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[Question]
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I'm trying to figure out how to make this gas giant moon habitable.
Here are the factors involved:
Moon is sub-temperate, mountainous with a nitrogen-oxygen atmosphere, with the planet being mainly made up of coastal forests, vast highlands, and massive mountain ranges. Hydrosphere is both active and stormy, with there being snowy winters and short warmer summers.
Moon is NOT tidally locked.
The gas giant needs to be ringed.
The system is a trinary star system with two red dwarfs and a G-class star (exactly like ours). The two red dwarfs orbit the yellow star.
The Gas giant and moon should be in the Goldilocks Zone, but the gas giant has extensive moon system similar to our gas giants.
The Gas giant does not have any moons similar to Jupiter's Io.
The Gas giant has a 23 degree tilt.
What conditions are needed to make this moon possible?
[Answer]
In this answer, I’ll attempt to address two primary concerns impacting the habitability of your moon:
* atmosphere retention
* absorption of solar radiation
You will undoubtedly have to tweak the parameters of your planet in order to get the desired weather patterns. However, these two factors seem most important with respect to habitability.
Before getting into the weeds, here’s a list of definitions for variables I’ll use:
* $R\_m$, the moon’s radius
* $M\_m$, the moon’s mass
* $L\_{s}$, the combined average luminosity of the three-sun system
* $D$, the distance of the planet-moon system from the three-sun system
* $G\approx 6.7\cdot 10^{-11} \space\text{Nm}^2/\text{kg}^2$, the gravitational constant
* $k\approx 1.4\cdot 10^{-23}\space \text{J}/\text{K}$, the Boltzmann constant
Alright, let’s go! (Note: I’m bound to have made some computational error somewhere below. Hopefully it doesn’t affect my estimates too much, and they’re still within the right order of magnitude. Bonus points if you find a mistake!)
---
**Atmosphere retention**
No matter how massive or cold your planet is, it will always continuously lose *some* of its atmosphere (as long as this atmosphere is gaseous). This is because not all of the atmospheric gas molecules have the same speed - their speeds are random, following the [Maxwell-Boltzmann Distribution](https://en.wikipedia.org/wiki/Maxwell%E2%80%93Boltzmann_distribution). At all times, *some* of the molecules will be moving fast enough to escape. The question is - how long do you want your atmosphere to last?
The escape velocity for your moon is approximately equal to
$$v\_{\text{esc}} = \sqrt{\frac{2GM\_m}{R\_m}}$$
and the root-mean-square velocity of gas molecules in a gas of temperature $T$ is equal to
$$v\_{\text{rms}} = \sqrt{\frac{3kT}{2m}}$$
where $m$ is the mass of the gas molecule in question. You certainly don’t want $v\_{\text{rms}}>v\_{\text{esc}}$, or your whole atmosphere will be gone in an instant. So, at the very least, you need
$$\sqrt{\frac{3kT}{2m}} \lt \sqrt{\frac{2GM\_m}{R\_m}}$$
or, for a molecule of diatomic oxygen,
$$\frac{M\_m}{R\_m T} \approx 2.92\cdot 10^{12}\frac{\text{kg}}{\text{m}\cdot\text{K}}$$
For a moon the size of [Deimos](https://en.wikipedia.org/wiki/Deimos_(moon)) (which is almost certainly much smaller than yours) and with an average surface temperature equal to Earth’s, the LHS of this inequality is approximately $8.3\cdot 10^{8}$. That’s well below this rudimentary upper limit - so far, so good.
Let’s get a little more nitpicky. Remember what I said before about how *some* of your planet’s atmosphere will *always* be escaping?
Assuming the atmosphere’s depth is negligibly small compared to the planet’s radius, we have that the surface area of atmosphere exposed to space is approximately $4\pi R\_m^2$. According to the Maxwell-Boltzmann distribution, if $T$ is the average temperature, then the proportion that have achieved escape velocity at any given time is equal to
$$\begin{align}\alpha\_{\text{esc}} &= 2\sqrt{2\pi}\int\_{\sqrt{GM\_m m/kTR\_m}}^\infty v^2 e^{-v^2}dv\\ &= \frac{2\xi e^{-\xi^2}+\sqrt{\pi}\text{erfc}(\xi)}{4}\\
&\sim \frac{\xi e^{-\xi^2}}{2}
\end{align}$$
for reasonably small values of $\xi$, where $$\xi=\sqrt{\frac{GM\_m m}{kT}}$$
As an estimate, let’s use the Moon’s mass and radius and Earth’s surface temperature (and consider diatomic oxygen molecules). This yields approximate values of
$$\xi\approx 18.5$$
$$\alpha\approx 2.13\cdot 10^{-148}$$
Yowza, that’s a tiny value of $\alpha$! The volume of atmosphere that would escape over the course of $t$ seconds would be approximately equal to
$$4\pi\alpha R\_m^2 v\_{\text{esc}} t$$
But I’m not going to proceed further with the calculations. The value of $\alpha$ is so microscopically tiny that it will basically overwhelm the other factors in the above expression. Looks like your planet’s atmosphere is probably safe!
If you *really* want to make sure your atmosphere is secure, I’d recommend the following additional precautions:
* Make your planet nice and dense. This keeps $R\_m$ low while driving up the value of $M\_m$, which will make $\alpha$ even tinier.
* Give your moon and the planet it orbits a hefty magnetic field to deflect atmosphere-destroying cosmic rays.
---
**Absorption of solar radiation**
Now for the easy part! This won’t be nearly involved as the above.
I claim that any given point on your moon’s surface spends about $1/4$ of the time in the daylight and $3/4$ of the time in the dark, under the following assumptions:
* no tidal locking, as stated in the question
* the moon’s orbit is independent of position of the planet it orbits around the sun
* the gas giant is massive compared to the moon
* the three stars in this ternary star system are relatively close to each other and very far away from the planet and its moon
Why? Well, about $1/2$ of the time, the moon is on the opposite side of the planet, so it receives no light. When it is on the lit side of the planet, only $1/2$ of the moon’s surface is lit at any given time. Thus, for any point on the moon’s surface (poles excepted), it is lit about $(1/2)(1/2)=1/4$ of the time.
This means that, in order to maintain an Earth-like climate and temperature, something must compensate for this increased duration of night-time. Here are some suggestions:
* Greater amount of solar radiation. There are *three stars* in the system, after all.
* Increased luminosity $L\_s$ of the stars.
* Smaller distance $D$ from the three stars. It wouldn’t have to be much smaller, though, since intensity at a distance $D$ is proportional to $1/D^2$.
* Lower [albedo](https://en.wikipedia.org/wiki/Albedo), to avoid reflecting away solar energy.
* Lots of greenhouse gases to help trap solar radiation energy.
---
Here are some other non-sequitur speculations about what your moon might be like:
* You mentioned that you didn’t want there to be any tidal locking, but if there’s any significant amount of liquid water on the planet’s surface, the gravitational pull of the gas giant will exert *significant* force upon it. At the very least, this could cause some very extreme tidal rising and falling (exacerbated by the planet’s low gravity), creating vast tidal zones on the planet’s surface.
* As mentioned above, the day-night cycle on the moon will be wacky, nothing like the regular half-day-half-night cycle of Earth. There will be a long stretch of darkness (when the moon is behind the planet), followed by a series of day-night cycles whose length depends upon the rotational velocity of the moon, and then a return to darkness. I wonder how this will affect the [circadian rhythms](https://en.wikipedia.org/wiki/Circadian_rhythm) of animals and [photoperiodism](https://en.wikipedia.org/wiki/Photoperiodism) of plants on the surface?
* Since the moon spends a significant amount of time on the dark side of the planet, freezing/thawing will be common. As temperatures will rise and fall rapidly as the moon moves into and out of the planet’s shadow, you can expect some crazy weather (think massive cyclones) as a result.
[Answer]
If you plan to write stories set on planets or moons which are more or less habitable for humans and other advanced multi celled lifeforms with biochemistry similar to that on Earth, what you need to do is find a copy of Stephen H. Dole, *Habitable Planets for Man* (1964, 2007).
[https://www.rand.org/content/dam/rand/pubs/commercial\_books/2007/RAND\_CB179-1.pdf[1]](https://www.rand.org/content/dam/rand/pubs/commercial_books/2007/RAND_CB179-1.pdf%5B1%5D)
It is a well known fact that some Earth lifeforms thrive in environments where humans would instantly die if teleported into, such as miles high in the air, miles deep in the ocean, or miles underground in rock. And humans would also die swiftly if teleported to the majority of the surface of the planet Earth, such as the surface of the ocean, the surface of deserts, the surface of ice sheets, etc., despite some Earth lifeforms flourishing in those places.
So most scientific discussions about the habitability of other worlds discuss their habitability for life forms similar to any type of life on Earth in general, not for large land swelling oxygen breathing animals like humans in particular. Thus most scientific discussions list as habitable many possible worlds which would be instantly fatal to unprotected humans teleported there.
That is why *Habitable Planets for Man* is especially useful for science fiction writers.
Dole describes the range of star types suitable for having habitable planets in orbit around them. Since it takes billions of years for a planet to become habitable for humans, the star has to stay on the main sequence for billions of years. Fortunately type G and type M stars will stay on the main sequence long enough.
There is considerable scientific uncertainty whether class M red dwarf stars can have habitable planets, so you will probably want to have your gas giant and habitable moon orbit the type G star.
Here is a link to the Wikipedia article on multiple star systems.
[https://en.wikipedia.org/wiki/Star\_system#:~:text=Multiple%2Dstar%20systems%20are%20called,or%20septenary%20with%20seven%20stars.[2]](https://en.wikipedia.org/wiki/Star_system#:%7E:text=Multiple%2Dstar%20systems%20are%20called,or%20septenary%20with%20seven%20stars.%5B2%5D)
And note specially the hierarchical structure of multiple star systems which are old enough to have habitable planets.
[https://en.wikipedia.org/wiki/Star\_system#Hierarchical\_systems[3]](https://en.wikipedia.org/wiki/Star_system#Hierarchical_systems%5B3%5D)
So your triple star system is likely to consist of a pair of stars and a single star, and the distance between the pair of stars and the single star is likely to be several times the distances between the stars in the pair - possibly tens, hundreds, or even thousands of times as far.
Your giant planet and habitable moon could orbit in an S-type orbit around one of the stars, or in a circumbinary or P-type orbit around two of the stars. But because of the hierarchical structure of multiple star systems, it seems highly unlikely that a planet orbiting around all three stars could orbit close enough to any of the stars to have habitable temperatures.
[https://en.wikipedia.org/wiki/Habitability\_of\_binary\_star\_systems[4]](https://en.wikipedia.org/wiki/Habitability_of_binary_star_systems%5B4%5D)
Examples of exoplanets in S-Type orbits, and others in P-type orbits have been discovered.
If your giant planet and habitable moon orbit around one star in an S-type orbit it is more likely to be class G star than a class M star, although a moon tidally locked to its planet instead of to its star would avoid some of the problems with having a habitable planet of a class M red dwarf. You say that you don't want to have your moon tidally locked to its planet, which will be a problem.
If your giant planet and habitable moon orbit around two stars in a circumbinary or P-Type orbit, they are more likely to be the class G star and one class M red dwarf instead of two class M red dwarfs.
Because of the hierarchical structure of a triple star system, only the one star or two stars that the planet and habitable moon orbit should be close enough to have visible discs in the sky of the moon. The other two stars or one star should appear as two points or one point of light in the sky of the moon, although probably extremely bright.
Science fiction writers and scientists have considered the possibility of life on planet sized exomoons orbiting giant exoplanets.
[https://en.wikipedia.org/wiki/Habitability\_of\_natural\_satellites#:~:text=The%20habitability%20of%20natural%20satellites,have%20environments%20hospitable%20to%20life.&text=Tidal%20forces%20are%20likely%20to,potential%20habitability%20of%20natural%20satellites.[5]](https://en.wikipedia.org/wiki/Habitability_of_natural_satellites#:%7E:text=The%20habitability%20of%20natural%20satellites,have%20environments%20hospitable%20to%20life.&text=Tidal%20forces%20are%20likely%20to,potential%20habitability%20of%20natural%20satellites.%5B5%5D)
Heller, René; Rory Barnes (2012). "Exomoon habitability constrained by illumination and tidal heating" Astrobiology. 13 (1): 18–46 is an important scientific discussion of the habitability of exomoons worthy of study.
[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3549631/[6]](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3549631/%5B6%5D)
Another important article is:
Heller, René (September 2013). "Magnetic shielding of exomoons beyond the circumplanetary habitable edge". The Astrophysical Journal Letters. 776 (2): L33.
[https://arxiv.org/abs/1309.0811[7]](https://arxiv.org/abs/1309.0811%5B7%5D)
You might also want to check my answers to questions like:
[https://worldbuilding.stackexchange.com/questions/175614/temperatures-on-an-earth-with-a-week-long-rotational-period/175719#175719[8]](https://worldbuilding.stackexchange.com/questions/175614/temperatures-on-an-earth-with-a-week-long-rotational-period/175719#175719%5B8%5D)
[https://worldbuilding.stackexchange.com/questions/174597/is-there-a-plausible-way-to-have-a-gas-giant-with-two-or-more-earth-to-mars-size/174624#174624[9]](https://worldbuilding.stackexchange.com/questions/174597/is-there-a-plausible-way-to-have-a-gas-giant-with-two-or-more-earth-to-mars-size/174624#174624%5B9%5D)
[https://worldbuilding.stackexchange.com/questions/174401/what-types-of-flora-would-flourish-on-a-tidally-locked-moon/174453#174453[10]](https://worldbuilding.stackexchange.com/questions/174401/what-types-of-flora-would-flourish-on-a-tidally-locked-moon/174453#174453%5B10%5D)
Since I quote from some of the sources I mentioned above.
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[Question]
[
So, nuclear war is on the horizon. I’m order for humanity and Earth to survive on, organizations, both public and private begin to construct massive underground shelters, each with the ability to house up to 500-800 people, and produce food and water for them to survive indefinitely.
These people plan to repopulate to the world once the nuclear winter ends, but one thing they must bring with them...is animals and plants. Since the nuclear war will cause a mass extinction, as well mutating the few surviving creatures, the people of the underground will have to save them (mostly by cryo-storing dna samples). But they don’t want to waste resources.
My question is, for these people, what animals, and plants, will be most important to save?
**Important Info**
-Ocean life is mostly fine; algae and whatnot will still be producing oxygen. Insects as well.
-The humans main focus when the emerge will be farming, but they also want to be able to set up a stable ecosystem.
-This is all taking place in the North American continent.
-The limit is....10 different animals. No limit for plants.
[Answer]
# Disaster no matter what
There's a lot of complexity involved in re-introducing animal species that have died off in the wild. For our purposes, I'll focus on a major problem your survivors will face no matter what they decide: food chains will be destroyed
In order to support any given animal, you'll need a whole chain of things to support that creature. Below is one example from Wikipedia. Re-introduction of a species requires that the species has an intact food supply, which generally requires numerous other plant and animal species.
[](https://i.stack.imgur.com/dmueI.jpg)
I love cats. So let's say I wanted to include cats as part of the post-apocalypse plan. Cats generally eat meat. So I might have to include birds or small rodents in my plan as well. And what do birds and small rodents eat? Well my favorite bird is the Black-Capped Chickadee, so I guess I'd reintroduce them too as prey for the cats. What do chickadees eat? According to [NWF](https://www.nwf.org/Educational-Resources/Wildlife-Guide/Birds/Black-Capped-Chickadee#), "They eat a diet of seeds, berries, insects, invertebrates, and occasionally small portions of carrion." Hmm, I guess I'll pick earthworms as their food source since [they seem important](https://theconversation.com/earthworms-are-more-important-than-pandas-if-you-want-to-save-the-planet-74010). Worms need plant matter to survive, so I'll choose... hmm... spinach as my plant? So even in this oversimplified food chain, bringing back cats requires three other species, which only leaves six more species for your survivors to take. In the real world, things are far more complex and interconnected.
**Diversity**
It's unclear how many of each species your survivors can keep. It's also not clear if you can bring multiple breeds of the same species with you (e.g. would saving Cocker Spaniels and Saint Bernards count as one or two species?). You'll need a lot of members of each species. Scientifically speaking, you need the [minimum viable population](https://www.britannica.com/science/minimum-viable-population) of each species. [This question](https://worldbuilding.stackexchange.com/questions/3/what-is-the-minimum-human-population-necessary-for-a-sustainable-colony) has good answers with regard to humans. An older rule of thumb is the "50/500 rule" which says that you need 50 of a given species to prevent inbreeding and 500 to limit genetic drift (more info [here](http://assets.press.princeton.edu/chapters/s12_9242.pdf)). If you can only save one breed of a given species, you'd be limiting the diversity that can exist within a species. For example, think about how many kinds of [dogs](https://www.akc.org/dog-breeds/) or [cattle](http://afs.okstate.edu/breeds/cattle/) or [chickens](https://www.starmilling.com/poultry-chicken-breeds/) or even [turkeys](https://en.wikipedia.org/wiki/List_of_turkey_breeds) there are.
[Answer]
Plants in general would prove more essential for survival and require fewer resources to keep.
From plants you can get all nutrients you may need, drugs, clothing material, raw materials for industrial production like rubber and so on.
A variety of mushrooms should be stored (again spores are easily stored) and cultivated in the shelters.
Would be essential to bring in some delicate insect species too: bees, bumblebees, silkworms, etc.
With limited space and time to prepare the shelters they would probably pick smaller animals but capable of fast population growth. Like rabbits (meat, fur) and mice (meat, lab testing). If possible sheep too.
If there is the availability of resources also some donkeys or llamas, depending on location. In case of scarcity of fuels they may provide help for transportation.
Also dogs and cats both as pets and in case the population of those rabbits and mice may run out of control.
Ideally they should coordinate the shelters so that each one would have a few different species, depending on available space.
You are the designer of the story so it's up to you... but are you aware there are new studies that have greatly reduced the likelyhood of a lassting Nuclear Winter?
[Answer]
Since the background with the question doesn't state whether cryro-storage of animals/animal ova/sperm is vs isn't feasible, I'll answer assuming no cryro, thus a small population of each animal will be needed (and that'll take precious fallout-shelter space.) This is my best guess to both enable high-protein agriculture via draft animals -- as well as giving deliberately-set-loose animals (when the domestic population permits) start refilling/rebuilding the wild ecology. No list of ten will be perfect. But anyway, here goes:
1. Chickens
2. Rabbits
3. Ducks (alternately, geese, possibly Canada geese.)
4. Goats (very adaptable/survivable)
5. Something in the Antelope family, probably Elk
6. Honeybees (non-Africanized)
7. Pigs (swine)
8. Horses (draft/plow animals!)
9. Cattle (draft/plow, dairy and meat.)
10. Wolves (the ecology will eventually need a top predator.)
---
Since the question states unlimited plants (via seeds in sealed containers), I'm not going to try to list them all; plenty of seed and Ag. catalogs for that!
What think you?
[Answer]
**Chickens, tilapia, channel catfish, goats, llamas, and maybe turkeys**
If you survive the nuclear apocalypse, the first thing you're going to worry about is food. You need a food source that's fast-reproducing, easy to breed, can feed on what little you can find in a post-apocalyptic environment, and can be raised easily. Protein is going to be a big issue, since you can easily store plant seeds. Protein rich plants like soybean and quinoa, or other options like spirula might be hard to obtain in such an environment. You need something that's low maintainance and can be taken just about anywhere.
Answer: I present to you the humble chicken. Chickens...
* **Breed fast**, they reach maturity at about 16-24 weeks of age. Broiler chickens can be slaughtered for food at 7-9 weeks
* **Eat just about anything**, chickens are omnivores and will eat insects, nuts, seeds, berries, centipedes, etc. If insects survive to any noticeable degree you can find enough food to feed chickens. Chickens can survive pretty much anywhere outside of the polar circles.
* **Can be easily handled**. This is a big deal. Horses, cattle, and a lot of large mammal require a lot of husbandry and can be difficult to manage. Think trying to range cattle without having access to horses to herd them or the tools necessary to slaughter and butcher them efficiently. Chickens can be easily herded and killed if necessary. You can kill them by hand, or with a shovel or broomstick if you get a big, aggressive rooster.
* **Can produce food without dying** (eggs). This is also very important, as it means you can produce food for people without reducing the very limited head of livestock you have at any given time. Even insects aside from honeybees don't do this on a scale efficiently enough for human consumption.
* **Are easy to raise.** Human farms since time immemorial have raised free range to semi-free range chickens. In a post-apocalyptic scenario you might even have an advantage because there are no foxes or coyotes to eat your chicken.
* **Don't require a lot of space.** You could technically raise chickens within the confines of a nuclear vault, provided you had sufficient grain. You couldn't do that with sheep, horses, or cattle.
Turkeys are kind of similar, being big chickens if you oversimplify things. However, they aren't as space efficient and can potentially be a little more dangerous. But they have a lot of the same benefits (omnivorous, breed easily, etc.)
Other animals that fit this criteria include tilapia (you can literally raise them in sewage tanks, they're easy to breed, and good to eat) and channel catfish (also easy to raise), as well as goats (a bit hardier than the other major hoofstock). Goats can also produce food without having to kill the animal, and you can also get leather out of them.
Sheep are a bit of a trap, they're originally a mountain species that will survive in the harsh conditions of a wasteland and they produce a very useful substance in the form of wool, but those same adaptations that let them survive in harsh environments will lead them to strip the surface cover from your meager post-apocalyptic soils and send you into a dust bowl, something you probably can't survive on top of a nuclear apocalypse. If you absolutely need wool get a llama, they aren't as destructive *and* you can use them as a pack animal on top of that.
Horses would be very useful, but are a huge amount of work to feed and maintain. Cattle just don't even bother, the downsides outweigh the benefits.
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[Question]
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For a society that lives primarily in a deep desert environment, what would be the most practical and/or common type of footwear in terms of both style and material?
The world is medieval-ish, but it's fantasy so it's not bound to any specific time or place. I have been trying to get some examples of the types of shoes worn by Bedouins and other desert-dwelling cultures. The Fremen of Arrakis are also a source of inspiration. This is a semi-tribal culture and portions of it are on the move regularly, often on horseback, so it should be a boot or shoe, not a sandal unless a sandal would be no issue on horseback.
[Answer]
In deserts with snakes and scorpions, ankle covering boots are common (although often sandals or bare feet are in use as well.)
In deserts where there are sharp stones, and/or hot sand temperatures, sandals are the least, boots not unheard of.
When your riders (horse, camel, whatever) use metal stirrups, like the ones in use by most riding horses on our world, boots with heels and hard soles are the most wanted footwear. But other kinds of footwear have been used.
But in history, many peoples, spread all over the world, have ridden animals without stirrups or with a different kind of stirrup that does not have the same needs for boots, or even any kind of footwear.
People who walk bare feet all the time have tough skin on the soles of their feet. So if you are inclined against boots, you can have your peoples go bare foot.
On the other hand, you are the writer, if you want your people to wear beautiful boots, by all means have them wear those.
Typically, before rubber became the norm for soles, boots were made out of leather and some sort of yarn made of animal hair or plant fiber. In the making of boots often wood was used to make a last (the form of the foot to build the boot around) but you can invent something else if there is no wood in your world. Some boots will have been made out of wood as well as leather, but it is not needed.
With riding animals you will have leather (from old/butchered riding animals or from other animals used for food.) And adult animals have thick leather, it 'just' has to be tanned in such a way that the thick parts get strong and sturdy.
Dress shoes (at least in the 20'th century) were soled with leather, and walking on streets their soles could last a year or even longer, then you would take them to the cobbler and you would get them re-soled, which would last an other year or two, depending on the use.
Riding boots will not wear as much on most of the soles, though leather should do for them for a year at least, so you may need to 'invent' an easily replaced part where the stirrup damages the sole, or you can just have the readers assume that the whole of the sole will be replaced if needed. (Or leave it out, you will also not describe how often they replace their riding trousers, unless it is vital for the story.)
You can go into the design and making of the boot or leave that out, as fits the story.
But history on earth will have much information.
Go back at least to the pioneers in the USA and those natives who used horses, or the same time or before in Europe, North Africa and Asia, for samples that would fit in your time/tech frame.
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[Question]
[
I've seen a [question similar to the one I'm about to ask](https://worldbuilding.stackexchange.com/questions/169366/eusocial-colonies-as-individual-sentient-organisms), but it does not quite address what I want to know, so here goes.
I want to create an organism in which sentient individuals are actually swarms of eusocial creatures. I already know several things about this organism, but there are three important and interconnected details that I'm trying to nail down.
**Things I know**
* Importantly, the reason the previous question does not answer what I
want to know is that an individual swarm is NOT physically
contiguous: the units of the swarm do stay *near* each other, but
they cannot communicate chemically because they are all flying about
in an amorphous swarm in the air (the total biomass of the swarm is about human,
but I'm split on whether I want swarms of ~100 units that add
up to that size or if I want a swarm of ~a million units where those units are
roughly bee sized, though I'm leaning towards the latter).
* The legal individual is defined as a swarm, and for good reason: a swarm can think on par with a human being (with similar variability in intelligence), while a unit of a swarm cannot do so any more than one of our cells or organs.
* In my ideal setup, there's no single "brain" organism for a swarm. I'm willing to bend on this if I need to, but I would like the intelligence of the swarm to be highly delocalized and an emergent property of the dumb units communicating which makes a sentient individual capable of abstraction, problem solving behavior, and critical thought emerge.
* Swarms can collaborate with each other on the same scale as humans can do so with each other; i.e. there isn't an automatic fight if two swarms are in the same place (like I think I remember happens for some other eusocial organisms if they're encroaching on territory). Swarms can form friendships and collaborations as well as enmity and scorn in the same way humans do, and are intelligent enough to have formed spacefaring.
* *Unit* reproduction occurs when drones and queens from a single swarm mate. This is equivalent to human development and healing: if a swarm is selfing, it's either growing up or restoring itself after sustaining injury. There are special units in a swarm which either incubate more eggs or actually carry "pregnancies" to term, depending on what I decide. Either way, restoration is pretty fast, maybe on the order of hours or days. Units are small enough that I expect most or all of them are going to be replaced regularly. Losing a single unit should be about as significant as something between human cells undergoing apoptosis and a human being getting a paper cut.
* Units of a swarm are almost certainly genetically distinct, and are unconsciously assigned castes upon creation in the same way our cells differentiate as different types of cells are needed. However, in the event of scarcity of an individual caste inside of a swarm, units can signal each other to take on different roles. In other words, every unit has the genetic material to assume any role, but one is picked epigenetically and can change.
* *Swarm* reproduction requires two different swarms to swap genetic material between their queens and drones and together produce a "superegg", which may or may not actually be a single physically contiguous object. This superegg "hatches" after some time (it can be a while, probably on par with a human pregnancy) to produce a small swarm of roughly 20000-40000 units, which is a newborn. This newborn develops intelligence precisely on par with human time scale, and is considered an adult after roughly six hundred million seconds (or about two decades: in this world, units are all expressed in SI units for complicated worldbuilding reasons I won't go into. The swarms probably have their own customary units, but I haven't bothered figuring that out). Swarms have a concept of marriage and co-parent.
* Swarms age and eventually die in a way analogous to humans: their self renewal ability gradually dims over time until they become vulnerable to disease.
* *Inter*swarm communication happens through language: native swarm languages revolve around using many bodies to form complex sounds and/or signs. Since they became spacefaring, swarms have adopted the standard interspecies languages (there's a specific spoken and a specific sign language adopted as intergalactic standard) by simply using their bodies to approximate hands or make unified sounds, since the other sentient species don't have millions of bodies to produce the phonemes that swarm languages consider standard.
* The strongest *limit* on what swarms can do is that they are not only biological, they are biological in the same way as we are. This universe operates on panspermia, so while different sentient species evolved on different planets with different evolutionary pressures, swarms still use DNA and RNA and protein, and all life in the universe has a single common ancestor. Furthermore, the evolutionary ancestor of all sentient life, including the swarms, was a *eukaryote*, so the cells of units have histones, nuclei, and mitochondria evolved in the same way eukaryotes on earth. This universe DOES have magic, but it cannot be essential to the way swarms work, since interacting with magic requires a sentient intellect, so the swarms would need to evolve biological sentience as a prerequisite and so cannot rely on magic in any way before evolving critical thinking.
**What I'm trying to figure out**
1. How do the units of an individual swarm communicate with themselves? This needs to resolve how the swarm can maintain itself unconsciously, critically think using its units, and maintain memory even as individual units are replaced and replaced frequently.
2. How do swarm units BETWEEN individuals not confound signals between swarm units OF individuals? If Swarm Alice's units bumps into the space of Swarm Bob's units, how do Swarm Alice's units' communications with each other avoid interfering with Swarm Bob's units' communications with each other?
3. Ideally, this communication would NOT be electromagnetic in nature or at least would have some way of protecting itself from interference: I want swarms to be able to use NMR machines and/or powerful magnetic fields without scrambling themselves to death.
EDIT: I'm pretty certain that, whatever solution I go with, their units all use some kind of signal which is in some sense encrypted. Not in a way they would consciously recognize (it's something they would have to do science on to realize it exists), but Swarm Alice's units use a different encryption key than Swarm Bob's. It would be complex enough to be more unique than fingerprints and probably the major reason that supereggs are physically contiguous as units for an incipient swarm converge on a signal. Nobody would have conscious awareness of the key their units use to encrypt communication: it would have be tested, and is probably the equivalent of taking fingerprints in the culture. Knowing someone else's key is personal information, of course, but it's hard to do something super nefarious with it: you can use it to send general biological signals if you know how to take the key and turn it into biology (e.g. tell drones and queens to make more units), but it's very hard to effect a change in a swarm's *thinking* with that key, because the signals used in thinking are unique, and emerge from an individual's personal experience. [A single signal's purpose can be understood, a small signal cluster's purpose can be vaguely grasped, but the whole is beyond. Nonetheless, it works.](https://www.youtube.com/watch?v=R9OHn5ZF4Uo) Each unit can only understand signals with this key and filtration happens automatically. This solves problem 2 very neatly, suggests general ideas for getting around problem 1, and prevents problems from whatever type of signal used between units happening to be native in the environment or spread ambiently around by other swarms interfering with swarms in ways biological creatures would logically evolve to avoid.
[Answer]
## Sound is remarkable, diverse and may be what you're after
There is [some evidence](https://beesource.com/point-of-view/adrian-wenner/sound-communication-in-honeybees/) that bee swarms communicate information between individuals and the collective via sound as well as dancing. It is long known that drones that explore come back to the hive and dance to communicate the whereabouts of food or new colony locations ([which earned Karl von Frisch a Nobel Prize](https://en.wikipedia.org/wiki/Karl_von_Frisch)), however this is complex information that many suspect cannot be described by dance alone. By vibrating wings at very high frequencies, complexity can supplement messaging and may also be evidence that bees can communicate through sound to each other, constantly transferring information between individuals.
[Similar, in fact, to modern drone swarms](https://medium.com/c%D3%95lus-concept/swarm-communication-33cffc47db6d) (but a sound equivalent of radio peer-to-peer drone swarm networks). As sound is a dissipating device, information needs to be constantly relayed:
[](https://i.stack.imgur.com/zAr4w.png)
Evidence suggests that bees attuning sound frequencies and rapid changing of 250 to 500 cycles per second it is possible to transmit messages nodally throughout the swarm.
Furthermore, if complex distance and location information can be transmitted in this way, it may be possible for vibrations to be encoded to ensure every swarm has a unique signature. The huge range of not just frequencies now, but variations in message length, now supports identification and security information and allows different swarm interactions to be separate.
The mechanism of sound can allow your species to evolve in an atmospheric environment, and if you want them to be spacefaring, sound is easily transferrable to a technological medium independent of an atmosphere (like in our current communication, if you remember old-school modems using sound, but transmitted over telephone wires). Spacefaring species are likely to have a concept of technology at an advanced level, and their preexisting sound 'language' can easily transfer to light, radio, or other advanced methods such as simply visually accentuating and vibrating their space suits, to be visually perceived by neighbouring drones.
If they indeed are advanced and technological and can manufacture space-suits for their individuals, communication can then be particles (perhaps such as shooting actual atoms out in same frequencies) or even (although highly speculative) manipulation of fields other than EM fields (potentially even gravity for extra long-distance swarm communication).
[Answer]
**They flicker with light.**
Each of your swarm units flickers with light. By light I mean an enormous range of the electromagnetic spectrum. Just as a laser in an optic cable can transmit enormous amounts of information by flickering, so too your creatures. Different wavelengths are reserved for different types of information. Your creatures are able to perceive very slight differences in wavelength and so very rarely do two creatures in proximity confict.
I see you ask that communication "not be electromagnetic in nature" but you go on to discuss magnetic fields. Electromagnetic radiation is light from radio waves to gamma rays and I would not expect these flickers to be impaired on the short scales you are using.
[Answer]
this is very intriguing and it seems you have thought through a lot here - very cool to see where this will go :)
Some thoughts:
1. As for the means of interconnection within and across swarms, if you want to refrain from electromagnetic transmissions, you can use the surrounding particles in the atmosphere (think nitrogen molecules) or special nano-bodies floating in it (think flower pollen / dust ) as kind of a "conductive" medium through which signals can be carried across huge distances if needed (without the need for direct line of sight). An interesting implementation of this idea (although different enough so you can adapt it to your own) was used in the novel Rosewater ( <https://www.goodreads.com/book/show/38362809-rosewater> ) where this kind of conductive ether was used for the hero to receive "supernatural visions" and data on remote places. You could use something similar where each Unit can pass on the signal to its immediate neighbors and so on like a neural network
2. As for the "encryption", you can maybe find some more plausible mechanism which isn't quite encryption but resemble more the routing mechanics of IP addresses - making sure a signal reaches a specific recipient (unit) or subnet (a swarm) without being interperted or read or intercepted by another net through which the data is routed. Maybe some of the carrying bodies in the air have some electric polarity patterns that define a "subnet mask" or "IP range" for which the signal is meant to reach.
Good luck :)
Noam
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I have a fairly-straightforward alternate modern-day Earth setting, somewhat similar to Ace Combat's [Strangereal](https://acecombat.fandom.com/wiki/Strangereal) or the '[America](https://gta.fandom.com/wiki/State_of_San_Andreas_(HD_Universe))' seen in Rockstar North's GTA series (real life, with the serial numbers filed off).
I'd like to take my counterpart countries etc and place them on a map that's reminiscent of Earth - similar proportions of water to land, ice to forest, etc - but which doesn't reflect the continental or country layout of our home planet.
It would be nice to accommodate (even coarsely) procedures like erosion, rain shadows, tectonic plate movement, etc in the production of this world / worldmap, but unfortunately I am no geologist / tectonic engineer.
It's a somewhat grandiose question, but... Is there a means to automate the process of building a mostly-accurate new planet? Can you recommend a piece of software, a web app or a guide I can follow to construct my globe?
This kinda imaginative exercise is quite new to me - any suggestions would be appreciated! Thank you!
[Answer]
**Google maps.**
[](https://i.stack.imgur.com/ODQ1W.jpg)
Mountains. Forests. The confluence of two great rivers. It is on our Earth now. Recognize it? If so, answer in [ROT18](http://members.quicknet.nl/nj.vandompselaar/files/prive/converter_for_rot_5_13_18_47.html) please in comments.
There are features on earth now that are real, but are not easy to recognize out of context. You can copy all of their landforms intact, down to placement of cities. And it will all be correct according to plate tectonics, erosion, etc.
If out of principle you do not want to use Google maps, you can still use Earth.
[](https://i.stack.imgur.com/tK7NN.jpg)
<https://dinosaurpictures.org/ancient-earth#90>
It is Earth in the Cretaceous. This site will take you back as far as you like but there are other that will take you forward, shifting the continents to unrecognizability. Again, no-one will be able to say you made up something stupid or ignorant. Or if they do you can point at God and say "You talking to Him?"
---
Comment noted: you want random and unique. How about this?
[](https://i.stack.imgur.com/RDdhI.gif)
<https://donjon.bin.sh/world/>
You give it parameters (%water, %ice, iteration) and a random number seed and it makes you a world. I think Minecraft uses something similar.
[Answer]
If you are genuinely concerned about tectonics, the only simulation tool I'm aware of is [this](https://davidson16807.github.io/tectonics.js/blog/news.html).
Otherwise, I'm a fan of [Azgaar's FMG](https://azgaar.github.io/Fantasy-Map-Generator/), although it's a bit better suited to smaller-scale stuff (islands, small continents) rather than full worlds. The climate simulation seems decent, but the way it generates heightmaps isn't particularly based on real processes.
One issue I think you're going to have is that I don't know of *anything* that does world-scale generation down to the degree of detail where erosion is going to matter significantly. You're asking about processes that occur at very different scales.
[Answer]
The Youtube channel [Artifexian](https://www.youtube.com/user/Artifexian) does a lot of good videos about building planets from scratch, but I'm afraid he doesn't have a lot of good words to say about any of the programmes that artificially generate geographic features. I guess it comes down to where you want the balance between being quick-and-easy (in which case, the map generated above is perfectly sufficient), or being as scientifically plausible as possible.
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The male MUTO creature new godzilla movies has a very peculiar wing design: despite having leathery wings, those don't connect to the side of its body, but to two support "rods" that seem to come out of its arm or the very base of it at least.
[](https://i.stack.imgur.com/IK7XW.jpg)
Now, despite the creature as a whole being mostly impossible to exist, could a similar structure work? If not, how could it be, preferably without giving up on its leathery nature, made more similar to bird wings; which have feathers not fused to their bodies but can still lift it during flight?
[Answer]
Superficially the structure is not dissimilar to that of birds, with the rod structure you've identified providing structural rigidity comparable to the scapular blade:
[](https://i.stack.imgur.com/Ud2JI.jpg)
So the question is really whether the bat wing structure can function without the plagiopatagium, or a reduced one:
[](https://i.stack.imgur.com/QMTKU.jpg)
Table 2 of this study—[Frequent or scarce? Damage to flight–enabling body parts in bats (Chiroptera)](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6645484/)—concluded the plagiopatagium is the first or second most common membrane to be damaged among numerous species. A second study—[Bat flight with bad wings: is flight metabolism affected by damaged wings?](https://jeb.biologists.org/content/216/8/1516)—came to the following conclusion about the effect of plagiopatagium damage to flight:
>
> During flight experiments, bats with damaged wings flew at a similar speed to conspecifics with intact wings (Table 2). However, bats with damaged wings performed fewer U-turns in the circular flight arena than conspecifics with intact wings (Table 2).
>
>
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So it would seem plausible that this wing structure works for basic flight, but is not ideal for complex changes in direction. It should be noted that the second study takes into account changes to metabolism and body weight as compensation to the reduced functionality of the wing.
[Answer]
So the question that comes up a lot with dragons is, how do they have four legs (or two legs and two arms, depending) and also wings. The answer there is to consider them as hexapedal animals, like insects. In the case of the MUTOs, we can go one better: they are octopeds, like arachnids. Take a look at the non-winged MUTO, with his two legs, and three pairs of arms. In his case, one pair of arms appear underdeveloped (though that need not be seen as a value judgement--maybe they're just more useful to the males that way).
In the female, two pairs of arms then form the support structures for the wings, with one being much larger and supporting two bat-like "fingers," while the other pair only forms the rods. A close examination of the place where the wings attach to the body shows that the rods don't *quite* connect to the same joint as the larger wing limb, implying a wholly separate joint structure.
Since such body-plans, at least on Earth, are pretty much never unique to a single species or even clade, this opens up the possibility that there is a whole taxonomic class of octopedal animals on your world.
As for what advantage this might grant an animal, over simply having the wings attached to the body, I must admit that my understanding of animal locomotion is lacking, but it seems... dubious. For one thing, the rod structure would have to be pretty muscular to withstand the stresses of flight, and even so I'm not sure it would ever offer an advantage to anchoring the wings to the body. There's a reason you don't see a lot--or any, so far as I'm aware--aircraft which have this sort of gimbaled wing structure.
I suppose it might grant your animals some extra maneuverability options: you could, essentially, turn both of your wings entirely into elevators or ailerons. But again, this is putting a lot of stress of the limbs in question, especially the bones, which would already have to be quite light in order to attain flight at all.
So, biologically feasible, sure. Advantageous, from an animal locomotion standpoint? Not in this reporter's opinion. That said, I am not an animal locomotion expert, or even an aerospace engineer. It could be that there might be some uses for this setup that I'm just not seeing.
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We played with technology too powerful for humans to wield and opened a gateway to a parallel universe, on a dark world with a dying sun. The dominant lifeforms on this world are semi-sentient flying squid-like beings that invade the bodies of the first explorers. The offspring grow within the host, and take over its mind and body, mutating it physically.
But these entities fear the light, as well as fire. Why is this the case? One intrepid survivor, a scientist, decides to do some investigation on one of the dead entities.
What does he find?
[Answer]
So, the creatures have certain biochemical problems with high amounts of light. Similar to the way small amounts of UV are good for humans (for vitamin D) but large amounts sunburn us. It's just that for them, they rely on visible light for this purpose, and an older flashlight would be enough light for them to perform their analogous process. Stronger amounts of light cause photochemical burns (why you actually go blind after looking at the sun) that are painful to them.
Fire is painful to them because as they live on a dark world without much sunlight, the temperature is much colder. Their biochemistry is adapted to the colder temperatures, optimized for a temperature of 5-10 Celsius. They avoid fire as they would develop heatstroke very rapidly if exposed to fire. In fact, inside a room-temperature outpost, they would be at risk for heat stroke (think a human in the desert) but a room with a fire in it quickly becomes way too hot to risk.
(Also, this body temperature thing gives you a good way to make them scarier - give the base infrared motion detectors, and have the possessed & mutated humans not set them off, since their body temperatures are lowered.)
[Answer]
>
> The offspring grow within the host, and take over its mind and body, mutating it physically
>
>
>
...but in so doing they adopt the chemistry of their home world, which is optimized for low energy reactions. Strong light, or any significant electromagnetic emission - and a fire has a powerful infrared emission - is harmful to them, and becomes harmful for the mutated host.
*After testing his hypothesis, the scientist hacks a portable LED light replacing the emitters with high-emission UV diodes.*
(This somewhat resembles the plot of [*Operation: Annihilate!*](https://en.wikipedia.org/wiki/Operation_--_Annihilate!))
[Answer]
**There is something they fear.**
[](https://i.stack.imgur.com/PDmG4.jpg)
The brightness reminds these creatures of the things they fear.
When your scientist studies a dead one, he finds a brand where symbols have been burned into its flesh to form a ring. To his great surprise, he can read the symbols. They are Hebrew letters.
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Let's say that sometime in the future, technology has advanced enough to the point where we are able to create a controlled black hole and hold it open with exotic matter, creating an Einstein-Rosen bridge (please correct me if I'm using the wrong terminology). Assuming that we are able to keep the bridge stable and traverse through it - how could we actually figure it *where* to open the bridge to? Is there any way of doing that, theoretically, or would it just open at a random point in space-time? Could we control the coordinates at all?
[Answer]
Since this is entirely theoretical, the answer is **whatever you need**.
Usually the destination locus is either (approximately) controllable from the input black hole's parameters - mass, spin, electric charge - or it might depend on where the input locus actually *is* (for example, its position relative to the nearest star).
See the description of an *Alderson tramline* in Niven & Pournelle's *The Gripping Hand*:
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> Ships travel along Alderson tramlines. Tramlines form between stars, along lines of equipotential flux. *I won't explain that, you got it in high school...*
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In other works (e.g. J. P. Hogan's *Giants* pentalogy), the hyperspatial projection of a gravitic vortex - an "open" black hole - is controlled through mass, spin and "other parameters". By manipulating the first two parameters, the exit point is positioned somewhere in a implied three-dimensional Newtonian isochronic continuum. By fluctuating the latter parameters, the terminus' fourth coordinate can be uncoupled from its default setting of "now" and land somewhen else.
In some cases (Hogan again, or the 'Second Takeshita Hypothesis' in David Weber's *The Apocalypse Troll*), a strong enough transition might land the terminus in a completely different *universe*.
[Answer]
Realistically speaking? Probably you'd make both ends in the same place, then move them around. It doesn't matter at all, though (the answer is "whichever is most interesting to you") - there are plenty of published worlds using both options, with nobody objecting. For some random examples, Peter F Hamilton's *Commonwealth* has wormholes that open to wherever you like (there's a scene in one book where some characters are rating new planets for colonisability by sitting in an office and opening wormholes into orbit above them for initial surveys, then onto the surface for more detailed investigations), whereas Iain M Banks' *Algebraist* world has wormholes made with the holes together then spread apart the slow way (and, indeed, the book is set in a system that has its wormhole blown up at the very start, and doesn't get it back until right at the end - because it takes a very long time to ship wormhole ends around slower than light - making this an exceedingly rare example of a space opera with (almost) no FTL).
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[
In June 1938 *Action Comics #1* was published, introducing Superman to the world and codifying the modern idea of a superhero that the world has known for almost the past 80 years. There were superpowered heroes that existed in popular culture prior to this, such as the various demigods and heroes of myth (Hercules, the Biblical Sampson, etc.) and more contemporary works such as *Gladiator* (1930), John Carter in *A Princess of Mars* (1912), and even folk heroes like Paul Bunyan and John Henry, but Superman basically defined what it meant to have superhuman abilities and set the stage for everything that followed, including *Captain Marvel* (the DC/Fawcett one), *Spider-Man*, *X-Men*, *Captain America*, *Fantastic Four*, *Green Lantern*, *The Flash*, and more. Most heroes in science fiction and fantasy prior to that time had no superpowers or at most relied on gadgets.
However, in a fictional universe set prior to 1938, it is almost certain that characters wouldn't view someone having powers in terms of Superman because the modern idea of a superhero hadn't entered the public consciousness yet, similar to how *Cowboys and Aliens* has its characters contextualize what we would recognize as modern-style extraterrestrial invaders in terms of demons and angels.
My question is this: **how would someone alive in the 1920s-1930s explain or rationalize superpowers**? I am specifically asking this in terms of a stereotypical urban fantasy/superhero genre conversation set in this time period between two people with superpowers, one who is experienced with powers and one who is new to having them, where the experienced individual provides exposition as to what is going on. **The experienced individual is basically trying to sell the idea of "you have superpowers and that's okay" to the inexperienced one.**
If this were a conversation set after 1938 the experienced individual would obviously say something akin to "you're like a superhero now" or "you have powers like Superman now" as a point of reference, but if this is in the 1920s-1930s superheroes as we know them weren’t a part of the public consciousness and they wouldn't make that analogy.
**Additional Parameters**
* **The story is set in New York City during this timeframe** - Just to give an idea of where the characters are coming from in a geopolitical or cultural background.
* **Powers work on X-Men rules** - The superpowers run on the same rules as *X-Men*, they just sort of appear without any clear warning. There is no alien contact or secret government super-soldier project or exposure to radioactive rays or some other pulp-y science of the times that the character can point to and say "you touched that and it gave you extra-ordinary abilities". Nor anything like many of the old folktales where you had to make bargains with dark powers or drink out of a wolf's footprint to gain magic.
* **The powers are kind of weird** - The best I can analogize it, the powers are kind of like Stands in *Jojo's Bizarre Adventure* or Quirks in *My Hero Academia* where the nature of the powers varies massively between wielders despite having a common origin and some are just plain strange. So it's not like they just have minor super strength or a healing touch that can more easily be rationalized (in context of the times) by comparisons to saints or fictional strongmen. The powers don't inherently make one good or evil, though people can always go power-mad.
* **Blessed/Cursed by God isn’t really an option due to context** - I realize the further back you go in history the more likely someone is going to invoke religious explanations for unusual or seemingly supernatural phenomena and it is likely that someone will come to this conclusion, but in this case it really doesn’t work. Both people involved in the conversation have powers, and it is very unlikely that the experienced person is going to try to sell the idea of having powers as “oh yeah, we’re horribly cursed” unless they have a martyr complex. Blessed might work to some degree but the powers are too weird to easily classify as a divine blessing.
[Answer]
# Othering is Not Dependent on Context
The name or terminology might be different, as you say ("You're like Superman!"), but assuming there's a community of people with powers (X-Men-esque), people will find a name! Maybe biblical - "You're like Samson!" if they have superstrength - maybe fictional - "You're an Achilles!" if they're invulnerable.
In general, the *popular* name for those with powers would be dependent on their public image. If they behave heroically, they might be referred to as something like "the Gifted". Some might have quirkier or less useful Gifts, but they can do things that non-Gifted humans cannot.
If the most popularized cases tend to turn to crime or seek power, they could be the Marked, the Curse, or the Dark. Particularly in the 30s, the last might have particularly vile resonances.
If it's just accepted as a fact of life, they might still be the Gifted (if all the powers are positive), or simply the Empowered. Both of these imply agency (a gifter, or an empowerer), but that doesn't have to be a deity, and can be as readily attributed to chance.
If the community is substantial, then they might have a name for themselves that your experienced member might employ - "I don't know what to do?" "I felt the same way when I first found that I was a Bright. Trust me, it can be hard, but you'll find that you've been exceptionally fortunate!"
You don't need a catch-all, particularly if the population is sufficiently small that someone needs to have the concept of having powers explained to them.
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> "What's a Bright?"
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> "Brights are people born with the potential for abilities far beyond those of the average citizen. I'm one of them - and so are you! You might be able to do things thought to be miracles or magic!"
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[Answer]
# As easily as they would today.
I believe you're seeing an issue where there isn't one, and that a person without our “modern” conceptions of superpowers would still be able to conceptualize superhuman abilities just fine.
The crux of your question seems to be about points of comparison. Humans have been telling stories involving magical powers probably for as long as we’ve had the ability to speak. The world is full of folk traditions about people who can fly or turn invisible or transmute matter, let alone the powers of non-human creatures. These are all beings possessing unexplainable supernatural abilities, which do not stem from some divine cause; the magic simply exists.
Nevertheless, mythological god-powers still provide good points of reference. It’s entirely sensible for a character to remark, “I can hurl electrical energy around, sort of like Zeus,” without believing he literally possesses a power bestowed by a god. In other words, characters can freely describe magical abilities in terms of being similar in effect or appearance to the powers of some mythological deity without the divine connotation attached.
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> The experienced individual is basically trying to sell the idea of "you have superpowers and that's okay" to the inexperienced one.
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Obviously, that particular conversation is specific to those characters. But the general notion of conceptualizing the magical abilities in question wouldn’t be all that different than for someone from our post-Superman society. We just have other things to compare against.
[Answer]
**People with super powers were being depicted in popular fiction at the turn of the century.**
In addition to people with gadgets and super tech, there were visitors from other worlds and other planes, persons with magic powers, and plain super powered persons. The fiction of H.G.Wells offers several examples, of which I think the Invisible Man is the best known. Invisibility is a popular super power to this day. More akin to the powers you describe are those in [The Man Who Could Work Miracles.](https://en.wikipedia.org/wiki/The_Man_Who_Could_Work_Miracles_(story))
>
> After a few petty demonstrations, the minister becomes enthusiastic
> and suggests that Fotheringay should use these abilities to benefit
> others. That night they walk the town streets, healing illness and
> vice and improving public works.
>
>
> Maydig plans to reform the whole world. He suggests that they could
> disregard their obligations for the next day if Fotheringay could stop
> the night altogether. Fotheringay agrees and stops the motion of the
> Earth. His clumsy wording of the wish causes all objects on Earth to
> be hurled from the surface with great force. Pandemonium ensues, but
> Fotheringay miraculously ensures his own safety back on the ground. In
> fact (though he is not aware of the enormity of what he had done) the
> whole of humanity except for himself had perished in a single instant.
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>
Dude is so super powered that he messes things up in a huge way flexing his newfound muscle.
I think Superman was very much a product of his times, and an entity endowed with great powers who lives as a human in the ordinary world was already a familiar concept to readers.
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Assume planetary-scale cables are easily constructed, and subsequently ignored.
I am assuming these cables would run just under the surface of the planet from one side to the other for minimal maintenance from weathering. (I am also assuming minimal tectonic activity.)
Would this be able to light up the entire dark side? Only a fraction?
If it helps for quick calculations, assume an Earth-like planet.
[Answer]
Yes theoretically, but it would create a dark patch on the bright side, as large as the area you are lightening.
Reason for this is that an optic fiber simply transport light with almost (mind this almost, it will become important in the following period you are going to read) no attenuation. But if you want to transport X amount of light from A to B, you have to take it from A. Thus, the light you cast on 100 square meter on dark side will come from 100 square meters of the bright side.
On top of that, the tenuous attenuation of those fibers will become important over the distances involved in shining the dark side. Telco usually employ amplifiers after a certain distance in order to compensate the losses. But they don't shine large surfaces. The energetic cost would be prohibitive.
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[Question]
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In my previous [question](https://worldbuilding.stackexchange.com/questions/163199/how-far-should-second-star-be-in-my-binary-system/163361#163361), I asked about how close can two stars in a binary system be for planets around them to stay earthlike, assuming that both stars have very sunlike and both planets very earthlike parametres. After receiving lots of helpful answers, the distance I decided to go for was tiny bit over 20 AU distance, between the two sunlike stars.
But here my new problem comes - with the second star so close, how would my planets nights be affected?
With the distance of 18-22 AU (the distance fluctuates little as the two sun-like stars orbit around the centre of the mass of the two) between the two stars, every year for at least 5 months, night sky would be dominated by the second star, brightness of which would be only 300-450 times lower than the Sun, thousand times brighter compared to the brightness of a full moon which is 400 000 times lower than Sun.
I can understand that concept mathematically, but physically, I honestly can't even imagine how would this kind of bright night look like. I know that it would be as bright as the Sun looks from the Uranus (haha), but I've never been on any of the moons of Uranus, so I can't compare. Just what would that mean for people and animals living on my planet? How can I understand what would it look like, so that I can build my worlds around it?
[Answer]
At 20 AU, Sun-like star will produce 20\*20 = 400 times smaller illumination.
Based on this data: [Lux](https://en.wikipedia.org/wiki/Lux), illumination will be in the range of 200-300 lux (with clear skies), which is more than on Earth on a "Very dark overcast day", but less than "Sunrise or sunset on a clear day" - more in line with well-lit building interiors.
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So, I'm slowly working on a concept a little like "Victorian Shadowrun", where magic is suddenly introduced to Victorian Society.
One of the side effects of this is a metal, let's call it Orichalcum which has some rather interesting properties, including an ability to wind a spring of it rather tighter than a steel spring.
Actually, a *LOT* tighter.
My question is though, *how* much tighter could a metal be wound than a spring steel? What sort of energy densities are possible? Can we get up to something like 45 MJ/kg (gasoline)? Higher?
I'm assuming there's no residual magic in the metal, just a perfect alignment of atoms etc.
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For plausible real-world materials such as [a spring made from single-walled carbon nanotubes](https://en.wikipedia.org/wiki/Carbon_nanotube_springs), you'll get specific energies of the order of 2.125MJ/kg (3.4MJ/l). That's pretty good... much better than lithium ion batteries, but its a long way short of chemical energy storage.
You could handwave your springs being much stronger, but be aware that this would imply that they have a stronger tensile strength than carbon nanotubes, and that has a lot of implications with regards to material technology and manufacturing. Your magical metal would make an excellent armour, for example, and would allow for all sorts of interesting and complex engineering to be performed that would otherwise have been impractical with real world materials of the same era.
[Answer]
It looks like [somebody](http://itila.blogspot.com/2014/05/energy-density-of-spring.html) did the math for you.
>
> * The energy per unit mass in a bit of the spring that is strained with
> a strain of $ε$ is $0.5 \cdot Y \cdot ( ε^2 ) / ρ$ where Y is the
> Young's modulus, and ρ is the density.
> * The stress τ is (roughly) related to the strain by $τ = Y \cdot ε$
> and the maximum stress you can cope with [in a spring that is to be reused many times] is called the Yield strength, which I'll denote by the symbol $τ\_{max}$.
>
>
> Putting these facts together, if $ε\_{max}$ is the maximum strain $ε\_{max}=τ\_{max}/Y $ The maximum energy per unit mass in the bit of the spring that is maximally strained is $0.5 \cdot Y \cdot ( τ\_{max}/Y ) \cdot 2 / ρ = 0.5 \cdot (τ\_{max}) \cdot2 / ( Y \cdot ρ ) $
>
>
>
which can be tabulated as follows
[](https://i.stack.imgur.com/roOez.png)
Considering that 1 Wh is equal to 3.6 kJ, you are pretty far from what you can get with gasoline, since you get at best below 24 kJ/kg, 3 orders of magnitude lower, by using carbon fiber.
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The main source of free energy that allowed life on Earth to develop was our *sun*. It bombards the planet’s surface with photons of high energy, which provide activation energy for reactions necessary for photosynthesis. Photosynthesis allows plants to grow, and their high-energy organic matter can be consumed by heterotrophs, which can then consume each other as well, etc.
**QUESTION:** Suppose we have a planet that starts off as a soup of inorganic compounds, as did primordial Earth, but that is quite far away from the nearest star. What might be some other sources/mechanisms by which energy could be harvested and life could form?
Some ideas:
* Even if the nearest star is far away, *some* of its light will still hit the planet, and the *occasional* high-energy photon might strike the surface. So maybe we might still see photosynthesizing organisms (or something like them) spring up, but with much slower metabolisms and longer lifespans (since they have to wait a long time for less frequent high-energy photons).
* The core of the planet would still be quite hot, meaning that volcanoes and underwater vents could occasionally release hot (and therefore high-energy) bursts of liquid/gas into the environment. Perhaps this could be harnessed, somehow...?
* I think I remember reading that primordial Earth had a lot of electrical storms. Maybe some sort of mechanism could evolve by which organisms harvest electrical energy?
Can anyone provide any other ideas, or flesh out (or even refute) any of my preliminary ideas?
[Answer]
Welcome to the stack! Great question!
>
> The core of the planet would still be quite hot, meaning that volcanoes and underwater vents could occasionally release hot (and therefore high-energy) bursts of liquid/gas into the environment. Perhaps this could be harnessed, somehow...?
>
>
>
This is the most likely answer, and it's occurring right here on Earth as we speak. [Riftia Pachyptila](https://en.wikipedia.org/wiki/Riftia_pachyptila) are the best known example. These are a species of tube worms that live exclusively on the deep ocean floor around volcanic vents, and they survive entirely upon energy drawn from the vents, completely independent of any energy from the sun. There are a number of other [extremophiles](https://en.wikipedia.org/wiki/Extremophile#Examples_and_recent_findings) and other species that have evolved in this way.
There have been enough examples of life of this kind found here on earth that scientists are considering it more and more likely that life like this could exist in other places in our solar system. [Europa](https://en.wikipedia.org/wiki/Europa_(moon)) is considered the most likely candidate even though its surface is frozen solid, because the tidal forces from Jupiter drive sufficient geothermal activity that vents just like the ones on Earth could be present on the bottom of Europan seas as well and, if so, there might be life there utilizing the same energy sources.
With regard to your other possibilities, the main thing to consider is that there has to be SOME kind of energy source for life to occur. Radiant energy from a star isn't the only possibility, but it is the easiest. Tidal forces creating tectonic energy like you get from the Galilean moons is another. One way or another though, you have to have heat to drive the chemical processes required for life.
I would note that in your third example, those electrical storms found on ancient earth were ALSO driven by energy from the sun, but here again, a nearby gas giant could provide the necessary juice via its own colossal magnetic field. Jupiter has massive electrical storms in its own atmosphere, and it's believed it might be driving similar storms on Io and/or Callisto as well.
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The nucleous of the planet could be pretty hot and provide enough energy for a stustainable life.
If the nucleous of the planet contains a enough radioactive materials, it could continue producing heating for billions of years, enough to allow the formation of a complex life.
The main problem is that there could be no photosynthesis, so no oxygen, or oxygen must be produced in another unknow way.
Life is possible in a Reducing atmosphere, on earth there are many extremophiles bacteria able to live in these conditions thanks anaerobic metabolism.
The problem is that all anaerobic metabolisms that we know are all too inefficient to sustain complex life.
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Some say that one of the reason humans developed agriculture is because megafauna (specifically the Pleistocene megafauna) were hunted for food to extinction and humans were forced to develop agriculture to survive, or that the lack of megafauna means no competition for humans to develop agriculture.
Ignoring other possible reasons like climate change killing off megafauna and creating suitable conditions for crops, is it possible for humans to develop agriculture while most megafauna are still around? And how would agriculture affect those megafauna?
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**Yes**
Fences can keep out megafauna but the key to doing it successfully is plenty of space and not many humans.
If you look at Africa, farmers use beehives and thorn bushes to protect crops from elephants
See [Comparing the effectiveness of beehive fences to thorn barriers in farm invasions and exits by elephants](https://www.researchgate.net/figure/Comparing-the-effectiveness-of-beehive-fences-to-thorn-barriers-in-farm-invasions-and_tbl1_227667487)
The real problem is too many people requiring too much land and pushing out and hunting to extinction of megafauna
If humans domesticated some of the megafauna, it could open up more agricultural options.
[Answer]
**Yes**
Agriculture is still able to be developed with the existance of megafauna. It's a matter of keeping the megafauna away from the farms that dictates the agriculture. If your people are able to set up some sort of barrier and herd the animals away, then your farms are able to grow and thrive.
If this is in the agricultural revolution-era, than it will be slightly more difficult.
Your people could build wooden walls, or wooden spike barriers around the farms.
The megafauna issue could and would be difficult. Your people could do a variety of things- like herding(as mentioned above) or domestication. Domestication would be the most efficient, though also the most difficult.
Herding would be the more realistic option. Like we do with cattle today, group them up in areas with more other megafauna and keep them in those areas.
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I’m trying to develop a realistic system with a limited understanding of astrodynamics.
Is it possible to have two binary worlds capable of sustaining atmosphere and complex life orbiting one another at such close proximity that they dominate each other’s skyline with even city lights of the other world in the sky being clearly visible at night?
Does the scale of the worlds or the distances involved mean that that can simply never exist?
[Answer]
# Hmm, it might be possible...but unlikely.
To respond to the clarified question (can be found in the comments), let's assume that by "take up the sky" you mean that each planet has almost a 90 degree angular diameter when viewed from the other planet. This will take up 50% of the night's sky. (Getting 100% is impossible due to the curvature of a spherical object)
I have calculated that the distance necessary between two Earth-sized objects for the above scenario is about **15380 km**. This leaves only 2638 km of distance between the outer surfaces of each planet! Uh-oh! That might be too close for each planet to be habitable!
With each planet taking up 25% of the sky, this distance increases to **23019 km**, leaving around 10277 km of space between the surfaces of the planets. This is still extremely close.
However, you'd be surprised at how big objects will look, even if they do not take up most of the visable sky. For example, with an angular diameter of 5 (about 2.7% of the sky), the planets would appear to be about **10 times bigger in apparent size than the real-life full moon**. The distance required for this sight is around 152429 km (about half the Earth-moon distance), which is a significantly greater distance and would **almost certainly be habitable.**
If you want to calculate the distance necessary for two Earth-sized objects, use the following formula, which I derived from the formula for angular diameter:
$$D =\frac{d}{2\;sin\left( \frac{\pi a}{360} \right)}$$
where $D$ is the distance between the two objects, $d$ is the actual diameter of the two objects (assuming they are identical), and $a$ is the desired angular diameter, measured in degrees.
The result (distance) of this formula will always be in the same units that you provided for the actual diameter.
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>
> Note: this part of my answer was written before the original poster clarified his question in the comments. It has been kept here because it offers Roche limit calculations:
>
>
>
>
> ---
>
>
> ### What you are looking for is the [Roche limit](https://en.wikipedia.org/wiki/Roche_limit) of both planets in your system.
>
>
> Let us assume you have 2 exact replicas of the Earth:
> For a rigid-satellite calculation, the Roche limit is determined by the ratio of the densities of the two objects, and is given by the following formula:
> $$d=R\_M \sqrt[3]{2\frac{p\_M}{p\_m}}$$
> where $R\_M$ is the radius of the primary (larger/more massive) body, $p\_m$ is the density of the primary body, and $p\_M$ is the density of the satellite.
>
>
> Since $p\_M$ and $p\_m$ are the same, they cancel out and become $1$. The simplified equation then becomes:
>
> $$d = R\_M \sqrt[3]{2} $$
>
>
> According to this simplified equation (it does not consider inertia force and rigid structure), there are not really limitations on the distance. This doesn't seem correct to me, but it might be due to the fact they are of comparable sizes so the force of one body does not dominate the other.
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[Answer]
The answer to your question is yes it is possible. The roche limit for 2 equally sized planets is very close. Close enough to allow a shared atmosphere even. Although that is another question and there are other issues, suffice to say that two planets could orbit each other in very close proximity.
However such a situation would not be without consequences. For starters it would be unstable as slight orbital perturbations would in all likelihood lead to catastrophe within a few hundred or a few thousand years depending on circumstances.
In addition planets orbiting in such close proximity would generate monstrous tides that would rise and fall by hundreds if not thousands of metres twice a day. Such a situation would also destabilise the orbits.
So in summary the worlds you imagine can exist but would be precarious and liable to destruction within a relatively short period. Life on both planets would likely share a common origin due to the close proximity and the ease of transferring material between the two via large meteorite strikes on either planet.
If you push the planets slightly further appart their life span would increase dranatically.
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**Scenario**
A civilization is living on an ancient super structure, they don't know much about it, they just live there and have lived there for as long as they know. For our current situation we can ignore most of this structure. The interior of it is hollow with the center hanging around an artificial gravity well/power source, for this case just imagine it as a star. Everything living on the inside is literally hanging over the void above this.
The outside of the structure is unsuitable for life, and the old working have a tendency to periodically get exposed to open space and the old machines can take a bit to fix things. Sure many people live here, but it's a dangerous life. So unless they're pretty bad off most live on the interior of the structure overhanging the void.
To sustain atmosphere and life on the interior we have a soil that can stick to the interior of the surface with minimal loss to the central mass. On this we have plant life, part of it being trees.
**Details that may matter**
* Gravity at the surface (pull toward the central structure), is approximately 1 G. Important to remember that down, is toward the central gravity well.
* I haven't figured out what the soil would need yet...that's going to be in a different question. Figure it's something that will be sticking to the surface between composition and plants preventing erosion, maybe magical machine tech making sure it stays in place.
* Root structures can dig deeper into the superstructure and can wrap around some of the super tech metals that are making it up. They won't break easily under any weight said plants and civ can put on them.
* Trees are growing both toward the center of gravity and their light source. Figure they have plentiful water from the super-structure they're growing on.
* Been running through tree questions and learning things, but figured this was a bit different since these trees aren't going to be fighting anything but their own weight from what I can assess.
* Not much happening to cause a change in seasons, assume we have an eternal summer going. Maybe no more than slight temperature variations of ~5C, so 21-26C.
* The super structure has in place its own super hand-waving tech in place that we don't understand that can recycle lost matter going to the center. So don't be concerned about some matter loss. It IS sustainable as long as it's slow enough that things grow and people can actually make decently long term cities in places (200-300 years.) This includes allow air near the "top" to stay at a level that can sustain life.
* Central mass is far enough away things aren't going to randomly hit it. It's not going to cook everything, it's designed to sustain the life not kill everything.
* It's less important of how this environment is possible, and more about how things would be or may need to be if it was possible. For this particular question the concern is the large plant life (trees.) How would they react if light and gravity worked from the same direction, unlike on a normal planet where they are basically fighting against gravity to get to the light.
**Inquiry**
The people are building structures utilizing these trees as supports and structures. How large and strong can I realistically expect these inverted trees to grow?
[Answer]
A lot will depend on the "surface" weather, especially regarding winds.
In the absense of winds, the most successful plants will be those that can grow the longest leaf-bearing stalks down into the abyss (though somehow "abyss" seems wrong for an endlessly sunlit void). Those with longer stalks will of course be able to get more sun than those with shorter stalks, because there will be fewer competing leaves in the way.
Immediately, this suggests that there will be no trees of any sort, because there's no benefit to having big chunky trunks; you don't have to support a huge canopy waaaay up in the sky against gravity, as gravity is now on your side. Instead you'll get lots of vine and creeper-like things... stuff like [ivy](https://en.wikipedia.org/wiki/Hedera), for example.
Instead of the tallest, strongest trees, you'll end up with the longest stems with sufficient tensile strength to hold up their weight plus whatever loads might be imposed upon them by epiphytes, wildlife, other creepers, debris, whatever.
A possible figure of merit is "breaking length", or perhaps [specific strength](https://en.wikipedia.org/wiki/Specific_strength):
>
> the maximum length of a vertical column of the material (assuming a fixed cross-section) that could suspend its own weight when supported only at the top
>
>
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This can be surprisingly long! natural oak has a breaking length of over 12 kilometres, if those linked figures are to be believed, and lighter balsa could manage an amazing *53 kilometres*. Obviously your plants will be unlikely to grow out to their own breaking lengths... something will break them, perhaps an accident, maybe the weather, maybe grazing, whatever, but clearly your upside-down canopy could be very, very deep indeed.
Your problem will be more how this aerial canopy is anchored to the body of the megastructure above it. A huge thick mat of vegetation might one day reach a critical mass, and thanks to the enormous tensile strengths of its components a huge scab of the world could peel off and fall to its eventual doom. You might want a lot of decorative knobbly bits on the underside of the structure for the vegetation to cling too, and plenty of grazers and weather to stop things dangerously overgrowing.
[Answer]
You may turn this into a greenhouse structure instead. However, the "glass roof" will be inside the "floor" structure, which is a giant tube or a dyson sphere. The roofing will be valuable in keeping all things within, including the precious atmosphere. The system, however, looks like an inverted greenhouse to its dwellers.
Plants hang from a hard-material roof which does not allow roots in, so roots evolve as a gripping organ, not unlike that of sea weeds. Water and nutrients intake would take place through aerial roots and foliage feeding, similar to what epiphytic plants do. Non-flying animals swing among the vines (Think Tarzan...). Tree seeds and spores are lighter-than-air thanks to gas bladders. They don't get rain, so they germinate as a response to humidity in the air. Water does not obstruct the sunlight as much as debris and is allowed to become the bottom of a lake. For the dwellers, it's like a swimming roof with glass floor and lighting underneath it, and then an opaque roof with hanging vines above it. Aquatic life would recycle the fallen debris and not allow them to pile-up until they obstruct the sunlight. Hunters feed on creatures in this glass-bottomed lake, fly back to the hanging "trees" and "feed" them with their guano...
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**Closed.** This question is [off-topic](/help/closed-questions). It is not currently accepting answers.
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This question does not appear to be about **worldbuilding**, within the scope defined in the [help center](https://worldbuilding.stackexchange.com/help).
Closed 4 years ago.
[Improve this question](/posts/159910/edit)
I know it's common for shops and stores to be named in D&D and other fantasy settings, but how common was that practice in the medieval era (say, from 1000 AD onward)? It seems to me that inns and the like were named more often than, say, the workshops of smiths, traders, or other craftsmen and merchants.
I'm trying to be as "realistic" as possible with the campaign world I'm establishing, so if there's historical precedent, I'll feel better about it.
Edit: It's also been brought to my attention to clarify whether or not I mean this in a general or specific sense. The answer is the former. If the convention wasn't really present in Asian or Middle Eastern countries, for example, but was in European ones, that information still helps immensely. I'm just hoping to find out how popular the practice was in the medieval era.
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I assume that by "Medieval" you refer to Western Europe (As so many do, the rest of the world only appeared in the 16th century, I guess :) )
Retail establishments usually catered to locals only, and was chartered by a feudal lord (hence - no competition). All the local villagers and nobles referred to it by trade (blacksmith, carpenter, tailor) or by name (which is why so many family names ARE trade names "John Smith", "Arthur Fletcher", "Albert Shoemaker")
Only in cities did shops and workshops, under the scrutiny of guilds, allowed to compete. Only there did such establishment given a name (usually the master craftsman name - that apprentices kept for generation, long after the apprentice was the new master).
In the middle-east, where cities existed long before and there was no strict guild-system, shops and workshops were named after the patriarch whose family owned the place. In some places (Allepo, Beirut) shops had women names!
China is a different story altogether - shops had names to deter evil spirits, or draw good luck - and did not have direct connection (maybe intentionally?) to whatever was in there (I don't know about Japan, Korea and Thailand - I guess they followed China's example - but I would not count on it)
West Africa shops were usually of wandering traders, rarely having an establishment. North Africa follows the middle-east example. Horn of Africa has much older traditions - but I did not find references to shops (but it does not mean they did not have them). An Ethiopian colleague of mine explained that they referred to trade differently (I did not understand).
You should investigate about South America cultures... I do not know if they had shops. Neither Oceania.
Good luck!
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Allowing that there are all different stipulations about what makes an android, consider the following android type: a synthetic organic that requires nourishment in the form of basic amino acids to keep the fleshy bits alive. Beneath the flesh, a cybernetic/robotic substrate, integrated with the organic parts. I've heard of several different options for power, including nuclear, solar, etc.
The question: Could hydrogen fuel cells be used as power for the cybernetics (assuming an infrastructure exists in a hypothetical world to produce it and the cells are small enough to be stored in the chassis of the android), and what might a typical battery life be for an average humanoid platform with slightly enhanced physical abilities?
[Answer]
Inevitable answer: "it depends".
A human uses about a hundred watts of power at rest, and maybe double that for extended periods if they're fairly fit. A world-class cyclist might manage as much as a kilowatt (possibly aided by pharmaceuticals).
The power-to-weight ratio of current fuel cells is [quite variable](https://en.wikipedia.org/wiki/Power-to-weight_ratio#Fuel_cell_stacks_and_flow_cell_batteries), but by the time you've got actual androids to power I'm sure that the higher-end figures will be commonplace. A kilowatt fuel cell could, therefore, be only a kilo, and will probably fit inside a replica human torso, no problem. Even more pessimistic estimates aren't that bad, with a 10kg cell providing enough oomph.
Fuel cell vehicles are about 50-60% efficient. This figure probably won't rise that much in the future, so lets assume the worst for simplicity. Hydrogen has an energy density of 140MJ/kg, giving you a maximum of 70MJ of useful energy per kilo of fuel, or 19.5kWh. That's enough to run an idle human for over a week, or a world-class athlete running at full power for a bit under a day.
Modern high-pressure hydrogen tanks are filled at 700 bar. At this pressure, and at room temperature (handwave, handwave) hydrogen has a density of about 38kg/m3. That 1kg of hydrogen, then, could fit in a cylinder of 10cm radius and 83cm height. That's quite big! You'll have difficulty fitting that in a person-sized hull and still have space for all the other useful androidy things you'll be wanting.
Take home message: hydrogen fuel cells good, hydrogen fuel bad. I'm not sure what alternatives would be best in your situation, but obviously depend very much on what you want your android to do and for how long. Other types of fuel cell do exist with much more energy-dense fuel, but current efficiencies are low. Naturally, as the author you may handwave your future tech as you see fit. A methanol fuel cell with a 50% efficiency (current real world figures are more like 10%!) would be a good start... the fuel has 20 times the density of 700bar hydrogen and is a lot easier to work with. Even with a usable energy density of only 11MJ/kg, a 6.4kg fuel tank isn't a big load to haul around and fits in 1/3rd the space.
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In my last question, I have asked on [how, once Mars has been terraformed, Terran species of plants and the insects on which the majority of them rely on would adapt to Mars's longer year.](https://worldbuilding.stackexchange.com/questions/154593/how-can-plants-and-insects-cope-with-living-on-a-terraformed-mars) By far, the only answer I got is to start the pioneering at the equator, where there won't be any seasons to worry about, and the plants can grow, blossom and be pollinated by insects without problem.
But Earth-based plants on Martian soil can't stay in the equator forever!
This question is particularly important not just here, but in any terraforming project involving dumping Earth-based species on any Earth-like habitable rock orbiting a star of any type from a distance greater than one AU (basically speaking, any orbit so far away that one year lasts more than 365 days.) Once the plants and insects have been established at Mars's lower latitudes, how long would it take them to colonize as much of **the rest of the planet** as they can?
*This is not a question that involves evolution, which would take too long. The reason I'm focusing on the plants and insects is due to their interconnected relationships, and how the other animals rely on them as well.*
[Answer]
**Depending on what you mean by 'Terraformed', anywhere from 100 years to more.**
Your terraforming process needs to have not just converted the composition of the atmosphere to a similar composition to Earth, but to also:
* Ensured the phosphates in the soil are removed
* Ensured the planet has a similar atmospheric pressure
* Ensure constant rainfall (but not too much) throughout the planet
* Ensure the soil has a sufficient quantity of nitrates
* Ensure radiation is no longer flooding the surface, whilst retaining a high enough light level for plants to survive.
If the above is miraculously accomplished using Clarktech, then the only similar examples we have on Earth are [newly formed volcanic islands](https://en.wikipedia.org/wiki/List_of_new_islands).
[](https://i.stack.imgur.com/shuoa.jpg)
Studies have indicated the slow growth rate of plants to both travel to the destination, and also to then root themselves and germinate at precisely the right conditions.
The following can be expected:
* first you may need microbes to grow on the surface - these may aid the chemical degradation of the rock and sand to form soil.
* you would require wind to carry microbes, and seeds across the landscape
* normally lichens are the first to grow, as they require little purchasing points and nutrients, however, keep in mind it may take up to 100 years for lichen to grow to the size of a 30mm circle.
* if conditions are perfectly right, however, [some plants would grow after a year on a volcanic island](http://scienceline.ucsb.edu/getkey.php?key=6109). Every island example is different, and on Mars it should be expected that given the extreme environment it wouldn't be this quick (and if it was it would be sporadic, in cracks or isolated areas), however this is rare and some volcanic islands that were formed some time ago are still barren.
[](https://i.stack.imgur.com/hhYdX.jpg)
[Answer]
Don't expect it to happen anytime soon (100's of years). Skeptical answer is to expect it (complete terraforming of Mars) to not happen at all.
As per [Wikipedia](https://en.wikipedia.org/wiki/Atmosphere_of_Mars) and [Space.com](https://www.space.com/16903-mars-atmosphere-climate-weather.html)
* the atmosphere of Mars is 95% carbon dioxide (== no oxygen)
* atmosphere is 100 times thinner than earth (== no air)
* Average temperature at equator of atmospher is 5 degree centigrade (== most species can not survive / reproduce fast)
* water vapour is a trace gas (== a remnant that won't support active life)
So outside of a controlled environment (say closed gas chamber with right conditions provided), very little growth is to be expected, even if you were to use mutated species.
Add to that logistical complexities such as
* growing plants in space (a seed germinated, but germination != tree)
* conducting experiments in space/mars - no man even landed on mars yet
* Earth took ~1.3 billion years to have all this oxygen and other composition of gases available
And this sounds almost impossible in human lifetimes.
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Instead, you can expect setting up of closed terraforming sites which are self-sufficient to be the more prominent way for inter galactic expansion of humanity.
[Answer]
Any living organism will adapt to the environment where it live via evolution, and that implies genetic changes. And that takes quite some time. Also in your case, since you are porting "bees and flowers" to an alien world, evolution will take its time and paths.
You can speed things up by increasing the mutation rate of all the organisms, and let then evolution play its game as usual.
In this [answer](https://worldbuilding.stackexchange.com/a/152844/30492) of mine I explain how this has been done for developing new types of crops, using [gamma fields](https://www.ilpost.it/2017/03/25/spaghetti-nucleari/).
Since insects produce large number of eggs each time, the method seems suitable for them, too.
Thus:
* irradiate a subset of them to induce mutation
* let them grow and see if there are any useful mutation
* select the mutation and start over
Since, on a first approximation, evolution rate is directly proportional to the mutation rate, by increasing the mutation rate of a factor $\alpha$ you are also reducing the time to adapt by the same factor.
Considering that insects can have more generations in one year, you can speed up the process a lot.
[Answer]
assuming you have engineered mars to be the atmospheric composition as earth, so we don't have to worry about plants dying in a newly seeded place it is a fairly easy math problem.
Lets say seeds spread about 1.5 meters from the parent plant. we start with a single plant. the surface of mars is 2106 miles, or 3389278 meters.
an equation of 1.5(x^2) - 3389278 = 0 will solve the timeline until plants cover mars, including the poles and polar regions.
it will take **1,503 seasons** if plants propagate once a growing season. feel free to fiddle with the numbers to exclude poles or deal with the equator which will have a better growing region than the rest of the planet.
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I'm writing a story that takes place in a world where people live on continent-sized chunks of earth (basically the size of tectonic plates) suspended in the air, left over from some cataclysmic event.
Before this event, it was a thriving planet with a technology level slightly superior to our own (with highly advanced nanotechnology and other magnetic-based technology)
I've done a lot of research on google in order to find some possible solutions for what hold up the islands, and the one that sticks out to me the most is superconductivity (AKA quantum locking).
I do want the explanation to be more natural-physical, involving technology as little as possible.
There are two important factors to this scenario:
1. It needs to be feasible;
2. Life still needs to be possible.
As far as the feasibility goes, I've also considered possibilities such as having a certain material in the mantle or aesthenosphere, or possibly a high iron content in the crust before the continents are lifted into the air (although I think the latter could affect life on the planet and probably wouldn't work very well).
I've also thought of using diamagnetism instead of having iron-content. But it'd somehow have to be scaled up a TON, and that's not super intuitive.
**TL;DR**: How could I have a feasible floating continent scenario through natural-ish means?
-If I remember other things I've researched or if I have/remember any other ideas, I will probably edit the OP.
[Answer]
In the real world? Not feasible at all. It might just be possible with quantum-locked superconductors, but (unless these are cryogenic aliens living on a world with a surface temperature well below 100K) that will not happen naturally. Maybe room-temperature superconductors are possible, but if so, they are definitely not simple natural materials; they would have to have been manufactured are artificially distributed throughout the continental crust in massive quantities.
Now, that said, that is the explanation for the floating mountains of Pandora from *Avatar*. So, y'know, it's science fiction. You can get away with it if you want.
[Answer]
I like the idea of a planet that blew up. Not a deathstar type explosion, more like an object that gets super heated then cooled very quickly. A fracturing. Massive hemispheres are still locked together having only shifted slightly from the whole, but creating huge cliffs and valleys, some as deep as the core itself. The tectonic plate size chunks that didn't get flung off into infinity are still locked in the gravitational pull of the ruined planet, but sort of 'float' like satellites or moons. The atmosphere might be different from plane to plane, lending to vastly different species or evolutions.
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I am creating a planet with an orange dwarf as its host star and which is at a certain distance from it in such a way that it receives 1 % of the light received by the Earth from the Sun. Obviously, without an atmosphere that has a significant amount of greenhouse gases, the average temperature would be very low, which I don't want. I was thinking of giving the planet an atmosphere with a certain amount of greenhouse gases (CO2 or CH4, for example) to increase the average temperature.
Is there any way to calculate the average temperature that this planet would have considering an atmosphere with *x* % of a certain greenhouse gas (preferably CO2) and a certain atmospheric pressure? (I don't set these values yet)
[Answer]
My first idea was to proceed in a step-wise calculation: first determine the temperature of the planet given its distance from the star, and then add the effect of the atmosphere.
This seems to be also the approach given [here](http://web.archive.org/web/20150211011741/https://www.lpl.arizona.edu/%7Eshowman/greenhouse.html), from where I will quote the most relevant parts.
>
> The first key idea is that hot objects lose heat faster than cold objects. This is obvious from everyday experience (you can feel the heat coming from a fire). Detailed observations show that the rate of heat loss is very sensitive to temperature -- specifically, if the temperature is doubled (on an absolute scale), the rate of heat loss is not twice as high -- it is sixteen times as high.
>
>
> The second key idea is that planets are near an equilibrium where heat lost to space almost exactly equals sunlight gained. Because hot objects lose heat rapidly, they tend to cool off if they have no energy source to maintain their temperature. On the other hand, because cold objects only lose heat slowly, they tend to warm up in the presence of energy sources. In both cases, the objects converge toward a condition where they lose heat at exactly the same rate that it is supplied by energy sources. In the case of planets, the energy source is sunlight.
>
>
> Let's see how this works for a planet with no atmosphere. At the position of Earth, the absorbed sunlight is $240 \ W/m^2$. In equilibrium, this means that the planet would lose heat to space -- as infrared radiation -- also at a rate $240 \ W/m^2$. How can we calculate the temperature from this? Detailed measurements show that, mathematically, the relationship between heat loss and temperature can be described by the equation $F = \sigma T^4$, where F is the rate of heat loss (the "heat flux") and $\sigma$ is a fundamental physical constant (called the Stephan-Boltzmann constant) with a value of $5.67 \cdot 10^{-8} W/m^2 K^4$. We can rearrange this equation to state that, for a planet with no atmosphere,
>
>
> $T = (F/\sigma)^{1/4}$.
>
>
> Plugging the values above, for Earth we find that T=255 K, or -18 C.
>
>
> How does having an atmosphere with greenhouse gases affect this situation? The greenhouse effect only works if the atmosphere is transparent to sunlight but opaque to infrared (heat) wavelengths. Many gases -- CO2, water vapor, methane -- behave just this way. These are the greenhouse gases.
>
>
> In this case, the Earth still gains $240 \ W/m^2$ from the sun. It still loses $240 \ W/m^2$ to space. However, because the atmosphere is opaque to infrared light, the surface cannot radiate directly to space as it can on a planet without greenhouse gases. Instead, this radiation to space comes from the atmosphere.
>
>
> However, atmospheres radiate both up and down (just like a fire radiates heat in all directions). So although the atmosphere radiates $240 \ W/m^2$ to space, it also radiates $240 \ W/m^2$ toward the ground! Therefore, the surface receives more energy than it would without an atmosphere: it gets $240 \ W/m^2$ from sunlight and it gets another $240 \ W/m^2$ from the atmosphere -- for a total of $480 \ W/m^2$ in this simple model.
>
>
> Now like the atmosphere, the Earth's surface is near an equilibrium where it gains and loses energy at almost the same rate. Because the surface gains $480 \ W/m^2$ (half from sunlight and half from the atmosphere), it also must radiate $480 \ W/m^2$. Unlike the atmosphere, however, the ground can only radiate in one direction -- upward. Thus, the surface radiates $480 \ W/m^2$ upward, and because the atmosphere is opaque to this infrared light, it is absorbed by the atmosphere rather than escaping to space. Notice that the atmosphere, the surface, and the planet as a whole each gain energy at exactly the same rate it is lost.
>
>
>
Some key points to keep in mind:
>
> * The greenhouse effect is NOT a situation where "heat is trapped and can't escape." The above calculation makes clear that the opposite is true: the greenhouse effect is how the atmosphere adjusts so that it CAN lose heat when greenhouse gases are present in the atmosphere. About the same amount of heat escapes to space regardless of whether a greenhouse effect exists.
> * In our simple model, we predicted an elevation in surface temperature of 48oC (86oF). This is an overestimate. On the real Earth, the current average surface temperature is 288 K (59oF), not 303 K, so the actual greenhouse effect causes a warming of only 33oC (59oF) relative to an atmosphere without a greenhouse effect. Thus, the crude model presented here overestimates the strength of the greenhouse effect by 50%. This discrepancy is caused by several factors that we neglected. For example, some sunlight is absorbed in the atmosphere rather than at the surface, and some infrared radiation from Earth's surface can escape to space rather than being absorbed in the atmosphere. These effects are all included in real climate models. Properly taking these effects into account would lead to a predicted temperature much closer to the actual temperature.
> * An increase in the abundance of CO2, water vapor, methane, and other greenhouse gases causes a decrease in the fraction of infrared radiation from the surface that can escape to space. This forces the surface temperature to increase as the Earth strives to reach the new equilibrium. More greenhouse gases mean a stronger greenhouse effect and a hotter planet.
> * We can again use the simple expression $T = (F/\sigma)^{1/4}$ to calculate the temperature of the surface. Using F = $480 \ W/m^2$, we find that T=303 K, which corresponds to 30 C.
>
>
> When the greenhouse gas abundance is increased, it takes time for the system to warm to the new equilibrium temperature. During these times, the Earth absorbs slightly more sunlight than it loses heat, which is what allows the warming. Thus, during these times, the Earth is slightly out of equilibrium. What this means is that even if the abundances of greenhouse gases became constant right now, the Earth would continue to warm by another 0.5-1C over the next 50-100 years as it reached the new equilibrium temperature. This delayed warming has already been caused and is unavoidable. Of course, additional warming will occur if greenhouse gas abundances continue to increase.
>
>
>
[Answer]
**Probably not going to work out how you want.**
I believe you are creating a version of [Saturn's moon Titan](https://en.wikipedia.org/wiki/Titan_(moon)). Titan has a greenhouse effect going on (and a smaller "anti-greenhouse" effect), which raises the atmospheric temperature. It's about 10 AU from the Sun, so receives about 1% of the power per unit area.
The problem is that although the greenhouse effect raises the temperature of the atmosphere, this is still extremely cold in human terms ( $94^\circ \,K$ or about $-179^\circ C$ - that's the warmed up version !).
This is going to happen because what limits the temperature you can reach with a greenhouse effect is how much power is being received. There's a limit to how much heat can be retained by an atmosphere. With only 1% of the power per unit area reaching it compared to Earth (or Venus, "Earth with runaway greenhouse effect" ).
**What the upper limit ?**
The good folks at the [University of Indiana wrote a web page that does do a calculation](http://www.astro.indiana.edu/ala/PlanetTemp/index.html) for you and this gives a much higher estimate. Let's assume these astronomy types know what they're talking about. Using their page I choose these parameters (explained on the page) :
* Same solar mass as our beloved Sol
* Planet 10 AU away from the star
* Low amount of power reflected back by the planet (bond albedo=10)
* Venus like runaway greenhouse factor (use 200)
The result is a surprising $-3^\circ C$ or a bad winter in my part of the world.
How reliable is that : don't know, but it's probably better than dice throws. :-)
**However ...**
There's always an however. :-)
If you play around with that page and try some less extreme numbers (a more realistic albedo, more like the 0.29 of Earth, less extreme greenhouse factor), these numbers fall significantly. Just the albedo of 0.29 drops temperature to about $-40^\circ C$ and reducing the greenhouse factor to $100$ (Earth normal is $1$), gets you to more like $-60^\circ C$.
So things go south (pole) pretty quickly.
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I am an aspiring science-fiction novelist. I am experimenting with a world I’m trying to create and I wanted a couple of expert opinions on Atmospheric composition;
53% Nitrogen
27% Oxygen
3% Xenon
15% Water Vapor
2% Carbon Dioxide
Off the bat, the air isn’t supposed to be breathable for traditional earth-based life. It is inhabited by a couple of cultures (most primitive being Neolithic hunter-gatherers, most advanced Iron Age equivalent to the Viking Age), it has a lighter gravity than earth with twice the atmosphere and I am curious what would happen to an explorer from Earth if their breathing mask was removed.
Edit: by twice the atmosphere I mean the atmosphere is twice as thick, allowing more massive creatures to fly.
[Answer]
They would cook.
You are asking for 0.3 atmospheres of water vapor. The temperature of water with that equilibrium vapor pressure is nearly 70 degrees Celsius, or 158 Fahrenheit. An unprotected human will not survive that for very long. And the fact that the air is already saturated with water means our natural heat rejection mechanisms won't work.
The carbon dioxide is also at toxic levels. Despite the high oxygen pressure, the elevated CO2 will cause blood acidosis, leading to hyperventilation and cognitive impairment. The xenon would also have a mild anaesthetic effect, further impairing cognitive function and motor skills.
Neither of those will kill you quickly, though. The real killer is the heat. The CO2 and xenon will merely contribute to making it more difficult for you to develop the presence of mind and motor coordination to actually do anything about the heat.
The oxygen is not up to toxic levels yet for most people, but it may be dangerous for some fetuses and newborns. That, however, will be the least of their problems if a fetus is exposed to this air.
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In my galaxy, I need a planet that is far enough away from its star to be relatively cold compared to Earth, but not so cold that liquid water cold not exist.
The planet has 2 continents, 1 northern and one southern. The southern continent's southern tip is around where the tropic of capricorn is on Earth, and its northern tip is basically the equator. However, the southern continent still only enjoys a Mediterranean climate in its warmest areas. The northern continent starts at around where the tropic of cancer would be on Earth and ends at around where the US state of North Carolina would be on Earth. The northern continent is highly mountainous and generally has a frigid subarctic climate similar to that of Scandinavia or northern Canada.
How far would this planet have to be from its star, assuming that both the star and the planet are about the size of our sun and Earth respectively and that the planet has an Earth-like atmosphere?
[Answer]
It sounds like you're asking about the habitable zone of a star, and for that we have a relatively good idea of where that is for a star like our Sun- a relatively up to date [0.95-1.67 AU](https://arxiv.org/abs/1301.6674 "Habitable Zones Around Main-Sequence Stars: New Estimates") from 2013. [Wikipedia](https://en.wikipedia.org/wiki/Circumstellar_habitable_zone "Solar system Estimates has what you're looking for") has some nice reading on the subject
But in case you were looking for a bit more variety in your stars, I direct you to the [Hertzsprung-Russell Diagram](http://astronomy.swin.edu.au/cosmos/h/hertzsprung-russell+diagram) as a handy 'star energy output' chart.
Any star that outputs more energy than our sun (either by being larger, or burning hotter, or both) is going to move that habitable zone outward, while anything that outputs less energy (either by being smaller, or burning cooler, or both) is going to pull that outer range in toward the star itself. [SOURCE](https://www.nasa.gov/ames/kepler/habitable-zones-of-different-stars "It's from NASA apparently")
With that said, there's some special phenomena that happens with other star types, such as:
* More destructive solar flares
* More interference from solar radiation
* Larger variation in sunspot cycles (I don't remember how that would affect us but still)
And then there's the stuff that happens as a result of shifting in the habitable zones:
* Intensity of sunlight
* likelihood of having a moon drops/raises the closer/further from a large body you are
That's about as much as I know, and you'd have to get into calculations and other stellar bodies (like gas giants and asteroid belts) to be significantly more specific than this
[Answer]
**Cool your planet by reducing the greenhouse effect.**
Instead of moving your planet farther out to make it cooler, adjust its atmosphere. Just as we hear all the time about global warming from more greenhouse gas (CO2), if you decreased greenhouse gases you would get global cooling. Without a little greenhouse effect, the planet will radiate away more of the solar energy that hits it.
<https://www.giss.nasa.gov/research/briefs/ma_01/>
>
> These gases are commonly referred to as "greenhouse gases" because
> they let in most of the incoming solar radiation that heats Earth's
> surface, yet prevent part of the outgoing thermal radiation from
> escaping to space, thus trapping some of the surface heat energy.
> Water vapor is also a major natural greenhouse gas, but its
> volatility, i.e., readily evaporating and condensing in response to
> temperature changes, complicates its role. Increases in the amount of
> atmospheric water vapor, under warmer conditions, reinforces the heat
> absorption by the other greenhouse gases. On the other hand, more
> clouds may form, as a consequence of increasing amount of atmospheric
> water vapor. Clouds can provide either a positive or a negative
> feedback by trapping outgoing thermal radiation or increasing the
> amount of solar radiation reflected back to space, respectively. At
> present, roughly 30% of the incoming solar radiation is reflected back
> to space by the clouds, aerosols, and the surface of Earth. **Without
> naturally occurring greenhouse gases, Earth's average temperature
> would be near 0°F (or -18°C) instead of the much warmer 59°F (15°C**).
>
>
>
Emphasis mine. Relevant gases would be CO2, methane, nitrous oxides and water.
---
**Alternatively you could warm your planet by increasing the greenhouse effect**. Mars is farther from Sol than Earth, but apparently had liquid water back when it had an atmosphere - presumably because the atmosphere provided some greenhouse effect to trap heat on the surface. I am not sure how hot you can get with the greenhouse effect but Venus is crazy hot due to its thick, thick atmosphere. If you moved Venus out to the orbit of Neptune, maybe it would be pretty nice. I think for a fiction you could safely assert this.
[Answer]
Nobody knows.
Go to the Wikipedia article "Circumstellar habitable zone" <https://en.wikipedia.org/wiki/Circumstellar_habitable_zone>[1](https://en.wikipedia.org/wiki/Circumstellar_habitable_zone)
And look at the table called Estimates of the circumstellar habitable zone boundaries of the Solar System. Note the vast, vast differences in the estimated inner and outer edges of the habitable zone of the Sun, and the vast differences in the estimates of the width of that zone.
So after that preliminary research you can do as much more research as you want to, perhaps starting by looking up the articles where various estimates of the habitable zone of the Sun were published and studying the methods used to estimate it.
And you can look up other discussions of the size of the habitable zone of the Sun on the internet.
And you can find other discussions of stellar habitable zones in this site.
Or if you want to be conservative you can always take the narrowest estimation of the habitable zone of the Sun, the one by Hart et al. in 1979, adjust it for the relative luminosity of your fictional star, and put your fictional planet in that narrow habitable zone.
Of course that zone seems much too narrow to contain two habitable planets if one goes by the relative sizes of known planetary orbits, though large enough to contain several habitable planets if one goes by the smallest known absolute distances between exoplanet orbits.
And on the other hand you might want to use a very optimistic estimate of the habitable zone so that your habitable planet can be as far away from its star as possible. I think that the most optimistic outer edge of the Habitable zone in the table is that by Pierrehumbert & Gaidos in 2011.
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The average temperature on Earth is [14C/57F](https://www.universetoday.com/55043/earths-temperature/). Water freezes at 0C/32F. So you don't have much room to play with if you want to keep fresh water from freezing. You can not alter the atmosphere much, and still have humans able to breathe it. Earth could not be much further out from our sun as still support life as we know it.
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Let's assume that some wealthy characters somehow find the plans for a [valveless pulsejet](https://en.wikipedia.org/wiki/Valveless_pulsejet). How is not important. Maybe there was a time travel incident, or some Atlantean book was unearthed, or someone had an intuitive leap after accidentally making a jam-jar valveless pulsejet (before it turned into hot shrapnel). So knowledge of the design is not a problem, nor is budget.
What is the earliest time period when artisans could conceivably have built a workable valveless pulsejet? The main consideration is for metallurgy and metal quality, though feel free to point out more limitations.
The goal is to have something powerful and light enough for heavier-than-air craft (the aircraft itself being out of scope here - see it more as a measure for the desired performance).
Pulsejets can run quite hot, so if some cooling system becomes necessary, it is fine as long as it can be reasonably built at the time and doesn't make the whole thing too heavy to work.
[Answer]
Modern builder build valveless pulse jets from materials as flimsy as EMT conduit, even from high temperature composite. These are low pressure devices; vibration is more of a limit than pressure. Further, if everything is heavy, it matters little unless you're trying to fly.
The bigger issue is fuel availability -- but if the builder knows what he's doing, a pulse jet can run on natural naphtha, which was available to the Romans, and it might be possible to make it run on olive oil (possibly mixed with naphtha for starting). Alcohol of high enough proof will also work, though its lower heat content and combustion temperature (relative to naphta or olive oil) will make it harder to get the jet to run well.
Then, of course, one would have to *know what's needed* -- which isn't something likely in the Bronze Age or early Iron Age, unless you have a time traveler available.
[Answer]
**The Romans could probably build one if the plans were complete enough**
Relevant questions (that I'm very familiar with because I answered the questions):
* [If the Romans found one working steam engine would they have been able to copy and use it?](https://worldbuilding.stackexchange.com/questions/98363/if-the-romans-found-one-working-steam-engine-would-they-have-been-able-to-copy-a/98369#98369)
* [What could prevent us from making alien technology if we had the schematics?](https://worldbuilding.stackexchange.com/questions/136971/what-could-prevent-us-from-making-alien-technology-if-we-had-the-schematics/137028#137028)
* [Reverse engineering electronics](https://worldbuilding.stackexchange.com/questions/87251/reverse-engineering-electronics/87341#87341)
* [Victorian optical sensors?](https://worldbuilding.stackexchange.com/questions/135268/victorian-optical-sensors/135290#135290)
Technological development is a pyramid: a specific technology stands atop a mountain of experience, education, and invention. The problem is that the plans you're sending back likely *don't* include plans for manufacturing facilities, chemical processing, specialized tools...
As an example, I could hand you a schematic for a 1980s computer, but if you didn't know how to build the manufacturing plant for integrated circuits, or the manufacturing plant for silicon slugs to make silicon wafers, or the understanding of what the symbol for a transistor even *meant....* (And let's not talk about glass processing and high-voltage controls for the monitor.) There is a massive amount of secondary and tertiary information that isn't listed in any schematic or set of plans.
A silly but obvious example: the plans for a bridge don't explain how to build a hammer.
Consequently, the plans must be comprehensible to the target audience. If you give the Romans (for example) a working mechanical device, they'd be able to duplicate it. They may not have the metals to make one as nice and efficient as the original, but they could duplicate the functions nonetheless. But hand them the schematic to an Intel 8080-based computer and it's just another meaningless foreign language — a mystery to build religions on.
So, how far back can you go with a pulsejet? How do you explain petroleum to people whose basic concept of oil has more to do with olives or whales? Even if you go to the Chinese, their gunpowder and canon tech is far too heavy to allow a working pulsejet to move, well, a canon.
**Conclusion**
Like @Demigan, I believe the problem is fuel (although metallurgy shouldn't be ignored, simple gasoline could be used if all you wanted to move was a go-kart, but if that go-kart weighs a half-ton it isn't moving). But for anything more complex, you're stuck with developing big-bang chemistry. Even with those instructions, you'd have to give them the instructions for extracting petroleum and refining it or complex chemical processing. I doubt you could build effective pulsejets much more than 50 years ahead of time simply due to the other dependencies on technologies that simply didn't exist yet.
[Answer]
Hero of Alexandria was doing some remarkable things in the first century AD. He made a primitive jet engine (it wasn't capable of flight just spinning and making a racket)
[](https://i.stack.imgur.com/WcppL.png)
<https://upload.wikimedia.org/wikipedia/commons/b/b8/Aeolipile_illustration.png>
This time period is also when distillation started to seriously take off. The creation of high volatility fuels either petroleum or alcohol based would have been well within the reach of the early Roman empire.
Copper while not ideal can easily be worked into thin sheets and beaten into complex shapes over wooden forms which are then removed.
Theoretically, the Romans could have used primitive V1 buzz bombs (without warheads) at the siege of Masada.
[Answer]
Recreating the pulse jet itself could have probably been been done as early as the Bronze Age. Bronze is about as heavy as steel, and is not as hard making it worse for making most tools and bladed weapons, but it is actually very good for its weight at resisting explosive forces, meaning it could be used to make a fairly light weight pulsejet engine.
Fueling it is another problem. The ancient Mesopotamians knew about and harvested petroleum oil since ~6000BCE, but its potential as an incendiary agent did not become known until the Chinese started burning it for light and heat around 0 CE, and advanced refining and manipulation took until ~700 CE when the Byzantines discovered Greek Fire. So whether your instructions include information on how to fuel it could make a huge difference.
The other big caveat here is that your ancient civilization would not go straight from pulsejet to plane. They did not know enough about lift, lightweight construction, etc. Instead, they'd need to see a similar pattern of evolution as the steam engine. It's likely to assume that one person would 1st use it to turn a mill, then the next guy would make a speed boat, the next would find a way to better contain and control the energy with an internal combustion, so on and so forth it would transform their society. Then after about 200 years of refining this tech, some guy would realize that engines are finely strong enough to fly with, if he could just figure out how birds do it; so, like the wright brothers, he or they would study birds much more obsessive that a world without engines would warrant until he cracks the lift problem, and makes his first plane.
This means you need to target a culture similar to the renaissance where a large portion of the population was big into science and experimentation for 2 centuries or longer to make this possible. If you add instructions for making fuel, giving this to ancient Greeks in 500 BCE could result in flight by ~300 BCE. If you don't include instructions for fuel, the Byzantine Empire could probably receive it in 700 CE and have planes by 900 CE.
[Answer]
I'm not going to discuss fuel, since you seem to be sure enough about it beeing a non-issue.
Since metallurgy seems to be the main concern I can tell you exactly *where*, but not precisely when.
**You want to go to southern India**
Rome has been mentioned in other answers but I don't get why. After all, the Romans did import Indian steel for is superior quality. This Wikipedia artice [1] discusses the history of steel production in Inda. Artisans capable of producing the steels you want could be around as early as 300 BCE or 200 CE as Wootz steel, better known as Damascus steel was developed at that time. You project would find a fertile and innovative environment if timed right. While I'm not sure if Wootz steel would suffice for your purposes, the skilled artisans of what would be and already was the industrial heartland of the world stand the best chances of figuring the engine out.
[1] <https://en.m.wikipedia.org/wiki/Iron_and_steel_industry_in_India/> (History Section)
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I know that currently, black hole civilizations are only theoretical. But here are my thoughts on why black hole civilizations are impossible.
# Black Hole Civilization Issues
## 1. Gravity
[](https://i.stack.imgur.com/7OGFt.jpg)
This is an obvious issue. There is just so much gravity around a black hole. The closest you could get to a black hole without having a weirdly shaped orbit would be 3 times the radius of the black hole or in other words 3 times the size of the event horizon. This changes if the black hole is rotating as pretty much all black holes are but still, that is pretty far. Also, it is very unlikely that a planet would form around a black hole because the gravity is so strong.
But even if you could get closer than 3 times the size of the event horizon, there is another gravitational effect that would get you long before you reach $r\_{isco}$. That is tides. The average tidal range on earth is 2 feet or .6 meters. Around a black hole, this would increase by an unimaginable amount. The radius at which tidal forces wouldn't significantly effect you is way bigger than $r\_{isco}$. So big in fact, that the planet would most likely have to be a rogue planet just passing by in order to survive near a black hole. That or be made out of something very dense like metal which wouldn't be effected by tidal forces as much as rock would. But a planet made entirely out of metal poses more issues including magnetism which is already an issue with the black hole itself.
## 2. Magnetic Field
The main problem with the black hole's magnetic field is simply the strength of it. A neutron star can erase your credit card before the neutron star is even visible to your eyes. The magnetic field of a black hole is even stronger, just like the gravity being stronger. Anything magnetic or that relies on magnets would stop working before the planet is even in orbit. If you assume the planet is made entirely out of metal, this black hole magnetic field would cause there to be a strong electric field around the planet which in turn would cause there to be a strong magnetic field. This planetary magnetic field would align with the black hole magnetic field and be yet another reason the planet wouldn't survive. The magnetic force would be so great that it together with the tidal force would spaghettify the planet and anything on it. And even if the force didn't tear the planet to shreds, you would still have the planet move towards the black hole like 1 magnet attracting another magnet.
## 3. Radiation
Now, I'm not talking about Hawking radiation here. I am talking about the radiation that occurs near a black hole because of fast moving particles. There are jets of radiation at the poles of the black hole. But that isn't the only radiation there is. There is also an almost constant amount of radiation due to particles orbiting the black hole. Any civilization that could survive the gravity and magnetism surely wouldn't survive the radiation. I mean, just think about it. The radiation around a black hole is like a constant amount of gamma rays. And yes, it is gamma rays because the black hole acts like a particle accelerator releasing a lot of very high energy photons. Sure, the gravitational redshift might shift it to X rays but still, a lot of radiation at very high energies. There is no way a civilization could survive black hole level radiation or even neutron star level radiation because even with the planetary magnetic field, it just isn't enough for radiation protection. Total extinction would result, even microbes wouldn't survive, and civilization would be impossible.
**But is my reasoning true? Or is it possible for a black hole civilization to survive?**
[Answer]
Okay, while your assumption may not be wrong per se, the reasoning you have for it needs some work. Let's start with Gravity.
Black holes are not points of infinite mass, they're points of infinite *density* a black hole with the mass of our sun weighs (and exerts the same gravitational force) as our sun does. That is to say, if our sun turned into a black hole overnight, the earth would continue to orbit it with no change in the orbit attributable to a change in mass. (This is a simplification but functionally correct.)
Now; you mention radiation, or more correctly, charged particles, which are not the same thing, even though I'm as guilty as everyone of describing them as the same for brevity. The point is, if your planet is orbiting inside the magnetic field of the black hole or has its *own* strong magnetic field, then you're probably not too badly off. Even our sun emits a solar wind of highly energetic charged particles that would do us a lot of harm if it wasn't for our own magnetosphere on earth.
So in point of fact, to some degree at least, the magnetic field you mention and the charged particle wind (this time rushing in rather than rushing out) cancel each other out to some degree.
That said, you do have many problems with the concept of a civilisation in this model. This implies that the planet has existed for a few billions of years with life on it, slowly evolving, in an environment that is relatively stable. We've already had a handful of extinction events on the Earth and it's *possible* intelligent life would have evolved much earlier without them. But, your planet not only has to deal with charged particles, but any other debris surrounding the black hole that is getting sucked in. This could cause a much higher rate of extinction events for your planet, making intelligent life much less likely. There is also the energy level issue; is the fluorescing gas getting sucked in giving your planet enough ambient energy for endothermic reactions of any kind, like photosynthesis, to form? If your life has some form of geothermic-synthesis, that would at least explain why it has such a strong magnetic field, but such life would have a very different ecosystem to what we would normally imagine.
Your point about the competing magnetic fields does mean that *if* you get intelligent life to form, and *if* they reach some form of technological proficiency, their technology will look very different to ours because (mathematically speaking), from our perspective the EM unification is the easiest and most useful fundamental force unification we have. It would be useless to your planet because of the interference, meaning that their technology would probably go down a very different path.
In short, your intelligent life is probably unlikely from my point of view, but not for the reasons you state. In point of fact, 1 is a misconception, and 2 & 3 more or less cancel each other out.
BUT, your black hole still introduces some measure of energy shortages by comparison to a conventional star, and potentially more orbital instability that will cause an increased liklihood of extinction events. So, intelligent life and by extension civilisation will find your environment a very hard place to survive.
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Living too near a black hole is definitely perilous and, with the universe as it currently stands, it's not really advantageous to do so. A star system provides plenty of energy. Where things get more interesting is as the universe ages and the stars slowly die out. Late-universe life that wants to continue surviving would need to come up with a strategy for dealing with the death of their stars and black hole angular momentum is an appealing long-term energy reservoir once convenient self-sustaining fusion is no longer available. Of course, by this point, you're dealing with such far-future tech that it's hard to speculate what life might be capable of, technologically.
I'm imagining that a late-universe black hole civilization would probably either build their habitats a comfortable distance away from the black hole itself or would just harness former star systems that have gone cold and use those to contain the habitats. Energy would be gathered closer to the black hole and then somehow transported to the habitats. Perhaps long-range electromagnetic transmission into vast distributed-collector capture antennae. A light-house stationed around a cosmic whirlpool transforming the slowly decaying currents into the last light for a dying civilization.
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1. Gravity
Not such an obvious issue after all. If we're talking about stellar-mass black holes, the ISCO is measured in mere tens of kilometers; *of course* a planet won't form there, because there's not enough room! At normal distance for planetary orbits, gravity is no different from what is it around a normal star.
Planets could form around a black hole in some of the same ways that they form around neutron stars; e.g., a black hole formed in a binary star system gets fortuitously shot through the heart of its binary companion by an asymmetrical supernova, immediately gaining an enormous disk of material whose "outer" reaches can form into a protoplanetary disk.
If we're talking about supermassive black holes, then the ISCO may indeed be a respectable distance out--so, you end up with a large, spread out planetary system. No big deal. At that distance, tidal effects will be negligible (at least from a "tearing the planet apart" perspective).
2. Magnetic Field
Also not a huge problem. Black holes don't have frozen magnetic fields like neutron stars do. A black hole's magnetic field comes exclusively from it's spin combined with its electric charge. And astrophysical black holes will be pretty darn close to electrically neutral. And even magnetars only have strong magnetic fields *near their surfaces*. The only reason a neutron star can erase your credit card before it's even visible is because neutron stars are *tiny* and not very bright in the visible spectrum. At typical distances for planetary orbits, their fields are just not that strong--comparable to those of regular stars at similar distances.
Black hole *accretion disks* can generate powerful magnetic fields, but if your black hole still has an active accretion disk, well, nothing is living there anyway.
3. Radiation
Jets are only a problem if you are in line with them, while a typical planetary system formed from a protoplanetary disk around the black hole would be perpendicular to the polar jets; they would be a complete non-issue for anyone living on such a planet. And on top of that, you only gets jets if you also have an active accretion disk--and you *won't* have an active accretion disk.
And it is not true that a black hole acts like a particle accelerator shooting out gamma rays from charged particles orbiting it. Neutral particles certainly aren't an issue; they will gain speed falling towards the black hole, sure, but they'll lose it on the way back out, so orbiting a black hole is in that regard no different from drifting alone through deep interstellar space. Charged particles will emit radiation as they accelerate towards and away from the black hole... but not much. Any charged particles that end up close enough to the black hole to be moving fast enough to emit significant synchrotron radiation won't *stay* in orbit very long--they'll be well inside the ISCO, and losing energy to that very radiation. And the rate of replenishment, even in the middle of a dense nebula, just isn't very high.
Now, if the black hole has an active accretion disk, then yeah, the radiation environment would be nasty... so just don't choose a black hole with an active accretion disk! And if the planet(s) formed in place as I suggested above, then there *isn't* an active accretion disk anymore by the time they're done forming. Those things pretty much go together.
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In the very far distant future, 10^127 years from now, much of the mass of the Universe will be contained in black holes. It may in fact be possible for civilizations to continue to exist that far in the future by using the Black Holes something like a hard drive:
<https://www.scientificamerican.com/article/black-hole-computers-2007-04/>
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> A one-kilogram hole has a radius of about 10-27 meter, or one xennometer. (For comparison, a proton has a radius of 10-15 meter.) Shrinking the computer does not change its energy content, so it can perform 1051 operations per second, just as before. What does change is the memory capacity. When gravity is insignificant, the total storage capacity is proportional to the number of particles and thus to the volume. But when gravity dominates, it interconnects the particles, so collectively they are capable of storing less information. The total storage capacity of a black hole is proportional to its surface area. In the 1970s Hawking and Jacob D. Bekenstein of the Hebrew University of Jerusalem calculated that a one-kilogram black hole can register about 1016 bits—much less than the same computer before it was compressed.
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> In compensation, the black hole is a much faster processor. In fact, the amount of time it takes to flip a bit, 10-35 second, is equal to the amount of time it takes light to move from one side of the computer to the other. Thus, in contrast to the ultimate laptop, which is highly parallel, the black hole is a serial computer. It acts as a single unit.
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> How would a black hole computer work in practice? Input is not problematic: just encode the data in the form of matter or energy and throw them down the hole. By properly preparing the material that falls in, a hacker should be able to program the hole to perform any desired computation. Once the material enters a hole, it is gone for good; the so-called event horizon demarcates the point of no return. The plummeting particles interact with one another, performing computation for a finite time before reaching the center of the hole—the singularity—and ceasing to exist. What happens to matter as it gets squished together at the singularity depends on the details of quantum gravity, which are as yet unknown.
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> The output takes the form of Hawking radiation. A one-kilogram hole gives off Hawking radiation and, to conserve energy, decreases in mass, disappearing altogether in a mere 10-21 second. The peak wavelength of the radiation equals the radius of the hole; for a one-kilogram hole, it corresponds to extremely intense gamma rays. A particle detector can capture this radiation and decode it for human consumption.
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So even with the very limited amount we currently know about black holes, we can conceptualize using them as computers. Given the limitations described, civilizations at the end of time will either use supermassive black holes at the center of galaxies as their repository, or perhaps constellations of black holes orbiting each other to provide the equivalent of a [RAID storage](https://searchstorage.techtarget.com/definition/RAID) unit or supercomputer [Beowulf cluster](http://www.beowulf.org/overview/).
Since black holes already exist, civilizations in the galaxy can begin experimenting now so the ultimate supercomputers will be well worked out and ready 10^127 years from now when finally needed...
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Recently, while at an extremely remote filming location for a movie I'm producing, I encountered a young man I'll call Sims who is a literal giant.
Sims is 22 years old, 9 feet tall, and he weights 800 pounds. Extraordinarily, he seems to be proportioned normally, his gigantism is not a result of a pituitary disorder, though he does have physiological adjustments that allow him to thrive at his size.
Despite being untrained, Sims is probably the strongest man alive, capable of deadlifting and squatting over 1000 pounds with ease. His 40 yard dash is 5 seconds, without ever training. He appears at least as durable as an ordinary man, being no more prone to broken bones, torn muscles or ligaments due to naturally stronger materials but he isn't invincible and can get injured.
Now I also have partial ownership in a certain NFL franchise, and I believe that Sims would make a fantastic player. I've broached the subject with him, shown him a few clips of our 2007 and 2011 teams, and Sims is very excited to play. He currently works with his family on their farm, and is tired of labouring all day in the sun.
My question is: What American football position should Sims play and why?
Furthermore, what sort of team and what type of players should I pick to best assist him? Also, how successful do you think he can make my team?
A few caveats: He's never played football before, and I want him ready by August for next season. He speaks no English. He can get extremely aggressive and violent when wrestling with the other villagers, having killed a few by accident, part of the reason he's eager to leave.
Finally, Sims younger brothers also seem to share his mutation. Within a decade I could have up to 7 Sims size players, how would I best incorporate them into my team? Is there another sport they might do better at?
[Answer]
Sims is going to be the world's best tight end ever.
* (-) Sims lacks the speed to be a wide receiver
* (-) Quarterback is based mostly on skill, intelligence, and a specific action (throwing)... there's no guarantee that Sims is any good at it
* (-) If he's an offensive lineman, he'll interfere with his own quarterback's ability to pass over him
* (-) It's tempting to put him as running back, but his longer legs make him more vulnerable to good tackles. He'll be nearly immune to bad tackles, but if his ankles touch he'll go down
* (+) He'll make an excellent short-yardage full back. But that position doesn't see much play, so we'll put him elsewhere most of the time
* (+) Tight ends have to block in many plays. Sims will be very effective at this
* (+) Height is very useful for a tight end - they do lots of quick passes where that extra 4 feet of reach will make it much, much harder to stop him from completing a pass
* (?) it's better to have an imbalance in your favor on offense than defense, since the offense chooses where to play the ball
* (-) aggression is good on defense, but Sims seems dangerously aggressive. We don't want him getting in legal trouble, and putting him on offense limits his opportunities to intentionally hurt people
Sims is going to need to learn three plays in order to take advantage of his amazing standing reach (12 feet) and stride (1.2 yards walking, 3.5 yards running.) I believe that Sims can be taught these plays within a month, even not knowing a common language.
Don't worry about teaching him trick plays, just make sure he realizes that he won't always get the ball.
* BLOCK = hit the two guys in front of you hard and push them back until you hear a whistle
* TWO-STEP = take two steps forward, then turn and have hands high to catch the ball. If you get the ball, fall backwards (forward direction, but facing backwards.) If you don't get the ball, run to either side and be ready for a pass.
* THREE-STEP POST = take two steps forward, turn a bit inside, then take a step at an angle and keep moving forward with hands high to catch the ball. If you get the ball, charge for the end zone.
Sims needs a mostly regular team, although his QB will have to be very patient to deal with the communications issues. Sims will also need an off-the-field handler, since you can't afford him to get into fights and you really don't want sexual assault allegations (true or false.) Over time, Sims will allow you to save money on offensive players, particularly the blocker or two right next to Sims.
Training should focus on catching the ball, holding onto the ball, and speed drills, since turnovers are Sims' biggest weakness and speed will be extra useful if he can develop it.
Sims will be an enormous advantage, making any team in the league a playoff contender by default. It doesn't guarantee victory, since a high-powered enemy offense might be able to keep up with the help of a few turnovers.
Once you get multiple Sims, you should put a few more on offense, but start going with defense. A full defensive line of Sims will be nearly impossible to block against, and they'll be the only defense in the league that regularly leads in sacks without ever blitzing.
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He could potentially make a good **tight end**, if you can teach him to catch well. Fast enough to be a receiver, and his height gives him tremendous advantage vs. defenders. And he can clearly do some blocking when needed. If you look at the players who typically play that position, they often fit that mold - taller and bigger than wide receivers. For example, Jason Witten or Rob Gronkowski.
He might, though, have more of an advantage in basketball.
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The previous answers provide the best conventional wisdom for what to do with a very large individual given current NFL offensive and defensive schemes. I don't know if that conventional wisdom scales all the way up to this individual's size, though.
At this size and strength, especially since you specify proper proportions, it is doubtful that Sims can be tackled by any single individual player of "normal" NFL size. The foot speed you list would be slow for a running back, but a running back who can't be tackled by less than three men doesn't need to be fast. If I had such a player, I'd at least *try* him at running back; hand him the ball and dare the other team to tackle him.
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Special teams when it comes to short yardage.
If the ball is on the one yard line, have him play running back and just bulldoze his way through. Hell, he could just *reach* over the defensive line and break the plane, above their heads. The mere threat of him would force the defense to pile on all their guys to try and stop him, which would tend to leave the receivers open for easy passing plays.
On the defensive side, get him somewhere near the middle and that jump over the scrum to get into the endzone play? Not going to work if it's near him. And if his reflexes aren't bad, you're talking about one hell of a kick blocker.
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> His 40 yard dash is 5 seconds
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Offensive lineman or defensive tackle. Conceivably quarterback. From [Wikipedia](https://en.wikipedia.org/wiki/40-yard_dash#Average_time_by_position):
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> ```
> Quarterback 4.93
> Defensive tackle 5.06
> Center 5.30
> Offensive tackle 5.32
> Offensive guard 5.36
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Of those five, offensive guard is generally considered the least skilled and quarterback the most. In order, perhaps guard, defensive tackle, offensive tackle, center, and quarterback. In general, the left side of the offensive line is more skilled than the right side, as they usually protect the blind side of a right handed quarterback. So I would focus on right guard or defensive tackle. He may also play fullback in short yardage situations (like Refrigerator Perry).
Height is most useful to quarterbacks, wide receivers, and tight ends. It allows quarterbacks to see over other players and allows receivers (including tight ends) to reach over defenders. He's too slow to play tight end or wide receiver.
It's going to take time to train someone in the family to play quarterback and it may simply be impossible. There have been any number of athletically gifted players who never managed to play quarterback at NFL standards.
My thoughts are that this might be more of a gimmick than a winning strategy. Good NFL players tend to have eight years of experience in high school and college ball. I'm not sure that he can go straight from the farm to the field and perform at a high level.
His best chance might be at defensive tackle. He won't be blocking his team's quarterback's view playing on defense. The job of a defensive tackle is relatively straightforward. Add a top middle linebacker behind him to compensate for his mistakes. But the rest of the family can't play defensive tackle. There are only two on the field at a time in a 4-3 defense. A nickel package might have three. A 3-4 only has one.
The Sims family's height might make them more dominant at basketball. But that too has skill requirements that they might not be able to meet, particularly with their limited experience.
Sheer size is most valuable in sumo wrestling. It's also useful in WWE wrestling. The scripted nature of professional wrestling allows for much less skill than free form sports.
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Wikipedia actually has an [article listing height](https://en.wikipedia.org/wiki/Height_in_sports) in sports and what roles each sport get advantages from above average and below average heights.
Gridiron Football (aka American Football, to differentiate between Association Football (Soccer) and Australian Rules Football (insanity, aka [Calvinball](https://en.wikipedia.org/wiki/Calvin_and_Hobbes#Calvinball)?).
The Article lists Wide Recievers, Lineman (Defensive or Offensive), and Tight Ends as the positions most advantaged by height. Quarterbacks, Defensive Backs, and especially running backs (where 6'0" and up is rare) are best given to shorter players. The Wikipedia article gives the reasons why.
Because the NBA was mentioned, I will point out that the NBA actually has an honesty in size problem. Here the average height is 6'7" and it's not uncommon to lie about heights, and not for the reasons you might think. Charles Barkley was officially listed as 6'6", but is more likely measured at 6'4"-6'5 1/2" and even if he was 6'6", he was still considered short for his position (Power Forward). Conversely, Kevin Durant's official NBA height is 6'9" even though he's really closer to 7'0". This is because his listed size is closer to his best position (Small Forward) where as above that people will only call you a Power Forward (Yeah, the same role Barkley played). And reporters are very careful to report the listed heights as opposed to actual height as players are very territorial about that number.... it can cost them a good position if misreported in either direction. So you may have a 9'0" giant, but he's really 9'6" because it sells better... shush!
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Genies can be trapped in a lamp for long periods of time, maybe hundreds or thousands of years. They are made of vapour so this doesn't inconvenience them much. Whilst in the lamp they don't have a human form but they can hear speech (and therefore summoning spells) and can feel someone rubbing the lamp. It is dark inside the lamp.
There is nothing else in the lamp apart from the genie's vaporous self.
Genies have great powers to grant wishes and in fact they can grant themselves three (and only three) wishes during the whole of their existence.
**Notes**
Genies are constrained by a Higher Power to remain genies until the Final Day. They must stay in the lamp at all times except when summoned. When summoned they must emerge and grant the summoner three wishes then return to the lamp. The summoner can require all three wishes at the same time or at different times.
Genies cannot countermand any restrictions imposed by the Higher Power.
The Genie only has three wishes for itself in total yet it may be summoned many times by different people over the centuries and millennia. Outside conditions may change drastically so they need to choose wisely.
Genies can only grant wishes including their own whilst *outside* the lamp.
**Question**
The Genie's (unavoidable) task is to grant *as many wishes as possible* but also to be as tricky as possible about it so that wishes are, if possible, granted in an undesirable way the summoner hasn't thought of. One of the paradoxes of this is that the genie must grant its **own** wishes in the least favourable way! I need to know what the wishes should be but also *what unfavourable outcomes could come from these wishes* and *how the genie can avoid tricking itself*.
What should the genie wish for?
[Answer]
The genie has no personal desires, beyond the need to grant as many wishes as possible. Hence the wishes must push the genie towards being as good at its job as it possibly can. I also sense a hint of chaotic neutral about its instructions.
1. **The lamp should never be out of the physical possession of a potential user for more than a decade.**
The genie isn't going to be granting wishes if the lamp is lost at the bottom of the sea for a millennium, it has to be found and rubbed for wishes to be granted. A person who has used all their wishes is no longer a potential user, this timer starts as soon as the third wish is granted. The most likely problem with this is that one person wishes for immortality and attempts to hoard the lamp forever, and so we come to:
2. **The lamp should never remain in the possession of any single controller for more than a year.**
People have a terrible tendency to hold off on that last wish until needed, that stops other people from getting control and wishing their own wishes. This timer starts as soon as the new owner first takes control of the lamp, even if it's casually thrown in a bag with other loot and never used.
The lamp needs to move around. It's going to get a lot of people killed if they're not willing to give up the lamp. The genie doesn't care about that, the genie wants new people to grant wishes to and as such the lamp must change hands by any means.
The greatest risk to the genie is that it's passed around endlessly but never rubbed, but then, if you've had it for a year and never rubbed it, what are the chances you're going to start now? Move it along and maybe a servant will polish it as it sits on a shelf.
3. **Reserved for undoing the damage caused by the other two wishes**
Because that's one of the rules of wishes, the last wish is always to undo the damage.
All time periods subject to adjustment for plot purposes.
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Being able to perceive outside the lamp, possibly even globally would be extremely useful for getting the most out of a) their remaining wishes and b) the wishes of their summoner (whether maliciously or benevolently)
Being able to affect things outside the lamp, whether perhaps environmental conditions, or tampering with the minds of passerby, etc could all also be potentially attractive, depending on the personality of the genie.
Having another entity for companionship, or the ability to communicate back and forth with other entrapped genies would appeal to some individuals (probably most if they are humanlike in personality)
The ability to record their thoughts somehow for posterity might appeal to some.
Ultimately what a genie wishes for is going to depend hugely on their personal preferences and desires. Maybe some would want a garden inside their lamp...
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One Wish will be enough, if it grants the Genie the capability to talk the lamp users into anything the genie wants. In this case, the Genie will have infinite wishes by talking the humans into wishing anything the Genie wants and giving the lamp to the next victim ..ehm .. user when the wishes are done.
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1) I want to become the eternal, immortal, omniscient ruler of the universe
2) My bottle should expand and contain the entire universe
3) I want to be able to make as many wishes I want
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I think a genie would want additional capabilities.
I would think a genei would want to be able to view the world around them or knowledge of what has happened while they are stuck in the lamp. So some sort of magical knowledge to let them predict events as they happen or some sort of remote viewing ability so they can watch events happening while they are in the lamp.
I also think they would want some control over how they are used or who finds them so maybe an ability to make the lamp change shape or appearance so they could try and hide if they wanted.
And I don't think a genie would ever use its final wish. Because once it has it has no more options to change anything or any control over its destiny. I would think a genie would value the option of being able to grant a wish for itself more than anything it could ever wish for.
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In my fictional world I would like to have something similar to modern optical sensors for things such as aiming systems, night-vision goggles and automaton vision.
The main problem I face is developing an interface between optics and the algorithms to evaluate them.
In modern technology one would have an optical sensor, consisting of multiple components that produce an electrical signal representing the vision. This electrical representation can then be fed into a *'black box that figures it all out'*.
In my world however electric circuits are effectively non-existent due to a lack of research and expertise, while mechanical computation (similar to the [Analytical Engine](https://en.wikipedia.org/wiki/Analytical_Engine)) has successfully been miniaturised and optimised to be small, fast and complex enough to support an effective AI-ruler with a mere dozen cathedral-sized halls filled with calculation banks and stores.
The size or cost of the contraptions required is not important.
The usage of biological components (such as real eyes or well-trained dogs) could be begrudgingly accepted, as long as the systems result in a mechanical output.
*PS: The things I would like to use this for are (with real-life examples in brackets):*
* *Vision enhancement (night/infrared vision)*
* *Vision replacement (prosthetic eyes)*
* *Auto-focus (self-adjusting binoculars)*
* *Image analysis (colour recognition)*
* *Object recognition (facial recognition)*
* *Object tracking (self-aiming turrets)*
[Answer]
Let's have some fun with this. Now, disclaimer, I'm going to utterly ignore vision replacement, image analysis, and object recognition because I frankly don't believe there's a path from here to there. Hopefully smarter people than I can come up with a believable solution for those, but I can't.
*And the idea of putting a key in your prosthetic eye to wind a spring... and then the awful tinnitus you'd experience from the whirring machinery... and your vision would jiggle...*
The rest, I believe, is just a matter of creative chemistry.
**Light enhancement** When I lived in New Mexico, I had a friend in the military who explained the night vision (infrared) goggles he was using. He was no engineer, and so couldn't explain the chemistry involved, but the goggles were *entirely passive.* They acted as both enhancers and discriminators. The goggles were multi-layered. Some layers filtered out the ambient "we don't want to see that" light while others shifted the frequency of the "light we want to see" into the visible spectrum. Were they as useful/good/efficient as powered goggles? Absolutely not! But they worked....
There are a number of [light-sensitive chemicals](https://en.wikipedia.org/wiki/Category:Light-sensitive_chemicals) in the world. If you had a thin enough layer of a sensitive-enough chemical, it would be believable that the layer would illuminate somewhat like the electron-sensitive cathode-ray tubes of yesteryear (the electrons would impact on phosphorous and make it glow). If you had an initial layer that acted as a [collimator](https://en.wikipedia.org/wiki/Collimator) to focus the light into narrow patches of that sensitive layer, then you'd get crude "dots." If you consider this, there are fluorescent collimators used for overhead lighting. They are covers, divided into grids, and often laminated with a lightly reflective material. The result is light focused more directly downward while blocking acute-angle observation of the source. (Granted, applying the word "collimator" to that description is a bit of a flourish... but it works.)
So, no sensor required for light enhancement.
**Object tracking** is a bit more complex, but not impossible. Unfortunately, you're in a mechanical and chemical world, which means you have no way to create a reference of your target in software. But, what you could do is use some refracting mirrors that reflect the image "seen" by the turrent onto what at the moment we'll call a piece of paper. You can do this with simple optics and [artists have been doing it for a honking long time](http://www.beginnersschool.com/2014/03/21/quick-and-dirty-tricks-for-getting-your-image-onto-canvas/). There are actually "projectors" that people use to do this very thing — but I can't find a link with a quick Google search because projectors have become such a ubiquitous part of our lives they overwhelm the search. I haven't used one since grade school, cumbersome beasties.
Anyway, once you have the image someplace useful, we're back to chemistry. There is no way on earth that you can process 3D imagery using Victorian tech. Therefore, we're working with blobs, and the goal is to keep the blob in the center of the aiming reticle.
Here's where I wish I was a chemical engineer. Think of the old silver oxide photographic tech. You're going to get light and dark images. so, rather than having a piece of photo paper, you have some of that light-sensitive chemical in a grid where the piece of paper once resided. And below it, something that reacts to the presence of the light-sensitive chemical, only it's blocked by half. (hold your breath...) once someone screams "Mark!", the gunner shifts a lever that allows these chemicals to start "tracking."
What's really happening is that as the ratio of light-vs-dark changes on the half-plate below the gridded top-plate, the chemical reaction pulls or pushes (an incredibly light) lever, which trips gears to cause forward/reverse rotation. They'll jiggle back and forth with the shift in the light/dark pattern and, basically (and very roughly) hold the reticle "on target."
***OBVIOUSLY*** there are tremendous real-life weaknesses with this.
* The lever will be feather light, meaning you have a cascade of gears to get to the point where you can rotate a turrent. Considering you're bouncing around in a tank (I assume), the odds of this feather light contraption remaining calibrated (or even operational) are perishing awful.
* The chemical-to-metal reaction that causes the metal to gently flex is most likely corrosive. You'll be replacing the lever frequently.
* Fluids slosh...
* IMHO, there is nowhere near enough tech to actually recognize a pattern. Thus, as you move around the battlefield, the light behind the target may change, forcing the gunner to regularly "reset" the system.
The problem with actual patten matching is that every time you change your angle of approach to the target, you're changing the reference image. In other words, you can't simply use a cutout as the reference. That would only work if the two of you were standing still — and you wouldn't need target tracking for that.
Last, but not least, is **auto-focus.** This one might actually be the simplest of the three... at least until you need to convert the results to mechanical action. There are several ways to achieve [passive autofocus](https://en.wikipedia.org/wiki/Autofocus#Phase_detection). I think the one that will work best is *phase detection.* We want to use a couple of pinholes (like the old artists used to capture an image to pain, earlier link).
[](https://i.stack.imgur.com/tXYnn.png)
Image care of the earlier Wiki link. Simplifying this something awful, you're trying to get only one glowing dot on your light-sensitive chemical, not two. But, think of it this way, if you have two small pools of chemical separated by a very thin barrier such that when you're in focus *there is no dot,* then all we need is a simple auger gear to move the focusing lense back and forth until the dot is gone. And that brings us back to the featherlight lever that warps with the chemical as the chemical reacts to light that I described for the turret.
**But what about my computers?**
OK, I'm having a bit of trouble working in the difference engines because I know what they are and how they work. They are NOT direct replacements for modern computers. Not by any stretch of the imagination. Did you ever see the movie *[Hidden Figures](https://en.wikipedia.org/wiki/Hidden_Figures)?* That big-old honking IBM was basically a difference engine running ballistic math problems, and look at its size and complexity *just to read punch cards.* If you want a better example, watch *[The Imitation Game](https://en.wikipedia.org/wiki/The_Imitation_Game).* Yeah, that big brick of an object running on a bazzilion electric motors that was parametrically programmable but not *actually* programmable? That's a modern babbage engine. Today a single microchip is many orders of magnitude more powerful — and we need multiple cores for decent image recognition. I, personally, can't choke down treating babbage engines as actual computers. They were large and complicated adding machines. Basically cash registers. Sorry. But that's why I haven't described how to create "software" for difference engines that would make your steampunk story look a bit more modern.
**Conclusion**
I think a believable set of solutions for the three desired outcomes I mention are obtainable. You'd need an actual Chem-E to work out the details — *and it would be dog-slow and fragile!* but it would work.
And once you have a believable solution, it's only a process of glass-blowing and a bit of handwaving to create working scenarios.
[Answer]
As far as I understand, you are quite out of luck with optical sensors in the Victorian era.
# General overview
* Photography and precursors is too slow.
* Biohorror has trouble coupling with mechanical response mechanisms and is not stylish enough.
* You *can* have very early and crude television efforts with tubes and mechanical scanlines. But...
* You might have more luck with a radar. You'd basically need huge tubes, ask the British in WW2.
So, tubes are probably our best bet.
# Tubes
The problem with tubes in the Victorian era is that tubes are pretty much hardcore hightech. (Semiconductors are even more hightech, search for the purity of silicium for P- and N-doping.)
You'd need:
* Some quite hard obtainable metals and rare earths. These alone mean decades on geological research and hardships of industrial production. How would you extract, say, wolfram in large quantities, if you have nothing that would reach its melting temperature outside from very exoctic labs?
* Vacuum. Vacuum tubes need (surprise) vacuum, of a quite high stage for that time. A lot of work on pumps, ingenious tricks on burning up the remainder oxygen inside the tube need to be discovered.
* Displays. Yeah, you radar display screen is a big-ass tube. But it's hard to fabricate and finding a proper luminophore is not easy.
* Power source. You'd need quite some electrical power. Where are the generators?
* Tube-based electronics needs some capacitors and a lot of transformers. Transformer steel is not that hard to produce as, say, cathodes, but still.
* Theoretical foundations need to be developed, starting from [Thermionic emission](https://en.wikipedia.org/wiki/Thermionic_emission).
My verdict: It's so far from then-current state of the art, so esoteric, and so resource-hungry that you'd fail to convince anyone to invest money in such a project.
[Answer]
**Light creates heat. Heat can be measured mechanically**
It's just hard.
Consider, for example, the Crookes radiometer - one side of the little spinner is painted black, the other left shiny - it spins when you put it in sunlight.
<https://en.m.wikipedia.org/wiki/Crookes_radiometer>
There's also the Nichols radiometer, which uses a tiny silver mirror to measure the force exerted by light.
This requires extraordinary miniaturization, but we're already supposing this for the sake of the story.
Nanoscale rods with tiny silver mirrors could be hooked up to tiny gears that transfer photon collisions to the tiniest amount of mechanical rotation. And, if you build an array of them, you have something that you can use to see. It's not easy, but neither was the invention of the digital camera.
It'd be hard to use, vulnerable to vibrations, needing a load of balancing and compensation mechanisms, but you could do it
Once you have this level of miniaturization, though, other things get easier. Night vision? Well, your device is exquisitely sensitive to vibrations outside of it's shell. Why not use it to sense the vibration caused by creatures or humans walking?
Perfect for hooking up a turret. Having the turret understand a passphrase is comparatively laughably trivial
[Answer]
<https://www.forgottenfutures.com/game/ff9/babbage.htm>
>
> At least one "eye": Patented in 1885 by Flez Biological Mechanisms of Switzerland (Flez Biomechanische Technik AG), the standard Flez eye consists of a lens in front of a 20x20 grid of 400 "elements", each a dissected insect eye connected via its optic nerve to a small piece of muscular tissue. Light makes the muscle contract and (via a series of gears) extend a small metal rod. A scanning mechanism feels the pins and reports their positions to the "brain". This can be done eight times a second. The insect eyes, muscles, and nerves are bathed in a nutrient fluid which keeps them alive for up to a year, but can be damaged by excessive heat or cold. The basic "eye" costs £5. A model offering colour vision (via a rotating colour filter wheel) is available but costs £10 and slows updating of vision to twice a second. A model with three grids and fixed colour filters costs £20, and gives colour vision refreshing eight times a second, but the triple-lensed design looks very odd and cannot be used for models imitating humans. All models must be refilled with nutrient saline every week, at a cost of a few pence, and the eye elements must be refurbished by a Flez main dealer at intervals of six months to a year. Refurbishment of all models costs 20% of the cost of the eye. The illustrations above show the basic mechanism and an automaton's-eye view of the same illustration.
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> Recognition
> Q: How does an automaton recognise someone?
> A: With great difficulty
> Since automaton sight is so limited, they can rarely recognise anything more complex than the outline of a human, and can easily be fooled by something that distorts or imitates the human form. This means that the basic visual process must be augmented by other means if it is essntial for the automaton to distingush between one person and another; for example, if an automaton sentry is to distinguish friend and foe. Sound (such as a password) is one possibility, others include insignia with distinctive light and dark patterns, flashing lights, and magnetic tokens. Recognition methods are often closely-guarded secrets; for example, the British mechanical soldier "Automaton Atkins" (see below) obviously has some means of recognising fellow soldiers, possibly by their uniforms or some token concealed in it, but the exact method has never been publicised.If an automaton is being run as a player character it probably isn't a good idea to emphasise this problem too much. See below for more on automatons as player characters.
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[Answer]
## pigeon guided bombs were a thing.
trained pigeons are your sensor and they peck at a target image which moves the screen creating a mechanical input. [link to a video](https://www.google.com/imgres?imgurl=https%3A%2F%2Fi.ytimg.com%2Fvi%2FmnKyOfNuSoo%2Fsddefault.jpg&imgrefurl=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DmnKyOfNuSoo&tbnid=2uth1w9Ahr0zwM&vet=12ahUKEwippNvtlZ79AhV4BGIAHcHqCL4QMygJegUIARDXAQ..i&docid=g2HbaaaB4hsdkM&w=640&h=480&q=pigeon%20guided%20bomb&ved=2ahUKEwippNvtlZ79AhV4BGIAHcHqCL4QMygJegUIARDXAQ) about how they worked. The sensor for the movement of the screen by pecks was electrical but they could be made entirely mechanical..
[](https://i.stack.imgur.com/ykYEU.png)
you can also use photovoltaic materials,
[Answer]
>
> Vision enhancement (night/infrared vision)
>
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>
2 ways for this:
1. Phosphors convert normally non visible light into visible light, (preferrably infrared. )
2. Having a wide "catching area" for light like wide telescopes reducing down the image to some eyepiece would ensure that you got the image, with more photons caught.
both assumes people with already outstanding vision are operating these.
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> Vision replacement (prosthetic eyes)
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I have little clue for this one outside that if a surgeon could somehow integrate a fine mosaic of materials with photoelectric properties with the nervous system and have the brain do the heavy lifting of seeing again?
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> Auto-focus (self-adjusting binoculars)
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Pigeons. This is going to be a common answer from me. Training pigeons to only peck when the image is clear for a reward allows for a pigeon to focusing interface that slowly adjusts the focusing lens in a looping fashion and would stop when it is pecked. bino's would be out of the question.
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> Image analysis (colour recognition)
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An array of pigeons. having light be filtered through filters of varying colors and a set of pigeons trained on a reference color could mean that incoming light could be split up by filters (or by prism) and when the pigeon sees their respective color, they peck. The data could be recorded. This assumes that unfocused light passes through. images may mess with pigeons.
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> Object recognition (facial recognition)
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Pigeon pecks button when seeing face.
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> Object tracking (self-aiming turrets)
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BF skinner bomb mechanism. See [John's answer](https://worldbuilding.stackexchange.com/a/242236/82834) regarding this. Most pigeon ideas are based off of this answer.
As for how the pigeon interfaces can directly influence some of these mechanisms, I was thinking that the pigeons (exactly like in bf skinner's bomb) are fitted with electric contacts that energize relays (1830's invention) that trigger DC motors (also 1830's invention) that either operate a punch card machine ( for tabulating data) or directly moves the aforementioned turret
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[Question]
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There's been a few questions about making big bugs before and the consensus in they can't get much bigger than 3ft or so (which in reality is still huge). Catch is, you need quite a bit of extra oxygen to do it which doesn't bode well if someone wants to throw people into the mix...
So,just how big *can* I make my bugs by cranking up the O2 before either they can't get enough oxygen or my humans drop dead from O2 poisoning? Is there some 'happy medium' where people can survive well while still having dragon flies the size of shoes flying around? (25% O2? 35%, 50%?)
[](https://i.stack.imgur.com/EMdoO.jpg)
*Where's your gas mask Nigel?* (<http://prehistoric-park.wikia.com/wiki/Meganeura>)
[Answer]
The answer is simple: have insects that have evolved a different respiratory system.
At some point during Earth's history no animals had lungs, and then many clades developed different forms of those. Even among the hexapods, evolution is still ongoing: insects' tracheas are and advancement compared to the [springtails'](https://en.wikipedia.org/wiki/Springtail) porous cuticle system.
A lung is a tightly folded, highly vascularized trachea by another name. It's the way biology found to flip the bird at math and its square-cube law. In a fictional world, it's no stretch to have insects develop something between what they have here and what we have.
[Answer]
**I don't think the main issue is oxygen (for either species). Food is the limiting factor.**
There are [puppy sized spiders](https://www.livescience.com/48340-goliath-birdeater-surprises-scientist.html) on earth now. If you go back to the pre-historic era, there are even [larger insects](https://askabiologist.asu.edu/explore/prehistoric-insects). I'm assuming your main concern with oxygen is that most insects breathe through holes in their skin called tracheae. Tracheae evolve as the species evolve (just like humans evolved lungs).
The limiting factor will be food and competition for it. [Over-fishing and over-hunting](https://adventure.howstuffworks.com/outdoor-activities/fishing/fish-conservation/responsible-fishing/alaska-fishing.htm) are well-documented problems that most governments solve with quotas. The world isn't over-run with lions because large creatures that have to run fast to catch food expend MUCH more energy than slower, smaller creatures. Being a big, fast creature means you can starve faster.
[Answer]
As far as giant dragonflies go, it's not so much the amount of oxygen in the air, as it is a higher atmospheric pressure which allows them to fly. You can compare this to light planes needing a much shorter takeoff roll at sea level than at my ~5000 ft home field. Or for a similar case, I was once given a battery powered toy helicopter (early version of a drone) that flew perfectly well in near sea level Silicon Valley, but wouldn't stay up at my home.
WRT oxygen concentration, it's not so much the percentage of oxygen in the atmosphere as it is the partial pressure. So you can increase the O2 percentage at low pressures and be fine, as for instance when people in unpressurized airplanes use oxygen masks at high altitude. Likewise, when you increase the pressure, as with scuba diving, you have a higher partial pressure of O2 even though the percentage hasn't changed.
People can survive extended periods of breathing air at several times atmospheric pressure. Any scuba diver who spends time at 32 ft/10 m depth experiences twice the sea level O2 concentrations. People have lived for weeks in undersea habitats at several times sea level pressure, e.g. <https://en.wikipedia.org/wiki/SEALAB_(US_Navy)> So humans shouldn't have any problems coexisting with giant dragonflies.
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[Question]
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I am a post-human adapted for permanent life in vacuum and micro-gravity. How might my physiology and biochemistry overcome the following challenges?
*Please note I have a strong cultural aversion to augmenting my body in order to help me survive: i.e. enclosing myself in artificially-constructed protective shells, etc.*
**[See Part 1 on radiation resistance](https://worldbuilding.stackexchange.com/questions/129268/what-does-the-physiology-and-biochemistry-of-a-vacuum-adapted-post-human-look-li?noredirect=1#comment402303_129268)**
**Part 2 Temperature control:** Space is cold, but vacuum is also highly insulating. How do I stop myself from both freezing and overheating?
**[See Part 3 on metabolism](https://worldbuilding.stackexchange.com/q/129400/56294)**
[**See part 4 on movement**](https://worldbuilding.stackexchange.com/q/129468/56294)
**[See part 5 on senses](https://worldbuilding.stackexchange.com/q/129647/56294)**
[Answer]
As you pointed out, space is cold and insulating.
You cannot rely on matter to exchange heat, this rules out conduction (you don't like shells) and convection.
What remains is radiation: your body will emit thermal radiation and lose power according to Stefan Boltzmann law, $I=\epsilon \sigma T^4$.
Since you want to keep this lost power low and not freeze, you can only work on $\epsilon$, your emissivity. The lower you make it, the less radiative power you will emit.
Basically your skin has to be pigmented in a proper way so that its emissivity can be as close as possible to 0, but not 0, else you will boil up.
You also want to be able to control this emissivity, for those cases when you want to emit excess heat and cool down.
You can refer to [this table](https://en.wikipedia.org/wiki/Emissivity#Emissivities_of_common_surfaces) for the emissivity of some common materials.
[Answer]
# Nothing needed
You just need to keep things as they are and keep your people hydrated. Oh, and compressed.
See research on [Space Activity Suit](https://en.m.wikipedia.org/wiki/Space_activity_suit):
>
> Cooling of the astronaut with an SAS is generally achieved with evaporation from body perspiration which is emitted from the suit in all directions.
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That's scientific way to say that **he would sweat**. And that's it.
---
Because space suit designs discuss cooling at great lengths, and heating rarely if ever, I believe it's safe to assume that freezing is not a real problem, overheating is.
[Answer]
Temperature control in this case depends on 4 factors: generation per kg of body. Amount of kg of body. Surface area to radiate heat off. How well the surface area generates heat radiation.
The ISS does not have a problem heating up. It in fact needs specific area's on the hull where heat is radiated away or the inhabitants would be cooked. In space astronauts wear both undergarments to cool themselves and layers to keep heat in, while the gloves have specific heating elements to keep the hands warm. So I have no idea if humans would lose heat or gain heat in space (if they survived).
These post-humans live in a vacuüm and travel interstellar distances, so they are likely to have a low metabolism and low heat generation. This means they are better off with more mass compared to surface area so they would need to be bigger to accomplish this. Their skin or outer shell would need to be of materials that have little heat radiation. In case of heating up due to sunlight or similar the skin sould have extendable hairs made of heat radiative materials, the hairs having a large surface area when extended and allowing more heat to dissipate.
[Answer]
How about bioluminescence?
According to the source below, bioluminescence is a 'cold' light, meaning only 20% of the energy produced is thermal radiation. Not ideal, but cover enough of your body in bioluminscent cells and you have a solid method for controlling your emissivity. You can also use it for communication in the void.
<https://www.nationalgeographic.org/encyclopedia/bioluminescence/>
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[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 question stems from watching a scene from ID2 and seeing the massive alien mothership landing/crashing on the North Atlantic.
What mass would a starship, or any other artificial object constructed in low earth orbit, need to be to start to create noticeable gravitational disturbances for the planet or spatial object it is orbiting?
By 'noticeable', I mean something like higher tides that can clearly be linked to the object in orbit or a slight shift in the orbit of the planet. Not something that only some precise instrument can measure and that scientists can determine through mathematical formulae. Something that would have the leaders of the planet think that it is time to get the construct away.
Is there a general rule, like 'at 10% of the mass of the planet', or does it vary depending upon what you are orbiting? Ie '10% the mass of a planet but 25% the mass of a G-type star'?
[Answer]
Assuming an object in lunar orbit 10% of the mass of the moon, or 7.342×1021kg, will cause a 5% variance of total [tidal amplitude](https://en.wikipedia.org/wiki/Tide#Amplitude_and_cycle_time), a difference of some 55mm overall. That will definitely be broadly noticeable, to anyone looking at tide gauges at least, rather than only being noted by scientists who study those effects in detail. For an object in [LEO](https://en.wikipedia.org/wiki/Low_Earth_orbit), where we are more likely to be building, for ease of access, that number will be considerable smaller.
[Newton's Law of Universal Gravitation](https://en.wikipedia.org/wiki/Newton%27s_law_of_universal_gravitation) states that:
F=G(m1m2)/r2
We can rearrange to solve for m2 at a given amount of gravitational influence, F. F for an object 10% the size of the moon, in lunar orbit, is 1.9x1019[N](https://en.wikipedia.org/wiki/Newton_(unit)) so for an object only 2042km away (in Low Earth Orbit) we get a mass of 2x1017kg or a little more than the mass of Saturn's moon [Prometheus](https://en.wikipedia.org/wiki/Prometheus_(moon)).
Apparently the above is nonsense, thanks AlexP, sorry it took a while to get back to this but the formula I should have been using is [Tidal Force](https://en.wikipedia.org/wiki/Tidal_force) and *not* general gravitation. So using that new formula we get a rather different, and more correct outcome:
Tidal effect of an object in lunar orbit of 10% the mass of the moon is actually only 6.6x1017N so an object in Low Earth Orbit would need to be 1.1x1015kg, approximately equivalent to 1.4x1011m3 of construction steel.
[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.
I suspect the answer is somewhat different from Ash's, in part because the required effects are still not well-defined.
First, what exactly is "low earth orbit"? [A common definition](https://en.wikipedia.org/wiki/Low_Earth_orbit) is low enough to produce more than 11.25 orbits per day, which works out to 1269 miles altitude for a circular orbit. Let's call it 1000 miles or less just for convenience.
It's well-known that for a uniform spherical body of uniform density the surface gravity is proportional to the radius. An orbiting body (presumably spherical) at 1000 miles altitude cannot have a radius greater than 1000 miles, and if it has the same density as earth, its surface gravity will be just about 1/4 g. Then the effective gravity directly beneath it will be 0.75 g. This would noticeable, alright, but I'm not entirely sure how objectionable it would be. It would also not have a simple effect on tides. On the one hand, tidal patterns are complex and non-intuitive, as the way the water sloshes around the planet is profoundly affected by the coastal and sea-bed conformations. On the other, an LEO satellite moves *fast*, by definition at least 12 times faster than the tidal cycle. I'm simply not up to calculating the effect on the tides, but it wouldn't be simple.
Nor can the satellite have a simple effect on the atmosphere. The air underneath it will tend to expand upwards, but since that point is moving at about Mach 3 there won't be much in the way of a "dragging" phenomenon.
Also note that making the satellite smaller really reduces effects. Cutting the diameter by a factor of two, to 1000 miles, reduces the mass by a factor of 8, and the gravity differential as it passes overhead drops to 3%.
Of course, at these scales Roche's Limit *does* rear its ugly head. While it's important to realize that structural materials such as steel are far better in tension than rock is (and it's tension rather than compression that counts here), the scale of the forces involved probably makes this a minor factor. But all of that is (or can be) pretty much moot. If the satellite is built to the proper shape, and its spin adjusted to make it effectively tidal-locked from the git-go, it will already be in the minimum-energy conformation and will not be affected.
Actually, I suspect that the most important immediate effect that would trigger a response is its effect on other satellites. Even a fairly small object would grossly distort all orbital dynamics for any other LEO satellites and would make such orbits unstable. This would probably extend to destabilizing geosync satellites as well, so we'd lose both communication satellites and things like GPS.
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[Question]
[
This is the first of possibly several posts about the following scenario, in which Earth's sea-level rises 2 km overnight, generating a world map looking like this:
[](https://i.stack.imgur.com/SkFEd.png)
**Question:** What would be the climate after 30 years?
*Would temperatures (and ice-sheets) rise, fall, or be redistributed somehow? What would trade winds and ocean currents be like: are there areas where the surviving landmasses are significant enough to generate gyres? I imagine storms will become more powerful, but when and where will they be concentrated?*
* I'm specifically interested in the area around the west of the main Tibetan landmass and the islands which used to be Iran.
* There is some potentially helpful info [here](https://www.reddit.com/r/askscience/comments/1djbmu/what_would_weather_patterns_on_an_ocean_planet_be/), though it addresses fully ocean planets and the results are inconclusive.
* I'm a humanities student, please try to avoid jargon if possible.
* I do not have set ideas about the average temperature or salinity of the new water, so please feel free to either assume that this is the same as that already present on Earth (average 5 degrees centigrade).
* Don't worry about how the water arrives on Earth; this takes place through a non-scientific process. Simply assume that it happened, and 30 years later, what are the consequences?
[Answer]
Your proposed planet would essentially be a water planet, despite the small amounts of land still found on the surface. As such, we can make a few simplifying assumptions and work with some best-guess scenarios.
## Air currents
Air currents are greatly simplified by this change. Rather than navigating complex topography, the surface of the Earth has been dramatically smoothed as it follows the ocean surface, which in turn follows the [geoid](https://en.wikipedia.org/wiki/Geoid). As such, the air currents will follow the idealized atmospheric cell circulation shown below (if this is confusing, check out my answer [here](https://worldbuilding.stackexchange.com/questions/112038/the-worlds-a-jungle-again-would-doldrums-blow-the-global-air/112254#112254) for a more detailed explanation of why these patterns form):
[](https://i.stack.imgur.com/YrcPnm.png)
The equator is still going to be the warmest area, as it's receiving the most solar radiation per square meter. Most of the evaporation will happen here, and the [ITCZ](https://en.wikipedia.org/wiki/Intertropical_Convergence_Zone) will remain intact but will actually align nearly-perfectly with the equator, rather than being deflected to the north as it is in today's Earth.
The atmospheric cells will radiate from there, following idealized Hadley and Ferrel models. As pointed out by the Reddit link you found, the jet streams will grow a bit stronger because they no longer need to meander quite as much. You can check out what the jet stream is doing today at [this cool website](https://earth.nullschool.net/#current/wind/isobaric/250hPa/orthographic=184.46,5.11,364). They'll still run into the Himalayan Plateau and the Andes, but those will each be easier to avoid.
The winds across the planet will probably get stronger, leading to more powerful storms and more destruction when they do run into the remaining land. There's an article [here](https://rmets.onlinelibrary.wiley.com/doi/abs/10.1002/qj.498) that argues it won't be *that* large of a change, but this has been disputed by other papers.
The monsoon season would be largely minimized. Monsoons are caused by the movement of the ITCZ, which would be significantly weakened for the same reasons described above. Without a strong ITCZ, the monsoons will likely be insignificant.
## Ocean currents
The oceanic currents are a bit more complex and we don't have as clear of an idea what will happen with them. [Some papers](http://paoc.mit.edu/paoc/papers/aqua.pdf) find that the Earth becomes latitudinally stratified, with ice caps reaching down much further and the equator becoming warmer. [Other papers](https://journals.ametsoc.org/doi/pdf/10.1175/JCLI3874.1) find that the ocean takes over where the atmosphere fails and succeeds at transporting huge amounts of heat between the equator and the poles, leading to less a less-stratified planet that's more homogeneous temperature-wise.
The gyres themselves would largely dissipate - there's no continental mass to deflect them, so the currents would continue in their normal direction and would wrap around the planet.
## Atmosphere composition
I'm not certain on this one, but it also seems likely that the increased ocean surface area will dramatically increase the amount of water in the atmosphere. Because water is a significant greenhouse gas, this will cause an increase in longwave radiation absorption and an increase in the global temperature. This could lead to a runaway greenhouse effect like L. Dutch points out in his answer.
## Energy balance
Finally, the [albedo](https://en.wikipedia.org/wiki/Albedo) of the ocean is much less than the albedo of land. This means that less incoming radiation would be reflected and more would be absorbed. Extrapolating from [this site](http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/Earthebal.html), the Earth's energy budget would increase by about 25 watts per square meter, or maybe 3% of the current amount. This would also contribute to a warmer planet and more greenhouse-like effects.
[Answer]
**Water cycle**
I don't think the other answers so far have discussed the effect on the water cycle in great enough length, so here goes.
There will be no problem with lack of rain. Even areas that were previously snowy mountaintops will now have a tropical climate. As other answers have pointed out, the water vapor will significantly increase temperature, which means a ton of water going into the atmosphere as water vapor, which will cause a ton of rain. I suspect that humans will be able to deal with the rain and humidity, but the temperature poses a threat to humans if it becomes a positive feedback cycle with the water vapor.
In this scenario, I am imagining that the water entering the ocean is salt or brackish water, or that its salt concentration is not low enough to make the oceans drinkable.
The major problem in this scenario is getting fresh water. The areas on the map that are above water have small land areas and are stretched out. That means there won't be many freshwater lakes or streams. Most of the aquifers are under water too, and there aren't many (if any) aquifers on mountains. This seriously affects the feasibility of humans being able to live with such high water levels. If humans have the resources, though, they will build rain-catching devices to provide their water. Without fresh water, humans will quickly perish of dehydration.
[Answer]
As hinted by AlexP in their comment, any object of extraterrestrial origin brings along a lot of kinetic energy.
This would result in the added water to boil off, resulting in the atmosphere being saturated with water vapor.
Water vapor is a greenhouse gas way more effective than CO2 at blocking IR radiation, therefore the immediate result would be turning the planet into a sauna. At that point it's very likely there would be a second hell-like planet a la Venus orbiting the Sun.
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[Question]
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Suppose a person, standing at sea level, could use telekinesis to exert a force around a sphere with a 10 cm diameter so that it becomes one-way permeable to air. As time goes on, the sphere becomes more and more filled with air and therefore hotter, more dense, and exerts pressure outwards.
How much force would the person have to use on that sphere:
1. to keep the air in there?
2. for that air to turn into a plasma or for it to cause a fusion explosion?
Bonus questions:
1. How much time would it take?
2. What would it look like?
To be clear, I need an answer in Newtons or a similar unit to compare against other forces in my story.
[Answer]
**You Need the Core of a Star, Preferably a large one**
Our atmosphere is comprised of primarily nitrogen, oxygen, carbon monoxide, and faint traces of noble gasses. The amount of energy to fuse these elements is only found within the hearts of stars. Most small star's fusion cycles do not incorporate these elements except fairly large ones, so I'm not really sure you can measure said pressure in newtons. Especially since the amount of energy required to fuse an element is not measured in newtons of pressure but electron volts.
[Answer]
>
> How much force would the person have to use on that sphere:
>
>
> 1. to keep the air in there?
>
>
>
That would keep increasing as more atoms diffused into your sphere. (Remember that standard atmospheric pressure is 1.03 kg/cm2, and your sphere has a surface area of 314.16 cm2.
Just *doubling* the air pressure would require this many Newtons:
```
2 * 1.03 * 314.16 * 9.8 = 6,324
```
>
> 2. for that air to turn into a plasma or for it to cause a fusion explosion?
>
>
>
As mentioned by @TCAT117, the same pressure exerted by the core of a large star.
>
> Bonus questions:
>
>
> How much time would it take?
>
>
>
Depends on how permeable the sphere is. A *long* time, though.
>
> What would it look like?
>
>
>
A few thousand of Tsar Bomba.[](https://i.stack.imgur.com/iD1v7.jpg)
[Answer]
**There won't be any fusion and it won't get hot. Apart from building up a pressure of approximately 100 atmospheres nothing will happen.**
In physics we have the concept of the [*mean free path (MFP)*](https://en.wikipedia.org/wiki/Mean_free_path#Mean_free_path_in_kinetic_theory) which means how far a molecule/particle can travel until it collides with another particle. We normally know that this path cannot be lowered anymore because the air liquifies at this point (the molecules begin to stick together).
For air the MFP is 68 nanometers and given that the molecules have a "size" (it is a bit more complex than that) of approximately 1 nanometer, you can estimate that molecules cannot enter anymore at pressure of approximately 68 atmospheres. Room temperature is far too high to liquify air, so what you have is a [supercritical liquid](https://en.wikipedia.org/wiki/Supercritical_fluid) which is indistinguishable from gas, but has the same density as liquid.
So what happens is once your sphere is full, incoming molecules will be prevented from enter because there is no space anymore. No fusion, nothing.
[Answer]
>
> How much force would the person have to use on that sphere:
>
>
> 1.to keep the air in there?
>
>
>
I'm not sure force is the right way to conceptualize this one. If it is a 1 way permeable membrane somehow only made up of energy I think it is more reasonable to think of it as a different dimension than a physical container. If it were a physical container there would be relationship related to the pressure difference between its inside and outside and it would cease being permeable when the inside was greater than the outside. However, if you considered it more like a 4th dimensional rift then it sounds a bit more plausible simply because we know less about how that would actually work.
>
> 2.for that air to turn into a plasma or for it to cause a fusion explosion?
>
>
>
Fusion and plasma are different. Fusion is when an atom gains atomic mass in the form of a proton thereby releasing energy. Plasma is a highly energetic state of matter.
Hydrogen, being the smallest atom, is the easiest to fuse which drives the majority of stars specifically the smallest. The higher in mass you go down the periodic table, the more energy is required to fuse elements. Elements like Nitrogen (7) and Oxygen (8) form at end of life of small stars and are more prevalent in mid size stars. [To fuse oxygen](http://jtgnew.sjrdesign.net/stars_fusion.html) requires temperatures of 1 billion Kelvin or 3.299999e+8ºN. I provided the link so you can look up the requirements for fusing air. Off the top of my head air is roughly 70% Nitrogen, ~20% oxygen, and then various other gases.
>
> Bonus questions:
> 1.How much time would it take?
>
>
>
Time is relative, however long it takes you to capture the amount of mass you want and raise it to the right temperature and pressure. This is very much based on the limitations of your magical system.
>
> 2.What would it look like?
>
>
>
Since a 4th dimensional rift has never been found, there is no knowing how it would react with physics as we know it. Though if light and energy are allowed to escape the sphere then I would expect it to appear much like a star, most likely igniting the atmosphere or in the very least burning every onlooker with ultraviolet radiation.
[Answer]
I think that the process could be improved by making the sphere permeable only to some compounds or elements.
Maybe the psychic person could heat and energize the air around the sphere and split up the molecules of elements and compounds in the air into separate atoms, and make the hydrogen atoms from water vapor the only atoms that can penetrate the sphere. So there will be a gradual build up of hydrogen inside the sphere, until hydrogen is by far the most common element inside the sphere, and oxygen, nitrogen, carbon dioxide, argon, etc. are only traces.
The free hydrogen that doesn't go into the sphere will react with oxygen and burn, producing heat and water vapor. There should be a very impressive zone of fire and glowing hot air around the sphere, and possibly an impressive zone of fire and devastation on the ground below and around the sphere. The psychic person might get caught in the fire and killed, ending the process.
I suggest that the upper limit of the density within the sphere would soon be reached because the atoms within the sphere would repel any atoms crossing through the permeable sphere. Thus the sphere wouldn't fill up with hydrogen enough to fuse.
Therefore, I suggest a more complicated course of action involving enlarging and shrinking the sphere and changing how permeable it is.
First, create a vast sphere in the air, and make it totally impermeable to molecules, atoms, and ions. Then shrink the sphere to a fraction of its former volume, thus multiplying the density and temperature of the air inside it.Then make the sphere permeable from the inside to the outside. Almost all the super hot air will rush out of the sphere, burning everything around it, and making the interior of the sphere almost a vacuum.
Then make the surface of the sphere impermeable and enlarge it again, making the vacuum inside even thinner. And when the sphere is greatly enlarged, make it permeable only from the outside in, and let only hydrogen in. Then heat up a vast volume of air around the sphere, so that molecules break down into atoms and ions. Only hydrogen atoms can pass through the surface of the sphere into the vacuum inside.
Some of the hydrogen atoms will remain outside the sphere and combine with oxygen. There should be a very impressive zone of fire and glowing hot air around the sphere, and possibly an impressive zone of fire and devastation on the ground below and around the sphere. The psychic person might get caught in the fire and killed, ending the process.
So the almost vacuum within the sphere will fill up with hydrogen atoms until they become so dense that they repeal all hydrogen atoms from entering the sphere. Then rapidly shrink the diameter of the sphere , thus increasing the temperature and pressure, until eventually the temperature and pressure is enough for an instant massive fusion reaction, a hydrogen bomb.
Or maybe stop the shrinking at the exact moment that a slower fusion reaction starts and use it as a power source.
I haven't done any calculations but it would take an immense amount of energy for all the heating up of outside air and all the compression of the size of the sphere.
And I assumed from your question that it would be done using psychic powers, so presumably the psychic person would be magically drawing energy from some unspecified outside source.
Or they could be using a highly advance science and some vast technological machines to do it.
[Answer]
Your first problem is that you'd be mainly trying to fuse Nitrogen not Hydrogen. This only happens in latter stages of nucleosynthesis and requires immense pressure.. I believe it would be the pressure required to cause electron degeneracy. You should investigate the 'Chandrasekhar limit'. You might even be able to work that in somehow. Your next problem is that a ball of degenerate matter that large would probably require the whole atmosphere. One teaspoon of the stuff weighs the same as Everest.
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I want to create an earth-like planet with massive aurora, visible during the day, and from the equator. How would I go about doing this? Do I increase the strength of the planet's electromagnetic field, increase the amount of stellar wind, or both? If these are the solution, how do I create a stronger field, or increase the amount of wind?
[Answer]
Here's the basics:
>
> When the charged particles from the sun strike atoms and molecules in Earth’s atmosphere, they excite those atoms, causing them to light up.
>
>
> What does it mean for an atom to be excited? Atoms consist of a central nucleus and a surrounding cloud of electrons encircling the nucleus in an orbit. When charged particles from the sun strike atoms in Earth’s atmosphere, electrons move to higher-energy orbits, further away from the nucleus. Then when an electron moves back to a lower-energy orbit, it releases a particle of light or photon. ([Source](http://earthsky.org/earth/what-causes-the-aurora-borealis-or-northern-lights))
>
>
>
Now, everything comes with a cost. There isn't a way to get more lights without a consequence. In reality, those lights represent something kinda bad: energy we don't want getting into the atmosphere. So:
The magnetosphere channels the charged particles. A stronger field means the northern lights are pushed even further north (because it channels the particles to the axis of the field). So...
1. A weaker magnetic field will bring the lights further south and strengthen the lights further north, at the cost of exposing the north (and south) poles to greater radiation.
The atmosphere is receiving the charged particles and becoming excited to a higher energy state. When they release the energy and fall back to a lower energy state, that release comes in the form of a *photon.* Thus, more atmosphere at higher altitudes will produce more auroras.
2. Thicken the atmosphere. Earth has something like 90% of its atmosphere in the first 10Km, the remaining 10% is between 10Km and 300Km. Let's lower the gravity just a bit, increase the foilage a lot, increase neon an the other fluorescing atoms a bit, and we'll get more light higher up. However, this will increase air pressure at sea level and decrease the value of the air to breathability. The world becomes a bit uncomfortable to live on.
Now, for this last bit, I'm going to defer to our astrophysicist experts and give you just a summary. The solar wind is made up of a lot of stuff, and not all of it will cause aurora. We specifically want the *negatively* charged stuff. So it's not really more volume we need ("more solar wind"), but a higher density of what makes life really cool near the poles. And here's where I'm going to get this whole thing wrong (if I haven't already): I believe what we want is a cooler, larger, bluer sun. (If I got that wrong, PLEASE correct me in comments!)
3. We want a sun that produces more of the charged particles that cause aurora. However, this will affect the nature of life on your world.
[Answer]
During the [Carrington event](https://en.wikipedia.org/wiki/Solar_storm_of_1859) in 1859 auroras were brighter and visible way closer to the Equator than they normally do.
>
> Auroras were seen around the world, those in the northern hemisphere as far south as the Caribbean; those over the Rocky Mountains in the U.S. were so bright that the glow woke gold miners, who began preparing breakfast because they thought it was morning. People in the northeastern United States could read a newspaper by the aurora's light. The aurora was visible as far from the poles as south-central Mexico, Queensland, Cuba, Hawaii, southern Japan and China, and even at lower latitudes very close to the equator, such as in Colombia.
>
>
>
So, based on the above I would say that a more active star would help you in achieving your goal. Whether that will also be life friendly or not is another topic.
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While only counting seasons and years, but not weeks or months, how far can human civilization progress?
Can they reach the middle ages?
Or is the invention of the calendar such a cornerstone of civilization that it is inevitable for it to exist?
[Answer]
### As far as you like, the calendar is not that important.
It also depends on what counts as a calendar!
The reason the constellations tend to not look anything like a description of their names, without an awful lot of artistic liberty being taken, is they were actually used as a calender to indicate *upcoming events on Earth*. Aries the Ram is basically a triangle, but in ancient times indicated something about sheep herding (I think it was the time to mate sheep; let the Ram loose).
Similarly for harvest time, monsoons and other seasonal things. Time could easily be measured by full-moon to full-moon, and corrected by very reliable constellations, without ever worrying about days.
If by "calendar" you mean a day-by-day calendar, I don't think that is really necessary at all, not even in modern times. We currently celebrate various holidays like Easter, Thanksgiving, Mother's Day, etc on different days of the year all the time, without this causing any hassle. The days we pick are culturally determined, but could just as easily be fixed to various celestial or natural events that may vary year to year.
You really don't even need a clock; other than sunrise and sunset. Even much industrial work and schooling could easily be by quota. Finish your 1000 pieces and you can go home. Things that require teamwork could be timed relative to sunrise, noon, and sunset; all of which people are trained to recognize. You show up at sunrise, work together until X is done, then go home. Likewise, the idea of weekends and days off is a recent development; it certainly isn't a requirement for an advanced society. Many professionals like doctors and lawyers and authors will work 7 days a week and take time off in bigger chunks; they don't need more than the phases of the moon for timing: The moon is around three quarters, I'll return when it is full.
An obsessions with the calendar and making specific days for specific purposes is an artifact of our culture, not something absolutely necessary for an advanced society. Most actual inventors of technology were not on a schedule to invent something, they were on an open schedule, fooling around with ideas as they came to them, and one day came across something interesting. Edison, famously, had no idea how long it would take to find a good filament substance for the light bulb.
That is what technology is based upon, not strict schedules at all, by clock or calendar.
[Answer]
Shorter periods are very handy for early economies: Calculating rent, taxes, water distribution, installment payments, interest periods and the like without requiring everybody involved to be skilled at multiplication.
Shorter periods can also be handy for common understandings of non-work days, worship frequency, market days, and other common uses so that everybody need not carry a stone-tablet calendar around with them to achieve common understandings.
The precision required for useful astronomy to accurately determine seasons and years is exactly the same precision required to determine shorter periods.
[Answer]
Besides what @user535773 said, even hunter-gatherers need timekeeping more finely grained than seasons. For example, some plants flower in early spring, others in late spring; some fruits are ready in the early fall, and others in late fall. Ditto migrating animals, the start of the rainy season, etc.
But mainly agriculture needs finer divisions within seasons.
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We are in a world similar to our current world (with the same technology level notably), but there is a huge catch: everything is considered as property, including human beings. Every human child is born as state property, and will be sold later at an age between 10 and 30 depending mainly on their educational success. People obtaining the certificate of eligibility for self-ownership can buy themselves from the state before they are sold, and become self-owners, human beings that aren't the property of anyone else. Only the "best" 1% of the population can have that certificate.
Property (the official name given to human beings that aren't self-owners) can have different status depending on what their owner decides:
* no status: in that case they don't have any freedom, they can't own anything to their name and are forced to obey any order from their owner (as long as it doesn't violate their dignity or integrity). However, unlike the two other status, the owner has an obligation to keep the property alive and relatively healthy.
* self-administration: in that case they don't have to obey direct orders from their owner and may "own" things to their name but they can't move to a place or sign contracts without the approval of their owner. They can't either have voting rights or leadership position in companies.
* freedom: in that case they have the rights of self-administration without the restrictions. They still cannot do things reserved to self-owners however.
The owner may downgrade the status at any time for any reason. Upgrading the status requires that the property passed the required certificate of eligibility (roughly 70-80% of people are eligible for freedom) and can only be done with their consent. The property having a status can always ask to be reverted to having no status and this request cannot be refused.
Self-owners are the only persons allowed to vote and be eligible at elections, to own human property (along with juridical persons owned and led by self-owners), to be able to do very sensitive jobs, etc. [Note: although the possession of other human beings ("human property") is reserved to self-owners, human property can "own" other things if they have at least the self-administration status]
Owners cannot kill their human property. However, if they don't want of them anymore and no other owner wants of them, the state will kill the property. This disposition combined with the obligation of owners to "keep alive and healthy" (essentially housing and feeding) property means that homelessness is almost non-existent. (Self-owners having lost all their money can still be homeless.)
Property who are working for the state (the army, law enforcement, civil service, teachers) are owned by the state and automatically granted the highest status they can pretend to, as such working for the state is prestigious and sought after. It doesn't pay very well however.
Other property are either owned by individual self-owners or corporations. Very highly skilled people tend to be bought by big companies and be granted certificates of freedom and high pay (as long as they work there), unskilled people are usually bought by huge factories to perform harsh, unpaid work with no status.
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Would a consumerist system like our current one be viable when there are people who cannot own anything? What would be the necessary adaptations of the market?
[Answer]
The economy would be surprisingly similar to our current one, although far less efficient.
We make a big deal about our efforts to reform ourselves as an enlightened society and purge the evils of slavery from our midst; we applaud people like William Wilbourforce, Abraham Lincoln and many other quiet reformers who effectively abolished slavery in England, USA and other developed nations. But, these people really got rid of something that was on the way out anyway, for a very simple reason;
It's expensive.
Owning a slave in a regulated environment may *sound* cheaper than employing people to work farms and cotton gins and the like, but the truth is anything but. In a regulated environment, you have to provide a minimum standard of housing, good quality food, medical care, etc. This all means that you end up with a small army of skilled slaves or employees working as carpenters, cooks, doctors, and many other professions just to keep your core body of workers going.
On the other hand, if you simply free them and then offer them work, *they* have to find and pay for their own homes, food and medical care on their own time.
Ironically, this is why the worst thing to happen to the treatment of slaves (especially during transport from Africa on boats) during that era in the USA was the Emancipation Proclamation. As soon as Lincoln declared slavery illegal, he effectively (by virtue of that declaration) repealed every regulation around the treatment of slaves which made their treatment subject to only one consideration, namely the profit margin.
Even more ironically, it's happening again. Modern employees (especially of large corporations) get all manner of sick and personal leave, medical plans, superannuation, etc. It's becoming more and more expensive for corporations to 'own' employees. The solution? Casualisation. More contract and freelance offerings, less permanent positions. Back to paying the 'employee' for what they do, and leaving the employee to pay for all their own support structures.
Your model does exactly the same thing, but with the ratio you describe does it on steroids and actually makes the single most ubiquitous instrument in modern economies almost impossible to wield;
Public Companies.
If only 1% of your population can own anything, that means that your stock market almost can't exist. I don't know the exact figures, but much of a modern stock market is fuelled by 'Mom & Pop' investors. In Australia, it's worse. A lot of the stock market is actually fuelled by superannuation funds investing the common workers' super holdings for their retirement.
How can you drive an economy without multiple people investing in a single idea, raising capital across the breadth of the economy? The problem with your model is that 1% is too small a population base to find those investors with the same vision you have, or who believe in your vision enough to put money into it. That means that in turn, many companies wouldn't exist, many products and services we take for granted today wouldn't exist, and research and development would be less likely to be funded as well.
To be specific against your question, where possible companies would much rather 'hire' people instead of 'owning' them because of the financial and administrative overhead. Always. Owning someone makes you responsible for them in a way that any business would rather not have to accept. Consumerism would 'sort of' work because people still consume; the difference is that most goods would now be sold in bulk because you have 1% of the buyers all buying 100x the goods they personally need.
In some ways, this would look very much like a Communist (or at least a Socialist) state. Communism isn't a form of government per se; it's an economic model in which all property is essentially owned by the state. In practice, this means that major assets are controlled by committees that represent the state. (Democracy and Communism are not opposites; Communism/Capitalism and Democracy/Authoritarianism are both opposite pairs)
In your world, the self-owned effectively become the economic equivalents of State officials who manage economic assets on behalf of the masses. This is not as efficient as it sounds and there's no inducement to contribute to such a model other than patriotism or altruism, or possibly through fear of reprisals from a lack of participation.
So; your model would put much control into the hands of a few. This would limit market flexibility, curb research and development, and limit production to practical goods that are needed for the common good. Ultimately your economy isn't going to last because there's no incentive for individuals to provide extra effort beyond supporting exactly that.
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In my fantasy universe, dwarves use a tactic that involves using a lot of catapults and ballistas mounted on carts that look like Polish/Cossack tabor or Hussite war wagon, which are parked behind the lines and shooting at enemy. What I am interested in, is if it's possible for such weapon systems to be effective in medieval field battle, because I know they were rarely used in that role.
On the weapons performance: Ballistas launch 0.5 - 1 kg projectiles, in form of bolts and solid rocks or metal balls, for 400 meters, catapults are a bit harder to define, but let's say the range is about 200 meters and projectiles are rocks and weight is 5-10 kg. Assume fire rate to be 3 rpm for ballistas and 1 rpm for catapults. I am also thinking if it's viable to make canister shot for these weapons, what do you think?
Edit: sources for the pictures
<http://wattsunique.com/blog/orsova-ballista-project-progress-report-2/>
<https://myarmoury.com/feature_armies_poles.html>
[Answer]
**Yes. The origin of both weapons is as field weapons.**
Here is this question from the Ancient History stack.
<https://history.stackexchange.com/questions/25744/are-there-any-examples-of-balistas-scorpions-or-other-catapult-like-weapons-be?utm_medium=organic&utm_source=google_rich_qa&utm_campaign=google_rich_qa>
Wikipedia here describes the [scorpio](https://en.wikipedia.org/wiki/Scorpio_(weapon)) which was a small ballista or heavy stationary crossbow.
>
> During the Roman Republic and early empire, sixty scorpions per legion
> was the standard, or one for every centuria. The scorpio had mainly
> two functions in a legion. In precision shooting, it was a weapon of
> marksmanship capable of cutting down any foe within a distance of 100
> meters. During the siege of Avaricum in the war against the Gauls,
> Julius Caesar describes the terrifying precision of the scorpio.[2] In
> parabolic shooting, the range is greater, with distances up to 400
> meters, and the firing rate is higher (3 to 4 shots per minute). With
> precision shooting the rate of fire was significantly less.
>
>
> Scorpions were typically used in an artillery battery at the top of a
> hill or other high ground, the side of which was protected by the main
> body of the legion. In this case, there are sixty scorpions present
> which can fire up to 240 bolts per minute at the enemy army. The
> weight and speed of a bolt was sufficient to pierce enemy shields,
> usually also wounding the enemy so struck.
>
>
>
That sounds like a good field weapon. The Greek [polybolos](https://en.wikipedia.org/wiki/Polybolos) was a repeating ballista with a bolt magazine and chain drive. Sort of an ancient gatling gun.
Alexander used catapults / ballista in field battles and was himself wounded by what sounds like a ballista bolt that went through his shield and body armor.
An account of field weaponry of this sort used against cavalry:
from <http://warfarehistorynetwork.com/daily/military-history/the-catapult-and-other-war-machines-of-ancient-greece/>
>
> In 329 bc swarms of Scythian horse archers opposed Alexander’s
> crossing of the wide, swift river Jaxartes (Syr-Darya, in Kazahkstan):
> “… the catapults, at the word of command, opened up on the Scythians
> who were riding along the edge of the water on the further side. Some
> of them were hit; one was pierced through both shield and breastplate
> and fell dead from his horse. The Scythians were taken completely
> aback by the long range of the catapults, and that, together with the
> loss of a good man, induced them to withdraw a short distance from the
> river ….”
>
>
>
One would think Greek fire thrown from a catapult would make for good shock and awe vs massed troops but my quick search did not turn up any references to the Byzantines making war like this. If anyone can find something, edit it in.
[Answer]
The rate of fire for siege weapons is not high enough for attacking mass troops. A fast cavalry charge could overrun a bank of ballistas. English longbows could shoot down charging horses because a large group of English bowmen could send up a cloud of arrows fast enough and far enough to stop a charge.
<https://www.historic-uk.com/HistoryUK/HistoryofEngland/The-Longbow/>
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Would it be possible to have a cold and remote polar region if the oceans are made of fire? By that, I mean that in the place of water, there exists lava.
[Answer]
Considering Earth as a template planet, probably not.
If the seas of your planet are [molten lava](https://en.wikipedia.org/wiki/Lava), their temperatures would be in the 700-1200 °C. Let's assume 850 °C as an average. That is hotter than the mean surface temperature of [Venus](https://en.wikipedia.org/wiki/Venus). Since lava usually contains greenhouse gases, your planet would be probably be a Venus on steroids, and its temperature would be the same anywhere.
Even if your planet didn't start out with an atmosphere (so as to maintain a separate temperature on landmasses not covered by magma), the magma itself would release gases that would make an atmosphere over geological time.
Now "cold" is relative, but the poles of that planet would not be "cold" to us.
[Answer]
I don't think so.
Back when Earth looked something like this:
[](https://i.stack.imgur.com/2yKK8.jpg)](https://i.stack.imgur.com/2yKK8.jpg)
there'd be no possibility for anything like a cold polar region. In those times, the atmospheric temperatures were something like [2000̊ C](https://www.climate.gov/news-features/climate-qa/whats-hottest-earths-ever-been). Not really conducive to nippy polar conditions!
[Answer]
Several times in Earth's history, there have been flood basalt eruptions that covered large areas with lava. From memory, one of them occurred in Siberia. I don't see any reason why they couldn't occur over the poles.
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I'd like to keep this as science based as possible. I'm not even sure if this sort of question fits this exchange. Is there a possible world wide affect that when triggered (by human/cosmological initiative) would make most if not all humans go nocturnal?
The effect on other creatures, plants and species preferred to be as minimal as possible. A few hundred species and some crops going extinct wouldn't matter. But if mass extinction can't be helped, well, we can explore how humans can adapt to that too.The technological level before this sudden change would be as of present.
If there could be some cultural/sociological/political change that can bring about the transfer from a diurnal to a nocturnal life, the incentives for such a change can be explored too. This would give the advantage of staying away from damaging existing global ecosystems and substance cycles.
I'm hoping that proposed changes would have humans and the new global ecosystem survive for eons rather than being on a timer till doom (like the case of our sun going missing), and something permanent, something we cannot fix within at least a century.
[Answer]
**It is too hot during the day.**
This already happens in tropical countries where it is unpleasantly hot in daytime. People come out at night.
[](https://i.stack.imgur.com/dhaYp.jpg)
<https://www.telegraph.co.uk/travel/picturegalleries/8308524/Singapores-best-hawker-centres.html?image=2>
This does not require a lot of imagination. Even in temperate countries with hot summers, people hide inside in the heat of the day then come out to socialize in the cool night.
The thing which could make this happen everywhere is a dearth of power. You can stay diurnal in Phoenix because of air conditioning. If there is not air conditioning and there is sweltering heat, people would sleep in cool basements in the day and come out at night. Plants that could handle the heat would do fine.
[Answer]
For some reason all humans turn allergic to direct sunlight. Only a few humans have this now, but you could research what makes it happen and turn it into something wide spread.
Religion/ Cultural reasons. Wether it is a new prophet or fake news being widespread. something is saying sunlight is bad and we should avoid it at all costs. When enough people change to nocturnal, others will start to change to it as well out of neccesity. (Opening hours of work, shops, social events, ...) but this would not happen overnight.
A new species comes to existance. (We made it, crashed alien zoo ship with space lions on board, ...). This is a highly efficient predator and very dangerous and hard to kill. However, it is only active in direct sunlight. You could tweak this to your needs until it turns out that it is safer and more cost efficient to change to a nocturnal schedule than to try and combat this species. Although I think humans would rather fight it.
Another thing I thought of, but is probably not very scientific, is a sort of epidemic that makes almost all humans sick. There does not need to be a high death toll or anything, but those who got ill and recovered, ended up with very sensitive eyes. When light hurts the majority of the population, such a switch would happen natural.
[Answer]
A massive infection which has the effect of leaving the infected humans with [porphyria](https://en.wikipedia.org/wiki/Porphyria) like symptoms.
Some kinds of porphyria make the skin extremely sensitive to sun light, with exposure resulting in pain, swelling and bleeding. More than enough to avoid exposure to daylight and seek refuge in the night.
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I'm trying to build a world that is orbiting a red giant but sustains life similarly to the conditions of earth.Since red giants are about half the temperature (3000 kelvin) of our sun (6000 kelvin) life could not be sustained, at least not to the same extent.
(I'm trying to keep the surface temperature about 20-60° Celsius)
Since red giants are about half the temperature of our sun, if it was half the distance away from the planet would the temperatures be the same?
Assuming it's solar mass was 0.5 that of our sun as well, would there be an increase in gravity or would the planet be able to orbit normally with no adverse affects?
The closer proximity seems as though it would cancel out the lack of temperature, and the halving of mass would furthermore cancel out the increased gravity of the closer proximity.
[Answer]
It is not the surface temperature of a star, or not the surface temperature alone, that determines the distance that habitable planets orbit at.
The surface temperature determines how much energy the star emits per unit of surface area. The total surface area of the star multiplied by how much energy is emitted per unit of surface area gives the total energy emitted by the star.
If Star A emits four times as much energy as star B, a planet would have to orbit Star A at twice the distance as a planet orbiting star B in order to receive the same amount of energy.
A red giant star would not be dimmer than the Sun. Red Giant stars have very large surface areas and thus emit many times as much total energy as the Sun.
Furthermore, the red giant phase is a relatively temporary phase in the life cycle of a star, and a planet that is at the right temperature for life to flourish on it while the star is a red giant will not remain at the right temperature for long enough for the life to develop interesting features.
You might want to make your planet orbit a dim red dwarf star instead of a vast red giant star.
The different aspects of stars do not have linear relationships but instead have geometric relationships. For example, a one percent change in the mass of a star will cause much more than a one percent change in the diameter, surface temperature, and total luminosity of the star.
Here are some links to sites that calculate the habitable zones of stars:
<https://www.google.com/search?newwindow=1&q=habitable+zone+calculator&sa=X&ved=0ahUKEwjKsfe7oPDZAhXvYd8KHYInAU4Q1QII8QEoAQ&biw=1920&bih=949>[1](https://www.google.com/search?newwindow=1&q=habitable%20zone%20calculator&sa=X&ved=0ahUKEwjKsfe7oPDZAhXvYd8KHYInAU4Q1QII8QEoAQ&biw=1920&bih=949)
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[Question]
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I have the tables explaining time dilation for a single ship at different relativistic speeds, but am unsure how to modify that to work out for two ships at different velocities, and the two different dilation effects:
I have two spacecraft travelling together at relativistic speeds, say 70%c. One, ship A, accelerates to 99.5%c or so, so that time dilation was more dramatic for them. Fuel and shielding are not a problem. These guys are good at gravity manipulation so acceleration not a problem.
If it finds a problem and turns back to rejoin ship B, how much further ahead from ship B (which is moving the same direction but slower) could it have gone if 100 years passed on ship B? How much time (from their point of view) passed on ship A?
The story is all about the travelers, so no outside non-relativistic observers.
I have two story points to cover:
a) A mother and son are on the different ships. When the mother returns, the son is very old.
b) Ship A finds something ahead which needs to be avoided - so how far ahead that is could affect the story and time left to avoid the problem after ship A returns with the bad news.
Any pointers would be appreciated, thanks!
[Answer]
You haven't provided enough information to complete the calculations, because distance is an issue. Let's have some fun anyway.
*Oh, wait, the info's there after all. Sorry!*
I like [this site](http://www.emc2-explained.info/Dilation-Calc/#.WqGxQudG19M), which gives you several calculators, including one that tells you how much time is compressed given your speed relative to light.
So, we have two ships both travelling at 0.7c. the relative speed between them is zero, so they're experiencing time wasting away at the same rate. But that's not a useful point of reference. If we're standing on a planet thinking about them, on the other hand, they'd be experiencing time at about 71% of the rate experienced by us.
Now, one of the ships needs to deal with a problem ahead, so it accelerates to 0.995c. Let's assume magic occured and it accelerated instantly. Suddenly, it's experiencing time at 10% the rate of the planet.
**So, from the perspective of the planet, it would seem that if ship A is experiencing time at 10% and ship B is experiencing time at 71%, so ship B should be aging at 7X the rate of ship A — from the perspective of the planet.**
But all this is moot unless enough ~~time~~ distance has passed to make a difference. How far ahead is this issue? How long was the 0.995c round trip?
*Duh, you said Ship B spent 100 years. So, 100/7 = 14.29 years at 0.995c.*
*NOTE: The website I reference makes a point that's important. Light, traveling at 1.0c, experiences 100% time dilation, which means no matter where it started from, it (the photon) thinks it arrived at its destination instantly. Despite the fact that it (the photon) would have experienced a [loss of energy, however small, over the distance it travelled](https://van.physics.illinois.edu/qa/listing.php?id=24619). In other words, as Tim B II states, the relationship really is between energy states, not speed, and degeneration may be a whole lot more complicated than the math equating speed with time suggests. In other words, maybe it seemed to you like you only travelled 5 years out of an actual 50, but your body may have lost "50 years" worth of life energy anyway. It would put an interesting spin on the story, and you would join the ranks of authors who have had a lot of fun thinking about how all this manifests over the decades. But, until we can actually push something to relativistic speeds and measure what really happens, we just don't know what will really happen.*
*Heaven help the monkey that makes that first trip....*
[Answer]
Going by real-world physics, this situation is actually quite a bit simpler than it may seem because you only care about the perspective of people on the ships, not the people on the planet (or whatever) they are moving at 70% of light speed with respect to.
Imagine yourself, the "narrator", moving along with ship B. In your reference frame, both ships start out just sitting there at rest. Ship A changes its velocity, i.e. it accelerates up to some speed and flies away, then later it comes back. As long as the acceleration happens quickly, this is *precisely* the classical [twin paradox](https://en.wikipedia.org/wiki/Twin_paradox).
The speed at which ship A winds up moving, in your reference frame (where B stays at rest), can be calculated from [the velocity addition formula](https://en.wikipedia.org/wiki/Velocity-addition_formula):
$$\frac{u - v}{1 + \frac{uv}{c^2}} = \frac{0.995c - 0.7c}{1 - 0.995\times 0.7} = 0.972c$$
This is enough information to figure out the total distance ship A will have traveled, as seen by ship B:
$$0.972c\times 100\ \text{years} = 97.2\ \text{light years}$$
Half of this distance is covered on the way out, and half on the way back, so ship A has gone $48.6\ \mathrm{ly}$ ahead, as seen by ship B.
Furthermore, the time dilation factor a.k.a. [Lorentz factor](https://en.wikipedia.org/wiki/Lorentz_factor) corresponding to this speed is
$$\gamma = \frac{1}{\sqrt{1 - \frac{v^2}{c^2}}} = \frac{1}{\sqrt{1 - 0.972^2}} = 4.26$$
which means that, if the ships meet again when $100\ \text{years}$ have passed for ship B, the amount of time that will have passed on ship A is $\frac{100\ \text{years}}{4.26} = 23.5\ \text{years}$. For your situation, where the mother is on ship A and the son is on ship B, it is entirely realistic that the son will be biologically older than the mother (or honestly, dead, unless you assume a longer-than-average human lifetime) when she gets back.
Of course, you'd also want to know how long ships A and B have left before they run into "the Problem" that ship A found. (Assuming they can't just change course to avoid it... maybe ship B is disabled, and ship A doesn't want to leave it behind for sentimental reasons or some such thing. Doesn't really matter for the calculations.) That really depends on how fast and in which direction the Problem is moving, and by adjusting the velocity of the Problem, you can give them as much or as little time as you want.
But I suspect you meant for the Problem to be at rest in the "planet reference frame", i.e. the same reference frame in which the ships are moving at $0.7c$ to begin with. If that's the case, then consider how this situation looks from ship B:
* There is a Problem out there in space approaching you at $0.7c$.
* Ship A spent 100 years (ship B time) making a round trip to the Problem and back, which means that 50 years (ship B time) have passed since ship A encountered the Problem.
* At the time of that encounter, the Problem was $48.6\ \mathrm{ly}$ (ship B distance) away.
Traveling at $0.7c$, it will take the Problem $\frac{48.6\ \mathrm{ly}}{0.7c} = 69.4\ \text{years}$ after the encounter to reach ship B, of which 50 years have already passed, so they have $19.4\ \text{years}$ left to prepare when ship A returns. And at that time, the Problem will be $0.7c\times 19.4\ \text{years} = 13.6\ \mathrm{ly}$ away.
[Answer]
We start at time 0, A and B are immortals
"A" travels at 99.9999999999999% of c at a point 640 light years away from "B"
B is stationary and observes with special tool allows A observation.
When "A" reaches destination, travels back to B at the same speed.
The distance is dilated to: 0.0000286102294921875 \* 2 light years (about 12 hours!)
The journey time as viewed from B (years) = 640.0000000000006 \* 2 = 1280 years
The journey time as viewed from A (years) = 0.000028610229492187527 \* 2 (about 12 hours!)
When B reaches A back, time 0 where it should be?
1. +1280 years?
or 2. +12 hours?
or 3. +1280 years for A and +12 hours for B?
If 1 is true, 1280 years have also pass for A that felt like 12 hours. So time for A was like watching a movie at fast forward (very fast indeed). Time for B was as we know, 1280 years observing A.
If 2 is true, 12 hours have past for B, as well for A. When A knock B shoulder, B is still watching A travelling. A: Hello i am here. B: No you are not, i observe you travelling. You barely have moved at all. A: No, i go and return. B: No you lie. You are someone else. A: No its me, here is the proof! (some proof) B: Oh its you! Come, lets observe your past together: A and B are now 1280(-12 hours) back to the past of B where they can happily stay and watch it for ... the next 1280 years!
If 3 is true (which is, based at our current knowledge), B has experienced 1280 years and A 12 hours. A starts traveling at a 'standard' 'time' 0 and return at a 'standard' time 1. Where 'standard' a shared common 'time' metric created exclusively for both A and B regardless their frames of reference. 1 unit of common time has elapsed, which was 1280 years for B and 12 hours for A, exactly because time as we know it is relevant when travelling close to the speed of light.
It gets more complicated with velocities c+ and how A and B observe each other. No matter observation though, because at those speeds is not an accurate descriptor, when you separate and join again A and B no matter directions and velocities, as long as velocities reach c at contrast (one stationary and the other 0.9c is equal to both moving away at 0.45c) starting this at some specific spacetime 0 and end it by joining them at a different spacetime 1 where only time changes (spatial x,y,z the same) then the 'time' we know is relevant for both yet the SPACETIME is the same. If they have not going anywhere at the first place then they experience the same time elapsing from spacetime 0 to spacetime1.
[Answer]
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> Fuel and shielding are not a problem. These guys are good at **gravity manipulation**
> so acceleration not a problem.
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It means that you are in a general relativistics field. And all special relativistic equations do not apply. This spaceships "drag" their time-space with them. Even light speed limit does not apply, if can do "gravity manipulation" for accelerations. Yes, you can travel *to past* in those ships!
Time still may and will go at different pace for ships, but it depends mostly on gravity fields applied (their curvature). In general you can use "rule of thumb" - the more acceleration and the smaller size of gravitiy field (and a ship) - the slower crew would getting old.
I am not giving any formula - they are complex and not needed for narative. You may pick up parameters for *any* time difference given in advance, i.e. any you want for your plot. Exactly like it was done in Interstallar movie.
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[Question]
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Piggybacking on this question: [Could soft matter infused with nano or pico sized magnets be used to clump together so that we could create environments with it?](https://worldbuilding.stackexchange.com/questions/106061/could-soft-matter-infused-with-nano-or-pico-sized-magnets-be-used-to-clump-toget?noredirect=1#comment321157_106061)
...So we have a planet that has lower gravity than Earth, low enough for people to float/fly in the sky (so it does have an atmosphere- like Earths), with an ocean that is held together with the use of nano-magnets evenly spread throughout (the ocean covers the planet).
**But how do we keep the place from evaporating into space or freezing over?**
I think that the atmosphere itself will keep it from evaporating, and I think that having it close to the sun will keep it warm so it doesn't freeze (the planet could be somewhere a bit farther out than Earth is to our sun, but not as far as Mars, or maybe it needs to be closer?).
This planet is artificial so we can literally build it anywhere to achieve our results. I like to believe that its placement in the solar system (again assuming a sun like ours) solves the problem, but I might be missing other aspects.
I also accept that the place is probably not stable, but I'm hoping for a scenario that could give us maybe a million years or so before falling apart.
[Answer]
Without something to 1) keep the atmosphere from just floating away (solved by gravity on Earth), and 2) prevent solar wind from stripping away lighter gases (solved by a magnetosphere on Earth), your planet is doomed to an airless, frozen fate.
Handwaving how "nano magnets" would hold water together or why people who can float in the air would want a planet without any solid surfaces, the solution is an artificial shell or envelope to contain the atmosphere. If your gravity is already so low that humans can float around in it, we're talking about a planetoid with negligible mass and size, so constructing such a thing isn't out of the question.
To keep the planet and shell centred and prevent them from drifting and colliding you'll want a number of stanchions anchored to the rocky surface and supporting the shell. These stanchions would also be a logical place to construct entry/exit facilities. Then fill the volume to your desired depth of water and density of atmosphere.
[Answer]
I would suggest
* A Planet with 0.7 Earth masses and 0.85 Earth radii
* surrounded by a transparent Dyson sphere with a CO2 rich atmosphere
* Orbiting a young Type-K white dwarf(no solar wind AND huge magnetosphere to protect from galactic winds)
* with a 3:2 orbital resonance (mercury style) to prevent destruction from tidal forces (the white dwarf has 0.5 Sol masses) and excessive baking of one side of the planet
For the planet decaying to death after a million years or so, I would suggest that after some time, the planets gets fully locked in 1:1 resonance. One side gets baked and the gases there leave local gravity and float towards the dwarf, adding to it's mass and causing a nova explosion.
**But**
I would say that the organisms from your previous question capable of flying and swimming would be impossible, physiologically.
Air flight is dependent on moving large pockets of fluid to move, and a body shape designed for an upward thrust.
Swimming in water doesn't require thrust because buoyancy (which is manipulated in fish using air bladders) and water is **so** dense walking *through* it is tough when in the pool, let alone "flying"(because the organism would have to repurpose their air adaptations for water).
All of the flora on the planet will adapt themselves to max out on either running flying or swimming, because each have their own unique set of challenges with unique solutions and survival of the fittest will chose the ones who excel in one rather than ones who can just do a bit of everything.
Footnote:
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> Penguins are flightless *birds* who can swim in water without air bladders, but they can only swim for short periods, and all the extra fat and insulation for swimming won't carry well into flying.
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[Question]
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Perhaps you have read Margaret Attwood's story ['A Handmaid's Tale'](http://www.sparknotes.com/lit/handmaid/summary/) (spoiler alert- entire plot synopsis)?
I thought a prequil is in order. A story to explain how American society got to that point. But in order for 'A Handmaid's Tale' to be coherent, Canada must remain fully functional.
So here roughly is a sketch of the plot, necessary to understand the scenario behind the nuke detonations, why they are limited, and why they are restricted to only the US. Please understand that it is a completely fictional account, and any similarity to current American politics and any similarity between my antagonist and [Mercer](http://www.cbc.ca/news2/interactives/sh/wex94ODaUs/trump-robert-mercer-billionaire/) is done in a completely fictitious and anecdotal intent. It is in the genre of alternative history, as is Margaret Atwood's novel.
Most major institutional stock trading in the US is now done by computer algorithms. An IT professional (the antagonist) has intensively studied them and has developed a super-algorithm that can predict their decisions, based on current economic and social data. He has set up a huge server and analytical infrastructure in Russia that follows all social and economic trends, that determine the inputs to these stock market algorithms, in order to predict future trends and current buying behavior. Further, he has developed a platform to use social media to alter the social zeitgeist just enough to drive the stock market input factors in the right direction. His idea is not to make money on the stock market, but to make his fortune on the futures market. That is, he bets on a future market trend, then manipulates the trading algorithms to make his prediction a reality. If you have looked at the futures market, you will understand that the gains can be much more enormous than just traditionally buying and selling the stock. Your gains are immensely and dramatically exponentially inflated, if you make the right predictions, with limited initial investment.
He soon becomes a billionaire. But his biggest objective is to manipulate the stock market to super-inflated highs, bet on the futures market, then cause a complete stock market collapse. All through his ability to predict the decisions made by these trader algorithms, and his ability to manipulate the social conditions necessary to influence the algorithm inputs. Subtle changes in buyer and seller behavior, based on social expectations, can be compounded by these algorithms into significant stock market shifts and trends. The value of stocks moves on small numbers being bought and sold, not on the overall total value of all stock. (If all of the stock were put on the market at once, the value would drop. If a few stock are put on the market and sold at a huge price premium, the value of all of the stock goes up. So very carefully placed bids can influence the overall stock market.) The stock market, after all, is purely emotional in nature for the general public. His wealth becomes unimaginable. But this is not his greatest achievement.
In order to succeed with his futures plan, he needs to minimize government intervention and regulation. He needs a financial regulatory climate where his machinations first cannot be detected, and secondly cannot be stopped, but most importantly, he can not be prosecuted (legal bills being so high these days). So he uses his social media and data analytics platform and propaganda machine to instill a government that is so chaotic it is completely dysfunctional and can no longer fulfill its regulatory functions. He makes sure his daughter is the person that makes all senior WH staffing decisions. Cabinet portfolios remain unfilled, the White House is critically under-staffed, and cabinet ministers are installed whose bias is to gut the agency they administer. The Senate and House are so ideologically deadlocked, and the POTUS administration intentionally waffles from extreme position to extreme position so that no effective legislation is passed. The government is put into shutdown for months on end because these waffling positions make it impossible to come up with a workable bill. The swamp is drained and a parking lot is put in its place. Except for one accomplishment. State federal court judges are appointed that will uphold his extreme ideological position, clearing away the last legal obstacle. The only requirement for these lifetime judicial appoints is a track record of gutting federalist control and of having a personal stance supporting white supremacy and sexism. The political position of elected state governors becomes irrelevant.
He is also able to recruit Russian help, so that the main computer programs and database can be run outside of the US, protected by the leader of Russia from American regulatory intervention. He can, of course, offer the Russian administration the one thing they so desperately want - the collapse of the American financial system, in revenge for the American involvement in the collapse of their own,
So, the US government collapses, and the country is driven into an ideological divide. Civil war between the ideological groups becomes inevitable. Civil war with nukes. Except that he is controlling the person with the nuclear codes. Progressive states like California and New York decide to succeed from the union, driven by the collapse of the American economy through policies of protectionism and isolationism. California and New York depend on global trade for their prosperity, and the administration is closing it off.
So the puppet government drops a few nukes on California and New York in warning. Given the insanity of the last American civil war, American lives are irrelevant in an American ideological dispute. At least ten percent of the American population, military and civilian, was killed or injured in that conflagration. Civilian death is inconsequential in US political ideology, given the one-sided gun debate.
Russia threatens to drop nukes on America to stop the insanity, because of course if America nukes itself to death, Russia will be destroyed by the radiation.
So California and New York capitulate, sue for peace (Russia, of course, also calls a truce) and the extreme white supremacist sexist oligarchical government takes full control of the US, exactly as in 'The Handmaid's Tale'.
***TL:DR***
So that leads to my question. I have outlined the *reason* why nukes have been dropped on the US by Americans, and the reasons why it is not all-out Armageddon between world antagonists. It is localized only to the US. It sets up the conditions necessary for 'A Handmaid's Tale' (though I am not sure Margaret had nukes in mind for the suppression of the liberal opposition).
How many nukes could this oligarchical government drop on its own people in a civil war order to suppress liberal opposition, to force capitulation, but also to ensure that Canada was left relatively unscathed, and Russia unthreatened and non-retaliatory?
[Answer]
Based on comments: USA have 6600 nukes. Biggest nuke are W88 with 475 kilotons and B83 with 1.2 megatonnes. Both values pulled from Wikipedia [B83](https://en.wikipedia.org/wiki/B83_nuclear_bomb) and [W88](https://en.wikipedia.org/wiki/W88).
Let's ignore the W88 and assume USA have 6600 B83.
Using [nuclearsecrecy.com/nukemap](http://%20nuclearsecrecy.com/nukemap) we can see that biggest in reach is Fallout contour for 1 rads per hour:
•Maximum downwind cloud distance: 407 km
•Maximum width: 105 km
•Approximate area affected: 33,980 km²
Adding to that known population density of Canada [](https://i.stack.imgur.com/YOBST.jpg)
We can safely conclude that only places that US government should avoid to nuke is Cleveland and Detroit. As those are only places where fallout rain, clouds etc. could travel to Canada and do any harm to it's population.
So to answer your question: **how many nukes can government in US use against their own people** the answer is: **all of them**.
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[Question]
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Earlier this year, a [second alien saucer](https://worldbuilding.stackexchange.com/questions/99987/a-40km-diameter-alien-saucer-is-floating-2km-above-the-ocean-for-a-long-time-wh/99993) came to Earth and stopped 1 kilometer above the central African nation of [Wakanda](https://en.wikipedia.org/wiki/Wakanda_(comics)). The Wakandans are fine with this and refuse to let anyone investigate or do anything about it, so it appears it'll be there for a while (at least 20 years).
However, Wakanda is heavily rainforested, as is the norm for central Africa. **What effects will this alien saucer have on the rainforest ecosystem below?** Specifically, how should we expect the ecosystem to evolve over the 20 years it stays above the surface?
Just like [the first one](https://worldbuilding.stackexchange.com/questions/99987/a-40km-diameter-alien-saucer-is-floating-2km-above-the-ocean-for-a-long-time-wh/99993), the alien saucer emits no visible light but is room-temperature (~25 degrees C) at all times and thus emits a small amount of IR. It has no obvious method of propulsion but nonetheless manages to remain fixed to the Earth's rotation and is completely immobile. Despite its stability, it also has a negligible mass which means that the gravity below is completely normal. This may be due to the fact that the disk is very thin, maxing out at perhaps 10s of meters thickness in the center.
[Answer]
From [the previous question](https://worldbuilding.stackexchange.com/questions/99987/a-40km-diameter-alien-saucer-is-floating-2km-above-the-ocean-for-a-long-time-wh/99993), this disk is also extremely thin.
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> *Thickness: the disk is very thin. Its thickness when compared with its altitude and diameter is negligible.*
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What you're asking, basically, is what would happen if we opened a giant, opaque sheet 1km high above the rain forest? I see two issues: sunlight and weather.
# How Much Of The Sky Will It Cover?
A 40km diameter disk 1km up means it will cover about 174° of the sky at the center, $atan2(20,1) \times 2$ or just about all of it. Given the average 12 hours of Sun, that means the surface at the center will get just 20 minutes of direct sunlight a day. And at a high angle.
As we move closer to the edge, things only get slightly better. At 10 km from the edge, it covers 172° or $atan2(10,1) + atan2(30,1)$. At 5km it's 167° or about 50 minutes of daylight. 1km from the edge it covers 133° of the sky, 3 hours of daylight. At the very edge, half the sky is still covered giving only 6 hours of daylight. Even forest not directly under will still be partially shaded from the Sun for kilometers around.
# Weather Patterns and Rainfall
Having what amounts to a 40km diameter sheet 1km up will play holy heck with the weather patterns and rainfall. The surface will be cut off from medium and high level clouds, and 1km will cut across many low level rain clouds which tend to be vertical. The ship itself, acting as a sheet, will tend to hold in moisture.
I'm not a meteorologist and cannot predict the exact effects, but its going to mess up the weather.
# A Whole Lotta Everything's Gonna Die
Obviously this doesn't bode well for the forest under or even near this object. [A tropical rain forest consists of four major layers](https://en.wikipedia.org/wiki/Tropical_rainforest#Forest_structure) each which get different levels of sunlight. But even the relatively dark forest floor gets some light. And they all rely on the nutrients provided by the upper canopy. With severely reduced sunlight, this carefully balanced ecosystem which relies on a constant supply of sunlight to power it rapidly breaks down.
Temperate forests must undergo seasonal change and regular reductions in sunlight for the winter, so their flora and fauna store a lot of energy for the winter. Tropical rain forests don't have to deal with winter. In their highly competitive environment, all energy is used to compete with each other. With their energy source from sunlight cut off, they'll have little reserves to fall back on. Plants will rapidly wither and die cutting off the food supply to most fauna who will then also starve and die (or migrate if they can).
The result will be rapidly growing dead spot in the forest under the ship that will eventually kill most of the forest over 40km around. Even plants used to growing on the forest floor in low light will not survive without the nutrients and protection provided by the rest of the forest.
Unlike temperate forests, rain forests have poor soil. Most of their energy and nutrients are locked up in their biomass. Anything that dies is rapidly recycled by scavengers. This poor soil means once the forest is gone, little will grow back. The long term result is similar to what happens after we clear cut a rain forest: desertification.
# Result
The forest under and near the ship dies and all the animals die or leave. Insect and microbial scavengers will thrive for a time, but eventually run out of things to scavenge for food and die. Evolution cannot account for such a rapid change in the environment.
What will be left is a dark, barren landscape.
The price Wakanda will have to pay is losing over 1250 km2 of rain forest and damaging another 1000 km2. This is larger than many island nations, roughly the size of [Luxembourg](https://en.wikipedia.org/wiki/Luxembourg). While the size of Wakanda is not known, it is not a large nation, and this could represent a very large chunk of their land area.
[Answer]
The entire region will become a lake, probably with a substantial river flowing downhill from it to the ocean.
This is because rainforests are wet. The Congo Basin, in central Africa near where the fictional county might be placed, gets 50-150 mm of rainfall per month. That means the saucer will have a near-constant rainstorm over at least part of it and will waterfall off water on all sides. With the death of all life beneath it due to the constant darkness and flooding, the water will slowly wash the region away downstream, creating an extremely lively river region. The center of the dead spot will erode last, so for a while there will be a circular lake with an island in the middle. Birds may be interested in the disk, and may colonize the edges eventually, in places the water is less frequent. Probably parrots and Eagles, with the parrots ducking under the waterfall and escaping the predatory birds when needed. Mud-based nest builders would colonize the underside of the edge if there's a mountain near by-- they don't normally fly up very high and they're not as curious as parrots.
Depending on wind patterns, aeolian soil deposition may lead to plant growth on the center of the disk assuming it rains little enough there. The plant growth will bind the soil, allowing more deposition and thus starting off the succession process. At the end of 20 years you will probably have a tiny bit of grass up there. Eventually, you'd end up with a forest, of course, but that would take many hundreds of years.
All of this, of course, is ignoring human interactions, which would make everything very different. Probably somebody (Magneto?) is going to colonize the top of the saucer and create a floating island country resulting in tensions between them and the local government. Human effort could drastically change the hydrological effects of the saucer, with various results.
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[Question]
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**This question asks for hard science.** All answers to this question should be backed up by equations, empirical evidence, scientific papers, other citations, etc. Answers that do not satisfy this requirement might be removed. See [the tag description](/tags/hard-science/info) for more information.
So I was curious what would be the advantages and disadvantages to have 12 DNA bases? For example could it be used to store complex memories in an organism, could it cause very complex structure in an organism that wouldn't be possible in ones with only 4, would it cause more cancer or cancer like diseases, etc...?
[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.
It wouldn't provide all that much of an advantage.
DNA basically stores a string of data. We can measure that in bitrates. Our current system with 4 bases can store 2 bits per nucleotide. For example, we can say A=00, C=01, G=10, and T=11.
A 12 based DNA is a bit trickier to count. If we skip to a 16 symbol system first (because it's easier) we can see that that would store 4 bits per nucleotide: A=0000 B=0001 C=0010 D=0011 E=0100 F=0101 G=0110 H=0111 I=1000 J=1001 K=1010 L=1011 M=1100 N=1101 O=1110 P=1111.
The actual relationship is the bits-per-symbol is $\log\_2S$ where $S$ is the number of symbols you have (i.e. number of individual nucleotide). We can use that to see that this 12-base DNA would be able to encode 3.58 bits/nucleotide, or just shy of twice as much data we can store.
This means their genetic material can encode data in half as many symbols as we need. Not all that impressive. Worse, it's not guaranteed that that means you actually take up half as much space. DNA is pretty simple. A 12 base system might have larger nucleotide, and take up more space!
Replication errors would also be more difficult to deal with, because there's simply more possibilities for what the data should have looked like.
The one really interesting thing you could explore with this 12-base system is how the DNA interacts with things. Consider that we have 22 amino acids that we build our proteins from. We only need 4 nucleotide, but 22 amino acids. Why? Because the amino acids have to do something. They have chemical characteristics that matter when we make proteins, beyond just their ability to hold onto data.
You might be able to explore a creature that finds it valuable to have the DNA directly interact with the environment, and thus more bases means more ways it can interact.
One of the many hypotheses about life forming on Earth is that a single molecule acted as both a data storage device (like DNA/RNA) and an actor on the chemical scene (like a protein). Your 12 base system might be the result of that system taking a very different track in the first half billion years of life.
[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.
While from an information theoretical point of view the number of bases is irrelevant (as long as there are at least two of them), a larger number of bases allows for a more dense packing of the genetical information, using shorter strangs of DNA, consuming less (potentially rare) phosphorus, or allowing for more luxurious proteins with more than the usual 20 plus 2–4 aminic acids.
On the downside, there is a more complex chemistry to be handled, more chances of transcription errors, and a higher rate of mutations. Finding 6 base pairs with nice matchings may also turn out difficult (synthetic biologist are experimenting with some [unnatural base pairs](https://en.wikipedia.org/wiki/Base_pair#Unnatural_base_pair_%28UBP%29) but they are far away from having six of them.
] |
[Question]
[
I'm currently building a world in which coilguns are the primary ranged weapons. Technology is advanced enough to allow for portable high velocity coilgun weapons. I'm assuming the projectiles fired from these weapons will have velocities roughly similar to modern firearm velocities.
I like the idea of a sort of "force field" which will only block the ferromagnetic projectiles fired from coilguns. My question is could some form of electromagnet be made to trap coilgun projectiles before they hit their target, similar to how that mech suit from District 9 catches bullets? Or would something like that just attract bullets straight into the user? I assume the electromagnet device will have the ability to detect projectiles moving above a certain velocity toward the user, and thus only activate when necessary.
If you have any alternative suggestions for stopping ferromagnetic projectiles those are welcome as well.
Since I'm not too concerned with exact mathematical equations for this, I really just want to know if something like this is possible if the only limitation is the laws of physics. We can basically assume unlimited technological and energy resources since I'm more than willing to fudge the numbers for "rule of cool".
[Answer]
## Mostly useless
If such a field would exist, you simply need ammunition made of a ferromagnetic sabot with non-ferromagnetic projectile.
That is a steel shotgun shell with lead pellet or slug. 19th century technology makes your super high tech force field obsolete.
[Answer]
**Use another coilgun.**
Your coilgun accelerates the projectile by triggering electromagnets in precise sequence and increasing the velocity of the projectile. You could catch the projectile in a coilgun the same way, in reverse: each electromagnet decreases the velocity of the projectile.
The trick is to catch the projectile within the coils of the deceleration coilgun. If the trajectory of the incoming projectile can be calculated this could be done by a computer.
I like this because on slowing completely, the projectile will be sitting at the bottom of the deceleration coil gun. Switch the sequence and fire it back!
If your computers are good, this will become a game of catch between the coilguns. You would need to figure out some way to put spin on the projectile or otherwise defeat the trajectory calculators of your opponent.
] |
[Question]
[
Say I want to make wolves intelligent like people, to create a Canis Sapiens of sorts.
**What sorts of tests should I conduct to develop human-like intelligence?**
If it helps, the sort of traits I'm looking for is stuff measured by IQ tests such as **short-term memory, analytical thinking, mathematical ability and spatial recognition.**
Notes:
I'm not sure how well we could test analytical thinking if the dog hasn't developed the ability to enunciate properly but if you can figure out how to get that done, please do.
I chose wolves because I figured the presence of a social structure might allow for the creation of societies and more complex thinking. Also not being turned into a certain breed of dogs probably leaves more adaptive flexibility but if you disagree let me know.
[Answer]
You've already got a start on it. They're called dogs. They can and do breed true with wolves, so they aren't far off.
**Differences & Similarities in Wild Canids vs. Dogs**
First and foremost, let's address one of the coolest things about the genes of wolves and dogs which may help somewhat.
Gene plasticity aka [phenotypic plasticity](https://en.wikipedia.org/wiki/Phenotypic_plasticity). Gene plasticity basically means is that their genes respond fairly quickly to the [environment](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2817147/). And that means it can be easier (compared to other species) to breed for specific characteristics. And further, because of this gene plasticity, dogs developed something that separates them from wolves, something else called [excitatory synaptic plasticity.](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4255776/) This means that dogs are better, not necessarily at problem solving, but with better memory than wolves:
>
> Here, we demonstrate that genes involved in glutamate metabolism,
> which account partially for fear response, indeed show the greatest
> population differentiation by whole-genome comparison of dogs and
> wolves. However, the changing direction of their expression supports a
> role in increasing excitatory synaptic plasticity in dogs rather than
> reducing fear response. Because synaptic plasticity are widely
> believed to be cellular correlates of learning and memory, this change
> may alter the learning and memory abilities of ancient scavenging
> wolves, weaken the fear reaction toward humans, and prompt the initial
> interspecific contact.
>
>
>
Getting to dogs from wolves actually took way less time than we previously thought. The Russian Fox experiment selected for tameness and responsiveness to humans, and that only took 25 years. These foxes began getting spots on their coats, floppy ears and a much wider variation in color than the foxes they started with.
Wolves aren't necessarily less smart than dogs, they're just way less interested in getting human approval. Dogs' dependance on humans, actually make them less smart than, say a dingo, when given a problem to solve WITHOUT a social component. An intermix of dogs and wild canids such as wolves and dingos might serve you well at the start of the program, just to breed out a little of the dependence.
**Types of tests**
But the kinds of tests you are talking about, dogs tend to pass more than wolves at least (but not more than dingos!) They are more capable of learning than wolves are because according to brain mapping, dogs are better at recalling things and people in general. There's one lab at Duke University [testing the way dogs think](http://www.cnn.com/2010/LIVING/11/18/intelligent.dog.psychology/index.html). To test them they take dogs through a series of tests that you might take children through to learn how smart they are.
Run a breeding group through those sorts of tests, then select for the smartest. Keep testing and selecting over several generations. The ones that don't pass, move them on.
**Math for Dogs, Beginning level**
Dogs CAN do simple math:
>
> In the canine version of this test the dog was shown a single large treat and a low screen was put in front of it. Then the dog watched as the experimenter obviously placed another treat behind the screen. If the dog can do the math he knows that 1 + 1 = 2 and he should expect that when the screen was raised there should be two dog treats. However, just like in the case of the babies, sometimes the experimenters surreptitiously removed the second treat so that when the screen was raised the dog saw only one. As in the case of the babies, the dogs stared at this unexpected outcome for a longer time than they did when the arithmetic came out correctly, apparently "surprised" at what they saw. Similarly, if an extra treat was secretly added so that the dogs saw three instead of the expected two, the dogs appear to be equally surprised. This suggests that dogs can not only count, but can also do simple addition and subtraction. [SOURCE](https://www.psychologytoday.com/blog/canine-corner/201103/do-dogs-know-mathematics)
>
>
>
So you would look for surprise, as you see in infants as one of the "first step" tests, and gradually ramp things up as you go.
**Short term Memory & Dogs and Test that's been used in the past**
As to short term memory, dogs, like [most animals are terrible at it](https://news.nationalgeographic.com/2015/02/150225-dogs-memories-animals-chimpanzees-science-mind-psychology/) but they are actually surprisingly better than chimps.
They are better at long term memory, and frankly if it doesn't have to do directly with survival or food, there's really not a reason to. They chose untrained animals for this who had not seen the test before.
>
> Dogs forget an event within two minutes. Chimpanzees, at around 20 seconds, are worse than rats at remembering things, while the memory spans of three other primates—baboons, pig-tailed macaques, and squirrel monkeys—exceeded only bees (the sole study participant that wasn't either a mammal or a bird). [SOURCE see link above]
>
>
>
It turns out that chimps, our closest relatives are actually WORSE than dogs at this particular test. Here's the test they used:
>
> In this test, an animal is typically shown a visual stimulus such as a red circle. The red circle disappears, then, after a delay, it's shown again with another sample stimulus—a blue square, say. The animal, usually with the incentive of a food reward, has to select the original sample it saw.
>
>
>
So start selecting/breeding for this trait. Dogs do have a head start vs. other animals.
**Spatial Recognition**
As to spatial recognition--there are lots of dog breeds that are already very, very good at this. Herding breeds especially so compared to others. You might be talking about something specific, like object permanence, but you can look at for something specific and search for that as far as children's cognitive tests (toddlers and babies to start). Generally there's a dog version out there.
**Selecting for Language Understanding & Analytical abilities**
Dogs do understand a lot of language, and if you want to select for that, chose dogs to breed who have a large vocabulary. Rico the dog not only understood 200 words, he also USED logic. If you told him to fetch something and you used a word he had not learned, he would fetch the new and unfamiliar thing in a massive pile of toys. That shows analytical thinking, or enough intelligence to be able to infer. Which is amazing! Other dogs, generally border collies have learned up to 1,000 different words.
**How to search for your tests**
You can use the examples above, but we have plenty of tests geared for people who can't talk (babies and toddlers) as well as animals in the annals of scientific intelligence test, which test the very things you are talking about. Research those and apply them for first steps. Then look at cognitive tests at a higher level, and so on and so on.
**Bottom line, there are plenty of intelligence tests you can give that in no way involve talking. There's a whole world out there of animal intelligence tests and tests for babies and toddlers.**
[Answer]
Researchers often test the intelligence of animals in terms of mirror recognition with the animal being placed in front of their reflection, if they show signs of touching their own face or twisting their own body to admire different angles of themselves then they recognize that it is themselves that they are looking at and exhibit self-awareness. Other tests include tool using (manipulating an object in your environment for your personal desires, elephants are known for breaking sticks to have a jagged edge in order to scratch themselves), evidence of forward-thinking and planning (a monkey in a zoo gathering piles of stones to throw at tourists that would visit later that day), along with long-term memory such as recognizing old friends after being separated or an octopus memorizing the routines of the watchmen in order to sneak out of its tank to eat the fish in the neighboring exhibit, all collected for evidence of the ability to learn.
Tests that look for these traits would be a good way to measure an animal's intelligence.
(note: all examples are from actual studies and observations
[Answer]
Wolves already [exhibit language](https://www.livingwithwolves.org/about-wolves/language/). So your challenge is to adapt your human breeders' behavior and vocal utterances to conform to the existing behavior of the wolves. The humans won't initially understand or be able to accurately imitate the canine communications, but they must limit themselves to postures and vocalizations which the wolves could imitate. Then through extended exposure, a bridge may form between the breeders and the pack.
In the same way that the wolves have an internal social order, your breeders should also live within a hierarchy composed exclusively of their human peers. One breeder should be dominant and equipped with the skills and weapons needed to compete with the wolf alphas in one-on-one combat. Other members of your breeder team should be more submissive, even to the point of accepting minor wounds without protest from their own human alpha and from their superiors in the adjacent canine pack.
The breeder team must strive to demonstrate their social and authoritative structure to the wolves in a manner that the wolves can understand. Only then is there hope that the human and wolf packs will merge when motivated by a mutual enemy or elusive prey.
If the packs merge, then you have finally reached the starting point where intelligence testing can begin.
Wolf language is mostly emotive, expressing emotional rather than intellectual content. Your initial tests will involve adding representative "words" to their canine vocabulary. Within the human side of the merged pack, a particular growl will come to represent food. Another will represent danger. By using these "words" consistently and in the presence of the real world objects the words represent ( provided by humans outside the testing environment ) hopefully this vocabulary and the whole idea of sounds representing objects will be picked up by the wolves.
Once this process begins, the humans should accelerate the vocabulary learning until distinctions among the student wolves begin to appear. Some of the wolves will be better at picking up and using the new vocabulary than others. It is these successful students who should be chosen for your selective breeding process.
Integrating into a wolf pack will not come cheap. Some of your breeders will be killed along the way. But if you want to select for the kind of smartness that might someday rival our own, that is the first installment on the price which must be paid.
] |
[Question]
[
Jane was different from the other kids. While all the other kids were playing with fire, Jane played with ice. Now, Jane has grown up and is an accomplished scientist or engineer in your discipline of choice.
Jane never got along with Joe, and after an argument between them, Jane has decided to literally freeze their relationship, by completely freezing Joe's entire body. (In this case, we can take "freeze" to mean "reduce the temperature of the object in question to 273 kelvin or lower, and turn any liquids into their respective solid forms".) She realizes that this will probably get her into trouble with the authorities, but she's okay with that.
Both of them are ordinary adult humans without any superpowers. Jane has access to whatever equipment and facilities might reasonably be available to a scientist or engineer in your chosen discipline. The technique is not required to work (or not work) in any particular location; it just needs to work *somewhere* she can plausibly get Joe. (So no cheating by taking a trip to [Titan](https://en.wikipedia.org/wiki/Titan_(moon)), and the South Pole on Earth is probably stretching it.)
Joe does not need to survive the process, or perish from it. He is, however, not a willing participant.
Jane is allowed to work anywhere it's reasonable for someone with her credentials to be working, but it's a big bonus if she doesn't require the assistance of coworkers to pull this off, as said coworkers might not be as inclined as she is to deal with the legal backlash.
**What can someone like Jane do in order to, in as little time as possible, freeze Joe? Roughly how long will the process take?**
Magic *not* allowed; answers should conform to known sciences.
[Answer]
Jane is an accomplished scientist or engineer and she has access to liquid nitrogen, as it is used in the facility where she works. The work place can be as simple as a food processing plant.
**Path 1**
1. She can fill a container, large enough to contain Joe's body, with
liquid nitrogen. Let's say about 80 liters volume. Filling can take about 30 minutes.
2. She makes Joe unconscious. 1-2 minutes with the proper mean.
3. She drops the body in the container. Another 30 minutes to carry the body and drop it.
Total: 1 hour
**Path 2**
a. Jane induces Joe to go next to the liquid nitrogen tank (like the one in the picture). This is variable, from minutes to hour.
b. She blows the bottle, getting Joe drenched in liquid nitrogen. This is a matter of seconds.
Total: depending on how much Joe trusts Jane.
[](https://i.stack.imgur.com/AFYQO.jpg)
Note:
What Jane is trying to do is also used in [Promession](https://en.wikipedia.org/wiki/Promession)
>
> Promession involves five steps:
>
>
> 1. Coffin separation: the body is placed into the chamber
> 2. Cryogenic freezing: liquid nitrogen at -196 °C crystallizes the body
> 3. Vibration: the body is disintegrated into particles within minutes
> 4. Freeze drying: particles are freeze dried in a drying chamber, leaving approximately 30% of the original weight
> 5. Metal separation: any metals (e.g., tooth amalgam, artificial hips, etc.) are removed, either by magnetism or by sieving. The dry powder is placed in a biodegradable casket which is interred in the top layers of soil, where aerobic bacteria decompose the remains into humus in as little as 6–12 months.
>
>
>
[Answer]
You may want to look into [cryonics](https://en.wikipedia.org/wiki/Cryonics). Cryonicists have got all that figured out for Jane. They have not figured out how to thawn Joe back safely yet, though. But then again, according to them, it's just a matter of time until someone figures **that** out.
But seriously, they take freezing speed into account when you go freezing a corps... Er, person.
Their technique is really simple. Throw the body into a container full of liquid nitrogen. It takes only a few seconds a few hours before the body gets completely frozen. More about it [in this link](https://www.express.co.uk/news/science/733717/What-is-cryogenics-how-does-freezing-dead-body-work):
>
> On arrival it is put into an arctic sleeping bag and cooled by nitrogen gas to -110C over several hours.
>
>
>
When it does, it will be rock solid. Don't just believe me because I wrote that. Look at what it does to a few things small enough to freeze in a shorter amount of time:
<https://youtu.be/iE-BtbV6zA8>
] |
[Question]
[
Could my civilization use [sonoluminescence](https://en.wikipedia.org/wiki/Sonoluminescence) to create exotic works of art? Someone said on a science forum that future applications of sonoluminescence can be art. Is this feasible or even possible? I want my civilization to create art in the most unique way but if this is totally impossible, I will find something else.
[Answer]
I'm going to go with "No, but yes."
I don't think sonoluminescence could ever be the *display medium* for art: the burst of light is very short lived, often requiring high-speed cameras to capture and view.
But I think you could make art *using* sonoluminescence, for instance, there's [this video](https://www.youtube.com/watch?v=tW8q_JfmcbU) on Smarter Every Day that is rather beautiful to watch. It uses triboluminescence instead of sonoluminescence (shattering crystals rather than collapsing vacuum pockets under water) but it's a similar effect. I'd say that *that* is worth calling "art" even if the display medium is standard (slow-motion) video.
] |
[Question]
[
I'm actually trying to create an alien ecosystem, so changing orbits, what's exhibiting tidal forces and the geography and such is welcome if needed. I also wonder how stable a setup with dramatic tides (flowing into an otherwise stagnant area) would be. The point of this specific ecosystem on my planet is the evolution of the dominant race; they evolved in fertile swamps that had dramatic tides. The high tide would be about 7 or 6 feet deep or so (essentially tall enough for a human to swim in), and the low tide would be knee/ankle deep, with days where there's almost no water at all. Anyway, it would need to be stable enough for a species to evolve and adapt to it.
BONUS: It would be helpful to know how this setup could develop, too, but that information is not necessary. I really only need to know if it is possible and stable.
[Answer]
# Mangroves in an area with naturally high tides works
Here is a mangrove forest in Kiribati at high tide:
[](https://i.stack.imgur.com/bgBZ4.jpg)
Here is one in Thailand at low tide:
[](https://i.stack.imgur.com/J8OEI.jpg)
Mangroves are designed for this sort of enviornment. They are able to grow in salt water by diffusing all the salt that they suck in from their roots into sacrificial leaves, which are then shed.
The next thing you need is to find a place that has high tides. Fortunately, I happen to know of a place that has mangrove swamps and also huge tides. [Bissau](https://en.wikipedia.org/wiki/Bissau), the capital of Guinea-Bissau in West Africa has around 4-5.5 meter [tides](https://www.tide-forecast.com/locations/Bissau-Guinea-Bissau/tides/latest), or 14-18 feet. At 6:54 am this upcoming morning (in Africa time), the tide is predicted to be 0.17m, or 0.6 feet. By 12:28 pm, or 6 hours later, the tide will be 5.41m or 17.7 ft.
As for fertility, there are lots of fish to be found in these places, so if your people are fish-eaters or maybe [Sahuagin](https://en.wikipedia.org/wiki/Sahuagin), they should do well here. Agriculture is a tougher call, in salt water, but they could also grow bugs fed on tree leaves, farm shrimp in pens or a variety of other things. Incidentally, Bissau also has a powerful monsoon, so the tide marshes fill with fresh water and dirt washed down from the hills once a year, which is good for re-fertilizing the soil. I'm sure you could come up with some adequate food chain for an intelligent species.
This should be the sort of environment and tidal variation you are looking for. So, it is possible and stable, because it exists on Earth.
] |
[Question]
[
Could a steam powered cannon be a practical weapon? And if so how good a weapon might it be?
As a measure of how good a steam cannon might be, comsider how might it compare to existing weaponry in terms of range and weight of projectile. For example hand guns, machine guns, small calibre howitzers, 6 inch navel guns and 12 inch naval guns.
I would be interested to know what aspects would limit the abilities of the steam cannon and what might be done to increase its effectiveness.
Consider the technology of 1918 as a base case, but more recent technical innovations might also be of interest if they make a big difference.
[Answer]
For the sake of simplicity, I'm going to compare a regular cannon, to a steam cannon.
A regular cannon uses explosion from gunpowder to push a cannon ball out from the barrel, and a steam cannon uses pressurized steam to push a cannon ball.
one of the main problems is that you will need to use **pressurized** steam, so you will need to have a tank to store the steam (that also serves as the heater), and a valve to control the flow of it to the barrel of the cannon. Using a regular cannon you just put the gunpowder at the back of the barrel, and that's that; no need for a tank to store steam, and a valve to control it.
another problem is that you will need way more steam than gunpowder (volume wise) to push a cannonball of the same size.
For use in the battlefield, a steam cannon will be very unwieldy; and dangerous to use.
Edit : Looking at the comments, I'm going to add a few more things.
A conventional cannon, has a fuse (optional); the propellant (gunpowder) a barrel, and the projectile (cannon ball). even with only 3 to 4 components; alot could go wrong. Imagine a steam cannon; there's the boiler (which by itself also has a few components of it's own), charcoal/coal to burn, the barrel, a valve to control when to release the steam, and finally the projectile.
When designing a weapon (or anything actually) it is best to keep it as simple as possible; to prevent anything from going wrong (anything that could go wrong WILL go wrong).
in the comments :
>
> One advantage a steam cannon would have would be the size of the gas
> reservoir could mean that the pressure fall could be much lower as the
> projectile moved up the barrel
>
>
>
Well, it IS technically correct; but you have to keep in mind the amount of heat, and water you would need for it to work. It would be far more effective to just use gunpowder.
Regarding the power of Steam : [Link](http://ir.library.oregonstate.edu/xmlui/bitstream/handle/1957/5466/All_Ever_Need_ocr.pdf)
Converting BTUs into Joules : [Link](http://www.greenbuildingadvisor.com/blogs/dept/musings/understanding-energy-units)
[Answer]
**Compared to modern and emerging weapon tech this is useless.**
Building steam requires significant time and energy and extra faculties. Igniting explosive compounds as a propellant takes no time at all.
As for what they can deliver, its virtually the same because both methods are hot gas that is pushing a projectile.
Now compare that to emerging electromagnetic weapons like the railgun. No more costly chemicals or projectiles and far superior speeds. Just a lump of metal flying at insane speeds causing tons of damage.
**Note:**
The iron triangle in weapons is range, precision, and rate of fire (there is also the destructiveness of its projectile however that is subject to its operational need).
Because this significantly hinders RoF it fails as an alternative.
] |
[Question]
[
[Here](https://worldbuilding.stackexchange.com/questions/90414/do-stars-in-a-binary-star-system-fall-along-the-ecliptic) I began exploring appearances of binary stars when standing on a planet. The planet orbits both stars.
I've established through the help of this community that there are times that the two stars align and appear as one star. I've further established that solar radiation (solar storms) hitting the planet can fluctuate depending on the orientation and geometries. I have solar storms and dangerous radiation happening when the suns are aligned with the planet.
^ Background. ^
**Question:** All else being equal, I intuit that the two stars at their maximum distance from one another (as seen from the planet) will heat the planet to a greater extent than the two stars in alignment with the planet. (I intuit that during alignment there is one heat source not two). But I am not certain and given the above background, it could actually be the opposite. Thank you for any clarity you can provide.
[Answer]
If you look at the diagram of the light intensity of a [binary system](http://www.physics.sfasu.edu/astro/ebstar/ebstar.html) vs the relative position of the two stars, you clearly see how the position affects it:
[](https://i.stack.imgur.com/6Vxvv.gif)
Now, since the inpinging radiation is proportional to the intensity, you can see that your intuition is correct. When one star eclipse the other there will be a dip in the intensity.
] |
[Question]
[
The setting for my RPG has one large empire of humans that wants to
establish a colony on a moon much like our own moon. No atmosphere, no
food, no heat, no problem: The empire has a hundred intelligent undead and
they have all been drafted as colonists.
"Intelligent undead" here means [vampires](http://www.d20pfsrd.com/bestiary/monster-listings/templates/vampire/), [skeletal champions](http://www.d20pfsrd.com/bestiary/monster-listings/undead/skeletal-champion/), and the like. It's a Pathfinder RPG campaign setting.
For their party, the vampires (and other intelligent undead) are tired of
being hunted. They have agreed (for now!) to work with this empire. Transport to the
moon and back is done by empire wizards with teleport spells.
A deal has been struck. In return for building out the colony and creating
a breathable biodome , the undead
become citizens of the empire. Fresh sources of blood are teleported to
the colony every few months: beasts, captured monsters. The empire does not
want to create any more vampires than it can secure on a distant colony, so the worst convicted
human felons are *not* sent to Undead Lunar Base.
The vampires have enough wizard levels / magic power to build the biodome, not enough to teleport away. Or so the Empire believes....
Part of the reason why "drafted as colonists" works is that the undead are
tired of hiding and fighting. They want a city of their own, on the far
side of the moon (buried under the surface to keep away from the sunlight), well removed from all the holy symbols, garlic, and paladins. These undead
have "bought in" to the empire's plan. The undead may even have a secret
plan to build their own power source within this colony, unknown to the
empire.
The empire also offers the carrot of 'citizenship' to the undead. This is the part I want to examine more closely with this question.
What aspects of "laws about citizenship" should I keep in mind to make this
work at start? What will the undead petition for over time?
This is both a campaign setting and a story in that campaign setting. Each side
does not trust the other, and that's part of the tension to the story.
I'm not worried about one side pressing an advantage over the other.
I'm worried about logic gaps in the background and I'm trying to think those through before I implement this setting.
---
[Answer]
"Dead" is usually a termination point for things like citizenship so you probably want to redefine the undead as being "differently alive" for a start.
Look at the rights of slaves in Rome for a start, you're going to need an equivalent of [manumission](https://en.wikipedia.org/wiki/Manumission) somewhere along the line. Even if the undead aren't technically slaves they're going to start with very few rights and the proposed set up suggests that they are in effect slaves; they're basically paid in food for a start. Then look at the civil rights movement in the USA starting with the civil war. You're going to want to pay special attention to rights around things like property and franchise (the right to vote).
[Answer]
In many (most?) countries on Earth today, one acquires citizenship in one of two ways: being born into it, or going through a formal process to become a citizen. Your vampires will presumably undergo the latter. *Their* descendants would presumably be born into it -- *but* you're going to have to define "born". Your question implies that vampires can raise other vampires (hence they don't get human criminals); does that count as "birth" for citizenship purposes? Or does the person's original citizenship continue past his undeath? No current laws address this question.
Some countries assign different rights to born and naturalized citizens. For example, in the US the latter are disqualified from the office of president. Your undead might not, over time, demand privileges equivalent to born citizens, especially in light of the colonization task they are doing on behalf of the empire. Alternatively, your undead might argue that, as in the previous paragraph, their citizenship when they still lived should continue to apply -- they might argue that they are born citizens, not naturalized, in other words.
Citizenship confers rights for residency and travel that do not always apply to non-citizens. There shouldn't be major changes here, with one wrinkle: can your vampires be photographed? If not, laws about valid ID, photos on passports, and the like will need to change for them to be *able* to legally travel.
In some (most?) countries, citizens (but not non-citizens) working for or as part of the government or military are sometimes granted security clearances. As part of the process, identity needs to be validated, including biometrically. Can your vampires be fingerprinted? Do they have personally-identifiable DNA? If any of your vampires want to work in national defense, these processes might need to change.
In some countries, citizenship grants rights to publicly-funded social services such as medical care. Human citizens might push back on that because vampires live forever and people don't, so the commitment for each vampire-citizen is greater. Your vampires might be fine with this, but expect your humans to lobby for lifetime limits, mandatory contributions (you only draw out if you pay enough taxes in), or other restrictions.
There are other laws that will need to change in a world that integrates the undead, particularly inheritance law, but those aren't usually tied to citizenship.
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My fantasy species has the ability to swallow small to medium appendages whole. They're known for biting off and swallowing hands and feet. A snake like jaw could work but how would it still maintain a somewhat human-like face?
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Oh, I think we can get 'er done.
Your critters look ... basically humanlike, but they all seem to have big jowls and double or triple chins. No biggie, right? Well, when it becomes time to swallow a large body part, they throw their heads back, and jowls/underchin area balloons out (think when a humpback whale takes a gulp of krill) to make room.
To address @l-dutch concerns, these guys will have a cartilaginous sternum instead of bone, so they can expand there as well.
Now what I'd be worried about is that the big eaters of the animal kingdom tend to get sleepy after gulping down massive body parts. It'd be awkward to have afternoon meetings at work. Though it could be worse...
"Hey, haven't seen you for awhile. How was your date with Mindy?"
"Well, she took the waiter's arm off at the shoulder, swallowed it whole, then passed out into the mashed potatoes. She's been asleep for the past three weeks."
"So what you're trying to say is that you didn't get to second base?"
"Yeah, pretty much."
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Apart from dislocating the jaw, the main problem is that we humans have a 90 degree turn when going from the mouth cavity to the esophagus. Sword eaters solve the issue by looking upwards, but I am not sure that would be doable with a dislocated jaw.
Another problem when swallowing a whole body part is going to happen once it has to pass through the rib cage.
The present structure of the human rib cage is closed, meaning it cannot expand that much. So the esophagus is limited in the size of objects it can carry.
[Answer]
These humanoids would have *evolved* to eat large amounts of food when it comes, (ie. food is abundant, but only at certain times, or in other words, feast or famine).
In both anime and cartoons, there seems to be a tendency to give people big heads. This would be pretty much perfect for our purposes, along with the following modifications:
1. A gape, AKA a serpentine arrangement of skull bones, ligaments, and muscles.
2. More cartilaginous structure (jaws, collarbone, sternum, ribcage, and so on) to allow consumption of huge amounts of food.
3. Expansive stomach and esophagus (like a gulper eel), along with strategic
Why a big head? Because big heads means bigger jawbones, which means larger gape. Granted, it won't be a *huge* difference, but every little bit helps.
This arrangement will allow your humanoids to swallow not only part of an arm, but an entire person. I can see it now:
Mindy: Hey, Yancy's coming over here, and she looks upset. Did you say something to her?
You: No, I can't imagine what I could have said to upset her....
Yancy stops in front of Mindy. Mindy steps toward her, about to ask her a question, and then Yancy's mouth suddenly distends horribly, clamping down over Mindy's upper body (head, chest, shoulders) and her arms grab and lift Mindy as she swallows. In mere seconds, Mindy has been swallowed whole.
Congratulations, you happened to get yourself claimed (albeit unknowingly) by the *one* girl who A) was a yandere just *waiting* to happen and B) just happened to be part of the *Hominem Edacem Sapiens* subspecies. What happens next is up to you, but if *I* were you, I'd exchange small talk until she drops her suspicions (of you planning to leave the country), then leave, change your name, and leave the country.
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**Closed**. This question needs to be more [focused](/help/closed-questions). It is not currently accepting answers.
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**Want to improve this question?** Update the question so it focuses on one problem only by [editing this post](/posts/83418/edit).
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My [Writers SE question](https://writers.stackexchange.com/questions/28645/is-ice-fire-opposition-too-stereotypical) about an ice magic user reminded me to ask this question.
I'm writing a long (~1000 pages) [hard fantasy](https://en.wikipedia.org/wiki/Hard_fantasy) story (in French, don't judge me on my English :p).
In this story, there are many different types of 'magic', including cooling and heating. I read other questions about how to make ice from air so I already know a way to make ice.
BUT, I want this ice to be controlled - that is to say one can *change its shape* or move it with telekinesis (at like 20km/12miles per hour). I already know how to move it, but I don't know how to explain that some can change ice's shape...
When I say **change its shape**, I mean : from a cube to a ball for example.
How would that work? I think maybe the same question could be asked for any solid object.
Do tell me if you need more details.
**Edit**
Thanks for your feedback.
Basically, in my world, magic works because some people have a natural ability to modify nature's properties, like giving energy to atoms to heat them.
So any magic would be explainable by our world's science, even if we aren't able of reproducing it.
There's not much real technology except for basic mechanical engines.
About how to make ice, [here](https://worldbuilding.stackexchange.com/questions/83049/what-are-the-effects-of-generating-ice-from-water-vapor-on-a-large-scale)'s a question whose first answer includes how to make ice. Basically, condensing and cooling air.
[Answer]
If it really *must* have an explanation:
# Telekinesis = Virtual Particles
Virtual particles is a theory about [how fundamental forces work](https://en.wikipedia.org/wiki/Virtual_particle). The basic idea behind this theory is that charged particles create and send virtual versions of themselves to run into other particles. These smaller particles running into 'real' particles gives rise to forces.
So you could claim that telekinesis is just exerting control over these virtual particles. Of course, how you do that is simply "magic," and this is mostly just a mathematical trick people use to get their heads around particle interactions.
# Control The Shape of Ice During Formation
If you're forming ice out of air, you simply need to control where in the air the conditions for ice formation occur. You control the first [nucleation point](https://en.wikipedia.org/wiki/Nucleation) and can control which portions of air have the correct properties to cool and condense water out of air.
Ice crystals are formed from a hexagonal crystal structure: odds are some combination of one direction or another will yield the shape you want, you just control which sides are allowed to grow and which ones are not.
# Shape Changing
Given that you can now move and shape ice, you just need to do what we do with many other materials: cut and join.
* Step 1: A person wishing to change the shape of some ice 'cuts' by melting a thin plane of molecules or applying the appropriate [shear force](https://en.wikipedia.org/wiki/Shear_force) (like you do with scissors).
* Step 2: Once that block of ice is separated, you move the ice to a place you want it to be.
* Step 3: Freeze that ice block to the original ice. Phrased another way: provide the conditions for ice formation along the plane such that the two pieces will be joined.
* Step 4: Repeat steps 1-3 until the desired shape is made.
[Answer]
So here is my answer, please continue reading after my initial statement (or don't):
This is all a really bad idea. Being able to freeze air and make sculptures is one thing, but the implications are another one. If one could really just alter properties of individual atoms/molecules just like that, making ice cubes is the last thing anyone would ever do with it. The things you could do with this are endless - from powering near-lightspeed spaceships to killing millions of people with the blink of an eye. I do not want to go into the details, I already discussed some problems in the comments - but basically if you introduce those kinds of magic into our real world, things get messy. Luckily, there is still a chance for you:
You said that your civilization is rather primitive. So if you let's say alter how things work microscopically, they will not notice. Choose your battles. If you are doing iron age fantasy, you do not worry about general relativity and what the result of the Stern-Gerlach experiment would be. Your people live in a strictly Newtonian world - even further, they do not live in a world made out of molecules and "atoms" but in a world made out of water, ice and rock. This is all you need to stay consistent with. If you want "real physics", well, just do it. You already said that you know how to implement it and if your people rather build ice structures than kill each other - well, good for them. But be aware that things do not make as much sense anymore (paradoxically).
I think it is clear that "ice" needs to be what some people might call an element of your world. A state anything can enter and leave if given the right stimuli rather than a marcoscopic observation that is a result of microscopic behaviour.
You should still worry about the pressure changes resulting in those escapades since even primitive cultures for example knew how sails work and certainly have experienced wind, but you could alter how density works and that things become heavier/denser once they enter the "ice state".
Some things are the result of what we call quantum mechanics. Quantum mechanics is completely lost once you say that you treat individual atoms and alter their speed. So do not worry about being consistent with our world. There will always be magic to save you - sure water ice does float on liquid water - so maybe do not change density in general but introduce magic density for example or remember that water even in our world is more of an exception than the rule - or as a third option make the liquid and ice state denser. There are many options once you backed yourself out of that corner you are in currently.
And the details - how do proteins work in a Newtonian world? Well, your culture still doesn't know what proteins are. There are many details like this and many things to clarify, but I would heavily advice you against trying to just introduce ice magic into our world and expecting that things still make any sense. Often enough, being super vague is a solution btw. Even pretty hard sci-fi technobabbles over all the important details. At the end of the day, all humans live in a Newtonian world made out of rocks and air and not in a quantum mechanical nightmare - that is how we see the world. This is how your audience knows the world. Introducing weird concepts to be consistent with contemporary physics is helping the 0.01% of humans that understand that stuff (I'm not one of them myself) - and even they think mostly in ice and rock. Choose your battles wisely.
[Answer]
All magic implies handwavium, so don't overthink that too much. If you want a magic that follows physics more *"realistically"* what you have to do is taking account of physical constraints rather than meddling with physics theorems.
For example, you want ice magic. If a mage wants to shot an ice bolt, where does the water come from? Water moisture in the air? Then, his/her powers vary greatly with the proximity of a water source and the humidity of the air. An ice mage would be much more powerful in the sea than in a desert.
[Answer]
Why can't telekinesis change its shape?
That is the ability to apply force to an object with one's mind, so why not ball a cube up mentally. The harder question is where do you get the water to make ice?
But you could get that from the air or blood or ground.
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If we were to encounter alien species of, lets say approximately the same size as us, **would there be any reason to expect them to communicate in the same frequency ranges as us?**
Human beings have a [frequency range that we hear in](https://en.wikipedia.org/wiki/Hearing_range#Humans), and a [range that we talk in](https://en.wikipedia.org/wiki/Vocal_range). **Is there anything special about this range?**
I'm thinking perhaps:
* Those frequencies easier to produce by biological constructs.
* Hearing those frequencies is more useful for other survival aspects.
[Answer]
So we have plenty of animals, even mammals, on Earth which create higher or lower frequencies than we can hear. There tends to be some cross over with the frequencies we hear but the fact that we have instances of it occurring on Earth means it would almost certainly happen on another planet.
On another planet the composition of the atmosphere, gravity and air pressure would all, most likely, be different - these would all effect how vocal chords would evolve there and produce a different frequency range in our atmosphere.
That doesn't mean we wouldn't be able to hear them, just probably not all of the sounds they make. Though in our atmosphere they might not be able to hear them either.
[Answer]
The [Fuzzies](https://en.wikipedia.org/wiki/Little_Fuzzy) have ultrasonic voices, not as a consequence of being smaller than us (they’re not *that* small), but to make their communication intentionally inaudible to most other animals. Hunters can talk to each other without alerting prey.
Bats make ultrasonic noise, not because their throats are so small, but because it makes for useful sonar. If they were to develop speech it would probably start with the complex vocal control they already have.
Elephants communicate using infrasonic calls not because their size requires them to make only low notes, but because it can be heard through woods — the tree trunks are small compared to the wavelength.
So it is quite concevable that aliens will use sound that is beyond our range of hearing.
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> Is there anything special about this range?
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No there isn't, it's just a product of our physical traits.
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Imagine we could open a wormhole or a jump point to a new star system. How soon would it be possible to have an accurate map of the major bodies in that system? In sci-fi, this sort of information seems to be easily available through "scanning the system" but what does that actually mean? What sort of scanners or sensors could we use to detect orbital bodies?
Using our own solar system as an example... we have made most of our discoveries through optical observation, this has taken hundreds of years, but we could imagine that time would be much shorter with modern telescopes and techniques. But unless we some had other sort method of detection, this would still be a very long process.
I would imagine that bodies closest to the star/s would be the fastest to discover, with the amount of time dramatically increasing as we move to the outermost planets. Maybe an entirely accurate map would never be feasible (just as we are uncertain of planets outside of Neptune in our own system, or we were uncertain of the number of moons Pluto had until the New Horizons flyby). Would there be optimal places to emerge to make this process faster? Like in the OORT cloud range for example, or extremely close to the star/s? If a completely accurate map isn't possible, how accurate of a map would we need for travel through the system?
[Answer]
It depends on a number of things.
## What are we mapping?
Even before we map anything, we need to know exactly what we are mapping. Large, easily visible stars? Planets? Moons? Asteroids? Find your cutoff first. Local stars are easy to map, generally speaking, since they tend to be fairly stable, and radiate energy on their own. Planets are harder to map, since they don't radiate energy on their own. Moons are harder still, and mapping every asteroid would be nigh-on impossible, if for no other reason than there are so many of them.
## Where are we mapping from?
If we're on a planet with atmosphere, that atmosphere will get in the way (as will the planet, its moon if it has one, and so forth). If we're mapping from space, but near a planet, we'll still have to deal with the planet being in the way. On the other hand, if we're mapping from a point of "dead space", far from the system, we'll have a full panorama spread out in front of us; not having to wait for day/night cycles, or worse seasonal cycles, will save a lot of time.
## What are we using?
If all you have to map celestial bodies is a basic telescope, it'll take years of careful study, regardless of anything else. If we're using tiny satellites carrying preprogrammed cameras, it will take weeks of taking images, transmitting them, and sending back new coordinates to map - and likely months or years of travel to get close enough to anything to get anything useful. If we are on a scientific vessel designed for just that purpose, however, it's likely we have countless imaging devices for all spectrums of energy, software to parse the images directly, and scientists to put all that information together - all of which will save a lot of time. A major part of the reason it took hundreds of years to map our system is technology; until the last 100 or so years, we barely had anything past telescopes. And now, most new discoveries are made through breakthroughs in technology.
## So, how long?
Forever. No matter how good your equipment is, you'll always have a little more to map. That's just the way of things; stars, planets, and space debris move around, and sometimes it takes a long time before a new celestial body is revealed.
However, if you have good equipment, good software, a good vantage point, and limit yourself to mapping easily visible local planets, and maybe a few large moons, you probably could map a system within seconds. As you extend the boundaries of your search, you can map more and more; it's up to you when to stop.
[Answer]
**It depends on the avaiable resources and political will for doing the mapping.**
All they have to do is to send a swarm of satellites carrying not-too high magnification but high field of view (<https://en.wikipedia.org/wiki/Field_of_view#Astronomy>) telescopes to spot the brighter bodies, and some high-resolution and high pointing accuracy telescopes to track the detected ones and determine their deatils and orbital elements. All telescopes outfitted with instruments working in IR, UV, Visible or even x-ray band.
The pointing telescopes would have Strong engines too, to place them appart and thus ensure faster parralax measuements.
After the biggest bodies are mapped, orbital perturbation analysis could be used to detect new ones.
**Of course complete mapping is impossible, it is almost impossible to discover all the sub-100m asteroides and micro moons of gas giants.**
**But as a questimate, I think that the complete mapping of the significant bodies of a solar system similar to ours would minimally take 5 months.** Since outer system bodies have very long orbital period (Pluto: 248 years), one have to observe them for a time to get meaningful orbital information.
If we only send a small telescope (NASA budget is low), it can possibly take hundred of years.
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I'd like to make a sentient plant species that can perform tasks such as communication and problem solving.
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> **My Definition of Sentience**
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When asking this question, I mean sentient as in able to rationalize and solve problems without solely relying on instinct. I believe there are two levels of sentience. The first is animal level sentience, which is basically where they are able to communicate and socialize on a low level and have simple emotions. The second is human level sentience. Our emotions, thoughts, and social lives are extremely complex compared to animal's. I am looking for the human level sentience in these plants.
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> **What I Already Know**
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I know that technically speaking a plant is a life form that uses photosynthesis to produce food for itself in order to survive (though other life forms can do photosynthesis too). That's about it. I am not a botanist.
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> **What I'd Like to Know**
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I'd like to know how this hypothetical species could fit my definition of sentience (I'd also like for them to be mobile, but it's not a must) while still technically being considered a plant. (please note: I am not wondering *whether* or *how* a plant could develop sentience, this question is more about whether a sentient plant is still a plant while being intelligent as a human)
[Answer]
It would be something like this:
[](https://i.stack.imgur.com/iEaqI.jpg)
There are two issues you need to overcome with a plant like this. The first is the [sentience quotient](https://en.wikipedia.org/wiki/Sentience_quotient) (SQ). SQ is a measure of how fast bits can be processed vs. the mass of their calculating organs, measured in bits/s/kg, and usually shown on a logarithmic scale. All neuron based life forms sit within a cluster around +13, including humans. Plants score a -2 while carnivorous plants like Audrey 2 rank at a +1. The first challenge would be overcoming the massive 10-orders-of-magnitude difference in processing rate.
The easy solution would be to let plants use neurons, but there's a price to pay. Neurons are not cheap to maintain. The human body dedicates 20% of its total power to the brain. This is where the limits of photosynthesis come in. It's not possible to generate enough power for such a brain using photosynthesis (I believe there was a past question on WorldBuilding regarding whether a human could live of photosynthesis alone, and the answer was "not even close").
Probably your best bet would be to abandon photosynthesis as a primary food mechanism, and instead have an immobile creature that feeds off prey animals. Perhaps it hypnotizes them into drawing too close. That would require a real brain to accomplish.
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Judy likes coffee. Right now he is standing in the middle of the urban park sipping it.
Unbeknownst to him a local phenomena occurs somewhat near: space itself bends where a lovely group of lilies grow.
As space itself I - as a layman - am speaking about that abstract thing that is, according to relativity, influenced by mass.
It's just a fluctuation, but on a macroscopic scale, limited to a sphere of a radius of 100 cm.
* It that a real thing? Or is space itself just a concept?
* If yes, what would be the effect on a common (but lovely) group of lilies? Or on the soil around it?
* If still yes, what would it look like from the external observer, i.e. what would the lilies look like to handsome Judy?
[Answer]
Space Time is a real thing. We just detected gravity waves to put that debate to bed.
The effect depends on how strong the fluctuation is. Think of a pond and dropping different sized rocks in. The ripples will be the same diameter as they travel outward but the peaks of the waves will be higher.
* So if the fluctuation is small, there likely won't be any observable
effect. Some atoms will get moved slightly but the movement will be
within their normal travel range.
* If it is larger, it might cause some internal damage by pulling
molecules farther apart. That would have no immediate visible effect
on the lilies but the amount of internal damage would depend on just
how strong the flux was.
* If it wasn't too strong, then the lilies would heal the damage with
no visible damage. As the flux gets stonger, after a few days the
lilies would look damaged (like getting stepped on) but survive. If
the flux was at the high end of this range, the lilies will likely
die as more damage has been done than it can heal.
* If higher still you get the first immediately visible damage to the
lilies. They will look ripped apart as the fluctuation pulls it
apart farther than the "springiness" of the plant can handle. This
will go all the way up to the area looking like it went through a
blender.
* The next step has molecules themselves being pulled apart. The
effects really depend on the chemicals involved.
* Next you might get enough movement to initiate some fusion. The
effects could range from some sparkles that are too faint to see to
**BOOM**.
* When you start ripping the atoms themselves apart, you are much more
likely to get fusion and you get to, briefly, see a low temperature plasma.
* Lastly, if it is super strong it can rip protons apart and you get to
discover what it would be like to stand inside the Large Haldron
Collider when it is running.
From the outside there may be other visible effects from lensing. Like gravitational lensing, you would see things behind the fluctuation move as if a lens had appeared between you and it. The amount of movement would range from unnoticeable to giving you a headache to look at.
[Answer]
Assuming Judy isn't within those 100 cm, Judy is going to see the lilies crushed by something invisible, which forms a divot in the soil. As he ponders as to the meaning of this, the shockwave of the displaced air hits and he gets knocked over, his ears start ringing and he feels nauseous. He falls unconscious and is no longer interested in unusual phenomena.
A simple way to consider space-time warping is to think of the rubber surface of an expanded balloon. A mass would be like a grain of sand on the surface; depending on its size (for want of a better word), it will cause a localised depression. This is its gravity well or, as you described it, bent space-time. When two such masses are close enough that their wells can intersect, the lighter one slips towards the heavier one, rolls downhill, as it were, unless they are far enough apart that the depth of the heavier one's well at the location of the lighter one is less than the depth of the lighter one's well.
The question now is, what is causing your local warp and how big is it?
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To visualize it, do it in Flatland. Standard graph paper is your normal map. Draw curved lines to have bent space. Distort a rubber sheet or silly putty picture (if you remember those; newspaper ink is different now and it no longer works).
Now the hard part: what it *looks like* from the inside will have light follow the grid without being aware of the distortion.
If you **post** a Flatland version of your particular bend, we can help you figure that out.
[Answer]
In essence you are asking what would happen when a very small black hole passed between a viewer and an object. The short answer is spacetime will be distorted into an "Einstein Ring" around such a small gravitational point source, and the visual image will be "bent" around the black hole.
Your viewer will have a difficult time interpreting what is being seen (and this is before taking into account the devastation that is being caused but the intense gravitational field). A very nice visualization of an Einstein ring moving across a field of view is here:
[](https://i.stack.imgur.com/1FBxy.gif)
*Einstein ring moving across your field of view*
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One of the answers to **[What could make a star green?](https://worldbuilding.stackexchange.com/questions/64344/what-could-make-a-star-green)** describes a living [Dyson sphere](https://en.wikipedia.org/wiki/Dyson_sphere) made of photosynthetic, plant-like material.
**What type of star or star system is ideal for a plant-like Dyson sphere?**
Keeping in mind **access to nutrients** and a **healthy dose of radiation**...
* [Protostars](https://en.wikipedia.org/wiki/Protostar) seem like a good choice, as there's lots of material available, but they also seem too chaotic. I don't want my sphere ripped apart. Plus, they go on to form protoplanetary *discs*, not *spheres*, making material hard to gather.
* [Red dwarfs](https://en.wikipedia.org/wiki/Red_dwarf) are cozy radiation-wise but they may not hold much material post-formation
* [Brown dwarfs](https://en.wikipedia.org/wiki/Brown_dwarf#Planets_around_brown_dwarfs) are pretty dim and may not hold much material at a low temperature
* [Main sequence stars](https://en.wikipedia.org/wiki/Main_sequence) have usually cleared out all the nearby material
* [Blue and white giants](https://en.wikipedia.org/wiki/Blue_giant) have too much deadly, ionizing radiation
* [Planetary nebulae](https://en.wikipedia.org/wiki/Planetary_nebula) sound like a pretty good start, actually
* This is just skimming the surface, and other configurations are bound to exist. You are not limited to this list, these are just my thoughts.
**So again, keeping in mind photosynthesis-friendly levels of radiation that won't immediately fry cells - as well as an abundance of material - what is the best system in which to place a photosynthetic Dyson sphere?**
\*Photosynthesis does not necessarily need to use chlorophyll if that matter
**EDIT:** If not clear before, I'm looking for a *natural* system that doesn't have to be edited manually first.
[Answer]
You might not necessarily like this answer, but...
Considering the technological level needed for a society to being able to go through with such a massive project, the **location will likely be secondary**.
You can literally just choose any system you come across that contains one or more planets with (primitive) plant-life1 capable of photosynthesis. The more evolved the plant-life on said planet, the more likely it is that radiation doses and other factors are favourable for whatever you want to live there.
Then your society starts the monumental project of taking apart all the bodies in this system (and likely neighbouring ones) to gather enough material to build a perfect sphere with a radius of roughly the distance of the planet that managed to create life by itself - and voila, you've got a new home or zoo2.
And before you know it you've created a tremendous structure somewhere in a corner of the galaxy, silently hiding away giving out no emissions and thus being dark to mostly any form of sensors.
1Doesn't necessarily have to be a plant, but writing *plant* makes understanding easier
2Or whatever it is that this species/society was looking to achieve by building that thing
[Answer]
If it's an artificial construct/creature you build/place it around a Red Dwarf, always; Red Dwarves live long, *long*, reasonably untroubled lives, if you are making the effort to build any of the system spanning mega-structures you're in it for the exceedingly long haul. You can probably find Red Dwarf systems with suitable debris halos in the inner system that you can exploit for the resources to grow the sphere but probably the ideal is to get in on the ground floor and put it up around a proto-stellar cloud that's about to become a Red Dwarf. If you do that the sphere captures all the debris blown out of the inner system when the star initially lights up, and in fact most of the proto-planetary material that's around during the heavy bombardment phase when planets would otherwise coalesce as well because anything that crosses the goldilocks line for the finished sphere will be intercepted.
I am assuming that anyone who can engineer a Dyson Sphere Plant can do so in such a way that it's life cycle is compatible with the star it's being matched with such that it can feed on the infrared of the proto-stellar disc during it's initial growth phase and the visible light of the star once it matures. Finding a good cloud should be easy enough since it's purely a matter of total mass.
[Answer]
If you can build a Dyson Sphere, you can build your own plantlife. All that's required is to drag enough resources to the site and build the Sphere. Rather than try and scoop this up from a Sun, I think you would be launching asteroids and entire planets to that sun for the materials needed, then build your Dyson Sphere! Just make sure you are done before the goldilocks zone changes because the sun goes into another state...
[Answer]
If you want something that would have a chance to naturally develop, start with a proto system.
At the right distance from the star, a plant like entity forms (or is seeded). It is sticky enough to gather grains of dust (or it starts out on a pebble sized chunk). Since it uses photosynthesis, surface area is important. So accumulated grains of dust will be transported to the edges of the plant (I'll just call it a plant and let a xenobiologist quibble about it's name). If pieces break off, they will likely remain in roughly the same orbit but will spread out to form a ring. Also, the plant would spread more in line with the orbit because growth in that direction is more stable; again promoting a ring. As it gets bigger, it forms its own gravity well, drawing in more dust.
Once a ring is formed, it can no longer grow along the line of its orbit and can only spread out forming a spherical shape.
The main problem is that the the sphere will have a hard time remaining solid. The forces are a lot less in the orbital plane. You may end up with rings moving at different speeds or with something like Dyson's "cluster sphere" where multiple round plants are all orbiting the star at roughly the same radius but on different orbital planes. If you have enough of these plants, it would appear solid from a distance.
The plants, once formed into disks wouldn't have to remain in orbit at all. They could use their surface area and mass to balance the push of the solar wind with the pull of gravity. In this scenario, solar CMEs may push plants out of orbit where they will become seeds waiting to find another star.
In any case, a nova will blow these plants all over the place and seed the nebula with seeds. Newly formed stars in that nebula may form with their sphere seeds already present.
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If it's a naturally occurring Dyson sphere, best bet might be a super early solar system. Your biggest constraint here isn't light or radiation (problems that can be exobiology-ed away), but nutrient inputs: even the most alien plants we can dream up need some physical matter to build with in order to be plausible. For earth plants, that mostly means carbon and nitrogen [EDIT: oh yeah and water lol], but also lots of other essential macro and micro nutrients. So you need lots of matter but it can't be locked up in planets, because that would be of no use to your space-bound plant sphere.
What you need is some space dust:
[](https://i.stack.imgur.com/1Mpx2.jpg)
The organism that created the sphere either evolved very early on in the history of this solar system, or it's a visitor from elsewhere. Before planets had time to form, this organism colonized the clouds of tiny asteroids that orbited this sun, linking the dust together with intricate root/vine networks. Millions of years later, when a typical solar system might have formed planets, the constant growth and activity of these plant-like organisms have kept the majority of matter in the inner rings of this system in a continual state of erosion. Plants are historically very good at defying gravity, after all.
I don't think this would form a complete sphere - more likely a thick ring (see image of space dust). Still could be pretty cool beans. Perhaps surprisingly, the formation of the planets in our solar system (millions of years) was a relatively quick event compared to the evolution of our world's current biodiversity (billions of years). So you have a lot of leeway in deciding how diverse you want this world to be: is it mostly a monoculture of that very first alien organism to enter the system, or is this a vast ring-world jungle with diverse animal life?
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I am starting a theorycrafting thread in a video game forum. It deals with the creation of a Hegemony created by the descendants of a colony ship that was cut off from returning to Earth (wormhole collapse) and needed to establish themselves in a new part of space.
Link to the thread found here: [Artemis Theory: The Artemisian Hegemony](https://forums.robertsspaceindustries.com/discussion/324564/artemis-theory-2-0-the-artemisian-hegemony/p1)
What would be an appropriate growth rate for a space-faring civilization given the following parameters:
1. Nearly fully functioning/intact colony ship upon arrival at destination (85%-90% intact) containing all necessary equipment and supplies to establish a colony
2. Unable to re-establish contact with Earth or other Earth Colonies;
3. Tech level: Space-faring (no warp/ftl capability but ships can travel at 0.1 c), maintain level of technology consistent with humans in the year 2232 in regards to medicine, agriculture, research, manufacturing and processing.
4. Time period for growth: Approximately 600 years
5. Encountered Predatory Species, Diseases, Social Unrest: Low to moderate chances. Colony would have been cut off so probably would have taken an isolationst stance; excellent medical preparation should keep disesase rates to average or below average; Due to nature of location colonists would have kept civil unrest to a low to moderately low state.
6. Starting population 5,000 people (sorry I knew I forgot something important)
Thank you in advance
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I don't think they'll retain their space faring technology for long. Modern space-tech is so complex there are only a few industrialized nations on Earth capable of doing it. Your population of 5000 simply won't be able to produce the raw materials, nor be able to maintain the high tech tooling required to maintain and repair their high-tech tooling.
Pick any modern convenience. Like a microwave oven. After a few years, it'll break. What do you need to build a new one? A magnatron, a flyback transformer, metal and glass plates, electrical components. What do you need to produce those? Fine tools, metalwork and glass for the magnetron. Vacuum pump. Fine, high purity copper wire for the transformer, iron, steel. This requires mines, ore smelting, purification. Fabrication facilities. Smelters and kilns. What do you need to make all those? What tools do you need to make those tools?
So stuff will break, and the tools to repair things will break, all the machines the colony starts with will break, they will run out of duct tape. How do you make new duct tape? And so the society will slowly slide backwards until an equilibrium is reached with what they can reasonably produce and sustain themselves. Sustainability is the key thing here, anything the colonists bring with them won't last long, only the things they can constantly produce themselves will matter after a few generations.
Where is that equilibrium point for a society of a few thousand? Probably living in mud or stone huts, dressed in animal skins, using tools made from bones and pointy rocks, malnourished, hunting animals or working 18 hours a day in an iron mine, and dying at 30.
The modern society tech tree is *extremely* large with massive inter-dependencies. It takes a population of hundreds of thousands, maybe millions, before it becomes economically viable to produce things like industrial weaving machines and internal combustion engines. In a resource and food rich land (best case scenario) your colonists would need to focus on survival and breeding, and over many generations increase the population to millions before there is time over so they can start to support specialized professionals like metalurgists or chemists or electrical engineers, which is when technology really starts to take off. Until then its just a very, very long slog through the mud (a few tens of thousands of years if our own civilization is anything to go by).
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I think that the fact you stated that it is a "colony ship" auto-negates the "omg! Decay to the stone age in ten years!" scenario. A COLONY ship would be equipped to establish a COLONY. That means it wouldn't be packed with the 23rd century version of ignorant valley girls and frat boys. Look at the training modern astronauts have to go through just to float above earth for a bit and maybe spacewalk. I'd wager that a colonist would be a mid-late 20s fertile individual who, regardless of sexual orientation, aggrees to participate in manual population growth until fertilization clinics can be established AND has completed the equivalent of a doctoral course including:
Survival,
Psychological toughening,
Technological interrelated history (like the old tv show "Connections" but on a much deeper level),
Staggered specialization (medical, mechanics, applied sciences, etc. And each colonist would have a primary specialty),
Overlapping familiarity with several other specialties.
Likewise, the colonization process would be planned, not improvised:
The colony ship would probably be designed to at the very least be cannibalized for shelters and machinery construction, if not designed to permanently land and become a small city/fortress at the colony's core once scout craft found its landing site. The ship's reactor would become the planet's first power plant. Engines vecome turbines to generate additional power or perform rapid excavation. Birthing becomes sheltered lodging. Hydroponics is now a giant greenhouse with preestablished familiar flora. Medical bay is an instant hospital . . . you get the idea.
After initial food, shelter, and safety are started, the very next project would be population control. Long before they boarded, each colonist should have a paired mate, and the couple assigned a place in rotation for reproduction. Especially once they know they have been cut off from emigrants/reinforcements, breeding becomes a matter of the group's survival, and would be kept as a priority at least through the first generation.
Your 5000 arrivals would likely close to double their number (each couple having roughly 4 children in a span of 10-15 years of remaining fertility is not unreasonable if it is a focus of the group as a whole). After that, population would still probably be at least that of 19th century England. Another part of that preparedness would probably include the medical knowledge of now+200 years having packed along some rather reliable fertility treatments.
Add to that the fact that your colonists could easily have the knowledge (or have come up with it in another 600 years) to create cloning facilities and artificial wombs . . .the 12 million estimate is conservative. You could just about make them have spread to numerous sub-colonies by now, and could number in the 10s or even hundreds of millions.
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There's 2 factors you need to consider:
1) What are the resource limitations of your colonies? On Earth humans have basically reached the point where carrying capacity doesn't really apply in the short term (long term problems like global warming are still an unknown, but I suspect modern technology will be enough to prevent a population collapse). In space you need to worry about rationing spaceships and food, which really comes down to the initial colonies industrial base (aka, how quickly they can build more colonies). Here there's really no theoretical limit, as most of the factories will be automated at that point. Plus on earth like planets there's not even those constraints. Ultimately it's just a matter of how much they prioritize making new colonies vs, say, making barbecues, toys, and space cars.
The only big limiting factor is growth will have to stop during interstellar travel (maybe they freeze everybody), but when they arrive exponential growth can continue. This travel time delay would basically be just that, travel time, nothing more (assuming they start near the middle of the galaxy, crossing it would take 50 million years ish, but that's an engine problem, not a population one).
2) The real limiting factor for a modern society is the number of children people choose to have. In much of the rich world population is going down because women (and men) would rather focus on education and careers than having children. Presumably an advance space faring society would face a similar issue, and could possibly never even expand beyond their colony. Niger has the world's highest fertility rates at the moment at 7.6 births per woman. With that kind of growth, and a society focused entirely on expansion, then you could have a population be ~1000x larger every century, continuing exponentially. However, this is unlikely as they probably wouldn't want to have that many kids. Really it depends on their society though, is this 40k or Star Trek?
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**Peaceful scenario: 600 000.**
**Action scenario: 12 million.**
Modern history shows that birth rates decline towards replacement level when things are going well. Picking a typical post-war western growth rate of 0.8 percentage per year, we get 600 000 people from a starting population of 5000.
A more interesting scenario is where there is something causing people to have more children, in the face of good or at least increasing levels of health care. The population of England grew from 8.3 to 30.5 million people between 1801 and 1901, giving a growth rate of 1.3 percentage per year.
That is: 8.3 \* (1 + 0.01309)^100 = 30.5
If we apply the same growth rate to your scenario, we get 12 million in 600 years.
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**Too many variables, I'd say: 250.000 citizens**
There's no telling how human technology will evolve in the next 200+ years.
We went from the first mass produced car (Ford Model-T) to walking on the moon in 60 years.
Many jobs will get automated over the next 50-100 years, robots already fill our factories, and as time passes [they](https://en.wikipedia.org/wiki/Atlas_(robot)) will become more and more sophisticated.
I don't think that, as state in other answers, resources will be a major hindrance.
Usually a colony ship doesn't return to earth, and you don't start a colony if you can't provide it with resources or the knowledge to acquire them independently on its destination planet.
Especially since interstellar communication is almost like time travel (very difficult to achieve effectively), a colony will need to be self sufficient right from the start.
In the end, as stated above, there are too many variables for me to give an educated answer. But...
I'd say, since it seems a pretty nice planet they found and 600 years are more or less 24 generations, that there could be more or less 250.000 people living there after that time period.
This means that every colonist will have at least 2 children by the age of 25, which will then have 2 children on their own, and so on...
**BTW**, if your colony starts with only 5000 people, and will never get immigrants from earth, then **you will get [gene pool issues](http://www.popularmechanics.com/space/deep-space/a10369/how-many-people-does-it-take-to-colonize-another-star-system-16654747/)** after a while.
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Considering the comments about a colony degrading technology wise, I would use the growth rate of the New England Colonies. Wikipedia gives the rate of 3% per year for births, and 1% per year from new emigrants.
Having women bear children, for the sake of the colony, probably won't 'sell'. But if the space colony was like our American colonies where your retirement plan was having enough children to support you in your old age, then having children is very important.
Although having a child takes a woman out of the workforce, for a while, the workforce will be dominated by low skilled, manual labor for several generations. Expect to see men and women working on the farm with babies on their back.
Preschool and Kindergarten will be replaced with chores and growing responsibilities. Children will have to work the farm and help their parents with some cottage industry after dark. When the colony grows to the point to support factories, expect children to be there too.
<https://en.wikipedia.org/wiki/Demographic_history_of_the_United_States#Earlier_Colonial_era>
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Starting population of 5000 - I will assume 2.500 males and 2500 females, all heterosexual and under 30 years old.
A woman can have one child per year - so in theory your 2500 couples, can have one child every year.
I will assume that in first year, no children will be born - colonist will be focused on setting up the colony and obtaining constant supply of food and water.
From second year on, after colony is stable, we can assume that most couples will try to have a child (lets say one, ignoring twins). Since not all attempts will be successful (natural births only, no extra medical assistance), we can assume 1000 newborns out of 2500 possible.
That's 20% increase by the 3rd year (at minimum).
After that, it depends on your society. If you keep similar to modern western societies, the original couples will stick to 1 or 2 children on average. If you have them simulate old America colonization, or even medieval Europe, then each couple can have 5 to 9 (or more) children - these societies depended on new children for growth (not to mention that there was no tv or internet then).
Also, as your colony grows, so must your food production and water supply.
I think for a starting colony 2-4 children per couple will be acceptable.
This rate will drop to 1-3 for second/third generation settlers.
With that in mind you will have an estimated average population growth of 30%-40% for your first generation colonists.
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In a scenario I am building, the vikings settlements in Newfoundland flourish, but only for a bit under a century. After that, the colony in Greenland disappears and the colonies are isolated from the homeland. Obviously even 11th century Vikings would bring advanced technology and discoveries like horses and metallurgy and of course they would still bring disease.
What I'm wondering is how fast could viking technology spread in the new world before Columbus comes in 1492? Could the technology spread to the empires of Mesoamerica and South America?
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In the real history the Norse colonists were too few and came from a much too poor mother country. But, however improbable, it is not completely impossible to imagine an Amerinorse empire taking off and eventually meeting the meso-american confederation/city-states/empire (depending on when exactly they make contact).
However, not from Newfoundland. Newfoundland has no natural resources which could be used by early medieval sea farers. It would be better to have the son of Erik the Red (or somebody else) lead an expedition to the south, find Manhattan, and establish a colony in a more favorable place. Then arrange for a decent number of Norsemen to come over, and make sure that they don't repeat the mistakes of Normandy and Russia and bring sufficiently many Norse women to ensure the survival of their language and culture. You may also want to arrange to bring over the most illuminated and mentally flexible Norsemen possible, so that they establish good relationships with the locals, and set up a thriving economy.
After 15 or 20 generations they may make contact with the Aztecs. (The Incas are way too far away, unless you make your American Normans develop navigation tech much faster than Europeans.) The whatever meso-american empire they meet was in the *stone age*. They hadn't even invented *the wheel*. The contact between the Amerinorse and the meso-americans would have probably led to the fall of the stone-age empire. Then Columubus arrives, then Cortes, but instead of a stone age empire he finds an Amerinorse empire which would repel his expedition with ease.
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[Question]
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**By [using antibiotics too frequently](http://emerald.tufts.edu/med/apua/about_issue/about_antibioticres.shtml), some argue, we're setting the world up for a pandemic that we cannot treat.**
Every time an antibiotic substance is used, the bacteria that survive reproduce.
Every time the new ones are introduced to stronger antibiotics, those that survive reproduce again.
Through this type of selection, as well as [horizontal gene transfer](https://en.wikipedia.org/wiki/Horizontal_gene_transfer), subsequent generations of bacteria grow stronger.
After years of this process - notably in densely-packed farms with little hygiene - we're left with bacterial infections we have no way to treat.
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**Hold on**! We might not be able to treat these bacteria, but they've existed for quite some time; things seem ([mostly](https://www.wired.com/2014/12/oneill-rpt-amr/)) fine. None have, as of yet, become pandemics - `prevalent over whole countries or the world`. I want to know if claims that the *world* could face the consequences of resistant bacteria are credible - or if isolated incidents do not compensate for years of evolution in order to spread rapidly.
**Is there a realistic path from drug resistance to pandemic? Is there any evolutionary reason why or why not this could occur?**
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**The concern is not that a single species of bacteria become pandemic, but the genes which provide resistance to antibiotics becomes pandemic.**
It's not that E.Coli is going to take over the world, but that all those small outbreaks of disease we can easily contain to one patient, or at least one wing of a hospital, can no longer be contained, and we're back to the bad old days of ships being left at sea in quarantine, entire cities being wiped out by cholera, flocks of livestock dying of disease, etc.
**Intensive farming itself seems to be the scariest worldbuilding scenario for this type of pandemic.** Flocks or herds which may have numbered in the tens or low hundreds now number in the high hundreds or thousands. Destruction of a single farm used to mean that family was in trouble; now it means an entire city could be in food trouble.
So, while I don't see a plausible way for a single **bacterial** disease to become pandemic, I can imagine a situation where, over the course of a couple of decades, constant antibiotic use has caused the genes for antibacterial resistance to become pandemic, brought around the world by gut flora in humans and farm animals, incubated, tested, and proofed in the digestive systems of the entire planet.
**Taking this as a worldbuilding question for storytelling and not a scientific question, because I am not a scientist:** I would have a rolling snowball of minor outbreaks of antibiotic resistant bacteria start to pop up all over the world. Salmonilla grabs a resistance gene in France and starts causing problems. Cattle farms in Texas are suffering lost stock due to a disease the vets are struggling to contain, causing the price of beef to skyrocket. Pig stocks in China are being decimated by a disease and the state is putting price and travel controls in place to stop the spread.
The world in this story would start to crumble not from one massive infection, but by death by a thousand cuts, as our modern society of high-density farming and cities struggle to handle these vicious attacks which can no longer be contained easily.
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I am not that flavor of scientist, but from what I've read and discussed with those knowledgeable, there is at least one realistic mechanism, namely <https://en.wikipedia.org/wiki/Bacterial_conjugation> Some scientists are worried about widespread use of antibiotics in raising food animals (chicken, swine, cattle) puts us at risk; <https://en.wikipedia.org/wiki/Donald_Kennedy> is one who sounded the alarm in the US and tried to do something -- only to by stymied by agribusiness interests.
Where might this happen? IMHO, especially likely where chronically-antibiotic-treated animals were raised or slaughtered -- and specifically places where biocrud goes and isn't sterilized. A plague-infected rabbit gets washed into a manure lagoon (yes, those are a thing!)? Similar rats get into some spilled slaughterhouse waste, when a garbage truck overturns? It could be happening right now.
Tuberculosis is becoming increasingly antibiotic resistant. As is, tuberculosis isn't very transmissable. If that were to change for a viable sub population of one of the existing antibiotic-resistant strains of TB, we could be in for real trouble, especially in crowded cities.
OT: I think it's absurd that agribusinesses can buy these chemicals by the ton (making me less safe), but I can't buy even gram quantities (just in case), without finding a doc who will prescribe them to me.
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**No, it wont happen**
When I pushed you for definitions of "prevalent," the answer you gave was "...at least 50% of the country and / or world is affected." Based on that definition, we wont even get close to that bar.
To look at how it could go, we can consider the flu. The flu is notoriously hard to vaccinate for, and gets transmitted every year. It can also kill, though typically only young and old and weak. However, the [1918 flu](http://www.history.com/topics/1918-flu-pandemic) is seen as an exception:
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> The influenza or flu pandemic of 1918 to 1919, the deadliest in modern history, **infected an estimated 500 million people worldwide–about one-third of the planet’s population** at the time–and killed an estimated 20 million to 50 million victims. More than 25 percent of the U.S. population became sick, and some 675,000 Americans died during the pandemic. The 1918 flu was first observed in Europe, the U.S. and parts of Asia before swiftly spreading around the world. Surprisingly, many flu victims were young, otherwise healthy adults. At the time, there were no effective drugs or vaccines to treat this killer flu strain or prevent its spread. In the U.S., citizens were ordered to wear masks, and schools, theaters and other public places were shuttered. Researchers later discovered what made the 1918 pandemic so deadly: In many victims, the influenza virus had invaded their lungs and caused pneumonia.
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50% is a really high bar for a disease that does serious harm to a species. In general, we're pretty good at defending against diseases that are deadly. As we see here, even the worst flu pandemic in history only got to about 1/3 of the population.
That being said, you can see why others put the bar far lower than that. A disease that killed 20-50 million people is frightening enough to cause changes in behavior. Those behavioral changes typically stymie the pandemic faster than any drug ever does.
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# Not really
The risk isn't about pandemics, they're normally viral as bacterial infections are, on the whole, not as contagious.
The risk is about things that are currently minor no longer being treatable. Antibiotics are given as a matter of course to prevent post-operation infections for example.
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> The use of antibiotic prophylaxis (both intraoperatively and postoperatively) is accepted as the gold standard in orthopedic practice and is recommended by the most widely accepted consensus-based guidelines. -<https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4596117/>
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It's this sort of use of antibiotics that's being threatened by resistance, increasing the risk of operations that are currently considered routine and setting back modern medicine by a couple of generations, not a pandemic of [TB](http://www.nhs.uk/Conditions/Tuberculosis/Pages/Introduction.aspx)
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> TB is a bacterial infection. TB that affects the lungs (pulmonary TB) is the most contagious type, but it usually only spreads after prolonged exposure to someone with the illness.
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> With treatment, TB can almost always be cured. A course of antibiotics will usually need to be taken for six months.
> Several different antibiotics are used because some forms of TB are resistant to certain antibiotics.
> If you're infected with a drug-resistant form of TB, treatment with six or more different medications may be needed.
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**Yes, it seems to me the two things are obviously related.**
Evolution adapts life to its environment, including any other lifeforms.
Many of these lifeforms compete for resources (food, space, you name it).
If life form A is unable to adapt or compete with life form B, it will disappear in one way or another.
Bacteria are everywhere, and some are a threat when our immune system is unable to cope with them, allowing them to reproduce unhindered inside of us. Science allows us to vastly enhance our survival rate when coming in contact with large numbers of those bacteria.
Since not only our immune system is attacking those bacteria, the evolutionary pressure on those bacteria is also increased.
This essentially means that we are strengthening the bacteria that survive, much more as if our immune system alone would fight them.
As long as we retain the upper hand, as long as science is able to come up with new ways to kill bacteria that get stronger every year, we are fine.
But...if this process will ever come to a relatively sudden stop, we're going to have a major pandemic on our hands. Our immune system is not used to such resilient bacteria, and will probably have zero chances against them.
You can see this already happening all over the world.
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> 480 000 people develop multi-drug resistant TB each year, and drug
> resistance is starting to complicate the fight against HIV and
> malaria, as well
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[Source](http://www.who.int/mediacentre/factsheets/fs194/en/)
AFAIK, the big problem is that, as of now, mankind has no way to **efficiently** create new, stronger, antibiotics. One big leap in that direction would be nano-technology (still 50 or so years away), which would enable us to create antibiotics that are easily reprogrammed to adapt to new kinds of microbes.
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The scary problem isn't necessarily the microorganism developing the drug resistance, but what ELSE it might pass that resistance to! Bacteria and viruses are notorious for crossbreeding with other related organisms. So if we make a staph bacteria resistance to every type of drug, can it pass that resistance on to something more contagious or lethal? This is of particular concern when animals are heavily dosed and are in tight confines with humans or other species, then you get cross species microorganism jumping. This is how the flu starts every year, jumping from the bird reservoirs into humans. H1N1 is another example, it contains parts of the flu that are normally found separately in birds, people, and pigs.
So a highly infectious, but not particularly lethal, bug might get increased lethality and drug resistance from other microorganisms, which would then turn it into a good candidate for a pandemic.
But the more likely outcome is that we just can't treat nosocomial (hospital acquired) infections folks pick up when they get a surgery or have to stay in the hospital. This would be bad for individual patients, but wouldn't create a pandemic as these drug resistant bugs don't normally get transmitted from person to person very easily. Multi-drug resistant TB would be a problem as that is contagious, but TB isn't very lethal, at least not in the short term, so quarantine could be a solution (basically we'd be back to dealing with TB like we did in the pre-antibiotic era with sanitariums).
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Bacteria might exchange genetic code between DIFFERENT SPECIES OF BACTERIA. They share a plasmid, a small fragment of DNA code that might allow it to synthetize a certain protein or group of proteins responsible for resistence to a certain drug.
If some bacteria resists vancomicyn but does not resist tetracycline, while another one resists tetracycline but does not resist vancomicyn, they can BOTH share plasmids and give one another the resistence they lack. From now on, both lineages of different bacteria kinds can resist two of the most powerfull antibiotics in existence. Add a third bacteria and so on, and you get a super-powerfull bacteria.
Not only that, but they can share virulence genes. Virulence is describes how powerfull a certain microoganism is at infecting people. So, if a bacteria that is not a lot virulent, but resists a good ammount of antibiotic classes, meets a very virulent bacteria that has low resistence, theres a chance that they will share plamids and become both virulent and RESISTENT. Thats the recipe to a pandemic.
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My story is set in an abandoned medieval castle. I am having a hard time describing the effects of time on the place.
What would happen if a place gets abandoned and neglected across the years?
What could be the effects on the furniture, roofs, and walls, after 6 months, 1 year, 5 years, and 10 years?
To draw comparison with our world, the castle would be fully functioning in the 14th century and abandoned thereafter. Furniture and structure elements would date medieval technology.
We're assuming normal earth-like central-European weather conditions.
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Probably the first thing which would happen is that people would break in to loot any portable items as well as the obvious valuables like furniture etc abandoned buildings have historically been informally demolished over time as a source of building materials. In this case doors, flooring and roofing would probably be the first to go. Indeed it is not unknow for lead and copper to be stolen from roofs while a building is still occupied.
An interesting real-world example is the [dissolution of the monasteries](https://en.wikipedia.org/wiki/Dissolution_of_the_Monasteries) in England, begun under Henry VIII. In this case most of the portable assets were confistacted and sold and the lands redistributed. In some cases the Monastary buildings were demolished or converted to other uses and in others just abandoned.
[Fountains Abbey](https://en.wikipedia.org/wiki/Fountains_Abbey) for example was stripped of timber, lead and some masonry was reused but a lot of the stone st ructures are in reasonable condition even now.
In terms of structural integrity entirely stone structures can survive for a long time whereas anything with significant timber elements especially in floors and roof will potentially decay a lot more quickly once the interiors are exposed to the weather.
In practice it is rare that a building is abandoned and left entierly undisturbed. But if it was a well consructed medieval building should last a long time before it really starts to decay. A fact attested to by the fact that many medieval churches and cathedrals are still standing. If you have a building with stone walls and an oak and lead roof there isn't actualy that much which can happen to it.
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I'll try to answer in terms of time frames, since you asked about that specifically.
(If you haven't seen it yet, [this answer](https://worldbuilding.stackexchange.com/questions/47097/how-long-would-a-medieval-castle-last-after-people) may be of help to you.)
It sounds like you're envisioning a scenario completely devoid of human influence post-abandonment -- no looters or squatters or whatnot? Left unchecked, first the natural environment will move back in *very* quickly. Within a few months, any nicely-pruned grounds will have long lost their kempt appearance, and in only a couple of growth seasons the foliage will be clearly overtaking the walls. Animal life will move in essentially immediately.
[Here's a neat article](http://www.dailymail.co.uk/news/article-3759263/Eerie-photos-Cairo-Illinois-abandoned-city-Mississippi-Ohio-rivers.html) illustrating this in a town that is still even occupied.
Structurally, the stonework will last centuries; medieval castles continuously visited by tourists today are still intact with minimal (if any) maintenance. The rate at which any wooden constructions will rot away depends on several factors, such as climate, insects, and wood-loving fungi. Wood can last a long time if weather isn't a factor (in the more extreme cases, there are wooden tombs thousands of years old still standing, not to mention the wooden items like furniture and decorations inside). A fully intact, well-maintained roof suddenly abandoned will likely last at least two decades or more before any large problems begin to manifest. Such a roof could potentially stay more-or-less structurally sound for at least a hundred years; the main beams themselves could last a couple hundred, perhaps more. None of this takes into account severe weather or fire, of course.
Anything left undisturbed inside dry rooms will stay in good shape until exposed to the elements (which will happen, eventually).
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I'm writing a story about Earth before the industrial revolution, but without continents, where all the countries are placed on separate islands, and all of them are extremely isolationist and xenophobic. They kill any foreigners that steps on their land, and the navy sinks foreign ships sailing near their coast. Any citizen that leaves their home country or has a relationship with a non-citizen becomes rootless.
The trade between countries is done by these rootless, who are allowed to dock in designated ports, and trade their goods. Each country allows only short stays. Rootless are not allowed to buy property, and leaving the gateway port or overstaying means swift death. If a child is born from a rootless parent it becomes rootless itself.
I'm having trouble how would their culture look like? Especially how would women & young children survive if they have to move constantly.
The closest thing I could find in our world are [Moken](http://www.survivalinternational.org/galleries/moken-sea-gypsies)
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By the fact that everyone else in the world keep their distance from them, these rootless would necessarily have to rely on each other (maybe having zero or few internal factions or tribes), thus creating a society of their own, with laws and traditions that are theirs (living only at sea changes your culture), but with influences by all the cultures of those expelled from mainland. Thinking about it, maybe being always at sea allowed them to explore more of the world, and find an unclaimed island to live on and keep secret?
Addendum: Instead of an island, they could have one or more floating bases or cities, built from scratch or connecting several ships.
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You can expect very close-knit communities formed around a single ship. Those ships would trade between each other and actually would potentially end up quite wealthy as they are the only way for trade to happen between the various islands.
However the lack of any fixed abodes would make it hard to spend that wealth, and keeping it on boats would be very risky. This is particularly the case if there are certain times of the year where storms are more likely.
It's entirely possible that the Rootless would follow "good weather" around in a migratory fashion, for example heading south during the northen hemisphere's winter, then north again once summer has returned.
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I'll make fallowing assumptions that I hope are in the spirit of the question:
* Any country has [Green-water navy](https://en.wikipedia.org/wiki/Green-water_navy) much stronger then Rootless
* All the useful land is already taken
* Rootless aren't allowed to own any land
I expect a very close knit community centered around a life in a ship. Since Rootless don't have to compete with the [states](https://en.wikipedia.org/wiki/Dutch_East_India_Company) on overseas trade I expect many of them to do quite well. They're not allowed to own any land so they would spend their money on ships. The wealthiest families own 1000 tons Carracks, manned by hired hands, the middle own Caravel which they sail themselves & the poorest work as hired hands. They spend most of their life on the seas while travelling the merchant routes. Since no country has blue water navy, piracy is problem in many areas, so their ships are armed.
Life for the families would be hard on the sea but since the ships don't carry any passengers, there will be enough accommodation for women & children. I think the hardest problem is the drinking water and scurvy. Lack of vitamin C killed more men then battles. In fact of the 184,899 sailors enlisted by Royal Navy during the Seven Years' War, 133,708 died from [Scurvy](https://en.wikipedia.org/wiki/Scurvy).
The Rootless would quickly learn to run clean ship, under strict discipline and frequently resupply with fresh food & water.
The other thing is risk, the sea is unpredictable for Sail Age technology, I expect parents to not want to put all their children in a single ship. When the children grow up many will leave their families to sail the world on other ships, and who knows maybe one day own one themselves.
Good eye for a trade, knowledge of customs and cultures of their customers, and most of all accepting their fate as child of Poseidon, would make for a race quite unlike the land dwellers.
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My friend created this world that's exactly like the real world, except with a new nation occupying Greenland. He made it so that the nation is ran by a "communistic oligarchy" where a small group (1000 or so) people called "the Grey" gather pretty much the entirety of political power and share a common pool of money and resources, including weapons and automated combatants (in case human soldiers are too hard to control).
When I asked him what keeps the oligarchy from splitting into small subgroups that try to seize complete, dictatorial control, he just said that the oligarchy practice some austere religion and only take members from the practitioners of that religion, which means the Grey are all ideologically processed to have no motivation of seizing power.
I don't see how the system he set up isn't going to be infiltrated by people who just want power and passed the religion exam, or how a small group of ideological extremists can monitor one another's ideology, not to mention that a nation controlled by an explicitly oligarchical group of rulers may not be possible in the first place.
I suspect that extreme ideology is just a lazy explanation for complex human behavior not explicable otherwise. So I am interested to know if this kind of hand-wave had appeared elsewhere in works of fiction and whether or not it is inherently deleterious to the quality of a fictional world.
[Answer]
The short answer is yes. It's easy to see places where a theocracy's laws are intensely entwined with its religion. Your argument about infiltration is a complicated one. You could make that argument about any religion, but you see very few religions derailed by an infiltrator. When was the last time you saw a non-devout pope? While it's hard to make any hard and fast proofs that infiltrators don't occur, you have to admit that nearly all religions do an incredibly good job of keeping them out.
However, your friend should be aware of [Sanderson's First Law of Magic](http://brandonsanderson.com/sandersons-first-law/):
>
> Sanderson’s First Law of Magics: An author’s ability to solve conflict with magic is DIRECTLY PROPORTIONAL to how well the reader understands said magic.
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As it turns out, Sanderson's law also applies very neatly to all sorts of not-quite-magical-yet-still-fantastic situations. Your friend's "austere religion" behave remarkably like magic in a book. Thus, it is wise to apply Sanderson's First Law. The more conflict your friend resolves with this religion, the more readers are going to have to understand it. He's going to need to flesh out the kind of questions you are asking, like how they avoid infiltrators. In the end, the act of framing that religion properly may actually provide a great deal of insight into the human condition, and be a valid reason to explore this world on its own.
Also, your friend may need to explain how those 1000 people avoid political gridlock. If the answer is religion again, that becomes another example of conflict that he's resolving with it, so it will call for an even more in depth understanding.
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The answer to your question is yes. As for examples they’re too numerous to count but extreme ideology is pretty much a method an author uses to explain some that about society that otherwise wouldn't make sense. This doesn't mean that this method is a bad thing. All fiction require some level of hand waving in order to make sense and it is based some what on real life, so as long as your friend doesn't over do it every thing is fine.
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Even if there is a way of ensuring that the people who are put on the leader track are truly faithful (which is hand-wavy enough as it is), there is still the problem of making sure that the people who pass this test don't lose the faith as they go along.
Remember that if the leadership has been practicing any deception of the plebes, at any point in its history, people moving up in the ranks will have to be let in on the secret. The ones who were in it for power all along will happily move on with their lives and schemes. The ones motivated by genuine faith will retire. The others will become cynical and decide to stay in power and keep the perks.
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**Closed**. This question is [opinion-based](/help/closed-questions). It is not currently accepting answers.
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What can he do with his knowledge of 21st century science and engineering to shift the tides of war in Germany's favor? Saying "help them build a nuke" isn't allowed (because it's way too obvious).
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### Accidental or Intentional Travel?
If your story is about a weird event with an accidental victim, the question would be if the scientist *wants* to help the Nazis and if the Nazis want to accept help. A guy/gal without papers? Strange speech patterns with lots of English words and even grammar? The Nazis murdered Germans with disabilities because they didn't want to care for them, what will they do to an obvious madman who may not be German after all?
A bad guy in a story might want to time-travel intentionally. Somewhere between 5% and 20% of Germans have *some* right-wing, xenophobic political opinions, fewer aer outright Nazis. A non-German character would be another possibility, some sort of white supremacist. So what can the time-traveler bring?
Another question is when the time traveler will arrive. 1923? 1933? 1943?
* The time traveler will need something that works quickly to prove his bona fides and get the cooperation of the government. Memorize the location of some post-war Germanic archaeological finds which can be dug out by hand if necessary, that'll get him the ear of some bigwigs.
* Books with embarassing information on historical leaders. Who can be blackmailed?
* [Naked on arrival](http://tvtropes.org/pmwiki/pmwiki.php/Main/NakedOnArrival), only what he has in his mind. If he arrives early enough, memorize some engineering breakthroughs. Transistors? Radar? Air-independent propulsion for submarines?
* If he can bring a couple of suitcases, blueprints for the AK-47, the T-34, the Leopard I tank, the Mig-15, the B-29, the Type 205 submarine. A mix of things that can be done quickly and "stretch goals" for the future.
* Some books with *exact* locations of raw materials in Germany and beyond. Germany does not have much oil, but it helps if you know where to drill.
* A couple of books on modern management practice if the Nazis were prepared to put them into practice -- but they were a remarkably inefficient government controlled by personal relationships and special interests.
[Answer]
Sometimes the simplest answer is best. It doesn't require future science and engineering to turn the tide of the Second World War. The Germans only need to be told their [Enigma](https://en.wikipedia.org/wiki/Enigma_machine) code was cracked by the Allies and they should add some extra rotors to their Enigma machines and improve their signalling procedures.
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> Though Enigma had some cryptographic weaknesses, in practice it was German procedural flaws, operator mistakes, failure to systematically introduce changes in encipherment procedures, and Allied capture of key tables and hardware that, during the war, enabled Allied cryptologists to succeed and "turned the tide" in the Allies' favor.
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This of itself wouldn't guarantee a German victory in the Second World War, but it would be an effective first step.
Next he could advise the German High Command that their V-weapons rocket program was essentially a waste of time, money and effort. Werner Von Braun had told Hitler in answer to the Fuhrer's question that rockets were the equivalent of artillery and he could make them in their thousands. Instead they should continue their development of jet aircraft.
Thirdly, the scientist should present the German High Command with a comprehensive set of military histories of the Second World war.
However, the OP omitted to suggest when this scientist arrived in Germany to begin the business of changing the course of history. The time of his arrival will radically determine the outcome of his activities.
It is recommended that the OP and anyone interested should take a look at the excellent Czechoslavian time travel comedy-drama [*Zítra vstanu a opařím se čajem*](https://www.youtube.com/watch?v=tVBPNfKfgNo) or in English *Tomorrow I'll Get Up and Scald Myself With Tea* (1976). This involves taking suitcase hydrogen bombs back to the Nazis via a time machine. Yes the OP didn't want nuclear weapons, but you deserve the opportunity to enjoy one of the best time travel movies of all time.
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Such a scientist could:
* Tell them that the "code" used my America was a native American language and by that help "break" the code
* Tell them when and where important battles were to expect (D-Day)
* Tell them who are key persons who lead to the allied victory
* Help them build their jet fighter aircraft earlier
* Help them to build better radar systems earlier to better defend against bombers from GB
One of the main reasons the allies won the war was that Hitler was insane and always wanted bigger weapons despite those being useless and lots of other mistakes he made. This is something a single scientist would not have been able to change. Examples of this are the [Mouse](https://en.wikipedia.org/wiki/Panzer_VIII_Maus) and the fact that the first jet aircraft, the [ME226](https://en.wikipedia.org/wiki/Messerschmitt_Me_262) was used as a bomber not as an interceptor.
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In *Star Trek TNG*, you hear about some sort of defense back on earth that is supposed to screen out all the bad weather. In the episode "True Q," it is mentioned several times as being capable of preventing/stopping a tornado.
Obviously we can't do this today, and I realize we still don't understand much about how tornadoes even form. We might know what stops them though. **What would we need to do to stop/prevent a tornado?**
Clarity: This is science-based. I know we can't do this right now, so I'm looking for what we would need to cause. How we cause that is another matter entirely. (For example, maybe a drop in air pressure somewhere solves the whole thing. How we do that comes later.)
*Note:* This is not a duplicate of [this question](https://worldbuilding.stackexchange.com/questions/57705/what-would-we-need-to-stop-a-hurricane) on how to stop hurricanes. The method for stopping them could possibly be the same (I wouldn't know, hence the question) but the two phenomenons are, to the best of my knowledge, quite different in how they form and behave.
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If you have Star Trek level future technology, I propose stopping a tornado by disrupting the [horizontal spinning effect](http://www.universetoday.com/75695/how-do-tornadoes-form/#) in the lower atmosphere. This phase causes the spinning motion that is then lifted vertical by rising warm air into a funnel cloud (and then reaches to the ground to cause destruction)
When the spinning motion has formed and is detected, it could be disrupted by suddenly heating the area. Warm air will expand and disrupt the spinning pattern and break up the tornado before it can be lifted vertically into a funnel.
To heat the area rapidly, I would use a large, powerful, space-mounted infrared laser.
So you could stop tornadoes by flying a fleet of early detection satellites and powerful infra-red lasers in space. Lasers, what problems don't they solve?
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With Star Trek technology, this shouldn't be a problem I suppose however with Earth-like technology it may be possible in the near future.
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> 1. Recent research indicates that in order to form, a tornado needs both a cold, rainy downdraft and a warm updraft. To stop a tornado
> from forming, just heat this cold downdraft until it's cold no longer.
> And how would one do this, you ask? Simple: Blast it with beams of
> microwaves from a fleet of satellites. The satellites would collect
> solar energy, transform it into microwaves, and send a beam down to
> Earth. The beams would be focused on cold downdrafts, heating them
> like last night's leftovers. The European Space Agency has funded
> initial studies on building this type of satellite, though it hopes to
> use the satellites as high-altitude solar-power stations, not as
> weather modifiers.
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[Popsci](http://www.popsci.com/scitech/article/2003-07/how-destroy-tornado) This link also provides a potential answer(s) your other [question](https://worldbuilding.stackexchange.com/questions/57705/what-would-we-need-to-stop-a-hurricane).
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Tornadoes need warm water to form. Warm water in Earth's oceans, when available, is a relatively thin layer over colder water. As a whole, ocean temperatures are low and stable.
Hence, **increasing the mixing of water in Earth's oceans would prevent tornadoes**, by decreasing the availability of warm water.
Imagine a gigantic floating vertical cylinder with an open top and an open bottom. Barely floating actually, mostly submersed with the rim just over the surface. Waves will crash at the rim, pouring warm water into the cylinder. The rising water column will pressure some water down from the cylinder bottom. There, mixing increased.
I have seen this years ago in some news article as a serious, if very outlandish, idea to prevent tornadoes before they form. Just churn out thousands and thousands of such cylinders. Unfortunately I cannot find the reference.
(If implemented, this is almost sure to have unintended consequences. Anyone who can imagine what they might look like, please share in the comments.)
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I´m pretty sure we are able to stop tornados. For a tornado to form you would need hot air on the ground and cold air up in the sky. (To put it very simply...)
To break the tornado, I guess you just need to either warm the top up, or cool the ground down. I suppose it´s better to cool the ground down, since heating the top up could just create a bigger tornado (I´m guessing here, but you would still have a hot lower part and a cold higher part, so that could go massively wrong). You could heat it up with a bomb btw, e.g. an atomic bomb.
A good way to cool it down would maybe be dropping high amounts of water on the path of the tornado. This could have two effects:
1. Cool the area
2. Give the tornado more mass (water) so it needs a bigger temperature difference to keep its rotational speed.
These effects would reduce the power of the tornado and in the end, stop it.
Don´t hate me if I made a mistake in my thoughts.
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On a certain planet, the sole continent of land is a large circumspecting ring about the equatorial regions, with a width averaging 500 miles. Rotational north and south are entirely pelagic. Various shallow seas exist on this continental stripe; some of these seas could join the surface layers of the two oceans. The planet is tectonically inactive, in that the mantle is unperforated and unbroken, and I suspect that it would be quite stable, barring some cataclysm.
Mass is roughly 1.5 times that of the Earth, and atmosphere is of mostly the same as here on Earth. Diurnal period, or rotation about its internal axis, is roughly 36 chronal hours with our SI units. Photosynthesis uses chlorophyll and soils are mostly the same as Earth also. In short, it is like a larger copy of the Earth with a different arrangement of oceans and land.
Its sole satellite, which is approximately one-third its mass and at slightly more twice the distance between Earth and Luna, orbit each other with nearly parallel axes.
Their axial tilt with respect to solar plane is approximately 28° arc. The parameters of their solar orbit is almost the same as that of the Earth.
The sun is Main Sequence, and lies somewhere between the G and K spectral classes.
Obviously my numbers are not precise yet.
Anyway, I expect that the large oceans would produce strong wind currents which would shift direction twice during the solar orbit, with the moist air causing seasonal variations of arid and soggy in some places as a result of the rain shadow. Otherwise, however, the climes should be mostly temperate.
What would be the climate equilibrium state, if any?
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Basic answer...not taking into account axial tilt and sun details etc. Just basic climatology.
**Landmass**
500 mile width. On Earth the distance between each degree of latitude is about 69miles. So on Earth, your landmass would average 3.5-4 degrees latitude either side of equator. On your larger planet, it would be less!
**Coriolis at the equator**
Earth rotates west to east, this rotation causes surface waters and winds to flow east to west.
Coriolis causes surface waters and winds to be deflected to the right in the northern hemisphere and left in the southern.
BUT, at the equator the is little to no deflection. We call it the 'doldrums'. So your coastal water currents will probably be fairly weak (if no other drivers can be found).
**Oceanic circulation.**
As mentioned by Palarran, there will be no complete ocean circulation. On Earth, all our oceans are connected and combines to create the thermohaline circulation. This transfers cold polar water to the equator and beyond and warm equatorial water to the poles. But I don't see why you can't have two separate thermohaline circulation systems.
Your planet has ocean from the poles to pretty much the equator (barring a few degrees). Your cold polar waters will extend alot further inwards than on Earth. Eg in the northern hemisphere the cold oceans are mostly barred by eurasia and north America. In the south, the cold currents have near free reign and have formed a large antarctic circumpolar current.
You will have two of these, North and south. But I believe it may be 'wider'. This will result in larger ice caps affecting air temperatures. The cold water will sink until it hits the ocean surface and then travel underwater towards the equator (you will need some sunken landmass to direct it there). When it reaches the equator it may rise and bring nutrients to the surface. See areas of upwelling on Earth.
Depending on how wide a continental shelf you have, your coastal waters will therefore be colder than expected. Shallow coast, weaker and warmer current; steeper shelf, stronger current influenced by the upwelling cold current.
Such a strong polar ocean current would also result in very little surface mixing with the water in the mid-latitudes. So thinking the problem through, you will have a excessively strong polar current and a very weak equatorial current. You may have a narrow third current between the two. A mid-latitude current. Where the equatorial and polar currents interact. I'd imagine it would be mainly driven by any atmospheric circulation as there will be no landmass to drive or focus the direction.
**Atmospheric circulation.**
I don't think it will be similar to Earth's hadley-ferrel-polar cell circulation. If it is, it will be a mutated version.
You will most certainly have a large strong polar cell. The polar cell has subsiding air at the poles and rising air at the polar front. On Earth about 60degrees.
With such a narrow landmass at the equator, you won't have a very strong zone of ascending warming air. Resulting in a weaker and smaller Hadley cell. This means that less warm air is going to be transported up into the upper atmosphere and down to the poles. Your tropics(where all the moisture falls back out if the sky) will also not reach to the 30 degree latitude and probably fall between 10-20 degrees (if that).
Your ferrel cell. This is where a very large amount of uncertainty lies. If it exists... Maybe just an interaction cell. Purely to exist to separate the cold polar air from the warmer equatorial air. It would be more of a buffer zone than an actual atmospheric cell.
**In summary**
I believe you have created a very cold planet. Your polar icecaps will dominant the weather. Most moisture will be locked in the salter than Earth's oceans and poles. The air will be dryer. It will rain alot on your equator landmass, as the rain band is that much narrower than on Earth. There will be strong polar winds. Storm surges onto your landmass probably won't be uncommon. Expect lots of coastal flooding in low-lying areas.
[Answer]
The state of your planet is unstable.
The two oceans will have different sea levels, and even more: One of the two oceans will raise at the cost of the other. The result will be sooner or later an overflow from the higher level ocean to the lower one, creating as a net result a channel between the two oceans (similar to the Bosporus between the Mediterranean Sea and the Black Sea).
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Ok, this is take two. Hopefully this is specific enough. I have a link to the original question [here](https://worldbuilding.stackexchange.com/questions/56920/what-are-some-possible-ways-a-civilizations-time-keeping-would-be-different-if).
And for those of you eager to see my sources for this, I'll link two videos here from the YouTube Channel *Artifexian*.
[Worldbuilding: Terresstrial Moons](https://youtu.be/t6i6TPsqvaM)
[Worldbuilding: Gas Giant Moon Systems and Habitable Moons](https://youtu.be/Evq7n2cCTlg)
I have a 6-planet solar system (only three planets have been fleshed out so far), with a purple gas giant in the Habitable zone. It has 3 Earth-ish sized moons: one small ice-covered ocean moon (like Europa), one swampy rainforest moon (like Endor/Dagobah), and one Desert moon with 60% of its surface covered in dry land. The desert moon's 'year' is 147 Earth days long, but due to the moon's rotation, it's actually more like 117 days long.
(*I'll put stats and numbers in comments, if any of you wanna recreate it in Universe Sandbox or stuff then let me know.*)
An intelligent species will inhabit the desert moon, the furthest one out. My big question is what are some possible ways they can create a calendar?
I've considered making the year based around the moon itself, but is it possible that they could see that their planet (the big, bright purple thing in the sky) orbits the sun (the big REALLY bright thing in the sky)? Or maybe they can tie time periods to the other two big moons?
(*P.S. The moon orbits at a sufficient angle and distance that regular eclipses aren't a thing, so if anything, solar and lunar eclipses would be about as regular as Earth's eclipses.*)
.....
Edit: here's the planet and moons' mechanics, per request. Units are given in terms of Earth. (Except for the planet, whose mass and radius is given based on Jupiter.)
**Planet 2: Purple Habitable Gas Giant**
Dist: 1.2 AU
M: 2.15 Mj
R: 2.89 Rj
g: ??? m/s^2
d: 0.88 g/cm^3
**Orbital characteristics:**
a: 1.2 AU
b:
e: 0.0038
i: 0.00028°
Ω: 83.2°
ω: 335°
Year: 1.3 Earth-Years
Moons: 7 (3 Earth-Sized)
**Moon 1: Ice World**
M: 0.74 Me
R: 1.01 Re
g: 6.93 m/s^2
d: 3.85 g/cm^3
**Orbital characteristics:**
a: 2,000,000 km (0.01336 AU)
b: ??? km (0.0 AU)
e: 0.027
i: 1.72°
Ω: 152°
ω: 20°
Year: 0.57 days (12.5 Earth Days)
It's icy because it formed with the gas giant out in the distance. It lacks any form of greenhouse gasses, and the surface ice reflects sunlight away, keeping it from melting fast enough. Tidal forces from the planet, though, keep it warm internally, enough to support a subterranean ocean.
**Moon 2: Endagobah (Swamp World)**
M: 0.76 Me
R: 0.92 Re
g: 8.85 m/s^2
d: 5.40 g/cm^3
**Orbital characteristics:**
a: 5,161,126 km (0.0345 AU)
b: 5,410,000 km (0.03 AU)
e: 0.0037
i: 2.45°
Ω: 98.5°
ω: 264°
Year: 42 days (55.4 Earth Days)
This place has bugs. Nobody'll go there anytime soon.
**Moon 3: Desert World**
M: 1.36 Me
R: 1.103 Re
g: 10.99 m/s^2
d: 5.59 g/cm^3
**Orbital characteristics:**
a: 10,500,000 km (0.0702 AU)
b: 10,499,112 km (0.0718 AU)
e: 0.013
Periapsis: 10,363,500 km (0.069 AU)
Apoapsis: 10,636,500 km (0.0711 AU)
i: 3.67°
Ω: 160°
ω: 98.0°
Year: 117.6 Days (147 Earth Days)
[Answer]
Just like there are multiple ways we could define days (solar vs. sidereal), there are many options available to the inhabitants.
**Solution 1: Bright=Day, Dark=Night**
Considering we base our days around the "bright/dark" cycles caused by the Sun, it is likely the moon inhabitants would as well. Assuming the host planet does not obscure the star for long portions of time, e.g. while the planet is between the moon and the star, the inhabitants will likely define a day similar how we have, i.e. start timing when the star is the highest in the sky and stop when it has returned to its highest point. This has many advantages. It ties their days to the brightest object in the sky (and most obvious). It likely ties the days to their circadian rhythm. It avoids unnecessary corrections to the days through leap hours or such. This seems to be the most intuitive, but there are other options.
**Solution 2: Relative to the Planet**
Now they could do the same thing, but using the planet, however this would cause the brightest light source (the star) to change it's height in the sky until its pitch-black at "high noon", when it was originally brightest. Or they may be tidally locked in which case the day would be infinite, which might be a problem for a work day. I would likely rule this out do to practical purposes.
**Other Solutions**
If they could observe the rotation of the host planet, they could define a day based on the host planet's rotation (or day) relative the star, but this is very difficult, since they would have to know the relative position of points on the planet to the star, independent of their own location in the lunar orbit. Precisely mapping the surface of the gas giant, or even the fact that it is rotating would be very difficult. I would rule this out due to the sheer difficulty compared to other options.
**Determining the Heliocentric Model**
It likely wouldn't be too difficult to determine that they are orbiting a planet which is itself orbiting the star, barring religious backing of certain moon-centric viewpoints. Since two gravitationally bound objects orbit their center of mass, there can be symmetrical views of which object is orbiting the other, and the case reduces to that of our solar system. Some intrepid astronomer(s) will eventually map out the relative positions of background stars, the host star, the host planet and the other moons over long periods of time and, given a rudimentary knowledge of orbital mechanics, would recover the correct answer.
**Months and Years**
Once you have solar days (using the dark and bright cycles caused by the star), it is easy to define a month from the rotation of the moon around the planet (or planet around the moon the inhabitants might believe) by observing changes in the planet's position in the sky relative to the star. Years would be more difficult, but they could be determined by recording the motion of the background stars in relation to the host star. Mark the constellations visible at midnight on a certain day, and their positions. When they return to those same positions, you know that the planet has completed an orbit around the star.
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Positing a high (c. 35%) O₂-level on a roughly Earth-equivalent planet (atmosphere about like the early Carboniferous), what types of lifeforms would flourish?
Obviously, giant insects could be possible, but there's no need to assume Earth-like evolution.
And what about fish? Would something like Rhizodontia be possible/probable? They're from an earlier epoch here on Earth, but could they not have survived? Any advantage/disadvantage to different marine species given the high atmospheric O₂?
Also, I'm particularly interested in the development of two other organisms: fungi and aspens. Any thoughts about their respective susceptibilities to high-O₂ environments?
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Well aspens appear to be adapted to forest fires, so can already be considered a [fire ecology](http://www.fs.fed.us/wildflowers/beauty/aspen/ecology.shtml) plant. Fires will be more frequent in a 35% oxygen atmosphere, so any and all plants adapted to survive periodic fire will do well (in comparison to those which are damaged or killed).
Meanwhile, IIRC fungi require lots of oxygen to break down lignin (the stuff that makes wood in trees hard and durable). So fungi may be decomposing fallen trees and infecting living trees faster than now.
Marine life... the depth of the [oxygen minimum zone](https://en.wikipedia.org/wiki/Oxygen_minimum_zone) will be deeper. However, how that affects all marine life depends on some other features of your planet. Ice caps are the pumping mechanism to get oxygenated water to the bottom of the deepest oceans, so currently the oxygen minimum zone is at a midwater depth. If you've got no ice caps, then oxygen just gets less and less with depth, and the minimum will be zero oxygen (in very deep water).
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Evolution of aerobic creatures would favor gigantic creatures. This is especially true for ancient types of body forms (i.e. amphibians and reptiles). If insects are present, they would also tend to acquire gigantic sizes.
Most land based creatures would *probably* be adapted for cold temperatures as large oxygen concentrations in the atmosphere tend to react with methane (a powerful greenhouse gas) and remove it, hence dropping temperatures on global scale.
Quadrupeds will tend to be faster and more agile than their counterparts under normal oxygen concentrations. Creatures with air-sac respiration systems will attain unbelievable speed and agility. Personally I think air-sac respiration method would quickly vanish, due to ready availability of oxygen without the complex air-sac system.
Methanogens will be hard hit, as oxygen is lethal for them.
Fish will also attain larger sizes, but that would be largely due to colder temperatures (larger animals are better insulated than smaller ones) than more readily supply of oxygen.
Coastal areas would have many times greater biodiversity than they have now.
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Fish would not be affected because the water holds as much oxygen as it can, and is already far less than the concentration in air.
You mentioned insects, as indeed they don't have lungs and their size is limited by their ability to get air to the cells. So most animals would not care or notice the higher level of oxygen.
It would enable *high altitude* life to go higher, as more oxygen is still available.
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Could a planet with an atmosphere composed mostly of neon, with oxygen and carbon dioxide making most of the rest, support life as we know it (specifically on a low gravity planet)? If so, what impact would it have on the biota of the world?
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# Different [Nitrogen Cycle](https://en.wikipedia.org/wiki/Nitrogen_cycle)
The nitrogen cycle helps give plants (and the animals who eat those plants) the nitrogen they need to make all their compounds which help make their cells. With a decreased level of atmospheric nitrogen, how will these plants make the various [amino acids](https://en.wikipedia.org/wiki/Amino_acid) they need? If you look at at the chemical composition of amino acids, you will quickly note that nitrogen is very common, and therefore very important, to life. Amino acids form the structures of proteins, which themselves are important to basic cellular functions and structure.
Life, if it is like life we know of, will need to develop some different techniques to even exist in this nitrogen poor atmosphere! Some bedrocks have nitrogen in them, and can serve as a source of nitrogen, this is not a property common to all bedrock. If nitrogen is too rare or uncommon, I do not know if life can even exist.
# Different Atmosphere
Looking at a [periodic table](https://en.wikipedia.org/wiki/Periodic_table#/media/File:14LaAc_periodic_table_IIb.jpg), you can see that Neon has an atomic number of 10, whereas Nitrogen is sitting at 7. Since Earth's atmosphere is made mostly of $N\_2$, and Neon (as a noble gas) tends to exist as simple Ne, this means the atmosphere itself would be composed of lighter molecules.
This would result in less buoyant force for things which attempt to fly, as gaseous Neon is [lighter and less dense than air](https://en.wikipedia.org/wiki/Lighter_than_air#Neon). This will result in larger wingspans or more vigorous flapping for flying creatures in general.
It also means that creatures experience less drag, so I would expect larger creatures to be generally faster.
# In Short: No Life
Nitrogen is a key element for all life. Although most forms of life rely on other forms of life to make atmospheric nitrogen available, removing those nitrogen fixers makes the nitrogen cycle crumble. No nitrogen cycle means no amino acids, and no amino acids means no life!
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Due to an unforeseen malfunction your intergalactic spaceship suddenly drops out of hyperspace and comes to a near full stop. The ship is damaged, and will need to be evacuated soon...very soon.
You have some control of sublight travel and manage to find a habitable planet in the system you have arrived in. Lucky you! Off you, and your main ship's computer, go and do all the necessary 'can this planet support life?' tests.
This planet is going to be home for the foreseeable future and you need your evacuation pods to have as much detail about the planet as possible (the pods computer systems are not as powerful as the main ship's system). Eg topography, water sources, temp ranges, and broad annual weather patterns (obviously dangerous plant and animal life will be a nasty surprise once you have landed).
The story-universe is based on normal laws of science. So even though this is an alien planet, hot air still rises, cold air still sinks.
**Question. Can you deduce the entire years general weather pattern from about half a day's scans?**
**If not, What can you deduce from about half a day's scans?** (maybe up to a full day cycle)
For example, your scans show a large mountain range, so you can deduce watershed, orographic rainfall, rainshadows, anabatic, katabatic winds, mountain and sea breezes etc.
Example, your scans show a wide shallow coastline along the equator. You can deduce warm shallow seas. Lots of sediment. Weaker ocean currents warming the air above it. Warmer currents spawn storms along the equator (hurricanes and tornadoes)
Etc etc.
**Edit** I have considered launching a series of small satellites before the ship is evacuated. This would allow more detailed information to be collected and be sent down to the planet in the future. But just incase one or two escape pods land on their communication antenna, or there is some reason why a pod couldn't receive the signal, what basics can I give my survivors.
**FURTHER EDIT - info to consider in your answers**
This being a completely unknown planet, with no known records on file. You have no climate time series; no ice cores, no tree ring data, you have no storm cycle records (eg storm every 100 or 1 000 years), no historical sea level records, no records of what is the hottest/coldest day of each year etc.
You do have far-future tech, so presumably you could get; atmospheric chemical makeup, current weather systems for the planet on the day, topographic map, maybe even a partial geological map (earthquakes and volcano map), current temperatures, broad climate regions (equatorial, tropical, subtropical tundra etc), sea temperatures and currents, bathymetric maps (underwater topographic map),atmospheric circulation (eg Hadley/ferrel/polar cells), wind speeds and currents (eg trade winds, doldrums), storm paths (eg roaring forties). Distance to the moon and the gravitational force on the planet and tides, distance to the sun and calculation of orbit, length of a full day, how long the seasons last for, how long a year is, orbital mechanics influencing 'mini ice ages', to name a few.
With a snapshot of about a day, with the help of a computer running simulations and calculations on how everything influences everything else, could you get a broad outline of the climate and weather for the year?
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You seem to be assuming that this planet is generically similar to other planets that this ship and crew has comprehensive information on. Given that, a snapshot of the atmosphere and weather, which is what you're getting, plus observations of the moon(s), the planet's orbit, etc. will tell you a fair bit about the *climate*, but not so much about the weather.
You can make a fair guess about the range of weather over the seasons for any given area of the planet, but you'll know that there will be surprises over the next few years, and details that you won't be able to predict about the climate.
Having wonderful tech doesn't let you avoid being wrong some of the time. For example, a simple indicator of where there's plenty of rainfall is the amount of plant life. But if, for example, rainfall at point A is strongly seasonal, and you're currently in the season when it happens, it's hard to tell that all that grass-equivalent plant life will be gone in a few months, because there's a desert there the rest of the time.
For another example, prevailing winds are very important, because they let you know which ways the weather moves. We understand the prevailing wind patterns on Earth, and they're been pretty consistent for several centuries. But there are historical records that indicate, a bit vaguely, that the prevailing winds used to be different in some places. We have no idea how that could have been the case, but that probably means we don't understand the problem as well as we think.
With only a day's observations of this planet, your colonists can't understand its weather from scratch. They can only try to fit what's happening now into a general model of how weather happens on planets like this, but no two planets are identical.
More uncertainty comes from the chaotic nature of weather, and the complexity of influences on it. You just don't have time to figure out all the details unless you have vastly superhuman minds or AIs.
It sounds as if once you've landed, you won't have much capability to move long distances. So you're going to want to try to pick somewhere that has reliably good weather for your needs. Do you expect someone to come and rescue you within a few weeks, or is it already time to set up farming and write a constitution? Rather than looking for the spot with perfect weather, the wise course may be to try pick somewhere that doesn't have extremely bad weather, and accept that it won't be perfect.
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Is there any websites on the web where a long site of semi-plausible worlds can be found? I am looking for all sorts of weird, colorful worlds that *are lifeless and terrestrial*. For I think it's fun to have planets that are creul mockeries of Earth all over the place, and it seems that's what reality has in store for us anyways. I know of Orion's Arm, Planetstar Wiki and the planets Star Control 2 has (though the plausibility of star control world types is on the very, very low side).
I recall Baxter made a list of many strange worlds somewhere too, but not sure where that is.
Any websites out there beyond the ones I have mentioned that have long lists of exotic geochemistries for alien planets? From my understanding all matter of weird, weird worlds could exist around the galaxy and judging by worlds like Io, Venus and Titan something tells me this is the case.
The website must have three things:
* Lists many types of worlds that are trerrestrial which could plausibly exist.
* Describes what stars it may occur around.
* Describes how abundant said world should be.
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# Orion's Arm
Orion's Arm is a [universe project](http://www.orionsarm.com/) authored by many. While it is bursting at the seams with hard sci-fi ideas and creations, I find a lot of it pretty esoteric, with its own lingo that can be hard to penetrate.
However, its strength is certainly is massive depth. There are a lot of contributers who each add information about their speciality, so it is remarkably in depth in many areas.
As far as planets go, there are [a lot of options](http://www.orionsarm.com/eg-topic/45b2e52e9eaac). Not everything on the linked page is a planet, but I counted 70 different types. Here is a [better organized page](http://www.orionsarm.com/eg-article/491c78b89879b) with all the planet types.
Good luck. Orion's Arm is something of a TV Tropes black hole of productivity. Don't click those links at work!
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I do not know of a canonical listing of either real exoplanets ( none are known to have life, so 'dead' is moot), or a fictional pan-authorship listing that would have what you have described.
I suggest as a starting point, you look through the Memory Beta website at:
<http://memory-beta.wikia.com/wiki/Planet>
While the ST universe may not have the planetary characterization of say - Niven's 'N-space', the classification on Memory Beta may give you resources to work from.
Happy hunting !
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It's not a straight list, but the Atomic Rockets site has a [very extensive guide](http://www.projectrho.com/public_html/rocket/worldbuilding.php) to designing worlds. Pick your sun, calculate habitable zones (for different biologies, even), climate zones, tectonics, -- even how to figure out how big the planet's sun is in the sky!
It also links to several planet-generators on other sites, although I didn't check those out myself.
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I am currently creating a world for a series of fantasy short stories (and hopefully movies one day), and I need some help with the science. Ideally, I would like the story to take place on a moon that is slightly smaller than the earth, with a similar atmosphere and temperature, that orbits a gas giant, which in turn orbits a star similar to the sun. The moon must be able to support human life. I have several questions that I have been unable to answer on my own:
1. What sizes and masses of the star, planet, and moon would make this possible?
2. What would the orbits of the planet and moon be (shape, distance, and speed), and how would I calculate the length of a day, month, year, and the seasons on the moon using this information?
3. How would the gas giant affect the tides of oceans on the moon, as well as the seasons and how much would it light up the moon at night?
Since this is for a fantasy world, it doesn't need to be 100% realistic, but I would like to be as scientifically accurate as possible.
Thanks
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It is quite possible.
For a model, I'm using Callisto. It is the second largest of Jupiter's moons, and the furthest large moon from the planet. It takes 16 days to orbit Jupiter and so suffers from less tidal heating than the other moons. It is also further away from Jupiter's radiation bands. (This last is an important point. Radiation around Jupiter is severe) We don't want tidal heating of the planet, as we have the sun to warm our atmosphere. Tidal heating will just make more volcanos.
You can be quite flexible in your choice of star. Something sun-like is safe. Dimmer stars are also possible, (though the planet must be closer to the star, so flares are more of a problem). Very bright stars probably don't last long enough. The length of the year would be shorter if the sun were dimmer longer if the sun is brighter, from a few Earth months to a few Earth Years.
The planet can be anything from Saturn sized to bigger than Jupiter. The mass will affect the moon's orbital period (for the same sized orbit, more mass=quicker orbit) But the radius of the planet will be about the same.
The moon will be tidally locked to the planet, so the planet will only be visible from one side of the moon. This may be a big deal for the inhabitants (do those born on the "far" side even know the planet exists?) Tidal locking also means that the day length = the orbit length. About 16 Earth days for Callisto. The nights will be long and cold. If that is too long you can increase the mass of the planet to shorten the day a bit.
Since the moon is tidally locked, there won't be much tide. The seas won't change in height a little due to solar tides, and perhaps small effects from other moons, but nothing like Earth tides. Also there wouldn't be any months.
The moon will orbit in the equatorial plane of the the planet (unlike our moon which orbits in the plane of the ecliptic) periodically the moon will enter the shadow of the planet causing a eclipse. Those on the far side probably won't even notice, but it will be a major event for those on the the planetside. The planet will be bright, perhaps too bright to allow stars to be seen by those on planetside except during an eclipse. Eclipses will occur during the planets equinox, twice a year,
Other moons are likely to exist, and may be quite significant sky features, clearly showing a disk to observers.
So to summarise
1. You can have a sun-like sun and a Jupiter like planet, and an Earth-like moon.
2. The planet's year could be about 360 days, the moon's day and month are equal at about 16 days.
3. The planet would be a major feature in the sky of half the moon.
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Looking at current Jovian satellites, Europa and Io give you some idea of what you'd need to consider. Starting with the Solar system model:
* Europa is (as Aaron commented) the most likely candidate, but is probably too small (little under the size of our moon) and too cold - but it probably has a water ice crust, which means it is not far off the necessary temperature.
* Io maintains a slightly higher temperature, but is the most volcanic object in the solar system (these 2 facts are linked with the proximity to Jupiter - Io is the closest of the Galilean satellites)
* So in an exact analogue of our solar system you probably would need this moon to be similarly close to Jupiter to allow for tidal heating, volcanism would be likely (and possibly help with warming if sufficient greenhouse gases were a part of this) but your real challenge in an exact Jovian copy is that you are so far from the sun, so solar heating will be tiny, photosynthesis will not provide plants as we know them, and hence oxygen will need to be sourced from somewhere.
The solution to the temperature/energy problem is to have the gas giant much closer to the star, or have a larger star. You do run up against a minimum orbital distance limit for gas giants, however if the gas giant was the only planetary body in the system, it could certainly be much closer than Jupiter is in our solar system.
So, a Jupiter-sized planet orbiting a little outside Mars' orbital distance, with a moon a fair bit larger than Europa could suit your needs. So you could use a year around 3 Earth years long for the gas giant, but need to look at how orbiting that gas giant affects things (an orbital period of 3 days or so is well within bounds for this model) in addition to the rotational period. For interest you could look at having the moon's orbit at a high inclination to the gas giant - this could simplify some of the concepts of days and years.
Rotational period may be very long - tidal locking is likely. If the moon isn't locked then the tidal effect on not just any liquid water, but the moon itself will be extreme.
Reflected light will make for impressively bright night skies on the side facing the gas giant (see how bright Jupiter is from Earth for an indication) - by default, gas giants have a large albedo so if you have tidal lock here the side facing the gas giant will only see darkness when eclipsed by the gas giant.
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Either you wait for these guys who know the math, or you take the easy-going approach I can offer.
**1**
So, the inhabitable world should be at least as heavy as Mars (in terms of mass), but better be in the same weight class as earth - less mass would allow fancy jumping combat, but you may lose your atmosphere, more mass would... do many things. To break things down: aim for a surface acceleration close to ours to get the most earth-like appearance. Something between Earth and Mars in terms of mass and size may work. When in doubt, add superheavy elements to the core ;)
About the other protagonists... here you should aim for something similar to our system. Bigger suns may offer brighter days but also more radiation... which may be nullified if your Earth-Moon is inside the gas giants magnetic field. At the other hand that would mean that it will so close the rotation went to a bound one (one side is facing the gas giant all the time). Just the same our very own moon (Luna) is doing after all. When you want this moon to have a more earth-like rotation, it have to reside in a pretty big orbit, but... I thing there might be a limit of some kind. Here the guys with the correct formulas on hand can offer better explanations: how far it can go of without saying farewell to the gas giant completely?
So, have a modest sun, place that gas giant inside its habitable zone, add a moon that is a bit smaller than Earth but a bit bigger than Mars and here we go. Should work and can offer pretty impressive polar lights under the right circumstances.
Something more: big gas giants will heat up your moon by their own. Not like a true sun, but sufficient to shift the orbit a bit more away from the sun. If you install a brown dwarf instead, chances are high that life would flourish even outside the habitable zone up to some million kilometers. But it would be pretty dim all the time.
**2**
Oh... math. As Aaron Lavers in his comment said, you could look up whats happening with the big moons in our system. The gas giant might need more or less a year (less, if the sun is smaller than ours, way more if its bigger, when its orbit is adjusted to stick inside the habitable zone). The planet of yours (the moon)... I guess he will take more than a month for a full round, but way less than a year. Three to four months (real earth months)?
Seasons would be pretty interesting, by the way, because you may have some days your moon would stick in core-shadow of the gas giant. Reminds me about the movie Pitch Black with Vin Diesel.
Well... to stick with the four month orbit (its good for explanation), you would have one month for northern hemisphere for Winter, one for Spring, one for Summer and one for Fall... and imagine the gas giant need twelve to orbit the central star and have some orbital excentricity of its own, you could have three "winter" which range from "cold as fu\*\*" to "pretty hot", while three times a year you suffer from total darkness for a couple of days... If that happens in the "cold-winter" your people would be... very poor off, while in the "hot-winter" it could be more decent. At the other side during a "hot-summer" they will enjoy the off time from scorching temperatures.
To conclude this: your moon will have summer, fall, winter and spring three times a year, one in a hot variant, one in a cold variant, one in a medium variant... and I thing these will shift over the years. Correct calculation will be a nightmare if you decide to go for super realistic orbital times... Maybe its a good idea to stick with the 4-months orbit for the moon and the 12 (or maybe 16) month orbit for the gas giant, so you can determine more easily how things are looking at that moon.
EDiT: Turns out I forgot something: to have long orbital times for the moon, that gas giant can't be pretty big (the bigger, the faster you have to run on your orbit to avoid crashing down). So either move away from the giant (which will make the ecpises less intense), or shrink the giant... hm. Titania from Uranus does have a similiar orbit to the one our moon has but still, it just takes about a week to do a full orbit. That will be tricky. Maybe a 4-month orbit is way outside any posibillity after all... or the gas giant would be as small as our moon at the night sky and lose its appeal ;)
**3**
Expect giant tides. And bright nights. The latter will only occur when your moon is between the gas giant and the sun. When its a bright ball of Helium and Hydrogen like Saturn, Reflection will cause nights that are as bright as days (with a few lumen off), while something more... Neptunish will cause more dark nights.
As soon as your moon is behind his gas planet (lineup: sun-gas-moon), nights will suddenly get pretty dark and even days can get very dark, when the moon goes for a full sun eclipse.
Well... enough for now. Coworkers already starting to wonder why I'm this busy typing all of a sudden. My answer might not be the most accurate, but I hope most effects had been covered so you can start expecting how thing would look like. Now wait for these guys with the formulas and small pictures of orbits. Or drop all this, because if its a fantasy-world without modern technology stuff like this wont matter enough to waste lines describing accurately how the solar system does look like.
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As a practical matter it is possible to write science fiction and fantasy novels set on habitable, earth like moons of gas giant planets and get them published.
For example, Lin Carter's Callisto series of eight novels is set on Callisto, a real moon of the real gas giant planet Jupiter. They are described as science fiction novels of the sword and planet subgenre. The sword and planet subgenre is definitely close to the rather vague line between science fiction and fantasy.
And what many people might think pushes the Callisto series over the line into fantasy is that Callisto is described as a habitable world, which violates everything which science has discovered about Callisto by 1972 to 1978, when the novels were published, and since then.
Setting a fantasy novel on a fictional habitable moon of a fictional gas giant planet in another star system seems with as reasonable to me as setting a fantasy novel on Earth in the past or future, or on a known or unknown alien planet, or on a flat disc world, or in an alternate dimension, or in an unspecified setting, or using any of the usual fantasy settings.
And it has the bonus of having a large object, the gas giant planet, visible in the sky of half of the moon and making a very impressive sight even if you don't make it's angular diameter larger than is scientifically possible.
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Before there were underground imaging technology, how did people know where to direct a mine tunnel? Presumably people knew from the kind of rock on the face of a mountain whether it contains veins of ore, but how would you decide where to tunnel to? Do they just explore? How do they know when the mine is exhausted? Why not just keep tunnelling until you find more ore?
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While I can't speak to the middle ages specifically, Pliny the Elder suggests that gold mining in the first century CE did involve randomly tunneling when seeking deposits at depth:
>
> The miners gaze as conquerors upon the collapse of Nature. And nevertheless even now there is no gold so far, **nor did they positively know there was any when they began to dig**; the mere hope of obtaining their coveted object was a sufficient inducement for encountering such great dangers and expenses.
>
>
>
(Emphasis mine, from *Natural History* book 33, volume 9 page 57 of [Rackham's 1938 translation](https://archive.org/details/naturalhistory09plinuoft).)
General placement of a mine would indeed be guided by surrounding geology (page 53):
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> People seeking for gold begin by getting up *segullum* -- that is the name for earth that indicates the presence of gold. This is a pocket of sand, which is washed, and from the sediment left an estimate of the vein is made.
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Though Pliny does not detail the method of locating a silver deposit, he does state it is only found in deep shafts (p. 73) and describes a number of other minerals found in the same mines. Similarly, copper and iron are described in terms of the geology in which they may be found and are said to be found both on the surface and at depth, but both in easily-identified ores (book 34; p. 215, 233).
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[Andrew Wilson](https://www.researchgate.net/profile/Andrew_Wilson4/publication/236157666_Machines_Power_and_the_Ancient_Economy/links/55f4898008ae6a34f6608f77.pdf) (p. 17) states that hydraulic mining of surface deposits was much more common than shaft mining and refers to Pliny's statements, where water would be collected or redirected over areas known to contain deposits to expose ore at the surface or in runoff. Wilson also estimates that the scale of Roman mining was unmatched until the industrial revolution (p. 26), which may suggest similar techniques were used through the entire period up to the development of mechanized mining.
Interestingly, Wilson also observes that Roman industrial-scale mining generally ceased around the third century CE, possibly due to the immense cost of constructing infrastructure for hydraulic mining. Given suitable construction capability, hydraulic mining might have been more common throughout the intervening time.
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**Gold was easier to spot in those times**
I live in New Zealand, and in the old days gold nuggets were found in shallow rivers/streams and washed up on beaches in gold hotspots.
There were even annual events for who can collect those most gold off the beach in one day.
So miners would simply walk around the hills, and look in the streams, and when there's a little gold, that's an indication that there's more around.
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Setting: Western world nation, Earth as we know it, May 2016, Gregorian calendar. Eccentric billionaire, large multinational corporation or similar; lots of money, and ability to enlist the help of some really smart people.
Let's say that I, for some nefarious or benevolent purpose (doesn't matter) want to make it seem like there is intelligent life out in the universe, and that they have something important to teach us Earthlings. Let's say that I have determined that the best way to do this is to transmit a signal of apparent extraterrestrial intelligent origin toward Earth at a time when I know that someone will be listening in that direction.
I have figured out the details of what to transmit, how to modulate the signal, which frequency to use, how to masquerade the launch so as to not attract unwanted attention, and every other such preliminary item on the checklist.
I have the ability to launch spacecraft (maybe myself, maybe by paying a commercial launch services company). I also have the ability to design and build a satellite or probe to make the transmission, and make it seem sufficiently legitimate to (again) not attract unwanted attention. I have the money for several such spacecraft and am willing to spend it if doing so significantly improves my chances of success. I can make things happen in such a way that it's very hard to trace it all back to me.
There's just one tiny problem left.
Given that I have all this down pat, in the face of a reasonably expectable level of scrutiny, **how can I make the transmission appear to originate from a distant star?**
I don't really care which star, but if possible would like for it to be one that is something like **20-60 lightyears away.** Ideally one that is known to host a planet that is potentially at least non-hostile to life as we know it, but that is less important than that the transmission will genuinely appear to originate from well outside of our solar system.
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**No**, it is not possible to fake it. The simple one word reason is **parallax**.
Let's say you try to fake a signal from Vega (to borrow an example from the movie, [Contact](https://en.wikipedia.org/wiki/Contact_(1997_American_film))). That's 26 light years away, so within the range you mentioned.
You can put a satellite in orbit around Earth and make your satellite transmit a signal, and pretend the signal is from Vega. A radio dish could pick up the signal when your satellite is in the same position in the sky as Vega. All a radio astronomer has to do is ask a technician at a different radio telescope a few thousand miles away to point their dish at Vega. When the other dish points at Vega, it won't be pointing at your satellite, so it won't get the fake message from your satellite.
It's a simple [parallax](https://en.wikipedia.org/wiki/Parallax) test.
Radio astronomers do this all the time. Every day. They might get some transient signal. The signal is not necessarily an artificial signal, but something from either a nearby source on Earth, something in orbit around Earth, some automated unmanned aircraft flying over their dish's controlled airspace, or perhaps a weird natural phenomenon hundreds of light years away. How do they filter out Earth based (or Earth orbiting) signals from astronomical events? They just ask their buddies at a different radio telescope to do a quick check. This check only takes a few minutes. If their buddy a few thousand miles away gets the same signal, they know the source is not from Earth. If their buddy does not get the signal, they know the source is Earth based.
I'm surprised the main character, Eleanor Arroway, did not mention this very simple test at the end of the movie when National Security Director, Michael Kitz, asked if Hadden could have faked the signal.
How do I know this? I've been an astronomer. I published peer-reviewed articles in astronomical science journals. There is a reason why my profile picture shows a radio dish.
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What you need is [synthetic hologram](https://en.wikipedia.org/wiki/Computer-generated_holography), only in radio spectrum, not visible light spectrum. But EM is EM, it is doable, at least in theory, and it is possible to create wave front that would look exactly like if it originated at arbitrary point (for example, distant star).
Earlier [answer about phase array](https://worldbuilding.stackexchange.com/a/42453/809) is neat. Indeed, phase arrays can be considered form of holography. But they are bit too simple, sadly. You would want to create holographic emitter the size of Earth. This means, you would need to put quite a lot of satellites, and make sure that during emission window they are sufficiently close to each other.
Good point is, if you can cover half of the globe with satellites, and make sure no two are too far apart (think wavelength distances), you would no longer need to care who is watching.
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Or simply sell IT equipment to all radio-telescope teams, and fake data directly in their database. Just make sure only "your boys" are looking when you do this.
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To really do a job you'd probably have to have a [minimum of a] couple of precisely linked craft either is really high orbit, or on an outbound trajectory. They'd beam coordinated signals at either side of the earth to simulate a parallax of an source father away. You'd probably want to pick a candidate that could reasonably expect some gravitational lensing from an object on the path between here and there, to cover any inconsistencies.
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Maybe a *phased array* can trick the antenna into thinking that the beam is coming from some specified direction, different from the real source. That can fake the effect of the moving earth and actual position of the source.
You might need different "trick" signals for each receiver. If the signal requires special equipment or only the elite observatories can do the job, that can help with the plans.
You will need to keep an eye on any plans for variations in the observations, such as deciding to observe from a different position or with different equipment. And, the transmitter will need to cope with these changes on the fly, when it's already way out there.
So, you will need some insiders helping you, as well as equipment capable of contingencies.
You might have the signal come and go with poor reliability. Then it's not too suspicious when you have to cut it after the observatory makes an improvement, before you can compensate for it. Compensating might even require the inside man to do something at the receiving end, as well as reporting on the details of the listening post.
To summarize, you can't fool all possible observers all the time. But you only need to fool the *actual* observations that are made. You can prevent observations that could not be handled, and adapt on the fly.
[Answer]
Yes, Easily.
A couple of men walk into the observatory in engineer type cloths, carrying a toolbox. They fiddle around and measure some things then attach a small box of electronics to the direct input, the system contains a microprocessor and is programmed to add its own signal to the incoming one.
] |
[Question]
[
Life on Earth has been annihilated because of a nuclear war. Everything above ground has far too much radiation to be hospitable. How can life go on?
Living in a bunker would have the following basic needs:
* food
* water
* energy
**Food** can be obtained by farming in the bunker.
**Water** is a more difficult question. You could store up water, but because humans need around 60 gal. per year, we're talking about a tank with thousands of gallons of water to sustain only three people for half a century. (This doesn't take into account showering or cleaning either). Drawing water from outside would also be problematic because it would be irradiated.
**Energy** is only somewhat of a problem. If someone figured out how to harness energy from the radiation outside, then it would be trivial to power the bunker.
So my question is, **how can drinkable water be obtained during globally high levels of radiation?**
[Answer]
Where you built your bunker, and how badly affected your area is, are going to be key factors in all this.
Generally speaking, your bunker is going to require insanely efficient air and water recycling systems. Every drop of moisture should be captured, filtered, and reused. This will mean that those 60 gallons/year might last you quite a while.
However, you also need water for hydroponics ("farming" in the bunker), cooling, etc. At some point or another, you will have to draw more water from the outside. And if your bunker isn't tapped into some local water supply (an underground spring, or even the local water table) you're in trouble (you may have to organize expeditions to the surface, pump some in using hoses, etc - very messy. Better if you design your bunker with this in mind, to begin with).
The water you draw in is probably going to be "irradiated". At least that's what us laymen would say. Actually, water can't be irradiated - it can, however, have irradiated particles suspended in it. This means you ***can filter them out***. There are articles out there on how to DIY, so I think it's fairly well-established that it's possible.
Power is also not a problem, as you would be able to drill down and set up a geothermal plant.
[Answer]
**Food**
I think, food would be much harder as you think. The current, not really overfeed humanity needs around 0.1 - 1 square kilometer to feed a single human. Now compare it to the cost of digging underground train tunnels. Even if you can somehow solve the problem of the tremendous light need.
On my opinion, food is essentially unsolvable problem by the current technology in underground farming.
**Water**
Water is from Hydrogen and Oxigen. Fortunately, all of the instabile isotopes of oxygen decays very fast (in decays in days). Hydrogen has only a single dangerous isotope, it is the Tritium. It has a half life of around 12 years. Fortunately, nuclear explosions create them only in negligible quantity (but, for example, in the safety protocols of nuclear reactors it is an important issue).
So, "radioactive water" would mean only non-radioactive water with radioactive contamination. It can be simply eliminated with distillation, filtering, etc.
**Energy**
The radiation contains very small energy compared to its damage. The thermal energy of the radiation which is enough to kill a human, wouldn't be enough to boil a cup of coffee. Harnessing energy from the radiation outside would be infeasible.
But, I think, energy can be solved most easily. Having underground nuclear reactors - or using the already available water and nuclear reactors on the surface - could be enough. Or the remaining surface reactors could be used by the survivors, and their voltage could be lead into the bunker.
---
What could work:
1. The current nuclear weaponry of the global powers don't target to exterminate the life on the Earth. They are constructed to make the other powers incapable to fight. So, their goal is not to sterilize, their goal is to mechanically destruct the rockets, factories, cities, military bases and government centers of the enemy. Thus, firing all of the currently existing nuclear rockets would kill a lot of people, but the Earth would survive it with minor problems. On the longterm, it would be even a positive result from an ecological view (compare the well developed fauna around the abandoned Chernobyl nucler plant - for the wild animals, it is *much* better to live in the vicinity of Chernobyl, as in the vicinity of New York). We, humans, with our pesticides, weapons, roads, deforestation, are much more dangerous to the ecosystem as our nuclear weapons.
Or course there are nuclear weapons which *[could](https://en.wikipedia.org/wiki/Cobalt_bomb)* goal to sterilize the Earth and it would be possible to construct them in the needed quantity, but they are only plans. Not because the major global powers are so good boys, but because their goal is not to sterilize the Earth, but to destroy the other.
2. Majority of the nuclear radiation would be gone in some years. There are around 4-500 nuclear isotopoes, around 2/3 of them is instabile (i.e. radioactive). Most of them decays very fast, and so they are a no-issue on the longterm. Many of them decays *very* long (in centuries or more). They are not really radioactive. And many of them won't be produced in nuclear explosions.
There is only around 5 really problematic isotopes.
For example, around the Chernobyl plant is there still dangerous radiation, but this danger means only that living there, you would have a significant chance to get cancer in some decades.
If the whole surface of the Earth would be the same, our life expectations would be much worse for some generations, but the humanity would survive it.
[Answer]
## There are many solutions
The Immediate solution I thought of is to build it underwater in the first place, primarily in the Marianas Trench, where there is plenty of water, but that would require a very effective water purifier. A quick google search later and I found [this website.](http://undergroundbombshelter.com/)
It agreed with my thoughts that a wise choice when planning your water storage is to have at least one water treatment option on hand. It may be necessary to venture out of the shelter for more water (or if underwater, open a water chamber). If you have to stay for an extended period of time in any shelter with even a large amount of stored clean water, your water may become contaminated and require treatment. If there is any question about the potability of your water, it’s safest to treat it first. Luckily you have several options available for emergency water treatment, including:
* Boiling- Boiling is one of the easiest and most reliable ways of rendering your water safe to drink. If your shelter includes a means of cooking, you can boil water for 3-5 minutes to kill pathogens. Boiling releases a great deal of steam, so if you choose boiling as your method of purification then you want to have a steam distillation system in place. This can be done very easily and cheaply in several different ways- for example, a length of copper pipe directing the steam from a boiling kettle to a wide-mouthed jar or other container (not plastic). The result will be clear, clean distilled water that is safe for drinking.
* Hand Pump Filtration- These are small, portable water filters typically intended for backpacking and outdoor adventures. While compact and easy to store with your disaster supply kit, they can be expensive and are really only intended for use by a single individual. Using a manual pump to filter multiple gallons of water every day for an entire family could be extremely difficult and time-consuming. It is, however, a better choice than no treatment at all.
* Chemical Filtration- Water purification tablets can be effective against bacteria, but may not eliminate other contaminants such as protozoa. You can purchase the tablets from an outdoor supply store, or you can choose to simply store iodine or chlorine. In a pinch, household chlorine bleach can be used at 1/8 tsp (8 drops) per gallon. Chemical filtration is likely to affect the color and flavor of the water.
* Ultraviolet Light- A device that uses UV light to deactivate bacteria/protozoa in the water is another option for small amounts of water. UV light will not protect against possible viruses in the water. Unlike chemical filtration, UV light will not alter the flavor or color of the water, because it simply inactivates any pathogens present in the water and renders them harmless.
[Answer]
You want all the water you can get - for radiation shielding. [Nasa is looking at it](https://www.newscientist.com/article/dn23230-mars-trip-to-use-astronaut-poo-as-radiation-shield/). Build your shelter *inside* a great big cistern or a series of tanks, maybe with double walls with an outer layer shielding an inner layer. As long as there's no *fallout* contaminating your water you ought to be fine. The CDC's decontamination protocols seem more concerned with radioactive dust than [water contamination anyway](http://emergency.cdc.gov/radiation/selfdecon_wash.asp).
If you water wasn't radioactive to start with you should be fine. (as an aside, human waste makes good shielding too. So if your outer layer of defensive water isn't radioactive, you could use that to store your "post consumer food", assuming you arn't using it as manure.
You could also reclaim waste water (directly, through various filtration methods, or indirectly by use of it as humanure or as nutrients for hydrophonics). This could be through filteration,distillation, condensing ambient water vapor or other means. Just treat the whole structure like a stillsuit.
Water's also a great way to *store* energy- you could possibly use a cycle or other pump to pump up water, and use it to turn a small generator for small sustained power needs.
[Answer]
I would think that as the radiation comes from speciffic molecules from the radioactive materials that special nanofilters only large enough to allow the water to pass through may suffice.
there are already items of this nature in existance with aperently solid bricks which will allow water to pass through seemingly uninhibited.
As for showering the solution could be much simpler with a filtration to reduce particles of dirt and dead skin the same water could in theory be recycled for a substantial amount of time.especially if it were chemically treated as city water is today.
[Answer]
[](https://i.stack.imgur.com/bqy8m.png)
## Clay and sand filters
As of 1987, the US DOD recommended a clay and sand filter to filter out radioactive isotopes from water. They could be engineered or improvised.
See [Nuclear War Survival Skills](https://ia800501.us.archive.org/35/items/NuclearWarSurvivalSkills_201405/nwss.pdf), chapter 8 for a full discussion of how to ensure clean water.
It is more fuel efficient than boiling based solutions.
## Disinfection
NWSS says that biological contamination is more likely to be dangerous than fallout contamination in many areas. Conventional disinfection using filtration or chlorine is advisable.
## Reverse osmosis
The effectiveness of RO is proportional to (hydrated) ion size. Uranium is either going to be in the form of particulates (in which case conventional filters will remove it), or salts (in which case RO would be very effective).
[Answer]
It's energy-intensive but you can simply draw in outside water and purify it with distillation. That will remove almost everything that could be radioactive (it will miss tritium but that's not going to be a big factor.)
Your limiting factor is energy, not water.
] |
[Question]
[
I am already aware of the concept of the **fusion torch**.
But I would like to consider other solutions for separation of raw materials that can be automated but are less "extreme" and closer to current technologies.
My machines are supposed to mine mostly asteroids (0g no atmosphere), moons and moonlets(low g, no atmosphere).
EDIT: As stated I am thinking at clanking replicators, not nanobot. If you want an example of material composition to use then moon regolith composition is ok: Oxygen (40%), Silicon (20%), Iron (10%), Calcium (6%), Aluminum (5%) and Magnesium (5%)
[Answer]
Look up how a [mass spectrometer](https://en.wikipedia.org/wiki/Mass_spectrometry) works. I believe the fusion torch concept is something of a variation on this. You don't need fusion to make it work, just an abundant energy source. It could be solar powered, for example.
First you heat the substance to a very high temperature (start with a mirror based solar concentrator, then zap the pre-heated material with a laser to reach the very high temperatures). This produces positive ions because electrons (which carry negative charge) are lighter than atomic nuclei (which carry positive charge). If you heat it up enough, any molecules will break down (since molecular bonds are based on shared electrons).
Then you magnetically propel the ions along a curved trajectory. An ultra hard vacuum (like exists in space or on the lunar surface) is necessary, otherwise they would bump into too many air molecules for this to work. Heavier ions retain their forward momentum longer, causing them to be separated from lighter ones as they are magnetically deflected around the curve. On the other hand, particles with higher charge are deflected more due to higher interaction with the magnetic field. So there is separation based on the charge-mass ratio of the atoms. These atoms end up forming different "beams" of particles, one beam for each element.
This concept is discussed by Freitas as an [Atomic Separator Replicator](http://www.molecularassembler.com/KSRM/3.14.htm). It isn't particularly energy efficient, but this is an "omnivorous" refining strategy, which means you can take just about any material and feed it in, and get the elements that it is comprised of. For self replication in an energy rich environment (i.e. since there is a lot of solar energy in space), an all-in-one process like that plausibly makes the most sense. The main design goals would be to eliminate the need for human involvement in the construction, operation, and maintenance of the machinery. Lunar regolith (just like dirt on earth) is about 10% aluminum, but the process we use for separating it out here on earth is rather complex, relies on specific ores, and would require pressurized tanks and specialized electrodes for high temperature electrolysis.
Something you could perhaps refine more easily would be iron, which is present in small amounts throughout the lunar regolith as a result of meteor fragmentation. You would collect the iron using magnets attached to rovers. That would produce a mixture of iron oxide (rust) and nickle-iron. Heating it to remove the oxygen would result in a metallic iron-nickle alloy. Further processing with carbon would be needed to make steel, but high quality steel might not be needed for your self replicating units -- the gravity is only a sixth there.
[Answer]
## Collection
Mobile bots will use chainsaws/circular saws/plasma cutters to slice material up into regular blocks. They will be transported to the central processing unit, where they will be processed in grinders, until it has the granularity of powdered sugar, this will also remove any ices in the ores, which can be condensed if desired.
## Sorting
Materials will be sorted using a combination of [hyper-spectral sensors](https://en.wikipedia.org/wiki/Hyperspectral_imaging), [centrifuge](https://en.wikipedia.org/wiki/Gas_centrifuge) and [magnetic separation](https://en.wikipedia.org/wiki/Asteroid_mining#Magnetic_rakes). Further [processing](https://en.wikipedia.org/wiki/Smelting) at temperatures that target materials melt at and 'tapping off' this material or by exposing the resources to heated Carbon Monoxide and then extracting metals from the resultant gasses.
] |
[Question]
[
*Setting*: In my [conworld](https://worldbuilding.stackexchange.com/questions/19788/how-would-flora-behave-on-a-two-continent-planet) there is a huge region (let's call it *the Midlands*) spanning from the northern borealis to the wide green pastures further south, of the northern continent, which is not one single country but rather a collection of dozens of *states* ranging from more utilitarian ones (e.g. big guilds) more centrally situated, to small kingdoms and duchies along the region's borders.
It is entrenched between two bigger countries claiming most of the area in the northern part of the world. The Western Empire in the west; and the Eastern Reich in the east.
The territory of the Eastern Reich though consists mostly of barren land which, although rich in minerals, ores and crude oil, is mostly infertile and thus they seek to possess the more fertile lands to their west (the Midlands).
```
A Western Empire
G Free Regions
H Eastern Reich
J Southern Lands
K Midlands (Coalition Territory)
L Border Lands
1 Equatorial Belt | Saltwater
2 | Saltwater
5 Northern Polar Sea | Saltwater
6 | Sweetwater
```
---
*History*: At some point in time, an [Alexander the Great](https://en.wikipedia.org/wiki/Alexander_the_Great)-esque character rose to power in the east and rallied an army behind him with the goal of \*making these greener lands available to our glorious Reich (back then nothing more than a bunch of smaller kingdoms, claiming the more fertile spots and hot springs along the mountain ranges).
When news of this rallying reached the west, the states of the Midlands eventually reached a point where they *signed a contract* and pooled together resources and their current individual armies, police forces, etc. to form what is called the coalition Military Force (from here on referred to as *the Coalition*). Thanks to this act they managed to fight back the *first wave* of attackers by having troops from all over the Midlands fortifying the eastern borders.
This collection of forces in turn managed to throw back the attackers long enough to give the Coalition the time needed to organize their new forces and set up a permanent block along the border, which continues to hold off the occasional raiding party from the east to this day (and further...); putting both parties in a cold-war/stalemate situation.
---
*Situation/Environment*: The inner states of the Midlands don't have the typical concept of borders. The lands mostly belongs to families and to guilds, the latter of which tend to buy and sell land where profitable; So borders in these areas are mostly informal. This is no issue because the whole system grew up to be that way (due to the way the early tribes/nomads in the area were organized and working with each other).
The outer states tend to be influenced more by the surrounding big countries and thus some have organized themselves in duchies and smaller kingdoms.
While the duchies and kingdoms to the east of the Midlands enjoy similarly rich pastures and amounts of resources, it is the center of the Midlands that really profits from the region and they way they are set up, there are no such things as tolls and other things that hinder free trade there and thus these *states* are comparatively rich.
The concept of the Coalition treaty/contract stems from the historical background that the families in these areas would usually band together to achieve this or that (culminating in the formation of guilds and *states*).
The Coalition Treaty itself consists roughly of the following parts:
```
+----------------------------------------------------------+
| The Coalition Treaty, of xx/xx/xxxx |
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
| |
| This Treaty shall serve as a foundation for the creation |
| of a super-governmental military body. The Signees of |
| this treay shall receive the following rights and obli- |
| gations. |
| |
| > Each Signee shall receive full military support in ca- |
| se of an attack stemming from outside or inside coa- |
| lition territory |
| |
| > Each Signee shall disband any state-owned military |
| forces immediately upon this treaty's inuring |
| |
| > Each Signee shall disburse an amount of money relative |
| to the richess of their lands, |
| the size of their population, |
| the safer they are from being invaded |
| |
| > Each Signee shall be able to disburse additional funds |
| in return for military services such as but not only |
| - police forces |
| - guard forces |
| |
| > Each Signee shall provide a pool of potential recruits |
| from which to conscript additional forces should they |
| be needed |
| |
| In return the created body shall have to organise itself |
| and provide services as best as is possible within the |
| limits of the provided funds |
+----------------------------------------------------------+
```
The Coalition therefore is basically a private army catering exclusively to the needs of the signees of the Coalition Treaty. It possesses military bases and other assets in most of the signee states. Logically it has to buy things such as provisions and material, weaponry, etc., a whole industry catering to the needs of this huge body will subsequently sprout in the Coalition territory and provide jobs and ways to shift funds back to the signee states.
Now why would they band together against a force that only seems to threaten the easternmost duchies/kingdoms (which themselves anyways chose to abandon the traditional ways for a more eastern approach) and why would the center states even consider the idea which obviously will conclude in bigger expenses for them than so far?
That is easy (mostly), easy: At the convent where most of the states gathered, the point was made that if the easternmost states/duchies/kingdoms fall, there is even less stopping the east army as it would gain a favourable position for annexing the rest of the Midlands. Thus the rich central states have a reason to back something that obviously means higher expenses to them than so far.
---
***Question***: Can a body such as the *Coalition Military Force* work in the described environment? And what issues that I failed to address/addressed *incorrectly* make it not work?
[Answer]
Two historical examples come to mind here.
The first example is the Delian League, which has been alluded to in other answers. Formed by Athens as a reaction to the Persian Wars, the Delian league had various maritime powers band together and pool ships and funds to protect the league and the rest of Greece from any attempt by the Persians to invade again. Very soon, the Athenians simply requested money from the other league members, who were happy to oblige for the most part, since owning a navy is very capital and labour intensive. However, when Athens decided to take full control of the League's treasury, the other members discovered that *not* having a Navy also means not having a vote.
Athens became an Empire in all but name, and the fear of Athenian Power lead to the Peloponnesian Wars.
During the 1400's, Italian City States tended to alternate between citizen militias and hiring professional mercenary companies (Condottieri). The Condottieri quickly discovered that they could play various parities against each other, accept payments to *not* participate in wars or switch sides and otherwise make planning difficult to impossible for the City State authorities (or even overthrowing them if they didn't pay up according to the terms of the contract)
So the essential point is that the hand that holds the sword eventually becomes the hand which holds the gold as well, and also the whip hand giving the orders. In your scenario, the central principalities will quickly discover that what seems to be an unrooted mercenary army is now calling the shots, and their tax revenues are not being spent for the benefit of the citizens of the central provinces.
How this plays out in the end is probably similar to the end of the Italian city states. Weakened by constant internal divisions and shifting alliances, they were unable to present a united front against foreign invaders (one reason Leonardo da Vinci ended up in the French court, for example). The coalition army, not being "rooted" and existing on tax contributions from a disarmed population, becomes predatory against the very people whom it is supposed to protect, and falls apart when directly challenged by an outside force.
[Answer]
I see an analogy with the alliance of Greek city-states in the Persian Wars (499 B.C. to 449 B.C.). That also was a military alliance formed to fight off a foreign invader -- the Persians -- which was much too powerful for any one Greek city-state to resist. Otherwise, the Greeks were a pretty fractious bunch... as was demonstrated not long afterward in the Peloponnesian War (431–404 B.C.). The lack of clear borders between States, which you describe, also seems to fit the city-state model.
The only real problem I see, which user58697 already pointed out, is your stipulation that the States forming the alliance would disband their own military forces. That would be equivalent to surrendering sovereignty... but the entire purpose of forming such an alliance would be so the individual States could preserve their sovereignty. So, not gonna happen.
The alliance of the Greek states against Persia lasted little longer than the threat did. Likewise, I doubt in your scenario it's realistic for the alliance, or confederation or whatever you want to call it, would last very long once the immediate threat was defeated.
So to make your scenario work, the external threat must be something that has to be repeatedly fought off. That would create a long-term confederation, which in time would perhaps grow into something more (as the original Confederation of the United States soon became a Federation). Perhaps there's a more powerful empire in that direction, one that has a hard time extending its reach to the lands in question, so doesn't invade often... but when they do, the military threat is formidable. I can think of at least one historical precedent for that: China (or more specifically, the Mongols) vs. Japan. There were two major Mongol invasions of Japan, but both failed.
[Answer]
Gonna answer your two questions in reverse order.
The main thing I'd say you have left to address is how the CMF is structured.
Who gives the orders? It's outside any sort of government, so it would have to have an internal command chain (democracy doesn't really work when it comes to heat-of-the-moment decisions), but how is that originally established, before the CMF is well-established and they can promote people based on merit? Do the people contributing the most get to lead? Do the people closest to the conflict (with theoretically the most experience) get to lead? Who decides promotions, anyway, especially into the top leadership positions? The larger, more powerful states likely aren't going to like the idea of someone from a smaller/weaker state leading the armies, and/or would want their own families to be in safer positions, so what sort of checks would be in place to prevent bribery and corruption?
As far as it actually working.... I can see it working in the short term. But in a few generations, I can see the families of the center states getting complacent, wondering why they're paying and sending their children to fight against this "phantom threat" that isn't actually threatening them.
Then there's also the problem of the CMF being the only military power in the West. What's to stop some ambitious CMF leader from seizing power (the analogous Julius Caesar to OP's Alexander)? It would certainly happen eventually, once the CMF starts to realize that they're the only ones with the weapons, so there's no point in paying for services anymore when they could just take over and get things for free.
[Answer]
Participants shall not disband their own forces. There must be something to balance the CMF. The Treaty shall have provisions similar to Second Amendment (as in well organized militia and the right to bear arms).
The overall structure of CMF seems to work best if the Eastern states contribution is mostly military, while for safer Central it is mostly financial. Centrals however must be ready to mobilize their National Guards shall a full-scale conflict emerge, in which case this becomes a usual (temporary) military coalition.
In no circumstances may army be allowed to perform police duties.
PS: As of why Centrals would agree to contribute, there is a saying (attributed to Napoleon), that *a nation which doesn't feed its own army will feed an alien's one*.
] |
[Question]
[
George is supervillian, and he has a evil plan but he needs a distraction to pull it off. Earlier today he was reading supervillian weekly and he saw an article on faking the Apocalypse and he want to try it.
The plan:
1. Hack into the major telescopes of the world make it appear that
there is a world ending meteorite on its way to earth.
2. Panic ensues everyone believes the world is ending police and the world are distracted.
3. The world returns to normal when the "fake asteroid" gets close
enough that it should be visible to the naked eye or simple
telescopes that can't be hacked.
How large does the asteroid have to be?
**How long can the distraction last if the George is only able to hack a few dozen telescopes?**
Are there other problems that George has overlooked? other than his mediocre supervillian name.
[Answer]
Instead of a puny little thing as few dozens miles wide asteroid, may I suggest a [rogue planet](https://en.wikipedia.org/wiki/Rogue_planet) at very very far distance instead? Basically George would want to:
* put the fake planet at such great distance and direction that only Hubble Space Telescope or select few on Earth can see or detect (through hacked radio and infrared telescopes) it.
* put the fake planet at extremely high speeds so that it would appear to come and collide with Earth in a matter of weeks.
# Reasons For Choosing A Planet Over An Asteroid
Planets are really really large things. And considering that most planets discovered outside out solar system are several *times* larger than Earth, it would mean that if a planet is coming at you, it is serious business. With an asteroid (even miles wide), you still have the hope of deflecting it by ramming it with a large, fast moving spaceship or try to break it up with several hydrogen bomb explosions in space (man that would be cool!).
Plus, if an asteroid was coming at you, the scientists would go on in a long, stupid, boring debate about whether or not it is on a collision course with Earth. Then talk about the variables of composition, speed, direction and blah blah to try and measure the extent of damage possible to Earth. All this would mean that while it would create some stir, there would be really little *panic* factor involved.
Now think about the shock when you read or listen that a **rogue planet** is on a collision course with Earth. Oh man, the horror! And another important difference would be that there would be little math involved with deciding whether the said planet is on a collision course with Earth or not.
Even if the scientists decide that the said planet is not on a collision course with Earth and would instead pass near Jupiter (I can tell you that's a huuuge distance between Earth and Jupiter, nearly 3 times the distance between Earth and the sun), still Earth would be at serious risk. The planet might deflect the orbit of Earth. Even a small change in Earth's orbit would spell doom to the reign of these puny creatures known as homo sapiens. And even if Earth is unaffected, the planet can still cause lethal damage by disturbing the orbits of Venus or Jupiter or Mars. Heck! Even deflecting *a few* asteroids from the asteroid belt (between Mars and Jupiter) inwards would be enough to cause an extinction level event.
# Size Of The Planet
Naturally George would want to make the planet as large as naturally possible, in order to increase the shock and hysteria factor. But larger planets are also easier to detect, and so the lie would not hold for long.
No, not really. You **can** have a Jupiter-sized planet while still making it impossible for amateur astronomers to see it.
# Making The Planet Undetectable For Amateur Astronomers
Ever read or heard about [TrEs-2b](https://en.wikipedia.org/wiki/TrES-2b)? I mean the planet, not the member of worldbuilding community. If not, then know that it is *THE* darkest (and also one of the most horrific) planets ever discovered. It is so dark that it reflects *less than 1% of all light falling on it*. And then again, its orbit is shorter than Mercury's orbit. What's more, it is a Jupiter-sized planet.
The important thing about TrEs-2b is its darkness. This planet is the darkest planet discovered so far, although it is revolving horribly close to its parent star. What about a rogue planet with an atmosphere like TrES-2b? It would be simply too dark to be seen from any and all telescopes by amateurs. Heck! It wouldn't even be seen by many professional telescopes operating in the visual light range. The only way to detect a planet such as this would be through infrared or microwave telescopes (which, luckily for George, are extremely sparse, even at professional level).
# Velocity And Distance Of The Rogue planet From Earth
Scientists have theorized that an angry rogue planet can get shot out of its former orbit at a [frighteningly high velocities](http://www.dailygalaxy.com/my_weblog/2012/03/-warp-speed-planets-escaping-milky-way-at-30-million-mph-1.html). We are talking about *10 million miles per hour*. That is more than 2700 miles per second. In 6 weeks, the planet would travel 1.008 x 10$^{10}$ miles.
Another important thing to keep in mind here is the radius of our solar system. Neptune is located 2.84 x 10$^9$ km from the sun ([reference](http://www.universetoday.com/15585/diameter-of-the-solar-system/)).
This means that George can place his imaginary planet 5 times away from Neptune and it would still come crashing into Earth within 6 weeks. ...and then they say train collisions are horrible to watch...
# Direction Of The Rogue Planet
In order to offer least hope and create maximum frenzy among the scientific community, George would prefer entering the rogue planet from an angle where its path is least affected by the gravities of outer gas giant planets. An image is being uploaded to help George on this.
[](https://i.stack.imgur.com/bksoF.jpg)
# How Much Time It Will Buy For George?
At most 5 weeks (if the credibility of the functionality of the radio and infrared telescopes is not reassured) and at least 4-5 days (this much time would at least pass in ascertaining that all hardware and software are working flawlessly and that the system has not been hacked).
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The big problem which George has overlooked is the amateur astronomy community. The first thing that will happen when the news is released is that hundreds of (in some cases quite decent) telescopes will point at the reported coordinates and see --- nothing. There are thousands of these folks, and they talk to each other. The word would spread pretty quickly that there's a problem.
How decent is decent? Well, [this company](http://www.obsessiontelescopes.com/telescopes/25/index.php) will sell you a 25 inch Dobsonian for 15k. Compare this to the Mt Palomar 200 inch, and it's only a factor of 64 worse. Now, it's true that most amateurs don't have the advantage of really good cooled CCDs for long-term exposures, but some of them do. The pro's also have locations which offer good seeing conditions (like mountain tops) but that actually won't help all that much. The point of amateur detection, after all, is not precision imaging, but rather detection.
EDIT - I see that my point has been missed. By providing a link to a 25-inch telescope, I did not intend to provide a limit on amateur efforts. A quick Google on "largest amateur telescope" provided a link to [a 50-inch monster](http://www.telescope.com/Orion-50-Monster-Dobsonian-Telescope/p/9162.uts) which any fanatic can buy, and also to someone who showed a bit of ingenuity and recycled a damaged [70 inch mirror](http://www.dailymail.co.uk/news/article-2487485/Utah-truckdriver-builds-worlds-largest-amateur-telescope.html). While this is touted as the largest in the world, it may or may not be the king.
Assuming 70 inches is the maximum, you need to realize that George's story has to be credible in the discovery mechanism. For comet/asteroid detection, which would be the most likely source of discovery, a wide FOV survey of the sky is performed, followed by another some time later. Comparison of the two images reveals which objects are moving with respect to the celestial background. A typical effort (and there aren't many) is [Spacewatch](http://spacewatch.lpl.arizona.edu/) and you'll note that the largest telescope they use is 1.8 meters, which translates to (surprise) 71 inches. A more powerful scope might then perform the observations which produced the orbital parameters, but it's clear that amateur scopes could detect such an object. This is particularly true since survey images tend to be taken with relatively short exposures in order to permit mapping the entire sky (wide FOV is a relative term), while confirmation observations by amateurs could well utilize longer exposures. All else being equal, a 70 inch/1 hour exposure is the same as a 50 inch/2 hour exposure.
So I really don't see that George is going to get away with it.
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If George is simply looking for a distraction, he does not even need to hack into astronomical observatories or NASA. Since he will need some help, he can call his fellow evil villain Gru and hire several dozen Minions.
With their help, George can start spamming web pages, blogs, Twitter, and social media sites with reports of the approaching asteroid/cosmic catastrophe and flood the Internet with this meme. As astronomers and scientists go on line or on the air to dismiss the story as a hoax, George's team of spammers start filling the Internet with cries of "Conspiracy!" and "Cover up!".
The amount of confusion and rumours started with this campaign will distract people while George carries out his real plan (unless Pinky and the Brain beat him to it again....)
[](https://i.stack.imgur.com/iFMhe.jpg)
In case you think this is too far out, another evil genius by the name of Vladimir Putin has a "Russian Troll Army" of hundreds to thousands of people who's primary job is to flood the Internet with memes to distract or highlight issues and ideas which support the Russian strategy of the day. Ask the people of Georgia, Crimea or Ukraine how that is working for them.
[](https://i.stack.imgur.com/YflrG.jpg)
55 Savushkina Street, St Petersburg, identified as the HQ of the Russian Troll Army
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What kind of a society would exist for an intelligent species that lays it's eggs/young in a host to gestate/grow? We have the [spider wasps](https://en.wikipedia.org/wiki/Spider_wasp) which paralyze their prey and lay eggs. While sometimes the host survives, most of the time it is eaten alive.
We have also have the [botfly](https://en.wikipedia.org/wiki/Botfly), which lay their eggs on a host, though generally not causing it severe harm.
And of course we all know about this
[](https://i.stack.imgur.com/UhbF5.jpg)
It seems to me that unless they can only use specific species to incubate their young like this, that they would tend to be a rather uncompassionate species to any outsiders. Seeing any animal large enough to be a potential host/meal for their young.
Adding more details for those who need them.
In this case I was thinking they have reached as least the level of culture as Rome (any time in their 1000 year history).
The mobility of the host? I had nothing in mind, other than vaguely something like a sheep or deer up to an elephant.
How Precocious? I expect that when they emerge, they are at least as physically capable as say a fawn when born, maybe a little more. Mentally could be an infant working on instinct.
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A parasitic lifeform cannot just extend its catalogue of potential hosts any time it likes. The initial movies in Ridley Scott's Alien series appeared to have a large plot hole that it is inconceivable that a naturally-evolved species could successfully parasitise not one but three completely alien species (Humans, dogs (in Alien3) and Predators (in Alien vs Predator)), but the revelation in Prometheus showed that these were engineered bioweapons, likely made for the specific purpose of eliminating mammalian life. The fact that they can also reproduce in the completely unrelated Predators, as well as grow in places where there are no practical organic resources other than air (containing carbon dioxide) and electrical power suggests that they are more likely nanotech than biological.
That said, if we had an *evolved* sentient species with a potentially-lethal-parasitic reproductive habit, it is more likely that the parasitic part of its life cycle could occur in a number of related species, since in evolutionary terms, to restrict the valid hosts to one species is to render the parasitic species vulnerable to the fate of their sole host species, and most species have related species that are also vulnerable to the same pathogens.
To use a real-world analogy, those host species might be able to be described as 'Homeothermic land-dwelling vertebrates above 25 kilograms body mass', or 'Squid and Octopi', or some other group of creatures that occur in the same biome as our parasitic species. Unless 'Humans' fall into the category of potential host species, even if they did not co-evolve, they would almost certainly be unsuitable as hosts. If by some coincidence humans resembled a valid, but totally alien, host species, implantation might be possible, but gestation would most likely be unsuccessful. The survival of the human in question, while likely but not assured, is probably much higher than that of the *intended* host organism.
Regardless of the nature of the potential host species, we must consider that obtaining a host is a reproductive necessity. By extension, we can reason that any successful parasitic species with any kind of mind at all, let alone extelligence (having a recorded culture) must develop an affection for its host species, and would most likely keep the host species around as pets, to be on-hand when it came time to reproduce. The hosts would be bred, pampered, nurtured - and then implanted, and nurtured some more, until their offspring killed the host, at which point the carcase would be devoured by the offspring.
Consider the effort and interest that humans put into reproduction. There would be no question of *whether* the members of the parasitic species kept host-pets, but *how many* and *which species*. If humans were obligate parasitic reproducers with other mammals, it'd be like asking, "Do you prefer dogs, cats, rabbits, sheep, goats,"... etcetera, and to receive a "I don't like pets at all" answer would be practically inconceivable, and would probably represent some sort of monastic, non-reproductive life-choice.
The species used as hosts would be selected to have traits that made them suitable as pets, including appropriate size and other traits that enhanced the survival of the parasitic species' offspring, as well as docility, up to and potentially beyond the point of implantation with the parasitic offspring. It would likely be far less risky to implant a pet than to try to implant a wild animal. It is likely that - if possible - the host-pets would be desensitised to the act of implantation by repeated instances of play-implantation. Species of host-pet that came to enjoy play-implantation would be highly prized.
While it is possible that the act of implanting the parasitic embryo - or even play-implantation - would be injurious to the host, in evolutionary terms, the longer the host survives post-implantation (until at or near birth of the parasitic offspring), the better, since we are talking about a parasitic species, not a sarcophagic species. Since in wild conditions, *any* injury can be fatal, from infection if nothing else, evolutionary pressure would be to minimise the trauma of implantation.
If humans were not on the list of the parasitic species' potential hosts (since, for example, they are from different worlds), then even if humans resembled a valid host, it is unlikely that they would be selected as a host, since the humans would most likely be seen as falling into the 'risky wild-animal-host' category.
If humans were not a typical host, but were a potentially valid host, it is still unlikely that a human might be selected as a host except by a thrill-seeking type of individual/couple who likes the thrill and danger of trying to implant wild - as opposed to domesticated - hosts.
If humans *were* amongst the list of valid hosts - which is unlikely given that human sentience enables us to realise that being a host is highly detrimental or even fatal - then human hosts would likely be kept as pets (or at best second-class citizens), and for the most part kept ignorant of their true purpose *as* hosts for as long as possible.
As for the parasitic species relationships with non-host species, there is no reason why we should assume that they might be any worse or more cruel from what they might be if the species in question were *not* parasitic reproducers. If we suppose for a moment that humans are parasitic reproducers with other mammals, that wouldn't change the way we relate to non-mammalian species, except perhaps in a positive way. Being biologically habituated to keeping pets (for reproduction) would tend to make keeping non-reproductive pets more likely. If humans kept other medium to large mammals around for reproductive reasons, we might still be *more* likely to like keeping birds or fish or small mammals than we already are as a non-parasitic species.
If our parasitic species did not see humans as a valid host, they would *still* be quite likely to be friendly, given their predisposition toward close association with other species (even if those other species *are* reproductive hosts). The potential problems might arise from the human side, as I can imagine that humans might be less than thrilled to find that a species that acts like Ridley Scott's Aliens to non-human species wants to be friends with them. As a case in point, Larry Niven's [Pierson's Puppeteers](https://en.wikipedia.org/wiki/Pierson%27s_Puppeteers) are concerned that revelation of their reproductive biology (which is stated to be similar to that of a digger wasp, very similar to that in the question and this answer) to other species would lead to negative reactions towards themselves.
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That's a valid argument and it is certainly possible for an alien species to have that mindset. However he Xenomorphs were shown to care for their young and their eggs, so it's not the only argument.
Consider that most humans are at least partly carnivorous, we live by consuming other living things. Hatching our eggs inside them isn't really *that* big a departure. After all in theory we could see anything vaguely edible as potential food but dogs, horses, cats and much more for the most part go uneaten.
The key thing would be for these other species to achieve a mutually beneficial symbioses much as we have with the three species I list. By doing that both gain by working together and the urge to use Fluffy as an egg incubator is not actually a successful survival strategy when Fluffy can help you hunt down something else to do the job.
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Imagine a scenario where the moon is not tidally locked with one side facing the earth but where it is able to rotate about its own axis. This could be due to a larger distance from earth or a mildly smaller mass of our planet.
My question is how would this changing face of the moon as viewed from the earth affect the development of humans. People have observed and worshipped the moon for millennia so a rotating moon must certainly have an effect on mankind.
This could have led to the discovery that celestial bodies are spherical earlier and led to the introduction of a heliocentric model earlier. Perhaps we could even have reached the space age centuries earlier.
What other possible effects might such a scenario have on a human population here on earth?
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There's no way to answer this with any great confidence.
# Science
As @Rugnir has noted, the spherical moon and earth were well known already to the Greeks, and there is good reason to think that this was also known in early China and India. If memory serves, it is somewhat unclear whether the ancient Mesopotamians knew this. But in any event, a rotating moon would presumably not speed up this early discovery.
One thing is that the analogy between a rotating moon and the rotating earth might have led somewhat earlier to a strong preference for heliocentric models. These were in fact proposed quite early among the Greeks, but were so annoying to calculate that, in the absence of strong evidence in their favor, they tended not to be followed up effectively. Since at base Copernicus's proposal was a matter of advanced geometry rather than (for instance) algebra, it could have been developed earlier. And if there were a strong preference for such a model, it might well have stuck firmly enough for geometers and astronomers to work out the kinks (as did not happen in European history until relatively late in the 16th century and on into the 17th with Kepler).
In addition, because the moon rotates and thus alters its appearance, the use of lenses to examine its changing faces might have been of significant interest rather earlier than Galileo Galilei.
On the same point, the irregular image of the moon might have led to a much earlier undermining of the "perfection in the heavens" assumption that dominates Ptolemaic astronomy.
# Culture
Cultures do tend to come up with notions about what the moon looks like, and develop mythological conceptions and descriptions. In Japan and parts of the Americas, the moon looks like a rabbit -- in Japan, it's a rabbit pounding *mochi* rice. In Europe, an old man's face is more common, though there are of course other notions.
I suggest that the changing faces of the moon would be classified and named, on the model of constellations. Within any given culture, a "rabbit moon" would differ from a "scorpion moon" or a "flower moon," or whatever. Each would then generate a range of mythological conceptions and stories.
These might in some cases have relatively concrete effects. For instance, it is quite common to ascribe both vulpine (wolf-like) and insane qualities to a full moon (thus luna-tics and werewolves). With a rotating moon, you might well get these kinds of ideas ascribed to particular faces of the moon rather than its phases.
More interestingly, I suspect you'd get both: a scorpion moon at the waxing half is understood to be especially dangerous, a full flower moon is especially calming, and so forth.
If I were doing this for a story, I'd probably come up with a bunch of images and concepts for the faces, then work out their notional implications at especially strong phases. But I don't know if you can get decent images of what the moon would look like -- of course, you don't have to use our moon.
Note that in many ways the moon will take on a considerably stronger role in astrological thought, but whether that's of use to you depends on whether you're planning to work out anything much in the way of astrology in the first place.
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Probably the greatest cultural difference would be the undermining of the idea that the "Heavenly sphere" was fixed and unchanging.
Since much of the heavens do appear to be relatively fixed and unchanging, it was fairly easy for ancient priests and philosophers to believe that the heavenly realm is truly different from the mundane world that we live in. The planets and the Moon were obvious exceptions to the idea of a fixed and unchanging cosmos, but the planets became mythological beings, while the general consensus among the "educated" people of the ancient world was the moon was a perfect sphere, and we were seeing the reflection of the Earth on the Moon's face.
This sort of attitude tended to sharply divide science and religion/astrology, since the various rules and ideas that seemed to work in the mundane world were obviously not in play in the celestial sphere.
A rotating moon, on the other hand, isn't so easily explained. It is pretty obviously a world in its own right, and while the idea that there were other worlds did exist in ancient times, it was considered a very eccentric notion at best, and rapidly died out. With the example of a world visible in the sky visible to everyone, the idea that the planets might be other worlds would not be so difficult to accept, and the sharp boundaries between the heavens and the Earth would not exist (or be much harder to justify). Notions like "there are other worlds", a heliocentric solar system and that natural laws apply everywhere and not just on Earth would have a much greater base, and rather than a "Scientific revolution" we would have a much more gradual and possibly board based growth of science as the philosophical world view of most people.
Specific changes to history would be difficult to imagine, although it is probably safe to say that Hero of Alexandria isn't going to be inventing liquid fuelled rockets. More likely society and culture will not be so structured with a priesthood claiming divine and mystical powers not accessible to mundane understanding, since it is obvious to most people that "mundane understanding" applies everywhere. A more fluid social order is the most likely outcome, and oligarchies, republics and democracies will be more common and arrive earlier than in OTL.
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According to [this](http://www.bbc.com/future/story/20140105-timeline-of-the-far-future), the Earth's core will be frozen 2.3 billion years from now.
Assuming humans still live on Earth, (a much smaller and inconceivably more technologically advanced population) how might we prevent this?
This is very broad, but not, in my humble opinion, too broad. **What might we do to keep our magnetic field** is a better question, and is, really, the underlying question in all of this, because we have no need for a molten core if we have another way to generate a magnetic field.
**So, assuming humans live on Earth and want to maintain it as a monument as long as possible (we have likely spread through the stars by this point, assuming it is possible for us), how could we either maintain the magnetic field at its current strength or keep the core around to maintain it?**
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[sdrawkcabdear was spot on](https://worldbuilding.stackexchange.com/questions/38070/how-to-stop-the-earths-core-from-freezing#comment106253_38070) that we might have the problem solved if we wait long enough. The exact fate of Earth is up for debate, but it is generally accepted that the Sun will exit the main sequence in ~5-5.5 billion years and reach the tip of the red giant branch ~2 billion years beyond that (see [Schroder & Smith (2008)](http://arxiv.org/abs/0801.4031)). Its maximum radius will engulf much of the inner Solar System, possibly including Earth.
If the core can hold out for about 7.5 billion years, then the problem of reheating it will go away - as will the core, for that matter, along with the rest of Earth. Let us, however, assume that we see a best-case scenario, where the core cools off much sooner than this. We can then get back to the question at hand.
The Earth gets [its internal heat](https://en.wikipedia.org/wiki/Earth%27s_internal_heat_budget) from two places: The cooling core and radioactive decay of elements in the mantle (to a lesser extent). I would advise reading the answers to [Why has Earth's core not become solid?](https://physics.stackexchange.com/questions/80159/why-has-earths-core-not-become-solid) for more information. Once the core finishes cooling to the level that a magnetic field is no longer produced, the residual heat in the core will be about exhausted. Radioactive decay will not help the magnetic field, though, as the elements are situated in the mantle and crust.
Obviously, reheating the core is going to be impossible. You would likely have to reform the Earth to do so, and that will cause many more problems than it will solve. The core will freeze. This then leaves us with only one other option to save the magnetic field: To create an external, artificial magnetic field. [This answer](https://worldbuilding.stackexchange.com/a/22534/627) notes that it is possible to induce a magnetosphere (*not* a magnetic field), as is the case with Venus and Mars (from the solar wind) and Titan (from Saturn). I see no reason why the solar wind would not induce a magnetosphere on Earth naturally.
That said, I think you’d be better off trying to replicate the effects of Saturn’s magnetic field [“rubbing off”](http://saturn.jpl.nasa.gov/news/features/feature20080911.cfm) on Titan when the moon briefly passes through the planet’s magnetic field. Unfortunately, [the effect only lasts for about three hours](https://www.newscientist.com/article/dn14717-saturn-magnetises-its-moon-titan/). However, perhaps a closer orbit involving more time spent inside the magnetosphere could increase this period. So, all you have to do to keep the magnetic field going is to bring Earth into an orbit around Saturn (or Jupiter, for that matter) and hope for the best. That said, perhaps you *could* merely copy the gas giants’s magnetic fields. All you have to do is build a massive artificial planet, create a core that will produce a magnetic field, and put Earth into orbit around it.
At this point, though, you’re probably better off just moving somewhere else, if you have the kind of technology to make this possible.
Anyway, in conclusion, you won’t be able to reheat the Earth’s core without essentially recreating the birth of the planet, but with a little a *lot* of luck, time, money, and energy, you can maybe induce a new magnetic field.
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One of the reasons the Earth's core is still "hot" stems from the fact that it contains [significant quantities of heavy, radioactive isotopes](http://newscenter.lbl.gov/2011/07/17/kamland-geoneutrinos/) (including Uranium, Thorium, Potassium, and others). The heat produced from this radioactive decay helps maintain the mantle in a hot liquid state.
Presumably, injecting additional quantities of radioisotopes would help active lifetime of the inner mantle, allowing it to remain liquid and sustain a magnetic field. Over geological timescales (such as what you're talking about) additional radioactive material could be gradually introduced at subduction zones, where its density relative to other crustal material would allow it to sink toward the inner mantle.
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Since much of the heat in the Earth's core is produced from the decay of radioactive elements, it may seem trivial to simply assume that you can inject more radioactive elements into the core to make up the deficit.
The real problem is that the Earth's core is in the centre of the Earth, and the static pressure will collapse any conceivable tunnel or bore hole long before you reached the core (probably before you even penetrate the crust and reach the mantle)
Getting energy into the core might be achieved in several ways:
Firstly, drop a slug of anti-matter condensed to neutronium density into the core. Neutronium will pass through most ordinary matter like it isn't there, and with some clever calculations, it can be launched in a trajectory which allows it to come to a stop at the centre of the Earth's core, where internal gravitational effects are essentially zero (gravity is cancelled out because all the matter attracting you surrounds you in a sphere. I have not been able to find the total heat energy contained in the Earth's core, but the Atomic Rocket's "Boom Table" suggests that the Earth has a heat flux of 4.4X10^13 J/sec. The upper limit is the binding energy of the Earth itself; exceed that amount and you have a glowing cloud of gravel rapidly expanding through the solar system (2.9X10^32J). (Boom table is found here: <http://www.projectrho.com/public_html/rocket/usefultables.php>
By controlling the amount of antimatter, the reaction will convert a small fraction of the core into energy, which will radiate outwards and melt the rest of the core. Since one milligram of antimatter + one gram of matter releases 1.8X10^11J of energy (about 4X more than a MOAB), you can see that this is a delicate balance.
The second semi plausible suggestion is an immensely powerful neutrino beam, as suggested in an article in New Scientist: <https://www.newscientist.com/article/dn3734-neutrino-beam-could-neutralise-nuclear-bombs/>.
The beam would not only deliver energy to knock nucleons from the densely packed atoms in the Earth's core, but also release a vast amount of alpha and neutron radiation as well. To maximize the effect. having three beams intersecting at right angles at the core would provide a "hot spot" capable of melting the core and releasing heat over a period of centuries. This is much slower than using antimatter, but probably a bit easier to calibrate. Since flinging chunks of antimatter through the solar system might be taken the wrong way by polities orbiting other planets, this might be more acceptable to whoever or whatever is inhabiting the solar system at this time.
Finally, in about one billion years, the increasing luminosity of the Sun will have baked away most of the Earth's oceans and atmosphere. If anything is "alive" on Earth at this time, it may be some form of machine intelligence or something incomprehensible to us, which isn't bothered by the lack of a magnetosphere, oceans or atmosphere anyway.
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I'll avoid trivial answers. I shall assume the Earth can be protected from the growing heat of the sun and the goal of this project is to keep the core of the earth warm. Also, this is not a science based tag so there will be no equations.
Let's begin:
**The Magnetic Feild**
The Earth's [Magnetic Feild](https://en.wikipedia.org/wiki/Dynamo_theory) is thought to be produced by a [Geodynmao](https://en.wikipedia.org/wiki/Dynamo_theory) and is the result of the interactions between [convection in the core and Earth's rotation](http://seismo.berkeley.edu/~rallen/eps122/lectures/L07.pdf). The outer core is still liquid due to the primordial heat and radioactive decay (there is even evidence for a [fission reactor](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC58687/) in the core), while the inner core is solid due to the immense pressure.
**Inner and Outer Core**
As has been pointed out they are hot and hard to reach. You can read up on the specifics of the inner core [here](https://en.wikipedia.org/wiki/Inner_core) and outer core [here](https://en.wikipedia.org/wiki/Outer_core). For the purposes of this project, there are only two things we need care about: the inner core needs to stay solid and the outer core needs to stay liquid.
**Save the core, save the magnetic field**
All we need to do is keep the outer core liquid. How? By delivering an enormous (by our standards at least) amount of energy to it. Firstly it *could* be done without remelting the whole of the earth. Humanity of the far future should be able to harness that kind of energy.
I don't see a chunk of [neutronium](https://en.wikipedia.org/wiki/Neutronium) as being able to work because neutron matter when not in a neutron star decays rapidly, plus there is no real good way to keep it together to the core. Making it out of antimatter won't help if it can't reach the core either.
A beam or beams of neutrinos could very well deliver that heat to the core but the overwhelming majority of the energy in the beam would pass through the earth and be wasted.
So how do we keep the core of the Earth molten is a relatively practical way? Here me out: An Ultra High Energy Neutron Beam (UHENB) look closely not neutrino. Now this beam of neutrons won't be able to penetrate all the way to the core of the earth so it will need to be installed deep within the earth. By this time the [mantle](https://en.wikipedia.org/wiki/Mantle_(geology)) will have cooled greatly, and to be fair it's not really even molten. There will need to be a shaft a couple thousand miles deep into the earth for this project. This is doable, firstly a cooler mantel means the digging will be easier. The harder part will be preventing the shaft from collapsing under the pressure. I won't hand wave and say some super strong material. It *could* be supported by many layers of walls nested together with the spaces between the layers pressurized. The same principal was employed in old vacuum chambers. There are plenty of materials that can tolerate the heat and throw in a giant cooling system for good measure.
Why a UHENB? Because the neutrons have a half-life of about ten minutes and when they decay you get a good amount of energy. Those neutrons will also release energy as their kinetic energy is dumped during collisions or breaking apart atoms they encounter which is a bonus because those decay products add more heat. Your run of the mill neutron beam has pretty good penetration, amp it up several orders of magnitude and the beam could penetrate hundreds or thousands of miles in the core. But here is the key, at such high energies the beam will initially pass completely through the matter in encounters only after slowing down will it really begin to heat up the material it is passing through.
**The Set Up**
A thousand mile long particle accelerator that's business end is deep in the earth, protected from the heat and pressure by pressurized nested layers of walls. It's powered by the sun since the sun radiates more than enough heat energy to warm the earth. The whole system would be built at the poles with the neutrons directed into the outer core on a path tangent to the inner core and pointed slightly in the direction of earth's rotation. There could even be several of them. So now you are dumping energy (heat) into the outer core, adding a little energy to its rotation and increasing the radioactivity (heat). The outer core stays molten and rotating, the inner core stays solid and all the energy in the beam is captured by the earth.
**Edit:**
Turns out neutrons don't actually behave quite the way I described. According to [this](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3429896/) there are better are better forms of particle radiation for the task. An Ultra High Energy Particle Accelerator is what you will need, and a beam of whatever particles will do the trick.
Also, should add this will take a long time and the beams of particles should be swept around to improve heating and reduce hot spots because super volcanos are bad.
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I read [this question](https://worldbuilding.stackexchange.com/questions/37784/how-do-the-zombies-win-when-theyre-so-weak) about how relatively weak zombies might cause complete global societal collapse, and an idea popped into my mind.
The zombies I am imagining;
* They are living humans inflicted with a disease.
* They can be killed by anything a regular human can.
* The zombies travel in packs of ten to twenty infected, though they can grow to up to one-thousand strong in rare cases.
* Opposing zombie packs can either fight each-other or merge into a larger pack. They are lead by the strongest individual.
* Zombies need sustenance. When no large packs of infected are around and when no humans are around they will search for water and food and shelter.
* Can use basic tools such as door handles and crowbars
About the virus;
* The virus can be spread by infecting rats (and any other rodents) who later become rabid and swarm uninfected. Raccoons, opossums, and most marsupials are able to catch and transmit the virus as well as pigs and apes/chimps/monkeys. Other animals are not able to become infected.
* The virus is blood-borne, and saliva-borne, meaning bites will transmit the infection as well as getting infected blood in your body.
* Once someone is infected, that person has 24-96 hours until "transformation." The first 75% of this time you experience no symptoms. Then a fever sets in and you have pounding headaches for the final 25% before you pass out and reawaken as a "zombie."
* The zombie virus kills any and all disease-causing organisms in the body.
**I ask, would the virus spread in small towns in central and southern United States as quickly as in the cities?** I imagine that the virus would mainly affect the big cities before groups of infected wander into the countryside. How towns handle the infected would vary. Some might try to treat them, and these towns would be the first to go. Beleaguered military divisions and routed National Guard units would likely fall back into the country as well, undoubtedly carrying a few infected soldiers with them.
I ask this because I live in a small town in southern Illinois called Iuka, and just about everyone here owns a gun. There are literally ten year olds who have guns. Outside the town there are dozens of farmers, and each one probably has enough rifles and hand guns to supply a small army. In the city this would never happen.
The sheer number of people in cities means laws must be in place to heavily regulate the ownership of deadly weapons. In small towns, it seems these laws do not exist, or, at the very least, are not enforced. I personally think my town is ready to take out swarms of rabid raccoons, opossums, and rats. God knows we have enough ammo to pump every animal in the region full of lead a few times over.
Would the time allotted to small towns1 make any real difference in their fate?
How would the limited social structure of my zombies affect the ability of small towns to resist?
1 Of course, some towns would fall as infected people fled the cities, but I am assuming **most** towns would have a decent chance to prepare as opposed to the cities.
[Answer]
There's two main category of issues when discussing this situation:
**Can they get organized?**
"Small-town America" is a lot more self sustaining than city folk are, and a lot more prepared to survive. However, these people are going to have to form a unified front against not only the incoming zombie hordes, but also the fleeing survivors.
Issues such as: do we help outsiders, do we share food/guns/ammo/fuel, do we provide shelter, do we defend others, how do we deal with potential infected, etc. will be very divisive.
Will those people come together as a community and help each other out, or will half of them barricade themselves in their homes and shoot anyone who gets close, while the other half try to help everyone who arrives into town, only to be taken advantage of by opportunists, or simply overrun by zombies?
A lot of towns will fail to find the appropriate balance and simply go under.
When civilization collapses people need a ***clear authority figure*** to impose law and order in the area.
With the survivors themselves posing a threat, never mind the zombies, what sort of leader you get is going to be one of the main deciding factors.
An impulsive and rude leader would probably polarize the community and influence their destruction.
A sensible human being will realize that everyone can't just go off on their own. That certain farms and outlying homesteads have to abandoned, resources pooled and policed, that not everyone who needs their help is worth saving, etc.
**The virus itself**
Now on top of those issues you have to deal with the virus itself. A lot of townsfolk - even some of the ones with key skills and knowledge - are going to get sick. If the virus is as infectious and easy to spread as what that original question seems to imply, then really, these towns may not have a chance anyway.
Frankly, the survival rate of the virus is going to be the deciding factor in whether all those other issues even come into play.
**Conclusion**
Realistically, the best way for these folks to survive is to "retreat" to a defensible position, and hold what they've got. This might be a particularly isolated estate with clear fields of fire, a local prison, or simply the "town center" (with all approaches barricaded, manned, and patrolled).
They can probably grow food in the outlying fields, and will have *some* local manufacturing capabilities.
However, they ***will*** lose people to the virus. They would do well to keep an eye out for survivors who are immune and can be integrated into their group, while rejecting those who seek a free handout/ride.
[Answer]
I am not certain but I'm pretty sure you will either be infected or die from starvation, disease, lack of water or other such fatal conditions.
**Infected**
Many towns will probably go down to the zombies as humans will probably flee the cities bringing the virus with them. Any town that accepts refugees from the cities will be infected and will fall. Other towns might refuse to let anyone in and kill anyone who tries. These towns may stop the virus but it is more likely that a few rats will sneak in and start infecting humans.
**Other deaths**
Even if you keep out the infected you will have no electricity as power stations go down with no one to run/maintain them. You will have only the food you can grow, and you have to grow it without fuel or piped in water. The only water you have is water from water towers. On top of this any water pipes and sewage pipes will have to be blocked to prevent rats getting in. Eventually the population will drop too low to effectively prevent zombies from getting in and the zombies will break in and kill anyone left.
[Answer]
## With minor deviations, you've just described rabies, and rabies hasn't destroyed the world yet.
The transmission behavior matches rabies almost exactly, except for the incubation period (usually 1-3 months according to Wikipedia).
Rabies doesn't include pack behavior, and replaces the urge to bite people with general violent urges. However, to include pack behavior you need a pack, and I'm not convinced your zombies would ever reach those numbers.
Zombism is enough like rabies that people will mistake it for rabies. Which is good, because the typical handling of a rabies outbreak (Don't get near, don't get bit, don't expect a rational response or a recovery) are excellent methods for dealing with a zombie outbreak.
You might argue that we're more at risk from a zombie outbreak than from a rabies outbreak because there is a rabies vaccine but not zombie vaccine. But the rabies vaccine has only existed for a century and a half, and rabid animals hadn't taken over the world in the meantime.
Blood and saliva borne transmission vectors are really terrible ways for a disease to spread.
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The setup:
We have space cadets who have ascended the ranks of their military order, and they're ready to go through some final Trials of Fitness with their head-honcho and soon-to-be commanding officer. He takes them to several different environments (perhaps in space in their starfighters, and perhaps on alien worlds where they may encounter alien flora and fauna) to prepare undergo these final Trials.
**What are trials they might undergo in order to test the proper skills for being a space cadet? I'd be curious to hear of scenarios designed to test specific skills from real military training that could be adapted for space cadets.**
Assumptions:
* The space cadets are human for all intents and purposes.
* Their society hasn't been at war for a long time, but it's required that every top-notch space cadet get this special training when they reach this rank.
* The head-honco CO takes them in small teams to do the training.
* They have probably already undergone several years of military training.
* These trials may or may not be deadly if the cadets fail.
* The trials do not have to all involve spaceships. For example, the CO might take them onto a planet to do some training specific to a certain skill s/he is testing.
* Commenters asked if there is artificial gravity. Let's say yes. They also asked what will the cadets do: pilot starships (big and small)
* Others indicated that "cadet" is the wrong term to use for high ranking military officers. Assume whatever rank makes sense to you based on the question.
Possibly relevant:
[https://worldbuilding.stackexchange.com/questions/22901/combat-training-for-a-multi-species-society#*=*](https://worldbuilding.stackexchange.com/questions/22901/combat-training-for-a-multi-species-society#_=_)
[The military application of predictive modeling](https://worldbuilding.stackexchange.com/questions/17126/the-military-application-of-predictive-modeling)
[Answer]
As the edit notes, "cadet" isn't really the right word.
* Consider the Royal Navy [submarine command course](https://en.wikipedia.org/wiki/Submarine_Command_Course). Experienced officers get first an intensive course and then an intensive evaluation before they get to command subs on their own. The training covers technical aspects of shiphandling and the ability to cope with stress and exhaustion.
* Stress and exhaustion also feature in special forces schools on land. They try to simulate the stress and terror of being shot at with shouting instructors and too little sleep.
[Answer]
As the previous answers have indicated, cadet is usually a rank reserved for personnel still in training, typically with no out of classroom experience.
The description you give though is one of advanced training given to personnel have already proven they've mastered the basics (e.g. special forces training).
### Basic Skills
Your "troopers" should have mastered all the basic skills. The should be familiar with and able to use all equipment they would normally encounter in their job. If the equipment is the right type (e.g. survival equipment), they should be able to use the equipment *without thinking about it*.
### Advanced Skills
In the training you describe, your troopers will learn advanced skills to make them more valuable team members to the CO's team. This might be hacking, sniper, demolitions, close combat fighting, communications/cryptographic, etc. Which skills they would learn would depend upon the role of the unit and its likely needs as well as where that particular trooper fits in the unit. You can expect each team member to be in the top 5+% of the population in these skills.
In most cases, all unit members will be at a minimum competent fighters in a wide range of skills.
### Survival/Environmental Skills
Your "troopers" will learn to survive **and accomplish their mission** in a wide range of environments which include all of those they're likely to encounter during their mission plus many they aren't likely to encounter. If this means running around on an icy Moon of Jupiter, suitable training for that mission will be provided.
### EE training
Escape and evasion training. If your troopers will receive training about what to do if they become separated from the unit, how to operate to decrease their chances of getting capture and what to do if they are captured by enemy forces.
### Interrogation Resistance
Troopers entrusted with very valuable information may receive training on how to resist torture. The goal isn't to prevent them from revealing the information but in delaying it. Hopefully it's delayed enough that your team isn't harmed by the release of information.
[Answer]
What skills were taught at Cadet Training? Tests are an assessment of what is expected knowledge/skill/ability.
The point of training/school is to teach those required skills and knowledge. Start with what Space Navy expects from its personnel, design your training regime around that, and then design your assessments as the opportunity to show competency in those expectations.
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Side Note:
Cadet sounds like the rank of someone about to *enter* the defence force. People completing bootcamp/initial training are often given the rank of Pvt/AB/AC/etc, and then promoted as they gain experience and progress through further training (but mainly experience).
A soldier should have a moderate NCO rank by the time they are picked for any elite squad.
The wording of the question implies that they're already a service person. As such, they will already have a military rank.
[Answer]
probably problem solving and instinctive stuff like that, things that cant be trained or taught and cant be programmed to be done better by a advanced computer. anyone can become physically fit and it would probably be a required part of the training; if the setting has interstellar travel and combat, it would also be logical that most of the basic operations of piloting would be completely automatic. i know a lot of universes try to justify space fighter combat being handled mainly by humans by saying that humans are more creative or quicker on their feet or whatever, but any civilization that has such advanced technology in other fields really shouldnt have any problems with making pretty good AI. also, related side note about starfighters: it would probably be a better use of resources, not to mention much more plausible, to have the cadets take control over larger drone carrier ships and focus on directing the larger scale movements of the drones (yes, i know thats what enders game is about. there is reason its so famous). anyway, the main things you should be testing for: intelligence, lateral thinking, strategy & tactics, and maybe diplomacy if you want them to also be explorers.
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Test one. Alien invasions simulation.
Location earth.
Method: computer simulator.
Test two rescued operation.
Location: space
Method:real ships, fake in dangered crew.
Test exploraction:
Location: uninhabited plant.
Goal find a object hidden on the plant.
Test 3. Attach simulation
Goal destroy an enemy military space station.
Location earth
Method: computer simulator
[Answer]
A fundamental problem with your question is that "space cadets" is way too broad.
If they have to do everything, the training program will take 20 years or something ridiculous. Anyone who graduates from the program will end up as a jack of all trades, master of none.
A more practical approach is to have subspecializations. Separate sci-fi military operations into several different branches: capital ship operations, scouting and exploration, science and engineering, fighter pilots, marines (specializing in ground combat in widely varying planetary environment), colonization, logistics, med/evac.
No serious modern military of world-class size rolls everything into a single blanket category. At the minimum, there will typically be separate branches for ground troops (army), sea warfare (navy), and airborne combat (air force). There's a good reason for this.
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The scenario; suddenly a modern human world finds their nice, simple, understandable spherical world/solar system going poof overnight, and it being replaced by a mine-crafting plane world. Everyone there was [transposed?] to the transformed world/universe, continents unwrapped and applied similar to unwrapping a globe without massive continent stretching. This world extends in the cardinal directions until infinity, and is stable. The how and why this happened is unexplained (and really cheeses off the scientists of the world). Everything that's man made in “orbit” simply falls down (really sucking for some astronauts). The sun and moon, however, still appear at their regular intervals, driving most remaining scientists to drink.
The terrain beyond the “explored” parts of the world appears to be completely new, with new flora and fauna being observed not even a handful of miles beyond the “borders.”
After the requisite upheaval of society and its reformation, some enterprising corporations and/or governments decide that there might be gold in them-theiar hills. The land “near” established areas certainly has a high premium in terms of value, but it is realized that there’s literally an infinite amount of it out there, if you could only get at it.
This presents a problem for exploring/prospecting/generally getting “there”;
1. Boats work ok for areas that can be reached by water, but are unsurprisingly not that good at crossing land masses
2. Planes can travel pretty far, pretty fast, but without a prepared landing area no pilot wants to set down, limiting how far out they can go before they have to turn around and come back the hard way.
In this new era of exploration, it is determined that expeditions are well served still by wagons … big, metallic, monstrous, possibly-nuclear-powered wagons. My question is:
What form do these expeditionary ‘wagons’ look like?
Are they single monolithic vehicles or a hive of smaller ones? Do I stick an oil rig on treads and call it done, or get ten thousand Ford Broncos? They should be built with more or less modern technology and avoid hand-wavium where possible. The goal of these vehicles and their expedition is to take men and materials out into the wilds, traveling for months and possibly years, with all the potentially heavy tools they would need for exploration and survival (and depending on which government, come back.)
The main issue is do the expeditions invest in one massive factory vehicle that can, for example, have a built in oil drilling platform and hydroponics? (Ex; aircraft carrier on wheels.) Or do they take hundreds of smaller specialized vehicles? Or something else entirely? I would like logical reasons for avoiding investing heavily sea and air travel for these expeditions, but if the reasoning is overpoweringly pro-water or pro-air travel I can accept that too, but would like the reasoning.
[Answer]
**Get a convoy.**
A single large vehicle requires firmer ground, is harder to transport over water, and is more susceptible to mechanical failure. If one of your Broncos breaks down, your worst case scenario is that you ditch it and load up the rest a bit more heavily. Large land vehicles tend to have more trouble with steep grades or with rough terrain, as well, which you're likely to run into if you're travelling long distances over undeveloped land.
Your convoy of vehicles will also be far more useful once you get to your destination. Something like forestry or mining will require lots of vehicles doing lots of tasks for things like transporting personnel, hauling materials, building roads, etc. Even if your giant vehicle is capable of doing everything, it can only be in one place in one time, unless it's Voltron. A fleet of small vehicles could simultaneously build houses, mine for gold in them hills, and report back to civilization.
Small vehicles will also be far cheaper to obtain. They already exist, and production lines to build them are already in place. Even rugged, expedition-type vehicles are being produced in large numbers in the modern day. At worst, refitting these vehicles for increased range, or to run on RNG-based electric energy, would require minor refits of existing vehicles, rather than construction of something completely new. It would be significantly cheaper.
**You should also build lots of outposts.**
Your convoy will also work best if you don't send it blindly on a one-way mission into the unknown without support. Many exploratory missions in the past have been aided by the creation of a series of outposts or supply dumps along the way. Food for the return trip, for example, doesn't need to be carried for the whole journey if it will only be eaten during the last week before your convoy gets back. Likewise, repair parts and fuel will generally be consumed at a steady rate, so parts for the return journey would best be left at outposts.
With sufficient personnel, the best way to handle your outpost would not be as lonely supply dumps, but as full fledged towns left along the way. Repair facilities, food storage, medical facilities, and the like could all be constructed at an outpost, which will serve not only as a one time source of supplies, but as a stopping point for future missions out into the unknown. The construction of hardened roads between these outposts will reduce the costs of future trips, and make resupply easier, as will railroad construction.
The goal of your company, after all, is to extract resources, not just to go on a single mission. A fleet of a thousand trucks may be the best way to rapidly explore and stake a claim on a distant ore deposit, but some serious infrastructure will be required to extract all of that ore and ship it back to civilization.
**How far could outposts stretch?**
The distance between the outposts will depend on how heavily traveled the route will be, and what the primary travel method between the outposts is. If it's seldom traveled, with only a few vehicles coming through every week or month, probably about a day apart, since outpost commerce won't be self-sustaining, and the company maintaining the road will have to pay for them. If there's a constant stream of trucks, probably a couple hours apart, like driving in the American west, since there would be enough commerce to sustain them.
On the other hand, if trains are the primary means of transporting people and goods, they might be a few days apart by train regardless of how much traffic there is, since it's harder to stop a train and less need to do so, since conductors can rotate shifts and there's usually space for passengers to eat and sleep without disembarking. With aircraft, large outposts could be thousands of miles apart, though these would likely be connected by widely spaced outposts on emergency roads, as well. A chain of outposts will stretch out until the cost of getting the goods back to society exceeds what they can be sold for. One thing to keep in mind, though, is that if fuel is not harvested locally, fuel costs will increase exponentially with distance, since fuel will be required to transport more fuel to distance outposts.
[Answer]
If you are moving an entire civilization, you'd need a large infrastructure in place when you get there. That would mean your vehicle needs to be some large monstrous thing that is literally moving a city (or can unpack into a small settlement at least).
It is more likely that as modern humans, we would send rovers out first to scout and report back. Since the sun still works, they can be solar powered and would be small -- their purpose would be to map resources/terrain and find a place for this new settlement.
If you are just exploring with humans instead of rovers, then the vehicles would need to be small and relatively agile; they have no idea where they are going to end up and need to be able to make it through terrain without pre-built roads.
The likely scenario is that you would have all three things. You will have rovers that find the destination and the best route to get there. Then you send out the construction crews to build the road to the promised land. And finally, the big monstrous settlement-in-a-can would be able to take said road to their new home, set everything up, and provide all the people.
This would be the process, and settlements would leapfrog to infinity as resources run out or enough enterprising people get together and decide their current situation needs a little spice.
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Could a modern society build a dragon? The society has similar funds to the U.S.A and the dragon must be fully working, made without any form of non-existent technology. The dragon must also fulfil the following criteria.
* Large (Anything heavier than an elephant will do.)
* Serpentine shape.
* Beautiful coloured scales which must be very hard, able to deflect small arms fire.
* Able to breath fire without being damaged.
* Able to fly, must use wings as some part of their flight. I will accept jets or lighter than air flight with wings for steering.
* Able to walk.
* Must look impressive to impress potential enemies and friends.
**Edit** Some clarification.
The dragon must be mechanical but it does not need to be an AI, it can be controlled by humans through a computer at the central base.
[Answer]
**Yes, modern society could make a dragon to the specs listed but with some really ugly trade-offs.**
If you want a flying war machine that breathes fire and comes heavily armored, then have your dragon be an A-10 Warthog. However, the A-10 isn't serpentine and can't walk.
* Large (Anything over 7000kg will do): Easy. Most heavier than air light combat aircraft are either in this range or slightly above it. With the inclusion of legs for walking, total weight will easily be over the limit.
* Serpentine shape: No problem here either though if the plane moves in a serpentine fashion on the ground or in flight, the complexity of this aircraft quickly becomes unmanageable.
* Beautiful coloured scales which must be very hard, able to deflect small arms fire: Easy. A steel or titanium skin painted to look like scales or actually scales. The latter option is a maintenance nightmare with so many individual parts and fasteners
* Able to breath fire without being damaged: Easy. Flamethrowers have been around for the better part of a century.
* Able to fly using wings: Easy. Humanity has over 100 years of flying experience on aircraft that weigh little more than a human to the gargantuan [Antonov AN-124](https://en.wikipedia.org/wiki/Antonov_An-124_Ruslan). Note though, this is only with fixed wing or rotary wing aircraft. We don't know how to build an aircraft that flaps its wings to fly. We have neither the power source, nor sufficiently strong actuators to make this work.
* Able to walk: Can be done but this imposes huge penalties on the rest of the airframe. Once the dragon is airborne, the legs and some/all the systems to make the legs work become deadweight. If this dragon has to perform air combat against conventional aircraft, it will be at a severe disadvantage. The heaviest sauropods topped out at 27-37 tons. The vast majority of their mass was dedicated to supporting their mass with legs shaped like giant columns...definitely not airworthy. Perhaps, walking would work for a very small dragon but that fails the >7000kg test.
* Must look impressive to impress potential enemies and friends: Beauty is in the eye of the beholder though I suppose that if all these design challenges can be overcome, whatever it looks like will be damn impressive to anyone who sees it.
So, yes. It's possible to build a mechanical dragon but the results are less useful than a conventional fixed wing or rotary wing aircraft.
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I reckon it could be done. Use synthetic diamond or sapphire for the scales. They're very hard, can be doped with trace elements for colour. Couple of jet engines for flying and a flamethrower at the front. Hard to make it smooth or flexible.
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Another idead Would be to take a dragon kite and enhance it to a mini blimp almost like the macys day parade character, however, unlike that character you would have a me hanism remotely controlling the amount of air/helium in it. The wings would need to have fans attached and you would need to be able to control the direction of the fans up down left right. The fans would need to be small lightwight and powerful to allow for gliding and maybe shut off and turned back on again.
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**Closed**. This question needs to be more [focused](/help/closed-questions). It is not currently accepting answers.
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**Want to improve this question?** Update the question so it focuses on one problem only by [editing this post](/posts/35367/edit).
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Suppose that due to unobtanium instability one wakes up tomorrow to realise that one is the only person left alive. Every other life form except for humans is left intact. Let's assume that all devices that would need constant supervision had failsafes that worked and shut everything down gracefully. Let's assume that one has general knowledge, some common sense and access to libraries and is in mid twenties with normal level of physical fitness. What one would need to ensure one's survival for the longest possible period after which sudden intervention of handwavium will gracefully bring everyone back?
Basically there are three questions:
1. What is worth the effort knowing that any serious injury could be game over? Building electrical generator? Keeping a vehicle running? Maintaining a house?
2. What resources should be cared for in the first place assuming that I live in a city?
3. What, if anything, I should learn?
[Answer]
**Drink water, eat food, don't get hurt.**
It's shockingly easy to stay alive without aid from other people when a human reaches adulthood. Humans have done an excellent job of taming the world. There are not a whole lot of seriously dangerous places (except for the humans living there).
If they're the only person left and there are no new dangers, they can simply set themselves up in or near a grocery store and eat non-perishable goods for years to come. If they run out of food or bottled water in one store they can simply go to another one. Canned food [can be safe to eat for decades](http://www.npr.org/sections/thesalt/2012/12/26/167819082/dont-fear-that-expired-food). In that time they can easily find alternate food sources through gardening or scavenging longer lasting packaged food (rice can last more than 30 years).
They can even go down to the local library or bookstore and start reading about various survival techniques, refresh on calculus, or read trashy romance novels out loud for fun.
They are likely to have a more comfortable life than a majority of humans that have ever existed.
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To answer you specific questions:
>
> What is worth the effort knowing that any serious injury could be game
> over? Building electrical generator? Keeping a vehicle running?
> Maintaining a house?
>
>
>
See below for what to learn. You don't need to build a generator, just scavenge a new one if the first one you find breaks. There will be a lot of them around. A similar idea for a vehicle, you'll only need one for the first few years to bring large supplies back to your home base, store a few small mopeds and vehicles indoors for later excursions. You don't need to maintain a house, just live on the main floor of a modern skyscraper. It's not going to collapse anytime soon and should remain in a decent state for many decades.
>
> What resources should be cared for in the first place assuming that I
> live in a city?
>
>
>
Food, fuel, hunting supplies, and clean water.
>
> What, if anything, I should learn?
>
>
>
How to hunt and preserve the meat, how to grow your own food, and how to treat wounds and illness.
[Answer]
**Severe isolation.**
The effect it has on the mind is huge. In fact, it's so bad that it causes physical problems in the person who's isolated, such as higher blood pressure, confusion, higher rates of dementia, and even inflammation/hormonal changes due to an immune response.
People need to socially interact and have a sense of belonging. It's third on the list of needs on [Maslow's hierarchy of needs](https://en.wikipedia.org/wiki/Maslow's_hierarchy_of_needs), and we can observe the mental effects of it even now in certain prison inmates or people who are victims of circumstance or scientific study.
Just a few of the problems:
* Confusion, disorientation, and a decrease in logical reasoning.
* Loss of a sense of time.
* Severe hallucinations.
* Severe anxiety, distress, and paranoia.
When you have to survive, these problems would interfere greatly. How can you feed yourself or tend to a wound when you are hallucinating and can't make proper decisions?
In the movie I Am Legend, Will Smith's character resolves this problem by setting up mannequins in the grocery stores and around the city. He created names, identities, and even social stories to share with them, as if his city continued to live and breathe normally.
You could do something similar to that, start writing to yourself, or find an animal that you can talk to. Keep dogs and cats around so you can ensure that your social interaction continues. In fact, setting up a shelter that accommodates a healthy number of pets would be one of my first priorities, so that the isolation doesn't get to me and get in the way of taking care of myself over time.
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He can live relatively well at least until he begin to have some
health problems, which can be couple or more of decades. Assuming that everything can be maintained in working state, in various way, he can use basically every modern item he already use every day.
The big problem can be the medicinal. They normally last for some years, if stored properly, but I doubt they can last for more then a decade. But generally everything related to the healt can be a problem: just imagine he had a bad tooth: he need a dentist that is no more present (ok, there is some other ways to handle the problem ;-) )
The food and water are relatively easy to get: as other already said, he has a large supply of canned food, that can last between 2 to 4 years. Honey in glass jars last for some centuries. He had also the possibility to eat fresh food, since all the other life forms are still here, he can breed some domestic animal (cows, rabbits, hens) and use them for food.
He still have access to a large number of books, comics, DVD, Bluray and so on, so I think he can hang out pretty well.
Clothing and equipment are not a problem, just enter a Walmart and you are done.
The big problem is how it reacts psychologically to the fact to be the last one and if he can cope to this without losing sanity.
**Edit to handle the clarification**
Nothing is worth the risk of a serious injury: the generator stop to work ? Just get another one. Same thing for houses, vehicles and so on.
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Yes, no one, only bacteria and with luck.
Let's suppose that:
* It is a fantasy world;
* The creatures live in a dormant volcanoes zone;
* The neighbors volcanoes are about 5 km and they are still active;
* Their power supply is the heat.
**How could be their anatomy?**
[Answer]
Yes.
In fact they already do, even without a fantasy element. There are any number of [extremophiles](https://en.wikipedia.org/wiki/Extremophile) that live in high temperature environments (which volcanoes tend to be). There are also extremophiles that live in highly acidic or basic environments. Then we've got some of the more exotic bacteria and plants that live in the dark and feed off volcanic vent activity at the bottom of the sea.
Now: Most of these tend to be simple lifeforms, and they all like having water around (though some of them don't seem to care if it's so acidic it can eat metal). Either your volcanoes get regularly rained on and the environment is very humid, you're next to the sea, or the volcanoes interact with a subterranean aquifer of some kind. Slimes and gels are the order of the day. Oh yeah..
Since you're in a fantasy environment we can expand the criteria a bit. Sentient, acidic slimes can be quite the hazard. Nests of burrowing worms that eat silicates aren't out of the question (and are horrible if they fall on your head). Plantlife (of a sort. Probably best not to try eat them) can exist, using heat to bind resources leached from the rocks using acid distilled from the vapours in the air. If you want to you can build a whole ecosystem based around hot, acidic creatures. They will suffer from hypothermia if you move them far from their natural habitat though, and though they might be able to eat us I doubt we'd have the right PH to make a tasty snack.
Unless you're willing to dive very deep into the realm of fantasy you can't have things living in the lava. While you might conceivably be able to handwave heat resistance into them, anything that sinks in lava is going to have to be denser than the molten rock it's living in, which means either your lava-dwellers actually float on the surface or they take years to sink/emerge, and they've got to be ungodly strong. While lava looks like it flows easily, it actually doesn't. It's still as dense as granite and has a tendency to freeze around cooler things that get put into it.
Bring on the Flaming Jesus Lizards.
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The lowest level of the food chain would probably some type of fungi or or maybe even some plants that manage to grow in the less volcanic parts of the planet ( perhaps above some sort of underground stream) like some kind of Oasis or something. Even the Sahara there are places where plants grow. If this planet didn't have any then maybe some type of fungi good makeup the lower level of the food chain smaller animals would eat the fungi and they would be eaten by bigger animals who in turn to be eaten by bigger animals. The creatures on this planet are most likely be cold blooded. After all there's no need hold heat inside of your body if the entire planet is boiling. Depending on the amount of lava you might see lizards with wings or maybe some sort of special fireproof feet that allowed them to walk a short distance across lava.
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Well, they could be just about anything, but make it heat resistant. Dragons with fireproof scales that can support molten stone, lava crabs, NO PLANTS, pretty much anything. Probably some kind of fireproof reptile, fish, or amphibian that can stand the weight of molten rock. And won't burn.
These creatures would probably die in cooler temperatures, though. I mean, they're used to living around molten rock and fire. Ice probably doesn't agree with them.
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Let's pretend that somewhere around our current time there exists a secret superweapon that kills humans nearly instantly but doesn't cause significant damage to structures or nature (flora and fauna). And it is used globally. At the same time, there is a secret defense initiative that installed shields in major cities. Let's say, the cities with population of 2+ million people. In Europe these are Istanbul, Moscow, London, St.Petersburg, Berlin, Madrid, Rome, Kiev and Paris.
So, everybody outside these cities die. What will happen with the city folks? Will they die of hunger, because they lose agricultural import from rural areas? Or do they have the capacity to restore the food supply? Or maybe even create food supply within the city? And will they be able to spread their population to the empty lands (there is no radiation, just damaged structures and wilderness) or will they become closed city states?
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**The biggest problem would be the potential societal/governmental breakdown this could cause.** For example, [many capital cities](https://en.wikipedia.org/wiki/List_of_national_capitals_by_population) have less than 2 million population. The destruction of much of the world's government would most likely be catastrophic and lead to unrest in which nothing (including agricultural production) was working properly. This would, indeed, likely lead to starvation, as well as death for reasons such as war. Only a fraction of the population would survive.
However, **anywhere that reasonable institutional stability remained, it would probably be possible to avoid significant starvation**.
Consider the following facts:
**The world population (and therefore its food requirement) has just dropped dramatically, lowering the food requirement.** The world is [about 50% urbanized](https://en.wikipedia.org/wiki/Urbanization), but a much smaller portion live in cities over 2 million people. Based on [this list](https://en.wikipedia.org/wiki/List_of_cities_proper_by_population), I would guess this would leave a population of perhaps 1-1.5 billion.
**There is a fairly large supply of existing food,** from cans on supermarket shelves to strategic grain reserves to livestock that can be slaughtered and eaten. It is hard to estimate this, but I would expect the population to be able to survive for a few months on existing food. This would allow agricultural operations to resume.
**Getting farms back operational would be a significant, but solvable problem.** There will be some people with farm experience in the cities, though not enough to operate very many farms. It would be necessary to train people to get things operating as quickly as possible.
Expertise is certainly needed to run a farm, but much of the actual labor involved is fairly simple and could be learned quickly. A system could probably be devised where the top experts travel between farms and give high-level advice, while those with more limited experience train others how to do things like operate equipment.
There certainly would be major losses in productivity, for several reasons:
* A gap of even a few weeks where a farm is unattended would damage some crops.
* Some farms would be mismanaged due to the lack of expertise.
* The supporting infrastructure for farms (e.g. tractor repair, fertilizer supply, etc.) is probably largely rural and may be harder to replace.
* Other, more general infrastructure, like fuel supplies, would be hard hit as well.
However, given that the food yield only has to support less than a quarter of the previous population, I don't think these problems would be big enough to cause starvation.
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If people and governments understand what is going on, and that it is now safe to go out again, the food problem could be solved. Sure, there would be widespread economic disruption and a drop in the standards of living, but it will be the confusion that kills the survivors.
* There will be enough underemployed people in the urban areas to become a sufficient farm workforce for the (now reduced) population.
* There will be enough former and current farmers in those urban areas to serve as teachers and foremen.
* Saving the animals will be a question of days or hours. A modern [dairy cow](https://en.wikipedia.org/wiki/Dairy_cattle#Animal_welfare) won't survive long without human care. There is enough livestock within one day of travel to serve as breeding stock. Perhaps the meat consumption will go down for a time, but that is healthy anyway.
* Saving the crops will be a question of weeks or months. You said the hardware survived. So what if the new driver for a combine harvester runs over half the crops, there are enough planted fields.
The impossibility will be understanding and organizing. Will the urban people believe that it is now safe (and urgent) to go out? Can farmers and helpers be dispatched to the big commercial farms before the animals die?
Similar considerations will apply to energy (rush people to the nuclear power plants, get enough people to the coal mines to keep the pumps going and restore operation later), transportation (save river barges and ships currently in port for future use), communications (maintain undersea cables).
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**They will all die.**
Well. Not all of them. But almost.
While farming is not rocket science, it still takes some skill, and more than you can learn from books in a few weeks.
So, while those that are quicker on the uptake will try to save what farms they can get hold of, a large part of the population will kill each other trying to claim what food and other resources can be found in supermarkets.
In the mean time, cows need to be milked, chicken need to be fed, and so on.
With noone caring for the livestock, a lot of the farm animals will die pretty quickly.
So, a lot depends on wether the first harvest will be lost completely, or if part of it can be brought in.
Practically every bit of infrastructure will collapse quite fast. For example: A lot of the big power plants are not in city centers, so their personnel will be hit by the weapon.
Can you train new personnel fast enough to prevent neglect rendering them useless, or even dangerous?
The big refineries will share that same fate.
So, to round it up: Those people who don't die in the anarchy and looting will have to re-establish agriculture and what infrastructure can be saved, losing large parts of what we are accustomed to, like fuel for cars(described above), health care (you need medicine, requiring processing of raw materials), energy and heating (described above), food distribution.
The cities will quickly turn into mostly empty heaps of rotting corpses, while a very small part of the original population will live off whatever agriculture they could grasp quickly, without the help of diesel engines and mostly without electricity.
Not a bright future at all.
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The biggest hazard here is actually fear, fear of whatever wiped out people the first time around. Who is going to leave the safe and shielded city to go out to the farms and provide food? Can people prove to them that it won't happen again?
There's a lot of infrastructure outside of cities. Power generation, factories, waste water treatment, to name just a few. Even if your generators are still working and still inside the city you need fuel for them. Your water supply almost certainly gets piped in from outside.
You can expect martial law, poverty, riots and hardship. I would expect the majority of people to survive, but it will be a lot fewer than the original 20% of the worlds population that survived the initial catastrophe.
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As seen on this graph of the world population in 2015, around 20% of the total world population lives in city's lager than 2 million people. That comes down to 7.398.158.900 \* 0.2 = 1479631780 people. Considering this and the fact that most ( if not all ) world leaders also live in these city's i'm quite sure they will do just fine.
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In my story, humanity has wiped itself off earth (salted nukes, to be precise) and survives as a large remnant civilization in the asteroid belt, with small bases on the moon and possible mars.
As the plot begins, my main character is a self employed ship owner who scavenges the remains of satellites around earth looking for microprocessors, which are one of the only things that her civilization still cannot produce. Because a processor is needed for every ship, several for a colony or for a factory, they are incredibly valuable. Ideally, one successful find can fund refuelling her ship, and supplies and rations that would last her months.
Is it plausible that a spacebound civilization, that produces rocket engines, life support equipment, tube radios, and large space stations, would be incapable of producing microprocessors, and so would pay the equivalent of millions of dollars for each scavenged unit? Would the radiation environment in space make producing computers more difficult than it is on earth?
Going off the answers to [this question about recreating a computer in ancient times](https://worldbuilding.stackexchange.com/questions/6747/a-small-group-recreating-modern-technology) , building a computer is incredibly hard. My space civilization necessarily has pretty good material science and manufacturing capabilities to even survive, but I don't know if it could devote the thousands of people needed to set up a photo-lithography plant. In addition, the existence of expensive but very powerful scavenged cpus should discourage efforts to make new computers unless they can be mass produced, since a million dollar hand-made computer capable of ten megahertz can be replaced by buying access to one thouandth of the processor time of your settlement's i7 based mainframe.
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As a bit of a tangent, if the technological base is too small or narrow to recreate computer chips and microprocessors from scratch, then some sort of alternative will be created to fill the gap.
If we consider that "computer" was a job description at one time, your space going civilization could quite literally go back to having rows of trained mathematicians sitting at desks to work out calculations. If you consider that "computers" worked for financial institutions, insurance companies, the military (creating ballistic tables, for example) and engineering firms, they you would not be surprised to discover that the United States had a huge pool of computers available to support the war effort and especially the Manhattan Project during the 1940's.
Using humans as computers is time consuming and resource intensive, so alternatives will be sought. Mechanical computers have been possible since the Babbage Machine in the 1800's, and indeed the Antikythera mechanism is considered to be a form of analogue mechanical computer.
We can carry on with vacuum tubes and other electromechanical devices, but you get the idea.
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It seems unlikely that they’d be incapable of producing microprocessors at that scientific level, but if they were unable to replicate the precise interface and specifications of old Earth chips, there would still be a value and necessity to scavenging.
A nuclear apocalypse extensive enough to force humanity off of Earth sounds severe enough that knowledge loss could happen to the collective human species. If the surviving humans lacked the collective knowledge to replicate the super-advanced microprocessors that their remaining technology relied upon, scavenging would be critically important to continue operating old-Earth technology. Even with an old microprocessor in hand, reverse engineering a black box (and its internal black boxes) without documentation is a substantial challenge.
But beware: an industry to manufacture these chips will exist eventually. In addition to the potential profit due to their value, it’s clearly a matter of survival for the species. Not only are there a finite number of scavengable chips out there, but eventually age and the harsh environment of space is likely to render the entire lot useless for your needs. When that day comes, you better hope someone figured out an alternative.
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Yes. From the [Wiki page on Radiation Hardening](https://en.wikipedia.org/wiki/Radiation_hardening);
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So, take all the difficulties of creating microprocessors, crank it up to 11 with the necessity of making them radiation hardened, and try to accomplish that task in space with high levels of cosmic background radiation. Very, very difficult. I like Thucydides' point that a "computer" used to be "one who computes," and that this spacefaring civilization might have to largely rely on manual computing. And yes, the cost of providing for hundreds of mathematicians is incredibly high. With humanity living in places with little natural protection from cosmic background radiation, a radiation-hardened chip that could replace hundreds of skilled mathematicians would absolutely be a treasure.
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The situation: A planet largely composed of water, with land masses being island chains scattered planet-wide. At all times there is precipitation of some sort, whether it be snow or rain based on regional climate. At times it can be light, and other times it can be extremely severe, but the average tends toward what would be considered a "steady" amount like that of a "typical" storm, not dangerous but certainly enough to have an effect on many facets of life. We'll assume that, as the planet has been like this, the water cycle is stable and therefore there's no concern of rising water levels encroaching on limited land resources.
The question: How would a population of human or humanesque people most likely adapt/overcome this sort of situation, and what would most likely be their biggest choke-point in doing so (i.e. resources, manpower, etc, assuming there is such a choke-point in your solution).
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## This is one lousy planet for humanoids.
I think we need determine how can you get continuous precipitation on an earth-like planet. Clearly you need a lot of water entering the atmosphere in its water cycle. So, hot oceans are required.
Next, you need air capable of carrying lots of moisture. Air can contain over 10 times as much water at 40 C as is does at 0 C, so again, hot atmosphere. You also need cool upper air to squeeze out the moisture in the air as well as dust particles to encourage droplet formation.
Though you have mentioned mostly oceans, some island chains instead of land masses, this is an absolute requirement, as any significant land masses would likely result in at least occasional gaps of rain.
So, steamy, jungle-like conditions, on steroids. Snow is not generally compatible with such an environment, so no cold polar regions. High mountains could get snow, but are bad because the air uplift squeezes out to much water, leaving desert conditions on the leeward side. So, snow should be very rare on your world.
How do you manage to have all the necessary conditions simultaneously? Because of the continuous rain, you have continuous down-draft that bring lower temperatures down to the surface with the rain. If you make the solar flux very large to compensate, you get much thicker cloud layers reflecting the sun and I believe kill off the temperature driven atmospheric uplift required. The continuous downdraft from the rain contraindicates the thermal uplift required to cause the rain in the first place too.
The only way I can envision making this world is to make the oceans hot due to very large heat movement coming from the core, making the oceans hot compared to the upper atmosphere at all times. So in addition to the rain, you necessarily will have high vulcanism and earthquakes. I think that constant rain is like impossible even under these conditions.
Earth style photosynthesis will be torturous at best due to the thick cloud deck reducing available light, so you need a brighter sun, but not too bright. So marginal plant growth at best. Soil erosion is going to be an awful problem too.
**Food sources will be very limited, probably impossible to support a large and varied biome like Earth. Much worse than you might otherwise expect.**
Thick clouds, constant rain, earthquakes and volcanoes and the food is not very good either. This place is going to have lousy tourism; so there is little hope of bringing in off-planet resources that way either.
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Forgot one important thing, tsunamis - lots of them. Those are really bad for small islands in the middle of deep water. Most people remember the 2 largest tsunamis of the 21st century, the Christmas 2006 tsunami (Dec 26) in Sumatra and the northern Japan tsunami that triggered the Fukushima meltdown in 2011 (Mar 11).
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Food would be an obvious one, where plants would need to be able to grow in low light levels. Precipitation means clouds, which means lower solar energy reaching the ground.
This isn't really a problem since any plants developing there are going to be adapted to the environment.
Most earth based plants are going to have a problem growing in overly wet, constant low light conditions.
Next is industry. Metal and water react to each other, causing corrosion. Electricity and fire both get along poorly with water.
A technological system like earth developed is going to have a hard time of it. But they could still have something. Biotech though selective breeding would still be doable, which could develop into a lot of areas.
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Okay, so a kingdom has this rule: Whoever is the oldest person who was the son of a previous king is the king. This mostly passes the throne between brothers and cousins. My question is, how do you prevent them from killing each other?
Here are the problems:
* If your dad is close to becoming king, but will likely die before so, you, your brothers, your sons, and your nephews all want to kill the current king. (If your dad dies before becoming a king, you can never become a king.)
* If you someone is about to become king, and his kids are a little older than you, you want to kill him before he becomes king (along with anyone else in your position, and your descendants).
* If you do not like a certain branch of the royal family (like, say, if you're the king and they are trying to kill you), you have an incentive to kill the patriarch (common living male ancestor) of it. Sure, they may want revenge, but any designs on becoming the king they had is now lost, and they lose a whole lot of political power.
* If the king and the next in line die around the same time (say in the same battle), it will be up to debate whether that guy was king before he died or not. This will lead to divisions in the kingdom.
* If record keeping for births is not good, it might not be clear who two people are older (you do not have to just track the king's sons, but also the sons (and their sons) of any previous king.)
* The problem is fractal in nature. All of the above applies at all levels.
This is ripe for backstabbing and killing and stuff. Although it will probably be fun, how do you lessen that?
Note: Although you would have a large pool of potential kings, it wouldn't grow out of control. When you get a large enough group of potential kings, they will be closer in age (due to pigeon hole principle), and when a king lives longer than average, a lot of the kings close to him will die before becoming kings. The effect is larger the larger the pool gets, so its self limiting (and also makes the system select for longer lived kings). Also, the backstabbing helps thin the pool (which in turns selects for backstabbier kings).
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To control bloodshed, you must decrease the desirability of the crown to those who are in line to receive it.
You can do this in two ways.
* Make the King's life shorter and less enjoyable.
* Make the lives of those waiting to be King more enjoyable and filled with privledges.
Add a rule that no King may wear the crown for more than ten years and that every King must die painfully on the tenth anniversary of their inauguration.
Add another rule that the King must lead every army into battle from the front line, and must therefore train for long hours every day as a warrior.
Grant unlimited privledge to ALL of the heirs, giving them the best clothes and food, their choice of the best concubines and freeing them from any battle duties or training. Let them live in lavish luxury and in silent terror of the day when they must become king.
Set all these rules in stone so that no future king may change any of them.
You will have the King's heirs all carrying first aid kits rather than swords, when they visit their older siblings.
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Political alliances, sharing of power, bestowing privileges, wealth, and domains on your family members.
That's what the English kings did, though it didn't help them much. In the end you get Magna Carta/Democracy.
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Don't explicitly try to prevent it, but engineer the social constructs of your world such that it's a really bad idea. This is easiest to achieve with a close knit caste of nobles, who all have excellent spy networks and some major Machiavellian mojo.
Some examples: I kill the king and get caught. This is regicide, a crime for which I will be publicly tortured before being hung, drawn and quartered.
I kill someone in line to being the king and get caught: This is a crime for which I will be publicly tortured before being hung, drawn and quartered.
If I kill someone in line to the king in secret, the court of all the nobles will undoubtedly pin me down through their excellent web of informants, spies and double dealers, leading to me being eliminated as competition (as I'll be publicly tortured before being hung, drawn and quartered).
In this kind of scenario, where everyone is double dealing and politically backstabbing each other, actual backstabbing (although tempting) becomes too risky as everyone is watching everyone like a hawk and everyone has their own agenda. If there is even a smidgen of proof that you're conspiring to kill a member of the Royal Line, you end up publicly tortured before being hung, drawn and quartered, so you'd best make sure that there is nothing to prove.
On the other hand: If everyone in the close knit inner circle agrees that the king is an idiot, and the next in line is an idiot, and they should both die, then the people at the top may well be deposed by common agreement (by being publicly tortured before being hung, drawn and quartered).
It also leads to an excellent narrative structure, with story hooks ranging from adventure themed all the way down to medieval murder mystery and intrigue. With a health side order of public torture before hanging, drawing and quartering.
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Make it almost as desirable to be a prince in the line of succession as it is to be a king, but much less risk and hard work.
* Regular revenues which are granted as a birthright of the prince, not as a gift of the king.
* Same for honors and titles.
The problem with that is the number of unproductive nobles. Could you make them administrators? Officers?
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## Being a king is too hard
If in your world being the king mean have too much responsibilities maybe just a few nobles will want to become king . Like if your kingdom is passing through the financial crisis and the current king is facing a lot of pressure and you as a noble just have to worry about your own problems, you wont want to get more problems for yourself .
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**This question already has answers here**:
[What if the attack on Pearl Harbor had been defeated in World War 2?](/questions/17383/what-if-the-attack-on-pearl-harbor-had-been-defeated-in-world-war-2)
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Closed 8 years ago.
Conspiracy theorists discuss Pearl Harbor all the time, implying it was planned as an excuse for the war or that we knew it was coming. Well, let's say that we *did* discover it in time and were able to stop Pearl Harbor from happening by moving our forces out to be ready to defend it. Japan saw the redeploy, figured that Pearl Harbor wasn't the easy victory they were looking for, and decided to have their fleet sail on past, pretending the fleet was always headed somewhere else and was never intended to attack Pearl Harbor. No major incident happened, no shots fired, and no proof that any attack was every going to happen.
How would this affect WW2? In particular how would it draw out the war or affect how it would end?
One obvious relevant question to this would be whether or not the US would join the war at all or sit the entire thing out. You're welcome to hypothesize either that the US never joined or that it does so at some later date. I'm mostly interested in the final outcome of the war regardless of US involvement, but obviously addressing the later US war efforts may influence the final answer somewhat.
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If the fleet sailed to Pearl Harbor than the Japanese admiral would have attacked. To avoid Pearl Harbor Japan would need an oil source. Either the U.S. does not start an oil embargo on Japan or Japan decides to focus on taking away Russian oil fields instead of Pacific/U.S. oil fields.
1. U.S. continues to sell oil. U.S. avoids any entry into the war. Japan mostly ignores Russia and keeps expanding in China and occupying the Dutch East Indies and British and French colonies. USSR eventually defeats Germany. But it takes longer. Most of Europe becomes socialist/communist but never reclaims its colonies from Japan. Three Super Powers emerge. USSR, Imperial Japan, and the U.S. The U.S. might be the least of these. After seeing the loss of life by others in WW II might even reinforce its pacifistic nature.
2. U.S. cuts off oil and Japan focuses on Russia. Russian troops are better equipped than the Japanese. The Japanese suffer disproportionate losses and only make gradual gains with much loss of life. Their continual pressure forces Russia to keep troops in the east though. Valuable reinforcements are missing at key battles. Russia loses Stalingrad and the Caucasus. Their military machine is crippled without the extra oil. The Japanese focus on Russia eventually allows them to make headway and gain the Eastern oil fields as well. Russia is unlikely to surrender and continues fighting for years. Eventually turning into a guerilla war and terrorist strikes. The Axis powers win. However terrorism and separatist movements are likely to cause unrest for decades to come. Unless more mass genocides wipe them out. This rout makes it more likely the U.S. would enter the war. But they might only declare war on Germany. Without the galvanization of the Japanese sneak attack the sleeping bear of the U.S. economy might never awaken and it might be to little help to late. The U.S. would probably make peace once its allies were out of the war. But they would continue to foster the unrest and be a strong super power against the German and Japanese super powers.
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The loss of Pearl Harbor substantially crippled the US's naval forces. If we were able to know about--and therefore stop--the bombing, the war would have ended much more quickly and possibly without needing the Manhattan Project. The US would have had its full Pacific fleet with which to pressure Japan, vastly quickening the end of the war on that front. I suspect that the atomic bomb would still need to be used in order to cause Japan to surrender, as I don't think that the increased naval capacity would change much, but there's the slight possibility.
I don't recall if any of the Atlantic fleet was re-positioned to the Pacific theater due to the loss of Pearl Harbor, but if any ships were reassigned (I suspect at least a few were), then in this alternate timeline, those units would have been available to maintain their original orders.
Long story short, the war would have ended much more quickly, leading to all kinds of side effects, such as prisoners in concentration camps who died having survived (as the timeline moved up, causing the prison closure now being at a point in time prior to their execution), so it would be worth looking into any famous individuals who died in the final weeks of the war. Even just mentioning a name or two would be a neat little easter egg for those that recognize it, such as [Kurt Gerron](https://en.wikipedia.org/wiki/Kurt_Gerron), even if it isn't relevant to the plot.
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I'm not sure if the scenario you paint could have happened. Japan felt it needed to knock the United States out of contention in the Pacific in order to break the embargo and secure sources of raw materials and labour for the Co Prosperity Sphere and the Empire. Even if the US fleet has steamed out of Pearl Harbour the Japanese may have felt compelled to attack, to deny the US the forward staging area and fleet base, essentially hoping the Pacific Fleet would have to steam back to the West Coast or die on the vine. (The Japanese were apparently unaware that the USN had been conducting experiments with fleet replenishment under weigh, and American Admirals were quite quick to suggest that this was the *real* key to the American victory in the Pacific).
Given the entire Japanese naval strategy rested on the idea that the US Navy was quickly knocked out of the war, and making the (unwarranted) assumption that American industry wold not be able to replace the fleet in any reasonable period of time, they might have chosen to attack the base and destroy the fuel and facilities based there, then steam on seeking to engage the US battle fleet before it could escape to safety.
The only way to avoid this branch of history would be to scroll back further into the 1930's where the Imperial Army and Imperial Navy were engaged in a power struggle over which direction the Empire should expand. The Imperial Army argued that taking Siberia would secure a rich resource base, secure from both attack and close enough to the home islands that transporting the materials would be easy and relatively safe. The Imperial Navy argued that the European Empires had already developed resources in SE Asia, and there was an existing pool of labour available to extract these resources for the Co Prosperity Sphere. The Imperial Army had the upper hand until they were defeated by the Russian Army at the Battles of Khalkhyn Gol, when the Naval faction gained ascendency and pursued their "southern" strategy.
If Stalin had managed to purge all of Marshal Mikhail Nikolayevich Tukhachevskii's mechanized warfare acolytes in 1937 (including Georgy Zhukov), then it is quite possible that the Russians would not have been able to defeat the Japanese 6th Army, and the Imperial Army's "northern" strategy would continue to have been implemented, avoiding the need for the risky Pearl Harbour gambit.
The United States could continue to press the issue of the embargo, but lacking a *Casus belli* would not have moved into war (the American public and the Congress were generally opposed to war, regardless of what Roosevelt thought, and only the dramatic action of an actual attack against American forces during a time of "peace" was enough to inflame American public opinion for a war). Imperial Japan would have been able to break the embargo with more and more materials extracted from China and eventually Siberia, while gradually drawing the nations of SE Asia into the Co Prosperity Sphere through economic enticements rather than conquest.
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Whales and dolphins surely do not have ears similar to ours and yet they can pick up ultrasound underwater without fear of water pressure damaging the eardrum. Any idea how the mermaids with ears like us can manage to overcome the water pressure when fully submerged while we need 2 pieces of ear plugs?
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Do mermaids have human ears? Or do they have something that is shaped like a human ear with their real ears elsewhere? Note that dolphins use their jawbones to funnel sound to their ears where we use the external portion of our ears for that.
Searching for information about how dolphins manage water pressure in their ears finds <http://dolphinworld.users.50megs.com/anatomy.html> which says:
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This would be internal to the ear. Even with external ears for hearing above water, something like this could exist inside mermaid ears. You wouldn't be able to tell without cutting the eardrum.
Note that dolphins lack an external ear not because of water pressure but to allow them to swim more easily. Perhaps mermaids maintain an external ear because their human-looking half spends more time out of water.
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I feel the need to point out that humans that swim on the surface sometimes wear earplugs, but nobody who wants to keep their hearing wears them while diving. We can hear perfectly fine underwater, in our normal range, as long as we equalize the pressure. Earplugs are for keeping water out of the ear canal, not for protecting against pressure; in fact, under pressure they become a danger.
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Mermaids could have their inner ear connected to the surrounding water by a thin canal, similar to a shark. This could be made even more human-appearing if the opening is inside the ear canal, with the rest of the ear canal simply being a blocked spiracle
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On an Earth-like planet, I'm imagining a bipedal sapient species whose juveniles have a largely hollow head so large that they can retract the whole body into the head when frightened, the way a turtle or snail can retract into its shell. They lose this ability when the rest of the body grows rapidly during puberty. Plausible?
Subpoints to consider:
* How big would the head have to be to allow this? My first guess is a round head roughly twice as big across as the height of the body below the collar bone. ([Compare](http://jdelgado.deviantart.com/art/The-Skeleton-of-Stan-Marsh-157923390))
* How would the body parts fit together to leave room in the head for the body? Consider how much attachment would be needed to hold up a head that big.
* How would such a child reach around himself for hygiene and dressing? Or would they be dependent throughout childhood on parents and parent-created tools?
* How does the plausibility change depending on the adult height of the creature? And would it be more plausible underwater with a dolphin tail than with land bipedalism? ([Compare](http://bubbleguppies.wikia.com/wiki/Gil))
* Finally, what in evolution would select for this ability? On the one hand, I know intelligent juveniles have to [stay small while still learning to conserve energy](https://worldbuilding.stackexchange.com/a/22902/601), so that might lead to the small body. On the other hand, the difficulty of giving birth would appear to put the brakes on evolving a large enough head.
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Have the children be a sort of snail or octopus, that can retreat by oozing its way into the shell. During puberty, the bones form/develop, blocking off this ability, or possibly the whole form hardens and is thus unretractable. A good question is whether or not this shell ever grow. Does it weaken and become more expandable as the brain gets bigger?
Another thought: perhaps these creatures lay really massive eggs that grow quickly and harden, but not before the attached baby breaks off the bottom part and grows out. If so, this structure could be rather large, maybe torso-size.
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With bones, the creatures would be very like us, but capable of holding a larger weight, thicker bones, etc. They would be skinny with double jointed limbs. To fit into the shell, they would simply curl into the fetal position. They would have to have eyeholes in the shell, or else some sort of tremorsense, to detect things. They would also have something on bottom, like my first example, something hard like shelled feet. This would be used as a sea snail uses its plug, and a hermit crab its large claw. Something protective from the bottom, and possibly equipped with a deterrent like claws.
On the other hand, more turtle-like, they would have to include stunted-looking pre-folded limbs, and rather stubby.
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So I've created this planet that's about 90% the size of Earth, orbits a binary yellow dwarf star and has an extremely electrified atmosphere. Cloud plumes coming from volcanoes contain various conducting compounds, resulting in huge lightning storms which occur almost every night globally.
This planet's equivalent to plants - phytids - use the electricity in much the same way that our own plants use light, in a process called electrosynthesis. My question is: what sort of biology would these phytids have that could allow them to convert electricity into energy for growth and reproduction?
They have long, rigid spires made mostly of copper-based proteins which face upwards into the air to conduct this electrical energy into their bodies, but that's about all I know. What would they need to do with the electricity once it was inside of them?
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Why would you 'produce energy' from electricity? IT IS ENERGY. Likely they would utilize as much as possible in it's native form. The human body uses electric impulses all to pass information back and forth throughout the body.
Adding in capacitors to hold this energy would be fairly important, it would be kind of like the fat cells in animals or sugars in plants. So plants and animals need energy to grow (and move). The growing is generally all chemical changes powered by chemical reactions from chemical energy sources. [Electrochemistry](https://en.wikipedia.org/wiki/Electrochemistry) would be huge in this planet.
I think a lot more plants and animals would be utilizing aluminum in their make up since with all the 'free' electricity it can be separated much easier from it compounds. 'Diets' of plants and animals might be significantly different when you can use electricity to break bonds instead of a chemical (acid) or physical (teeth or crop) to break things down to be useful for building ones own body.
Water can be broken down into Hydrogen and Oxygen with electricity and maybe some plants will store the two gases instead of a capacitor or in conjunction with them?
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The Asian Hornet converts sunlight into electricity, then appears to use it directly:
```
The sunlight that these hornets capture is likely converted into electrical
energy. There exists a voltage between the inner and outer layers of the
yellow stripe that increases in response to illumination. The harvested
energy may be used in physical activity (digging or flight) and temperature
regulation. It even seems to provide enough energy to carry out metabolic
functions similar to the liver (producing or filtering enzymes and sugars).
The enzymatic activity in these regions has been shown to decrease when the
hornet is exposed to light, allowing it to conserve its energy.
```
[Photovoltaic Asian Hornet](https://asknature.org/strategy/photovoltaic-pigments-harvest-solar-energy/#.WjVuBFWnFaQ)
While the Asian Hornet is unique, it doesn't seem to need any exotic materials to make use of the electricity, though I believe the process is not completely understood.
Since the hornet can use the electricity to produce sugars, I imagine similar organisms might get by with a sugar reserve to consume when electrical energy sources are scarce.
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So I'm approaching this question the wrong way. Instead of asking how long a road would last (which is apparently too broad for stackex), let me tell YOU how long I want it to last and you can tell ME under what conditions that would be reasonable.
I'm thinking I want a road that if looked upon would only reveal patches. Let's call it somewhere between 10-30% of the road remains. I would prefer if the road were previously cut through a heavily wooded, back-country area and over time the grass, leaves and trees have encroached (actually, the trees probably approach but don't encroach). Yearly temps range from low in the 30's in winter to highs in the 90's in summer. Average rainfall somewhere between 20 - 40 inches per year. The only wear comes from sun, wind, rain and infrequent snow.
Based on the above criteria would it be reasonable for such remains to exist after 100 years? 200? 250-300?
What parameters above would you change to MAKE such a road last 100 years? 200? 250+? (If this question is too broad for stackex, I'll withdraw it)
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I know of such a piece of road that was bypassed in the 1930s and not used other than as a footpath since then. Most still recognisably road. Vegetation encroaching over asphalt from sides but not yet meeting in middle. One stretch on a gradient completely washed away. This in English woodland, summer temperature rarely over 70F and winters generally mild but wet (40" annual rain) Hope this helps.
A lot will depend on how well a road was built to start with. I have walked on another path that was once a Roman road and in a few short stretches the Roman road is still identifiable. Many Roman roads were the best in the country 1500 years after they were built and many modern UK roads still rest on Roman foundations.
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I'm building a world that I would like to be quite realistic. One of the plot lines I've considered is plate tectonics that move at a rate of anywhere from 0.8 to 2.0 kilometers per year. This is in comparison to the Earth's rates of centimeters per year.
Would civilization be possible here? Obviously areas near fault zones would need constant maintenance to facilitate ground trade between them, and this would pose obvious dangers for any kind of mountainous peoples like dwarves or highlanders. But would it stop the rest of the world from developing life and civilization? What is the fastest tectonic drift that would be capable of supporting life, avoiding as much willingness to suspend rational thought as possible.
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**No...no it would not.** The energy created by that much tectonic motion would increase the ambient temperature of the planet significantly. Not only would civilization not develop but complex life (at least as we know it) would not exist.
The force created by a single 7.0 magnitude earthquake is somewhere around [199,000 tons of TNT](http://science.howstuffworks.com/environmental/energy/energy-hurricane-volcano-earthquake3.htm) 199,000 tons is 0.199 mega tons, which for reference lands you somewhere in-between [Tunguska](https://en.wikipedia.org/wiki/Tunguska_event) and modern nuclear weapons.
According to that article there are around 100 6.0 or greater earthquakes each and every year. If you were to increase the rate of movement to 2 km a year and linearly adjust that rate the number would go up to somewhere in the 10,000,000 range.
Its hard to say if that would work out in a linear fashion but either way that is a lot of energy and it wouldn't be the only sources either, volcanic eruptions would also be far more common, not to mention friction heat created by the plates moving.
Remember the Tunguska/Nuke note above...now imagine that is happening 10,000,000 times each year. Oh and it is worth mentioning that 10,000,000 nukes is **666 times the number of the global nuclear arsenal.**
The extra tectonic activity would also poison the atmosphere (if it had ever become breathable at all that is.)
This question of mine([A world with far more mobile continents?](https://worldbuilding.stackexchange.com/questions/19238/a-world-with-far-more-mobile-continents)) covers this topic, though without any particular rate in mind.
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**Sure.**
Let's say there is a location in the world that is 2,000 km from any fault lines; not a difficult situation to have. Further, assume a city can withstand a quake from fault lines that are at least 500 km away. There exists then a 1,000 km zone where cities can be built, and survive 500 to 1,250 years before they come within 500 km of the next fault zone. That's plenty of time for a city to grow and spread in an anti-driftward direction. Old cities are driftward, new cities are anti-driftward, with hundreds to over a thousand year for each to rise and fall.
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Hmm. I'm no scientist, but I think it might be problematic.
Truly advanced civilizations develop in many different ways: they gain knowledge, yes, but they also build impressive buildings in which this knowledge will be stored for the ages.
You're looking at a situation in which earthquakes would likely be a daily occurrence. The landscape itself might shift under such pressure, making building a city a dicey game. Throw in some volcanic activity to boot.
If people are so preoccupied with simply surviving, will they be able to really develop new technologies, and advance? Sure, but far more slowly.
And then, of course, what happens when two plates collide - especially at that speed? (which would happen within a couple of centuries) Complete devastation.
Here's another question for you: say two very large tectonic plates collide. What now? Do they keep moving? Do they combine? Are continents forming and breaking apart every couple of centuries, with species migrating across landmasses and the weather changing drastically?
In all honesty, I think any civilization would face some pretty nasty obstacles.
They might stand a better chance if their civilization had a chance to evolve, and only then did an event set the instability of the tectonic plates in motion.
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