to a specific ancestor; rather you have to say [some kind of Amniote](https://en.wikipedia.org/wiki/Evolution_of_mammals#Amniotes) and looks like a generic lizard.
It’s easy to imagine a lineage of crocs that continued to advance but retained more of what we would consider to be a reptilian appearance including lizard-like skin. This is what people have imagined as a “dino-man” before realizing that therapods already had feathers.
So this is a unique choice in being a *recognizable* species, and also is exactly what others have imagined in possible evolution from dinosaurs.
[Answer]
### Monitor Lizard
* Commonly considered the most intelligent reptile, showing the ability to count.
* Capable of standing upright. (I haven't been able to find evidence specifically of monitor lizards walking/running upright.)
* Egg laying.
* Monitor lizards do *not* have opposable thumbs. (Though it's only recently that we've seen reptile tool use at all, in [alligators and crocodiles](http://www.livescience.com/41898-alligators-crocodiles-use-tools.html).)
Given that lizardfolk are often presented as using stone tools, it wouldn't be a stretch to say they're slow evolvers.
Lizardfolk are often in magical worlds where evolution takes a back stage to magical bioengineering.
Also, if you have a world where lizardfolk are naturally possible, it's likely that there were different species at some point (for example, gecko-based). (At one time there were two species that modern humans could have evolved from.)
[Answer]
Common Basilisk lizard. The ones you've probably seen in videos running on water (on their hind legs). imho, you need to free up their front paws, which will domino into larger brain size. Our path was probably use of forepaws in the trees followed by going down into savanna and finding them useful to hold weapons. If you don't get them off their forepaws, you're unlikely to get tool use, imho and so unlikely to get intelligence.
[Answer]
Interestingly, the scenario of intelligent tool-using bipedal dinosaurs 51MYa isn't totally implausible.
Had the K-T mass extinction been slightly less severe (eg the asteroid hit at a shallow angle or at a lower velocity, somewhere less dangerous ie with a lower sulphate level) many species might have died out including the larger species but the smaller scavengers could hide underground for a few decades taking advantage of geothermal energy and further develop their intelligence then re-emerge later once the dust had cleared.
The evolutionary pressures later on might have been enough for them to evolve from mere opportunistic scavengers such as ornithopods into hunter-gatherers, lose their feathers in favor of heat and UV-reflective and visible mimic scales similar to a snake or lizard with the side effect that they could also somewhat hide in the background as modern chameleons already do by shifting scale angles or some other variant of camouflage such as chromatophores similar to deep sea squid.
This would have the side effect of making them much harder for predators to spot and may have even given them a significant advantage over mammals.
Interestingly they may still lay eggs but take care of the vulnerable young thus freeing up capacity for brain development which was the main bottleneck in A.afarensis and other hominids due to pelvis size versus head size.
If there were geographical pressures such as an isolated archipelago or some other (cough Zealandia /cough) area then they might have stayed in one small area and eventually over time developed technology based on organic computers which led them to develop highly advanced space travel from primitive liquid fueled rockets to metallic hydrogen synthesized from abundant natural diamonds and Orion drives based on natural uranium a la Oklo without burning through an entire planet worth of resources when finding that another large impactor was en route beyond their abilities to deflect.
This would also leave very little for future geologists to find, the process of mass migration ahead of the impact could involve something like an Orion drive that would totally wipe out the now-deserted island and produce a crater.
Someone should write a science fiction novel using the above, it would probably make good reading.
] |
[Question]
[
I've been thinking of creating a setting similar to that of BattleTech, but set some time around when the industrial revolution is in full swing. This setting would also include bipedal mechs of various sizes, shapes, and weights. When I say mechs, I mean "walking weapons platforms", and not giant human/gundam mechs.
Advantages/disadvantages of such mechs aside, I wonder if there is a valid reason for a bipedal mech to have reverse jointed legs. As an example, think of an Atlas from BattleTech, with its regular jointed legs, versus a Daishi/Dire Wolf with "inverted" knees. Both are 100 ton mechs.
Is there any practical reason other than flavor as to why such a mech would have inverted knees? My wholly uneducated pure speculation would be that a regular jointed mech would have an easier time scaling uneven terrain or steep cliffs and would have overall better balance, whereas on a flat surface a reverse jointed mech could theoretically reach a higher maximum speed. Does this idea have any merit or would it be purely for design variation and fluff?
[Answer]
# [Joints](https://en.wikipedia.org/wiki/Hinge_joint)
Let's say these fine engineers have taken clues from biology and are trying to select some joint for their walkers. They would likely be looking at various "[knee joints](https://en.wikipedia.org/wiki/Knee)" in the animal kingdom.
The big news here is that many of these "knees" are not knees at all. Frequently, these other animals are walking on wrists or even fingers. They all serve a similar purpose: to change the distance between base and top of the limb. In this, there really isn't anything stopping one or the other from performing just fine.
# A Fine Point: Docking!
If your walker needs to raise/lower next to a wall, tower, or building, which I will call performing a "docking" maneuver, reversed knees come in handy here. Reversed knees allow you to walk up to the structure and raise/lower without repositioning the torso.
You can try this with your own legs and a wall: attempt to keep your torso as close to the wall as you can while squatting down. If you face the wall and try to lower your torso, note how your legs (knees) must go forward and push your torso away from the wall. If you face away from the wall and attempt this same exercise, you can raise and lower yourself and stay much closer to the wall. When you are facing away from the wall, you are like a digitigrade (reversed knee) walker.
Since mobile things tend to encounter obstacles and "docks" in front of them instead of behind, there is more likely to be space behind for the joint to move. It's a small difference but may help in certain situations.
[Answer]
# The difference between a knee and an ankle
Forward bending joints and rear bending joints on rear and bipedal legs have separate purposes in the animal kingdom. The knee helps us adjust how far our foot is from the ground. The ankle absorbs impact elastically and redirects the energy into the next push. This is why horses and kangaroos look like they have backwards-bent knees. Those are actually their ankles.
So, for something as big as a mech, a longer "foot" -- a backwards-bent knee -- would be essential for absorbing the weight of any two-legged mech that was capable of actually "running," with running defined as a gait where both feet are off the ground at the same time.
[Answer]
Your knees are always in the way when you're squatting down and trying to see and work in the area on the ground in front of your feet.
It would be much more convenient in those situations if they were out of the way behind you. The best alternative is to kneel, and nobody wants their mech to do that!
To a 100 ton mech, people and many other people-sized things are small, and will often need to be manipulated in this position.
[Answer]
## Let's look at the anatomy of a pair of Mechs in popular fiction:
[](https://i.stack.imgur.com/PtJpC.png)
The savvy one might recognize the iconic MadCat Mk2 from Battletech/Mechwarrior and VF-1 Valkyrie from SDF Macross in GERWALK mode. Both *seem* to have reversed Knees... but do they? Red *appears* as the upper leg, yellow the lower, green the foot - but they are not having a knee in the traditional sense.
The "legs" of the Valkyrie are not legs at all, they are Thrusters, and the joint between the red upper leg and the yellow lower leg is actually at its furthest extent pushed to the front at the moment in the picture. The Valkyrie doesn't "walk" they skate on the exhaust on this configuration, and the next configuration to humanoid does prevent this "under sweeping" of the legs under the torso.
The MadCat Mk2 baffles with its anatomy, the legs being apparently reversed, but there is genuine engineering thought in the madness here, and on a really technical basis, this mech behaves completely differently from normal anatomy: The red upper limb rotates around the hip joint to go forward and under the body, while the lower limb rotates also forward but faster to get off the ground, and a little sideways to get direction done. The result is, that the green foot is pushed forward and lifted. Now, yellow rotates backward, presses the foot onto the ground, until the weight is on it. As the other foot does the lifting cycle, the whole Mech's body moves down as the red-Yellow and red-hip joints rotate simultaneously reverse to the first movement. That's not how a leg or knee works, but it's how your elbow does move your arms - with some twisting coming from that flexible joint. Yes, technically the MadCat Mk2 walks on arms when it comes to anatomical comparisons. And you totally can be done as [a controlled fall forward](https://youtu.be/4Z8KmZnHN-Q) which is exactly how the MadCat Mk2 bobs *down* during each step.
] |
[Question]
[
I have a setting where a nomadic man lives alone in a forest. Presume the wildlife is similar to a typical subtropical or temperate forest. I had the idea that before he sits down to cook, he would always play music using a small instrument like a flute, a small drum, or something of the sort he could easily carry with him to scare away any predators or scavengers near by so that they would not be lured in by the smell of cooking food.
Would this work, and if it does, what instrument should he use?
The instrument needs to be something that can be crafted using only simple hand tools.
[Answer]
Last summer I was talking with a friend who plays taiko (a Japanese type of drum, which was often used in the past for communication during battles or to call the villagers to a gathering): they were telling me that they were in a remote farm to practice, hoping to not bother anybody. Well, not even after 10 minutes of practice, the farmer from the neighboring farm, on the other side of a small hill, came asking if they could stop because they were scaring their horses.
Considering also the effect which New Year fireworks have on dogs, cats and other domestic animals, it corroborates the idea that loud and sudden sounds are effective at scaring animals, in particular those with a sensitive hearing.
So, you can go for a drum, which can be made by simply carving a tree trunk, and maybe tensioning a skin on one end.
However, mind that it can turn against you: an animal can easily associate the noise with food, and then it would act as a call. For example crows in my garden have learned that the door opening around lunch time means crumbles on the tiles and are not scared any more. Therefore you would need to avoid creating a pattern.
[Answer]
## Scottish folk music
Cats (also big ones) and dogs (wolves) have a frequency range much wider than humans. Dogs can hear sine wave sounds to about 54kHz, cats 64kHz. Cats also have a very sensitive hearing.
**Whistles may keep the wolves away**
Dogs can get really stressed when you're playing a tin whistle.. they resent the loud sound. I wouldn't be surprised if wolves react the same to tin whistles ! Dogs can also be conditioned with a soccer whistle or a [dog whistle](https://www.seniorcatwellness.com/do-dog-silencers-and-whistles-affect-cats/), but these are not really musical instruments.
**Hissing or very loud sounds scare cats**
Cats don't like *noise*, especially noise with high frequency components like hissing. Pan flute produces a lot of noise, but that is low frequency. Snare drums may be more annoying. And cats don't like loud shouting, or loud sounds in general.
<https://pets.stackexchange.com/questions/10327/what-effect-do-loud-drums-have-on-cats-hearing>
**Try bagpipes, tin whistle and banjo?**
A common denominator seems to be *loudness*. The loudest flute-like sound I know of is bagpipes. To get noise and loudness, play the banjo. When you play these instruments indoors, it will even annoy people, except when they are fans, of course.
[Answer]
**Dissonant panpipes**
[](https://i.stack.imgur.com/hy9K6.jpg)
Flutes and panpipes are very old instruments that can be created from materials available in a forest. Normally panpipes are created with each pipe tuned to a note in a scale, to make playing pleasing music easier. You could, however, use dissonant intervals like the [tritone](https://en.m.wikipedia.org/wiki/Tritone), or even [microtuning](https://en.m.wikipedia.org/wiki/Microtonal_music), to make the sound harsher and unsettling. Flutes can also be overblown to make squeakier shriller sounds.
[Answer]
## Use Classical Conditioning
Easier to do if the person stays around the same territories.
Before and during cooking, play the music to make it known that a consistent signal is being sent out as a recognizable pattern. This can cause fear in itself, but we want to persuade anything curious that yes, this does mean to stay away.
When animals approach, attack them on sight in the area.
If they watch from afar, no worries that where we want them to be.
AFTER you are done cooking, pack up your stuff, but rather than leaving food, leave poisoned or otherwise painful food that doesn't have to kill, simply teach the animal that even though the food smells good, it's very much worth their while to avoid it at all costs. As mentioned in the comments, animals may be turned off from foods with a number of simple spices (coffee, cumin, peppers) rendering it inedible to them.
Over time when the sound is played, intrusions occur less, and scavengers learn to avoid any food left behind. It may take some time to establish, but the animals may teach their young to avoid the sounds going forward.
Consistency will be required until this new natural order is established. Any instrument could be used most likely, but deep notes, drums, and the like will carry further than something high and sharp like a flute. Though perhaps they only want the sound to go out so far, consider how far reaching the smell of food would be, the same wind will also be carrying the sound to tell animals not to get interested in it.
] |
[Question]
[
I'm building a setting for a sci-fi RPG. The overall idea is a somewhat grounded in reality universe, albeit impractical and honestly quite silly sometimes.
Somewhat like Shadowrun meets Futurama.
In this setting, one of the world-sprawling corporations is a food-based company called CHECKERS.
CHECKERS has, as one of its signature services, the *Orbital Delivery*. You open up an app on your smartphone, select your goods, pay the fee, and in a little bit a package is sent your way from their space-based wharehouse (employment laws are a tad more lax in low earth orbit).
This service is mostly used to deliver shady packages all over the globe - weapons, ammo, legally-questionable devices, underpaid software developers... you name it. However, this highly-questionable service can't be used in the open without attracting attention from all sorts of governments, so CHECKERS needs a good coverup to their operation.
They solved it using Orbital Delivery Pizza.
CHECKERS puts its pizzas - while still uncooked - inside a specially designed shell and shoots it down from orbit towards the target destination. The pizza-boxes use the heat from re-entry to cook their contents, delivering its cargo hot and crispy down there. Sometimes too crispy.
Those containers are - externally, at least - almost indistinguishable from the packages containing the shady goods. To the layman, seeing an orbital package usually means their fellow friendly neighbor ordered a nice pepperoni pizza. To the neighbor, getting that package means that they just got their weekly fix of Gethighnow 20x or similar. So far so good.
This, however, raises a question - Is the heat from re-entry enough to cook a pizza? Is it even possible to build a container able to capitalize that heat and cook the pizza inside?
[Answer]
If you’re designing the delivery system however you like? Sure. Just drop it in a normal (ie large enough for significant compressive heating to occur) capsule and have a cooling loop between the nose cone and an oven inside. Angle the descent so you have at least enough heating time for the pizza, only turn on the loop when the temperature outside is above the internal oven temperature and turn it off when the oven is hot enough.
Perfectly cooked pizza every time, as long as it has a short enough cooking time (as good pizzas should).
The better question is why do this? It would be smaller, simpler easier and more efficient if you cooked the pizza in orbit with an electric oven (using your abundant solar power. You have that right?) then used a small rocket motor to deorbit a small insulated box with a parachute attached.small light box means you need less shielding which means less delta v which means less fuel wasted on the deorbit burn.
Hell, if you want to: cook the pizza using waste heat from the booster you’re using to de-orbit the delivery box. That way it’s possibly the most efficient *and* every pizza comes with a lovely aftertaste of literal rocket fuel.
Imagine the advertising campaign!
[Answer]
Yes, you can. But it will be very, very tricky to do. And also extremely expensive to develop. If you want to develop an orbital pizza delivery system, steer away, there are far better ways to make money.
Reentey can generate temperatures of around 1650°C (3000°F) and takes anywhere from 30 minutes to just over 10 depending on your space craft. Say you have the most high tech heat diffusers keeping your temperature at a nice even 200°C, and your reentry takes no longer than 20 minutes, then yes, your pizza will still be burnt. Most heat dissapation takes place after reentry, as the heat is absorbed by the heat shield. So for a fair amount of time your orbital oven will stay quite hot, cooking your pizza with residual heat. As reducing the temperature further will give you a slab of warm dry rubber instead of a pizza, you will need to reenter quicker. Which most likely generates more heat, so better shielding is needed, which is more volatile. And your pizza will most likely still be overcooked.
All in all, in theory, it might be possible. But you'll most likely end up with overcooked pizza and crushed hopes and dreams. A better approach would be to take the fuel out of the boosters you *will* need, and use it to power an oven. You could bake dozens (if not hundreds) of pizzas with it, and put in a lot less effort and money.
[Answer]
Given that you need special thermal ablative to not cook passengers, I would say it's even more then enough heat to cook pizza. You can re-enter in many different angles, so you could pick baking time even.
[Answer]
**You can, but what about the shady cargo?**
If you can cook the pizza, the real cargo may go to waste because it is literally inside an oven. Cook the pizza first and keep it warm enough until landing. The reentry heat should be shielded.
[Answer]
As a former pizza cook in the part of Florida where we could see the shuttle going up, I feel uniquely qualified to provide some additional data point. Our Pizzas would be cooked in an oven at about 400-475 F for 8-10 minutes time. The Orbiter (the part of the shuttle that looks like a plane, the entire stack is "the Shuttle" according to NASA) on reentry will experience temps of ~ 3000 F for about 3 minutes to 30 minutes depending on approach (pre-Shuttle was about 3:15 minutes (straight dropped) while the shuttle was closer to 30 minutes (gliding to landing)). Angle of re-entry is important as the shuttle's glide meant it had to take a shallower angle, where as the Apollo and earlier had a much steeper angle of re-entry... this is somewhat covered in the conclusion of Apollo 13, with the longer period it took to re-establish communications (nearly double the time of typical Apollo missions), because they had a much shallower re-entry angle owing to the fact that much of the planned mission had to go out the window. The window for descent had to be changed to get them down earlier.
This would be a temperature and time would be more than enough to not only cook my pizza, but melt my oven to slag to boot. The temperature is also sufficient enough to melt the aluminum frame of the shuttle if left unshield, which was what ended Columbia (the shield break was in the under wing, which compromised the wing and caused the oribiter to go into a violent barrel roll spin, breaking it apart). For a reference, 3000 F is about 1780 F hotter than the melting point of aluminum, which is the metal used in the shuttle's frame. And itt may only be by 800 F less then re-entry heat, but even lava is cooler!
Because it's so hot, most people don't quite get how hot it can be. Rest assured, I, your pizza space man have seen the heat resistant tiles in action, up close and personal (the white ones, which don't resist heat nearly as well as the black ones). NASA does have a "used" tile on hand and I was once selected to demonstrate their resistence by placing my then sixth grade aged hand on the tile while the tech hit the other side of the tile with a blow torch. My end remained cool to the touch (I however was not cool as no one asked "are you afraid of fire").
That said, looking back, it should be a point of knowledge that NASA educators felt comfortable to hold a lit blow torch that close to a child's hand and not get sued by the absent parents. So your exposed pizza would be basically be vaporized while your properly shielded for re-entry oven would be a cool as an uncooked pizza when it landed. And I should point out that you should not be allowed in a kitchen if you think raising the heat will lower the cook time at the same ratio. Ovens do not work that way.
[Answer]
First of all, it would *not* work at all. The box would melt, yes, but then the contents inside would melt too. Unless you can put a heat-resistant shield on the actual shell, of course. Maybe before it lands, a parachute will be deployed so that the item inside lands softly.
] |
[Question]
[
I am writing a scifi novel based roughly four hundred years from now, and it occurred to me that the planets and other objects might not be quite where I need them to be for certain travel details to make sense.
Primarily, Eris and Pluto have irregular orbits that take a *very* long time (558 and 248 year respectively), which sometimes puts Eris closer than Pluto. This is a problem if I write that Eris is the last stop before exiting the solar system if Eris is at ~38 AU (perihelion) and Pluto is at ~49 AU (aphelion).
**Are there any software tools available to accurately map the solar system hundreds of years from now?**
[Answer]
JPL's [HORIZONS](https://ssd.jpl.nasa.gov/?horizons) system will give you ephemerides, charts of a planet's location in the sky (via right ascension and declination) and position in space via quantities like the [true anomaly](https://en.wikipedia.org/wiki/True_anomaly). You can find ephemerides for all eight planets, as well as about 800,000 asteroids, comets and moons (yes, including Pluto and Eris).
HORIZONS is quite accurate, and allows you to make calculations in a variety of timesteps (and shows you intermediate positions along the way!), ranging from days to years. The shorter the timestep, the better the accuracy, but the longer it takes. Usually, it can calculate ephemerides for up to 500 years in the future.
There are a number of interfaces, with the simplest being the [web one](https://ssd.jpl.nasa.gov/horizons.cgi#top). Pick the option that suits you best.
[Answer]
The Universe Sandbox has the ability to simulate planetary physics. I doubt that it is 100% accurate, but as a tool for projecting a future it may fill your need.
Alternately, the math for working out roughly where a planet is in its orbit is not overly complicated. Find when their next perihelion/aphelion will occur, and simply add the time required to complete 1 orbit. Another nice thing about perihelion/aphelion is that the planet takes about half the orbit time to go from one to the other.
[Answer]
<https://celestia.space/> is what you need. [Wikipedia](https://en.wikipedia.org/wiki/Celestia) suggests that NASA and the ESA use it for education. It's open source, and it is available for AmigaOS 4, Linux, macOS, and Microsoft Windows. Plus there's a heap of add-on's if you know where to look.
[Answer]
The combination of Real Solar System and Principia mods for the commercial game *Kerbal Space Program* provide planetary motion for the Solar system, giving correct eclipse dates and times for a least a few centuries into the future. The game is inexpensive (under $50), and the mods are free downloads. The lesser bodies (minor moons of Jupiter and Saturn, lesser asteroids) aren't covered, but unless you need to know where Gaspra will be, that isn't likely to matter. Ganymede and Titan will have correct "eclipse nights" well into the future.
[Answer]
I might recommend [Space Engine](http://spaceengine.org). Some description first, then my own thoughts.
[Wiki description](https://en.wikipedia.org/wiki/SpaceEngine):
>
> SpaceEngine (stylized as "Space Engine") is a proprietary 3D astronomy program[2] and game engine developed by Russian astronomer and programmer Vladimir Romanyuk.[3] It creates a three-dimensional planetarium representing the entire universe from a combination of real astronomical data and scientifically-accurate procedural generation algorithms. Users can travel through space in any direction or speed, and forwards or backwards in time.[4] SpaceEngine is in beta status and is currently freeware for Microsoft Windows.
>
>
>
Here's a brief blurb from the site:
>
> An almost infinite procedural Universe is seamlessly blended with real objects known to modern astronomy. You can find our own planet Earth and the Solar system, famous stars with recently discovered exoplanets, hundreds of galaxies with real shapes. The power of the procedural engine fills known galaxies with procedural stars, creates procedural planets near real stars and generates procedural landscapes for all exoplanets and uncharted objects of our Solar system.
>
>
>
The key points are 1) it's windows software 2) that's free 3) which gives an accurate simulation of known celestial objects and 4) fills in unknown data with procedurally generated objects.
It's not a pure 100% physics simulation. For instance, the sun won't go red giant and consume the earth after a few billion years. Wikipedia also points out "stellar proper motion is not simulated, and galaxies are at fixed locations and do not rotate." (I think I tried to simulate the Andromeda collision, but that won't happen) But the positions of planets should be accurate, especially in the time frame you mention.
Things I like: you can travel around the universe at various speeds. Anything from 1m/s to AU per second. You can travel to a moon and watch the planet-rise. You can control the FOV and camera projection. You can change the timestep (very slow or very fast, anything in between), or jump to a specific date time. And the physics don't get wonky at increased speeds, like they do in Universe Sandbox. There are user addons and some official expansion packs, like high detailed maps of the planets in our solar system.
Things I don't like: The UI is rather deep, it has a steep learning curve. Like a lot. You're going to be in the manual trying to figure out how to do simple tasks. Grab a piece of paper and make a cheat sheet. Also, it's still in beta, there are a few glitches you will encounter sometimes. Off the top of my head, I remember an issue when switching between camera projections a lot, and the space ship movement has some weird collision issues.
Other thoughts: The last version was released a couple years ago. There's a new updated planned "soon" which will be $20 on steam. I only mention the price to say the author has stated the old versions will continue to be free, and these already have quite a lot of capabilities. You can see a lot of user discovered screenshots at <https://www.reddit.com/r/spaceengine/>
edit: Sorry for the delay, here's a screenshot of Eris in the year 2347 (just fast forwarded a bit to no date in particular).
Here I've turned on markers for comets and asteroids
] |
[Question]
[
So, I have a question that focuses on a character from a show, Spongebob. Sandy Cheeks lives in a reverse aquarium under the sea in Bikini Bottom, in a dome that looks like this 
The Treedome is made out of polyurethane, and had grass and an large oak tree. My question is, could you make the treedome in real life? It would need to solve five problems.
* Where to get food
* Where to get water
* Could she survive in that temperature
* Where to get oxygen
* Pressure
Bikini bottom is located in Bikini Atoll’s sea floor, where ch is about 180 feet, or 55 m underwater.
[Answer]
If she has a basement beneath that dome holding a lot of equipment, yes.
She'll need equipment to do electrolysis to split water into hydrogen and oxygen, so she can breathe. She'll also probably need some kind of furnace, in which she can burn kelp or other plant matter. This is because the tree and grass probably need more CO2 than can be provided by one squirrel. I highly doubt she and the tree are in perfect CO2-O2 equilibrium. She'll need desalination equipment to get fresh water. Pressure is no issue. Submarines regularly dive much deeper. It won't be all that cold, so heating is not too much of an issue. Temperature varies a lot as the ocean currents change, but it will generally be about ~60F or ~20C at that depth. She can get food with hydroponics and grow lights. All of this will require electricity, so she'll need some kind of power generation; maybe geothermal or nuclear. Fossil fuels don't work because she needs the oxygen.
At 55m depth, there will still be some light, but I don't know if it is enough to keep grass and an oak tree alive. It will be approximately 25% of the light on the surface. I suppose she could use more grow lights, but we don't see them when we look at the dome.
[Answer]
At 55m the pressure is about 5.5 bar, which is the same as, roughly, 5.5 atmospheres a polyurethane dome can take that, it's only 80 something PSI. At 55m there's still generally enough light for photosynthesis, but it's getting sketchy, coral bottoms out at about 60m so the grass and the oak tree are a stretch but possible, especially if they aren't *quite* what they appear to be. The water temperature at that depth is difficult to qualify, depending where in the world Bikini Bottom is it could be as high as 30°C or as low as 4°C but whatever it is, due to the high specific heat of water, the atmosphere of the dome will be the same temperature. With sufficient vegetation food and oxygen are taken care of, as it is in the images we get of the dome that isn't the case for a human sized creature but for a squirrel of "normal size" that may actually be enough photosynthesis and enough acorns and grass seed. Otherwise she's going to need a means of [electrolysis](https://en.wikipedia.org/wiki/Electrolysis) to "crack" water for Oxygen and she'll need to bring in food.
[Answer]
# The dome won't make it
Hydrostatic pressure is
$$ p = \rho g h ,$$
where $\rho$ is the density of seawater (1025 kg/m$^3$), $g$ is the acceleration due to gravity (9.8 m/s$^2$), and $h$ is depth underwater (55 m). Thus, hydrostatic pressure at the given depth is 552 kPa.
Let us assume a spherical dome that can contain an oak tree comfortably. Lets say the dome has a radius of 50 meters. The total surface area of such a dome is the area of the corresponding circle, $\pi r^2 = 7854 m^2$. Multiply this by the pressure and we get $4.3\times10^{9}$ N of pressure.
Can such a dome make it? Not if it is made out of any known material that is transparent. Lets assume the force of the water pressure is concentrated around the circumference of this 50 m circle (314 meters). This yields am equivalent of 14 MPa of pressure on the entire glass circumference. Glass typically has a tensile strength of 7 MPa and compressive strength of 1 MPa; not enough for this application.
A glass dome would be crushed by hydrostatic force at this depth. Sandy is getting wet.
[Answer]
>
> "The Treedome is made out of polyurethane"
>
>
>
Are you absolutely sure about that? PUR is usually used as insulation, so it probably helps with the temperature. But it's generally not strong enough as a weight-bearing material. You can make a couple of bushings, sure, but a dome under that much water... I'd guess it would become a very thick layer. Which brings the following:
Making a dome out of see-through PUR is hard. Especially since PUR tends to discolour under light. Yes, there's not a lot of light at 55m, but it's no total darkness either. There's also the problem of some ground-living fungi being able to eat the stuff, depending on what type of PUR you use. Polyamide (nylon) might be a better fit. Added benefit is PA can be poured instead of woven, making it easier to get it in any shape you want.
] |
[Question]
[
**Closed**. This question is [opinion-based](/help/closed-questions). It is not currently accepting answers.
---
**Want to improve this question?** Update the question so it can be answered with facts and citations by [editing this post](/posts/79402/edit).
Closed 6 years ago.
[Improve this question](/posts/79402/edit)
My name is Tavish Wallace. It's April 10, 2027. The end of the world. Governments are trying to hold as much power as they possibly can until their imminent demise. Military forces are stronger than ever, eliminating their enemies with an iron fist. At least, that's what they'd have you believe. Behind that facade, however, anarchy rules. Shops are being raided, murders happen every day, fire is everywhere.
And We're running from it all.
It's just me, my elderly parents, my wife, and my son.
Everybody is after us. Bounty hunters, the army, even my old neighbors tried to kill me. But I don't care, they haven't caught me yet. They'll all be dead by tomorrow.
I'm meeting another group who's on the run up on the mountains. We're travelling together with them from there to find a safe spot to hide until everybody else dies off.
**It's 10 years in the future. We're searching the [Appalachians](https://en.wikipedia.org/wiki/Appalachian_Mountains) for a structurally safe place to hide 13 people until the end of the world. There isn't anybody around for miles. Where do we go?**
Also,
It would probably be helpful to know what the party is carrying, and what trades the different party members have:
My father is an electrical engineer and my mother is a seamstress, along with Jared Hale and Austin Carr, who are travelling with us. Michael Thorpe, also travelling, Is a metalworker. His wife Angela is a botanist. I am a carpenter. Besides these, we have have 2 mothers, and 3 children. In all, the entire party Has 1 .50 Caliber Rifle (with a scope), 2 Glock 18s, and one Smith and Wesson 460V. We have 2 Medical kits (with antibiotics), and 673 servings of canned food.
[Answer]
Personally, as someone who lives in the area, I'd find a hill/ridge. Away from trails/powerlines/sparce tree cover, and preferably near a stream (DON'T DRINK DOWNSTREAM FROM A BEAVER POND) and build a [I forget the name of it], you stick branches into the ground, then weave smaller branches in between them, you make two layers of "walls" this way, then fill the space between with leaves. Or in a pinch make one of [**these**](http://www.fieldandstream.com/photos/gallery/survival/shelter/2006/10/seven-primitive-survival-shelters-could-save-your-life#page-5). If you can salvage a tarp, line the ceiling/floor with these to keep out water. Build it up against a craggy rock (those hills are filled with them) and heap leaves over/against it to conceal it. Climbing the ridge will allow you to see potential approachers (via wood-smoke, trails, or flying contraptions), but building on the side of it means you won't be silhouetted.
This is more efficient than seeking out a pre-existing shelter (avoiding random encounters and people [probably locals] who got there first), and you won't be utterly devastated if you need to bug out and re-locate.
While this likely isn't as interesting as a "forgotten" bunker (yes there are some of those up in the hills), you'll be more likely to survive.
Alternatively, there are a few former-industrial/farming towns among the foothills. There are buildings that were abandoned hundreds of years ago and rotted away, leaving behind their basements and wells surrounded by miles of forests. These square ditches are commonly found in twos and threes. It wouldn't be too difficult to build a layer over a basement and cover it with loam and detritus, but you would be closer to a settlement with a greater chance of discovery.
[Answer]
I'd suggest looking for **a long-closed mine whose entrance you can force open covertly and is structurally sound, at least around the entrance** (and I'd stay as near the entrance as possible while remaining hidden.) A key bonus would be a mine with usable water that you can get to. Beware bad air (methane) and welcome to the Resistance!
If you are especially brave/desperate, consider mines known and marked as closed due to collapse accidents. Your pursuers (and competition) may be put off by the known risk. You only need to find a small area you can get to (and stock) that's safe, or shore it up if you can scavenge the tools and materials covertly. Be careful to disguise any lumbering as the work of busy beavers; likewise, brush away your footprints, etc.
Note well that mines often had multiple openings (for safety, ventilation, pumping out water, etc.) and the main entrance is probably where hunters would look first. So try to avoid the 'front door' and instead search for an auxiliary entrance and use that instead.
[Answer]
Caves or Mines would be your best bet, but you may have other options in a pinch. Just remember the following things and you might be ok regardless of where you end up.
1) Water. Know where your water source is. You can last a long time without food, but only a few days without water.
2) Shelter. It means more than a place to hide. You use it for maintaining heat. It can get COLD in the mountains at night. Hypothermia is a real danger. If you can't get in a cave, you can make debris shelters, use rock overhangs, and so on. You can build a debris shelter inside of a cave to help with maintaining heat and be out of sight and out of the rain. Strangely, structural soundness is a secondary consideration until you decide to stay there for more than a night or two.
3) Fire. For the same reason as shelter. You need to maintain heat. You should have plenty of fuel up in the Appalaichan mountains. Here is where it gets tricky. you need to hide the fire and smoke as much as you can. I have seen some interesting stuff regarding rocket stoves for camping and cooking, and a 2 hole method for building a fire in a way that hides the light and smoke fairly well.
4) Food. This is actually the least of your worries at first. Yes you need food, but going without for a few days won't kill you. Deal with water and shelter, then you can start worrying about food acquisition. Hunting is the obvious thing, and you can easily rig snares and deadfall traps. Fishing is an option depending. Don't worry about large game until you get the basics well and truly squared away.
I would say with a little research, anyone can and should build a **S.H.T.F.** pack or **Bug Out Bag**. It can be done for less than $100 US for a really fancy one. Heck, a pocket knife, a poncho, a lifestraw, some string, and a mylar emergency blanket gets you most of the way there. This is useful for the end of the world, or a tornado, or a flood, a blizzard, tornado...etc etc.
[Answer]
Not sure what you have in the Appalachians, but in the Adelaide Hills we have some old rail tunnels that have been converted to mushroom farms. They'd be my first port of call if I was looking for somewhere to hide.
] |
[Question]
[
**Closed.** This question is [off-topic](/help/closed-questions). It is not currently accepting answers.
---
This question does not appear to be about worldbuilding, within the scope defined in the [help center](https://worldbuilding.stackexchange.com/help).
Closed 12 months ago.
[Improve this question](/posts/39379/edit)
So, you died. Good for you. Luckily, due to various scientific advancements that spit in the face of biology, philosophy, engineering, and general plausibility, you’re technically not dead! Your body is, as well as your brain, but your consciousness has been mapped and uploaded to the big server farm in the sky, and now you’re here!
So, obviously, this is some sort of transhumanistic, ghost-in-the-machine, virtual afterlife, and that comes with two major perks. Functional immortality, and free reality-bending powers, to some degree. But this is where things start to get complicated.
There are two extremes: A setting where everyone can just make or do anything, to anyone, without limits, without any need for skill or experience. At all. Think of a puppy. There is a puppy. You just willed a puppy into existence. Think of someone's head exploding. That guy's head just exploded. You did that. Think of begin god-king of the universe. You are now god-king of the universe. Someone else wants to be god-king. Someone else is now god-king. You kill him with your mind. He comes back and kill you. Now someone *else* wants to be god-king. You can see where this is going. Clearly, this is a terrible, terrible idea, and the decline of the virtual paradise will be swift and drastic.
The other extreme is that only one person, or maybe only a few people, know how to control the artificial reality, because they’re the ones who made it. This is also not a great idea, for the same reason that if humans can do something without any consequence, they almost invariably always will. Those few with the power of gods will act like gods with human values always do, and things will start to go downhill.
So, our two options are anarchy, and dictatorship. There needs to be a balance between the two, and some form of maintaining general peace and making sure everything doesn’t fly off the rails. But before we implement any kind of existing government, here’s some important information.
---
## Dying
Getting killed is not a big deal. If you die, you pop back up somewhere nearby within a few minutes. It still hurts, but not nearly as much as being killed for real, and doesn’t really have any permanent psychological effects. Killing someone is kind of equivalent to punching someone in the arm, really hard, and for no reason. It’s not the worst thing you can do to someone, but it also makes you kind of a D-bag. If someone killed you, then stole all your stuff, you’d probably be more mad about all of your stuff being gone than actually dying.
Also, you can actually die if you want to, because as we all know, [immortality sucks](http://tvtropes.org/pmwiki/pmwiki.php/Main/WhoWantsToLiveForever).
## Reality-Bending
People can change their reality. Obviously not at first, but the only upper limits are time, determination, and how much you actually have to learn. If you get to the point where you have complete and utter omnipotence and omnipresence, great. You win. There is literally no aspect of reality you cannot control. You hit the level cap. Have fun. This would take a really, really, really long time, and would honestly be pretty boring, so most people don’t do it. It’s kind of like memorizing the dictionary. Theoretically, you could do it, but most people just get to a point where they can see anything within a billion light-year radius, can create entire galaxies with the snap of their fingers, shrug, and say, “Yeah. That’s good enough.”
Some Reality-Bending Rules
1. The pre-existing laws of physics are viewed as “suggestions” by
most. You can defy gravity, but given that it's pretty useful for
keeping stuff on the ground, as long as no one's actively changing
it, physics will snap right back to what passes for "normal"
2. People can change themselves, including minds and bodies. Do so at
your own risk.
3. No time travel. Because that would require sending data (i.e. the
data making up a person or thing) back or forward in time, and it’s
complicated enough already.
4. You can’t change some stuff, just because it’s so basic. There are
definitely aspects of the universe that would definitely cause
everything to stop working if they changed, so the people who built
the universe had the foresight to make them tamper-proof. It doesn’t
stop people from trying, though.
## Destroying Everything
If you do something that would destroy a decent chunk of the universe, then you’re going to get some sort of popup message that says something along the lines of “It looks like the action you’re about to take would destroy most of reality. This will likely inconvenience many hundreds of billions of people, and cause them all to blame you for this. Are you sure you want to continue? Y/N” This does not generally happen, given that it takes a lot of time and skill to even destroy a few square light-years, and when all those billions of people come back, they will likely kick the living daylights out of you, one at a time. This creates a surprising amount of peace.
## Self-Contained Universe
It governs itself, because it has to. There is no outside influence upon reality, or at least no provable one. People die, pop up here, and someone shows them around and welcomes them to the club. That’s it. At no point is a lab tech somewhere back in the real world going to use his admin powers to ban someone for being annoying. You have to deal with that yourself. Any laws beyond basic universal structure are made by someone on the inside.
## Knowing What You're In For
You sign up when you’re alive, they put a thing in your brain, you die sometime later, and then you wake up here. People may not know *exactly* what it’s like, they can’t look into the afterlife and see, but they know roughly what to expect. that means that they know they get immortality, reality-bending, and things like that, but they know nothing about the societal or governing structure in-universe.
## Infinity?
Computers are bad at infinity, so the universe is only functionally infinite. That means that at any given moment, it has a finite number of space and atoms in it, but you can always make more. The universe can be made bigger, and more things can be made. Difficulty of making them scales up with complexity, so, making a $1\text{m}^3$ block of silicon atoms is a snap, but making an entire computer is quite a bit harder.
---
All of this clearly invalidates, or at least complicates, most traditional forms of government. So here are some some basic requirements.
1. It needs to work, and work well, for a long time. These people are
going to be around for a very, very, *very* long time.
2. People need to be happy, or at least the vast majority. The whole
point of there being an afterlife is that it’s actually better than
normal life.
3. There need to be rules. Murder is sort of a non-issue, but other
general human terribleness should be kept in check.
4. These rules need to be enforced. Maybe the populous is kept in check
by those who have ascended to near-godhood. Maybe there are
artificial entities already in place as part of the universe’s code,
to act as lawmen. Maybe it’s all just held in place by
mutually-assured destruction. If you kill someone, they’ll come back
to life and kill you right back.
5. These rules are subject to public opinion. Same reason that, “If one
finkf when one fhould floate, then they are decred gilty of
whichcrafte ” isn’t a law that’s on the books anymore. Times change.
6. There needs to be some degree of stability. We can’t have the
governing body in wherever you live being overthrown every other
week.
7. Ignore the other six requirements. Of course it can’t work properly!
Where’s a story without conflict! People should be dissatisfied,
laws should be broken, punishments can be avoided! Chaos needs to
exist, if only as the exception to prove the rule. If everyone were
happy with everything, all the time, then nothing interesting would
happen. A utopian society is not going to happen. All I'm looking
for is something that keeps the universe from burning down or being
consumed by lovecraftian monstrosities, while still allowing human
demi-gods to run around and do/make fun stuff.
So: **How to govern a society of functionally immortal reality-benders?**
[Answer]
Why would you be allowed to mess with other people's data? We don't do that *now*: you visit web sites and customize them within the scope of their design, and *could* make one from scratch or even own your own server. But you don't change up a public site beyond your own account or beyond its custimizability.
Likewise, you can create VR spaces and invite others in, but you can't edit those owned by someone else, and public spaces will exist with limited ability to alter at all.
Now maybe there will be free-for-all sandboxes that you can play with, both shared and private. But there will be places set up to be a certain way and the whole reason for using then is that it *is* that way and a beach, for example, won't change into an office building.
Your premise seems to imply that it's set up as a single global reality with 3D positions like our real world. Why? Places will have their own disjoint 3d space within them, and multiple places exist simultaneously.
[Answer]
I think your best bet would be to have an up vote/down vote system for behaviour. Committing a crime gets you down votes. Murder would be 1 down vote and serious crimes like rape and kidnapping are say 100 down votes with other crimes in-between. The down votes would be decided by a panel of judges, say 3 per case. When a crime is committed the victim reports the crime. If the perpetrator is known then the judges summon them to stand trial. If they refuse they have 100 down votes automatically given. If the perpetrator is unknown the judges seek out evidence, like a modern day police force would.
Up votes are gained by doing good for your community. Up votes will also be handed out at a rate of 1 per year as standard however criminals lose their up vote gaining for 10 years as standard. The number of votes you have determines how many powers you can gain although you still need to practise to reach the full potential of your current level. So a lazy 100 voter has the same powers as a 80 voter who practises a little or a 50 voter who practises constantly.
Judges are people with over 1000 votes. If a judge has any down vote they instantly lose their judgeship. Judges have the power to give down votes along with other powers unique to judges. Killing a judge gives a huge penalty as judges are crucial to society running correctly and killing one inconveniences everyone.
[Answer]
## Everyone has a budget of CPU power and memory for "Mods"
By default, the simulated Universe runs a rough approximation of the physical one, with the same laws of nature. This can be changed by people "modding" the simulation in a specific location. How much they can change is limited by their personal budget. This may start out small and increase with responsible use and decrease if the mods cause issues. A person doesn't know their exact budget, but will notice it takes more and more effort to add or maintain changes until nothing extra happens anymore.
* People can pool their budget by cooperating on some "mod". Whole groups can set up their unique slice of the Universe with completely different rules.
* Changes attempt to overwrite each other, causing a conflict. If person A is maintaining a mod that makes the sky look pink from a certain location and person B tries to make it look blue again, the two instructions will use up both people's mod budget until one gives up or they reach a compromise. Since this is costly to the system, both person A and B will have their budgets shrunk slightly. This discourages conflict and encourages communication and cooperation.
* A person has increased CPU priority on their own avatar and home location. This means it's very easy to protect oneself from hostile modding and even mod ones way out of normal danger. All the conflict's budget penalties are allocated to the hostile person. A home location cannot be claimed in conflict, because the oldest active claim takes precedence.
**Example time!**
A group of people have banded together and set up "Furryland". All avatars entering this zone instantly sprout a soft, smooth fur all over their bodies, while their faces take on an animal aspect and their eyes grow huge. This is maintained by the entire group, leaving them most of their budget for further private perversions mods.
Any person entering can allow the mod to take effect without expending their own budget or decreasing that of the furries. If they resist, they will get priority and no change will happen, but this is taken out of the furries' budgets. Before long a group of hostile people is trying to ruin Furryland by making mud tornadoes and fighting the changes to their avatars, costing the furries their mod budgets. To prevent this, the furries set Furryland to be their home locations, abandoning any other claims they might have had. Now, the priority works as follows: The home location effects now override the mud tornado, with penalties going to the hostiles. The hostiles' personal resistance to the furry effect still overrides all, but it doesn't penalize the furries in their home location.
One lone griefer tries another way: modding boulders out of thin air far above Furryland, then letting normal gravity drop them on the poor furries. He reasons that since the simulation is the one creating the big crash, the furries can't negate his mod. However, what happens is that with very little effort, barely more than a reflex, the people underneath the boulder can mod it away before it hits them or their home location, this being an exception to the rule that modding the default simulation costs effort/budget.
**Conclusion**
Within this framework, cooperation is rewarded greatly by the ability to create and maintain greater things, as well as protecting them through the "home" designation. Conflict is punished by diminished ability to change the simulation. With everyone having supreme authority over their own avatars, you don't need law enforcement, though people certainly can set up a cooperation to prevent "griefing" and other abuse, as well as organizing to create greater things on a cosmic scale.
[Answer]
A book suggestion for you, where all these topics/issues are touched if not even solved:
[Pink Noise: A Posthuman Tale](https://sfbook.com/pink-noise.htm) by Leonid Korogodski
The books setting is a bit different as the world is filled with three intelligent, cognitive races. It is also set in a far-future era. There is usually no interaction between the three races. This is by law, based on a decision after *the war*.
# Three races
## actual humans
again split into more groups that have massive genetic differences, as they spliced there genes. It is so big, that they are not able to easily (if at all) communicate anymore.
They have mixed communities where the communication works via a chain off intermediate versions of the two ends of the line. So a fish-like human speaks to a bit less fish-like, this one speaks to a fish-insectoid-like human, and so forth.
Humans also live in small enclosed communities. The planet is mainly inhabited by plants and non-human species, although more or less every little piece of the flora and fauna is genetically engineered for specific purposes.
## Androids
They are robotic life-forms that evolved(?) from what we usually take as a typical robot. They mainly take care of the planet in the long term. One example is, that they change the direction of an astroid a tiny little bit, because there is a probability of a collision in around a hundred thousand years or so.
## (simulation based) Artificial Intelligences
The third race is living in big simulated environments. The main actor of the book is one of them, so the reader learns way more about the details of them as of the others.
There are different simulations which are like countries. You can move between them, but it is not without effort – unlike inside one simulation. This is due to the needed transfer from one *datacenter* to another. There are big differences from simulation to simulation, for example how new individuals are born.
This is how the book starts: It describes in detail how the main actor gets born. I absolutely recommend anyone to read at least this part.
There is also of course immortality and reality bending to a certain point. The AIs are jumping inside the simulation without any effort. So they can for example watch the Robots (they have a nicer name in the book I don't remember) changing the trajectory of an astroid, in real time. But they know – and also mention – that it is not actual real-time, as they are only spectators watching recorded data. Light-speed is still the limit.
# Immortality
All the AI individuals are technically immortal. There is a *very* slow but not zero birth rate, though. They keep their minds clean by changing it. It is like taking drugs, but more on that later.
# Reality Bending
AI people (has anyone a better name?) are able to change there environment. They have to obey physical laws, though. So what the simulation does is to perfectly(?) simulate physics but give the individuals a direct channel to manipulate it. So they cannot destroy the universe but easily create a four-dimensional cube floating in front of them.
In order to do such things, they need to be able to understand the math behind the physics. So it is a big effort. Some things – like changing their position – are simpler, because there are "APIs" for that. They think of it and it happens. Other things need to be done with lower level interfaces, so they are more complicated. Not everyone is able to do so and individuals are usually focussing on different things.
# Changing themselves
There are ways to change the innermost of the simulation based individuals. But they cannot be forced to do so. It is an active decision to upload code that changes yourself. Some of them are very prone to do that and naturally it becomes more "normal" for individuals living many hundreds or thousands of years. Some of these *programs* are handled like drugs. Mainly because they can be very dangerous, they are not exactly illegal though.
# Communication / Latency
AI individuals are communicating via interfaces like nowadays network programs or webservices do.
They have unique identifiers and can sign messages and so on. As expected, it is all based on mathematical methods. They use something like [asymetric cryptography](https://en.wikipedia.org/wiki/Public-key_cryptography). That enables them to communicate privately and to validate the origin of a message.
Latency is no problem at all as the simulations are inside single, massively protected data centers. These datacenters connect to the real world via sensors, that are everywhere, except inside human-populated areas (part of that law that prohibits the interaction between the races). The simulations are also running way way faster than the real world, so if the actors want to watch an event in real-time, they have to slow themselves down (what they can easily do if they wish).
# Law
The laws are very clear in this world. There is the global law existing between all three races, that was created after *the war* and there are different sets of rules in each simulation. These rules are implemented in the core of that simulation. I'm not sure if they can be changed. There is also general consenus between the individuals and a kind of law enforcement.
[Answer]
Well since money makes no difference and you are all code in the computer. Then might as well use something everyone would be interested in.
Maybe even mind controlling literature which can cause your free traveling mind to become subservient without you knowing it.
[Answer]
I have actually heard of a philosophy, the name of which escapes me, in which we are actually reality warpers. It's a form of solipsism, basically saying that every single intelligence in the universe has conscious control over everything covered by its awareness. What complicates (and yet simplifies) this, is that over 7 billion people in the world have some influence. Like two people pushing an object from opposite sides, but instead it's 7 billion conflicting perspectives. Reality resolves itself by obeying larger consensus bodies and ignoring the less popular opinions.
Hypothetically, if such a world were to lose all but one intelligent mind, that mind would have complete at-will control over what was real.
[Answer]
For me, the question falls apart at the part that goes "*So, our two options are anarchy, and dictatorship. There needs to be a balance between the two*".
A change that fundamental will quite probably mean that the choices we currently might assume from human nature will seem very naive after a while, and choices and reasoning for them that we don't imagine now, would dominate. So assuming "new world but basically same life" doesn't work. Much like people used to imagine gods a bit like "people only stronger". Whatever people are now, these would completely change their understandings.
Perhaps people there go "who cares what they do for the first 20 billion years, let them". Perhaps the concept of ownership and proprietary/possessiveness fizzles and people see reality as art, and random change/creation/destruction as development in that art, all equally valid. Who knows.
Perhaps if death, loss and imprisonment don't help, people will do things they can't here and now, such as having your mind changed to mush - after all if you're a drooling wreck or have no memory of past matters, you can't so easily use your superpowers to change yourself back perhaps. Will that be possible?
Point is, *you cant import human expectations*. You can't expect to take a completely new paradigm, then figure its going to work based on how people react/ motivate/behave in this more limited world and lifespan, because the very beliefs you're using to assess how it might develop and therefore what governance if at may exist or be wanted, won't be held since the reality underpinning them will differ.
My bet is that human nature and understanding of life would change enough that governance as we see it just wouldn't be applicable, nor its lack a problem. Would the concept of "I" even remain the same? Doesn't seem likely. What would be discovered given that timespan? What would be valued? Why would it be? What would we learn of reality and its manipulation in a few quadrillion years (apart from "oh god, boring!")? People do things "to be remembered by history" but will that still be so? People do things knowing they'll be dead in a while and can forget it, will that be so? Those seem a bit more fundamental than how we'd govern and settle disputes.
The question is at heart, all about how we'd manage disputes in such a world. My feeling is, you can't settle disputes without experiencing what causes them, why they matter to other people, what matters to the participants that can be leveraged to resolve it, and what motivates people generally.
Can we imagine the answers to these that a few billon year old beings might have reached?
[Answer]
# The same way we do now
...that is to say by reaching a consensus regarding the rules, rules which we base on our own emotions, our logic and our empathy (that is to say our ability to feel other people's emotions).
[Answer]
I think it will end up like so many online systems do: there will be some powerful users, and with a bit of luck, at least a sufficiently large part will be (mostly) benevolent, even if some of them might develop a god complex.
But what the heck: they are as god-like as it gets, so no harm done there.
These, let's call them super-users, will come to the aid of weaker users when those fall victim to trolls.
The trolls should be fairly easy to confine if a group of our superusers team up together to somehow banish them.
They might even create an illusion inside the illusion, push the trolls in there, and seal it up as good as possible, occasionally checking that the troll in question is still safely inside, where they are free to pester illusions of other users without harming anyone.
Mind you, it will not be a stable system. It will have its ups and downs, but overall, it should be just fine.
That is, as long as the trolls don't team up before the superusers do, but that can be considered very unlikely, because trolls hardly ever form teams, since that does not exactly come natural to a troll.
So, while not being paradise for everybody, it stands a reasonable chance of being a generally nice and pleasant place.
Which begs the question: Where can i sign up?
[Answer]
As your infinite society progresses, I see two factions becoming very powerful ruling classes. The builders an the controllers.
The builders are a group of people dedicating to building the most amazing structures. Destroy their world sized constructs and they simply rebuild them. They can reforming anything that gets destroyed in an instant, minimizing the destructive habits of their neighbors. To join their group, you must dedicate your immortal life to building and cooperation.
The controllers spend all of their time attempting to control the minds of the new guys. The work tirelessly to ensnare them in sudo universes of their own creation so that the captives do no know that they are trapped in a created universe. No matter how much the captives destroy, the can never escape because they do not know that they are captives. The perception of the greater universe has been stolen from them.
[Answer]
It would be better if every dead person had its own universe and reality shaping abilities but could connect with other people if they consent, like for events when they invite lots of people. This way would be less frustrating.
Private universe should be governed by their own ''god'' which has complete control of it so if they want they can decide to share this control
there should also be a public universe which everyone can enter and do all the mess they want and here everyone is a god .
This way it'be a way more peaceful and enjoyable afterlife but would require stronger machines that can hold all these universes .
when someone dies how do you know their conscious goes directly in the machine of afterlife but instead the machine doesn't simply make a copy of him and leaves the original person dead while the copy believes to be the true one ?
[Answer]
IRL the reason why I cant just wave my hand and make anything appear is because those are the laws of physics in this reality. In order to stay alive I need to breathe so its a law of this reality that I cant survive in a vacuum or underwater. Etc. etc.
Establish the laws of physics, of reality, within your virtual world and you wont have everyone doing just anything and everything.
Maybe there's a limit to things. You can die five times and after that you die for real! That sort of thing.
[Answer]
For many games, you can create your own world that you are in control of, and invite people you wish to play with. A very popular sandbox game with private servers, and a friend system added the ability to upload your mind, as people prefered to be in the game, more then living in reality. While each player is a god of the worlds they create, they must remain civil for fear of losing their friends, and never being able to visit other worlds.
] |
[Question]
[
**This Query is part of the Worldbuilding [Resources Article](https://worldbuilding.stackexchange.com/questions/143606/a-list-of-worldbuilding-resources).**
---
Many languages exist on Earth and many languages will also exist in a detailed fantasy world. The influence of some languages will spread over time while other will only be spoken in a small area. I would like to know what is responsible for this difference and how it can be applied to a fantasy world. For example, Arabic became the dominant language in North Africa and in the Middle East but never managed to surpass the "local" languages in Persia or in the Indian subcontinent.
**What is responsible for the spreading of a language? What would make it fail to propagate into certain places?**
---
Note:
>
> This is part of a series of questions that tries to break down the process of creating a world from initial creation of the landmass through to erosion, weather patterns, biomes and every other related topics. Please restrict answers to this specific topic rather than branching on into other areas as other subjects will be covered by other questions.
>
>
> These questions all assume an earth-like spherical world in orbit in the habitable band.
>
>
>
---
See the other questions in this series here : <http://meta.worldbuilding.stackexchange.com/questions/2594/creating-a-realistic-world-series>
[Answer]
[Lostinfrance's answer](https://worldbuilding.stackexchange.com/a/25399/9685) has some very good point, but I think that the main factor is missing, IMHO.
>
> What is responsible for the spreading of a language?
>
>
>
The main factor is the **movement of human population**.
# Early history
One needs to first understand what is a language: it is a tool used by people to exchange and communicate.
The early history of Human languages is, in that sense, very interesting. For example, one can see the different [language families](https://en.wikipedia.org/wiki/List_of_language_families) that span Europe, and see where they [came from](https://en.wikipedia.org/wiki/Indo-European_languages#Proto-Indo-European). There are still some studies, but the Human migration is shown to be strongly related to the language spread following the lines of
[](https://i.stack.imgur.com/fpe6l.png)
Different [migration waves](https://en.wikipedia.org/wiki/Indo-European_migrations) could be observed in Europe. And each of those can be [connected](https://en.wikipedia.org/wiki/Indo-European_languages#Diversification) to one or more language. To simplify, Western Europe saw several waves amongst which
* Celtic (ca. 500 BC),
* Italic (ca. 50 BC),
* Germanic (ca. 500 AD).
Those populations brought in their languages with them. Now when the place was already inhabited by a sizeable population, those populations will need to communicate. I can imagine that they, at first will form some kind of [pidgin](https://en.wikipedia.org/wiki/Pidgin) (a simplified communication mean steaming from two or more languages), which would later develop into a new/different language.
To illustrate that, English, Dutch, Scandinavian languages and German trace (part of) their origin to the [Saxons](https://en.wikipedia.org/wiki/Saxons).
So if consider the migrations as being the vector of the spread, the main causes are
* "economic" (food/resources),
* politics, e.g. Roman conquests,
* religious? but I never came upon one in Early history.
# More recent history
More recently, there were less large movement of populations in Western Europe.
As a consequence the languages haven't moved so much. The borders were, of course not fixed, but as early as the 9th Century AD, pre-French and pre-German was used in what is now France and Germany. Latin in Italy, etc.
Lostinfrance mentioned war conquests as a strong vector. And it could be. But usually the "elites" would take the language of the conqueror, whereas the rest of the population would not. There are many examples of that:
* Latin was kept to elites in most of the Roman Empire. Exceptions are the influence within countries that are still using latin-based languages nowadays, which, indicently are closed to Italy and to Rome.
* French in England was only spoken by the nobles, and eventually disappeared.
* The Franks were German tribes, but lost their German pretty fast upon conquering what would be France.
* Mongols had a huge Empire, but few local languages were affected by their own language.
* Spain (or part of) was under Arabic rule for 700 years, but Arabic isn't the language used there.
The only example of a real success that I can think of is the Arabic spoken in North-Africa. But even there, after centuries of Arabic language as the official language, there are still in Morocco people who only speak Berber (*albeit* not many).
Nevertheless, all those military conquests have influence over the language spoken in the country. Most illustrous is the strong influence that French had on English: about 29% of English words are [from French origin](https://en.wikipedia.org/wiki/List_of_English_words_of_French_origin), even before direct latin contacts. And actually the influence of both German and English languages are important contributing factors in the separation of French and other latin-based languages.
Another very important point to take into account is that languages are like living creatures. They evolve on their own. Every region of the world get a language that result from the origins of the people that live there, and the languages used by neighbouring countries (due to commercial exchange they need to communicate with each other). Due to that, it is often easy for native speakers to identify the origin of other native speakers:
* Hardly an English speaker would fail to recognise a Scotsman.
* Most of the Spanish-speaking world would spot immediately an Argentinian.
* Someone from Quebec would most of the time be clearly identified in France.
[Answer]
What is responsible for the spreading of a language?
Given the limits of my knowledge, my suggested answers will concentrate on the history of English, but of course these phenomena have happened worldwide.
Some warlike reasons:
* Conquest with the displacement or killing of the previous inhabitants who spoke a different language. E.g. Anglo-Saxon versus the language of the Britons (i.e. the ancestor of modern Welsh), English versus Native American languages.
* Conquest where the conquered people remain in place and continue to speak their old language but they need to learn the conqueror's language to deal with the new government. E.g. Norman French versus Anglo-Saxon.
* People being forced or persuaded with menaces to teach their children the new language. E.g. the [Statutes of Iona](https://en.wikipedia.org/wiki/Statutes_of_Iona) which forced Highland Scottish clan chiefs to send their heirs to lowland Scotland to be educated in English.
Sad to say, the use of *sufficient* force seems a very effective way of propagating a language. An imposed language might fail to take root if the imposition were half-hearted, or if the empire dissolves, or is itself conquered. Russian is in retreat following the demise of the Soviet Union.
I simplify for brevity. Actually, it's rare to have a completely black and white picture of linguistic aggressors and victims. There are numerous complications: for instance after the Spanish conquest of the Incas the Quechua language was [promoted by the Spanish as an administrative language](https://en.wikipedia.org/wiki/Quechuan_languages#History:_origins_and_divergence) at the expense of other local languages.
The reasons above coexist with and merge into more peaceful means of language spread:
* Economic or cultural domination, where the new language is not forced on anyone but is seen as the only route (or, realistically, actually is the only route) to get access to markets, technology, influence in the wider world or "modernity" in general.
* the language serves as a bridging language or lingua franca between people who don't share a language, e.g. [Swahili](https://en.wikipedia.org/wiki/Swahili_language) or the original [Lingua Franca](https://en.wikipedia.org/wiki/Lingua_franca). It might eventually develop into a pidgin or creole, e.g. [Tok Pisin](https://en.wikipedia.org/wiki/Tok_Pisin). Indian English went from being the language of foreign conquerors to a bridging language and is now spoken as a native language by a some Indians. English as a lingua franca is currently benefitting from a [snowball effect.](https://en.wikipedia.org/wiki/Snowball_effect)
* Religion is a huge factor in the rise of languages, whether spread by the sword or peaceful persuasion. E.g. Sanskrit, Latin, Hebrew, Arabic. Whether to [translate the Bible](https://en.wikipedia.org/wiki/Early_Modern_English_Bible_translations) from Latin into vernacular languages such as English or German was a flashpoint during the Reformation. The expansion of a religion can cause the language associated with that religion to supplant minority languages, but religion can also end up preserving minority languages. Many languages were first put down in writing by Christian missionaries so that Bibles could be produced.
* Cultural attractiveness. Under the influence of Chinese literature and culture, Japanese and Korean picked up many loanwords from Chinese despite not being closely related to it. The writing systems of both countries were also heavily influenced by Chinese. The spread of English has been helped by pop music and Hollywood films.
Finally it's worth mentioning one factor that people love to claim is decisive in spreading a language - the intrinsic superiority of (usually) the speaker's own language for government, trade, science, culture or whatever. There is practically zero evidence for this theory. The ups and downs of history provide many examples of languages that at different times have been seen as an instrument of empire and as fit only for peasants. English has filled both roles.
The failure of a language to spread to areas where politics and history would suggest it would dominate might simply be because the local people's existing language is very different in sound or structure. It's too hard to learn the new language.
Nicholas Ostler's book [*Empires of the Word*](http://www.nicholasostler.com/nicholas/books) is a useful source.
[Answer]
**Summary of the answers**
I decided to make a community wiki because all the answers have good points but none covered all the aspects.
---
Languages evolve with distance and time. Different groups will develop different dialect/language if they are far from each other for long enough.
**Movement of human populations** sometimes due to demographic pressure on local resources is the main factor explaining the spreading of languages.
**Conquest** can lead to the assimilation of the local population, the assimilation of the conquerors to the local population or a mix of the two languages creating an hybrid that would be unintelligible for native speakers of the original languages. The conquered population might have been lowered enough for the new language to dominate. Usually, the conquerors rarely manage to impose their language over the local populations. The other two scenarios are much more common. A mixing of the two languages will often occur and the dominance of one language over the other will depend on several factors...
**The states** have a role to play. They can enact laws, forcing the assimilation of minorities of conquered territories. The local languages can be given a special status after the conquest, which will help in preserving it. Political unity helps in maintaining the dominance of a language over the others. For example: Russian is in retreat following the demise of the Soviet Union.
**Non-coercive conversion**: Adopting the language of the elite can be seen as a way to improve the economic or social status. The "dominant" language can be used as a lingua franca inside a country with many different languages. It's not possible to learn all of them and speaking a common language is the easiest way to communicate with the different groups. Choosing the language of the ruling class is common. For example, many ancient French colonies in Africa became francophone over time.
There could be a lingua franca for commerce, scientific publications and interactions between different cultures. Diffusion of this language depends on dominance, prestige, power, privileges. But sometimes this language is only spoken by a minority: aristocrats, scientists, intellectuals; most of the population will keep their native language.
**The spreading of religions** can sometimes be tied with a specific language. Islam and Arabic spread simultaneously in several regions.
[Answer]
**Dominance, power, prestige and privilege are the principle drivers of language adoption.** The movement of human populations plays a critical role in which languages dominate others.
**Dominance, Prestige, Power, Privilege**
In England, there's a difference between how the aristocracy speaks and how everyone else speaks. This difference is known as [Received Pronunciation](https://en.wikipedia.org/wiki/Received_Pronunciation) and it's a common way to distinguish between a prestigious elite and a commoner. A long standing pattern throughout history indicates that the elites will frequently speak a different language or dialect than the commoners. In fact, phrases such as "cease & desist" are artifacts of the need by the legal system to communicate with elites *and* commoners. "Cease" and "desist" mean the same thing.
**Utility of Language**
In addition to the above domination by one language group by another language group, languages can also spread by utility or social preferences. For example, [The lingua franca of scientific communication has varied over time](http://www.researchtrends.com/issue-31-november-2012/the-language-of-future-scientific-communication/). German took over from Latin for scientific communication. In turn, English has taken over from German. During WW1, science papers in German were shunned by scientists in England and the US. Coupled with the downfall of Germany after WW1 and the isolation bred by the Nazis, the rest of the world transitioned away from German to English as the lingua franca of science. This transition along with the world-wide economic domination by the United States post-WW2, lead us to the use of English as the common denominator for international communication.
A far more indepth treatment of the spread of language *and* the scholarship of such spread can be found in "[Language spread and Its Study in the 21st Century](https://ofeliagarciadotorg.files.wordpress.com/2011/02/langauge-spread-and-its-study-in-the-21st-century.pdf)". There are many theories about the reasons for a language's spread or deprecation. Far too many to discuss here.
[Answer]
You can't really distinguish languages from cultures and people, which is what this question really boils down to. How do people and cultures spread and, equally important in terms of linguistic evolution, why do they stop?
The core agent of distributions is survival - people want to survive and they want their children to survive. That means that if the population gets too large for the environment to support them, the environment starts to change dangerously, the neighbours get too rowdy or any one of a thousand other reasons, groups may choose to relocate. Initially most human groups were nomadic hunter-gatherers, so they would need to be relatively thinly spread but also likely to meet up from time to time and probably to communicate at least with neighbouring tribes.
Initial divisions are likely to have a geographical element to them - two groups are divided by geography ( maybe a volcano erupts, a new strait floods, a disease thins out the population and leaves surviving groups in disparate locations ) and continue to grow in parallel. Their languages begin to diverge further until they begin to lose mutual intelligibility. At the same time these separate populations are still spreading ( assuming the conditions are sufficient ) and so their language and ideas are going to change as they need to describe new locations and experiences.
Even in large but widely distributed communities sharing a common language, you are likely to get dialects developing in different areas and at some point these dialects may cease to be mutually understandable ( although someone from the centre may be able to converse with both ) and you have a pair of child languages developing. [This English.se question on dialects](https://english.stackexchange.com/questions/5815/where-do-accents-and-dialects-come-from) has some answers that give more informed views on this area.
As some parts of society become more sedentary the travelling groups may begin to settle in communities with common culture and language, which are likely over time to fall under common governance, becoming something like a nation. Language is now a strong cultural identifier and as nations grow and their relationships with neighbours develop there are new opportunities for cultural domination - which can be military, but could also be artistic, religious, technological or trade based. In places with a lot of travel there are likely to be trade languages which lend many words to the languages they pass through.
Conquest can work in two directions - as a conquering culture is assimilated either their language will be imposed on subject peoples ( hence the latinate languages in Europe ) or the conquerors will be assimilated into the subject language in the way that the English court gradually became anglicised. In both cases there will be words that survive and that propagate between the languages. As this resolves there is a chance of a child language that is constructed from parts of both but is recognisably different from both parents. Social and cultural pressures will drive the language further towards one or the other, but these will be very context specific and hard to describe in general terms.
] |
[Question]
[
**tl;dr: *What adjustments to a "rewind" power allow multiple equally powerful characters?***
## Background
There are many different [models of time travel](http://qntm.org/models). Personally I find it easiest to tell stories using the "fixed history" model, where the past is immutable because it has already happened: time travel can cause or provide information about past events, but it cannot change any aspect of history (see *12 Monkeys* or the time-turner from *HP*).
However, it has consistently come up in feedback that people have two problems with this model.
1. They do not understand it. ("You can't change anything." "Yeah, but what what if you did *this*...")
2. They feel that it is too restrictive. ("What's the point if you can't change anything?")
So I've decided to write my next story with a model that allows the past to be changed.
## One-person Model
The model I have in mind is based on a "rewind" mechanic. This has been used successfully before: see, for example, [*Next*](http://en.wikipedia.org/wiki/Next_(2007_film))1 or [*Life is Strange*](http://en.wikipedia.org/wiki/Life_Is_Strange).
In this model, the main character has the ability to rewind time, usually by a limited amount. This power manifests itself to the outside world as precognition.
My internal model of how this works is something like a [git](http://git-scm.com/) repo.
* The state of the universe is continuously stored as time progresses forward.
* At some point, the main character chooses to jump backward to an earlier moment. This can be handled in two ways:
+ The character somehow chooses a specific moment, and jumps immediately to that point.
+ Upon triggering their power, the character experiences time in reverse (at normal or accelerated speed). They cannot change anything at this point, only choose how far they go back.
* The entire universe undergoes a rollback and is returned to its previous state, with one exception:
+ The main character's current mental state is copied into their past body, so that they retain the knowledge they gained in their (current) future.
+ Unlike *Life is Strange*, you cannot hold onto anything that you pick up, and you resume in the location you were at the time you return to.
* Time progresses forward normally again.
There are a few things that I like about this model:
* There is a cost to the rewind. If you rewind one minute sixty times, you'll have wasted an hour of your time: which could be boring at best or mentally exhausting at worst. It probably has a poor effect on your sleep cycle/circadian rhythm as well.
* Making money is nontrivial. If your rewind limit is two minutes (as in *Next*) you cannot cheat the lottery, which usually must be purchased fifteen minutes or more before the numbers or drawn (I assume a similar rules exist for horse racing and the like). You can't cheat games where the randomness comes after your bet, like craps, roulette, and slot machines (although you can increase your odds by playing multiple times, with the aforementioned time cost). You *can* cheat games where the randomness happens before your bet, like blackjack and poker; but they are not high-payout games, and a string of wins looks suspicious.
* An outside observer sees no discontinuities. You don't blink out or teleport. The only indication that something has happened is that you are disoriented briefly while your brain readjusts to the sudden change in sensory input. (Although maybe for jumps which "push the limit" concussion-like effects, coma, seizure, etc. may be possible.)
* You can do lots of impressive things in the short-term (like [dodge bullets](https://youtu.be/RC5ZiK6o7uQ?t=34s)), but can't preexamine the long-term effects of your actions; so most storytelling devices still apply.
However, I don't like the part in the 'rules' that states "main character." The idea that this mechanism is specific to one particular individual is unattractive to me.
## Extending the Model
[*Braid*](http://en.wikipedia.org/wiki/Braid_(video_game)) introduces a new feature into the mix: some people in the universe are not affected by your power. In terms of the model above, their mental state is also coped into the past.2 I don't want to use this exact behavior for two reasons:
1. The rewind ability is still asymmetric, since the rewind still falls under sole control of the main character.
2. Anybody with this 'persistence' property would experience a rewind whenever you initiated one, even if they were on the other side of the planet and never met the 'rewinder.' This would be highly annoying at least!
This is the crux of my question: **how can I modify the rules to allow a second character with the rewind power?**
Here are my requirements:
1. All empowered characters must obey the same set of rules regarding the rewind power.
2. Characters must be able to tell when another is using the rewind power against them and counter somehow. (*"Going around again? Nice try, but you can't use that trick on me!"*)
3. However, characters must not be forced to relive a moment more than once if they choose not to exercise their power. (Bonus points: two characters can remain unaware of each other's nature or even existence until they interact.)
4. Unpowered outside observers must not observe any glitches. If you use a branching-timeline model this includes observers in all timelines.
5. If you use a branching-timeline model, at the end of any series of rewinds by both parties there must be only one timeline remaining.
* For example: interpreting the original model as a branching-timeline one, another timeline branches off the current on every rewind. All the "stub" timelines end when the main character chooses to jump. Time only continues forward in the new branch.
6. A hard time limit on rewinds is **not** required.
1 From my understanding, Cage is supposed to be *seeing* the future, not *experiencing and rewinding* it; but the story plays the same either way and matches what I'm thinking.
2 The actual game mechanic is that they continue to propagate forward in time as you rewind. This works great for the game, but doesn't make physical sense in the real world.
[Answer]
>
> 2. Characters must be able to tell when another is using the rewind power against them and counter somehow. ("Going around again? Nice try, but you can't use that trick on me!")
> 3. However, characters must not be forced to relive a moment more than once if they choose not to exercise their power. (Bonus points: two characters can remain unaware of each other's nature or even existence until they interact.)
>
>
>
I think the best way to accomplish goals two and three together is to have passive rewinders only aware of the future on a subconscious level:
**Those with the ability who are brought along during someone elses rewind can only notice on a conscious level when they see a divergence with their own eyes**.
Simply put, if you have the power and a rewinder brings you back in time, you can't tell. That is, until you witness a divergence in the timeline, at this point the rewinder will see a person or object split, a ghostly form carrying on with their original behaviour, while the corporeal version doing their new behaviour. Upon witnessing this, the rewinder will then know that someone else is using their ability to alter the past in a way which will effect them.
This way, it's very difficult for those with powers to fight each other, as if you were about to lose and rewind, your opponent will see the ghostly version of himself beat you and do the same thing.
Advanced rewinders could also use this as an advantage against newer rewinders by continually rewinding the last minute and filling the room with ghost fighters as a distraction.
However, this doesn't completely make rewinders immune to each other, as a seriously clever puppet master type could theoretically defeat another rewinder if they can come up with a convoluted plot which changes the past of the rewinder without directly effecting anyone that the rewinder *sees* (e.g. the puppetmaster messes with the phone lines at the local exchange so when the rewinder gets called in the morning, the lines switch with a sex chat line, which distracts the rewinder enough to make him late enough that he doesn't have time to foil the puppetmaster's plans, nor will he have a chance to run into his ghost future self who did foil the plot).
[Answer]
As far as I can see, your model is flexible enough to allow for this already. Since you're employing the use of a fairly large amount of handwavium, you can simply employ some more and just *say* that more than one person with this power is possible. There are a few major ways I can think of about how it would affect other rewinders:
* **Only the rewinder performing the rewind is copied.** So, only the person who rewound time remembers that they did it; nobody else, including other rewinders, notices any change.
The problem with this is that it doesn't fit fit one of the rules you mentioned: that other rewinders must be able to detect a rewind.
* **All rewinders are copied.** Whenever a rewind happens, all rewinders have their mental state copied back with them. This enables detection of a rewind but not prevention.
* **All rewinders must agree.** Whenever someone tries to rewind time, every other rewinder must allow it before it happens. Perhaps this is mentally controlled: their brain is set up to automatically allow rewinds, but they are capable of stoping a rewind if they really want to.
This method can be combined with number 2 to enable detection and prevention.
I think number three is the most viable option here.
As a bonus point, rewinding could leave signals. Whenever someone rewinds, their aura or rewindium cloud or whatever changes. A bit like someone releases a lot of rewindium dust into the air in the location of the rewind. The dust decays after a while, but the rewinder would be detectable by other rewinders who can sense the dust.
[Answer]
I like ArtOfCode's answer but wanted to add one more touch:
When a rewinder uses their power they start going back in time. As they do so a "bubble" spreads out from them at the speed of sound (this will take several hours to cross the entire planet). I picked the speed of sound just because that's how long it will take most of the changes you make to ripple out. Speed of light is another obvious candidate but would be too fast. Just picking an arbitrary speed would also work but it feels better if there is some significance to the speed.
As the bubble reaches any rewinder they get pulled into the rewind, they can either actively help it, allow it or resist it at that point.
This means that small and localised rewinds, for example going back a few seconds, are normally hard to stop. As you go back further and further in time though you need more and more rewinders to either allow it or help push it through since the bubble grows larger and larger including more and more of them.
Two rewinders in hand to hand combat would not be able to use the power much at all, two in a gunfight may be able to rewind a fraction of a second here or there.
[Answer]
I think that your analogy of a git repository is quite handy for settling what would happen. Version control systems are designed for multiple users. The version of events that sticks depends on a *last* mover advantage.
Say we have two combatants, Tom and Ann. Let's consider their first meeting. Neither knows that the other is unstuck in time. Ann makes the first move, she attacks Tom as she would anyone. Tom zips back in time to anticipate Ann's attack. Ann notices Tom come unfocused just before she had planned to attack.She then knows that Tom possesses the ability to shift back, and can spring back herself far enough to be out of sight of Tom. From there she can adjust her strategy to take Tom out before he even knew there was about to be a fight.
Now, suppose that both combatants are already aware of each other. All other things equal, the fight turns into an exhausting game of nim. Whether the jumps are hard limited or limited by stamina, the outcome is the same. Both Ann and Tom would be running through cycles of attack-observe-rewind as quickly as possible, in an attempt to place their opponent in a position of no escape. Each would also be attempting to wind back farther than the other, to wipe out their gained knowledge. Eventually, either one combatant passes out from too many loops and lack of sleep, or they manage to land a knockout blow before the other can react. In the case of a faint, the winner would be fresh as a daisy, having basically done nothing to defeat their foe, and in the case of a perfect strike, the winner would be terribly mentally drained.
This ties things together nicely, without the need for complicated energy waves or other distracting fluff, and it operates on a single, continuous timeline. The only rule needed is that no two travelers can shift back exactly simultaneously.
[Answer]
How about that:
When someone rewinds time, minds of all other time-benders are attempted to be copied into their past bodies too, but there is a choice of which version of mind to use.
By default human subconscious declines the copy attempt and keeps using the old mind. On any time rewind all time-benders just get some weird feeling - like deja vu, maybe. Some of them, probably, know that it means time rewind, and some don't even know that.
But if a future mind shows strong negative emotions, like it is in a danger - then the subconscious accepts the changes, so the time-bender is aware of the rewinded timeline.
It makes more sense if time-bending is evolutionary, people with this trait are very likely to avoid life-threatening situations, but they do not waste their mental resources on numerous rewinds of all others.
What it gives:
- Characters are able to tell when another is using the rewind power, but usually can just ignore it.
- If before the rewind they knew they are confronted - enemy's rewind lets them know exactly what would happen.
- They are likely to be unaware of each other's power; they can even be unaware of their own power. But if confronted, they not only get to know it, but they know it in advance.
- If you would need some stronger time-benders, you can give them more control of a process. Like, some meditation or medication, which allows to always accept a new mind (exhausting, but probably a good choice for a desperate villain), or even to make a conscious choice between the old and the new minds (but probably it should take some time).
Drawbacks:
- Obviously, if some time-bender is scared, when, accidentally, someone on the other side of earth rewinds the time, he would be forced to relieve that rewind. On the other hand, he have just effortlessly gained some knowledge about the future danger, so probably he won't mind it too much?
Also, it probably is the only way to find out that you're a time-bender.
- You could mess with any untrained time-bender as much as you'd like as long as he thinks he's safe.
[Answer]
One way to do this is by saying when a rewinder is using their power, they create a bubble of control that is only detectable by other rewinders, and is responsible for the persistence effect. Everything inside and outside the bubble is turned back, but if another rewinder is close enough to be inside the bubble they are aware of it happening and the persistence effect includes them.
This way, if I'm a rewinder and another on the other side off the planet rewinds time I'd never know as I'd be outside of the bubble and would be rewound along with everyone else, but if someone near by was trying to mess with me I'd know what was happening and be able to counter it, maybe stop the rewind from happening.
A different method is to say that as a rewinder if time is rewound by anyone anywhere I'd keep my memories of the other timeline. That would let me know if there were others using their power, and if my timeline was under attack. This can be paired with the control bubble to good effect.
[Answer]
I've thought long and hard about this question, and its requirements. I want to lead off with a couple of observations I've made.
As far as the branching-timelines needing to end; this is really a non-requirement. The story will be told from the vantage point of a given person or group of persons. Prior to any interaction between two rewinders, there will have been a near infinite number of divergent timelines created by rewinders around the world, doing things as simple as un-dropping a contact lens. Since the entirety of the universe is rewound, leaving nothing changed otherwise, there is no reason for any special treatment - we need only be able to observe the interactions involving the people in the story, all of whom exist in every timeline where they didn't die yet. Sure, this leaves a complicated multiverse, but no one exists that can actually see across the boundaries - so it doesn't matter. What's more, if you change your mind later, you can write in someone who can pass through the boundaries. Less is more, here.
As far as outside observers not being able to notice, you've essentially already written this mechanism as well as you need to. If you actually make the rewinder experience the rewind in real time or some (maybe selectable) multiple of real time, preventing them from manipulating anything during the rewind, there's nothing to notice. An adept rewinder could get skilled at watching his environment during the rewind and more or less seamlessly reenter the "new" situation.
Now we need to tackle the requirements that really don't mesh well; it is desirable that no one can be forced to relive a situation, but we'd like for the rewinders to know or reasonably suspect when they've been rewound, and be able to do something about it. For them not to relive a situation, they must not perceive the situation recurring, but to detect a rewind, there has to be something that is perceptible to them. But everything has to rewind, and everyone has to follow the same rules.
As such, I propose the following;
1. Rewinders experience a profound sense of deja vu when in the
vicinity of another rewinder.
2. This feeling waxes and wanes based on proximity.
3. Physical contact with another rewinder provides a sense of sureness
that this other person is a rewinder.
4. Any two rewinders activated in the same timeline cancel each other
out.
5. As a logical consequence of (4), all rewinders are familiar with
lurching to a halt mid-rewind and generally consider it a loss of
focus on their part.
6. The cancellation halt is somewhat disorienting, and at your option
somewhat painful.
Using these mechanisms in plot, it is now possible for a scooby gang of friendlies to find each other out, and gives the resident big bad a method of hunting down the people who keep interrupting his attempts to return to childhood with his newfound power and knowledge - perhaps something he has done several times without pain until Our Hero discovered his abilities, which disrupt his.
As far as handling the timeline during a cancellation event, lets work on an example. Allen and Barry are rewinders on opposite sides of the world. Lets say our story primarily involves the life of Allen, and how Barry deals with Allen. Allen starts a rewind at 1:47 pm that halts unexpectedly at 1:43 pm, the exact moment that Barry had started to go back a year or so. Allowing branch timelines means some things have happened here. In one, Barry never lurched - he went on back happy as a clam, but we don't care about that one, or the Allen in that particular timeline. We watch the one where Allen goes about trying again so he can try a different pickup line on that girl, and hopefully undo that part where he lurched and fell on his face.
Note that the only thing that matters is when Allen rewinds across the start of another rewind - in his timeline, when he starts, there may or may not be any other rewinds in progress. If there are, he'll misfire, to his surprise. When he does, he'll try again - and maybe, misfire again. It will be like two people calling each other and getting a busy signal - eventually, Allen's rewind will start first and he'll be able to continue back in his frame of reference, until he crosses the start of someone else rewinding, which could be days in his timeline.
Now let's put Allen and Barry in the same room, and make one try to kill the other. Barry shoots Allen in the chest - Allen rewinds to make his way back out the door he came in and manages to rewind himself all the way to the point where (he thinks) Barry became an adversary. Things move on for Allen until Barry becomes aware again and makes another attempt, only this time Barry intentionally did six two-second rewinds right before the attempt on Allen's life. Timelines are thrown left and right, but Allen is the only one we care about, and Barry would continue in both timelines created, and each time there would be a rewind event to cancel. Following Allen-prime's frame of reference, he gets shot and attempts to rewind, lurching both of them still in the same room and cancelling that rewind. Allen runs for his life, and in a panic tries to rewind - he gets to relive the run for his life, the moment of the cancellation, and then he gets to the next to last rewind Barry did before he rounded the corner. They both lurch, but now, Allen-prime has been shot and has lurched twice, but Barry has only lurched once, still fully intends to kill Allen, and has a full clip.
] |
[Question]
[
I'm aware that deep sea fish don't actually "explode" when brought to the surface but any air sacs in their bodies would expand and cause them possibly fatal damage.
However, what other physiological problems might occur in a creature that had evolved in an environment of extremely high pressure when moved to a low pressure environment?
I'm trying to think of what "survival gear" would be required for a being used to living in pressures in the hundreds of MPa range to be kept alive at the Earth's surface.
[Answer]
Many of the effects will be similar to what humans encounter when exposed to very low pressures. Here are a few:
### It will be harder to breathe
Gas exchange across things like lungs or gills is dependent on the partial pressure of oxygen on those surfaces. In a low pressure environment, any creature that relies on breathing oxygen will be exposed to hypoxia, which could be fatal. This can be survived to some extent through acclimatization, but no humans have lived for extensive periods of time at more than about half of this.
To survive this change, a creature would need to be given either a higher concentration of oxygen or else a pressurized air supply. For long term habitation in an otherwise breathable atmosphere, this could consist of an air compressor. Since the lungs would burst if their pressure was hundreds of times the external air pressure, this would also require a pressurized suit, like what astronauts wear.
Low partial pressure of oxygen is the main issue that mountaineers face, but they only face a pressure around 1/3 of normal air pressure. For lower pressures, other issues will come into play.
### Some substances will change phase
This is something that astronauts encounter when going into space. Blood and other fluids in the human body begin to boil at low pressures. For an organism evolved to survive at hundreds of MPa, the body may contain fluids which are only fluid under high pressures. Likewise, some solid structures may become liquid at low pressures.
Astronauts face this problem when they go into space. It requires a pressurized suit to be survivable, since your body can't operate with gas for blood.
[Answer]
First, check out [this article](http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2104549/) describing how deep-sea fish can be conditioned to live at atmospheric pressure. The depths they talk about are in the tens of MPa (hundreds of atmospheres) range. Basically they find that slowly lowering the environmental pressure allows the fish to survive.
This is similar to the case of scuba divers. If they ascend quickly the expanding gasses in their body can be fatal, but ascending slowly gives the gas enough time to escape the body.
According to [wikipedia](http://en.wikipedia.org/wiki/Pressure_vessel#Stress_in_thin-walled_pressure_vessels), A spherical tank to hold 100 MPa of pressure made of, say, a composite material with an ultimate tensile strength of a few GPa would have a radius around 50 times its thickness, not unreasonable. So it would probably be possible for high-pressure beings to undergo a long period of decompression in such a tank, eventually being able to survive at near-atmospheric pressures in a sort of space suit (or even without the suit if they can survive with just 1 atmosphere pressure).
The one problem with a space suit is that any significant pressure tends to inflate the suit like a balloon, making it difficult to move. Even in zero gravity, astronauts tend to be exhausted by spacewalks just from having to bend the joints in their suits.
Note however that things like temperature and oxygen levels are less adjustable. The partial pressure of oxygen is the total pressure times the fraction of the atmosphere that is oxygen. Normal partial pressure is 21 kPa, below a certain value you will suffocate (limit is somewhere around value for the peak of Mont Everest ([43 mmHg](https://en.wikipedia.org/wiki/Hypoxemia), or 5,7 kPa) - people can climb there without oxygen bottles, but it is hard and they cannot stay there), and above around 30 kPa the oxygen actually [becomes toxic](http://en.wikipedia.org/wiki/Oxygen_toxicity) (slowly, diver can still spend 45 min at 160 kPa). Your beings would probably need to breathe a special mix of gasses, like how astronauts breathe a low-pressure, high-oxygen mixture in their space suits.
[Answer]
When we humans go to high altitudes we bring extra oxygen to get enough of it in each breath. For deep sea diving we need to bring special air with lower percentages of oxygen and nitrogen so we don't get too much and get poisoned.
At hundreds of MPa, the chemicals we know in their gas form, can exist as liquids or as solutes in strong liquid solution. Carbon dioxide, for example, would not form bubbles.
What survival gear is needed depends on the concentration of these chemicals.
I suggest a creature that lives deep in an ocean where there is about the same concentration of oxygen as at the Earth's surface, but a much higher concentration of carbon dioxide. The creature would want to wear a wetsuit so its skin doesn't dry out and some sort of irrigator to pour oxygen-rich seawater on its gills.
Also, because it is used to a high concentration of carbon dioxide, its blood usually has so much of it that at 100 kPa it would fizz like a shaken Coke. To survive at Earth's surface the creature wears an injector that pumps an acid into its bloodstream to compensate for the carbonic acid that is rapidly lost through the gills at the low pressure. Without the injector, the creature's blood pH would rise and uncontrollably speed up its metabolism. Its muscles would then anaerobically produce carbon dioxide so fast that the creature would get the bends and die violently.
[Answer]
One thing to think about is what happens to humans. When we go on top of a mountain we have a much harder time breathing (at least until we get acclimated to it.
On the other hand when we go down into the deep and come back up we have to take precautions because of 'the bends'. I think different air mixes help alleviate this situation but for a long time people had to stay in a pressure tank and be slowly acclimated back to normal pressure the length of time depended on the how long they were down and how deep they went.
[The bends](http://en.wikipedia.org/wiki/Decompression_sickness) for those that don't know is dissolved gasses turn to bubbles in the blood when decompressed to fast causing all sorts of pain and possibly death. These kinds of things would be the most troublesome. Throwing a body out of the space station door wouldn't make it explode, at least not from the difference in pressure, maybe freezing inconsistently might make it look like that.
If the difference was enough, it might be like needing an Oxygen mask at the top of Everest, so that the being could get what it needed, maybe even a pressure mask if the pressure was important in the absorption process.
[Answer]
I recall hearing of abyssal life that they rely on the pressure to shape enzymes correctly, fold proteins, etc. In general, organic chemistry *changes*.
[Answer]
Since this question has been successfully answered, I will only present links for detailed study on the matter:
<https://en.wikipedia.org/wiki/Decompression_sickness>
<http://www.nature.com/scitable/blog/saltwater-science/do_whales_suffer_from_decompression>
<http://www.whoi.edu/oceanus/feature/even-sperm-whales-get-the-bends>
] |
[Question]
[
**Closed**. This question needs to be more [focused](/help/closed-questions). It is not currently accepting answers.
---
**Want to improve this question?** Update the question so it focuses on one problem only by [editing this post](/posts/109572/edit).
Closed 5 years ago.
[Improve this question](/posts/109572/edit)
I want to figure out what kind of effects following physical attributes and in-universe conditions would have on Orc populations, society and warfare in a realistic low-fantasy setting:
Physical attributes:
* Height ~190-200cm for males
* Weight ~150kg for males
* Roughly twice stronger than an average human
* Sexual dimorphism is simmilar to humans(although a female Orc can still overpower an average male Human)
* Senses(sight/smell/hearing etc) are more or less equal to Human or slightly superior(easily countered by watch dogs).
Conditions:
* They used to populate the fertile central plains of in-universe notEurope and local Donau valley but were gradually driven away, exterminated or enslaved by humans during the past millenia(not long enough for tribal mythos to forget the fact). Those lands now a part of the notRoman Empire.
* Tribal/Clan societies ranging from hunter-gatherers to non-sophisticated agricultures. Most populations inhabit fantasy counterparts of Alps(like Picts), Northern Europe(Saxons), less fertile plains of Eastern Europe(southern regions are dominated by the cavalry-heavy human nomads).
* On the overall the world is around our Earth's Antiquity(300BC-100AD), Orcish societies can produce little iron and steel products compared to neighboring Human civilization but it's mostly because of population sizes and overal development rather than mental inability(fastforward a thousand years - Orcish civilizations cut the gap in technological progress and even dominate in certain areas).
* Story-wise there are two periods: one is an analogue of our classical Antiquity(think Alexander the Great/Ceasar in Gaul), the other is an analogue of Migration Period/Viking Age caused by the Little Ice Age.
**1. What would be the average food requirement for these Orcs?**
Sub questions would be: a) what would be an average population density in low to mid fertility regions? Gallo-Germanic plains and Donau valley had an average of ~8 people per km2 during antiquity - I'd assume that because of higher food requirements there'd be even less Orcs to go around.
b) in-universe these Orcs make the best gladiators, but would they be good as slaves for physically intensive labour? Would it be worth fielding Orcs over regular Humans or the strength vs food costs would favor more of latter?
**2. Would physical attributes affect society structures compared to humans?**
a) How fertility and maturity rates would be affected and thus affect society? I'd assume that lower population levels on their own do not allow for higher social structures.
b) Violent resolution of internal conflicts seems to be undesirable because at such strength levels wounds are going to be more severe, lower populations and higher dependancy on healthy individuals push it even more.
c) How physical superiorty would translate on the Orcs' worldview(including mythos and religion) and their attitude(diplomacy?) towards other intelegent species?
**3. How the above ultimately affects warfare?**
As was mentioned Orcs make for great gladiators in melee combat because of their physical characteristics, but would that translate to their free kin? Or they'd be more oriented towards skirmishing assuming much lower numbers compared to other fantasy species?
Primary enemy(neighbour) is the human notRoman Empire that makes extensive use of noble heavy cavalry(think medieval knights and their men-at-arms), professional heavy infantry(extra troops outfited and paid for by the nobles) and with local levies as expendable frontline.
Also what about the second time period, when literally whole tribes/clans would have to migrate and fight for their very survival?
One in-universe condition is that Orcs don't have cavalry: neither equestrian nor chariots. The Humans' ability to ride the horses and greater numbers is the primal reason why Orcs were pushed from their homelands in the first place.
Note: the magic in the setting is very obscure and indirect like "12 Imperial Mages chanted for three days straight using the rarest ingridients gathered from all the corners of the Empire to cause the storm that scattered Hannibexes' fleet", "Lakonian Warlock knows things he has no access to, like what the Emperor had for breakfast and such.." or "Avernii shamans that can bring people from the brink of death!"
Edit: The questions might look like three separate entities but I want you to view them as intertwined and based around the fundamental limitation that such great physical attributes(typical for modern fantasy) would entail - higher calorie/dietary requirements over other humanoid species. Bigger is not always better, I believe it's the reason why Megafauna died out in our world - smaller and more cost effective species spred faster and took all the ecological niches once the resources became more scarce.
The setting takes inspiration from that process: Orcs took the most fertile and climate friendly regions by the virtue of strength in pre-history, then got pushed back once the technological progress kicked in - Humans exploded in numbers due to agriculture and cavalry sealed the gap in strength.
[Answer]
Humans are built for endurance, this is what makes them "weak" in comparison to for example a chimpanzee or human-sized monkeys/apes (don't kill me for not knowing which one to use).
If you change the strength of the Orcs to be stronger than humans then it would mean that Orcs would spend more time resting (not necessarily sleeping) and combat would need to be quick, brutal and fast because any lengthy engagement would exhaust the Orcs too much. It would actually be a good reason for the Orcs to be warlike: By capturing and enslaving especially humans they can make them do the more exhausting endurance work like the heavier parts of farming.
A consequence is that the Orcs would need to have a different war "timetable". Humans can plan an offensive that lasts hours, Orcs would need a shorter plan and have to cycle their units in and out of combat much more often to keep their troops fresh and stronger than their opponents. Humans would try to keep the maneuvering phase going as long as possible to exhaust the Orcs as much as possible before the initial fight (they are all wearing armor and heavy weapons after all), and when the engagement begins the humans will try to keep the Orcs from disengaging after the initial brutal losses the human's sustain from the superior orcs, as the tables will quickly turn towards the human's favor and the Orcs will start dying.
Edit: in case the orcs are the slaves/workers, their work needs to be tailored to them. For example they could work as dockworkers who unload heavy stuff, then get long rests in-between. Some construction work where they need the manpower for a moment, that kind of thing.
[Answer]
**Your orcs can be a human subspecies, or even a human ethnic group.**
<https://www.worlddata.info/average-bodyheight.php>
Your parameters are well within the range for humans. Average weight is 150 kg which is about double the average weight of a Frenchman and 30% more than a Samoan. A Samoan is double the average size of a Laotian and I suspect that average strength tracks with size.
I could imagine that these large, robust and durable humans were imported as slave labor in ancient times. In fact you propose exactly this. Descendant populations persist, appearing in many ways similar to their ancestors. Such a thing has been known to happen in the real world.
The good thing about this is that you don't have to make up anything. "Orcs" are a human race, or a (crossfertile) Neanderthal-like Homo subspecies at most distant. They eat what we eat. Their society is not completely alien.
[Answer]
## Caloric Needs
According to [CalorieKing](http://www.calorieking.com/interactive-tools/how-many-calories-should-you-eat/) for a 6 foot 2 inch, 330 pound male orc, aged 20 years and doing heavy labor you'd need about 4,000 to 4,200 calories per day to maintain weight (3,200 to 3,400). For comparison to an average human at between 2,000 to 2,500, the food need is between 1.5x to 2x.
That calorie need can be cut to 3,400 to 3,600 calories (and when I say calories, I'm meaning kilocalories) per day by cutting their lifestyle from heavy labor (my base assumption) to light labor.
1.a.) Generally, it's believed that about 4 acres of land was needed to produce enough crop for 1 person for the year. Given that, I'd say orcs would require an average of 7 acres per person or 6 people per square kilometer, using your metric.
1.b.) I think the problem with stronger slaves is more about securing a population of slaves that is twice as strong as the guards, not calories.
## Culture
2.a.) The population difference isn't so severe as to completely rule out larger social forms.
2.b.) The population could still resolve conflicts through ritualized violence: wrestling matches, counting coup, or pre-Shaka African "wars" which were mostly two armies exchanging largely useless spear volleys and going home.
Alternatively, the scottish (and some medieval brits) used feats of strength or skill (caber tossing, hammer throwing, olympics) to compete.
2.c.) Larger creatures (see the Rakshasas of Hindu myth or Goliath) tended to be portrayed as more reliant on the own capability (more atheist).
This is encountered by real-world examples of the Norse and the Dinka, who are both as religious as any other culture. I'm inclined to say size has no effect.
## Military
3.) Your stronger orcs will be able to, if they choose to, wear nearly twice as much armor. That might be enough to become fairly immune to arrows and even stand up nicely to notRoman piercing swords, spears from charioteers, and cavalry charges.
If your orcs adopt the shield wall tactics of their notRoman southern neighbors, it might be able to hold against traditional wall-breakers : cavalry and chariots. A heavy warhorse (Shire) weighs up to 2,200 pounds. Not impossible for a small (2 to 3) group of your strong 330 pound strong orcs (assuming they can lift twice their weight) to throw down.
Now in Gallic lands, your orcs are well positioned to adopt chain maille from the Gauls before the notRomans do. In between these two groups of innovators, if orcs are paying attention, they may adopt the best of both cultures ahead of the humans.
Also, the larger strength and bigger size would allow orcs to draw heavier bows, pull farther, allowing them to have superior range and hitting ability as archers.
] |
[Question]
[
What planetary parameters such as plate tectonics and volcanism etc would best encourage the most uneven planetary surface on an earth like planet?
I want a world to be covered in very uneven terrain, the more precipitous the better over 90% of its surface whilst still providing a good place for humans to live or at least without it becoming uninhabitable for humans. How might this realistically come about?
The world must be approximately earth-like, but planetary parameters can be changed within these bounds if it helps.
The planet may have seas but these should be broken up and dispersed and covered with mountainous islands.
The best answer will have the most uneven terrain over the greatest proportion of the planet.
[Answer]
Continental plates are the way to go... On Earth we have a bunch of small plates, and 7 big ones. As they spin and bump against each other, mountains are pushed up as the edge of one plate slides under another. The mightiest mountains we know -- the Himalayas -- are caused by India smashing into Asia.
So...
You need **smaller continental plates**, so that collision-born mountains will be more prevalent and you don't get all those tedious *steppes* and *praries* that you find in large continental interiors.
Per this interesting article (<https://www.huffingtonpost.com/2014/04/07/earth-tectonic-plates-new-model_n_5104087.html>) plates were caused by low-pressure areas underneath big plates, which caused ruptures. We need more of that. Perhaps kick up the core temp and magma flux a *little* bit, enough to create more fracture points, and voila! More plates.
The extra action will cause more volcanoes etc, but you're the boss of this planet and you can mitigate the problem. Perhaps sulfur-eating organisms remove extra minerals from the atmosphere. Perhaps people/animals just sigh and deal with it.
Now I can't guarantee **no** large continental areas, but we can cheat. Push the big ones up to the poles where they'll be useless. And then the rest of the planet can be small craggy continents and archipelagos.
Enjoy!
>
> Update: This world will have more earthquakes on average than our world. I expect the local people to be a little fatalistic about this, in a "Man proposes, God disposes" sort of way. They'll probably steal a page from the Incas, who were **extraordinarily good** at making earthquake-resistant structures. See here: <https://www.ancient.eu/Inca_Architecture/> . Thanks to Michael K for drawing my attention to this!
>
>
>
[Answer]
**Habitability is a very variable equation**
so first to answer your question, probably a volcanically active planet like IO whose core is constantly squashed by the other moons and Jupiter. That would keep the crust from solidifying too much.
After that we need to create conditions where water is liquid and the atmosphere is breathable (for human habitability).
**Then the question becomes what to do with that heat and volcanic atmosphere.**
Like IO, put it far out in the solar system so the surface can cool faster. So the equation becomes a balance of supplementing solar heat for volcanic such that the average temperature supports liquid water.
**And the atmosphere**
Being a volcanic world the atmosphere wouldn't be good for photosynthetic organisms. However, plenty of terrestrial organisms are capable of making energy from volcanic environments. All humans need to survive is Air, food, and water. This is the crazy part. What if we would genetically engineer an algae capable of producing oxygen from volcanic energy. What if we could then reengineer our crops to produce edible foods from volcanic energy.
The final variable for human habitability is having a crust stable enough to produce long-term structures. This is largely an engineering problem however they would have to identify plates and build settlements towards the center as the edges would be too chaotic. These edge areas would probably be ideal for agricultural areas though as they would have more farmable energy.
This wouldn't be a lovely place for humans(as we know them) with the ash requiring masks but we could irk out an existence. With some self genetic engineering we could be adapted to thrive though.
This answer does rely a bit on the magic of genetic engineering but realistically, that's the answer to any real terraforming attempt.
**Note:** the engineered algae isn't too farfetched, algae was among the first organisms to survive the harsh early volcanic Earth so much so that it eventually changed the atmosphere. The only challenge here is making an algae capable of making oxygen from volcanic energy instead of sunlight. This would also be a great way to extract the harmful gases from the atmosphere as food sources for your air makers. Like our own ecosystem its likely you would need a spectrum of organisms to cleanse different toxins.
[Answer]
You may want low gravity so that your planet will have higher mountains and steeper ridges.
To avoid excessive erosion you may want also a thinner atmosphere.
Keep things "interesting" periodically going through a large meteor shower beautifying your world with brand new craters.
Thinner atmosphere would minimize "meteoric winter" effects.
You can even have a "no axial tilt" planet with a "cold season" right after the meteor shower.
Of course planet must be relatively young, otherwise it would already have weeded out the meteor swarm, unless there's a constant supply.
[Answer]
A highly active hot planet with a very high proportion of light elements and their associated minerals. Basically the world is covered in a thick layer of what on earth is continental rock but coming up through this thick crust you have hot-spot volcanoes everywhere. No oceans *per se* but deep cold lakes between volcanic ridges and richly soiled steep mountainsides that can be terraced and farmed between the eruptions and landslides.
On the nasty side of life the air will be a little acidic and a little toxic due to excessive sulfur and associated compounds and you'll never know ahead of testing it whether that lovely clear lake is H2O or H2SO4. It rains acid on occasion and there's not much in the way of flat land that you don't make for yourself either, but it's livable.
[Answer]
**Lower the viscosity of the mantle** - that will do it one fell swoop. As @akaioi has elegantly answered, you need lots more continental plates, and you want them moving around a lot. It may cause quite a bit of vulcanism - but hey that's cool, right? You've got loads of extremophilic flora and fauna..
] |
[Question]
[
Spaceships are a peculiar thing. We've got them in all forms, sizes & colours. They are everywhere and go everywhere else. carrying with them anything from [music](https://en.wikipedia.org/wiki/Voyager_Golden_Record), over [tractors](https://en.wikipedia.org/wiki/Agricultural_machinery), to [foodstuffs](https://en.wikipedia.org/wiki/Soylent_Green) and [frozen babies](https://en.wikipedia.org/wiki/Cryonics)... but space is vast and ~~empty~~ actually filled to the brim with all sorts of [fancy](https://en.wikipedia.org/wiki/Solar_particle_event) [exotic](https://en.wikipedia.org/wiki/Cosmic_ray) [radiation](https://en.wikipedia.org/wiki/Van_Allen_radiation_belt).
Assuming we have mastered the challenges of creating *nigh unlimited* amounts of energy in a stable manner, as well as having figured out (smart) solutions to any other hindrance:
**Q**: What current-day or [near-future](http://tvtropes.org/pmwiki/pmwiki.php/Main/TwentyMinutesIntoTheFuture) (potential) materials/technologies can be used to shield our ships from radiation *other than wraping them into [meter-thick layers of lead](https://en.wikipedia.org/wiki/Lead_shielding) (or ice or other stuff)*?
[Answer]
I'll defer to NASA on this one.
With human missions to Mars looming on the horizon, research into how to protect astronauts from radiation is a major field of study. NASA is [conducting research](https://www.nasa.gov/feature/goddard/real-martians-how-to-protect-astronauts-from-space-radiation-on-mars) into a few potential areas; I'll give a brief overview of each.
## Hydrogen
One of the best ways to protect against high-energy particles is with a particle of a similar size. Guess what? Hydrogen is basically a particle (an atom composed of 1 proton + 1 electron). Even better, it's the most abundant element. Using water as shielding has good potential; it's also necessary for the astronauts, so they're already taking it with them. Additionally, hydrogen is a major component in some plastics, such as shopping bags and water bottles. This kind of plastic isn't structurally feasible for a spacecraft, so it would add mass and make launches harder, but there's good news on this front!
## Hydrogenated BNNTs
This is a new material being developed: hydrogenated boron nitride nanotubes. It has the potential to double as a structural component and protection against radiation. They've even figured out how to make spacesuits out of it.
## Force Fields
Yes, they're looking into this, too. We're nowhere near what we see in fiction (Star Trek, et. al.), but creating an energy-efficient magnetic field (exactly like the Earth does naturally) would be an excellent form of protection. At the moment, though, doing so is prohibitively energy- and material-intensive.
## Medication
One suggested item is also a medication that would actively alleviate the impact by radiation on the astronauts. This one is currently purely theoretical.
[Answer]
Here are some articles discussing the idea of a portable magnetic shield. A [pro one](http://www.islandone.org/Settlements/MagShield.html) and a sorta [con one](http://engineering.dartmouth.edu/~d76205x/research/Shielding/docs/Parker_05.pdf). Using ice or water as a physical shield shouldn't be casually dismissed though, it is likely that the ship and crew NEED lots of water, might as well multi-task large tanks of water if you have to bring it with you anyway!
Another option would be a solar shield/bunker just to block solar flare radiation. This would rely on mass, but would be less massive than wrapping your entire ship in it. The crew/electronics areas would be protected, but just from one direction (or a very confined area). This would require an early warning system for flares and either the ability to maneuver the ship to put the shield in between the ship and the flare or for the ship to operate normally while all the crew huddle in the bunker. This wouldn't help with background cosmic radiation, but perhaps there is a biological solution for that, making human DNA robust enough to resist persistent low levels of gamma rays (probably not a good idea for children or fertile women though).
But if you have a super energy source, then you presumably have access to all sorts of other high tech things. The mag shield is more feasible with tons of power, and travel times would be short enough that cosmic ray exposure could be minimal and solar flares wouldn't be a guaranteed thing every trip. In this case, something like a [plasma shield](https://www.newscientist.com/article/dn9567-plasma-bubble-could-protect-astronauts-on-mars-trip) could help. It would lower exposure to cosmic radiation without the need for a strong magnetic field and perhaps in the event of a solar flare, the shield could be "dialed to 11" for a short period of time.
Heck, perhaps the crew spends the entire flight secure in small shielded coffins, living in VR with anthropomorphic drones for when they need to do physical work. This is rather dull for fiction, but probably quite feasible for real world work in an extremely hazardous environment. Bulk cargo carriers and the like would probably be completely automated, so humans would just be around for travel, search and repair missions (for when one of those drone haulers breaks down), and exploration. We are pretty close to being able to do [fine detail work with drones](http://www.bbc.com/future/story/20140516-i-operate-on-people-400km-away) so it shouldn't be much of a stretch for an entire space mission to be completed with the crew in VR the entire time.
[Answer]
I'll bring out a little idea that's been considered for lunar colonization; while it might work better for a station than a ship, it's still worth considering, I say.
# Water
[](https://i.stack.imgur.com/VXard.png)
Turns out, water is a pretty darn good insulator from radiation! They use the same stuff to store old nuclear fission rods, when they go bad. And this useful trait has been considered for a lunar colony. Imagine an inner "safe room", surrounded by water to keep out harmful solar radiation during solar flares. That's basically the idea.
Now don't take this as me saying your spaceships should be water-ships. Far from it, ya don't have to go that far. But consider this: during those longer treks, close to large gas giants and during heavy solar flares, your crew will need a little more protection from radiation.
So a yellow alert sounds, and all staff are sent to the rad-bunkers: special rooms on the ship surrounded by a tank of water, with enough supplies and tools to wait out any high-radiation zones. Then, when the danger is passed, the crew exit, and return to their posts!
Just an idea, but one with some basis in reality. And who knows? It might come in handy!
[Answer]
## Major Caveats
Let’s start this discussion by saying that although crazy things are possible we aren’t trying to build for every crazy thing.
For example, the [Oh-My-God](https://en.wikipedia.org/wiki/Oh-My-God_particle) particle describes a cosmically-sourced particle moving so fast that it hits with the force of a baseball. Despite the enormous power and theoretical possibility of being hit by a barrage of the things, they are so rare that we aren’t going to consider them.
Space dust is another example. The faster you go, the more space dust starts to feel like bullets. I’m leaving it to you to deal with shielding against that sort of debris… we’re only talking about radiation here.
## Ionizing Radiation
**Ultraviolet Radiation - No Problem**
Ultraviolet radiation - the 10-125nm area - ionizes air molecules and is biologically hazardous. On Earth we are generally shielded by our atmosphere, but in space that is not the case.
Fortunately UV radiation is blocked or reflected by any material likely to enshroud your spacecraft. Quoting [Wikipedia](https://en.wikipedia.org/wiki/Ultraviolet#Blockers_and_absorbers), “standard summer fabrics have UPF of approximately 6, which means that 20% of UV will pass through”. In contrast, Earth’s atmosphere blocks about 98-99% of UV radiation. The logical extension here is that if your spaceship’s hull were comprised entirely of t-shirts, with just 3 layers you would block more UV than Earth’s atmosphere (99.2% vs 98%), and at 5 layers you could block 99.968%.
To be safe I would probably move up from t-shirts to sweaters… or, you know, pretty much any metal of non-trivial thickness.
**Alpha Radiation - No Problem**
Alpha particles consist of two protons and two neutrons. They are charged and so interact with matter strongly, which is both a good and bad thing. On the bad side it means that standing next to an alpha particle emitter can be very hazardous, however on the good side the fact that they do react with matter so readily means they are also blocked very readily.
The standard statement on Alpha radiation is that, in general, a standard piece of paper is sufficient to shield you. So unless you plan on making your spaceship out of ultra-thin paper, I think you are OK on this one.
**Beta Radiation - No Problem**
Beta radiation is basically an energetic electron. Being smaller it can be more penetrating than alpha radiation, and is also capable of causing bodily harm. However, any non-trivial amount of metal shielding (eg. 1-2mm of aluminum) will stop this radiation from penetrating.
**Gamma Radiation - How Much Weight Do You Wanna Bring?**
Photons less than 3x10^-11 meters. Bad ju-ju.
The trick with gamma radiation is that the *type* of shielding is almost (but not quite) irrelevant. What matters most is the *mass* of material that gamma rays pass through, not the makeup of that mass. For example, a lead shield only provides a 20-30% improvement over a lighter metal like aluminum or something like soil on a per-kg basis. Obviously though, lead (or, better, tungsten) is more compact, which may have advantages in terms of ship construction.
To identify how much shielding you need, you’ll need to consult the [Half Value Layer](https://www.nde-ed.org/EducationResources/CommunityCollege/Radiography/Physics/HalfValueLayer.htm) index for your target material. This index identifies how thick the layer of material needs to be to reduce the gamma radiation allowed through by half. The HVL for a few materials for gamma radiation from Cobolt-60 are:
- Concrete: 60.5mm
- Steel: 21.6mm
- Lead: 12.5mm
- Tungsten: 7.9mm
- Uranium: 6.9mm
Next you need to identify what amount of gamma radiation is normal for your environment and what you consider “safe”. To tell the truth I could not find a good number for the amount of normal background radiation in space, nor even good peak estimates. On the safety side though, we do know that when we are talking about short-term exposure anything [less than 15rem](https://www.nde-https://www.standeyo.com/News_Files/NBC/Roentgen.chart.html) is basically undetectable and that, discussing long-term exposure norms, the average American receives ~0.62rem.
Not knowing the background radiation amount is a problem, but I have a solution: we cheat. I’m going to make the not-so-wild assumption that a 1.2 megaton nuclear blast releases more gamma radiation at 2km ([500 rem / 5sv](https://space.stackexchange.com/questions/1336/what-thickness-depth-of-water-would-be-required-to-provide-radiation-shielding-i)) than you are going to get from peak background radiation in space. Though I could not find any hard numbers about what background levels are in space, this assumption seems to hold with what I found. So let’s just find out what it would take to protect one against that level of radiation all the time.
To reduce 500rem to <0.62rem, you should plan on 10 HVL’s (takes it down to 0.49rem). More is better though. That would mean shield thicknesses of:
- Concrete: 605mm (23.8”)
- Steel: 216mm (8.5”)
- Lead: 125mm (4.9”)
- Tungsten: 79mm (3.1”)
- Uranium: 69mm (2.7”)
Personally though, I’d add another layer to be safe.
As a reminder, the key here is MASS. You can use water and only take a 20% performance hit on a per-mass basis, but 1 cubic centimeter of Tungsten weighs a LOT more than 1 cubic centimeter of water. You can choose other materials like water, but you the thickness required will increase sharply when using non-metals or even lighter metals.
**X-Ray Radiation**
This is really a duplicate to Gamma radiation. Effectively, if you elect to block Gamma radiation with a dense metal, it’s going to deal with X-ray radiation as well.
In short, using Concrete as the example, a 1GVp X-ray has the same HVL requirements as gamma radiation from Cobalt-60 decay (44.45mm). Lead, however, goes down from 12.5mm with Gamma radiation to 7.9mm with X-rays.
**Neutron Radiation**
Here’s where things get interesting.
To protect against Gamma radiation and maintain ship slimness you want a heavy metal shield… but that’s totally inappropriate for a Neutron shield. Heavy nuclei have a very hard time slowing down a neutron, let alone absorb a fast neutron.
At the same time, having no charge they ionize matter only indirectly and have great penetrating power.
Your best bet for Neutron radiation is to use a high concentration of light elements, like hydrogen, which can absorb neutrons quite effectively. Water with Boric Acid is ideal, though probably not useful in constructing a long-term vessel.
To make a long story short here, see the link below from the Space SE, which recommends 1m of water be used for shielding when in Earth’s orbit. It’s either 1m of water or a lot more of something else, when discussing long-term travel.
## Shielding So Far
So far we have identified that to shield the ship you need:
* Alpha Radiation: Literally anything of any thickness
* Beta Radiation: Any non-trivial amount of metal is ideal
* Gamma Radiation: 125mm of lead (more examples in section)
* X-Ray Radiation: Covered by Gamma Radiation shield
* Neutron Radiation: 1m of water
With that summary being stated though, you don’t need both 125mm of lead AND 1m of water; in reality the answer could be a compromise between the two (as long as you compromised on the amount of lead and not on the amount of water).
For the sake of safety factors though, let’s say that you keep both. Presuming that you don’t want the water outside the hull and that you don’t want it uncontained INSIDE your hull either, you could happily get away with an **80mm outside hull of lead**, **a cavity for 1m of water**, **and a 45mm internal containment wall**.
If you have other material lining your ship (and I presume you would, on average) then you can shave off some additional size that way or leave the measurements as-is and enjoy some additional safety margins.
## Non-Ionizing Radiation
This section covers visible light, infrared, microwaves, radio waves, VLF and ELF. In general, this is all radiation on the electromagnetic spectrum which your shielding as currently described could handle with ease. Visible light isn’t going to be a substantial problem, and otherwise the ship is going to act like a faraday cage.
One challenge you may have is heat acquisition due to infrared (and the other frequencies to a lesser degree). Object cooling in space can be quite difficult, but how that can be dealt with is really another topic… though one I would suggest looking into.
[Answer]
Planets are shielded from the deadly solar wind (an array of charged particles) through their magnetic fields. I would suggest the same for a spaceship. Basically, you would want to turn your spaceship into a giant electromagnet.
# How it would be done?
This magnetic ability of the spaceship would have to be integrated into its design from the basic level. When you start building the outer shell of the spaceship, you would make it two-layered. The outer layer would be what spaceship shells are usually made of (some alloy of aluminum or titanium), and the inner layer would be [Alnico](https://en.wikipedia.org/wiki/Alnico) wrapped in insulated electric wire.
When the spaceship is in space, you would turn on the electricity to the coil, turning the alnico layer into a powerful electromagnet. You would want to orient the polarity of your spaceship magnet so that it is the same as the polarity of the solar wind, hence deflecting it away from your spaceship. This can be easily done by simply reversing the polarity of the electric current flowing through alnico's wiring.
[Answer]
I'd recommend **Equipment**.
You're going to need lots of big, heavy, reliable equipment on your spaceship. Things like:
* Power sources (probably VERY large - lots of metal and water)
* Pumps and Fans (for heat transfer)
* Refrigeration units (for frozen babies)
* Atmosphere control (for breathing...)
* Spare parts
* Stores (especially water)
* Fuel
* Engines
* Severs and other electronics
So one could imagine a space ship where the people largely live and work in the center of the vessel, and lots of infrequently visited equipment and stores are spread around the exterior.
This equipment is going to be largely unaffected by the high energy particles that are the most dangerous portion of cosmic radiation. A few inches of steel will lower the ionizing radiation level by an order of [magnitude](https://www.nukeworker.com/study/hp/neu/Part_2_Radiation_Protection/RP-4_Radiation_Protection.pdf).
When personnel need to do maintenance or otherwise interact with this "shielding equipment" they might bring temporary shielding, carefully track their time, and take other preventive measures.
This actually works better with larger spaceships; surface area grows more slowly than volume as you scale up - so the fraction of your equipment that needs to be "infrequently visited" can be smaller.
This is known and used widely in the nuclear industry - portions of the plant immediately adjacent to the reactor are designed to be visited less often, and the further away you get the more all the equipment has soaked up the zoomies.
[Answer]
If we assume that we are so advanced that we can create nigh unlimited amounts of energy, I think you could also assume that we mastered building objects at the molecular level. It doesn't seem crazy to think that we could manufacture some hi tech sandwich polymer of highly radiation resistant material being
1) worn by astronauts all the time
2) used in the hull of the space ship
Passive solutions (things that are "always there") seem to always be better than active solutions (energy shield that needs to be activated)
] |
[Question]
[
So, for a reasonably detailed version of my magic system, go [here](https://worldbuilding.stackexchange.com/questions/33507/how-might-castles-develop-in-magical-world). Because I'm pretty sure no-one went there, it says,
**Brief Overview of Magic**
These powers manifest themselves any time from birth to the end of puberty. These magical powers fall under seven broad categories. Air, water, earth, plasma (fire/lightning), plants, light, and animals. Animal magic is tricky, because living things resist magic. But, many animal mages can influence animals, and some can control dead animals (this is called necromancy and is a big societal no-no.) The strength and scope of magic varies from individual to individual. But, these are the most common in order. Earth, water, air, plants, animals, plasma, and light.
These magical capabilities are like the show Avatar, the Last Airbender, in how controlling magic works. However, in my book magic is much less powerful. For instance, an earth Mage may only be able to influence as much dirt as they could lift, and lifting this dirt would take about as much energy as doing it by hand, except you don't have to touch it, and it could be a perfect brick shape. No force is exerted in separating the dirt or material from other similar material attached to it. So if you were to pull this rock in two, that would take little effort, other than the force of pushing the pieces apart.
Magic is like a muscle that is really hard to develop.
The level of magic described above is only about 75% of magic users. Everyone else is more powerful.The strongest people can do things like shoot lasers, uproot trees, be human flame throwers, make zombie hordes, create small tornadoes, cause rovers to overflow or to break dams, or cause small earthquakes. This is about 7% of the population. Everyone else is in between.
**My Question**
So, in my world, depending on where you live, you attend school for about eight years. You graduate at 12-16 years old. Most people then proceed to get an apprenticeship or learn a trade. The time period is not specified, but it is probably comparable to the 18th century. However, any time between 1750-1875 would probably be fine.
Given the specified time period, and that a lot of society is fueled by magic, what subjects would be taught in school? Assume that a lot more people have access to these schools, and that magic is taught a lot more after graduation.
[Answer]
So, Magic is a natural part of your society? Then it might be handled as easy as we do it with science topics this day.
Small kids will learn "how not to burn your house down" probably by their parents, "how to use it without roasting your other students" in school and "how to use it to burn down a house and roast other people" in the battlemages university.
It would be the same as it is with potential dangerous stuff today: don't mess around with fire, when we are young, how to separate H and O from Water and making it pop in School, and for people which do show signs of potential in that specific area there are many ways to use this, from creating pyrotechnic, over controlled destruction of buildings, up to creation of new burning agents for weapon usage in war.
So these who are talented would be reported by the teachers to... whatever authority could be interested in that. Find out what the kids are good at and try to put them somewhere your group of interests would be happy about. Expect teachers, who do it the government-way and sending talented flamers to an institution where they can benefit their country by... well... burning down something.
These who do show more talent than common folk in an area of magic may get access to special universities, where they dedicate themselves to ridiculous magic science. These are the guys which shoot fireballs at volunteers which happen to wear experimental protective gear. So expect five mages with lists which do make notes, one who runs in circles screaming because the protective gear didn't work, one who is standing around looking sad because he was the one who shot the fireball, one fire department mage that is trying to put out the flames, at least one magic nurse who will try to fix that burning guy and about fourty students standing behind a marking observing the scene with their mouth wide open. Its science!
Well, you could invoke circumstances that are more professional than these at the Unseen University in Ankh-Morpok, but that would be boring.
Rich people would stuff their heirs into exclusive colleges (yes, like that one where they play Quidditch) to get more exclusive teaching in the art of magic. These who excel there will someday become archmage of such a school or get other well paid positions.
Then there are these guys which don't had access to a proper school. Either you have that guy who becomes the greatest mage off all time by himself, or you have those kids ending up in more shady groups, which may use talents detected for less lawful stuff when grown up. In that case you should put the more motivated but less gifted kids from the lawful end of societies spectrum into some kind of magic police. Have your Inspektor Average Magic Joe beating absurd powerful shadow mages by using his brains (or the horse of his partners after getting suspended from job) could be a fine plot point, if you are into such things.
Well... after all, things will not go to fancy when magic is a part of you world that did exists as long as people can remember. It would become something common that isn't handled in any fancy way. Just install 1800 A.D. societies and put magic inside like its something the kids do as soon as they can talk. Darn, I won't thing there could be any insurance company that is making any profit...
That's how I think magic stuff might be handled in such a society. But as I always say: look into computer games where magic is more common. There where a lot of (more or less) creative heads, who did the worldbuilding way before you. Skyrim might not be the best reference, Dragon Age... maybe (they do have an anti-magic-templar force to keep these giftet ones at bay)... if I remember a good example, I will add it if needed.
[Answer]
A day in magic school:
Good morning class, please sit down. Please stop trying to blow the girls skirts up Johnny. Girls, I know he's a creep, but please put him back down. Gently!
So, first lesson today is English - could you pass your homework down to the front please.
Ok, which one of you wrote this essay? Come on, I wasn't born yesterday - all of these essays are identical apart from the handwriting. Oh, except yours, Johnny, which is in mirror writing - you need to spend more time on practical magic instead of trying to see knickers.
Seeing as none of you can be trusted, we'll spend the lesson redoing the essay, properly. Stop groaning - what did you expect!
---
Ok, English books away. Let's do some maths. Who can tell me the area of a right angled triangle?
Excellent. Could you write that on the board please. No, get up and do it by hand - we can't afford any more blackboards this year. I know it was an accident, but you still managed to shatter the last board, didn't you...
---
Lunch time, class! Form a line by the door and we'll go down to the dinner hall. Johnny, have you left any surprises in your desk? Go and sort them, then go to the back of the line. Did you really think that would work?
---
Ok, we've got art and magic this afternoon. Art first. Don't groan.
Right, we're going to work on still life drawing today. Here is a bowl of fruit. Get out your sketchbooks and draw what you can see, concentrating on the shadows between the fruit.
Stop moving that banana and those plums, whoever it is. Actually, it's you Johnny, isn't it...
Whoever is using the light spell, please stop it. You've washed out all the shadows for everyone.
Johnny....
Why has that apple turned brown? Who is messing with the local time field around it? Can you undo it? No? Fine, get another apple and put that one in the bin. I know it's disgusting - you made it like that.
No! Don't try lift...
Ok, you two, take Johnny to the toilets and wipe off as much rotten apple as you can. You, get the mop and start cleaning. By hand.
---
We're supposed to be doing magic class now, but because you've been practising all day, I think it's safer for us all if we just sit quietly until it's time to go home, don't you?
[Answer]
How do you teach magic in a 1750-1800 school ?
First a note : your world's society is really advanced for having public schools for every one before 1800.
So, back to school !
Children are left in the care of their family up to 8 years old. Somehow, they managed not to burn their parents or their house during that time.
All this was stated before : start small, build the appropriate social restraint, then use the skills at full power for the chosen ones.
I have two points :
In such an era, most of the teaching will probably be linked to some religious authority (not all, but a lot of it : the clergy were the one with most time to think, then teach) so if this fit your world, theology and metaphysics will be quite important.
Then you have to think about the way magic works. It's not really a science. Partly, but not entirely. It is also a form of art.
Students geared toward magical careers will learn to think of imaginative and original solutions to apply their power. The idea here is that a limited power can be as useful as a great one, if applied correctly.
I'll direct you toward the Eddings' books (The Belgariad) and Mercedes Lackey's Sisters series where they explain exactly that : apprentice (mages with low abilities) with enough knowledge of the world and imagination to use their abilities can be more useful, at the end of the day, than adepts (mage able to channel a lot of energies) who would be more blunt in their ways.
Of course a smart adept can wipe both the smart apprentice and the stupid adept, probably together.
So, those school would work toward giving their student as broad an education as possible, so that they can get the most out of their magic.
From this point, it all depend on how advanced is your civilisation. Think "antique philosophers", "edge steampunk", "the art of war" but also "out-of-school excursion", "practical cases",... Everything that can open those mages' mind.
] |
[Question]
[
This is a multi-tiered question. I have seen these larger questions before, but if I need to separate them out into their own questions let me know.
In my story I have a machine that can manipulate gravity, either increasing it or decreasing it. The how is not important, I want to know what would happen after it was turned on at different levels.
What would happen to the earth if a zero-g environment were created on the earth that is:
* 1 cubic foot
* 10 cubic feet
* 100 cubic feet
* 1 cubic mile
* 10 cubic miles
* 100 cubic miles
* Encompassing the entire surface of the earth and atmosphere, but not penetrating into the surface
* Encompassing the entire earth, from the top of the atmosphere right down to the core.
These events will be localized to the Earth, meaning that the Earths gravity still exists outside of the area of effect.
Area outside of the zero-g environment experience normal gravity, including directly above it. Time frame is indefinitely (or until the machine is turned off).
I assume that when you get into the larger areas that it will have extremely detrimental effects on the Earth, what would these be? On what kind of time scale would the atmosphere leave and make the planet uninhabitable? Would the planet break apart? Would it happen within minutes, hours, days, years?
[Answer]
I'm assuming all but the final two situations are with the effect epicenter on the surface of the Earth in an open area.
>
> 1 cubic foot, 10 cubic feet, 100 cubic feet
>
>
>
Gravity is gone inside a relatively small area. The air pressure inside the volume might be a little wonky, causing a perpetual updraft. The air at the edges of the volume, especially the bottom, would be under more pressure than the air just inside and it would pour in and flow upward to the slightly lower pressure air on top.
>
> 1 cubic mile
>
>
>
The ground half a mile down is under a fair amount of pressure from the ground above it (about 200 atmospheres). As the device turns on the pressure is immediately relieved and the ground will pop up rather violently. There is no gravity to stop the upward motion and the ground will reach the top of the volume and then oscillate at the edge. Moving past the edge and falling down to collide with ground moving upward. Eventually any floating ground material will pile up at the edges outside the volume of effect. This would be a great way to do some strip mining.
>
> 10 cubic miles
>
>
>
At 1.3 miles down the ground has [645 atmospheres of pressure](http://news.stanford.edu/pr/00/000315rocks.html) from the ground above it. When the device is enable this pressure is immediately released and the ground violently explodes upward, likely killing anyone on the surface. The ground will rapidly reach the upper edge of the volume and be flung in all directions. Air rushes into the sides of the volume and blows out the top into the low pressure atmosphere above. The heavier than air materials will eventually settle around the edges of the volume.
>
> 100 cubic miles
>
>
>
Similarly to the 10 cubic mile case, except the pressure released is over 1,400 atmospheres at 2.98 miles down. The explosion is more violent and spreads material even further away. The volume cycles huge amounts of air through it and significantly disrupts the local weather.
>
> encompassing the entire surface of the earth and atmosphere, but not
> penetrating into the surface
>
>
>
We all die. We lose significant air pressure and people would asphyxiate immediately. Everything not bolted down is now airborne as it's no longer tethered to the Earth by gravity it continues along its path. You would observe this as the the Earth and everything bolted down as pulling away from you and everything *not* bolted down. Everything gets a turn at exiting where the edge of the atmosphere used to be then being pulled back down to collide with the surface of the Earth again. Masses of vehicles, boats, and bodies will begin to form into huge hurricane spirals due to the [coriolis effect](https://en.wikipedia.org/wiki/Coriolis_effect). The floating debris begins to move at different speeds than the surface of the Earth as it spins. Eventually everything gets dumped into an ocean (assuming the effect hugs the surface of that too, otherwise it's flying around with our bodies).
>
> encompassing the entire earth, from the top of the atmosphere right
> down to the core.
>
>
>
The Earth explodes. The core is under immense pressure from the weight of the ground above it. Suddenly that weight is gone and that pressure is going to equalize. The mass of the Earth ejects from the edge of the anti-gravity volume but there is no Earth to maintain the gravity outside of it. It continues outward but is eventually pulled into an oscillating dance at the edges of the sphere while pieces on the far side pull on pieces on the opposite side. As they fall into the anti-gravity sphere they continue through where the Earth once was at constant velocity (unless they hit other pieces doing the same) and emerge to be pulled somewhere else. Oh, and obviously, everyone is dead.
[Answer]
# Pressure release and earthquake
Let's say the earth is flat. Someone standing at the center would feel weightless. The closer he gets to the edges the more matter he will have behind him and the stronger gravitational pull will be. He will literary feel like he is climbing a steeper and steeper mountain. It's the same for the matter which composes the Earth. **Think of it as a sponge.** As soon as you release **it it will expand and take more place**. It the same for matter: at the center it weights nothing but it is squeezed between the matter which stands at the edges, willing to collapse. This squeezing (pressure) compresses matter which consequently will to expand as soon as possible. The moment you suppress gravity you allow matter to expand and release its potential energy as a sound wave travelling through Earth.
In my opinion if you target a block which is inside the crust **this would look very much like an earthquake** and would have similar impacts on the environment. If you activate this on a volume that contains crust and air I think that everything described by @Samuel is correct.
# No centripetal force anymore
According to Newton's laws of motion, any object to which is applied a force $F$ will move through empty space in straight line forever. It's **linear motion** and no force is required to *actually* move. Force is required to *change* the momentum (direction and speed). Objects on Earth's surface are not moving in straight line because of a **centripetal force** which keeps changing their momentum. They *want* to move in linear motion but they can't. They are like a rotating ball attached by a string. This force is Gravity.
The Earth is spinning very fast. The angular speed of Earth's rotation in inertial space is [about $7.2921150\times 10^{-5}\ \text{rad/s}$](http://hpiers.obspm.fr/eop-pc/models/constants.html) (solar second). When you multiply this by equatorial radius of $6\,378\,137\ \text{m}$ it gives you a tangential speed of $465.1\ \text{m/s}$. If you were able to remove gravity from a block of matter, nothing (as far as I know) would stop it from moving in straight line at $465.1\ \text{m/s}$ into space except for the frictional forces and the effect area. Friction might be quickly overwhelmed as your block increases in size.
# Scratching the surface
>
> I meant to have the area of effects not penetrate the surface on any of the scenarios except the last one
>
>
>
If your machine does not target Earth's crust at all things tend to be gentler. Imagine everything @Samuel talked about without any violent explosions. On a large scale however, air displacements would significantly affect the weather, producing exceedingly violent winds travelling at huge speed and destroying almost everything on its passage.
---
### The speed of light
If your matter losses its mass it must become something massless and there is not many options here: it should turn into energy (otherwise your Universe has energy leaks which is very weird and question all modern physics). According to the mass-energy equivalence equation $E=mc^2$ this is completely devastating and equivalent to an anti-matter bomb. Since I suppose this is not really interesting for your story, you have to take this into account, either to ignore it of find a way to avoid it.
---
### How do you do this?
>
> The how is not important, I want to know what would happen after it was turned on at different levels.
>
>
>
I disagree and *how* is certainly a question you should ask to yourself and be clear about in your question: how does your machine remove gravity from the block of matter? Does it modify space-time curvature? Does it make you matter massless so almost unaffected by gravity (turning it into electromagnetic waves and therefore making it travelling at light speed)? It might impacts the answers you obtain here.
[Answer]
For the one that encompasses the surface and atmosphere, you don't mention whether the anti-gravity goes with the atmosphere as it leaves Earth, but let's assume it doesn't.
The first thing that's going to happen is that anything not stuck to the ground will get flung into space by centripetal force. However, as soon as it hits a 100km altitude (the traditional "beginning" of space and outer limit of the atmosphere), it's going to be captured by gravity again, albeit slightly less of it.
This means that all the survivors will live at 100 km on a sort of invisible bubble - almost as if they were in a low orbit (though not the same thing). They'll have to be able learn to swim, though, as all the water will go with them, and form a giant floating ocean around the earth.
Things will tend towards the equator but this movement will be limited by the masses of water.
Saltwater and fresh water will mix so there'll be nothing to drink up there, and I imagine food production will be impossible too.
For people who stayed indoors, and are still on Earth's ceilings, their water is now all gone except what was left in their attic tanks, and they will most probably not be able to breathe because if there's any air left it's only courtesy of the pressure of the air from 100 km above them, which is likely to be tiny (since most of the atmosphere is above the new ocean, and anyway, the Earth's spin is trying to push it away) Besides it's going to get very cold because of the shield of water blocking the sun.
] |
[Question]
[
Alice is in a rush! Luckily, she [recently divined](https://worldbuilding.stackexchange.com/questions/11252/how-to-catch-a-dream-thief) the location of a pair of **boots of speed ®. How far can she get in 10 hours?**
Well, upon closer inspection, a slightly disappointed Alice will tell you they're more like "the long-limbed exoskeleton of speed", but here are the basics:
**Must have**:
* Must preserve the cartilages, bones, skin and general body integrity of the wearer.
* No, it's not a full body suit, so wind (and bugs, yuck) will be a factor.
* Must move significantly faster than a human (duh).
* Must not [take off into the clouds](https://worldbuilding.stackexchange.com/questions/10069/effects-of-a-human-moving-faster-than-sound/10074#10074) with every step (unless that provides the fastest means of transport)
***Nice to have:***
* Zero or close to zero extra fatigue compared to walking
* Able to handle rougher terrain than a perfectly flat paved road
* Not blow up the place when you get going and avoid throwing shards of pavement concrete into the faces of grandmas doing their grocery shopping as you pass by.
*Optional to have:*
* A system that does not desperately need a handwavium or other non-portable powersource
[Answer]
We got some options. Let's start with low-tech and work our way up. Also, as a baseline, we're taking Usain Bolt's records, who did the 100 m dash in 9.58s, which is about 23 mph. Obviously, most people do not come even close to this speed. Marathon runners have covered 1 marathon (26 mi and 385 yards) in 2 hours, 45 minutes, and 46-ish seconds. That's [9-ish miles per hour](http://www.wolframalpha.com/input/?t=crmtb01&f=ob&i=26.21875%20miles%20%2F%20(2%20hrs%2054%20mins%2046%20seconds)).
# Kangaroo Locomotion
Your boots/exoskeleton of speed can be made of a some springy material which allows them to [hop like a kangaroo](http://en.wikipedia.org/wiki/Kangaroo#Locomotion). The nice thing about hopping is that your previous hop can contribute to the energy needed for the next hop. This makes it potentially more energy efficient compared to other forms of locomotion. A "comfortable" speed for a red kangaroo appears to be around 15 mph, with a maximum of 44 mph.
# Cleats or Snowshoes
Your boots of speed could just provide better traction over rough terrain. As Lindybiege hilariously relates [here](https://www.youtube.com/watch?v=-3qTniJsoEg), hobnails and cleats improve your grip, which in turn can improve your speed. Not exactly an exoskeleton, but you can take more direct routes and therefore move more quickly than normal.
# What About Stilts?
As seen on the [records](http://en.wikipedia.org/wiki/Stilts#Stilt_walking_records), stilts do not actually help people move faster, despite the increase in stride length you can get from them. Worse still, stilts are powered by the people using them. (For instance, the 7'13" world record for running a mile? Not impressive.) No, stilts will not help you move faster unless they're powered by something.
# Powered Exoskeleton
There are some [design issues](http://en.wikipedia.org/wiki/Powered_exoskeleton#Limitations_and_design_issues) with powered exoskeletons. It seems most of them are designed for either heavy lifting, or to help the disabled. Most products out there are not designed for speed. If you would, you would find they are:
1. Light
2. Very Energy Efficient
I would go with a [solid state battery](http://en.wikipedia.org/wiki/Solid-state_battery), which stores electrical energy really well compared to many other batteries, and could be potentially recharged by solar arrays. Some simple linear actuators or hydraulics could help get some speed in those legs, but both of those are relatively slow.
[Answer]
I think she needs some heavily tech modified version of **Bamboo Boogie Boots**.
*With a warning label this big, you know they gotta be fun!*
**Adjustable Height**
The boots provide adjustable extensions. To make walking easier, the extensions should retract with each step, this reduces the moment of inertia required to take a step. Think adjustable length [powerbocks](http://www.gizmag.com/powerbocking/12337/). The adjustable length allows Alice to choose a comfortable walking/running pace that keeps her level while walking over uneven terrain. Users of regular passive powerbocks have been clocked [running at 20mph](https://en.wikipedia.org/wiki/Powerbocking).
**Powered**
But Alice's boots are not spring powered passive affairs, they're nano-tech-fusion-fuel-cell powered. They literally *eat ground* with every step. The boots assist with the pushing, allowing for significantly larger steps.
**Cruising**
Comfortably striding at 30mph will allow Alice to travel 300 miles in 10 hours. Maybe a little faster than 30mph if she has some goggles, squints really well, or likes the taste of bugs.
[Answer]
**Fast Travel By Human Slinky**
So I think the killer factor you're going to run into here is air resistance. Since it increases by the square of your speed, going faster didn't seem viable - it will take more and more effort on Alice's part. At first I didn't have any ideas on how to bypass it, but then I thought of *divers* - someone stretched out, limbs together, designed to minimize water resistance. I think we can use the same concept for your "boots" here.
So starting with the diver position as the basis, the problem becomes the landing. Rotating in air is possible but hurts air resistance. But what about having the arms and hands also be capable of handling the landing/springing?
So then our technique becomes:
1. Spring off from the ground in a diver's position to minimize air resistance.
2. At the last moment, open hands and land. Then spring off with your arms, in a **reverse** diver's position with your feet pointed.
3. Land on your feet, re-orient. Go back to 1.
The end result is that Alice will travel like a super-efficient slinky, going from feet to hands and back again, minimizing air resistance the whole way. As a bonus, minimizing air resistance also minimizes Alice's bug intersection count.
**Details**:
1. Suit Construction - we need the suit to act like a spring on both ends. Possibly some sort of advanced metamaterial? Effectively it will act as a form of Regenerative Braking, absorbing the kinetic energy of each landing and turning that into power for the next jump.
2. Travelling this way will be technically difficult (as in, it requires a high level of skill). Based on previous questions I think Alice might be capable of doing it with no assistance, but the average user would probably be in trouble. So I would suggest some sort of vampiric computer assist system - this would be a HUD, a computer with a dumb AI, and micro-motors at each joint. It would take some of the energy of each jump to power, requiring increased effort, but would help the user coordinate each jump and go where they should be going.
3. Priming - Alice will need to "prime" the suit before use by jumping straight up and down. Each jump up will add energy, which will be absorbed and used to help power the next jump. This will build up until the energy lost at each point equals the amount Alice is adding.
4. Environmental and Alice damage - the most efficient angle to jump would be 45 degrees. However, consider that with this mode of movement, the amount of force impacted to the ground - and the amount of G-force Alice needs to handle at each landing and jump - is proportional to the *vertical* component of her movement. The horizontal component is mostly carried through from jump to jump. So the shallower the suit can move, the less damage the environment and Alice will take. I suspect an angle in the 25 to 35 degree range will work best in terms of functionality vs speed, but Alice might need to experiment. Increasing the height of the suit also reduces the G-forces Alice will experience by giving the suit more time to decelerate and accelerate.
5. Hills - it will be difficult to go directly up hills this way, although going down might be fun. I would recommend switchbacking up and down rather than going direct.
An interesting side effect is that this method uses more of Alice's body - in addition to her legs, she utilizes her arms for half of her movement. This should help with endurance. I will try to dig up some math to support this later, but my [WAG](http://www.urbandictionary.com/define.php?term=WAG&defid=1027073) is this method of travel would yield speeds in the 30-50 MPH range with approximately the same effort as a light jog, depending on the user's ability and the exact properties of the suit materials. So she could go **300-500 miles** in your time frame.
She could go faster for short bursts if she's willing to put in more effort and accept additional environmental/body damage, probably up to 100-150 MPH.
] |
[Question]
[
In the story i'm writing [Orcs](https://worldbuilding.stackexchange.com/questions/167531/what-evolutionary-pressures-would-lead-to-orcs?noredirect=1#comment524719_167531) have managed to domesticate hyenas possibly even [cave hyenas](https://en.wikipedia.org/wiki/Cave_hyena)
[](https://i.stack.imgur.com/hdl5G.png)
In actuality, could Orcs (or any other intelligent hominid) domesticate hyenas? Even if we assume that there are no wolfs where they live, would they even want to? If so, what behavioral differences compared to domesticated cats and dogs?
Note: magic does not exist in my story.
[Answer]
Quite likely - though not canines, hyenas are very behaviorally similar to wolves thanks to convergent evolution. They are pack hunters with a hierarchical social structure that a hominid could take the place of. Though not domesticated (domestication requires multiple generations of breeding to permanently alter the species on a genetic level), they can be tamed and trained relatively easily.
There is some evidence that hyenas were tamed and used for food and possibly hunting by the ancient Egyptians, [though it is unlikely that they were truly domesticated](https://thrillseekingbehavior.wordpress.com/2013/01/23/on-the-unlikelihood-of-hyena-domestication-or-no-you-cant-have-one/). Still, that's nothing that a few generations of finely-controlled selective breeding, or a few thousand years of less-controlled selective breeding, couldn't fix.
So why *weren't* hyenas domesticated? In order to really answer that question, we would need to understand how dogs were domesticated, and that question is still up for debate.
The domestication of dogs occured around the Last Glacial Maximum - perhaps cold temperatures and lack of food forced humans and wolves to work together. Regardless of the reason, once dogs were domesticated, they quickly spread through the global human population, and why go through the trouble of domesticating hyenas when you already have dogs?
[Answer]
Most animals can be tamed, in the sense that while you may not be able to command them, you can at least ensure that they do not try to bite or harm you. Note that this isn't the same as domesticating them. To be able to say you have domesticated an animal is to train it to do something useful for you, such as fetch the newspaper or smell out truffles.
Hyenas can be domesticated. You commonly see them in circuses performing tricks for treats. It isn't too far fetched to say you could also train them to be attack dogs of a sort.
[Answer]
Hyenas are sort of domesticated in several places where they are native, see [wikipedia](https://en.wikipedia.org/wiki/Spotted_hyena#Relationships_with_humans). So yes domesticating them is very possible and realistic. They are similar to wolfs/ dogs.
[Answer]
Very, likely to domesticate them. As a matter of fact quite a few have been domesticated and used as pets.
<https://www.youtube.com/watch?v=s2vguqjjtN8>
[Answer]
Google Nigerian with Hyena, There are Nigerian gangsters that have pet hyenas and baboons, there are even pictures of small boys with baby baboons.
The Hyenas and baboons may even be on steroids as some are insanely big and muscly, the hyenas look more like the creatures from lord of the rings.
[Answer]
## It is possible.
It is unlikely they could domesticate modern hyena, *but* they might be able to domesticate cave hyena, specifically since you have orcs, this is a slightly different functional world you have some flexibility to extinct hyena behavior.
Modern Hyena have a pretty strict yet dynamic social structure, which makes it hard for human to take over said social structure. Generally we can only tame individual hyena separated from their packs. Wolf social structure is loose and far less aggressive which is why humans can take advantage of it. It might be possible if you could somehow tame the dominate female but if you separate the female for long enough to do that it is unlikely to be the dominate female anymore.
Of course since this is a fictional setting using an extinct hyena species, you could have slightly different hyena, maybe your cave hyena have a looser social structure, one humans can easily infiltrate/take over.
] |
[Question]
[
We have all heard what too much CO2 can lead to, but so far the biosphere have never been exposed to too low levels of CO2. But what if it did? And please, this topic has nothing to do with the ongoing discussion about global warming. We are talking about the last ice age and a hypothetical scenario where the terrestrial flora and fauna would have suffered because of too little CO2.
Apparently the agricultural revolution happened 11,000 year ago all over the world because of increased levels. Pre-industrial levels are said to have been 280 ppm.
Aerobic plants have three types of photosynthesis. C3, C4 and CAM. The original and most common type is C3. C4 and CAM have evolved to deal better with heat, drought and lower levels of CO2. C4 is a little better than CAM in that regard.
Some quotes found on the net:
*"Studies have shown that the average biomass production of modern C3 plants is reduced by approximately 50% when grown at low (180–220 ppm) CO2, when other conditions are optimal … (The abortion of all flower buds) suggested that 150 ppm CO2 may be near the threshold for successful completion of the life cycle in some C3 species."
"Although some C3 plants like palm trees can cope with a combination of high oxygen levels and warmer, sunnier, and dryer conditions, most C3 plants can lose efficiency in productivity of up to 40% in warm, sunny, and dry conditions."*
(But less CO2 means more stomata, and the more stomata, the more water loss)
*"About 85% of all plant species are C3. All trees, fruits, vegetables, and most food crops are C3. The only C4 food crop exceptions are maise, millet, sorghum, and sugarcane.
On average, at 150ppm the primary C3 plant productivity was reduced an average 92% as measured by dry weight biomass.
During glacial periods land ecosystems have much lower productivity."*
And from this page:
<https://environmentcounts.org/evidence-of-biological-feedback-driving-warming-at-ice-age-terminations/>
*"There is evidence that atmospheric CO2 concentration has never dropped below 190 parts per million (ppm). Analyses of ice cores have revealed that a minimum of 190 ppm was reached at the end of eight ice ages over the past 800,000 years. Although atmospheric CO2 concentration has varied widely, even reaching more than 1,000 parts per million (ppm), there is little evidence for values lower than 190 ppm.
Studies have shown that within a single generation of exposure to low CO2, modern plants that rely on photosynthesis show an average reduction in photosynthesis of 50% when grown at low (180–220 ppm) vs current (350–380 ppm) CO2 concentrations. When CO2 is reduced even lower to 150 ppm, research has shown that biomass production may be reduced by over 90%. When applied to the entire Earth ecosystem, these physiological responses imply large reductions in Net Primary Productivity or NPP (the net carbon uptake by plants after accounting for plant respiration) and carbon storage during glacial periods.
During the initial glacial period, the high reflectivity of the northern ice sheets reflects most of the solar radiation resulting in cooling. As the oceans and atmosphere cool, more atmospheric CO2 is absorbed by the oceans. Atmospheric CO2 concentrations eventually reach a critical minimum of about 190 ppm, which combined with cool arid conditions, cause a die-back of temperate and boreal forests and grasslands, especially at high latitudes. The ensuing soil erosion generates dust storms, resulting in increased dust deposition on the northern ice sheets and greater absorption of solar radiation. As northern hemisphere solar radiation increases during the next Milankovitch cycle, the dust-laden ice-sheets absorb more solar radiation and undergo rapid melting, which forces the climate into an interglacial period. In support of this mechanism, Antarctic ice cores provide evidence of increasing atmospheric dust at the end of all ice ages over the past 800,000 years."*
(Also, plants themselves exhales a lot of CO2 at night, but with fewer plants, less CO2 will return to the atmosphere.)
So, if a combination of several factors had occurred, which had resulted CO2 levels so low that most or even all C3 plants had gone instinct (with the possible exception of cave flora, where C4 plants have adapted to low light and the CO2 levels are sometimes higher than outside the caves, and/or frozen seed and plant matter in permafrost was discovered), but high enough to allow the C4 and possibly CAM plants to survive, more than 90% of all plant species could still disappear. Practically all trees, in addition to most ferns, gymnosperms and moss. There is a risk that peat moss would disappear. Lichen and terrestrial algae would probably be hit hard as well. Which in turn would lead to a mass extinction of animals and fungus.
It's a good thing it never happened, but from a fictional point of view, it could be interesting to imagine what world humans (assuming they survived) would find themselves in once the ice age ended and the production of plant matter returned to previous levels, but with far fewer species.
There are woody C4 plants in the deserts, even if they are usually of modest size. It would take time for them to evolve into trees. C4 and CAM plants are usually not found in cold areas of the world. There would barely be any plant species at all in places like Canada and northern Europe, Russia and China.
Would hoofed animals still be around? Some cave dwelling bats would have been able to survive, but bats and birds that lives in trees would be gone.
It would have been an extinction even of a kind never experienced before in the history of earth.
Would a technologically advanced civilization have been possible at all in such a world? One could still mine for coal, and perhaps use other plants than trees for fuel, or build houses and furniture with other materials, but it would have been far more difficult. And with fewer trees, little or no paper, and without paper, not many books that one could use to pass on knowledge from one generation to the next.
[Answer]
Let's get to the basics of plant physiology first, and then get into the hypothetical question of whether or not mankind could survive or thrive in such an environment.
First of all, yes; plants actually NEED CO2 to survive. No, they don't 'breathe' it as you rightly point out, but their roots are embedded in a medium called soil from which they primarily draw water and nutrients. There are no meaningful carbohydrates in normal plant soil and so a plant without CO2 available to it can starve, not because of the lack of oxygen, but because of the lack of sugars produced by photosynthesis.
So, yes, a lack of CO2 is bad for plants; no question. But, the real question is whether or not CO2 levels can ever get down that far. Let's discuss that next.
CO2 and water are lower energy states for hydrogen, carbon and oxygen to be in than (say) O2 and sugars. That means that all things being equal, this is the more likely state of these elements in a natural environment. This is especially the case with oxygen, which is more likely to bind to exposed iron ores than remain in the atmosphere as molecular oxygen. Also, because we animals *don't* produce our own oxygen and sugars, we are constantly releasing the highly toxic (to us) CO2 back into the atmosphere, meaning that as long as there are animals alive, there is enough CO2 in the atmosphere to support plant life to at least some degree, meaning a mass extinction because of a lack of CO2 is highly unlikely.
Another way of looking at this is that in order for the plant extinction to occur as a result of this, you would pretty much have had to wipe out all animal life first. Remember too that the reason why plants evolved to do what they do in the first place is that it is assumed that the early Earth's atmosphere contained massive quantities of CO2 and that the [Great Oxygenation Event](https://simple.wikipedia.org/wiki/Great_Oxygenation_Event#targetText=The%20Great%20Oxygenation%20Event%20(GOE,about%20one%20billion%20years%20ago.), which is believed to have taken around a billion years to occur, was only possible because plants had so much CO2 to process in the first place. Once they were well underway freeing up all that oxygen, it was possible for animals to evolve to consume that oxygen directly rather than free up their own via a costly endothermic reaction like photosynthesis. All of a sudden the oxygen could be reacted directly with the carbohydrates harvested directly from the plants that are eaten by these animals, those plants also providing essential nutrients, and our oxygen cycle is born.
Put simply, the likelihood of a critical shortage of CO2 at any point in the evolution of life on Earth after the first animals appear is highly unlikely, not to mention that [volcanoes](https://www.scientificamerican.com/article/earthtalks-volcanoes-or-humans/#targetText=According%20to%20the%20U.S.%20Geological,CO2%20emissions%20every%20year%20worldwide.) alone are likely to provide enough CO2 to the atmosphere at critical points so as to make this scenario unrealistic.
Is it *possible*? Yes, mathematically at least. but it's so improbable that it doesn't surprise me in the least that it's never happened.
[Answer]
Yes, it is possible, and it's one of the scenario for [Earth future](https://en.wikipedia.org/wiki/Future_of_Earth):
>
> The luminosity of the Sun will steadily increase, resulting in a rise in the solar radiation reaching the Earth. This will result in a higher rate of weathering of silicate minerals, which will cause a decrease in the level of carbon dioxide in the atmosphere. In about 600 million years from now, the level of carbon dioxide will fall below the level needed to sustain C3 carbon fixation photosynthesis used by trees. Some plants use the C4 carbon fixation method, allowing them to persist at carbon dioxide concentrations as low as 10 parts per million. However, the long-term trend is for plant life to die off altogether. The extinction of plants will be the demise of almost all animal life, since plants are the base of the food chain on Earth.
>
>
>
It can be that life will develop new adaptations to overcome this obstacle. However, life as we know it is based on carbon. Further down the road we have the end of carbon cycle:
>
> In about one billion years, the solar luminosity will be 10% higher than at present. This will cause the atmosphere to become a "moist greenhouse", resulting in a runaway evaporation of the oceans. As a likely consequence, plate tectonics will come to an end, and with them the entire carbon cycle.
>
>
>
[Answer]
**This actually happened 34 million years ago.** Decreasing atmospheric CO2 levels (and the associated drop in temperature) caused the most severe mass extinction event since a meteor killed the dinosaurs.1
Rising CO2 isn't concerning for any inherent danger of high CO2 levels. For the bulk of Earth's history, atmospheric CO2 has been over 800ppm. The Cambrian period, famous for its tremendous explosion of biodiversity, saw CO2 levels well over 4000ppm. The pre-industrial levels were actually pretty close to as low as atmospheric CO2 has ever been, at least during the Phanerozoic eon.2
The reason why the rise in CO2 is concerning for the biosphere is because of the *speed* of the change. Our biosphere is set up to inhabit a world with 280ppm atmospheric CO2. If that rises faster than species can adapt, it leads to extinction. Conversely, if it were to drop faster than species can adapt, it would also lead to extinction.
In fact, given that the preindustrial world was considerably colder and less-CO2-filled than average, it's pretty reasonable to suppose that rapidly reducing atmospheric CO2 would be substantially *worse* than rapidly increasing. Reducing efficiency of photosynthesis isn't the only possibly concern here either. At present, the Earth is in an ice age (in geological terms, this term means that there is glaciation at the poles - yes that is how it's defined). Removing greenhouse gases from the atmosphere would make it *colder* than its already colder-than-normal state, and we'd see a repeat of the Eocene-Oligocene extinction event, maybe even more severe.
On the topic of plants dying off due to being unable to photosynthesize - this wouldn't happen if the reduction were gradual enough. Evolution would find a way to solve this problem. But a rapid reduction of CO2, just like a rapid increase, would certainly wreak havoc on all the organisms adapted to live in an environment with 280ppm atmorspheric CO2. I think you might be misinterpreting the 90% reduction in plant biomass production that occurs at 150ppm. This doesn't imply 90% of plant species would go extinct. It does imply that this would be very hard for many plants to deal with. But the selective pressure would be very strong and C3 plants would adapt (many would go extinct of course, but I doubt that *all* of them would). This is why, while CO2 dropping 34mya caused an extinction event, we aren't still through going it despite atmospheric CO2 being even lower today. Plants adapted to what was, at the time, a much-lower-than-optimal CO2 level, so that now what is 'optimal' to modern plants is lower. It's always a rapid change in environmental conditions that causes extinction events, the absolute level of CO2 or O2 or temperature isn't important (to within reasonable bounds of course, but I don't see why 150ppm CO2 would be outside of reasonable bounds).
**Citations:**
1. Prothero, D.R. (1994) "[The Late Eocene-Oligocene Extinctions](https://www.annualreviews.org/doi/pdf/10.1146/annurev.ea.22.050194.001045)" *Annual Review of Earth and Planetary Science.* 22:145-165.
2. Berner, R.A. (1990) "[Atmospheric Carbon Dioxide Levels Over Phanerozoic Time.](https://science.sciencemag.org/content/249/4975/1382)" *Science*. 249(4975):1382-1386.
[Answer]
Many landplants produce equal or more CO2 than they consume. O2 production is sort of energy waste and more advanced plants produce less net O2 and more CO2. It's a reason why air is more fresh in pine forests.
So all landplants has a very low impact on O2/CO2 ballance. Almoust all O2 produced and CO2 consumed by water-based plants (most of them unicellular) and by water itself. And there are huge amount of CO2 in ocean - more than in atmosphere.
The main reason why during glacial period CO2 levels were so small it the fact that solubility of CO2 greatly rises at low temperatures ("keep it cool" - you know), and ocean "takes" more of this gas from atmosphere.
All it means that your scenario is possible only when Earth losses almoust all of it's (surface) carbon. *And if this event somehow happen - it imply dissapearence of any carbon-based life.*
In all other cases CO2 level just can't drop below of what it was in glacial period - it a question of global chemical ocean/atmosphere ballance.
[Answer]
This is probably what caused the **end-Devonian extinction event**, one of the largest extinction events in Earth's history. Specifically, what appeared to happen was the evolution of trees and other plants with large roots. The middle to late Devonian sees the appearance of Earth's first tree, *Archaeopteris*, and during the Frasian and Fammenian you get an expansion of *Archaeopteris* species across most wet parts of the globe. There were two major consequences of this. One, the increase in plant biomass on land resulted in a massive drawdown of CO2 as it was fixed into plant tissues. Because lignin-digesting bacteria hadn't evolved yet, when these large plants died they tended to not decompose, resulting in even more carbon being locked away (and incidentally marking the beginning of the formation of coal beds that extended into the Carboniferous). Secondly, the evolution of deeper taproots both broke up the soil and accelerated the weathering of silicate rocks, which also draws down CO2 from the atmosphere. It didn't help that the more stable root systems also shifted many braided streams into meandering ones, and meandering streams erode rocks faster than braided streams.
The end result of this was both a massive influx of nutrients into the oceans causing eutrophication and widespread anoxia, basically smothering the coral reefs and river ecosystems that held the bulk of Earth's biodiversity at this time, as well as a massive "cold snap" that resulted in a mass glaciation that killed most of the life in the oceans as well as on land. This is what wiped out *Dunkleosteus*, most of the earliest tetrapods like *Tiktaalk*, *Acanthostega*, and *Ichthyostega*, and (ironically) *Archaeopteris*, who became a victim of its own success. About 50% of all life on Earth was wiped out, and this was the event that basically created the modern world, wiping out a lot of previously dominant groups like placoderm and acanthodian fishes as well as being the death knell for the trilobites (who limped on into the Permian with a single family).
] |
[Question]
[
Most dragons (before Skyrim and GoT) had six limbs in total, four legs and a pair of wings.
The question is how would a dragon's forelimbs be placed? It's obvious they have good terrestrial capabilities, without having long noodle legs. But then there's the flight muscle, it needs lots of space and a large attachment site, same goes for the wings. But how should I put the front legs on the dragon so that it doesn't interfere with the wings' motion? Sure, those things only move during climb out, but it' still troubling. Whatever I choose should be compact.
**How and where would the front limbs of the dragon connect to the rest of the skeleton?**
[Answer]
Im not an avian biologists so i do not know if this configuration would be biomechanically sound, however it may prove to be some help to you.
[](https://i.stack.imgur.com/4VMqC.jpg)
*Credit to Christopher Stoll*
Shown here is a break down of the skin, muscle and bone layers of Toothless from the How to Train Your Dragon series. This image clearly depicts how and where the bones connect and where the muscle attatches to the skeleton. As i mentioned, i am not an avian biologist so i do not know if this setup would actually be functional in the real world, you may very well be able to draw inspiration from this though.
Edit: As you specified for an image containing the pectoralis, i found another one that depicts it.
[](https://i.stack.imgur.com/iLXRC.jpg)
<http://mythicalanimalscience.blogspot.com/2015/04/dragons.html>
[Answer]
**Split the forelimb.**
Making a 6 limbed creature from a tetrapod body plan is tricky. WB stack is littered with efforts on this front. Here is a new idea.
First, comparative skeletal anatomy.
[](https://i.stack.imgur.com/MKJgG.jpg)
<https://www.slideshare.net/OmerRasool1/comparative-anatomy-skeletal-system-71723331>
Look at the whale. Now imagine splitting the distal forelimb into two limbs: one with the radius as core and the other with the ulna. The radius and associated digits (5 at baseline but you can add more digits; polydactyly is fine) becomes the robust wing, availing itself of the scapula and other support structures.
The ulna also has digits and is much less robust. It would not be a stocky limb to match the hindlimb but something more like a Tyrannosaurus. These small forelimbs would touch the ground and allow ambulation but for fast motion they are not the equal to the hind limbs.
Having powerful back legs, powerful wings and spindly forelimbs means these dragons would not look like Toothless or Smaug.
1. Running at speed would be bipedal. The dragon would rear up and run like a bird. Wings might be used while running for propulsion or to jump. Some people think this use is how birds evolved wings in the first place.
2. The small front limbs would lend themselves to more delicate manipulation. Dragons could sit up and have a smoke, or play cards.
3. Front limbs might move during flight because they retain a connection to the humerus. Probably it would be some sort of rhythmic movement mirroring the wings.
4. In general I think dragons are depicted as too robust. I picture this dragon as along the lines of a crane.
[Answer]
The problem with wings is the necessary amount of power to lift the creature.
This is a bird skeleton:
[](https://i.stack.imgur.com/FtXvo.jpg)
Note the size of the sternum (the bone that all your ribs connect to). It's massive in comparison to ours and stands far out of the chest while a human sternum is basically flat in comparison. This sternum is what your pectoralis major muscles are attached to (the chest muscles).
The sheer size is because the muscles attached to it, shown here:
[](https://i.stack.imgur.com/k7oXV.jpg)
These absolutely humongous muscles are required to lift the weight of the entire creature up in the air, and the larger the bird the more % of the bird must be pectoralis major muscles just to keep it in the air due to the square cube law, but you can ignore this for the sake of cool. Despite this suspension of belief on the part of the square cube law you still want a bodyplan that can handle 4 paws and 2 wings simultaneously.
Note how these skeletons lack a large scapula. In the first picture you can see it mentioned but it's tiny and largely immobilized because everything is focused on that up/down movement of the arms, not about reaching forwards, backwards, upwards or downwards.
Having to have muscles attached to the chest for these extra appandages would diminish the amount of muscles for your wings. You could slightly circumvent this through kinematic chains.
An example of a kinematic chain is your quadriceps of your leg, or any other muscle that moves over more than 1 joint in the body. If you have muscles pull on one end of the bone they are attached to, you can use that to pull on the quadriceps, the quadriceps us that to pull on the muscle one joint removed, allowing you to transfer the muscle power from one bodypart to another. You attach a portion of the pectoralis major muscles to the dragon's leg, and have muscles above it attached to the wing (likely an adapted version of the triceps, romboideus, one part of the deloideus and trapezius). When flying the leg will be pulled down in the same motion as the wings and the muscles above that will simultaneously pull on the wings, allowing you to transfer the muscle power that went into the leg into the wing as well. This isn't wildly efficient and would likely make the leg flop up and down with the wingbeats, but it's an option. Ofcourse if you time it right and pull just as hard on the leg as on the wings, the leg would effectively keep still during flight. Although you'd be better off pulling it in as it would stretch the muscles above it and with that pull the wings.
[Answer]
Any depiction by Larry Elmore should suffice. More like angles; their forelegs are actually arms, and the wings protrude from their back, beginning just below the shoulder blades.
[](https://i.stack.imgur.com/86uVF.jpg)
*Dragonlance*'s blue dragon, [Skie](http://fantasy-faction.com/2011/larry-elmore-artist-spotlight), as pictured by Larry Elmore in the original cover art for, *Dragons of Winter Night*.
] |
[Question]
[
I am working on an extraterrestrial class of tetrapod-like organisms. To give them an evolutionary advantage, I am considering biological hydraulics to supplement the muscles in the hind legs. Eventually I may ask about more mechanisms, but currently, I am investigating whether or not this would even be worth the energy.
The class comes in a similar size range to land mammals, with the smallest weighing about two grams and the largest at around twenty tonnes. Of course in some species, the hydraulics could have become an obsolete trait. Some things the entire order has in common are:
* Four chambered heart
* Warm blood
* A closed circulatory and a separate closed lymphatic-like system
* A two chambered lymphatic heart-like organ below the true heart to pump lymph
* Small, rigid lungs with a unidirectional pattern of breathing
* Four respiratory airsacs
* Endoskeleton with four limbs, a skull, and one to two tails
The basic design is the circulatory or lymphatic system functioning as storage for hydraulic fluid. The blood or lymph will then be forced via muscle contractions into closed chambers in the thigh to push the limb when required. I am also considering using a separate fluid stored in the abdomen, but less so because of the loss of space to other organs.
Would hydraulics systems help the creatures survive, or would they be a waste of energy?
[Answer]
**Velvet worms are terrestrial animals that use hydraulic legs. Model your creature on them.**
[](https://i.stack.imgur.com/hj5PN.jpg)
<http://www.abc.net.au/science/articles/2011/09/05/3306983.htm>
[](https://i.stack.imgur.com/50TfF.jpg)
[Periodic Tables Unifying Living Organisms at the Molecular Level:The Predictive Power of the Law of PeriodicityNov 8, 2017
by Antonio Lima-de-Faria](https://books.google.com/books?id=lUNBDwAAQBAJ&pg=PA107&lpg=PA107&dq=VELVET+WORM+HYDRAULIC&source=bl&ots=ybZdJVUwbv&sig=cCdccpDQGF02UY23qgP7azmdDJ4&hl=en&sa=X&ved=0ahUKEwjGkbaPsPLaAhVW_oMKHVgKCYwQ6AEIczAL#v=onepage&q=VELVET%20WORM%20HYDRAULIC&f=false)
Velvet worms have legs but do not have a skeleton. All of the functions of the skeleton are done via hydraulics.
If you are dead set that your creature will have an endoskeleton, hydraulic appendages are still very much an option. You may be familiar with a method vertebrates (including humans) use to produce a temporarily rigid organ using only hydraulic pressure.
[Answer]
I just want to address the method you've suggested for the hydraulics. I realize this is an old post but if anyone else stumbles upon this like I have perhaps this will be useful.
Lymph is definitely a realistic fluid to drive hydraulics. In fact, a kind of tuna has been found to use exactly that (<https://news.stanford.edu/press-releases/2017/07/20/tuna-fin-movemenydraulic-systems/>). However, I'm not sure you completely understand what lymph is and how it moves through the body. Lymph is not a closed, cyclical system like blood is, and therefore having a heart-like organ to move it probably wouldn't work. Lymph is excess interstitial fluid (the fluid between cells) that slowly gets pulled through the lymphatic vessels to drain back into the bloodstream.
I'm certainly not saying that these creatures couldn't have a new closed-system fluid to power the hydraulics, just noting that lymph is not closed-system.
It also strikes me that it would be quite difficult for a twenty-tonne animal to generate any relevant levels of force with hydraulics. Spiders and velvet worms (the examples given in some of the comments above) are very light, and tuna aren't attempting to support any kind of propulsion with hydraulics. I won't say that it's impossible, but I'd suggest significant further research to figure out if meaningful hydraulics would be possible for such a large animal.
I hope this sheds some more light on the subject for anyone who comes across this question.
[Answer]
Thinking about this, its hard for me to see any kind of evolutionary pressure that would push a species to evolve hydraulics rather than normal muscle. There are some disadvantages to hydraulic systems of movement, like how any damage to the pressure system for the hydraulics nullifies any possibly movement from that system, meanwhile, muscle fibers can be damaged but the other muscles around them can still work fine.
There is one possibility i can think of though, and that is stored pressure in a highly accurate package. This is the idea:
Lets say that there is a predatory species that lives in a habitat where many of their prey stay hidden underground. Firstly, the evolution of highly sensitive feet parts to sense the vibrations underground may help them to locate prey, and later on, instead of having to dig for the prey carefully, trying not to alert the prey to run off somewhere else in their underground maze, the species may have evolved to very accurately locate where prey is underground, and uses the precise linear movement of a hydraulic appendage, they can line themself up, put a lot of hydraulic pressure into the appendage, storing the energy, and finally, releasing all the force quickly and accurately, stabbing underground and grabbing hold of its prey before it even knows its being hunted.
[Answer]
Natural selection works via two ways, selection for survival and sex selection (think peacock tail feathers which have no survival value except, maybe, weeding out those too weak to compensate for all the disadvantages of it).
Translation, things can and do evolve that aren't energy efficient if there is selection pressure for it.
] |
[Question]
[
I was watching Shoddycast's video on the value of bottle caps as currency in *Fallout 4* today, and after having read part of Brandon Sanderson's *Words of Radiance* earlier this morning, my mind started to wander to the possibilities of currency far stranger than either bottle caps or the Stormlight-infused glass "spheres" with gemstones inside them seen throughout Roshar. Is it possible for food or organic materials and animal byproducts to be used as a practical currency?
Which leads me, of course, to slimes and honey. Honey is sweet, nutrient dense, and has a very long shelf-life. And slimes are the quintessential fantasy trash mob. Why not combine the two, and make honey (or perhaps some sort of similarly sticky-sweet "slime milk" or gel) the common currency of a fantasy world where these creatures exist? By themselves, they already fulfill many of the qualities of a good currency according to the definitions set by the Shoddycast video:
-They are "shelf-stable" (honey lasts a long, long time, and presumably so does slime)
-They are rare, but not too rare (since slimes are wild monsters and must be killed to harvest their byproducts)
-They're easy to identify (usually because they're brightly colored and, indeed, slimey)
-They're hard to fake (taking into account their distinct color, taste and texture compared to other foods and animal byproducts)
However, the problems I'm seeing are that slimes fail in a few other major categories. They aren't easy to carry around or turn into money (you can melt metal into coins but what do you do with a blob of slime?).
While slimes aren't usually considered good livestock or farm animals in most fantasy settings. The possibility of someone attempting slime farming or someone stumbling into a huge number of slimes at once in the wild makes runaway inflation a distinct possibility. Unlike metal or minerals, which tend to be a finite resource, organic materials like honey or a slime's slime can always be reproduced in large quantities after loss or consumption. Such is their nature.
Are there any ways to deal with these problems that could justify honey or slime as a practical currency, or will metal and gemstones always be a better "store of value" than organic materials?
[Answer]
OK, "organic materials" certainly *can* be currency -- paper money is made of an organic material.
But you're asking that the honey be used as some sort of [specie](http://en.wikipedia.org/wiki/Specie) - specifically a type of [commodity money](http://en.wikipedia.org/wiki/Commodity_money). The answer is "yes".
What is the key ingredient in honey? Sugar. Sugar has a long history in the development of Western European colonial empires (and the spread of slavery). (If you haven't read *[Sweetness and Power](http://books.google.com/books/about/Sweetness_and_Power.html?id=_pefwak9cPAC)* by Sidney W. Mintz, you should.) In the 17th and 18th Centuries, refined sugar was a rare luxury item that was locked away to keep the servants from nicking it, or even getting a taste.
*[The Sugar Barons: Family, Corruption, Empire, and War in the West Indies](https://books.google.com/books?id=C5XtCAAAQBAJ&pg=PA34&lpg=PA34&dq="sugar+as+currency")* by Matthew Parker describes situations where colonial planters, far from home and a ready supply of coinage, used their own product (tobacco, indigo, sugar, whatever they produced at the time) in exchange for the goods they wanted. If metals are so rare in your world as to be impractical for use even as tokens, they might pick a commodity as currency.
But even in that case, people might find a way to make an abstract specie. In colonial New England, English settlers used [Wampum](https://en.wikipedia.org/wiki/Wampum) as currency to trade with Native Americans. In Larry Niven and David Gerrold's 1971 novel *[The Flying Sorcerers](http://en.wikipedia.org/wiki/The_Flying_Sorcerers)*, the rapidly industrializing natives adopt slices of bone as currency.
The difficulty of transporting honey can be overcome -- [this blog by beekeeping enthusiasts](http://blog.beeraw.com/real-raw-honey-crystal) talks about the advantages of crystallized honey. So your world's people could trade blocks of "rock candy" derived from honey. A little more problematic is standardization -- "Honey Money" could be measured by weight or have standardized block sizes, but then someone would have to monitor quality and that means refining the honey in a more complicated way, which would lead to industrialization.
But I think you're going to have to deal with some ugly social consequences of using honey or "slime milk" as currency. Funny things happen to people around lots of money, and the "slime milk" producers would have all of it.
I won't delve into all of the ills of the Era of Colonization or the Industrial Revolution it generated; you can take them for granted.
Even if you're using "slimes" (I pray they aren't sentient!) instead of bees, they aren't going to remain "wild monsters" for very long. Slimes would soon be extinct in the wild -- they will all be rounded up and kept where the rich and powerful can breed and harvest the slimes for filthy lucre, keeping the slime-milk to themselves.
[Answer]
The way this sort of thing usually works out is:
1. So, hey, you like honey (or gold or silver or whatever) and I like honey, so how about I start paying you my rent with barrels of honey. Everyone is happy with this. For a while.
2. Yeah actually moving all these barrels of honey around all the time is sort of a big pain for everyone. How about I give you this letter which states that you own these barrels of honey over here, and you can come pick them up whenever you want?
If everyone agrees to that, you now have a honey-backed currency. If everyone agrees that one buckaroo is worth a pound of honey, you're now on the Honey Standard.
3. It turns out that hardly anyone is actually coming over here to turn over their buckaroos for pounds of actual honey, so... tell you what. I promise to keep enough honey around so that if, oh, ten percent of all the buckaroos out there suddenly need to get converted back into honey, then I'll be able to cover that.
Now we're moving off the Honey Standard. This will deeply-upset everyone in the business of producing honey and probably also upset other assorted random weirdos, but a lot of people won't care.
4. Gather round, children, and let old Great-Grandpappy tell you the story of why that money in your pocket is nicknamed 'the sweetback.'
Eventually everyone just comes to agree it's obsolete and most people forget about it.
[Answer]
>
> They aren't easy to carry around or turn into money
>
>
>
[Not a problem.](https://worldbuilding.stackexchange.com/a/123323/21222)
>
> Yap is known for its stone money, known as Rai, or Fei,: large doughnut-shaped, carved disks of (usually) calcite, up to 4 m (12 ft) in diameter (most are much smaller). The smallest can be as little as 3.5 centimetres (1.4 in) in diameter. Rai, or stone money (Yapese: raay), are more than 6,000 large, circular stone disks carved out of limestone formed from aragonite and calcite crystals. Rai stones were quarried on several of the Micronesian islands, mainly Palau, but briefly on Guam as well, and transported for use as money to the island of Yap. They have been used in trade by the Yapese as a form of currency.
>
>
> The monetary system of Yap relies on an oral history of ownership. **Because these stones are too large to move, buying an item with one simply involves agreeing that the ownership has changed. As long as the transaction is recorded in the oral history, it will now be owned by the person to whom it is passed and no physical movement of the stone is required.**
>
>
>
And from my answer in the link:
>
> There is even one such stone that is in the bottom of the ocea due to a shipwreck. Legend goes that the owners kept using that stone for trade anyway, trusting that oral tradition would keep honoring the transactions involving the lost stone.
>
>
> These stones are often cited when someone wants to make a point that nearly anything can be used as currency provided that a set of requirements are met. Anyway, if stone will do, so will concrete.
>
>
>
As you see, carriability is not a problem when considering materials for currency.
---
>
> The possibility of someone attempting slime farming or someone stumbling into a huge number of slimes at once in the wild makes runaway inflation a distinct possibility.
>
>
>
Yes.
But consider Bitcoin. The amount of Bitcoin only increases with time (and will increase until the last bitcoin has been mined).
Also consider that in the past, people would use animals and grain as currency. There is a limit to how much you can farm of animals or plants, so that will cap inflation.
[Answer]
**Honey would be a poor choice for currency.**
The problem of adulterated honey is a [big problem today](https://www.forbes.com/sites/larryolmsted/2016/07/15/exclusive-book-excerpt-honey-is-worlds-third-most-faked-food/#65a257774f09), even without designating it as currency.
Chemically, honey and high-fructose corn syrup are very similar. Add some additional chemicals and coloring and you have fake honey that is not easily detected. If you don't care whether honey or HFCS are essentially equivalent currency, I suppose you could ignore this objection.
] |
[Question]
[
The species here has three possible genders, "A", "B" and "C" (for simplicity's sake). Each of the three genders can mate with another gender, producing the third gender. In other words, A and B reproduce to form C, B and C together make A, and A and C together form B.
However, it's a little more complicated than that. Like males, the "A" gender does not have a womb and cannot become pregnant, while "B" and "C" both have the capacity to become pregnant. So when "A" and "B" mate, "B" will be pregnant for a few months before giving birth, while "A" is able to continue to reproduce with others. On the other hand, when "B" and "C" mate, either one or both of them become pregnant and bear children (the genes would not be identical), and thus one or two of them would be unable to breed for months at a time. This means that "B" and "C" both have a gene-delivery system (like a penis).
With this in mind:
* What sort of social structures and mating habits could develop?
* Would monogamous relationships be dominant, or would something different develop?
* Are members of the species likely to mate with the same gender across the board, or will they switch around?
* Will population/distributions of the different genders remain approximately equal, or will inequalities/eventual extinction occur?
[Answer]
This is a really interesting species to think about. Since the problem isn't easily done in the mind, I did some agent-based modeling to see what would happen. A more extensive write-up of that question can be found on [WorldBuilding's blog on Medium.com](https://medium.com/@deeprgreen/the-three-sexes-problem-ef25c62363b8#.7qeuopwys).
**My primary finding was that the ratio of sexes in this species are susceptible to wild oscillations.** In a starting population of just 20 where half of those individuals were As, within 100 years (or the 5th generation) the As wildly outnumbered the Bs and Cs combined.
[](https://i.stack.imgur.com/b1qWe.png)
If the As are in any way more aggressive then Bs or Cs then a war is going to breakout or something. In normal duo-sexual species, a 20% preference for males over females has a profound impact on practically every aspect of society. Ask China how that worked out for them. A more balanced set of sexes in the initial population lead to decreased or no oscillations in the sex ratio.
**Will population/distributions of the different genders remain approximately equal, or will inequalities/eventual extinction occur?**
This species is very sensitive to ratios in the sexes. If there are significantly more of one sex than any other then wild oscillations in sex ratios result. The population won't die out immediately if all As die because the As can be brought back by the Bs and Cs. However, this means that while all those As are growing up, there aren't any Bs or Cs being born either. Because of the deterministic way that the sex of an individual is determined, these oscillations may be inevitable without any kind of dampening social or environmental pressure.
**What sort of social structures and mating habits could develop?**
Social structures and mating habits would evolve to provide damping forces on the oscillations because a run away growth of a single gender over the others will have huge repercussions for decades, if not centuries. The species may develop a built in knowledge that sometimes, an individual isn't going to be able to mate because doing so will exacerbate a significant problem.
**Would monogamous relationships be dominant, or would something different develop?**
I think there would a tendency away from monogamous relations as that would enhance any sex ratio oscillations.
**Are members of the species likely to mate with the same gender across the board, or will they switch around?**
They will likely switch around to dampen any oscillations or form up in tri-sexual families to ensure that all three sexes can be produced.
Note that an individual's sex refers to their biological state while gender refers to any social roles that an individual may fulfill.
[Answer]
>
> * What sort of social structures and mating habits could develop?
> * Would monogamous relationships be dominant, or would something different develop?
>
>
>
Note the extreme variability to these answers even in a two-sexed environment. There's no reason to suppose three sexes would suddenly get less complex.
>
> * Are members of the species likely to mate with the same gender across the board, or will they switch around?
>
>
>
Given the number of homosexuals in existence today, when homosexuality makes next to zero sense\* from an evolutionary standpoint, I imagine there would be hugely different sexual preferences between members of a three-sexed species when those preferences can actually be useful in the selection algorithm.
>
> * Will population/distributions of the different genders remain approximately equal, or will inequalities/eventual extinction occur?
>
>
>
It's hard to say, but my gut feeling is that, for any given population, one of the sexes would end up being less preferred by the other two sexes, and would therefore eventually go extinct. This would take quite a bit of time, but I think it would eventually happen.
Note that a different sex might go extinct in a different population group, and there's no particular way to determine in advance which sexes would dominate in any particular group.
The only way to keep a sex from going extinct is if all three sexes are required to reproduce. For example, maybe A and B need to mate to produce one half of an embryo, then B and C mate to finalize the embryo. In this case, either selection will find a way to bypass one of the sexes (who will then go extinct), or all three sexes will remain part of a stable population.
As for the proportions, I don't know. It doesn't make a lot of sense to me that there are so many males. One male can easily keep dozens of females pregnant, but somehow nature decided a 50:50 ratio was better. The answer seems to be that males have a selection bias\*\*, so couples with more male children produce more grandchildren, so despite the lack of "need", more males are produced anyways. Obviously the answer is somewhat complex, but if that rationale holds for three sexes, the ratio would likely be even as long as all three sexes are required.
\*My best guess, which Google says is some other people's best guess, is that either: having homosexuals around helps the rest of the population's sexual fitness somehow and therefore populations with gay genes thrive better than populations without, or: something that makes people more sexually fit happens to occasionally make gay people, and the added fitness to other people outweighs the reduced fitness of gay people. Or some combination of both. [Source](http://www.queerty.com/three-reasons-homosexuality-is-not-a-choice-and-that-gay-men-exist-and-one-myth-20150309) -- warning, scantily-clad men, possibly NSFW.
\*\*[Source](http://www.livescience.com/33491-male-female-sex-ratio.html) -- warning, naked baby covered in ick, possibly weird and/or NSFW.)
[Answer]
The questions you are asking do not have fixed answers. A lot of sexual psychology has to do with what people/creatures *like* to do. As such, you are free to tweak the preferences of your characters the way you want. Here in our world, you cannot define why some people like homosexual lifestyle over heterosexual or vice versa. It all goes with personal choice.
As for whether races would be monogamist or poly, this depends not only on sexual preferences but also on the economy structure of the family and the physical strength of the genders. It also depends on which gender has more outdoors exposure (males in our society) than the others.
So all in all, the world you are creating is yours to create. You can make one gender very much prized by the other genders (maybe because there are few of them and bearing a child of this gender takes more time and there is a huge chance of infant fatality for this gender). You can put homosexual traits in the genders (varying according to your choice). Your system of 3 genders does not naturally place confines or create social/family structures in itself. Things are a lot more complicated than that, and a **lot** goes to personal choices and social structures.
] |
[Question]
[
The purpose of the machine was obvious from the elegant cruelty of its design:
* The seat restraints and the seat's solid, one-piece, gold-colored metal structure made it clear that whatever it did, was intended to be done against the initial will of those subjected to it.
* There was an eldritch mass of writhing, thin silvery coils and tentacles situated at head height that somehow suggested this would be a *very invasive* procedure.
* The transparent, yet seemingly sound-proof spherical casing placed around the seat indicated that during its active state the patient is very unlikely to be quiet.
[](https://i.stack.imgur.com/8cuZx.png)
>
> [**Rynn**](https://worldbuilding.stackexchange.com/questions/12990/a-most-subtle-magic)'s new friend walked around the sphere, gazing inside. She
> shuddered, and looked back at Rynn.
>
>
> "*How ghastly*," Rynn said.
>
>
> "*Don't your amulets do much the same thing? Make people see you
> bathed in an aura of goodness and purity, interpret your words and
> actions in the best possible way?*"
>
>
> "*Haha*," Rynn laughed. Alice
> couldn't help noticing the laugh was **warm** and the voice
> **crystalline**. Rynn's brief, wide smile was the **embodiment of good-will**, in a strange dissonance with the torture chamber they
> were in. Apparently, the amulets worked perfectly well even when
> you were aware of them.
>
>
> "*Perhaps they do, but in a passive way, unlike this kludgy
> thing*," she continued. "*I mean: Tentacles that burrow into the
> skull? Rather unsubtle and primitive, is it not?*"
>
>
> "*Effective enough nonetheless, based on what we saw outside.*"
>
>
> Rynn nodded, somberly.
>
>
>
---
**How would an indoctrination (also known as brainwashing, mind control, coercive persuasion) device actually work? Can such a device even exist? For the purpose of this exercise I refer to the 'unsubtle' version:**
* Intensive use can turn a sworn enemy into an adoring (slavish even) friend, or (bonus level) plant a false idea or memory firmly inside one's mind as unquestionable truth.
* The effects, once in place, are permanent absent other later strong(er) stimuli.
* This may (or may not) damage the subject in physical and neuro-permanent ways.
* It would work by known physical principles or reasonable extensions and interpolations thereof (no magic or psycho-babble), such as (but not necessarily) by acting on the pain and pleasure centers.
* More specific, detailed answers will get my upvotes.
[Answer]
Most of the answers so far involve some variant of torture, conditioning, or dependence. But these are crude techniques, developed by people who can only batter on the vessel which carries the mind. When you can access the mind itself, a more subtle technique may be employed...
---
>
> Alice circled once more around the device.
>
>
> "Have you figure out how it works?" Alice detected the slightest amount of impatience in Rynn's voice. As usual, she was doing a good job of hiding it.
>
>
> "Not yet. But there's *something*..." She trailed off. Although she had never seen anything like it before, it was familiar to her. But there was nothing useful there, just a sense of déjà vu—or a half-forgotten *memory*. The image of a [**wolf**](https://worldbuilding.stackexchange.com/questions/11252/how-to-catch-a-dream-thief) flashed through her mind...
>
>
>
The human brain is an amazing organ, but is fundamentally very simple. Beyond the base instincts, there is only one function that the brain performs: the identification and recall of patterns.
Even our very memories are stored, not as a concrete sequence of images, but as a loose association of sensations. This *compression* is what makes our brain so powerful. If I asked you to recall this morning's breakfast, your brain uses the few salient facts it has stored to reconstruct the experience in your mind. Any detail that you wish to remember is recreated for you to inspect *post facto*.
But this is also the weakness of the brain. Invariably it is impossible to recall every detail of your experience. Your brain mixes together associated memories, and [fabricates outright](http://en.wikipedia.org/wiki/False_memory) what it needs to. The brain is quite easy to fool, and while the [methods it uses](http://en.wikipedia.org/wiki/Heuristic#Theorized_psychological_heuristics) are often good enough, they fail [surprisingly often](http://en.wikipedia.org/wiki/List_of_cognitive_biases) and in predictable ways.
---
>
> "Alice, talk to me!" After seeing the look on Alice's face, Rynn was no longer bothering to control her voice. She knew that Alice had realized what the device was.
>
>
> Alice knew eventually someone would figure out how to duplicate the effect. But not this *fast*! Something like this should have taken decades to produce. "Rynn, I've seen this tech before, but not on this *scale.* The things they could do with this are... unimaginable. The things they've *done* with this..."
>
>
> "Could be worse than we ever imagined." Rynn nodded her head gravely. There was only one thing to be done...
>
>
>
The Mære Wolf performs a type of remote side-channel attack on the brain. Through careful external manipulation of the victim's emotional state, the brain is induced to **recall** important memories and then **associate** them with the nightmare.
However, with access to a system's hardware, a low-level **reformatting** can be achieved. Alterations are no longer limited to memories: other, more permanent associations can be accessed and changed.
The first thing the device does as it burrows into the subject's skull is to administer an **anesthetic**. For its work, pain will only be a hindrance. The next chemical it releases is a memory blocker that induces **anterograde amnesia**, to prevent any forming memories from interfering with the procedure.
Next, the device performs a **sensory probe.** Although each brain stores memories in the same way, the specific workings of the memory system develop uniquely in each individual. Since everything in the brain is stored as an **association**, the device must learn the subject's unique sensory association map.
This is when the real work begins. The device can now make *any* desired change to the subject's memory and beliefs. For example, let's say that the device is used to turn Alice against Rynn. First, it will find the sensory patterns associated with Rynn, and present those to Alice's brain. It will then induce her brain to traverse all of the feelings and memories associated with that sensory pattern, breaking those associations one by one. Then it will begin to add a new set of associations. Among others, it will associate the sound of Rynn's name with hatred, and the sight of her face with revulsion. It will add memories of people telling Alice of Rynn's evil deeds, and of Rynn killing Alice's parents in front of her eyes. Finally, it will associate *Rynn* with **enemy**, and this will an absolute truth in Alice's new mind.
The key that makes this possible is the recall mechanism of the brain. The device will simulate Alice's brain to access a memory, and present the barest outline of the desired memory: *"Rynn killing my parents."* The brain will then fabricate details associated with that memory (*"The blood-soaked knife plunging into Mother's chest again and again"*), which will be fed back into the brain until a complete set of sensory information is produced. This false memory is then fed into the memory mechanisms of the brain, which store the memory alongside real ones. A similar mechanism allows the device to add and remove learned facts (including the subject's worldview and core beliefs), as well as to teach and erase skills.
Finally, as the device withdraws it heals the entry wounds it caused and induces a sleep state into the subject. This allows them to be removed from the device and placed into their new life, where they will awake in now-familiar surroundings.
---
>
> "See now how the tables have turned! If you only knew how long I waited for this moment, the pain you have caused me, you would thank me for *merely ending your life!*" The figure bellowed as his blade plunged towards Alice, missing her by a fraction.
>
>
> "Daz, what are you talking about! It's me, Alice—don't you remember?" She struggled to parry his blows. Her bewildered mind could barely register the fact that Daz could barely lift a blade the last time she saw him, but now he was definitely going to kill her.
>
>
> "Remember? *Remember?*" Daz laughed as he struck Alice, sending her sprawling on the ground. "Do I remember the one who betrayed me? The one who made me *suffer* for all those years? Do I remember!" He raised his hands for the killing stroke. "Whatever trick this is, it will not save you now!"
>
>
> Alice instinctively raised her arm across her face, even though she knew that this was the end. But then something happened: one of the coincidences that she had gotten used to seeing in the past two weeks. She saw, as if in slow motion, the tip of Daz's blade glancing off the device's smooth crystal enclosure. Horrified, she watched as the sword bounced back and embedded itself in Daz's skull.
>
>
> She ran forward to hold the crumpled body of her childhood friend, ignoring the spray of blood that soaked her clothes. Turning away from his ruined face to look at Rynn, she spat out, "You! Why did you do that? He was... he was..." She buried her face in his shoulder and began to sob gently.
>
>
> "There was nothing more that could be done for him." Rynn grabbed Alice with both hands and turned her away from the body. Looking into her eyes, Rynn said, "His mind was already gone. All that was left was his body." Rynn had to use all of her powers to calm Alice's mind. "Now you've seen what this device can do. Now you know why it has to be destroyed..."
>
>
>
[Answer]
This is both simple and terrifying, but you nailed it in your question:
>
> such as (but not necessarily) by acting on the pain and pleasure centers.
>
>
>
We're using [Operant Conditioning](http://en.wikipedia.org/wiki/Operant_conditioning).
The device burrows into the skull. It then does the following:
1. Allows the target's current thoughts to be read.
2. Accesses and is able to stimulate both the pleasure and pain centers of the brain. As a bonus, include others (so making someone feel extreme cold or heat, vertigo, etc) - this allows you to tailor your treatment more closely to the target and the desired effect.
3. Allows you to control the target's senses - you can make them see/hear/feel/taste/smell what you want them to, basically this is VR.
**Basic Conditioning:**
1. Inject a memory of the target doing things you want (following orders, killing their friends). Combine this with stimulating pleasure.
2. Inject a memory of the target doing things you don't want (disobeying you, saving their king from an assassin, etc). Combine this with stimulating pain.
3. Go back to 1 and repeat constantly for 1-2 days.
Now bring them into a VR simulation. Put them back into those situations, but let them act however they wish. If they do what they're supposed to, you simulate pleasure. If they don't, you simulate pain. As soon as they switch, the stimulus switches (so if they start to disobey, but then do what they're told, the pain goes away and is replaced with pleasure).
They're now conditioned to associate the things you want with pleasure, and the things you don't want with pain. Do this enough and they will have an instinctive, gut reaction to act the way they want - they literally won't be able to help themselves.
For obvious reasons you can use this to create false memories as well since this puts the person effectively into VR.
**Beliefs:**
This is trickier, you will want to be more subtle and take more time about it. Instead of giving the target memories, you would instead ask them questions (interrogator style). Don't use pain at all here - instead, whenever they agree with you, or think along the lines you want, stimulate their pleasure centers at a very low level, enough that they just feel good but it's not obvious what you're doing. Over time this will be enough to shape their beliefs unnaturally the direction you want.
[Answer]
As Pavel says, brainwashing is a process. And it's a process that's been done already.
1995, Russia. The Cold War is over. Boris Yeltsin in power. There is some resentment left over from the Cold War, but generally people are starting to see Russia in a better light: they didn't, after all, nuke the lot of us, and OK there might be some good things about them.
Wait. *There is some resentment left over from the Cold War*. **Why?**
During the Cold War, there was a period known as the Red Scare. It was caused by what was, essentially, a brainwash of the US population - the US government (under President Truman) distributed so much propaganda and gave such bad impressions of the Reds (Russians) that *people believed them*.
You can read more about the Red Scare [here](http://www.history.com/topics/cold-war/red-scare).
---
This is what brainwashing is. Not cold, metal devices. Not high technology. Not even shoving a gun to someone's head or beating them almost to death. Yet it's still brutal. It's still unsubtle. Nobody ever tried to hide the fact that the US government was saying that the Reds were poison; they shouted it from the rooftops. All that mattered was that *not the entire truth* was told.
All you need to brainwash someone is for them to trust you a bit. People didn't totally trust the US government, but they believed that what they were doing was right - they wouldn't just *lie* to all their people about an issue of national interest, would they?
That belief in you enables you to tell people things. And when you tell people things enough, they start to believe them. Now you have *two* people spreading your cause. And when each of them makes another believe them, you have 4. Then 8. Then 16. 32. 64. 128, 256,512,1024 2048 4096 and the cycle *keeps going*. You now have an army of people who believe what you believe, and because you opened their eyes to this new light, they revere you above others. And nobody's going to argue with that many people, are they? *Are they*?
Maybe, maybe not. Maybe eventually you'll get one doubter, and they'll start a revolution.
---
>
> Although Rynn's new friend - Alice - trusted her, Alice felt a sense of doubt hanging about this place. Rynn was changing people's perceptions, changing the way they looked at her and the world.
>
>
> "Alice? Are you coming?"
>
> "Give me a moment - I want to look at this thing," Alice called, indicating the machine.
>
> "Oh come *on*. Don't you believe me or something?"
>
> "Of course. Come on then."
>
>
> Alice hurried off with the strange young woman. She'd forgotten her doubts for now. But deep in her mind, the sliver of doubt took root - and began to grow.
>
>
>
[Answer]
(Pun intended)
Now on more serious note: **Indoctrination is a process**
Recently, I did read a story which had name *Keep washing your clothes:* During First World War, there were two opposing armies, being stuck in fortification. No one moves, no one shoots.
One weekend, there was music from opposite side. (say German). Then next happy music. Then voice: "Look. We are soldiers, you too. We are being stuck here for weeks, so lets officially cease fire and wash our clothes."
Soldiers from another side (say French) did not believe it at once, but then someone stood up and went to wash his clothes. Without being killed.
This was repeated for several weeks. Every weekend, there was happy music from German side and soldiers went to wash their clothes together.
When Germans really attacked, they faced little, to no defense, because French soldiers were already convinced that *these neat people would never ever do anything bad to us*
(Pun intended again)
Being from Czech Republic, some internet discussion under news articles are in mode: "What did these *sleazy Americans* do good to us? Do you see Putin? Strong, competent. Powerful. Russia and Czech used to be brothers. *Brothers,* dude." (And so on)
**You dont need elaborated device. What you DO need is elaborated process**
Do heroes think the villain holding them is ... well, *villain*? Spend some time in preparing them friendly welcome.
Show them your propaganda. Show them how *bad* they are. Bend reality in your favor. Let them accept it. And if they are humans, they will. Because it is pure human nature.
[Answer]
A more brutal, less subtle answer than the other ones:
That plastic shell isn't to dampen the sound of screaming, it's a **splatter guard**. The tentacles burrow into the brain, connecting to the spinal cord, optical nerve, and other nerves, then systematically determine which nerves correspond to which sensory stimuli and muscle movements via a procedure of methodical electrical stimulation. The brain itself is removed (washed away, as it were), and a computer is put inside the skull to replace it.
Fits your bullet points:
* Intensive use (all use is completely intensive) results in a friend who thinks exactly the way you programmed them to.
* The effects, once in place, are permanent absent replacement by another computer or brain.
* Definitely damages the subject in physical ways.
* Machines that interpret signals from the nervous system already exist.
[Answer]
*I always love working with Rynns, so I've been rather Rynn-centric in this one. It was fun choosing to push on her and see how she shifts the fates with careful words and powerful acts.*
"Beautiful, isn't it," boomed a voice from behind the two adventurers. Alice whirled around to find a cleanly shaven man, immaculately dressed. In his hands he held a glass of what looked to be a fine whiskey, its color accentuating the rims of his glasses with lightly smoked lenses. Rynn appeared to have already been facing him and stood there looking at the newcomer. Alice seethed in frustration, "does that woman ever actually have to turn around, or is she always facing the right direction in the first place?"
"My name is Matthews," he continued. "I've been eagerly looking forward to meeting you both." He looked at the bodies of the guards at the doorway, "you did not disappoint."
"You built this monstrosity?" Alice exclaimed. She drew herself a hair closer to a ready stance, square to Matthews with her full body ready to strike at any moment.
"Yes, I built this monstrosity, and a beautiful monstrosity she is, is she not? It is amazing what a decade of raw will can do to father an act of creation." He took a measured sip from his glass and let the liquid slosh around in his mouth before continuing. "It is so easy to create a knife which cuts deep to the soul, but much harder to sew the wound shut again in the shape of your pleasing."
Alice took these words as though an alien uttered them, an alien whom she would never understand because she didn't want to understand. "You treat the mind like it's a toy to be played with. Even if you had found the secret of alchemy, things like this," gesticulating towards the chair, "should be destroyed. They play with too great a power."
Matthews smiled widely, and almost bowed, "It is quite an accomplishment. Of course, I cannot claim to have discovered the secret of alchemy. I simply found another way to power." He slid over to the wall nearest him and smoothly pulled a brass lever. The wall parted and rose up to reveal a room behind it. In this room, amidst gleaming brass machinery, were hundreds upon hundreds of glass vessels, stacked to the ceiling. Each was full of flesh, twisted and tumorous. The machinery seemed to breathe and pulse, forcing life into the piles of flesh. Alice could hear screaming from them. No, that's not quite right. It wasn't "hearing" that she was doing. In some odd way, she *felt* them screaming. Agony, it was.
Alice looked to Rynn, whose smile had faded to a thin red line. Alice's thoughts suddenly spiraled out in front of her: "I've never felt anything like this before; it's overwhelming. But what about Rynn? She picks up all sorts of details like this. It must be utterly agonizing for her to look at them. I'm amazed she's still standing."
Matthews continued on. "This is the real heart of the machine. 973 individual containers of living matter, linked by machine. You see, the secret to brainwashing is simple, really. Every mind is different, and if you simply try to force your will onto it like a battering ram, each mind comes up with a different and ingenious way to keep you out. Even if you strike at the same mind repeatedly, each time it comes up with a new solution to repel the blow. However, offer a place for the mind to grow, and it happily reveals its secrets, including the nature of its own defenses. We simply, oh, what's a good word for it.... 'inspire' these containers to be receptive to any mind and wait for the secrets to come to us."
Rynn spoke for the first time since his arrival, her voice calm, but measured. "If each mind thinks differently, as you say, it would take a very long time to teach your 'creation' how to understand our thoughts. This machine does it quickly, so I assume you're trading off size for speed. It seems difficult to store a whole mind in here. It's too small of a room. Only a fraction would fit."
"That is the true joy of my creation. I don't have to integrate with the whole mind at once. People's minds are built in layers. It's how they can stand back up again after someone knocked them down. They simply dig deeper and rise up again. They're marvelous creatures, really." Matthews had grown excited, sharing his work with others. His glass now rested on a table next to the machine's controls, and he was gesticulating to emphasize his points. "All we must do is provide sufficient... stimulation to encourage a clean break between the layers, then she integrates with the outermost layer. Once that is complete, we can simply siphon away the essence of that layer to be put back later, flush her containers again, and begin on the next layer. Once we are done, it's just a matter of using her to help put the layers back, one by one."
"And if the machine were overwhelmed by trying to chew off too big a layer?" Rynn looked skeptical, but Alice swore she heard something in her voice. There was something in her intonation that was cloyingly familiar to Alice. She'd heard it used before. She just couldn't put a finger on it. It was pushing, in a sense. Forcing. But if she hadn't been working with Rynn recently, she'd have never noticed.
"That, my dear, is where the power of statistics comes in. We measured countless minds, stripping thousands upon thousands of layers. My creation is sized sufficiently that I'm more likely to find the alchemist's stone itself than find a mind that can't be set upon by my machine. There are always edges in a person's mind to grasp, and we can find them!" He turned to stare directly at Rynn through his smoke-tinted glasses, "Why, I'd bet even you would submit to this machine in no more than 10 minutes' time."
Alice immediately raised her weapon to fully ready, crouching slightly ready to spring at Matthews' throat. He chuckled, "Relax. If I had wanted you put in the machine by force, I would have done it while I still had an army at my beck and call. Think of it more as a challenge, from one creative force to another. We are kindred spirits, trying to make sense of the world and make it suit our purposes. See what I have created. Experience it."
Rynn walked over to the window into the room crammed to the brim with containers. She touched one of them lightly. She held her finger on it for a moment, perhaps two, then pulled back quickly but controlled. Was there a purring noise from the vat as she touched it? Hallucinated sensations can be so hard to evaluate, thought Alice.
"You don't need to brainwash me. If all you care about is a strong mind to test your machine against, there are plenty of others. Why bother focusing on me at all?"
"You are right," he boomed, "but you are here, so it seems like you would be the best candidate for the job. What do you say? I know you are special. Are you up for testing what you are made of?" Rynn did not respond.
Matthews paused for a bit, picked up his whiskey glass and turned to Alice, "Tell ya what: how about I sweeten the deal. I know Rynn wouldn't be interested in a trade for information, but you just might be. It's amazing the things you learn when shucking minds is your occupation. You'd be amazed at how much your parents wished they could have told you, but never got the chance. Think of what I might be able to tell you, if only she gave my creation a try." He raised his glass in her direction.
Alice was electrified. Until now, the focus had been on Rynn and Rynn alone. Rynn remained cool, calm, and...well... Rynn. Now the attention was on her. Matthews's stare was infectious. She almost felt the excitement of discovery flowing from his eyes through the smoked lenses. Instinctively she began calming exercises, but every adventurer knows the one place those exercises don't work is the place you need them to work.
Rynn rescued her, "So you want a strong mind to test the mettle of your machine, and you're willing to offer Alice information you think she might be interested in, regardless of the result of the test?" Matthews smiled and nodded.
Rynn said nothing more to him. She walked up to the machine and sat down. Matthews deftly hooked up several electrodes and hypodermic needles, then shimmied to the control panel like an excited child running off to his tree fort.
Alice looked at Rynn, then at Matthews, then back at Rynn. She swore she saw just a flash of a smile. Thinking back, she almost even remembered feeling the vats stop screaming and smile too. It wasn't for long: just a split second before Matthews flipped a switch and sent the vats into indescribable wracking pain.
---
Rynn stepped down from the machine. It wasn't quite a stagger, but it was certainly not Rynn's usual level of grace in movement. She took a few steps towards Alice, and rested a hand on her shoulder. Rynn's breath was calm, but it felt like that was the only calm part left in her. The rest of her moved like strands of a wire flexed one too many times.
"What now?" asked Alice. She looked over at Matthews standing rigid next to the control panel, knife against his own throat. He quivered slightly, but other than that, he dared not move. "What are you going to do with him?"
"I'm not going to do anything. He's not mine to deal with. He's yours." Alice frowned in confusion at Rynn's words. Rynn continued, "If I had tried to control his mind while in that machine, he'd have felt it and stopped it. He's no fool, and his attention was completely devoted towards me. I had no opportunity. You, however, you did have the opportunity. He wasn't paying as much attention to you as he was to me."
"But, I didn't do anything. He wasn't even hooked up to the machine!"
"Wires and chemical injections never had much to do with it. Regardless, he is not mine to deal with."
Alice thought for a moment, "If I did this, and not you... I don't even know what I 'did!' What would have happened if I didn't?"
"I had confidence." Rynn raised up and walked out the door. The vats of matter were broken and leaking. The machine would be inert soon enough. Alice swore she saw wisps of something slowly uncoiling from the containers and dancing about in their own right. Their dance was free spirited, but seemed to drift in the direction Rynn was walking. Rynn even seemed to walk a little straighter as the wisps got near, offering them direction. They walked with her.
None of this made any sense to Alice. Just a few weeks earlier, she could trust her senses. She lamented the continued streak of hallucinations that seemed to follow her when she was around Rynn.
Alice looked back at Matthews. His eyes cried for death, but his hand seemed to refuse the order. His lips trembled, as though they were begging for Alice to give a command but could not form the words on his lips. It truly looked like he would stand there in pain until he starved to death if she gave the order. "Oh bother," she thought, "what to do, what to do."
It really was a monstrous machine.
[Answer]
You might want to look into Subliminal advertising. That is putting 'hidden messages' in images and so on by putting one frame between the others. this frame is repeated but you don't see it, your sub conciousness picks it up though. Or so is the theory, I think the myth was busted a time ago.
Nonetheless you could use it, forcing a human into an endless repeating series of certain images, 1 image can speak a thousand words and all that, and they would become slaves eventually.
[Answer]
Drug addiction.
It's not a genuine loyalty; it's craving for a drug and dreading the hunger.
The machine merely implants remotely controlled capsules in the brain of the victim, and delivers enough of the drug to build up a very serious addiction.
As long as you stay obedient, enough drug is delivered to keep the addict satisfied. Positive actions are rewarded with larger doses. Negative actions deliver a counter-drug, causing not only craving but incredible torture.
Some training, some controlled opportunities to resist that trigger the punishment, some opportunities to obey that bring bliss beyond imagination, and soon the victim learns to be a good puppet.
[Answer]
Pain doesn't work. 'Interviewees' will tell you whatever you want to hear, especially lies, if they believe it will make the pain stop. Fear however is a different matter.
Triggering the body's Fight or Flight response when the interviewee is heavily restrained would induce a state of absolute terror, which if focused on a person or object, could be used to coerce information.
It's far more difficult to lie convincingly when terrified and by ramping up the FoF response by directly triggering the release of the required neurotransmitters using the tentacles, the only limit would be when the interviewee has a heart attack from fear - which is highly survivable provided trained medical staff are on hand.
In terms of damage, the interviewee will probably be left with a permanent phobia of whatever was used. Interesting examples: The dark - reduce the lights when the Interviewee isn't co-operating. A Mirror - not sure if the Interviewee would develop a 'bloody mary'-type fear or just a fear of their own reflection. Flowers - can you imagine the psychological trauma that a snow drop could produce? Now imagine a sunflower. For the finale - a bouquet.
Or just nerve staple them.
] |
[Question]
[
**I come out of hyperdrive as far as possible from any galaxy. How isolated am I and what do I see?**
My purpose is to carry out a top-secret experiment where space is as flat as possible. For this reason I want to be maximally distant from any large masses including galaxies.
1. In our known universe, what is the furthest I could get from any galaxy?
2. Having arrived, what will I see with the naked eye? My guess is that I will see only galaxies and will not be able to distinguish individual stars. Will these galaxies be evenly distributed in all directions? Will I detect any galactic spirals, or will they just be dots of light?
---
Notes
1. I am not looking for coordinates relative to the Milky Way. I simply want a reasonable estimate of the largest distance in light-years that would be possible from *anything*.
2. Assume that there are no rogue stars in deep space between galaxies.
3. Assume that I have excellent natural human vision.
[Answer]
### Possibly $\sim$50 million light-years
I agree with the broader point in Ash's answer, if not the specifics. [Cosmic voids](https://en.wikipedia.org/wiki/Void_(astronomy)) are structures on the order of tens of millions to possible billions of light-years across. In general, they have low densities, [roughly $\sim$10% of the mean density in the universe](https://astronomy.stackexchange.com/a/16146/2153). That said, many voids do contain galaxies, albeit fairly isolated ones. Pisces A and Pisces B are notable nearby examples, although given the large distances to voids, detecting void galaxies is not an easy task. That said, their very existence means that your problem is a bit more complicated than just finding the maximum size of a void.
The spiral galaxy [MCG+01-02-015](https://en.wikipedia.org/wiki/MCG%2B01-02-015) is sometimes cited as being the most isolated galaxy in the universe. Lying roughly 300 million light-years away, it sits near the middle of [a void about 200 million light-years across](https://www.syfy.com/syfywire/you-think-youre-isolated-today-meet-the-galaxy-mcg01-02-015). As far as I can tell, no other galaxies have been found within that void, although it's *possible* that there are low-surface brightness galaxies in the vicinity, or perhaps extremely dim dwarf galaxies.
There are larger voids than the one that hosts MCG+01-02-015, but most are farther away, making it even harder to probe them. For example, the supervoid Ash mentions [is centered at a redshift $z\simeq0.22$](https://academic.oup.com/mnras/article/450/1/288/994945), which corresponds to a distance of [roughly 3 billion light-years](http://www.astro.ucla.edu/%7Ewright/CosmoCalc.html), ten times as far away. Therefore, any source would be 100 times dimmer, making it harder to detect any galaxies that might lie within it!
The point is, current observational evidence says that you could come out of hyperspace **50 million light-years** away from the nearest galaxy - a factor of ~20 lower than if we were to consider that supervoid. This would place you halfway between MCF+01-02-015 and the edge of its host void. At that distance, with the naked eye, you'd see . . . nothing. I believe Triangulum and Andromeda are the only galaxies visible to the naked eye from the Milky Way, and they're a mere 2 million light-years from us.
[Answer]
### The ***supervoid*** sounds pretty promising
There's a 1.8 billion light-year across [feature](https://www.telegraph.co.uk/news/science/space/11550868/Giant-mysterious-empty-hole-found-in-universe.html) called the [supervoid](https://www.pbs.org/wgbh/nova/article/universes-supervoid-may-be-the-largest-structure-ever-discovered-by-humanity/). It's about 3 billion light-years away from Earth, and averages 5 protons per cubic meter.
I have no idea what it will look like to the naked eye. If I had to guess: Probably billions of tiny fine pinpricks of light that you can only see if looking directly at them, but are basically invisible in your peripheral vision, with the variation in brightness so subtle it would be difficult to spot any features.
[Answer]
### The Cosmological Horizon
People, of the superstitious sort, used to think that the world was flattish and that, at the horizon, the world ended, and there was a great waterfall and if you sailed over it, you'd die.
Well, eventually. For a little while, at least, you'd have a really good view of some really big oliphants before crashing into the bitter cold carapace of a gigantic turtle.
Obviously, we know different, because some fellow called Magellan decided to sail towards the horizon and prove them wrong, which he did.
But that's just one little planet. The universe itself is much bigger and has more surprises in store.
For example, we really don't know how big it actually is. We only know how far in time we can see using our best technology. But you've got a starship that can take you to any point --- and that means you can truly get away from it all!
And to boot, you can prove Magellan, ultimately & fundamentally, wrong.
Eventually, your starship is going to approach not just the edge of the Geocentric Observable Universe, but you're going to approach the edge of the Universe proper. There will be, beyond this line, no stars, no planets, no comets, no cupids, no galaxies, no black holes, white holes or blue holes. Only radiation & the information it carries with it. This is the Cosmological Girdle, a sort of hazy & dim region of sparse particles of energy.
But beyond even this region, your starship will approach the very edge of Absolutely Everything Whatsoever, which is the Cosmological Horizon. The horizon, on Earth, we know, is the demarcation line where the light of the Sun first peeks up over the arcking edge of the Earth.
The Cosmological Horizon is the ever advancing demarcation line between that place *where you can discern the allermost, uttermost and lastestmost *squimon* of information originating from within the Universe itself* on the one hand, and that other place *where you can no longer discern anything at all from within the Universe*. Could be a light particle or some bit of matter or radiation, doesn't matter. Once your starship reaches that ultima thule of cosmology, you can pull up alongside the speeding *squimon* and stand on the theoretical border between The Universe, towards the aft of your ship, and Not The Universe, towards the bow.
Detectors arrayed along the aft quarters of your ship might detect 1 or 2 particles of energy in a petrasqintijillion cubic parsecs of space, the dim glow of the Universe's bow wave. Detectors arrayed along the bow of the ship can detect nothing approaching from ahead, and will also be unable to detect anything approaching from abaft. You've just passed beyond the last anything of the universe.
So, just bop along for a few more lightyears (ha-ha! -- how can there even bé a lightyear where there is no light?) and come to a full stop.
At this point, distance ahead is meaningless, because there's nothing around you to compare with. You are now in **THE VOID**. No rinkydink intrauniversal void this! This is the place everything that the Universe actually is *expands into and illumines with its radiance*.
Looking out your windows, you will be able to see only these two things:
1. **NOTHING** --- Nothing to see here, folks! You are beyond the physical & astronomical extent of the Universe, so there are no stars or galaxies here. You are now beyond even the radiation emanating from the objects that are along the outermost edge of the Universe. In every direction you look with your eyes, point a telescope or aim any kind of radiation sensor, you will receive no inbound data.
2. **EVERYTHING** --- Curiously enough, having left the final frontier outpost of the Universe, you will interestingly and conversely enough, be able to see everything! Every particle of matter and every particle of radiation that exists is now located within your starship, or radiating from it, whether it's your blinking hazard lights or the residual emanations from you hyperdrive exhaust ports. If you sent out a probe from your vessel, it would be surrounded & bathed in the very dim radiation of your own private little universe.
**Of Note:** You specified the "known universe", so here's something to chew on. Wherever you are, you are at the centre of the Observable Universe. If you move ten billion lightyears away from Earth, the centre of the O.U. moves ten billion lightyears away from where it was before, and naturally the Known Universe grows along with it.
There is also the Unobservable Universe out there, beyond what we can detect. This is where your starship is now. But, paradoxically enough, now that you have actually reached the edge of the U.U., and have gone beyond it by some distance, *you have actually not only increased the size of the O.U. by orders of magnitude, but you have also taken the Known Universe with you, out beyond itself*. Kudos and welcome to the Twilight Zone!
I've read that the U.U. may be 23 trillion lightyears in diameter. I would take that to mean everything up to the Cosmological Horizon. I've also read that the Universe is about 13.8 billion years old. Since we really don't know where we are within that 23 trillion lightyear diameter volume, and thus don't know which direction the original centre is (where the Singularity was), it will be a matter of pure guessing as to which direction to fly towards. If we happen to be only 14.2 billion lightyears from the Edge of the Universe Proper, and the shortest direction is "down" from the solar system, then you'll only be travelling something like 28.5 billion lightyears to get beyond the Cosmological Horizon.
If you choose wrong, well, you're going to be travelling a long, looooong way! 13.8 billion lightyears beyond the 23 trillion light years to travel through Absolutely Everything.
] |
[Question]
[
Imagine an alternate universe where the aborigines' impact on the Pleistocene Australian ecosystem was much less severe than it was in our timeline, and the Pleistocene megafauna managed to survive the sudden changes associated with human arrival in Australia.
Now, the year is approximately 6000 BCE, around the time when other societies were starting to take up agriculture and domesticate their first animals. Would the survival of these species provide any domesticable animals, or would the Aboriginal Australians continue their existence in a manner mostly unchanged from our timeline?
**Here are the main megafauna genera/species in consideration:**
* Diprotodon (Wombat the size of a Volkswagen Beetle)
* Procoptodon (Giant kangaroo #1)
* Sthenurus (Giant kangaroo #2)
* Zaglossus Hacketti (Echidna the size of sheep)
* Palorchestes (Marsupial tapir)
* Meiolana (Giant spiky-tailed tortoise)
* Megalania (Imagine a komodo dragon but much, much bigger)
* Genyornis (Omnivorous flightless bird that was over 2m tall and weighed up to 240 kilos)
* Thylacoleo ("Marsupial lion")
* Quinkana (Fully terrestrial crocodiles around the size of a saltwater crocodile)
* Wonambi (30-foot-long snake)
* Thylacine (Marsupial Wolf)
**Other things to consider:**
* Dingoes are still brought over by the humans, as happens in our timeline
* Aboriginal Australians have basically no contact with the outside world until the British arrive, similar to what happens in our timeline
[Answer]
# A couple of them at a push, but we probably want the smaller versions of even the best of these.
# (Except the Thylacine, which is fine.)
It's pretty fun to look at ancient creatures and wonder if we could have rode around them, but we sort of forget how hard it is to domesticate or even tame large creatures in an early technology society and despite the billions of species on earth, humans have domesticated big ones about... er... 8 times. And annoyingly for our hunter-gatherer ancestors, 7 of those were on the Afro-Eurasia megacontinent, leaving South America with Llamas and North America with the long-lost memories of Horses that had all run off to Asia.
So I'm gonna go through all of these creatures.
We're looking for a few qualities (which I've stolen almost verbatim from CCP-Grey, but here we are):
**Friendly** - Anything that views humans as food or 'to be killed' is right out. Without serious protection, if getting started is near suicidal, we're gonna stick to hunting them. We can breed this out eventually if we can contain them initially, but this makes everything else harder.
**Feedable** - We ideally want to feed it something we don't eat, that's easily accessible. If we have to hunt meat or feed our other domesticated creatures to it; that's really inefficient. We definitely won't be eating any carnivores, because we'd rather just eat the meat that they would eat. Almost all our domesticated animals eat basically any plant and the ones that don't better have really good uses, and are usually much smaller.
**Fecund** - If we're seriously domesticating something, we want to be able to selectively breed that, which we can only really do if we can get multiple generations past in the space of a human lifetime. If we can't write anything down; 10 years between offspring might as well be infinity and we'll never make any progress beyond the initial taming.
**Social** - Our best options are also Social. The herd won't separate. If you grab the leader of the herd, the herd will follow. Better yet, if the herd just thinks you're a very strange member of their herd, they'll go wherever you go. Horses will follow the herd. Zebras will abandon a captured family member. Flush a familly of rabbits out of their burrow and they'll scatter in 12 different directions. (This is perhaps the hardest one to guess for prehistoric animals, but we can take a guess from their descendants or close relatives.)
**Utility** - Whether food, combat, travel, hunting or ploughing; we need this creature to serve a purpose, otherwise it's pointless.
So
---
## - Diprotodon
**Friendly** - Wombats will attack humans even now, and this version is the largest marsupial to ever exist. There's little evidence of us even hunting them, (just like we didn't hunt Bears or Rhinos), and they're probably not friendly. Ambivalent at best. D-
**Feedable** - Eats basically any plant. Doesn't eat meat. Quite large though and probably migrated to find food, suggesting their impact on a local ecosystem would be significant. B+
**Fecund** - Based on size and herd numbers (Huge and >40); year long gestations. Multiple years between births. Basically impossible to selectively breed. F
**Social** - Herds of large numbers have been found, containing family members of all ages. Perhaps this aspect might be to our advantage. A?
**Utility** - Meat. Agriculture. Travel. Maybe even riding. A+
**Overall Rating:** C. Possible to be tamed in small numbers, much like elephants, for which they have their uses, but with no real success in domestication.
---
## -Procoptodon & Sthenurus (Gonna group our Giant kangaroos)
**Friendly** - Based on our current Kangaroos, almost certainly not. Males especially. Current tangles with Kangeroos are dangerous and these ones are taller than us. F
**Feedable** - Both herbivores. They only good aspect of this creature. A
**Fecund** - Slow to breed even at their non-extinct size. Even worse for a bigger prehistoric version. Pouch and fighting to mate makes it even harder for humans to intervene. F-
**Social** - Smaller families with complex herd dynamics. Potentially okay, but quite antagonistic. B-
**Utility** - Not the best source of meat and has little other utility. D
**Overall Rating:** D-. Impossible to properly domesticate and the value of taming them is low.
---
## -Zaglossus Hacketti (Echidna the size of sheep)
**Friendly** - Likely timid and flighty. Defenses are not so great that they'd stand their ground. Teeth aren't a threat, so they're unlikely to turn and attack us. A+
**Feedable** - A diet of insects. We could, perhaps, suppose it supplemented this with fruits, but the digestion of modern Echidnas and creatures like the Giant Anteater suggest this adaptation is probably unlikely and still doesn't get us to the point of it eating ubiquitous shrubbery that we'd like it to. C-
**Social** - Solitary? Current echidnas are, and so are non-extinct large insectivores. (Bacause hunting bugs is a solitary pursuit). Going to be hard to gather a herd. D-
**Utility** - Meat. Spines for tools? B-
**Overall Rating:** C. Despite the safety of this one, it's solitary and hard to feed. We'd better breed that solitary nature out quickly and find an area rich in something like termite mounds if we want to herd these.
---
## -Palorchestes (Marsupial tapir)
**Friendly** - Probably not. Modern tapirs would prefer to flee, but will turn and bite humans with powerful pig-like jaws if they feel threatened. A creature 10 times the mass of that probably won't bother to flee. D-
**Feedable** - Fruit, berries, leaves, bark. Pretty ubiquitous. A
**Fecund** - As above. Long lifecycle in living species. Even longer in larger exitinct ones. D-
**Social** - Pairs or small groups. Not ideal. C-
**Utility** - Meat. Agriculture. Travel. Riding? A+
**Overall Rating:** D. We'd love to domesticate or even tame these, but being somewhat comparable to an elephant but with even less social structure, we're more likely to be killed.
---
## -Meiolana (Giant spiky-tailed tortoise)
**Friendly** - Hard to say. Dangerous bite and tail, but slow and with low reach, so the threat is possibly avoidable? B-?
**Feedable** - Everything we want. A.
**Fecund** - Bloody hell. With a lifespan even longer than than ours, and a maturity rate to match, despite the fact that they'll churn out offspring once they are mature, we won't make any progress on domestication. F
**Social** - Very hard to guess. Possibly solitary. Possibly social. Unlikely to herd. D
**Utility** - Meat. Somewhat usable shells? Extremely slow to grow either though. C.
**Overall Rating:** C. We could pen these in and feed them on grasses, but they'll probably grow slower than their wild cousins and they already grow slow. Stick to hunting this really easy to hunt animal.
---
## -Megalania (Imagine a komodo dragon but much, much bigger)
**Friendly** - HAH. F
**Feedable** - Nope. F
**Fecund** - Eh. D
**Social** - Normally solitary. Groups can form around water sources, but there's no social structure. F
**Utility** - Hunting partners. A.
**Overall Rating:** F. Only good if you're looking for a hunting partner that will spend most of its time hunting you.
---
## -Genyornis (Omnivorous flightless bird that was over 2m tall and weighed up to 240 kilos)
**Friendly** - Extremely dangerous if cornered. Otherwise runs away. We've tamed other species like that (see: Horses). We're not a valid food source. C?
**Feedable** - Is maybe herbivorous? Possibly supplemented with small animals. B+?
**Fecund** - Not great, but at least they lay eggs, so we can pretend to be their parents when they hatch, further improving on their sociality? C+
**Social** - Possibly lives in groups, a la modern Ostrichs, with a Top Hen as a leader. We could be Top Hen. B+?
**Utility** - *googles Ostrich riding* Um. Hm.
**Overall Rating:** I was expecting to completely rule these out, but they're most closely related to modern Fowl, potentially have a social structure and eat plants. Uh.. B?
---
## -Thylacoleo ("Marsupial lion")
**Friendly** - "Pound for pound; Thylacoleo carnifex had the strongest bite of any mammal species, living or extinct" - F
**Feedable** - Eats bone marrow. Yours. - F
**Fecund** - Fine, but irrelevant. C.
**Social** - More in common with Kangeroos than cats, but an even smaller brain to body ratio suggests we're out of luck here. D
**Utility** - A hunting partner that will eat your entire kill. D
**Overall Rating:** F. I... No.
---
## -Quinkana (Fully terrestrial crocodiles around the size of a saltwater crocodile)
**Friendly** - No. F.
**Feedable** - Also No. F.
**Fecund** - Go on. Stick your hand in a crocodile nest. F
**Social** - Nope. F.
**Utility** - Nope. F
**Overall Rating:** F. Nope.
---
## -Wonambi (30-foot-long snake)
**Overall Rating:** F. See above.
---
## -Thylacine (Marsupial Wolf)
**Overall Rating:** Gonna skip over the details on this one because really we just need to know if it behaves more like foxes or wolves. If it's the latter, we're in luck and we just acquired our dog precursor. If it's foxes, well, then we might be approaching a domestic cat analog instead.
---
## Final Summary
I expected to agree with some of the other answers for the giant Wombat and Tapir, but both these species are too large to contain, too slow to domesticate and the Tapirs aren't even social. At best we have the same relationship as Elephants, where we can get them to do stuff for us, but only on an individual basis (i.e. One elephant can be trained to do X. A herd of elephants does whatever it wants and wanders off whilst ignoring us.)
Weirdly, the giant Echidna seems viable if your society lives near a lot of termite mounds you can move the herd between or have lots of insects in your better-climate Australia. Good meat and potentially spines or long hair for wool (if you want to take a guess at features we're lacking a paleological record for.) I haven't done the maths on a insect to Echidna consumption efficiency, but if you're happy to gloss over that, or bump up the number of insects in a hot, wet Australia, then you're probably fine.
The 2 metre tall speed-chicken isn't as absurd as I'd expected either, being potentially herbivorous and social. The greatest barrier to entry would be catching one, but you and 4 mates with ropes to try and catch it around the neck would allow you to get one without having to get too close to it's feet. (If your society is starting to need a Horse analog for travel.)
Realistically, you probably want to tame the non-giant versions of some of these. We have [Phascolonus](https://en.wikipedia.org/wiki/Phascolonus), a quite large wombat that would cheerfully chew through all the plants we want to it to, without being quite so dangerous to contain whilst we selectively breed it. It's sturdiness could make a good Oxen analog if we're shifting to agriculture. Or [Ngapakaldia](https://en.wikipedia.org/wiki/Ngapakaldia), a sheep-sized Tapir.
[Answer]
At a guess: Diprotodon, Palorchestes, and Thylacine.
There was a [Russian study](https://en.wikipedia.org/wiki/Domesticated_red_fox) which tried to domesticate foxes, attempting to mirror the dog-from-wolves domestication. It started in 1959, and is still ongoing, at least to a minor extent due to budget cuts. Look up the study if you want more information, but the long and short of it is that it seems most animals can be domesticated - well, at least most mammals. There's never been a succesfully documented case of a domesticated reptile. (Friendly, yes. Separate subspecies, no.)
So now the question is really just 'Which of these species would the Aboriginals *want* to domesticate?' And the answer seems pretty straightforward.
Diprotodon & Palorchestes - food. Wombat meat used to be a staple of Australian culture before they became endangered, so Diprotodon is an easy choice. Palorchestes would be my next pick for domesticated game, even though it's closer to horse than cow. After all, horse meat is considered to be fair game by ancient China.
Thylacine - wolves to dogs. Dogs have a very well earned reputation as man's best friend, and the Aboriginals would love a faithful companion to help them hunt.
[Answer]
## Probably none, alas.
You need a number of characteristics for animals to be [domesticated](https://en.wikipedia.org/wiki/Guns,_Germs,_and_Steel#Agriculture), at least these:
* sufficiently docile
* gregarious
* willing to breed in captivity
* having a social dominance hierarchy
That will eliminate every species that is not a mammal, and if a carnivore, wolf size or smaller. Also, as thylacines will have direct competition from dingo's, and as dingo's are step ahead in the domestication curve, have a big problem there.
Mind you that the bigger the animal, the more dangerous is becomes to domesticate. [Cattle](https://en.wikipedia.org/wiki/Cattle#Domestication_and_husbandry) (cows and bulls) are thought to have only be domesticated two, max thee times, due to being so incredibly dangerous to do so. And with as little as 80 individuals in one case. Horses have been domesticated multiple times, as have sheep, goats and donkeys. You can see the pattern here.
**Taming options:**
*Palorchestes* & *Diprotodon*, come kind of close to the [north african elephant](https://en.wikipedia.org/wiki/North_African_elephant). Maybe a few can be tamed, if raised from young.
**Domestication option(s):**
*Zaglossus Hacketti*, if it was a group animal and not a picky eater, is my best pick. Small enough to be able to handle quite well. Kind of like sheep. (but the picture with the long snout does not bode well for food)
*Thylacine*, if dingo's do not survive long and man decides it needs a new best friend. Else the competition is probably to strong.
**Smaller option:**
If you have something that can fill the function of ducks or chickens, you might have an alternative. But nothing I have read points to bigger birds a domestication options.
] |
[Question]
[
**This question asks for hard science.** All answers to this question should be backed up by equations, empirical evidence, scientific papers, other citations, etc. Answers that do not satisfy this requirement might be removed. See [the tag description](/tags/hard-science/info) for more information.
In the DC comic book universe, the Vega System is a solar system around the star [Vega](https://en.wikipedia.org/wiki/Vega) (Alpha Lyrae), which is depicted as having dozens of habitable planets. While it seems to be an implausibly large number, it does make me wonder: *what star type and arrangement allows the theoretical maximum number of human habitable planets (or planet-sized moons) in a solar system?*
I'm guessing that the answer would probably involve multiple, massive super-Jupiter planets orbiting in the star's Goldilocks zone, each of which has multiple habitable moons, as well as having more habitable planets in their L4 and L5 Lagrange points, but I'm not well-versed enough in the math to work it out for myself.
Since stellar mass is inversely proportional to the lifespan of the star (or, at least, negatively correlated with lifespan, if it's not strictly inversely proportional - again, not familiar with the math), having a super-massive star with a large Goldilocks zone isn't helpful if the star dies before life evolves, so it'd need to have a lifespan of at least several billion years to let life get started.
[Answer]
This is based off the information found in the [link provided by Juraj](https://planetplanet.net/the-ultimate-solar-system/).
**The answer is 2,862,106 earths in the goldilocks zone**
How to get 2,862,106 earths in habitable orbits:
Rules, they have to all be exactly the same mass.
Multiple planets can be in the same orbit, so long as there are at least 7, and they are at least 12 hill distances apart.
You can pack rings together tighter if alternate rings orbit in opposite directions.
First, start with a super massive black hole of 1,000,000 solar masses.
The Schwarzschild radius of this black hole is .02 AU, or 3,000,000 km. The closest stable orbit is .06 AU.
Put the Sun into orbit around it at .2 AUs. The black hole does not emit light of course, but the sun will, so this will give us a habitable zone. Of course the tidal forces on the sun will rip it apart into an accretion disk, but it will still be emitting light.
Because of the 1,000,001 solar masses of the black hole/sun system, the hill radius of each earth is 1/100th smaller than it would be around the sun itself. So you can put 4154 planets in each ring of planets.
If alternating rings are retrograde, you can put 689 rings in the suns habitable zone.
Alternately, you could avoid having the sun ripped apart into an accretion disk by having a ring of 9 suns evenly spaced in an orbit at .5 AU. The extra solar radiance would push the habitable zone out a ways, but otherwise the number of planets and number of orbits stays the same.
Another possibility would be to put the suns on the outside, with 36 of them orbiting in a ring at 6 AU. This would mean that each planet would get light from every side, meaning there would never be night time.
**Downsides:**
1. You aren't going to find a system like this in nature.
2. Each planet would be orbiting very fast, going around the black hole every 9 hours instead of 365 days. So the planets would be moving at about .1 C.
3. Planets in different orbits would be affected differently by relativity, and people on planets with closer orbits would be aging slower than people on further orbits.
4. Because of the orbital speeds involved, you would never be able to visit a planet in another orbit. But there are over 4000 planets in your orbit, and they would be stationary relative to you, and only about the distance of earth and the moon apart, so travel between them would be almost trivial. If they became tidally locked, you would be able to travel between them using a space elevator.
[Answer]
**SHORT ANSWER:**
It is impossible to calculate an answer to your question, therefore I expect that you won't get any hard science answers to your specific question. However, it is possible for experts to give you calculations about some limiting factors.
**LONG ANSWER:**
As far as I know, there is no theoretical maximum number of habitable planets in a star system. Star systems with habitable planets probably become rarer as the number of habitable planets increases, so that it becomes statistically less and less likely to find star systems with more habitable planets and finding a star system with more than a specific number probably becomes extremely unlikely.
Nobody has actually discovered any habitable planets outside our solar system, since with present technology it is impossible to tell if an exoplanet is habitable or not.
But astronomers have discovered a few roughly Earth sized planets orbiting within the habitable zones of their stars, and consider those planets to be potentially habitable planets. More such planets will be discovered. Sometime in the future each of those potentially habitable planets will be classified as either uninhabitable or habitable as more evidence about their conditions is discovered.
[https://en.wikipedia.org/wiki/List\_of\_potentially\_habitable\_exoplanets[1]](https://en.wikipedia.org/wiki/List_of_potentially_habitable_exoplanets%5B1%5D)
At the present it is unknown how common habitable planets are and thus what proportion of star systems have even one habitable planet. And of course systems with one habitable planet are probably more common than systems with two habitable planets that are probably more common than solar systems with three habitable planets and so on.
Sometime in the future astronomers may have detected a lot of habitable exoplanets and be able to calculate what percentage of star systems have one habitable planet each, what percentage of star systems have two habitable planets each, what percentage of star systems have three habitable planets each, and so on.
And then they could calculate an upper limit for habitable planets in a single star system likely to be found among a thousand star systems, or among a million star systems, and so on. They should be able to calculate the largest number of habitable planets in a single star system likely to be found in the Milky Way Galaxy, our galaxy, with its hundreds of billions of star system.
They could even calculate the largest number of habitable planets in a single star system likely to be found in the entire observable universe with its hundreds of billions of galaxies.
But nobody will ever be able to calculate the largest number of habitable planets in a single star system likely to be found in the entire universe that actually exists, stretching far beyond the observable universe, until scientists have a much more accurate idea of the size of the actual universe.
And of course calculations based on the relative frequencies of observed star systems with one, two, three, four, etc. habitable planets are likely to be more and more inaccurate for star systems with higher numbers of habitable planets, so calculations for the frequency of star systems with seven, or eight, or nine, etc. habitable planets would be increasingly inaccurate.
Here are some rough estimates of the frequency of solar systems with various numbers of habitable planets. These estimates are totally arbitrary just to illustrate the way it might possibly work:
I system with 1 habitable planet for every 10 stars.
1 system with 2 habitable planets for every 100 stars.
1 system with 3 habitable planets for every 1,000 stars.
1 system with 4 habitable planets for every 10,000 stars.
1 system with 5 habitable planets for every 100,000 stars.
1 system with 6 habitable planets for every 1,000,000 stars.
1 system with 7 habitable planets for every 10,000,000 stars.
So a statistically average random group of 10,000,000 stars should have 1 system with 7 habitable planets, 10 systems with 6 habitable planets, 100 systems with 5 habitable planets, 1,000 systems with 4 habitable planets, 10,000 systems with 3 habitable planets, 100,000 systems with 2 habitable planets, and 1,000,000 systems with 1 habitable planet.
There would be a total of 1,111,111 systems with one or more habitable planets and 8,888,889 star systems without any habitable planets in the group of 10,000,000 star systems.
That is just an example of an arbitrary distribution of star systems with various numbers of habitable planets.
Thus every habitable planet in an entire galaxy would have to be discovered for an accurate answer to the question of what is the largest number of habitable planets in an single star system in that galaxy.
When I was kid, I loved old science fiction stories where there were several habitable planets in Earth's solar system, even though the probability of that seemed dubious to me then and seemed dubious to astronomers even when those stories were written.
Venus, Earth, and Mars were all habitable for humans in many of those old science fiction stories.
Many stories even had other habitable worlds in the solar system. Every planet from Mercury to Pluto was habitable for humans and/or had native life in at least one old science fiction story that I remember. The giant planets Jupiter, Saturn, Uranus, & Neptune had solid surfaces that Earthmen could walk on and were habitable in some old stories. Habitable natural satellites included the Moon (though usually in the past), Jupiter's large moons Io, Europa, Ganymede, and Callisto, Saturn's moon Titan and maybe others, and Neptune's large moon Triton.
I once asked a question about what science fiction story had the most naturally habitable woulds in our solar system. [https://scifi.stackexchange.com/questions/94599/which-science-fiction-work-had-the-most-habitable-worlds-in-our-solar-system[1]](https://scifi.stackexchange.com/questions/94599/which-science-fiction-work-had-the-most-habitable-worlds-in-our-solar-system%5B1%5D)
As far back as 1964 an answer of sorts was provided to your question. Stephen Dole's *Habitable Planets for Man* (1964, 2009) was a detailed analysis of the factors influencing planetary habitability and the probability of a planet being habitable.
According to Dole, there was a limit to how densely packed the orbits of planets could be in a star system, due to gravitational interactions between the star and the planets, which would tend to make planets orbiting too close to others collide or be ejected from the system. I believe the size of a planet's exclusive zone would be larger the lower the star's gravitational force on it is, and lower the higher the star's gravitational force on the planet is.
According to Dole, the Sun's stellar habitability zone is about half full of the exclusion zones of planets and about half empty. So if the planets were packed as close as they could possibly be, with the edges of their exclusion zones just touching, within the Sun's stellar habitability zone, there could be about twice as many planets in the habitability zone as there actually are.
Assuming that there are three planet's within the Sun's stellar habitability zone, a star exactly like the Sun, with a spectral type G2V, with the same size circumstellar habitable zone, might have five, six or seven planets within its circumstellar habitable zone although that would be a rare occurrence. And among stars that have five, six, or seven planets within their stellar habitability zones, some would have all five, six or seven of those planets actually habitable, although that would be rare.
A more massive star than the Sun would be more luminous and thus its stellar habitability zone would be wider, and could contain more planets.
But Dole pointed out a problem with more massive and thus more luminous stars. More massive stars fuse hydrogen at a faster rate than is proportional to their mass. So they run out of fuel sooner than less massive stars do, and when they run out of hydrogen fuel they leave the main sequence stage of stellar existence and swell up into red giant stars and eventually shrink into white dwarf stars, changes that should kill off any life on their habitable planets and make those planets uninhabitable, even when those changes don't totally destroy those planets. The more massive stars also go though even worse stages like becoming novas and supernovas, which are even more likely to totally destroy their planets.
Dole estimated that a planet would not become habitable for humans until it was at least three billion (3,000,000,000) Earth years old, and that would probably be rare because Earth didn't become habitable for humans until it was a lot older than that. So a star would have to be capable of remaining in the main sequence stage for at least three billion (3,000,000,000) Earth years in order to be capable of having any habitable planets.
According to astrophysical calculations, stars more massive than spectral class F can not remain calm main sequence stars for as much as three billion (3,000,000,000) Earth years. Dole believed that even the most massive and luminous type F stars would not remain on the main sequence for three billion (3,000,000,000) Earth years. Dole decided that the most massive stars capable of remaining on the main sequence for that long were either F2 stars (less massive than F0 stars) or F5 stars (less massive than F2 stars), I forget which.
This was highly disappointing. It meant that most of the most famous stars in the heavens were incapable of remaining main sequence stars long enough for their planets to become habitable. Unless super advanced civilizations moved already habitable planets into orbit around those stars or terraformed the planets already orbiting those stars.
So I imagined that possibly a small percentage of F type stars would have the maximum number of planets in their habitable zones, and also be over 3,000,000,000 Earth years old, and also have all of their planets in the habitable zone actually habitable for humans. Presumably a very small proportion of them.
And I figure that if there were two identical F type stars orbiting closely enough - maybe five or ten million miles apart - around each other, they could have habitable planets orbiting both of them in a habitable zone whose limits would be 1.41 times the limits of a habitable zone for only one of those F type stars. A planet that orbits around both stars in a binary system is said to have a circumbinary or P-type orbit.
Astronomers have now discovered planets orbiting in P-type or circumbinary orbits around binary stars.
And for decades I believed that such a star system might possibly have as many as ten or twelve planets habitable for humans and that such desirable star systems would be very, very, rare.
Wikipedia has an article called Circumstellar habitable zone.
[https://en.wikipedia.org/wiki/Circumstellar\_habitable\_zone[2]](https://en.wikipedia.org/wiki/Circumstellar_habitable_zone%5B2%5D)
The width, or the inner and outer limits, of a star's circumstellar habitable zone or "Goldilocks Zone", are usually given in Astronomical Units or AUs.
An Astronomical Unit, or AU, is the average distance between Earth and The Sun. It is defined as exactly 149,597,870,700 meters or 149,597,870.7 kilometers, or 92,955,807 miles.
[https://en.wikipedia.org/wiki/Astronomical\_unit[3]](https://en.wikipedia.org/wiki/Astronomical_unit%5B3%5D)
If a star has X times the luminosity of The Sun, its circumstellar habitable zone should have X times the inner and outer limits, and thus total width, of the Sun's circumstellar habitable Zone. So to estimate the size of a star's circumstellar habitable zone one would just find out how luminous it is compared to the Sun and then multiply or divide the size of the Sun's circumstellar habitable zone by that amount.
Except that there isn't much agreement about the size of the Sun's circumstellar habitable zone.
The Wikipedia article "Circumstellar habitable zone" has a section with a table listing various estimates of the inner or outer edges, or both, of the Sun's circumstellar habitable zone.
[https://en.wikipedia.org/wiki/Circumstellar\_habitable\_zone#Solar\_System\_estimates[4]](https://en.wikipedia.org/wiki/Circumstellar_habitable_zone#Solar_System_estimates%5B4%5D)
According to the table, Dole estimated that the Sun's circumstellar habitable zone extended from 0.725 to 1.24 AU, with a total width of 0.515 AU.
Later studies have suggested highly different inner or outer limits or different total widths.
Some of those estimates may have been for planets habitable by humans, and others may have been for planets habitable for liquid water using organisms even if not habitable for humans, explaining some but not all of the differences.
In recent decades, over 4,000 planets in other stars systems have been discovered, including many examples of more than one planet orbiting the same star. And many systems with two or more exoplanets have widely different orbits than those in our Solar System.
The star with the widest spaced planets known is PTFO-8-8695, also known as CVSO 30. CVSO 30 c is about 662 AU farther out than CVSO 30 b, and its orbit has about 78,998 times the semi-major axis of the orbit of CVSO 30 b.
On the other extreme, Kepler-70c has an orbit with a semi-major axis only 0.0016 AU (about 240,000 km) wider than the semi-major axis of the orbit of Kepler-70b.
>
> During closest approach, Kepler-70c would appear 5 times the size of the Moon in Kepler-70b's sky.
>
>
>
However, it is now believed that the planets Kepler-70 b and c probably do not actually exist.
[https://en.wikipedia.org/wiki/Kepler-70[5]](https://en.wikipedia.org/wiki/Kepler-70%5B5%5D)
The system with the smallest known ratio between the semi-major axis of the orbits of two planets is Kepler-36. The semi-major axis of the orbit of Kepler-36c is only 1.1127 times the semi-major axis of the orbit of Kepler-36b.
[https://en.wikipedia.org/wiki/List\_of\_exoplanet\_extremes[6]](https://en.wikipedia.org/wiki/List_of_exoplanet_extremes%5B6%5D)
I don't know why Dole was wrong about the minimum possible spacing between planetary orbits, or how much closer stable planetary orbits could be spaced than in those examples.
I do not know whether the physics of planetary orbits is more dependent on the relative spacing or the absolute spacing of planetary orbits to determine how close two stable planetary orbits can be.
The narrowest habitable zone for the Sun is that given by:
>
> Hart, M. H. (1979). "Habitable zones about main sequence stars". Icarus. 37 (1): 351–357.
>
>
>
[https://www.sciencedirect.com/science/article/abs/pii/0019103579901416?via%3Dihub[7]](https://www.sciencedirect.com/science/article/abs/pii/0019103579901416?via%3Dihub%5B7%5D)
Since the outer edge of Hart's habitable zone is only 1.0631 times as far as the inner edge, if planetary orbits had a ratio of 1.1127 to that of the next inner orbit there would be room for only one stable planetary orbit within Hart's habitable zone.
Hart's habitable zone has an inner edge at 0.95 AU and an outer edge at 1.01 AU, with a total width of only 0.06 AU. If planetary orbits were spaced 0.0016 AU apart, there could theoretically be 37 or 38 stable planetary orbits within such a habitable zone, though it might be extremely rare for even one planet to orbit in such a narrow habitable zone.
The most common definition of the Sun's habitable zone is that of:
>
> Kasting, James F.; Whitmire, Daniel P.; Reynolds, Ray T. (January 1993). "Habitable Zones around Main Sequence Stars". Icarus. 101 (1): 108–118.
>
>
>
[https://www.sciencedirect.com/science/article/abs/pii/S0019103583710109[8]](https://www.sciencedirect.com/science/article/abs/pii/S0019103583710109%5B8%5D)
Kasting's habitable zone is much wider than Hart's. Kasting offered a conservative habitable zone, between 0.95 AU and 1.37 AU, and an optimistic habitable zone, between 0.84 AU and 1.67 AU.
The outer edge of Kasting's conservative habitable zone is 1.4421 times the distance of the inner edge. Assuming that a planet orbits at the inner edge, and that the planetary orbits are each spaced at the minimum ratio of 1.1127 times the orbit of the next planet:
The first planet would orbit at 0.9500 AU.
The second planet would orbit at 1.0570 AU.
The third planet would orbit at 1.1761 AU.
The fourth planet would orbit at 1.3087 AU.
The fifth planet would orbit at 1.4562 AU, which would be outside of Kasting's conservative habitable zone.
So assuming that the minimum possible ratio between the orbits of successive planets is 1.1127, there is room for four stable planetary orbits within Kasting's conservative habitable zone.
The outer edge of Kasting's optimistic habitable zone is 1.9880 times the distance of the inner edge. If a planet orbits at 0.84 AU and the planetary orbits all have a ratio of 1.1127 of the orbit of the next inner planet:
The first planet would orbit at 0.8400 AU.
the second planet would orbit at 0.9937 AU.
The third planet would orbit at 1.0400 AU.
The fourth planet would orbit at 1.1572 AU.
the fifth planet would orbit at 1.4327 AU.
the sixth planet would orbit at 1.5942 AU.
the seventh planet would orbit at 1.7738 AU, which would be outside of Kasting's optimistic habitable zone.
So assuming that the minimum possible ratio between the orbits of successive planets is 1.1127, there is room for six stable planetary orbits within Kasting's optimistic habitable zone.
Note that if the minimum possible spacing between stable planetary orbits is determined by their relative spacing, the absolute dimensions of a star's circumstellar habitable zone will not matter. Only the ratio between the inner and the outer borders of the star's circumstellar habitable zone will matter for how many stable planetary orbits could possibly be within that star's habitable zone.
Kasting's conservative habitable zone is 0.42 AU thick. Assuming that the minimum spacing between stable planetary orbits is dependent on their absolute spacing and not the relative spacing, and assuming that the minimum possible absolute spacing is 0.0016 AU, there is room for about 262 to 263 stable planetary orbits within Kasting's conservative habitable zone.
Kasting's optimistic habitable zone is 0.83 AU thick. Assuming that the minimum spacing between stable planetary orbits is dependent on their absolute spacing and not the relative spacing, and assuming that the minimum possible absolute spacing is 0.0016 AU, there is room for about 518 to 519 stable planetary orbits within Kasting's optimistic habitable zone.
Since Kepler-70 b and C might not exist, we could use the spacing between the orbits of TRAPPIST-1 f and g, 1,250,000 kilometers, as the minimum absolute spacing. Kasting's optimsitic habitable zone for the Sun is 0.83 AU, or 124,16,232.7 kilometers wide, and thus would have space for 99.33 planetary orbits spaced 1,250,000 kilometers apart.
If the minimum spacing between planetary orbits is dependent on their absolute spacing and not the relative spacing, the absolute size of a star's habitable zone and not the relative size of it will determine the maximum possible number of stable planetary orbits in it. Thus I suppose that if there is a binary system of F5 stars, with a combined habitable zone much larger than that of the Sun, there could be maybe as many as about 1,000 stable planetary orbits in the combined habitable zone of the two stars.
Of course possibly having as many as 1,000 stable planetary orbits in the habitable zone of a system doesn't mean that 1,000 Earth like planets will form in that system in the habitable zone or form somewhere else in the system and migrate to the habitable zone. But it does indicate a sort of a theoretical possible maximum of 1,000 habitable planets orbiting in the combined habitable zone of a system of binary F5 stars.
Of course there are are many spectral type A, B, & O stars which have much larger circumstellar habitable zones than my example of a binary system of F5 stars. Thus such stars can theoretically have stable orbits for thousands of planets in their habitable zones - if the minimum spacing between stable planetary orbits is dependent on their absolute spacing and not the relative spacing.
But according to current astrophysical calculations, spectral type A, B, & O stars cannot possibly remain main sequence stars for long enough to any planets they might have to become habitable for humans or develop advanced native lifeforms. The only way such stars could have any planets interesting at all - except for possibly mining - would be if an advanced civilization terraformed their planets to make them habitable for advanced lifeforms, or if an advanced civilization moved older planets with advanced life from other star systems and put those planets in orbit around those stars.
One way to check these calculations is the configurations of various families of exoplanets orbiting the same star as they are discovered.
According to the Wikipedia List of potentially habitable exoplanets TRAPPIST-1 has four planets orbiting in its circumstellar habitable zone which thus are potentially habitable planets.
TRAPPIST-1e orbits at 1.3153 time the orbit of TRAPPIST-1d.
TRAPPIST-1f orbits at 1.3150 times the orbit of TRAPPIST-1e.
TRAPPIST-1g orbits at 1.25 times the orbit of TRAPPIST-1f.
[https://en.wikipedia.org/wiki/TRAPPIST-1[9]](https://en.wikipedia.org/wiki/TRAPPIST-1%5B9%5D)
If the minimum possible spacing between stable planetary orbits is determined by their relative spacing, and the minimum relative spacing was 1.25 times, there could be two stable planetary orbits within Kasting's conservative habitable zone and three stable planetary orbits within Kasting's optimistic habitable zone.
If the absolute spacing of planetary orbits and not their relative spacing, determined the minimum possible distance between stable planetary orbits, a lot more planets could fit within a habitable zone.
Kasting's conservative habitable zone is 0.42 AU wide, and Kasting's optimistic habitable zone is 0.83 AU wide. Since an AU is 149,597,870.7 kilometers, Kasting's conservative habitable zone is 62,831,105.69 Kilometers wide, and Kasting's optimistic habitable zone is 124,166,232.7 kilometers wide.
Since TRAPPIST-1g orbits 3,680,000 kilometers beyond the orbit of TRAPPIST-1d, there are three orbital gaps in 3,680,000 kilometers, or one orbital gap per 1,226,666.66 kilometers. So there should be about 51 or 52 stable planetary orbits in Kasting's conservative habitable zone, and about 101 or 102 stable planetary orbits in Kasting's optimistic habitable zone.
There have been many questions about hypothetical habitable moons of giant exoplanets. You might want to look at the answers to some of those questions for references to other sources, such as this question:
[https://worldbuilding.stackexchange.com/questions/138653/temperature-and-climate-under-the-gas-giant-in-a-tidally-locked-moon/138696#138696[10]](https://worldbuilding.stackexchange.com/questions/138653/temperature-and-climate-under-the-gas-giant-in-a-tidally-locked-moon/138696#138696%5B10%5D)
The article "Exomoon Habitability Constrained by Illumination and Tidal heating" by Rene Heller and Roy Barnes Astrobiology, January 2013, discusses factors affecting the habitability of exomoons.
[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3549631/[11]](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3549631/%5B11%5D)
Added 08-23-2020:
And there is a blog called PlanetPlanet about planetary formation. It has some sections about science fiction worlds.
It has a section called Ultimate Solar System with posts designing solar systems with successively more habitable planets. [https://planetplanet.net/the-ultimate-solar-system/[2]](https://planetplanet.net/the-ultimate-solar-system/%5B2%5D)
And the more habitable planets there are in one of those solar systems, it less likely it would be for such a solar system to form naturally, and the more likely it would be that such a solar system would have been constructed or engineered by a highly advanced civilization.
So we can be pretty certain that systems like
The Ultimate Retrograde Solar System: [https://planetplanet.net/2017/05/01/the-ultimate-retrograde-solar-system/[3]](https://planetplanet.net/2017/05/01/the-ultimate-retrograde-solar-system/%5B3%5D)
The Ultimate Engineered Solar System: [https://planetplanet.net/2017/05/03/the-ultimate-engineered-solar-system/[4]](https://planetplanet.net/2017/05/03/the-ultimate-engineered-solar-system/%5B4%5D)
The Black Hole Ultimate Solar System: [https://planetplanet.net/2018/05/30/the-black-hole-ultimate-solar-system/[6]](https://planetplanet.net/2018/05/30/the-black-hole-ultimate-solar-system/%5B6%5D)
And:
The Million Earth Solar System: [https://planetplanet.net/2018/06/01/the-million-earth-solar-system/[7]](https://planetplanet.net/2018/06/01/the-million-earth-solar-system/%5B7%5D)
Would have been deliberately constructed by advanced civilizations.
[Answer]
AndyD273's answer is impressive and while I will not quarrel with the math behind it it's possible to go even higher:
First, it's based on a million solar mass black hole. The biggest one known is 40 billion solar masses. That's 33x as many planets per orbit.
Also, the original material offered two lighting options--stars below the planets and stars above. There's no reason for this to be an or, though--you could have multiple rings of stars alternating with bands of planets. I don't have the kind of computer power available that would be needed to see how many rings you can add before the grip of the black hole weakens enough to be a problem.
[Answer]
If multiple stars orbiting a (supermassive) black hole counts as one 'solar system', as some of the answers here presuppose, I propose that we take a supermassive black hole, put a bazillion stars in orbit around it, and have planets orbiting each star in its habitable zone. Such a configuration is more commonly known as a 'galaxy', and there is as far as I know no limit to the number of stars that can physically be part of a galaxy, so neither is there a limit to the number of planets.
If that is not the kind of answer the OP is looking for, I think clarification of the definition of 'solar system' is in order, especially with respect to binary (and more) stars and non-stellar massive objects like black holes.
] |
[Question]
[
# Premise
On Earth the seas have numerous filter feeding species, large and small, sustaining themselves on the microscopic nutrients and organisms that drift in the current. The largest animal evolution has produced here feeds on some of the smallest. Tropical coral reefs are the go-to example, but as a strategy there are examples from pole to pole and from the sun-warmed shallows to the abyssal depths.
Imagine a world with terrestrial environments in which numerous organisms – both sessile and motile – have evolved to do the same, living off pollen, spores, seeds, and other biological matter **drifting through the air**. Without *necessarily* using webs or slime, just opening its mouth or [purpose-evolved appendages](https://www.youtube.com/watch?v=z-K-6OKYw7Y) and scooping the air an organism can sustain itself for a season and/or supplement its diet. As on Earth there are biomes (perhaps the equivalent of tropical rain forests) where this is omnipresent and others where it may be less prevalent (perhaps the poles), but it is essentially as prevalent as filter-feeding in the ocean.
I expect a world that can support this sort of widespread feeding strategy would need prolonged periods of pollen-, seed-, and spore-production, which suggests minimal seasonal variation through the year and a high degree of competition. It also suggests there aren't enough pollinators to do the job manually, or the dispersal of pollen/spore to the air is done to combat pollinators and predators that consume more than they spread about.
Note: I am making a distinction between filter feeding and predation of flying organisms with webs and such, as that is already a successful strategy.
# Question
What conditions – atmospheric composition and density, tilt (as above, I suspect a low-to-no degree of tilt), evolutionary history, etc – would directly contribute to the success of such a global strategy and how?
---
Related: [Land coral and filter feeding](https://worldbuilding.stackexchange.com/questions/95132/land-coral-and-filter-feeding) asked by [metal\_maelstorm](https://worldbuilding.stackexchange.com/users/42719/mental-maelstorm)
[Answer]
First requirement is low gravity to make it even easier for materials to get and stay air borne.
Second is a relatively dense atmosphere or as dense as possible in the gravity. This would aid strong air currents and storms that would also help keep things air borne.
If there was a lot of rough terrain such as high mountains with heavy storms in the lowlands it might disrupt a lot of plant material and sweep them high up into the air. This might in turn encourage species to move to higher altitudes.
The low gravity, relatively high density and strong winds encourage plants to spread pollen and seeds by air rather than relying on pollinators.
There are in fact animals on earth that remain air borne for very long periods. [Swifts](https://en.wikipedia.org/wiki/Common_swift) stay aloft for months on end and do not generally land between breeding seasons. Swifts feed mainly on insects such as bees, wasps, dragonflies, flying ants etc.
So Swifts are not exactly what you are looking for but they are getting close. Such a species might be of interest and would certainly be encouraged in a low gravity environment.
[Answer]
The viability of filter feeding depends entirely on the viability of aeroplankton and the other organic material in the air. There's really no way around this, as filter feeding is only useful if there are a high abundance of things floating around.
Simply put, aerial filter feeding will happen wherever there are high concentrations of organic material floating through the air. There are a few ways to optimize this.
## Planet-scale effects
### 1) Decreased gravity
This is the most obvious one. If it's hard to stay in the air on Earth, then the obvious thing to do make that easier on our planet. It's easy to get to 0.25$g$ and you can probably push it to 0.10$g$ without too many large-scale planetary problems.
### 2) Increased atmosphere density
Again, we're going to be using the buoyancy equation so the heavier we can make the material we're displacing then the easier it'll be to stay afloat.
## Local effects
### 3) Focusing mechanisms
Filter feeders aren't found everywhere in the ocean. They choose their locations very specifically, often selecting for areas where there's a constant flow of plankton and nutrients. In the ocean, this means areas of upwelling and areas of high flow.
If our aerial filter feeders are still similar to Earth aquatic ones, we'd find them at areas of consistent atmospheric upwelling- the rising branch of the Hadley and Ferrel cells. Here, any materials in the atmosphere would be borne towards each other and upward until they can no longer be carried by the air, then they'd drop out and onto our filter feeders. Just like the rainforest temperate forest biomes, these biomes would be found near the equator and at 60 degrees N/S.
They'd also be found in more localized areas of flow- in valleys, for example. When wind passes through valleys, it's often focused, making it an ideal place to filter it out. Organisms living here would probably inhabit caves during the day and creep out with their feeding appendages to hunt at nighttime, very Avatar-style.
### 4) High-nutrient areas
Just as in the ocean, areas of high nutrient concentration would be vital. In the ocean, these are areas like hydrothermal vents. For the air, these would be areas near deserts. Many minerals can be found in dust, and deserts are large sources of dust and thus minerals, which would be important for anything trying to grow nearby. This would be another biome for the aeroplankton and thus the aerial filter feeders.
[Answer]
Water has a much higher capability of keeping things in suspension. Airborne particles tend to be much smaller (otherwise they would fall on the ground quite quickly). This pose a major limitation in the dimensions of the filter-feeders.
I strongly doubt this is a viable solution, but you may try:
* have no flying insect.
* have pollination via dispersion of pollen in the wind (like conifers).
* have dry air (rain washes-down any particles in air) with constant winds.
* have seeds to be airborne.
* devise some reason why flying is a very bad idea (e.g.: strong winds) so that plants need to rely on airborne seeds and pollen to spread.
[Answer]
First: what is a [filter feeder](https://en.wikipedia.org/wiki/Filter_feeder)?
>
> Filter feeders are a sub-group of suspension feeding animals that feed
> by straining suspended matter and food particles from water, typically
> by passing the water over a specialized filtering structure.
>
>
>
Swapping in "air" for "water" are there any existing animals that fit the bill? I think [nighthawks](http://what-when-how.com/birds/common-nighthawk-birds/) do.
Nighthawks swoop through the air, scooping up small insects as they go. Their beaks can gape very widely, similar to the gape of filter feeding fish.
screenshot from video <https://www.youtube.com/watch?v=XqDL-HzrfA4>
[](https://i.stack.imgur.com/Wxpwv.jpg)
Filter feeding marine animals have baleen (whales), [gill rakers](https://en.wikipedia.org/wiki/Gill_raker) (fish) or similar structures to effectively increase the surface area for catching food. Nighthawks beaks have bristles all around them that serve the same function.
<http://projectbeak.org/adaptations/beaks_picking.htm>
[](https://i.stack.imgur.com/tFrhQ.jpg)
Nighthawks are not eating the insects they catch one at a time. They are accumulating them in a big wad as they scoop them up, like a whale accumulates krill and plankton on the baleen.
<https://atowhee.wordpress.com/2011/06/13/chordeiles-minor-a-wonder-to-be-held/>
[](https://i.stack.imgur.com/kBBlh.jpg)
This site also shows the "windshield" of feathers nighthawks have around their eyes to protect them as the bird plows through clouds of insects.
Here an adult delivers a wad of insects to its young.
[](https://i.stack.imgur.com/DKLX4.jpg)
<http://what-when-how.com/birds/common-nighthawk-birds/>
Other birds lead similar lifestyles. Limiting factors may not be specific to airborne food - the chimney swift similarly filters the sky of insects, and their populations exploded after people started putting up brick chimneys everywhere (and then fell off as chimneys fell into disuse and were demolished). Higher density of airborne food facilitates this lifestyle - if you pay attention during outside sports games at night, you might see nighthawks swooping through the dense clouds of insects attracted by the lights. I wish I could have found a photo of this!
Some of the largest water creatures are filter feeders - I suspect because their indolent lifestyle allows it, larger size allows larger gape, and there is not much downside in the water. But lots of smaller water creatures are successful filter feeders too - like cod. I think in existing air animals the difficulty staying airborne works against very large sizes, although I could certainly imagine a pelican-sized bird being a successful air filter feeder in an environment with consistent loads of insects (or swarms to follow).
[Answer]
This hasn't received the attention I'd hoped for and the initial answers haven't garnered follow-ups to my comments, so I decided to do a bit more research and speculation and post it. Is answering your own question taboo?
*Note: I've said "plants" below but that should be understood as the alien equivalent, and include analogues to fungi, lichens, etc.*
---
# Planet Attributes
* **Low/no axial tilt and orbital eccentricity:** Seasonal variation would be at a minimum, meaning pollination and growth are possible year-round. It also means perpetual twilight at both poles and extends the [tree line](https://en.wikipedia.org/wiki/Tree_line) beyond the current ~60-70° and should help reduce permafrost at lower elevations.
* **Thicker atmosphere, more greenhouse gases:** This will raise the global temperature and stabilize any variation that may exist, further reducing permafrost and extending the growing range of plants. A denser atmosphere also makes it easier for small particulates to stay aloft, increasing the range pollen and seedlings and such can drift and the value of those strategies.
+ Increased greenhouse gases are necessary because removing carbon dioxide from the atmosphere, as plants do, has to be offset to keep the temperature stable over geologic time. I'm unsure how this could be achieved naturally and reliably – volcanism? more frequent forest fires?
* **Lower gravity, stronger magnetosphere:** This would aid the suspension of pollen, but more importantly it would increase the potential height of tree-analogues. A stronger magnetosphere would help retain lighter atmospheric gases (namely hydrogen) in the weaker gravity. Taller trees are critical because of the next point.
# Ecosystem Attributes
* **Greater botanical parasitism:** With taller trees and a warmer, stable climate, there will be more parasitic plants growing without any direct connection to the ground. This obviously multiplies the number of plants producing pollen and seedlings, but it also means more plants that can't take advantage of the [mycorrhizal networks](https://en.wikipedia.org/wiki/Mycorrhizal_network) that facilitate inter-plant and inter-species communication and cooperation.
* **Airborne signal networks:** With parasitism more common the lack of access to the mycorrhizal networks will have to be adapted to. Parasitic plants (and regular plants) will rely more heavily on pollen and [biological volatile organic compounds](https://en.wikipedia.org/wiki/Volatile_organic_compound#Biologically_generated_VOCs) to communicate with parasites on neighbouring trees and beyond, meaning more particulates.
* **Increased competition:** On the flip side, this also means more plants will employ and rely on [chemical warfare](https://en.wikipedia.org/wiki/Allelopathy) to compete for resources, discourage rivals, and combat (or selectively attract) predators. More particulates produced.
* **Late start for land animals:** On Earth the evidence suggests it was a relatively short time in the [Ordovician](https://en.wikipedia.org/wiki/Ordovician_radiation) after the [first simple plants took root on land](https://en.wikipedia.org/wiki/Evolutionary_history_of_plants#Colonization_of_land) that the [first animals](https://en.wikipedia.org/wiki/Pneumodesmus) followed.
+ A stable surface world thoroughly dominated by plants and fungi with advanced defenses would be a harder place for aquatic animals to transition to, but it would also mean more plant species have the aforementioned signalling and warfare mechanisms in place when predation and [zoophily](https://en.wikipedia.org/wiki/zoophily) start to factor.
+ The delay of animal-aided pollination would also mean plants are more reliant on airborne reproductive methods for longer.
[Answer]
**Buoyant algae via hydrogen generation.**
Several types of photosynthetic algae can metabolically produce hydrogen.
<https://www.sciencedirect.com/science/article/pii/S0960852417312014>
[](https://i.stack.imgur.com/YrEnt.jpg)
A colonial organism like a volvox could sequester bubbles of metabolically produced hydrogen inside its body to the point where it was buoyant in air. Buoyancy would have benefits for a photosynthetic organism as it could rise above earthbound competitors for sunlight. Such organisms are very small and so the bubble needed to lift them would not be big.
Such organisms would need a method to keep oxygen away from the hydrogen, a trick because these organisms also usually produce oxygen. In an analogous situation, legumes use leghemoglobin to scavenge oxygen and keep it away from the nitrogen fixing bacteria that reside inside them - oxygen poisons the nitrogen fixing biochemistry. Floating algae could do the same to protect their hydrogen. It would make them red.
Floating algae would need nitrogen from the air which probably means N2. They would need the ability to fix nitrogen or have onboard commensal bacteria which could do it. Good thing they have that oxygen scavenging system!
Floating algae would need moisture from the air as well as they could easily dessicate. High ambient humidity would be the best way to do this.
---
Walking through a wet humid planet dense with these things would very quickly look like they were covered with blood. Aerial filter feeders could eat this aerial plankton up just fine.
[Answer]
**Planetary Conditions Aren't necessarily the critical factors**
Sure things like lower gravity and increased air pressure would aid in this kind of evolution but the **KEY FACTOR IS ECOSYSTEM.**
Technically, Earth could support such an evolution as a flying filter feeder, but what is needed is the available aerial energy.
* Lots of insects or small birds flying around like constant swarms of locusts or larks.
* and/or lots of aerial pollen or seeds drifting in the wind.
After that it is a matter of evolutional roulette but its not hard to fathom adaptations to allow large filter feeding animals.
] |
[Question]
[
My world has a huge crater (4400 miles in diameter) on a world that's roughly earth equivalent (so a circumference of 25000 miles). The native population doesn't need to know how it was formed but it would be nice if the world creator did! Around the edge is a ring of islands, inside and outside there's nothing but the sea.
I've been thinking about the [crater from the meteoroid which wiped out the dinosaurs](http://en.wikipedia.org/wiki/Chicxulub_crater). I believe it's 180 km in diameter, obviously, this is far too small. I'm not sure a planet could survive an impact from something almost ten times the size (apocalyptic isn't an issue but the planet needs to survive and go on to create life afterward).
I've thought about volcanoes but I'm not sure that would create the shape I'm looking for.
I can resort to magical means as a last resort but I'd really rather keep this real world.
Ideally, I would like the crater to start in the polar regions and stretch down well towards the equator (almost like the death star) so there is a vast range of islands. It does not need to be particularly deep so doesn't need to go anywhere near the planet's core.
Could a crater this size occur without godlike intervention? If so how?
[Answer]
Actually while the title of your question asks for an enormous crater, the body is asking for something completely different - a ring of islands.
That could be explained by a couple of means that do not involve craters at all - both of these start in a planet entirely covered by water, but not too deep water.
**Ring of Fire**
A "hot spot" in the magma of the planet causes volcanoes to form above it, over time that hot spot moves around in a circle driven by Coriolis forces within the magma, as it does a line of islands appears above it as volcanoes punch up from the sea bed and into the surface.
When first formed you would get tall active volcanoes, these would then gradually erode down as the hot spot moved on until millions of years later the hot spot returned and built them up again, so you would have a ring of gradually eroding islands "behind" the active one.
**Organisms**
A hypothetical corral species proves very successful and builds its way all the way up to the surface and then starts expanding outwards. As it moves out the old coral starts to erode and collapse back down. The growth of the coral absorbs certain nutrients from the sea shore so it always keeps expanding outwards in a ring.
Natural events, valleys in the sea floor, variation in the mineral, etc mean that breaks form in the ring as it expands leaving the situation after millions of years of a ring of islands with empty sea both inside and outside of the ring.
[Answer]
There have already been some great non-impact ideas, but I thought I'd add one more resource. consider Saturn's 3rd moon, [Iapetus](https://en.wikipedia.org/wiki/Iapetus_(moon)):
Scientists have several theories for Iapetus's characteristic equatorial ridge, but the most compelling to me is the collapse of an ancient ring system (this would have been from Iapetus's own ring system, not that of Saturn). See the Wikipedia page [Equatorial ridge on Iapetus](https://en.wikipedia.org/wiki/Equatorial_ridge_on_Iapetus) for the other, more boring theories.
Over time, all planetary ring systems collapse. If you wish to connect this cause to the present through stable rings that survived this collapse, they would require [shepherd moons](https://en.wikipedia.org/wiki/Shepherd_moon) to keep them in place.
[Answer]
A few ideas, I'm not sure how viable they all are:
**Spin Changes**
The planet formed and cooled spinning very rapidly as a result it had a flattened rather than spherical shape. It then captured a large moon nearly as large as itself, the resulting tidal forces slowed the spin down drastically (and led to some interesting times for anyone alive at the time).
The slowed spin meant that the poles were now significantly lower effective gravitational level and the water drained down into them, filling them with water.
This would give massive circular oceans at each pole.
**Near miss**
A large planetary body came very close to striking but in fact only skimmed the surface then headed back out into space. The glancing blow ripped out a huge chunk of land (unfortunately unlikely to be circular but less devastating than a direct impact).
**Headshot**
A very dense body (for example black hole or neutron star) punched clean through the planet taking out a huge chunk of material as it did and then continued on across the solar system.
The rest of the planet then collapsed into the void and you had some pretty extreme geology for a while afterwards but ironically by just removing large amounts of material cleanly it might do less damage to the rest of the planet than a conventional meteorite impact would do.
[Answer]
Unfortunately, a single compact object hitting a planet with enough mass and velocity to create a crater this size would be an extinction-level-event that would most likely sterilize the planet and turn the impact site into a four-thousand-mile-wide pool of lava surrounded by the crater wall as it punched clean through the planetary crust and into the magma layer beneath (assuming that this planet is earthlike with a molten core). It is also likely that there would be massive fault-line ruptures radiating away from the site of such an impact.
On the other hand, such a large impact would leave its mark on the planet for millions of years, however it is likely that on an earthlike planet, such a great amount of elapsed time would result in the workings of plate tectonics disrupting the nice neat ring described, and it could take billions of years before advanced life appeared again unless there was a bit of [panspermia](http://en.wikipedia.org/wiki/Panspermia) going on.
Another option that may remotely work is a huge [caldera](http://en.wikipedia.org/wiki/Caldera), a volcanic system where a section of crust separates in a roughly circular area and subsides, leading to a ring of volcanic eruptions around its edge. However, calderas are not usually found on that sort of scale, they are typically tens of miles across, not thousands. Again, a caldera on this scale could also be an extinction-level-event.
The most likely non-magical event that I can imagine is also somewhat far-fetched. If a circular orbital habitat 4400 miles in diameter fell to ground on its side, it could cause the circular chain of volcanoes or crater wall mountains described that would be visible thousands of years later without necessarily causing a mass extinction event However, that would presuppose that a previous civilization was sufficiently advanced to create such a habitat, and then departed without leaving other traces - or that any other traces they may have left have long since decayed.
[Answer]
sorry i didn't read all the previous answer but a huge impact crater is terrible for live on your world. Have u consider to use a mechanism like the one thath create the blue holes?
Acidic rain erode and dissolve limestone creating lots of crack in it. So weaked the limestone can collapse in a second time under the action of an high pressure or maybe an earthquake.
sure it's not a crater, but is similar and surerly more life suitable than an asteroids
] |
[Question]
[
I know some griffins are depicted with bird tails, but in the majority of fiction, artwork, etc. I've seen, they are depicted with lion tails.
I am wondering, how exactly would a lion tail benefit the griffin more than a bird one?
I'm writing a story with griffins in it so I would like some help with this detail please.
[](https://i.stack.imgur.com/vnkBF.jpg)
[Answer]
**Griffins are mostly land predators**
The lion tail is there for counter balance and helps with manoeuvrability on land.
A bird's tail helps with flight. The lack of one suggests that a griffin doesn't spend much time flying.
So, all this means that griffins with a lion tail spend more time on ground, especially hunting. The wings must be something they use seldom. They can still use it to go up or down a cliff for example.
One interesting idea is to use it for scouting - go up a tree or other elevated part of the terrain and then swoop down in the direction where the pray is. Close by but not exactly next to it. The griffin can then use the stealth and hunting tactics of a lion - approach and attack.
One more notable thing about lion's tails - the little puff at the end aids with communication. Lions can swing their tail to communicate with other members of their pride and griffins can also probably do that. It will be quite useful if there are some posted as lookouts up high. They can swing their tail to notify "Prey spotted" or "Everything clear".
This seems like a logical way to use their bodies and features.
[Answer]
**Dignity:**
Because the hairs on the Lion tail channel its flying Magic *much* better than mere feathers can. Just look at **where** a griffin's wings are located. *Way* in front of the center of mass. Without a significant anti-gravity boost from the tail, the Griffin would fly in an ass-dragging posture, and that is simply not dignified!
Without something better than mere aerodynamics to lift its backside, a flying griffin would look like this (plus wings)
[](https://i.stack.imgur.com/O5IlK.jpg)
[Answer]
Tails are often used as an extra appendage to provide safety in hanging from heights while still being able to grab & tear & hold onto food without needing to balance. That tail can be used as luer then those claws & beak can attach the curious/nosey animal. It could swat potential food from its perch, nest whatever & then the coordinated talons or beak grab it as it flies beneath that falling 'morsel'. Can be brought around & wrapped over the face to protect the eyes while sleeping? The bird can disappear amongst bright flowers, the back end & long narrow tail amongst tree trunks, rises in the soil....blending in for self protection.
] |
[Question]
[
So my story hinges largely upon a precursor type race centered around a single star system that went extinct tens of thousands of years prior to the modern day. Obviously, the most common way to go about making an advanced civilization of this sort would be to create a Dyson Swarm and move away from planetary living entirely in favor of constructed habitats yadda yadda yadda, stop me if you've heard this one before.
So partly out of a desire for novelty and partly out of a desire for the sick visual (comic rather than novel), I had the idea of a civilization using the standard 'space folding' FTL technology to simply transport desirable planets from their native star systems and into their own. This would eventually result in a monstrously large star system (that they perhaps feed atomic hydrogen from nebulae in order to maintain its size and gravity) with several hundred planets orbiting it in perfectly calculated and carefully controlled orbits, looking sort of like the cartoony depictions of atoms you often see but turned up to 11.
The thing is, I know just enough about astronomy and astrophysics to know that I don't know nearly enough to actually understand whether or not this is an even remotely viable strategy, or if it would all completely fall apart under conventional physics. Would it be practical, or even feasible, much less possible (provided the method of planetary transportation was a non-issue) to custom-build your own star system with hand-picked planets from around the galaxy? Additionally, what might be some unique benefits or drawbacks that could come from doing this?
Edit: suggested questions do help with some aspects (particularly using gas giants with planet-sized moons. I like that one), but the level of technology that this civ has access to makes **some** of the presently known limitations a non-issue, and the precision of aligning planets all into the extremely tight habitable zone may not be as big of a deal for them. I was more concerned with figuring out the orbital mechanics and what would be necessary to keep planets from crashing into each other. Keeping planets equidistant on their various axes works for that, but as I said, I'm going for the 'sick visual' to some degree (and I don't mind fudging the rules **a little**, as this isn't the hardest of hard sci-fi stories,) so I was hoping for multiple orbits, multiple axes. Something beyond our current capabilities by a long shot, but not something that utterly destroys conventional physics on its own: maybe just... **bruises** conventional physics a little.
[Answer]
### TL;DR:
Assuming you have the considerable energy to get the imported planets into stable orbits, then yes.
Hundreds to thousands of Earths can fit into stable orbits in our solar systems habitable zone.
### Positioning the planets:
Conversation of momentum should hold through space folding FTL - the host star systems will have different velocities relative to each other, the planets will have different relative speeds to each others suns. You'll need to apply 10's - 100's of km's per second of delta-v to a planet-sized mass within a timeframe of days to settle down the orbits... that's a lot. You may be able to optimise this by careful timing and positioning, and / or slingshot around a distant gas giant, but it's still dyson-sphere levels of energy. (Unless your space-folding can also space-bend or space-shrink/expand in such a way that this is handwaved).
The more planets in the habitable zone, with different orbital periods, the more likely 2 will eventually interact and disaster results for those people. A maths analogy would be the Lowest Common Multiple of any pair of integers in a large set.
Consider 2 planets in orbit, one in 7 month orbit, one in 8 month orbit; Eventually 7, 14, 21, 28, 35, 42, 49, 56 intersects with 8, 16, 24, 32, 40, 48, 56. When they do, both of their orbits will change. Subtly or catastrophically. You may be able to buy some time by carefully choosing the numbers, or making the orbits have different planes, or having widely elliptical orbits, but eventually it'll all fall down, with the exception of one configuration:
The most stable orbits for multiple planets in a habitable zone would be on the same ring, with the same orbital period, but equally divided in phase. These 4 planets would be stable for a very long time:
[](https://i.stack.imgur.com/Kcvnk.png)
Adding a planet to the ring will also require thrust by all other planets, assuming their all the same mass, the planets should be kept equidistant from each other so that the forces the planets exert on each other cancels out, eg for 6 planets:
[](https://i.stack.imgur.com/azwrN.png)
To get from 4 to 6 planets, the 2 incoming planets will need huge amounts of thrust to enter that orbit, but at least 3 of the existing planets will need to do manoeuvres as well. This would be 2 thrusts, one to transition to an elliptical orbit, and one to transition back to the original orbit, but "behind" where it was by a small fraction of the year, enabling room for the new planets on the ring.
### Max number of planets:
What's the upper bound of the number of planets in the ring before it all breaks down? It more likely depends on the ratio of the mass of the planets before any other factor. If the planets are equal mass, then I believe the limiting factor will be making sure the atmospheres don't touch, as that could affect their day length and create friction, which would create heat, and thus intense storms. This dense packing will also remove all moons, and any satellites not in orbit perpendicular to the planet's orbit.
Working with our solar system, and leaving a safety margin of 8 earth diameters between them, you could fit ~9000 earths onto the orbital ring of Earth in the current solar system. (940,000,000km circumference of orbit, 12,700km diameter of earth).
Some people in the comments believe you'll need more of a safety margin than this. I only have my gut feeling of "but they should cancel out" to defend this number.
More than one ring may be possible, if your habitable zone is big enough, but each ring must have an orbital period different enough so the interaction is (essentially) zero.
### Interesting issues
Tides would be a pain, the more planets added to the ring, the stronger the pulls in the forward or rearward direction. As the number of planets grows, it will be like sea levels rise. Tides would synchronise with the length of the day too, high tide would occur and sunrise and sunset.
One planet would rise at midday, and at sunset would be high in the sky. Few hours later that would set. You would then get a few moments of pitch blackness, depending on latitude and geography, and then another planet would rise. When this reaches high in the sky, the sun will rise.
Your two neighbouring planets would both be perpetually in half shadow. There would be no "phases of the moon" kinda thing.
Everytime a new planet is added, the night sky will become permanently brighter. The first 50 planets will have near total darkness at night. When there's thousands, true darkness will be rare. This will make land-based telescopes useless, and mess with nocturnal creatures.
Also getting a new planet in the system would be a big deal for the entire ring. Eg it would break every planets individual calendar. It would be half a year where you couldn't rely on sunrise and sunset being their precalculated values, the day length may be subtly different. A perfectly accurate clock could appear to lose and then gain time. Given we struggle with leap seconds (Eg stock exchanges lengthen every second by a a fraction rather than risk breaking high frequency trading with a 61-second minute), this interruption could be unpopular for the ruling body. If Christians or similar are present, the calculated date of Easter would be incorrect. Festivals which occur on equinoxes and solstices might have to be moved, or worse case even skipped. Moving a public holiday with only a few weeks or months notice would cause havoc with businesses, people would have to cancel travel plans, etc.
It's possible one planet could be spared from this chaos, one single planet could keep a constant calendar through all system-wide manoeuvres and be spared this complexity - probably the ones whose citizens donated the most to the ruling parties reelection campaign.
### Trade
Transport between planets "upstream" on the ring would be very costly, but "downstream" would be very cheap (daily launch windows, once you get in orbit, a tiny amount of delta V needed to get from one planet's gravity well to the nexts). Unless you're willing to expend extreme amounts of propellant, (or space-folding is available everywhere and has replaced rockets), resources and trade would always go in one direction.
The most efficient path for non-time-critical resources (eg bulk frieght) in this system, interestingly, involves them applying thrust to take them upstream. Applying thrust to start you moving towards the planet ahead of you, will speed a ship up relative to the sun, swing you out a bit, and when you rejoin the ring you'll have moved downstream. Another thrust is needed to stabilise your new orbit. See <https://en.wikipedia.org/wiki/Hohmann_transfer_orbit>
### Renders?
Someone in the comments have asked for renders of what 9000 planets on the same ring look like:
Excuse the low quality. Here's 9000 planets on the same ring as seen from a nice vantage point
[](https://i.stack.imgur.com/d0NGn.png)
View of ring east from northern hemisphere at mid day. Will look roughly the same to the west too.
[](https://i.stack.imgur.com/Clejw.png)
[Answer]
Sounds perfectly feasible, as long as you keep maintaining it. The planetary orbits are unlike to be stable over the long term (thousands of years), but if you can move the planets from different solar systems, you can certainly tweak their orbits from time to time to keep them stable. You’ll want to use a big star to maximise the size of the habitable zone, so it won’t be the aliens’ original home star, because big stars don’t last long enough for intelligent life to evolve.
[Answer]
### You could have a huge lot of planets in a system!
If you are only concerned with the stability of the system once it is formed by whatever means, you could have many habitable worlds in (relatively) stable orbits crammed relatively reasonably close together. For detailed instructions, see the *[Ultimate Solar System](https://planetplanet.net/the-ultimate-solar-system/)* guide by Sean Raymond. [The biggest one proposed](https://planetplanetdotnet.files.wordpress.com/2016/04/ultimate_solarsystem_part6-010.jpg) contains around 400 habitable planets within 1000AU, see *[Building the ultimate Solar System part 6: a system with multiple stars](https://planetplanet.net/2016/04/13/building-the-ultimate-solar-system-part-6-multiple-star-systems/)* for detailed explanation. Even if left unchecked after the formation, [it would still take around a billion years for it to fall apart](https://planetplanet.net/2016/04/28/the-biggest-tragedy-in-the-history-of-the-universe/).
You could make it even better by [introducing a supermassive black hole](https://planetplanet.net/2018/05/30/the-black-hole-ultimate-solar-system/).
[Answer]
Your scenario is that of the Captive Systems maintained by Carontians in Roger McBride Allen's *Hunted Earth* series.
These systems are **unstable**; you need to get your planets in resonant orbits, and this almost automatically puts most of them outside the Goldilocks zone.
Even just **two** planets in the same orbit would be in an unstable equilibrium, and this is the exact scenario that is thought to have given rise to the [Theian impact](https://en.wikipedia.org/wiki/Theia_(planet)). Stability ensues if the Trojan mass is less than 1/25th of the planet's, but this prevents it from being habitable.
You can manage **for a short while** with specific configurations known as [Klemperer's Rosettes](https://en.wikipedia.org/wiki/Klemperer_rosette), but this too has restrictions on the planet sizes.
So, your only "real solution" is to use handwaving. The system **must be actively kept stable**, and this can be done by using Klemperer configurations with *disappearing planets*. The small "stabilizing" masses in the Klemperer configurations are periodically phased out via wormholes to a distant companion of the megastar, where they are put in stable orbits; this is done in such a way that the orbital instability in the megastar system *compensates* for the growing instability from the large planets.
In practice, as soon as two Earth-like planets in an orbit start drifting too much apart (which means they drift towards some other Earth-homologue), a Moon-sized lump of mass is FTL-gatewayed in the empty space between them, attracting them together. If the mass appears soon enough after the instability manifests, the mass requirements are low.
Of course, if you happened to land on the uninhabited "holding" binary system and land on on of the many Moon-sized planetoids that are there, just before it is phased out, this could be a nasty surprise for the rest of the crew.
[Answer]
You might want to read the answers to [this](https://worldbuilding.stackexchange.com/questions/151028/what-is-the-theoretical-maximum-number-of-habitable-planets-in-one-solar-system%5B1%5D) question.
And there is a blog called PlanetPlanet about planetary formation. It has some sections about science fiction worlds.
It has a section called [Ultimate Solar System](https://planetplanet.net/the-ultimate-solar-system/%5B2%5D) with posts designing solar systems with successively more habitable planets.
And the more habitable planets there are in one of those solar systems, it less likely it would be for such a solar system to form naturally, and the more likely it would be that such a solar system would have been constructed or engineered by a highly advanced civilization.
So we can be pretty certain that systems like the [Ultimate Retrograde Solar System](https://planetplanet.net/2017/05/01/the-ultimate-retrograde-solar-system/%5B3%5D), the [Ultimate Engineered Solar System](https://planetplanet.net/2017/05/03/the-ultimate-engineered-solar-system/%5B4%5D), the [Black Hole Ultimate Solar System](https://planetplanet.net/2018/05/30/the-black-hole-ultimate-solar-system/%5B5%5D), and [the Million Earth Solar System](https://planetplanet.net/2018/06/01/the-million-earth-solar-system/%5B6%5D) would have been deliberately constructed by advanced civilizations.
And don't just blow away the idea of space habitats for the central star system of a space empire instead of or in addition to many planets in that system.
You should read "[Bigger than Worlds](http://www.isfdb.org/cgi-bin/title.cgi?133302)" by Larry Niven, *Analog science Fiction/Science Fact* March, 1974, which has been reprinted many times.
[Answer]
Start with a brown dwarf or other large "dim" planet orbiting a star. Your first set of planets are now moons around that brown dwarf.
Then stick a much smaller gas giant at the leading and trailing Lagrange points of this brown dwarf. Stick more planets in orbit (moons) of these smaller gas giants.
Most other "Goldilocks" configurations result in dynamic instability; as the bodies drift away from the stable rosetta pattern (or other stable pattern), they drift further away from the stable pattern, until the system collapses.
The leading/trailing points are far more stable, in that perturbation leads to the body orbiting the point instead of being rapidly ejected.
Small bodies orbiting a large one (moons) can be stable, and the distance to the brown dwarf (or gas giant) doesn't matter much to the temperature of the moon, which is determined by the distance to the star (which is relatively constant).
The gas giant or brown dwarf would evaporate as its atmosphere was shredded by the star, and the moon's orbit might decay slowly, but this should be much slower than any rosetta configuration and require less intervention.
The primary dwarf must be much lighter than the star, and the secondary gas giants much lighter than the primary dwarf, for the math to work out here.
] |
[Question]
[
Slimes are a common monster we often see in games such as Minecraft, Terraria and Slime Rancher, but it is never explained how such an animal can exist. How could the body of such an animal even exist on land, how could they go about in nature?
As we have seen in the games these animals populate a slime can be described as:
1. Having a slime like exterior
2. Having a firm shape
3. Moving around via hopping.
4. Having eyes and having mouths
Assuming earth biology and natural occurrences, how could a slime exist? How could it move in such a way, how could it eat or even see? How does in not simply collapse like most slimy water animals do?
A list of all of the Anatomically Correct questions can be found here
[Anatomically Correct Series](http://meta.worldbuilding.stackexchange.com/questions/2797/anatomically-correct-series/2798#2798)
[Answer]
## 1. Anatomy
If we try and think of slimes as animals in nature, they must be composed of cells, or at the very least one cell. In fact, slimes do show an uncanny similarity to single-celled organisms, but there is a problem: there is a limit to the distance between the nucleus and the other edge of a single-celled organism. While we could combat this by having multiple nuclei distributed all over the place and there are animals that have this strategy; syncytium, or slime molds.
The slime needs to be multi-cellular, we do have multi celled "slime molds" called dictyostelium. It has a slug like face and crawls around as a discrete blob, but even though it is a good match, it is not a good candidate for what we want. Natural slimes mold are either too small or to in-cohesive. These are as close to the slime we need as nature gets, after this we need to speculate.
We know our slime has a firm shape, so it needs to have some kind of support structure, we also know it eats and has eyes, so it will need organ systems. Based on what we know, the slime will need to be a discrete organism, no less complex than your average jellyfish. In fact, let's consider jellyfish.
Jellyfish are soft bodied sea critters that use their "arms" to catch and eat food. Their body is shaped like a bell to push water and propel themselves. Jellyfish have to tissue layers; The ectoderm, forming their 'skin' and the endoderm, forming their gut, represented below by green and blue respectively.
[](https://i.stack.imgur.com/rCne5.png)
So for our jellyfish slime, we are thinking of a jellyfish with a ectoderm that is spherical rather than bell shaped. Comb Jellies are jellyfish that match this description fairly well. Most comb jelly species are roughly ball shaped as they float around through the sea. When stranded on land, they form small transparent blobs,
[](https://i.stack.imgur.com/Nf9tr.jpg)
Rather akin to the slimes we are after, but the slimes we want are large, with a height ranging from a meter to a foot, though Minecraft slimes can and do exceed human height. To retain shape for such a large body a fluid-filled body cavity in the shape of a torus is needed, surrounded by muscle to keep it under pressure and combat gravity wanting to flatten it while on land. The resulting shape will be wide in the midsection, flat on the bottom and rounded on the top, which matches all of its depictions excluding Minecraft for obvious reasons.
The inner walls of the body cavity will be lined with cartilage akin to ribs, which, like a shark, will replace bones. All of the organs, excluding the brain, will go in this body cavity. The brain will not be a single organ but instead work like an octopus, with the neural system being distributed across the body.
## 2. Locomotion
We now need a mechanism to propel the body upwards like we see in the games, kind of like a pole-vaulter. Imagine multiple rods similar to a vaulting pole lining the body cavity. You would need at least four, though six or eight would be better. In pole-vaulting, the pole is bent down to store elastic energy, which is then released, launching the vaulter into the air. A central band of much stronger muscle goes in the center of the slime (which is also the reason for the body cavity being torus shaped) which pulls the rods and when released, vaults the slime.
But, this only launches the slime upwards, to gain direction a change must be made. Instead of having one muscle we need many, one for each rod. Failing to use one muscle results in movement.
## 3. Feeding
Slimes are shown to possess a mouth but lack any means of getting food towards said mouth. However, slimes do possess another tool that could be even better, a slimy outer surface. Being slimy on the outside, food particles would just stick to the skin and move towards the mouth. The constant flow of mucus towards the mouth (which is then swallowed and excreted again to avoid waste) can be explained by having our slime be surrounded by small, roughly-beating hairs called cilia, like our lungs do, but on the outside.
[Answer]
Slime s are covered in an egg. So what I mean is that there is an outer layer of slime (pun intended) that is harder than the rest, it’s also what stops it from drying out. The shell is transparent and lightweight so the slime can move with out rolling. In the games a sword would just get stuck in the slime but it doesn’t! In Minecraft slimes multiply when they are killed so it shows that slimes carry their young. Even up to an age where the baby it’s self has babies. The shell supports the slimes and protects it. The shell would also have a certain amount of bounce so the slimes could move even before splitting.
] |
[Question]
[
There are several programs available that will generate a random map of an Earth-sized planet, complete with a choice of projections from sphere to 2-D representation.
Are there any available that will generate random maps for a setting like Larry Niven's Ringworld, that is habitable but effectively flat over distance scales large compared to the size of a normal planet?
[Answer]
*EDIT: as of the 2020s, this answer is largely out of date. The techniques mentioned, or even at least indirectly referred, however, are still applicable to this day, for creating believable maps.*
Only some examples from /r/worldbuilding. Not the most popular or useful ones, but you can make use of them.
* [Voronoi-based planet generator](https://i.stack.imgur.com/EIvTm.jpg) made in Unity. If I recall correctly, you can edit the final result. Might be a bit oversized for you, but this is the best stuff I've ever seen in the topic.
[](https://i.stack.imgur.com/GKghY.png)
* [This stuff called WorldBox](https://www.reddit.com/r/worldbuilding/comments/2bq8u8/worldbox_a_sandbox_map_generator/), generates islands for you. Importing out is possibly only by image editing, as I judge it, but I'm sure you'd do that either way. If you miss to find a download link, [here it is.](https://dl.dropbox.com/u/13290882/mkarpenko/games/WorldBox.swf)
[](https://i.stack.imgur.com/ceMeW.png)
* [An unnamed HTML5-based map generator](http://fpalm.se/map/) - obvious browser support + png export feature. A bit slow, recommended only on PC.
[](https://i.stack.imgur.com/of4wl.png)
* The game **Rimworld**. Several games generate amazing 2D maps in-game, I'd recommend looking for some options.
[](https://i.stack.imgur.com/qKVhq.jpg)
[Answer]
There's always Fractal Terrains from Profantasy.
[Fractal Terrains](https://profantasy.com/products/ft.asp#&panel1-1)
[Answer]
**Frameshift:**
Your objective is effectively impossible on current hardware and of no value anyway. Not counting any fancy encoding schemes I get 2pb just for the elevation data for the Ringworld and that's assuming 1 mile pixels. (I'm assuming 1 foot resolution. I don't recall how tall the spill mountains are, perhaps you can get away with 1pb with a coarser elevation measure.) Even if you had a system that could build it you don't have enough years left in your life to look it over.
Generate a flat low-resolution world. Decide where you want your action and generate higher resolution worlds for those areas. The fact that the rest of the world is extremely coarse is irrelevant as nobody will ever do more than see it from a great distance.
] |
[Question]
[
Here on the stack exchange we talk about dragons... a lot. We have discussed all the factors that would allow dragons to exist and yet, there is a question we have not asked. What evolutionary pressure would lead to realistic dragons?
[Answer]
**A proto-dragon will have to deal with escaping enemies and acquiring food just like every other animal.** Below is a rough process for how a dragon would evolve.
Before we get to dragons, let's consider the bat. We start with a quadrupedal animal then end up with two wings and two legs. At every stage, the animal is functional and with slightly higher performance than the previous generation.
[](https://i.stack.imgur.com/BL0Ej.jpg)
So let's look at the Welsh dragon (the image chosen because it forms a basic body plan for a dragon. Of course, there are a thousand different variations on dragons. I've chosen a very basic variety.)
[](https://i.stack.imgur.com/3eDft.png)
Starting with a basic six legged creature that lives in the trees. Getting from one tree to another is achieved by jumping and those creatures with increased surface area can jump/glide further, thus giving them a survival advantage. As time goes on, the skin between the middle leg and torso stretches to encompass an ever greater area (till the bones in the middle arms become to weak and break frequently enough to cause that sub-species to die off.) At the same time, the tail extends for balance and offers another place to increase surface area.
Claws on the hands and feet offer considerable grip on tree bark and also help with predation of smaller animals or insects. Secondly, being a predator means you only have to eat a few meals a week to get enough energy instead of munching on plants all day like an herbivore.
Scales could evolve from proto-feathers that consolidate to form protective armor during mating rituals. If there are other large predators, these scales will help there too.
After dragons achieve true flight, they can further differentiate to fill different ecological niches. Some will get huge, others will stay smaller.
**No fire**
I've got no answer for how dragons would evolve fire. Maybe I'll come up with something later.
[Answer]
My two cents:
Our starting point is a lizard. Now, there are already arboreal lizards that glide - of course their genus is named *Draco* - but I'm not using that because I have my doubts they will be able to produce powered flight, much less be able to maintain it at enormous sizes. I also want them to be venomous for reasons I'll get into later, so I think I'll use a monitor lizard. That's quite appropriate because giant monitors are one of the origins of the western dragon myths.
[](https://i.stack.imgur.com/cIdox.png)
So our venomous monitor lives in a jungle. Pickings seem nice except for a few problems. One: there are bigger dangerous animals on the ground like cats and pigs, which the monitor can fight off but at great danger to itself. Two: Those ground predators keep eating the same stuff the monitor eats. Many individual lizards would leave the jungle, but clever ones would see potential food and safety in the trees. Bird nests and beehives are easy pickings, even if bloody meat is a little more scarce. It's enough to live on.
[](https://i.stack.imgur.com/uO1Qx.png)
Our venomous lizard now lives in trees. It has developed a shorter, stronger torso, longer legs and more powerful claws to assist in climbing. Life is good, but there's a problem: falling hurts, a lot. Luckily, some especially long-fingered lizards are born with stretchy skin on their front paws, and use them at first to get an even better grip on the trees, but eventually this webbing expands around the arm and down the torso, allowing the lizard to parachute if it falls. Later they learn to jump from one branch to the other using the flaps to glide.
[](https://i.stack.imgur.com/UtSJx.jpg)
We now have something comparable to IRL "flying" lizards, but our bois are bigger, stronger, more bat-like and venomous. Don't forget the venom. Gliding is nice, but it's a real pain in the tailbone when you underestimate the jump and land on the manticore-infested jungle floor. Unlike the old gliding lizards whose puny wings come from fragile ribs, our flying monitors can make a little more use out of their muscular arms to pull more lift from the air. They start flapping, and over the generations they get better and better at it. Eventually the flying monitors are capable of fully powered flight.
[](https://i.stack.imgur.com/2A3pO.png)
Our true flying lizards are now much leaner and more elegant than their ancestors, with sleek, muscular bodies they soar away from the jungle where they hunt from an aerial vantage point, much like a bird of prey. They build nests in high places and their scales become many vibrant colors to attract mates and warn off predators. However, competition arises. The lizards, males mostly, must fight over territory, but escalating the conflict with venomous bites is too risky, so they learn to muscle each other out by grappling with their wings, lashing their tails around and butting heads. This style of fighting favors the larger ones, and those whose brow ridges become nubs, then spikes, then full horns.
[](https://i.stack.imgur.com/gYYFY.jpg)
The giant colorful horned flying lizards are well on their way to being apex predators, but there's still the problem of terrestrial predators being generally stronger, and at their size it's difficult to just fly away from a standing start.
**Remember the venom?**
Their venom remains a strong deterrent, but it only takes effect when the danger is already in biting range, or the other animal has evolved an instinctive fear of the lizards. So, our lizards start to do what some cobras have already done: they spit the venom to fester in the target's face from a distance.
[](https://i.stack.imgur.com/hcB4l.jpg)
This is better, although still not ideal, as to an oblivious predator it would at first feel like saliva and that might not be enough to safe the lizard. **FIRE** on the other hand, is immediately recognizable to any animal, as extremely dangerous. Like the bombardier beetle, the spitting lizard evolves two different venom types, that when mixed as when sprayed from the mouth, cause an intense chemical reaction, extreme heat and possibly even full-on combustion. The beast uses this new fire-venom to fend off other species, fight rivals of its own kind, flush prey out of hiding, and set wildfires so it can return to eat the charred corpses.
[](https://i.stack.imgur.com/SUQ9G.jpg)
**Now there is a giant, shiny, powerful, spiky, flying lizard that spits fire. And that's a godam dragon if I ever saw one.**
[Answer]
I think one of the best evolutionary incentives for dragon development would have been competition with other dragons. In a dragon's case, it's not so much a fight against prey as it is a fight against other predators; most likely the only cause of a dragon's death before humans would be because another dragon stole their food (or killed them for it). This competition could lead to bigger dragons who can bully the smaller ones, or flying dragons that can get to the prey faster. Fire breath may have been an early anti-dragon development, for which fire-proofing was evolved (thus, dragons aren't fireproof to defend against their own fire, but to defend against the fire of competitors).
After this competition is established, you can probably come up with many different evolutionary paths depending on where you want to split dragons off from the real evolutionary tree. I would suggest that they started out with the ability to fly, as that's a hard one to develop *after* you've grown to the size of a small mountain. So perhaps they were flying dinosaurs that survived the extinction event and *didn't* turn into birds.
[Answer]
Well, this is all dependent on what a "realistic" dragon is. It sounds like you are referring to some other Q&A on the SE. I am going to base my answer around a dragon being an extremely large lizard that breathes fire. I suppose I might want to consider wings as well, as that is a common things dragons are depicted with.
So how can we explain these evolutionary traits? With ***SCIENCE!***
How do we get an extremely large lizard? Well, thats easy. A predator's size is determined by the prey they eat. Small lizards eat bugs. Medium size lizards eat small mammals. Large lizards, like crocodiles and komodo dragons, eat buffalo. As their plant eating prey grow larger, so do their predators. And we know from dinosaurs, land predators can get very large.
Now on to breathing fire, what would cause that to evolve? Again, thats an easy one. What other reptile spits something out of its mouth? If you guessed a spitting cobra, you were right! Why do venomous snakes use venom? Many reasons, but often to incapacitate their prey and defend themselves. BTW, this is a great [documentary](https://www.youtube.com/watch?v=UDJaAHLdDK4) on the evolution of venom. A chemical based fire would evolve in the exact same way, for the same reason.
The last evolutionary trait is wings. That one is too obvious to go into.
[Answer]
Just answering the flying dragon aspect.
I believe that evolutionarily, learning to glide and not plummet straight to your death when jumping off a high surface is a precursor to flight. It's also useful, as mentioned above, in helping get away from predators.
In reverse, some birds have actually evolved with wings and have lost the ability of flight. Eg ostrich and penguins.
If you are wanting you dragons to have evolved from the existing evolutionary tree you can have them gain and lose the ability to fly several times over time. This way, you can incorporate several differing traits from non flying beasts into your various dragon species.
Just seen this video of the 'rare' footage of a peacock flying titled
'the mysterious flight of the peacock' (I think I got my phone to copy the correct link)
<https://m.youtube.com/watch?v=8fzO9NqYKLY>
That! Right there! Is the beginnings of a magnificent dragon! I actually think they could be halfway there already! Just got to work on fireproofing those feathers!
First off. It's not rare or technically flying. Apparently peacocks somehow get up in tree branches and on top of roofs (especially at night) and then glide off.
With what I've read and heard of peacocks, they are vicious, screeching, argumentative creatures (especially at 4 in the morning) and neighbours hate those birdlovers that rear them in the backyard. Sound like a dragon to you?
And to top it all off, in that video you have the basis of all the assumptions that dragons are vain.
[Answer]
When planning a plausible explanation of evolution of an imaginary creature, what I do is think in the evolution path in reverse direction. I mean: What is a probable ancestor, and the ancestor of that one, and so on. Because evolution usually takes little steps, something that was useful for one thing, maybe evolves in something useful for another thing.
Some thoughts about dragons:
* They could produce the gas, ot they could have some microbiome. That opens two different paths, everyone with interesting options.
* If they produce the gas: it could be that they fly and they have some gas exchange mechanism related with flotation (I use this in a Universe), like a submarine. Also it could be gas expelling to suffocate prays/predators.
* If you take the microbiome path: they develope wings before or after the first "fires".
* How gas turns into fire is related to how gas expelling evolves to fire expelling: They have some catalist in their teeth? Or in the throats? Or it's catalysed only by high pressure and temperatures? Every possibility arrise more questions that show possible evolutionary paths.
* At first, they expelled big amount of fire, or it was just a little amount? It was related to food digestion?
] |
[Question]
[
What would cause an area to get continuous rainfall (a la *Blade Runner*), and what implications would that have for other parts of the world?
Ideally I'd like to hear about both natural conditions that would cause this, and man-made activities that could result in this as a side effect.
[Answer]
Maybe it's possible to achieve with enough heat and moisture in the air but even our jungles aren't as rainy. Tropical rain forest is the closest we have to a constant rain.
Some examples:
* [Quibdó, Colombia] : 304 rainy days, 83%. With more than 8m of annual
rainfall.
* Kauai island, USA: has the Guinness record for the most rainy days:
[350](http://www.guinnessworldrecords.com/records-3000/most-rainy-days/) but receive more or less only 1m in a year. Rain is more frequent but less intense.
* The Indian state of Maghalaya is probably the wettest place on Earth. They receive they most annual rainfall. They can receive twice as much rain in a year than Quibdó but they have a dry season. Most of the rain come from the Monsoon.
Now let's look at Quibdó. It is always located under the influence of the [Intertropical convergence zone](https://worldbuilding.stackexchange.com/a/1395/147). This is a hot and low pressure zone where the rain converge. And lastly, it's close to the mountains. The hot and wet air is pushed but as it gain altitude it become colder and since cold air cannot contain as much moisture, it falls on the city. These are the main natural factors to consider.
* Needs to be in a low pressure area.
* Need to be close to the mountains with the winds coming toward the mountains. The city does not have to be at high altitude. In fact, it's better at low altitude = more rain.
* Ideally, it should not be too far from a large body of water. Moisture can be carried overland but the closer the city is from the sea, the more rain it should receive.
**Man made activities:**
* With water bombs...: I know it's possible to force the rain to fall using some chemistry
but I don't know if that could lead to side effects. Obviously, the
area past the city would receive almost no rain but it doesn't really
matter if it's a mountain. But the water they drink must come from
somewhere.
* Living in a dome: it would be very easy to control the factors generating rainfall. Moisture is natural. The rising air encounters the colder dome and transform into liquid water. With enough moisture and heat, you could achieve a water convection movement inside the dome. It might work but it would not be a pleasant place to live.
[Answer]
I don'no bout all dat at-moss-sheric stuff, but back in 2041, just south of Myrtle Beach, we had us a year n a half of hard rainfall. Every day, every hour, it rained and rained and rained.
Seems one of dem solar-sats, da energy capture satellites which NASA sent up in da thirty's, it got confused. Started beam'n down its microwave power to a spot just off shore, stead of to the solar farms out in Texas. Boiled up our ocean for months an' months. Caused the rain to fall mighty fierce. Even after de fixed it, the rain didn't stop for a long time. ...and the storms that followed a year latr... don't get me started, talk'n bout storms. I've seen some bigg'ens!
[Answer]
I'd say it is possible given the right circumstances and a slight modification to earth...though it might not be stable over a long period of time (decades).
The best pattern I can think of that would account for that is what occurs to the Pacific west coast. There is a weather pattern known as the 'Pineapple Express' that is driven by trade winds. Essentially the equatorial ocean waters receive a very constant heat (near Hawaii in this case) that creates a steady stream of clouds (can be referred to as an atmospheric river). These clouds are caught up in the trade winds and sent a bit northward as it travels towards land and eventually dumps it's rain all over Seattle and Vancouver. In winter months, Vancouver is well known for entire months of clouds and rainfall (from heavy rain, to a light misting) with people never seeing the sun. The grey blahs as we will. The seasons change here though and the trade winds shift north and south as different parts of the globe are heated.
On an earth-like planet that lacks the seasons (IE, less of a tilt), these trade winds could become essentially static, allowing for this pattern to maintain itself for an extremely long period of time. Climate change here on earth seems to be making these trade winds more prominent as is...more energy in the system appears to be making these trade winds stronger.
So add a few degrees to the world and lose the seasons...and I think you can have the effect you'd want here.
Not all too sure on man-made...storm seeding is a potential, but you require the clouds to do so. Sometimes the conditions just aren't right for rain to form..the water needs something to form around or it remains a gas. Storm ceding in this case would be delivering silver iodide to the clouds. These particles act as nuclei for water particles to gather around, form water droplets, and then fall as rain.
[Answer]
Yes. Consider a warm, rapidly spinning world and a big mountain range in the right place.
One big driving force behind weather is the fact that the air at the equator is moving much faster than the air at the poles, the faster the planet spins the greater this effect is. Thus a rapidly spinning planet is a windy planet.
Since it's warm we have a lot of moisture in the air over the ocean. The wind drives that moist air into the mountain range, it rises, cools and drops it's water. It rains as long as the wind blows.
[Answer]
It's a world right on the inner edge of its star's goldilocks zone. It'll be like Venus in a few million years. But for now it has cloud cover of 95% and it's raining almost everywhere most of the time. Some places all of the time. Probably too hot and humid for humans ( especially away from the poles) but for your aliens it's home sweet home.
] |
[Question]
[
Imagine a world covered in a shallow sea (usually only 4 metres or less) that has little land, where there is land its in the form of fairly small islands (less than 1sq KM)
This will be populated externally so it doesn't need to be life bearing.
Is such a world geologically plausible ?
What world creation scenarios could explain such a world ?
[Answer]
I'll say plausible (though I question the extremely shallow depth...200m not 4m maybe?), though perhaps not the most likely. Earth is unique (so far at least) within our solar system with tectonic plates, so it's more than feasible to have planets lacking this plate structure.
The problem you will face is how the planet releases it's heat. On planets without plate tectonics, you get very large volcanoes as the means through which it releases its heat (Olympus Mons on mars is a good example of the size these volcanoes reach like this). I've seen a theory that applies to Venus that see's the entire planets crust 'melt' from internal heat in a 200 million year long event...I guess a melted and reformed crust might look like this?, seems like a stretch though. You basically need a planetary body that's cool enough internally that it doesn't have the need to expel this heat. Best if the planet has no moons as they tend to cause gravitational effects that stir up a planets interior causing more heat...and no tide to move the water around, leaving it the consistent depth)
Planetary bombardment might be hard to explain away as well. Though not as true today, the galaxy used to be a messy place with asteroid impacts being nearly commonplace (look at the moons bombardment history if you want an idea of the timeline there). Craters leave deep impacts and large rings (might actually explain the island presence you are going for).
Planets are never really round...they have bulges and the sort (earth has 4 I believe) and the rotation of the planet tends to redistribute water as well.
Those are the issues...lets give this a go:
My preferred explanation for such a bodies existence is an impact event that rips apart a larger planet. You have a larger, cooling body that suffers a massive impact that rips a section of the planet away. This surface section ripped off doesn't contain the same heat and pressure as the larger planet once did, so you are working with a cooler interior to start
This planet fragment (now a planet in it's own right) then undergoes a massive volcanic event releasing a magma flow that basically extends planet wide, filling in the cracks and leaving the planet coated in a volcanic crust. Should be close to round at this point.
No clue how the water got there (perhaps released with the lava), but the planets water undergoes a 'snowball earth' style effect where the planet entirely freezes over (freezing effect is easy as the sun this planet orbits can easily undergo an extended cold/dormant phase). This glacial 'covered in ice' period works to further flatten the planet by covering it in a large mass of heavy ice. Sun goes back to normal and melts everything leaving you with a world that you are looking for. It might not be quite prefect, but a few millions of years of erosion with no forces such as volcanic or tectonic activity to reshape the world should continue to flatten it out. Marine life such as coral tends to help this as well...millions of years worth of shelled life remain can also flatten out the seabed as it settles.
Not sure on how feasible this is though...comments and corrections more than welcome.
[Answer]
Essentially what you are asking for is a world with a very smooth surface. So how do we get it? Gravity and erosion will both generally act to gradually smooth a planet's surface. Wind and water will chip away at exposed rock and deposit the sand in crevices, while gravity causes things to move downwards and flatten out in general. So what is it that creates mountains and valleys in the first place? Plate tectonics! On earth the continents move around on top of a liquid mantle and bump into each other causing mountain ranges and trenches to form. Volcanoes sometimes peak through the surface and create mountains as well. Geologists have a lot of terms for all of the different mechanisms that cause different formations, but all we really need for our planet to be smooth is for it to have cooled down to the point that its interior is no longer liquid. Without a molten mantle none of the turbulent processes that generate mountains and valleys will happen! As far as how to get your solid mantle planet I think the simplest answer is that the planet is very, very, very old. Time will cause the planet to gradually lose heat to the crust and space, and allow wind and water to erode all of the continents.
[Answer]
You'd be hard-pressed to get four-meter seas through any natural process -- the simple variation in planetary radius between the equator and the poles will exceed that.
On the other hand, if you don't mind your seas being a hundred meters deep or so, there's an easy way to get them: ice ages. Your planet has had a long (multi-million-year) ice age with a stable sea level. Rivers have produced enormous alluvial plains (think the Atlantic/Gulf coast of North America, only larger). Then, the ice melts.
You've now got three distinct geologic areas: the ocean deeps (areas that were ocean during the ice age), micro-continents (mountain ranges and plateaus during the ice age), and between them, enormous shallow seas ranging in depth from a few tens of meters to a few hundred.
[Answer]
It is believed that one of the major formative events in the Earth's history is the [collision between Theia and proto-Earth](http://en.wikipedia.org/wiki/Giant_impact_hypothesis). This had a massive effect on the planet's formation, injecting a vast amount of energy into the system and leaving us with the hot core and relatively volatile planet that we inhabit.
If that had not happened, we might have ended up on a colder and considerably flatter planet with far less geothermal activity meaning no plate tectonics to speak of and less by way of greenhouse gasses in the atmosphere. This might be a viable starting point for the type of world you are looking for.
If I were creating this world, I might then leave the planet covered in a ball of ice for most of its existence, to smooth it out a little further and then perhaps have changes to it's star heating it up enough to melt the glaciers and render it habitable.
] |
[Question]
[
Just what the title says, I'm trying to understand how ships would be built for seas on low-gravity worlds. I've searched around a little for an identical question but surprsingly turned up empty-handed. Questions like, [How would lower gravity affect motion?](https://worldbuilding.stackexchange.com/questions/53497/how-would-lower-gravity-affect-motion/53518#53518), [Designing vehicles for different gravities](https://worldbuilding.stackexchange.com/questions/132920/designing-vehicles-for-different-gravities), and [How would it feel to sail a Rocheworld ocean?](https://worldbuilding.stackexchange.com/questions/94906/how-would-it-feel-to-sail-a-rocheworld-ocean/94982#94982) either focus on different aspects of low-gravity and seas or different types of vehicles like surface & air.
---
### Wave properties & gravity
Intuitively, it takes more energy to create a wave of equal height on a planet with higher gravity than it does lower gravity. $U=mgh$, the higher the wave, the more potential energy, and potential energy depends on $g$. If $g$ goes down, $h$ goes up, when all else is constant. According to Wiki's page on wave energy, [here](https://en.wikipedia.org/wiki/Wave_power#Wave_energy_and_wave-energy_flux), the relationship between mean energy of a wave (per unit area), $E$ [J/m^2], and its height, $H$ [m], is:
$$E=\frac{1}{16}dgH^{2}, \quad H=\sqrt{\frac{16E}{dg}}$$
where $d$ [kg/m^3] is fluid density and $g$ [m/s^2] is gravitational acceleration. ($H$ is the height from crest to trough, not amplitude; $a=\frac{1}{2}H$) From the 2nd equation, you can see that $H\propto\frac{1}{\sqrt{g}}$. Assuming water's density is the same, the energy of a 1 m tall wave on Earth is ~612 J/m^2. Using the rearranged equation to solve for $H$, plugging in the same wave energy for 1/3 gravity, we get a wave height of ~1.7 m. The same imparted energy yields a taller wave.
Using [Airy wave theory](https://en.wikipedia.org/wiki/Airy_wave_theory), for waves whose amplitudes are negligible compared to water depth, we can find these relationships:
$$\omega\propto\sqrt{g}, \quad H\propto\frac{1}{\sqrt{g}}, \quad c\propto\sqrt{g}$$
The wave angular frequency, $\omega$, (inversely proportional to wave period) and wave speed, $c$, are proportional to the square root of gravity (grows smaller as gravity grows smaller), while the wave height is *inversely* proportional to gravity (grows larger as gravity grows smaller). The overall trend is that lower gravity means longer, taller, and slower waves.
---
### Types of ships
There really isn't a general, spherical-cow approximation of ship. There are many shapes and sizes of sea-going vessels, designed for different cargos, speeds, and voyages. I'm interested in two rough categories of vessel: large barge-types, traveling large distances under engine-power, of large cargo capacity for transporting bulk containers of goods; and smaller, lighter cutters, single-mast, traveling short distances under wind-power, carrying a light cargo & crew complement.
Assume any modern construction materials and design principles are available.
With the information I have here, I reason that large barge-types would be taller and have a lower center of gravity to account for the on-average larger wave heights, which are able to impart more of their wave energy to the hull surface area. I've heard of something called "parametric rolling", in which wave conditions affect the stability of a ship when the wave encounter frequency is near the ship's roll frequency, inducing a kind of resonance which sometimes causes ships to lose containers over the side. I'm not quite sure how this effect would change under lesser gravities.
As for smaller cutters, a lower center of gravity keeping the ship more upright in various wind & wave conditions makes sense, I think. Or, maybe not. Cutters would be, in a sense, proportionally smaller to the waves they're facing. There's often a trend of things being taller in lower-gees: taller people, taller trees, etc. I'm just not sure what would change. I have very little personal experience with oceans and ships and I hope somebody here has a better idea than I do lol.
---
If it matters, the gravity + atmospheric properties of my *specific* world are:
* $g$ = 3.34 m/s^2
* $P\_{sealevel}$ = 101,325 Pa
* $d\_{sealevel}$ = 1.26 kg/m^3
* $T\_{sealevel}$ = 280 K (note, mean ocean temp. will be cooler)
I ran the numbers to see if the sea water density would be drastically different under the different planetary conditions, and it wasn't. ~998 kg/m^3.
>
> [5th order polynomial approx.](https://www.omnicalculator.com/physics/water-density#:%7E:text=Density%20is%20usually%20denoted%20using,as%20the%20temperature%20or%20pressure.), T°C: $$d\_{T}\left(T\right)=999.83311+\sum\_{n=1}^{5}a\left[n\right]T^{n},$$ $$a=\left[0.0752,-0.0089,7.36413\cdot10^{-5},4.74639\cdot10^{-7},1.34888\cdot10^{-9}\right].$$
>
>
>
[Answer]
One parameter for ship design is hull speed or displacement speed which also depends on gravity.
$v\_{hull}=\sqrt{\frac{L\_{WL}g}{2\pi}}$
Where $L\_{WL}$ is the length of the waterline in meters. You get more drag when the bow wave is equal to the waterline length of the vessel. Basically as you increase speed you get more drag from the interference of waves. Hull speed was known for a long time, the more modern description naval architects use is the Froude number. A smaller gravity gives smaller hull velocity or a larger Froude number.
[](https://i.stack.imgur.com/dHcPB.png)
I think the implication is that you could think about having more hydrofoils or craft where you plane the hull. Basically minimize the area of the hull in contact with the water. Planing the hull can give a significant speed increase.
The other alternative is to make the ships longer to have them go faster. There are techniques to strengthen longer ships so they don't break, (for example the bow and stern supported by the waves, the middle unsupported) but with less gravity and the same strength of materials that may not be as much of a problem.
Ship stability is an issue, the period at which the ship would recover from a roll should get longer and recovery from being tilted would take a longer time with less gravity. So I am guessing that rolling, yawing and pitching would be more extreme. So with bigger waves and that maybe more sea sickness.
You might want to think through the center of gravity, center of buoyancy and metacentric height for the different ship designs you consider if you start changing the dimensions of the hulls significantly. In general the righting moment will be less with less gravity. Another stability criteria is the free surface effect if you have liquids on board. In lower gravity it seems like they could slosh around more.
Proportionally, it seems like the wind forces could remain the same for a given wind speed, and with less of a righting moment and bigger waves could make the dynamics more exciting. Even ships with out sails can get pushed around by the wind if they have enough area out of the water.
[Answer]
# Submarines
With more dangerous waves we can do three things. Either take them head on, making ships that battle the wave. Accept them, using ships that can ride the waves. Evade them, going over or under the waves and never having to deal with them.
As your question doesn't include air transport in a conveniently lower gravity, we choose submarines. They can travel under the waves and be practically immune to weather and wave changes.
As the density of water seems to be similar we have more advantages. The water pressure doesn't increase as fast with depth thanks to the lower gravity. That helps us make submarines that are much larger. Cargo ship size perhaps.
You might think to take advantage of the lower gravity to make cargo ships that put the real life versions to shame. Yet in real life we have set maximum sizes for a reason. We can already build larger ships, but harbours have no are barely any way to accommodate them. And as we see they are even in this Earthly climate susceptible to the weather, losing cargo or even whole ships. In short, there is no reason to build larger boats. But the lower gravity might make cargo submarines affordable and much safer than wave cresting alternatives.
[Answer]
TV tropes has a trope about the hardness of science fiction. BMF should ask themself how "hard" they want their story to be.
<https://tvtropes.org/pmwiki/pmwiki.php/SlidingScale/MohsScaleOfScienceFictionHardness>
Here is a frame challenge:
Can a world with a surface gravity of only 3.34 meters per second per second have an atmospheric presssure of 101,325 Pa, or one Earth atmosphere?
Earth has a surface gravity of 9.80665 meters per second per second (1 *g*), and a sea level atmospheric pressure of 101,325 Pa, or one Earth atmosphere. So your world has a surface gravity of 0.34 *g*.
Actually the amount of time that a world can retain whatever atmosphere it may produce or acquire depends primarily on its escape velocity, and not on its surface gravity. Since the escape velocity of a world is calculated using a different formula than its surface gravity, the diiference in surface gravity between two worlds will usually not be the same as the difference in their escape velocities.
I note that Mars, and Mercury, have low surface gravities and atmospheres much less dense than 1 Earth Atmosphere.
Mars has a surface gravity of 3.72076 meters per second per second (0.379 *g*), and Mercury has a surface gravity of 3.7 meters per second per second (0.377 *g*). Both are somewhat more than your desired world with 0.34 *g*.
The escape velocity of Earth is 11.186 kilometers per second. The escape velocity of Mars is 5.027 kilometers per second (0.449 that of Earth) and Mercury's is 4.25 kilometers per second (0.349 that of Earth). In those cases Mars has a higher relative escape velocity than surface gravity, and Mercury has a lower relative escape velocity than surface gravity.
So it is possible to design a planet with an escape velocity relatively higher than its surface gravity.
*Habitable planets for Man* Stephen H. Dole, 1964, discusses the escape velocity necessary for a planet to retain a dense atmosphere for geological eras of time and for oxygen to accumulate in its atmosphere.
<https://www.rand.org/content/dam/rand/pubs/commercial_books/2007/RAND_CB179-1.pdf>
Planets lose atmosphere when it either combines with other materials to be come solid instead of gas, or escapes into outer space. Gases escape into space from the topmost layers of the palntary atsmsphere, their exospheres, where gases are very thin and very hot. The temperatures in the exospheres of worlds are usually several times the temperatures at the sufaces of the worlds. And of course the hotter the gas particles are, the faster they move, and the more likely they are to move faster than the escape velocity of their world and so be lost into space.
ONpages 34 and 35 Dole discusses the ratio between the planetary escape velocity and the root-mean-square velocity of a gas in the exosphere. How long it takes the original amount of that gas in the atmosphere to be reduce to 1/*e*, or 0.3678796 of the original amount. depends on the ratio of the escape velocity divided by the root-mean-square of the gas's exosphere velocity.
Table 5 on page 35 shows that if the ratio is 1 or 2, the time to reduce the atmosphere by that amount is zero.
If the ratio is 3, the time to reduce the atmosphere is a few weeks.
If the ratio is 4, the time to reduce the atmosphere is several thousand years.
If the ratio is 5, the time to reduce the atmosphere is about ahundred million years.
If the ratio is 9, the time to reduce the atmosphere is approximately infinite.
Thus a comparatively minor change in the ratio between the escape velocity of a world and the root-mean-square of gas in its exosphere can make the difference between the planet loosing all its atmosphere almost instantly and retaining its atmosphere almost infinitely.
Of course in some cases atmospheric gaess can be replaced by sources on the planet as fast as they are lost into space. But obviously it would be a lot more probable for natural forces to replace atmosphere as fast as it is lost if it takes 100 million years for the atmosphere to be reduced to 0.3678 of its orginal amount than if it takes only 100 million seconds or about 3.2 years.
And the stellar wind can cause a planet to lose atmosphere if the planet doesn't have a magnetosphere to divert charged particles away from the exosphere.
But the escape velocity is much more important.
On page 54 Dole noted that the temperatures in Earth's exosphere are between 1000 K and 2000 K. Dole said that if the temperaturs in the exosphere of a planet never exceedes 1000 K, and the planetary surface is still warm enough for liquid water, a planet could retain a long term oxygen rich atmosphere if its escpe velocity was at least 6.25 kilometers per second (5 times 1.25 kilometes per second).
According to Dole's figures, based on his formula for relating the mass, density,a nd radius of a planet, a planet with an escape vleocity of 6.25 kilometer per second would have a mass 0.195 that of Earth, a radius of f.63 Earth radius, and a surface gravity of 0.49 *g*, considerably higher than the 0.34 *g* you desire.
If there can be considerable variation in the overall density of a habitable planet, it might be possible to design a planet which as a surface gravity as low as 3.34meters per second per second (0.34 *g*), and an escape velocity as high as 6.25 kilometers per second, 0.5587 that of Earth.
But there are limitations to how high or low you can make the average density of a planet which has a solid surface partially covered by oceans and partially above the oceans, as on Earth.
Earth has an average density of 5.514 grams per cubic centimeter.
Our solar system was four terrestrial type planets, of which Earth is the densest, and four giant planets which are largely composed of hydrogen and helium gases and so have low average densities.
Neptune has the highest average density of the known giant planets, at 1.638 grams per cubic centimeter, 0.297062 that of Earth. And Neptune doesn't have anything like a solid surface.
imagine a world with the same average density as Neptune but the same mass as Earth. To have the same mass as Earth with 0.297062 the density it woudl have to have 3.3663006 times the volume of Earth. 1.49872 is the cube root of 3.3663673, which is close enough. Since the average radius of Earth is 6,671.0 kilometers, the average radius of such a planet would be about 9,548.3451 kilometers.
According to this online surface gravity calculator:
<https://philip-p-ide.uk/doku.php/blog/articles/software/surface_gravity_calc>
The planet would have a surface gravity of 0.45 *g*, higher than you desire.
According to this online escape velocity calculator, the planet would have an escape velocity of 9.137 kilometers per second, about 0.8168 that of Earth.
Suppose that a planet has an average density of about 2.757 grams percubic centimeter, about half that of Earth. If such a planet had the mass of Earth, it would have twice the volume of Earth. Since 1.26 is the cube root of 2.00376, that is close enough. That planet would have a radius of about 8,027.46 kilometers.
Such a planet would have a surface gravity of 0.63 *g*, and an escape velocity of 9.965 kilometers per second.
So it looks like you need to use a planet less dense. But I am not sure that a world less dense than that could exist without having a lot of liquid, enough liquid that its solid surface would be covered by hundreds of kilometers or miles of liquid. If you want native land dwelling people on that planet to build boatsout of wood from trees on land, that would be no good.
There have been a number of other posts in various places where I have tried to calculate worlds which surface gravities as low as possible and escape velocities high enough to retain atmospheres for billions of years.
And maybe I can link to them.
Part Two: A titanic solution.
There is a world in our solar system which has an atmmosphereic surface pressure even higher than that of Earth, despite having a very low escape velocity, much lower than an habitable world should have. It is Titan, the largest moon of Saturn. Titan receives only about 1 percent as much energy from the Sun as Earth does, so it is much colder in Titan's exosphere than in Earth's exposphere, so Titan's low escape velocity of 2.639 kilometersper second, 0.2359 that of Earth, is enough to retain its atmosphere.
Of coure that means the surface of Titan is very cold, so water is frozen rock hard. The temperaturea and pessure on Titan is near the triple point of methane, so methan can be, and is, solid, liquid, and gaseous on Titan. Titan is believed to have many methane lakes of various sizes; The largest, Kraken Mare, is about 900 kilometers long, and even the smallest known ones are large enough for boating.
I note that the surface gravity of Titan is 0.632 kilometers per second per second, less than you desire, and that liquid methane may have different properties than liquid water. But hums owuld able to survive on Titan with breathing apparatus and temperature suits, and it might possibly be that their are lifeforms on Titan and/or similar worlds in other star systems, lifeforms which use liquid methane as their solvant instead of liquid water.
Part Three: The smallest possible habitable worlds.
Since Earth type life forms use liquid water, and liquid water requires a dense anough atmosphere, a planet has to be able to retain a dense enough atmospehre for geological eras of time to retain liquid water and thus have water oceans and lakes for the life forms. And you also want a planet with water oceans and lakes to sail on.
Recently some scientists have imagined how some types of planets could retain atmosphere andthus liquid water despite having much lower mass and escape velocity than previously believed.
Under some conditions, a planet as small as 0.0268 Earth mass could retain an atmosphere and liquid water for geological eras of time, according to their calculations.
<https://earthsky.org/space/small-rocky-exoplanets-can-still-be-habitable/>
But what's the difference from worlds used in earlier calculations, and what is the catch?
The discussion is about water worlds of low mass.
The orginal article: <https://iopscience.iop.org/article/10.3847/1538-4357/ab2bf2>
Says:
>
> We assume that the low-gravity waterworld has a pure water vapor atmosphere and a water reservoir fixed at 40% of the planet's total mass.
>
>
>
So the solid surfaces of those planet and moons are likely to be at the bottoms of oceans hundreds or thousands of kilometers deep. Such planets would not have native land dwelling intelligent beings to build boats out of wood, and there wouldn't be any trees to build old fashioned boats out of.
But space travelers from other worlds could bring their own boats and ships to such worlds to sail in their oceans. The study assumed that the atmospheres would be all water vapor from the oceans.
But ultaviolent light would beak up water vapor molecules into hydrogen and oxygen atoms. The hydrogen atoms would escape much faster than the oxygen atoms, so oxygen might accululate in the atmosphere and which might eventually become breathable.
And possibly the oceans of that world might develop floating islands of some type where land plants and animals might evolve, possibly including people who make baot sout of tree equivalents.
Part Four: Worlds With Roofs.
A world which has too low an escape velocity to retain an atmosphere naturally might be terraformed to have an artificial atmosphere and the terraformers might put a roof over the world to hold the atmosphere in.
There are several different hypothetical types of "shellworld" maegastructures. Two theoretical types of shellworlds are:
>
> An inflated canopy holding high pressure air around an otherwise airless world to create a breathable atmosphere.[5](https://iopscience.iop.org/article/10.3847/1538-4357/ab2bf2) The pressure of the contained air supports the weight of the shell.
>
>
> Completely hollow shell worlds can also be created on a planetary or larger scale by contained gas alone, also called bubbleworlds or gravitational balloons, as long as the outward pressure from the contained gas balances the gravitational contraction of the entire structure, resulting in no net force on the shell. The scale is limited only by the mass of gas enclosed; the shell can be made of any mundane material. The shell can have an additional atmosphere on the outside.[5][6]
>
>
>
The first type of shell world could have lakes and oceans on its surfice beneath the shell, while the second type could have water as well as atmosphere within its shell. Enough mass of water would form a sphere surrounded by the gas.
Part Five: Conclusion.
Asking for a world with surface water to sail on, an Earth like atmosphere, and a surface gravity of 3.34 meters pr second per second, causes some problems in designing the world which the OP didn't anticipate.
I hope that my suggested solutions to the problems will be helpful.
[Answer]
Waves will be larger, but not steeper. So wavelength will still be 7 to 10 times wave height. (~7 is where waves start to break.
Since a wave will be taller for a given energy, and wave height is a factor in how fast wind energy is transfered to wave energy, I suspect that waves will kick up a lot faster, and that dangerous waves will form on a shorter reach (distance the wind has over the water)
[Answer]
Well, sailboats are out because there isn't much righting moment to resist the heeling moment of the sails. Or the boat's have to be huge. There is a scaling law where RM scales with size a little bit faster than heeling moment does.
Sea wave size and shape and velocity are are all totally different. Linear wave theory, which is pretty useful on Earth, won't work as well. Boat wakes will also be very different. There won't be any "mill ponds", all the gravitational free fluid surfaces will look like a the inside of a washing machine.
] |
[Question]
[
**Scenario**
The straits of Gibraltar never quite opened and the entire Mediterranean basin is dry land apart from a few large salt water lakes at the lowest points ~5% by area. The Europe – Africa land bridge has been slowly eroded and is now just 2 kilometres wide and no more than 10 meters high at any point.
It is April 100 AD and a civilization similar to that of Rome holds sway over the lands of the Roman Empire and the whole of the Mediterranean basin.
A particularly high and fierce storm tide temporally breaches a one kilometre stretch of the centre of the bridge allowing a little salt water in and reducing the barrier height to just 1 meter above normal high tide level before retreating again. The recent breach is the first sign of the seriousness of the situation. The composition of the land bridge is a simple extension of the coastal rock on either side of the straights as we know them.
**Question**
Would a civilization similar to that of Rome have been able to understand the danger they faced and be willing and capable of taking effective action to prevent catastrophe over the short and long term?
**Out of scope**
Any arguments about the Roman Empire not being able to evolve without the Mediterranean sea. History would have been very different but it’s there.
No magical involvement.
[Answer]
The [Romans made spectacular dams](https://en.wikipedia.org/wiki/List_of_Roman_dams_and_reservoirs) which by itself is enough to read about for an hour.
Long seawalls (much longer than the Strait) were [under construction in the Netherlands](https://en.wikipedia.org/wiki/Westfriese_Omringdijk) even in Roman times and the principles involved there would be obvious to roman engineers familiar with what was going on.
The thing about this is that none of the lands we are familiar with would be threatened by the Mediterranean filling up, because none of them are under the Mediterranean. Italy is a long way from the strait - so far they would not immediately think that something at such a distance could affect them.
**The deciding factor here are the people occupying the basin east of the land bridge.** This world is not the ancient world plus a huge empty seabed. That seabed would be loaded with people, cities, farms, etc. If the Iberian Romans / North Africans who lived next to this breach realized their farms and cities could be flooded, they would be extremely motivated to fortify that wall, with help from the capital or not. Even the Dutch barbarians figured that out.
But if there was no-one east of the land bridge because it was a worthless salt marsh, people might not worry too much about it flooding. It might not be until it started filling in earnest and the gap was huge that the civilizations might do the math and figure out what would be next. It might then be too late.
[Answer]
Would the Romans be capable of understanding the threat? Of course they would. This civilization spawned generals, statesmen, poets, philosophers, etc. and left a legacy behind still remembered today (2000+ years later). Those people did not think *small*. In fact, they conquered a good chunk of the world. They were innovators, and incredibly ambitious.
Now, that being said, could they take on the ***ocean*** and win? Could ***we***?
If the land bridge was being eroded at a particularly narrow point, I believe that the Roman civilization would rally, and implement a pretty inventively engineered solution to the problem. They knew all about cement, and were experts at building fortifications, roads, and other infrastructure (such as aqueducts, and sewage systems).
As far as taking on a grand engineering project is concerned, that's not really an issue. If the Emperor decides that something should be done, then the entire might of the empire will be thrown against this challenge.
The Roman empire did not only have access to vast resources, but they also made extensive use of slave labor (plenty of those around at the time), as well as having access to many trained/skilled engineers (trained in the legions).
] |
[Question]
[
This is a world without humans (so no problems with competition for space, etc.), and where the apex species is a quadruped [obligate carnivore](https://en.wikipedia.org/wiki/Carnivore#Obligate_carnivores) with an intelligence roughly on par with that of humans on Earth. One major difference is that they don't have hands, only paws (which may over time evolve to be more dexterious), so they lack the fine manipulation ability of humans.
Being obligate carnivores, these creatures have no reason to, for their own needs, develop farming. Instead, they (essentially free range, but otherwise not unlike how humans do it on Earth) herd livestock, upon which they prey and on which they rely as their primary source of food. The livestock is monitored and protected, but generally expected to (within rather wide geographical boundaries; these creatures moving and moving with their livestock) find their own food. The creatures keep their livestock within areas that are known to be relatively safe, both from others of their own kind as well as other predators.
Would it be reasonable for these creatures to develop such animal husbandry without ever developing any kind of (plant) farming techniques, either in the past or in the future, assuming no massive changes to their biology? Failing that, how could circumstances be arranged to prevent developing farming for as long as possible?
The level of civilization of these creatures that I have in mind is mostly, in terms of what we've seen on Earth, a hunter/gatherer level, with maybe low levels of technology (think simple tools such as, for example, those used by apes and ravens on Earth). Think more along the lines of early humans on the African savannah, than banking salespersons in large cities in Europe or North America.
[Answer]
They will develop animal husbandry first. There is no issue with that. However you need one more thing to keep farming from ever happening to supplement food production. You need a highly nutritious (for the livestock) plant that is the most efficient growing plant in all conditions and environments. If such a plant does not exist, the group that grows food more densely for the livestock can support more livestock and hence more population.
There are non-dietary needs that can be satisfied by farming as well. Dies, cloth, medicine, drugs, alcohol, building and heating supplies, furniture etc.
So never developing farming is a stretch of plausibility.
***Edit***
The OP has updated to change the biology to lack hands. I think an apex predator with no hands will have little need to develop tool using/or advanced intelligence. However if they do get to that level of intelligence few things will stop them from using tools, and developing agriculture.
The biggest show stopper will be if they are highly solitary creatures. A mouth, teeth, tongue, lips and jaw work as a fairly deft replacement for a singular hand. Some species (goat) have a split prehensile upper lip that acts as two thumbs/fingers. So it would require two or more co-operating together to become as adept at tool creation as a single human would. (Long term the team work tool building would probably become better).
Their tool evolution would initially be spurred by combat within their species. If their claws/jaws are lethal weapons then they would start with armor instead. Tying stones/wood/bones around the neck and other vulnerable spots and common targets would increase survivability.
[Answer]
I think that developing animal husbandry without farming is a definite possibility. It could easily come before farming; however, the likelihood of an intelligent species avoiding the development of farming altogether is not very reasonable. There are quite a few reasons why farming is a likely development for intelligent creatures, even if animal husbandry is satisfying the creatures nourishment needs.
**There are many other uses for plants besides food**
Plants can be used for a wide variety of purposes other than just food. Spices would likely be discovered and cultivated to flavor the food obtained from the animals. Leaves and husks are often used in modern cooking as containers (banana leaves and corn husks are very common). Outside of food plants provide fibers for textiles, pigment for dies and paints, materials for tools or building, and chemicals for industry and medicine. Plant cultivation also produces food for domesticated animals and allows intelligent creatures to raise them more effectively. The variety of uses that plant life offers are not likely to be covered through animal husbandry alone.
**Farming is often more efficient than animal husbandry**
These creatures are omnivores, and while they might prefer these creatures that they eat to other food, they also will take the easiest path to survival. Plants grow and produce much faster than animals do. Even the fastest maturing animals take months to grow large enough to be used as food. Plants can produce much more food, often more quickly. Plants also require less resources. Soil, sun, and water are often the only requirements. Animals are less efficient energy wise than plants (see [the energy cycle](http://hyperphysics.phy-astr.gsu.edu/hbase/Biology/enercyc.html)). Also, plants grow and produce using much less space than animals. In the area it would take to grow a cow to maturity, a farmer can likely produce much more corn. Also, it is usually less effort to harvest and cook plants than it is to kill an animal and prepare it for consumption. In nearly every way it is more efficient to produce food through farming than through animal husbandry.
**Intelligent creatures are inquisitive and often desire variety**
If the efficiency and utility of plants is not enough to inspire their cultivation, intelligent curiosity might be. These creatures would likely desire different tastes and experiences. They would likely see plants sprout and grow and would wonder if they could control it. Regardless of their other motivations, they would probably develop farming for no reason other than it being possible.
That all being said, I do think this situation is *possible*.
**Some ways to prevent the development of farming:**
You would need to have some very energy efficient animals for these creatures to raise. Perhaps smaller creatures that can gain energy from the sun? An enormous algea-like fish or lizard seems plausible. Basically make the creatures as easy to domesticate and raise as a plant would be.
Making the animals produce other materials besides food would be another good idea. Perhaps their bones are an excellent building material? Their skins an incredibly useful clothing material? You could have them produce venoms or secretions that are powerful medicines too. Any waste could be used to feed the other animals. Basically this animal (or even better a group of very similar animals with slight but important differences) should be a swiss army knife of usefulness.
I think a good example of what I have in mind is found in [slime rancher](http://slimerancher.com/), a game where creatures called "slimes" provide incredibly useful resources and dominate the surface of an entire planet.
**Anyway, I'll reiterate the point**:
Is a intelligent society using animal husbandry but not farming reasonable. *No*. But, with the right amount of thought and creativity this situation could *be engineered to happen* in your world, which would result in a very cool and interesting alien society indeed.
[Answer]
Farming and animal husbandry developed around the same time in the Near East. But the same people did not develop both at the same time. Pastoral nomads on the steppe did not have farms - they were nomads! They moved their herds from place to place. I [read recently](https://www.world-archaeology.com/issues/by-steppe-desert-and-ocean/) that it was these people who invented the wheel, because wagons were useful in toting their stuff, kids and old folks around. Likewise the horse. These pastoralists were not obligate carnivores but the excellent teeth in their skeletons suggest a low carbohydrate diet - milk, blood and meat being the probable staples.
There are still people who live as pastoral nomads today. There is nothing wrong at all with your creatures living like that.
[Answer]
# "Ever" is a very difficult word.
The limitation is greatly helped by their lack of dexterity suggesting that they're not going to build complex tools to help with the task, but even little things like identifying plants that are poisonous to their herds and killing them as they travel would be steps along the line to farming.
This behaviour would fall somewhere along the transition between true nomadic herding and [transhumance](https://en.wikipedia.org/wiki/Transhumance), where seasonal pastures are used.
The next step would be removing plants that are of no interest to the herds or overrun the grasslands they need for food. At what point does this sort of behaviour translate into cultivation? Since their primary plant of interest is grass (or equivalent) they never need to sow seeds, but they can still work towards effective monoculture farming just by elimination of plants of no interest.
# Population limitations
Population of a species is primarily limited by food supply. A large tribe with a large herd would be able to expand, though at some point they'd exceed the number of people their herds could support. This would give an advantage to a farming tribe with greater supply of food for the herds to allow the herds to grow at an equivalent rate. To prevent this advantage the population would have to be limited by some other mechanism than food limitation.
# Drought
The rains didn't come, the grass didn't get the autumn/winter/spring growth, there's ever less food especially for those moving where another tribe has moved ahead of them. A tribe who had farmed and stored food would still be able to feed the herds from the store, again an advantage over the nomads. Possibly offset by allowing them to travel great distances relatively quickly, but it would still require quite low population density so they're not treading on each other's toes.
# Immobility
Possibly a large portion of the group were injured in a conflict or are elderly forcing them to remain in one place for longer than normal and work to improve the local pasture for the herds to survive.
# Rich grasslands
The tribe has wandered into a temperate region where they no longer need to be nomadic. As long as they do a bit of basic ground clearance to get rid of the brambles and deadly nightshade they can settle down and build.
---
There are many factors that could cause the tribes to settle into some sort of farming pattern. Probably initially via transhumance and improving the pastures to which they will return next season, but also through more immediate internal or external pressures.
[Answer]
I think they would adopt a transhumant lifestyle, moving with their livestock between summer and winter pastures. This way the plants regrow without farming.
Your obligate carnivores would adapt their diets to (the equivalent of your world to) milk, butter, cheese, etc. which are very nutritious and don't require killing your animals.
] |
[Question]
[
What technology will humanity use the first time it moves a planet?
In the near-ish future, humanity has colonized Mars which has since become self-sustaining and independent, as well as various other solar system bodies. The asteroid belt is a principal source of resources, and a mature infrastructure exists for prospecting and mining, and of course delivering materials to colonies where they are consumed.
In a treaty that seeks not just to redraw lines on a map but reshape the map itself, the King of Ceres has formed a union with the Federated Republics of Mars, and this is to include **physically relocating [Dwarf Planet Ceres](https://solarsystem.nasa.gov/planets/ceres) to become Mars' Moon**!
This is politically brilliant, as the rest of the Belt, rather than being sore at the loss of a major piece of territory, is more excited about how much *money* they will make from contracts related to humanity's first megaproject.
The orbit injection must occur within 30 years (but shaping of the orbit may continue beyond that time).
How might this be accomplished? What technology (available to the described civilization) could be used? Please broadly describe the way the plan would work out.
The specific engine technologies available to them is the answerer’s choice. It should be something forseeable today as real science without breakthrough physics. (So, no [emdrive](https://space.stackexchange.com/questions/12626/why-dont-we-put-an-emdrive-in-space/12647#12647), no anti-gravity, no telekinesis, no [negative matter](https://en.wikipedia.org/wiki/Negative_mass#Runaway_motion).)
---
This post is the result of [this lesson](https://worldbuilding.meta.stackexchange.com/a/4890).
See also: The [energy requirement](https://worldbuilding.stackexchange.com/a/66272) of changing planets’ orbits has been discussed previously.
Here are [some rocket engines](http://www.projectrho.com/public_html/rocket/enginelist.php#id--Pulse--Inertial_Confinement--Magneto_Inertial_Fusion), with numbers, food for thought and common vocabulary. However, don’t limit yourself to [only rockets](https://en.wikipedia.org/wiki/Solar_sail)!
[Answer]
Hoo boy. This is one serious orbital mechanics problem.
The most energy-efficient method of getting a spacecraft (or, in this case, an asteroid) from one roughly-circular orbit into another is with a [Hohmann transfer.](https://en.wikipedia.org/wiki/Hohmann_transfer_orbit) For moving Ceres into Mars's orbit, this will entail firing thrusters on Ceres directly opposing its direction of motion so that its perihelion (its closest approach to the Sun) just touches Mars's orbit, waiting until Ceres reaches that point, then firing the thrusters again to circularize the orbit.
In order to actually have Ceres fall into Mars's orbit, though, the maneuver must be initiated at exactly the right time, so that when Ceres completes its half-of-an-ellipse transfer orbit, Mars will be right there waiting for it. Ceres has an orbital period of 4.60 Earth years, while Mars's year is only 1.8808 Earth years. They line up about every Mars year and a half, and the transfer itself will take less than half of a Ceres year. If there were rockets planted on Ceres' surface right now, that means Ceres could be in orbit around Mars within 8 Earth-years in the worst-case scenario, where the most recent launch window just recently closed. There's plenty of time to prepare.
The most important quantity in orbital mechanics is delta-V, which basically just measures the amount by which your spacecraft (or asteroid) needs to change its speed, which, in turn, determines how much fuel you need, how much that fuel and the engines used to burn it will weigh, how much more fuel you need to move all that fuel around, etc. It's used a bit like how distances are used when traveling around the Earth.
That Wikipedia page gives the delta-V for the Hohmann transfer as follows:
$$\Delta v\_1 = \sqrt{\frac \mu {r\_1}} \left( \sqrt{\frac {2r\_2} {r\_1+r\_2}} - 1 \right)$$
$$\Delta v\_2 = \sqrt{\frac \mu {r\_2}} \left( 1 - \sqrt{\frac {2r\_1} {r\_1+r\_2}} \right)$$
where $\Delta v\_1$ is the delta-V needed to put the asteroid into the transfer orbit, $\Delta v\_2$ is the delta-V needed to synch that orbit up with Mars, $\mu$ is the mass of the Sun multiplied by the gravitational constant G, $r\_1$ is the radius of Ceres' current orbit, and $r\_2$ is the radius of Mars's orbit.
Plugging those equations into Wolfram|Alpha, we get $\Delta v\_1$ = 2.814 km/s and $\Delta v\_2$ = 3.272 km/s, for a total of 6.086 km/s of delta-V.
That's actually not a whole lot, in astrodynamics terms. It takes more than that to reach low Earth orbit.
But Ceres is big.
It has a mass of 9.393×10$^{20}$ kg, so changing its velocity by 6.086 km/s would require an [impulse](https://en.wikipedia.org/wiki/Impulse_(physics)) of 5.76×10$^{24}$ newton-seconds.
In order for a Hohmann transfer to work, the rocket burns at the beginning and end of the maneuver should ideally be instantaneous. This, of course, is impossible without destroying the asteroid and killing everyone on it; but [nuclear pulse propulsion](https://en.wikipedia.org/wiki/Nuclear_pulse_propulsion) is probably about the closest you'll get without going well beyond the near future.
The engineers of [Project Orion](https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propulsion)) concluded that a nuclear pulse drive based on their design could potentially reach a specific impulse of up to 100,000 seconds. Specific impulse, by the way, is a measure of the efficiency of a rocket engine. A specific impulse of 100,000 seconds means that a sufficiently-refined Orion drive could support the weight of its own fuel in Earth gravity for about 100,000 seconds.
The amount of fuel actually required to pull off this maneuver can be derived from the infamous [Rocket Equation](https://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation):
$$\Delta v = I\_{sp} \cdot g \cdot \ln \left(\frac {m + m\_p} m\right)$$
where $I\_{sp}$ is the specific impulse, $g$ is Earth's gravity, $m$ is the mass of Ceres, in this case, and $m\_p$ is the mass of the thermonuclear bombs serving as propellant.
Solving this for $m\_p$ gives
$$m\_p = m \left(e^{\frac {\Delta v} {I\_{sp} \cdot g}} - 1\right)$$
Invoking Wolfram|Alpha once again indicates that you'll need 2.72×10$^{18}$ kg of nuclear weapons to start the transfer orbit, and 3.16×10$^{18}$ kg of them at the end. And that's if you get someone to restock your asteroid-ship with the second batch of nukes midway through.
Plus whatever you'd need to actually get the asteroid into orbit around Mars, which depends on how close you want it to orbit.
Good luck!
[Answer]
To get an idea of what sort of numbers we're looking at, I figured I'd look at the "big dumb rocket" method: what sort of scale are we looking at to do a straight Hohmann transfer orbit from Ceres to Mars, ignoring the plane-change that Michael Kjörling mentioned in his comment to the question.
I found an [online Hohmann Transfer calculator](https://instacalc.com/42836) and plugged in the numbers to move an object from Ceres's orbit to Mars's, and got a result of a bit over 6 km/s of delta-V needed. Ceres has a mass of roughly 9.4 × 1020 kg, so we're looking at something like 5.64 × 1024 Ns of impulse needed to get Ceres into the same orbit as Mars. Which is a lot.
The Space Shuttle Solid Rocket Boosters, the largest solid rockets ever launched, burned 500,000 kg of propellant at an ISP of 268 seconds (in vacuum). If we strapped one of those to Ceres pointing straight up and lit it off, we'd get [1.75 × 10−12 $\frac{m}{s}$ delta-V](http://www.quantumg.net/rocketeq.html). We'd need something on the order of 3.5 × 1015 SRBs to get the delta-V needed to move Ceres into Mars's orbit.
If you had some mythical rocket engine that could produce an isp of 10,000, you would still need to shove about 6 × 1019 kg of fuel into it. Or if you're allowed to use Ceres itself as fuel, you're going to arrive at Mars with about 5.6 × 1019 kg less of it than you started.
There are almost certainly more creative ways to do this, involving lasers or slingshots past Jupiter or other things like that, but any plan that's going to move almost a sextillion kilograms of dwarf planet around is going to need a *lot* of energy. And it's going to need to do so *very* precisely, to prevent Ceres from slamming into Mars or breaking up due to the forces involved. So, I'm not saying it's *impossible* to move Ceres into Mars's orbit, but I don't think doing so is within the "near future" of humanity unless we make some *astounding* breakthroughs before then.
---
Another way of looking at it: Ceres's [specific orbital energy](https://en.wikipedia.org/wiki/Specific_orbital_energy) is −161.2 MJ/kg. Mars's is −292.8 MJ/kg. Thus, moving Ceres to Mars's orbit requires 131.6 MJ/kg of energy at a minimum. As mentioned earlier, Ceres's mass is about 9.4 × 1020 kg, so a total energy expenditure of roughly 1.237 × 1029 J of energy would be required. The Sun emits about 3.828 × 1026 J/s, so you'd need to harness the entirety of the Sun's output for over five minutes (323.14 s) to move Ceres into its new home.
Congratulations! Your civilization is a [Kardashev 2](https://en.wikipedia.org/wiki/Kardashev_scale)!
] |
[Question]
[
The US Military is publicly preparing to [deploy +100 Kilowatt](http://dailycaller.com/2014/12/10/watch-the-u-s-navys-new-laser-weapon-take-out-two-ships-video/) laser systems on [its potentially vulnerable surface ships (see linked question)](https://worldbuilding.stackexchange.com/questions/26138/do-surface-warships-have-a-future). Which probably means that it has secret prototypes and special service weapons that can output in excess of 1 Megawatt. These weapons are capable of blasting drones out of the sky and small ships out of the water in a matter of seconds. The reported cost per shot is somewhere in the neighborhood of $1, thousands and hundreds of thousands of times cheaper than shells or missiles.
While there may or may not still be issues with bad-weather performance of these systems, there seems to be a clear upward trend in the capabilities and cost-effectiveness of laser systems, with a corresponding decrease in the system size and toxicity.
Now, since the speed of light is much much higher that that of any aircraft, does if follow that extraordinarily powerful lasers will make current types of aircraft obsolete? Are aircraft essentially sitting ducks to these weapons?
[Answer]
Aircraft already have to deal with deadly weapons nearby capital ships, they already cannot enter the visual range of battlegroups. Its not like you bomb destroyers using dumb bombs a la ww2. A major factor on the development of anti-ship aircraft was the area denial weapons aboard combatant ships. We usually talk about standoff weapons while talking about antiship missiles. This laser wont change much. A SM-2 missile fired from a destroyer reaches much longer ranges than such laser and denies the air space around the carrier battle group since the nineties (or before).
Those lasers will be used against anti-ship missiles, the aforementioned standoff weapons. Russians developed a plethora of supersonic antiship missiles and deliver means (subs, ships, aircraft, shore etc). Theres no real qualitative change from a phallanx/aegis combination or a laser/aegis, but a quantitative one, the laser is more effective than a chaingun at destroying incomming missiles.
Russians dealt with this problem by using saturation strikes, and so, this laser, in the end of the day will make any future attacker need to allocate more missiles per battlegroup in order to ensure a high probability of killing the carrier. Besides that, this laser might be used against chinese ballistic anti-ship missiles, wich are, currently, almost impossible to deter. So far so good, this laser does not change a lot in the possible naval battles of the future.
Russian missiles like sunburn/moskit fly at 3 times the speed of sound and can autonomously detect/track/engage ships in a battlegroup without human intervention. You might very well consider a sunburn missile as a kind of drone (all elements of a drone are there).
In other words, all this discussion was done under the wrong assumptions.
[Answer]
# No. Even with advanced lasers, Aircraft can still be feasible, provided the designers of the aircraft build with laser defense in mind.
What kind of defenses could you put on a plane that could help protect it against high powered lasers?
Well, let's first take a look at how the high powered laser would destroy things.
It's most likely that it would heat up target enough that it either
* fries the internal components
* Melts the outer layer and then the inner components
* Some other sort of **heat** related damage
All of which really boils down to just "heat damage".
Depending on the strength of the laser, here are some options that could be installed on the plane to defend it.
**1) Heat shields**
Think space style heat shields. As in space shuttles. The shielding they use on those ships are designed to soak up ridiculous amounts of heat - by putting that stuff on our planes, assuming sufficient plating and possibly a new method of propulsion to help with the weight increase, it is possible for the planes to survive the lasers since the shield will simply absorb the heat. Graphene plates might also work for this, since those tend to absorb heat very well, Ceramics being a third possible option.
**2) Rotating armor**
Heat lasers have a big flaw over all - it needs time to heat up the target. So all we need to do is make it so that the laser cannot stay on the same area long enough to heat up the target. Thus, I propose "rotating armor". By having armor plates that shifts around all the time in random motions (probably machine controlled), the laser will constantly be targeting a "cool" area that it needs to heat up, but by the time it even gets slightly hotter, that area has moved away and the laser is now targeting a new spot on the plane. Meanwhile, the previously targeted area is cooling down.
**3) Ablative armor**
Ablative gel/armor can be used "short term" to protect your plane while it quickly flies to the target to blow it up. Although this basically is just a different type of heat shield, I thought it different enough to give it its own number. :P
**4) Shrouds**
The laser needs to be able to target the plane in order to hit it. So all we need to do is stop the targeting. Before flying your plane into the defended area, fire "shroud missiles" mixed with actual missiles into the area. Let the enemy's lasers take out all the missiles (because if they don't take out all of them, a real one might be allowed to land). As the shroud missiles are destroyed, they should spread some sort of dense cloud of material over the area, and assuming you shot enough of them (or the clouds of X are large enough), just fly over the material and use the material as a shroud between the plane and the lasers. Since the lasers are (probably) stationary, you can just drop bombs (or large rocks kinetic projectiles) on where you think they should be to disable them.
**5) Mirrors**
How about just a mirror coating? Assuming energy density damage threshold in common dielectric coatings is $\approx 14 \;\frac{\text{J}}{\text{cm^{2}}}$ for a $20\;\text{ps}$ pulse ([According to this site](http://www.thorlabs.com/NewGroupPage9.cfm?ObjectGroup_ID=139)), and assuming that the laser is a continuous wave laser, it would have a power density of $7 \cdot 10^{11} \;\frac{\text{W}}{\;\text{cm}^{2}}$. (Power / Area = Power Density) Assuming a $\approx 10 \;\text{cm}^{2}$ area for the focal point (at long distances), you'd get $10^{4}\;\frac{\text{W}}{\;\text{cm}^{2}}$, meaning that the mirror coating would indeed protect the plane against such a laser.
**6) (This one is just speculation, I have no idea if it would work and it's just an idea I had) Prisms**
Assuming that in the future, we can manufacture prisms that don't break under high powered lasers, you can cover your plane in a layer of prisms. The idea is to "bend" the laser away from the body of the plane using that layer of prisms. Since the prisms don't move relative to the plane, assuming it was placed properly the plane should be completely impervious to lasers as the lasers would just bend around the plane and never hit it.
But then again, you could just use a really big prism as a frontal shield when flying towards laser protected areas... Just make sure you blow up the lasers before leaving ;) .
[Answer]
**It does not follow that lasers will end aircraft as we know them.** Lasers work by inducing heat in a target which can't be attenuated quickly enough to prevent damage. If this heat can be reflected, ablated or avoided all together then a beam weapon is useless.
**Reflection**
This is perhaps the easiest route. Developing highly reflective coatings effective against IR, visible and the longer end of UV [is a common thing](http://www.edmundoptics.com/technical-resources-center/optics/metallic-mirror-coatings/). An aircraft will still need conventional camouflage so these highly-reflective coatings will need to be underneath normal paint.
At the bare minimum, an IR reflective coating will need to be added to all windscreens and cockpit canopies. Even if the aircraft may survive a laser strike, the fragile retinas of the pilot may not. A blind pilot is a dead pilot.
[](https://i.stack.imgur.com/OSEst.gif)
**Ablated**
An ablative layer could be added to the underside of the aicraft. This carries a weight penalty and may interfere with any stealthy coatings on the plane. Space shuttle style tiles or coatings may help by absorbing the heat of a strike.
**Avoided**
Combat aircraft already have countermeasure systems for detecting and defeating radar guided and IR missiles. Laser detection systems could also be developed and deployed to aircraft. When the laser detection system triggers, an evasion autopilot may take control to jink the aircraft in unpredictable patterns and get out of the laser's engagement area. Radar acquisition usually presages a laser "launch" though not always.
**Ultimately, beam weapons win**
This is an age old competition complex. The attacker can bring bigger weapons to bear and to survive the defender must wear/build ever heavier armor. Megawatt or gigawatt beam weapons simply aren't blockable or avoidable. And the ability of sensor networks to accurately track targets is only going to improve over time. There may be a short period where beam weapons can be mitigated by aircraft countermeasures but not for long if beam weapon power continues to increase at previous rates (and likely they will exponentially increase in power.)
[Answer]
**Essentially, yes.** With nuclear engines to power it up, the laser systems' effective rate of fire (rather low at the moment for current systems) may end up being limited only by equipment cooling requirements and the time it takes the turret to turn and acquire a new target. Moreover, unlike other projectile-based solutions, once a target is acquired, damage starts occurring instantaneously. With a battery of a few dozen of these miniaturized puppies, you can effectively blast away anything that enters your skyes from a range of 5km (horizon distance at sea level) to 100km (horizon at aircraft cruising altitude).
Aircraft cannot match the power supplies or sheer quantity of lasers on a floating (or fixed) platform. While some posters state that using superreflective materials would help, I disagree. Current beams can achieve unbelievable focus, properly ranged (and you have a laser ranging system, hehe), down to beam sizes mere nanometers across. Even the best mirrors have less than 100% reflectiveness, and would vaporize locally essentially instantly at 10MW power levels and above. This would ruin the mirroring effect further, and soon ablation effects would become significant.
Laser platforms in place would effectively create an aerial area denial zone until silenced by heavy hyper-velocity kinetic impactors (too heavy to laser-vaporize, too fast and heavy to use a Phalanx-like system against).
[Answer]
No. Powerful lasers don't mean the end of *all* aircraft. It means that usa is preparing to sell it's next generation of fighters with a powerful initiative.
As Aify and Green have mentioned before me, evolution is a constant process (even when it comes to weapons) and only the fittest survive. So all the *weak* species of aircrafts are going to get extinct pretty soon, agreed. But what about the species which are fit enough to survive? I will not be going into details here as Aify and Green have already discussed the matter in detail. My idea is that usa airforce has already finished building fighters which have laser defense system in them (whatever the method). So once all warships have the laser canons, usa would be in prime position to obtain orders for it's next generation of very expensive aircrafts.
[Answer]
Here's another way to fight laser weapons: A smoke screen. Just have your aircraft generate lots of smoke. That has two effects: First, it makes aiming harder (because you no longer see the aircraft), and second, it blocks the laser (because the laser power goes into heating the smoke instead of the airplane). A disadvantage is that smoke trails will be a dead giveaway that there's something in the sky, so you'll only generate that smoke as soon as the enemy knows you are there (e.g. by detecting their radar).
[Answer]
Let me start with the obvious reason why combat aircraft will remain in use - *my aircraft* will still be needed to operate in *my airspace* after *my lasers* have established air superiority for *me*. Current laser projects are being geared toward anti-aircraft efforts, but the number one goal is anti-missile systems.
Now let me give you a brief primer on how to fly over a basic anti-aircraft weapon.
[](https://i.stack.imgur.com/qpoXJ.png)
Turrets are turrets, and they move as fast as the designers can make them move, but the overall goal of getting through an AA battery is to get from one side of the arc to the other without being annihilated. The classic training for this is "low and slow," because that got you safely through the narrower part of the arc pretty quickly. But that's gotten to be impractical against more modern AA batteries. Now it's more like "really low and stupid fast," because what you have to do is stay so low that the system simply isn't aware that you are a thing that should be shot at. But there's another point to be made here - if you avoid target lock, you don't get blasted. Electronic countermeasures come into play and you start calling in special platforms that make radar do stupid things.
Now, if these next generation systems move fast enough, we have some problems; but remember that basically anything that hits the laser station will basically end its role in the fight. If the optical pumping chamber can be even slightly misaligned or cracked, it's over. Shelling should do nicely, as the laser itself can't particularly stop a ballistic projectile, even if it could track it (and it probably could).
[Answer]
I think this warrants a new generation of aircraft. Instead of the million dollar fighter jets, we move on to fast, agile, thousand dollar drones (okay, more like 1 million). Deploy them in swarms, a hundred aircraft in a hemisphere around the enemy turret. One will make it through, and then, it's bye-bye laser. And *then* we bring out the normal aircraft, if we want to.
Obviously, some design considerations can make it even easier for you.
**Shape:** Drones should be rather pointed cylinders, with thin, large wings, to increase surface area per unit weight not exposed to the laser. Drones can be intelligently oriented with a reflective, ablative side towards the laser, and a dark radiative side facing away. Computer systems and engine can be in the center.
**Engine:** Get something with a relatively high flow rate (air is pretty bad coolant, but it's all we have), and fast. Scramjets seem to fit the bill. Thrust vectoring is a must for extra maneuverability.
**Many Many missiles:** Some carrying reflective dust/strips that make you harder to target and hit, some are actual missiles to destroy the laser.
Say the UAVs speed towards our ship at low altitudes at around mach 3-4. They'll cover 100 kilometers in slightly more than a minute. If one drone can be destroyed in 5 seconds once targeted, our drones can destroy the enemies' lasers with 12 casualties if they start targeting us at 100 km. It will be fairly expensive, but, hey, a F35 costs a few hundred million.
[Answer]
Defense. The aircraft can be covered in retroreflectors, or better yet, active phase-reversing amplifying reflector panels. This will not only protect the plane but destroy the laser instead.
[Answer]
Another thought here—attack where the laser can't fly. We already have rocket-boosted torpedoes, consider what happens if we put together state of the art technologies:
Stage 1 is an aircraft-launched missile. It's going to be a big missile, though. It stays below the horizon to the ship it's attacking, the laser is useless.
Now, eventually staying below that horizon will drive it into the water. Before this happens it shuts down its engine and trades its airspeed for lift—the intent is to bleed off as much speed as possible without hauling along extra mass to do so. Eventually the lifting surfaces stall, at this point the airframe is discarded, the payload comes away on a parachute.
Stage 2 goes into the ocean something like 30 miles from the target ship. It goes to it's preset depth and light it's rocket booster—it's a supercavitating torpedo. It roars for about 9 minutes, the target fleet will do what it can during that time to evade but there are a bunch of these coming and they are fired in a spread.
As the torpedoes approach the target area their rockets shut down and are jettisoned. Some are programmed to go a bit long, some a bit short.
Stage 3 is an ordinary anti-ship torpedo. The fleet has had enough time to break any targeting they might have had but they can acquire on their own. They can hope to interpose their decoys but the torpedoes are scattered beneath the fleet, they can't steer away from every torpedo. The torpedoes that don't come out of supercavitation at the right spot to engage start hunting. They could also trail an antenna wire and listen to instructions on where to find the enemy—the fleet is going to find itself surrounded by hostile torpedoes and you can't run from enemies surrounding you.
] |
[Question]
[
**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.
The spud gun uses air pressure to shoot a projectile - unusually a potato - at high speed towards a distant target much similar to todays revolvers. The only difference is that there is no gunpowder. Can people in the medieval age as early as 5th century A.D. develop a potato gun that kills? The projectile can be anything but I'll applaud the gunmen who can shoot lethal potatoes.
[Answer]
The [oldest known air gun dates back to 1580](https://en.wikipedia.org/wiki/Air_gun#History). A 5th century weaponsmith faces great challenges in creating a similar weapon. The primary problems will be in creating a hand-held weapon able to withstand the pressures involved and with the necessary seals to avoid significant leakage. Did they have the *knowledge*, and even if they did, did they have the *materials*?
There's two types of [air guns](https://en.wikipedia.org/wiki/Air_gun#Air_gun_power_sources), spring and pneumatic. [Spring piston guns](https://en.wikipedia.org/wiki/Air_gun#Spring-piston) use a cocked spring to drive a piston to generate the pressure to fire the round. They have the advantage of not needing a sealed, pressurized reservoir. Their disadvantage is in the time and force necessary to recock the spring and the complexity of the piston and pressure chamber.
In the 5th century, making reliable, compact and powerful springs would be very difficult. Compact and reliable [coiled springs were not introduced until the 15th century](https://en.wikipedia.org/wiki/Spring_%28device%29#History). Even with the knowledge of coiled springs, steel making in the 5th century was in its infancy and would not be up to making [spring steel](https://en.wikipedia.org/wiki/Spring_steel) up to the task.
Sorry, [no springs](https://www.youtube.com/watch?v=le2eB2xtvBQ#t=1m20s) in the 5th century.
In addition, while storing compressed air was not necessary, the chamber would need to withstand the extremely high pressure *and heat* produced by the piston. I do not believe 5th century metallurgy was up to the task.
[The other type of air gun uses a pressurized reservoir of compressed air](https://en.wikipedia.org/wiki/Air_gun#Pneumatic). This introduces big problems of how to manufacture a compact, man-portable vessel to withstand the pressure and control leakage. This problem was solved in 1780 with the [Girardoni Air Rifle](https://www.youtube.com/watch?v=2dZLeEUE940) adopted by the Austrian Army. Watching that video will give you an idea of what is involved in making a successful air gun.
The primary problems are the reservoir, seals and valves. The strength and fine metal work of a threaded valve is likely beyond 5th century metallurgy, not to mention the small holes and pins, though it could be possible with very careful brass work. The seals available would be things such as leather, wax, and if they're very lucky, natural rubber. As we'll see in a moment, it's not likely they'll stand up to the pressures.
In the video, they estimate the pressure in the Girardoni reservoir to be 800psi or [about 55 atmospheres](https://en.wikipedia.org/wiki/Atmospheric_pressure#Standard_atmosphere). This is a lot. It's the pressure at 550m underwater, four times the test depth of a WWII submarine. A locomotive engine was considered "high pressure" if it used 350psi and those were not worked out until the 1800s. The Girardoni reservoir was designed to fire multiple rounds, a single shot weapon could get away with less pressure and a smaller reservoir, but I don't believe the reduction in pressure would be enough for 5th century technology. It would be nice if someone did the math. I sure wouldn't want to haul one around the battlefield knowing it might blow up.
So no, a 5th century weaponsmith could not create a reservoir able to hold a high enough pressure to drive a heavy enough ball at lethal speed.
No springs, no valves, no seals, no reservoir. It's not going to work.
Maybe [@Vincent](https://worldbuilding.stackexchange.com/questions/23168/can-medieval-people-make-potato-gun/23169#comment60574_23168) has the right idea...
<https://www.youtube.com/watch?v=2qCxTuctHuY>
[Answer]
Late answer, but another possibility... The kind of spud guns I've seen around here didn't use compressed air, but instead used a flammable liquid/gas like alcolhol or aerosol hairspray to [propel the potato](http://m.youtube.com/watch?v=ZFs4e9Z27y8).
Granted, hairspray is not going to be an option, but high proof alcohol vapors are explosive too.
Basically any kind of fuel air explosion could propel the potato without needing a pressure vessel or springs.
Edit:
Just because this is a fun video, an [explosion in a potato gun at 20,000 fps](https://youtu.be/_TNSUIsjdpY)
[Answer]
You could probably conjure something up with the right medieval tools and resources. Although [smelting and molding iron](https://en.wikipedia.org/wiki/Smelting#History) was still a new concept, parts could technically be made, and with the right [organic binding agent](https://en.wikipedia.org/wiki/Binder_(material)), you could make a reliable pump based air cannon. But, if your going to be shooting potatoes, you better make sure your not Irish or Latvian.) ;)
] |
[Question]
[
This question is directly related to my last: [What would be the impact of a modern programmer and laptop being dropped into World War II, possibly breaking Enigma?](https://worldbuilding.stackexchange.com/questions/12129/what-would-be-the-impact-of-modern-program-and-laptop-being-dropped-into-world-w/12171#12171) Where a young programer, and laptop. is somehow accidentally sent back to early WW2 time.
The problem is that the protagonist is a quasi-pacifist (not oppose to all war, willing to agree that WW2 probably has to happen now that Hitler is in power, but still is very uneasy supporting the war). He would rather focus on progressing science, quality of life, and pushing the government towards more progressive/modern policies, particularly in terms of civil rights and treatment of others.
He will get attention for himself by mentioning he could break Enigma with little effort, drawing the attention of the military. However, he tries hard to push towards using the laptop for non-military proposes, or trading it's military use for some other positive policy being enacted. For instance I'm almost certain he would try to exchange the ability to do code breaking for minimizing or stopping the Japanese Internment camps that he sees as a shameful black mark on US history. The question is *could* he make 'trades' like this?
This involves a few questions. First, how does he keep the government from just taking his computer and tossing him out when he becomes a nuisance? He will claim to have placed hooks in the OS, so that if he doesn't get occasional unsupervised access to 'defuse' them the computer it will lock itself or wipe the harddrive. The truth is he doesn't know how to do this, it's a bluff to try to discourage the laptop being taken away from him.
He's also the only programmer they have. The loss of his programing and computer expertise would greatly limit the usefulness of the laptop, though they could eventually figure out how to write code on it themselves. The government could try to bully him into writing code, but he has pointed out it's quit easy for him to lie about what can or can't be done, work at a slow down, provide false results, or just run an application that fries the computer by overclocking it, having someone doing such important work uncooperative is dangerous.
How much bargaining power could he reasonably have in a situation like this? Could anyone make as massive a promise as to cut back or stop the Japaneses internment camps, or is the government simply too big for any party to be able to follow through with something like that? What bargaining chips could someone high up in the government who is desperate for his support of the war effort offer that they could actually gaurentee? How far could someone like our time traveler push before the government of WW2 era would likely stop bargaining and start strong arming?
Keep in mind he would likely mildly alienate those involved in the war effort with his different world views. He is offended and tries hard to argue against the racist cartoons/propaganda against jap and German people, which, combined with his more pacifist view to the war effort, would make some see him as an enemy sympathizer, or perhaps just foolishly naive. Culture clash over other topics, like civil rights, smoking, and sex/sexuality, could also occur.
He also has to deal with the fact that anyone who hasn't seen his laptop in action will never believe he is a time traveler, and even those that have often suspect he got it from some group with advanced technology as being more believable then time travel. He may try "the future will look back and be ashamed of this action", but not everyone will believe that's true.
In this scenario the programer has very limited interest or knowledge of History in general, and particularly knows very little of the war due to his pacifist nature causing him to avoid listening to or learning about war history. What history he does know is more of a cause->effect concept, but he can never remember dates or time frames. As such he has limited historical knowledge which could be of any use directly in the war effort. He knows D-day, pearl harbor, and *maybe* midway happened, but not when, and not too much about how. He knows more about non-war history, particularly history of science and computers, but still nothing too specialized. I may have him be more aware/interested in internet and history of it's development, as something he may to try to push them towards developing sooner.
He fell through time while walking to college, and as such has with him his backpack and school supplies. This includes his laptop, one Graphing Calculator, and a cheap smart phone who's battery ran out very shortly after arriving. The Graphing calculator is in some ways more useful then the laptop, because it's much easier to teach scientists how to use it without having to go through him, but at the same time that also makes it much harder to keep the government from just taking it and using it without his permission.
His backpack could also have 1-2 textbooks, of whatever subject I decide it's reasonable and interesting for him to have. The books will not include "history of WW2" or anything too 'game breaking', but I'm keeping open the possibility of having a book which is somewhat relevant if it makes the story interesting. Computer Networking, some civil rights-related course, and basket weaving 101 are all possible textbook topics :)
[Answer]
He's actually got **a lot** of power in this situation, owing almost entirely to the fact that he is literally the only man on the *planet* capable of operating his laptop. At least in the time frame the military would want it used in (i.e. immediately). On the other hand, he's completely at the government's mercy in terms of whether or not what he thinks he's getting in return is actually even happening.
Code-breaking is only one of many ways such a powerful tool could be used: he could, for instance, quickly and easily collect and index in the one device all information about known enemy troop deployments and movements, and with just a few keystrokes provide detailed analyses to intelligence officials that would normally have taken them days -- if not weeks -- of poring through paper files to come up with. That's a *huge* asymmetrical advantage to the US, being able to analyze enemy troop dispositions far more quickly than their enemies can analyze theirs, and handing that information to the right strategic minds lets the US quickly take advantage of weaknesses while avoiding strong points and ambushes.
>
> He will claim to have placed hooks in the OS, so that if he doesn't get occasional unsupervised access to 'defuse' them the computer it will lock itself or wipe the harddrive. The truth is he doesn't know how to do this, it's a bluff to try to discourage the laptop being taken away from him.
>
>
>
Of course he does! Anyone who can reasonably be called a programmer knows how to set up "deadman switches" and other traps in a computer that could wipe it at the first sign of unauthorized access. He'd be very unlikely to know how to do it in a way that could thwart modern day experts (or even his own colleagues), but he wouldn't need to -- simply dragging a file to the Recycle Bin and then emptying it is plenty to make it irrecoverable to even the top minds of the day, even though modern-day experts can easily recover such a file without even batting an eye.
Remember, the folks of this era don't know the "tricks" you and I take for granted, like Alt-Tab'ing out of programs or Ctrl-Alt-Del to get to Task Manager and killing programs. He wouldn't even have to worry about full-disk encryption, since there's zero chance the best minds of this era could even defeat the venerable Windows Login Screen, a mild annoyance at best to anyone today trying to access a computer.
>
> The loss of his programing and computer expertise would greatly limit the usefulness of the laptop, though they could eventually figure out how to write code on it themselves.
>
>
>
If by "eventually" you mean decades later to come up with even the most trivial of programs -- well after the war was over anyway -- then yes, you're right. In all likelihood the original dawn of the Computer Age would occur before they make serious inroads on figuring out this laptop on their own, though of course once they do it will greatly accelerate technological progress.
Now, if his backpack includes "Programming 101", that could accelerate efforts to cut him out of the picture and put the laptop itself into direct service of the war effort -- but even the most hard-headed pro-war military officer would know full well that they'd get much further much faster with the programmer's help than without it.
>
> Could anyone make as massive a promise as to cut back or stop the Japaneses internment camps, or is the government simply too big for any party to be able to follow through with something like that?
>
>
>
The President would almost certainly get involved at some point. He would be, after all, the US's most important military asset. And with the President's backing, things like an end to the internment camps could indeed be promised with the power to be followed through on.
Whether or not they actually would, however...
>
> What bargaining chips could someone high up in the government who is desperate for his support of the war effort offer that they could actually gaurentee?
>
>
>
They'd offer him all sorts of creature comforts: A big house, a government spending account so large he'd have a hard time spending it all, a veritable army of aides to see to his every need, etc. And of course a security detail to rival that of the President's own, because this one guy is arguably the most important military asset at the US's disposal.
If he's as principled as you suggest, however, he may actually turn these carrots down (or at least some of them), and instead demand concessions like an end to the internment camps and a promise to never use the nukes. Whether or not these are genuinely offered is another matter...
>
> How far could someone like our time traveler push before the government of WW2 era would likely stop bargaining and start strong arming?
>
>
>
Honestly I doubt they'd do much overt strong-arming at all. Like you said, it's far too easy for him to simply refuse to help them, or to provide false information or deliberately work more slowly. And in many cases they'd have no way of knowing. "I'm sorry, sir, but searching a million database records for one keyword is a time-consuming process. I'm sure it will be done within the next 20 or 30 hours, though."1
What they would do, however, when his demands become too much for them to stomach, is to mount a campaign of deception and propaganda against him. By controlling what he can see on the television and creating custom-written newspapers just for him, they could trivially convince him that they've honored his requests. They could write stories about how a broken code lead to the bloodless surrendering of an entire company of Nazi soldiers (when the truth is that the broken code allowed the Allies to surprise them and slaughter them to the last man); he could read about the end of the Japanese-American internment camps and the official apologies and reparations paid to its victims (when in reality nothing changed with the program); he might see television broadcasts announcing the capitulation of Japan after Hitler's surrender, when the truth is that he's watching actors reading from a script while Japan is being nuked following Hitler's suicide.
He's just one man. He has no connections in the present era. The military could easily control access to him under the guise that they're protecting him (actually not really a guise, they would be) and thus easily control what information reaches him. It's not like he can just hop on the internet and find out the truth -- if the television, newspapers, and people around him are all telling him that his efforts are contributing to less bloodshed *and* Allied victory, he'd *happily* redouble his efforts on behalf of the US military!
Cue the dramatic turning point of the story when someone breaks the rules and tells him he's been Truman Show'd, that everything he thought was true has been a lie all along, and that the reality is that with his help Axis casualties have tripled while none of the improvements at home he demanded ever actually happened...
---
The graphing calculator would be pretty trivial for the mathematicians of the day to figure out how to use, but on the other hand it wouldn't give them a whole lot of advantage. Not a single a calculator, and certainly not on balance against the huge advantage embodied by the programmer and his laptop. Batteries for it wouldn't be an issue -- once they die, all you need is to hard-wire in a simple 4.5V or 6V power supply (depending on whether it's 3 or 4 batteries -- I've seen both configurations, depending on model), pretty simple even in WWII, just not as portable as AA batteries.
Similarly, the smart phone would be of little use. Nifty "wow" factor, and once he hacks together (or has someone of the era build) a basic power source for it (really, not hard even in WWII to produce 5V @1A, plenty to power and even recharge the device) he'll be able to fill his downtime with Angry Birds again, but the real power of smart phones comes from their connectivity -- and without that, it's of little more use than the graphing calculator, and certainly a lot less use than the laptop.
---
1 For those unaware, a million records is a small database, and a simple search for a single keyword would take a fraction of a second on even low-end hardware today.
[Answer]
How do they do it?
I don't believe programming skill is enough to bargin for change. During early WW2 era, the allies could have called in people like Alan Turing, John von Neumann, Grace Hopper or even Albert Einstein to examine your claims and technology.
My experience (as a programmer who has briefly taught one young genius), is that a few minutes showing how to get a compile, run, observe, development cycle working, is that a very good mathematician of the era could out perform the young programmer very quickly, making the knowledge of programming and of the modern technology of little value to people like Turing.
Which leaves me with social engineering.
The time traveler could freely volunteer everything they know, help and handover the devices. All this would build credence. There would be no counter evidence if they then used this standing to talk to people about their legacy and how the future will view them. Imagine if you could talk to Turing about how gay rights had changed within your time? Or Einstein about the history of the holocaust?.
Things like those internment camps? They stemmed from what some (not all), thought was the best thing to do at the time. With your basic knowledge - you can simply state they achieved little and that post imperial Japan quickly becomes an ally. I suspect with that knowledge they would not bother to spend the time and money on pointless activities like the camps; when they would be very busy focusing on nuclear power, ballistic missiles, guidence systems, building computers and so much more...
[Answer]
I'd be very worried if my *pacifist* programmer friend was sent in the conditions you describe **during** the war. He would have to be **extremely fast** at proving he (and only he) can provide significant help to the country. Well, either extremely fast OR in a way that puts him in a situation of power. Read "blackmail the authorities of the country". Not to extort any money of course, but just to garantee his own safety and freedom.
>
> How far could someone like our time traveler push before the
> government of WW2 era would likely stop bargaining and start strong
> arming?
>
>
>
My view on this one is the exact opposite of Kromey. That would be almost instantaneous. Your programmer just arrived here, has contacted them on his initiative (they didn't send someone to pick him up). They will assume he's a patriot coming to help his country. They will not take it lightly when he starts to make requests in exchange of his help. Except for maybe two types of request which the generals might understand and agree to "consider":
* Money: Even if you're not greedy yourself, you know the world is full of them so nobody would be surprised by such a request. The rest of the negotiations would just turn around the final amount.
* Emotional: "Please help my wife and children still stuck in Poland" or similar. They would understand it is important for you so they'd probably promise to "do something about it" to get your cooperation.
Any other request type, if they cannot understand why it is important for you, will make them suspicious and on the defensive. (pacifist request might be very important for your programmer, but a general in the middle of a conflict is not ready to appreciate that).
If the war is started, the authorities of the country you land in do not have the same thought process as in peace time. A lot of the main and first concerns are military. How can I finish this war as quickly as I can. What can I do to get an edge on the enemy and what can I do to protect against the opposite. The civilian concerns comes next. Of course they also want to protect their population, organise the food banks etc, but they accept in their mind that not ALL of the population can be saved, there will be casualties ... for the cause. Even in our so called "developped countries", in times of war the value of an individual life is nowwhere near where it is in time of peace, and is nearly nothing if put in balance against several or many other lifes.
Now imagine your programmer arriving there, and starting to try to **trade** promises of great benefits/helps against ... *whatever* actually. The risk here is to try to *trade* with someone in position of power over you. Remember you are at war. Many generals, or military oriented politicians, might simply tell him: "*You are a patriot, then do this for us, or else you are a traitor*". Sure the programmer can decide to go on a hunger strike in the bottom of his cell and not do any computing work for them ... but that's assuming that they'd put him in a comfortable full board jail. Torture has been used all over the world since it's beginning, and do not ever think your government (whichever country you're from) has never used some form of it. All these people in power, not affraid to loose an individual life for their cause, with the chance of getting a formidable boost ... I'd be very worried that they'd just lean on him until he breaks or he agrees to help.
*Reader: Ok, but what about:*
>
> The loss of his programing and computer expertise would greatly limit
> the usefulness of the laptop
>
>
>
True! But they do not know yet what they are loosing. A simple one time demonstration would not be enough to convince everyone that the benefit of him+laptop are tremendous, or that it's repeatable, or that it's not an elaborate trick. They would need repeat results over time to appreciate the value of it. Time your programmer might not have if he come into negotiation too strong too early.
---
Now as said in the beginning, that's likely if he tries to trade before showing his superiority. So if he somehow manage to get his hand on an encrypted message and decode it, or any other feature that can be recognised by the authorities as something extraordinary (not something common in their time), then he has better bargaining chip to begin with. He will still need to also convince them that only him can operate/achieve whatever feat he did to convince them.
But even then, it is not garanteed. Remember nobody believes in time travel until they actually time travel or see someone doing it. The authorities in 1939 didn't think that time travel existed, so it might not be easy to convince them you are actually coming from the future. They still might think you're just a crazy lunatic/scientist and all the gears in your backpack are "advanced" but comtemporary to them. If they think it's contemporary, then they probably also think that they can operate/reverse engineer anything you've got with the help of all the great minds they just happen to have available. Whether they could *actually* do it or not is not relevant, the point is if they do not see your particular value, then you're just a speck of dust in the middle of a battlefield and you are completely disposable, not a good position to trade (specially with pacifist requests to a militarized government right in the middle of a conflict).
---
So for me his best bet would be to fully collaborate from the start, not making any request yet, and abiding happily to what he is asked for. At least for a while. Basically he'd have to turn a blind eye to his convictions for a few months. Once he's been judged collaborative and useful, he will get a status similar to the great scientist recruted at the time. This will allow him to voice his convictions again, but not necessarily to get his request granted yet. Many of the scientists had freedom of movement, but for some it was very conditional to their participation (and still somewhat limited).
Basically, do not try to bargain hard with a government already at war. They'll have very limited patience to foolhardy requests (pacifist requests when we just entered a war!!), and in times of war individual rights are lessened so ... play at your own risks.
] |
[Question]
[
Suppose one constructed a [Bernal sphere](http://en.wikipedia.org/wiki/Bernal_sphere), similar in design to that described in [this article](http://www.nss.org/settlement/space/bernalsphere.htm) and [this article](http://www.nss.org/settlement/space/bernalspheredetail.htm) at the National Space Society.
* If the sphere was simply rotated on a single axis, would gravity be constant everywhere on the internal surface? Or would there be areas with stronger gravity and areas with weaker gravity?
* Is there any way to rotate the sphere such that gravity is constant everywhere in the sphere, at least to the point that humans cannot recognize a significant difference in the gravity?
[Answer]
if it is a sphere then no, at the "poles" the apparent gravity would be lower than at the "equator" this is linear so if you half the distance to the axis then the apparent gravity is halved. Near the poles gravity also would be a bit sideways but that is easy to solve by a terrace-like layout.
You can solve this by making the sphere a cylinder (or stretching the sphere to a more oblong shape) where gravity would be consistent on the surface. Or by rotating different latitudes at different speeds.
[Answer]
There are a variety of different ways in which artificial gravity (the experienced acceleration) would not be constant inside a rotating sphere. There is no way to reduce these discrepancies sufficiently to make them indistinguishable to humans (apart from the unhelpful trivial case of slowing the rotation and making the gravity everywhere so low that humans cannot perceive it).
# Variation in strength from equator to pole
Standing on the inside of the sphere, you are moving in a circle around the axis of rotation. This circle is largest at the equator, and gets gradually smaller until it is zero radius at the poles. Since the time taken for one revolution is the same everywhere, there is maximum gravity at the equator, and zero gravity at the poles.
# Variation in slope from equator to pole
The direction of gravity is directly away from the axis of rotation. This means that the surface appears to be horizontal at the equator, but as you walk towards the pole it becomes steeper, much like walking up the inside of a bowl.
# Variation in strength when walking or running
Stood on the inside surface of the sphere you feel stationary, but you are actually moving in a circle. If you walk or run in the opposite direction to this motion then you will weigh less. If you move in the same direction as this motion then you will weigh more. If the radius is not sufficiently large, running could make you weightless so that you lose contact with the floor and drift through the air. Increasing the radius increases the speed you would need to attain in order to become weightless, so that running is no longer a problem, but even a large sphere will still have this problem as you approach the poles and the radius decreases.
This will be more of a problem if there is powered transport at greater than running speed. If the outer radius (equatorial radius) is sufficient to prevent problems at running speed, there could still be problems near the poles or on high floors of buildings.
# Variation with height
The nearer you get to the axis of rotation (which appears to be above you), the less you weigh. This means that when standing upright your head experiences lower gravity than your feet. To avoid this effect being large enough to cause discomfort, the radius must be large enough that gravity changes slowly with height. This is a problem in a sphere, since the radius of rotation decreases as you approach the poles.
This also means someone in a building a few floors up from you will feel lighter than you, heading towards weightless at the axis of rotation.
# The floor tilts when you stand up
The [Coriolis effect](http://en.wikipedia.org/wiki/Coriolis_effect) causes what feels like a horizontal acceleration when moving towards or away from the axis of rotation (that is, during the process of sitting down or standing up, or when going up or down stairs or in an elevator). This combines with the apparent downward acceleration to produce an apparent acceleration that is no longer directly downwards. The sensation is that the floor is no longer horizontal, as if it has suddenly tilted.
For this reason elevators may be allowed to swing so that the floor can align with the temporarily tilted horizontal plane during ascent and descent, returning to normal when they stop.
Again, this effect is reduced by increasing the radius.
# Comparison with a cylinder
In a cylinder, you can simply make the radius large enough to make these effects too small to cause problems. In a sphere, a large proportion of the surface area is at a smaller radius of rotation, approaching zero radius as you near the poles, so it is harder to avoid these problems unless you only use the surface nearer the equator.
Even if the outer appearance of the structure is spherical, it would be more practical for any floors inside to be cylindrical, so that the floor appears horizontal wherever you stand.
Even then, people on sufficiently high floors (nearer the axis of rotation) will suffer discomfort and disorientation, accompanied in many cases by nausea. These areas might be restricted to scientific use or storage (or perhaps be very low rent if your sphere has an economy).
# Fine detail
This answer is already long so I haven't included specific numbers. If you wanted to know something in particular, like the radius or rotation speed at which running would cause weightlessness, or the change in weight per floor if the outer floor is normal Earth gravity and the radius is a mile, then they could be asked as separate questions.
[Answer]
Rotationally simulated gravity always points directly away from the axis of rotation, and there's no way to change that. So unfortunately the answer is no to the second question.
For the first question, essentially the further you move from the axis then the stronger the simulated gravity becomes. You have free fall right at the axis, then as you move further away the force becomes stronger and stronger.
] |
[Question]
[
I'm thinking on the colonizing of another planet by humans. The conditions of this planet are quite different from Earth, and particularly the day-night cycle is much larger.
In my fictional planet, the day will last 48 hours. The day-time and the night-time is duplicated, and that means than the proportion between the hours of sunlight and the hours of night is the same than in the Earth.
Would the humans living on this planet adapt their sleeping to the new day-nigth cycle, i.e., will they sleep during all night-time and be awaken during day-time? (This is after some years or even, if needed, a couple of generations.)
[Answer]
Actually, an 48 hour cycle is great, because it's exactly twice the normal 24 hour cycle. Thus adaption would be easy; people would just sleep twice for each planetary day. There might, however, be the need to have bright enough illumination during the "night-day" time, in order to stay healthy for a prolonged time (I guess they are on that planet for the whole rest of their life, not just for a year or so).
However, also something else might happen: In experiments to the circadian rhythm where people were living in bunkers without any indication of current time, it turned out that some people actually switched to a ca. 48-hour rhythm, and when the time was over, they didn't believe that much timme had passed because for their own feeling, only half the number of days had passed.
So maybe with an external 48h stimulation, most people would automatically switch to that cycle.
Also note that this cycle is special exactly because it's twice the normal time. On a planet with e.g. 30 hours per day, people would likely experience a permanent jetlag.
[Here](http://news.psu.edu/story/141822/2004/06/09/research/it%E2%80%99s-about-time) is an article mentioning the time experiments and the 48h rhythm.
[Answer]
Yes people would adapt and live.
People need approximately 8-9 hours a day of sleep. So people would get that much sleep during a 24 hour period. If people go 24 hours without rest on Earth, they have problems. People on the other planet would too. According to [this](http://spaceflight.nasa.gov/living/spacesleep/index.html) article, people in Space (which has weird day night cycles) sleep pretty much like they do on earth.
>
> Generally, astronauts are scheduled for eight hours of sleep at the
> end of each mission day. Like on Earth, though, they may wake up in
> the middle of their sleep period to use the toilet, or stay up late
> and look out the window. During their sleep period, astronauts have
> reported having dreams and nightmares. Some have even reported snoring
> in space!
>
>
>
[Answer]
I suspect that the early settlers would adapt by taking a relatively short nap(maybe 4 hours or so to start) during the day cycle and a longer sleep period during the night cycle. As the generations grow up used to the cycle I would expect that the population would adjust to extended cycle times without the need for the naps.
Some things that are going to affect this:
If it is signfigantly more friendly of an environment in the day than it is at night, there is more pressure to get things done during the favorable cycle, this is going to push for the longer cycle times. For instance in a desert world the temperature is likely to cycle greatly making the nights extremely cold and the days extremely warm. In this the cycles are going to be optimized for the dawn and dusk cycles where the temperature is the most friendly.
On a planet where the local Fauna come out and pose a threat during one cycle or the other are going to push for the opposite cycle to be the primary operations cycle. Many people probably think that predators are most active at night on earth but the truth is most predators are [Crepuscular](http://en.wikipedia.org/wiki/Crepuscular) meaning they operate most at dusk and dawn. So in a world with large predators to contend with the population is probable going to adjust to a dusk and dawn sleep cycle with waking periods during the day and middle of the night.
A civilization forced to rely almost exclusively on solar power is certianly going to want to get the most out of their daylight hours pressuring people to be active for the daylight period and resting(and thus using less power) during the night cycle.
So there is more to think about than just what is the cycle of the planet. You need to consider those factors that are going to have a huge impact on when humans operate. Humans are adaptable and will adjust to their environment in the way that they need to.
[Answer]
There are 2 main issues that come to mind:
1. Sleep is strongly affected by light. The presence of light inhibits the production of melatonin, darkness encourages it. Sleeping during the day light hours would require a lot of shade. Staying awake during the dark hours would require good lighting and an extra pot of coffee.
2. Human beings do not NEED to have all of their sleep in one stretch. Thomas Edison famously power napped instead of sleeping all at once. Ultimately REM sleep is cumulative, and if you get enough of it, it doesn't matter how you do it.
That said, here is how I think humans would adapt:
Daytime would be mostly work time, with catnaps interspersed through at the light hours. I would tend to believe that there would be easily accessible bunks in work places for people to go at naptime.
Nighttime would most likely be the opposite. If we assume there would be 16 hours of darkness, I would guess that at least half of it would be spent sleeping, probably in 2 chunks. Maybe 4 hours of sleep, 8 hours of fun-time followed by another 4 hours of sleep before getting back to the daily grind.
[Answer]
It would be most likely very easy to change daily activities and sleep schedules, the amount of time it would take for someone to change may depend
some people are very heavy sleepers but other are very light and wake up in the middle of the night periodically to use the restroom or other utilities thus it may be easy for other not so easy for others
] |
[Question]
[
**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.
Hemerythrin is an oligomeric iron-containing protein of the metalloprotein class found in the blood of some invertebrates. Able to reversibly bind with oxygen, ensuring its transfer to tissues. Hemerythrin is used to transport oxygen in the blood of brachiopods, sipunculids, priapulids, and some annelids (polychaetes).
Here we are interested in how hemerythrin carries oxygen, so unlike the hemoglobin we use, in which oxygen is transferred directly, here oxygen is not transferred by itself, but in the form of a special compound HO2 or -OHH, which ultimately gives an interesting feature: our hemoglobin is good associates not only with oxygen, but also with carbon monoxide that is released during combustion (often during a fire, people die precisely because of carbon monoxide poisoning, and only after that because of burns), but hemerythrin, due to its peculiarity in terms of capture oxygen, it does not bind to carbon monoxide, so if I understand correctly if we had gemerythrin instead of hemoglobin, we would not be exposed to the action of carbon monoxide.
And here we come to the heart of my question: what problems can arise when using hemerythrin as an oxygen carrier instead of hemoglobin?
The main problems in this question include: the efficiency of oxygen transfer and how many things will need to be rearranged in the human body.
[Answer]
**It might work well!**
I initially thought - no way. This molecule is for cold blooded creatures living in low oxygen environments. It is going to be burnt by our high O2 environment and will not deliver O2 adequate for our hot muscles.
To my surprise I found a bunch of stuff about using hemerythrin as a blood substitute!
[Towards the Development of Hemerythrin-Based Blood Substitutes](https://link.springer.com/article/10.1007/s10930-010-9264-2)
>
> Our results indicate that chemically modified Hrs constitute a
> promising alternative candidate for blood substitutes. Hr undergoes
> minimal oxidative and nitrosative stress-related reactions compared to
> Hb. Moreover, PEGylation and dialdehyde crosslinking were shown to be
> feasible procedures for controlling Hr’s molecular weight, oxygen
> affinity and resistance to autoxidation. The extent to which such
> modifications may overcome extravasation and antigenicity barriers
> remain to be determined.
>
>
>
In short, it is apparently no great thing to chemically modify hemerythrin and alter its oxygen binding / releasing affinity to match what we would need. A great benefit as the OP mentions is intrinsic resistance of hemerythrin to poisoning - not only by CO but also nitrite and other oxidative stressors.
I figured that hemerythrin would be phenomenally antigenic - keyhole limpet hemocyanin is used as a vaccine adjuvant because of its immunogencitiy. From what I can tell that is not a huge issue with hemerythrin. I think that the molecule might be chemically modified and polymerized before putting it in artificial blood.
In sum: if used for artificial blood this could work, as evidenced by a number of labs working in earnest on such products. I am more skeptical about genetic engineering humans to express hemerythrin - that would sidestep antigenicity because of tolerance and one could engineer in a genetically hacked version with appropriate O2 avidity... ok, getting less skeptical.
] |
[Question]
[
A typical cliche that is often used in Anime is that anthropomorphic cats exist. These are basically humans with cat-ears and a cat-tail (see [Plausibility of the Japanese Nekomimi](https://worldbuilding.stackexchange.com/questions/58878/plausibility-of-the-japanese-nekomimi) for a fitting picture).
**I want to know how it would affect a human if he was suddenly able to hear like a cat.**
I want to focus on the frequency range cats can hear. In this regard [Wikipedia](https://en.wikipedia.org/wiki/Cat) states that "Cats have excellent hearing and can detect an extremely broad range of frequencies. They can hear higher-pitched sounds than either dogs or humans, detecting frequencies from 55 Hz to 79,000 Hz, a range of 10.5 octaves, while humans and dogs both have ranges of about 9 octaves. Cats can hear ultrasound, which is important in hunting because many species of rodents make ultrasonic calls." Other points regarding the ears of cats, like steerable ears, can be ignored.
For this question we will assume a crazy bio-engineer in the distant future manages to operate a normal adult human, removing his human ears and instead giving him cat-ears similar to those of a [Maine Coon](https://en.wikipedia.org/wiki/Maine_Coon), just bigger. This human acquires the same hearing capabilities as this type of cat. Other changes that would be necessary to make this plausible can be ignored. After the operation the human goes back to his normal life and is monitored by the crazy bio-engineer to see the results of this little test.
To make it possible to make assumptions about the environment we will stick to the present. This means that the human race will only focus on bio-engineering and not change in any other aspect. Therefore it will be normal for other people if this human disappears for some time and comes back with cat-ears, but technology, culture, etc. will (except for the acceptance of such bio-engineered humans) remain the same as today. The setting is Europe and we will imagine this human to be a middle-class white-collar worker.
This question is different from others like [Plausibility of the Japanese Nekomimi](https://worldbuilding.stackexchange.com/questions/58878/plausibility-of-the-japanese-nekomimi) because I don’t want to create a new race which is born with such capabilities and therefore accustomed to them.
**I want to know what would change for a normal human if he suddenly got such capabilities and how this would affect his everyday-life.**
[Answer]
The human will be able to hear a variety of additional, but largely unimportant sounds, at the expense of poorer ability to interpret important sounds, particularly speech. He will be much more aware of his or her environment, at the expense of difficulty with social interaction due to having a hard time communicating.
The problem has to do with the issue "frequency discrimination". That is, how well can you tell apart two similar frequencies. Cats, having their hearing range spread over many more frequencies, are [much poorer](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3627498/) at telling apart two nearby frequencies. This is particularly important in speech, where such cues are critical for understanding what word is being spoken.
This also is an issue for detecting where a sound is coming from. Due to our large head size, humans are much better-suited for picking out [interaural time differences](https://en.wikipedia.org/wiki/Interaural_time_difference), which are differences in the arrival time of sound between the two ears. The catch is that ITDs are only useful at low frequencies. The human brain's sound processing is laid out in terms of frequency, so with no other brain changes the sound location system will be completely messed up and a large portion of it will be totally useless. Even if the brain was also changed, you still have the issue that your subject has less of his auditory system dedicated to the necessary low frequencies. This is a major problem, since being able to tell where sound is coming from is essential to understanding speech in noisy environments.
Overall, your subject would have a really, really hard time understanding speech, especially at parties, or on the subway, or while walking near a busy street, to such an extent that he or she will likely avoid many social encounters.
[Answer]
This is an "in addition to" answer, as BlackCat's answer has good points, but I started writing a comment and moved to an answer due to length.
So, the first extra issue is also sensory overload and nuisance. Basically, human society is built for human hearing ranges. There are some things that will have undoubtedly ultrasonic noises that might be strong enough to cause nuisance in animals that can hear them. Some areas might be positively painful for any creature with that kind of hearing range to go into and there might be certain sounds that an individual with that hearing just could not cope with, leaving them rolling around on the floor in agony while people look on in puzzlement.
Equally, it might cause a lot of nuisance if you could hear every mouse squeak and suddenly realise your building is infested with mice you can hear behind the walls or your garden is a major hive of nighttime wildlife activity crossing through and around. It might affect your sleeping, or you'd just look odd, suddenly swiveling to follow sounds that no one else can in a conversation.
With a different hearing range, there's also the issue of responding to sounds. For example, it's been said that cats respond better to women than men because men have lower pitched voices and therefore are harder to hear. If that's true, then that would have a significant impact on the social functioning of your person with cat ears.
However, there might also benefits in some ways. For example, there are mice on the London Underground which are supposedly a different type of mouse because their ultrasonic squeaks are tuned such that they can speak (or should it be squeak?) quite clearly to each other even over the noise of tube trains, which are quite loud and deafening at the best of times.
There might also be an adjustment period while the person gets used to things, especially if their hearing is more directional due to the ear-turning thing, and everything might be overload at that point.
While that's not all, the human would also have to deal with suddenly having more body-language with animals, particularly cats, who use ear position as a way of communicating feelings. They'd have to be careful about how their ears are poised if they're trying to deal with a cat especially.
[Answer]
In addition to what TheBlackCat and aphenine said. TheBlackCat said this, which is important:
>
> The problem has to do with the issue "frequency discrimination". That is, how well can you tell apart two similar frequencies. Cats, having their hearing range spread over many more frequencies, are much poorer at telling apart two nearby frequencies.
>
>
>
Compared to a human, you will be practically tone deaf. You won't be able to tell apart so many notes in so many songs that they will not make sense to you anymore.
Imagine never being able to enjoy music again.
Another thing: some audio devices such as CD players, as well as audio file formats such as MP3 filter out sounds higher than regular human hearing frequencies in order to save up storage space. So if you hear something firsthand and then hear a recording of it, depending on the media, you will notice quite a difference. You might see a dognon TV and think "hey, that's not what a dog sounds like at all!" A human analogy would be watching Guns'n'Roses live and hearing everything, but then when hearing a recording it would be as if Slash and Axl were never there.
] |
[Question]
[
When building a world, I use one of two approaches: Either figure out the geography or write down the societal history. I can then use the one to influence the other and then move on to the rest of the world.
When building a world for the sake of worldbuilding, I like to create the geography of it first and then let the society play out its own history. But when building a world for a story, I have to work on the history leading up to the story, to determine how the society evolved to its current state. Then I figure out the geography I need to let that history play out (for example, maybe I need to have characters live in a city on the slope of a mountain, and so I create a mountain range).
While working on one of my current worlds, I determined that a specific city needed to be in or near the foothills of what I've called the Great Western Mountains. That's fine enough; most of the rest of the immediate area in the east is flat and gently starts to become more mountainous, with a couple hills here and there. The issue, though, is that in order for the city's history to develop to where it is in my story, I want to have a great battle take place in a long, grassy plain outside the city - kind of like the [Battle of the Pelennor Fields](https://en.wikipedia.org/wiki/Battle_of_the_Pelennor_Fields), for all you Tolkien fans. The problem? I can't come up with a good reason for there to be a giant plain in the middle of the foothills of the Great Western Mountains. I'm not willing to change the battle setting, because when last I checked, cavalry charges are not good on forested mountain slopes.
This isn't the only time I've had the geography of my world clash with its history. At least one island city has never come to fruition because I determined that the mountain islands it resides on would, in a realistic world, extend north on the mainland in a large mountain range that blocks off a trade route or two. These aren't fantastic examples, but the point is, I've had many cases where I can't have a certain setup and preserve historical and scientific realism.
The obvious solution here is to develop the geography and history side by side, integrating each into the other. My reason for not doing so is that I tend to end up with either a world that is scientifically unnatural (e.g. a peninsula that spontaneously juts out from an otherwise flat coastline) or a world with an implausible history (e.g. General Thel has to make a detour along a mountainous ridge that I've had to make instead of engaging the enemy's much smaller force on the valley floor I originally wanted but had to get rid of).
Maybe this is just the result of a lack of imagination on my part, and an inability to see solutions to these issues (as well as the terrible examples I've given), but this sometimes becomes a problem I can't solve. So when I'm trying to build a world, and I need event X to happen at location Y, but the two are incompatible, what can I do? How do I build a world that doesn't behave like I want it to?
Please note that I'm not asking how to solve the specific examples I gave, but the case in general.
[Answer]
>
> The obvious solution here is to develop the geography and history side
> by side, integrating each into the other.
>
>
>
For starters, this made me laugh, and I will get into why in a minute.
>
> My reason for not doing so is that I tend to end up with either a
> world that is scientifically unnatural (e.g. a peninsula that
> spontaneously juts out from an otherwise flat coastline) or a world
> with an implausible history...
>
>
>
Been there, I understand your pain.
>
> Maybe this is just the result of a lack of imagination on my part, and an inability to see solutions to these issues
>
>
>
Maybe a little bit.
>
> So when I'm trying to build a world, and I need event X to happen at
> location Y, but the two are incompatible, what can I do? How do I
> build a world that doesn't behave like I want it to?
>
>
>
Ok let's get to it. The reason this: *The obvious solution here is to develop the geography and history side by side, integrating each into the other.* made me chuckle is because while it seems like that is obviously true and should be the simplest, that doesn't tend to be the case.
**In an ideal situation this would be my recommended process**.
1. Create a geographical world complete with map.
2. Define a history based on that world.
3. There is no step three.
...ok I admit unless you are starting a brand new project (or making a sandbox) this isn't likely the scenario you are working with. When you are telling a story you likely have scenes in mind, ideas, plans epic moments.
This is where I can **feel your pain** I have rewritten and redrawn maps more times than I care to admit.
The short answer is unfortunately that there is no simple solution to this problem.
I do have suggestions for you though to help you deal with the problems we all inevitably have.
* **Don't be married to your own ideas.** This one is difficult, I have had to learn to throw away. These were things I thought I had to have. Being willing to eliminate (always save the idea somewhere) or at the very least being willing to modify them will make your life much easier. Maybe that fortress doesn't have to be in the mountains after all.
* **Be flexible with both the world and the story.** Think of this process as shuffling a deck of cards where one half is geography and the other history. The process you are working on is weaving them together.
* **Be creative.** Come up with new ideas rather than always trying to smash existing ideas together. For example, your city in the foothills that was part of a major battle on the plains. What if the city was mostly destroyed in the battle, heck the battle could be named after the city, and after it was over the survivors fled toward the hills and rebuilt. It could be a part of the city's history AND allow the battle to take place on a plain.
* **Discuss your ideas with other people** Its really easy to get settled with where things are at, having a new set of eyes take a look for you may help immensely. A friend of mine and I are both big nerds (we play DnD etc together) and when we go sit at the bar for a few hours it never fails that we start talking about campaigns, alignments (always entertaining) and story ideas...If you are going to do this at the bar I recommend something to take notes...it can get a little hazy the next morning otherwise.
* **Search for new ideas** Maybe this comes from conversations in the idea above, maybe from a movie, a comic book, video game or whatever. You get the idea, keep adding to the pile and you may find the right piece. Always keep the flow of new ideas and content going. I keep a notepad program on my phone just for this purpose...write it down...right away!
This brings us back to this....
>
> The obvious solution here is to develop the geography and history side
> by side, integrating each into the other.
>
>
>
It is not the easiest, but in my experience this will give you the best, most consistent world and gives the world great depth and the history appears integrated and natural.
[Answer]
Try not to oversimplify, do not underestimate nature, do not overestimate humans.
Simplifying is something needed when worldbuilding, simply because the process is too complicated for us to extensively understand. However, if you want to come up with a self-consistent world, by simplifying the rules of your universe, you may exclude possible phenomenons to occur, then closing yourself some doors.
I am not sure it exactly what you wanted, but as an example, here is [a giant plain in a mountain chain](https://en.wikipedia.org/wiki/Tibetan_Plateau) and here a [way to create mountainous islands without using tectonic plates](https://en.wikipedia.org/wiki/Hotspot_(geology)).
It leads me to my second point, do not underestimate nature complexity. It can probably produce things you would not be able neither to imagine, nor to explain ([seriously, moving stones ?](https://en.wikipedia.org/wiki/Sailing_stones)).
The conclusion of this two first point is that it is actually really hard to now if a geographical setup is actually not possible, and you may fall into the old trap to come up only with *likely* setup, which is far narrower than *realist* setups.
But how to come to now all that stuff ? I honestly do not now, I personally tend to crawl randomly in Wikipedia, but if it gives you more possibilities, it does not help you checking if a particular setting is realist. Well of course you can ask it here, but neither of the option is a systematic approach to the problem.
You may have notice that I have not so far talked about history. Here comes the part about not overestimating humans. Your problems in fitting history and geography is that you tend to expect your populations to follow a reasonable way of thinking. They not necessary do.
You can actually test if your humans are too reasonable by asking some historical question : would your generals ever accept [sending more than 500,000 men to invade Russia in winter without assuring supply](https://en.wikipedia.org/wiki/French_invasion_of_Russia) ? Or would your people [fight among themselves when their empire is threatened from everywhere](https://en.wikipedia.org/wiki/Crisis_of_the_Third_Century) ? If the answer is "no" then your humans are too reasonable, and you can clearly afford to make them a bit more stupid to explain your world.
In conclusion, I think that you have way more possibilities than you may think at first glance. You can use this freedom to make your worlds fit your needs. Of course, your capacity of playing with geography and history without ending in a contradiction or unrealistic result depends on your expertise in the domain (team work may actually help a lot).
In the end, I admit, the only true advise that answer actually contains is "Learn more about the real world, it will give you freedom". It is a bit disappointing I guess, but, to me defence, you have already cleared a large bit of the other possibilities in [your own answer](https://worldbuilding.stackexchange.com/a/35437/9779).
[Answer]
I've run into challenges like this both in world building and elsewhere. Most typically it occurs when I try to take on a large effort and have to make simplifications to keep it tractable. If one's preferred simplifications are harder and more universal than absolutely necessary, one can artificially remove solutions from the playing field without fully considering them.
To give an example, from your question, it is very easy to restrict Science to truly scientifically defensible effects. This can lead to "inevitable" decisions. In reality, the reader may have cared about the "inevitable" decision, but all those little events which lead up to it might have been massaged to avoid it. Maybe 3 small "creative interpretations" of plate tectonics a few million years prior could be enough to give you a short lived plain to fight on thanks to glacial scouring and a conveniently timed warming trend (short lived being maybe 100,000 years). The hard part is when those 3 key points are so far from the question at hand that you can't even sense that they offer a solution.
In the real world, the answer is simple. Geologic activity occurs on such a longer span than human existence, that geology does what it does, and History fills in after it. In world building, however, we have more power than that. We can let Geology and History intermingle, trading off the location of rivers for the rise and fall of kingdoms as we please. Its very powerful, but makes things more complicated. Its hard enough to trace back through Geology to find the small shifts that make your world a reality. It's even hard to trace back and forth between Geology and History tradeoffs to find your perfect world.
The solution I often turn to is an [agent based](https://en.wikipedia.org/wiki/Agent-based_model) approach. The basic premise is simple: if I lack the dynamic range to build the entire world in one piece, I can instead focus on a bunch of interconnected smaller problems. I lose some control over the final world, but I know I wasn't succeeding at making that world anyway. In exchange, I gain access to literally limitless detail. Some of those little details might have the key to making my world a reality, or even identify a better world that I didn't even think to make in the first place!
The idea is simple. You spawn any number of "agents" you please, which all seek to craft the world using their own free will and creativity. Sure, they're really just bookkeeping devices, you'll have to supply your own free will and creativity, but they supply a necessary element: boundaries. When you're figuring out what an agent in charge of making a plain would do, you can just focus on the narrow issues at hand.
Figure out what each agent would want to do. Then, you shape the world a little. **Treat this as a democratic autocracy: they vote, you decide.** You collect all of the agent's opinions as to what should happen (alternatively: your own opinions when you bound yourself into each agent's POV). Their opinion is a key guide, but in the end its your world. In the end, this approach permits you to clone yourself a bunch of times, and see how the crowd of HDE 22686's might solve the problem.
The basic process described above is obviously under constrained. All it really says is "pay attention to the little stuff, then make the world." However, the structure of this agent based approach permits you to add more flavor, constraining the solutions until you arrive at something you like. These constraints have the advantage of being very human-like, so we have lots of experience applying them. Here's a list of some of my favorites:
**Self-reflective goals**: You can always make an agent whose job is to build you a plain for a battle. However, those agents tend to start acting very single minded, and they don't inspire you in any creative ways you hadn't considered before. Self-reflective goals permit an agent to refine their goals as you go. Simply change the wording of the goals for any agent to refer to themselves or something they might have. Instead of "Ensure this area is a plain, so a battle can be fought here," permit the agent to instead have a goal: "I have an image of a fight. I should adjust the geology until this fight can be a reality." Then, if another agent can suggest a better fight, they may be able to take that image and work with it.
**Balanced desires**: Agents are also boring when all they do is try to instill their worldview on the world around them, without looking at what they already have. It's like a sculptor not considering the grain of a marble block before starting to carve his idea of a bust. Instead, try to have each agent's world view slowly reflect the world around them, while they seek to shape the world according to the world view. This sounds strange, but its incredibly powerful because it forms a feedback loop. It leads each agent to start having its own personality, so your world doesn't look like it's made by 10,000 Agent Smiths. It also inspires creativity, because its very difficult to predict what a complex system of feedback loops will do. The result of those loops may serve as a muse, suggesting directions for your creativity that you never even thought of. One of those directions may even solve your problem!
**Flexibility and Optimization**: Its easy to write requirements like "make sure a castle appears here in the year 1200," but hard edged requirements like that often lead to the agent based equivalent of bickering. Instead, it works better if there's some flexibility. Give them a metric, such as "100 points for a castle here in 1200, and -1 point for every 2 years it misses that goal by." Optimizing a balance often leads to solutions that were not considered before because it softens the requirements. The agents don't give up on what they hold dear, but they are less likely to rip eachoether's head off when things go wrong (What do you mean you put a swamp there? Ugg! Now I'm going to have to build 3 more castles before this, let each one sink into the swamp before I build the 4th!)
Done right, you should find your agents shift their focus to draw your attention to the most important details in a very flexible manner. You'll find things you thought were important but actually were not will slowly become less and less important to all of these agents. Meanwhile, you may find that some details you never even thought of suddenly become a contentious battle to be resolved. (all the world in one girl). And I think that's really the point. You still know how to world build, all you need is a system to shake it up a bit and draw your attention in directions you hadn't considered!
[Answer]
Why try to make the two work together at all? It turns out that I can have my cake world, and eat build it, too.
Many of my conundrums arise because of other geological features that must exist for feasibility issues. For example, think of the mountainous islands I mentioned in the question. The northern extent of the mountain range on the mainland must exist where it is because the collision of two tectonic plates will not simply cause one small archipelago to have mountains, while the surrounding mainland does not. To address the feasibility issues, all I have to do is destroy these secondary features. To do *that*, I have several options, which I'll illustrate with my mountainous island city setup.
**Magic**
I'm one of the Tolkien fans I mentioned in the question, and many of my worlds have medieval fantasy settings, with a touch of magic. If I need to get rid of a mountain range, all I have to do is invoke intervention by the Lityish Clan of warlocks from the far north. Here's how I can acknowledge that in a story:
>
> "There used to be great mountains here, when I was a child," the old man said, sadly. "I used to play in the foothills, by the banks of the great river Gela. But then this changed." He furrowed his brow, and his eyes flared in anger. "The Lityish Clan intervened, angry at the king. They were unhappy because of the defeat of the Pov'tish at the Battle of Gela Delta. So they took away the mountains, and the forests with their wood, and even Gela itself." Anger took hold of him again. "They will pay one day."
>
>
>
Another option here is, of course, divine intervention, but I tend to leave that out of worlds. Religion may be present - indeed, it is often present, in some form or another - but I like to leave gods out of things like this. Otherwise, the resulting baggage tends to drag the world in directions I don't want it to go.
**Time**
The world is always changing. The forces of nature build up mountains and erode them down to nothing. Valleys are carved out of the rock as glaciers barrel through, but eventually become flat again. In a story where one part of an event happens in the past - say, a famous battle on a flat plain that led to a ruined city nestled in a valley that should not exist - I can simply say that the battle happened a very long time ago. In the intervening thousands and thousands of years, glaciers came and went, and when they left, a valley remained.
You might argue that these timescales are unrealistic, but in many cases, they're just fine. I once again reference Tolkien's histories, and his Ages that lasted for thousands upon thousands of years. For those not familiar with the chronology of Middle-Earth, I'll put it like this: Elrond should have retired a looong time ago. Ice Ages don't have to last more than, say, ten thousand years, and that seems like a timespan in which an old, mysterious (and magical?) character could live through.
This doesn't mean that characters have to live as long as Elves, just that two events were separated by a decent span of time and, for some reason, not much changed in the interim. Here's how I can put this into a story.
>
> "There used to be great mountains here, long, long ago," the old man said, sadly. "The stories have been passed down over the centuries and millennia. Those who lived and fought and died in the Battle of Gela Delta are naught but dust now, but their memory lives on." He paused in thought. "Were it not for the efforts of the scholarly Monks of Tine, this and so much of our ancient history would be forgotten."
>
>
>
Or, if we make this old man an Elrond-ish figure who's been around for quite some time:
>
> "There used to be great mountains here, when I was a child," the old man said, sadly. "I used to play in the foothills, by the banks of the great river Gela. But then this changed." He had a faraway look in his eyes. "You youngsters, you have no knowledge of what it is to live through the dark ages in the dusty corridors of time. I have lived through fire and ice, and seen my home in the mountains taken away." He paused, now brought back to the present. "But by the cycle of nature, once more, in the far future, those mountains will rise again."
>
>
>
Let's face it, most of the time, it's not necessary to get every little thing right or completely accurate. Sometimes, it's not worth worrying about.
**Don't explain it**
The option that I never like to use is to simply never explain why there is a paradox here. After all, many readers or explorers of the world might not pick up on why certain situations are impossible. So I can simply go on building my world and suck it up. This is, however, only an option I use when building a world for a story. Otherwise, I tend to get annoyed. After all, [something is wrong in my world](https://www.xkcd.com/386/)!
>
> "This broad plain extends as far as the eye can see," the old man said. "It is what makes the trade routes from Celtan City to Deynar Province possible. If there were hills or mountains here, like there are to the west, this land would be impossible to traverse."
>
>
>
**Cut the whole thing**
The final option, of course, is to rework the entire world so that none of this happens. Get rid of the island, the mountains, the river, and the rest of it and start anew.
>
> The old man said nothing, because he, like the great river Gela and the Ltiyish Clan and the Pov'tish and the Battle of Gela Delta and the scholarly Monks of Tine and Celtar City and Deynar Province were never created.
>
>
>
This is perhaps the worst option, and should only be used if the paradox proves so bad that no alternatives can be found. Really, it shouldn't be used at all.
[Answer]
I would like to take a different stand in this question. You have wiggle room!
Even though the formation of a landscape is an open process, with a lot of variables to play around with, the end result is nevertheless governed by the laws of nature. Obviously, you can chose laws and patterns that differs from what we have observed so far, but the core principle remains:
**Geography depends on logic**
Let us take a look at the other side of your "dilemma". I can try to sum up human behaviour in a short statement:
**Humans are totally batshit insane!**
What do I mean with that? I mean that how humans propagate through, and manipulate a landscape over time is very unpredictable, bordering to directly improbable. Let me show you some snippets from the real world:
* Czechoslovak legionaries once conquered all the large cities of Siberia, including Yekaterinburg.
* Guyana has the fifth largest percent of Hindu population in the world.
* Iceland is the largest European producer of bananas.
Is that something you can predict from geography alone?
"All settings can fit every story." That is a horrible claim, I know, but things are often easier to solve than they seem. I DO NOT say just hand-wave it, that is no fun.
That feeling of banging your head against the wall because of a particularly difficult compatibility problem is one of the things that make world-building so exiting. Reboot, change the world, see it it worked, if not, repeat.
>
> So when I'm trying to build a world, and I need event X to happen at location Y, but the two are incompatible, what can I do?
>
>
>
Hmm... If you really need that plain because of cavalry, it must be there. I might object that even though cavalry was not good for forested mountain slopes the last time you checked, that is certainty not stopping humans from trying.
Let me conclude with the boring answer. Build both your story and setting part by part, and integrate them into each other as you go. If you get stuck, try to include some of the never ending human madness, that usually does it.
] |
[Question]
[
>
> If you've never been in a shower fight you cannot possibly imagine the pain a wet towel can inflict..
>
>
> Pete Williams, 12b Avergreen Road, 4th grade, likes Brussels sprouts1
>
>
>
---
A [towel](https://en.wikipedia.org/wiki/Towel#In_popular_culture) can be many things. It can be a means to wipe oneself dry after a dip into the cold wet. It can be a used to cover a chair before sitting, or coat an ugly cousin's face. It can be a friend in the dark. And, it can be a [weapon](http://tvtropes.org/pmwiki/pmwiki.php/Main/ClothFu).
Towels are the probably meanest armament to make it into the arsenal of grade schoolers and above. And while *they* may be perfectly confident with drenching their dry-off-implement before whipping it at each other; *we* are somewhat more ambitious!
Our plan is to create a *gun* with the following characteristics:
* can shoot *wet towels* ammunition
* mostly precise over a distance of roughly 3–4 lengths of a standard towel
* the ammunition should achieve this nasty *whip-slap* effect on skin that we know and enjoy from towel-fights
* make us the king of towel-fights
---
**Q**: How to create such a towel gun so we can achieve that satisfying wet whipping effect?
1Honestly, ~~what kid~~ *who* on God’s [green](https://en.wikipedia.org/wiki/Red) Earth likes these things? NO ONE, THAT'S RIGHT!
[Answer]
# Shooting
I was at a basketball game and the [costumed entertainer](https://en.wikipedia.org/wiki/List_of_National_Basketball_Association_mascots) was giving out T shirts using an air gun of some kind. The shirt was folded flat and rolled up with rubber bands. A towel would work just as well. A wet payload work work the same, if you adjust for the increased mass.
The range was considerable, shooting from the playing floor up into the lower tier of seats.
This is the first thing I thought of, and I think they are commercially available. But shooting a compact projectile is not what you had in mind. But, the only answer posted thus far does that, so I decided to mention it too.
# Whip-slap effect
You did specify
>
> should achieve this nasty whip-slap effect on skin
>
>
>
so this rules out a rolled up projectile.
You need to perform the whip motion. This means a device that grips one end and like a robot arm will shake it just like you would. It can be a simple piston, but with computer control to time the swing.
The problem is that you can’t *throw* a whip! The device is limited to holding the towel at one end. If you “cast” the whole towel, it will not do the whip thing.
So, make the arm *long*. It telescopes or unfolds to a considerable distance while imposing the whip motion, so the snap is delivered at the farthest reach.
If you want the effect without the same mechanism, consider just the tip that delivers the blow to the skin. A small corner is propelled to high speed (faster than you can throw) via a [transverse wave moving through a tapered media](https://en.wikipedia.org/wiki/Whipcracking#Physics).
But if you just want a square inch of wet cloth to hit the target at high speed (matching the hand towel whip, based on experiments), you can use an air gun that fires a wet wadded piece of cloth of about 2 square inches. Just the corner of the towel, in other words.
## Practical issues
Today, you would not be able to bring a pistol-looking device into the locker room and wield it while people are showering. Just having it would be too much of a spectacle.
So make it not look anything like a gun. Any wand-shaped piece of sporting equipment, chosen to match what is around, is used to conceal the barrel. A hose can lead to a hidden compressor elsewhere, or make use of an existing compressed air source on the premises.
[Answer]
# Compressed air gun
A younger and sillier me used to use PVC pipe, some glued on fittings, and a [portable air compressor](http://www.homedepot.com/p/Porter-Cable-6-Gal-150-PSI-Portable-Air-Compressor-C2002/203162815) to give projectiles some oomph. You can absolutely blow parts of a fence out with baseballs that way, not that a mild mannered kid like me would ever do such a thing.
I hesitate to call it a potato gun, because we always used baseballs. The secret to success was learned watching Revolutionary War re-enactments: wrap the baseball in wet paper towels and ram it into the chamber using the axe handle. Then, when you blow the air in, you get a good seal the entire way down the barrel and pretty solid muzzle velocity (it helps if you grease the inside of the barrel with Crisco, too).
To adapt this for a towel, simply wad the whole towel up, soaked in water, and put it in the barrel. That should provide a plenty good seal for some serious muzzle velocity.
# Older kid variant
As I got older, simple compressed air didn't do the trick any more. We needed FIREpower. If you glue a BBQ grill starter into a 'chamber' of a PVC pipe, then fill the chamber with [ether](http://www.autozone.com/deicer-and-starting-fluid/starting-fluid/valvoline-11-oz-extra-strength-starting-fluid/7877_0_0) (most combustible thing we found), you can then ram in your baseball wad and get a pretty good pop.
Make this even more effective by soaking your paper towels/actual towel in gasoline. Not only does that provide more fuel in your chamber, but also tends to send the payload out on fire. Especially useful for night fire exercises, though to be honest, I think the air cannon had more muzzle velocity.
[Answer]
Initial thought was a balled-up towel, but you want the sharp slapping effect, so I'm gonna go a slightly different route.
I'm thinking a design similar to a crossbow, except instead of firing in a linear fashion, a high speed arm moves in a semi-circle with one end of the towel (preferably with weighted ends to maintain speed and shape) before release, causing it to fly similarly to a bola or tomahawk, delivering the satisfying wrapping *smack* so iconic to wet towels.
It doesn't even need to be high-tech, you could probably build one spring-loaded with a trigger release. Especially at short/mid range without becoming lethal. Although practicality probably depends on what size is "standard towel", if we're talking skimpy-wrap hotel-pool towels, then definitely. But if we're talking proper large'n'heavy beach/bath towels then there might be a problem.
[Answer]
A [bola-launcher](https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=8&cad=rja&uact=8&ved=0ahUKEwj8s_r7xsjTAhVBRCYKHdfYC8oQFghDMAc&url=http%3A%2F%2Fwww.google.com%2Fpatents%2FUS6381894&usg=AFQjCNFFpauNxCZph2Uxl-tG4E-DDLoSJQ&sig2=gY8a9X9gQfv-KPbCuJ7OaQ), modified, should do the trick.
Since you're looking for the "whip-slap" effect, you need a projectile that is long, thin, flexible, and hits sideways. Obviously a whip is the first connection, but that's still at close range. The possibility I thought of for a longer range weapon, that has the same kind of strike, is the [bola](https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0ahUKEwihrdnYyMjTAhVGbSYKHdSGBpUQFggnMAA&url=https%3A%2F%2Fen.wikipedia.org%2Fwiki%2FBola&usg=AFQjCNHZPh0M_aPOI6r_ZP5A6-8T5lGyng&sig2=3SJ5qdXJMA1vmkaW8GAi0A).
A bola consists of rope with heavy weight on the ends. It is swung and thrown, and it hits the target with the rope, letting momentum wrap the weights around the target to tangle. Obviously, since this is a weapon, the momentum behinds the weights striking can do a good deal of damage - not ideal for our purposes, and the reason the concept needs some tweaking.
So, the bola needs weights on the ends to make it easier to launch, otherwise there's no way for a light rope to get enough momentum. A towel would probably weigh less, generally, than a bola - but this is indeed counteracted by the weight of the added water. A towel would also have more mass in the middle, less on the ends. This would not be great for the spin-throw that a freehand bola uses, since the weight differential helps build up momentum, but since we are using a bola launcher anyway, that is less important. I think we will still need weights on the ends, for launching and stabilizing the throw, but they can be smaller.
With more weight in the middle of the towel and less on the ends, and greater air resistance to the volume and mass of a towel compared to rope, this "towela" is probably nudges itself out of the dangerous-weapon range and back into the merely painful category. I'm sort of picturing a longish, narrow towel with each weight connected to both corners on the narrow ends, for the little parachuting imagery it gives me.
On to the bola launcher. A bola launcher, from what I see, uses two parallel (and identical) mechanisms that grip the weights and launch simultaneously when the trigger is pulled. The mechanism could be similar to a (double launching) [crossbow](http://theawesomer.com/bola-launcher/242412/), or as complex as any mechanical launcher or firearm.
[](https://i.stack.imgur.com/klYDC.jpg)
Our "towela" launcher would need to be somewhat stronger, as a wet towel will be heavy and the distribution of mass would mean more resistance - so more power needed to effectively launch the towelas. The loading mechanism would also need to be modified, towels being thicker and the connections to the weights would be wide and clumsy compared to rope connectors, making it harder to reliably grip and release the weights unless some thought went into it. It would take some practice to learn to balance factors like distance, strength, and materials to make precise effect desired, to quickly load, arm, and otherwise manage the towela ammunition, and to reliably aim at and strike the targets.
Of course, since we're modifying the towelas anyway, there are some extra possibilities. A cotton towel (think tea towels or dish towels) is thinner and lighter and so will need stronger weights than a heavier terrycloth towel, but can generally act more like a bola in strength and force. If the towel is straight between the weights, it will have more air resistance, less force, and more surface area hit than if the towel is twisted (it will then act more like a rope than a parachute). The towela can be loosely or tightly twisted for further control over the force vs resistance balance. And, it may be possible to add some padding to the weights themselves, to minimize the distraction from the blow when the weights land, in order to maximize the snap-whip effect from the towel's sideways blow.
[Answer]
So we are looking to create a weapon that causes the ***whip-slap*** effect at range. I think the power involved is called Torque. It needs the water in the towel to store the energy. With a pivot point to give it the momentum. Aka, whip.
Now, we don't want a long arm to dish out this wet towel *whip-slap*. That can get nasty in the closed environments where we do battle with towels.
---
## The *whip-slap* Towel Catapult
**Theory**
Create a way to rotate the wet towel to hi speeds and send it off to intended target.
Now, in idea it is close to the [Shuriken Catapults](http://warhammer40k.wikia.com/wiki/Shuriken_Catapult) of the Eldar (Warhammer 40K). But alas, I could not find blue prints...
**Build**
So we have 2 round plates that hold the wet towel (smallish towel ~60cm (2 feet) diameter). Those are mounted on a frame that let's you spin them up to speed with a cordless power drill. When you hit the release button the spinning plates, with the wet towel, move ~1m forward over the frame. Here forward speed is created with [rubber tubes](https://www.youtube.com/watch?v=qxtHtPK2MH8) (youtube) that work as springs. At the end of that open up a bit to release the towel. That will fly towards the target, [Frisbee style](https://www.youtube.com/watch?v=gI8_PMO3XWU).
I don't think you will be able to be sneaky, stealthy or fast with this one. But you will have reach. Maybe enlist someone to guard you while you reload and aim. (don't aim for the head)
Happy slapping!
[Answer]
Since there are already plenty of ways mentioned to *fire* a *wet* towel somewhere, I have an idea for the 'whip-effect'.
Above mentioned arms etc. are nice, but then the gun becomes a whip again, since OP wants a projectile, how about adding some "breaks" to one end of the towel.
You could use some kind of parachute or even retrorockets, put them on one end of the towel and fire it at your enemies.
Only problem is, that the effect only works for a precalculated/preconsidered range, since the parachute opens more or less always at a certain range, which restircts the range of the towel-whip. With retrorockets one could avoid it by remote triggering the ignition of said rocket to adapt the range of the "gun".
---
Little addendum:
In case you want to "pimp" your little shower friendly RAT-gun1, you could add a water tank to your gun, to wet your towel prior to shooting some poor fellow. So the towel won't go moldy if you don't use your gun for a few days.
Added bonus, in case of zombie apocalypses, alien invasions or similar events, switching the water tank for a gas tank2 could give you a little survival boost.
1Rocket-Aided-Towel-Gun, not to be mistaken with a device called Rat-gun, which fires vicious little critters and which should be banned in all civilized countries
2A burning towel-whip-projectile, ignited by the retrorockets, has the potential to frighten even a well travelled alien. If the aliens win despite your resistance, at least they have to make new towels and will be hindered to hitchhike to the next planet for some time.
[Answer]
Take the wet towel, give a mad scientist cackle, and combine it with a spear fishing gun and a T-shirt cannon.
First take your towel, roll it, and add a weight at one end. This weight must be heavier than the towel, even when the towel is wet.
Take the reel mechanism from the spear fishing gun. Attach the end of the line to the weight. Modify it so that you can, on the fly, stop it and control the distance at which it will stop. Add a winching return mechanism.
Attach the reel to the T-Shirt cannon. Beef it up to handle the additional mass of the wet towel, weight and line.
Take aim at your victim, pull the trigger, then hit the stop on the reel just short of the distance. The line snaps taut, causing the weight to suddenly stop, thereby whipping the other end of the towel around at the victim at welt raising speed.
Hit the return on the reel to bring back the towel, stuff the weight back into the cannon, and select your next victim.
Of course this will take a little practice to get the range right and you may cause some concussions in the process with the weight arrangement, but it will be worth it. It's for science and the domination of the pool side and the locker room.
[Answer]
I see two mayor problems with your request (please bear in mind I'm not a scientist and I'm not an English native, I may explain quite badbly... sorry about that).
A) When a projectile whipslaps, it basically kills off a lot of rotation. Space satellites "play yoyo" with dispensable whipslaping parts as a means to stop rotating (<https://en.wikipedia.org/wiki/Yo-yo_de-spin>). So, your projectile has to whipslap just the right moment, because it will have no energy for a second try.
B) the towel is a non-newtonian object. It's not rigid, it's not solid, and in fact its center of gravity isn't "fixed" in a certain point, since it's a moving fabric and air will effect it in the air.
So, bad news. You need micro miniaturizing...
1) A device to "make it whipslap" at the right distance to target.
2) A way to detonate the whipslap itself.
Antiair rounds in WW2 used a doppler sensing radio device, but that was a shell thrown to a solid object. Maybe a solid core with the towel wrapped around, tied by a cord joining the towel back to the weapon? Throwing the towel as a fabric envolving a rotating axle-like core linked back to a brake back in the weapon? You shoot, the piece rotates "winding up" the towel, cuts rotation when a doppler sensing antenna in the axle notices a solid mass at the right distance and makes the thing to whipslap by inertia.
Could work, but the problem is, the projectile will be rotating in an axis 90° opposite what you need for an stable projectile. It will not stay pointing the right direction. AND projectile tied to the weapon means the shooter will get pulled by the thing when it detonates.
So, to sum up... hard to detonate at the right time, hard to aim, short range, single shoot, bulky as hell, will pull the shooter. Not an easy thing, you know. Not at all... I'll say "possible but unpractical".
] |
[Question]
[
The common evolutionary belief is that life originated in water, and that it developed to survive on land later on. Eventually, mammals evolved on land.
Cetaceans, which include dolphins, whales, and other marine mammals, then evolved from land-dwelling creatures, going **back** into the water.
[](https://i.stack.imgur.com/yc6cH.jpg)
Some believe this change has made it unlikely for cetaceans to revert back to life on land again. Notably:
* Their **legs atrophied** over time and now they rely on one pair of fins and a tail. These are not as suited as the two pairs of fins and relatively smaller, lighter tails that the first amphibious animals had.
* Some have **twice as much hemoglobin** as most mammals, so they don't have to come up for air as much. If they breathed air constantly, they would receive twice as much oxygen - which may cause fluid buildup in their lungs, pain, and eventual suffocation.
* Many of them are **enormous**. The square cube law means that they would have to evolve to support their own weight out of water, which is simply not feasible for larger species.
* **Echolocation** is suited for use underwater - some cetaceans cannot communicate on land.
* **Baleen** designed to filter small food is useless out of the water, so there is no feasible way for some species to eat out of the water.
Of course, if mammals completely unsuited to life underwater can evolve into whales and dolphins, it must be feasible that cetaceans can eventually evolve to walk on land once again. *Just as these changes can be done, they can be undone.*
---
**What natural evolutionary pressures would cause these problems (and others) to vanish, allowing both whales and dolphins to become land mammals?**
Assume there is no human intervention, and the world is normal. General-purpose answers work - you do not need to address specific concerns for every subspecies, just "whales" and "dolphins" in general. Assume the whales in question are species with baleen.
[Answer]
Many marine creatures temporarily "beach" themselves for a variety of reasons, including food. If climate or geological events left ocean food supplies decimated, critters that could hunt on shore would have the distinct advantage of not starving. Once the "low hanging fruit" close to the water was consumed, differentiation in gene lines would let some individuals spend more and more time out of the water. Mutated traits for heavier limbs, lower body weight and rebalanced metabolism would be selected for. Given time they will shed features that were advantageous in water but a literal drag on land. If the ocean's life and nutrient cycles aren't restored, aquatic life would become a distant genetic memory.
Nature would re-use biological mechanisms. Echolocation hardware can be repurposed for hearing sound through air to escape predators, communicate danger and find mates. Each of these is an evolutionary advantage. Half-working ears that accidentally trigger flight response means you pass your mutated ability on to a new generation while your neighbor gets eaten. At some point the aversion to smoke against what used to be a gill will keep a bloodline from walking into a forest fire. All these little mutations, responses and abilities will eventually result in a variety of land-viable species as they create new niches in the rebalancing ecosystem.
Hemoglobin may not be that big an issue. A newborn human's normal levels vary from 10 to 18 g/dl and a dolphin's levels may reflect its environment more than its genes. We have multiple overlapping systems to preserve homeostasis. Dolphins deal with a greater range of atmospheric pressure and their hemoglobin balancing systems might be fine tuned for this.
Baleen whales do face a new gross physical challenge, but even the krill eaters eat fish by accident. Maybe whalebone would be useful in sifting nutrients from beach sand. If not, and if nature doesn't find another use for those organic mechanisms, they're going to be under heavy evolutionary pressure and be one of the categories that get wiped out.
Now I have images of poisonous tree-climbing squid swooping in unsuspecting prey like a flying squirrel. Nature is metal.
[Answer]
You need to eliminate all vertebrate life on land so they have no competition. This is going to take a long time. Whales and dolphins are extremely specialized, so you need to remove as many obstacles as possible. Any terrestrial vertebrate will be able to fill open niches much faster than whales and dolphins. You need nothing in the way so the the highly disadvantageous specialized adaptations don't matter.
You need to get them into swamps to have them start redeveloping feet and hind limbs. It will be dolphins, whales just won't happen due to their size, you need small animals to make such a transition. So if you absolutely need whales you need to get rid of dolphins so whales will expand into their niche with smaller size.
Hemoglobin is an insignificant problem easily changed, and echolocation works on land (see bats). Baleen again requires the elimination of toothed whales and dolphins to encourage them to re-evolve teeth or an analog.
If you just need one or two species of toothed whale (or dolphins) to do it, it is not to bad. You use killer whale beach hunting behavior to encourage more terrestrial adaptations, but that won't work for baleen whales.
[Answer]
I'm not sure what the etiquette on this site is regarding reposting [answers to past questions](https://worldbuilding.stackexchange.com/questions/47692/how-would-dolphins-look-if-they-evolved-to-human-levels/47704#47704), but I remember answering a similar question on dolphins readapting for life on land, that might be useful here. Whether the reason I remember this answer is due to my fondness for the goofy MSPaint image I made to accompany it is neither here nor there...
[Answer]
One of the key factors here is to realize the shift from land animal to whale was over 55 million years of evolutionary pressures...it's not a short shift by any means that will include many staging points along the way. It's also worth noting that there were several failed steps along the way that eventually went extinct as they were not able to adapt.
First and foremost, the pressure to get out of the sea must exist...and to do this I would go one of two routes.
-1 massive predator...with some warmer waters, it is possible to reintroduce the Megalodon, an absolutely massive shark. This shark relies on deep water to hide itself, locating a prey (whale) near the surface, and swimming quickly for a surprise attack from the depths. This makes deep waters exceedingly dangerous to the whale and dolphin populations and forces them to shallow water habitats. This would likely bring about the extinction of larger whale species as they die off to this new competitor. Dolphins and smaller whale species are only capable of surviving because they can function in shallow water.
-2 toxin or 'dead' zones become prevalent. Algae blooms and other natural phenomenon can become rampant. These blooms consume the oxygen from the water making for large dead zones. Since ocean mammals still breathe air, they are not directly impacted, but their food source sure is. This forces them to where the prey is...shallow water. Once again, larger whale species won't be able to transition to shallow or they would be unable to find the scale of food they require in shallow habitats. Small whale species become dominant.
In either case above, you now have the whale population either extinct or in shallow waters. In deep ocean, speed has the advantage...in shallow waters, agility dominates. Over the next million or so years, the whale population slowly adapts to become more suited to quick movements instead of fast speeds.
Out of this comes the ability to 'push off', using the tail to fling itself off of the ground or nearby rocks to reach top speed at moments notice. At this stage (potentially 3-4 million years in the future) the whale now has the shape and predatory tactics closer to that of a crocodile (kutchicetus or potentially ambulocetus) where it lies in wait, in shallow water, until a prey species comes by for them to quickly strike at. This creature would have descended from the dolphin populations, but no longer resemble much of a dolphin. Legs for pushing off could begin development at this stage (potentially 5 million years in the future, maybe longer). Sonar and the sort will have gradually faded away, allowing more of the brain to be used for sight and smell.
And at this phase you need something to push them fully on land...a shifting landscape (like the Americas seperate allowing the ocean current to flow between north and south america) changes currents bringing cold water into the formerly warm shallows these creatures lived in...forcing them onto land to sun themselves for warmth. Or a change in the prey available forcing the former-dolphin-like creatures further onto land for prey (kinda crocodile like). Over the next few million years, these traits slowly become like the Pakicetus until it's once again a land creature.
[Answer]
While it is unlikely that cetaceans would regain their back legs, it *is* possible for tails to be re-purposed for terrestrial locomotion. Sea lions have done just that, and they are quite agile on land for a primarily aquatic species.
It seems unlikely that baleen whales would return to land, as the main motivation for returning to land would probably be to find food and baleen is useless out of the water. Baleen whales could probably return to having teeth, though, given the right circumstances.
The process of returning to land could begin with a carnivorous whale or dolphin species that "beaches" itself sometimes in order to acquire food. Orcas are known to do this to hunt seals, for instance. Individuals that can propel themselves on land somewhat with their flippers have an advantage over those that cannot. Eventually, they might evolve an amphibious shape similar to a seal, which can then branch out into the more terrestrial sea lion shape. If a fully terrestrial niche opened up, they might leave the water completely. This could lead to a whole new branch of various kinds of mammal that uses their tails for back legs.
[Answer]
# An Empire
There is no way cetaceans could return to land out in the wild. But, a sufficiently long-lasting society could get them started. Specifically, they could selectively breed dolphins or some other creature to be able to survive on land (able to maintain water, keep cool, move about), which could be enough for these dolphins to survive on land if they go feral. However, they'd most likely need some clear space (such as a small island without predators) to actually evolve and not just be outcompeted
[Answer]
I have wondered if with help, Dolphins could be introduced back onto the land with mechanical help. A vehicle or suit in which they could move on land and manipulate their environment might give them a "bridge" that would allow them to participate on land or in space!
Regards.
73
-Grace
NNNN
z
] |
[Question]
[
Other questions have tried to address how big/small towns have to be in order to function, but I'm more interested in approaching it from a different angle: How big would a town have to be to support a given population?
Firstly, let me just clarify that by "town" I really just mean a place where people live, and not implying any arbitrary population cutoffs (as opposed to a village or a city).
For the purposes of this question, let's assume medieval era farming techniques and knowledge. Let's also assume that the town in question can do trade, but trade is infrequent enough (or the town poor enough) that while they could get the occasional tools or a new seed stock, they cannot rely on trade for essential things like supplementing their food supplies.
Given this, and assuming a reasonable variety of crops given the era, how large a plot could a farmer farm? (For bonus points, how much food, and what kinds, would he be producing here?) How much could that be increased by hired hands? For self-sufficiency, how many people would be needed to support this farmer (blacksmiths to make/repair his tools, carpenters to build his house, etc.)? How would this scale if we add a second farmer and plot? That is, do we have to have twice the number of blacksmiths and carpenters, or can a single "set" support multiple farmers?
I hope this one's not growing too broad; the gist is that I'm trying to find a way to determine population size based on the number of farms/farmers, or going the other way to find out how many farms/farmers I'd need to have, given a specific population. And, consequently, what the physical size of the town would be, including said farms.
[Answer]
In Medieval Europe there was a method of land ownership called [Open Field](http://en.wikipedia.org/wiki/Open_field_system) or Strip Farming. In this method each home was "given" several strips of the large field on which to grow their own produce. In return they had to pay levies to the Lord of the Manor (who actually owned the land).
Because each tenant was responsible for their own food and because of the large amount of cooperation involved (different residents would supply different pieces of equipment such as the plough/oxen etc) This is probably one of the best solutions you're going to find. while not as efficient as the large scale industrial farms we have today they can be operated on a much smaller scale.
Theoretically all you need is a large enough population to provide the aforementioned equipment and animals and the village could be self sufficient. Of course once you start needing repairs/blacksmiths/food which cannot be grown the size of the village must increase.
The example I gave in the link above cites Elton in Cambridgeshire (UK).
>
> The village of Elton, Cambridgeshire is representative of a medieval
> open-field manor in England. The manor, whose Lord was an abbot from a
> nearby monastery, had 13 "hides" of arable land of six virgates each.
> The acreage of a hide and virgate varied, but at Elton a hide was 144
> acres (58 ha). A virgate was 24 acres (10 ha). **Thus, the total of
> arable land amounted to 1,872 acres** (758 ha). The abbot's demesne land
> consisted of three hides plus 16 acres (6.5 ha) of meadow and 3 acres
> (1 ha) of pasture. The remainder of the land was cultivated by 113
> tenants who lived in a village on the manor. Counting spouses,
> children, and other dependents, plus landless people **the total
> population resident in the manor village was probably 500 to 600**.
>
>
>
My suggestion would be that if the village is a satellite to a larger town where supplies not made in the village could be bought from (and an insightful Lord who was willing to take responsibility for purchasing the equipment) the threshold for being self sustaining (at least as far as food was concerned) could be much much lower.
[Answer]
I am going to assume you're talking about a settlement in Europe during the Middle Ages. They would have old world crops, including things like cabbage, wheat, and kale. Corn, tomatoes, and potatoes would never show up in Europe until the [Columbian Exchange](http://en.wikipedia.org/wiki/Columbian_Exchange) happened. You can see what they ate [here](http://people.eku.edu/resorc/Medieval_peasant_diet.htm).
According to S. John Ross, in his web article called "[Medieval Demographics Made Easy](http://www222.pair.com/sjohn/blueroom/demog.htm)," the average population density was 30 per square mile. This is an average, but it will give you the sense of size a settlement of a given size needs to sustain itself.
Looking at the definition of an [Acre](http://en.wikipedia.org/wiki/Acre), it's the amount of land a farmer could plough in one day. This being said, you should check out the article [here](http://www.ibiblio.org/london/agriculture/general/1/msg00070.html). It has some numbers which talk about the Domesday Survey, which give you a good idea of how much people produced on their farms. As you can see in the article, there are some problems, but the above resources can give you a good idea of how large a settlement should be for a given population.
It appears most farmers farmed in a group of other farmers on plots of land around 120 acres. You could have 10-12 people working that land, so you could expect a farmer to easily maintain 12 acres of land. It's a lot of assumptions, but it will give you a good starting point.
[Answer]
Other answers talk about food which is certainly relevant, but as the question suggests there are other needs for self sufficiency. For example if we are looking at ploughing you are going to need to have harness for the animals ( and to get useful working lives out of them it should be well fitted ) and the equipment will need to be made either from metal or from a mixture of wood and metal, which means you need to have the resources and skills available to make them or you need to have trade routes to bring them in.
If you are looking at local resources rather than trade you probably need at least a blacksmith, a potter and a carpenter in your town. The value of the work of these individuals in your world will dictate how easy or otherwise it is for them to make a living but it is logical to suggest that there would be a minimum size of location that it would be economic for them to set up shop in terms of turnover. Of course it is not impossible for someone to be a blacksmith-farmer or a carpenter-farmer and there are many tasks that are going to be performed collectively, but if you want to have a truly independent town then they are either going to want to have these skills resident or to have travelling artisans who pass through every season or two and pick up the last few months worth of work.
In terms of work rate it is hard to judge, partly because the quality of the work affects the amount that is required and the speed with which it can be performed. How long it takes to build a plough or a house or a chair is very a much piece-of-string type of question but if you are interested in the techniques used historically a book called *The Doctrine Of Handy Works* is basically a very early DIY manual and contains a lot of interesting information on these topics.
If you don't have the trade routes you are also going to need supplies for your artisans to work with - certainly you will need building materials in any case, but without trade to bring in iron or clay you would need to be able to produce those in the local area and if you are smelting or firing them you will probably also need charcoal, so being in reach of forest would be helpful. This might indicate a forestry economy as well- woodcutters would be another likely trade. Building materials are quite flexible, but worth consideration because whether you have mud, brick, wicker, wood or dry stone available will strongly affect the architectural style of your town.
If you have livestock around you will also need people to look after them and, around working animals, to train them. Ensuring they are fed and kept healthy also requires land and expertise. Again these tasks might well be thought of as farming, but specialisation is an efficiency and with maintenance tasks like farriery and equine dentistry, you might expect that a town would have sufficient work for specialists in these fields.
[Answer]
That would depend on the tech level.
I mean, you could consider a stone-age hunter-gatherer to be mostly "self-sufficient", by himself. Or, if you want something a bit more "permanent", maybe his family or "clan". The men would hunt and gather food, the women would prepare the catch (work the skin and bones, sew the hides, and so on). As long as these tasks can be taken care of, they are "self sufficient", and they need nothing more. So, maybe 10 or 20 members would be enough.
If you consider a medieval community, a "village" could be as small as a few families.
In fact, you could even have people live with fewer inhabitants (like, a lone farm), but it wasn't usual - mostly because of defensive needs. What would change, here, compared to the stone age, is that the technological needs are higher. I mean, sure, you *could* use a stone hoe, or a wooden plow, for your field. But if you want metal tools, which are more efficient, you'll need a smithy, which requires know-how (the smith itself), and materials. Which means charcoal (requiring miners, or charcoal burners), and ore (requiring miners). So, either you consider that to be a very infrequent need, which can be fulfilled by trading (which could be the case it the community needs only a few metallic items every so and then), or you consider that to be a constant need (for repairs, renewal, new tools, etc.), and you'll need people dedicated to that, which increases the needed population.
Science, too, requires people. That is, the pursuit (or merely preservation) of knowledge. Educating people requires... people. As teachers, but also as students. And if these students do NOT use what they were taught, they'll forget a lot of it. Which means you cannot afford to teach many people if it's not going to be *useful* (if it helps in the fields, very good. If it's useful for their trade, why not. If not, they'd be "better off" working already). So, the more advanced the science, the more people you'll need to dedicate to keeping that alive, at the very least (even if you're not trying to discover new things). I mean, "scholars" in ancient Greece could learn about many domains, and know just about everything there "was" to know then. Nowadays, it's impossible for a scientist to be an expert in that many fields. Even just one or two is difficult enough, especially if they have to keep up to date all the time.
For an Industrial period community, once again, depends on what you view as "necessary". If you consider a rural community as "self-sufficient", then food, clothes, and building/combustible materials + builders should be enough. Which means that the size should be around that of a "medieval" community. At the very least, several tens of people, I'd say. But if you want any more, you'll need more people.
If you consider a "journal" to be necessary, you'll need people to write, but you'll also need press (it can be a quite primitive one, printing a single broadsheet, and operated by the person writing the articles) which you'll have to have got *somewhere* (either by trading, or having been built for you by a craftsman on location), and you'll need paper. Which requires more work, and more craftsmen.
If you need animals (for wool, for milk, for meat, for power - as draft or saddle animals, whatever), you'll need more people.
If you need vehicles, you'll need carpenters or specialized craftsmen.
If you want better roads, you'll need cobblers, and people to cut the stones.
If you want power, you might require steam engines (needing engineers to design them, mechanics to create them, and people to take care of them - like feeding coal or wood to them, lubricate them, etc.) If you need electricity, same thing.
So, depending on your technological needs, and what should be done frequently in your community, the needs for people grow accordingly. If you want the level of comfort of a large settlement (with doctors, education, craftsmen of different trades, along with plenty of materials to work with), you'll need way more people (like, several hundreds, or thousands) than you'd need in a more "rural" setting. So, in a way, it all depends on what you're considering is "needed" to be self-sufficient.
And, of course, for a "modern" community to be self-sufficient, once again, if they can trade for some items from time to time (like, buy a tractor, a harvester, a new machine), they won't need that many people - but keep in mind the needs for fuel and electric power. They'll need regularly scheduled deliveries, for fuel - and a way to get electricity, either through batteries, fuel generators, or a power line.
In that case, from several tens of people to a few hundreds should be enough to have a small, thriving village.
If they need to *really* be self-sufficient, that is, make everything themselves, then the minimum population will explode, and come to tens or hundreds of thousands, AND have the required natural resources within reach, too (considering the diverse needs for experts, workers in different technical fields, producers of primary products, etc.)
[Answer]
Climate (adequate rain? too cold? too hot? too windy?), soil fertility, geography (rivers? with fish? flooding? tsunamis? seacoast? mountains?), local resources (wood, coal, iron-ore, etc), will all impact your settlement sizes.
] |
[Question]
[
In many SF stories (or fantasy if you replace *science* with *magic*), there is **one technology that is hyper advanced in one specific field**, like robotics in [Real Humans](http://en.wikipedia.org/wiki/Real_Humans) or in [Extant](http://en.wikipedia.org/wiki/Extant_(TV_series)), but almost nothing else in the world has advanced beyond what we know today.
However, robotics (like most advanced science fields) is **a highly pluridisciplinary field of study**, from mechanical engineering to energy production and storage, to ethics, to artificial intelligence, to human biology (bionics), to human psychology (social robotics)...
**What could lead a society as the one on earth today to focus so much on one specific thing ?** (like building human-like androids) without the technology ever branching out to other applications (improving transportation, treating mental disorders, developing communications, better health system and whatnot).
[Answer]
Investment will go where the money is. How much is invested to fight disease like Ebola compared to the new almighty iphone 6. The world is at stake here.
Money and the need for a specific resource will push people toward one project. Our dependency on oil made us neglect other sources of energy. This is partly because of the strong corporatism and the powerful lobbies. In sci-fi it's common to see a world rules by the mega corporations. I don't believe this will happen but if it does, let's just say that the companies and the governments don't have the same goals. Corporation goals might not look very rational form the point of view of a nation.
And as bowlturner, if mankind face a dire threat they will need to invest most if not all of their resources. Maybe the threat is the climate changes, warfare, an evolved and aggressive alien specie.
That being said, I'm not sure it's possible to go narrow as having progress in just one field.
[Answer]
Generally I would say an extreme event/push on the society. We come upon a problem that requires all of our focus, say knowing that in 3 years a planet killing asteroid has a %90 chance of plowing into the earth. We would focus all of our energies into finding a way to preserve as much of the earth as possible and find a way to prevent the disaster.
We might actually design a generational starship with artificial gravity or make an 'anti-gravity' beam to push the asteroid out of our path. We would likely have a huge jump in one direction like that, but after the danger has passed and we start to feel safe other uses for the technology would begin to seep out into the market for other purposes. Unless of course governments or powerful businesses keep a tight lock on it all for 'national security' or 'protecting profit margins'.
[Answer]
I suspect most stories focus on only one form of hyper-technology simply to examine it's specific impacts without having to worry about a more complex picture.
That said I have a couple suggestions why not this might happen, but does happen.
1) Not all things are equal:
>
> *XKCD*
>
>
>
2) [Once you have a hammer...](http://en.wiktionary.org/wiki/if_all_you_have_is_a_hammer,_everything_looks_like_a_nail)
With many technologies, if you develop one far enough the use of others can be diminished. For example, many individual tech markets like portable music players, camera's, watches and so on have all had hits due to the wide success of the smartphone.
Similarly if one has access to large numbers of semi-intelligent robots, what would be the point in continuing to develop 3d printing, self-driving cars, more labour efficient industry etc?
[Answer]
I'd say that a sudden abundance of easily available food and energy would lead society to a state of wandering. If at that moment a charismatic leader appears, he could bring all people onto one grand idea.
[Answer]
I think its best to understand why technologies are created. 3 main reasons, arguably 2
1.) Easy Access to Food (farming, cultivation, processing etc..)
2.) War- easier to kill others and take their food and resources
Arguably 3
3.) Laziness - ie making jobs we don't like doing easier
Focus on one of these things.
Example Food: Interstellar Movie- extra galactic travel in search of food because of the blight.
Example War: Live Die Repeat (day after tommorrow) movie- mechanized combat suits given to infantry to fight alien invaders and actually have a chance at killing them.
Example Lazy: as mentioned earlier the iPhone giving people immediate access to the internet and essentially computers in our pocket. But this can be further evaluated based on the invention of the internet which is a communication invention and used for purposes of war...
So the initial reason for inventions can have ripple effects on society technology later on which leads to this laziness.
] |
[Question]
[
**Closed**. This question needs to be more [focused](/help/closed-questions). It is not currently accepting answers.
---
**Want to improve this question?** Update the question so it focuses on one problem only by [editing this post](/posts/222/edit).
Closed 9 years ago.
[Improve this question](/posts/222/edit)
Fire (or the ability to create it) is often cited as the spark of civilization, it is so revered that its inventors are [legendary](https://en.wikipedia.org/wiki/Prometheus) [figures](https://en.wikipedia.org/wiki/Suiren) in mythology.
Practically speaking, fire can:
* Keep you warm, expanding your habitat to colder climates
* Preserve, and extract more nutrients from food
* Serve as an effective defense against predators
It doesn't sound like much but when humans had little to no technology, this would have been a great boon.
Suppose however that humans never developed fire-making skills (or much later, after the development of other technologies made it trivial). What effect would that have had on humans?
* Was it crucial - civilization would likely not have appeared without it?
* Was it very important - without which our development would have been delayed, 1000 years? 10000 years?
* Was it not very important - not as important as tools, or domestication?
[Answer]
There are some theories that cooking increases the nutritional value of food (or the range of nutritious foods available) so much that humans would not have been able to develop our current level of intelligence without it. But that's speculative. Let's also assume you live in a climate where you can survive year-round.
Fire is a necessary stepping stone to a lot of other technologies. Without fire you'd never get metalworking, pottery, or glass. The materials that you could use include:
* knapped stone tools
* sun-dried adobe
* wood and vines (but only what you can fell/shape using stone tools)
* animal products including hide, bone, sinew, horn, fur, and hair (though cleaning and tanning are harder without fire)
I believe you can make papyrus or parchment and ink without fire, so it's possible that you could get writing, and a lot of the intellectual developments that follow from that.
Agriculture would be harder without fire because almost every civilization relies on cereals or tubers that need to be cooked. But you could potentially get around that with fermentation, especially if you had some way to make warm water (I guess keeping it at body temperature is pretty good, like the Alaskan gold miners who kept their prized sourdough cultures bundled up in their bedrolls with them).
It's hard for me to imagine a civilization that could get very far without fire. On the other hand, our civilization's penchant for burning stuff might end up killing us all, so maybe the fireless civilization would eventually surpass us, however slowly they move.
[Answer]
I think a society could get on without fire if there are enough natural heat sources that can be safely used (say, some predictable vulcanism). On the other hand, any such heat source will tend to set things on fire, so maybe it would be inevitable that people would learn to handle fire even in that case.
[Answer]
Without fire there wouldn't have been external warmth or cooking. Civilization would have formed to some extent without it. People still would have gathered in towns. People didn't gather in towns to get around fires, they gathered for safety and for trade.
Most starch foods for different cultures require cooking before they are edible.
Fire was the first source of energy that humans could control. Fire was important to the creation of the steam engine, and some other early machines. Fire also allowed the manipulation of metal, another important advance in technology.
I think without fire, technological advancement would have been severely slowed, though civilization may still have existed. We would be possibly thousands of years behind in advancements.
[Answer]
I would tend to agree with the others. With out fire so many of our technologies would be impossible to get to. I would assume that to get very far without fire a different energy source would be needed. The next best bet would be electricity, but that would require a lot of coincidences to come about, making a simple battery is pretty easy but for it to be really useful you'd still need some decently refined metals.
[Answer]
Crucial to the development of civilization? No.
Much of stone-age Mesopotamian technology (irrigation canals, sun-dried brick, wood and stone tools) was not dependent on fire. You could certainly have a primitive agrarian civilization without fire -- or a city-based hunter-gatherer society if you've got something like the Pacific Northwest's salmon runs to provide high natural food density.
Technology is a different matter. You might be able to substitute some other source of high-density energy (lava?), but even if you do, the discovery of fire is likely to be an accidental outcome. The ignition temperatures of common materials such as dried reeds or cotton is well below the temperature needed for many interesting things such as the smelting of copper or iron ore.
[Answer]
Well, humans could and did develop fire far before they developed civilization. In fact, pre-humans had fire, as in Neandethals 200,000 years ago, and even earlier, perhaps 500,000 to 1.5 million years ago, by pre-Neandethals (Homo Erectus) see for example [this NY Times article](http://www.nytimes.com/1988/12/01/world/fossils-date-use-of-fires-1-million-years.html). I don't think there are any aboriginal people who don't use fire, and if not it's by choice; it's not because they don't know about it.
I would say that a world where there are human-like people would only not have fire if it were not very possible, due to some sort of physical limits. For example, the atmosphere might be somehow breathable but not combustible, and/or materials available being fire-proof.
Otherwise, it's extremely easy to learn, and extremely useful, even to pre-humans. If it weren't possible, technology would have developed very differently. Other sources of great heat that *did* exist in such an environment, may have taken on much greater importance.
] |
[Question]
[
Well, today I have a fairly simple question. Is it possible for a human to have some sort of birth defect, mutation, disease or something that causes the human body to be unable to produce body heat?
[Answer]
Nothing that simple. A lot of physiological mechanisms in human body depend on the temperature. Blood composition, immune system, energy transfer. Exceeding the temperature by 3 degrees causes effects like hallucinations and extreme weakness (fever).
Mere lack of thermoregulation would be lethal even in early infancy stage.
The changes would need to be way more thorough to be survivable, including a whole lot of physiological processes and fundamental construction of the cells. Not something that can happen through birth defect, a simple mutation or disease. Several thousand years of evolution maybe, though I don't know what factors would encourage such a change.
To compare: can you power a PC from a solar panel? Yes, with a buffer accumulator, inverter, charger circuitry etc; lots of "backend". If you just draw wires from the panel to the power socket, it won't work.
[Answer]
The normal range for human body temperature, as measured with a thermometer stuck to a person's a... rmpit, is between 36.5 and 37.5 degrees Celsius, or 97.7 o 99.5 F.
[If you go down even just one and a half degree C, or 2.7 F from the lower range, you start having serious problems:](https://en.wikipedia.org/wiki/Hypothermia)
>
> **Hypothermia** is reduced body temperature that happens when a body dissipates more heat than it absorbs. In humans, it is defined as a body core temperature below 35.0 °C (95.0 °F). Symptoms depend on the temperature. In mild hypothermia there is shivering and mental confusion. In moderate hypothermia shivering stops and confusion increases. In severe hypothermia, **there may be paradoxical undressing, in which a person removes his or her clothing**, as well as an increased risk of the heart stopping.
>
>
>
I swear I'm not making this thing about undressing up.
You see, we mammals evolved self thermorregulation millions of years ago. Being able to heat up on metabolism alone didn't just give us an immediate advantage over cold-blooded expletives; It allowed us to evolve other advantages that build on that.
Not only we produce heat, we produce and let go of it in a very fine tuned, very delicately calibrated way so as to keep it in the best setting for our enzymes and proteins. A little hotter and we cook from inside out - literally! A little colder and we are not using our energy reserves in the most efficient way - we could take days to digest an hamburger in cold places if we were cold blooded.
---
Back to the core of the question. There are a few things that can cause a person to's body temperature to drop. From the wiki I already linked:
>
> Hypothermia has two main types of causes. It classically occurs from exposure to extreme cold. It may also occur from any condition that decreases heat production or increases heat loss. Commonly this includes **alcohol intoxication but may also include low blood sugar, anorexia, and advanced age.**
>
>
>
People with hypothermia still produce some heat, they just don't produce enough of it. Hypothermia does lead to another, very common condition in which people do not produce any body heat: death.
] |
[Question]
[
I am working on developing the cultural framework for my world and I have a singular religion in mind that plays a role in both the story and more relevantly the state of the world. To provide the appropriate level of depth I am trying to define what the religion is, which begs the question: **What makes up an organized religion:**
This is difficult to differentiate, but I am not asking what all belief systems have in common. I am specifically looking at structure and organization. This is not about the beliefs or philosophies nor how people react to it but rather the Organized Religion itself.
Think of the religion as a business. When compared to other 'businesses' what do the larger, global, organized ones have in common?
**Setting:**
* Medieval Technology
* Magic
* Otherwise Earth-like
* High fantasy racial make up
* Singular creator deity, though multiple deities exist
[Answer]
First, there is one thing all major religions have in common. Complexity. Religions have multiple layers, multiple purposes, multiple actors, multiple sources, and these all interact and change over time in response to both each other, changes in society, cultural influences, individual people of influence, political events... Any image of religion is going to be partial, fragmentary, and contradictory.
For example, a major religion would probably have following elements.
**Canonical**
A religion would probably have established canonized scripture and established dogma. These would have been written at different times by different people having different opinions. Overtime the cultural, linguistic, and dogmatic differences between the writers and readers will accumulate and interpretations will vary over time and place, and almost certainly lacking serious scholarship and research be quite different from originally intended meaning.
Yet while interpretations vary, possibly to the point of religious war, having authoritative writings gives religion continuity and stability. Drawing a line between orthodoxy and heresy based on commonly accepted canon protects religion from disintegration from transient political concerns and local differences in belief.
**Organized**
Clergy needs to be trained and administered. Places of worship need to be built and maintained. Rituals must be formalized and organized. Dogma needs to be defined, interpreted, updated, and defended against heresy. Political aspects of religion must be handled.
Religions do not exist in a vacuum and religion has lots of power over the minds of people. Somebody needs to make religion compatible with the other power groups such as kings, nobles, mages, merchants, and guilds or eventually lots of people will die. Sometimes quite painfully. This happens both by reinterpretation and redefinition of dogma and by influencing other groups to accept the proper religious authority.
**Communal**
Religion is powerful agent of social identity. People identify very strongly with their religious community and will go to great lengths to conform to the values and expectations of their community. This is a major component defining the moral and ethical values of the people. If people believe their religion condemns some practice, people practising it will be stigmatised and even punished. If people believe their religion approves of something, they will approve it as well.
It is the task of the common clergy to keep the beliefs of the people within accepted dogma and prevent heresy and religious division. They often fail. What people believe generally differs from what the clergy teaches. Which differs from the current dogma. Which in turn differs from what the canonized texts actually say. Usually this will stay within acceptable limits, but this is sometimes achieved by widening the acceptable limits.
**Folk**
People will have beliefs and rituals they did not learn from clergy and that the clergy may even condemn and try to remove. This may be remnants of previous religions, superstitions, or local interpretations of the main religion. Or simply traditions. In a world with magic they may even be old pacts with local spirits. Or Old Gods.
These folk rituals and beliefs will blend with the official religion and give it a rich texture and depth that a religion dictated from above would lack. Sometimes the beliefs may become so popular the end up affecting the official dogma. After all even a great religious leader will still be affected by the beliefs and values he had as a child.
**Personal**
A truly successful religion must not only be able to affect the values and mores of communities, it must also be able to touch the hearts and minds of individual people. When a person searches for greater spiritual or ethical depth, he should be able to find it from his religion. Otherwise apostasy will spread and the social elites will become secularized.
There are rarely one size fits all solutions to personal religious needs and a major religion will usually have multitude of sects and orders to fulfil the spiritual needs of the faithful. There will also be a multitude of various schools of thought within the faith that have differing theological and ethical interpretation.
Usually personal religious beliefs will be tolerated by the religion as part of the personal relationship the faithful have with the faith. But sometimes people of deep faith cannot tolerate the mainstream religion and become heretics, apostates, or reformers. Even prophets.
---
This is one way to see the structure and organization of a religion. You should remember that while all these elements are connected and create a whole, they also evolve separately and respond to different forces. A political change might cause a fast change in the dogma and organization of the religion to match the new reality. But at the communal level the same change might take a generation or several generations. A conservative religion might fall out of touch with the personal and communal beliefs of the faithful.
Different communities might have quite different and even incompatible views of the same religion. Usually religious authorities will try to suppress such differences. Some differences will be deemed harmless and will be tolerated. Sometimes it will be more profitable to let the differences grow and then cut off the cancer with sword and flame. Sometimes this fails and schisms happen. Some schisms are temporary some will create permanent divisions.
[Answer]
If you reduce religion to a system of habits and beliefs, which is a very broad definition (a common one, but not shared by everybody), then you could ask yourself :
* why it started ? What needs does this religion fulfill ? This need can be psychological, social, etc : Hiding the fear of death behind the hope of a better existence ? Believing that your specie/group is doomed to some destiny or is simply "better" ? Creating a strong social link between members ? Being a justification for a minority to dominate the whole group ? Note that even science or rationality could be included as they are also system of belief (with some specific capabilities).
* why it continues ? This could be the same as the initial cause, but this is not systematic. A system of belief require some information sharing to remain consistent, especially in a large group. This may involve some formalism around the religion (books, practices, values, culture) and some propagating vectors (people). People involved or taking benefit from the system may become a full organization. And as organizations tend to justify and maintain their mere existence, this may turn into conflicts against alternate systems of belief (internal ones or external ones).
So it may be worth considering why and how your religion appeared and evolved. This is a story on itself but could make it really fit your setup.
Considering tour case :
**Medieval Technology**
Limited way to reach people/masses, so it is likely to have a significant amount of people ensuring the propagation of the religion, especially if just emerging, where fanatical believers will take great risks to disseminate it, compensating the somewhat reduced number of them. After some time, church people will settle down and create places to practice and maintain religion locally, also ensuring there is no challenger (or at least ensure challengers will not overthrow them). Interconnections between these local places will become the communication network of the church. Some special places, of political or religious importance will emerge and may attract significant amounts of believers, becoming also places where information/books are written and stored, bringing structure in the belief system. Things like schools and universities focused on the religion will appear in such places.
**Magic**
May alter the communication, but probably not on a large scale, except if magic is so mainstream that it allow magic-phones or the like. Magic may improve the communication in case of crisis, and occasionally help in miracles and enforcing belief. Depending of the religion values and system of belief, there may be conflicts with magic-users. If the church is old enough, is will probably be more political than idealist and deal with this contradiction. In any case, important people of the church may use the service of magic-users anyway, as they are deeply involved in politics and power games, where magic is an important asset.
**Otherwise Earth-like** / **High fantasy racial make up**
Not sure it would change many things : races may have their own religions, multiplying alternative churches. However, this would probably mean that deities are limited to one race, so religious conflicts are unlikely as they do not compete for believers.
**Singular creator deity, though multiple deities exist**
This may be an interesting source of conflicts, especially if the same church managed the whole pantheon with specific people taking care of every deity. Internal struggles are likely to happen, but will rarely take dramatic proportions, as the survival of the church itself will be a priority.
Is the religion recent or old ? Well implemented or emerging ? Aggressive or tolerant ? Involved in the physical world or purely spiritual ? Political or detached ?
Depending of this, you could see fighting-priests helping to secure roads, enlightened hermits, a rich or poor church, etc
[Answer]
* internal structure of priests: Great example is catholic church. But it is almost common that priests have several ranks in every bigger religion
* system of religious festive, alias the calendar: It can be relatively easy system of solstices and equinoxes to something quite complicated, as the Easter is (first Monday after first full moon of the spring)
* shared dogma about the god: Mohammad is the true prophet, Jesus is the son of the god... Just to give you the idea what I am talking about
* often shared enemy: From different nation to same nation, believing the same god but not having the same dogma
* system of religious rituals: How do you worship god? Is it singing song, sitting in quiet, or bowing in special manner?
* shared religious artefacts: The holy tree under which Buddha become enlightened, holy places...
* often shared dress code: In earth religion it's hats. Everyone loves wearing hat
* philosophy: What you shall do and what not. How to live "good" life
* and shared idea about afterlife: Do good warriors go to Valhalla? Is there place in afterlife for "bad people"? Wide spread religions have answer
] |
[Question]
[
There are several varieties of tails that I am interested in:
* Fully Prehensile Tails, able to manipulate objects, carry weapons/ shields (though note they may not be able to *wield* them effectively)
* Flat tails (think stuff like a beaver's, able to make a slapping attack)
* Fluffy tails (a fox's or dog's tail, or perhaps even a deer's)
* Stiff tails (think along the lines of what a lizard man or kangaroo man might have)
* Flashy or distracting tail (peacock's tail)
* Thin round tail (cats/ great cats)
* Rattling tail (rattle snake)
How could a bipedal creature use their tail in combat? Would it help much? Could such creatures design weapons for their respective tails? Or would it be an irritation that causes more problems than they're worth?
[Answer]
Point by point:
* **Fully Prehensile Tails:** if they are dextrous enough to use weapon in a fight, then they are, for all practical purposes, an extra arm - or rather, a tentacle. For this to work, the tail has to be quite long though. If it is not that dextrous, but is long enough, it can use to grapple/strangle an enemy. Might also help with Judo/Jiu-Jitsu moves, by giving extra grip to existing techniques and making new techniques possible.
* **Flat tails:** two words: houndhouse tailwhip! Seriously now, you have an advantage that humans don't have - you can attack someone who is right behind you without having to rotate your torso for a back kick. It may also be a very strong, fierce attack.
* **Fluffy tails:** if it is long enough, you can use it to distract your enemy by rubbing the tail against their face. Consider: such a tail might not do any physical harm in most situations, but you try and fight with a duster shoved against your face. The fur may also cause damage to eyes if it is hard enough.
According to east asian myths, foxes that have lived long enough will have an extra tail for each millenia they have lived. Such tails are connected to different kinds of magical or divine powers depending on the source you look up. If your world allows for magic, you might want to research about it.
A deer tail provides insignificant protection to your behind if you fall on it at best, and provides enemies with something to aim if it contrasts with the background at worst.
* **Stiff tails:** another version of the flat tail. Effectiveness will depend on the freedom of movement the tail has. You can always used for a roundhouse tailwhip too.
* **Flashy or distracting tail (peacock's tail):** you could maybe use bioluminescence - or, lacking it, some lights attached to your tail - to mesmerize or confuse your opponents. You can add a mix of taunts or awkwardness to enhance the effect. Bonus if you sing a song while doing it.
[](https://i.stack.imgur.com/3m4uR.jpg)
This is going to buy your allies a few precious seconds for them to disappear while your enemies beat you down.
* **Thin round tail (cats/great cats):** these may be a little help in keeping balance, but this depends on the percentage of the body mass they represent. This should be much more effective for a small house cat than for a humanoid cat being.
* **Rattling tail (rattle snake):** if you mean only the tip that rattles, it is no use in a fight. If you mean a snake-like tail, it works just like the prehensile tail from before.
**One last, very important piece of info to add:** while each of those tails could have different positive effects for their owners in a battle, they all have one single negative effect in common - it's one more limb for your opponents to use against you - by grabbing it, slashing it (causing you to lose blood), twisting it to immobilize you through pain etc. Your fictional creatures should be aware of this and include the necessary combat caution in whatever martial arts they develop.
**Edit:** To answer the following comment:
>
> The only thing I was hoping someone would cover but no one did is if you had stiff tail that could support your weight, could you use it to momentarily balance on and kick your opponent?
>
>
>
As kangaroos do in comics, to kick with both feet at once. You could. This could probably work on a one on one fight, such as in a kick-boxing ring. In a brawl, though, that would provide your opponents with something to give a sweeping kick to from behind. Also such a tail is good in the open, but if you have to put your back to a wall, that might be the worst tail to have.
[Answer]
Any kind of tail with any mass would operate as a counterweight; it'd make it a lot easier to keep your balance, so you'd have the freedom to commit more to your moves. You could comfortably spin faster and lean forward more.
A heavy tail - like a lizard - would be useful as a club, in the same way as an elbow. But it would be comparatively dangerous to use; to hit someone with your tail, you would have to turn your back on them. The best approach might be to spin rapidly, hitting with your tail halfway around.
A prehensile tail could function as an extra arm, if it's sufficiently dextrous. But let's suppose it isn't; I'd use it purely defensively. Put heavy armor along it, and use it to parry attacks when my arms are busy.
A tail like a peacock could be used to dodge more effectively - imagine flaring your tail behind you so that it completely obscures your body. An attacker from behind would have to make an educated guess about where your vital areas are.
Other sorts of tails would be more of a vulnerability than anything else, I think - like having long hair. You'd want to find a way to pin it to you, maybe under armor or bound to one leg.
[Answer]
A fully prehensile tail, a beaver tail, or a stiff tail might be helpful. The beaver or stiff tail could be used as a weapon, particularly in a spinning kick sort of situation. Another blunt instrument attached to your body seems useful, even if it can't grab or wield things. It could be used to trip the opponent as well, assuming the tail were stiff enough to swipe out a person's legs. A prehensile tail could possibly hold a shield to protect the person's back, or maybe hold a blade to cut the opponent as you spin.
Fluffy, thin, or rattling tails would probably be neutral. There's not much you can do with that sort of tail, other than maybe whap the other person's face and hope it stuns them. In the heat of battle, I don't think a rattle would distract your opponent, nor would a flashy peacock tail. The best strategy for those with this sort of tail would probably be to tie the tail to one leg, keeping it out of the way. It wouldn't hamper them too much, and it would be unlikely to get cut off or stomped on.
A peacock tail would be bad. I don't know about a longer, bright tail, but I'm picturing a full-on peacock tail, and it isn't good. The feathers, or possibly big fur tufts, would get in the way and would not help at all. Maybe as camouflage the tail could help, but in battle it would just get in the way, and there's really no good way to tie down a big, fat peacock tail. You might be able to gather all the feathers together and band them together into a long, stiff bundle, which could maybe be used as a stiff tail, but it would probably be uncomfortable and clumsy. It would also take extensive preparation as you'd probably need someone to help you.
] |
[Question]
[
## The Setting
Imagine a generation ship of 10-20 generations (200-400 year trip). The generation ship is divided into living crew and frozen eggs.
Upon reaching the destination & for genetic diversity, the crew must begin gestating these eggs and producing colonists.
Meanwhile the crew will continue to produce some of their own children.
## The Conflict
People tend to treat their biological children better than adopted children on this ship (not sure if that also applies to *in vitro* fertilization [IVF]).
From the crew's perspective they and their ancestors did all the "hard work". They and their society successfully completed this multigeneration voyage and risked extinction as they hacked a life out of their new world.
They may wish to ensure their successful society runs things at the new colony.
Since colonists were raised from birth at the colony, other than possible education, there's no real way for them to know that their society could run along any different lines.
## The Question
Would this encourage a caste system (ala [Larry Niven's **A Gift from Earth**](https://en.wikipedia.org/wiki/A_Gift_from_Earth)) in which the crew set themselves up as the "nobility" of the new colony?
Bonus points for answering the following:
1. Would/could such a stratification be beneficial?
2. How long might such a situation persist?
[Answer]
Would such a setup encourage castes ?
Depending on the crew culture of origin... Maybe.
Westerner culture always had a semi-fluid system where the best and brightest could climb the social ladder, at least through several generations.
Easterner cultures were more rigid.
Then you have the will, knowledge, and loyalty of the crew to a distant mission and origin. The more ambitious, with knowledge of caste system could implement one. People who would want the best for their children might create a kind of meritocracy where their child get a huge head start, but where the best of the in-vitro colonists (the "tubbies") could still rise
When first writing this, I overlooked an important point : even with IFV, the colonists will be the sons and daughter of the crew, unless they have a mean of breeding the kids without woman bearing them.
If they have this technology, then they can engineer any kind of society they want and the question is very valid.
If they don't have this technology, then many women of age will have to turn into baby-making factory. At this point, either you already have a caste of breaderess on board the ship and you can go for it, or you need to have modified your culture so that women don't care for the well being of IFV children or, finally, you can have modified the society so that most child are raised collectively with a few being raised by families.
**The most likely case would be that, over generations, the people (particularly the women) of the ship have become disgusted with the idea of mandatory IFV pregnancy.**
This would justify the difference of treatment in the children with "naturals" being seeing as for more lovable than "tubbies". And then you have your two-caste society with loved children cared for, and unloved small sized slaves whose care is considered a punishment.
Would/could such a stratification be beneficial?
* The meritocracy ensure that the colony will get people actively try
to better themselves and the settlement.
* The caste system are quite stable, just or not. Stability is an important success factor for a colony far from it's home.
How long might such a situation persist?
An unbalanced meritocracy is doomed over time as some tubbies will rebel. Give it a few generations. Maybe a century. This one has more chance to evolve instead of degenerating into a civil war.
A caste system is prone to stagnation and could last until it collapsed. As expansion is critical to a budging colony, I'd give them maybe two centuries (8-10 generations) before things go sufficiently sour to get to a radical, violent change. This one has more risks to need a civil war before it can change.
[Answer]
It **could** have this result but it doesn't necessarily **would** have this result. You can justify it either way, depending on your story.
* Say the colony is run along capitalist lines, but every adult has the right to claim a large plot of public land for development. As it happens, the adults at the time of the landing all claimed plots next to each other, in a good place for a capital city (good climate, good transportation, ...). The first hospital, the first university are built there. That makes the initial crew *richer* than the rest. What is worth more -- a square mile in Manhattan or a square mile in Montana? This could last a long time if the wealth of rich people is self-reinforcing.
* Or the colony does not make the transition away from the shipboard command structure. The captain remains in command until an unspecified time in the future when "the colony is mature enough." Even if promotion to the officer corps is strictly on merit, those raised by officer families would learn how an officer and gentlemen is expected to behave, and hence pass the examination unless they're really stupid. Meanwhile, colonist-born children would have to be really good to overcome that lack of examples.
* Or the crew has suffered a high degree of genetic damage due to exposure to radiation and a bit of inbreeding, while the colonists are all carefully selected for health. The descendants of the crew become an underclass.
* Or the crew find that their skills and work culture which where fine on a ship are simply not applicable to the planet. They and the children they raise become an underclass, not a nobility, while they struggle to fit in.
[Answer]
I'd go with **yes**.
Generation ships are by their nature designed to be remain within the same operational parameters for the entire mission with some safety margin added. So effective generation system should be as static as possible for the designer to achieve.
There are workarounds. I recently asked about a bubble-ring model of generation ship that would get around this by having enough redundancy that some social experimentation at a ring level would be practical. But that requires on entirely different model for how you are using the generation ships so it doesn't apply to your question.
An optimally static society would have no real need for social mobility. People would be tested for aptitude and then trained for tasks that suit them best.
Since the crew would be chosen for high ability at their tasks and high ability needs to be available for the following generations as well, it is reasonable to assume the original crew was chosen for high natural aptitude at their specific tasks. The eggs would presumably also be as much as possible be chosen for natural aptitude since that is all that can be done on Earth.
Since the crew was chosen for aptitude at specialized tasks and children socially take after their parents and the ship would be too static, unless something goes catastrophically wrong, to need social mobility it is reasonable to think the crew positions would be nearly hereditary. Specifically there would be division between leadership, management and technical positions. Something resembling the officers, NCOs, and the crew division of military systems. If it works and all that.
Once landfall is made the need for static society would not really change. You'd simply have vastly increased need for management and technical positions. Thus leadership positions would remain in the hands of the ship officers and the eggs would have been chosen for aptitude at the management and technical positions and be used to rapidly increase those classes of people. This would create a need to rapidly educate and train large numbers of people which would continue the ship tradition of training people to specific positions based on aptitude.
So the castes would probably be largely hereditary initially with some limited mobility to account for the fact that even with genetics and upbringing people are probably not that predetermined. But the division would not be between the crew and colonists rather it would be a continuation of the rigid social system on the ship into which the new born would be raised into.
Two notes though:
First, such a caste system would actually be fairly good for the needs of the initial colonization. Democracy and freedom are required for efficiently deciding what to do. When you have an abundance of things to do with limited resources and probably a fairly specific plans on how to do them, a society with strict hierarchy works just fine. So the caste system might actually be an advantage, not something to avoid.
Second, as the demands of the society change, the social structure will automatically evolve to match the needs. There will be friction, but generally you can assume that once the caste system is not useful, ie the amount of resources grows so there is some need to think about the direction of the colony not just survival, the society will move on. And unlike aristocrats of our own world, the crew would have access to information telling them about the inevitability of social evolution. They'd probably even have plans drawn by some very smart people back on Earth about how to handle the transitions to more liberal society.
[Answer]
While a neo feudal system is possible under this construct, several other variations may also arise:
Plutocracy/oligarchy. The crew, having access to all the ships systems and resources, can control virtually every aspect of the new colonists lives. This can be in the form of soft control (i.e. filtering information) rather than hard repressive control. The Crew and eventually the descendants of the crew will be much like "old money" and be able to subtly guide development in ways which allow them to retain control.
Hydraulic Empire. Since the crew controls all aspects of the ship's life support systems, they have 100% control over the lives of everyone aboard. All acts and decisions have to flow through them, and a hereditary caste of "priests" and God Emperors may arise to control the life support system(s) of the ship and any subsequent colonies in the system. I include artificial colonies built in asteroids and on airless moons, and terraforming projects which require the special skills of the "priesthood" to manage.
The downside of this is the "three generation rule", (from shirtsleeves to shirtsleeves in three generations), which suggests the various aristocrats/plutocrats or hydraulic empire priesthoods will become corrupt and ineffectual in the third generation after they are established. Most systems on Earth avoid that particular fate because they are very large and usually not tightly bounded (there are always ways to ensure some forms of social mobility and allow truly talented people into the upper echelons), but an interstellar colony is a closed system and has too few people in the initial generations to ensure that there will be enough social mobility to keep the system open and viable, regardless of the social and political systems developed when the ship arrived.
[Answer]
I'd go with yes.
I feel this would also start in the ship portion of the trip as well. Crew members such as the Captain and those who perform essential duties will see themselves as more important than the others. The ship's ecosystem works in favor of these essential crew and this favoritism would be the cause for a split between crew.
[Ascension](https://en.wikipedia.org/wiki/Ascension_(miniseries)) gives a good representation of what might happen on a generational ship and answers "yes" to your primary question. The whole series was on Netflix at one point.
] |
[Question]
[
*This is inspired by our third fortnightly challenge, but a question I've had for a while anyways.*
Bones are seriously complex structures. Far more complicated than most structural materials humans use. They are porous, with compact and spongy sections which repair themselves. Bones mostly rely on [Hydroxylapatite](http://en.wikipedia.org/wiki/Hydroxylapatite) for their structural strength, but also on [collagen](http://en.wikipedia.org/wiki/Bone_tissue#Structure) to make them more shatter resistant. This results in a good material for making bodies. I would like to do better.
I would like to know how a creature could, assuming earth-like biology and resources, have better bones. Specifically, how can you improve the [hardness](http://en.wikipedia.org/wiki/Mohs_scale_of_mineral_hardness), [compressive strength](http://en.wikipedia.org/wiki/Compressive_strength), and [shearing stress](http://en.wikipedia.org/wiki/Shear_stress) of bone without dramatically increasing the weight? [This](http://en.wikipedia.org/wiki/Bone#Mechanical) is a reference showing some of the numbers to beat, but I'll list them here for simplicity:
* Compressive Strength: 170 MPa
* Hardness of Hydroxylapatite: 5 (Mohs Scale)
* Shear Stress: 51.6 MPa
**Edit**: If you feel that a creature could use multiple or different materials for their skeleton (as bone serves many different purposes), please state why in your answer.
[Answer]
You could do this by simply substituting calcium for something else. Maybe carbon as @IsaacKotlicky suggested, as it's pretty light and strong.
For a little more weight you could weave iron into the bone structure. We already use iron in our blood, and blood is manufactured in the bone marrow, so it's not that great of a leap to suggest that in this creature iron could also be stored in the bones until it's needed for blood manufacture as a reservoir.
This would give you a creature that would have really strong bones, and be able to survive blood loss better.
**EDIT:**
Ok, some numbers... I'm not any kind of ologist, so these are mostly rough estimates.
Calcium is a metal, so we'll assume that this creature uses iron instead of calcium for half it's bone mass in a calcium/iron matrix.
A human male skeleton weights around 13607g (30lb). If you replaced half the weight with iron instead of calcium, it would weigh roughly 16283g (35lb).
Calcium:
Shear modulus: 7.4 GPa
Mohs hardness: 1.75
Brinell hardness 170-416 MPa
Iron:
Shear modulus: 82 GPa
Mohs hardness: 4
Brinell hardness: 200-1180 MPa
I can't begin to guess what the resulting iron/calcium composite would be like in regards to strength (especially because the structure of bone is already so much stronger than the use of calcium as a building material should make it), but considering how much stronger iron is to calcium I believe it's safe to assume that the resulting structure would be better in almost every way, with only a slight increase in weight.
Source:
<http://www.materialstoday.com/mechanical-properties/news/why-are-your-bones-not-made-of-steel/>
[Answer]
I'm first going to reply to your question as it is. Then I'll elaborate and try to answer the question in a more general sense.
**Reply to question as is**
If all you care about is hardness, compressive strength and shear strength, you could take something like diamond (or a similar material that is easier to produce biologically) Diamond (see references [1](http://en.wikipedia.org/wiki/Material_properties_of_diamond "1"),[2](http://en.wikipedia.org/wiki/Material_properties_of_diamond),[3](http://pubs.acs.org/doi/abs/10.1021/jp102037j) and [4](http://www.ncbi.nlm.nih.gov/pubmed/11102147)):
Moh's hardness: 10
Tensile strength: 60 GPa (perfect crystals could be up to 225 GPa)
Shear strength: 95 GPa
Compressive strength 223 - 470 GPa
So far we're looking at twice as hard and approx 1000 times as strong.
Enter toughness at: 2.0 MPa m1/2
Compared to bone toughness (see reference [5](http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CB4QFjAA&url=http%3A%2F%2Fwww2.lbl.gov%2Fritchie%2FLibrary%2FPDF%2Fbone_tough_bone_08.pdf&ei=OYEAVcLJIaLQ7AbFtoGoBQ&usg=AFQjCNGNd4GEiV2Y24csVoImlE4gXjP3ew&sig2=hMjVPz0XBlNj9YlIuAl8ww&bvm=bv.87611401,d.ZGU&cad=rja)) is more like 3.6 MPa m1/2
So diamond bones would actually break faster. They would potentially allow you to exert significantly greater forces if you did it slowly enough and if the rest of your body could handle it.
**More general response**
First we'd need to look at what we use bones for and what properties we'd need for that.
Bones are used for attaching muscles and taking the stresses induced by using muscles. In general these forces don't happen to sudden, so we can use tensile strength and shear strength to see how much the bones can take. Try to go for the yield values in both cases as you want the stresses to stay in the elastic range (would not be good to have your bones permanently deform as you use them). Somewhat less important is the amount of deformation that happens in the bone. You want this to be low enough to not bother you in movement and also low to reduce the energy expense to bend the bone so most of the energy expended goes to the intended movement (energy for bending is stress times the amount of deformation). So that comes down to having a high Young's modulus. So we're looking at mainly high strength and to some extent high stiffness.
Bones are also used to keep the shape of your body. This means they should deform little under various stresses (elastically). This is again the stiffness.
Bones protect you from damage. Bones should deal with life (falling, impacts, ...). Both of these require high toughness. You can look at total toughness (energy absorbtion up till breaking) or to elastic toughness (energy absorbtion up to permanent deformation).
It would also be less than ideal if your bones easily deform permanently (bending bones back in shape seems harder than mending broken bones). This implies having the yield strength be very close to the actual strength (so breaking occurs instead of bending). I guess this one is somewhat more debatable.
Bones have to able to grow organically (so slowly accumulate, not just appear finished at once).
Bones have to live in your body. So they should corrode minimally in the conditions present in your body and have little negative impact.
So now we've set the scene:
High enough (yield) strength to take the load of muscle usage, weight of body.
High enough stiffness to keep your shape and optimal energy usage.
High enough toughness to deal with sudden impacts such as falling, getting hit, ...
On top of those requirements we'd also have to look at what's biologically feasible.
Metals would be a nice start (I'm thinking hardened steel, which is both stronger and tougher than bone, but plastic deformations are minimal). Metals however have the disadvantage of being hard to make into the required composition by means of biological process. They may also corrode and be poisonous. If we could purify them somehow and we could coat them to keep them separate from the body, it might be an option. In any case, other answers have treated this sufficiently, so I don't feel the need to add much more.
Otherwise I'm thinking about all kinds of biological polymers. Some of the strongest and toughest materials known to man are biological polymers. Spider silk for example has a tensile strength up to 2000MPa and is very tough. Unfortunately it deforms rather easily as it has a low stiffness. So having bones of something like spider silk would be like having very strong rubber bones. Stiffening it up with extra crosslinks between protein chains might help make it stiffer (though also less tough).
In general, I'd look at reinforced polymers. Life is good at making polymers and reinforced polymers (example: wood are strong fibers in a polymer matrix). So you'd just need to find the correct fiber and the correct polymer matrix to go around it. Other examples of reinforced structures are carbon fiber with a glue matrix (high strength, low weight bike frames). The entire structure can be stiffened (at the cost of toughness) by adding hard particles (like calcium salts). Note that if you increase your stiffness, you usually lower your toughness (unless you also manage to increase your total strength or your maximum deformation).
A lot also depends on the exact structure of your material (molecular buildup, orientation, crosslinks, crystal structure, ...).
You could try limpet teeth (See reference [6](http://rsif.royalsocietypublishing.org/content/12/105/20141326)) which have a tensile strength of 3 - 6.5 GPa, if necessary combined with some kind of longer fiber to keep it strong in larger sizes.
You can probably get away with just attributing it to a change in micro-structure (even without added elements or replacements), though that might not be as cool as fancy new molecules :-).
[Answer]
Even humans have a way for strengthening bones. Take a look at the Wolff's law. Bone in a healthy person or animal will adapt to the loads under which it is placed. Martial arts takes advantage of this.
<http://en.wikipedia.org/wiki/Wolff%27s_law>
[Answer]
Well, carbon nanotubes are obviously the stuff of the future, but I don't really know much about those, so I'll be leaving that up to @IsaacKotlicky.
Instead, I'm going to go down a different route, and see if we could integrate steel into your creatures' bones. Now, I'll be talking about endoskeletal bones (ie. the ones on the inside that primarily support your posture and locomotion); there are quite different considerations on exoskeletal bones (eg. turtle shell) and similar not-quite-bone structures (teeth), which I'll touch on at the end.
## Materials
The word "steel" actually refers to a rather wide variety of (principally) carbon-iron alloys, with an equally wide variety of properties. I wasn't able to find figures for shear stress of steel (presumably because it depends heavily on the geometry), but the [yield point](http://en.wikipedia.org/wiki/Yield_(engineering)) (eg. the stress beyond which the material permanently bends, or breaks if it's hard/brittle) seems to be about 10x higher compared to bone for a decent bar of steel you can make into something in your forge.
This is a good thing, because flexibility (expressed as a high yield point) will be a principal requirement for an endoskeletal bone - you want it to be able to take as much stress as possible while flexing, so that (in trauma situations) it absorbs as much of the schock as possible without getting irreversibly bent or broken.
Note that this is the kind of flexibility that we generally talk about in structural engineering - a good bone will be flexible much like a good sword, rather than limp like rubber.
## Organic manufacture of steel
Obviously, we won't be able to melt down iron (or iron ore) inside your typical organism. The good news is, we might not have to.
The two chemical processes you need to master is first getting the iron in the first place, and then creating steel and making it into something useful.
Your body can already get iron from food - it's what your red blood cells are made of, among other things - but for volume production, you might want to look for other sources. Iron is one of the most abundant elements, mostly in form of various oxides, so you could concievably have your creatures eat something that contains hematite powder. Extracting atomic iron from hematite is a question of reduction - in industrial practice this is done in a furnace using coke as the reducing agent, but I'm pretty sure any number of organically-available reagents would do the trick.
So now that you have iron, what do you do next? Well, iron (and all other metals, really), have the interesting property that if you simply put together two pieces of it in a favourable chemical environment (such as vacuum, but anything that will prevent the surface from oxidizing will do the trick), they will get [cold-welded](http://en.wikipedia.org/wiki/Cold_welding). This way, you could build up small particles of iron into larger structures - interspersing them with some cementite to up the carbon content - until you get steel.
## Altering the properties
The properties of steel are largely dependent on the size and configuration of the monocrystals that make it up (besides the exact chemical composition, of course). In general, larger crystals make harder, more brittle steel, while smaller ones make it softer and more flexible; you want to strike a balance here.
The human body, among others, seems to be capable of growing crystalic substances; that's how it makes enamel out of hydroxylapatite, so I'm going to run with that and assume that we can design an organic process that will grow microcrystals of different sizes.
## Building bones
By depositing and welding them together, you could concievably construct matrices of desireable properties, much like we have inside our bones, but made of steel. If you add cells with the ability to selectively oxidize some parts of that matrix away, you now have osteoblasts and osteoplasts and your steel bones have the same self-repair and adaptation capability as normal bones do.
Exactly what the properties of such a bone would be is anyone's guess, and i depends heavily on the geometry of the bone mesh and the applied forces. We can take the factor of 10 as the ideal case, but other things to consider are that clever geometry can actually make a steel item stronger than its weight/volume would suggest (that's how I-beams work, basically), plus if you can play around with carbon content and crystal sizes, you can mix it up to either mimic [pattern welding](http://en.wikipedia.org/wiki/Pattern_welding), or tempering/quenching without the (usually) necessary heat.
## Final notes
I promised to mention something about teeth here, so here goes: where flexibility is needed and you are not expecting to have the object directly scratched or chipped by something really hard, you don't really care about high hardness. Quite the contrary, hardness usually corellates with brittleness, which in turn decreases flexibility, so it's something you might want to avoid.
In some cases however, it might be beneficial. Teeth might be one such case (they are not properly bone, but the enamel - the hard outer part - is also based mainly on hydroxylapatite), where in striking the balance between hardness and brittleness, you might want to go a bit higher on the hardness scale (although not hign anough that you can break your own teeth biting down hard).
Depending on how it's made, steel runs the mohs scale from 4 all the way up to 8. Otherwise, there is plenty of minerals harder than hydroxylapatite that you might grow crystals of using a similar process, although it should be noted that unlike bone, a broken tooth can not be repaired (there are no osteoplasts or osteoblasts that would do that inside a tooth). You could, of course, go the way of the shark and just grow a new one, if you're so inclined.
Finally, note that stronger bones alone do not mean you can put your creature through unlimited abuse - heavy wear or significant shock might damage joints, and you also need good muscle to support the skeleton and help absorb the forces. Also, I hear that bones are supposed to break in order to absorb shock that would cause greater harm to other body parts - making them unbreakable might cause other problems later on.
Well, this was a fun mental excercise; I hope I didn't write anything outrageously wrong:)
[Answer]
When we want to strengthen a material, like concrete, putting in a bit of metallic structure into the mix helps a lot...as in reinforced concrete.
An animal could in theory, do this to its own bones..depositing a metal into the bone structure in fibers, producing an internal web of stronger material. Think of a fiberglass like result, but with metal.
[Answer]
Limpet teeth are the strongest biological material to date and are made of goethite, an iron compound. A composite of limpet teeth and silk hydrogel would be the strongest and toughest composite I can think of while still being 100% possible according to known biology.
The goethite for hardness, the silk for tension and the oil hydrogel for the spongy material.
You can have the skeleton be around 20% heavier at max depending on density or have it weigh less for equal strength to normal bones.
[Answer]
One interesting thing I find about humans is the common perception that we're weak in the animal kingdom - that as we evolved for intelligence, we lost muscle (and presumably) bone strength. And technically this is true - you can compare us to Chimpanzees, which are roughly [twice as strong](http://www.slate.com/articles/health_and_science/science/2009/02/how_strong_is_a_chimpanzee.html) as humans pound for pound.
But the fact is that there's no free lunch in evolution or body design. Stronger muscles and bones take more energy and take longer to heal. Humans are "weak" because *weak is efficient*, and with technology we can prioritize efficiency over strength and still come out ahead, enhancing our overall ability to survive. And human bones can break, but we can heal that broken bone. Think about taking a fall - if your bone doesn't break, but your muscles aren't any stronger, your bone could literally rip itself off of the muscle structure. That could turn a 6-week fracture into an amputation or death scenario.
Now, this isn't to say you can't strengthen bones in your creatures - lots of excellent answers here, from carbon nanotubes to titanium or steel. But you shouldn't strengthen them in *isolation*. A stronger skeleton necessitates a stronger and more robust muscular system, higher energy requirements, and might result in a tougher time recovering from injuries. You might also want to change the very structure of your animal so that it can use those super strong bones to protect the rest of the body - for example, maybe the animal can "lock" the skeleton in place, so that most of the shock of a fall or impact is taken by the skeleton, therefore protecting the comparatively weaker muscles and ligaments.
] |
[Question]
[
Would it be possible to raise a piece of land (say the size of Texas or France) from the bottom of an ocean (say, the middle of the South Pacific)? More specifically, would it be possible (given the wealth & technical means), to
1. "cookie cut" cut a circular slice at the bottom of the ocean, say
between the Easter Islands and the Equator
2. cut horizontally under the "cookie"
3. drill one or several wells to the core of the Earth
4. let the pressure from the molten core to push up the cookie until
it breaches the surface
5. collapse the wells with a few nukes buried close to the wells
and various depths
Would something like that be possible, or would that be doomed to fail?
[Answer]
The plates float and oceans are deeper than continents because the oceanic plates are heavier. There is not enough pressure to raise the cut off piece of the plate to the surface, it is too heavy. Any pressure would just come out at the edges that had been cut.
But there is a way to create new countries, kind of. Nuclear bombs can be made directional (the US even developed some for use as EMP weapons), and AFAIK there is no real upper limit to the size of thermonuclear bomb. So you could make a bomb that can cut a hole down to sufficient amount of magma. And if you made enough of the bombs you could get enough of the lava to get your small country. So it is just a matter of money for a nuclear power.
*Ph'nglui mglw'nafh Cthulhu R'lyeh wgah'nagl fhtagn*
There are just some minor issues, though. First, exploding large amount of nuclear devices of unprecedented power would not make people happy with you. Thermonuclear bombs could be made relatively clean, but there is no way to get rid of the shockwaves, electromagnetic pulses, tsunamis... So you'd become pretty unpopular very fast.
Not that it really matters because as soon as the magma started flowing all that would be forgotten. Feel free to read the Wikipedia article on [Large Igneous Province](http://en.wikipedia.org/wiki/Large_igneous_province) as that is essentially what you are trying to create. Pay attention to the part there they list all the past extinction events that have been linked with fast creation of large amounts of land with volcanism. Including the one that is also called "the great dying" because it made the majority of everything go extinct. Of course every single hole created would also qualify as a massive explosive eruption.
So this would only make sense if you do not care about every single person on the planet dying, large number of species going extinct, and triggering a new ice age. Probably a short one, but still. Seriously the nuclear winter people used to worry about would have been child's play. And while you can probably come up with a way to trigger the eruptions that does not involve ridiculous number of nuclear explosions, you can't really avoid the consequences of enough magma to raise a small country erupting when your goal is to create a small country from erupting magma.
[Answer]
That's pretty much what Hawaiʻi is. You could locate a mantle plume in the area you want, and thin out or weaken the crust over it. Perhaps just punching a hole is enough in the story, with the plume needed in natural cases to punch through the crust, and artifial means are used to speed the outflow.
[Answer]
Or much simpler, you can use [biorock](http://en.wikipedia.org/wiki/Biorock) to grow artificial island in shallow reef areas like [Saya de Malha Bank](http://en.wikipedia.org/wiki/Saya_de_Malha_Bank) - area of 40,808 km2 (15,756 sq mi).
[Answer]
Extending the answer by [Peter Masiar](https://worldbuilding.stackexchange.com/a/6478/353):
Biorock is not too slow. Facing tsunamis and magma [E.L.E.](http://en.wikipedia.org/wiki/Extinction_event) means you are going too fast.
Use [biorock](http://en.wikipedia.org/wiki/Biorock) and the reverse of this [japanese demolition technique](https://www.youtube.com/watch?v=8_4G_8gEjng):
Set up the foundation:
* Build underwater a plain mesh of steel girders in the general shape of your desired country. Set a solid foundation below the girders, on the bedrock. This mesh will have to support your entire country's weight.
* Grow enough biorock around the girders. Since biorock has the strength of concrete, you are basically making one huge concrete slab underwater.
Prepare your landscape:
* Make a second mesh of girders, in the general shape of the landscape of your country. Hills, valleys, lakes, riverbeds. They will have to get some dilaltation gaps, since it is going to be overwater and subject to weather.
* Put your landscape mesh on hidraulic jacks. Grow biorock over the mesh but not on the jacks.
* Also plan for the underground water veins, and the freshwater cycle. You want freshwater on your country, do you?
I command you to rise from your grave and rescue my daughter... (oh, wait, strike the grave and daughter part).
1. Raise the landscape using the jacks. Bind more girders below the landscape slab, and grow more biorock. Remove the jacks and place them below this layer.
2. Repeat #1 above until you get to the desired height.
3. Once the landscape slab clears the ocean level, seal the biorock so it does not degrade.
Now we need earth.
* At this point, you have a huge concrete structure sticking out of the ocean.
* add gravel, earth, dirt over your landscape slab. You will need to add several meters of gravel and earth so you can grow trees and have the rainwater infiltrate the soil.
* Grow trees and vegetation in order to lock the earth in place. You will also need to wait a couple years for the loose soil to settle before moving in. Grow a forest, and think of all the hardwood you can cut once you move in. It could be [Paul Bunyan's](http://en.wikipedia.org/wiki/Paul_Bunyan) wet dream come true. Also to recover some of the building costs.
* Now you are ready to start building your city.
Added bonus: seal the meshes, pump out all the water, and now you have an underground maze to boot.
Added bonus #2: since you are already growing biorock, you get to do your coral reef for almost no added cost. Time to put Australia to shame.
It would take some decades to build it, and it depends on the ocean depth and desired height, but it is doable with current technology.
] |
[Question]
[
This is a science fiction intelligent alien biology question.
I'm imagining a race of large (around 2m in height) insect-like species on a distant planet who discovered astronomy VERY late in their technological advancement, in fact only after meeting aliens from another planet. This was because of the combination of several factors such as their compound eyes, the atmospheric composition of their planet, and their species biologically and culturally being more interested in what's below than above them in general. At the time of them first meeting aliens and discovering the existence of outer space, their technological level is slightly more advanced than present day humans of 21st century, with the exception of those fields dependent on the knowledge of astronomy and some fields being significantly more advanced, like biology.
Now, I'm entertaining an idea that upon being granted access to the knowledge in astronomy and astrophysics built up by the aliens, a few members of their race showed astonishing proficiency in those fields, rapidly becoming major contributors to the interstellar astronomy community, and that it's because of a particular biological trait shared by those individuals. What could this trait be?
A few points to consider:
1. The very first astronomers of this race worked almost entirely on existing data on sheets and made significant scientific achievements from just that.
2. Astronomy and astrophysics are complex fields of science with a lot of things going on, such as computation of orbit, understanding the composition of a planet's atmosphere, making sense of data and theorizing on what could explain it, etc. And then there are activities such as making observations, explaining existing data, discovering new physical laws and equations, etc. Our insectoids don't have to excel at everything astronomy, they just have to be good at a particular task that's very useful for astronomy. Bonus point if the task is helpful for explaining anomalous data.
3. The trait in question doesn't have to be related to their vaguely insect-like biology, though traits that actual Earth-insects have and would be helpful for this species' astronomical studies would be very nce. But a purely intellectual trait wouldn't be interesting unless there's good reason to make it unique to this species. Also note that this trait doesn't have to be shared by all individuals.
4. The interstellar community obviously have FTL, allowing them to directly visit some celestial bodies they want to observe.
5. One idea I'm considering is that they have a hive mind and can essentially perform grid computing. But for now let's assume they're all their own individuals.
[Answer]
# Introduction
Firstly, think of autistic savants. There is no noticeable physical difference there, yet these people are capable of incredible (hyper-specialised) feats. Quoting Kim Peek's Wikipedia:
>
> "He could speed through a book in about an hour and remember almost everything he had read, memorizing vast amounts of information in subjects ranging from history and literature, geography and numbers to sports, music and dates. Peek read by scanning the left page with his left eye, then the right page with his right eye. According to an article in The Times newspaper, he could accurately recall the contents of at least 12,000 books."
>
>
>
Consider also someone who has absolute pitch? There is no physical advantage that they have, however, their brain allows them precisely identify the world of sound around them.
Now consider also synaesthesiacs, who can "taste colours" or "hear smells" etc. Again,there seems to be no physiological difference, yet they are able to experience the world in profoundly different ways, having a more **specific** experience of certain things (making each object/experience more easily distinguishable).
Insects have far more senses than we do really. They can communicate effectively via pheromones in a way incomprehensible to us and they can see in parts of the EM spectrum we can only grasp with computers.
# Concept
The fact that it took so long for this race to develop in the field of Astronomy suggests that they are perhaps unable to naturally look at the Stars, perhaps they can only see in a very narrow part of the EM? Perhaps their planet has a very thick atmosphere? Whatever the reason, I think that a specific physical advantage is less likely.
However, there is no reason to say that a small group of them might not have developed variants on these human abilities listed above. One that can memorise everything it reads/learns almost instantly and never forget it? One that can not only see a spectrum of light, but feels it like it's a pheromone? These might have have been beneficial traits for previous roles, such as acting like a cultural memory bank or working in farming to only get the very best food.
Now, think about a very small group who have all these abilities. Someone that might be able to look through a telescope and remember ***exactly*** what they just saw. Who could then convert that into a specific pheromone, etc, to explain it to everyone else. They could judge similar experiences (sights, sounds, smells) with each other allowing them to rapidly develop their field - quickly creating star categories, etc.
[](https://i.stack.imgur.com/2tpD6.png)
[Answer]
At least on Earth, astronomical instruments are extremely precise and sensitive compared to the innate biological abilities of an astronomer! Sure, I can look up at the sky and see that Betelgeuse is a bit dimmer than normal, but I can only guesstimate how drastic the fainting is. With a decent telescope, on the other hand, I can have measurements of its magnitude at the same wavelengths to a decimal place or two without too much effort. *Particularly* in a galactic society with faster-than-light travel, it seems that any observational task the insects could do well, machines could quickly be built to do better. Given how data-driven astronomy is, and how imprecise our senses are, it seems hard for this species to outdo telescopes and computers.
There's one big exception to the rule: initial back-of-the-envelope observations. Sometimes you don't necessarily need to know quantitative data about an astronomical object, just qualitative data. For instance, if I'm monitoring a star for a possible exoplanet transit, I might care only about whether or not there's a transit in a given dataset - other people can do detailed follow-up observations to determine the parameters of the exoplanet. So the one way these insects could contribute to observational astronomy would be if they had an ability to perform a variety of quick-and-dirty measurements.
Using that as a sort of recipe, here are some possibilities:
* [Magnetoreception](https://en.wikipedia.org/wiki/Magnetoreception), the ability to sense a magnetic field. This could be useful for mapping magnetic fields throughout the galaxy (though the galactic magnetic field is quite weak).
* The ability to restrict vision to a particular band in the electromagnetic spectrum, as well as versatility in the range of wavelengths visible to the naked eye. It could be handy to be able to compare how an object looks at different wavelengths.
* The ability to determine a sample's composition. [Freedomjail suggested mass spectrometers](https://worldbuilding.stackexchange.com/a/169778/627); I think the ability to view individual spectral lines when looking at a source would be even more useful. This would enable them to determine a star's spectral type just by looking at it.
All of these are only the starting points for astronomical observations. All they do is provide a little push towards obtaining more detailed data. But then again, sometimes all science needs is a little push in the right directions.
[Answer]
**As juveniles, these insects form far-ranging nocturnal swarms. Some adults remember how.**
[](https://i.stack.imgur.com/lPhO3.jpg)
<https://pestcemetery.com/subterranean-termites/>
Your termite-like insects dwell in a subterranean hive or nest. Periodically, some juveniles with wings are born. These young pioneers group together and make a far ranging nocturnal flight of migration, navigating by the stars.
Once they arrive at a new site, they eat their wings. They begin the work of excavating their new home. Most lose themselves in the earth and their new life, and forget what it was to fly under the stars. But every now and then there is an individual who secretly leaves the nest on a clear night, and looks up, and remembers.
These few become the astronomers and later the starfarers of your society. There may be more of them than they initially realize.
[Answer]
Their antennae can "taste" an atmosphere's composition, similarly to a pollution filter. They would also, as possible, have a means of using that for survival in their "ancient" days, such as being on a volcanic planet with dense clouds of ash giving them ability enough to measure pollution, air composition, and any other factors that they might have been dependent on the survival of on your planet for them.
Because you state that they only learned about astronomy from high-tech interstellar civilizations, they would have probably not have had a way to observe the night sky; in any part. This would fit very well into a volcanic planet, because the surface would be generally avoided due to the high amounts of atmospheric pollutant, leading to a mostly underground civilization.
Perhaps instead of needing complex scans on their planets, to determine the content of each planet, it would be easier to just take it to to the ant-people, whose specialized people could give them a quick, accurate, and precise reading.
[Answer]
### Difference in Thought Patterns
Consider this species. They have very limited knowledge of the grand cosmic-scaled physics that we do. Counter to that, they have an advanced understanding of things on smaller scales. Their models and theories are based on micro-scale observations and experiments on models of their size.
This leads to the first premise that they will think differently when confronted with the same problems. Just a difference in perspective might be enough to crack problems that have stumped us for years. The only reason that they have not done it yet is because they lacked our astrophysical data which both pointed out and explained holes in their theories.
Given that they are looking inward towards their planet, then they might have a better understanding of matter -- both from a chemistry and a physics perspective. They can possess an advantage relating to astronomical matter because they have a deeper understanding of it. Spectral lines that we can't explain, unknown isotopes of elements, and other things like this are right up their alley.
While this is a mental trait, it is born as a result of them abandoning astronomy until now and of their nature applied to a different pursuit.
### Social Work Structure
Another possibility is that these people are at least partially connected with those around them due to a more eusocial manner of living. Not to the point of a full-on hive mind, but they are used to working together and can synergize with each other better than, say, two humans working together. This can manifest in two great minds bouncing ideas off of one another until an equations sticks, or it can be a small group that know their individual places and do their best for the team instead of themselves.
While this aspect does not necessarily lend itself to being great at this field in particular, it does allow them to thrive when put into a collaborative situation where this behaviour can be nurtured and encouraged.
### Physical Differences
As has been brought up, these insectoids will almost certainly have different eyes than others in this universe. If they spend most of their lives underground, then expect them to be well-adjusted to the darkness, meaning that the relative void of space will be brighter for them. Alongside that, they will probably not have the same visible light range that we do. Depending on the frequencies that they can directly see, this could prove to be very interesting for observing the cosmos.
If they possess something akin to compound eyes as their means of vision, then their microscope technology would have to adapt to their visionary constraints. This might give them a competitive edge on optical-based observation equipment once they put that knowledge into making telescopes and the like.
[Answer]
All of the members of the species have vestigial light receptors covering their exoskeleton, connected to an equally vestigial independent nervous system (inherited from an ancestor species that used to run away from light, or maybe seek it). They all more or less "feel" light, but for most it's a sensation akin to when us humans have the hairs on our arms stand up.
Some individuals, though, have that vestigial system erroneously connected to their central nervous system which made them suffer from a sort of synaesthesia. Once this was a nuisance, but now it's like having a multicore visual cortex, and their ability to process and understand information relating to light is much greater, as they understand light in a much more intuitive way, like a person with synaesthesia can "taste colours" these guys can comprehend light in a way nobody else can: a bunch of data in a set of screens around them merely describing light is way more revealing to them than it is to even an AI. Light and data about light is like a pristine clear symphony to them, for lack of a better analogy.
[Answer]
## Living mass spectrometers
As a species which is culturally more interested on what is below than above then, they fastly understood that their habitat was finite and thus developed a very strong interest for “ecology”.
Thanks to their tremendous biological knowledge, they embraced eugenics and modified themselves so they would be able to use the totality of what their habitat offered them. They became living recycling machines, able to “eat” literally everything then sorting and separating elements so they can reject raw materials which will be reuse. In the process, some of them became living mass spectrometers, their ability to quantify the sorted elements being precise up to the atom…
Therefore, there is today no other species able to achieve what they can do with a simple sample of dust, mud, roc or atmosphere of a planet: they are the ultimate species to understand the composition of a planet.
[Answer]
Does your insectoid species have castes like ants and termites do? If so, perhaps they could, over time, develop a caste dedicated entirely to astronomy. Perhaps their eyes are better adapted to seeing at further distances, maybe their intelligence would be higher than that of the other castes, maybe they are more perceptive.
[Answer]
Maybe most of the galactic civilizations are surface dwellers; but your insects are subterranean.
They normally don't see the stars; but they are exceptionally good analyzing the planet below; having no fear of the dark and not being frightened in enclosed spaces. So maybe those new members of the galactic society are perfect for long-range-flights where you have to stay in an enclosed space all the time, or for mineralogy on newly discovered planets.
[Answer]
Presuming the atmosphere is unfavorable for direct observation, space telescopes are how astronomy is needed, hence innate skills with electronic displays systems would be needed.
This would open the door to a lot of very advanced technology we are just getting now in astronomy such as the use of the planet's orbit to get multiple perspectives of a star cluster. In most cases, as someone else mentioned, juveniles of insects are better at parallel 3D visual-spacial tasks like formation flying. Hence I would presume that it would be tied to life cycle, not particular genetic traits.
[Answer]
## Insects are Genetically Versatile
Insects cover a vast range of biological niches, and there are specializations within insects nearly every biological dimension. They reproduce in vast numbers with short generation times (typically, there are exceptions), and should evolve faster than long-lived animals.
## Astronomy is About Light -- Photons
Until the development of gravitational wave detectors, all of astronomy requires detecting photons. As humans, we started with photons of human-visible energy, and have expanded to cover most of the spectrum.
## Therefore, Eyes
Insects, with their segment eye structure, could evolve to have a greater range of photodetectors, from IR through soft-UV. One can imagine spectroscopy being built into specialized eye-lets. With more information, insects (or certain, gifted insects) could directly observe many more properties of space.
With more information, as they developed technology they would be drawn to more significant observations earlier than humans were, and might be data-driven rather than religion-driven.
## Better Eyes Make Superior Astronomers
So the answer is that the segmented, multi-part structure of the insect eye can evolve to be much better astronomical observation tools, and individuals blessed with the most extreme range of the genetic variation would excel.
[Answer]
[From the first hit on a search.](https://study.com/articles/Astronomer_Job_Information_and_Requirements_for_Students_Considering_a_Career_in_Astronomy.html)
>
> According to the BLS, astronomers must have the ability to solve complex problems, conduct research, and accurately analyze data. They need strong math and science skills, along with being about to work within a team. It also helps to have knowledge of specific science-related software programs.
>
>
>
So possible abilities are ability to solve complex problems, analyze data, do math, work within a team, and use of the relevant programs.
So that hive mind option would actually help since it would boost team work. But making the species social and cooperative would be enough.
Mathematical talent would also help since it would be easier to get those good math skills. Especially if it comes in the form focussed on math relevant to astronomy. Possibilities I can see are being better at working with larger data sets or with multiple dimensions. These would help you process the data your programs give you more efficiently and solve problems related to space or space-time with less effort. Being able to intuitively understand relativistic phenomena would be a nice talent for an astronomer to have.
Related but not on the quote because the quote is for humans and this is a human limitation. Humans kind of suck at understanding curved or rotating space. Being able to deal with that intuitively would be nice.
Similar to being able to process larger data sets, simply having better working memory without extra mathematical aspect would still be useful. Better ability to learn and recall would also help.
Also, from the same.
>
> In addition, because astronomy graduate programs are highly competitive, beginning research early in an academic career can be very beneficial. Students should be open to interning at astronomy labs, working with professors on research projects, and/or completing an undergraduate thesis project to make themselves more competitive for these graduate programs.
>
>
>
Astronomy might simply be the new hot thing with the local government heavily promoting its study. It would attract the best students. Research funding might be easy to get with opportunities to participate abundant. Internship positions might also be easy to get.
My recommendation would be to mix and match several factors from the above. You should stress factors that are specific to astronomy such as the funding and support from local government. Alternate or complementary to that, the superior ability to work with three or four dimensions is specific enough to be a good choice. It is not really a problem if they are also really good at some parts of physics and math, right?
Also include something that is easy to demonstrate. If the story is set on their home planet you can just show the value locals give to astronomy. Otherwise ability to work with large datasets is probably the best pick. You can probably show them being really good at processing tables of data or checking a long list or a long text in some story relevant context.
] |
[Question]
[
I'm trying to create a world map for my fantasy novel. My problem is that I love designing things, and I'm finding myself bogged down with figuring out how desert A got where it is, and how plain B's temperature is different than plain C, and so on. I've never studied that type of thing in any great detail, so my knowledge of how the different ecosystems form is limited.
This has led me to ask the following question: how can I know if a map is realistic?
For the majority of readers, knowing that plain G would be cool instead of hot, or that a forest would require more rainfall than is mentioned, is not going to be a problem. However, there will invariably be the one person who knows how all those things work, and if the impossibility of the map really gets to him, it could sour his reading experience. That's not something I want.
So how do I know if a world map is realistic, short of knowing how every ecosystem on earth forms? Is there a cheat sheet?
**Post-Answer Note:** While I've marked the answer by John, it's not the one that helped me. It does answer the question, but what I ended up using was the [resource linked by Monica](https://medium.com/universe-factory/climate-modeling-101-4544e00a2ff2) in the comment below. It was detailed but still simple enough to provide exactly what I needed. I was able to create a realistic world in a matter of hours, and have zero doubts about whether or not it is realistic.
[Answer]
First it is always possible to educate yourself, you can find secondhand or old edition textbooks fairly cheap just find a beginners Climatology, landform geology, and Meteorology book. learning the basics in not that hard.Continuing education classes and even [Khan academy](https://www.khanacademy.org/) videos are also options.
Second, here is some bare bones basics just to get you started. I am sure other will have many things to add to the list. I have bolded the important take aways.
There are a few basics worth considering, and that make bad maps easy to spot.
1. Landform, nothing gives away a bad map faster than landform. **Continental rock mass tends to break at a 120 (or 240) degree angle and the majority of the earth's coastline is made by connecting these angles.** big sweeping smooth curves or long straight lines are just unnatural in a coastline and tend to stick out. **Mountains are rarely isolated and tend to run in ranges. Also mountains come in many shapes not just curved pointy cones.** Incidentally if you have your mountains and coast laid out most of the map will make itself if you have the basic knowledge.
2. Rivers. I don't know how many maps I have seen with rivers that start in the middle of nowhere. **Rivers start small and numerous in the mountains and run down hill, getting fewer and larger as they go and connect, most eventually reach the ocean. The closer the mountains are to the coast the more unconnected rivers you will get.** [Here](https://img.purch.com/w/660/aHR0cDovL3d3dy5saXZlc2NpZW5jZS5jb20vaW1hZ2VzL2kvMDAwLzA4Ny8zMjQvb3JpZ2luYWwvcml2ZXItYmFzaW5zLmpwZw==) is a map of the river systems in the US to give you an idea.
3. Rain, wind tend to come from one prevailing direction in a region and mountains cause moist air to drop its water as it rises, this creates a [rain shadow effect](https://en.wikipedia.org/wiki/Rain_shadow). One side of a mountain range is always drier, which side is determined by the major winds. If you have jungle on one side of a large mountain range the other side will tend to be much drier. **If you want a drastic changes in rainfall over a short distance you need a reason, mountains in between are usually it otherwise changes should be more gradual, deserts don't suddenly change into rainforest. Change tends to be gradual**
4. Climate belts AKA [climate zones](https://content.meteoblue.com/en/meteoscool/general-climate-zones). the planets spin combined with drag in air movement creates zones of different climates on earth. the same zones with hot jungles also have hot deserts. The other facet of this is major [air cells](http://gotbooks.miracosta.edu/oceans/images/world_wind_zones.jpg) these zones are also created by large moving air cells, All you really need to know is rising air drops rain while falling air from these cells creates deserts.this means rainfall patterns also tend to run in belts across the planet. **It is basically impossible to get a jungle or desert or any ecosystem that stretches too far north and south.** [5](http://gotbooks.miracosta.edu/oceans/images/world_wind_zones.jpg)
Lastly Sometimes less is more, smaller local maps are easier to do than large global ones, by removing many variables like jetstreams and ocean currents you can skip a lot of those problems.
[Answer]
Earth, your cheat sheet is earth. You are not an expert and you don't need to be. Chose an ecosystem for your starting location, then decide where the action goes in relation to that place. Where is the planet getting the most prolonged contact with its star? It will be warmest there. [Proximity](http://www.acer-acre.ca/resources/climate-change-in-context/general-concepts/proximity-to-water-bodies) to an ocean or large body of water makes it more humid but also more temperate:
>
> Large bodies of water such as oceans, seas, and large lakes affect the
> climate of an area. Water heats and cools more slowly than land.
> Therefore, in the summer, the coastal regions will stay cooler and in
> winter warmer.
>
>
>
[Altitude](http://www.mbgnet.net/sets/rforest/explore/elev.htm) also affects your climate. The higher up you go, the lower the temperature:
>
> For each 1,000 foot rise in altitude there is a 4°F drop in
> temperature. For example, if at sea level the average temperature is
> 75°F, at 10,000 feet the average temperature would be only 35°F.
>
>
>
Deserts form due to many factors but have extreme temperature shifts because sand reflects sunlight but does not store it long, leading to hot days and freezing nights. Between extreme ecosystems, there must be a substantial transitory territory (except in the case of altitude, where the transition is shorter and more vertically inclined.)
Finally, when in doubt, check if analogues to your fiction exists in some way in reality. This isn't "cheating", it's a way to ground your player and helps him suspend his disbelief.
[Answer]
[](https://i.stack.imgur.com/iBWRi.jpg)
Put your story in a real place on Earth, then change the names. Robert Howard did a great job of this with his Hyborian Age. If you spread out his world and drop the Mediterranean in it is Europe, Africa, the Middle East etc. Of course the premise was that the Hyborian age was actually the remote past of the real world so it should be similar. I have read that Sword of Shannara did something similar: the world is basically North America.
This maneuver makes weather and geography easy, because the author can just pull the details in from the real world. Just look it up.
[Answer]
Look strongly at John's answer.
If you are wondering where to place mountains and valleys, remember that mountains exist for a reason. Most mountains are created when two plates of crust push against each other. So, they tend to be in rows.
Also, mountains are sharper when they are new due to the effects of erosion. Using the US as an example, we have two major mountain ranges: in the West and in the East. The western mountains are newer so they are taller and sharper. The eastern mountains are shorter and rounder because they have been worn down over time.
Mountains can also be created by volcanic action. They often exist in newer mountain ranges as the cracking of the crust allows magma to find it's way up. However, they can occur other places as well due to a hot spot under the crust. Since the crust moves, there will be a string of this kind of volcano. The Hawaiian Islands are an example of this kind of volcano. You can also get volcanoes where the crust is being pulled apart. Most of that occurs in the oceans but it can happen on land (as is currently happening in Africa). That area will become a new sea but that won't happen for a very long time.
Once you have the shapes of the land and seas from deciding what is moving where, figure out prevailing winds. You can use the Earth for a model of that.
You can also figure out ocean currents. A very simplified version of ocean currents is to draw clockwise circles (counter clockwise in the southern hemisphere) in every big body of water and then draw smaller circles near land masses where there are hallows in the coast. Things are actually more complicated than that but this will rough it out. Where the current travels from the pole toward the equator, it will pull colder water and the air that passes over it will be drier. Where the current rises from the equator to the pole, the water will be warmer and the air passing over it will pick up more moisture from evaporation.
The windward side of mountains will always have more moisture than the leeward side. Swamps happen in flat spots where water drains slowly. This usually happens in slow areas but could happen at elevations that have poor drainage.
This will allow you to rough out your terrain and climate but there can always be local oddities. The Earth has plenty (Grand Canyon, salt flats, Yellowstone geysers, Butte Montana, etc.).
[Answer]
Knowing how every ecosystem on earth forms actually isn't that complicated. You really only need to know two things: how hot or cold it gets in an area, and how much water it gets and when. Places near oceans are usually wetter than places that are inland and/or blocked off by tall mountains; cool wet places will experience snow in the winter, while places that are rainy and warm all year round become rainforests. Depending on the size of the continents in your world they might experience on earth as well.
After that it's just a question of knowing what types of plants and animals are likely to be found in what climate, for which earth can be a pretty good cheat sheet. I've also found [Geoff's Climate Cookbook](http://img.4plebs.org/boards/tg/image/1428/00/1428006590131.pdf) to be a useful resource in this area.
] |
[Question]
[
Can powered exoskeletons convey the same advantages to animals as they do to human soldiers?
A few years ago we saw stories about the development of legged autonomous vehicles for accompanying soldiers on foot and carrying heavy loads for them. The prototypes tend to look like cows. This did not prove fruitful and funding has discontinued for this idea.
[](https://phys.org/news/2012-12-legged-squad-ls3-darpa-four-legged.html)
However, the idea of a [powered exoskeleton](https://en.wikipedia.org/wiki/Powered_exoskeleton) for a person to wear seems to be doing well, and development continues.
[](http://www.sciencemag.org/news/2015/10/feature-can-we-build-iron-man-suit-gives-soldiers-robotic-boost)
Although autonomous beasts are not working out, why can’t you use the idea that is working along with *real* animals that have served these roles for thousands of years? That is, take a donkey or a mountain goat — it knows how to maneuver in rough terrain, where to place each footstep even in the worst cases, not fall over, and not wander off a cliff. Put the animal in a powered exoskeleton, so it can handle enormous loads (including its own armor) and generally not get tired.
Horses have been with us for a long time, too. Well-trained war horses gave us [dressage](https://en.wikipedia.org/wiki/Dressage) which is now an Olympic sport! So certainly we could train horses to use such powered suits. And while those robot beasts had trouble following commands and understanding what needs to be done, a dog such as an [Australian Shepherd](https://en.wikipedia.org/wiki/Australian_Shepherd) *understands* this, and if himself equipped with a similar suit, will *eagerly* keep the pack animals in line.
So, can powered exoskeleton convey the same advantages to animals as it appears to for humans? Will this be practical, given that exoskeletons are already developed for the people and animals are already available in these roles?
---
# update
I’m thinking of a future as described in [the railguns question](https://worldbuilding.stackexchange.com/questions/81409/handling-recoil-of-hand-held-railguns) where we have **superconductors** and **battery tech** that allows the energy density of chemical fuel but direct to electricity.
But, the question works in any case where **mecha for people** is something that is being done (therefore it’s practical).
[Answer]
The issues facing autonomous beasts would not be prevented by sticking a pack animal in an exoskeleton.
The reason Boston Dynamics [LS3](https://en.wikipedia.org/wiki/Legged_Squad_Support_System) was not accepted by the US Marines was for reasons of noise (It was powered by a small engine) and difficulty with field repairs. It was sufficiently advanced to be able to traverse most terrains and right itself if it fell.
If you had an animal in an exoskeleton it you would still need to power the exoskeleton and making repairs to the system would still be problematic. Additionally you now have an animal that you need to feed, train, and worry about getting shot who will panic as soon as the shooting starts.
[Answer]
**Ye.. sort-of.. s**
Animals are extremely adaptable and have shown to be able to learn and adapt at similar speeds to humans in [various situations](https://www.k9carts.com/rear-wheelchair) (e.g. training them to do things).
The biggest *effort* aside of money would likely be the time it takes to get an animal acquainted to this new situation.
The biggest *issue* though would be that these animals will still have their own mind, so no matter how well trained and domesticated it may be, there's always a factor of uncertainty. While this also hold true for humans, humans at least have a goal they work towards, some motivation to do a job - with animals there is no direct goal/motivation aside from maybe a treat or something along the line.
So, considering *cost* and *time* it takes to train an animal that will still need time-outs, rest and motivation, it becomes **cheaper** and more effective **to just build a robot**/semi-autonomous-drone. most of the **tech** needed **is already available** as these artificial muscles and actuators need plenty of math-power behind them to properly move.
[Answer]
## Yes/No
To answer your question directly, yes a powered exoskeleton would be able to augment the natural abilities and potentially make animals them more useful.
**However** it would not be very practical. Building a machine around an animal is very challenging in its own right. Then you have to power it and train the animal to use it. Also, if you want the machine to be able to move with the animal to keep balance, for example, it is going to have to be every bit as dextrous as the animal. It will also need one heck of a sensor array to monitor the animals' movements to keep up with it. Sure, an animal could be trained to cope with the difficulty of operating a less dexterous machine, but that is time-consuming. [Boston dynaimcs](http://www.bostondynamics.com/robot_Atlas.html) has already created robots that can balance themselves.
[](https://i.stack.imgur.com/uAYKC.gif)
[Animal](http://www.bostondynamics.com/robot_cheetah.html) monstrosities that behave like animals.
[](https://i.stack.imgur.com/Ec1JP.gif)
If you really want an animal like a machine, it's easier to build the machine like the animal rather than make a machine that the animal can use.
### Update in light of modifications to the question.
It's still more practical to just build machines because there is no training necessary, just program and go. The machine could use the space that would be taken up by its animal operator to be more powerful/durable than an animal could ever be.
[Answer]
**Not in the current form**
The [BigDog](https://en.wikipedia.org/wiki/BigDog) project was designed to be a robotic mule. Carrying heavy loads across uneven terrain. Places footsoldiers can reach but wheeled vehicles cannot. The robot was not considerably stronger or faster than a live animal. But it was preferable in a combat situation because it requires no food and knows no fear.
It was ultimately rejected as the engine was too loud for combat use. It immediately gave away its position, and the position of its handlers, to any hostile forces nearby.
Equipping a live mule with power armor combines the worst aspects of animal and machine. Now you have a loud, easily-spooked animal that needs to eat and sleep. That means carrying feed on its own back or pausing to graze several hours a day.
The only advantage of the hybrid system is it might be stronger or faster than either of the animal or machine. However, as I said, this was never the original purpose of the project.
] |
[Question]
[
***Original post:***
>
> Imagine a world in which both left- and right-handed [chirality](https://en.wikipedia.org/wiki/Chirality_(chemistry)) appeared and evolved into a variety of complex organisms comparable to post-Cambrian Explosion Earth (both plant and animals).
>
>
> As on Earth, chirality would apply to amino acids, sugars, enzymes, and potentially other essential biochemicals. A biochemical with the correct chirality will taste or smell a particular way to an organism with matching chirality, and be digestible/usable by their body, while a biochemical with opposite chirality will lack flavour or smell differently, and their body may be unable to digest it.
>
>
> Is it plausible for both forms of chirality to not only arise but thrive, without one driving the other to extinction very early on?
>
>
>
***For clarification:***
As stated in the comments below, assume the following:
* In primordial conditions the likelihood of a given biochemical molecule developing left- or right-handedness is 50/50.
* The conditions that give rise to such a molecule are, at least in the immediate area at the time of its formation, stable and/or repeatable enough that opposite-handed molecules will also form.
* If nearly identical conditions can be found elsewhere, the same processes there may give rise to opposite-handed molecules as well.
So in reading the question above, emphasis should be placed on the second half:
>
> Is it plausible for both forms of chirality to not only arise but **thrive, without one driving the other to extinction very early on?**
>
>
>
"Early on" should be understood as any point prior to the emergence of multicellular life.
[Answer]
In the primordial ocean the first compounds were synthesized essentially by random chance using available energy sources, including radiation and lightening; here chirality was 50/50.
From this "soup" the first, very rough, self-replicating "things" emerged.
These thrived consuming the large amount of available organic material.
As soon as these materials become less abundant a strong evolution push appeared: the ability to produce needed complex (rare!) compounds from relatively abundant "simpler" ones.
This lead to first enzymes acting as catalysts for chemical reactions.
This is the point where symmetry was broken. Most (if not all) enzymes catalyze a single chirality.
This means (relatively) shortly after first "true" living proto-cells started colonizing the ocean (much before fitoplancton started changing atmosphere composition) the vast majority of organic compounds available were produced by "living" cells... and thus with a specific chirality.
It is conceivable two non-communicating primordial oceans could have given birth to unrelated bio(emi)spheres with partially (or completely) different compounds, possibly with different chirality. As a very special case it would be possible the two bio(emi)spheres could include the same compound with different chirality.
Probability of something like this happening in practice is anyone guess, but I regard it as rather low. Rationale being a very long and complex chain of unlikely events was needed to produce living cells in the first place and chance this chain could happen *twice* in the time span needed for first one to fill all "likely" environments is quite low.
Complex reactions are very difficult to set-up and replicate; as an example mitochondria (who learned how to produce energy from sugar and Oxygen) were never replicated, but accepted as symbiotic "partners" inside other cells, being so successful there's virtually no cell not hosting them (and they are all closely related; no "parallel evolution").
Bottom line: it is conceivable to have different and unrelated biospheres on the same planet, given suitable morphology. It is also conceivable these two biosphere could come in contact much later (perhaps because of a tectonic movement removing the barrier). In this case, however, it's extremely unlikely the biota would be anywhere near "similar". Chirality would be the least of the problems.
*UPDATE:*
O.P. asked: At some point the progeny of these two incubators – whether two oceans a world apart or two tide pools metres apart – have to come in contact. *Then what happens*?
It (as always) depends on specifics. I'll attempt a speculation.
In general there will be an initial stage where the two different populations will simply ignore each other and compete on an equal basis for the available resources. Compounds produced by the "other world" would be useless or even toxic (because the enzymatic set isn't able to handle them) and thus no direct interaction will happen.
From this moment, as said, the two populations will be in competition for resources, this means if one has a significant edge over the other then it will slowly drive the "less efficient" "half world" toward extinction (it may resist in some sheltered niche). This is what happened to anaerobic bacteria in our world when more efficient aerobic metabolism appeared.
OTOH, if efficiency (even if based on different chemical processes) is about the same then some kind of "mutual recognition" is going to take place.
There will be a push to:
* avoid poisoning from the "other"
* find ways to metabolize "alien" compounds.
Each step in this direction risks breaking the above-mentioned equilibrium and will push to develop "counter-measures". Something similar to "invention" of [lignin](https://en.wikipedia.org/wiki/Lignin) by trees which took million years to bacteria to find out a way to cope with.
Here you can imagine two divergent results:
* war: competition to death and thus one of the two "halves" prevailing sooner or later and driving the other to extinction (or to some biological enclave).
* cooperation: development of one or many symbiotic arrangements where complex biological interactions will include species from both "halves".
In any case it would be extremely unlikely "parallel evolution" of any kind.
[Answer]
Sure. In [How can orientation-discriminating people keep their views when it turns out they live on a non-orientable surface?](https://worldbuilding.stackexchange.com/q/101804/8914), I posit a world on a [real projective plane](https://en.wikipedia.org/wiki/Real_projective_plane) (see the 5th note). In particular, it is non-orientable.
In this world, although chirality exists locally, it does not exist as a global property of any object (chemical, organism, etc...). This means that as life spreads across the world, and wraps around it, it will essentially reverse its chirality automatically, like a mobius band (indeed, a projective plane is basically a mobius band without a boundary).
I suspect that many organisms would become partially achiral (even locally) in such a world though, so as to be able to eat more things.
Note that your world doesn't necessarily need to be a real projective plane for this to work. Any [nonorientable surface](http://mathworld.wolfram.com/NonorientableSurface.html) will due (just remember that it has to be embeddable in a suitable 3D space, unless you want your world to be another [Flatland](https://en.wikipedia.org/wiki/Flatland)).
[Answer]
We can delve into levels of chemistry that would astound you, just from this question alone.
Keeping it short and non-technical (relatively so), it would be theoretically possible, though, as pointed on in comments on the question, it's unknown about what the chances would be.
The best place to start would be finding out how chirality is determined (I don't mean how we determine a chemical's chirality, but how the synthesis of the chemical determines the chirality). [This published 'theoretical' study](http://www.mwdeem.rice.edu/djearl/chiral_htp_jcp2003.pdf) shows an attempt at predicting chirality:
>
> Results for a variety of TADDOL [...] derivatives show good agreement with experimental findings for the sign, magnitude, and the temperature dependence of the helical twisting power (HTP). [...] We discuss the temperature and solvent dependence of the helical twisting power and argue that in all the systems studied here, preferential selection of certain molecular conformations at different temperatures and in different solvents are able to explain the observed experimental behavior of the HTP.
>
>
>
So it's theoretically possible to predict chirality. Awesome.
Next we need to know the processes the biochemicals that started life underwent to be created. Then the same for the biochemicals early life needed to survive. This goes on until you have an accounting of all the chemicals, and their synthesis conditions.
In other words, likely impossible to discover.
That being said, if we make the assumption that life of both chiralities arose in the same biosphere, then it's really a matter of "could they co-habitate?" Probably, but not in direct association. Almost all animals are territorial, and would likely force the other out of their territories. A lot of plant life relies on animal life to aid in pollination/spreading seeds, so that chirality of plant life would flourish there while there other may not (specifically ones that require digestion interactions for spreading seeds, like bird-poop).
] |
[Question]
[
On Earth, [the polar bear](https://en.wikipedia.org/wiki/Polar_bear) is [among the most sexually dimorphic animals](https://en.wikipedia.org/wiki/Polar_bear#Physical_characteristics), with males being on average almost twice as heavy as females (Wikipedia claims average weights of 450 kg for males versus 260 kg for females, with a significantly larger difference in the extreme cases).
There is an obvious natural limit to how large dimorphism can be sustained, namely the reproductive behavior of the species. In mammals, if the male is unable to safely mount the female, then procreation becomes much more difficult and at the extreme end impossible. That would then lead to either limit or reduce the dimorphism in the species (possibly instead leading to a subspeciation, with size as a determining factor), or lead to a change in the reproductive behavior of the species.
However, what if we are looking at it from the other end of the scale? **What evolutionary factors could *contribute* to sexual dimorphism in animals, and what factors may contribute to supporting a large degree of sexual dimorphism in large mammals?**
Bonus questions: Does the polar bear represent approximately the largest sexual dimorphism sustainable in large mammals in an Earth-like environment, and if so what might be the specific limiting factor in the case of that species? Would a larger degree of dimorphism be sustainable in an environment different from the polar bear's natural habitat, and what environmental difference might be the determining factor in that case?
For the purposes of this question, I am primarily concerned with differences in size, but if answers touch on other aspects as well I certainly am not going to downvote because of that.
[Answer]
Sexual dimorphism occurs when the male and female individuals in a species come under different selective pressures. Most evolutionary pressures, be it predators, disease, or starvation affect both sexes indiscriminately. Males and females have to worry about them equally and so tend to arrive at the same optimal solutions, and so are not different themselves. You only get sexual dimorphism when the males and females need to do different things. This can be because of different behavioral roles. You can imagine a species where the males hunt and the females guard the nest and therefore need different physical traits to better adapt them to their respective roles. But by far the most frequent cause of sexual dimorphism is sexual selection.
There is an inherent asymmetry between the male and female members of a species when it comes to reproduction. In mammals, reproduction for a female is a prolonged, energy-intensive process. In some species females can spend years rearing a single offspring. Most male mammals on the other hand have virtually no limit to how many offspring they can father. This means females and males have very different reproductive strategies. Females tend to be selective in their mates, while males tend to try to copulate with as many females as possible. Of course, there are plenty of exceptions, but these are general trends. These different reproductive strategies result in different evolutionary pressures on the different sexes. Males that have bright coloration may be more visible to predators, but are also better at attracting females. Whereas the female members of the species have a reduced incentive to make themselves flashy.
To get to your specific question about size dimorphisms, male mammals tend to be larger than their female counterparts because of competition. Simply put, males compete for females, but females don't compete for males. The larger a male is the better it is able to out compete rival males to monopolize as many females as possible. The biggest downside of being too large is that you have to eat more. I don't think ability to copulate is too much of a concern, because all of these changes are gradual and females would adapt as well. Outside of various specific limitations like needing to be able to climb trees, run fast, or fit into narrow tunnels, getting enough food is definitely the limit to animal size.
The above is a decent (I hope) description of how sexual dimorphism arises, but I'd like to give you more succinct list of the most important factors for getting big males.
1. Your species needs to be polygamous, and the more polygamous the better. In a monogamous species males have less reason to fight over females. In a polygamous species in which males control large harems of females a large fraction of males will never be allowed to mate and therefore will have strong pressures to be able to compete.
2. Your species needs to have an abundance of available food. A large male needs more food, but also has less time to forage it as they must defend their territory and females. If food is a limiting factor then the largest males will be less successful than the smaller males and male size will be driven down.
[Answer]
While Polar bears represent the largest dimorphism in modern mammals, the most extreme case are some species of angler fish, where the male has become a small parasite attached to the female.
The evolutionary factors in general are what makes it more likely for the male or female to survive and pass on their genes. In polar bears, size provides advantage to the males in hunting and driving off rival males. With angler fish, becoming a parasite means the male has no rivals to pass on its genes once it is attached to the female, as well as relieving it of the need to hunt for food.
Since evolution has had 500 million years to experiment, I suspect the 2:1 ration of polar bears may be close to the limits of dimorphism possible in mammals. More extreme ratios might need adaptations of different morphologies (an anglerfish like ration might be achieved in creatures derived from marsupials, for example).
[Answer]
Polar bears might be the most extreme in the wild...but I get the feeling the breeders of the Chihuahua Husky mix might be a benchmark of the more extreme difference in partners size.
First to point out - size is one attribute that I can focus on, but it should be noted it's simply one attribute out of many. As a good example that was stated above, frogs are around the same size for a male and female, but (generally, some exceptions) only male frogs croak. Rather simple...the male frog is using croaking to attract a mate, which comes at the cost of attracting predators. Peacocks and Betta's use visual cue's with the males visual plume being it's method of attracting a mate. In these cases, the male is taking on the role of attracting the mate, often at a risk to it's own survival. The methodology of this 'attracting a mate' often becomes the basis of sexual dimorphism (this is an interesting line simply because it shows how evolution heavily contains a behavioral aspect)
Another point to consider...survival of the fittest/strongest isn't really true, on a genetic level it becomes more 'survival of those most capable of mating'. The fastest, strongest, smartest, fittest peacock around may never get the opportunity to breed if it lacks the plume. This is the point that really starts to define the differences between males and females in a species, those males possessing a trait that attracts them the mate and allows them to pass along their genetics will pass that attribute on to the next generation. This has the tendency to create some pretty extreme mating displays and some stark contrasts in female / male appearances and behavior.
If you want to highlight size between males and females in a species, then you need to focus on species that have the behavior that stress size as a mate attraction technique, usually in the form of strength. Antlered herbivores are good examples here...males fight between each other to win and defend their females. This process is usually the two stags sizing each other up before clashing antlers. However this doesn't necessarily promote sheer size...there are a lot of components of the fight such as the antlers, endurance, agility, etc...and although you will see a pronounced difference between males and females here, you won't find the biggest difference.
To get to the biggest difference, you need to find the mate attraction technique that values size above fighting skill. And you'll find that in intimidation. Intimidation is different than fighting...fighting is a fall back when the intimidation fails and a truly successful intimidater would never actually fight. Size and scariness becomes an end all here...not strength or agility, but size at all expense and it's in this category of creatures that you'll see the biggest variations in size between sexes in the same species. Polar bears fit in this category capable of using intimidation to scare other creatures such as wolves off a kill so they may claim it for themselves. Most male on male polar bear encounters end with one of the males backing off before fighting occurs...only extremely close matchups or extreme situations actually end in a fight.
There is one creature, now extinct, known as the giant short faced bear that might have seen a greater sexual dimorphism as far as size goes (my speculation). The giant short faced bear would have been a brutal opponent in battle, but it is most likely these creatures were scavengers and not killers, relying on their extremely strong sense of smell to locate a fresh kill and it's massively intimidating frame to scare off any competition for that kill (15 feet tall when reared up with overtly long arms and giant claws). Mate selection within the giant short faced bear was likely intimidation based, leaving the males most capable of intimidating the most capable of mating and a strong pressure on males to become larger and larger.
] |
[Question]
[
If you wanted to build a space hotel, say with 500 rooms, how many people (excluding hotel guests) would have to be permanently on that space station?
I'm assuming getting into space is safe and unproblematic, yet still expensive and time consuming, so "normal" rich people would book at such a hotel (the same type that would book e.g. on luxury cruising ships).
I figure you'd need the following groups of people:
* Normal hotel personnel (room service, cleaning, restaurant crew, etc.).
* Extra services which we would not normally consider part of a hotel, but which we would need to have available (medical service/emergency room, fire service, space station police, anything else?).
* Extra services/infrastructure for personnel (because they can't just go to the shop or cheap restaurant around the corner).
* Those actually operating the space station (maintaining space station technology, keeping the space station in the correct place in orbit, controlling the rotation for artificial gravity, ...).
However I don't find out how to get data even for the first point. So, what would be a reasonable number of people working in that space hotel?
[Answer]
I don't think it's going to be all that many (i.e.: the 366 quoted).
Also, you're going to have single workers, and pay them a bunch - or you're going to have to move families for long-term contract types.
Top chefs, administrators, and some other people might need to get the family contract. But the rest you can assume are just out-of-college, under 40 and single - doing a high-paying gig (like oil-rig workers) and then going back to civilization.
Also, robots. A *lot* of stuff can be done now (e.g.: automated bathroom cleaning, roomba, etc) via automation, and probably more in the not-too-distant future.
But, rich people may be paying in order to have 'servants' do things for them - i.e.: the human touch.
So, it also becomes a question of why are people going to the hotel in the first place? Is this in earth orbit? Or is it near something/some place that people want to go to? Distance (both time and space) from other people is a factor in how many people you need.
You're definitely going to have to have exterior maintenance people. People who check the rockets (you're going to have to be able to move the thing for space debris), as well as hull integrity, power management, etc, etc.
I don't think you're going to have landing bays and stuff. Use existing space-shuttle docking plans - no extra crew or people for that, the people flying the shuttle are perfectly capable of docking. You might want one flight controller (who can probably do double duty doing something else for the rest of the time - how many flights a day do you expect? i.e.: how long do people book their hotel rooms for?).
You're going to need guest services people. Singers, dancers, bed-warmers (ahem, probably double-duty if it's not an explicit job), microgravity coaches/team members, etc. A lot of those people could be double-duty with other tasks - but some are going to be single-duty (prima dona singers/musicians, for example).
You'll have to have cooks if it's a stand-alone hotel. I doubt there are pizza delivery places in space. Unless you're near enough (transit time) to other places, it's going to have to be part of your complex. Automated meals are only so-so, unless you have amazing technology (nano-assemblers/replicators) - and people often like to see people making their food (often).
Do you count crew of ships and ground facilities? You'll need a ton of people on the ground to handle stuff, you'll also need pilots, ground control, fueling specialists, repair guys and such (and marketing, sales, and...). But people sleep on the space-shuttle, and if space-flight is cheap and easy, there's no need to have pilots bunking on-station - they just de-orbit (assuming less than 12-14 hours. on-duty) and go home for the day. Your emergency pilots (if needed) can be double-duty staff. But, you don't even need pilots if you're in Earth orbit - just give them re-entry capsules, and tell them to get in and the computer handles the re-entry.
You will need trained emergency staff - but that could be part of every worker's job. You're going to have to pay these workers very well (assuming no orbital society to draw workers from), but since you're paying them very well, you can also require them to be very skilled. Everyone knows how to fight fires, handle decompressions, basic medical care, etc.
Speaking of medical care, you're going to need a set of physicians (round-the-clock staffing, and emergency staffing: probably minimum of 2-3, and more likely 4-6: assuming skilled nursing double-duty types are available to triage/help). You're far away from any medical care, and space is dangerous. Assuming no automation to take care of that. Telemedicine will only work in Earth orbit, otherwise the lightspeed delays will make a hash of any operation not run by a skilled program. You don't need a full hospital, but you do need an emergency room - and people who are able to take direction from tele-doctors.
Depending how rich your clients are, you may need some bulky security staffing.
You may have weapon systems on your hotel, to prevent hostage-taking / takeover attempts.
You'll definitely need a house detective or two. But those might be double-duty - especially so to handle internal theft, etc. One or two of those may be posing as guests, if so you'll lose a room or two of capacity, since they should be treated exactly as guests.
You don't need any yard/landscaping workers. It's possible that your maintenance crew is minimal (i.e.: emergency repairs only), and you bring up skilled workers to handle over-hauls and bigger jobs / routine maintenance - all that happens on scheduled intervals and/or on contract, so you wouldn't count them as part of your normal staff. They might even bunk in their maintenance vehicle and never come in your hotel most of the time. Interior repair people, yeah, different story.
Unless there's something to see in the local area, you're not going to need drivers for hotel-shuttles that would normally take you to and from the airport or to and from the symphony. Just your dedicated transit shuttle pilots. If there is something to see in the local area, it's possible your other staff can double-duty. Nor are you going to need valet parking :D
You're not really going to need a lobby person - if there's nowhere to go in the local area, and flights come in at scheduled times. There's no random dropping in by people with their own space-yachts. If there is, then you may need to staff that. But with a flight controller, you'll see them coming / have warning to pull someone out of another area and go down and greet them. It's not like someone pulling into the roundabout from the road. It'll take a moment (/snark) for them to dock, and you'll probably have at least 30 minutes of warning by radar that someone's headed your way (esp. if you have weapons & security).
After adding and subtracting those categories, call up your local posh hotel and ask how many workers they have.
[Answer]
Here are the people you would need:
* **Those operating flights to and from the space hotel.** (Perhaps two pilots per ship, five other crew members, and a host of people on the ground (100-ish?)) But only the crew members would be staying *at* the hotel, and even then only for a short period. So seven crew members per ship.
* **Those coordinating the flights from the safety of the hotel.** I'd guess that you'd need at least 10 people for this, although that could vary, depending on the number of flights.
* **Technicians and landing-bay workers.** Let's say five people per ship, with a negligible number of auxiliary workers.
* **Those involved in keeping the station in orbit, and communicating with ground control.** These are the top guys in charge, as well as those reporting to them. I'd estimate twenty-five or so to deal with all the aspects of keeping the thing where it's supposed to be.
* **Extra services-people.** I don't think we'd need a lot of them. Emergency tasks could be automated (i.e. the equivalent of sprinkler systems, which would have to be modified for microgravity). This would still need a lot of humans, so I'd guess about 25 emergency workers. The crew would also be trained to handle emergencies.
* **Normal hotel workers.** A concierge or two, [managers](https://en.wikipedia.org/wiki/Hotel_manager), lobby people, cooks (which many hotels have), cleaners, etc. I would think these would be in the range of a few hundred - we'll go with 200. On a space station, they'd need to know a range of trades to reduce the number of people needed.
With 500 rooms (yikes!) meaning perhaps 1000 people, and an average stay of maybe one week, you could swap out 1000 per week. Let's assume the shuttle to the station can fit 25 people. That's 40 flights a week (about 6 per day). Assuming that the pilots only make one trip a day (i.e. a two-day round trip), that means they can make 3.5 flights per week. So you need 11 crews, at least, plus a backup one or two - 77 total people. 6 shuttles in the station mean you need five technicians in each bay, so perhaps 30 total. Let's do the addition: $$77 + 10 + 30 + 25 + 25 + 200 = 367$$ So you'd need 367 people.
[Answer]
**If you wanted to build a space hotel, say with 500 rooms, how many people (excluding hotel guests) would have to be permanently on that space station?**
For a solitary exclusive luxury hotel:
* **1** Hotel Manager
* **3** Assistant Hotel Managers (24 hrs, overall manager when hotel manager isn't there.)
* **1** Marketing and Advertising
* **2** Accountants
* **1** Purchaser
* **1** Event Planner
* **3** Supervisor of Guest Services (24 hrs, basically assistant manager for housekeeping, etc.)
* **1** Front Desk Supervisor
* **3** Front Desk Clerks/Receptionists (24 hrs, port activity sets number with low end being 3 and busy-bank activity levels being 9)
* **3** Porters/Bellhops (assuming checking in and giving a rundown of services takes 15 minutes you have port activity per hour divided by 4 with a minimum of 3 (which we take because we're at 500 rooms with 7 day stays))
* **1** Head Concierge
* **6** Concierges (24 hrs desk service plus 1 helper on-hand for longer requests)
* **1** Housekeeping Supervisor
* **3** Phone Guest Services (24 hrs, calling for room service, etc. others will probably do this job as well but I expect you have at least 1 dedicated phone person at every hour to prevent a busy line.)
* **19** Housekeepers (do 22-30 rooms a shift so: Rooms/26)
* **1** Restaurant Manager
* **3** Hosts/Ushers/Maitre de (24 hrs)
* **1** Kitchen Manager
* **1** Executive/Head Chef (meal planning and management)
* **3** Sous Chefs (24 hrs)
* **~18** Line Cooks (grill, sauté, fryer, expo, pantry, pastry, etc.)
* **~3** Prep Cooks
* **3** Dishwashers (24 hrs, 1 per restaurant)
* **43** Servers/Waiter/Waitress (assuming everyone wants breakfast and subtracting phone service staff since a good amount of orders will be over the phone, you'll need almost the same amount for dinner and less for lunch)
+ Calculations:
(breakfast from 6-10 assuming a normal distribution with 4.4% ordering breakfast at 6 or before (-2σ) then 8 should be our peak with an order time taking an average of 5 minutes from order to table (since each standard deviation is an hour then we go from -(5/60)/2 to (5/60)/2 standard deviations [in our formula](http://www.wolframalpha.com/input/?i=1%2F2%281%2Berf[%28%288%2B%285%2F60%29%2F2%29-8%29%2Fsqrt%282%29]%29+-+1%2F2%281%2Berf[%28%288-%285%2F60%29%2F2%29-8%29%2Fsqrt%282%29]%29) to get 3.3% of our hotel for our peak rush
.033\*500 for breakfast we'll round up to get a whole person, dinner down because we need less, and we'll take an arbitrary 80% of dinner for lunch for 17+16+13 - 3 phone people)
* **3** Room Service (to cover the phone people we subtract from the Servers, larger square footage may require more. Will probably steal people from other areas.)
* **13** Medical (There are 14 surgical specialties, 1 anesthesia technician, 1 dentist, 3 general practitioners, 1 Internist (Doctor of Internal Medicine), and 3 Nurses. I'll assume we only have 1 neurosurgeon and 3 general for the 24 hr shift cycle.)
* **3** Security (I couldn't find an equation that worked for all cities but all the ones I did look at suggested <1 security guard for less than 1500 people no matter the crime rate or population density, so we fill all the shifts and get 3. My own town has no police and 1 contracted so it's possible you only have 1 security officer and he's just on call.)
* **3** Fire (probably the same as security for arson and medic response. Will appear less as more are volunteers.)
* **3** Port Technician:
+ Mechanics get paid by the hour and each job has a book time that they get paid a fee for. Claims made on crashes average [2,950](http://www.rmiia.org/auto/traffic_safety/Cost_of_crashes.asp) dollars in the US and make up 90% of mechanic work. The other 10% has a large range in time so we'll ignore it for now (routine maintenance to complete overhauls). Mechanics make a median [36,610 per year @ 17.60 per hour](http://www.bls.gov/ooh/installation-maintenance-and-repair/automotive-service-technicians-and-mechanics.htm) so we have about 2,080 hrs of work per year which is an 8 hour day. There's [~5,615,000 police reported crashes a year](http://www-nrd.nhtsa.dot.gov/Pubs/812006.pdf) and if we assume they all file a claim (some won't, but some will file that weren't reported which should make up for that) then @ 127-[253 million cars](http://www.latimes.com/business/autos/la-fi-hy-ihs-automotive-average-age-car-20140609-story.html) you get .022 crashes/car which takes up 90% so add in an extra 0.0024. At max hours per vehicle you see 0.36666 hours per car which takes up [70%](http://www.government-fleet.com/channel/operations/article/story/2009/11/calculating-mechanic-staffing-requirements.aspx) of the work load so 0.5238 hrs per car and since construction vehicles take 5x that we'll multiply by an arbitrary 15 instead to get 7.86 hrs per starship, so for every starship that visits yearly we could expect to get 8 hrs of work a year. If we have a dedicated ship for each room you have 500 ships (+1 for supplies). That gives us enough work hours for 2 mechanics. If customers fly in on their own ship for a 7 day vacation and each just happens to have a problem you can have (365÷7×500+1)×8÷2,080 = 100 mechanics. If ships are unreliable and always come in with problems you can have 26,365 workers). **tl;dr: low is 2, unlikely is 100, crapsack is 26,365**
* **18** Space Station Technicians (24 hrs, 2 technicians for every 29,000 ft² of basic machinery plus they're critical so **x3**)
* **1** Specialty Technician (plasma engineer, etc. one each)
For a minimum of:
$$ 164 $$
Some numbers are guesstimates, some are researched.
[Answer]
Rather than trying to calculate the answer to this, I'm going to argue by analogy.
About 375.
I would suggest that a space station would be approximately equivalent to a cruise ship - specifically, all the crew listed in the question have equivalents on a cruise ship. Hotel staff, shops, emergency services, telephone exchange, restaurants.
>
> Crew is usually hired on three to eleven month contracts which may
> then be renewed as mutually agreed, which is based upon service
> ratings from passengers as well as the cyclical nature of the cruise
> line operator. Most staff work 77 hour work weeks for 10 months
> continuously followed by 2 months of vacation.
> - <https://en.wikipedia.org/wiki/Cruise_ship#Crew>
>
>
>
This would also, I imagine, be comparable to a space station (depending on technology).
Doing some digging around, the R class of the Princess Cruises line can carry 680 passengers, the right order of magnitude, and have 373 crew ( <https://en.wikipedia.org/wiki/Princess_Cruises#R_Class> )
I expect there would be a few extra jobs, mostly technical; conversely, with no day/night cycle, there would be no "peak" times (room cleaning? breakfast and dinner? evening shows? embarking/disembarking?) - this would reduce the need for service crew somewhat.
I wouldn't count shuttle staff (bringing customers, staff, supplies to/from hotel) as being part of the "crew of the hotel", but it depends what you need this answer for.
The passenger:crew ration of the R class is 1.8:1, larger ships seem to have about 2.2:1 (source: <https://en.wikipedia.org/wiki/MS_Allure_of_the_Seas> )
[Answer]
It seems that most answers are taking for granted a couple of new jobs that a space station requires:
Air supply: If this runs out, everybody dies. There has to be a large staff watching this like a hawk. 24-7.
Heating/Cooling: Outside temperatures range from well about 100 degrees to -100. This can never get to the guests. Designs would need to include monitoring and fast response servicing.
Fire department: Must be increased massively, as if a fire gets out of control everyone dies.
Evacuation: You can't just have everyone go out front on a fire drill. You need lifeboats and pilots and techs for them.
[Answer]
Zero.
You don't need a human staff at all. It's always safe and error-free thing to put computers and robots in-charge (think Google self-driving car; most of the things can be automated). Humans can always assist the space hotel remotely.
And, where human intelligence is really required, just remove that requirement by tightening the protocols. It's always good to have strong protocols in a sensitive place like space.
And, in the end, if it doesn't feel right, put few highly skilled human engineers in case a maintenance bot fails or something goes critical beyond capabilities of the machine.
] |
[Question]
[
In relation to [this question](https://worldbuilding.stackexchange.com/questions/463/what-is-the-limiting-factor-for-a-plants-growth), what would plants do if they were taken from their environment to another gravity level, in particular zero g.
For example would the daisy manage to grow higher because it doesn't need to make so much effort to hold its head up? Would its form change?
What happens to a tree if it gets planted in an low or zero g environment? What would happen if it was already established in normal g and then sent to space?
Or in short:
**What factors of a plant growing are affected by low gravity?**
**EDIT:** Liath did point out the breeding of plants in low or micro gravity, but my question was also about: **How would a full grown plant react?** for example a tree in the middle of its life span. If it is ripped out of its planet and put on a generation ship to regenerate the air.
[Answer]
There have actually been quite a few [studies](http://science.howstuffworks.com/space-farming2.htm) around what happens to [plants in space](http://news.nationalgeographic.com/news/2012/121207-plants-grow-space-station-science/).
Interestingly one of the biggest problems has been ensuring the plants receive enough light (most likely not an issue for fungus). Also plants do breath so they need access to oxygen (as well as the CO2 they use for photosynthesis).
Rather than growing to an uncontrolled size plants seem to suffer from the lack of gravity and often need some additional help. Water distribution in the soil is different in space (it doesn't all sink to the bottom) so less can be absorbed by the roots.
There is no atmosphere to protect them from the increased radiation of outer space. Climbing plants (such as vines) typically adapt by changing their twists per metre. There are loads more fascinating examples in [this article](http://www.slate.com/blogs/quora/2014/09/20/how_do_plants_grow_aboard_the_international_space_station.html).
**TLDR**
Rather than growing to huge sizes because gravity no longer restricts them other factors such as light, oxygen and water consumption become difficult and tend to hamper plant growth.
[Answer]
From a circulatory point of view, fluids in plants move through capillarity and evaporation. Low gravity would not change significantly this and most plants should deal with it as long as the substrate has enough pressure to allow water absorption. Higher gravity will reduce the maximum height achievable by plants, with very strong gravity potentially completely breaking the process and killing the plant.
From a structure point of view, low gravity will change the overall shape of the plant leading to sub-optimal light absorption (leaves overlapping each other, etc.), but that should not be a big deal. However, high gravity will have a more significant effect. Plants are adapted to earth gravity : resistance beyond dealing with strong winds is an unnecessary waste of resources. Some extra g may be ok, but very high gravity will exceed structural resistance and break parts of most plants or deform them. Some shapes or basic structures may resist better (round-shaped cactus, moss...).
On the overall : high-g is not ok for plants, but low-g should be a sustainable environment for them. Very-low or zero-g will impact the growth of the plant significantly after you put them there, however.
] |
[Question]
[
Related to: [How would rudder protection against water elementals affect ship's performance](https://worldbuilding.stackexchange.com/q/206/95) and [How would sails from a fireproof material affect ship's performance?](https://worldbuilding.stackexchange.com/q/263/95)
Most real-world ships from say 14th to 17th century had no roof over their board. Was it just because it wasn't needed and that extra wood for it would slightly increase the cost of the ship, or were there some better reasons against the roofs?
I assume magical warfare with fireballs and even such spells as acid rain or rain of fire, so wooden roof with some extra protection on its top seems natural. The roof could also protect (at least partially) against shots from ballistae and mangonels.
Also, would it be possible to combine some boarding device (somewhat similar to Roman [corvus](http://en.wikipedia.org/wiki/Corvus_(boarding_device)), but shorter and not solidly fixed to the ship, and used only on bigger ships, so that they wouldn't affect the ship's stability so much) with a roof (or its part) consisting of wooden plates with some protective layer on their top? The roof plates could be lifted from a tower on a mast. Off course, opening part of the roof would decrease its protective value, at least temporarily. But is there any other drawback of this?
[Answer]
A roof over the top of the ship would have a number of negative consequences, the severity of each would vary:
* Restricted visibility - crew members would not be able to see everything else that's happening, particularly people on deck seeing the sails and rigging.
* Rigging would need to be rooted around the roof.
* The roof would make the ship more top heavy, and would also catch a lot of wind. This would combine to make the ship more unstable. In particular if the ship started to tip then sails naturally shed wind and cause the ship to right. A roof though would actually catch more wind at certain angles.
* Increased weight. The weight of the roof would not be insignificant.
There were actually some ships in the real world built along these lines though, for example the Korean [Turtle Ship](http://en.wikipedia.org/wiki/Turtle_ship).
[Answer]
In a combat situation as described, there are a few more effects the roof would have than listed in the other answer.
1. Reduced ability to access rigging/sails. If they fire a stone through your asbestos sail you will have more difficultly accessing it unless planned accordingly.
2. Can't run away as easily. (speed of boat)
3. Less flexibility in retaliation. You can't fire spells or arrows through the roof.
4. harder for them to board your ship
5. Lower troop moral, can't hang out on board before battles
6. Higher troop moral, percieved protection from visibly impressive attacks
Basically, I find myself wondering what is the benefit provided by the roof compared to situating the canons and ports on the lower levels of the ship?
] |
[Question]
[
Aliens show up in a generation ship. They don't particularly care about living on a planet specifically, and they don't have any interest in conquering Earth for our land or our water or our biodiversity or anything like that. After all, they've been living in space for generations and they would be perfectly happy to just hang out in the asteroid belt and build more space colonies.
Except... they need uranium and thorium, which aren't particularly common elements, but are concentrated by geological processes.
So: what are the best places to go mining for those things? Are they inevitably going to end up interacting with us on Earth, or can we just be annoyed at them from afar as they settle in around Mars, Venus, or Mercury?
[Answer]
## They probably will come to earth, after some detours
Let's first start off by narrowing our search window. We know heavy elements tend to concentrate in inner orbits, so we can exclude the gas giants(and Kuiper belt) on that alone.
So how do the rocky planets stack up?
From what we can tell¹, Earth far outweighs the rest of the solar system in terms of uranium/thorium concentrations, with an average of uranium 2.8 PPM (parts per million), while uranium ore deposits we currently extract have over 1000 PPM of uranium[[1]]. Thorium is much more common, in the neighborhood of 56 parts per million. However, it's insoluble, so it doesn't concentrate as well.
Venus *could* have similar concentrations[S], but uhh... good luck getting it. Unless the aliens screw up massively and anger us humans, mining on earth will be much more efficient than on Venus. Y'know, pressure and acid rain.
The moon has a region that may reach 2.1 PPM, but it's only a small portion, and again, not exactly confident in these measurements. Barely worth it. Next.
Mars is estimated to have around 1 and 5 PPM of uranium and thorium, respectively, but we aren't exactly confident in this measurement.
Mercury doesn't seem to have much; the MESSENGER probe only detected around 100 parts per *billion*(.1 PPM). Thorium was slightly more common at around 200 parts billion, which is peanuts.
Lastly, the asteroid belt. It might be 8 PPB, or lower. We don't really know, and as JBH said, that's a shame. NASA should really be studying the composition of the asteroid belt harder.
So yes, Earth has the highest concentrations of fissile material-**but is it the most efficient option?**
* Again, Venus is right out the window. It's simply too hostile to be efficient.
* Mercury is a joke when it comes to contents
* The same applies to the asteroid belt
* Mars has decent concentrations, and lower gravity (1/3 G)
* The Moon is close to a large deposit(earth), and has much lower gravity (1/8 G)
So we have two major alternatives: **Mars and the Moon**
Mars would likely be a major operation. It has a decent enough concentration of uranium, and it's much easier to move into orbit than what's here on earth. There's also the added benefit of not having to spend a lot of resources dealing with humans(either destroying them, or trading with them).
Now, if their demand is great enough, Earth is the next target. It's got infrastructure already in place for the extraction and refinery of uranium, so that's a lot less in startup costs, and there's probably more of it here, too.
And the moon? That would be extracted on the way to Earth, as a forward operating base of sorts. Gravity is likely weak enough to make extraction profitable.
[Answer]
It depends on the engine technology of the aliens.
If their engines are relatively weak, such that gravity wells and atmospheres are worth considering, Mars and the asteroid belt are their best bets. Escaping gravity wells can be a huge cost, especially when we're talking about moving something really heavy that you need in relatively large amounts, like fuel.
If their engines are strong and gravity wells and atmospheres are negligible issues, mining is instead the main cost. Asteroids again will likely be decent choices, but geologic processes may concentrate fissile fuels in relatively rich deposits on planets. Or they could just trade with the Earthlings who already dig up mountains of the stuff, and who would pay top dollar even for alien trash.
[Answer]
## Asteroid Belt
Asteroids are the ideal place to mine practically any metal because they do not form by the rule of averages like planets do. Planets form by colliding a bunch of different asteroids and comets made of different stuff until you get a big ball of everything all mashed and mixed together, and only through tectonic and whether patterns do you get any sort of concentrations of ores... but asteroids are WAY better than this because most asteroids will be formed primarily from the remains of 1 stellar event instead of many.
Because different stellar events, produce different elements, it means that most asteroids will not contain any uranium/thorium to speak of. The thing is that most of the non-hydrogen/helium mass in the solar system comes from dying stars and white dwarf supernovas; so, here on earth we have to separate out massive amounts of oxygen, silicon, carbon, iron, etc. But, an asteroid formed from a very rare neutron star collision, will have very little amounts of these elements, and hundreds if not thousands of times as much uranium/thorium as you will find anywhere on Earth.
So, instead of having to melt thousands of tons of ore over and over again to try to get a few kg of pure uranium on Earth, the aliens could scan thousands of asteroids for radioactive signatures, and mine only those formed from neutron star remnants.
[](https://i.stack.imgur.com/tjIQb.png)
[Answer]
I am not sure what form of difinitive answer you are after, as their is currently little information on the mineral composition of the planets other than earth. The best that can be offered is conjecture.
If it helps, there is evidence that Mars at one time had experienced spontaneous [natural nuclear explosins](https://www.hou.usra.edu/meetings/lpsc2015/pdf/2660.pdf).
>
> Previously, it had been hypothesized that Mars had been the location
> of large natural nuclear reactors[1,2], as are known to have occurred
> on Earth [3] This hypothesis was prompted by evidence of a large
> nuclear energy release in Mars past, and was considered the simplest
> hypothesis to explain the available data. Evidence of large scale
> nuclear activity on Mars comes from a variety of sources. It has been
> a long standing paradox that uranium, thorium and potassium, appear
> hyper-abundant on Mars surface when compared to Mars meteorites, which
> are believed to sample subsurface rocks. [4] This suggested a thin
> debris layer on the surface of Mars, enriched in Th, K and U , and
> dispersed by some impact or explosion. Thorium and radioactive
> potassium appear concentrated in the northern Mare Acidalium in the
> region of approximately 50 W 55N with a smaller concentration in
> Utopia Planum centered at approximately 90E and 55N with an additional
> small concentration at the approximate antipode of the Acidalium hot
> spot ( see Figure 1and 2). This pattern suggested a massive explosion,
> such as the explosive disassembly of a large natural nuclear reactor,
> producing a global debris pattern , with a shock wave wrapping around
> the planet and colliding with itself at the approximate antipode.
>
>
>
Just how much uranium do your aliens require? The evidence seems to indicate that there should be ample supplies on Mars.
[Answer]
If they are technologically advanced enough probably star-lifting. Our star has the majority of matter in solar system. It is just a matter of filtering that matter to get the elements you need. And it is quite fortunately that you get practically limitless amount of energy in situ to fuel that process. That also put their colonies closer to the star which only make sense. Why would you settle in the asteroid field/Mars instead near the sun, where you get all the energy you would need?
Well, that is assuming aliens arrived either in large numbers, or they plan to raise their numbers. If they are small in number (1 billion of aliens IS a small number) they could just trade with Earth.
But the real question would be why do they need fission fuel? Using solar power is way more efficient, even for ships. You can use star-powered lasers to accelerate colony ships leaving the solar system - so there is little need for fission/fussion. Only reason for usage of fission I can think of is that they didn't control their star (so, they are refugees). But that explain the usage before comming here, where they could easily take control of the sun.
] |
[Question]
[
There are lots of different creatures that are loosely based on wolves. The most prominent one is probably the Werewolf, a mix of a human and a wolf. But there are also others, such as Dire Wolves or Wargs.
The problem is **How much territory of which kind would I need for a pack of Werewolves/Wargs/Dire Wolves/...?**
I am looking for a way to calculate the territorial needs of different packs by comparing each individual to an average gray wolf and then looking at the food and space requirements of the new numbers.
For example, suppose I am using the following numbers for my versions of these creatures:
* An adult Werewolf, when compared to an adult gray wolf:
+ eats twice as much
+ moves twice as fast
This is a simple version at first glance. Every Werewolf is equal to two gray wolves because it's two times as fast and can, therefore, cross two times the distance a gray wolf can while at the same time needing two times as much food. Catching the prey should be a bit easier because it's faster, so I will ignore this fact. Looking at Wikipedia should show me the average gray wolf pack consists of x members, so it should be possible use x/2 Werewolves with the same territory... Right?
Taking a look at [Wikipedia](https://en.wikipedia.org/wiki/Gray_wolf):
>
> Territory size depends largely on the amount of prey available
>
>
>
and
>
> The core of their territory is on average 35 km2 (14 sq mi), in which they spend 50% of their time.
>
>
>
but also
>
> The smallest territory on record [...] occupied an estimated 33 km2 (13 sq mi), while the largest was [...] encompassing a 6,272 km2 (2,422 sq mi) area.
>
>
>
That's quite a big difference... And the problem is
>
> The gray wolf is a habitat generalist, and can occur in deserts, grasslands, forests and arctic tundras.
>
>
>
It seems to me that I could just use the core and postulate that this is probably in a forest or grassland as the average habitat, but I am not sure.
>
> The average pack consists of a family of 5–11 animals [...], or sometimes two or three such families, with exceptionally large packs consisting of up to 42 wolves being known.
>
>
>
Again, this doesn't really give me a lot of information as there is a lot of variance here. But basically, I think I could just use a territory of 35 km² and probably 3 to 6 Werewolves (one to 3 of them being juveniles and 1 yearling for the largest pack). But what if I wanted to have 12 Werewolves in my pack? Could I just scale that up and say that it's probably somewhere between 70 km² and 140 km² of forest land? Or would prey not be able to recover from, well, being preyed on? My prey needs some time to have offspring that will be able to feed my pack, so I can't just kill all of them.
All of this seems awfully rough, even by my standards (and I am handwaving that Werewolves can exist). I'd prefer to have a better grasp on the subject to not feel like I am just pulling numbers out of thin air. (Rough estimates are okay, but it should be better than "probably more than 10 km² and there are probably more than 2 Werewolves".)
But what if I say that my Werewolf does not move twice as fast, but instead is only equally fast?
Now, this Werewolf can't move so fast and my pack needs to find two times the amount of prey in the same area that gray wolves have at their disposal. Would this change anything at my calculation, for example, because there is just not enough prey in this region? I have no idea how to get this information.
For simplicities sake, I only want to look at packs consisting of one species.
Imagine I postulate that **Werewolves are equally fast but eat three times as much as gray wolves and my pack consists of 15 Werewolves in a middle European forest**:
**How can I calculate the territorial needs of my pack?**
I'd prefer answers to give resources where I can look up the relevant information of territory, such as "amount of prey animals per km²" and information about what this means for calculating the needs for different packs in different territories, for example by mentioning limiting factors such as "time the wolve-like creatures can stay in one place" or "amount of water that can be found close enough" (`The den is usually constructed not more than 500 m (550 yd) away from a water source`). The bolded question is supposed to be an example calculation so that it's easier to understand and to make this question less broad. If there is information missing from the physiology it can be inferred from gray wolves.
**A good answer will give me the ability to calculate the territorial needs for differently sized packs of different wolf-like species in different climate regions, while exemplarily answering the bolded example.**
[Answer]
Climax forest is not the best habitat for wolves, because they're carnivores and it's not the best habitat for their prey. Most prey species, and especially deer and other medium sized solo grazers, prefer "edge habitat", areas where they can access the cover of forest and the good grazing of grasslands. Woodlands on the edge of grasslands with an annual burn cycle, natural or artificial are often the best habitat for these kinds of animal assemblages.
To work out the food requirements of a given lupine species physical size is probably more important than anything else since all mammals have a minimum calorific requirement per kg of body weight, as they get larger this requirement tends to go down so it would be advantageous to compare your species to existing mammals on a mass basis to determine their overall metabolic requirements. Bear in mind, no pun intended, that carnivores need a bit more food due to the fact that they run down prey, thus using more energy to get their calories than herbivores.
There's a bunch of stuff about prey density and hunting success rates etc... that goes into working out the figure but the next important component boil's down to the average sustainable daily calorie density of the space the wolf pack is in. As an example a pack might be able to harvest an average of ten thousand food calories per acre per day year round, (this is a completely arbitrary number purely as an example). This number will change depending on the speed of the hunter relative to the prey, the number of hunters, their ability to co-ordinate, prey reproduction, prey migration and many many other ecological factors. Here's some numbers that may or may not help:
* According to [this list](http://www.discoverwildlife.com/animals/hunting-success-rates-how-predators-compare) depending on location Grey wolves succeed in their hunts something between 5 and 20% of the time, whether werewolves would be this successful is open for debate, one could argue that human thinking helps with hunting or that the civilised instincts of humans might blunt the hunting drive of the pack.
* Having done some irritatingly unsuccessful research it looks, from [this data](https://www.researchgate.net/figure/Estimated-biomass-density-kg-km-2-for-13-large-herbivore-species-in-Lake-Manyara_fig5_321702836?_sg=OpIz4wnSBO8dpG21SniWAM7gmNY75FUguiUV7lzEf-ZZMeFw19RQdFiQPrr_P8VTaImBaZvrfI6tXjNhOysTIA), like reasonably wild grasslands have something on the order of 16,000kgkm-2 of meat on the hoof available to hunting carnivores.
* Wolves [apparently](http://shan.moonbase.net/writings/wolves-man-and-truth/6-the-adult-wolf-food-consumption-digestion-and-waste) need about 1 to 1.5kg of meat per pack member per day.
* According to episode one of the documentary [Wild Mississippi](https://www.imdb.com/title/tt2835484/?ref_=ttep_ep1) 8-10 wolves need at least one substantial kill, like an adult deer, every 2 days to get through the winter.
I'd love to run the numbers for you but you'll need to work out some prey species percentages to divide that meat mass into before that's possible so the size distribution of kills can be estimated.
To work out the minimum hunting territory of a pack you need to multiply the subsistence calorie rate for an individual by the number of individuals in the pack and divide that total by the calorie rate of the land they're on.
That gives you an estimate of their *minimum* range, in reality they're likely to have a much larger range. If they retain a human perspective they'll want resource security and thus probably take and hold *as much land as possible*, in this scenario speed and senses are of the essence; the deciding factor on territory size is being able to detect and intercept intruders not the direct, immediate, needs of the pack.
I'm not sure where you'd get the exact numbers you'll need to use to work this out I'm afraid but hopefully the above frameworks are of some use to you.
[Answer]
It may be worth distinguishing between a home range for these werewolves, and a territory. The former is typically defined as the "habitually used area", whereas the latter is an area which is actively defended against other individuals/groups of the same species. The two may be the same, or the territory only part of the range.
Mitani & Rodman (1979) proposed a "Defensibility index" which described the relationship between the distance traveled in a day, and the area of the home range (<https://link.springer.com/article/10.1007/BF00184423> for a more recent assessment of this study). This was for non-human primates, but the essence is probably the same - long day ranges relative to home range area are necessary for territoriality.
Given that home ranges tend to scale according to food supply, if the prey is widely scattered, then home ranges will be large. If the prey are nomadic, so much the worse for territoriality.
Territoriality is only going to happen if there is some reason that the werewolves need to defend their home range - and this is driven, in part, by the population density. If competitor packs are widely dispersed, then territoriality may be uneconomical (cost more in effort than saved in protecting food sources from other packs); alternatively, if packs encounter one another regularly (very high population density), then again the costs of defence would be too high - instead, we would expect packs to defend individual kills, rather than a foraging area (this would also happen if prey are clumped, and clumps of prey are dispersed relative to one another). So making some decision about how many werewolves, and how many packs these are divided into, will highlight whether they are likely to be territorial.
The quoted wikipedia article appears not to make this distinction. There is no way a pack of grey wolves is defending (against other packs) an area in the region of 6,272 km²! As your question states the need to work out the requirements of different packs, I am assuming that these packs will interact, but whether they are "territorial" or "kill-defenders" will change aspects of their behaviour.
If prey density is heterogeneous, then you could have a situation with some resident, territorial packs (particularly if there are patches of fast-renewing resources (small bodied, fast reproducing prey) within these territories) and other packs that are not territorial but either follow migrating prey, or search over large non-defended areas. Werewolves subsisting on ground-hogs isn't particularly glamorous, but you'll have to solve the food-supply problem if you want packs of werewolves defending discrete areas.
[Answer]
It is useful to start with a food pyramid. Here are some data points:
[How much do wolves eat?](http://www.wolf.org/wolf-info/basic-wolf-info/wolf-faqs/#16)
>
> 15. What do wolves eat?
>
>
> Gray wolves prey primarily on large, hoofed mammals such as
> white-tailed deer, mule deer, moose, elk, caribou, bison, Dall sheep,
> musk oxen, and mountain goat. Medium sized mammals, such as beaver and
> snowshoe hare, can be an important secondary food source. Occasional
> wolves will prey on birds or small mammals.
>
>
> Red wolves primarily prey on white-tailed deer, raccoons, rabbits and
> rodents.
>
>
> 16. How much do wolves eat?
>
>
> Gray wolves can survive on about 2 1/2 pounds of food per wolf per
> day, but they require about 5 pounds per wolf per day to reproduce
> successfully. The most a gray wolf can eat in one sitting is about
> 22.5 pounds.
>
>
> Red wolves eat an average of 5 pounds of food per day, but have been
> known to eat up to 12 pounds in one sitting.
>
>
> 17. How many prey do gray wolves kill per year?
>
>
> In Minnesota, wolves kill the average equivalent of 15 to 20
> adult-sized deer per wolf per year. Given the 1997-98 estimate of
> 2,450 wolves in Minnesota, that would equal about 36,750 to 49,000
> deer killed by wolves. In comparison, from 1995-1999 hunters killed
> between 32,300 to 78,200 deer each year in Minnesota's wolf range. In
> addition, several thousand deer are killed during collisions with
> vehicles each year.
>
>
> The deer population of Minnesota is roughly 800,000, as of 1997. Thus,
> it takes roughly 200 deer to support one gray wolf, and given that
> they tend to operate in packs of 5-6 wolves, it takes roughly
> 1,000-1,200 deer to support a wolf pack. Multiple wolf packs are
> necessary to maintain a viable gene pool.
>
>
>
For reference [Minnesota](https://en.wikipedia.org/wiki/Minnesota) has 86,936 square miles, much of it small glacial lakes interspersed with forests and also some mostly non-natural grassy plains in a temperate to quite cool climate.
[How much do mountain lion's eat?](https://washparkprophet.blogspot.com/2007/09/lions-wolves-and-horses.html) (link is to a quote from an original source whose link has gone bad).
Mountain lions eat primarily deer throughout their range. If there are no deer, there are few lions. Secondary prey can include bighorn, javelina, and even porcupines. A puma generally kills one deer per week. The lion caches the carcass under a shrub or buries it under leaves, and may return to feed nightly for several days. Pumas in the desert kill more often then those in the mountain woodlands, because the cached carcasses decay faster in the hot desert.
If the kill to total population ratio of deer is similar for mountain lions and wolves, then it takes about 500 deer to support a single mountain lion. They live in solitary environments most of the time, but it still takes many mountain lions to support a viable gene pool.
**Horses as food**
One of the main food sources for human hunter-gatherers and large predators on the Pontic-Caspian steppe prior to the Bronze Age was horses.
Of course, a horse is much larger than a deer. Adult horses are 850-2000 pounds. An adult white tailed deer usually weighs 90-220 pounds, although they can get to be up to 350 pounds. Thus, a horse has about ten times as much meat as a deer.
Solitary mountain lions are poor horse predators. A dead horse doesn't last long in the wild, and a mountain lion can only eat so much at once. Most of the meat on a dead horse would be wasted by a single mountain lion whose usual weekly meal is a deer.
On the other hand, a pack of twenty wolves that took down 40 horses a year, could probably eat a comparable share of the meat from the horses to what they take from deer prey. This suggests that a herd of about 400 horses could support a single large wolf pack.
Moreover, in reality, the wolves would probably eat some prey other than horses, so a large wolf pack could probably do well managing a somewhat smaller herd of horses, if it also had other prey available.
**Smaller Cats**
About 80% of songbirds are killed by predators, and that in particular 47% of songbirds are killed by cats (about equal numbers of feral and domesticated cats) (hard copy newspaper clipping source).
**Human Hunter-Gatherers**
>
> The lowest recorded hunter gatherer density of 2 individuals per 100
> $km^2$ reported for the !Kung (Kelly 1995) and the density of 3
> individuals per 100 $km^2$ estimated for Middle Paleolithic people
> (Hassan 1981).
>
>
>
-Source Per Sjödin, Agnès E Sjöstrand, Mattias Jakobsson and Michael G B Blum, "Resequencing data provide no evidence for a human bottleneck in Africa during the penultimate glacial period" Mol Biol Evol (2012) doi: 10.1093/molbev/mss061.
There are about 2000 Lebbo hunter-gatherers in Southeast Asia, who occupy on the order of 2500 $km^2$ of territory, which is about 80 per 100 $km^2$ in this much more abundant environment.
Population density (and hence a werewolf's territory requirement) is very much a function of vegetation abundance and climate.
**Neanderthals and Homo Erectus**
The best estimates of peak Neanderthal population are about 70,000 (census population, not effective population). Their geographic range is shown [here](http://www.newworldencyclopedia.org/entry/Neanderthal).
Neanderthals were outnumbered 10:1 by the modern human hunter-gatherers that immediately followed them in residing at the same locations in Europe where adjacent layers are present.
I've estimated *Homo Erectus* populations in Eurasia before and concluded that the size of the geographic range of Homo Erectus in Asia (and by Asia in this context I mean to the east of India) was on the same order of magnitude as the size of the geographic range of the Neanderthals, but the census population size of Homo Erectus may have been on the order of 7,000 to 35,000.
[Answer]
I am reading into your quotes that though the core area for wolves is almost never under 35 km$^2$, it might be much larger. Let's take those 35 km$^2$. Now, your, say, direwolves move $x$ times faster. Imagine they move randomly. They would be able to cover $x$ times as much in any direction, this translates into $x^2$ larger territory.
As for werevolves needing more food: you might need to check activity or majorly bump their strength compared to a "normal" wolf. It might be that poor licantropes need to hunt all the time. And I am unsure if wolves do not hunt/search for food the majority of time anyway. If so, werewolves starve and die out. The only saver is: they are stronger than wolves. Than they can attack larger prey. Still, the question of sustainability remains.
[Answer]
There are some detailed studies about wolves' territorial size and behaviour from Poland which is well representative of a European forest setting, cf. [Habitat variables associated with wolf (Canis lupus) distribution and abundance](http://www.zbs.bialowieza.pl/g2/pdf/1421.pdf) and [Territory size of wolves (Canis lupus) linking local and Holarctic-scale patterns](http://www.velkeselmy.cz/knihovna/b/rok2007/Jedrzejewski_et_al_2007_Territory_size_of_wolves_Canis_lupus-linking_local_(Bialowieza_Primeval_Forest,_Poland)_and_Holarctic-scale_patterns.pdf).
On the one hand, they found that the size of **territory** is **independent of pack size** for 3-8 wolves averaging **201 km²** with **core areas** ranging from **14 to 78 km²**.
>
> Home ranges of individual wolves from the same pack varied with season as well as the age, sex, and reproductive status of the wolf. ... latitude and prey biomass were essential factors shaping the biogeographic variation in wolf territory size. Territories increased with latitude and declined with growing biomass of prey.
>
>
>
In principal, the further north the pack lives the more likely it has to follow its nomadic prey. The further south and less likely the prey migrates, the smaller the territory hast to be. They also found that wolves are less likely to attack livestock when living in dense forest areas as compared with ares with little forestation.
Thus, in a **European forest area** with enough **deer and small prey** to support your pack, your **werewolves** would have little need to wander with their prey and abundant food sources to provide for their pack, controlling **150-200 km² of total territory** and **35 km² of core territory** for upbringing of the pups would suffice for their sustainable support.
] |
[Question]
[
I've discovered some ways of coloring the atmosphere through personal research:
* The atmosphere could be colored by particles or colored gases (as on Mars, unless I'm wrong)
* The atmosphere could be more dense to refract more colors.
* The Sun itself could in fact beam a less "colorful" light.
But I might have misunderstood something. So I ask the question here: On a planet other than Earth, how could the sky be orange but the air **still** be breathable? The more precise the answer the better.
[Answer]
# Rule out some things
If the atmosphere is more dense, then it will refract more. However, light refraction is highly wavelength dependent, so if it refracts more light, the sky will be more blue. The equation can be seen [here](https://en.wikipedia.org/wiki/Rayleigh_scattering#Small_size_parameter_approximation). Different compounds have different scattering cross-sections, so they will scatter different amounts, but all of them will have the same wavelength dependent curve.
Every yellow star will have a blue sky if there are no colored compounds in the air. If the star was redder, then the sky would be shifted to red. If the red, yellow, and blue components to the sky's scattering were equal (a possible result of a red star), then the sky would appear white. If the star were bluer, then the sky would be even bluer or violet.
So basically, we are limited to a tinted sky to get the orange color you want.
# Tinted sky
If your sky was tinted with something orange, then it would be orange. However, there would still be a blue-ish tint to the atmosphere due to reflection from the much more common nitrogen and oxygen. Your best bet is to have planetary cloud cover that is tinted orange; then there is always an orange backdrop at a couple of km altitude.
The list of things that could be in the clouds and are [orange](https://en.wikipedia.org/wiki/Color_of_chemicals#Examples) is not long. For gasses there are basically none, but Nitrogen Dioxide and Bromine might be close. Nitrogen Dioxide clouds are plausible in some sort of biologically dominated system. Bromine sounds pretty dangerous. While it is very reactive and won't normally be found as a bromine gas, sunlight converts organo-bromide compounds to free bromine at the top of the atmosphere, so that gives us a plausible reason for bromine haze. Unfortunately, free bromine destroys the ozone layer, so that is a bummer.
As far as aqueous compounds suspended in water droplets as a method for coloring clouds, we have Dichromate (Cr$\_2$O$\_7^{2-}$) and Cobalt ammine {Co(NH$\_3$)$\_6^{3+}$}. I don't know much about either, but neither one sounds very healthy. Depending on your goals for this planet, you could either have the geological and life cycles on this planet be adapted to having high levels of chromium or cobalt around, or just make your human explorers wear masks.
[Answer]
## You are correct, the sky can be orange using any of those methods.
* **Changing the star:**
"[Sky color of an alien world](https://worldbuilding.stackexchange.com/questions/48867/sky-color-of-an-alien-world)" describes why the sky on a red-dwarf's planet will appear mostly white due to light [scattering](http://hyperphysics.phy-astr.gsu.edu/hbase/atmos/blusky.html). However, subtle changes in the composition of some layers of your atmosphere, or an even redder star, may be able to get around that problem.
* **Changing the atmosphere**: Using Mars as a model, iron oxide (rust) dust may be able to change the color of the atmosphere, among other substances. Other problems may result from this (the dust or substances may settle on the surface) but they should not severely inhibit life's ability to function. Other, non-DNA or non water-based organisms may also be able to withstand phosphorus or sulfur, which some suggest is responsible for the red spot in Jupiter's atmosphere.
[Answer]
**Airborne 'xeno-algae' that use a close analog of carotene absorb the visible light other than orange.**
Here's a way to make the sky look orange, as seen from the surface:
There are several phyla of *xeno-algae* that use a close chemical analog to <https://en.wikipedia.org/wiki/Carotene> as their primary photosynthetic absorber.
These xeno-algae are so successful and well adapted that only the light they cannot absorb (orange) reaches the surface. A side effect is that the stars aren't visible -- even the sun is diffused into a mere 'bright patch' in the sky. Surface-based plants use something like chlorophyll, but the surface energy economy is sparse, compared to earth. Fallen xeno-algae\* is a significant base nutrient in the ecology.
[Answer]
## Cloud of Gas or Particles Around the Sun
I am not well versed in physics or optics, but I think it might be possible for the Earth's atmosphere to remain the same in terms of elements and still be orange if a cloud of gas or particles were to come between the sun and Earth, thereby coloring the sun's light a different color so that when it enters Earth's armosphere, the primar color seen is orange.
Perhaps if the cloud of elements only had an [emission spectrum](https://en.wikipedia.org/wiki/Emission_spectrum) of orange, i.e. around 600 nanometers (nm), then there would be no other colors coming into earth's atmosphere.
[](https://i.stack.imgur.com/xQu7D.gif)
So, if the cloud blocks all the other wavelengths/colors of the visible spectrum of sunlight, then orange would be (I believe) the only color visible.
This scenario would allow you to have an orange atmosphere on modern day earth without changing Earth's atmosphere or the sun, but it would certainly wreak havoc on life on Earth by eleminating all the rest of the wavelengths of visible light.
[Answer]
You can increase the thickness of the atmosphere, so that only the red part of the Sun spectrum is transmitted (like it happens at sunrise/sunset).
[Answer]
Replace the nitrogen in the atmosphere with neon.
Neon is a noble gas, very similar to nitrogen, which is non-reactive in most situations. It also glows red when ionised.
This means that your planet can have a breathable atmosphere, since neon can be inhaled safely, and a mixture of yellow sunlight with a gently glowing red atmosphere should give you the orange sky you're after.
[Answer]
# Dust.
You don't need anything fancy for an orange sky - in fact, many Australians experienced it profoundly in early 2020:
[](https://i.stack.imgur.com/PyPmV.jpg)
Particulates from bushfires - in particular, black carbon and volatile organic compounds - [absorb blue light strongly, re-emitting at lower wavelengths](https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2021JD034984). This produces an orange sky, with the tint variable by minor changes to the spectrum of the star.
The problem is maintaining an orange sky year round - it seems unlikely that you could grow forests at a sufficiently high rate to produce global smoke. Instead, if you make your planet much younger than Earth, volcanic ash could do the job.
*Oh my God, I was wrong // It was Earth, all along!*
] |
[Question]
[
**Take the Earth-Moon system as we know it.** Now, something causes a large rock to be lobbed in the direction of our moon. Exactly how that happens is deliberately left unspecified; it could be everything from an [Earth-Mars war](https://worldbuilding.stackexchange.com/q/8954/29), to a rogue planet passing through the solar system, to something else entirely.
The impact should be sufficiently energetic to cause **the resulting ejecta plume to be clearly visible from Earth** to any creature with human-like vision who happens to be looking Moonward at the time. Let's put the lower limit for this at a plume height of about 10% of the angle subtended by the Moon itself as viewed from Earth at the maximum height where there is still a reasonable particle density. Bonus points to answers taking into account albedo and particle density, but that's not required.
You may choose the time, point and angle of impact arbitrarily, as long as the condition of visibility from Earth is met. (So hitting the back side of the Moon probably won't do it, but you are free to hit the [Apennines](https://en.wikipedia.org/wiki/Hadley%E2%80%93Apennine#Apennine_Front) from the side if you want to.) I'm thinking a direct hit near the terminator near full moon, but if something else works then feel free. **I'm hoping for the spectacular effect, which is why I'm not fixating on any particular location.**
You can assume that humans do nothing to counter the threat of an approaching large space rock; as to why, there is every reason from technical or physical inability to international politics or that humans are long gone from the planet.
With the preliminaries out of the way, two very much related questions:
**What impactor parameters could give this short-term effect?** Impactor mass, velocity (relative to the Moon), strike angle, location if relevant, any other relevant parameters I'm not thinking of?
**Will the Moon likely survive the impact in the medium term?** Said in one other way, is the impact energy comfortably below the [gravitational binding energy of the Moon](https://worldbuilding.stackexchange.com/a/8952/29) (which is approximately $1.24 \times 10^{29}$ J)? You don't need to worry about the effect of the impact on the Moon's orbit.
[Answer]
# How small of a thing can we see on the moon?
Wikipedia has a [list of objects](https://en.wikipedia.org/wiki/Lunar_observation#Naked_eye) on the moon that can be visible with unaided vision. Doing some poking around Astronomy blogs for real-life experience as opposed to calculations, the mode answer seems to be the crater [Tycho](https://en.wikipedia.org/wiki/Tycho_%28crater%29), which is 86 km across.
# What needs to hit the moon to make a 86 km ejecta plume?
First, lets use kinematics to determine how fast the ejecta must be going to get to that height. We can use $$v\_f^2 = v\_i^2 + 2ad$$ where $d$ is 86000 meters, $a$ is the surface gravity of the moon, -1.6 m/s$^2$, and $v\_f$ = 0. I solve this for $v\_i$ = 524 m/s.
Next we can go to a paper to calculate expected ejecta velocity, such as [Richardson, et al., 2007](http://www.jerichardsonjr.info/Papers/jerichardson_ICAR2007.pdf). If you look at Fig 7. of this paper, it shows that ejecta velocity is a logarithmic function of distance from the impactor's edge. Now I could not extract any useful information for what mass density of ejecta would be needed to be visible, and this is getting a bit mathematically complicated anyways, so lets make a simplifying assumption that we need the impact to cause ejecta within 1km of the impact edge to be going 500 m/s.
From equation (12) we can calculate the volume of the transient impact crater as $$V\_g = K\_1\left(\frac{m\_i}{\rho\_t}\right)\left(\frac{ga}{v\_i^2}\right)^\frac{-3\mu}{2+\mu}.$$ The density ratio term from eqn (12) is dropped; we'll assume that the density of the impactor is the same as the moon. For material properties we will use 'soft rock' from Table 1; so $\mu=0.55$, $\rho\_t=2250$, and $K\_1=0.2$. $m\_i$ is the mass of the impactor, and $a$ is its radius. We can express mass in terms of radius as $m\_i = 4/3\pi\rho\_t a^3$. the gravitational force of the moon is $g$ and equals 1.6 m/s$^2$. I resolve this expression as $$V\_g = 1.7a^{2.353}v\_i^{1.29}.$$
Now for follow on equations, we want $R\_g$, radius of the transient impact crater, which is related in equation (11). I solve that backwards for $$R\_g = \left(\frac{3}{\pi}V\_g\right)^{1/3} = 1.18a^{.784}v\_i^{.431}.$$ As a test run of our model so far, if you plug in a 100m object and a 10 km/s impact, you get a 2.3 km transient impact crater. Great!
Now we move on to eqn (28) which gives us ejecta velocity as a function of distance from impactor rim $$v\_e(r) = \frac{\sqrt{2}}{C\_{Tg}}\left(\frac{\mu}{\mu+1}\right)\sqrt{gR\_g}\left(\frac{r}{R\_g}\right)^{-1/\mu}.$$
$C\_{Tg}$ is a proportionality constant equal to 1.6, see discussion around Eqns (15) and (20). I simplify these terms to $$v\_e(r) = .397r^{-1.82}R\_g^{2.32}.$$ We want $v\_e$ to be 500 m/s at a distance of r = 1000 m, so plugging these and $R\_g$ in we can solve for radius and velocity $$2.47\times10^{8}= a^{1.82}v\_i.$$ Obviously, there are infinitely many solutions, but for some reasonable projectiles, if we set radius to be 250 m, then impact speed must be 10.7 km/s. At [maximum comet speed](https://astronomy.stackexchange.com/questions/6384/how-fast-is-a-comet-moving-when-it-crosses-earths-orbit) of about 70 km/s, we get a radius of about 90m.
# Conclusion
To make an ejecta plume visible on the moon's surface to the naked eye, you need to hit it with an object at least 100m if it is moving at the speed of a long term comet, or at least 250m for a glancing blow.
The second question is an obvious yes, those impacts are pretty small on a scale of 'things that have hit the moon', and won't leave a (naked eye) visible impact crater when all is said and done.
[Answer]
A tiny spacecraft, [Lunar Prospector](https://en.wikipedia.org/wiki/Lunar_Prospector#The_Mission_profile) (which is also the subject of [this paranoid answer](https://worldbuilding.stackexchange.com/a/14449/885)) was crashed with the expextation of making a visible plume.
People *do* see “transient phenomina” probably caused by small impacts, and they don't leave marks that can be seen with the most powerful telescopes. So again, *small* insignificant bodies.
For survivability, consider the “rays” on the lunar surface coming from some craters. Clearly was a huge plume to make fallout for hundreds or thousands of miles; but just a crater. No big deal.
You calculated the binding energy… do you know what that *means*? Consider that the impactor will be **falling** from (approximatly) at-rest infinity, the same as used in the binding energy. So, just from the definition of terms it appears that a falling object would need to be as large as the moon in order to impact with the same energy as the moon’s binding energy.
[Answer]
We have an observation of an impact plume that dates from the middle ages. The moon is still there. We do not know the height of the plume, though.
] |
[Question]
[
By that I mean someone who looks roughly like this:
[](https://i.stack.imgur.com/NlDQw.png)
(Note: the name that is increasingly common to associate with this kind of creature is Lamia. [The mythical Lamia](https://en.wikipedia.org/wiki/Lamia) carried around a snake skin, but was not part snake herself)
[Snakes have four different ways of moving around, as described here:](http://animals.howstuffworks.com/snakes/snake3.htm)
[](https://i.stack.imgur.com/Tzwz6.gif)
Let's assume that all the organs for digestion and reproduction are in roughly the same place as they are with humans (don't ask me how they'd use a toilet though). This means that everything below the genetalia is essentially one big mass of muscle. Fun fact: this means that such a snake person has a bigger tail-to-body ratio than an actual snake. This creature will have to hold up its torso, hips and enough of its body so that it is of average human height, and has to propel itself fowards with the rest of its body. Which of these four ways would be the best for a snake person like above?
I am looking for the way that has the best ratio of speed VS the strain put on its body. Would one of the four above options work out? Or would it require another form of movement?
[Answer]
My guess is that it would use all four types of movement, depending on terrain; however, it would likely use serpentine movement the most.
* [Concertina](https://en.wikipedia.org/wiki/Concertina_movement) is an inefficient, though powerful grab-and-push movement; the snake bunches up, then pushes with its tail, shoving itself forward. With a huge, heavy, muscular tail, it makes sense to use this method, especially in areas other than flat ground. It's very useful for traversing in tree or along rough ground, as the area between "grabs" is effectively ignored. However, it is also very slow; snakes using this method rarely move faster than 2% of their length per second.
* [Serpentine motion](https://en.wikipedia.org/wiki/Undulatory_locomotion#Kinematics) uses friction to slide along the ground. For flat ground, it's efficient and simple. It takes less energy than concertina, but more than sidewinding. It can also be used to swim.
* [Sidewinding](https://en.wikipedia.org/wiki/Sidewinding) uses a sliding, stepping movement to move across slick or rolling surfaces. Direction of travel is diagonal. Unlike serpentine motion, which uses sliding friction to move, sidewinding uses static friction: any part of the snake touching the ground does not move.
* [Caterpillar movement](https://en.wikipedia.org/wiki/Rectilinear_locomotion) uses static friction as well, lifting a portion of its body, moving forward, then pulling backward while the forward scales are on the ground. It's slow, but nearly silent. Moreover, the only part of the snake in motion is the muscles controlling its scales; the snake doesn't bend. Many snakes use this method to hunt.
With that in mind, I expect a snake-person as you described to usually move along solid ground with a serpentine motion, sidewinding on unstable or slippery ground, using the caterpillar movement to stalk prey, and finally using concertina to climb or traverse difficult/unstable ground.
[Answer]
The fastest, most efficient means of locomotion for a serpentine being is for it to roll itself into a hoop and roll around like a wheel. It can provide propulsive effort by flattening the loop slightly similar to a caterpillar track and flexing and extending its body in the appropriate way, or it can form a perfect circle and take advantage of inertia to keep it moving. It can steer by flexing its body from side to side, and could conceivably turn in little more than its own diameter.
It could be expected that on level ground, such a being using this method of locomotion could easily outpace and outdistance any creature using a method of locomotion that involves reciprocating limbs or any other variety of serpentine locomotion. It could conceivably keep pace with some slower or even medium-speed birds. A speed of 100kph sustained for over an hour or more is not inconceivable, but this would be approaching a maximum practical speed.
This is all well and good in theory, however there are also a few potential drawbacks:
* A lamia's body, coiled into a ring, might be unbalanced. This could be overcome to some extent by overlapping the thinner end of the tail with the torso, and this would also protect the torso somewhat.
* This would require that the ground be pretty smooth. Obstacles such as medium-sized rocks might cause injury if impacted at any speed. However, roads and herbivore-grazed plains would be ideal terrain. On rougher, less level terrain, the other forms of serpentine locomotion the OP mentioned would be required.
* Balance might be an issue. If a lamia relies on anything like a human's system of semicircular canals in the inner ear, such rotation could cause dizziness. However, since [several other species](https://en.wikipedia.org/wiki/Terrestrial_locomotion#Rolling) move in a manner at least similar to this, this is not an insurmountable problem.
* It would be difficult for the lamia to see where it was going. It might need to put its head out of the loop to the side, or turn its torso so that it was looking over its shoulder. Either way, there would be a significant part of the rolling cycle in which the lamia could not be looking where it was going. It would need pretty good eyesight to be able to see obstacles a sufficient distance ahead, and it would also need fast eyes so that it could form clear images despite its rotation. This would lead to an increase in its flicker-fusion frequency, meaning that a lamia would likely see a human movie at a mere 25 FPS as being a series of static images.
* The faster the lamia moves in this manner, the greater the centripetal forces attempting to pull its body out of its loop. Lamiae would likely need to evolve some sort of latching mechanism in order to keep their body in shape at higher speeds, or the lamiae may need to resort to artificial harnesses in order to overcome this limitation.
Still, despite all these limitations and problems, if they could be overcome, it would change lamiae from a slow, lumbering species with poor endurance to the fastest, longest-distance [cursorial](https://en.wikipedia.org/wiki/Cursorial) species the world has yet seen, humans included.
] |
[Question]
[
The [Hecatoncheires](https://en.wikipedia.org/wiki/Hekatonkheires) was the collective name given to three monsters; (Briareus, Cottus and Gyges) who were the children of Gaia and Uranus. They were not only known for their frightful enormity, but also for their ghastly arrangement of one hundred arms and fifty heads. Even Uranus was so taken back by their ugliness that he decided to push them back into their mother’s womb. On failing to do so, they were subsequently banished to the underworld of Tartarus.
This is a very creepy creature and is probably going to be a very difficult challenge. I imagine that it will have to be an invertebrate of some kind, maybe a mollusk or even an advanced sponge. I also really doubt all appendeges will be functional. How could a Hecatoncheires appearing species realistically evolve.
A list of all of the Anatomically Correct questions can be found here, suggestions for future question are welcomed;
[Anatomically Correct Series](http://meta.worldbuilding.stackexchange.com/questions/2797/anatomically-correct-series/2798#2798)
[Answer]
The hundred arms aren't a problem. A [centipede](https://en.wikipedia.org/wiki/Centipede) has that, sort of. We'll assume that the Hecatoncheir can use its limbs as legs or arms as convenient. The [metamerism](https://en.wikipedia.org/wiki/Metamerism_(biology)) of the centipede might also provide a basis for the fifty heads. Quoting Wikipedia:
>
> In biology, metamerism is the phenomenon of having a linear series of body
> segments fundamentally similar in structure, though not all such
> structures are entirely alike in any single life form because some of
> them perform special functions.
>
>
>
One must suppose that each of the repeating metameres or segments of the body of one of the hecatonchires\* has within it or growing from it something that one can call a head. What defines a head? I'd say that two out of three of (a) a cluster of sensory organs (which could include eyes, noses, ears, antennae or vibration-sensors), (b) a mouth, (c) a brain would be enough to count as a head. Note that the "brain" on each segment needn't be fully independent, it could be that these creatures had their intelligence distributed over [multiple](https://worldbuilding.stackexchange.com/questions/14807/what-are-the-conditions-in-which-a-creature-would-evolve-more-than-one-brain/) or [non-centralized](https://worldbuilding.stackexchange.com/questions/12254/creature-with-a-non-centralized-brain) brains, as dinosaurs [were once believed to.](http://www.smithsonianmag.com/science-nature/the-double-dinosaur-brain-myth-12155823/?no-ist)
\*They aren't all three joined together, are they? If so, that's beyond my worldbuilding pay grade / yuck factor. As is determining which of the many variants on offer is the correct spelling of "hekatonkheires".
] |
[Question]
[
It's a fairly well-known fact that reptiles are [ecotherms](https://en.wikipedia.org/wiki/Ectotherm), meaning that they require outside sources of heat to stay warm and metabolize. However, being too hot can cause heat sickness (not fun), and being too cold can trigger hypothermic states where metabolisms slow down, and movement becomes difficult.
Now, size and shape affect how well creatures retain heat, which also influences how much heat they retain and how well they can retain it. Since the creatures in question are human-sized, humanoid creatures, how would you determine the upper and lower temperature limits?
---
***Related***: [This question](https://worldbuilding.stackexchange.com/questions/75967/possible-thermoregulation-temperatures) is similar in that is discusses temperature ranges, but it's looking more for answers on how to change the range of thermoregulation for endotherms, rather than figuring out the existing range for ecotherms. [This question](https://worldbuilding.stackexchange.com/questions/93931/how-plausible-would-it-be-for-a-reptilian-race-to-have-settlements-in-cold-regio) is also similar, but assumes the knowledge of temperature ranges for their creatures. I am looking to find those numbers.
This is a graduated question from the [Sandbox](https://worldbuilding.meta.stackexchange.com/questions/4835/sandbox-for-proposed-questions)
[Answer]
I suppose the lower limit would be somewhere around the freezing point, where ice formation would cause tissue damage. But the reptile would be very, very comatose. If you want the creature to be functional, then it must be remembered that even reptiles generate heat from muscle activity. If the reptile had an unlimited food source, or huge amounts of internally stored energy, I can imagine that it could be active through internally generated heat right down to tissue damage. Just because an organism is an ecotherm, doesn't mean it can't store energy (fat) or have a thick layer of insulation. Being an ecotherm just means it doesn't have to generate heat just for the sake of generating heat. However, it also means that it can not maintain optimum efficiency for optimal performance. Ecotherms are EXPECTED to have a broad range of functionality and performance.
The upper limit, of course, would depend on the reptile's ability to release heat to the environment. Some reptiles have fin structures that they can open up, like fan radiators, to disperse heat. Again, just because they are an ecotherm does not mean they can not have mechanisms to disperse excess heat. Their blood can still move heat to the extremities. The upper absolute limit, I suppose, would be their bodily fluids boiling. The next limit would be that temperature at which their tissues actually bake (or, more specifically, their tissues going through chemical transformations due to the application of heat).
The complexity of the answer is compounded if you make the reptiles sentient, and aware of their surroundings, so they can actively take measures to seek heat sources or to cool their bodies.
I have this vision of a frog wearing a sweater.
[Answer]
The simplest way would be to look at reptiles that roughly approximate humans in size... alligators, crocodiles, larger turtles or monitor lizards. All tend to be found in tropical or semi-tropical environments, as the very large reptiles are not known to hibernate during cold periods.
In general, the larger the reptile, the warmer the climate it lives in... very large snakes are also restricted to tropical climates. It appears that their large muscles need an average temperature not far off what warm blooded creatures maintain.
The fossils of an enormous snake dubbed Titanoboa, reaching 50 feet in length, have been found and dated to the Paleocene time frame, when the climate of the earth was known to be warmer than it is today, averaging around 90 degrees F, presumably hotter in the equatorial areas.
There is one advantage to being cold blooded that you might factor into your human reptiles: because they don't burn off energy maintaining body temperature, their food needs are considerably lower.
At the same time, you can consider two fish that are semi-warm blood, in that they maintain a body temperature around 10-15 degrees higher than ambient temperatures... the great white shark and bluefin tuna. Both are very powerful creatures, the bluefin tuna can achieve speeds of around 50 mph. Both are also very large, and tend to be found in cooler waters. It is possible that your reptile humans could make this same adaptation.
Curiously enough, this adaptation has not been seen in reptiles.
[Answer]
If you look at modern lizards for comparison then have about a **15-20 degree celsius temprature range they are active in**, this is a bell curve so activity drops off on the ends. Now an intelligent species would be on the wider scale since they can apply technology.
Now you have a bit of play in where this range sits, in colder adapted reptile it may start as low as 15 degrees, in warmer adapted ones temperatures up to 45 degrees are acceptable. So you have to ask yourself what kind of climate are my creatures adapted to cold or hot.
You also have a small issue with the word "reptile", Crocodillians in general handle a wider range of temperatures than most other "reptiles". The term "reptile" can be applied to endothermic organisms, so you should decide if your creatures are actual ectotherms or not.
[Answer]
**There's way more to this than size and shape**
First, as for [warm-blooded](https://en.wikipedia.org/wiki/Warm-blooded), it's not just warm-blooded and cold-blooded.
The real root and determinate factor to this question **isn't size and shape** but a species' **genetic adaptations**.
**Metabolism** (/ecotherms as you referenced) is but one genetic adaptation a species has selected as a response to the thermal challenges of its environment. Metabolism can be handled in many ways on a chemical level. There are plenty of other adaptations that can be employed in response to this challenge, either singularly or in combination.
* **Hair** can add varying levels of insulation to resist the cold. Density, construction, disposability of it can all variably impact the response to cold. Even color can be used dispense excess heat.
* **Sweat** can lower an organisms body temperature in response to heat, though this requires access to water.
* **Hibernation.** Some animals just hibernate when it gets too cold. Some frogs (amphibians) allow themselves to be frozen in ice to pseudo hibernate and thaw out in the spring. Saharan crocodiles bury themselves in mud pits during the dry season and enter a state similar to hibernation.
Your reptile could have unique adaptations that meet this challenge similarly to the above but still appear reptilian. For instance it could have insulating scales that trap heat in, allowing it to survive colder temperatures. It could sweat to reduce its temperature. It could have reflective scales to reflect excess sunlight. It could store fat and become warm-blooded if it senses it has become too cold. It could just hibernate and encase itself in ice.
**The bottom line is these limits you want are governed purely by the genetic adaptations of your species and not just its size and shape.**
[Answer]
With the right biochemistry the lower limit is frozen solid, thawed and carried on, but that's a "life limit" not an activity limit, modern crocodiles and alligators are about the biggest reptiles on Earth they remain relatively active down to about 13 degrees Celsius but they stop feeding at as high as 21 degrees. I believe 56 degrees is the point at which most reptiles have to seek shelter or they risk organ damage but I can't think where I heard that number.
So those temperatures could be a guideline for you, I would think that an upright biped would in fact suffer greater complications at both high and low environmental temperatures, the human head is more exposed relative to the body than it would be in a quadrupedal body form so at low temperatures it suffers greater heat lose but as it is at the top of the body and heat rises it would also cause issues at high temperatures.
[Answer]
Instead of searching for an answer based on size, which habitats/climates would fit your story best? There is actually plenty of possibilities of adaptations to temperature within reptiles of the size your looking for. I will mostly look at the lower temperature border in this answer.
Have you considered [mesothermy](https://en.wikipedia.org/wiki/Mesotherm)?
Mesotherms are animals who because of high metabolic rates generate enough heat to have a constant body temperature despite changing surrounding temperature.
One extant example is the [leatherback turtle](https://en.wikipedia.org/wiki/Leatherback_sea_turtle), who has even been found [within the Arctic Circle](https://www.lofotposten.no/lokale-nyheter/dansker-i-kajakk-motte-monster-ved-nusfjord/s/1-71-7575956)! High muscular activity, [counter-current heat exchange](https://en.wikipedia.org/wiki/Countercurrent_exchange), thick fat covering and incredibly something similar to [brown fat tissue](http://www.jstor.org/stable/1445737) found in mammals for generating heat without shivering.
But even more extreme were **Dinosaurs**!
There has been a lot of debate about the metabolism of dinosaurs and some scientists believe that some speceis were in fact warm-blooded. You can find a lot about that in this exhausting [wikipedia article](https://en.wikipedia.org/wiki/Physiology_of_dinosaurs).
Some dinosaurs species have lived in very cold conditions and the article gives some temperatures:
>
> Dinosaur fossils have been found in regions that were close to the poles at the relevant times, notably [...] the North Slope of Alaska [...], so polar dinosaurs and the rest of these ecosystems would have had to cope with the same extreme variation of day length through the year that occurs at similar latitudes today (up to a full day with no darkness in summer, and a full day with no sunlight in winter).
>
>
> Studies of fossilized vegetation suggest that the Alaska North Slope had a **maximum temperature of 13 °C (55 °F)** and a **minimum temperature of 2 °C (36 °F) to 8 °C (46 °F)** in the last 35 million years of the Cretaceous (slightly cooler than Portland, Oregon but slightly warmer than Calgary, Alberta).
>
>
>
The possibility of migration is disregarded:
>
> But a round trip between there and Montana would probably have used more energy than a cold-blooded land vertebrate produces in a year; in other words the Alaskan dinosaurs would have to be warm-blooded, irrespective of whether they migrated or stayed for the winter.
>
>
>
So to answer your question, maybe something around 2 °C (36 °F) can be the lower limit for year round human-sized reptiles. With hibernation you can even have it colder: the farthest north extant terrestrial reptile is the [Viviparous lizard](https://en.wikipedia.org/wiki/Viviparous_lizard) although you will have size-constrains for your human-sized reptiles...
For the upper limit, similar approaches are possible. If you want your species to live in hot deserts, think about heat exchangers like the neural spines of [Spinosaurus](https://en.wikipedia.org/wiki/Spinosaurus#Function_of_neural_spines), bright skin colour, behaviour adaptations like night activity or borrowing/living in caves. Compare for example [here](https://www.desertmuseum.org/books/nhsd_adaptations_amph.php).
] |
[Question]
[
I've been working on an alien species for some time that combines several traits I find interesting into a single being. This species is for use in a fantasy story, but I want it to have a hard science anatomical structure so that I could use it in future sci fi stories as well. I will bold the areas where I need the most help in to make it at least slightly scientifically viable.
Basic Description: A semi-aquatic arboreal species of sexapods with digitigrade back legs and four arms. Look reptilian but are probably closer to a dinosaur biologically.
Habitat: They originated in a dense jungle dotted with swamps and rivers. The trees are very tall and thick, and have a wide canopy that covers the watery ground floor. There are large patches of dry land, but most of the area is wet.
Evolutionary Path: They evolved from a fresh water ambush predator much like a crocodile that's main method of attack was leaping out of the water and dragging it's prey down with it's arms. It eventually started climbing and ended up filling a different sort of predatory niche involving traveling through the trees and dropping down on unsuspecting prey, grappling them into the water.
Advanced Description: This species, on average, stand to be 6'5" to 7' tall on their hind legs and have six limbs. Certain members of the species grow much larger than that, but that will be covered below. They have a very slender, elongated build that minimizes bulk in favor of a lighter weight and more efficient strength. A set of arms coming from the torso and a pair of digitigrade legs, along with a long, prehensile tail that is roughly the length of the full body from head to toe. The upper set of arms are slightly longer than the legs in proportion while the lower set of arms are closer to what humans would consider proportionate to it's size. It's body is covered in a thin layer of scaled, leathery skin that is highly flexible and smooth, much like the skin of a snake. The color of the scales can change, largely in response to the creature's mood though they have some conscious control over the changing color as well. Each limb ends in three digits (Though I am debating on the number of fingers and toes) ended in slightly curved claws with dull edges and sharp points. The head has a slightly pronounced jaw-line designed to allow for superior bite force, but not so pronounced that it can't support lips for better vocalization. I am also debating on giving them small conal horns that aid in channeling sound waves so compensate for not having proper ears. For hair they have long, very thin feathers that grow from their cranium like a crest. It would appear like hair to anyone looking at them from a distance, and culturally is treated much like how we'd treat our hair. Ideally the feathers are water resistant in some way so that they do not become a burden to the creature when submerged or in the rain.
**Breathing:** I've done a lot of research into why a four armed creature can't breath, but I didn't find many work arounds in it's place so I started looking through the animal kingdom. The best answer I could find were turtles. Like turtles this creature would likely need sheets of muscle tissue around their lungs that constantly expand and contract around the lungs, allowing the creature to breath despite the chest being contained and unable to expand with it, similar to a turtle shell. It isn't as energy efficient as normal breathing of course, but giving the creature generally more efficient lungs and blood to make oxygenating the muscles more efficient can compensate a bit. This does still leave it with a loss of upper back mobility though, and a thought I had that I can't find much information about was that it's solar plexus is broken into flat vertibrae similar to a second spine. This would theoretically make the creautre able to bend it's upper back at least slightly at the cost of a weaker chest. I am unsure how scientifically valid this concept it though.
Naturally as a semi-aquatic species it's muscles are very efficient at storing oxygen for later use, allowing it to stay submerged for about an hour at a time. It may also be able to absorb oxygen from the water through it's butt, much like the beloved turtles I referenced earlier.
**Body Temperature:** I was divided between warm blooded and cold blooded for this species, but came to a middle ground. The premise being that they are endotherms with the capacity to lower their metabolism and shut down the ability to produce body heat during periods of time when intense physical activity isn't necessary. So when it's warm out and there isn't a lot of hunting to be done they would convert to an ectothermic lifestyle, but when it gets colder or food is desperately needed they could convert back to endothermic. There should probably be some sort of trade off for this, but I can't think of one aside from it maybe using up a lot of energy?
**Substantial Growth:** A unique attribute of the generally larger male half of the species is the capacity to grow indefinitely. Females may have this ability too but just don't for cultural reasons. Basically if one of these creatures is consistently overfed it will continue to grow larger like a snake in a large tank. In this way the normally 7' tall male could grow upward 10-12 feet tall, though at that point it wouldn't be able to stand bipedally anymore and would likely not be able to effectively climb, sacrificing it's ability to hunt for itself in favor of being large and in charge. Females and beta males would do the hunting while this giant alpha fought off other large predators. Fights between tribes would usually be settled by a fight between alphas, and in cases of all out war the smaller female could ride her mate into battle in the form of a cavalry archer. They spend most of their time in the water when they can so as to minimize energy usage between fights. Becoming this large takes years and is a long term goal for any male leader of a tribe. Being so large does shorten their lifespan however, much as it does in abnormally large humans.
Males that don't want to become giant need only not over eat, as they can only get bigger by overfeeding. With a stable intake of food they won't grow far beyond the 7' tall limit. Alternatively I had considered frequent mating with multiple female partners to be what triggered the capacity to grow. A sort of hormonal shift. If this idea is even possible I'd like some input on which method of beginning the transformation makes the most sense.
**Green Blood:** Their blood is actually white, which I read somewhere is the most efficient in terms of oxygen transportation. However it also has a high concentration of biliverdin that gives it a green pigment, much like a specific group of skinks on Earth. It doesn't have to be biliverdin though, and if someone could tell me a better way to get green blood that would be very nice.
**Can use a Bow and Arrow:** I kind of fell in love with the idea of a four armed archer. Not to hold and fire two bows at once or anything, but simply for the ease at which it could reload and fire rapidly. I know the claws would be a hindrance, but perhaps an arrow grip where the claws are used to hold and notch the arrow, then pull back the string? If need be they could cover their string claws with some sort of padding. Or just a pinch draw.
So there it is. There's more to this species than what I've listed but I'm already worried this is too long. So is the described creature scientifically viable?
[Answer]
**Breathing.**
You are overthinking it becasue you were misinformed.
**Four armed creatures would be able to breathe without issue, Only a mammalian
breathing system needs a flexible chest.** Dinosaurs had an absolutely rigid torso and could breathe just fine, one group used air sacs the other pulled on the lungs directly via tendons attached to the liver similar to modern crocodiles. Crocodiles are the closest to your body plan with a very rigid chest and a more flexible lumbar region, they have something in between, [lungs partitioned to work like a pseudo-air-sac](https://science.sciencemag.org/content/327/5963/338/tab-figures-data) and muscles pulling directly on the rear of the lungs, again with a liver intermediary. The lung is stretched like a piston chamber, in fact a fairly rigid chest makes it work better. There is quite bit over variation in this across archosaurs, with some turning the pubis into lever to give even more pull. Quite frankly the mammalian breathing system is awful there is no need to copy it if you don't have to.
[](https://i.stack.imgur.com/U74MS.png)
**Ears**
Don't bother with external ears, Unless you give them mammal like inner ears they won't get any benefit for it. it makes even less sense in a semiaquatic species. even semi-aquatic mammals drastically reduce or loose external ears. Most animals have really poor hearing compared to mammals, or course mammals have very poor color vison. so if you are basing them on dinosaurs they have simple hearing and very good vision.
**scales.**
You may want to go with sea snake like or crocodilian scales with a more pebbled texture, overlapping scales reduce flexibility, snakes have them for added traction.
**Body temperature.**
You basically described endotherms that can torpor, like squirrels. In the short term it is pointless, the cost of heating the body back up out weights the savings, it is only useful for long periods of inactivity like winter.
**Locomotion.**
Being fast swimmers will make them slow climbers, fast climbing will make for slow swimmers, they will end put being bad at hunting in one of the terrains. They are optimizing two very different forms locomoting with very different needs. climbing favors light weight, long highly flexible limbs with fine motor control, strong grip with long thin fingers, good depth perception, long flexible tails, ect. Swimming favors high density, short stiff wide limbs, Flat stiff digits, powerful stiff flattened tails, ect. If they hunt like crocodiles they also need eyes high on the body and the ability to sit still for long long periods without becoming lethargic, while climbing hunters need to be constantly on the lookout for food, and either high speed or extremely good stealth.
**Growth.**
Again it sounds like crocodiles, who also continue ot grow throughout their life. Note however their growth does slow down however once they reach maturity. A hormonal change is possible but you will likely see drastic differences between males and the shift happens before mating, often triggered by nutrition, something like elephant seals with single dominant male that is huge and a few sneaky small males. This however will make for poor cooperation because female have little choice in partner, so your first idea may be better.
**Blood**
Animals with chlorine based blood like annelid worms have green blood. Alternatively combine **copper**, makes blue blood, used for oxygen transport (crustaceans and octopi) and **vanadium** makes blood yellow,(beetles and sea cucumbers) weirdly the vanadium compounds are likely not used for oxygen transport, and [we really don't know what it is used for](https://pubmed.ncbi.nlm.nih.gov/11921344/), so you can justify them having both and no one can say otherwise. Our best guess is it is part of their immune system but it really is just guess work at this point. Blue plus yellow gives you green blood.
**Bows**
Climbing claws could be a bonus or a hinderance, it really depends on how curved they are, the more curved the more they hamper by hanging up the bowstring. You may want to use a Japanese style/Mongolian draw where the thump is used not the fingers, this can allow even fairly curved claw to work, although they will almost certainly put some kind of protection on the bowstring to keep the sharp point of a claw from fraying the bowstring. Something like a string loop or thumb ring will protect the bowstring, Both are common historically and easy to make.
[](https://i.stack.imgur.com/vxAj0.png)
[Answer]
**Green blood:** you'll probably have to invent a ***respiratory pigment*** that remains green in colour both when it is carrying tons of oxygen (in the arteries) and when it is depleted of oxygen (in the veins on the way back to the lungs). Probably something copper based. If there is someone here who knows enough chemistry to tell you the colour of various copper compounds in different oxidation states, they'll be able to help
There is a real world 'green blood' but it turns red when carrying oxygen: [chlorocruorin](https://en.wikipedia.org/wiki/Respiratory_pigment)
**Substantial growth:** this is the bit I have problems with. Not the growth potential itself - you describe that well. The problem is how this might have evolved in the situation you describe. For instance, to get big the male must eat lots. And after it IS big it will need more food than a small male. Yet it is the small males and females doing the hunting and then - presumably - sharing their kills with the big males. Why are the small males doing this? They could just keep the meat for themselves and grow bigger. How does the big male enforce sharing of the meat? In lions, it is because the male travels to the kill site and chases the lionesses away from the meat, but your big males spend their time resting in the water.
Also because of the shortened life span, there has to be an ENORMOUS advantage to getting big. In evolutionary terms, this means fathering lots and lots and lots more offspring than long-lived small males. In pretty much all the species where males are bigger than females (apart from humans - we're complicated), that increased male size and strength is for the sole purpose of beating the living crap out of other males of their own species *to prevent them getting laid*. It is *not* for defence against predators. It might be useful for that, the same way fingers are useful for pointing at things, but they didn't evolve for that purpose.
So your males mate with lots of females because they are big. Rather than your suggestion of becoming big because they mate with lots of females.
Also, if your big males hang around in water, the only predators they can fend off are water ones, or ones that come to visit them. If policemen stay in in the police station the only criminals they catch are those who break into that police station! :-) Predators are going to be all over the tribe's territory, and will be picking off small males and females when they are out hunting or gathering firewood or whatever.
So if you want this to be evolutionary rather than cultural I think your big males need to be more active. They need to be bullying food out of smaller males, patrolling their patch to drive off other big males who are after their women, kicking small males who are getting to medium size out of the tribe as a potential threat (this includes their own sons), and generally behaving like a bad-tempered boss stallion, rutting stag or beachmaster bull elephant seal.
If it is cultural, then it is a whole other kettle of fish. Then you can invent traditions and laws that say only the heir to the throne gets to eat swan meat or bloopbloop berries. And it is something in those foods which triggers the size increase. Or simply that royalty eats better than the peasants!
[Answer]
I'm wondering if you have any justification as to why this species has become intelligent, or rather more intelligent than leopards or lions? Are they supposed to be around that level of intelligence?
Why and how would this species evolve the manual dexterity necessary for tool creation and utilization (eg. bows and arrows)? What would distinguish it's arms from it's legs in terms of function?
Why would a water or tree dwelling ambush reptile have slender, and therefore fragile, legs? In general, reptiles have very stocky, thick limbs for their size, especially Alligators and Crocodiles, the supposed ancestors of this animal.
Why would the animal's legs be different lengths? Animals that walk on four legs generally have either similarly length limbs or longer hind limbs. The only animals I can think of with longer forelimbs are tree-dwelling primates who move through a swinging motion. This supports an arboreal lifestyle, but the swinging-through-trees, horizontal lifestyle instead of the up and down a single tree, drop bear lifestyle of the animal.
These are all just thought questions, and I do not by any means want to discourage you from going forward in using these creatures. I just want to understand how and why you chose your creature. It seems like a being with a set of interesting, almost cobbled-together set of traits that don't really make sense from an evolutionary standpoint. It could be that I am being overly pessimistic, but it seems hard for me to divorce the idea of intelligent life too far from our only data point, humans and great apes. I have read and enjoyed many stories that don't really justify the existence and traits of their chosen creatures, but if you want to have an explanation, you might as well consider my questions.
[Answer]
Advanced Description: There seems to be no need to weaken the jaw to permit lips, as almost all vertebrates, including several such as *T. rex* and *O. megalodon*, seemed to have had lips. Waterproof feathers need some sort of oil covering to not get wet, but as they are intelligent, this shouldn't be a problem
Breathing: Why not use the dinosaurian breathing method of a rigid lung with air-sacs surrounding it? This works well with a rigid ribcage, as can be seen in birds, and should work fine in this creature
[Answer]
## Lungs.
With the others I'm confused why a diaphragm won't work, but let's forget about that. The biggest problem with your system as described is that muscles don't "expand" Birds have a system of air sacs, described in a [previous question here](https://worldbuilding.stackexchange.com/questions/113038/would-this-biological-cooling-system-work) so I'll recycle the image:
[](https://i.stack.imgur.com/Xq95a.jpg)
Now what's apparent from this is that a different evolutionary path could fairly readily have surrounded each *sac* with the sort of musculature you describe (let's call it a [detrusor muscle](https://en.wikipedia.org/wiki/Detrusor_muscle)), though this one is skeletal muscle and much faster-acting). The creature still needs *some* sort of bellows that can expand to suck in air, but one option is that since you say the chest doesn't expand, you could have some sacs pulled open when others contract. Conceivably such a system could have many small orifices, each specialized only for inhalation or exhalation, with different breathing circuits operating in parallel. Perhaps on your world there are underwater plants that fill bladders with pure oxygen from photosynthesis, and your creatures thrust sharp scales near one opening into the cavity and drain it of its oxygen, retaining it in their body as a storage for some hours while breathing ordinary air, so that at a moment of exceptional stress they can supercharge their metabolism. Or perhaps they store metabolic waste products, such as exhaled ammonia, in a bladder as a signal or a means to deter predators.
## Limbs.
Explaining the evolution of extra limbs is tricky. I'm going to go with ... fly swatting. Your critter had powerful webbed feet (front legs I think??) for rapid bursts of swimming underwater. The swamps and jungles gave it an opportunity to leap from the water and grasp a tree branch high above, from which it hung with its arms (I think) until prey arrived to be caught with its powerful claws. All very good except that the flies and mosquitoes on your world are merciless. If we suppose that your "tetrapods" are more segmented and less canalized than ours and occasionally have mutants with an extra segment with extra arms or legs to go with it (digitigrade hind legs??), perhaps some of those mutants were simply able to swat (and perhaps eat) these intimidating pests.
## Green blood.
Evolving a green pigment isn't especially hard, though you do need to absorb both red and blue light. Here though, let's do ... structural color. Like the scales of a butterfly wing (see [this blog](https://bengarrido.com/2013/12/19/geekery-of-the-day/) for an abundance of lovely images), the blood cells have periodically spaced ridges of protein. Perhaps they have a means of regulating oxygen affinity by changing the distance between layers of protein. Whatever the reason, their blood is usually green, but the blood cells *can* move the layers to a different distance (unlike butterfly wings) resulting in different colors. Blood passing through the scales can do this for color signalling - there is simply a rapid paracrine signal, maybe nitric oxide, that communicates to the blood cell as it enters. But the blood will not reset its color until its oxygen is depleted, so if it is shed, it remains whatever color it was. The result of this is that the organism could potentially shoot its blood (like a [horned lizard](https://www.nationalgeographic.com/animals/article/animals-lizards-reptiles-blood-eyes)) and the blood would remain whatever color it had been until it dried out. So it could actually paint multicolored messages and images biologically (decoys?), before developing tools to do so with less cost.
## Large males.
Make them *queens*. The females lay their eggs externally, *before* they are fertilized. But they do it *inside* the male, which can then store the eggs internally, keep them safe, fertilize them, incubate and nurture them internally, and lay them at the appropriate time. This is a more extreme notion of the [midwife toad](https://en.wikipedia.org/wiki/Midwife_toad). The males attract females by being mighty, sturdy protectors capable of defending their nests, bulked with massive stores of nutrients that guarantee the offspring will successfully complete an internal phase of development.
] |
[Question]
[
Given a monarchy, how far apart can two cities/towns/etc be situated, while still maintaining order and power? Alternatively, think about it this way: given any random settlement area, what is the farthest another settlement could be that the second is still controlled by the first?
What factors outside of technology could change this? Think socially, politically, and so on.
Assume medieval technology, give or take a century.
I've looked at the answers already posted, and they mostly seem to deal with empires and the largest expanse they conquered.
Note that I'm not asking for what the largest expanse of an empire can be, but rather more specifically farthest reach of power between cities or towns.
[Answer]
EDIT: Ok, in answer to the edited question, I'm completely redoing the answer. I did leave my old answer below if anyone wants to read it.
The distance two towns can be apart and still be under one *regime* is infinite. But the distance between two towns that a single governor/monarch can handle (i.e. no act in, besides maybe a simple mayor to handle civil disputes), would be about a week ride. Because the monarch would have to go there to see exactly how things are doing. A Garrison of solider would be under his command, not the "mayors" so he would need to be able to give them commands.
Social problems could reduce the distance. If there was a high chance of an uprising, the monarch would need to be closer to be able to keep a better eye on things.
---
## Old Answer
That would definitely depend on what technology the civilization had. With even current day human technology, world-wide domination could be considered possible (the English did it with even less sophisticated technology). Instant communication, and even better, instant travel would be huge in deciding how much distance apart two areas could be and still be ruled by one person.
As suggested, good, local authorities would also be needed for any sort of distance. A ruler can not be in any place all the time, even with the above technologies. But a good local ruler can keep an eye on things and make basic decisions without his leader.
The leader would also need to keep in touch with the people. If you don't know what your people want/need you won't be able to keep them happy/rule them. Or the leader could be a dictator, but either way the leader would need to know where problems were. This is complicated by larger distances, so that can put a limiting factor.
So it is hard to give a number on how far away two areas can be to be ruled by the same person, a specific set of technology/circumstances would need to be given for that.
[Answer]
Roman empire was **huge**. And it lasted a lot of centuries on the basis of being divided on provinces and the fidelity of the Governors (and the roads for haveing an effective menace of sending legions).
Spanish empire was **huge** and sparse. Again, Viceroys and Governors were key to its (time limited) success.
Russian empire was **huge** and lasted for centuries. It started with medieval weapons, so it is not a matter of modern weapons nor communications. Again, fidelity. Remember Miguel Strogoff.
Alexander's Empire was **huge** and it did not succeed. His generals were not loyal to his blood but created kingdoms on theirselves.
The pattern repeats over and over: delegation of power, as much as necessary, on strong but loyal governors.
**EDITED** New answer below for the sake of the rephrased question
This depends on several things. Roman empire was a single settlement (Rome itself) and it still controlled the "known world". But if you are thinking on direct control, with a single governing body (a mayor or king, a counsel like in Sparta, or any other) directly controlling both towns from one, the most important point is loyalty. Settlers from town A creating a settlement B near a silver mine would still have their families and issues in A, so they will be loyal to A (if they already were). With time, and with the development of B, it becomes more and more self-sustained, and eventually an independent town. How long this takes and how friendly is the new town depends on the feelings of B citizens and on the attitude of A towards B. Openness and friendliness causes B to become an independent friendly city with "a common history" and multiple business between them, on the long time. Metropoli/colony thinking causes B to end revolving, causing either an angry independence (USA from England) or a permanent colony status that must be maintained by force. In this last case, you need to go there quite quickly, so maybe you can not keep control of B from more than some travel days ago.
[Answer]
I would approach this from different angle. How loyal and competent is the governor of the distant city? I see this as the most important question.
Of course, technology plays some role. If the fastest messenger can get there in a day it's easier than if he can get there in a week, or even in a month. But for if you don't rely for them to provide you military help when some unexpected enemy attacks you on the other end of your empire, all you need is that the governors of the colonies send you taxes and when you send there messengers asking for soldiers or some other special help, the order will be obeyed. This is a matter of organization, not much of communication technology.
Look at Spain and its colonies in South America as an example. Ships were slightly faster, but otherwise communication in 16th and 17th century was not faster than in Middle Ages. Still, Spanish governor in Lima or any other distant city was able to maintain order in his province. And the order lasted until 19th century, when the inhabitants of most colonies decided they need independence.
Whether it could be even better if the king visited the colonies sometimes is a question; I guess that the time spend on a ship, far of the court where all the diplomats and messengers could easily find him, would hurt the empire much more than slightly less control over the colonies.
So space is not a question if the king is sensible and local stewards compenent and loyal.
[Answer]
Theoretically? infinite,
In reality it depends on a. the technological level of the society, b. the power of those in charge (their military, bases etc) and c. how accepted the power of those in charge is.
If, for instance, you have a medieval society with the the man in charge being disliked or unaccepted by the people (say he invaded and took over the land) then to keep order he may need to have armed strongholds roughly 30 miles apart to keep order over the people. This is because 30 miles is about a days march, so if there is an uprising those 'keeping the peace' do not need to travel far to counteract it and should a stronghold go under siege then the nearest strongholds can quickly send aid.
Of course, as strongholds/castles are expensive you may only have a high density of them in strategic locations or where uprisings have occurred previously.
This answer was based off of England after 1066 when William the Conquer came to power. This was his method of keeping power (along with destroying everything with fire should an uprising occur)
] |
[Question]
[
I have a planetary system with a yellow dwarf similar to our own Sun and three habitable planets. I want to hide this system from sight and long range scans in a nebula, a giant cloud of dust and gas in space. Can this planetary system exist safely hidden within the nebula or within a pocket of empty space in the nebula?
[Answer]
We have plenty of examples where stars have been hidden by nebulae - and not just newborn stars. Typically, the gas and dust comes from mass loss from one of the stars in the system. Examples include
* [LL Pegasi](https://en.wikipedia.org/wiki/LL_Pegasi), a binary system containing a carbon star that is sloughing off large amounts of dust as it nears the end of its life. This makes the star visible only in infrared light.
* [CW Leonis](https://en.wikipedia.org/wiki/CW_Leonis), a similar star which seems to have a binary companion that has evaded direct detection; its existence was only discovered through measurements of the motion of the primary.
*Some* stars, as L.Dutch indicated, can ionize the gas surrounding them, producing [HII regions](https://en.wikipedia.org/wiki/H_II_region) and emission nebulae which are easy to find. However, these stars are typically hot and massive; their high temperatures mean their emission peaks at shorter wavelengths, and therefore they emit more high-energy photons capable of ionizing the circumstellar hydrogen. Your star, on the other hand, should be fine, as it's comparatively cool.
A yellow dwarf seems comparatively unlikely to form a dust cloud while it's on the main sequence; later in life, as it enters the asymptotic giant branch phase, it could if it indeed becomes a carbon star like the stars I mentioned above. To form this dust cloud, then, perhaps there's a companion stars on an eccentric, long-period orbit, constantly replenishing a large circumstellar cloud of dust that enshrouds the system.
(Of course, as Juraj suggested, the system could simply be moving temporarily through an interstellar cloud, e.g. something as dense as a [Bok globule](https://en.wikipedia.org/wiki/Bok_globule). I'd been thinking largely of systems that would be stable over longer periods of time, and I'd completely missed that possibility.)
It's true that the dust will reemit light, peaking at a few microns, firmly in the infrared part of the electromagnetic spectrum. CW Leonis, for instance, is extremely bright, as seen from Earth, at 5 microns. But unless the people doing the scanning are carrying instruments capable of imaging the system at those wavelengths, it won't pick anything up. If they're on a spaceship, I think it's unlikely a ship would have such an infrared imaging system; most objects radiate at plenty of other wavelengths, and carrying optical or radio instruments seems much more efficient.
[Answer]
When you want to hide a star, distance is your friend. Due to the famous law, the luminosity of a star decreases with the square of the distance. Therefore the farther the observer is, the more difficult it is to see the star.
But what happens if you put the star in a nebula?
The light of the star will excite the atoms in the nebula, getting them to emit light. As a consequence, instead of a dim point, you have now a diffuse glow that shouts, for those who can hear, "hey, I am hiding a star here!".
Wrapping up: if you want to hide the planets, maybe the nebula is a good idea, as the current technologies we have for detecting planet rely on the direct observation of the emission of the main star. If you want to hide the main star, better rely on attenuation with distance.
[Answer]
If you are worried about the habitability of these planets with a nebula, they could be just fine. As star systems travel through space they can pass through nebulae of varying sizes and have nebulae form near them and fill the sky with colour. I imagine the night sky on these worlds could be spectacular.
] |
[Question]
[
This creature was void-born in the farthest depths of time in this Universe. Drawing its energy from electromagnetic radiation, and sealed against the vacuum of space, this drifting creature establishes itself in stable orbits, Lagrangian points, and in the wakes of comets. With the patience of a microbe, it can be ejected from solar systems and wait millions of years to re-establish itself. So, by fortune, it has spread, over billions of years, across this galaxy and beyond.
How does space plankton work?
It must:
* Be able to survive and reproduce in the vacuum of space.
* Generate energy somehow using electromagnetic radiation. It would be cool if multiple strains could utilize different frequencies.
* Go dormant as necessary to survive millennia or more in slow, sublight travel across galaxies. Upon reaching a suitable new habitat, it must be able to reproduce and grow once more.
[Anatomically Correct Series](https://worldbuilding.stackexchange.com/questions/25281/anatomically-correct-griffins)
[Answer]
Their bodies are made of concentric shells of photon absorbing materials, arranged in a quantum cascade fashion:
* The outer layer absorb photons of energy $E\_1$, re-emitting a photon of energy $E\_1 - \delta E = E\_2$
* The following layer absorb photons of energy $E\_2$ and re-emits at lower energy $E\_3$
This cascade proceeds ad libitum.
Such principle can be applied starting from any point in the electromagnetic spectrum, and energy can be kept within metastable molecules to be released on demand.
The organism feeds on capturing travelling ions encountered during the travel. When the size of the organism goes above a certain threshold it simply splits in two smaller beings which depart one from the other. This works as reproduction for them.
Absorbed photons and ions provide momentum to them, keeping their eternal space travel.
[Answer]
**Panspermia perhaps**
Perhaps we can look at how a particular species like this could evolve.
If it was, for instance, a similar origin to a plant species, converting light and gas into cell structures, it may be conceivable for alien plant-like species to develop seeds in much the same way as fungal spores, light enough to be easily ejected into space.
If such spores were in the trillions, floating out from its origin system, it might be possible that in millions of years it could float to adjacent star systems, or into gas clouds.
In this instance, in further millions of years, it needs to:
* Maintain its DNA (or similar) structure impervious to radiation, or evolved to reproduce naturally far away from extreme sources of radiation to prevent its demise.
* be able to find, or bump, into others of its kind to mate, or simply reproduce asexually.
* gain mass in order to reproduce and spread.
One way to gain mass is simply to wait millions of years, where through the gradual force of gravity hydrogen and other light elements may 'stick' to it, and slowly become the genesis of a new cell. Once sufficient mass is gained, it could again 'explode' and send more spores/seeds out to other star systems, for the next generation.
Each generation could be hundreds of thousands, if not millions, of years - a mere blink of the eye cosmologically.
] |
[Question]
[
Consider centaurs, mermaids/mermen/merfolk, driders/arachne, lamia/naga, and other half-human creatures with similar bodyplans, which I will henceforth refer to as "centauromorphs". They all have a legless human body (which may or may not include the pelvic region) attached to an animal body where its head would normally be; this applies even to the snake-based lamia/naga, because anatomically speaking, a snake's body is mostly an extremely lengthened thorax, with the actual tail only forming a small portion at the end.
So, this begs the question: How would the [anatomical terminology](https://en.wikipedia.org/wiki/Anatomical_terminology) work for a centauromorph, considering that there would be duplicate body regions and parts between the humanlike and nonhumanlike halves of the whole body? This is further complicated by the fact that those regions/parts aren't always truly homologous (e.g. the thorax in humans and horses contains the respiratory system and the heart); they can be merely analogous (e.g. the abdomen in humans and insects; whereas it's mostly the digestive and urogenital systems in the former, it contains practically every major internal body system in the latter except the brain, including the lungs and heart that would be found in the thorax in vertebrate animals)?
Furthermore, in the case of arachnid- or crustacean-based centauromorphs, the animal body part that the human portion would be attached to is the cephalothorax (i.e. it's a head and a thorax in one in the animal that the hybrid creature is based on); I don't know about anyone else, but describing a drider as having a legless humanoid body attached at the lower end to the front of a spider's cephalothorax sounds really awkward to me unless it's meant literally, i.e. if you actually amputate a humanoid's legs (or just use a humanoid who lost their legs beforehand) and surgically/magically attach them by the pelvis to an already-existing spider's cephalothorax.
For an example of what seems IMO to be improper anatomical terminology for such duplicate body parts, take [*Monster Musume*'s Arachne race](http://dailylifewithamonstergirl.wikia.com/wiki/Arachne) (**WARNING: it's a fanservice-heavy manga/anime, thus expect frequent NSFW-ness of images on the site**). In the official diagram for Arachne anatomy, the thorax and abdomen are qualified with the adjectives "first" (for the human ones) and "second" (for the spider ones). This seems quite lackluster, because anatomical terminology typically proceeds in a medial/proximal to lateral/distal direction with respect to the standard anatomical position, the only exception I know being the numerical order of the digits (it starts from the thumb, which in SAP is actually the most laterally positioned of the digits). Furthermore, it gives preconceptions about the roles of each body region (especially their internal makeup) that do not seem to make any sense biologically; why would a centauromorph have two thoraxes that are separated by an abdomen, with yet another abdomen coming after them all?
PS: This question is particularly relevant in the case of one particular fictional arthropod-based centauromorph species that I'm working on, since its brain is actually distributed between the human head and what would be an arachnid/crustacean cephalothorax (i.e. effectively two brains), but that's a topic for another time I'm afraid, for the simple reason that I'm planning to make a dedicated question for said species considering how much issues I would like to ask for help about.
[Answer]
Personally, I would just prepend the family of the specific animal type whose body part(s) you're referring to.
ie: hominid-thorax or equid-thorax for a centaur. Optionally omit the family for parts that are *not* duplicated, like the head.
You mentioned that your particular species has two brains, one in each of the expected areas. However, if you had another species that did NOT duplicate organs - for example, perhaps a centaur only has a heart in the equid-thorax and does not duplicate another in the hominid-thorax because the first is capable of supplying enough blood flow throughout. In that case you might want to refer to the "fake" thorax (the one that doesn't actually contain the expected organs) as *pseudothorax* or something along those lines. And then "thorax" implicitly refers to the "real one."
[Answer]
Well the same way it already is with humans. Are the lower and upper head called differently? Yes and no.
Start talking about the head as one and then differentiate. Jaw, brain, etc.
For the thorax you would have the same as with human legs. It's all thorax, but there are maybe 30 ribs, upper left and lower left kidney, etc. Just like in upper and lower legs that are both part of the leg, but inside there are femur, tibia, patella etc. If we had two identical knees per leg, they probably be either upper and lower or medial and cranial knees. If they were different they might have separate names, but in that case you have to invent those.
So do it just as we already do. What's there twice gets named by relative position (left eye right eye) and everything that's new gets new names. Everything has a name for the whole thing and names for the parts. Medical terminology is very systematic and that system can normally be extended.
For the animal parts take the animal terminology and extend that.
[Answer]
Centaur anatomy is out of order compared to humans, but it should be possible to label them by number and type. For example: first segment (human/only head), second segment (first/human thorax), third segment (first/human abdomen), fourth segment (second/animal cephalo/thorax), fifth segment (second/animal abdomen), etc.
Although, I find it difficult to believe a hexapedal organism would have multiple torsos as opposed to one as with insects like [the praying mantis](http://www.enchantedlearning.com/pgifs/Prayingmantid_bw.GIF). It is the closest animal in real life with a centaur body plan.
I think you're the first person to ever use "centauromorph." The terminology varies depending on whoever you are talking to, but in my experience these are variations of [animal]+(cen)taur+ic/oid.
[Answer]
You answer your own question. Centauromorphs are merely analogous. Descriptions (and depictions) of them are based from 'what we know' rather than from 'what they are'.
Let's split them up first. There are those which are artificial - they are made, not born, and there are those which are natural - they are born, not made.
The former **may not be** anatomically and structurally coherent, in that they are constructed and may need support systems to survive (as found in China Mieville's Bas-Lag series). They suffer from traumatic stress and find it difficult to identify who they are against who they were.
Whereas those being who are born, not made, **are** anatomically and structurally coherent, otherwise they could not survive or breed. Their depictions may suggest multiple respiratory organs, or what-have-you, but this is the fault of the artist, not some odd structure of the being itself.
[Answer]
I had a similar issue on one of my works for a RPG setting.
I tackled this from the practical side of things. Most creatures do not follow the centauromorph structure - they are the exception, not the rule. So, the naming scheme for them is the exception, not the rule.
In my setting, those creatures' body parts are either by c- or h- followed by the bodypart name. So, a centaur would have a c-thorax and a h-thorax - the first one referring to the horse part, and the second one to the human part.
Creatures like mermaids or lamias follow a different rule - they have the head, the torso, the abdomen, and then the *tail*. Here, practicality takes precedence over correctness!
For a creature like your drider, with two different types of brains that do different things with different responsibilities, terms like *central brain* and *distributed brain* works well enough.
] |
[Question]
[
**This Query is part of the Worldbuilding [Resources Article](https://worldbuilding.stackexchange.com/questions/143606/a-list-of-worldbuilding-resources).**
---
My rivers and streams are just about as good as my waterways - that is, not too good. I do know that their paths are impacted by elevation, so I generally determine the elevation of an area before drawing in the shapes of rivers. One issue is that waterways change the shape of the land around them - a perfect example being the Grand Canyon.
* What are the processes that cause rivers to take the shapes they do?
* What processes impact the shapes of river deltas and the environments within?
---
Note:
>
> This is part of a series of questions that tries to break down the process of creating a world from initial creation of the landmass through to erosion, weather patterns, biomes and every other related topics. Please restrict answers to this specific topic rather than branching on into other areas as other subjects will be covered by other questions.
>
>
> These questions all assume an earth-like spherical world in orbit in the habitable band.
>
>
>
---
See the other questions in this series here : <http://meta.worldbuilding.stackexchange.com/questions/2594/creating-a-realistic-world-series>
[Answer]
**Headwaters**
Your headwaters are formed by three things, although not always exclusively one:
* Rainwater
* Snow Melt
* and/or an Artesian Spring (a good classification system is [here](https://en.wikipedia.org/wiki/Spring_(hydrology)#Classification))
Each has a unique geographic quality to them, and your story will have to procure the appropriate "source" of your river.
**Scale**
You already know that small creeks from runoff and rainwater form into larger and larger rivers until you have something like the mighty Columbia river.
**Types**
There are four basic types of river:
* Young - think steep, relatively deep, and short; not a lot of historical erosion.
* Created - caused by a tectonic event; [these are around](https://en.wikipedia.org/wiki/Rio_Grande#/media/File:Riogranderivermap.png) more than you might think. This will give you your grand canyons, although not exclusively.
* Mature - long, with lots of tributaries and picks up a lot of sediment along the way to dump into the sea, such as the mighty Columbia and Mississippi rivers.
* Old - a long, flat, wide river with low erosion left, such as the Nile.
**Waterfalls & Diversions**
The basics of geology, insofar as water processes, are your three types of rock:
* Igneous (very hard, granite, etc.)
* Metamorphic (like gneiss and marble)
* Sedimentary (sandstone; "soft" and easily breakable).
When an igneous rock is formed from lava - note: I'm being very elementary here, I know - it pushes up through other rock types and can form [mineral dykes](https://en.wikipedia.org/wiki/Great_Dyke) or outcroppings of very hard stone.
This means that a water body can erode the soft stone, leaving the hard stone. This is exactly what happens when a waterfall forms, for example. The softer stone was eroded away, but not the harder granite, so the water has to go over the hard stone and drop away where there once was soft stone long eroded away. Diversions happen this way too.
Another forming factor in flatlands is the soil and sediment, which can cause a river to have the long, sinewy look in very fertile parts of your world. A once-straight river pushes sediment aside, which builds up. The side that has the most becomes a barrier, so the river goes the other direction; subsequently, the faster moving (furthest) side builds up. This creates a *S-curve* as well as [oxbow lakes](https://en.wikipedia.org/wiki/Oxbow_lake).
**Deltas**
At the culmination of a river into a sea, lake or (more likely) ocean, a lot of really fascinating things happen. A mature or old river has long flattened out the end of its geology, and fans out into a delta. Because of the sediments it has brought with it, lush flora typically is present, such as that at the end of the Nile.
This also brings a lot of hungry fauna, including people. Furthering the biodiversity is the mixing of fresh and salt waters in the estuary. This is where I go fishing!
**Cultural**
I shouldn't have to stress how important rivers are, and at the risk of starting a list:
* Transportation of Goods
* Travel
* Water Supply (on mainland and islands)
* Energy Generation & Engineering
* Agriculture (leading to mythology about fertility)
* Hunting & Fishing,
... and on, and on.
**Bonus: Have fun!**
It is perfectly plausible to have in your story a [navigable underground river](https://en.wikipedia.org/wiki/Puerto_Princesa), super [short river](https://en.wikipedia.org/wiki/Roe_River), or a river whose watershed is [bigger than Alaska](https://en.wikipedia.org/wiki/Lena_River#Basin). I should think rivers of different material composition on your world ([rivers and lakes of methane](https://en.wikipedia.org/wiki/Lakes_of_Titan)?) would have a different impact on life on your Earth 2.o.
] |
[Question]
[
For purposes of this question, reincarnation works in the following manner:
* The transmissible personality, memories skills, knowledge and experiences of a person shall be referred to in this question as a Soul.
* During life, the soul develops alongside the body. At death (the moment that the soul's body ceases to be a suitable vessel to hold it, some time after the cessation of all processes of life), the soul becomes separate from the body.
* Some time after the death of its previous body, the soul may attach to a newborn member of the same species. As the newborn matures, the soul progressively integrates with the body and becomes fully integrated at physical maturity. The period of time between death and reincarnation may be as little as a second, or may be many lifetimes, though it is most commonly a relatively short period of time. It may be speculated that one or more 'bad' lives may delay reincarnation, however good lives may also delay reincarnation. There is some correlation between the reincarnation times of a particular soul. Reincarnation is not guaranteed.
* While reincarnation often occurs in a region in which the reincarnated individual lived, it need not always do so, and could theoretically occur at interstellar distances (with lightspeed delays). Reincarnation may occur into a newborn of any race or gender of its species provided that the newborn has a reasonably normal brain.
* A reincarnated individual gains the mental skills, knowledge and memories of the soul which attaches to it.
* a newborn without a reincarnated soul is not born with a soul of its own, it develops one at some point during adolescence.
* The effects of brain injury and/or illnesses such as dementia do not become part of the soul. A soul may be considered to function additively, and has no mechanism for externally applied subtractive processes.
* A soul's content degrades slightly between reincarnations. A soul which has reincarnated many times may typically remember roughly ten previous lifetimes, more if the previous lives were short, or less if the previous lives were long. More recent previous lives are more clearly remembered than older lives.
* Rarely (on the order of 1 in 100,000 reincarnations), a soul may reincarnate into two newborns simultaneously (taking lightspeed delays into consideration). Such duplicate reincarnations lead to two separate souls, the souls do not become one again after the death of both of the bodies.
* Where the species' population numbers are rising, there will be many newborns who are not born with a reincarnated soul. Where the species' population numbers are constant or falling, more newborns will have reincarnated souls, to the point where a newborn without a reincarnated soul is very rare.
Obviously there would be profound social implications for this sort of reincarnation, but they are *not* the point of this question. However, the social implications will have to be addressed if they could affect the evolution of the species.
My question is, What effect would reincarnation have on a species?
As an example, humans do not *demonstrably*, frequently and reliably reincarnate. However, for purposes of this question, let us suppose that at the time that hominids speciated from chimpanzees and bonobos, roughly 5.5 million years ago, the hominids gained the ability to reincarnate. If all other selection pressures remained effectively identical and evolution progressed similarly wherever reincarnation has no evolutionary effect, what differences could we expect between real-life humans and reincarnating humans after a similar period of time since speciation 5.5mya?
These differences need not be purely physical, and may be differences in the basic psychology of the species.
**Edit**
There seems to be some confusion as to how souls work. They do *not* function as a metaphysical cloud storage that's accessible at any time, like a google drive account that's able to have its content downloaded into RAM relatively quickly.
Rather, a soul's content must be copied into the physiological memory of the body during maturation before it becomes accessible, and any content that is in excess to that which the body can retain is culled according to the usual physiological processes that discard or overwrite less useful memories.
After the body's brain is physiologically mature, the soul isn't able to add much more of its content to it, perhaps only 5% of that gained during maturation.
The process by which memories of former lives may be lost is that memories successfully written into the body are removed from the metaphysical soul. During life, a new soul is written from the body's brain. When the body dies, the remainder of the old soul is copied in a slightly lossy manner to the new soul before the new soul goes on to be reincarnated... when and if it does so at all.
Perhaps 1 in 20 souls do not reincarnate at all, and perhaps 1 in 6 do not reincarnate 'immediately' (within a single typical lifespan of a member of the species).
[Answer]
One thing to consider is that accumulation of experience as a creature ages tends to soldifiy past beliefs and patterns behavior to a degree that they no longer are changeable. "*You can't teach an old dog new tricks*" as they say and we've all met older people which we politely describe as "set in their ways". However, this can be highly deleterious; the learned behaviors of an individual who has a lifetime of experience for survival in a jungle will not be all that useful when transmigrated to the body of an individual born in a sub-arctic environment.
Its unclear how the body affects the soul in this scenario, but it seems likely that there will be strong evolutionary pressure toward the neuroplasticity of childhood to last into adulthood to allow the individual to learn new behaviors and overwrite old ones that are harmful in the soul's new environment as well as for increased propensity for risk-taking to help the individual overcome no longer appropriate learned behaviors.
[Answer]
## Regression in both evolution and also society - and it may be quickly lost.
The important thing to remember about evolution is that it is the **genes that are important, not the individual**. The incremental improvement of genes relies upon the death and selecting out of non-beneficial genes.
So if an organism, say a flying insect such as a house fly, flies into a spiders web and is eaten - it is reborn and remembers now where the spiders web is, and avoids it.
This pattern repeats many times, meaning two things: The fly never actually dies (although eaten) and does not evolve a keen sense of sight to detect the web, and the spider has to also evolve and step up its game in order to catch the fly (perhaps using more and more larger webs, or creating a situation where the fly has no ability to evade the web even if it remembers where it is). Both organisms adapt gradually, however the fly regressively so.
Basically, **the removal of 'survival' imperative from the genome means the genome does not have as much incentive to incrementally improve**. The ability to transfer souls would actually over time *would actually be lost*.
This also happens to Homo Sapiens in society. If someone dies, but their soul appears in another, there is no real incentive to stay alive. **Some of the worlds best inventions are based on necessity, and perhaps even the fear of death - remove this and the tenuous web of society may never have formed**.
[Answer]
# Clever, Strong, but with Poor Memory:
Your species are subject to the same forces that affect anything else. Evolution only drives the development of things that are rigorously reinforced, and leads to the degeneration of traits over time with low or no survival advantage. So what happens with your species with reincarnation?
Your individuals are able to survive despite having a poor memory, because your souls are providing multiple lifetimes of experience to the bodies they inhabit. An organism doesn't need a great memory, but it does benefit from being clever.
Culture would evolve somewhat independently from biology, and I think there would be a strong pressure for a more altruistic culture with collective child-rearing. There may be some social pressure to weed out souls with poor attitudes, but how this would manifest would depend greatly on choices and how your reincarnation system worked.
I'm assuming souls have some options in what bodies to inhabit, so whatever traits the souls prefer will create a pressure for bodies to match it. Everyone wants a clever host. And physical prowess disproportional to the needs of biology may be selected for due to the souls desiring to be strong. I'll assume the souls can somehow evaluate whom they inhabit as well (either through genetics or the ability to perceive the mother).
Reproduction may need to be a very hormone-driven process, as intelligent organisms will intellectually feel less tied to their bodies and will be less driven to have kids. Kids will grow much faster, and need a greatly reduced period of learning, since memories of past lives mean they are ready to be adults intellectually the moment they are born.
Then there are surely opinion pressures that will matter based on what the souls prefer. If souls remember being bonobos, then they may tend to select bodies that are bonobo-like. If they like variety, then the bodies will become dimorphic, so the souls can mix things up between lives. If there are standards of physical beauty, they may inhabit the offspring of pretty females.
[Answer]
## Very little change
Since the memory is not immediately copied and can easily be over written, it is unlikely that reincarnated people will have much if any advantage. Therefore, not much change will be imparted upon the species in the form of beneficial mutations.
## here lies andy; peperony and chease
[In the Paleolithic Era, only around 60% of humans even made it to be 15 years old](https://en.wikipedia.org/wiki/Life_expectancy). So a person might not even know if they were reincarnated, since they are about as likely to die first as they are to survive.
## I have no memory of this place.
One thing a prehistoric person might want to remember is the migration patterns of prey, the creation of basic tools, or which plants are poisonous. However, by the age the reincarnation memories kick in these people will probably already know this stuff. Furthermore, the migration patterns of arctic prey is of little concern to someone living in a desert. So unless they reincarnated very close to their last life, it is possible all this information will get overwritten, or at least ignored, since it isn't helpful. Also, if they remember that they were a tool maker in a previous life, but now they are a hunter, if hunting is the better profession, that information isn't very useful.
## Intercontinental Tool design collaboration
One advantage would be remembering previous tool designs. This might have a minor effect on the effectiveness of tools over the entire population. This means the whole world would have the most effective bows, slings, knives, and fire starters for their region after a few cycles. This wouldn't require any changes to the genome, and any change that could be made won't help.
## prehistoric Career fair
One of the few advantages this provides is if the previous life did a job that is difficult to learn or teach, that can also be done here, the reincarnated individual can do that job. If this person were a leader this also applies. However this has very little effect on the society, and therefore modifying everyone's brains to have more space to maybe remember more lives would have a negative instead of a positive effect.
## Results
While a few people in the prehistoric times could use this to their advantage, the effects are too small to make changes to the species beneficial enough to justify the potential cost. The ability to learn from your ancestors would help people, but many people during this time learned from their ancestors by talking to them, and were prepared for the world mostly by adolescence. Therefore expensive changes to the brain would not be worth it for a fairly circumstantial benefit.
] |
[Question]
[
What I "want":
My fantasy world has lots of volcanos. Deep under the surface there is a root-like form of life predominant. It grows in big bundles and searches for important minerals, gases, fluids, etc. to feed a big network of itself. When an attempt of finding resources has failed, all the roots that dug in that direction just die instantly and get eaten after by small rat-like creatures. Some smaller roots around will stay, stabilizing the structure a bit. Some of these caves will just cave in, others will probably hold.
Now what I want are sulphurous rivers flowing through some of these caves. When a part of one of the caves collapses, what's left in the part where the water is cut off is a yellow riverbed. This riverbed may be inflammable. Wouldn't that be cool? A blue flamestorm blasting through a system of big yellow caves?
---
## Question
1. Is it likely that my caves can be "generated" in the described way?
2. Will the sulfur crystallize in the riverbed while it's mixed with flowing
water and how much of it would have to be in there e.g. per gallon? (in case of it not being likely to happen)
3. Is there anything important about sulfur I don't seem to know?
---
[Answer]
# Cave formation
This setup reminds me of [rhizomes](https://en.wikipedia.org/wiki/Rhizome), which are essentially underground root systems that can spread out underground, sending up new seedlings at various intervals. Rhizomatic root systems make colonies of [aspen](https://en.wikipedia.org/wiki/Aspen) possible, and colonies can be both massive and long-lived. If one tree dies, another one can start growing in its place, or somewhere else in the colony.
This seems, in a sense, similar to what you're asking. You've got a giant network of roots extending through the soil searching for nutrients, and rhizomes do basically the same thing - they just usually have plants grow up through the soil, rather than further down.
# Sulfur formation
A commonly-occuring yellow sulfur crystal is [octasulfur, or $\text{S}\_8$](https://en.wikipedia.org/wiki/Octasulfur). $\text{S}\_8$ is often produced by volcanoes, but can also be [made by humans](https://en.wikipedia.org/wiki/Claus_process). Volcanic elemental sulfur often contains a large percentage of $\text{S}\_8$ by mass, and this is a good thing, because there may be a natural way to seed your riverbeds.
[There are lava tubes and subterranean caves on Mars](https://worldbuilding.stackexchange.com/a/63820/627), some of which formed through mineral processes (e.g. involving limestone) and some of which formed through [the cooling of lava](https://en.wikipedia.org/wiki/Martian_lava_tube). Now, it's possible that your world could have pockets of lava tubes deep below the surface, and it's *also* possible that those tubes could have $\text{S}\_8$. Your rhizomatic roots therefore don't even have to form new tunnels; they could already exist, and might simply be expanded by the invading plants.
$\text{S}\_8$ melts at 392 K (119$^\circ$C, 246$^\circ$F). This means that to have actual rivers of sulfur, you'd need to raise temperatures to this point. However, the boiling point of water is 100$^\circ$C, meaning that water should be gaseous at temperatures where sulfur is liquid. We therefore have a problem; we can't really have a river of liquid sulfur and water except under extreme conditions.
Therefore, it seems much more likely that the already-existing crystallized sulfur will remain crystallized, or at least in a solid state. Another possibility is that we change the ambient pressure, as boiling and melting points are pressure-dependent.
[Answer]
You are not looking for **sulfur**, you are looking for **[sulfate](https://en.wikipedia.org/wiki/Sulfate)** and **[sulfide](https://en.wikipedia.org/wiki/Sulfide)**.
Let's start at the beginning. Sulfur (the yellow stuff) is elemental sulfur. It is not soluble in water, and pretty hard to make it burn, unless you ignite it. However, you can oxidise it to sulfate, or reduce it to sulfide, where it is much more reactive and can participate in interesting chemical reactions, some of which are rather spectacular. This is not hand waving - on Earth, most of the (inorganic) sulfur is in one of those two states. Elemental or native sulfur is rather rare.
You want your organism to look for:
>
> important minerals, gases, fluids, etc. to feed
>
>
>
One possibility is the reduction of sulfate. Sulfate is oxidised sulfur: SO42-. There are [bacteria that reduce it](https://en.wikipedia.org/wiki/Sulfate-reducing_microorganisms) in order to feed. So you can have your soil rich in sulfate (for example [gypsum](https://en.wikipedia.org/wiki/Gypsum), [epsom](https://en.wikipedia.org/wiki/Magnesium_sulfate)) and then your organism feeds on that.
You can have sulfate seams in the ground that your organism follows, and then once a seam stops, the organism dies. Explaining the sulfate seams is easy: all you have to do is have a dry environment in the geological past to form [evaporite deposits](https://en.wikipedia.org/wiki/Evaporite).
Now the fun part. What happens when the organism dies? You now have a decomposing mess of carbon and reduced sulfide (S2-). Some of this reduced sulfur might form [pyrite](https://www.google.com/search?tbm=isch&q=pyrite&tbs=imgo:1), also known as fool's gold. Spectacular shiny crystals of iron sulfide. Some of it might form hydrogen sulfide (H2S), a very stinky and flammable gas. The carbon will serve as a sink for oxygen forming CO2, lowering the availability of oxygen for burning of the sulfides. This allows the sulfides to accumulate.
Now comes the cave in! At an instant you expose everything to the atmosphere including oxygen. The hydrogen sulfide [ignites](https://www.youtube.com/results?search_query=burning%20h2s), burning the pyrite as well. Some of the burnt gas might deposit as yellow crystal of native sulfur. The oxidation of the sulfides then leads to something that may look like modern [acid mine drainage](https://www.google.com/search?tbm=isch&q=acid%20mine%20drainage&tbs=imgo:1).
] |
[Question]
[
For this question, assume that the planet is Earth-like in almost every way, and is in a system like ours...the distance from the sun, orbital period, rotation, axial tilt, etc is all pretty much the same as Earth now - except this planet's radius and mass are reduced such that the gravity on the surface of the planet is half that of our Earth's. That means that the radius of this planet is $\frac12\ a\_\oplus$ (1/2 Earth radius). Keeping the ratio of land mass to bodies of water, let's assume that oceans and continents are about 1/4 the size that they are on Earth.
The air density/atmospheric pressure at any given altitude is about 1/2 that of Earth's.
Could storms on this planet be as violent as storms on Earth? What would it be like in a hurricane?
[Answer]
Leaving aside the issues Youstay has raised we can look at answering the core question:
There is one factor here that is going to over-ride everything:
* Reduced atmospheric pressure. With atmospheric pressure of 50% earths you may well have massive fast moving impressive looking storms. However their ability to carry debris and generally cause damage will be drastically reduced. It is objects being carried by the storm that normally cause the damage, not the wind speed by itself. Lower pressure air will both do less damage in the first place, and also find it harder to carry and accelerate objects.
The other reasons I expect the weather to be less severe is:
* Lower gravitational gradients mean there is less difference between
layers of the atmosphere and the layers are further apart.
* The smaller world probably means there is less temperature difference
between poles and equator, again reducing the power available to
drive weather systems.
However the actual effects of the weather might be felt more:
* Lower gravity means it's easier to lift up debris and carry it with the storm.
* Even things that cannot be lifted can be moved more easily.
* Lifeforms would be evolved to suit a lower-gravity environment. This may well make them tall and fragile, more vulnerable to storms.
One thing that would not be different is:
* The [Coriolis Force only depends on angular velocity](https://en.wikipedia.org/wiki/Coriolis_force#Formula) so has the same strength no matter what size the planet. (Thanks Khris)
So storms would not form as often and would be weaker. When they do form they may be visually impressive or very large but the reduced atmospheric pressure will vastly reduce how much damage they can do.
[Answer]
First off, I'm afraid that the details you mentioned in your question statement are not logically possible. I should have stated that in a comment, but considering how lengthy it would get and how many laws of physics are involved, I thought it better to post it as a complete answer.
**Error #1**
>
> this planet's radius and mass are reduced such that the gravity on the surface of the planet is half that of our Earth's. That means that the radius of this planet is $\frac12\ a\_\oplus $ (1/2 Earth radius).
>
>
>
If the planet has 1/2 of Earth's radius then its gravity would be 1/8 of Earth's gravity, not 1/2 of it!! This is why:
Volume = $\frac43\pi r^3$
So if the radius of the planet is 1/2, the difference in volume would be $(\frac12)^3 = \frac18$
Considering the aggregate density to be the same (as stated in your question body), the total mass of the said planet would be 1/8 the mass of Earth which would give it 1/8 the gravity of Earth.
**Error #2**
>
> Keeping the ratio of land mass to bodies of water, let's assume that oceans and continents are about half the size that they are on Earth.
>
>
>
The same thing applies here, only to a factor of 1/4 instead of 1/8.
Surface area of a sphere = $4\pi r^2$
If you keep the same ratio of sizes, then the size of water bodies would be 1/4 the size of water bodies on Earth, not 1/2.
Well, this was just a cosmetic issue and I brought it up only for the sake of correction. This is not as serious as the error in gravitational force.
**Error #3**
>
> The air density/atmospheric pressure at any given altitude is about 99.5% that of Earth's.
>
>
>
For a planet 1/8 the size of Earth, the atmospheric pressure **cannot** be the same as Earth's at any two given altitudes! The altitude versus atmospheric pressure graph for the given planet would be vastly different than that of Earth, no matter how thin or thick you make its layer of atmosphere.
So ... correction in planetary details, perhaps?
[Answer]
Take a look at the equations for the [geostrophic wind](https://en.wikipedia.org/wiki/Geostrophic_wind#Governing_formula).
First the hydrostatic equation:
$0 = -g - \frac{1}{\rho} \frac{dP}{dZ}$
Rewrite it as:
$g \rho = -\frac{dP}{dZ}$
This tells us that the density of the air multiplied with the gravitational acceleration equals the negative vertical pressure gradient.
Therefore having only half of Earth's gravity makes the vertical pressure gradient only half as steep. Added to that less gravity would mean that the planet won't be able to hold as much atmospheric mass so the density of the air will be lower as well decreasing the vertical pressure gradient even further.
Second the geostrophic equations:
$fv=\frac{1}{\rho} \frac{dP}{dX}$
$fu=-\frac{1}{\rho} \frac{dP}{dY}$
The first one says that the meridional wind speed times the Coriolis Parameter equals the zonal pressure gradient times the inverse of the density.
The second one says that the zonal wind speed times the Coriolis Parameter equals the negative meridional pressure gradient times the inverse of the density.
The Coriolis Parameter only depends on the angular speed of the planet's rotation and the geographic latitude. As your planet should be rotating as fast as Earth the Coriolis Parameter will be the same.
If you reduce the density in those formulas while keeping the rest the same you get an increase in wind speeds with the same horizontal pressure gradients.
This makes sense since a less dense volume of air has less mass and therefore less energy is needed to accelerate it to a certain speed.
But in this situation the vertical pressure gradient is flatter so it's questionable if the same horizontal pressure gradienst as on Earth are even possible or if those are decreased as well, and I think they are. If they are the situation is similar to Earth, otherwise you'd get higher wind speeds.
Keep in mind however that lesser density - which is certain on your planet - means that the winds have less impact overall, since there is less mass in a volume of air there is less impulse. So in general I'd say your windstorms might get faster than on Earth but certainly not more devastating, more likely the opposite.
With Hurricanes there's also the question of vertical convection. With the flatter vertical pressure gradient convection will generally be weaker, so thunderstorms and tropical storms will generally be weaker as well.
[Answer]
Because the question is messed up it does make it harder to answer. Half the mass and half the radius gives a g for the new planet a 1.96 m/s^2 value instead of 9.8 m/s^2. That's less than the acceleration due to gravity on Mars with 3.71 m/s^s. Something important to note on a planet with less gravity is that it is less capable of holding the atmosphere. Mars atmosphere is so thin the wind hardly exerts a force at all. It does have massive storms that can last for months, but the particles picked up are very fine. The max winds witnessed on Mars were 175 kph. This would feel like approximately a 10 mph wind. It's one of the flaws in my favorite book, the Martian. What you want is a planet with the same radius and half the mass of Earth, which would give you half the acceleration due to gravity as that of Earth, but I'm not really certain how thin the atmosphere would get. But that would make everything else about the same, right? Coriolis effect is the same assuming the same rotational speed. Amount of the sun's energy incident on the planet would be the same. But with less gravity, water particles would evaporate easier, due to less pressure.
I'm guessing that the storms would be less damaging. They might be as severe, meaning wind velocity, but less damaging. With half the gravity fixed items like concrete, steel, wood, could potentially have the same strength and therefore be less effected by it. Loose items would be lighter, though and more easily picked up. I think the bigger problem relates to how dense the air is on this planet. Drag is directly proportional to density of the fluid, so half the density, half the force due to drag. A 100mph wind would feel like a 50mph wind. I hope this helps.
[Answer]
Trying to address the actual question
This related response may be of interest concerning the effect of low gravity on storms
[Storms on a low-gravity planet](https://worldbuilding.stackexchange.com/questions/28115/storms-on-a-low-gravity-planet)
It would appear that low gravity tends to return wind speed so less severe weather would be expected. Also as already pointed out increased air density would also reduce the intensity of the wind so all in all the atmosphere would be a great deal calmer than that seen of Earth. So the answer is no storms on this world could not be as violent as those on Earth.
] |
[Question]
[
In [this question](https://worldbuilding.stackexchange.com/q/10901/75), I asked about a matter-filled 4-spatial-dimensional universe, with a gross structure defined by my own [answer](https://worldbuilding.stackexchange.com/a/12993/75) to that question.
Then, in [this question](https://worldbuilding.stackexchange.com/q/13094/75), I asked about what the periodic table would look like, assuming that something like classical atoms could exist.
Now, assuming that there is a 4D Carbon-analog element that can form complex structures alone and in combination with other elements, what can we expect living organisms in such an environment to be like?
We can assume that there are generalities that apply in both 3D and 4D, such as [autotrophy](https://en.wikipedia.org/wiki/Autotroph)/[heterotrophy](https://en.wikipedia.org/wiki/Heterotroph) and reproduction.
These 4D organisms do not need to interact with a 3D-universe — they exist and interact solely within their own 4D-universe.
Specifically:
1. What — aside from occupying an extra physical dimension — would need to be different between a 3D and a 4D organism? What is likely to remain the same?
2. What would a 4-dimensional lifeform be able to do that a 3D lifeform cannot? What new structures are possible and are any existing structures more efficient in 4D than in 3D?
3. What can a 3D lifeform do that a 4D lifeform cannot do? What 3D structures do not function and are any existing structures less efficient in 4D than in 3D?
4. Are any [symmetries](https://en.wikipedia.org/wiki/Symmetry_in_biology) more likely in 4D than in 3D?
[Answer]
Well, the first obvious difference would be that the square-cube law would basically be replaced by a cube-tesseract\* law. Since 4/3 is closer to 1 than 3/2, this means that there could be greater variations in size. Another difference is that more of the (hyper-)volume is close to the (hyper-)surface. Since this means that important organs are closer to the surface, probably organisms would grow thicker protective skins. On the other hand, plants would probably profit from the increased surface/volume ratio, as they could keep relatively compact form and yet present a large surface to the light. Therefore I guess leaf structures would be less common, or otherwise, plants developing those would have more energy at their disposal, allowing them to evolve some more sophisticated abilities.
Since the floor would be three-dimensional, you'd need at least four legs on the floor for a stable standing (instead of three, as in our three-dimensional world). Therefore for an insect-like moving pattern, you'd need 8 legs. Coincidentally, if you extrapolate the four-legged pattern of the land vertebrates to four dimensions, you also get 8 legs. Therefore I conjecture that eight-legged animals would be common in four dimensions. Probably the typical four-legged animal would be long on one horizontal axis, and when looked on from above (so you get a 3D projection, similar to the 2D projection when looking at out animals from above), you'd basically see an ellipsoid with four left attached close to the front, and four close to the back, each arranged in a square. A stable standing would be achieved with two diagonally opposed front legs, and the two back legs on the other diagonal. From that fact, possible walking patterns could be derived.
When moving to an upright position (similar to humans), those creatures would walk on their four hind legs (interestingly, unlike our two foots in 3D, those four legs would still be enough to provide a stable stand without the help of specially formed feet, if positioned right), and have four arms available for manipulating things.
\*) A tesseract is the four-dimensional equivalent to a cube.
[Answer]
Radial Symmetry in 4d would be like bilateral symmetry in 3d. A life form living in four spatial dimensions that has legs would likely have radial symmetry instead of bilateral symmetry. They would likely have at least five sides as five is generally the minimum number of sides for any type of radial symmetry on Earth. An organism in 4d could also rotate as it walks without turning around because it can rotate around its sides.
One thing that would be different is that a river would not be a natural boundary for none avian life forms in 4d meaning that rivers could not cause speciation events in the way they do in 3d. This means that sympatric speciation events would likely happen less often in 4d as natural boundaries would be less common in 4d. Speciation events can result from selective pressure as well though and I'm not sure how the rate of that would be effected by 4d. So one thing a 4d life form could do that a 3d life form could not is get around a river without going over or under it.
In 4d it would be possible for two organ systems to pass through each other without ripping each other apart. Hair getting tangled up would not be a problem so long as the hair consist of one dimensional strands because if it formed knots the knots could simply be untied through yanking.
In 4d the surface area to volume ratio is slightly larger than in 3d meaning that things would have slightly less volume per surface area than in 3d. This would barely effect life though because the difference in the surface area to volume between 3d and 4d is only 4/3 meaning that the difference in cell size between organisms living in 4d would likely be greater than the difference between cell size in 4d and 3d.
A brain would need to be larger and more complex in order to process information from it's environment.
] |
[Question]
[
Time travel on movies and tv always say they were able to tell the year by looking at the
stars. But how?
For example Voyager goes back in 1996 and Ensign Kim says astrometrics puts them in the year 1996. In the movie Timeline they said they sent probes and pointed it's cameras at the night sky and determined the date.
>
> http://www.chakoteya.net/voyager/304.htm
>
>
>
>
> Star Trek Voyager
>
>
>
>
> JANEWAY: The question isn't where we are, it's when we are. Mister Kim.
>
>
>
>
> KIM: According to astrometric readings the year is 1996
>
>
>
>
> http://www.script-o-rama.com/movie\_scripts/t/timeline-script-transcript-michael-crichton.html
>
>
>
>
> Timeline movie
>
>
>
>
> That's when Mr. Doniger made the brilliant decision to point the camera straight up. So once we cross-referenced star charts to the horizon, we realized that the camera was not only in the wrong place,- but it was in the wrong time.
>
>
>
My problem is my **accidental time travelers** are amateur astronomers/stargazers (they also **have Stellarium software or equivalent** and laptops), and I want them to at least be able to isolate the year or decade they time-jumped to.
I was planning to use **Barnard's Star** as the easiest reference. **Am I wrong? Is there an easier way?**
>
> https://oneminuteastronomer.com/8869/barnards-star/
>
>
>
>
> Barnard Star’s main claim to fame is its large proper motion, the angular change of its position across the sky. It moves about 10.4” per year, more than any other star, which is a result of its true motion through the galaxy and its proximity to our solar system. **Over an average human lifespan, the star moves about a quarter of a degree or about half the diameter of the full Moon.** In astronomical terms, that’s mighty fast. - See more at: <https://oneminuteastronomer.com/8869/barnards-star/#sthash.xGxKkwnN.dpuf>
>
>
>
This is what Ensign Kim (Star trek Voyager) should see in 1996 if using Barnard's Star. Sorry about the zoom factor I wanted to show the Ophiuchus constellation.
Kapteyn's Star is second highest then Groombridge 1830 third highest proper motion are also possible choices.
[Answer]
The technique should work. I can't really say much besides that.
There are other things they could do, too. They might not be easier than tracking the [proper motion](http://en.wikipedia.org/wiki/Proper_motion) of a star, but they'll work:
* **Use [variable stars](http://en.wikipedia.org/wiki/Variable_star).** Most variables stars have regular periods hat can (and have been, in many cases) determined. They can also be used to figure out the exact date. Here's how:
Take a star - $A$ - that has a period of $P\_A$. It has a [light curve](http://en.wikipedia.org/wiki/Light_curve) that remains constant over time. [Here's](https://upload.wikimedia.org/wikipedia/commons/6/6c/Delta_Cephei_lightcurve.jpg) an example: the light curve of Delta Cephei:
During each cycle, the star reaches a given brightness twice (unless the brightness is he maximum or minimum brightness), unless it is an eclipsing binary. So you can figure out that at a given brightness, it is at one of two points in its cycle. Observations a short while later can confirm the exact point by seeing how the curve changes.
After taking these measurements, you know at what point in the cycle you're in. If you know the point in the cycle the star was at when you left, you know the star has been though $a+n\_A$ cycles, where $a<1$ and is the amount of cycles the star would have gone through if $n=0$. You can figure out $a$; now you need to find $n\_A$.
Take a second star, $B$. It has a period of $P\_B$, and another light curve. You can figure out, as before, that it has been through $b+n\_B$ cycles. These two stars should have different periods; this configuration only arises within a given amount of time that is *longer* than $P\_A$ or $P\_B$.
Continue this with more stars, and you can better figure out what $n\_A$ and $n\_B$ are. Given that variable stars can have extremely long and extremely short periods, this can help refined your other measurements to high accuracy.
As far as I can tell, there aren't any other methods involving stars that your spacefarers could use. They need to observe things that predictably change with time. On a larger scale, they could use thee expansion of the universe and the recessional velocity of galaxies, as dictated by the [Hubble parameter](https://en.wikipedia.org/wiki/Hubble%27s_law), which changes with time. But it's extremely hard to measure to any usable accuracy.
[Answer]
It depends on how far they've traveled, and if they've got a rough idea of when they are.
* **Days**: If you know when you are to within a month or so, the [Galilean moons of Jupiter](https://en.wikipedia.org/wiki/Galilean_moons) can tell you when you are to a precision of hours or less if you've got a good pair of binoculars.
* **Months to years**: If you know which century you're in, you can pin down the date to within a month or so by observing which planets are visible at night, and what constellations they're in.
* **Centuries to millennia**: Over longer time periods, Earth's orbit shifts and the constellations themselves change. Where is Barnard's Star? Which star is closest to the North Pole? Is SN 1006 a star or a nebula? What shape is Ursa Major?
* **Longer periods**: Beyond a hundred million years or so, there's no good way to figure out the time. The Solar System has a [Lyapunov time of around 200 million years](https://en.wikipedia.org/wiki/Stability_of_the_Solar_System): it is effectively impossible to predict positions that far out from current conditions. Many of the bright stars have lifespans shorter than this. The longer-lasting stars are dim enough that they move out of amateur observational range over this timescale. Your best bet is geologic rather than astronomical: radioisotope dating of rocks, or measuring the U-235/U-238 ratio of uranium ore.
] |
[Question]
[
I am writing a plot for a project I am working on, and I need to know if there is a poison that kills/incapacitates quickly (within 1 hour) when eaten, but has little effect upon injection. It needs to be toxic at less than 50 ml. I need it to be ineffective in the blood as part of an assassination plan.
[Answer]
I propose a more mechanical solution: [nanocapsules](https://en.wikipedia.org/wiki/Nanocapsule). Take the poison of your choice, wrap tiny droplets of it in tiny hollow spheres, which should dissolve in stomach acid but not under white blood cell attack. At least not at the same rate: if the poison is released in a matter of minutes from stomach acid, but the blood takes days to do the same job, in the latter case the poison may be handled by the body at an acceptable rate and not kill the victim. It also helps if a few days is enough time for the poison itself to degrade and become inert.
I don't have any specific materials for you, partially because this science is relatively new, but there are a lot of proven and suggested mechanisms for the release of nanocapsule contents, including infrared light and ultrasound, so I do not think a chemical release mechanism is out of the question.
[Answer]
A substance that is non-poisonous when in a neutral form but became a poison on acidification might work. Such a substance could circulate in the neutral or slightly alkaline pH of the blood stream where it could be metabolized and removed from the body. But if ingested would change its form on contact with strongly acidic stomach acids leading to the formation of the poison.
I am not aware of any such substance, but I am fairly confident that such a thing could be synthesized. There are chemicals which undergo chemical changes across the pH range of interest such as [Bromothymol blue](https://en.wikipedia.org/wiki/Bromothymol_blue). I don’t think this is particularly poisonous in either form but might well be chemically modified to be so.
There are a number of chelating agents used to absorb specific heavy metal poisons
<https://www.sciencedirect.com/topics/earth-and-planetary-sciences/chelating-agent>
With sufficient development is should be possible to develop a substance that would bind to a metal at blood pH and allow the chelated metal to be slowly filtered from the blood stream, but release the metal ion rapidly in the acidic conditions within the stomach.
[Answer]
**There should be**
I don't have a real life example ready, but there are as far as I know many molecules, not necessarily poison, that work that way. It's because of bindings. Let's look at it at a high over more or less correct way.
Some molecules are bound to others. This makes them act differently. This differently can be harmless, beneficial or bad. Look at sugers. They are often stored in long chains to each other like glucose. But this in itself doesn't help the body. They can only work when taken apart, freeing the bound energy when a free molecule is then paired with some enzymes. Another are things like ethanol. It isn't healthy in the blood, but it's the breaking down of the ethanol that produces the bad molecules. These are examples for things inside the blood, which is not what you want, but they are important as examples.
This idea is very important. Something directly into the bloodstream can be harmless, or at least not deadly/incapacitating. The processes there can possibly not unbimd or change these molecules, allowing you to piss or shit it out again. In contrast, via indigestion all kinds of special processes happen to break down and change the food. Acids, enzymes, bacteria and finally the passive/active diffusion into the blood, with first passage through the liver, can all change the molecules. Things that were bound can be freed, or some processes van result in new molecules with different effects, allowing it to roam free and start it's potentially harmful process. Imagine a solution of saltwater they use in hospitals bound to CO, Carbon Monooxide. In this fictional example, it might be harmless in the blood. It'll not react and get unbound. But if it passes through the digestion system, it could be broken down by a number of things. The CO is very good at diffusing into the blood, which we know from the lungs, which then can populate the red blood cells and basically suffocate someone.
So in short, you need something (relatively) harmless or even beneficial when directly put into the blood. But if eaten the processes can make something very lethal. I'm pretty sure someone can give real life examples.
] |
[Question]
[
**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.
This came up when running some numbers on the hard science possibilities of interstellar colonization and I mostly want to know whether I made some major errors and am off by a few orders of magnitude somewhere.
First, assuming the speed of light is an absolute bound, any possible space ship needs to be completely autark, that is have everything it and its passengers will ever need on board. So it needs to be pretty big. I will just assume a cube of 10km edge length. Putting a density of 1 (high density building material filled with air) this gives a mass of $10^{12}$ tons.
Second, if you want to get to any other stars within human life spans you need a speed that is a decent proportion of the speed of light, say $0.5c$.
To compute the fuel needs to accelerate $10^{12}$ tons to $0.5c$ (and then decelerate to zero again) we use the rocket equation, for example [here](https://www.omnicalculator.com/physics/ideal-rocket-equation). An exhaust velocity of $1c$ and a target speed of $0.5c$ gives us that we need approximately as much fuel as the mass we want to accelerate (the calculator gives $40\%$ fuel and $60\%$ ship weight).
To achieve an exhaust velocity of $1c$ we will use an antimatter drive. The antimatter will be made from the energy from our sun. The total energy output of the [sun](https://en.wikipedia.org/wiki/Sun) corresponds to converting $4\*10^6$ tons of matter to energy per second. So if one is able to capture the entire energy output of the sun, one would need about $10^{12}/(4\*10^6)=2.5\*10^5$ seconds or around 7 hours.
Meaning in summary accelerating a single ship of this size to around half the speed of light would already take the complete energy output of our sun for a several hours assuming $100\%$ perfect efficiency in every step. So we are talking a full Dyson sphere, not just some large solar sails. Does that make sense of did I miss something major somewhere?
**Edit** (in response to comments): I was indeed thinking of a fully self sustaining colony ship and that does require millions of people on there. The entire computation is also linear in the mass, so if you are interested in the numbers for a smaller ship, you can simple divide the needed energy by the same factor that you reduce the mass. Similary $100\%$ efficiency is easiest to look at because one can account for lower efficiency by simply multiplying in whatever efficiency one wants to use.
[Answer]
You've got a few minor errors in there... it is easy to do, and a good reason for doing all your working in a program or spreadsheet or a mathmatical modelling tool or whatever. The obvious mistake is 250000 seconds is *70* hours, not *7*, and you're applying your mass-creation rate to the total mass of the ship.
Here are my workings and results:
For a delta-V of 1c and an exhaust velocity of 1c (and ignoring relativistic effects, which is slightly naughty but not *too* naughty at only .5c max velocity) you end up with a mass ratio of e (~2.7), this is because the [rocket equation](https://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation) gives us $R = e^\frac{\Delta\_v}{V\_e}$. If your total launch mass is 1012 tonnes (I'll use the metric ones here), that means you'll have a dry mass of 1012/$e$, or ~3.7x1011 tonnes, NS ~6.32x1011 tonnes of fuel. That's more like 63.2% fuel, 36.8% ship.
(I note that if you had a delta-V of 0.5c, so only enough to get up to cruising speed and not to slow back down again, you do end up with a mass ratio of $\sqrt{e}$, which would be reflected as a launch that was 60% ship and 40% fuel, which were the figures you originally came up with.)
Your fuel will only be 50% antimatter. This makes the next bit easier, because when you're conjuring up matter ex nihilo, you end up with equal amounts of matter and antimatter because of the [conservation of baryon number](https://en.wikipedia.org/wiki/Baryon_number#Conservation).
Assuming a perfect conversion of energy to mass, e=mc2 shows you need 6.32x1011 x c2 or ~5.68x1031J of energy. The [sun's luminosity](https://en.wikipedia.org/wiki/Solar_luminosity) is 3.828x1026W. If you harvest 100% of that, it'll take you ~148412 seconds (or a little over 41 hours) to create the required mass of matter and antimatter.
If you meant [short ton](https://en.wikipedia.org/wiki/Short_ton) instead of [metric tonne](https://en.wikipedia.org/wiki/Tonne), your mass requirements are dropped slightly, and it will take more like ~134637 seconds to generate the required matter and antimatter, or about 37.4 hours.
There are better ways to do what you want to do (for a start, using magnetic braking at your destination instead of a bajillion tonnes of antimatter) but that's a bit outside of the scope of this question. You might ask a different question about how to reduce fuel demands without compromising journey time.
] |
[Question]
[
I need to generate some characters for my world, and at the moment, inspiration fails me.
Now, before you reach for the 'Close' link, I'm not asking for the WB community to help me with character design - that's *my* job. I'm looking for character design *resources*.
What resources - preferably online - exist that provide lists of occupations for various time periods throughout history? Preferably with the percentage of the population that engaged in that occupation at that time, but a simple list will do.
Additionally, are there any resources that provide similar occupation data for a fantasy/magic - based world?
I am looking only for a list of occupations for any given place and time. Nothing else. While my setting is similar to renaissance Europe, and includes magic, I can extrapolate from a non-magical setting.
[Answer]
I don't have a global answer for any time period. But some specific instances of lists of professions follow in somewhat chronological order.
* There is a Mesopotamian text called the "Standard Professions List" that lists about 100 professions. The translation can be found in a library.
* Ancient Greece, list of jobs for men and for women: <http://www.rwaag.org/gjobs>
* List of occupations in Rome: <http://www.tribunesandtriumphs.org/roman-life/ancient-roman-jobs.htm>
Stackexchange won't let me post more than two URLs, so I can't list the other links directly, but I will post the google queries that will lead you to the links (should be the first link showing)
* "Mesoamerica list of Aztec jobs" should land on the [legendsandchronicles](http://www.legendsandchronicles.com/ancient-civilizations/the-ancient-aztecs/aztec-jobs/) site.
* "lists of medieval european professions arcana" should bring you to the [arcana wiki for both Middle Ages and renaissance](http://arcana.wikidot.com/list-of-medieval-european-professions).
* Victorian era (discussion of jobs): "[victorianweb work](http://www.victorianweb.org/victorian/history/work/index.html)"
* Victorian artisans: "[200-artisan-skills-required-to-make-a-victorian-town-functional](http://transitionculture.org/2009/01/22/the-200-artisan-skills-required-to-make-a-victorian-town-functional/)"
* Modern times: "[wikipedia lists of occupations](https://en.wikipedia.org/wiki/Lists_of_occupations)"
* Global gaming list (all ages together): "[arcana list-of-all-occupations](http://arcana.wikidot.com/list-of-all-occupations)"
EDIT: I was not able to find a good translation online for the Mesopotamian occupations list, but here is a partial list from the Esagil archives in Babylon: royal administrator (several levels), architect, baker, bitumen-carter, bleacher, boatman, boatbuilder, brickmaker, bricklayer, brick-stamper, basket-maker, cavalryman, carpenter, charioteer, cook, doctor, doorkeeper, engineer, exorcist, farmer, fuller, furniture-maker, gardener, goldsmith, guard (several kinds), herder, horse-trainer, jeweler, King, laborer (agriculture), laborer (wage), leather worker, merchant, miller, musician, overseer, overseer of cattle, paymaster, potter, priest (several levels), ration-dispenser, rope-maker, scribe (several kinds and levels), servant, ship's carpenter, silversmith, smith, tax collector, temple cleaner, weaver, wheelwright, wine-maker, workman (construction).
[Answer]
This is quite brief and relates to a later stage of industrial development than your world, but taking you at your word that you are interested in occupations throughout history, you might find it useful. It's an Excel table compiled from UK census returns by the UK Office for National Statistics giving the percentage of working people employed in each industry group from 1841 to 2011: [170 years of industrial change, 1841-2011, Data Tables](http://www.ons.gov.uk/ons/rel/census/2011-census-analysis/170-years-of-industry/rft-tables.xls).
The ONS press release giving a commentary on the results is here: [170 Years of Industrial Change across England and Wales](http://www.ons.gov.uk/ons/rel/census/2011-census-analysis/170-years-of-industry/170-years-of-industrial-changeponent.html).
I found it interesting that as early as 1841 manufacturing employed more people than any other sector, services was a very close second, and agriculture and fishing, which I would have expected to dominate, were only in third place.
Given that the Industrial Revolution took off in the UK, one would expect it to be a special case. Most countries at that time were far more agricultural. However a world such as yours containing magic might well follow a path which an industrial revolution (powered by magic rather than steam) took off at an earlier stage of technological development than in our world.
By the way, **census returns** generally are probably a good source of the type of information you seek. Seeing that you are Australian I had a quick google and found this portal from the Victorian state library: [Get Started: Early Australian Census Records](http://guides.slv.vic.gov.au/earlycensus); just one of a wealth of similar resources. I am sure the same is true for the US and other countries.
*Added later*: Further searches have turned up what looks like a very relevant and much more detailed resource from the [University of] Cambridge Group for the History of Population and Social Structure: [The occupational structure of Britain 1379-1911](http://www.campop.geog.cam.ac.uk/research/occupations/)
Finally, although it does not directly give a breakdown by occupation, there is fascinating detail in the earliest ever comprehensive analysis of England by social class and land use that is contained in the [Domesday Book](http://www.domesdaybook.co.uk/index.html) compiled from the findings of the survey that William the Conqueror ordered to be made in 1085-86:
>
> "...They inquired what the manor was called; who held it at the time
> of King Edward; who holds it now; how many hides there are; how many
> ploughs in demesne (held by the lord) and how many belonging to the
> men; how many villagers; how many cottagers; how many slaves; how many
> freemen; how many sokemen; how much woodland; how much meadow; how
> much pasture; how many mills; how many fisheries; how much had been
> added to or taken away from the estate; what it used to be worth
> altogether; what it is worth now; and how much each freeman and
> sokeman had and has."
>
>
>
[Answer]
I am going to suggest some written (and reasonably priced written works)
**First, [The Writer's Complete Fantasy Reference](http://rads.stackoverflow.com/amzn/click/1582970262) (ISBN-13: 003-5313107108)**
This is one of my go-to books for developing settings. It covers various forms of government, magic, militaries, social hierarchy, gods and more. It should cover you on the list of professions but it does not (to my recollection) provide #/Population figures. Here are some pics of the table of contents for reference:
[](https://i.stack.imgur.com/CrZN9.png)
[](https://i.stack.imgur.com/uq05K.png)
**Second, the [D&D 5th Edition DM Guide](http://rads.stackoverflow.com/amzn/click/0786965622) (ISBN-13: 978-0786965625)**
This is a great book for helping fill gaps in the world. It provides tables that you can choose (or randomize via dice) government types and much much more. Secret organizations...and a whole host of other things.
I have a few more in mind, I will add them later.
[Answer]
Most role playing games will have some material for you to use. Just choose a world close to yours and you'll have a lot of ideas popping around. Specially if you look for campaign settings or campaign books.
One of the biggest online store would be [drivethrurpg.com](http://drivethrurpg.com).
Fan sites are a bit more scattered and you didn't gave us any hint on what you are looking for, so Google is your friend.
[Answer]
I can't help you with the non-historical, but your best bet for historical data is likely to be your local library. If they don't have the books you need, they probably know a library that does, and can get the books sent to your library for minimal charge.
Libraries have access to anything from history books to encyclopedias to peer-reviewed journals that cost a small fortune to buy for yourself.
My local [university library](http://www.library.arizona.edu/services/borrowing/privileges) allows non-students to get a card. I'm not sure how typical that is, but it's a good place to start, since universities may have subscriptions a standard library might not pay for. Not that the renaissance has changed in the past few centuries, but you may find recent studies that give you better information than something from the 70s.
For something simple, you could try [this](http://www222.pair.com/sjohn/blueroom/demog.htm) world-building resource I stumbled across. I have no idea how authentic it is, and it's medieval rather than renaissance, but it looked interesting. He says "this article is a distillation of broad possibilities drawn from a variety of historical reference points", and has a bibliography at the end for example resources.
] |
[Question]
[
In the world I'm making I want to have very large creatures that will later be used in organic architecture as housing for the human equivalent in this world. In order to make this world realistic I am only going to be pushing the creatures to the upper limit of the Square-Cube Law. This has been discussed at length on this site and there are quite a few examples of the size limits of different body types and activity levels.
In order to have the city sized creatures I want, I plan on shrinking my humanoids to the smallest size that can still be mistaken for full size. Let me clarify a little better. How small can I make my humanoids before we start getting weird physics and biology? I don't want them to be carrying water in their hands and throwing it like water balloons and they need to have a very similar biology to full sized humans (no open circulatory system, they have to be warm blooded, and they can't be able to jump 100x their body length). I know someone already asked about [microscopic humans](https://worldbuilding.stackexchange.com/q/37450/7072) but I want to find the sweet spot between small size and normal physics (yes I know this question is about use of fire but I couldn't find the one that asked about anatomy).
You can ignore comparisons to other plants and animals. I will be adjusting their size as well and most likely creatures like mice will be replaced with relatively larger bugs.
[Answer]
*Homo floresiensis* was a subspecies of hominid (sometimes nicknamed "hobbits") that was around 3-4 feet tall. While not much is known of their culture and lifestyle, they did make tools, and given that modern dwarfism can result in humans that size or smaller, there is no reason to believe that they would be less intelligent.
If you want to go smaller, you probably can get fairly small without running into serious square-cube law issues. Capuchin monkeys are quite small, but water will still behave effectively the same for them as it does for us.
Once you get down to mouse-size you might start running into problems with heat loss, so humans that small might be more "round" to minimize surface area. You might not want that.
The square cube law will make people proportionally stronger and more agile at small sizes, but depending on what you mean by "weird physics" it might not be *too* bad. As a general rule, if body shape remains the same you can presume that speed and jumping height will remain more or less unchanged - if you can jump 2 feet and run at 10 mph, you shrunken down to 2 foot tall can also jump 2 feet and run at 10 mph. Is it a serious issue if everyone in the world can move like a professional sports player (and a professional sports player can move like a superhero)?
[Answer]
I suggest you look up dwarfism.
As far as I can tell it is possible to be less than two feet tall. However, dwarfism is usually due to genetic variance. For example proportionate dwarfism is usually due to organ underdevelopment. Your humans probably should stick above the 4 foot 10 inch bar. (That height being the standard for dwarfism.)
] |
[Question]
[
Let's say my terrestrial planet has a stable [circumbinary orbit](http://kepler.nasa.gov/images/K47system_diagram-full.jpg "Yes, an orbit like this can be stable according to NASA.") around two suns similar to the [Kepler-47 system](http://kepler.nasa.gov/news/nasakeplernews/index.cfm?FuseAction=ShowNews&NewsID=228 "It's a very similar setup."), in the habitable zone, with an orbit similar to Kepler-47c. The challenge here is that I'm trying to set it up similarly to Venus, with a retrograde rotation (probably from an ancient catastrophic collision that created my planet's moon) that takes 340 Earth days to complete. That means approximately 170 days from sun(s)up to sun(s)down.
The trouble is attempting to equalize the temperature. I'd prefer to keep the temperature between 75ºC and -100ºC ... preferably a little less extreme. In real life, Venus's temperature is the same everywhere thanks to its incredibly dense atmosphere. Is there a way I can distribute the temperature?
From what I understand, a high amount of water should help retain the temperature, and the temperature difference itself ought to create powerful storms and winds, which will, again, distribute the heat. And I think a high albedo might stop some heat (though that didn't work out too well for Venus), but I'm not sure what to do about the cold. What else can I do mitigate the temperature effects of such a long day? I've also heard that a slow-rotating planet will have a cooler equator and warmer poles... is that true?
If it's not possible to stabilize the climate somewhat, just let me know.
One more thing… I'm only ***mostly*** hopeless okay at math. If someone could direct me to the equations necessary to work all of this out myself (or an online resource for it), I would be very appreciative.
[Answer]
Give your planet a mega-ocean. Water is a great heat transfer mechanism. On Earth, we have currents that run from equator to pole, and significantly warm places like the UK.
If you created a world with many small islands you could have an almost earth-like setup but a very slow period of rotation. Your currents will most likely go east-west rather than north-south.
You should expect major storms as well. The light side will experience lots of evaporation, which will result in clouds that travel towards the dark side and then precipitate out. This will transfer additional heat from light to dark side.
] |
[Question]
[
A generation ship was sent out a long time ago, to colonize a far away planet. However the ship failed to reach its goal due to navigational issues (which also means they didn't have any clue where in the galaxy they actually were, and how to return to earth). They continued the journey in the hope to eventually either find a colonizeable planet or find back to earth.
It is now travelling for much longer than its originally planned travel time, indeed, a multiple of that. This means that obviously any fixed energy supply the ship may originally have been equipped with is long consumed. So the ship somehow needs to harvest energy from the universe. I don't want it to simply go into orbit around a star and remain there, but it shall still be on its interstellar journey.
This of course poses the problem where the ship gets its energy from. I see the following possibilities:
* It harvests hydrogen from space and uses it for nuclear fusion.
* From time to time it goes close to a star and refreshes its energy supplies from solar (or rather, stellar) power, which it then uses until the next visit of a stellar system.
However given the small density of hydrogen in space, and the long time travelling between star systems (remember, this is a generation ship, so you'd not expect extraordinary high speeds), both options don't seem too convincing to me.
Does anyone have a better solution (or alternatively, can convince me that the two solutions are not as bad as they seem)?
Note that I don't need (actually, don't want) an abundance of energy, but it should be sufficient to keep the spaceship operating and the people on it alive.
[Answer]
The [Bussard ramjet](https://en.wikipedia.org/wiki/Bussard_ramjet) idea could very well work - if you plan your route correctly.
You're worried about the low [number density](https://en.wikipedia.org/wiki/Number_density) of hydrogen atoms/ions in outer space. [This table](https://en.wikipedia.org/wiki/Interstellar_medium#Interstellar_matter) shows that this is indeed quite a big problem. There is a solution, though, which is to travel nearly exclusively - when possible - through [molecular clouds](https://en.wikipedia.org/wiki/Molecular_cloud). These are swaths of space filled with hydrogen and helium where stars are born. They also have a very atomic/ionic number density - roughly $10^2-10^6$ atoms per cubic centimeter (which translates to $10^8-10^{12}$ atoms per cubic meter). Wikipedia says that ~$\text{91%}$ of the interstellar medium is hydrogen; molecular clouds could have an even higher percentage. I'll go with that, and assume a density of $10^{10}$ atoms per cubic meter.
You're on a generation ship, so it's most likely large - after all, it needs to have enough supplies (not just food) to last for many decades. So attaching a large scoop to the front of it shouldn't cause a substantial structural problem. Let's say that the scoop is circular, with a one-kilometer radius. That translates to an area of $1,000,000 \pi$ square meters. Assuming you're traveling at a nice clip - say, $20$ kilometers per second. That means that each second, your scoop travels through $20,000,000,000 \pi=2 \pi \times 10^{10}$ cubic meters of space. With $10^{10}$ atoms per cubic meter, you've scooped up $2 \pi \times 10^{20}$ atoms in that second. If ~$\text{91%}$ of those are hydrogen atoms, you've picked up $5.718 \times 10^{20}$ hydrogen atoms. With one [hydrogen atom](https://en.wikipedia.org/wiki/Hydrogen_atom) having a mass of one [atomic mass unit](https://en.wikipedia.org/wiki/Atomic_mass_unit) ($1.661 \times 10^{-27}$ kilograms); you pick up $8.601 \times 10^{-7}$ kilograms of hydrogen. So it will take you about $115$ days to collect one kilogram of hydrogen.
Fortunately, most Bussard ramjet ideas have much larger scoops. To collect one kilogram of atomic hydrogen per day, you'd only need a scoop with a radius of $10.7$ kilometers. In an answer [here](https://physics.stackexchange.com/questions/72926/in-nuclear-fusion-reaction-what-is-the-percentage-of-mass-converted-to-energy/72929#72929), user23660 said that approximately $\text{0.0037681%}$ of the mass is converted to energy. So you have $0.0037681$ kilograms of hydrogen. Via $E=mc^2$, that translates to $3.387 \times 10^{14}$ Joules (using [$c=299,792,458$](https://en.wikipedia.org/wiki/Speed_of_light)) produced each day, or a power output of $3.920 \times 10^{10}$ Joules per second.
In that one second, $3.920 \times 10^{10}$ Joules of energy have been consumed. The velocity I gave before was $20$ kilometers per second, so the ship has gone $20,000$ meters. Work is defined as $\text{Force} \times \text{distance}$; setting the energy used as work, I get a force of about $195,984$ Newtons. Given that the mass of the ship is $\text{something very large}$, you're not going to have a huge acceleration. You can always increase the size of the scoop: multiplying the radius by $x$ will multiply the area by $x^2$, and thus multiply the amount of hydrogen collected by $x^2$, so long as $x$ is in meters.
Of course, there are ways around this. For example, maybe your ship is propelled by a [solar sail](https://en.wikipedia.org/wiki/Solar_sail). A solar sail takes a while to get to a decent cruising speed, but it needs no fuel. Plus, it will be about the same size as the scoop, so the scoop shouldn't cause any additional drag. This means that all the energy can go towards keeping the ship's inhabitants alive.
Molecular clouds aren't easy to come by, though. Wikipedia ([the molecular cloud article](https://en.wikipedia.org/wiki/Molecular_cloud)) says that they only compose one percent of the total interstellar medium. Ouch. However, it does say this:
>
> The bulk of the molecular gas is contained in a ring between 3.5 and 7.5 kiloparsecs (11,000 and 24,000 light-years) from the center of the Milky Way (the Sun is about 8.5 kiloparsecs from the center). Large scale CO maps of the galaxy show that the position of this gas correlates with the spiral arms of the galaxy.
>
>
>
So you can think of that ring as an express lane for Bussard ramjets. I haven't been able to find an image showing the location, but [this](http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=8970394&fileId=S1323358013000222) (paywalled) paper seems to be a good start. In summary: choose the right locations (and take a solar sail along for the ride) at it seems like you'll be okay with a Bussard Ramjet.
---
I just realized that there's a loophole to this (and I feel stupid for not realizing it before!).
The Swiss plane [Solar Impulse](https://en.wikipedia.org/wiki/Solar_Impulse) aims to circumnavigate the globe. One of the problems, though, is that it must fly during the night, where there's no solar energy to be gathered. Solar Impulse solves this problem by gathering extra energy during the day, storing it in batteries, and using it slowly at night, while drifting down a little. The ramjet could do this, too, collecting excess hydrogen and storing it in tanks. The fuel would add extra mass, but it would enable the craft to go to new places along new routes.
[Answer]
My favorite idea for a reactionless drive is based on ZPE. That's Zero Point Energy. How does it work? The simple answer is that "empty space" is anything but empty, instead is a boiling cauldron of energy, with quantum uncertainty generating sets of particle-antiparticle combinations (with zero net energy) all the time. To use a loose metaphor, you can think of "real" particles as a thin icy film on top of a very, very deep ocean.
How do you harness this? One current way of doing so is by generating a pressure differential via the Casimir Effect. Two plates are placed so close together, that virtual particles with a certain wavelength cannot form inside, but freely form outside. This generates a pressure that pushes the two plates together. If a more advanced version of this can be vectorized, you don't even need to bother with getting reaction mass on board.
[Answer]
You could always have the ship go planet to planet, stripping the planet of whatever resources it has to continue operation. It would require relatively long stops to refuel, but then the ship could continue on its way for a long time. Also many star systems have multiple planets, meaning that within a relatively small region, there would be multiple opportunities to gather resources. Likely lacking the more efficient technology of the world it was launched from, this task would be difficult, and the ship wouldn't find itself with an abundance of energy.
[Answer]
Heinlein, iirc, had one of his generation ships use direct matter to energy conversion... of course, since they were off-course and long past their estimated trip time, the degenerate descendants were slowly stripping the ship (and their wastes and life-support) to feed the energy converters...
[Answer]
The ship could be powered by Dark Energy (which [Wikipedia](https://en.wikipedia.org/wiki/Dark_energy "Wikipedia") tells me is 68.3% of the universe). Theoretically, exists in great abundance everywhere, but there's no reason that your ship's collectors/generators need to be any more efficient than the plot demands. And, of course, there's no telling when the ship will find itself in a region of particularly low energy for some reason.
[Answer]
An highly energized nuclear reactor.
EXTREMELY efficient solar?
Harnessed cosmic radiation?
outer structure made of superconductive coils, a magnetic center spun to induce current. balanced freely in the middle and spun in a vacuum to avoid friction. It would also produce artificial gravity by spinning.
Anyone who says the magnetic field would cause it STOP spinning on its own...
Check out the dynaflux alternator:
<https://www.youtube.com/watch?v=HK3JOlY0V8Y&list=LLPZOJw60jGMI9oKNJQVQ6pg&index=6>
Cold Fusion?
A zero-point-module from an ancient's device. (Stargate anyone?)
A portable black hole ? Feeding it rips matter apart producing powerful x-rays.
Magnetic containment may be a problem though! It worked for the Romulans.
] |
[Question]
[
**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.
I was curious: Suppose we built an [O'Neill cylinder](https://en.wikipedia.org/wiki/O%27Neill_cylinder) with an air mixture similar to Earth's (not pure oxygen).
Does the air also get "thrown" down towards the floor of an O'Neill cylinder? If I started a campfire in an O'Neill cylinder would it behave the same way as on Earth?
[Answer]
**This question asks for hard science.** All answers to this question should be backed up by equations, empirical evidence, scientific papers, other citations, etc. Answers that do not satisfy this requirement might be removed. See [the tag description](/tags/hard-science/info) for more information.
The fire would look like a normal fire. However, the smoke would do weird things.
Here is a diagram of the O'Neill cylinder with a fire. (Darker blue represents higher air pressure.)
The radius of the smoke column will grow more than on earth as the altitude increases, since the centrifugal force decreases as the smoke reaches the inner part of the cylinder.
[](https://i.stack.imgur.com/duhIU.png)
At this point, it looks normal. Then, it gets weird.
As the smoke reaches lower air pressure, it cannot rise because it is mostly composed of [solids and liquids](https://en.wikipedia.org/wiki/Smoke), and solids and liquids do not expand. The smoke will stay in the area where its density equals the density of the air, beginning to form a cylinder.
[](https://i.stack.imgur.com/YnDfX.png)
The new, high temperature smoke will displace the older smoke, pushing it down the O'Neill cylinder. Particles of smoke are held up by their high temperature. Since the cylinder of smoke is constantly losing temperature as it leaves the fire, the cylinder of smoke will undergo [dry precipitation](https://en.wikipedia.org/wiki/Deposition_(aerosol_physics)), "sinking" back to the edge of the O'Neill cylinder.
[](https://i.stack.imgur.com/mSF1u.png)
I hope my pictures helped to portray what I was saying. Please comment if you are confused.
] |
[Question]
[
In 1815 [Mount Tambora](https://en.wikipedia.org/wiki/1815_eruption_of_Mount_Tambora) erupted throwing so much dust into the atmosphere that the year became known as "[the year without a summer](https://en.wikipedia.org/wiki/Year_Without_a_Summer)". \*There were a few other mitigating factors but Tambora is thought to be the main culprit.
From Wikipedia
>
> "This climate anomaly has been blamed for the severity of typhus
> epidemics in southeast Europe and the eastern Mediterranean between
> 1816 and 1819.The climate changes disrupted the Indian monsoons,
> caused three failed harvests and famine contributing to the spread of
> a new strain of cholera originating in Bengal in 1816. Many livestock
> died in New England during the winter of 1816–1817. Cool temperatures
> and heavy rains resulted in failed harvests in Britain and Ireland.
> Families in Wales travelled long distances as refugees, begging for
> food. Famine was prevalent in north and southwest Ireland, following
> the failure of wheat, oat, and potato harvests. The crisis was severe
> in Germany, where food prices rose sharply and demonstrations in front
> of grain markets and bakeries, followed by riots, arson, and looting,
> took place in many European cities. It was the worst famine of the
> 19th century"
>
>
>
In 1883 [Kratotoa](https://en.wikipedia.org/wiki/1883_eruption_of_Krakatoa) erupted and is known as the deadliest volcanic eruption in modern times. It threw so much sulphur and dust into the air that it caused temperatures to drop worldwide for ~5 years. At least 36 000 people died.
>
> In the year following the 1883 Krakatoa eruption, average Northern Hemisphere summer temperatures fell by as much as 1.2 °C (2.2 °F). Weather patterns continued to be chaotic for years, and temperatures did not return to normal until 1888
>
>
>
and
>
> The Krakatoa eruption injected an unusually large amount of sulfur dioxide (SO2) gas high into the stratosphere, which was subsequently transported by high-level winds all over the planet. This led to a global increase in sulfuric acid (H2SO4) concentration in high-level cirrus clouds. The resulting increase in cloud reflectivity (or albedo) would reflect more incoming light from the sun than usual, and cool the entire planet until the suspended sulfur fell to the ground as acid precipitation.
>
>
>
These are global cooling events but are not as extreme as nuclear winters or as if Yellowstone super volcano had erupted. There is no radioactive fallout, actually thinking about it there are probably trace amounts in the ejected tephra. This sort of chaotic event would not create a snowball earth scenario. I'm trying to avoid that.
---
In my story, I have a similar setup where several various factors intermingle and create a period of time with large to excessive amounts of dust in the atmosphere leading to cooler summers, colder winters and severe food shortages. People die, regimes fall, chaos ensues. But then the dust clears and life can resume.
I'm not aiming for long-term ice ages or anything as 'fixed' as that. I'm aiming for an extended period of chaotic weather (only a slight 1-2 degree average temperature difference) that will affect the stability of human food production that would further influence mankind's societies in the short-term.
**Now for the question.** Just how long can a society survive in such conditions? I have a minimum range of 5 - 10 years from Krakatoa and Tambora but society didn't fail in the real world. Yes, people died and moved around as refugees looking for food but I haven't found any mention of nation states breaking down. How much longer could such an event have lasted so that it could be the direct cause of a state breaking down. What is the maximum range; decades up to 50 years?
A sub question to help focus any answers. Would the ensuing climate chaos have to have a more severe effect over a shorter time period or can I just extend the duration of the climate chaos to decades to cause society failure? I have a feeling if the climate changes are just extended, surviving humanity will adapt and find new crops and contingencies to make do with.
---
Note: I haven't focused on the industrial level pre-disaster as I haven't figured that out yet. Several centuries after the event and my society in question is approaching or is already in the Renaissance. If this is the second enlightenment or the first I haven't decided yet. It all really depends on how intense the colder famine period was. Answers can take this into consideration.
Note: I do realise that the political situation will play a part in if the state fails or not. But I'm trying to figure out how long a state/society could theoretically survive with a damaged food production system ***before*** bringing political factors into play (which will help me narrow down the time period even more).
[Answer]
That is highly dependent on how bad it comes.
The [Deccan Traps](https://en.wikipedia.org/wiki/Deccan_Traps) lasted *30 000 years* and were together with the meteorite impact (which very likely also did trigger the traps) responsible for the mass extinction at the end of the Cretaceous period.
100 years ago such an event would very, very likely eradicate humanity. Now we would be able to continue even under an ash cloud with nuclear energy, but most of the human population will die an ugly death with a complete breakdown of society (riots, anarchy).
Another supervolcano incident, the [Toba eruption](https://en.wikipedia.org/wiki/Toba_catastrophe_theory), lasted only 6 years, but nearly wiped us from earth because it caused a severe genetic bottleneck, reducing humanity to approximately 1000 persons.
Essentially storages are only a short term solution (half a year at max). Humans have fat storage which enables us for weeks/months to continue working, but once this storage is empty, we need on average 300g fat or 500g carbohydrates and approx. 1 g protein per kg each day not to starve. *That's a lot*. While previous societies had fewer people they also had more diseases/war and less productivity, so I do not think the timeframe will be very different. So expect that society breaks down 1/2 - 1 year after the incident because people will be reduced to survival level or below.
[Answer]
According to the [german Wikipedia article](https://de.wikipedia.org/wiki/Kleine_Eiszeit#Machtpolitische_Ereignisse) the little ice age needed around 50 years with a growing population and crop failures to be a partial cause of the thirty year's war. And then only one year with a high population, drought, hail, hard winter and no money to spark the events of 1789.
But if you look the other way around at the french in the 17th century or the prussians in the 18th you have very "stable" societies.
I think a "stable" society may survive several generations of hardships as long as the population believes in it's nation / leadership / emperor / common goal / blood sacrifice ...
[Answer]
There is a perfect example in a very good book: *The Bible*. In there you will find a story about a guy who advised to store food to be not only enough for 7 years for the country storing it, but also in surplus to be sold outside.
So this points you to two things: The famine would need to be long enough to deplete the country's storage and large enough to affect the worldwide market. If only one condition would be fulfilled you would get some unrest, maybe a few uprisings. But without any outside force it's very unlikely the society would change.
And the outside force I have in mind: German agent Lenin working to change the government for the actual profit of Russia to withdraw from war.
[Answer]
To look at the global situation, there is an example of a report [here](http://www.fao.org/3/a-I5703E.pdf). Basically, the world production of basic cereals is about 2500 million tonnes a year, roughly balanced by consumption, with stocks of c. 600 million tonnes.
So - if a volcano completely wiped out farming, the answer is 'About 3 months'. The world does not carry a lot of food stocks. you might worry about this. You might add a month for food people had stored locally, and in supply chains, but with 'just in time' policies, that doesn't help much.
But.. from the same source, you'll note that over a third of grain production goes to animal feed. A large chunk of this could be diverted to human use without much problem; this gives the system a buffer. So as long as we didn't have complete harvest failure, we could cope with significant reductions. And it's fair to say that with the knowledge that a volcanic eruption had caused a temporary climate shift, farmers could adapt far more quickly nowadays than in, say, 1815.
The big problem could be market reaction. With prices being bid through the roof and normal exporting countries imposing export bans, local or regional famines could easily develop even when storehouses elsewhere were full. These can quickly escalate into revolution and war, as we saw in the 'Arab spring', mainly studied [in the context of global warming](https://climateandsecurity.files.wordpress.com/2012/04/climatechangearabspring-ccs-cap-stimson.pdf), but also applicable for volcano induced cooling.
Conclusion: We could survive given sensible adaptation and international cooperation. So we would probably see some major wars and famines, then.
] |
[Question]
[
In a world I’m designing, one of the eldest extant intelligent species is the Trolls. These are not D&D trolls, but something else. I have a number of basic characteristics for these beings, and am wondering whether these characteristics necessarily imply anything remarkable about their physiology.
Note: Assume that everything is Earth-like unless otherwise stated.
# The Basics of Trolls
Trolls are about 3m tall, and weigh about 300-400kg.
Their bodies are mostly covered in a thick, coarse hair. This hair, like that of wolverines on Earth (*gulo luscus, gulo gulo*) naturally inhibits ice formation.
They are viviparous and mammalian. They are also marsupials, at least in the non-technical sense that their infants are carried and suckled in a pouch.
Trolls live an average of 200 years, barring major injury.
They live principally in a large system of cold fens and moors. During the warm months, the weather is not unlike that of northern Scotland: cool and moist. During the cold months, temperatures rarely rise much above 0C except at midday, and nighttime temperatures are commonly around -15C.
Their diet consists primarily of vegetable matter, though they scrounge a certain amount of protein from insects and carrion. They do not normally hunt and eat other animals.
Trolls are immensely strong by comparison to humans, on the order of gorillas.
They are extremely durable: not only are they difficult to hurt in the first place, but they heal quite rapidly and consistently. They are not significantly prone to major disease.
# The Question
Based on these characteristics, I imagine that a certain amount can be inferred at once regarding their physiology. However, I know very little about animal biology. Specifically:
* Given these characteristics, are there other necessary or extremely likely qualities that would be remarkable? (By “remarkable,” I mean something that is not usually the case for all mammals and would probably get mentioned in a fourth-grade book on animals, but that I have not mentioned here.)
* Are there any serious objections to animals like these trolls existing? (That is, some of these characteristics appear mutually contradictory, requiring some other as-yet unstated quality to explain—or perhaps requiring me to eliminate something.)
[Answer]
1. Given those temperatures, and being mammals, the trolls would have a layer of blubber (like seals), or alternatively wear clothes. Assuming they have blubber, these trolls must eat a lot of fat (or sugar, to make fat).
2. Because of their method of defending themselves by breaking things on their knees, they may have some kind of (possibly keratin-based) "bony protuberances" (like rhinoceros or dinosaurs) to shield and weaponize the parts of their anatomy used for combat.
[Answer]
For your first question, assuming your trolls spend any time actually in the water in their habitat they are going to have a small issue with being marsupials. Mother nature seems to have already solved this problem in the [Water Opossum](https://en.wikipedia.org/wiki/Water_opossum) with a sealed, water-tight pouch.
For your second question, I think your trolls might have trouble finding enough food. As you've described them, their diet fairly closely resembles that of the gorilla, mostly plant matter with some insects. According to [this](http://www.berggorilla.org/en/gorillas/general/everyday-life/what-do-gorillas-eat/) source an adult male Grauer's gorilla weighs 170kg and eats 30kg of plant matter a day. That's means they eat roughly 1/6 their own body weight in plants every day. To find this much food they have to spend roughly half the day just foraging. Scaling up to your trolls, to sustain a 300-400kg body weight would require 50-70kg of plant intake per day. Keep in mind that while gorillas eat a lot of shoots and leaves much of their diet is also composed of various fruits which are more calorie dense. Those fruits may not be available in a fen. While I'm not saying its impossible for the trolls to forage that much edible plant matter in a day its certainly not going to be easy for them. There are lots of fun ways you could provide an extra food source though. Any sort of troll agriculture would work, or relaxing restrictions on hunting and eating animals to allow for fish or giant insects. Maybe there are large species of carnivorous plants that provide a lot of calories when eaten, or maybe they even eat big blocks of peat cut straight from the bog.
[Answer]
The trolls would have a low high weight to height ratio.
Their BMI would be (for a 300Kg, 3m tall troll) 0.0033 as opposed to a human's of ten times that.
The BMI falls with the square of the height.
In short they would be very thin and weedy creatures, They would not be strong as you suggest and would not have a insulating shape to whether the cold. They would likely need to eat frequently to overcome their fat shortages.
Can't say any more about the biology of a BMI that low but they would need to be quite different. Their hearts would need to be large to pup blood so high and would likely need large brains just to balance themselves.
] |
[Question]
[
I have two interstellar civilizations, both of which are extremely advanced and within a few thousand light years of earth. They go to war and make some stars explode in the process.
**The Combatants**
I have in my space setting two civilizations who are extremely, extremely advanced. To get an idea of their capabilities let me list the ones relevant to this discussion. Both sides were capable of causing a star to go super nova, had micro black hole arrays as their "small arm weaponry" and were able to warp from star system to star system by willing it. There is a tech gap between them that is balanced by the less advanced ones, who I will refer to as the Industrials (of whom you can imagine as extremely advanced machines), being much more tenacious than the Archivists. The Archivists, whose design is very serpentine and fuming in blinding energy are ancient beings who really just wanted to collect data on the universe. They predate the empire, but that part of this overbuilt cosmic history isn't important here.
So why are they at war? Here's a bit of context for anyone who needs it.
**Context**
There is a somewhat complicated history behind why such a cataclysmic war occurred in the first place. Since it's not the meat of my question and really unrefined in terms of completion i'll just say the following long sentence. While humans were figuring out agriculture a powerful, seemingly all encompassing empire spanning the Orion Arm fell apart violently due to a miasma of catastrophes that stem from the Archivists launching a decapitation raid on the empire's oligarchs in response to the empire destroying their observatory world located around a star in the Aquila rift. Said observatory held quite a few Archivists. Given the distance of the named place, you may see why i'm asking this question.
Fast forward a thousand years and the empire is pretty much dead. A procession of events leads the Industrious to have a civilization that is slowly murdered by a cryptic force known as the Celestials who appear on the scene a few centuries after the empire's decapitation. They just start killing anyone who is self-aware and a pain inducing war against a would-be Empire Successor polity called the Eternal Republic which no one but the Celestials won. The Eternal Republic was exterminated, but the Industrious had enough time to go into hiding as the celestials massacred their society as well. Industrious than spent a few millenniums in hiding as the Celestials continued hunting down life that was sensed by them as self-aware, purifying world after world of such life. The Industrious however, rebounded and rebounded hard.
The Industrious deep within the mantle of multiple worlds uninhabitable managed to advance to technological levels that rivaled the Archivists to a degree and begun a uphill crusade against the Celestials, at first being very outnumbered. However the Industrious at this point were militarily far more advanced than the Celestials, meaning they easily fought the Celestials despite being out numbered and rapidly expanded in numbers as they exterminated the Celestials. Once the Celestials were killed off, the Industrious inexplicably turned their weapons and vast military on the Archivists. Thus began the Annihilation.
In the Annihilation (which was a war that only lasted a century), multiple stars were super novae'd. But the Industrious, despite managing to do far more damage to the Archivists than the Empire ever could would lose the war. The Industrious as a species were let off surprisingly easy, being only reduced to a primitive, stone age civilization. The Archivists however, instead of coming to dominate the Orion Arm simply went into further hiding. They still are out there to this day, observing as they always had.
I am aware that by cosmic history has opened way more questions than answers (like about the culture/nature of all these aliens and the way the empire was ran), but I rapidly came to realize a massive, massive trouble with all this star exploding and interstellar massacring:
**Wouldn't we have noticed all this?**
I ask this since there is no way a war where stars went into supernova in such rapid procession wouldn't be noticed by astronomers and raise tons of questions. The super novae would after all leave behind planetary nebulae in their wake, such as the crab nebula which came from a super nova seen around the world in 1200 AD. The question of super novae also has been bothering me since wouldn't multiple super novas in short procession would cause some very noticeable planetary nebulae complexes? These would be extremely noticeable cosmic features within a thousand light years and their cultural impact may have history altering conditions if I have this in my mind right.
One solution I had was simply to write these anomalies into the history books, but than I realized that having multiple super novae go off in the sky in rapid procession may completely alter human culture (the Annihilation happening just as our civilizations were taking shape) to the point where i'd have to rewrite all of human history, something I don't really want to do. I like to make alien societies from scratch, but find remaking human history a extremely hard task despite looking up history in my free time, go figure.
So, what would a nearby interstellar where super novas occur as a direct product look like from earth and is there a way to hide it or have it be simply dismissed in our time as just a natural occurrence? I don't really know what to do and I don't want to move all this to the other side of the galaxy. I used to have it on the other side of the galaxy, but decided that I didn't want a galactic setting anymore and so compacted my space opera into our corner of the galaxy. Why? Because I like space being massive and being able to traverse the galaxy has always undermined that feeling for me. So a empire that *only* spans the Orion Arm is extremely, extremely massive to me.
**To the main question.**
Ignoring the subjective part (on my placement of the empire), my assessment on the product of a interstellar war between extremely advanced societies where some stars are detonated accurate? If not, what would the impact of a war of this magnitude of destruction in the space? Assume a variable distance of 450-1700 Ly or so from earth towards the general direction of the Aqulia Rift.
(I think a anomaly of many planetary nebulae in one area would be a bit anomalous, not even taking into account the cultural impact of seeing supernovae in the sky as a reoccurring event for two centuries on our ancient ancestors.)
[Answer]
I think a lot of it would depend on how far back you are setting the war. Humans became anatomically modern @ 200,000 years ago, but the cultural explosion happened much closer in time (@ 50,000 years ago).
If you push your time line far enough back that the light from the distant suns passes Earth between 200,000 and 50,000 years ago, essentially there would be no one there to notice. Humans and their cousins from that time period exhibited few or no signs of culture, language, arts or other signs of sapience beyond that of extremely smart pack animals. Modern astronomers would obviously be aware that something is amiss in the night sky, but this would be a result of late 20th century astronomy using the entire sophisticated arsenal of observation tools and in multiple wavelengths (from radio astronomy to visible light, infrared, UV and even x-ray astronomy).
Given the relatively short time any individual astronomer can have on a particular instrument, and spreading the observations over long periods of time and space (a Spanish astronomer observes star "x" in Infrared and notes an anomaly in 1988, but the next time the star is studied it is a Japanese astronomer using a radio telescope in 1996. The Hubble space telescope takes a look as part of an American project in 2002, and the Kepler observes this in passing while looking for a habitable planet in 2014). It takes a long time before these various observations are brought together, and even longer before anyone starts noticing something is amiss.
*What* they are seeing are large nebula formed from the explosions of stars, huge swaths of ionized gasses and molecular clouds punctuated by a rather unusual number of pulsars (neutron stars rotating at extremely high speeds). What will eventually tweak someone's curiosity are the sheer number of nova and supernova remnants in a relatively small area, and the puzzle that many of the remnants do not seem to match modern theories of supernova formation. The estimated masses of the nebula and former stars will be far lower than the generally accepted lower bound for a type 2 supernova (8 solar masses. The supernova is caused by the collapse of the core when the fusion process has reached iron, which produces no net energy. The radiation pressure of the core ceases and gravity causes the mass of the star to collapse into the core, triggering the supernova).
Considering the number of stars you seem to be postulating, there should also be a fair number of type 1 nova in the region as well, as the neutron star remnants of the former stars move into binary orbit of an unexploded star over time and begin transferring mass from the active star. The resulting hydrogen "atmosphere" will eventually reach a pressure and density that triggers a fusion reaction, which both ancient and modern astronomers will certainly notice.
A bit of tweaking of the backstory would be required to ensure that the number of observed type 1 nova matches the historic record. You could also invoke some sort of handwavium by having the cores of the murdered stars ejected from the galaxy at high velocity due to whatever caused the supernova explosion in the first place (they will not have reached the edge of the galaxy yet, but are moving fast enough that they will not interact with other stars).
So if the events happened far enough away in time and space that there were no "modern" humans to see the actual events in the sky, then modern astronomers will have lots of clues scattered about, but due to the dispersed nature of astronomy (no singe astronomer spends his life at one telescope or observatory any more, unlike Tycho Brahe or John Herschel), it will take a long time to put the subtle clues together.
[Answer]
**From your intro we have:**
There is a somewhat complicated history...While humans were figuring out agriculture...in the Aquila rift...(Archivists attacked)...a few centuries after...(we have Celestials)...(over) a thousand years (from the Archivists' attack)......(Everything is quiet)...(Industrious) spent a few millenniums in hiding (and then kicked butt)...(so over a thousand years is actually a few milleniums (3+))
**Which gives us a timeline:**
* Humans Discovering Agriculture (11,500 yrs ago)
* Archivists vs Empire (11,500 yrs ago)
* Celestial Cleansing (+X00 yrs)
* Industrious Revolution (+Y000 yrs)
* Annihilation (+100 yrs)
So we need to overcome some issues. Mainly surviving records and detectable remnants.
**For records:**
* 4,485 BC is about our latest date if you max out the X to 9 and bump the Y to 4. We're talking the time when the Sumerians were inventing the patriarchy. No more clay Mother Earths. The world had more important social issues and stars were probably not high on the list.
* The Earliest recorded supernova is from 185 AD. Well after any of your dates. So we're looking at so long ago that there wouldn't be remaining records or ways of viewing after the initial burst. Although we're close enough that you would have a near-Earth supernova and you'd be [likely dead anyway](https://en.wikipedia.org/wiki/Ordovician%E2%80%93Silurian_extinction#Gamma_ray_burst_hypothesis). If you want humans to survive better you need more of your burst to be neutrinos.
* Wikipedia's article on [Kepler's Supernova](https://en.wikipedia.org/wiki/Kepler's_Supernova) seems to suggest that many would be obsessed with viewing it if they could see it (large amount of stargazing contemporaries and whatnot). But if you we're struggling to survive there's very little reason to record what the sky is doing (oral tradition in those days) which leaves your 185 AD record intact.
**Detecting the remnants:**
* [Tycho's supernova](https://en.wikipedia.org/wiki/SN_1572) highlights issues for detecting the remnant and also for possible advances or cultural shifts during that time. Of note is the fact that advances can slip away from humanity if that culture gets conquered so no net gain is acceptable, and once again the the advancement is not likely due to survival pressures.
* [RX J0852.0-4622](https://en.wikipedia.org/wiki/RX_J0852.0-4622), is *closer* than your distance and seems to have eluded us until 1998/2001.
* Your method of explosion determines how visible and for how long. Material of star does as well. Roughly speaking the heavier the material the brighter and more short-lived it is, whereas lighter material is brighter longer. The majority of 55% of our supernova are bright and fast. If you move more of the products into neutrinos you become less detectable. Maybe they could only blow up stars with lots of heavy metals?
* There's a decent amount of protostars nearby that are attracting the clouds of The Rift but not yet accreting disks. Your supernovas could have been dispersed by them.
* Supernovae should occur about three times every century in our galaxy ([source](http://arxiv.org/abs/1306.0559)). Yet I don't think we're discovering remnants at that rate.
* At your distances *active stars* are already being obscured by the water clouds in The Rift. As long as the remnant's thermal signature is low enough they should be all but invisible even if they're standard supernovae.
**In conclusion**, I'm not an expert but after a fair amount of research it seems like you could just wing it and you'd be good. Disruptions in the clouds are still being explained (magnetism, etc.) so as long as you explosions are roughly uniformly distributed (or so densely packed we missed it), your probably good to go.
[Answer]
**Supernovas beyond [26Ly](https://en.wikipedia.org/wiki/Near-Earth_supernova) are just pretty, bright lights** and without telescopes to figure out what happened, they will remain historical curiosities. Human astronomers will event whatever explanations suit their theology and philosophy; just as they did for thousands of years before telescopes and science.
Given the superstitious nature of pre-science humans, seeing that many bright lights in the sky would be taken as an omen or omens of some kind. What that would be depends on the culture and the situation at the time. Halley's Comet, a giant ball of ice with no impact whatsoever on Earth was nevertheless able to cause commotions when it sailed by.
>
> stars went into supernova in such rapid procession wouldn't be noticed by astronomers and raise tons of questions
>
>
>
The OP doesn't specify what "rapid procession" means so I'm going to assume that it's within a span of 10 years. Either these stars will need to explode in a staggered fashion "timed" so they show up in quick succession *or* they will be physically close together and detonated about the same time. Having stars simultaneously go supernova in a range between 400 and 1700 light years away means that the light from those explosions will reach us over a range of 1300 years; not exactly rapid succession.
Events like supernovas definitely leave behind stellar remnants and glow for a good long time afterwards. Even at 400 to 1700 Ly, those remnants should still be identifiable with good enough telescopes. Saying that the stars were destroyed in a war will be the ideas of science fiction writers unless there is clear evidence that distinguishes the destroyed stars from naturally occurring supernovas.
] |
[Question]
[
There was a good question and answer here: [Does mermaid evolution come with buoyancy control?](https://worldbuilding.stackexchange.com/questions/30699/does-mermaid-evolution-come-with-buoyancy-control)
But I would like to expand the question. I got off talking with a friend, it got me thinking about mermaid buoyancy. It came up that perhaps mermaids should exhibit some synergy or combination of the methods used by fish, sharks and dolphins. An interesting example was that, if a mermaid ascends too quickly, the gas from their swim bladder might empty out into their lungs or stomach, leading them to feel sick.
**Reason for This**
For plausible reasons this might be the case, I'll point first to the unusual nature of the mermaid granting the possibility of unusual biology. They are a naturally composite creature, so being a further composite biologically seems to build on that narrative.
More importantly, I'll point to the fact they're not exactly a whale, seal, shark or dolphin. Mermaids look pretty light, not like fat-laden sea creatures nor dense sharks. Their presumably muscular tails indicate they will not be as buoyant as humans. So it leaves the question of how they can best control/maintain the preferred buoyancy.
**Advantages of Each?**
There is the question of which advantages each biological method has, and how they may not mesh well or how they might mesh well.
*Swim Bladders:* As was mentioned in the other question post, swim bladders are good for saving up energy, if you're not spending much. Mermaids probably won't be spending just about all their time patrolling and hunting like sharks, so ways to preserve energy for low energy activities seem handy.
*Large oily livers...* I do not know enough about the biological implications of that to talk about pros and cons. It is intended to increase the buoyancy of the creature, not really to reach neutral buoyancy in the case of a shark. A mermaid probably can't afford to have an enormous, oily liver.
This could actually serve as a good reason for a combination. If a mermaid can't have a large enough liver for desired buoyancy, they need other factors involved. That is, assuming a small oily liver isn't much more trouble than it is worth.
*Lungs and Swallowing Air:* Sharks sometimes swallow air to help them counteract their density. Dolphins and seals apparently control their breath and lung capacity to aid in buoyancy control. The likelihood of these may depend on what mermaids breathe, air, water, or both. The Mermaids I'm thinking of can breathe both. If they still surface frequently, I don't see the problem with them utilizing this techniques for better buoyancy control, in what limited capacity a human-like creature can utilize them (when I tried to swallow air, it hurt).
A point of importance, is that whales apparently don't get much use out of this, because their lungs are too small relative to their great weight. They rely more on their blubber.
**Synergy?**
The most synergy I can see currently, is mermaids probably have mammal lungs capable of operating in the air, so they are free to use those lungs as divers and mammals do. Since their lungs will probably be pretty large, as humans' are, that makes them more useful for this purpose.
The other point, is simply the ineffectiveness of any one method for the diverse activities mermaids are likely to perform, as human-like creatures of the sea. Adaptability is one of humanity's real strong points, and I would hope the same to be true of mermaids both biologically and technologically.
Anyone with biological/marine knowledge who would like to weigh in?
[Answer]
It could be possible for them to have a duel system (both gills and lungs), like [lungfish](https://en.wikipedia.org/wiki/Lungfish).
Some lungfish are able to run the two systems independently, so when they are breathing through their lungs then the gills are closed, and when they are breathing through their gills then the lungs are bypassed.
There could be a system in mermaids where some of the gas captured through the gill system is transferred to the lungs to increase buoyancy, and if they have to ascend quickly they'd be able to exhale and equalize pressure.
They could also have an oily liver or spermaceti organ like dwarf sperm whales to get them to mostly neutral, possibly combined with some level of body fat, and then you would only need small changes in buoyancy to make a difference.
[Answer]
In order of increasing probability, I would arrange them as: swim bladder, oily liver, large lungs. As in, swim bladder is the least likely/advantageous while large lungs are the most likely/advantageous.
Reasons for choosing larger lungs are easy.
* All marine mammals use large lungs to hold their breaths for extended periods of time. The best examples being dolphins and whales.
* Being (probably) closely related to humans/mammals, the mermaids wouldn't have gills or swim bladders since those are more closely related to fish than mammals.
* Breathing in air and holding breath during dive has been a very successful strategy for large marine animals in all evolutionary times. For example, the ichthyosaurs, plesiosaurs, nothosaurs, placodonts and turtles, all these lineages breathed in air and held their breaths during diving. All of them were quite successful in their times.
] |
[Question]
[
My protagonist is an astronomer in a fantasy world.
Ideally, what I want is software where I can specify some properties of this planet, e.g. orbital and rotation period, nearby stars, number of moons, and then visualise what someone would see from the planet's surface.
All the software I've found while searching visualises the real universe, whereas I want some kind of sandbox mode.
If this doesn't exist, can anyone guess what kind of tech stack I could use to build something basic myself? I am a Python engineer, but very inexperienced.
[Answer]
Maybe, the most similar software to that specification and free, is Digital Universe developed by Hayden Planetarium. This software is available for Windows, Mac and Linux.
[Download here](https://www.amnh.org/our-research/hayden-planetarium/hayden-planetarium-promos/download-files) and look for tutorial and guide [here](https://www.amnh.org/our-research/hayden-planetarium/digital-universe/help).
This package is the most accurate in visualization but is not sandboxed (you can not simulate specific conditions).
Using [Universe Sandbox 2](http://universesandbox.com/) you are free to simulate many celestial events (for example, generate your star, planets and moons with realistic conditions of gravity force -not custom periods-) but if you can compare with an actual sky this is not the best option, thus you need to recreate many bodies in the near universe. You need to pay for Universe Sandbox.
My last recommendation is [Stellarium](http://stellarium.org/) if you choose a real body in the solar system. You can change specific position (local coordinates) in the body and time of observation (past, present or future, with custom velocity to see changes in the sky). This is free.
[Answer]
**[Astrosynthesis](http://www.nbos.com/products/astrosynthesis)** is a nice generator that could fit your needs. It's a paid-for program, but it also has a 14-day trial so you can see what it has.
It lets you generate stars as well as show them on a number of map types. I've fiddled around with it before, and I *think* you can do things to make constellations, too? There's definitely a "Celestial Sphere" sort of display mode, and you can set a lot of things up with it, too.
[Answer]
I'm thinking Kerbal Space Program maybe?
It's a game about launching rockets and exploring space from a fictional planet named Kerbin. Kerbin has two moons and exists in a different solar system than our own, complete with made-up planets some of which have their own made-up moons.
I know that people have made mods to make change the in-game solar system from the fictional one to a model of our own solar system. If the solar system can be changed like that, then you can make a mod (there may even be modding tools to help you) that puts your desired solar system into the game. You could make your own planet, moons, sister planets, comets, and your own skybox for the stars. When I say a mod I don't think it'd be a big overhaul or anything. You'd probably just have to define the parameters of the solar system in some file and load it in.
Then you could walk or fly a Kerbal astronaut around in the game and see what your protagonist would see. There are mods to turn off the HUD for better screen-captures.
] |
[Question]
[
**Closed.** This question is [off-topic](/help/closed-questions). It is not currently accepting answers.
---
This question does not appear to be about worldbuilding, within the scope defined in the [help center](https://worldbuilding.stackexchange.com/help).
Closed 1 year ago.
[Improve this question](/posts/197969/edit)
In order for magic to manifest in this world, one has to recite a specific incantation following a visualization of the anticipated result, and only then will the magic occur. Amazingly, many students from the special school of the disabilities, especially the mutes, seem to be able to perform magic unaided. This appears illogical because, in order for magic to be performed successfully, one must not only speak intelligibly but the pronunciation must also be accurate! Since the invention of voice synthesizer and electronic recorder didn't happen until much later, how do the mutes cast magic spells which require an incantation?
[Answer]
**Ravens!**
Just as blind people can be given a well-trained guide dog, those who cannot speak can be given a trained talking raven.
In your scenario, this type of raven has been bred over centuries to be the best possible of mimics. They are trained from an early age to recite incantations in response to hand signals.
The requirement of magic is that the voice must come from close proximity to the thought. The raven perches on the mute mage's shoulder and that is just as close as the person's vocal chords are or would be.
Even ordinary ravens are capable of this to some extent. Just imagine how much better they would be after generations of selective breeding and maybe even a little magical enhancement.
[**Ravens can talk!**](https://youtu.be/AfsnHVaScjg?t=8) (video)
[](https://i.stack.imgur.com/4RBvr.jpg)
[Answer]
**Words aren't important**
It was never about the incantations but the mindset formed saying the words.
In the Marvel Movie Doctor Strange, Strange says to the Ancient One he can't cast due to the injuries to his hands at which the Ancient one shows him a caster missing a hand completely.
Magic is all in the mind. Incantations, mystical ingredients, hand movements, artifacts all do nothing except assist the person to reach the correct state of mind to cast the spell exactly like Dumbo has a "magic" feather that helps him fly.
[](https://i.stack.imgur.com/RsN3l.png)
[Answer]
I guess the [Pied Piper of Hamelin](https://en.wikipedia.org/wiki/Pied_Piper_of_Hamelin) came out of this school.
The trick is being able to find a translation of the spell which works well when it is casted by playing the appropriate sequence of notes in a musical instrument, be it a piper, a flute, a harp or any other instrument with a sufficient extension.
Once the key is properly played, the spell is activated.
[Answer]
Nobody realized it is not the sound that is important, but the magic is *gesture* based - and specifically, the Magic Recognition System is tuned to very accurate movements of your lips and tongue (who said gestures have to be performed by hands only?). For the speaking folk, the "precise pronunciation" is just a side effect of this precise mouth movement. And as everyone who learns foreign languages knows, phonemes you learn in your childhood influence very much the set of phonemes you are able to reproduce accurately (AKA "having an accent"). Thus assuming you learn the magic in your adulthood, the speaking folk has quite a trouble mastering weird and quickly changing mouth shapes, but the mutes are not hindered by their ingrained language (unless they are mute because of a physical deformity, like missing tongue or equivalent).
[Answer]
Sign language is as legitimate a language as any spoken one. The same parts of the brain are used in the "recitation", and that's all that's necessary to cast the spell?
And, yes, there's no reason sign languages couldn't have existed in the Middle Ages. Deaf communities naturally create them ex nihilo if necessary.
[Answer]
>
> Since the invention of voice synthesizer and electronic recorder didn't happen until much later
>
>
>
As a general world building rule, in any system where you have magic but lack a technology that would be helpful to your plot, you can usually find ways to replace the technology with a magical equivalent.
Need to fly but don't have planes? Use a flying carpet.
Need long range communication, but don't have phones? Use a [palantír](https://en.wikipedia.org/wiki/Palant%C3%ADr).
Need an army of killer robots, but don't have robots? Build constructs.
So, just having a lack of technology does not really preclude your setting from having any modern wonder you want, including voice synthesizers.
To resolve this, have mages who are able to speak use their magic in lue of technology to record their voice performing incantations into magical stones, scrolls, wands, or what ever best fits your setting. Then when it comes time to cast a spell, the mute mage need only tap the enchanted object, and it will recite the spell while he performs the necessary gestures.
**A Possible Frame Challenge:** If your setting has healing or transfiguration spells, you will want to address the elephant in the room about why you would ever have a disabled mage to begin with. If a disabled mage gets to the point where he is casting magic, his first priority will probably be correcting his maledy; so, the very concept of the Special School of the Disabilities may actually be flawed unless you put some very clear limitations on what magic can do in your world.
[Answer]
### Define "mute"
There's a common trope in fiction about someone having their tongue cut out to prevent them being able to talk. [Shakespeare used it](https://en.wikipedia.org/wiki/Titus_Andronicus), and he got it from [Ovid](https://en.wikipedia.org/wiki/Metamorphoses), who probably got it from somewhere else. Of course you'll find it in [Game of Thrones](https://gameofthrones.fandom.com/wiki/Ilyn_Payne) as well.
And it's entirely factually incorrect. I have personally met a girl who had no tongue, and she could talk intelligibly. It took a bit of work to "recalibrate", but it was doable. Her speech was rather similar to that of some people with [cerebral palsy](https://en.wikipedia.org/wiki/Cerebral_palsy), who may not have the necessary control over their tongue for fully "normal" speech.
The sounds we produce in language come from breath control, from the vocal cords, from the tongue, and from the lips. The loss of any one will certainly be an obstacle to fully "normal" speech, but it need not prevent it.
* If you eliminate the tongue, you still have access to all vowels, to the "plosive" letters B, M and P, and to the "fricative" letters F and V (and S and SH by using teeth instead of tongue to restrict airflow). With a bit of work, CH sounds are OK too, and sharp exhalations (using breath control) can fill in a bit for some other sounds. If your incantations can be limited to those sounds, there's no reason someone without a tongue couldn't still perform perfectly well.
* The loss of lips would limit different sounds. In this case the "plosive" letters are lost, and some "fricative" letters. Teeth can still substitute to some extent though, and mouth shape is still enough to produce vowels reasonably effectively. If your incantations are all about vowel sounds, that will still work perfectly well.
* The loss of vocal cords will naturally reduce the volume - but whispering is (basically by definition) talking without engaging your vocal cords, and we all know that works. Some letters require vocal cords to be produced - the difference between "f" and "v", or "s" and "z", is down to your vocal cords. If your incantations don't need those sounds, or those sounds don't need to be distinct, they will still work. This would also be a clue that only a low minimum level of volume is necessary for an incantation - Gandalf could whisper "you shall not pass" and it would be just as effective as declaiming it forcefully.
Basically, only the complete inability to consciously control breathing would prevent any speech. Anything else, people can deal with to some extent; and then it simply depends on whether what's lost in translation is important for your magic system or not.
Finally we also need to consider [selective mutism](https://en.wikipedia.org/wiki/Selective_mutism). People may be unable to talk in some settings, but have no problems in others. Someone with selective mutism may be unable to talk to other people, but be perfectly able to voice incantations.
[Answer]
Mute people are generally able to whistle. They may use a whistling language such as [Silbo Gomero](https://en.wikipedia.org/wiki/Silbo_Gomero) *in lieu* of a regular spoken language to form the incantation of a spell.
Alternatively, they may use [pasgas™](https://worldbuilding.stackexchange.com/q/129387/21222) for the incantations.
Finally, it may be that the visualization is what is important. As you visualize, you must also hear the incantations with the "ears of the mind", much like you can recall and "listen" to a song inside your mind. Speaking or singing an incantation is just a surefire way to get the proper incantation in your mind. Mute casters have trained so as not to need to speak, they just hear it inside their heads and thus are able to cast successfully.
[Answer]
[](https://i.stack.imgur.com/eZfnF.jpg)
Wikipedia tells me in the Tibetan Buddhist tradition, spinning wheels with prayers written on them has much the same effect as orally reciting the prayers.
Perhaps mutes have discovered **something equivalent to speaking the incantation** that doesn't need them to speak.
Perhaps the technique is kept secret by mutes, out of solidarity: All their friends from the school for mutes are keeping themselves employed as spellcasters using the secret technique, and revealing it would leave them all unemployed.
Or maybe the technique is something well known, but only available to mutes - maybe making your vocal chords resonate with the magical aether allows you to subvocalise your incantations, but you've got to go 90 days without speaking to achieve that resonance.
[](https://i.stack.imgur.com/zdInh.png)
Or you could make mutes' extra ability religious in origin - sure, in our world **monastic vows of silence** are mostly about quiet contemplation and even the quietest religious orders talk some of the time. But maybe in *your* world there's a god-like power who just really likes silence, even without worship of contemplation. It could even be a mysterious forgotten god, and mutes have satisfied it by coincidence.
[Answer]
**Language in all it's forms**
There are two requirements: incantation and visualisation.
An incantation is a series of words that form a spell. An incantation is thus just as valid on paper as spoken. That means the incantation can be done in any form that represent those words. On paper this can still be difficult, as some of the subtleties have to be described instead of written down ("It's *leviosa*, not *leviosa*). Still possible if you devote some more time to the written language, but difficult.
Some forms like sign language could add these subtleties in each movement of the hand for example. So any broadcasting of the incantation of any form of language is valid!
[Answer]
**Frame Challenge: Translators May Be Necessary**
If you decide to make magic more mental than physical, Thorne's answer is correct. If music, ravens, or gestures could do the trick, those respective answers will be correct. However, you said one has to *recite* the incantation but mutes are casting regardless, seemingly without aid.
Well, guess what? The term "mute" today is specifically applied to a person unable to use articulate language due to deafness. And deaf people *can* speak, it's just very difficult to learn how to make the sounds and know what you're saying when you can't hear. In other words, deaf people should be able to chant and therefore cast just fine, albeit with more effort.
Alternatively, if by "mute" you mean anyone who through a mishap or genetic disorder cannot speak, being mute does not necessarily mean being unable to create sound. Think about it; breathing in and out makes a sound now doesn't it? And whistling doesn't require vocal cords at all! Therefore, mutes can create a language of their own based off those sounds and cast with it.
Breathing could be used in a sort of Morse Code, with short, forceful puffs for dots and longer, drawn-out breaths in between. Whistling could be used to sing a tune, and if the tune corresponded to musical notation for a spell, it could count as an incantation. **Or** you could have a translator.
Seriously, what's wrong with a translator? In *Harry Potter*, one of the most popular stories about mages, it's *technically* possible to cast without a wand, but few people ever do because it's so very difficult. Perhaps most mutes are the same; they need a translator to recite the incantation they're signing, but they also know some mutes, through extensive training and sheer force of will, can cast with only their *thoughts*.
The fact that the mutes are seemingly unaided could come from a telepathic link; if magic is an expression of who you are (just like your unique way of speaking), then translating for someone could forge a powerful bond between the translator and the speaker. Basically, when the mute wants to cast, the translator senses their intent and speaks for them.
You may not like this idea, but it has *so much* story potential. Perhaps a mute-translator pair casts stronger spells naturally, because both are contributing their will and/or mana to the casting, or perhaps they share the *cost* of spellcasting with each other. It could even be both!
This mute-translator pairing could also serve as a check on powerful mages; just as the translator gives voice to a mute's will to enable their casting, a mute can do the reverse (give silence in the place of speech), therefore preventing their translator from casting. All in all, this was a very interesting question and I hope my ideas help you.
[Answer]
## Magical compulsion.
Some people lack the ability to speak due to paralysis of the larynx. They cannot send nerve signals to make themselves speak.
However, a magical spell can be cast on them to *force* them to speak, whether they like it or not, operating their muscles according to *that* caster's dictate. That spell can even be cast in advance, to force them to speak the incantation when they make a specified gesture.
The dark practitioners of that grim school of thaumaturgy are more than eager to demonstrate that they can transform the lives of the disabled, just as designers of brain-computer interfaces wax enthusiastically of their plans to improve the lives of paralyzed veterans.
[Answer]
Not sure if you find this applicable, but in Dungeons & Dragons, there's a metamagic feat called "Subtle Spell" which allows the caster to disguise material, verbal or somatic component of the casting (or was it all three at once?), so technically a mute character could cast the spells non-verbally with this feat.
[Answer]
**Its not the sound that actually matters, but instead the mouth movements.**
In your case the magic is drawn out of the body when you breath. This magic is without an purpose so just "sits" near the breather who then breaths it back in in the next breath. However, if you make the right mouth movements (which in a normal person just so happens to also be recognizable speech) the expelled magic now knows what to do and goes and does something useful.
[Answer]
A common concept in Magic is the use of familiars - an animal with which the caster has an extra-sensory connection. Using the Raven example from chasly's answer, if a mute person has the aptitude for magic, they are paired with a familiar capable of speech. They then use their extrasensory (psychic) link to speak through the familiar. This provides the full combination of framing the thoughts in their minds, exercising the power of their will, and voicing them aloud (through the familiar), and leaves their hands free for any gestures that may also be required.
[Answer]
*I also include and work on the base of other answers, giving credit to their original authors and linking them.*
---
## What Is Your Magic Based On?
* Do you have to be ***born with*** a gift (like the wizards in *Harry Potter*)?
* Can ***everybody* learn** magic? (Maybe with a little natural
talent involved, like music or complicated mathematics or any craft; a simple fire spell might be as common as matches!)
* Maybe there are ***different kinds*** of magic in different parts of the world, either forgotten, banned, not yet detected or rejected by other societies.
In *Harry Potter* house elves use a different kind of magic to which different rules apply, in *The Last Airbender* the different elements are controlled in different ways.
This might affect, if **the spell just *helps* the magic user *to focus and channel his own magic*** or if **some sort of articulation is needed**.
---
## Visualizing Magic
Another big question is, if you need to simply **visualize / articulate** the content of the spell ***somehow***, or if you need actual **actual words/language**.
## Non-verbal
As [L.Dutch](https://worldbuilding.stackexchange.com/a/197970/67222) already mentioned, there are more forms to **express yourself in detail, without language**...
**Music** lets you *feel* the emotions and images the artist wants to convey.
In Asia and the arabic world **calligraphy** is an eminently respected craft. At first glance you might want to distinguish the spoken / performed magic from the magic texts. On the other hand there is a long cultural tradition of belief that writing holds magical powers, from ancient Egypt to the Great Plague of London in the 17th century when the spell ABRACADABRA was used as a safety measure. And (written) magic symbols, sigils and summoning circles are commonly used in fantasy.
Different articulations to perform magic might be **distinct to different cultures**, with native tribes using **ritual dances** (e. g. *rain dance*), while master **craftsmen** are able to incorporate simple blessings or defense magic into temple **guardian statues** and **lucky charms**.
Developing that concept further, **every art form and every means of communication** holds the potential to envoke magic, however, over time rituals and spells have been passed through by famous teachers, setting the foundations for the different magic traditions in your world, as manyfold as those in our very own.
## Actual *Languages*
If the precise recitation through actual language is needed, this could also include **whistling** (mentioned by [The Square-Cube Law](https://worldbuilding.stackexchange.com/a/197982/67222)) and **sign language** (mentioned by [Trioxidane](https://worldbuilding.stackexchange.com/a/197974/67222) and [Robert Larkins](https://worldbuilding.stackexchange.com/a/197984/67222)).
Aside from the mutism aspect it makes a huge difference in general,
* if it is only important to **understand** what you are saying
(every mage casts in their mother tongue),
* if there is **only one magic language** (like in *Eragon*)
* incantations **work, even if you don't understand** the language you use
(like the *Sectumsempra* spell in *Harry Potter VII*).
Another question is, how intricate spells are: Just controlling/summoning something by one word ("fire!") and the thoughts on how you want to use it shape its form (a wall or peak or blade of fire) or does the magic effect have to be described more detailled or with stipulated hexes ("giant wall of flames!").
Magic users could ***invent* their *own* languages**, making it **impossible for enemies to foresee what attack to parry**. They even might develop a language that **use the same words of an existing language but with switched meanings** (saying "fire" and creating a blizzard). Or simply thinking outside the box and repurposing magic spells in a way an observer can't predict the outcome (casting "water" to stop the bloodflow of the enemy's body).
At this point I would like to reference a concept of my own from another question, the [***spellsword***](https://worldbuilding.stackexchange.com/a/153140/67222), **comparing *curses* to new commands in a computer program**:
Instead of always having to cast "a flaming sword of three feet length should appear in my left hand right now" during battle, you could (depending on your magic system) cast a *curse* like "a flaming sword of three feet length should appear whenever I say the *codeword* abracadabra or make this special hand gesture".
A *curse* being placed over something beforehand and being activated, when something is done (stealing the cursed Aztec gold, Sleeping beauty touching the spindle etc.)
---
## Mute Mages vs. Spell Casters
**Verbal magic** might be **easier and safer** but also **limits the user** to the spells he has learned and especially *how* he learned to apply them, making it harder to think out of the box, while **nonverbal magic** is much **harder** to master but allows a **more intuitive** and free approach. A spell caster casts fire to burn an enemy, while a mute magican just disintegrates the enemy (Thanos style). A spell caster either uses the spells for "rock" or "fire" to reshape a boulder while a mute mage just *reimagines* the outcome. Therefore maybe mute people might be less likely to master magic but those who do are outstanding.
It could be possible, that verbal and nonverbal magic have **different weaknesses and strenghts**, e. g. non-verbal magic being better suited for creating, while verbal magic allows quicker fighting.
Also possible: Not being able to speak generally elevates the magical senses (a disabilitiy leading to other heightened abilities).
---
## A Question of Society
There can be reasons why non-verbal magic is **not accepted in society although not being much different** in effect. No world is perfect and each has its own forms of exclusion, injustice and thoughts of surpremacy, cf. the historic role of women or white surpremacy.
* **Words stand for control, order and tradition**.
The [first known grammar](https://en.wikipedia.org/wiki/P%C4%81%E1%B9%87ini) was an attempt to preserve the original language of holy texts. A quasi-religious, quasi-military magic order could be interested in maintaining the sacred order of yore. Compare, as an example, the various religious secessions, reformations and counter movements that have been bloodily put down by the major religions throughout history.
* It is also a **question of teaching methods and educational understanding**:
Either seeing unfit children who keep their fellow students back or children who need special support to unlock their potential.
* And, as [Willeke mentions below](https://worldbuilding.stackexchange.com/a/198104/67222), historically mute people were taken for **stupid**.
(Btw. I didn't think of that argument myself but didn't want to omit a good point after I read it)
* Magic that solely relies on focus and willpower is more **dangerous** (imagine *thinking* a death curse while suddenly being distracted by your hot spouse).
* The use of magic could just be deemed **unthinkable** for mute people **in a society** centerd around magic spells, just think of the role of women in religion, society and war over the last couple thousand years. There might even have been some famous exceptions without changing the overall view of the people (cf. historic exceptions of female leaders and warriors).
* Here, mutism might be seen as a large **humiliation**.
* There was the thinking, that the appearance of a person matches their
character - someone hidious must have a terrible character, deseases and desasters are a punishment by God and humans are not allowed to interfere with
**divine will and fate**. Maybe (in your world) lore has it, that if a child with magic
abilities is born mute, this is divine intervention to prevent the
world from a powerful evil wizard or to punish you for your past life (cf. the Indian tradition of rebirth and social castes or the positions one was born into in medieval Europe).
* Verbal magic could be part of an **honor code**: The performer is revealing themself and enabling the opponent to react, similar to the regulation of concealed weapons or the *Geneva Conventions* or the difference between a honorable duel an a dastard murder. This also proves a magic action to be a willing performance, not just a **lack of control over one's magic powers** (cf. *[obscurus](https://harrypotter.fandom.com/wiki/Obscurus)* in Harry Potter). In *Eragon* a magic duel consists of an attacker and a defender reading the attacker's mind to be able to defend themself from the anticipated strike.
* Verbal magic might be considered more **civilized** in comparison to the "wild" tribes performing intuitive magic (cf. colonial Europe).
* There might be a rivaling empire, approaching things very differently (some being evil, some bad, some just different) E. g. commonly accepting non-verbal magic (more inclusive than your kingdom) while also commiting human sacrifices (evil). Therefore non-verbal magic is connected to the evil and wrong practices of the **enemy**.
**To sum up:**
Mute children require **more effort** (a personal tutor, ideally with the same handicap, as the **academy refuses mute acolytes**) by the parents who are **ashamed** and disappointed by their offspring and **underestimate** them. Furthermore it is a **sacrilege**, according to society, religion and tradition. So how often do children actually find their way into the special school for unusual circumstances? How widespread is the word of that institution at all? **Even if mutism doesn't make that much of a difference on a magical level.**
This ***might* change**, if e. g. a war or a loss of mages boosts the need for more, through a social revolution or a mute hero or royal successor. However there is no guarantee.
[Answer]
A friendly wizard visited the school for children with special needs, and cast spells to make their lives easier. The boy with no feet was blessed with the power to levitate, the boy with no eyes was given an ugly and slightly mischievous imp that whispers in his ear what it sees, and the girl with no voice was inflicted with a curse that makes her innermost thoughts echo audibly around the room.
The teachers were annoyed by these disruptive gifts and did not invite the wizard back the next year.
[Answer]
To answer this question you must first define how the voice act in the casting of the spell. What part of the "saying a spell out loud" enable the spell to be cast?
Is it the vibration that get created in the air? If so, is it possible to reproduce the spell by achieving similar vibrations with instruments or props?
Or maybe the sound must be produced by the caster himself, because it need to be "imprinted by his personality/spirit/whatever". If so, does the sound has to come from the vocal cords of a person, or can be generated by whistling/clapping/whatever?
Or is not the sound the important part, but the fact that by pronouncing it you are less prone to mistaking your intention with something else (If you have read Eragon this may sound familiar)? In this case with adequate training you may be able to do it.
You mentioned voice recorders. If someone is able to cast a spell by using a voice recorder, how is he able to do that? Is the sound (vibration?), is the "intention" to cast the spell being recorded with the voice?
Answering this questions may help you come up with an answer.
[Answer]
Posted as a comment but I am asked to post it as an answer:
As far as I understood, mute people in medieval times were seen as 'unteachable' and 'dumb' in the sense of having no intelligence.
So if someone was born without the option to learn to speak, it was very likely that they would never learn enough to need those incantations.
Having lost speech as an adult, they would likely face a lot of problems and not being able to do magic would only be a small one.
Added to fill out the answer:
In our current western world people with handicaps are seen as fully able people who have some restrictions. But in big parts of the world today the situation is not as good. And if you go back in our history, even 100 years ago people with handicaps had it a lot worse. Not being seen as fully human is one thing, seen as valueless as a mongrel dog that has lost it usefulness was more likely in many cases.
Go back 3 or more centuries, forget special education. In fact, most people did not get any education and those who were not fully able to keep up with the brightest would not get any education if they were not the children of the very rich.
And even the rich would often not admit that they had a child less than perfect.
Of course as a writer you set your own world, you may be able to make a setting in which a person without speech can function as a full human, but it will not be as it was in our history.
[Answer]
This is not my area of expertise, but I believe that Deaf linguist William Stokoe hypothesised that humans might have developed sign language before spoken language. I don't know how widely this is accepted, but you could simply decide that this is true in your world.
In such a world one could imagine that magic preceded speech and that the incantations are in fact transcriptions from earlier sign language based gestures.
This has all sorts of potentially interesting ramifications.
In our own world "oralism" is known to the educational movement which sought to suppress sign language use amongst the Deaf and teach them to 'speak'. This was hugely damaging to Deaf communities, leaving many Deaf people with only a limited ability to communicate.
In your world, one could imagine a parallel to oralism which sought to suppress sign language because it gave people access to magical powers which authorities feared.
(Although as I write this I realise the risk of slipping into the [Disability Superpower trope](https://tvtropes.org/pmwiki/pmwiki.php/Main/DisabilitySuperPower).)
] |
[Question]
[
**Closed**. This question is [opinion-based](/help/closed-questions). It is not currently accepting answers.
---
**Want to improve this question?** Update the question so it can be answered with facts and citations by [editing this post](/posts/121909/edit).
Closed 5 years ago.
[Improve this question](/posts/121909/edit)
I have recently discovered that I have a superpower: based on a situation, my superpower creates a superpower for me to use. If I'm drowning, maybe it will shapeshift me gills and fins, or allow me to telekinetically attract air bubbles, or just remove the need for breathing altogether.
It tends to start with a certain theme: say, light, time, physical objects, emotions, sound, electricity, chemical reactions, metal - you get the idea. Then it modifies this raw control over the theme it's interested in at the moment and shapes it into a power relevant to my situation. To get from chemistry to flight, maybe it comes up with the power to create combustion at will, which I can use to rocket propel myself.
The problem here is kind of obvious: why am I not a god, then. I always have the perfect power for any given situation, right?
---
My past attempts as a writer to weaken this power have usually resulted in the character having immense potential but never using it because of lame plot reasons, or the character having a superpower that does all the work for him but he somehow messes it up every time, neither of which are any fun.
The character lives in a world of superheroes, where about 2% of people have powers ranging from super weak to extremely powerful, but I want this character to fall into the 60th to 80th percentile of power strength so that there's still room for non-strength-based problem resolution. In general, I'm trying to use power limitations that are less made-up sounding (so not: he can only use his power on a full moon or something). The pattern that seems to have arisen is that powers themselves have few limits, but the connection between human and power is what causes the limits. Since all powers in universe use the same mechanism, sticking in limits this way should affect all powers, not just one, which makes limiting this one a bit harder.
What are some possible ways this power could be made more fair? I'd prefer solutions that modify the world the character lives in (or 'powers' in general within the universe) rather than the core mechanism of the power, but I understand that small caveats are inevitable.
[Answer]
# Your power manifests itself in ways you don't control.
---
You mentioned that your power manifests itself in a way that could be useful to you, but who is defining what's useful? If you're drowning it's pretty obvious that gills and fins might help.
However assume your entire city is about to get nuked, your power may manifest itself by making you bombproof and radiation proof, or allowing you to teleport away. You can now save your own life but this does absolutely nothing for your desire to save the city.
This has interesting implications in story terms as it creates a hero who is infinitely powerful when it comes to self-preservation, but frequently helpless when it comes to saving others. Their ongoing journey as they learn to adapt to what they're given to try and help others would be fascinating.
[Answer]
This might not be the answer you're looking for but I'll give it a shot:
## Apathy(or the Doctor Manhattan Solution)
Your character is essentially a god, so why shouldn't he have the viewpoint of one? He doesn't act often because he no longer sees things the way humans do. When he does act, his "heightened" perception has also made him extremely aware and mindful of all the minute details of the consequences. Hence he tends to work in mysterious and/or subtle ways.
[Answer]
**Comprehension and adaptability are your problem.**
You might spontaneously gain the ability to breath underwater, but you're not going to realise this until you suck in enough water to kill yourself otherwise. You're still panicking and thrashing around basically until you would otherwise drown.
You might not have any cue that you've gained a power, so if you're falling off a building and spontaneously gain the ability to fly around like superman, you've got to realise this and make a conscious effort to do so otherwise you slam into the ground as normal.
If you're not constantly experimenting with your powerset, you might not know what you can do and therefore routinely miss out on opportunities that you could have taken advantage of.
You'll **never know your own limits** either because you won't have time with the powers to push them.
You might see a kid and a grandma about to be hit by a bus and have to make the decision which one to save with your super-speed..and not realise you're perfectly able to save both of them if you tried to run a bit faster.
You might dodge the shot you could have tanked, things that can't harm you make you flinch.
And then there's **super-senses.**
The setup of Man of Steel played a lot on the way superman adapted to his ability as he grew up, and the other kryptonians that arrived on earth as adults were really unused to their newfound strength and super-senses, they found super-senses truly disorienting and had to take time to acclimatise.
You gain and lose new abilities all the time as you need them and constantly become disoriented. "What's this new colour I'm seeing?" "Oh god I can see inside people!" "What the hell is that annoying sound?" (said annoying sound turns out to be the ticking of a clock in the next building)
The shifting power-set will be confusing, disorienting and at its very best you'll be permanently learning and relearning your limitations.
There's your balance factor :)
[Answer]
Sort of reminds me of that film Bedazzled, where the protagonist would ask something of the devil, but every time it was always skewed in some way against him.
For instance, perhaps your hero is off the coast of Japan, at a large boatyard, being pursued by a gang of gun toting men intent on his destruction for some past slight against them involving another 'superpower', the hero transforms into a gilled aquatic subhuman and dives into the waters below, meanwhile the pursuers acquire a boat by illegitimate means to continue their pursuit. Then your hero comes across a whaling boat and other trawlers during his escape who also decide to come after him.
Just set your hero up so although the power may be good for one particular situation, it might not be best suited for another, so odds eventually stack up against him. Like being chased through a field, transforming into a crow and then being shot at by a nearby farmer.
Something like that. Unless you want the hero to do everything, wreck every opponent and have little challenge, you'll find some creative way.
[Answer]
Assuming there is a limit to the number of powers you can develop at once.
The power gives you the powers you need not the powers you want.
You want to save the city, you want to stop the bank being robbed, but you don't need it to survive. sure this makes you strong in combat and you won't be defeated but that does not mean you save the city.
lets say you are fighting a super powered villain who fires powerful lasers from their eyes, sure it would be real convenient for you to become immune to damage, but what if instead your power makes you 100% reflective. Great you are now a human disco ball shining lasers of death in all directions.
maybe you get poisoned, sure producing an anti-venom is a no-brainer, but what if the ability you have developed is the ability to transfer your ailments to people nearby or expel it as a gas cloud.
This can be even more limiting if his power doesn't work the same way each time, sure last time the knife just snapped, but maybe this time you are just going to regenerate after you pull the knife out.
You are powerful, you are good, but you are forced to be chaotic good.
[Answer]
The lack of choice in how the power manifests is a limit. One that you can make quite debilitating if you choose.
If muggers pull guns on your family a godlike being might stop time, or put up a shield around the whole family, or affect the attackers minds or come back from the dead and resurrect the rest of the family or kill the muggers with a super fast and super strong attack.
Your character might become bulletproof allowing the family to die or teleport away allowing the family to die or even burst in to a super hot plasma melting the incoming bullets, incinerating the muggers and the family.
Even one such incident might result in a character who is afraid of what might happen if they are put in a situation where a power might manifest and will try hard to avoid that.
That could even be a part of the power. The character gets what they need but in the worst way possible.
[Answer]
The mechanism doesn't come for free, but takes a toll on the hero's body, consuming energy: i.e. they can get gills if they are drowning and reach the surface, but then they won't have enough energy left to also start flying. If they overuse their power they get practically consumed.
In this way the power is naturally limited, and the hero has to carefully choose when to use it.
BONUS: in this way you also self-prevent super recovery, because obviously it cannot be used as first.
[Answer]
## Unlimited diversity is not unlimited strength
Simply make your character's superpowers relatively weak compared to superpowers of others capable of doing the same thing. For example, your character can do telekinesis (because he can do *anything*), but he will typically lose a purely telekinetic fight against a dedicated telekinesis wielder not capable of any other superpowers. He is the ultimate jack of all trades and master of none.
[Answer]
# Depression
>
> *She's ageing more noticeably every day, while I am standing still.*
>
>
> *I prefer the stillness here. I am tired of Earth, these people.*
>
>
> *I'm tired of being caught in the tangle of their lives.* — [Dr. Manhattan, Watchmen](https://www.youtube.com/watch?v=ATDmVbHIQ7E)
>
>
>
So you have everything you could ever have wanted. You are invulnerable. You can fix any malady. You can do whatever you want.
...and that is such a **lonely** place.
You have no-one that can relate to you. There is no-one that can ever grasp your situation. Instead everyone comes running to you and ask — no, **demand** — that you take care of their problems, while they keep scheming and quarrelling and arguing in their petty ways.
Sure... you can dive head first into every situation. But what awaits you tomorrow other than **more** trouble to fix? As the cynical adage goes: "The reward for work done well is more work". There is no struggle. No hurdles to overcome. There is no reward for feeling your effort was well spent.
Unless you have a superpower that protects you from the human condition itself, you will be depressed and apathetic soon enough.
[Answer]
Add a system of Karma regarding people who have powers.
Imagine that for every gift a person has, a trial awaits that person. Someone with super high telekinetic abilities might be cursed with muscle atrophy. Someone with super strength may suffer from a perpetual hunger.
Then have the trial proportionate to the ability. Say someone can make flowers out of thin air, just like a magician. They are cursed with being bad at cards; like losing 95% or more the time. Inconsequential powers have inconsequential trials.
But strong powers have larger trials. A superhero who can shoot powerful lasers may be blind, or be forced to face a super villain who has an equally strong force field.
So basically whenever he activates a power, he also activates a trial that could either be permanent like being bad at cards, or only lasts until the power ends, like being able to breath underwater, but for the duration of the power sharks will try to eat him. So activating his power is not only dangerous because he could get a strong power with a permanent trial, but a temporary trial that only lasts as long as the power may be as deadly as whatever situation he's trying to avoid.
Addition: The Karma could also build up into a climax type moment, like the more powers he uses, the stronger the anti-hero gets. He could periodically face off against anti-heros so sometimes they'll not have that much power because he has low karma, but sometimes he may use his power a lot in between anti-heros, leading to a very powerful anti-hero to overcome.
[Answer]
### Don't gain it, borrow it
You don't get your new superpower out of nothing, there's someone somewhere that loses it. For example: you develop gills but some aquatic creature develops lungs (effectively killing it in most cases); you gain the power to control fire but some supernatural being loses it, and may not be happy about it.
This may lead to angry supernatural entities and moral problems for unwilling deaths you may cause when borrowing powers.
[Answer]
**Persistent Novelty**
Just from the situation that you've described, "it comes up with the power to create combustion at will, which I can use to rocket propel myself." So, you are falling and need to learn how to control a new power which makes you a jet engine, **before you hit the ground!**
Imagine how traumatizing it would be to suddenly not need oxygen! Then to need it again once you'd become accustomed to not breathing.
This sounds like a recipe for disaster to me and a creatively diabolical one at that. Your character is given the perfect power, but doesn't understand how to use it. At just the moment they gain some mastery over it, it changes to something else. BRUTAL!
Severely limiting. Rather than being a god, this character is always one step behind. Not only do they need to figure out what their power has become (it's not like someone tells them), but they need to figure out how to activate and control it. By the time they have it understood, someone else has done all of the heroing.
The awkward, ineffective, learning-to-control-their-powers phase is essential superhero prerequisite. Your hero is stuck in this phase forever, sadly, comically, frustratingly, self-defeatingly.
Sounds like a relatable and interesting hero.
[Answer]
A large part of my answer is already covered by MGDavies, Ruadhan, and others, so I'll skip to the unique part.
## The power is too helpful
Worried that your date will like you? Now you have pheromones!
Worried that you will fail your test? Here's telepathy! (Which is horribly distracting, and you're too ethical to use it to pass the test)
Your power keeps giving you "solutions" to problems that are better solved by mundane means.
[Answer]
Seems like horror [Outer Limits](https://www.imdb.com/title/tt0112111/?ref_=tt_urv) episode [The new breed](https://www.imdb.com/title/tt0667978/?ref_=ttep_ep14)
Nanobots can repair your body and create new features. But they are not undoing them. They are creating features you did not expect or want. So slowly you are transforming into a monster.
Also this nanobots need time to decide and implement what you need - first you drown, they repair the damage and only then they transform you so you can breathe underwater, so you did not have superpower in the moment of need.
[Answer]
From your description, you've made it sound as though this super-power has a kind of personality, perhaps you should build on this concept.
The power could be fickle and distractable, often giving half hearted or short-term solution to problems which can cause their own problems (like having a god-like dog that you have to train well and hope it will fight for you)
The power could have strong self-preservation instincts and try to keep its host safe and away from danger at the expense of those you are trying to protect.
Or, contrarily, it could thrive off danger: It seeks action and drama and often puts its host and others in great danger to amuse itself; having no allegiance to good or evil but just a desire to be entertained
[Answer]
Direct power limit. For example you have already arranged powers in percentiles, and each percentile has a certain maximum power it can offer. So if you need to be breathing under water you can, but if you start going deeper and deeper the pressure starts rising and your power eventually cant compensate anymore.
Time bound. It takes a while for your body to adapt. If you already have an ability active it takes longer for your body to adapt to a new one. This makes it relatively easy to adapt to the beginning of a crisis, but as it drags on and other powers are necessary your hero will need to make due with what he has. this allows a large variety of challenges for your hero depending on what happened before. In combination with a power limit the hero might be able to divide the power across multiple abilities but have to pick and choose, meaning he wont have the full benefit of some of the abilities he gained and still has to struggle.
[Answer]
## Energy drain
Switching from one power to another costs him energy, which
1. is the same as a normal human's energy reservoir and returns after a normal human's energy refreshing rate, ie. sleeping, eating, energy drinks, etc. This will also weaken his power when he's generally out of energy after a night of partying for example.
2. is not the same energy reservoir but a superpower reservoir, that refreshes over (non-switching or non-usage) time, so he's not able to switch moment after moment but only after some minutes or hours. In battle, fighting two opponents with different powers, this causes him huge trouble.
This could be refined further, you could allow him to add in additional powers but this will limit him to the set union of these powers. After he switched to earth, he might be able to add in fire, which allows him to create a volcanic eruption but no longer allows him to cause earthquakes or blast a darting flame out of his hands. This would allow him to react to new dangers within the "cooldown" but with a tight limiting factor, so it's a constant balance and tough decision. It may also cost him additional energy, but much less than a complete switch.
[Answer]
"As needed" is awfully unreliable. Here is a spoiler about a superpower in the "Dr McNinja" comics:
>
> Chuck Goodrich is a time astronaut incidentally protected against attack by an awful powerful spectre, a Nasaghast. When he tries to save the world from a terrible future, his coalition is put to pieces by a terrible monster that isn't interested in him. So his protective power is not interested in interfering. [This ends badly for him.](http://drmcninja.com/archives/comic/21p87/)
>
>
>
[Answer]
A few thoughts:
1. What if your hero’s powers manifested in non-life-or-death scenarios? Maybe he’s got to do some public speaking in college, and he gets super nervous being the centre of attention, so his superpower teleports him away uncontrollably, or forcibly deafens and blinds everyone else in the room. Or he’s startled by a car horn and he accidentally produces a six-foot radius forcefield that vaporises everything it touches. It’s fine when he needs to respond to *actual* emergencies, but from day-to-day, it’s just really difficult to fit in and function normally.
2. Maybe his superpowers don’t switch off until the next urgent situation. He’s been dropped into the sea and now has gills, great. Unfortunately, his powers now think that he’s safe, so they force him to stay underwater until the next crisis. If he tries to get out of the water, he gets teleported back in because that’s the environment his body has now adapted to. He’ll have to wait until a meteor plunged into the water next to him in order to develop flight, which he then can’t switch off until the next calamity.
3. You say that his superpower creates a power for him to use. What if it doesn’t tell him what it is? He has to use all his ingenuity and imagination to work out what power his survival instinct will have given him in this scenario, and only then can he actually use it.
4. This superpower polymorphism is super exhausting. While he’s being super, sure, he can fly, breathe underwater, glow in the dark, and be immune to all poisons. But once he’s averted the crisis, he effectively goes into hibernation. Some sense monitors the outside world, ready to kick in if he’s endangered, but he spends most of his time trying to consume enough calories and feeling perpetually sleep-deprived. He struggles to hold down a job, finds it hard to maintain relationships, and has no spare time or energy to pursue other activities or interests. Maybe for this hero, it’s about learning how *not* to use his superpower, because he strives so desperately just to lead an ordinary life.
[Answer]
## Limitations
There's a finished web series about superheroes, Worm, where one of the strongest heroes had a very similar power. (Mild spoilers ahead about one character powers)
He had three limitations: only three different powers at a time (so he needed to let go of one power to gain a new one, and no foreknowledge of which new power he'd get), powers having a build-up time (starting weak and being god-tier after some minutes) and the overall strength of the powers diminishing as he aged. With this limitations and some character flaws his character arc felt compelling even though his power should have been an "I win" card.
So you can get some inspiration from this and add some limitations to his powers and an exploitable character flaw, and you have yourself a strong but still relatable character.
As for specific examples I found the "let go of a power so you are given something more appropiate" excellent, especially in rapidly-changing circumstances (you are on a house fire, do you let go of super strength so you can get ice breath or something similar but lose the ability to lift big piles of debris?). You could make it so his power isn't generating the powers in a vacuum, but takes them from someone else, and have him realize he just stole super-sidekick telekinesis as he was fighting doctor-evilguy. Or maybe he has to use the powers he gets, no matter what, so if he just got laser eyes and mecha-godzilla died of a vanishing stroke he need to raze half of the city with lasers. Just find something that fits in your world, and creates good opportunities for stories.
] |
[Question]
[
So I have this tyrannical wizard with absurd powers who is the emperor of a large and powerful empire.
Part of his success is not simply down to his ability to murder people but also his brilliant administrative qualities and how he provides for the people. But he also likes to connect those helpful aspects to himself so that people are doing well but dependent on him.
This is merely for context.
**Now the magical aspect can be safely ignored once the animal is already made as magic can just replace advanced biological engineering and time.**
Much like how with time we could breed dog breeds, and other animals, of certain qualities the magic can just speed up and replace the process.
This also applies to the "genes" as if he made an animal 25% percent bigger then the offspring would be 25% bigger, and it becomes a new animal with the qualities he made and follows biology.
**This is important as I don't want opinions, I want actual biological facts. I don't want people to say but magic can mean anything so whatever, as it does not here.
The goal is to use a lot of magic upfront and then have the new animal just do its thing.**
The closest example is if you can provide a caveman with a trained horse. This breaks nothing and we did train horses eventually.
Now his goal is simple: he wants to get rid of all farm animals and just make this one, or as few as possible, important animal that can do all the rules.
He does have a system of control of the existence of that animal but this is not a part of the question and again just for context.
Here is what I consider to the relevant points.
* Chicken and birds and fish are not a part of the equation.
* The magic works just like selective breeding **and** advanced engineering.
* The engineering parts is like if you can go into a lab and increase strength of a horse or make cows breed faster or whatever else is possible within the world of science.
* This is magic but magic can replace science in certain aspect but he is **not** looking for creating a magical animal. So no flying demons or anything similar as it would require massive wings and that is stupid...etc.
* The wizard is incredibly inventive, so don't hold back your imagination.
* The animal should have zero hostility towards humans and should be cooperative.
* The tech is roughly 100 AD. And much like earth at that time.
* His goal is to either replace all farm animals with it or most of them.
* No need for unwanted genes or aspects that do not serve the needs of farming.
* The needs for farming is just human farming in 100 AD. There is no magical dangers or anything new or changed there.
* The animal or animals must provide all the current benefits but should also provide extra benefits and be better than what is available to humans.
* Assume his empire is open to trade and so they have access to all sorts of animals to pick and choose traits from.
* He is not worried about the amount of magic he has to spend to create the new animal
* He is not worried about how much food the new animal will consume.
* He only wants it for agriculture not for fighting or anything else.
I think this covers it. More can be provided.
Here is an example of how I imagine this to work.
Say I want the perfect dog. So I like the color blue and as a strong wizard I will make a breed of blue colored dogs that can actually chameleon themselves to match the environment like the chameleon.
I will also make the dog as big as dire wolves and provide it with claws that can shred steel and fangs that are incredibly strong.
It would be short haired but resilient to all weathers and incredibly loyal with a 50 year lifespan.
It is smart enough to understand complex commands and can be ridden if need be.
It can also cooperate with other animals if I trained it to do so...etc
Now once I magically make a dog with all these qualities then the current dog and the new dogs will be a new breed with all the qualities above and require zero magical maintenance later.
It will then adhere to the laws of biology as normal animals.
Yes evolution later can alter that but this is not part of it.
I am looking for something like this but in the agriculture world.
Now frame challenges are allowed and of course fine. That's why I left it open to the possibility of having more than one animal.
So if one animal is not enough he can create more.
I'm sorry for stressing certain points more than once. But I just wanted to make it clear as magic can be misinterpreted to: Does not matter.
So what is a "scientific" solution to our friend's problem?
[Answer]
### Super Cow
* Can eat almost anything (replacing pigs as garbage disposal)
* Puts out huge amount of milk under constant nipple compression (replacing dairy cows, and removing the need for complicated dairy pumps. A peg clamped on will put out gallons.). Leaving the nipples clamped will disable milk production, allowing energy to be saved.
* Can pull a huge weight (replacing oxen)
+ Strong neck and shoulder bones allow for convenient yoke mounting.
* Can travel at 30km/hr when unladen (replacing horses).
+ Soft padded mid back removes the need for a saddle.
* Bi-chromal eyesight, so can make out the colour red. And will walk towards any flapping red fabric, even if in a circle for hours, until at the point of exhaustion, so can be trivially utilised to power a mil, crane, or (centuries later) generate electricity.
* Solid waste is highly compacted by its powerful colon into a dry, odourless, solid, easily stackable fuel briquettes (male) or fertiliser blocks (female).
* Females creates a large egg every day even if unfertilised. This egg is very tasty strong enough to fall to the ground without breaking, and doesn't need to be sat on to reproduce.
* A Crest of feathers from eyebrow to neck on both genders, these are used for mating rituals in nature - the taller and more feathers the better the genes, but humans will find them conveniently sized for arrows.
* Conveniently placed D-Shaped ivory growths that make for functional tie points for equipment, railings to aid people climbing up, and to make great piano keys.
* A beard grows at a decent rate (50cm/day), the beard on females is essentially silk, on males, a super strong fibre with properties like kevlar.
* A large bushy tail grows very quickly, and trivially removable with a knife. The tail from males is basically wool (with a lanolin grease similar to sheep), and females is basically cotton, and can be spun into fibres easily.
* Absorbs trace metals from the environment in youth, which (along with its high temperature stomach) is used to convert [methane waste into methanol and alcohol](https://onlinelibrary.wiley.com/doi/abs/10.1002/anie.201704704). When hydraded, the urine is only about 5% alcohols, but when dehydrated, it's urine can be up to 90% alcohols. The urine from a dehydrated super-cow is usable as a fuel already, but with fractional distillation can provide pure methanol and ethanol. Fuel and alcohol. (Helps out thousands of years by keeping greenhouse gases down too!)
* If starved, first will eat its own beard and tail, but then, if it has access to a tree or large bush. Will eat all the leaves, the minor branches, and then up uproot the tree and eat the roots. You can tie them up in a scrub and come back a few days later to cleared land and felled trees ready to cut into firewood
* Earwax is produced at a rapid rate in 4 distinct phases (separated by a few months in case someone wishes to clean them). And has several useful properties.
+ The earwax from a Male calf is a substitute for honey
+ Female Calfs produce a substance that's a handy adhesive
+ Male teenagers produce a substance with great waterproofing properties
+ Female teens produce a substance which has contraceptive properties , allowing reproductive choice.
- Keeping this, and mixing traces of it into the female adults food, will stop egg production, saving energy for other uses.
+ Male adults produce a substance which when mixed with water and activated with sunlight make a powerful antibiotic.
+ Female adults produce a substance which in small doses helps with anxiety and stabilises moods, in large doses gets you really high safely.
+ Male seniors produce a jellied random powder, it's different depending on family lines and diet, but Can be trivially processed (by boiling and drying) into several spices.
+ Female seniors produce a substance which is a powerful painkiller.
* In old age, uses its last act to enter a rapid growth period growing nice muscle and dissolving bones and non essential organs to do so, doubling in size until the body fails under the weight.
+ Giving lots of easily butchered meat. The release of enzymes at death add extra marbelling, and the majority of the meat is freshly grown just before death. The different cuts have wildly different flavours, emulating pork, bacon, veal, beaf, etc.
+ The skin also grows rapidly in this final phase resulting in a hide nearly 50 sqm. A novice farmer can strip the hide in one peice and make a bolt of leather with ease.
There is ZERO chance of this creature evolving naturally, however once magicked into existence, I don't see this violating any fundamental rules of science.
[Answer]
Consider this. Modern agriculture rely greatly on machines. We have full control and full power to make any machines we want. And where it goes? One superagriculture machine "to rule them all"? Or hundreds and thousands specialized or even overspecialized contraptions?
So you wizard will not create one single breed, but lots of very special animals - super cows for milk and meat, super pigs for meat and garbage dispose, super horses for work power and etc. And there would be even greater specialization! Like "wheat cows" (eat pure straw and produces special manure for wheat), "ground vegetable cows" (eats tops and again - very special manure) and etc. And this will go for chickens as well (again - manure and excesses dispose)
All this agriculture would be both super-effective and highly wizard-dependent. People will not be able to support such a variety by themselves for long time. Single flood or fire can destroy entire breed which is an important link in production chain. But while the wizard replaces losses this country would prosper
UPD: as an opposition to other answers I want to mention, that people's quality of life also include *variety* of food. Eating only single one type of meat is not that pleasent even if it is the best meat in the world.
[Answer]
The German expression *eierlegende Wollmilchsau* is idiomatically used for any person or object that English would describe as "all-singing all-dancing". If you google it, you'll get plenty of images of the "egg-laying wooly milk pig" that answers your question—my favourite is below. The name alone describes an animal that covers pretty much all the agricultural bases. Ideally it should be engineered to eat unfussily and cheaply (like a goat), occasionally hunt and eat rodents (like a farm cat) and have the homing instincts of a pigeon.
Of course the males (i.e. the ramboarbullcocks) won't give you milk or eggs, but they could be bred larger, hairier and more muscular than the ewesowcowhens, for increased wool yields, meatier meat, and sufficient strength to pull a plough or cart.
[](https://i.stack.imgur.com/B92Fh.png)
And if they can be taught to sing and dance, well that's just a bonus.
[Answer]
**The Ameglian Major Cow**
[](https://i.stack.imgur.com/TDCrw.png)
>
> A large animal was brought to Zaphod Beeblebrox's table, a large, fat,
> meaty quadruped of the bovine type with large watery eyes, small horns
> and what might almost have been an ingratiating smile on his lips. He
> was an Ameglian Major Cow.
>
>
> "Good evening", he said, "I am the main dish of the day. May I interest you in the parts of my body? Something off the shoulder perhaps? Braised in a little white wine sauce?"
>
>
> "Er, your shoulder?" said Arthur in a horrified whisper.
>
>
> "But naturally my shoulder, sir, nobody else's is mine to offer." . . . "May I urge you to consider my liver?" asked the animal, "it must be very rich and
> tender by now, I've been force-feeding myself for months." . . . After
> some protesting by Arthur . . . "Well," said the animal . . . "it was
> eventually decided to cut through the whole tangled problem and breed
> an animal that actually wanted to be eaten and was capable of saying
> so, clearly and distinctly. And here I am." "Glass of water?", asked
> Arthur.
>
>
> "Look," said Zaphod, "we want to eat, and we don't want to
> make a meal of the issues. We'll have four rare steaks, and hurry
> please.'
>
>
> The animal gave a mellow gurgle. "A very wise choice, sir,
> very good," he said, "I'll just nip off and shoot myself."
>
>
> Arthur (head in hand): "Oh, God!"
>
>
> Animal: "Don't worry sir, I'll be very humane."
>
>
>
Basically the wizard breeds an intelligent animal that wants to be eaten so will look after itself and do what it needs to do to improve it's eating experience.
[Answer]
I agree that having single super-livestock won't work. As many necessary features of such animals are in direct conflict. For example, if you make cow that is good at producing meat and milk, it needs to divide it's energy and food suplies towards both. If instead you have cow specialized for meat and cow specialized for milk, they will use food they eat towards only single purpuse, being both efficient and most probably easier to engineer.
I'm going to assume that wizard's livestock 'industry' is somewhat like ours. In that it can go as far as factory farming. Based on that, I'm going to answer different question 'What kind of livestock could we engineer to make livestock better for us, given our current state of husbandry.'
There are few major points that wizard would need to address. First is the moral one, which vegans often point out. Many animals are kept in conditions that are extremely stressful for them. Cows and pigs stand side-by-side, unable to move for most of their lives. Chicken, who have strict hierarchies, cannot establish them and get stressed. So first big modification should be some kind of nerve-stapling, making them as docile and as little needy as possible. Make them, so they are perfectly comfortable not moving for extended period of time and not caring about world around it, other than feeding.
Another point of waste is reproduction. Often, only one sex is worthy for raising. But naturally, animals have 50/50 chance of having either sex children. This is waseful. For example, only female chicks are useful. Male chicks are killed shortly after being born. So engineer them so that the ratio is heavily lopsided for the useful sex. For chicken, that could easily be 95/5 so that only few male chicks are born.
Another big problem is disease. Putting dozens or hundreds of animals into small space is perfect place for spread of disease. So we use majority of our antibiotics on livestock. Your wizzard should definitely invest a lot of resource to engineer best immune system into his livestock.
Pollution is another bad problem with our livestock. It produces lots of polution, in air, water and soil. Maybe the wizzard can do something about it? Make the cows metabolism produce less harmful chemicals, or if it needs to produce it, it excretes it in a way that can easily be cleaned up and either safely disposed or re-purposed.
Lastly, one of the bad things with livestock is that it is really inneficient in using it's resources. Studies show that only 1-3% of calories eaten by cow gets converted into meat. It is little better for poultry. This is definitely area the wizard should focus on.
[Answer]
Assuming that the major needs served by farm animals are:
* meat
* dairy
* fibre
* power (locomotion, powering static machinery via treadmills etc)
* fertiliser
We already have animals that can provide at least 4 of these by themselves: sheep, and also some breeds of goat. Increasing their size and changing their proportions (e.g. to the size/shape of small cattle) in order to allow them to bear human weight and pull at least 1 horsepower of load would round out the power component. Temperament might also need to be adjusted as sheep are herd animals that don't do well alone.
Given that there are many breeds of sheep which are specialised to various human needs, it should be very possible for specific breeds of riding and draft sheep to be developed. If time weren't a factor then careful breeding could potentially accomplish the size increase without even needing magic; humans have accomplished some pretty major shape changes via selective breeding of domesticated animals over the last few thousand years.
[Answer]
**A creature with caste**
The problem is that you can't just have one kind of animal do everything. This is inefficient, impractical and just generally silly. That is why I would suggest a caste system.
If we look at group creatures like bees and ants, we can see they have large amount of differentiation within them. There are several methods to achieve this. Ants for example smell each other's function. If an ant smells too little of a certain function, they will differentiate into that version if possible. Via hormones in the air from both the creatures and the environment you can have the creature differentiate into an appropriate form during their growing stage. This can be taller to eat the leaves of trees in a forest, lower to eat the grass on a field and be less susceptible to wind, or on other levels differentiating into making milk or growing fat for meat.
Keep in mind that you don't need a central queen for this. You can conceivably get this in a herd.
Possibly the meat creature creates bulges on it's sides that have no purpose, but fall off when finished. This can be done with apoptosis (programmed cell death) as well as vestigial growth. This is edible meat with a leather shell. This will make the creatures survive for longer until it is time to slaughter the whole animal. This can be very advantageous for reproduction. This meat variant can immediately be used for plowing, as it's strong but slow.
A milk variant is more intermediate, allowing for some travelling between cities and pulling of carriages. Generally not used for long distance in a day.
You can have other variants, like one that spins webs for clothing as @Demigan suggests, or extra hairy ones for fur production. Growing animals put into a house will diversify into a smaller version, capable of eating much like a goat, is good for companionship and generally smarter than the rest.
An even more select few will become travel animals. They produce a bit of meat and milk if there's plenty food and they aren't pushed too hard. The highest form of this is producing nothing and is just for long distance heavy riding.
In each herd one or two animals are smarter than the rest, which the others follow. The smarter ones can be trained easily, removing the need for herding animals and such.
From this you can mix and match to your desire. A caste system helps survivability of the creatures, vestigial growths and the like aid this further, while the creature adapts in most cases as efficiently as possible to the circumstance for optimal eating of the food. A forest where you only eat grass or fallen leaves is just not efficient. This will give your civilians an abundance of resources, from food to labor to companionship, making them certainly more happy and less prone to famine and the like.
[Answer]
You want a giant platypus. Nothing else (except maybe an echidna) will give you milk, wool *and* eggs. You’ll want to breed out the venomous spurs, as well as making them much larger and woolier.
[Answer]
A [shmoo](https://en.wikipedia.org/wiki/Shmoo).
The shmoo is an animal invented by Al Capp for his satirical comic strip, Li'l Abner, that has just about everything you want.
Shmoos [from wikipedia]
* ... reproduce asexually and are incredibly prolific, multiplying faster than rabbits. They require no sustenance other than air.
* Shmoos are delicious to eat, and are eager to be eaten. If a human looks at one hungrily, it will happily immolate itself — either by jumping into a frying pan, after which they taste like chicken, or into a broiling pan, after which they taste like steak. When roasted they taste like pork, and when baked they taste like catfish. Raw, they taste like oysters on the half-shell.
* They also produce eggs (neatly packaged), milk (bottled, grade-A), and butter—no churning required. Their pelts make perfect bootleather or house timbers, depending on how thick one slices them.
* They have no bones, so there's absolutely no waste. Their eyes make the best suspender buttons, and their whiskers make perfect toothpicks. In short, they are simply the perfect ideal of a subsistence agricultural herd animal.
* Naturally gentle, they require minimal care and are ideal playmates for young children. The frolicking of shmoos is so entertaining (such as their staged "shmoosical comedies") that people no longer feel the need to watch television or go to the movies.
* Some of the more tasty varieties of shmoo are more difficult to catch, however. Usually shmoo hunters, now a sport in some parts of the country, use a paper bag, flashlight, and stick to capture their shmoos. At night the light stuns them, then they may be whacked in the head with the stick and put in the bag for frying up later on.
[Answer]
**Trees**
Animals are very, very inefficient. To produce anything, they need to eat plants. The digestion is using a lot of energy to transform it to something usable. If I remember correctly, about 40% is wasted. Then it goes to storage, movement and thinking besides the growth of product, all which waste a lot of energy. What you need is to cut out the middle man.
When thinking about what plant to use, I would say trees. It might take a moment before they have grown, but the benefits are quite big. Compared to regular plants, after they've grown a certain size they don't need to regrow this. A wheat plant needs to grow the whole plant before it grows the fruit every time in comparison. The roots of a tree go deeper, allowing for more sustenance and less susceptible to drought. The canopy is also less easy to eat for larger animals. Depending on how much light the canopy lets through, the ground can grow grass and bushes, allowing for other kinds of harvesting or animal grazing.
The fruit that grows there can be altered by adding a few versions of the tree, allowing for variety. In the outer layer it can produce edible liquid, which can harden for either crafting purposes (like a form of amber) or edible purposes. This can be harvested like tree resin. Sap and oils can be nutritious, while also able ward off many bacteria and rot, allowing for a good travel food if kept in liquid or hardened state. You might even use it for pottery if you heat it enough. The wood itself can be used as lumber, which again can contain the oils to allow for easy, durable building. With several kinds of trees you can immediately add more flexible wood or the slow growing but incredible strong wood. New twigs and roots can be edible as well, each with their own taste. Much like strawberries and potato plants they can grow new trees via the roots and the potato limps, the tree can grow these on the edges of it's roots. Even the bark can be edible or used for crafting.
To futher the edibility and diversity, you could graft plants on the roots. The canopy can use all light for growing, giving the energy to the grafted plants. These can futher give off things like wheat, but in a way that only the "fruit" has to be harvested. The rest of the plant can stay, so it won't need to grow again. This way, you can have a lot of diversity in food and construction with just a few kinds of one tree, aided by specially grafted plants.
It might take some time for the tree to grow to a fully producing tree and the grafting can take effort, but afterwards you hopefully only have to harvest. The harvesting might still be very intensive though. That being said, the tree can bear food most of the seasons, much like some raspberry bushes will keep producing until it gets too cold. It might even allow things like potatoes to be dug from the roots in winter.
Lots of animals actually reside in woods, so they can be let loose there for extra sustenance. Possibly one of the creatures suggested above. But this tree might actually be possible, based on the traits of other trees and plants.
[Answer]
I want to take pieces of some of the other answers and kind of merge them together.
What if as others say your wizard develops multiple super animals as suggested. Because the animals are "super" in that they produce crazy amounts of food/milk/honey/etc., they all REQUIRE a special nutrient (hormone/protein/mineral) only found in a very super plant that you have magically created. Because of this, your evil wizard kills all the other animals and controls 5 farms as the sole distributor of this superfood. Anyone who has a super animal (because your wizard no longer needs control of the animals, but their food source) must come to one of your special farms once every month to allow it to eat or risk their animal not producing food or even dying. Of course, access to these farms is expensive and requires some payment beyond money for the subjects. This forces the subjects to live close to the wizard so he can keep a close eye on them. It also keeps them productive because they are forced to raise their own food.
[Answer]
German has a word for that: Eierlegende Wollmilchsau (literally egg-laying wool-milk-sow).
I think you'd do well to adapt pigs or boars to your needs.
You probably won't get the egg laying to work with just rapid breeding, but
* Boars have hair so you can just make that grow longer and softer to get wool.
* Pigs/boars give milk to their piglets, so you just need to breed for more/tastier milk.
* You can probably breed your pigs big and sturdy enough that you can use them to carry and pull things - they might not be the fastest, but your average villager doesn't need fast. If you don't have teleportation magic, you'll probably want to keep horses around for your personal use.
* And of course they already have tasty meat.
[Answer]
What about instead of some super singular animal that can do big work itself and be turned into a big cut of meat, instead what about a about smaller collective-based creature, like a hoard of smart, collaborative, hive minded mice. They can swarm to dig (plow) fields, plant seeds, and then reap the crops. A thousand of them can team up to carry a big beam of wood, another 10 or so pick up a hammer, and one holds the nail in place. They can climb up walls, crawl through tight spaces, good sense of smell, hearing, and sight. They'd be great spys, depending on how the communal intelligence worked, or hell they could even spell out messages with their bodies to let you know what they overheard. Also they breed like... well, like rats! Also they're good eating if you put enough of them in the pot, you can even have some of them butcher and cook the other ones for you.
So, yeah. A hive of millions of trained mice could take over the world I think.
[Answer]
**Yeasts**
we have many yeasts that produce a lot of products now, with magic you could go without costly research straight to prosperity
most of animal products are protein based
* you can have meat producing yeasts(they exist) that form fiber structure similar to meat (does not exist AFAIK) to have tasty texture
* producing eggs is just producing proteins, you can even separate yolk and white
* silk and spider silk is also just a long protein, ATM we cant produce it in bulk via yeasts but with the right DNA maybe?
* alcohol :)
* medicine and drugs
so farming would be crops for agar that is then processed by yeasts into whatever
to adhere to the one-animal request: you could have one ultimate yeast that is jump-started to produce proteins by adding a sample that should be produced (those genes would express themselves) this has some potential plot hooks with unwanted substances falling into the yeast vats
and for you control over them - adding some backdoor protein would trigger selfdestruction creating more of the backdoor protein if he wants to decimate the economy created
if you want something more interactive, the yeasts could clump up into a slime (like dnd gelatinous cube etc.)
] |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.